3D printing vs traditional workflow for the fabrication of mandibular implant overdentures: Study protocol for a mixed-methods cross-over RCT

3D printing vs traditional workflow for the fabrication of mandibular implant overdentures: Study protocol for a mixed-methods cross-over RCT | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article 3D printing vs traditional workflow for the fabrication of mandibular implant overdentures: Study protocol for a mixed-methods cross-over RCT Dana Jafarpour, Nesma El-Amier, Jocelyne Feine, Christophe Bedos, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3873159/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 16 Apr, 2024 Read the published version in Trials → Version 1 posted 5 You are reading this latest preprint version Abstract Background Complete tooth loss is a significant global oral health issue, particularly impacting older individuals with lower socioeconomic status. Computer-assisted technologies enhance oral healthcare access by the elderly. Despite promising in vitro reports on digital denture materials, evidence from randomized clinical trials (RCTs) is lacking to verify their performance. This cross-over RCT will investigate whether 3D-printed implant-retained mandibular overdentures (IMO) are more satisfactory for edentulous seniors than those made through traditional methods. Methods/design: We will recruit 26 completely edentulous participants (any sex/gender) based on the following eligibility criteria: age ≥ 60 years, no tooth extraction in the past 12 months, two implants in the lower jaw, and need for new dentures in both jaws. Each participant will receive two denture pairs, either manufactured by 3D printing or traditionally, to be worn in a random order. A timeline of three months with each denture pair will be considered for outcome assessment (total: six months). Patient satisfaction with dentures will be measured by the McGill Denture Satisfaction Questionnaire. We will evaluate other patient-reported outcomes (including oral health-related quality of life), as well as clinician-assessed quality and cost. At the end of the trial, participants will choose which denture pair they wish to keep, and interviewed about their experiences with the 3D-printed IMO. The quantitative and qualitative data will be incorporated through an explanatory mixed-methods strategy. A final quantitative assessment will happen after 12 months with the preferred IMO to assess the long-term performance and maintenance needs. Discussion This mixed-methods RCT will explore patient experiences with 3D-printed IMOs, aiming to assess the potential for altering clinical practice and dental public health policies. Our results will inform policies by showing whether 3D printing offers comparable outcomes at lower costs, facilitating greater access to oral care for the elderly. Trial registration: ClinicalTrials.gov, NCT06155630, Registered on 04 December 2023. https://classic.clinicaltrials.gov/ct2/show/NCT06155630 3D printing CAD/CAM mandibular overdenture Costs and cost analysis Cross-over studies Dental care for aged Edentulous mouth Implant-supported dental prosthesis Patient satisfaction Removable prosthodontics Figures Figure 1 Figure 2 Background Complete tooth loss or edentulism remains one of the most burdensome oral health issues globally. Its prevalence is clustered in elderly populations and tends to remain high for many decades [ 1 ]. Edentulism can devastate well-being [ 2 ], with depressive symptoms worsening after complete tooth loss [ 3 ]. Poorer oral function after tooth loss, including impaired mastication [ 4 ], is closely linked to psychosocial discomfort and lower self-esteem [ 5 ]. Many edentulous individuals do not partake in social activities due to embarrassment when smiling, speaking or eating [ 6 ]. Moreover, edentulism has been shown to have likely systemic implications, as evidenced by its association with disability and earlier mortality in the elderly [ 7 ]. Even if full dental prostheses (i.e., dentures) can restore oral function/appearance [ 8 ] and enable better nutrition [ 9 ], elderly individuals face major barriers to that kind of care: (a) Restricted public funding for adult oral healthcare [ 10 ] – in general, government programs do not cover prosthetic treatment for the vast majority of edentulous individuals [ 11 ]; (b) Most edentulous patients depend on private care, with fees that are usually non-reimbursable and obstructive. Since edentulous individuals tend to be in poorer socioeconomic strata [ 12 ], high costs hamper their access to care [ 13 ]; (c) Many operatory steps on different days, since dental prosthetic care can easily demand more than six clinical appointments [ 14 , 15 ]. In this case, limited mobility and transportation fees can be a major barrier for the edentulous elderly, mainly for residents of long-term care facilities [ 10 ]. Moreover, a large number of in-person appointments may be markedly problematic for the elderly during contagious disease outbreaks, as clear during recent viral pandemics. Computer-assisted technologies can greatly improve access to oral healthcare by the elderly. Fewer appointments for denture treatment, i.e., two to four, instead of five as with the conventional techniques, can reduce patient costs [ 16 ]. Since one of those appointments serves mostly to confirm dental aesthetics before final prostheses are delivered, remote care becomes a reality. Patients can receive 3D images of their face with future dentures by internet, thus avoiding a clinical visit [ 17 ]. Moreover, elderly patients are at risk of losing their dentures and need a remake, especially if cognitively or physically impaired. Digital files can be used to remake the same dentures in the absence of the patient, whereas analogic techniques need a repetition of the original workflow [ 18 ]. Among the computer-aided designed and manufactured (CAD/CAM) options for denture fabrication, 3D printing (or additive manufacturing) stands out as a highly promising technology. In comparison to traditional and other CAD/CAM workflows, 3D printed dentures have the potential to minimize material waste while achieving high speed and quality [ 19 ]. Even with promising in vitro reports of digital denture materials [ 20 – 22 ], however, evidence from randomized clinical trials (RCTs) is still missing to verify their clinical performance. Our recent scoping review (search update: March 1st 2023) [ 23 ] found no RCT on 3D-printed implant-retained mandibular overdentures (IMO), which have been considered the standard of care for complete edentulism by international consensuses [ 24 , 25 ]. In addition, treatment success with dentures mostly depends on positive patient experiences. Integrating patient attitudes into the final dentures is vital for favorable results. Thus, patient-reported outcome measures (PROMs) are the core criteria in evaluating denture care, as for many healthcare interventions [ 22 ]. Yet, no study has explored patients’ experiences with the CAD/CAM dentures. In other words, it is unclear how patients perceive CAD/CAM dentures and whether they have a satisfactory performance from patients’ perspectives. Objectives We plan a mixed-methods cross-over RCT to determine the efficacy of 3D-printed complete overdentures, compared to the traditional method, for independently living edentulous seniors who have two implants in the anterior mandible, as purported by the McGill Consensus on Implant Overdentures [ 24 ]. Hypothesis This randomized cross-over trial aims to reveal whether implant-retained mandibular overdentures (IMO) produced by computer-aided design and 3D printing are more satisfactory to edentulous seniors than those fabricated using traditional methods. Methods Design and setting This mixed-methods cross-over RCT will compare one experimental intervention (CAD/CAM dental prostheses) versus an active comparator (standard of care conventional methods). Outcome assessment will take place three months after each intervention, up to a total follow-up of six months. This will be a single-center RCT, conducted at the Faculty of Dental Medicine and Oral Health Sciences, McGill University (Montreal, Canada). The creation of this report adhered to the guidelines outlined in the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) [26]. Figure 1 illustrates the standard protocol items diagram as suggested by SPIRIT, while the SPIRIT checklist for this study is provided in Additional file 1. Eligibility Criteria This trial will recruit edentulous patients seeking treatment with IMOs and maxillary complete dentures at McGill University. Inclusion criteria: (i) elderly according to the age cut-off purported by the World Health Organization (age ≥ 60 years) [27] and living independently; (ii) completely edentulous; (iii) no tooth extraction within the past 12 months; (iv) two Straumann tissue level RN implants symmetrically distributed in the anterior mandible for three or more months before the trial interventions; (v) desire to receive both upper denture and lower IMO with new stud attachments; (vi) good understanding of spoken and written English or French; (vii) ability to provide written informed consent. Exclusion criteria: (i) severe systemic disease or needing frequent hospitalization (i.e. American Society of Anesthesiologists Physical Status class >II) [28]; (ii) evidence of cognitive or motor impairment; (iii) acute or chronic symptoms of parafunctional or temporomandibular disorders; (iv) intraoral pathologies, either acute, progressive, potentially malignant or capable to hamper denture fit; (v) signs of endosseous lesions or residual dental structures in panoramic radiographs; (vi) signs of implant failure, including clinical mobility, peri-implant radiolucency, unacceptable bone loss (0.2mm/year after 1st year, or <2 mm any time) and/or persistent signs/symptoms of pain, neuropathy, infection and/or exudate [29]. Participant Recruitment We will recruit participants from the Greater Montreal area by verifying lists of prospective and past patients in our Faculty. This will be done directly with the Faculty’s clinical staff to reach those patients. Priority will be given to patients treated in recent years who may need to have their old IMOs replaced; e.g., 63 patients from 2010-2018 (around eight patients/year). Staff involved in clinical services will mention this study to patients and, if the latter have interest, refer them to our trial coordinator (TC). Patients without implants will be included if they comply with inclusion criteria #4 (two implants in the lower jaw) within the recruitment period. Recruitment rate will be based on the ability of the researchers to provide treatment rather than participant availability, which is set at three patients/ month. Recruiting 37% of the 63 patients available from 2010 to 2018 would reach the planned sample size (n=26). Participants will be assigned to interventions with the recruitment flow, which will take nine months (from the 5 th to the 14 th month). Recruitment and care provision to participants will be spread over a 9-month period to reduce seasonal variation in their responses. Trial Interventions After screening and obtaining patient consent, participants will return to start denture fabrication (Fig. 2). Both denture pairs will be fabricated simultaneously and delivered in random order. Existing attachments will be replaced by Novaloc abutments of adequate cuff height (external margins 1 mm above the mucosa) and yellow/medium retentive matrices. Participants will come for a first appointment for scanning their existing dentures, with new abutments (manual torque) and attachment housings in place. The first visit will be the same for both conventional and digital pathways and will consist of scanning the patients’ existing upper complete denture and IMO. The existing dentures will be scanned by using a desktop scanner (Autoscan DS-EX, Shining 3D Ltd., Hangzhou, China). In the lab, the resulting .stl files will be 3D printed using a Max DLP 3D printer (Asiga, Alexandria, Australia). In a second clinical appointment, the interim printed dentures will be adjusted with wax for the desired lip support, occlusal plane, occlusal vertical dimension (OVD) and centric relation (CR). Secondary impressions (regular PVS) will be taken under the intaglio to refine fit, with the new abutments and housings in place. Maxillary and mandibular interim printed dentures will be scanned separately and in occlusion (Autoscan DS-EX). The face of the patients will also be scanned by a face scanner (Shining 3D face scanner, Shining 3D Ltd.). In the second lab session, .stl files will be superimposed for the digital pathway. Another software (Exocad Full Denture Module, Exocad GmbH, Darmstadt, Germany) will be used to set teeth and denture bases virtually; virtual dentures will be superimposed to the facial