Effect of MMP inhibitor pre-treatment on the fracture resistance of single versus multiple pin post endodontic restorations: an in vitro study

Effect of MMP inhibitor pre-treatment on the fracture resistance of single versus multiple pin post endodontic restorations: an in vitro study | 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 Effect of MMP inhibitor pre-treatment on the fracture resistance of single versus multiple pin post endodontic restorations: an in vitro study Vaishnavi Dhok, Sanket Jadhav, Pratik More, Deepyanti Dubey, Asmita Sonawane, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8170577/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 15 You are reading this latest preprint version Abstract Background: Bond degradation by dentin MMPs can reduce the longevity of post endodontic restorations. Chlorhexidine may improve bond stability, but its effect with different post systems is not well established. This study assessed whether MMP inhibitor pretreatment enhances fracture resistance in single and multiple pin post restorations. Materials and Methods: Forty single-rooted maxillary premolars were extracted, and their crowns were sectioned at the cementoenamel junction (CEJ), followed by endodontic treatment. After the post space was prepared via a standardized technique, the samples were distributed into four groups: Group 1 , single-fiber post with no dentin pretreatment; Group 2 , single-fiber post with dentin pretreated with a matrix metalloprotein (MMP) inhibitor; 2 %, chlorhexidine solution ( Globus Medisys , Vadodara, Gujarat, India ); Group 3 , multiple Dentapreg pins ( Dentapreg ; ADM , Brno , Czech Republic ) without dentin pretreatment; and Group 4 , multiple Dentapreg pins with dentin pretreated with a MMP inhibitor. Fracture resistance was assessed after post placement and core build-up via a universal testing machine, in which a 45° compressive load was applied at 1 mm/min until failure. The data were analyzed via one-way ANOVA and Tukey’s post hoc test, with significance set at P < 0.05. Results: Group 4 presented the highest mean fracture resistance, followed by Groups 3, 2, and 1, with statistically significant differences ( P < 0.05). Conclusion: Within the limits of this study, the evidence indicated that dentapreg pin posts exhibited greater fracture resistance than single-fiber-reinforced posts did. Additionally, the application of 2% chlorhexidine after etching significantly increased the fracture resistance strength. Clinical significance: Understanding how MMP inhibition influences the performance of different post systems can help clinicians make more informed material choices. This may ultimately support the selection of restoration techniques that offer greater reliability and longevity in endodontically treated teeth. Chlorhexidine digluconate Dentapreg multiple pin posts Fiber-reinforced posts Fracture resistance test MMP inhibitor Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction When significant coronal tooth structure is lost, an endodontic post is often used to restore the tooth, onto which a full crown is cemented [ 1 ]. An optimal endodontic post must exhibit precise adaptation, compatibility with biological tissues, and strong resistance to tensile and fatigue stresses to efficiently disperse chewing forces. While an endodontic post helps support coronal restoration, it may also increase the likelihood of root fracture [ 2 ]. According to vartak et al. [ 3 ], approximately 20% of root canal-treated teeth restored with radicular posts may develop vertical root fractures. Therefore, careful selection of post endodontic and precise clinical techniques is crucial for the success of post endodontic restorations. Clinical studies have shown that fiber-reinforced composite (FRC) posts have a success rate of 95% to 99% in restorative dental procedures [ 4 ]. These posts are favored for their appealing appearance, resemblance to natural dentin, and superior mechanical performance [ 2 ]. Nevertheless, prefabricated FRC posts may not match the shape of the root canal, requiring additional shaping that can compromise fracture resistance. In large or irregular canals, excessive cement is needed, which may weaken the bond due to the lower mechanical strength and polymerization shrinkage (1.2–6%) of the composite resin cement, increasing failure risk [ 5 ]. Dentapreg® ( Dentapreg; ADM, Brno, Czech Republic ) offers a novel, minimally invasive fiber pin post system intended for the restoration of endodontically treated teeth. Each pin is 20 mm long and has a diameter of 0.45 mm, allowing flexibility and adaptation within the root canal. Made from unidirectional S2-glass fibers, ultrathin yet firm pins are procured and flexible, allowing them to conform to the root’s curvature without additional instrumentation. This flexibility maintains the tooth’s natural biomechanics, reducing the risk of root fractures [ 6 ]. Over time, endogenous matrix metalloproteinases (MMPs) contribute to the enzymatic breakdown of the collagen within the hybrid layer, compromising the strength and durability of the adhesive dentin bond. The application of MMP inhibitors has been shown to effectively preserve this interface, resulting in improved adhesion and increased resistance to fracture [ 7 ]. Chlorhexidine, a widely used bisbiguanide, is recognized not only for its potent antimicrobial properties but also for its role as an effective inhibitor of matrix metalloproteinases (MMPs) [ 8 ]. Matrix metalloproteinases (MMPs) are naturally occurring enzymes that significantly contribute to the breakdown of the collagen matrix within dentin, particularly in the hybrid layer created between dentin and adhesive resin. The deterioration of the hybrid layer is a key contributor to the gradual decline in bond strength, which can ultimately result in the failure of dental restorations [ 9 ]. Limited data exist regarding the effectiveness of the Dentapreg multiple pin post system in reinforcing root canal-treated teeth, particularly when combined with MMP inhibitors. The current study was designed to assess the effect of MMP inhibitor pretreatment on the fracture resistance of root canal-treated teeth restored with either single or multiple pin posts. The null hypothesis proposed that MMP inhibitor application would not significantly influence fracture resistance across the tested systems. 2. Material and methods 2.1 Ethics approval statement: Ethical approval was obtained from the institute with reference number YDCH/Ethic/A2/2023-2024, and the study was performed accordingly. All procedures were performed in accordance with the ethical standards of the institutional ethics committee and the Declaration of Helsinki. 2.2 Selection of teeth: This study involved forty extracted maxillary premolars with a single root and fully formed apices obtained for periodontal or orthodontic indications.Written informed consent was obtained from all participants for tooth extraction and for the use of their extracted teeth for research purposes .Teeth exhibiting caries, fractures, prior root canal treatment, or anatomical anomalies were excluded. All the samples were ultrasonically cleaned to eliminate any remaining soft tissue and then immersed in normal saline at room temperature (24–28°C) to maintain hydration throughout the study period. 2.3 Sample preparation: The samples were sectioned just below the CEJ via a diamond disc (Mani, Tochigi, Japan) under water cooling and standardized to 12 ± 1 mm. The pulp tissue was removed, and the working length was set to 1 mm short of the apex via a size 10 K file (Mani, Tochigi, Japan). Canals were shaped with the ProTaper rotary system (Dentsply Maillefer, Ballaigues, Switzerland) up to size F3 via the crown-down technique. Irrigation after each file was performed with 2 ml of 5.25% NaOCl (Prime Private Limited, Maharashtra, India) and saline (Vishal Private Limited, India) via a 30-gauge side vented needle. The final irrigation method included NaOCl, 17% EDTA (Prime Private Limited, Maharastra, India), and saline. After drying with paper points, canals were obtained via F3 gutta percha (Dentsply Maillefer, Ballaigues, Switzerland) with AH Plus sealer (Dentsply Maillefer, Ballaigues, Switzerland). Coronal sealing was performed with Cavit G (3 M ESPE), and the samples were incubated at 37°C in 100% humidity for 24 hours to ensure complete setting. 2.4 Post space preparation: Peeso reamers (Mani, Tochigi, Japan) up to size 2 were used to prepare post spaces to a depth of 7 mm, ensuring that 5 mm of gutta-percha remained intact in the apical portion. Following saline irrigation and drying with sterile paper points, the samples were randomly allocated into four experimental groups (n = 10). Group 1: Single-fiber post without dentin pretreatment Group 2: Single-fiber post with dentin pretreated with an MMP inhibitor Group 3: Multiple dentin pins without dentin pretreatment Group 4: Multiple dentin pins with dentin pretreated with an MMP inhibitor Groups 1 and 3 were restored via single-fiber reinforced posts (Selfpost, Medicept UK Ltd.) (Figure 1) without surface pretreatment, and 37% phosphoric acid (3 M ESPE) was applied to the post spaces for 15 s, followed by thorough rinsing and drying. Scotchbond Universal Adhesive (3MESPE, Seefeld, Germany) was applied, and the samples were air dried and light cured. Dual-cure resin cement (RelyX Ultimate, 3 M ESPE) was introduced into the canals, and the posts were positioned with finger pressure (Figure 2). Excess cement was removed, followed by 5 minutes of self-curing and 30 seconds of light curing. Posts were trimmed to 6 mm above the root, and core build-up was completed via Filtek Z350 composite resin (3 M ESPE, St. Paul, MN, USA), which was standardized to 6 mm using a Vernier caliper (Altraco Inc., Sausalito, California, USA). Groups 2 and 4, restored with multiple pin posts ( Dentapreg ; ADM , Brno , Czech Republic ) (Figure 3), underwent the same etching procedure as the other groups did. A 2% chlorhexidine solution ( Globus Medisys , Vadodara, Gujarat, India ) was dispensed into a dappen dish, and the canal walls were coated with a saturated microbrush or paper point with gentle scrubbing motion for 60 seconds, rewetting the applicator as needed to maintain contact; excess solution was then removed by blotting with dry paper points until only a sheen of moisture remained, without rinsing. Scotchbond Universal adhesive was applied, and the samples were air-dried and light-cured. Dual-cure resin cement was placed in the canal, and multiple pin posts were inserted according to the manufacturer’s guidelines (Figure 4). Following 20 seconds of light curing, the posts were trimmed to a size of 6 mm coronally, and core build-up was completed as described previously. All the samples were mounted in self-curing acrylic resin (DPI, Jabalpur, India) blocks within 2 cm diameter plastic rings, with the resin positioned 1 mm apical to the buccal cementoenamel junction (CEJ). 2.5 Fracture Resistance Test: Fracture resistance was evaluated with the help of a universal testing machine (ACME Engineers, India), which applied a compressive load with a 5 mm round-tip probe at a 45° angle to the tooth’s long axis at a crosshead speed of 1 mm/min. The fracture force was measured in newtons (N). 