The assessment of root apical curvature of maxillary lateral incisors phenotypes reveals side and gender difference

The assessment of root apical curvature of maxillary lateral incisors phenotypes reveals side and gender difference | 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 The assessment of root apical curvature of maxillary lateral incisors phenotypes reveals side and gender difference Erika Kuchler, Mario Pereira Couto Neto, Jeferson Luis Oliveira Stroparo, and 9 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5066252/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract BACKGROUND Maxillary lateral incisors root angulation is a common developmental aspect characterized by an alteration in the axial inclination between the crown and root of the incisor, in which a curvature of varied angle of the dental root is observed. This study investigated if root apical curvature of maxillary lateral incisors has gender and side preference as observed in patients with cleft lip and/or palate. METHODS Panoramic radiographs from 230 orthodontic patients were investigated. The method described by Schneider method (1971) was used for the estimation of the degree of root apical curvature of maxillary lateral incisors and to classify the root as straight (5° or less) or curved (higher than 5°). To compare curvature degree among genders, t test was used, and to compare left and right degree differences, a paired t-test was used. Chi-squared test and Odds ratio were used to calculate gender and laterality differences among straight or curved root groups. The established alpha was 5%. RESULTS Ninety-seven were males and 133 were females. A total 198 left maxillary incisors and 201 right maxillary incisors were measured. A statistical difference was observed, in which straight root was more common in the left side (p = 0.028; odds ratio = 1.5, confidence interval 95%: 1.1–2.4). On left incisors, the mean curvature degree was 5.9° (SD = 4.4°) in males, while the mean curvature degree was 7.5° (SD = 5.3°) in females (p = 0.030). Means comparisons between left and right incisor regardless the gender showed a statistical significant difference between sides (p = 0.0001). CONCLUSIONS Our study confirmed the hypotheses that root apical curvature of maxillary lateral incisors has gender and side preference in the general population. dental dilacerations dental anomaly dental development oral cleft Figures Figure 1 Figure 2 BACKGROUND The maxilla in vertebrates is the upper bone of the jaw and is the most important bone of the midface. It has a central location and provides structural support to the viscerocranium and fundamental role in facial architecture and contains the maxillary sinus. It also separates the nasal and oral cavities including superior teeth [ 1 ]. Maxilla is formed by the fusion of the paired medial nasal and maxillary processes, which occurs in the area where the lateral incisor is locate, therefore fails in the fusion process could explain the occurrence of cleft lip with or without cleft palate and developmental dental alteration [ 2 ]. In fact, several studies have been demonstrating that patients with cleft lip with or without cleft palate have a higher risk to present maxillary lateral incisor anomalies such as dental agenesis, microdontia/peg-shaped, supernumerary teeth and tooth impactation in the cleft area and also in the non-cleft area (contralateral side) [ 3 – 6 ]. Numerous studies have also demonstrated that cleft related genes are also associated with isolated dental anomalies, such as non-syndromic tooth agenesis [ 7 ]. Recently we also observed that genes encoding Bone Morphogenetic Protein (BMP), which are well-known involved in cleft lip with or without cleft palate [ 8 ] and tooth agenesis [ 3 , 7 , 9 ], were associated with root curvature of maxillary lateral incisors [ 10 ]. Therefore, it is possible that some trends observed in cleft epidemiological studies could also be observed in dental phenotypes studies. Side preference and gender preference are well-explored in cleft research. The phenotypes involved unilateral cleft lip affects more frequently the left side than the right side [ 11 – 13 ] Gender preference is also observed in cleft studies, cleft palate is more common in females [ 11 , 14 , 15 ], while cleft lip with or without palate are more frequent in males [ 16 , 17 ]. Much evidence has been accumulated over the past century to indicate that oral cleft has a side and gender preference. However, the possibility that the same trend is observed in other anomalies that affect the maxillary lateral incisor area (the area where fusion of the paired medial nasal and maxillary processes occurs) have been poorly explored. Maxillary lateral incisors root angulation is a common developmental condition characterized by an alteration in the axial inclination between the crown and root of the incisor, in which a curvature of varied angle of the dental root is observed [ 18 , 19 ]. Therefore, in the present study, we hypothesized that the root apical curvature of maxillary lateral incisors has gender and side preference as observed in patients with cleft lip and/or palate. METHODS The present cross-sectional study included panoramic radiographs from non-syndromic patients as previously reported [ 10 ]. The study was only conducted after the approval of the study by the Research Ethics Committee from Ribeirão Preto Dental School, University of São Paulo (number: 3.150.551), in accordance with latest version of Declaration of Helsinki guidelines. The dental records of the individuals were only included in the project after all the patients gave their written informed consent to participate in the study. If the individual were under 18 years old, an assent from the patient was also obtained beside an informed consent from their legal guardian. Dental records including anamnesis and orthopantomographs (OPG) from patients undergoing dental treatment in universities and private clinics in Curitiba (Paraná state) and Ribeirão Preto (São Paulo) in Brazil were screened. Only OPG with high quality were evaluated. Patients with cleft lip and/or palate