images to estimate final results. Denture bases will be manufactured by a Max DLP 3D printer with Dentca Denture Base Resin (Dentca Inc., Torrance, USA) at 100 μm/layer and supports on the flanges’ facial surface. A 0.3 mm relief will be applied in the sockets dedicated to receive teeth and attachment housings. Following washing in isopropyl alcohol (five minutes), dentures will receive Portrait 3D teeth (Dentsply Sirona, Charlotte, USA), treated by the Fuse 3D Denture Bonding System (Dentsply Sirona). Uncured base resin will be used to lute teeth and cured under UV. Final polymerization will take place in a dental polymerization equipment (Flash, Asiga) for 30 min. Dentures will be finished and polished, and sandblasted (50μm aluminum oxide) in the attachment sockets. For the conventional pathway, the second lab session will consist of pouring the impressions (Type IV stone), mounting the casts in an Arcon semi-adjustable articulator, removing the printed teeth, and replacing them with wax rim and acrylic tooth setup (Portrait, Dentsply Sirona – same shape, size and shade used for 3D-printed dentures). A third appointment will be used for wax try-in for the conventional pathway. For the digital pathway, participants will have a chance to appraise their smile on a computer screen (virtual try-in, done remotely) and request modifications. Denture bases will be manufactured with conventional heat-polymerized resins, and participants will return for a fourth appointment for delivery, including chairside pick-up of attachments (GC Reline resin; GC America Inc., Alsip, USA). Two short-term adjustments will be scheduled 24-72 h and seven days after delivery, and then weekly until the dentures are comfortable. In the fourth appointment, the following will be done for the digital pathway: denture delivery, including abutment insertion (torque: 35Ncm), chairside attachment pick-up, and first adjustments. Chairside pick-up will use a hard reline resin (GC Reline), to be handled as per manufacturer recommendations. For both interventions, we expect to adjust most dentures at two post-delivery appointments. In a previous RCT on conventional complete dentures, 10% needed more than four appointments, with a maximum of six appointments for a single participant (total n=39) [30]. Participants will be scheduled for outcome assessment at three months following the delivery of each denture pair. A three-month period is enough to elicit stable patient perception of existing dentures, but will not induce significant wear/degradation of dental biomaterials or poor fit due to changes in intraoral tissues. Moreover, extending each follow-up from three to six months is not expected to result in changes of ratings of patient satisfaction with received dentures, even if denture adjustments are part of the three-month period [31, 32]. Participant Allocation and Minimization of Bias Assignment to either experimental or comparator as the first method will take place immediately after delivery adjustments of both denture pairs. The sequence for the interventions will be decided at the individual level following a list of random numbers (1:1 ratio), according to permuted blocks of varying sizes. Randomization will be performed by the trial coordinator (TC; uninvolved with clinical and follow-up procedures) and will take place at the individual level. The TC will retain a list of fabrication methods per denture pair and identify them as #1 and #2, depending on which will be used first. Random allocation to each intervention sequence will be concealed until both denture pairs are ready for delivery. The TC will be the only person with access to the randomization codes. It is known that gender influences patient perceptions of received dentures, e.g., elderly women tend to give a higher value to esthetics than their male counterparts [33, 34]. Therefore, the sample will be stratified based on male/female, to analyze possible effects of gender on trial outcomes. Regarding blinding, participants will be unaware of received interventions, and a researcher uninvolved in the clinical procedures will collect outcome data. Blinding will be lifted only after data collection is complete. Since digital manufacturing may have some specific features (like a subtle staircase topography), blinding effectiveness will be verified at each three-month follow-up. Participants will answer which denture pair is in use, and to grade their conviction of their response from 0-10 (“not at all certain” and “extremely certain,” respectively) [35]. Outcome measures The primary outcome of this trial will be the general satisfaction of participants with their full dentures, in line with its ultimate goal. In addition, secondary measures will include satisfaction-specific aspects (e.g., chewing ability and aesthetics), oral health related quality of life (OHQoL), clinical quality of the dentures, and treatment costs, all based on a public health system perspective. 1. The McGill Denture Satisfaction Questionnaire (MDSQ) [36, 37] will be used to measure overall satisfaction, and satisfaction with specific aspects of the denture – ability to chew, comfort, stability, aesthetics (appearance), ability to speak, and ability to clean. Participants will rate their satisfaction on a 100 mm visual analogue scales (VAS) with anchors representing “no satisfaction at all” to “complete satisfaction”. Participants will receive training with VAS before answering the MDSQ. Previous studies have shown good properties for the MDSQ. Besides good internal consistency and reproducibility [37, 38], its ability to discriminate between different clinical conditions denotes good construct validity [37, 39, 40]. At the last follow-up, participants will be asked about which denture pair they prefer, if any, and their reasons. 2. OHQoL: This construct, conceptualized as the “subjective evaluation of the individual's oral health, functional well-being, emotional well-being, expectations and satisfaction with care, and sense of self” [41], will be assessed by the Oral Health Impact Profile for Edentulous Patients (OHIP-EDENT) questionnaire. OHIP-EDENT is a short version (20 questions) of the original 49-question OHIP (Oral Health Impact Profile) tested specifically with edentulous individuals [42]. Questions can be grouped into subscales, corresponding to domains/dimensions of perceived impact, including functional limitation or social disability. This short version shows good reliability and discriminant validity, akin to the original OHIP [42]. Despite the seven original subscales, a four-domain model based on recent factor analysis studies will be used [43, 44]. 3. Clinical denture quality: This trial will use the Functional Assessment of Dentures (FAD) instrument to assess denture quality [45, 46]. FAD is composed of questions about relevant clinical parameters, including dental occlusion/articulation, denture retention and stability. A single dentist will apply the instrument without removing the dentures from the mouth, which will ensure that s/he cannot see the staircase topography of CAD/CAM fabrication. The color of the denture base materials will be verified at baseline and after three months with a Vita EasyShade portable spectrophotometer [47]. Upper dentures will be placed on a black background and three measures will be taken from the center of the palatal vault, at the polished side. Color measures will be expressed according to the CIELCh and CIELab systems. Clinically evident damage (e.g., fractured base or teeth, stains) to denture constituents will be also reported. 4. Cost: Data on both the direct and indirect costs of each fabrication method will be gathered, as done previously [30, 48]. The number of clinical visits for denture fabrication and adjustments will be reported separately, including non-scheduled visits. Total cost per fabrication method will be described in terms of expenses with human resources (time and CAD$) and materials (consumables/equipment use, CAD$). Yearly cost differences, or $(Δ), will be calculated based on the expected lifetime of five years for a pair of dentures, by dividing total cost differences by five. After the last follow-up, participants will answer four questions on their willingness-to-pay for each denture pair: (1) If you were to choose A over B, how much are you willing to pay for it? (2) Are you willing to pay the $(Δ) to have A over B? (3) Are you willing to pay the $(Δ) to have A over B by monthly installments (12 months)? (4) Do you think that a public health plan should cover the cost of these treatments? Both or only A or B. The cost-effectiveness of both methods will be compared by using overall patient satisfaction to measure the effect of interventions. Economic analysis will have the perspective of the public health system of Quebec. All expenditures and resources through all stages of dental care (from clinical exam to denture adjustments) will be included, considering a short-term/three-month time frame. Results will be expressed by the incremental cost-effectiveness ratio (ICER). 5. Adverse effects: All adverse events during the RCT will be recorded at each post-delivery appointment and follow-up. Common events, i.e. mucosal injuries and difficulties with new dentures, will be rated on a three‐point ordinal scale [49]. More uncommon (nausea, change in taste and lingering speech difficulties) and rare events (allergy to denture materials) will be reported on a binary scale. 6. Choice of overdenture and patient experiences: A qualitative analysis will be carried out to better understand patients’ perception of CAD/CAM dentures and to find out any emergent themes besides: (1) patients’ reasons for choosing a specific denture pair; and (2) their experience of using a 3D-printed IMO. By adopting a descriptive approach, individual semi-structured interviews will be carried out to obtain an in-depth understanding of patients’ experiences and preferences [50]. Outcome Assessment Timeline 1. Screening: The RA will invite potential participants, answer questions, and gather informed consent. The RA will complete a screening form checking eligibility criteria for all approached individuals. Panoramic radiographs will be requested, and recruitment will be conditional based on the results from the imaging (as in Exclusion Criteria). As a piloting process, we collect data on gender conformity by two questionnaires, the Conformity to Feminine Norms Inventory-45 and Conformity to Masculine Norms Inventory-30 [51, 52]. 2. Baseline: Participants will return for baseline evaluation, intraoral scanning , and collection of sociodemographic information (including gender questionnaires), medical and dental history (including patient experience with previous dentures). Participants will be asked to complete the MDSQ and OHIP-EDENT, and a dentist with experience in providing full dentures will apply the FAD instrument. 3. Delivery and denture adjustments: Immediately after the end of the delivery appointments, the FAD instrument will be applied for each denture pair (same dentist as on baseline). The adverse effects form will be completed at the same time, as well as during each post-delivery appointment, scheduled or not. 4. First follow-up (three months): Participants will complete the outcome data questionnaires, the MDSQ and OHIP-EDENT. We will administer both questionnaires with a tablet computer away from the clinical setting. In turn, we will complete the FAD and adverse effects form, as described in the previous paragraph plus the colorimetric evaluation of denture bases. 