2.6 Statistical analysis: Fracture load values (in N) were recorded in Microsoft Excel 2010 and reported as the mean ± standard deviation for each group. One-way ANOVA followed by Tukey’s post hoc test was used for statistical analysis (P < 0.05), and data visualization was performed via bar charts (Figure 5). SPSS version 19 was used for all analyses. 3. Results The results showed that Group 1 (single-fiber post without dentin pretreatment) had the lowest mean fracture resistance among all the groups. Group 4 (multiple Dentapreg pins with MMP inhibitor pretreatment) demonstrated the highest fracture resistance, followed by Group 3 (multiple Dentapreg pins without pretreatment) and Group 2 (single fiber post-MMP inhibitor pretreatment) (Table 1, Figure 5). Tukey’s post hoc test indicated significant differences across all groups (P < 0.001), except between Groups 2 and 3, for which there was no statistically significant difference. (Table 2) Table 1: Descriptive statistics for the fracture load (N) among the four groups Groups N Minimum Maximum Mean Std. Deviation Group 1 : 10 239.16 373.12 276.1860 47.06171 Group 2 : 10 290.32 474.44 399.6340 57.15834 Group 3 : 10 295.32 540.67 433.5260 72.70173 Group 4 : 10 446.88 673.22 575.3070 67.70996 Table 2 : Pairwise comparison of the fracture load (N) among the four groups according to Tukey’s post hoc test Dependent Variable: Fracture load (N) Tukey HSD (I) Groups (J) Groups Mean Difference (I-J) Std. Error Sig. p value 95% Confidence Interval Lower Bound Upper Bound Group 1 Group 2 -123.44800 * 27.70565 <0.001* -198.0656 -48.8304 Group 1 Group 3 -157.34000 * 27.70565 <0.001* -231.9576 -82.7224 Group 1 Group 4 -299.12100 * 27.70565 <0.001* -373.7386 -224.5034 Group 2 Group 3 -33.89200 27.70565 <0.001* -108.5096 40.7256 Group 2 Group 4 -175.67300 * 27.70565 <0.001* -250.2906 -101.0554 Group 3 Group 4 -141.78100 * 27.70565 <0.001* -216.3986 -67.1634 *. The mean difference is significant at the 0.05 level. 4. Discussion Posts should effectively transmit and distribute stress to minimize the risk of root fractures. This study assessed and compared the fracture resistance of endodontically treated teeth reinforced with either a single-fiber post or multiple pin posts, with and without pretreatment with an MMP inhibitor. Single rooted maxillary premolars were chosen for this study because their anatomical structure, including narrow roots and reduced dentin thickness, makes them particularly vulnerable to vertical root fractures. This susceptibility becomes more pronounced after endodontic treatment because of the loss of tooth structure and altered stress distribution under occlusal loading. Therefore, they serve as an ideal model for evaluating the fracture resistance of various post endodontic restorative techniques [ 10 ]. The results revealed a marked improvement in fracture resistance in teeth restored with multiple pin posts combined with MMP inhibitor pretreatment compared with those restored with a single fiber post without any pretreatment. This may be attributed to the greater modulus of elasticity provided by multiple pins with smaller cross-sectional areas but similar lengths to single posts [ 2 ]. Additionally, multiple pin posts likely offer improved adaptation, forming a more unified structure with dentin and cement [ 11 ]. Luting cement also contributes to the overall flexibility and stress distribution of the post system. Resin cement has a modulus of elasticity similar to that of dentin, and its bonding to intraradicular dentin helps form an internal reinforcing layer, thereby enhancing the overall structural integrity [ 12 ]. Multiple pin posts provide a larger surface area than a single post does, reducing the stress concentration at the cement–dentin interface. This broader distribution helps limit crack initiation by dispersing tensile forces over a wider area [ 13 ]. The multipost approach not only improves adaptation but also may reduce the risk of post dislodgment and increase resistance to long-term cyclic loading [ 14 ]. Thus, using multiple posts or customizing a single post to match the root canal anatomy may contribute to improved clinical outcomes. Maceri et al. [ 15 ] demonstrated that using multiple post restoration methods can significantly reduce stress concentrations, with a 27% decrease in von Mises stress under intrusive loads and a 20% reduction under oblique loads. Additionally, Rankine stress analysis revealed lower tensile stress in both the apical and cervical regions, indicating a decreased risk of root fracture. These results are consistent with those reported by Q. Li et al.[ 16 ], Frater et al.[ 17 ], Brackett et al.[ 18 ], Zheng et al.[ 19 ], and Moogi et al.[ 7 ], who reported that multiple pin post systems provide superior fracture resistance compared with single post restorations. In this study, Dentapreg multiple-fiber pin posts were utilized for the restoration of endodontically treated teeth. These posts contribute to reinforcing the remaining tooth structure by establishing a monoblock system, wherein the post, cement, and dentin act as a unified structure. Dentapreg posts are composed of unidirectional S-type glass fiber materials initially designed for the high strength and durability demands of aerospace applications, such as space shuttles. Each pin has a diameter of approximately 0.45 mm and is light-cured, providing a combination of firmness and flexibility. Their slim and adaptable design allows them to follow the natural curvature of the root canal, thus eliminating the necessity for additional canal enlargement or instrumentation [ 6 ]. These fiber pin posts offer enhanced retention through two primary mechanisms. First, micromechanical retention is achieved by increasing the number of posts within the canal, which contributes to better stress distribution and improved mechanical interlocking. Additionally, micromechanical retention is achieved through the adhesion of bonding agents to the root dentin, promoting better integration of the post system with the canal walls [ 11 ]. The samples were tested under an oblique load applied at a 45-degree angle to the tooth’s long axis—an approach recognized by Wandscher et al.[ 20 ] as one of the most challenging scenarios for assessing fracture resistance in endodontically treated teeth. This loading direction generates significant stress on the cervical region of teeth lacking a ferrule and imposes considerable shear forces at the interfaces between the post, luting agent, and radicular dentin. This setup simulates a worst-case occlusal loading condition, providing a stringent test of the durability and integrity of the restoration and remaining tooth structure [ 3 ]. Establishing a strong and stable bond between the adhesive and dentin is essential for ensuring the long-term success of tooth-colored restorations. In both the etch-and-rinse and self-etch systems, the acid etching step either demineralizes or modifies the mineral content of dentin, depending on the adhesive approach used. This exposes the collagen matrix, which is then infiltrated by adhesive monomers to form the hybrid layer [ 21 ]. Over time, the integrity of this adhesive‒dentin interface tends to deteriorate, primarily owing to the breakdown of the hybrid layer. This degradation is often linked to hydrolysis of the collagen network and breakdown of the hydrophilic resin components within the adhesive [ 22 ]. Matrix metalloproteinases (MMPs), which are naturally present in dentin, become activated under acidic conditions, such as during etching, and contribute significantly to the degradation of the exposed collagen, thereby compromising the bond strength at the interface [ 9 ]. To reduce collagen breakdown and increase the longevity of the adhesive–dentin bond, various improvements to traditional bonding protocols have been suggested. These include applying an extra hydrophobic resin layer, using multiple adhesive layers, improving solvent evaporation, prolonging the curing time, incorporating MMP inhibitors, and using an electric current to support monomer penetration [ 23 ]. These techniques have shown promising results in maintaining the hybrid layer, reinforcing the adhesive interface, and increasing the bond strength. The application of matrix metalloproteinase (MMP) inhibitors to dentin either after acid etching or as part of adhesive formulations has been shown to increase the durability of the adhesive interface, thereby improving the long-term performance of tooth-colored aesthetic restorations [ 24 ]. Among the various MMP inhibitors, chlorhexidine is widely recognized as the most effective. It is a cationic bisbiguanide compound known for its strong antibacterial properties and is frequently used as a root canal irrigant and in mouthwashes because of its sustained activity. Chlorhexidine inhibits MMPs through mechanisms such as chelation of metal ions or disruption of protein structure, thereby helping to maintain the hybrid layer and reduce enzymatic degradation [ 18 ]. Carrilho et al. [ 25 ] demonstrated the positive role of chlorhexidine in maintaining dentin bond strength by functioning as an MMP inhibitor, particularly when applied before adhesive bonding without rinsing. In this method, chlorhexidine interacts directly with the exposed collagen fibrils and becomes encapsulated by the adhesive resin, helping to protect the fibrils from degradation. Favetti et al. [ 13 ] reported a notably reduced failure rate within the hybrid layer, especially in its deeper sections, six months after treatment with chlorhexidine. These findings suggest that the increased bond strength in this group was linked to the preservation of the collagen matrix in the hybrid layer—most critically, in the deeper areas, where collagen is more vulnerable to enzymatic breakdown. Furthermore, Ricci et al. [ 26 ] reported from in vivo studies that chlorhexidine application did not compromise the immediate bond strength and may be effective in preventing early bond deterioration. Different concentrations of chlorhexidine (CHX) have been investigated to determine the most effective protocol for enhancing its performance. Among these methods, a 2% CHX solution applied for 60 s before primer application in adhesive systems has become the most commonly accepted method to inhibit MMP activity and help maintain bond strength over time [ 27 ]. On the basis of this widely endorsed protocol, the present study employed 2% CHX for 60 s prior to bonding. When applied before bonding and without rinsing, MMP inhibitors such as chlorhexidine (CHX) penetrate exposed collagen fibrils and become encapsulated by adhesive resins. This not only helps inhibit collagen degradation but also offers antimicrobial action and allows the rehydration of dried mineralized dentin [ 28 ]. As CHX does not negatively affect the immediate bond strength, its clinical use is recommended to increase the durability of the resin–dentin bond, [ 29 ] thereby contributing to improved fracture resistance. The findings of this study may have limited clinical applicability, as fracture resistance was evaluated via a single-point load. Additional in vitro and in vivo