or syndromes were excluded. Teeth with morphological alterations such as fused roots were excluded. Orthodontically treated teeth, endodontically treated teeth, internal or external root resorption, root with associated cist or open apex root were also excluded. The total sample size was calculated using the following assumptions based in our previous results from our study that showed the prevalence of straight and curved lateral incisor in this population [ 10 ]. We assumed a difference of 20% per group. A significance level of 95% and power of 80% was accepted for the purpose of sample size calculation. Therefore, a minimum sample size of 186 individuals was needed for the study. Maxillary lateral incisors root curvature measurements A dentist trained by an endodontist performed all the measurements as previously reported [ 10 ]. Briefly, 10 random OPGs were measured twice in a 2-week interval to assess intra-examiner reliability. The intraclass correlation (ICC) was then calculated and the results showed that the ICCs were greater than 0.80. A well-established protocol to evaluate root curvature was used in the present study [ 20 ]. The degree of the root curvature was estimated according to Schneider method (1971) that uses two straight lines, in which the first line represented the continuity of the apical region, and the second line followed the middle and coronal thirds of the root [ 10 ]. The angle between the lines was geometrically measured, and this curvature was expressed in degrees. More details of the method are shown in the Fig. 1. Statistical analysis The measurements expressed in degrees were used for continuous analysis. Additionally, each incisor was classified based on the degree of curvature established by Schneider (1971), as straight (5° or less) or curved (higher than 5°) as previously reported in our study [ 10 ]. All analyses were performed on GraphPad Prism 9 package (Graph-Pad, San Diego, CA, USA). Root curvature measurements (angle °) were evaluated as continuous data. To compare curvature degree among genders, t test was used. To compare left and right degree differences, a paired t-test was used. The data were expressed as mean ± standard deviation (SD) Chi-squared test and Odds ratio were used to calculate gender and laterality among straight or curved root groups, and the data was expressed as frequency (%). The established alpha was 5% for all analysis. RESULTS A total of 230 individuals/OPGs were included and evaluated. Ninety-seven were males and 133 were females, and their age ranged from 11 to 64 years old. A total 198 left maxillary incisors and 201 right maxillary incisors were measured. The distribution of root morphology classification (straight or curved) according to the gender (and side) are presented in the Table 1 . There were no statistical significance differences between gender in the categorical analyses (p > 0.05). Table 2 presents comparison between left and right regardless the gender. A statistical difference was observed, in which straight root was more common in the left side (p = 0.028; odds ratio = 1.5, confidence interval 95%: 1.1–2.4). Table 3 shows the comparisons of the root curvature degree between genders for each incisor. In the left incisor of males, the mean curvature degree was 5.9° (SD = 4.4°), while in the right incisor of males, the mean curvature degree was 7.7° (SD = 5.2°). In the left incisor of females, the mean curvature degree was 7.5° (SD = 5.3°), while in the right incisor of females, the mean curvature degree was 8.4° (SD = 6.1°). A gender difference was observed in the continuous data analysis for the left incisor (p = 0.030). Figure 2 shows the means comparisons between left and right incisor regardless the genders. In the left incisor, the mean curvature degree was 6.7° (SD = 4.9°), while in the right incisor, the mean curvature degree was 8.3° (SD = 5.9°). A statistical significant difference between sides was observed in the continuous data analysis (p = 0.0001). DISCUSSION The development of dental germs is closely related in terms of anatomical position, time and genetic background with the establishment of cleft lip and/or palate [ 21 ]. The reconstructions of humans’ maxilla showed that maxillary lateral incisors have a double origin, since it has a developmentally contribution from the two facial processes [ 22 ], which explain the connection between cleft and the high frequency of developmental dental anomalies in the maxillary lateral incisor. Therefore, we decided to investigate if a root developmental alteration commonly observed in maxillary lateral incisor present a similar trend of cleft lip and/or palate, showing gender and side preference. The results observed here is interesting and brings new knowledge regarding dental development. Sexual dimorphism shows a set of morphologic features in the shape or size that differentiate a male from a female. Gender predilection in cleft lip with or without palate is well known in the literature. Isolated cleft palate is more frequent in females [ 11 , 14 , 15 , 23 ], while cleft lip with or without palate are more frequent in males [ 16 , 17 , 23 ]. Some odontometric parameters also clearly present sexual dimorphism, such as dental size [ 24 ] Gender preference is also observed in isolated tooth agenesis, in which maxillary lateral incisor agenesis is more frequent in males, while premolar agenesis is also more common in females [ 25 ]. However, the gender preference in other dental developmental alterations are poorly explored. In our study we observed for the first time that gender difference may also exist in root curvature, in which males presented smaller curvatures. A number of traits have differences in laterality. In fact, side preference is also a topic explored in different conditions, including in dental research. Tooth agenesis is more commonly observed as an unilateral condition than a bilateral condition [ 26 ]. Unilateral cleft lip with or without cleft palate is four times more prevalent than bilateral cleft. For unilateral clefts, around 70% occur on the left side [ 11 – 13 , 27 ]. Asymmetry cannot be interpreted as a