5.Second follow-up (six months):Same as in previous time point (questionnaires and colorimetric analysis). At the end of the trial, participants will choose which overdenture they wish to keep. When faced with a choice, one is presented with the choices and the associated costs, which allows for a rationale decision. This is particularly important as dentures are typically not covered by the health care provider. Then we will conduct individual semi-structured interviews about their experiences with the IMOs. The rich descriptive data obtained by qualitative interviews will help further explicate the quantitative findings. An experienced qualitative researcher will be responsible to conduct the interviews outside of the clinic using an interview guide with open-ended questions. Given the explanatory nature of this mixed-methods design, the interview guide will be created iteratively based on the quantitative outcomes which require further explanation. Each interview will be audio-recorded and transcribed verbatim. At baseline, we will register time (professional and patient) and materials use for cost analyses. The same procedures will be repeated during every appointment in the trial, scheduled or not. 6. Long-term follow-up:Once participants provide 6-month data and choose the denture pair they wish to keep, we will continue their follow-up. For those participants who have no preference for one specific pair, the last pair used will be kept. Then, we will schedule them for yearly appointments until five years, during which the same outcome data will be gathered. In the meantime, participants may contact the research team for unscheduled appointments. Any event such as maintenance and clinical complications, as well as time and procedures done, will be reported as part of collected outcome data. Sample size estimation The planned enrollment comprises 26 participants, based on overall patient satisfaction. A minimal important difference of 10mm (10% of the VAS) was used for the estimation, as done in previous RCTs [40, 53]. A standard deviation of 7.5mm was chosen for the difference in satisfaction [54]. Considering a 2-sided alpha of 0.01 to compensate for the number of secondary outcomes and a power of 90%, the RCT requires n=21 for superiority hypothesis testing (i.e., the confidence interval for between-treatment differences would exclude zero) [55]. The final sample size is drawn from including further 20% to the planned n to compensate for possible dropouts; although withdrawals will unlikely pass 10% [40, 54, 56], additional participants may be lost due to aging-related issues (e.g., worsening of systemic diseases, and death). Adherence to Protocol and Losses to Follow-Up Previous studies by our group reveal high study adherence rates, with >90% wearing their full dentures over the course of six months [40, 56-58]. This RCT provides variations of a treatment sought by participants at university clinics, with no major change in their routine. Subsequent follow ups following the end of this RCT will also elucidate adherence rates for longer periods. As much as possible, we set up the intervention schedule, follow-up and data collection to resemble traditional oral healthcare procedures. We will also have the RA communicate with the participants using their preferred communication method (e.g., phone, text, e-mail) to verify possible adverse events, such as pain under the denture base, that may require a rapid adjustment visit. Those events and consequent conducts will be reported as part of the outcome variable “5. Adverse effects”. Analytical plan Quantitative Analysis We will enter and analyze outcome data in a blind fashion at the end of data collection. The TC will enter data in spreadsheets by randomly coding the interventions as 1 and 2, and the data analyst will be unaware of their meaning until the end of statistical testing. Data will undergo descriptive analysis, with substantial deviations from normality leading to variable transformation. Generalized estimating equations (GEE) will be used to test the effect of interventions, follow-up time and gender as independent variables, with 95% confidence intervals. Other approaches to assess the primary outcome will involve the inclusion of age, baseline results and previous denture wearing in separate models, one covariate at a time. Results will be evaluated according to the intention-to-treat principle. In the case of unbalanced missing data among interventions or loss of 5% (n > 2) or more of participants, different strategies will be attempted for imputing primary outcome data, as recommended by Dziura et al. [59]; multiple imputation will be used for patient satisfaction based on least squares regression with at least five datasets. In the case of “missing not at random” (MNAR) data, analyses will be repeated after a baseline-observation-carried-forward approach (i.e., withdrawn participants will be considered as dissatisfied as prior to receiving dentures). A second analysis will be performed with imputed values and cross-checked. Qualitative Analysis Once the interviews are completed and transcribed, we will use the MaxQDA software for thematic analysis. Transcripts will be cut into meaningful segments and coded. Analysis will initiate by a deductive coding strategy based on the interview questions and the theoretical framework of denture satisfaction [37, 60]. Then, we will proceed by adopting an inductive analysis to add any emerging codes. By an iterative process, the coded segments will be regrouped into relevant themes linked to our study objectives [61, 62]. Methodological rigor will be warranted in the study, including member checking before or during data analysis, to meet trustworthiness, credibility, and transferability [63]. That is, the results of the study will be formally or informally discussed with participants. To enhance coding quality, the qualitative researcher and one of the team members will independently code two transcripts chosen at random and then meet to compare/revise the codes if needed. Lastly, the qualitative data will be integrated into quantitative data by an explanatory strategy. Data management, monitoring, and auditing Two independent researchers will regularly review the collected data as part of a data monitoring committee. Additionally, McGill University's Research Ethics Board (REB) Office retains the authority to conduct an independent audit at any point in time. Risks, participant safety, and trial adherence This study represents minimal safety risk for participants, since all procedures are comparable with nonsurgical oral healthcare (i.e., clinical exam, intraoral molding). The number of appointments to fabricate and adjust provided dentures is similar to what is done in standard practice, and all materials to be used are approved for patient use by Health Canada. Potential participants will receive a complete explanation of the RCT, including potential risks before invitation to sign the informed consent. All denture materials are licensed for patient use and sold in Canada and United States. This way, risks associated with treatment are the same expected for minor oral surgery and standard dental implants/dentures. Participants may experience sore spots under the dentures after the placement of retentive components. If this happens, the dentures will be adjusted as necessary. Allergic reactions to dental materials (such as the acrylic mixture used to bond components and denture) are rare but might also occur. The lower denture might break after the placement of the implant retentive components. If this happens during the study timeline, the dentures will be repaired at no cost. Confidentiality Each participant's quantitative and qualitative data will be assigned an identification code to ensure confidentiality. The information connecting participants' identities to the codes will be securely stored in a password-protected file and computer. The final research forms, x-rays, and collected data will be sent to the primary investigator’s office and stored for 25 years for the exclusive objectives of this study and then destroyed. These will be kept secure by a password to which only the principal doctor will have access. Dissemination and knowledge transfer Knowledge translation will target (i) the scientific community, and (ii) the public health and professional sectors. For the first, the team will publish reports in high-impact dental journals, as done with our previous clinical studies [57, 64]. The group will present results in scientific conferences aiming at dental professionals and researchers, as well as industry professionals, including the General Session of the International Association for Dental Research (IADR). For the second, our team will describe clinical and laboratory procedures as appendices of our scientific papers, besides a short book and YouTube videos, both directed to clinicians. The results of this study will be used to develop continuing education courses and webinars that explain the use of digital dentures based on our experiences and research findings. In addition, we will produce patient education materials, including a brochure and a video that describe the potential benefits and limitations of CAD/CAM technology for denture fabrication. Discussion Despite promising results, there is a scarcity of RCTs comparing CAD/CAM to conventional full denture fabrication methods, either implant-retained or conventional [ 23 ]. As of March 2018, only two clinical studies have compared full dentures fabricated by CAD/CAM and conventional methods [ 65 ]. Both of these studies were non-randomized, with one based on treatment provided by dental students [ 66 ] and the other considering surrogate measures [ 67 ]. A recent systematic review (updated: Oct-2019) confirms that CAD/CAM technologies produce dentures that fit intraoral tissues better than conventional methods [ 68 ]. That review was restricted to in vitro studies, however. To appraise the state of the current literature regarding digital removable dentures, we re-ran the electronic search strategies of those reviews and found no cross-over clinical trial comparing CAD/CAM to conventional implant-retained dentures. Amongst those newly published comparative studies on CAD/CAM conventional dentures, two were prospective clinical studies [ 66 , 69 ], two were retrospective studies [ 70 , 71 ], one was cross-sectional [ 72 ] (all five conducted in student clinics), and one was a non-randomized trial [ 73 ], besides one RCT on conventional dentures made with a closed workflow (Dentca) [ 74 ]. Besides, no study has so far explored patient experiences with the CAD/CAM dentures. Given the impact of dental prostheses on the oral health of edentulous patients, it is essential to document the clinical and patient-reported performance of digitally fabricated dentures. Determining the potential benefits of CAD/CAM full dentures for seniors demands high-quality comparative evidence (i.e. RCT). This proposal is the first step to determine the advantages and limitations of that novel technology in treating the elderly with implant overdentures. Utilizing qualitative methods allows for a comprehensive exploration of patients' experiences, as evidenced by a previous study conducted by our team, which examined the reasons for declining treatment with implant overdentures [ 37 ]. Employing a mixed-methods approach will integrate the quantitative findings from the clinical trial by offering an in-depth interpretation of patient perspectives through qualitative methods [ 57 ]. Anticipated outcomes are expected to hold significant relevance for clinicians administering implant-assisted treatment to edentate patients. The resulting guidelines and recommendations have the potential to enhance dental prosthetic care for the edentate elderly population, a substantial portion of whom face challenges accessing more intricate treatment modalities. Results will be important to guide public health systems and practitioners in the adoption of CAD/CAM to streamline denture provision. Better outcomes will enhance the potential access to care by edentulous seniors; government-subsidized programs, such as the recently launched Canadian Dental Care Plan for seniors, will be able to provide IMOs with lower costs and/or fewer restrictions. Less appointments and better infection control will also reduce risks for elders to contract diseases such as COVID-19 and flu-like infections in the dental setting. Possible remote care (virtual try-in of new dentures, ordering remakes at distance) also reduces infection risk. Better knowledge of patient perceptions of CAD/CAM IMOs will highlight the potential barriers and opportunities for using digital prostheses in dental practice. It will also help understand if the CAD/CAM technology has reached its goal of offering a superior/cost-effective treatment. Declarations Trial Status ClinicalTrials.gov, NCT06155630, Registered on 04 December 2023. Recruiting began January 2024. Estimated date of recruitment completion: September 2024. Acknowledgements Dana Jafarpour is the recipient of Vanier Canada Graduate Scholarship for this protocol. Funding This project will be supported by a grant from the ITI Foundation, Switzerland (Grant No. 1744-2023) (Additional file 2). Availability of data and materials For depositing research data, we might deposit anonymized datasets in the McGill Dataverse repository upon request. According to McGill, all data are stored securely on servers located in Canada. The anonymized data may be published or shared during scientific meetings; however, it will not be possible to identify the participants. Authors’ contributions RFS designed and will coordinate the trial. DJ drafted the manuscript and will execute the trial. NE helped to draft this manuscript and will help with the clinical interventions. CB contributed with the study design and is overseeing the qualitative data gathering and analysis. SE contributed with the study design and is overseeing the economic data collection and analysis. SAN is assisting in the prosthetic stages and integration phase/knowledge translation. TS has advised in the data analysis plan. JSF provided