An in vitro assessment of teething gels' effects on human gingival mesenchymal stem cells.

BACKGROUND: The aim of this study is to examine the cytotoxic effects of dental gels with different contents, which are frequently used during teething, on gingival mesenchymal stem cells (G-MSCs). METHOD: The teething gels used in this study were Dentinox, Gengigel, Osanite, and Jack and Jill. The human gingival mesenchimal stem cells (hG-MSCs) were incubated with these teething gel solutions (0.1%, 50% and 80% concentrations). Reproductive behavior of G-MSCs was monitored in real time for 72 h using the xCELLigence real-time cell analyzer (RTCA) system. Two-way repeated Anova test and post hoc Bonferroni test were used to evaluate the effect of concentration and dental gel on 0-hour and 72-hour viability. Significance was evaluated at p < 0.05 level. RESULTS: Teething gels prepared at 50% concentration are added to the G-MSC culture, the "cell index" value of G-MSCs to which Dentinox brand gel is added is significantly lower than all other groups (p = 0.05). There is a statistically significant difference between the concentrations in terms of cell index values at the 72nd hour compared to the 0th hour (p = 0.001). CONCLUSIONS: The local anesthetic dental gels used in children have a more negative effect on cell viability as concentration increases.

Global overview on current paediatric dentistry teaching: A survey of National Member Societies of the IAPD.

BACKGROUND: Published information on the teaching and recognition of paediatric dentistry (PD) is limited worldwide. AIM: The aim of this study was to investigate the status of current teaching of undergraduate and postgraduate training in PD and identify differences by country-level economic development. DESIGN: Representatives from 80 national member societies of the International Association of Paediatric Dentistry (IAPD) were invited to complete a questionnaire on undergraduate and postgraduate PD curricula, types of postgraduate education offered, and recognition of the specialty. Country economic development level was classified according to the World Bank criteria. The chi-squared test and the Spearman correlation coefficient were used for data analysis (α = 0.005). RESULTS: Response rate was 63%. Teaching of PD at the undergraduate level was present in all countries, but PD specialization, master's, and Doctor of Philosophy (PhD) coursework were offered in 75%, 64%, and 53% of surveyed countries, respectively. Postgraduate specialization courses were offered in a significantly larger proportion of high-income countries than in upper-middle- or lower-middle-income countries (p < .01). In 20% of participating countries, PD was not an officially recognized specialty with no difference in recognition of the specialty by country's economic development level (p = .62). CONCLUSION: Paediatric dentistry is taught at the undergraduate level universally, but at the postgraduate level, significantly fewer courses are available, especially in lower-income countries.

Clinical assessment of deleterious oral habits and dental caries-periodontal parameters among Turkish twins.

Abstract Background/purpose: Twin studies are crucial to assess the relative contribution of genetic and environmental factors. This study was conducted to evaluate association between deleterious oral habits and dental caries-periodontal parameters among Turkish twins. Materials and methods: The study comprised 143 pairs of dizygotic (DZ) twins and 59 pairs of monozygotic (MZ) twins aged 3-15 years. Twins were examined for dental caries, plaque index, gingival index, bleeding on probing and deleterious oral habits. Mann Whitney U test was used to examine the data. Results: The MZ twin pairs consisted of 60 male and 58 female twin pairs, whereas the DZ twin pairs consisted of 144 male and 142 female. The mean age of the twins was 9.63 ± 3.0 in MZ twins and 9.47 ± 3.2 in DZ twins. The mean DMFS value of MZ twins with bruxism is higher than those of MZ twins without bruxism (P = 0.001). The mean DMFS value of DZ twins with pacifier sucking is lower than those without (P = 0.007). A statistically significant difference was found between MZ twins with and without nail biting in terms of bleeding on probing and dmfs values (P = 0.035; P = 0.012). The mean values of the plaque index increased due to the mouth breathing in DZ twins (P = 0.024). Regarding the bleeding on probing, there was a statistically significant difference between MZ twins with and without atypical swallowing (P = 0.016). Conclusion: These findings suggest that dental caries-periodontal parameters are similarly affected by deleterious oral habits in MZ and DZ twins.

FAM20A mutations and transcriptome analyses of dental pulp tissues of enamel renal syndrome.