studies are needed to confirm these results and support their relevance to long-term clinical performance. Conclusion Within the limitations of this study, Dentapreg multiple-fiber pin posts demonstrated significantly greater fracture resistance than single glass-fiber-reinforced posts did. Moreover, pretreatment with 2% chlorhexidine, an MMP inhibitor, significantly improved fracture resistance, regardless of the type of drug used. Abbreviations MMP – Matrix Metalloprotein CHX- Chlorhexidine SD- Standard Deviation Declarations Ethics approval and consent to participate: Not Applicable Consent for publication: Not Applicable Availability of data and materials: The datasets used during the current study are available from the corresponding author on reasonable request. Competing interests: The authors declare that they have no competing interests Funding: The authors have no financial relationships relevant to this article to disclose. Authors' contributions : Conceptualization, Data curation, Formal analysis, funding acquisition: Dhok VD; Investigation, Methodology, Project administration: Dubey D, Resource, Software: Jadhav SR. Supervision, Validation, Visualization: More PP, Sonawane AA. Writing - original draft: Dhok VD,Kshirsagar S; Writing - review & editing: All authors. All authors read and approved the final manuscript. Acknowledgements: Not Applicable Declaration of generative AI use: During the preparation of this work, the author(s) used ChatGPT (OpenAI, GPT-5.1) for language refinement and editing. After using this tool, the author(s) reviewed and edited the content as needed and take full responsibility for the published article. References Qing H, Zhu Z, Chao Y, Zhang W. In vitro evaluation of the fracture resistance of anterior endodontically treated teeth restored with glass fiber and zircon posts. J Prosthet Dent. 2007;97(2):93–8. Haralur SB, Al Ahmari MA, Alqarni SA, Althobati MK. The Effect of Intraradicular Multiple Fiber and Cast Posts on the Fracture Resistance of Endodontically Treated Teeth with Wide Root Canals. Biomed Res Int. 2018; 2018:1671498. Vartak MA, Hegde VR, Hegde SR, Fanibunda U. Fracture resistance and failure modes of endodontically treated permanent teeth restored with Ribbond posts vs other post systems: a systematic review and meta-analysis of in vitro studies. Restor Dent Endod. 2025;50(1):e5. Makade CS, Meshram GK, Warhadpande M, Patil PG. A comparative evaluation of fracture resistance of endodontically treated teeth restored with different post core systems - an in vitro study. J Adv Prosthodont. 2011;3(2):90–5. Rezaei Dastjerdi M, Amirian Chaijan K, Tavanafar S. Fracture resistance of upper central incisors restored with different posts and cores. Restor Dent Endod. 2015;40(3):229–35. Dhok VD, Khanvilkar U, Moogi PP, Bandekar SD, Kshirsagar S, Jadhav SR. A comparative evaluation of the effect of matrix metalloproteinase inhibitor on the fracture resistance of endodontically treated teeth restored with Everstick-reinforced composite resin: An in vitro study. J Conserv Dent Endod. 2024;27:1104–9. Prashant PM, Sonawane AA, Siddhesh DB, Shirin PK, Kalyani IA, Tryambake R, Pavan. Comparative evaluation of push-out bond strength of single and multiple fiber-reinforced posts cemented with dual-cure resin cement using different adhesive strategies: An in vitro study. Endodontology 35(1): p 18–23, Jan–Mar. 2023. Martina LP, Ebenezar AVR, Ghani MF, Narayanan A, Sundaram M. Mohan, Ajit George. An in vitro comparative antibacterial study of different concentrations of green tea extracts and 2% chlorhexidine on Enterococcus faecalis . Saudi Endodontic J 3(3): p 120–4, Sep–Dec 2013. Tandelilin RTC, Saini R. Dynamics of Matrix Metalloproteinases in the Oral Environment. Int J Exp Dent Sci. 2015;4(1):53–7. Zarow M, Vadini M, Chojnacka-Brozek A, Szczeklik K, Milewski G, Biferi V, D'Arcangelo C, De Angelis F. Effect of Fiber Posts on Stress Distribution of Endodontically Treated Upper Premolars: Finite Element Analysis. Nanomaterials (Basel). 2020;10(9):1708. Dentapreg® PINPost cured elastic & flexible pins. UK Dentistry Ltd. Available at: https://ukdentistry.co.uk/Dentapreg-PINPost-cured-elastic-flexible-pins (accessed 16 August 2025). Alwan NJ, Al-Askary RA. Analysis of fiber post–resin cement interfacial adaptation at different post regions using field emission scanning electron microscopy. Saudi Endodontic J 14(3): p 368–78, Sep–Dec 2024. Favetti M, Schroeder T, Montagner AF, Correa MB, Pereira-Cenci T, Cenci MS. Effectiveness of pretreatment with chlorhexidine in restoration retention: a 36-month follow-up randomized clinical trial. J Dent. 2017;60:44–9. de Moraes IQS, do Nascimento TG, da Silva AT, de Lira LMSS, Parolia A, Porto ICCM. Inhibition of matrix metalloproteinases: a troubleshooting for dentin adhesion. Restor Dent Endod. 2020;45(3):e31. Maceri F, Martignoni M, Vairo G. Mechanical behavior of endodontic restorations with multiple prefabricated posts: a finite-element approach. J Biomech. 2007;40(11):2386–98. Li Q, Xu B, Wang Y, Cai Y. Efects of auxiliary fber posts on endodontically treated teeth with fared canals. Oper Dent. 2011;36(4):380–9. Frater M, Forster A, Jantyik ´A, Braunitzer G, Nagy K, Grandini ´S. In vitro fracture resistance of premolar teeth restored with fbre-reinforced composite posts using a single or a multipost technique. Australian Endodontic J. 2017;43(1):16–22. Brackett WW, Tay FR, Brackett MG, Dib A, Sword RJ, Pashley DH. The effect of chlorhexidine on dentin hybrid layers in vivo. Operative dentistry 200 Mar; 32(2):107–11. Zheng P, Zaruba M, Attin T, Wiegand A. Effect of different matrix metalloproteinase inhibitors on microtensile bond strength of an etch-and-rinse and a self-etching adhesive to dentin. Oper Dent. 2015;40(1):80–6. Wandscher VF, Bergoli CD, Limberger IF, Ardenghi TM, Valandro LF. Preliminary results of the survival and fracture load of roots restored with intracanal posts: weakened vs nonweakened roots. Oper Dent. 2014;39:541–55. Stanislawczuk R, Amaral RC, Zander-Grande C, Gagler D, Reis A, Loguercio AD. Chlorhexidine-containing acid conditioner preserves the longevity of resindentin bonds. Oper Dent. 2009;34(4):481–90. Porciani PF, Vano M, Radovic I, Goracci C, Grandini S, García-Godoy F, Ferrari M. Fracture resistance of fiber posts: combinations of several small posts vs. standardized single post. Am J Dent. 2008;21(6):373–6. Bajaj R, Pawah S, Gupta A, Sikri A, Madan P. The Impact of Various Pretreatment Agents on Shear Bond Strength between Self-adhesive Resin Cement and Dentin: An In Vitro Study. 2023; 11 (1):19–21. Mazzoni A, Tjäderhane L, Checchi V, Di Lenarda R, Salo T, Tay FR, Pashley DH, Breschi L. Role of dentin MMPs in caries progression and bond stability. J Dent Res. 2015;94(2):241–51. Carrilho MR, Geraldeli S, Tay F, De Goes MF, Carvalho RM, Tjäderhane L, Reis AF, Hebling J, Mazzoni A, Breschi L, Pashley D. In vivo preservation of the hybrid layer by chlorhexidine. J Dent Res. 2007;86(6):529–33. Ricci HA, Sanabe ME, de Souza Costa CA, Pashley DH, Hebling J. Chlorhexidine increases the longevity of in vivo resin–dentin bonds. European Journal of Oral Sciences., Tuncer S, Demirci M, Balci S. Do matrix metalloproteinase inhibitors improve the bond durability of universal dental adhesives? Scanning. 2016;38(6):535–544. Soares CJ, Pereira CA, Pereira JC, Santana FR, do Prado CJ. Effect of chlorhexidine application on microtensile bond strength to dentin. Oper Dent. 2008 Mar-Apr;33(2):183–8. Inoue S, Carrilho M, Sugiyama T, et al. Inhibition of enzymatic degradation of adhesive-dentin interfaces. J Dent Res. 2009;88(6):537–42. Tekçe N, Tuncer S, Demirci M, Balci S. Do matrix metalloproteinase inhibitors improve the bond durability of universal dental adhesives? Scanning. 2016;38(6):535–44. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 13 Jan, 2026 Reviews received at journal 07 Jan, 2026 Reviews received at journal 05 Jan, 2026 Reviews received at journal 05 Jan, 2026 Reviewers agreed at journal 02 Jan, 2026 Reviewers agreed at journal 02 Jan, 2026 Reviewers agreed at journal 31 Dec, 2025 Reviews received at journal 28 Dec, 2025 Reviewers agreed at journal 26 Dec, 2025 Reviewers agreed at journal 26 Dec, 2025 Reviewers invited by journal 26 Dec, 2025 Editor invited by journal 04 Dec, 2025 Editor assigned by journal 04 Dec, 2025 Submission checks completed at journal 02 Dec, 2025 First submitted to journal 02 Dec, 2025 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. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8170577","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":566397132,"identity":"f46c046e-1f9e-4e92-a65a-ee4fc2abc425","order_by":0,"name":"Vaishnavi Dhok","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABBUlEQVRIiWNgGAWjYFACxgZmEMXGwGDGwHDAhrEBxOMBI+K0pBGjhYGBGUqDtByGa8EJDI4fbv5cuMMusY+BeduDD2fOy26XSGB88LaNQcYcl5YziW3SM88kJ7YxsJUbzrhx23jnjARmw7ltDDyWDdi1SDYktjHztjEbszHwmEnzfLiduOFGAps0L1CLwQEcWvofNn/mbauHaTkH0sL+G58WfonEBqCZh+UgWm4cANvCjF/LwzagluNybMxsZZIzziQb7+x52Cw555wETi1s/OmPgQ6r5pFvb94m8eGYnex29uSDH96U2djj0oIAsNgxYABHjQQh9UjAgAS1o2AUjIJRMDIAANcGVbKT7RWTAAAAAElFTkSuQmCC","orcid":"","institution":"Dr. D.Y.Patil Dental college and Hospital Dr. D.Y.Patil Vidyapeeth","correspondingAuthor":true,"prefix":"","firstName":"Vaishnavi","middleName":"","lastName":"Dhok","suffix":""},{"id":566397133,"identity":"0b66bc53-6fc0-4079-94d9-2cb3db625157","order_by":1,"name":"Sanket Jadhav","email":"","orcid":"","institution":"Dr. D.Y.Patil Dental college and Hospital Dr. D.Y.Patil Vidyapeeth","correspondingAuthor":false,"prefix":"","firstName":"Sanket","middleName":"","lastName":"Jadhav","suffix":""},{"id":566397134,"identity":"5b2a3935-a111-4392-8996-e80cb8875383","order_by":2,"name":"Pratik More","email":"","orcid":"","institution":"Krishna Vishal Vidyapeeth (KVV) Deemed to be University","correspondingAuthor":false,"prefix":"","firstName":"Pratik","middleName":"","lastName":"More","suffix":""},{"id":566397135,"identity":"96a3b1e0-7705-43b1-87ff-68a48edaeca9","order_by":3,"name":"Deepyanti Dubey","email":"","orcid":"","institution":"Dr. D.Y.Patil Dental college and Hospital Dr. D.Y.Patil Vidyapeeth","correspondingAuthor":false,"prefix":"","firstName":"Deepyanti","middleName":"","lastName":"Dubey","suffix":""},{"id":566397136,"identity":"4bcdedf5-e21d-4fb4-a1e9-ad9d8677b193","order_by":4,"name":"Asmita Sonawane","email":"","orcid":"","institution":"Yogita Dental College and Hospital","correspondingAuthor":false,"prefix":"","firstName":"Asmita","middleName":"","lastName":"Sonawane","suffix":""},{"id":566397137,"identity":"3de70f50-4b52-47a1-9819-edd76c32302c","order_by":5,"name":"Shirin Kshirsagar","email":"","orcid":"","institution":"Yogita Dental College and Hospital","correspondingAuthor":false,"prefix":"","firstName":"Shirin","middleName":"","lastName":"Kshirsagar","suffix":""}],"badges":[],"createdAt":"2025-11-21 07:08:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8170577/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8170577/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":99315356,"identity":"917375d1-07a4-442b-9aae-9a980f827293","added_by":"auto","created_at":"2025-12-31 