important contributions to study design and drafted this manuscript. EZ will assist with knowledge transfer and assessment of material performance. All authors revised and approved the final manuscript. Ethics approval and consent to participate Before enrolling in this trial, all participants will be required to give informed written consent and will be made aware of their right to withdraw at any point. Only in this case will unblinding be permissible. The consent process, study documentation, and the entire trial will adhere to the guidelines outlined in the Tri-Council Policy Statement [75]. The McGill University REB Office approved this protocol under the reference A00-M29-23B (22-07-089). Ethical approval documents can be found in Additional file 3. A version of this protocol has also been registered in the Clinicaltrials.gov registry under the identifier NCT03126942. Any amendments or modifications to the protocol during the trial will be formally communicated to the REB Office. If approved, these changes will be documented on Clinicaltrials.gov and disclosed to participants, allowing them time to consider continued participation. Participants will be officially enrolled in the trial only after obtaining a signed informed consent form (Additional file 4). A researcher will explain the study's aims and nature to each participant before they sign the consent form. It will be clarified that participation is voluntary, and participants are free to withdraw from the study at any time without providing a reason. Compensation for participants will cover the cost of transportation to data collection appointments, including the baseline assessment. Participants will receive implant overdenture treatment at no cost, along with maintenance during the follow-up period. Consent for publication Not applicable. Competing interests The authors declare that they have no competing interests. References Cardoso M, Balducci I, Telles DM, Lourenço EJV, Nogueira Júnior L. Edentulism in Brazil: trends, projections and expectations until 2040. Cien Saude Colet. 2016;21:1239–46. 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A modified short version of the oral health impact profile for assessing health-related quality of life in edentulous adults. Int J Prosthodont. 2002;15(5):446–50. John MT, Feuerstahler L, Waller N, Baba K, Larsson P, Celebic A, Kende D, Rener-Sitar K, Reissmann DR. Confirmatory factor analysis of the Oral Health Impact Profile. J Oral Rehabil. 2014;41(9):644–52. Souza RF, Leles CR, Guyatt GH, Pontes CB, Della Vecchia MP, Neves FD. Exploratory factor analysis of the Brazilian OHIP for edentulous subjects. J Oral Rehabil. 2010;37(3):202–8. Anastassiadou V, Naka O, Heath MR, Kapari D. Validation of indices for functional assessment of dentures. Gerodontology. 2002;19(1):46–52. Corrigan PJ, Basker RM, Farrin AJ, Mulley GP, Heath MR. The development of a method for functional assessment of dentures. Gerodontology. 2002;19(1):41–5. Al-Qarni FD, Goodacre CJ, Kattadiyil MT, Baba NZ, Paravina RD. Stainability of acrylic resin materials used in CAD-CAM and conventional complete dentures. J Prosthet Dent. 2020;123(6):880–7. Della Vecchia MP, Leles CR, Cunha TR, Ribeiro AB, Sorgini DB, Muglia VA, Reis AC, Albuquerque RF Jr., de Souza RF. Mini-Implants for Mandibular Overdentures: Cost-Effectiveness Analysis alongside a Randomized Trial. JDR Clin Trans Res. 2018;3(1):47–56. de Resende GP, Nogueira TE, Leles CR. Effectiveness of a simplified method for final impression in complete denture treatment: A pragmatic clinical trial. Gerodontology. 2019;36(4):365–73. Lesaffre E, Feine J, Leroux B, Declerck D. Statistical and methodological aspects of oral health research. Wiley Online Library; 2009. Levant RF, McDermott R, Parent MC, Alshabani N, Mahalik JR, Hammer JH. Development and evaluation of a new short form of the Conformity to Masculine Norms Inventory (CMNI-30). J Couns Psychol. 2020;67(5):622–36. Parent MC, Moradi B. An abbreviated tool for assessing feminine norm conformity: psychometric properties of the Conformity to Feminine Norms Inventory-45. 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Single-implant overdentures retained by a novel attachment: A mixed methods crossover randomized clinical trial. JDR Clin Trans Res. 2024;9(1):27–41. Albuquerque IS, Regis RR, de Souza RF, Gurgel KF, Silva PG, Pinto-Fiamengui LMS, Freitas-Pontes KM. Is a two-step impression mandatory for complete denture fabrication on the severely resorbed mandible? A randomized trial on patient perception and denture quality. J Dent. 2020;98:103356. Dziura JD, Post LA, Zhao Q, Fu Z, Peduzzi P. Strategies for dealing with missing data in clinical trials: from design to analysis. Yale J Biol Med. 2013;86(3):343. Awad MA, Feine JS. Measuring patient satisfaction with mandibular prostheses. Community Dent Oral Epidemiol. 1998;26(6):400–5. Braun V. Cv, hayfield n., terry g., thematic analysis. Handbook of Research Methods in Health Sciences 2018. Thorogood N, Green J. Qualitative methods for health research. Qualitative methods for health research 2018:1-440. Sandelowski M. The problem of rigor in qualitative research. ANS Adv Nurs Sci. 1986;8(3):27–37. De Souza R, Ribeiro A, Della Vecchia M, Costa L, Cunha T, Reis ACd, Albuquerque R Jr. Mini vs. standard implants for mandibular overdentures: a randomized trial. J Dent Res. 2015;94(10):1376–84. Janeva NM, Kovacevska G, Elencevski S, Panchevska S, Mijoska A, Lazarevska B. Advantages of CAD/CAM versus Conventional Complete Dentures - A Review. Open Access Maced J Med Sci. 2018;6(8):1498–502. Kattadiyil MT, Jekki R, Goodacre CJ, Baba NZ. Comparison of treatment outcomes in digital and conventional complete removable dental prosthesis fabrications in a predoctoral setting. J Prosthet Dent. 2015;114(6):818–25. AlHelal A, AlRumaih HS, Kattadiyil MT, Baba NZ, Goodacre CJ. Comparison of retention between maxillary milled and conventional denture bases: A clinical study. J Prosthet Dent. 2017;117(2):233–8. Wang C, Shi YF, Xie PJ, Wu JH. Accuracy of digital complete dentures: A systematic review of in vitro studies. J Prosthet Dent 2020. Srinivasan M, Schimmel M, Naharro M, C ON, McKenna G, Muller F. CAD/CAM milled removable complete dentures: time and cost estimation study. J Dent. 2019;80:75–9. Arakawa I, Al-Haj Husain N, Srinivasan M, Maniewicz S, Abou-Ayash S, Schimmel M. Clinical outcomes and costs of conventional and digital complete dentures in a university clinic: A retrospective study. J Prosthet Dent 2021. Kim TH, Huh JB, Lee J, Bae EB, Park CJ. Retrospective Comparison of Postinsertion Maintenances Between Conventional and 3D Printed Complete Dentures Fabricated in a Predoctoral Clinic. J Prosthodont. 2021;30(S2):158–62. Clark WA, Brazile B, Matthews D, Solares J, De Kok IJ. A Comparison of Conventionally Versus Digitally Fabricated Denture Outcomes in a University Dental Clinic. J Prosthodont. 2021;30(1):47–50. Drago C, Borgert AJ. Comparison of nonscheduled, postinsertion adjustment visits for complete dentures fabricated with conventional and CAD-CAM protocols: A clinical study. J Prosthet Dent. 2019;122(5):459–66. Ohara K, Isshiki Y, Hoshi N, Ohno A, Kawanishi N, Nagashima S, Inoue M, Kubo D, Yamaya K, Inoue E et al. Patient satisfaction with conventional dentures vs. digital dentures fabricated using 3D-printing: A randomized crossover trial. J Prosthodont Res 2022. TCPS-2: Canadian Institutes of Health Research, Natural Sciences and Engineering Research Council of Canada, and Social Sciences and Humanities Research Council of Canada. Tri-Council Policy Statement: Ethical Conduct for Research Involving Humans 2014. Supplementary Files Additionalfile1.SPIRITchecklist.docx Additionalfile4.ConsentformREBEnglish2.docx Cite Share Download PDF Status: Published Journal Publication published 16 Apr, 2024 Read the published version in Trials → Version 1 posted Editorial decision: Minor revision 25 Mar, 2024 Reviewers agreed at journal 15 Mar, 2024 Reviewers invited by journal 15 Mar, 2024 Editor assigned by journal 15 Mar, 2024 First submitted to journal 15 Feb, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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RCT","fulltext":[{"header":"Background","content":"\u003cp\u003eComplete tooth loss or edentulism remains one of the most burdensome oral health issues globally. Its prevalence is clustered in elderly populations and tends to remain high for many decades [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEdentulism can devastate well-being [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], with depressive symptoms worsening after complete tooth loss [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Poorer oral function after tooth loss, including impaired mastication [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], is closely linked to psychosocial discomfort and lower self-esteem [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Many edentulous individuals do not partake in social activities due to embarrassment when smiling, speaking or eating [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Moreover, edentulism has been shown to have likely systemic implications, as evidenced by its association with disability and earlier mortality in the elderly [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEven if full dental prostheses (i.e., dentures) can restore oral function/appearance [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] and enable better nutrition [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], elderly individuals face major barriers to that kind of care: (a) Restricted public funding for adult oral healthcare [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] \u0026ndash; in general, government programs do not cover prosthetic treatment for the vast majority of edentulous individuals [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]; (b) Most edentulous patients depend on private care, with fees that are usually non-reimbursable and obstructive. Since edentulous individuals tend to be in poorer socioeconomic strata [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], high costs hamper their access to care [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]; (c) Many operatory steps on different days, since dental prosthetic care can easily demand more than six clinical appointments [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. In this case, limited mobility and transportation fees can be a major barrier for the edentulous elderly, mainly for residents of long-term care facilities [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Moreover, a large number of in-person appointments may be markedly problematic for the elderly during contagious disease outbreaks, as clear during recent viral pandemics.\u003c/p\u003e \u003cp\u003eComputer-assisted technologies can greatly improve access to oral healthcare by the elderly. Fewer appointments for denture treatment, i.e., two to four, instead of five as with the conventional techniques, can reduce patient costs [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Since one of those appointments serves mostly to confirm dental aesthetics before final prostheses are delivered, remote care becomes a reality. Patients can receive 3D images of their face with future dentures by internet, thus avoiding a clinical visit [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Moreover, elderly patients are at risk of losing their dentures and need a remake, especially if cognitively or physically impaired. Digital files can be used to remake the same dentures in the absence of the patient, whereas analogic techniques need a repetition of the original workflow [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAmong the computer-aided designed and manufactured (CAD/CAM) options for denture fabrication, 3D printing (or additive manufacturing) stands out as a highly promising technology. In comparison to traditional and other CAD/CAM workflows, 3D printed dentures have the potential to minimize material waste while achieving high speed and quality [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Even with promising \u003cem\u003ein vitro\u003c/em\u003e reports of digital denture materials [\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], however, evidence from randomized clinical trials (RCTs) is still missing to verify their clinical performance. Our recent scoping review (search update: March 1st 2023) [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] found no RCT on 3D-printed implant-retained mandibular overdentures (IMO), which have been considered the standard of care for complete edentulism by international consensuses [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn addition, treatment success with dentures mostly depends on positive patient experiences. Integrating patient attitudes into the final dentures is vital for favorable results. Thus, patient-reported outcome measures (PROMs) are the core criteria in evaluating denture care, as for many healthcare interventions [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Yet, no study has explored patients\u0026rsquo; experiences with the CAD/CAM dentures. In other words, it is unclear how patients perceive CAD/CAM dentures and whether they have a satisfactory performance from patients\u0026rsquo; perspectives.