single biological process. It is a manifestation of many biological processes. This phenomenon is called fluctuating asymmetry that means small differences between the left and right sides due to random imprecisions in developmental processes [ 28 ]. It occurs as small differences between the left and the right sides and is the individual’s variation from the average directional asymmetry [ 28 , 29 ]. In our study, left-right asymmetry was observed in both analysis, in the analysis as a continuous data and as a dichotomous data classifying the root as straight or curved according to Schneider in 1971. Root curvature is historically described using the system created by Schneider (1971). Schneider introduced a simple method that uses parameters to determine the degree of root curvature (one line parallel to the long axis of the canal and other line from the apical foramen to intersect of the line), where the canal starts to leave the long axis of the canal. This angle that is formed is the degree of root curvature. This method has been widely used in past decades. Briefly, it is important to understand more about the characteristics and etiology of the traits that affect the maxillary lateral incisor area, then we can better interpret the complex etiology of oral cleft and developmental dental anomalies. Interestingly, a remarkable observation in cleft field is that cleft lip with or without cleft palate have nonrandom laterality, and presents left-side preference of the unilateral cases [ 11 – 13 ]. In our study, a straight root morphology had a 50% increase in the odds for left side. The root apical curvature degree was also statistically significant lower in the left side. Left-sided clefts are twice as common as right-sided clefts for reasons that are not well understood [ 30 ]. And future studies should also evaluate the maxillary lateral incisor developmental alterations pattern to explore side and gender preference in these phenotypes. CONCLUSION Our study confirmed the hypotheses that root apical curvature of maxillary lateral incisors has gender and side preference in the general population. Table 1 Comparison of the root morphology according to the gender Morphology Left incisor n(%) Right incisor n(%) Male Female p-value OR(CI95%) Male Female p-value OR (CI95%) Straight 37 (45.7) 45 (38.5) 0.310 1.3 (0.7–2.3) 25 (32.0) 37 (30.1) 0.768 1.1 (0.6-2.0) Curved 44 (54.3) 72 (61.5) 53 (67.9) 86 (69.9) Note: Chi-square was used. OR means odds ratio; CI means confidence interval. Chi-square was used Table 2 Comparison of the root morphology according to the side Morphology Left Right p-value OR (CI95%) Straight 82 (41.4) 62 (30.8) 0.028* 1.5 (1.1–2.4) Curved 116 (58.6) 139 (69.1) Note: Chi-square was used. OR means odds ratio; CI means confidence interval. Chi-square was used. *means statistical significance difference Table 3 Apical curvature degree° according to the gender. Side Gender Minimum-maximum Mean (SD) p-value Left Male 0.01–23.27 5.9 (4.4) 0.030* Female 0.27–28.85 7.5 (5.3) Right Male 0.09–32.04 7.7 (5.2) 0.433 Female 0.10–37.95 8.4 (6.1) Note: t-test was used. *means statistical significance difference Figure 1. Representation of the lines establishment and degree measurement of root apical curvature of maxillary lateral incisor. The measurement was according to the Schneider method reported in 1971. Figure 2. Means apical curvature angle comparison among sides. Paired t-test was used. ***means statistical significance difference (p = 0.0001). Declarations Ethics approval and consent to participate This study was approved by the Research Ethics Committee from Ribeirão Preto Dental School, University of São Paulo (number: 3.150.551). The assent and consent were obtained from the children and their legal guardians, respectively. Acknowledgment Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) Funding This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001 and National Council for Scientific and Technological Development (CNPq) (307733/2022-0) for individual scholarships. Data Availability Statement The datasets generated for this study are available upon reasonable request. Conflict of interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. References Dalgorf D, Higgins K. Reconstruction of the midface and maxilla. Curr Opin Otolaryngol Head Neck Surg. 2008;16(4):303–311. Hovorakova M, Lesot H, Peterka M, Peterkova R. Early development of the human dentition revisited. J Anat. 2018;233(2):135–145. 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Hypodontia: An Update on Its Etiology, Classification, and Clinical Management. Biomed Res Int. 2017;20179378325. Vyas T, Gupta P, Kumar S, Gupta R, Gupta T, Singh HP. Cleft of lip and palate: A review J Family Med Prim Care. 2020 Jun 30;9(6):2621-2625. Klingenberg C. A developmental perspective on developmental instability: Theory, models and mechanisms. 2003;14--34. Klingenberg CP. Size, shape, and form: concepts of allometry in geometric morphometrics. Dev Genes Evol. 2016;226(3):113-137. Gallagher ER, Collett BR, Barron S, Romitti P, Ansley T, Wehby GL. Laterality of Oral Clefts and Academic Achievement. Pediatrics. 2017;139(2):e20162662. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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. 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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-5066252","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":373952300,"identity":"f31798b4-b5d8-4afa-bc90-640b55868dec","order_by":0,"name":"Erika 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establishment and degree measurement of root apical curvature of maxillary lateral incisor. The measurement was according to the Schneider method reported in 1971.\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-5066252/v1/ff640d70ba1f00e0e31470da.png"},{"id":69350399,"identity":"25c232f6-aeda-4205-90d9-d7c1aab327e5","added_by":"auto","created_at":"2024-11-19 13:01:35","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":21273,"visible":true,"origin":"","legend":"\u003cp\u003eMeans apical curvature angle comparison among sides. Paired t-test was used. ***means statistical significance difference (p=0.0001).