AIM: Biallelic loss-of-function FAM20A mutations cause amelogenesis imperfecta (AI) type IG, better known as enamel renal syndrome (ERS), characterized by severe enamel hypoplasia, delayed/failed tooth eruption, intrapulpal calcifications, gingival hyperplasia and nephrocalcinosis. FAM20A binds to FAM20C, the Golgi casein kinase (GCK) and potentiates its function to phosphorylate secreted proteins critical for biomineralization. While many FAM20A pathogenic mutations have been reported, the pathogeneses of orodental anomalies in ERS remain to be elucidated. This study aimed to identify disease-causing mutations for patients with ERS phenotypes and to discern the molecular mechanism underlying ERS intrapulpal calcifications. METHODOLOGY: Phenotypic characterization and whole exome analyses were conducted for 8 families and 2 sporadic cases with hypoplastic AI. A minigene assay was performed to investigate the molecular consequences of a FAM20A splice-site variant. RNA sequencing followed by transcription profiling and gene ontology (GO) analyses were carried out for dental pulp tissues of ERS and the control. RESULTS: Biallelic FAM20A mutations were demonstrated for each affected individual, including 7 novel pathogenic variants: c.590-5T>A, c.625T>A (p.Cys209Ser), c.771del (p.Gln258Argfs*28), c.832_835delinsTGTCCGACGGTGTCCGACGGTGTC CA (p.Val278Cysfs*29), c.1232G>A (p.Arg411Gln), c.1297A>G (p.Arg433Gly) and c.1351del (p.Gln451Serfs*4). The c.590-5T>A splice-site mutation caused Exon 3 skipping, which resulted in an in-frame deletion of a unique region of the FAM20A protein, p.(Asp197_Ile214delinsVal). Analyses of differentially expressed genes in ERS pulp tissues demonstrated that genes involved in biomineralization, particularly dentinogenesis, were significantly upregulated, such as DSPP, MMP9, MMP20 and WNT10A. Enrichment analyses indicated overrepresentation of gene sets associated with BMP and SMAD signalling pathways. In contrast, GO terms related to inflammation and axon development were underrepresented. Among BMP signalling genes, BMP agonists GDF7, GDF15, BMP3, BMP8A, BMP8B, BMP4 and BMP6 were upregulated, while BMP antagonists GREM1, BMPER and VWC2 showed decreased expression in ERS dental pulp tissues. CONCLUSIONS: Upregulation of BMP signalling underlies intrapulpal calcifications in ERS. FAM20A plays an essential role in pulp tissue homeostasis and prevention of ectopic mineralization in soft tissues. This critical function probably depends upon MGP (matrix Gla protein), a potent mineralization inhibitor that must be properly phosphorylated by FAM20A-FAM20C kinase complex.

Path Analysis of the Relationships between the Eruption Time of the First Primary Teeth and Various Factors in Twins.

The timing of primary tooth eruption is critical for children's health planning and the diagnosis of specific growth disorders. The purpose of this study is to assess the relationship between twin pairs' birth weight, gestational age, and gender, which are indicators of prenatal factors; breast-feeding duration, which is an indicator of postnatal factors; type of delivery, which is an indicator of maternal as well as genetic factors; and age of the primary tooth. Twin children aged from 3 to 15 years who applied to the clinic for the first dental examination constituted the sample group. In this twin study, 59 monozygotic (MZ) twin pairs and 143 dizygotic (DZ) twin pairs were included. Genetic (MZ vs. DZ), maternal (type of delivery, gestational age), perinatal (birth weight, gender), and postnatal (duration of breastfeeding) information was obtained, and effects on the children's Eruption Timing of the First Primary Tooth (ETFPT) were examined. Statistical analysis was performed using the consistent partial least squares structural equation model (robust PLSc) technique. As birth weight increased, the age at first eruption became younger, but this change was different between MZ and DZ twins (p < 0.05). While the age at first tooth eruption was older in identical twins who were breastfed for the first 6 months, this increase was not observed in DZ twins. The mean of ETFPT was calculated as 7.31 months in MZ twins and 6.75 months in DZ twins. The effect of breastfeeding and birth weight on ETFPT may differ according to zygosity in twins. MZ twins may tend to take longer to experience the eruption of their first primary teeth.

Novel WDR72 Mutations Causing Hypomaturation Amelogenesis Imperfecta.

Amelogenesis imperfecta (AI) is a heterogeneous collection of hereditary enamel defects. The affected enamel can be classified as hypoplastic, hypomaturation, or hypocalcified in form. A better understanding of normal amelogenesis and improvements in our ability to diagnose AI through genetic testing can be realized through more complete knowledge of the genes and disease-causing variants that cause AI. In this study, mutational analysis was performed with whole exome sequencing (WES) to identify genetic etiology underlying the hypomaturation AI condition in affected families. Mutational analyses identified biallelic WDR72 mutations in four hypomaturation AI families. Novel mutations include a homozygous deletion and insertion mutation (NM_182758.4: c.2680_2699delinsACTATAGTT, p.(Ser894Thrfs*15)), compound heterozygous mutations (paternal c.2332dupA, p.(Met778Asnfs*4)) and (maternal c.1287_1289del, p.(Ile430del)) and a homozygous 3694 bp deletion that includes exon 14 (NG_017034.2:g.96472_100165del). A homozygous recurrent mutation variant (c.1467_1468delAT, p.(Val491Aspfs*8)) was also identified. Current ideas on WDR72 structure and function are discussed. These cases expand the mutational spectrum of WDR72 mutations causing hypomaturation AI and improve the possibility of genetic testing to accurately diagnose AI caused by WDR72 defects.