\u003c/p\u003e \u003cdiv id=\"Sec2\" class=\"Section2\"\u003e \u003ch2\u003eObjectives\u003c/h2\u003e \u003cp\u003eWe plan a mixed-methods cross-over RCT to determine the efficacy of 3D-printed complete overdentures, compared to the traditional method, for independently living edentulous seniors who have two implants in the anterior mandible, as purported by the McGill Consensus on Implant Overdentures [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eHypothesis\u003c/h3\u003e\n\u003cp\u003eThis randomized cross-over trial aims to reveal whether implant-retained mandibular overdentures (IMO) produced by computer-aided design and 3D printing are more satisfactory to edentulous seniors than those fabricated using traditional methods.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cem\u003eDesign and setting\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThis mixed-methods cross-over RCT will compare one experimental intervention (CAD/CAM dental prostheses) versus an active comparator (standard of care conventional methods). Outcome assessment will take place three months after each intervention, up to a total follow-up of six months. This will be a single-center RCT, conducted at the Faculty of Dental Medicine and Oral Health Sciences, McGill University (Montreal, Canada). The creation of this report adhered to the guidelines outlined in the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT)\u0026nbsp;[26]. \u0026nbsp;Figure 1 illustrates the standard protocol items diagram as suggested by SPIRIT, while the SPIRIT checklist for this study is provided in Additional file 1.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eEligibility Criteria\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThis trial will recruit edentulous patients seeking treatment with IMOs and maxillary complete dentures at McGill University.\u003c/p\u003e\n\u003cp\u003eInclusion criteria: (i) elderly according to the age cut-off purported by the World Health Organization (age ≥\u0026nbsp;60 years)\u0026nbsp;[27]\u0026nbsp; and living independently; (ii) completely edentulous; (iii) no tooth extraction within the past 12 months; (iv) two Straumann tissue level RN implants symmetrically distributed in the anterior mandible for three or more months before the trial interventions; (v) desire to receive both upper denture and lower IMO with new stud attachments; (vi) good understanding of spoken and written English or French; (vii) ability to provide written informed consent.\u003c/p\u003e\n\u003cp\u003eExclusion criteria: (i) severe systemic disease or needing frequent hospitalization (i.e. American Society of Anesthesiologists Physical Status class \u0026gt;II)\u0026nbsp;[28]; (ii) evidence of cognitive or motor impairment; (iii) acute or chronic symptoms of parafunctional or temporomandibular disorders; (iv) intraoral pathologies, either acute, progressive, potentially malignant or capable to hamper denture fit; (v) signs of endosseous lesions or residual dental structures in panoramic radiographs; (vi) signs of implant failure, including clinical mobility, peri-implant radiolucency, unacceptable bone loss (0.2mm/year after 1st year, or \u0026lt;2 mm any time) and/or persistent signs/symptoms of pain, neuropathy, infection and/or exudate\u0026nbsp;[29].\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eParticipant Recruitment\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eWe will recruit participants from the Greater Montreal area by verifying lists of prospective and past patients in our Faculty. This will be done directly with the Faculty’s clinical staff to reach those patients. Priority will be given to patients treated in recent years who may need to have their old IMOs replaced; e.g., 63 patients from 2010-2018 (around eight patients/year). Staff involved in clinical services will mention this study to patients and, if the latter have interest, refer them to our trial coordinator (TC). Patients without implants will be included if they comply with inclusion criteria #4 (two implants in the lower jaw) within the recruitment period.\u003c/p\u003e\n\u003cp\u003eRecruitment rate will be based on the ability of the researchers to provide treatment rather than participant availability, which is set at three patients/ month. Recruiting 37% of the 63 patients available from 2010 to 2018 would reach the planned sample size (n=26). Participants will be assigned to interventions with the recruitment flow, which will take nine months (from the 5\u003csup\u003eth\u003c/sup\u003e\u0026nbsp; to the 14\u003csup\u003eth\u003c/sup\u003e\u0026nbsp; month). Recruitment and care provision to participants will be spread over a 9-month period to reduce seasonal variation in their responses.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eTrial Interventions\u003c/em\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAfter screening and obtaining patient consent, participants will return to start denture fabrication (Fig. 2). Both denture pairs will be fabricated simultaneously and delivered in random order. Existing attachments will be replaced by Novaloc abutments of adequate cuff height (external margins 1 mm above the mucosa) and yellow/medium retentive matrices.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eParticipants will come for a first appointment for scanning their existing dentures, with new abutments (manual torque) and attachment housings in place. The first visit will be the same for both conventional and digital pathways and will consist of scanning the patients’ existing upper complete denture and IMO. The existing dentures will be scanned by using a desktop scanner (Autoscan DS-EX, Shining 3D Ltd., Hangzhou, China). In the lab, the resulting .stl files will be 3D printed using a Max DLP 3D printer (Asiga, Alexandria, Australia).\u003c/p\u003e\n\u003cp\u003eIn a second\u0026nbsp;clinical appointment, the interim printed dentures will be adjusted with wax for the desired lip support, occlusal plane, occlusal vertical dimension (OVD) and centric relation (CR). Secondary impressions (regular PVS) will be taken under the intaglio to refine fit, with the new abutments and housings in place. Maxillary and mandibular interim printed dentures will be scanned separately and in occlusion (Autoscan DS-EX). The face of the patients will also be scanned by a face scanner (Shining 3D face scanner, Shining 3D Ltd.).\u003c/p\u003e\n\u003cp\u003eIn the second\u0026nbsp;lab session, .stl files will be superimposed for the digital pathway. Another software (Exocad Full Denture Module, Exocad GmbH, Darmstadt, Germany) will be used to set teeth and denture bases virtually; virtual dentures will be superimposed to the facial images to estimate final results.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDenture bases will be manufactured by a Max DLP 3D printer with Dentca Denture Base Resin (Dentca Inc., Torrance, USA) at 100 μm/layer and supports on the flanges’ facial surface. A 0.3 mm relief will be applied in the sockets dedicated to receive teeth and attachment housings. Following washing in isopropyl alcohol (five minutes), dentures will receive Portrait 3D teeth (Dentsply Sirona, Charlotte, USA), treated by the Fuse 3D Denture Bonding System (Dentsply Sirona). Uncured base resin will be used to lute teeth and cured under UV. Final polymerization will take place in a dental polymerization equipment (Flash, Asiga) for 30 min. Dentures will be finished and polished, and sandblasted (50μm aluminum oxide) in the attachment sockets.\u003c/p\u003e\n\u003cp\u003eFor the conventional pathway, the second lab session will consist of pouring the impressions (Type IV stone), mounting the casts in an Arcon semi-adjustable articulator, removing the printed teeth, and replacing them with wax rim and acrylic tooth setup (Portrait, Dentsply Sirona – same shape, size and shade used for 3D-printed dentures).\u003c/p\u003e\n\u003cp\u003eA third appointment will be used for wax try-in for the conventional pathway. For the digital pathway, participants will have a chance to appraise their smile on a computer screen (virtual try-in, done remotely) and request modifications.\u003c/p\u003e\n\u003cp\u003eDenture bases will be manufactured with conventional heat-polymerized resins, and participants will return for a fourth\u0026nbsp;appointment for delivery, including chairside pick-up of attachments (GC Reline resin; GC America Inc., Alsip, USA). Two short-term adjustments will be scheduled 24-72 h and seven days after delivery, and then weekly until the dentures are comfortable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn the fourth\u0026nbsp;appointment, the following will be done for the digital pathway: denture delivery, including abutment insertion (torque: 35Ncm), chairside attachment pick-up, and first adjustments. Chairside pick-up will use a hard reline resin (GC Reline), to be handled as per manufacturer recommendations.\u003c/p\u003e\n\u003cp\u003eFor both interventions, we expect to adjust most dentures at two post-delivery appointments. In a previous RCT on conventional complete dentures, 10% needed more than four appointments, with a maximum of six appointments for a single participant (total n=39)\u0026nbsp;[30].\u003c/p\u003e\n\u003cp\u003eParticipants will be scheduled for outcome assessment at three months following the delivery of each denture pair. A three-month period is enough to elicit stable patient perception of existing dentures, but will not induce significant wear/degradation of dental biomaterials or poor fit due to changes in intraoral tissues. Moreover, extending each follow-up from three to six months is not expected to result in changes of ratings of patient satisfaction with received dentures, even if denture adjustments are part of the three-month period\u0026nbsp;[31, 32].\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eParticipant Allocation and Minimization of Bias\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eAssignment to either experimental or comparator as the first method will take place immediately after delivery adjustments of both denture pairs. The sequence for the interventions will be decided at the individual level following a list of random numbers (1:1 ratio), according to permuted blocks of varying sizes. Randomization will be performed by the trial coordinator (TC; uninvolved with clinical and follow-up procedures) and will take place at the individual level. The TC will retain a list of fabrication methods per denture pair and identify them as #1 and #2, depending on which will be used first. Random allocation to each intervention sequence will be concealed until both denture pairs are ready for delivery.\u003c/p\u003e\n\u003cp\u003eThe TC will be the only person with access to the randomization codes. It is known that gender influences patient perceptions of received dentures, e.g., elderly women tend to give a higher value to esthetics than their male counterparts\u0026nbsp;[33, 34]. Therefore, the sample will be stratified based on male/female, to analyze possible effects of gender on trial outcomes.\u003c/p\u003e\n\u003cp\u003eRegarding blinding, participants will be unaware of received interventions, and a researcher uninvolved in the clinical procedures will collect outcome data. Blinding will be lifted only after data collection is complete. Since digital manufacturing may have some specific features (like a subtle staircase topography), blinding effectiveness will be verified at each three-month follow-up. Participants will answer which denture pair is in use, and to grade their conviction of their response from 0-10 (“not at all certain” and “extremely certain,” respectively)\u0026nbsp;[35].\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eOutcome measures\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe primary outcome of this trial will be the general satisfaction of participants with their full dentures, in line with its ultimate goal. In addition, secondary measures will include satisfaction-specific aspects (e.g., chewing ability and aesthetics), oral health related quality of life (OHQoL), clinical quality of the dentures, and treatment costs, all based on a public health system perspective.\u003c/p\u003e\n\u003cp\u003e1.