\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-5066252/v1/dbc8d27422d77d78649ad34d.png"},{"id":73259419,"identity":"d9db3321-5c4d-4b95-802e-a0682ee86a20","added_by":"auto","created_at":"2025-01-08 09:09:26","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":500202,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5066252/v1/45448a46-f4a0-49c0-8e9a-e797b0d23ecd.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The assessment of root apical curvature of maxillary lateral incisors phenotypes reveals side and gender difference","fulltext":[{"header":"BACKGROUND","content":"\u003cp\u003eThe maxilla in vertebrates is the upper bone of the jaw and is the most important bone of the midface. It has a central location and provides structural support to the viscerocranium and fundamental role in facial architecture and contains the maxillary sinus. It also separates the nasal and oral cavities including superior teeth [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Maxilla is formed by the fusion of the paired medial nasal and maxillary processes, which occurs in the area where the lateral incisor is locate, therefore fails in the fusion process could explain the occurrence of cleft lip with or without cleft palate and developmental dental alteration [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. In fact, several studies have been demonstrating that patients with cleft lip with or without cleft palate have a higher risk to present maxillary lateral incisor anomalies such as dental agenesis, microdontia/peg-shaped, supernumerary teeth and tooth impactation in the cleft area and also in the non-cleft area (contralateral side) [\u003cspan additionalcitationids=\"CR4 CR5\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eNumerous studies have also demonstrated that cleft related genes are also associated with isolated dental anomalies, such as non-syndromic tooth agenesis [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Recently we also observed that genes encoding Bone Morphogenetic Protein (BMP), which are well-known involved in cleft lip with or without cleft palate [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] and tooth agenesis [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], were associated with root curvature of maxillary lateral incisors [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Therefore, it is possible that some trends observed in cleft epidemiological studies could also be observed in dental phenotypes studies. Side preference and gender preference are well-explored in cleft research. The phenotypes involved unilateral cleft lip affects more frequently the left side than the right side [\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] Gender preference is also observed in cleft studies, cleft palate is more common in females [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], while cleft lip with or without palate are more frequent in males [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMuch evidence has been accumulated over the past century to indicate that oral cleft has a side and gender preference. However, the possibility that the same trend is observed in other anomalies that affect the maxillary lateral incisor area (the area where fusion of the paired medial nasal and maxillary processes occurs) have been poorly explored. Maxillary lateral incisors root angulation is a common developmental condition characterized by an alteration in the axial inclination between the crown and root of the incisor, in which a curvature of varied angle of the dental root is observed [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Therefore, in the present study, we hypothesized that the root apical curvature of maxillary lateral incisors has gender and side preference as observed in patients with cleft lip and/or palate.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cp\u003eThe present cross-sectional study included panoramic radiographs from non-syndromic patients as previously reported [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The study was only conducted after the approval of the study by the Research Ethics Committee from Ribeir\u0026atilde;o Preto Dental School, University of S\u0026atilde;o Paulo (number: 3.150.551), in accordance with latest version of Declaration of Helsinki guidelines. The dental records of the individuals were only included in the project after all the patients gave their written informed consent to participate in the study. If the individual were under 18 years old, an assent from the patient was also obtained beside an informed consent from their legal guardian.\u003c/p\u003e \u003cp\u003eDental records including anamnesis and orthopantomographs (OPG) from patients undergoing dental treatment in universities and private clinics in Curitiba (Paran\u0026aacute; state) and Ribeir\u0026atilde;o Preto (S\u0026atilde;o Paulo) in Brazil were screened. Only OPG with high quality were evaluated. Patients with cleft lip and/or palate or syndromes were excluded. Teeth with morphological alterations such as fused roots were excluded. Orthodontically treated teeth, endodontically treated teeth, internal or external root resorption, root with associated cist or open apex root were also excluded.\u003c/p\u003e \u003cp\u003eThe total sample size was calculated using the following assumptions based in our previous results from our study that showed the prevalence of straight and curved lateral incisor in this population [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. We assumed a difference of 20% per group. A significance level of 95% and power of 80% was accepted for the purpose of sample size calculation. Therefore, a minimum sample size of 186 individuals was needed for the study.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eMaxillary lateral incisors root curvature measurements\u003c/h2\u003e \u003cp\u003eA dentist trained by an endodontist performed all the measurements as previously reported [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Briefly, 10 random OPGs were measured twice in a 2-week interval to assess intra-examiner reliability. The intraclass correlation (ICC) was then calculated and the results showed that the ICCs were greater than 0.80.