16:26:52","extension":"jpeg","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":19316,"visible":true,"origin":"","legend":"","description":"","filename":"Fig1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/5136007559632b2b580763c4.jpeg"},{"id":99316423,"identity":"d0df5077-a1ac-40ee-8361-00789932e154","added_by":"auto","created_at":"2025-12-31 16:28:27","extension":"jpeg","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":16586,"visible":true,"origin":"","legend":"","description":"","filename":"Fig2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/981bac74739173c0b074b6b4.jpeg"},{"id":99144767,"identity":"f7896482-a4cc-4566-a3f6-b5046ac06228","added_by":"auto","created_at":"2025-12-29 08:49:57","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":150381,"visible":true,"origin":"","legend":"","description":"","filename":"TitlePageFinal.docx","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/2bc22ca26c3fa5ac48bbe86d.docx"},{"id":99316465,"identity":"3cc5549a-076e-40d5-8ace-0ae34cf7a535","added_by":"auto","created_at":"2025-12-31 16:28:29","extension":"jpeg","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":31259,"visible":true,"origin":"","legend":"","description":"","filename":"Fig3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/dcecd85088a16dea76e84817.jpeg"},{"id":99317228,"identity":"a94fe1d6-8bd9-4594-bc45-6e81442fe09e","added_by":"auto","created_at":"2025-12-31 16:29:48","extension":"jpeg","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":23071,"visible":true,"origin":"","legend":"","description":"","filename":"Fig4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/3326d5e48c7f03191b216415.jpeg"},{"id":99315475,"identity":"c7a7ab46-fbb9-4def-aef0-273de6538ab6","added_by":"auto","created_at":"2025-12-31 16:26:57","extension":"docx","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":13179,"visible":true,"origin":"","legend":"","description":"","filename":"Table1.docx","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/77784f5034beeca7351391ba.docx"},{"id":99144780,"identity":"20e85636-0990-4cb1-915f-294b37a32da0","added_by":"auto","created_at":"2025-12-29 08:49:58","extension":"jpg","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":36672,"visible":true,"origin":"","legend":"","description":"","filename":"Fig5Graph1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/0c0a7805bd734156e6ea9a34.jpg"},{"id":99316635,"identity":"38ba6dc1-22cc-49be-97f6-586c5ac57ea9","added_by":"auto","created_at":"2025-12-31 16:28:45","extension":"docx","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":13788,"visible":true,"origin":"","legend":"","description":"","filename":"Table2.docx","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/8b43d6532763fd8562726a05.docx"},{"id":99315881,"identity":"4f846192-234b-4868-bcef-9c5a72c6b78a","added_by":"auto","created_at":"2025-12-31 16:27:26","extension":"json","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":8037,"visible":true,"origin":"","legend":"","description":"","filename":"af5f5649e6a74641bb7e7c225cbdfd9a.json","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/a59327ffa440e72785bf92c4.json"},{"id":99144793,"identity":"68630daa-2dd8-4e24-a59a-48bc6c6ceea1","added_by":"auto","created_at":"2025-12-29 08:49:58","extension":"xml","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":104680,"visible":true,"origin":"","legend":"","description":"","filename":"af5f5649e6a74641bb7e7c225cbdfd9a1enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/c21fe5d4b094808b92d371f0.xml"},{"id":99315121,"identity":"f9d1c69f-c10c-45dd-9c7e-ec1ba1c42da5","added_by":"auto","created_at":"2025-12-31 16:26:24","extension":"jpeg","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":19316,"visible":true,"origin":"","legend":"","description":"","filename":"Fig1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/2bc9f139809123363c2235f7.jpeg"},{"id":99144788,"identity":"ddecab5b-9518-47c3-aaeb-a4febf3055a2","added_by":"auto","created_at":"2025-12-29 08:49:58","extension":"jpeg","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":16586,"visible":true,"origin":"","legend":"","description":"","filename":"Fig2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/8c514b8d9bce92c1c4409177.jpeg"},{"id":99315236,"identity":"9766cf14-4c9d-455f-8a6b-5bc376bce716","added_by":"auto","created_at":"2025-12-31 16:26:40","extension":"jpeg","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":31259,"visible":true,"origin":"","legend":"","description":"","filename":"Fig3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/59fad9ee0b49d34d187cc909.jpeg"},{"id":99317251,"identity":"13c0687f-536e-45be-b988-08786b2dd642","added_by":"auto","created_at":"2025-12-31 16:29:49","extension":"jpeg","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":23071,"visible":true,"origin":"","legend":"","description":"","filename":"Fig4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/67bdee5818d8af9c893a2854.jpeg"},{"id":99144791,"identity":"21dd53fa-cea9-4e81-8e99-f5e4618d1187","added_by":"auto","created_at":"2025-12-29 08:49:58","extension":"jpg","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":36672,"visible":true,"origin":"","legend":"","description":"","filename":"Fig5Graph1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/accf5b4174d8a36fb35486fa.jpg"},{"id":99315052,"identity":"7360ecba-4a78-494b-9dac-b95435fbf4a3","added_by":"auto","created_at":"2025-12-31 16:26:14","extension":"jpeg","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":19316,"visible":true,"origin":"","legend":"","description":"","filename":"Fig1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/0110250bf9d876a0feadb211.jpeg"},{"id":99144784,"identity":"899b4581-2c0c-4afa-93f3-c1d81b26ab0c","added_by":"auto","created_at":"2025-12-29 08:49:58","extension":"jpeg","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":16586,"visible":true,"origin":"","legend":"","description":"","filename":"Fig2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/b669b30247360dc2a5d99614.jpeg"},{"id":99317284,"identity":"b223a397-0059-4d4e-ab98-e0f2a5d908af","added_by":"auto","created_at":"2025-12-31 16:29:54","extension":"jpeg","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":25836,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/31bfcf7fec808523ef738fcd.jpeg"},{"id":99315852,"identity":"ca062dbe-0277-4706-846f-df65eb5e9cef","added_by":"auto","created_at":"2025-12-31 16:27:24","extension":"jpeg","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":23071,"visible":true,"origin":"","legend":"","description":"","filename":"Fig4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/ee1ab5bae67ac4e81dc1bc71.jpeg"},{"id":99144792,"identity":"1b19bdaa-2a26-437c-bbed-0a8254e479a0","added_by":"auto","created_at":"2025-12-29 08:49:58","extension":"jpeg","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":36672,"visible":true,"origin":"","legend":"","description":"","filename":"Fig5Graph1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/2be4aa5f593b1d1f8796684b.jpeg"},{"id":99144786,"identity":"4de0c446-1aca-4560-8f34-752789c39804","added_by":"auto","created_at":"2025-12-29 08:49:58","extension":"png","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":9068,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig1.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/85c739dfee4d7c1f7f982cb1.png"},{"id":99316846,"identity":"3336465b-2728-413c-ba3b-61a8408267db","added_by":"auto","created_at":"2025-12-31 16:29:20","extension":"png","order_by":21,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":14332,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig2.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/351bcd609b137046c5f9f57b.png"},{"id":99315149,"identity":"2b8e59e7-d0c4-4e77-8c21-8d16fbc1b71f","added_by":"auto","created_at":"2025-12-31 16:26:29","extension":"png","order_by":22,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":69692,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig3.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/2750f1fb074354c6e8167c37.png"},{"id":99144789,"identity":"57f97df3-929d-4c94-8f9f-b9b0073e8308","added_by":"auto","created_at":"2025-12-29 08:49:58","extension":"png","order_by":23,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":39339,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig4.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/885da8d917013abdbe23c541.png"},{"id":99315099,"identity":"dccaa222-a8f7-49fb-9e30-0ebaa7919f9f","added_by":"auto","created_at":"2025-12-31 16:26:19","extension":"png","order_by":24,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":28341,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig5Graph1.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/d9399a950029fda868fd0b4d.png"},{"id":99315817,"identity":"d332d48b-ad68-4464-b6b6-6273e5472f2e","added_by":"auto","created_at":"2025-12-31 16:27:23","extension":"png","order_by":25,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":9068,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig1.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/658c441452e10dc2afaccafa.png"},{"id":99144790,"identity":"f0a2dc7e-5c70-4c53-8b74-a2f74adb222b","added_by":"auto","created_at":"2025-12-29 08:49:58","extension":"png","order_by":26,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":14332,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig2.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/e281b7249e714151e9db5992.png"},{"id":99144800,"identity":"88417f81-b2f8-463e-87b5-8f577b382700","added_by":"auto","created_at":"2025-12-29 08:49:59","extension":"png","order_by":27,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":38900,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/a65af24ca8d293ca74893d15.png"},{"id":99144802,"identity":"2f27c649-e41a-4e63-b8e8-bd0e484175b3","added_by":"auto","created_at":"2025-12-29 08:49:59","extension":"png","order_by":28,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":39339,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/eeec5210ef43bcea5a1685fd.png"},{"id":99144794,"identity":"338a4844-0ad3-4322-ab24-ca3f26af6c57","added_by":"auto","created_at":"2025-12-29 08:49:58","extension":"png","order_by":29,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":28341,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/fd55fc0f6024d32d1df91538.png"},{"id":99144787,"identity":"50509f5d-93f8-48c8-a6ac-97a497c8986b","added_by":"auto","created_at":"2025-12-29 08:49:58","extension":"xml","order_by":30,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":101114,"visible":true,"origin":"","legend":"","description":"","filename":"af5f5649e6a74641bb7e7c225cbdfd9a1structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/b4085c10f39f12533ef1ee22.xml"},{"id":99144798,"identity":"8988c86c-addc-4059-8500-99f09804b10c","added_by":"auto","created_at":"2025-12-29 08:49:59","extension":"html","order_by":31,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":114157,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/8fffd4dcfbdc56a89fd1f8ce.html"},{"id":99316438,"identity":"3ad17fb1-dade-41ae-8c39-8db7c6cb8ca6","added_by":"auto","created_at":"2025-12-31 16:28:28","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":26786,"visible":true,"origin":"","legend":"\u003cp\u003eSingle Fiber Reinforced Post (Selfpost, Medicept UK Ltd.)