\u0026nbsp;The McGill Denture Satisfaction Questionnaire (MDSQ)\u0026nbsp;[36, 37]\u0026nbsp;will be used to measure overall satisfaction, and satisfaction with specific aspects of the denture – ability to chew, comfort, stability, aesthetics (appearance), ability to speak, and ability to clean. Participants will rate their satisfaction on a 100 mm visual analogue scales (VAS) with anchors representing “no satisfaction at all” to “complete satisfaction”. Participants will receive training with VAS before answering the MDSQ. Previous studies have shown good properties for the MDSQ. Besides good internal consistency and reproducibility\u0026nbsp;[37, 38], its ability to discriminate between different clinical conditions denotes good construct validity\u0026nbsp;[37, 39, 40]. At the last follow-up, participants will be asked about which denture pair they prefer, if any, and their reasons.\u003c/p\u003e\n\u003cp\u003e2. OHQoL:\u0026nbsp;This construct, conceptualized as the “subjective evaluation of the individual's oral health, functional well-being, emotional well-being, expectations and satisfaction with care, and sense of self”\u0026nbsp;[41], will be assessed by the Oral Health Impact Profile for Edentulous Patients (OHIP-EDENT) questionnaire. OHIP-EDENT is a short version (20 questions) of the original 49-question OHIP (Oral Health Impact Profile) tested specifically with edentulous individuals\u0026nbsp;[42]. Questions can be grouped into subscales, corresponding to domains/dimensions of perceived impact, including functional limitation or social disability. This short version shows good reliability and discriminant validity, akin to the original OHIP\u0026nbsp;[42]. Despite the seven original subscales, a four-domain model based on recent factor analysis studies will be used\u0026nbsp;[43, 44].\u003c/p\u003e\n\u003cp\u003e3. Clinical denture quality:\u0026nbsp;This trial will use the Functional Assessment of Dentures (FAD) instrument to assess denture quality\u0026nbsp;[45, 46]. FAD is composed of questions about relevant clinical parameters, including dental occlusion/articulation, denture retention and stability. A single dentist will apply the instrument without removing the dentures from the mouth, which will ensure that s/he cannot see the staircase topography of CAD/CAM fabrication.\u0026nbsp;The color of the denture base materials will be verified at baseline and after three months with a Vita EasyShade portable spectrophotometer\u0026nbsp;[47].\u0026nbsp;Upper dentures will be placed on a black background and three measures will be taken from the center of the palatal vault, at the polished side. Color measures will be expressed according to the CIELCh and CIELab systems. Clinically evident damage (e.g., fractured base or teeth, stains) to denture constituents will be also reported.\u003c/p\u003e\n\u003cp\u003e4. Cost:\u0026nbsp;Data on both the direct and indirect costs of each fabrication method will be gathered, as done previously\u0026nbsp;[30, 48]. The number of clinical visits for denture fabrication and adjustments will be reported separately, including non-scheduled visits. Total cost per fabrication method will be described in terms of expenses with human resources (time and CAD$) and materials (consumables/equipment use, CAD$). Yearly cost differences, or $(Δ), will be calculated based on the expected lifetime of five years for a pair of dentures, by dividing total cost differences by five. After the last follow-up, participants will answer four questions on their willingness-to-pay for each denture pair: (1) If you were to choose A over B, how much are you willing to pay for it? (2) Are you willing to pay the $(Δ) to have A over B? (3) Are you willing to pay the $(Δ) to have A over B by monthly installments (12 months)? (4) Do you think that a public health plan should cover the cost of these treatments? Both or only A or B.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe cost-effectiveness of both methods will be compared by using overall patient satisfaction to measure the effect of interventions. Economic analysis will have the perspective of the public health system of Quebec. All expenditures and resources through all stages of dental care (from clinical exam to denture adjustments) will be included, considering a short-term/three-month time frame. Results will be expressed by the incremental cost-effectiveness ratio (ICER).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e5. Adverse effects:\u0026nbsp;All adverse events during the RCT will be recorded at each post-delivery appointment and follow-up. Common events, i.e. mucosal injuries and difficulties with new dentures, will be rated on a three‐point ordinal scale\u0026nbsp;[49]. More uncommon (nausea, change in taste and lingering speech difficulties) and rare events (allergy to denture materials) will be reported on a binary scale.\u003c/p\u003e\n\u003cp\u003e6. Choice of overdenture and patient experiences: A qualitative analysis will be carried out to better understand patients’ perception of CAD/CAM dentures and to find out any emergent themes besides: (1) patients’ reasons for choosing a specific denture pair; and (2) their experience of using a 3D-printed IMO. By adopting a descriptive approach, individual semi-structured interviews will be carried out to obtain an in-depth understanding of patients’ experiences and preferences\u0026nbsp;[50].\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eOutcome Assessment Timeline\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e1. Screening: The RA will invite potential participants, answer questions, and gather informed consent. The RA will complete a screening form checking eligibility criteria for all approached individuals. Panoramic radiographs will be requested, and recruitment will be conditional based on the results from the imaging (as in Exclusion Criteria).\u0026nbsp;As a piloting process, we collect\u0026nbsp;data on gender conformity by two questionnaires, the Conformity to Feminine Norms Inventory-45 and Conformity to Masculine Norms Inventory-30\u0026nbsp;[51, 52].\u003c/p\u003e\n\u003cp\u003e2. Baseline: Participants will return for baseline evaluation, \u003cu\u003eintraoral scanning\u003c/u\u003e, and collection of sociodemographic information (including gender questionnaires), medical and dental history (including patient experience with previous dentures). Participants will be asked to complete the MDSQ and OHIP-EDENT, and a dentist with experience in providing full dentures will apply the FAD instrument.\u003c/p\u003e\n\u003cp\u003e3. Delivery and denture adjustments: Immediately after the end of the delivery appointments, the FAD instrument will be applied for each denture pair (same dentist as on baseline). The adverse effects form will be completed at the same time, as well as during each post-delivery appointment, scheduled or not.\u003c/p\u003e\n\u003cp\u003e4. First follow-up (three months): Participants will complete the outcome data questionnaires, the MDSQ and OHIP-EDENT. We will administer both questionnaires with a tablet computer away from the clinical setting. In turn, we will complete the FAD and adverse effects form, as described in the previous paragraph plus the colorimetric evaluation of denture bases.\u003c/p\u003e\n\u003cp\u003e5.Second follow-up (six months):Same as in previous time point (questionnaires and colorimetric analysis). At the end of the trial, participants will choose which overdenture they wish to keep. When faced with a choice, one is presented with the choices and the associated costs, which allows for a rationale decision. This is particularly important as dentures are typically not covered by the health care provider. Then we will conduct individual semi-structured interviews about their experiences with the IMOs. The rich descriptive data obtained by qualitative interviews will help further explicate the quantitative findings. An experienced qualitative researcher will be responsible to conduct the interviews outside of the clinic using an interview guide with open-ended questions. Given the explanatory nature of this mixed-methods design, the interview guide will be created iteratively based on the quantitative outcomes which require further explanation. Each interview will be audio-recorded and transcribed verbatim.\u003c/p\u003e\n\u003cp\u003eAt baseline, we will register time (professional and patient) and materials use for cost analyses. The same procedures will be repeated during every appointment in the trial, scheduled or not.\u003c/p\u003e\n\u003cp\u003e6. Long-term follow-up:Once participants provide 6-month data and choose the denture pair they wish to keep, we will continue their follow-up. For those participants who have no preference for one specific pair, the last pair used will be kept. Then, we will schedule them for yearly appointments until five years, during which the same outcome data will be gathered. In the meantime, participants may contact the research team for unscheduled appointments. Any event such as maintenance and clinical complications, as well as time and procedures done, will be reported as part of collected outcome data.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eSample size estimation\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe planned enrollment comprises 26 participants, based on overall patient satisfaction. A minimal important difference of 10mm (10% of the VAS) was used for the estimation, as done in previous RCTs\u0026nbsp;[40, 53]. A standard deviation of 7.5mm was chosen for the difference in satisfaction\u0026nbsp;[54]. Considering a 2-sided alpha of 0.01 to compensate for the number of secondary outcomes and a power of 90%, the RCT requires n=21 for superiority hypothesis testing (i.e., the confidence interval for between-treatment differences would exclude zero)\u0026nbsp;[55].\u0026nbsp;The final sample size is drawn from including further 20% to the planned n to compensate for possible dropouts; although withdrawals will unlikely pass 10%\u0026nbsp;[40, 54, 56], additional participants may be lost due to aging-related issues (e.g., worsening of systemic diseases, and death).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAdherence to Protocol and Losses to Follow-Up\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003ePrevious studies by our group reveal high study adherence rates, with \u0026gt;90% wearing their full dentures over the course of six months\u0026nbsp;[40, 56-58]. This RCT provides variations of a treatment sought by participants at university clinics, with no major change in their routine. Subsequent follow ups following the end of this RCT will also elucidate adherence rates for longer periods. As much as possible, we set up the intervention schedule, follow-up and data collection to resemble traditional oral healthcare procedures. We will also have the RA communicate with the participants using their preferred communication method (e.g., phone, text, e-mail) to verify possible adverse events, such as pain under the denture base, that may require a rapid adjustment visit. Those events and consequent conducts will be reported as part of the outcome variable “5. Adverse effects”.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eAnalytical plan\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eQuantitative Analysis\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eWe will enter and analyze outcome data in a blind fashion at the end of data collection. The TC will enter data in spreadsheets by randomly coding the interventions as 1 and 2, and the data analyst will be unaware of their meaning until the end of statistical testing. Data will undergo descriptive analysis, with substantial deviations from normality leading to variable transformation. Generalized estimating equations (GEE) will be used to test the effect of interventions, follow-up time and gender as independent variables, with 95% confidence intervals. Other approaches to assess the primary outcome will involve the inclusion of age, baseline results and previous denture wearing in separate models, one covariate at a time.\u003c/p\u003e\n\u003cp\u003eResults will be evaluated according to the intention-to-treat principle. In the case of unbalanced missing data among interventions or loss of 5% (n \u0026gt; 2) or more of participants, different strategies will be attempted for imputing primary outcome data, as recommended by Dziura et al.\u0026nbsp;[59]; multiple imputation will be used for patient satisfaction based on least squares regression with at least five datasets. In the case of “missing not at random” (MNAR) data, analyses will be repeated after a baseline-observation-carried-forward approach (i.e., withdrawn participants will be considered as dissatisfied as prior to receiving dentures). A second analysis will be performed with imputed values and cross-checked.