\u003c/p\u003e \u003cp\u003eA well-established protocol to evaluate root curvature was used in the present study [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. The degree of the root curvature was estimated according to Schneider method (1971) that uses two straight lines, in which the first line represented the continuity of the apical region, and the second line followed the middle and coronal thirds of the root [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The angle between the lines was geometrically measured, and this curvature was expressed in degrees. More details of the method are shown in the Fig.\u0026nbsp;1.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eThe measurements expressed in degrees were used for continuous analysis. Additionally, each incisor was classified based on the degree of curvature established by Schneider (1971), as straight (5\u0026deg; or less) or curved (higher than 5\u0026deg;) as previously reported in our study [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAll analyses were performed on GraphPad Prism 9 package (Graph-Pad, San Diego, CA, USA). Root curvature measurements (angle \u0026deg;) were evaluated as continuous data. To compare curvature degree among genders, t test was used. To compare left and right degree differences, a paired t-test was used. The data were expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD)\u003c/p\u003e \u003cp\u003eChi-squared test and Odds ratio were used to calculate gender and laterality among straight or curved root groups, and the data was expressed as frequency (%).\u003c/p\u003e \u003cp\u003eThe established alpha was 5% for all analysis.\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eA total of 230 individuals/OPGs were included and evaluated. Ninety-seven were males and 133 were females, and their age ranged from 11 to 64 years old. A total 198 left maxillary incisors and 201 right maxillary incisors were measured. The distribution of root morphology classification (straight or curved) according to the gender (and side) are presented in the Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. There were no statistical significance differences between gender in the categorical analyses (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e presents comparison between left and right regardless the gender. A statistical difference was observed, in which straight root was more common in the left side (p\u0026thinsp;=\u0026thinsp;0.028; odds ratio\u0026thinsp;=\u0026thinsp;1.5, confidence interval 95%: 1.1\u0026ndash;2.4).\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e shows the comparisons of the root curvature degree between genders for each incisor. In the left incisor of males, the mean curvature degree was 5.9\u0026deg; (SD\u0026thinsp;=\u0026thinsp;4.4\u0026deg;), while in the right incisor of males, the mean curvature degree was 7.7\u0026deg; (SD\u0026thinsp;=\u0026thinsp;5.2\u0026deg;). In the left incisor of females, the mean curvature degree was 7.5\u0026deg; (SD\u0026thinsp;=\u0026thinsp;5.3\u0026deg;), while in the right incisor of females, the mean curvature degree was 8.4\u0026deg; (SD\u0026thinsp;=\u0026thinsp;6.1\u0026deg;). A gender difference was observed in the continuous data analysis for the left incisor (p\u0026thinsp;=\u0026thinsp;0.030).\u003c/p\u003e \u003cp\u003eFigure 2 shows the means comparisons between left and right incisor regardless the genders. In the left incisor, the mean curvature degree was 6.7\u0026deg; (SD\u0026thinsp;=\u0026thinsp;4.9\u0026deg;), while in the right incisor, the mean curvature degree was 8.3\u0026deg; (SD\u0026thinsp;=\u0026thinsp;5.9\u0026deg;). A statistical significant difference between sides was observed in the continuous data analysis (p\u0026thinsp;=\u0026thinsp;0.0001).\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThe development of dental germs is closely related in terms of anatomical position, time and genetic background with the establishment of cleft lip and/or palate [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. The reconstructions of humans\u0026rsquo; maxilla showed that maxillary lateral incisors have a double origin, since it has a developmentally contribution from the two facial processes [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], which explain the connection between cleft and the high frequency of developmental dental anomalies in the maxillary lateral incisor. Therefore, we decided to investigate if a root developmental alteration commonly observed in maxillary lateral incisor present a similar trend of cleft lip and/or palate, showing gender and side preference. The results observed here is interesting and brings new knowledge regarding dental development.\u003c/p\u003e \u003cp\u003eSexual dimorphism shows a set of morphologic features in the shape or size that differentiate a male from a female. Gender predilection in cleft lip with or without palate is well known in the literature. Isolated cleft palate is more frequent in females [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e], while cleft lip with or without palate are more frequent in males [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Some odontometric parameters also clearly present sexual dimorphism, such as dental size [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] Gender preference is also observed in isolated tooth agenesis, in which maxillary lateral incisor agenesis is more frequent in males, while premolar agenesis is also more common in females [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. However, the gender preference in other dental developmental alterations are poorly explored. In our study we observed for the first time that gender difference may also exist in root curvature, in which males presented smaller curvatures.