\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/5328ee0fce66fb1a17cc23a1.png"},{"id":99315956,"identity":"8f1ea72f-0d8b-44aa-af2d-4ff18a725c14","added_by":"auto","created_at":"2025-12-31 16:27:30","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":53840,"visible":true,"origin":"","legend":"\u003cp\u003ePlacement of Single Fiber Post in prepared post space\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/68215838c772464c24ecb655.png"},{"id":99315257,"identity":"e2436521-4176-4a6d-9f29-9ed76fc4039c","added_by":"auto","created_at":"2025-12-31 16:26:42","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":25795,"visible":true,"origin":"","legend":"\u003cp\u003eMultiple Dentapreg Pin Posts (Dentapreg; ADM, Brno, Czech Republic)\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/22d0ee77effa09746b35eb8c.png"},{"id":99315227,"identity":"41004cf1-b285-4823-b8f0-86c486ec4e18","added_by":"auto","created_at":"2025-12-31 16:26:39","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":66553,"visible":true,"origin":"","legend":"\u003cp\u003ePlacement of Multiple Dentapreg Pin Posts in prepared post space\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/b92e7df95ec56ca08c2337d7.png"},{"id":99315559,"identity":"3ac0dc38-ec94-4324-bef7-09f6148ba30a","added_by":"auto","created_at":"2025-12-31 16:27:05","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":157691,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of Fracture load (N) between four groups.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/bcaddc31f01e7d6c40baeb86.png"},{"id":99323593,"identity":"b4d44fd4-3bf2-4734-8c42-10c5d95c4aa9","added_by":"auto","created_at":"2025-12-31 16:45:39","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1091478,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8170577/v1/5f4d0d3c-196f-4ce2-821f-042a73252cc5.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eEffect of MMP inhibitor pre-treatment on the fracture resistance of single versus multiple pin post endodontic restorations: an in vitro study\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eWhen significant coronal tooth structure is lost, an endodontic post is often used to restore the tooth, onto which a full crown is cemented [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. An optimal endodontic post must exhibit precise adaptation, compatibility with biological tissues, and strong resistance to tensile and fatigue stresses to efficiently disperse chewing forces. While an endodontic post helps support coronal restoration, it may also increase the likelihood of root fracture [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. According to vartak et al. [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], approximately 20% of root canal-treated teeth restored with radicular posts may develop vertical root fractures. Therefore, careful selection of post endodontic and precise clinical techniques is crucial for the success of post endodontic restorations.\u003c/p\u003e \u003cp\u003eClinical studies have shown that fiber-reinforced composite (FRC) posts have a success rate of 95% to 99% in restorative dental procedures [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. These posts are favored for their appealing appearance, resemblance to natural dentin, and superior mechanical performance [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Nevertheless, prefabricated FRC posts may not match the shape of the root canal, requiring additional shaping that can compromise fracture resistance. In large or irregular canals, excessive cement is needed, which may weaken the bond due to the lower mechanical strength and polymerization shrinkage (1.2\u0026ndash;6%) of the composite resin cement, increasing failure risk [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDentapreg\u0026reg; (\u003cem\u003eDentapreg; ADM, Brno, Czech Republic\u003c/em\u003e) offers a novel, minimally invasive fiber pin post system intended for the restoration of endodontically treated teeth. Each pin is 20 mm long and has a diameter of 0.45 mm, allowing flexibility and adaptation within the root canal. Made from unidirectional S2-glass fibers, ultrathin yet firm pins are procured and flexible, allowing them to conform to the root\u0026rsquo;s curvature without additional instrumentation. This flexibility maintains the tooth\u0026rsquo;s natural biomechanics, reducing the risk of root fractures [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOver time, endogenous matrix metalloproteinases (MMPs) contribute to the enzymatic breakdown of the collagen within the hybrid layer, compromising the strength and durability of the adhesive dentin bond. The application of MMP inhibitors has been shown to effectively preserve this interface, resulting in improved adhesion and increased resistance to fracture [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eChlorhexidine, a widely used bisbiguanide, is recognized not only for its potent antimicrobial properties but also for its role as an effective inhibitor of matrix metalloproteinases (MMPs) [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Matrix metalloproteinases (MMPs) are naturally occurring enzymes that significantly contribute to the breakdown of the collagen matrix within dentin, particularly in the hybrid layer created between dentin and adhesive resin. The deterioration of the hybrid layer is a key contributor to the gradual decline in bond strength, which can ultimately result in the failure of dental restorations [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eLimited data exist regarding the effectiveness of the Dentapreg multiple pin post system in reinforcing root canal-treated teeth, particularly when combined with MMP inhibitors. The current study was designed to assess the effect of MMP inhibitor pretreatment on the fracture resistance of root canal-treated teeth restored with either single or multiple pin posts. The null hypothesis proposed that MMP inhibitor application would not significantly influence fracture resistance across the tested systems.\u003c/p\u003e"},{"header":"2. Material and methods","content":"\u003cp\u003e\u003cstrong\u003e2.1 \u0026nbsp;Ethics approval statement:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthical approval\u0026nbsp;was obtained from the institute with reference number YDCH/Ethic/A2/2023-2024, and the study was\u0026nbsp;performed\u0026nbsp;accordingly.\u0026nbsp;All procedures were performed in accordance with the ethical standards of the institutional ethics committee and the Declaration of Helsinki.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2 Selection of teeth:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study involved forty extracted maxillary premolars with a single root and fully formed apices obtained for periodontal or orthodontic indications.Written informed consent was obtained from all participants for tooth extraction and for the use of their extracted teeth for research purposes .Teeth exhibiting caries, fractures, prior root canal treatment, or anatomical anomalies were excluded. All the samples were ultrasonically cleaned to eliminate any remaining soft tissue and then immersed in normal saline at room temperature (24\u0026ndash;28\u0026deg;C) to maintain hydration throughout the study period.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3 Sample preparation:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe samples were sectioned just below the CEJ via a diamond disc (Mani, Tochigi, Japan)\u0026nbsp;under water cooling and standardized to 12 \u0026plusmn; 1 mm. The pulp tissue was removed, and the working length was set to 1 mm short of the apex via a size 10 K file (Mani, Tochigi, Japan). Canals were shaped with the ProTaper rotary system (Dentsply Maillefer, Ballaigues, Switzerland)\u0026nbsp;up to size F3 via the crown-down technique. Irrigation after each file was performed with 2 ml of 5.25% NaOCl (Prime Private Limited, Maharashtra, India) and saline (Vishal Private Limited, India) via a 30-gauge side vented needle. The final irrigation method included NaOCl, 17% EDTA (Prime Private Limited, Maharastra, India), and saline. After drying with paper points, canals were obtained via F3 gutta percha (Dentsply Maillefer, Ballaigues, Switzerland) with AH Plus sealer (Dentsply Maillefer, Ballaigues, Switzerland). Coronal sealing was performed with Cavit G (3 M ESPE), and the samples were incubated at 37\u0026deg;C in 100% humidity for 24 hours to ensure complete setting.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;2.4 Post space preparation:\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePeeso reamers\u0026nbsp;(Mani, Tochigi, Japan)\u0026nbsp;up to size 2 were used to prepare post spaces to a depth of 7 mm, ensuring that 5 mm of gutta-percha remained intact in the apical portion. Following saline irrigation and drying with sterile paper points, the samples were randomly allocated into four experimental groups (n = 10).\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eGroup 1:\u0026nbsp;Single-fiber post without dentin pretreatment\u003c/li\u003e\n \u003cli\u003eGroup 2: Single-fiber post with dentin pretreated with an MMP inhibitor\u003c/li\u003e\n \u003cli\u003eGroup 3: Multiple dentin pins without dentin pretreatment\u003c/li\u003e\n \u003cli\u003eGroup 4: Multiple dentin pins with dentin pretreated with an MMP inhibitor\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eGroups 1 and 3 were restored via single-fiber reinforced posts (Selfpost, Medicept UK Ltd.) (Figure 1) without surface pretreatment, and 37% phosphoric acid (3 M ESPE) was applied to the post spaces for 15 s, followed by thorough rinsing and drying. Scotchbond Universal Adhesive (3MESPE, Seefeld, Germany) was applied, and the samples were air dried and light cured. Dual-cure resin cement (RelyX Ultimate, 3 M ESPE) was introduced into the canals, and the posts were positioned with finger pressure (Figure 2). Excess cement was removed, followed by 5 minutes of self-curing and 30 seconds of light curing. Posts were trimmed to 6 mm above the root, and core build-up was completed via Filtek Z350 composite resin (3 M ESPE, St. Paul, MN, USA), which was standardized to 6 mm using a Vernier caliper (Altraco Inc., Sausalito, California, USA).\u003c/p\u003e\n\u003cp\u003eGroups 2 and 4, restored with multiple pin posts\u0026nbsp;(\u003cem\u003eDentapreg\u003c/em\u003e; \u003cem\u003eADM\u003c/em\u003e, \u003cem\u003eBrno\u003c/em\u003e, \u003cem\u003eCzech Republic\u003c/em\u003e)\u0026nbsp;(Figure 3),\u0026nbsp;underwent the same etching procedure as the other groups did. A 2% chlorhexidine solution (\u003cem\u003eGlobus Medisys\u003c/em\u003e\u003cem\u003e,\u0026nbsp;\u003c/em\u003eVadodara, Gujarat,\u003cem\u003e\u0026nbsp;\u003cem\u003eIndia\u003c/em\u003e)\u003c/em\u003e was dispensed into a dappen dish, and the canal walls were coated with a saturated microbrush or paper point with gentle scrubbing motion for 60 seconds, rewetting the applicator as needed to maintain contact; excess solution was then removed by blotting with dry paper points until only a sheen of moisture remained, without rinsing. Scotchbond Universal adhesive was applied, and the samples were air-dried and light-cured. Dual-cure resin cement was placed in the canal, and multiple pin posts were inserted according to the manufacturer\u0026rsquo;s guidelines (Figure 4). Following 20 seconds of light curing, the posts were trimmed to a size of 6 mm coronally, and core build-up was completed as described previously.