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eQualitative Analysis\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eOnce the interviews are completed and transcribed, we will use the MaxQDA software for thematic analysis. Transcripts will be cut into meaningful segments and coded. Analysis will initiate by a deductive coding strategy based on the interview questions and the theoretical framework of denture satisfaction\u0026nbsp;[37, 60]. Then, we will proceed by adopting an inductive analysis to add any emerging codes. By an iterative process, the coded segments will be regrouped into relevant themes linked to our study objectives\u0026nbsp;[61, 62]. Methodological rigor will be warranted in the study, including member checking before or during data analysis, to meet trustworthiness, credibility, and transferability\u0026nbsp;[63]. That is, the results of the study will be formally or informally discussed with participants. To enhance coding quality, the qualitative researcher and one of the team members will independently code two transcripts chosen at random and then meet to compare/revise the codes if needed. Lastly, the qualitative data will be integrated into quantitative data by an explanatory strategy.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eData management, monitoring, and auditing\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eTwo independent researchers will regularly review the collected data as part of a data monitoring committee. Additionally, McGill University's Research Ethics Board (REB) Office retains the authority to conduct an independent audit at any point in time.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eRisks, participant safety, and trial adherence\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThis study represents minimal safety risk for participants, since all procedures are comparable with nonsurgical oral healthcare (i.e., clinical exam, intraoral molding). The number of appointments to fabricate and adjust provided dentures is similar to what is done in standard practice, and all materials to be used are approved for patient use by Health Canada. Potential participants will receive a complete explanation of the RCT, including potential risks before invitation to sign the informed consent.\u003c/p\u003e\n\u003cp\u003eAll denture materials are licensed for patient use and sold in Canada and United States. This way, risks associated with treatment are the same expected for minor oral surgery and standard dental implants/dentures. Participants may experience\u0026nbsp;sore spots under the dentures after the placement of retentive components. If this happens, the dentures will be adjusted as necessary. Allergic reactions to dental materials (such as the acrylic mixture used to bond components and denture) are rare but might also occur.\u003c/p\u003e\n\u003cp\u003eThe lower denture might break after the placement of the implant retentive components. If this happens during the study timeline, the dentures will be repaired at no cost.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eConfidentiality\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eEach participant's quantitative and qualitative data will be assigned an identification code to ensure confidentiality. The information connecting participants' identities to the codes will be securely stored in a password-protected file and computer. The final research forms, x-rays, and collected data will be sent to the primary investigator’s office and stored for 25 years for the exclusive objectives of this study and then destroyed. These will be kept secure by a password to which only the principal doctor will have access.\u003c/p\u003e\n\n\n\u003ch3\u003eDissemination and knowledge transfer\u003c/h3\u003e\n\u003cp\u003eKnowledge translation will target (i) the scientific community, and (ii) the public health and professional sectors. For the first, the team will publish reports in high-impact dental journals, as done with our previous clinical studies [57, 64]. The group will present results in scientific conferences aiming at dental professionals and researchers, as well as industry professionals, including the General Session of the International Association for Dental Research (IADR). For the second, our team will describe clinical and laboratory procedures as appendices of our scientific papers, besides a short book and YouTube videos, both directed to clinicians. The results of this study will be used to develop continuing education courses and webinars that explain the use of digital dentures based on our experiences and research findings. In addition, we will produce patient education materials, including a brochure and a video that describe the potential benefits and limitations of CAD/CAM technology for denture fabrication.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eDespite promising results, there is a scarcity of RCTs comparing CAD/CAM to conventional full denture fabrication methods, either implant-retained or conventional [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. As of March 2018, only two clinical studies have compared full dentures fabricated by CAD/CAM and conventional methods [\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e]. Both of these studies were non-randomized, with one based on treatment provided by dental students [\u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e] and the other considering surrogate measures [\u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e67\u003c/span\u003e]. A recent systematic review (updated: Oct-2019) confirms that CAD/CAM technologies produce dentures that fit intraoral tissues better than conventional methods [\u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e68\u003c/span\u003e]. That review was restricted to \u003cem\u003ein vitro\u003c/em\u003e studies, however. To appraise the state of the current literature regarding digital removable dentures, we re-ran the electronic search strategies of those reviews and found no cross-over clinical trial comparing CAD/CAM to conventional implant-retained dentures. Amongst those newly published comparative studies on CAD/CAM conventional dentures, two were prospective clinical studies [\u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e, \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e69\u003c/span\u003e], two were retrospective studies [\u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e70\u003c/span\u003e, \u003cspan citationid=\"CR71\" class=\"CitationRef\"\u003e71\u003c/span\u003e], one was cross-sectional [\u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e72\u003c/span\u003e] (all five conducted in student clinics), and one was a non-randomized trial [\u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e73\u003c/span\u003e], besides one RCT on conventional dentures made with a closed workflow (Dentca) [\u003cspan citationid=\"CR74\" class=\"CitationRef\"\u003e74\u003c/span\u003e]. Besides, no study has so far explored patient experiences with the CAD/CAM dentures. Given the impact of dental prostheses on the oral health of edentulous patients, it is essential to document the clinical and patient-reported performance of digitally fabricated dentures.\u003c/p\u003e \u003cp\u003eDetermining the potential benefits of CAD/CAM full dentures for seniors demands high-quality comparative evidence (i.e. RCT). This proposal is the first step to determine the advantages and limitations of that novel technology in treating the elderly with implant overdentures. Utilizing qualitative methods allows for a comprehensive exploration of patients' experiences, as evidenced by a previous study conducted by our team, which examined the reasons for declining treatment with implant overdentures [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. Employing a mixed-methods approach will integrate the quantitative findings from the clinical trial by offering an in-depth interpretation of patient perspectives through qualitative methods [\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAnticipated outcomes are expected to hold significant relevance for clinicians administering implant-assisted treatment to edentate patients. The resulting guidelines and recommendations have the potential to enhance dental prosthetic care for the edentate elderly population, a substantial portion of whom face challenges accessing more intricate treatment modalities.\u003c/p\u003e \u003cp\u003eResults will be important to guide public health systems and practitioners in the adoption of CAD/CAM to streamline denture provision. Better outcomes will enhance the potential access to care by edentulous seniors; government-subsidized programs, such as the recently launched Canadian Dental Care Plan for seniors, will be able to provide IMOs with lower costs and/or fewer restrictions. Less appointments and better infection control will also reduce risks for elders to contract diseases such as COVID-19 and flu-like infections in the dental setting. Possible remote care (virtual try-in of new dentures, ordering remakes at distance) also reduces infection risk. Better knowledge of patient perceptions of CAD/CAM IMOs will highlight the potential barriers and opportunities for using digital prostheses in dental practice. It will also help understand if the CAD/CAM technology has reached its goal of offering a superior/cost-effective treatment.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eTrial Status\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eClinicalTrials.gov, NCT06155630, Registered on 04 December 2023. Recruiting began January 2024. Estimated date of recruitment completion: September 2024.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDana Jafarpour is the recipient of Vanier Canada Graduate Scholarship for this protocol.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis project will be supported by a grant from the ITI Foundation, Switzerland (Grant No.\u0026nbsp;1744-2023) (Additional file 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFor depositing research data, we might deposit anonymized datasets in the McGill Dataverse repository upon request. According to McGill, all data are stored securely on servers located in Canada. The anonymized data may be published or shared during scientific meetings; however, it will not be possible to identify the participants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eRFS designed and will coordinate the trial. DJ drafted the manuscript and will execute the trial.\u0026nbsp;NE helped to draft this manuscript and will help with the clinical interventions. CB contributed with the study design and is overseeing the qualitative data gathering and analysis. SE contributed with the study design and is overseeing the economic data collection and analysis. SAN is assisting in the prosthetic stages and integration phase/knowledge translation. TS has advised in the data analysis plan. JSF provided important contributions to study design and drafted this manuscript. EZ will assist with knowledge transfer and assessment of material performance. All authors revised and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBefore enrolling in this trial, all participants will be required to give informed written consent and will be made aware of their right to withdraw at any point. Only in this case will unblinding be permissible. The consent process, study documentation, and the entire trial will adhere to the guidelines outlined in the Tri-Council Policy Statement\u0026nbsp;[75]. The McGill University REB Office approved this protocol under the reference A00-M29-23B (22-07-089). Ethical approval documents can be found in\u0026nbsp;Additional file 3.\u0026nbsp;A version of this protocol has also been registered in the Clinicaltrials.gov registry under the identifier NCT03126942.\u003c/p\u003e\n\u003cp\u003eAny amendments or modifications to the protocol during the trial will be formally communicated to the REB Office. If approved, these changes will be documented on Clinicaltrials.gov and disclosed to participants, allowing them time to consider continued participation.\u003c/p\u003e\n\u003cp\u003eParticipants will be officially enrolled in the trial only after obtaining a signed informed consent form (Additional file 4).\u0026nbsp;A researcher will explain the study\u0026apos;s aims and nature to each participant before they sign the consent form. It will be clarified that participation is voluntary, and participants are free to withdraw from the study at any time without providing a reason.\u003c/p\u003e\n\u003cp\u003eCompensation for participants will cover the cost of transportation to data collection appointments, including the baseline assessment. Participants will receive implant overdenture treatment at no cost, along with maintenance during the follow-up period.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eCardoso M, Balducci I, Telles DM, Louren\u0026ccedil;o EJV, Nogueira J\u0026uacute;nior L. Edentulism in Brazil: trends, projections and expectations until 2040. 