\u003c/p\u003e \u003cp\u003eA number of traits have differences in laterality. In fact, side preference is also a topic explored in different conditions, including in dental research. Tooth agenesis is more commonly observed as an unilateral condition than a bilateral condition [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Unilateral cleft lip with or without cleft palate is four times more prevalent than bilateral cleft. For unilateral clefts, around 70% occur on the left side [\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Asymmetry cannot be interpreted as a single biological process. It is a manifestation of many biological processes. This phenomenon is called fluctuating asymmetry that means small differences between the left and right sides due to random imprecisions in developmental processes [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. It occurs as small differences between the left and the right sides and is the individual\u0026rsquo;s variation from the average directional asymmetry [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. In our study, left-right asymmetry was observed in both analysis, in the analysis as a continuous data and as a dichotomous data classifying the root as straight or curved according to Schneider in 1971.\u003c/p\u003e \u003cp\u003eRoot curvature is historically described using the system created by Schneider (1971). Schneider introduced a simple method that uses parameters to determine the degree of root curvature (one line parallel to the long axis of the canal and other line from the apical foramen to intersect of the line), where the canal starts to leave the long axis of the canal. This angle that is formed is the degree of root curvature. This method has been widely used in past decades.\u003c/p\u003e \u003cp\u003eBriefly, it is important to understand more about the characteristics and etiology of the traits that affect the maxillary lateral incisor area, then we can better interpret the complex etiology of oral cleft and developmental dental anomalies. Interestingly, a remarkable observation in cleft field is that cleft lip with or without cleft palate have nonrandom laterality, and presents left-side preference of the unilateral cases [\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. In our study, a straight root morphology had a 50% increase in the odds for left side. The root apical curvature degree was also statistically significant lower in the left side. Left-sided clefts are twice as common as right-sided clefts for reasons that are not well understood [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. And future studies should also evaluate the maxillary lateral incisor developmental alterations pattern to explore side and gender preference in these phenotypes.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eOur study confirmed the hypotheses that root apical curvature of maxillary lateral incisors has gender and side preference in the general population.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of the root morphology according to the gender\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cem\u003eMorphology\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cspan type=\"ItalicUnderline\" class=\"ItalicUnderline\" name=\"Emphasis\"\u003eLeft incisor n(%)\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e\u003cspan type=\"ItalicUnderline\" class=\"ItalicUnderline\" name=\"Emphasis\"\u003eRight incisor n(%)\u003c/span\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOR(CI95%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eOR (CI95%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eStraight\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e37 (45.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45 (38.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.310\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e1.3 (0.7\u0026ndash;2.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e25 (32.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e37 (30.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.768\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e1.1 (0.6-2.0)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCurved\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e44 (54.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e72 (61.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e53 (67.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e86 (69.9)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"9\" nameend=\"c9\" namest=\"c1\"\u003e \u003cp\u003eNote: Chi-square was used. OR means odds ratio; CI means confidence interval. Chi-square was used\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of the root morphology according to the side\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eMorphology\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLeft\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRight\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOR (CI95%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eStraight\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e82 (41.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e62 (30.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.028*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e1.5 (1.1\u0026ndash;2.4)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCurved\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e116 (58.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e139 (69.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eNote: Chi-square was used. OR means odds ratio; CI means confidence interval. Chi-square was used. *means statistical significance difference\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eApical curvature degree\u0026deg; according to the gender.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eSide\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMinimum-maximum\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean (SD)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003eLeft\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.01\u0026ndash;23.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5.9 (4.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.030*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.27\u0026ndash;28.