\u003c/p\u003e\n\u003cp\u003eAll the samples were mounted in self-curing acrylic resin (DPI, Jabalpur, India) blocks within 2 cm diameter plastic rings, with the resin positioned 1 mm apical to the buccal cementoenamel junction (CEJ).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.5 Fracture Resistance Test:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFracture resistance was evaluated with the help of a universal testing machine (ACME Engineers, India), which applied a compressive load with a 5 mm round-tip probe at a 45\u0026deg; angle to the tooth\u0026rsquo;s long axis at a crosshead speed of 1 mm/min. The fracture force was measured in newtons (N).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.6 Statistical analysis:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFracture load values (in N) were recorded in Microsoft Excel 2010 and reported as the mean \u0026plusmn; standard deviation for each group. One-way ANOVA followed by Tukey\u0026rsquo;s post hoc test was used for statistical analysis (P \u0026lt; 0.05), and data visualization was performed via bar charts (Figure 5). SPSS version 19 was used for all analyses.\u003c/p\u003e"},{"header":"3. Results","content":"\u003cp\u003eThe results showed that Group 1 (single-fiber post without dentin pretreatment) had the lowest mean fracture resistance among all the groups. Group 4 (multiple Dentapreg pins with MMP inhibitor pretreatment) demonstrated the highest fracture resistance, followed by Group 3 (multiple Dentapreg pins without pretreatment) and Group 2 (single fiber post-MMP inhibitor pretreatment) (Table 1, Figure 5). Tukey\u0026rsquo;s post hoc test indicated significant differences across all groups (P \u0026lt; 0.001), except between Groups 2 and 3, for which there was no statistically significant difference. (Table 2)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 1: Descriptive statistics for the fracture load (N) among the four groups\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"652\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroups\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMinimum\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMaximum\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eStd. Deviation\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 1 :\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e239.16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e373.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e276.1860\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e47.06171\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 2 :\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e290.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e474.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e399.6340\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e57.15834\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 3 :\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e295.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e540.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e433.5260\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e72.70173\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 4 :\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e446.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e673.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e575.3070\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e67.70996\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eTable 2 : Pairwise comparison of the fracture load (N) among the four groups according to Tukey\u0026rsquo;s post hoc test\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"661\" class=\"fr-table-selection-hover\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\" valign=\"top\" style=\"width: 661px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDependent Variable:\u0026nbsp;\u003c/strong\u003eFracture load (N)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;Tukey HSD\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e(I) Groups\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e(J) Groups\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eMean Difference\u003c/p\u003e\n \u003cp\u003e(I-J)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eStd.\u003c/p\u003e\n \u003cp\u003eError\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003eSig.\u003c/p\u003e\n \u003cp\u003ep value\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 198px;\"\u003e\n \u003cp\u003e95% Confidence Interval\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003eLower Bound\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eUpper Bound\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eGroup 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-123.44800\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e27.70565\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-198.0656\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-48.8304\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eGroup 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-157.34000\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e27.70565\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-231.9576\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-82.7224\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 1\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eGroup 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-299.12100\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e27.70565\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-373.7386\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-224.5034\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eGroup 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-33.89200\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e27.70565\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-108.5096\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e40.7256\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eGroup 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-175.67300\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e27.70565\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-250.2906\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-101.0554\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 3\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eGroup 4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-141.78100\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003e27.70565\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 76px;\"\u003e\n \u003cp\u003e\u0026lt;0.001*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e-216.3986\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e-67.1634\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\" valign=\"top\" style=\"width: 661px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e*. The mean difference is significant at the 0.05 level.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"4. Discussion","content":" \u003cp\u003ePosts should effectively transmit and distribute stress to minimize the risk of root fractures. This study assessed and compared the fracture resistance of endodontically treated teeth reinforced with either a single-fiber post or multiple pin posts, with and without pretreatment with an MMP inhibitor.\u003c/p\u003e \u003cp\u003eSingle rooted maxillary premolars were chosen for this study because their anatomical structure, including narrow roots and reduced dentin thickness, makes them particularly vulnerable to vertical root fractures. This susceptibility becomes more pronounced after endodontic treatment because of the loss of tooth structure and altered stress distribution under occlusal loading. Therefore, they serve as an ideal model for evaluating the fracture resistance of various post endodontic restorative techniques [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe results revealed a marked improvement in fracture resistance in teeth restored with multiple pin posts combined with MMP inhibitor pretreatment compared with those restored with a single fiber post without any pretreatment. This may be attributed to the greater modulus of elasticity provided by multiple pins with smaller cross-sectional areas but similar lengths to single posts [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Additionally, multiple pin posts likely offer improved adaptation, forming a more unified structure with dentin and cement [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Luting cement also contributes to the overall flexibility and stress distribution of the post system.\u003c/p\u003e \u003cp\u003eResin cement has a modulus of elasticity similar to that of dentin, and its bonding to intraradicular dentin helps form an internal reinforcing layer, thereby enhancing the overall structural integrity [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Multiple pin posts provide a larger surface area than a single post does, reducing the stress concentration at the cement\u0026ndash;dentin interface. This broader distribution helps limit crack initiation by dispersing tensile forces over a wider area [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The multipost approach not only improves adaptation but also may reduce the risk of post dislodgment and increase resistance to long-term cyclic loading [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Thus, using multiple posts or customizing a single post to match the root canal anatomy may contribute to improved clinical outcomes.\u003c/p\u003e \u003cp\u003eMaceri et al. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] demonstrated that using multiple post restoration methods can significantly reduce stress concentrations, with a 27% decrease in von Mises stress under intrusive loads and a 20% reduction under oblique loads. Additionally, Rankine stress analysis revealed lower tensile stress in both the apical and cervical regions, indicating a decreased risk of root fracture. These results are consistent with those reported by Q. Li et al.[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], Frater et al.[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], Brackett et al.[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], Zheng et al.[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], and Moogi et al.[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], who reported that multiple pin post systems provide superior fracture resistance compared with single post restorations.