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J Dent Res. 2015;94(10):1376\u0026ndash;84.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSischo L, Broder HL. Oral health-related quality of life: what, why, how, and future implications. J Dent Res. 2011;90(11):1264\u0026ndash;70.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAllen F, Locker D. A modified short version of the oral health impact profile for assessing health-related quality of life in edentulous adults. Int J Prosthodont. 2002;15(5):446\u0026ndash;50.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJohn MT, Feuerstahler L, Waller N, Baba K, Larsson P, Celebic A, Kende D, Rener-Sitar K, Reissmann DR. Confirmatory factor analysis of the Oral Health Impact Profile. J Oral Rehabil. 2014;41(9):644\u0026ndash;52.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSouza RF, Leles CR, Guyatt GH, Pontes CB, Della Vecchia MP, Neves FD. Exploratory factor analysis of the Brazilian OHIP for edentulous subjects. J Oral Rehabil. 2010;37(3):202\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnastassiadou V, Naka O, Heath MR, Kapari D. Validation of indices for functional assessment of dentures. Gerodontology. 2002;19(1):46\u0026ndash;52.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCorrigan PJ, Basker RM, Farrin AJ, Mulley GP, Heath MR. The development of a method for functional assessment of dentures. Gerodontology. 2002;19(1):41\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAl-Qarni FD, Goodacre CJ, Kattadiyil MT, Baba NZ, Paravina RD. Stainability of acrylic resin materials used in CAD-CAM and conventional complete dentures. J Prosthet Dent. 2020;123(6):880\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDella Vecchia MP, Leles CR, Cunha TR, Ribeiro AB, Sorgini DB, Muglia VA, Reis AC, Albuquerque RF Jr., de Souza RF. Mini-Implants for Mandibular Overdentures: Cost-Effectiveness Analysis alongside a Randomized Trial. JDR Clin Trans Res. 2018;3(1):47\u0026ndash;56.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ede Resende GP, Nogueira TE, Leles CR. Effectiveness of a simplified method for final impression in complete denture treatment: A pragmatic clinical trial. Gerodontology. 2019;36(4):365\u0026ndash;73.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLesaffre E, Feine J, Leroux B, Declerck D. Statistical and methodological aspects of oral health research. Wiley Online Library; 2009.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLevant RF, McDermott R, Parent MC, Alshabani N, Mahalik JR, Hammer JH. Development and evaluation of a new short form of the Conformity to Masculine Norms Inventory (CMNI-30). J Couns Psychol. 2020;67(5):622\u0026ndash;36.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eParent MC, Moradi B. An abbreviated tool for assessing feminine norm conformity: psychometric properties of the Conformity to Feminine Norms Inventory-45. Psychol Assess. 2011;23(4):958\u0026ndash;69.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEllis JS, Burawi G, Walls A, Thomason JM. Patient satisfaction with two designs of implant supported removable overdentures; ball attachment and magnets. Clin Oral Implants Res. 2009;20(11):1293\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ede Souza RF, Bedos C, Esfandiari S, Makhoul NM, Dagdeviren D, Abi Nader S, Jabbar AA, Feine JS. Single-implant overdentures retained by the Novaloc attachment system: study protocol for a mixed-methods randomized cross-over trial. Trials. 2018;19(1):243.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJulious SA. Sample sizes for clinical trials with normal data. Stat Med. 2004;23(12):1921\u0026ndash;86.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCunha TR, Della Vecchia MP, Regis RR, Ribeiro AB, Muglia VA, Mestriner W Jr., de Souza RF. A randomised trial on simplified and conventional methods for complete denture fabrication: masticatory performance and ability. J Dent. 2013;41(2):133\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ede Souza R, Jabbar A, Jafarpour D, Bedos C, Esfandiari S, Makhoul N, Dagdeviren D, Abi Nader S, Feine J. Single-implant overdentures retained by a novel attachment: A mixed methods crossover randomized clinical trial. JDR Clin Trans Res. 2024;9(1):27\u0026ndash;41.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlbuquerque IS, Regis RR, de Souza RF, Gurgel KF, Silva PG, Pinto-Fiamengui LMS, Freitas-Pontes KM. Is a two-step impression mandatory for complete denture fabrication on the severely resorbed mandible? 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ANS Adv Nurs Sci. 1986;8(3):27\u0026ndash;37.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDe Souza R, Ribeiro A, Della Vecchia M, Costa L, Cunha T, Reis ACd, Albuquerque R Jr. Mini vs. standard implants for mandibular overdentures: a randomized trial. J Dent Res. 2015;94(10):1376\u0026ndash;84.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJaneva NM, Kovacevska G, Elencevski S, Panchevska S, Mijoska A, Lazarevska B. Advantages of CAD/CAM versus Conventional Complete Dentures - A Review. Open Access Maced J Med Sci. 2018;6(8):1498\u0026ndash;502.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKattadiyil MT, Jekki R, Goodacre CJ, Baba NZ. Comparison of treatment outcomes in digital and conventional complete removable dental prosthesis fabrications in a predoctoral setting. J Prosthet Dent. 2015;114(6):818\u0026ndash;25.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlHelal A, AlRumaih HS, Kattadiyil MT, Baba NZ, Goodacre CJ. Comparison of retention between maxillary milled and conventional denture bases: A clinical study. J Prosthet Dent. 2017;117(2):233\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang C, Shi YF, Xie PJ, Wu JH. Accuracy of digital complete dentures: A systematic review of in vitro studies. J Prosthet Dent 2020.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSrinivasan M, Schimmel M, Naharro M, C ON, McKenna G, Muller F. CAD/CAM milled removable complete dentures: time and cost estimation study. J Dent. 2019;80:75\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eArakawa I, Al-Haj Husain N, Srinivasan M, Maniewicz S, Abou-Ayash S, Schimmel M. Clinical outcomes and costs of conventional and digital complete dentures in a university clinic: A retrospective study. J Prosthet Dent 2021.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim TH, Huh JB, Lee J, Bae EB, Park CJ. Retrospective Comparison of Postinsertion Maintenances Between Conventional and 3D Printed Complete Dentures Fabricated in a Predoctoral Clinic. J Prosthodont. 2021;30(S2):158\u0026ndash;62.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eClark WA, Brazile B, Matthews D, Solares J, De Kok IJ. A Comparison of Conventionally Versus Digitally Fabricated Denture Outcomes in a University Dental Clinic. J Prosthodont. 2021;30(1):47\u0026ndash;50.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDrago C, Borgert AJ. Comparison of nonscheduled, postinsertion adjustment visits for complete dentures fabricated with conventional and CAD-CAM protocols: A clinical study. J Prosthet Dent. 2019;122(5):459\u0026ndash;66.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOhara K, Isshiki Y, Hoshi N, Ohno A, Kawanishi N, Nagashima S, Inoue M, Kubo D, Yamaya K, Inoue E et al. Patient satisfaction with conventional dentures vs. digital dentures fabricated using 3D-printing: A randomized crossover trial. J Prosthodont Res 2022.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTCPS-2: Canadian Institutes of Health Research, Natural Sciences and Engineering Research Council of Canada, and Social Sciences and Humanities Research Council of Canada. Tri-Council Policy Statement: Ethical Conduct for Research Involving Humans 2014.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"trials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"trls","sideBox":"Learn more about [Trials](http://trialsjournal.biomedcentral.com/)","snPcode":"13063","submissionUrl":"https://www.editorialmanager.com/trls","title":"Trials","twitterHandle":"MedicalEvidence","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"3D printing, CAD/CAM, mandibular overdenture, Costs and cost analysis, Cross-over studies, Dental care for aged, Edentulous mouth, Implant-supported dental prosthesis, Patient satisfaction, Removable prosthodontics","lastPublishedDoi":"10.21203/rs.3.rs-3873159/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3873159/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eComplete tooth loss is a significant global oral health issue, particularly impacting older individuals with lower socioeconomic status. Computer-assisted technologies enhance oral healthcare access by the elderly. Despite promising \u003cem\u003ein vitro\u003c/em\u003e reports on digital denture materials, evidence from randomized clinical trials (RCTs) is lacking to verify their performance. This cross-over RCT will investigate whether 3D-printed implant-retained mandibular overdentures (IMO) are more satisfactory for edentulous seniors than those made through traditional methods.\u003c/p\u003e\u003ch2\u003eMethods/design:\u003c/h2\u003e \u003cp\u003eWe will recruit 26 completely edentulous participants (any sex/gender) based on the following eligibility criteria: age\u0026thinsp;\u0026ge;\u0026thinsp;60 years, no tooth extraction in the past 12 months, two implants in the lower jaw, and need for new dentures in both jaws. Each participant will receive two denture pairs, either manufactured by 3D printing or traditionally, to be worn in a random order. A timeline of three months with each denture pair will be considered for outcome assessment (total: six months). Patient satisfaction with dentures will be measured by the McGill Denture Satisfaction Questionnaire. We will evaluate other patient-reported outcomes (including oral health-related quality of life), as well as clinician-assessed quality and cost. At the end of the trial, participants will choose which denture pair they wish to keep, and interviewed about their experiences with the 3D-printed IMO. The quantitative and qualitative data will be incorporated through an explanatory mixed-methods strategy. A final quantitative assessment will happen after 12 months with the preferred IMO to assess the long-term performance and maintenance needs.\u003c/p\u003e\u003ch2\u003eDiscussion\u003c/h2\u003e \u003cp\u003eThis mixed-methods RCT will explore patient experiences with 3D-printed IMOs, aiming to assess the potential for altering clinical practice and dental public health policies. Our results will inform policies by showing whether 3D printing offers comparable outcomes at lower costs, facilitating greater access to oral care for the elderly.\u003c/p\u003e\u003ch2\u003eTrial registration:\u003c/h2\u003e \u003cp\u003eClinicalTrials.gov, NCT06155630, Registered on 04 December 2023. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://classic.clinicaltrials.gov/ct2/show/NCT06155630\u003c/span\u003e\u003cspan address=\"https://classic.clinicaltrials.gov/ct2/show/NCT06155630\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e","manuscriptTitle":"3D printing vs traditional workflow for the fabrication of mandibular implant overdentures: Study protocol for a mixed-methods cross-over RCT","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-19 15:24:59","doi":"10.21203/rs.3.rs-3873159/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Minor revision","date":"2024-03-25T04:53:39+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2024-03-15T15:16:34+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-03-15T15:07:27+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-03-15T11:47:13+00:00","index":"","fulltext":""},{"type":"submitted","content":"Trials","date":"2024-02-15T13:15:47+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"trials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"trls","sideBox":"Learn more about [Trials](http://trialsjournal.biomedcentral.com/)","snPcode":"13063","submissionUrl":"https://www.editorialmanager.com/trls","title":"Trials","twitterHandle":"MedicalEvidence","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"40ec418c-ebc3-4f80-8f16-0815deab190b","owner":[],"postedDate":"March 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-04-16T15:51:08+00:00","versionOfRecord":{"articleIdentity":"rs-3873159","link":"https://doi.org/10.1186/s13063-024-08097-7","journal":{"identity":"trials","isVorOnly":false,"title":"Trials"},"publishedOn":"2024-04-16 15:51:08","publishedOnDateReadable":"April 16th, 2024"},"versionCreatedAt":"2024-03-19 15:24:59","video":"","vorDoi":"10.1186/s13063-024-08097-7","vorDoiUrl":"https://doi.org/10.1186/s13063-024-08097-7","workflowStages":[]},"version":"v1","identity":"rs-3873159","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3873159","identity":"rs-3873159","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}