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.5 (5.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003eRight\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.09\u0026ndash;32.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.7 (5.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.433\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.10\u0026ndash;37.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.4 (6.1)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e \u003cp\u003eNote: t-test was used. *means statistical significance difference\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFigure 1. Representation of the lines establishment and degree measurement of root apical curvature of maxillary lateral incisor. The measurement was according to the Schneider method reported in 1971.\u003c/p\u003e \u003cp\u003eFigure 2. Means apical curvature angle comparison among sides. Paired t-test was used. ***means statistical significance difference (p\u0026thinsp;=\u0026thinsp;0.0001).\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Research Ethics Committee from Ribeir\u0026atilde;o Preto Dental School, University of S\u0026atilde;o Paulo (number: 3.150.551). The assent and consent were obtained from the children and their legal guardians, respectively.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003eAcknowledgment\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCoordena\u0026ccedil;\u0026atilde;o de Aperfei\u0026ccedil;oamento de Pessoal de N\u0026iacute;vel Superior \u0026ndash; Brasil (CAPES)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was financed in part by the Coordena\u0026ccedil;\u0026atilde;o de Aperfei\u0026ccedil;oamento de Pessoal de N\u0026iacute;vel Superior \u0026ndash; Brasil (CAPES) \u0026ndash; Finance Code 001\u0026nbsp;and National Council for Scientific and Technological Development (CNPq) (307733/2022-0) for individual scholarships.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated for this study are available upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eDalgorf D, Higgins K. Reconstruction of the midface and maxilla. Curr Opin Otolaryngol Head Neck Surg. 2008;16(4):303\u0026ndash;311.\u003c/li\u003e\n\u003cli\u003eHovorakova M, Lesot H, Peterka M, Peterkova R. Early development of the human dentition revisited. J Anat. 2018;233(2):135\u0026ndash;145.\u003c/li\u003e\n\u003cli\u003eAntunes LDS, K\u0026uuml;chler EC, Tannure PN, Lotsch PF, Costa Mde C, Gouv\u0026ecirc;a CV, Olej B, Granjeiro JM. TGFB3 and BMP4 polymorphism are associated with isolated tooth agenesis. Acta Odontol Scand. 2012;70(3):202\u0026ndash;206. \u003c/li\u003e\n\u003cli\u003eK\u0026uuml;chler EC, Gomes Da Motta, L, Vieira AR, Granjeiro JM. Side of dental anomalies and taurodontism as potential clinical markers for cleft subphenotypes. Cleft Palate Craniofac J. 2011;48(1):103\u0026ndash;108.\u003c/li\u003e\n\u003cli\u003eParana\u0026iacute;ba LM, de Aquino SN, Bufalino A, Martelli-J\u0026uacute;nior H, Graner E, Brito LA, e Passos-Bueno MR, Coletta RD, Swerts MS. Contribution of polymorphisms in genes associated with craniofacial development to the risk of nonsyndromic cleft lip and/or palate in the Brazilian population. Med Oral Patol Oral Cir Bucal. 2013;18(3):e414-420.\u003c/li\u003e\n\u003cli\u003ePhan M, Conte F, Khandelwal KD, Ockeloen CW, Bartzela T, Kleefstra T, van Bokhoven H, Rubini M, Zhou H, Carels CE. Tooth agenesis and orofacial clefting: genetic brothers in arms? Hum Genet. 2016;135(12):1299\u0026ndash;1327.\u003c/li\u003e\n\u003cli\u003eK\u0026uuml;chler EC, Reis CLB, Silva-Sousa AC, Mara\u0026ntilde;\u0026oacute;n-V\u0026aacute;squez GA, Matsumoto MAN, Sebastiani A, Scariot R, Paddenberg E, Proff P, Kirschneck C.Exploring the Association Between Genetic Polymorphisms in Genes Involved in Craniofacial Development and Isolated Tooth Agenesis. Front Physiol. 2021;12723105.\u003c/li\u003e\n\u003cli\u003eLi YH, Yang J, Zhang JL, Liu JQ, Zheng Z, Hu DH.BMP4 rs17563 polymorphism and nonsyndromic cleft lip with or without cleft palate: A meta-analysis. Medicine (Baltimore). 2017;96(31):e7676.\u003c/li\u003e\n\u003cli\u003eLu Y, Qian Y, Zhang J, Gong M, Wang Y, Gu N, Ma L, Xu M, Ma J, Zhang W, Pan Y, Wang L. Genetic Variants of BMP2 and Their Association with the Risk of Non-Syndromic Tooth Agenesis. PloS One. 2016;11(6):e0158273.\u003c/li\u003e\n\u003cli\u003eK\u0026uuml;chler EC, de Oliveira Stroparo JL, Bitencourt Reis CL, Ullrich N, Olsson B, Scariot R, Matsumoto MN, Ribeiro Mattos NH, Proff P, Baratto-Filho F, Kirschneck C.Oral Cleft Related-Genes may be Involved in Root Curvature of Maxillary Lateral Incisors. Cleft Palate Craniofac J.. 2022;105566562211210.\u003c/li\u003e\n\u003cli\u003eFreitas JA, Dalben Gda S, Santamaria M Jr, Freitas PZ. Current data on the characterization of oral clefts in Brazil Informações atuais sobre a caracterização das fissuras orofaciais no Brasil. Braz Oral Res. 2004;18(2):128\u0026ndash;133.\u003c/li\u003e\n\u003cli\u003eJamilian A, Lucchese A, Darnahal A, Kamali Z, Perillo L. Cleft sidedness and congenitally missing teeth in patients with cleft lip and palate patients. Prog Orthod. 2016;1714.\u003c/li\u003e\n\u003cli\u003eKim NY, Baek SH. Cleft sidedness and congenitally missing or malformed permanent maxillary lateral incisors in Korean patients with unilateral cleft lip and alveolus or unilateral cleft lip and palate. Am J Orthod Dentofacial Orthop. 2006;130(6):752\u0026ndash;8.\u003c/li\u003e\n\u003cli\u003eGorlin R, Cohen M, Hennekam R. Syndromes of the head and neck. 4th ed. New York: Oxford University Press, 2001.\u003c/li\u003e\n\u003cli\u003eMartelli-Junior H, Porto LV, Martelli DR, Bonan PR, Freitas AB, Della Coletta R.. Prevalence of nonsyndromic oral clefts in a reference hospital in the state of Minas Gerais, Brazil, between 2000-2005. Braz Oral Res. 2007;21(4):314\u0026ndash;317.\u003c/li\u003e\n\u003cli\u003eMartelli-J\u0026uacute;nior H, Orsi J\u0026uacute;nior J, Chaves MR, Barros LM, Bonan, PRF, Freitas JAS. Epidemiologic study of cleft lip and palate in Alfenas - Minas Gerais - from 1986 to 1998. 2006.