\u003c/p\u003e \u003cp\u003eIn this study, Dentapreg multiple-fiber pin posts were utilized for the restoration of endodontically treated teeth. These posts contribute to reinforcing the remaining tooth structure by establishing a monoblock system, wherein the post, cement, and dentin act as a unified structure. Dentapreg posts are composed of unidirectional S-type glass fiber materials initially designed for the high strength and durability demands of aerospace applications, such as space shuttles. Each pin has a diameter of approximately 0.45 mm and is light-cured, providing a combination of firmness and flexibility. Their slim and adaptable design allows them to follow the natural curvature of the root canal, thus eliminating the necessity for additional canal enlargement or instrumentation [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThese fiber pin posts offer enhanced retention through two primary mechanisms. First, micromechanical retention is achieved by increasing the number of posts within the canal, which contributes to better stress distribution and improved mechanical interlocking. Additionally, micromechanical retention is achieved through the adhesion of bonding agents to the root dentin, promoting better integration of the post system with the canal walls [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe samples were tested under an oblique load applied at a 45-degree angle to the tooth\u0026rsquo;s long axis\u0026mdash;an approach recognized by Wandscher et al.[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] as one of the most challenging scenarios for assessing fracture resistance in endodontically treated teeth. This loading direction generates significant stress on the cervical region of teeth lacking a ferrule and imposes considerable shear forces at the interfaces between the post, luting agent, and radicular dentin. This setup simulates a worst-case occlusal loading condition, providing a stringent test of the durability and integrity of the restoration and remaining tooth structure [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEstablishing a strong and stable bond between the adhesive and dentin is essential for ensuring the long-term success of tooth-colored restorations. In both the etch-and-rinse and self-etch systems, the acid etching step either demineralizes or modifies the mineral content of dentin, depending on the adhesive approach used. This exposes the collagen matrix, which is then infiltrated by adhesive monomers to form the hybrid layer [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Over time, the integrity of this adhesive‒dentin interface tends to deteriorate, primarily owing to the breakdown of the hybrid layer. This degradation is often linked to hydrolysis of the collagen network and breakdown of the hydrophilic resin components within the adhesive [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Matrix metalloproteinases (MMPs), which are naturally present in dentin, become activated under acidic conditions, such as during etching, and contribute significantly to the degradation of the exposed collagen, thereby compromising the bond strength at the interface [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTo reduce collagen breakdown and increase the longevity of the adhesive\u0026ndash;dentin bond, various improvements to traditional bonding protocols have been suggested. These include applying an extra hydrophobic resin layer, using multiple adhesive layers, improving solvent evaporation, prolonging the curing time, incorporating MMP inhibitors, and using an electric current to support monomer penetration [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. These techniques have shown promising results in maintaining the hybrid layer, reinforcing the adhesive interface, and increasing the bond strength.\u003c/p\u003e \u003cp\u003eThe application of matrix metalloproteinase (MMP) inhibitors to dentin either after acid etching or as part of adhesive formulations has been shown to increase the durability of the adhesive interface, thereby improving the long-term performance of tooth-colored aesthetic restorations [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Among the various MMP inhibitors, chlorhexidine is widely recognized as the most effective. It is a cationic bisbiguanide compound known for its strong antibacterial properties and is frequently used as a root canal irrigant and in mouthwashes because of its sustained activity. Chlorhexidine inhibits MMPs through mechanisms such as chelation of metal ions or disruption of protein structure, thereby helping to maintain the hybrid layer and reduce enzymatic degradation [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCarrilho et al. [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] demonstrated the positive role of chlorhexidine in maintaining dentin bond strength by functioning as an MMP inhibitor, particularly when applied before adhesive bonding without rinsing. In this method, chlorhexidine interacts directly with the exposed collagen fibrils and becomes encapsulated by the adhesive resin, helping to protect the fibrils from degradation. Favetti et al. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] reported a notably reduced failure rate within the hybrid layer, especially in its deeper sections, six months after treatment with chlorhexidine. These findings suggest that the increased bond strength in this group was linked to the preservation of the collagen matrix in the hybrid layer\u0026mdash;most critically, in the deeper areas, where collagen is more vulnerable to enzymatic breakdown. Furthermore, Ricci et al. [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] reported from in vivo studies that chlorhexidine application did not compromise the immediate bond strength and may be effective in preventing early bond deterioration.\u003c/p\u003e \u003cp\u003eDifferent concentrations of chlorhexidine (CHX) have been investigated to determine the most effective protocol for enhancing its performance. Among these methods, a 2% CHX solution applied for 60 s before primer application in adhesive systems has become the most commonly accepted method to inhibit MMP activity and help maintain bond strength over time [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. On the basis of this widely endorsed protocol, the present study employed 2% CHX for 60 s prior to bonding.\u003c/p\u003e \u003cp\u003eWhen applied before bonding and without rinsing, MMP inhibitors such as chlorhexidine (CHX) penetrate exposed collagen fibrils and become encapsulated by adhesive resins. This not only helps inhibit collagen degradation but also offers antimicrobial action and allows the rehydration of dried mineralized dentin [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAs CHX does not negatively affect the immediate bond strength, its clinical use is recommended to increase the durability of the resin\u0026ndash;dentin bond, [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] thereby contributing to improved fracture resistance.\u003c/p\u003e \u003cp\u003eThe findings of this study may have limited clinical applicability, as fracture resistance was evaluated via a single-point load. Additional in vitro and in vivo studies are needed to confirm these results and support their relevance to long-term clinical performance.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eWithin the limitations of this study, Dentapreg multiple-fiber pin posts demonstrated significantly greater fracture resistance than single glass-fiber-reinforced posts did. Moreover, pretreatment with 2% chlorhexidine, an MMP inhibitor, significantly improved fracture resistance, regardless of the type of drug used.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eMMP \u0026ndash; Matrix Metalloprotein\u003c/p\u003e\n\u003cp\u003eCHX- Chlorhexidine\u003c/p\u003e\n\u003cp\u003eSD- Standard Deviation\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot Applicable\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\u003eAvailability of data and materials:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used during the current study are available from the corresponding author on reasonable request.\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\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no financial relationships relevant to this article to disclose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors' contributions\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eConceptualization, Data curation, Formal analysis, funding acquisition: Dhok VD; Investigation, Methodology, Project administration: Dubey D, Resource, Software: Jadhav SR. Supervision, Validation, Visualization: More PP, Sonawane AA. Writing - original draft: Dhok VD,Kshirsagar S; Writing - review \u0026amp; editing: All authors. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot Applicable\u003c/p\u003e\n\u003ch4\u003e\u003cstrong\u003eDeclaration of generative AI use:\u003c/strong\u003e\u003c/h4\u003e\n\u003cp\u003eDuring the preparation of this work, the author(s) used ChatGPT (OpenAI, GPT-5.1) for language refinement and editing. After using this tool, the author(s) reviewed and edited the content as needed and take full responsibility for the published article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eQing H, Zhu Z, Chao Y, Zhang W. In vitro evaluation of the fracture resistance of anterior endodontically treated teeth restored with glass fiber and zircon posts. J Prosthet Dent. 2007;97(2):93\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHaralur SB, Al Ahmari MA, Alqarni SA, Althobati MK. The Effect of Intraradicular Multiple Fiber and Cast Posts on the Fracture Resistance of Endodontically Treated Teeth with Wide Root Canals. Biomed Res Int. 2018; 2018:1671498.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVartak MA, Hegde VR, Hegde SR, Fanibunda U. Fracture resistance and failure modes of endodontically treated permanent teeth restored with Ribbond posts vs other post systems: a systematic review and meta-analysis of in vitro studies. Restor Dent Endod. 2025;50(1):e5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMakade CS, Meshram GK, Warhadpande M, Patil PG. A comparative evaluation of fracture resistance of endodontically treated teeth restored with different post core systems - an in vitro study. J Adv Prosthodont. 2011;3(2):90\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRezaei Dastjerdi M, Amirian Chaijan K, Tavanafar S. Fracture resistance of upper central incisors restored with different posts and cores. Restor Dent Endod. 2015;40(3):229\u0026ndash;35.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDhok VD, Khanvilkar U, Moogi PP, Bandekar SD, Kshirsagar S, Jadhav SR. A comparative evaluation of the effect of matrix metalloproteinase inhibitor on the fracture resistance of endodontically treated teeth restored with Everstick-reinforced composite resin: An in vitro study. J Conserv Dent Endod. 2024;27:1104\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePrashant PM, Sonawane AA, Siddhesh DB, Shirin PK, Kalyani IA, Tryambake R, Pavan. Comparative evaluation of push-out bond strength of single and multiple fiber-reinforced posts cemented with dual-cure resin cement using different adhesive strategies: An in vitro study. Endodontology 35(1): p 18\u0026ndash;23, Jan\u0026ndash;Mar. 2023.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMartina LP, Ebenezar AVR, Ghani MF, Narayanan A, Sundaram M. Mohan, Ajit George. An in vitro comparative antibacterial study of different concentrations of green tea extracts and 2% chlorhexidine on \u003cem\u003eEnterococcus faecalis\u003c/em\u003e. Saudi Endodontic J 3(3): p 120\u0026ndash;4, Sep\u0026ndash;Dec 2013.