\u003c/li\u003e\n\u003cli\u003eNagase Y, Natsume N, Kato T, Hayakawa T. Epidemiological Analysis of Cleft Lip and/or Palate by Cleft Pattern. J Maxillofac Oral Surg. 2010;9(4):389\u0026ndash;395.\u003c/li\u003e\n\u003cli\u003eSilva BF, Costa, LED, Beltr\u0026atilde;o RV, Rodrigues TL, Farias RL, Beltr\u0026atilde;o RTS. Prevalence assessment of root dilaceration in permanent incisors. Dental Press J. Orthod. 2012;17(6):97\u0026ndash;102.\u003c/li\u003e\n\u003cli\u003eWeckwerth GM, Santos CF, Brozoski DT, Centurion BS, Pagin O, Lauris JR, Carvalho IM, Neves LT. Taurodontism, Root Dilaceration, and Tooth Transposition: A Radiographic Study of a Population with Nonsyndromic Cleft Lip and/or Palate. Cleft Palate Craniofac J. 2016;53(4):404\u0026ndash;412.\u003c/li\u003e\n\u003cli\u003eSchneider SW. A comparison of canal preparations in straight and curved root canals. Oral Surg Oral Med Oral Pathol. 1971;32(2):271\u0026ndash;275.\u003c/li\u003e\n\u003cli\u003eStahl F, Grabowski R, Wigger K. Epidemiology of Hoffmeister\u0026rsquo;s \u0026ldquo;Genetically Determined Predisposition to Disturbed Development of the Dentition\u0026rdquo; in Patients with Cleft Lip and Palate. Cleft Palate Craniofac J. 2006;43(4):457\u0026ndash;465.\u003c/li\u003e\n\u003cli\u003eHovorakova M, Lesot H, Peterkova R, Peterka M. Origin of the Deciduous Upper Lateral Incisor and its Clinical Aspects. J Dent Res. 2006;85(2):167\u0026ndash;171.\u003c/li\u003e\n\u003cli\u003eImpellizzeri A, Giannantoni I, Polimeni A, Barbato E, Galluccio G. Epidemiological characteristic of Orofacial clefts and its associated congenital anomalies: retrospective study. BMC Oral Health. 2019;19(1):290.\u003c/li\u003e\n\u003cli\u003eCapitaneanu C, Willems G, Thevissen P. A systematic review of odontological sex estimation methods. J Forensic Odontostomatol. 2017;35(2):1\u0026ndash;19.\u003c/li\u003e\n\u003cli\u003eK\u0026uuml;chler EC, Risso PA, Costa Mde C, Modesto A, Vieira AR. Studies of dental anomalies in a large group of school children. Arch Oral Biol. 2008;53(10):941\u0026ndash;946.\u003c/li\u003e\n\u003cli\u003eAl-Ani AH, Antoun JS, Thomson WM, Merriman TR, Farella M. Hypodontia: An Update on Its Etiology, Classification, and Clinical Management. Biomed Res Int. 2017;20179378325.\u003c/li\u003e\n\u003cli\u003eVyas T, Gupta P, Kumar S, Gupta R, Gupta T, Singh HP. Cleft of lip and palate: A review J Family Med Prim Care. 2020 Jun 30;9(6):2621-2625.\u003c/li\u003e\n\u003cli\u003eKlingenberg C. A developmental perspective on developmental instability: Theory, models and mechanisms. 2003;14--34.\u003c/li\u003e\n\u003cli\u003eKlingenberg CP. Size, shape, and form: concepts of allometry in geometric morphometrics. Dev Genes Evol. 2016;226(3):113-137.\u003c/li\u003e\n\u003cli\u003eGallagher ER, Collett BR, Barron S, Romitti P, Ansley T, Wehby GL. Laterality of Oral Clefts and Academic Achievement. Pediatrics. 2017;139(2):e20162662.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"dental dilacerations, dental anomaly, dental development, oral cleft","lastPublishedDoi":"10.21203/rs.3.rs-5066252/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5066252/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e \u003cb\u003eBACKGROUND\u003c/b\u003e \u003c/p\u003e \u003cp\u003eMaxillary lateral incisors root angulation is a common developmental aspect characterized by an alteration in the axial inclination between the crown and root of the incisor, in which a curvature of varied angle of the dental root is observed. This study investigated if root apical curvature of maxillary lateral incisors has gender and side preference as observed in patients with cleft lip and/or palate.\u003c/p\u003e \u003cp\u003e \u003cb\u003eMETHODS\u003c/b\u003e \u003c/p\u003e \u003cp\u003ePanoramic radiographs from 230 orthodontic patients were investigated. The method described by Schneider method (1971) was used for the estimation of the degree of root apical curvature of maxillary lateral incisors and to classify the root as straight (5\u0026deg; or less) or curved (higher than 5\u0026deg;). To compare curvature degree among genders, t test was used, and to compare left and right degree differences, a paired t-test was used. Chi-squared test and Odds ratio were used to calculate gender and laterality differences among straight or curved root groups. The established alpha was 5%.\u003c/p\u003e \u003cp\u003e \u003cb\u003eRESULTS\u003c/b\u003e \u003c/p\u003e \u003cp\u003eNinety-seven were males and 133 were females. A total 198 left maxillary incisors and 201 right maxillary incisors were measured. A statistical difference was observed, in which straight root was more common in the left side (p\u0026thinsp;=\u0026thinsp;0.028; odds ratio\u0026thinsp;=\u0026thinsp;1.5, confidence interval 95%: 1.1\u0026ndash;2.4). On left incisors, the mean curvature degree was 5.9\u0026deg; (SD\u0026thinsp;=\u0026thinsp;4.4\u0026deg;) in males, while the mean curvature degree was 7.5\u0026deg; (SD\u0026thinsp;=\u0026thinsp;5.3\u0026deg;) in females (p\u0026thinsp;=\u0026thinsp;0.030). Means comparisons between left and right incisor regardless the gender showed a statistical significant difference between sides (p\u0026thinsp;=\u0026thinsp;0.0001).\u003c/p\u003e \u003cp\u003e \u003cb\u003eCONCLUSIONS\u003c/b\u003e \u003c/p\u003e \u003cp\u003eOur study confirmed the hypotheses that root apical curvature of maxillary lateral incisors has gender and side preference in the general population.\u003c/p\u003e","manuscriptTitle":"The assessment of root apical curvature of maxillary lateral incisors phenotypes reveals side and gender difference","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-11-19 13:01:25","doi":"10.21203/rs.3.rs-5066252/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"028a2bea-adf4-4b3b-a36d-3d09e0999275","owner":[],"postedDate":"November 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-01-08T09:09:01+00:00","versionOfRecord":[],"versionCreatedAt":"2024-11-19 13:01:25","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-5066252","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5066252","identity":"rs-5066252","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}