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTandelilin RTC, Saini R. Dynamics of Matrix Metalloproteinases in the Oral Environment. Int J Exp Dent Sci. 2015;4(1):53\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZarow M, Vadini M, Chojnacka-Brozek A, Szczeklik K, Milewski G, Biferi V, D'Arcangelo C, De Angelis F. Effect of Fiber Posts on Stress Distribution of Endodontically Treated Upper Premolars: Finite Element Analysis. Nanomaterials (Basel). 2020;10(9):1708.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDentapreg\u0026reg; PINPost cured elastic \u0026amp; flexible pins. UK Dentistry Ltd. Available at: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://ukdentistry.co.uk/Dentapreg-PINPost-cured-elastic-flexible-pins\u003c/span\u003e\u003cspan address=\"https://ukdentistry.co.uk/Dentapreg-PINPost-cured-elastic-flexible-pins\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (accessed 16 August 2025).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlwan NJ, Al-Askary RA. Analysis of fiber post\u0026ndash;resin cement interfacial adaptation at different post regions using field emission scanning electron microscopy. Saudi Endodontic J 14(3): p 368\u0026ndash;78, Sep\u0026ndash;Dec 2024.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFavetti M, Schroeder T, Montagner AF, Correa MB, Pereira-Cenci T, Cenci MS. Effectiveness of pretreatment with chlorhexidine in restoration retention: a 36-month follow-up randomized clinical trial. J Dent. 2017;60:44\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ede Moraes IQS, do Nascimento TG, da Silva AT, de Lira LMSS, Parolia A, Porto ICCM. Inhibition of matrix metalloproteinases: a troubleshooting for dentin adhesion. Restor Dent Endod. 2020;45(3):e31.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMaceri F, Martignoni M, Vairo G. Mechanical behavior of endodontic restorations with multiple prefabricated posts: a finite-element approach. J Biomech. 2007;40(11):2386\u0026ndash;98.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Q, Xu B, Wang Y, Cai Y. Efects of auxiliary fber posts on endodontically treated teeth with fared canals. Oper Dent. 2011;36(4):380\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFrater M, Forster A, Jantyik \u0026acute;A, Braunitzer G, Nagy K, Grandini \u0026acute;S. In vitro fracture resistance of premolar teeth restored with fbre-reinforced composite posts using a single or a multipost technique. Australian Endodontic J. 2017;43(1):16\u0026ndash;22.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBrackett WW, Tay FR, Brackett MG, Dib A, Sword RJ, Pashley DH. The effect of chlorhexidine on dentin hybrid layers in vivo. Operative dentistry 200 Mar; 32(2):107\u0026ndash;11.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZheng P, Zaruba M, Attin T, Wiegand A. Effect of different matrix metalloproteinase inhibitors on microtensile bond strength of an etch-and-rinse and a self-etching adhesive to dentin. Oper Dent. 2015;40(1):80\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWandscher VF, Bergoli CD, Limberger IF, Ardenghi TM, Valandro LF. Preliminary results of the survival and fracture load of roots restored with intracanal posts: weakened vs nonweakened roots. Oper Dent. 2014;39:541\u0026ndash;55.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStanislawczuk R, Amaral RC, Zander-Grande C, Gagler D, Reis A, Loguercio AD. Chlorhexidine-containing acid conditioner preserves the longevity of resindentin bonds. Oper Dent. 2009;34(4):481\u0026ndash;90.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePorciani PF, Vano M, Radovic I, Goracci C, Grandini S, Garc\u0026iacute;a-Godoy F, Ferrari M. Fracture resistance of fiber posts: combinations of several small posts vs. standardized single post. Am J Dent. 2008;21(6):373\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBajaj R, Pawah S, Gupta A, Sikri A, Madan P. The Impact of Various Pretreatment Agents on Shear Bond Strength between Self-adhesive Resin Cement and Dentin: An In Vitro Study. 2023; 11 (1):19\u0026ndash;21.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMazzoni A, Tj\u0026auml;derhane L, Checchi V, Di Lenarda R, Salo T, Tay FR, Pashley DH, Breschi L. Role of dentin MMPs in caries progression and bond stability. J Dent Res. 2015;94(2):241\u0026ndash;51.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCarrilho MR, Geraldeli S, Tay F, De Goes MF, Carvalho RM, Tj\u0026auml;derhane L, Reis AF, Hebling J, Mazzoni A, Breschi L, Pashley D. In vivo preservation of the hybrid layer by chlorhexidine. J Dent Res. 2007;86(6):529\u0026ndash;33.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRicci HA, Sanabe ME, de Souza Costa CA, Pashley DH, Hebling J. Chlorhexidine increases the longevity of in vivo resin\u0026ndash;dentin bonds. European Journal of Oral Sciences., Tuncer S, Demirci M, Balci S. Do matrix metalloproteinase inhibitors improve the bond durability of universal dental adhesives? Scanning. 2016;38(6):535\u0026ndash;544.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSoares CJ, Pereira CA, Pereira JC, Santana FR, do Prado CJ. Effect of chlorhexidine application on microtensile bond strength to dentin. Oper Dent. 2008 Mar-Apr;33(2):183\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eInoue S, Carrilho M, Sugiyama T, et al. Inhibition of enzymatic degradation of adhesive-dentin interfaces. J Dent Res. 2009;88(6):537\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTek\u0026ccedil;e N, Tuncer S, Demirci M, Balci S. Do matrix metalloproteinase inhibitors improve the bond durability of universal dental adhesives? Scanning. 2016;38(6):535\u0026ndash;44.\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":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Chlorhexidine digluconate, Dentapreg multiple pin posts, Fiber-reinforced posts, Fracture resistance test, MMP inhibitor","lastPublishedDoi":"10.21203/rs.3.rs-8170577/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8170577/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e Bond degradation by dentin MMPs can reduce the longevity of post endodontic restorations. Chlorhexidine may improve bond stability, but its effect with different post systems is not well established. This study assessed whether MMP inhibitor pretreatment enhances fracture resistance in single and multiple pin post restorations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMaterials and Methods:\u003c/strong\u003e Forty single-rooted maxillary premolars were extracted, and their crowns were sectioned at the cementoenamel junction (CEJ), followed by endodontic treatment. After the post space was prepared via a standardized technique, the samples were distributed into four groups: \u003cstrong\u003eGroup 1\u003c/strong\u003e, single-fiber post with no dentin pretreatment; \u003cstrong\u003eGroup 2\u003c/strong\u003e, single-fiber post with dentin pretreated with a matrix metalloprotein (MMP) inhibitor; \u003cem\u003e2\u003c/em\u003e%, chlorhexidine \u003cem\u003esolution \u003c/em\u003e(\u003cem\u003eGlobus Medisys\u003c/em\u003e,\u003cem\u003e \u003c/em\u003eVadodara, Gujarat, \u003cem\u003eIndia\u003c/em\u003e); \u003cstrong\u003eGroup 3\u003c/strong\u003e, multiple Dentapreg pins (\u003cem\u003eDentapreg\u003c/em\u003e; \u003cem\u003eADM\u003c/em\u003e, \u003cem\u003eBrno\u003c/em\u003e, \u003cem\u003eCzech Republic\u003c/em\u003e) without dentin pretreatment; and \u003cstrong\u003eGroup 4\u003c/strong\u003e, multiple Dentapreg pins with dentin pretreated with a MMP inhibitor. Fracture resistance was assessed after post placement and core build-up via a universal testing machine, in which a 45° compressive load was applied at 1 mm/min until failure. The data were analyzed via one-way ANOVA and Tukey’s post hoc test, with significance set at P \u0026lt; 0.05.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e Group 4 presented the highest mean fracture resistance, followed by Groups 3, 2, and 1, with statistically significant differences (\u003cem\u003eP\u003c/em\u003e\u0026lt; 0.05).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e Within the limits of this study, the evidence indicated that dentapreg pin posts exhibited greater fracture resistance than single-fiber-reinforced posts did. Additionally, the application of 2% chlorhexidine after etching significantly increased the fracture resistance strength.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical significance:\u003c/strong\u003e Understanding how MMP inhibition influences the performance of different post systems can help clinicians make more informed material choices.\u003cbr\u003e\nThis may ultimately support the selection of restoration techniques that offer greater reliability and longevity in endodontically treated teeth.\u003c/p\u003e","manuscriptTitle":"Effect of MMP inhibitor pre-treatment on the fracture resistance of single versus multiple pin post endodontic restorations: an in vitro study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-29 08:49:51","doi":"10.21203/rs.3.rs-8170577/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-01-13T14:57:20+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-07T18:29:24+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-05T11:13:42+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-05T05:31:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"286594270288857122186346425269232414094","date":"2026-01-02T08:01:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"239478974857480390954630065204581798104","date":"2026-01-02T07:45:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"122717246687087476822859792394971956425","date":"2025-12-31T06:10:05+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-28T13:04:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"56206192855787661109376737693372378158","date":"2025-12-27T02:56:57+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"166204431739841281097981717440177340632","date":"2025-12-26T06:09:47+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-26T05:23:25+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-12-04T08:50:05+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-04T08:46:21+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-03T04:50:31+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Oral Health","date":"2025-12-03T04:43:44+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-oral-health","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ohea","sideBox":"Learn more about [BMC Oral Health](http://bmcoralhealth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ohea/default.aspx","title":"BMC Oral Health","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"5f4286fe-0842-41b6-aad1-fc19c2d5e041","owner":[],"postedDate":"December 29th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-12-29T08:49:52+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-29 08:49:51","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8170577","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8170577","identity":"rs-8170577","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}