Evaluation of the predictors of oral health-related quality of life among 3-5-year-old children with dental trauma.

This study evaluated the influence of socio-demographic, clinical, and parental psychological factors on oral health-related quality of life (OHRQoL) and determined their predictors in preschool-aged children with traumatic dental injury (TDI). The study sample consisted of 324 dyads of children and their parents attending the Clinics of Pediatric Dentistry at Istanbul University. After clinical examination, the Sense of Coherence (SOC), Generalized Self-Efficacy Scale, Early Childhood Oral Health Impact Scale, and Multidimensional Health Locus of Control Scale-MHLC questionnaires were administered to the parents. The statistical analyses included Spearman correlation coefficients, Mann-Whitney U tests, Kruskal-Wallis tests, multiple linear regression, and confirmatory factor analysis. Having mixed TDI, a non-nuclear family, fewer children, and weak parental SOC were important predictors of worse overall OHRQoL and its sections of child and family. Lower internal health locus of control and dental pain due to TDI were predictors of worse overall OHRQoL and child impact, respectively. Consideration of these predictors may help oral health professionals to develop prevention and treatment programs for TDI and oral health literacy programs for families.

Evaluation of dental students' knowledge, attitudes and behaviors regarding COVID-19 infection: a cross-sectional survey.

BACKGROUND: This study aimed to determine the differences between preclinical and clinical dental students' knowledge, attitudes, and behaviors regarding Coronavirus disease (COVID-19). METHODS: A cross-sectional study was carried out among 303 undergraduate dental students (107 clinical students and 196 preclinical students). Questionnaires were given to the participants using an online data collection platform. The online questionnaire covered the dental students' socio-demographic information and their knowledge, attitudes and behaviors of Coronavirus disease. RESULTS: More frequently than preclinical students, clinical students benefited from the latest information about the COVID-19 outbreak obtained from television, internet news sites, and the World Health Organization website (P<0.05). The use of other protective equipment other than gloves and goggles has changed from "No" before the pandemic to "Yes" onset of the pandemic (P<0.001). The knowledge level of infection control in dentistry increased significantly more for clinical students than for preclinical students (P<0.001). CONCLUSIONS: Although dental students show reasonable knowledge, attitudes and behavior about COVID-19, attention should be taken to provide education on infectious diseases, starting from preclinical classes, and to make real information resources provided by global and national health authorities accessible to students.

Phenotypic variability in LAMA3-associated amelogenesis imperfecta.

OBJECTIVE: Amelogenesis imperfecta (AI) is defined as inherited enamel malformations. LAMA3 (laminin alpha-3) encodes a critical protein component of the basement membrane (laminin-332). Individuals carrying heterozygous LAMA3 mutations have previously been shown to have localized enamel defects. This study aimed to define clinical phenotypes and to discern the genetic etiology for four AI kindreds. MATERIALS AND METHODS: Whole-exome analyses were conducted to search for sequence variants associated with the disorder, and micro-computed tomography (µCT) to characterize the enamel defects. RESULTS: The predominant enamel phenotype was generalized thin enamel with defective pits and grooves. Horizonal bands of hypoplastic enamel with chalky-white discoloration and enamel hypomineralization were also observed and demonstrated by µCT analyses of affected teeth. Four disease-causing LAMA3 mutations (NM_198129.4:c.3712dup; c.5891dup; c.7367del; c.9400G > C) were identified. Compound heterozygous MMP20 mutations (NM_004771.4:c.539A > G; c.692C > T) were also found in one proband with more severe enamel defects, suggesting a mutational synergism on disease phenotypes. Further analyses of the AI-causing mutations suggested that both α3A (short) and α3B (long) isoforms of LAMA3 are essential for enamel formation. CONCLUSIONS: Heterozygous LAMA3 mutations can cause generalized enamel defects (AI1A) with variable expressivity. Laminin-332 is critical not only for appositional growth but also enamel maturation.

Enamel defects in Acp4R110C/R110C mice and human ACP4 mutations.

Human ACP4 (OMIM*606362) encodes a transmembrane protein that belongs to histidine acid phosphatase (ACP) family. Recessive mutations in ACP4 cause non-syndromic hypoplastic amelogenesis imperfecta (AI1J, OMIM#617297). While ACP activity has long been detected in developing teeth, its functions during tooth development and the pathogenesis of ACP4-associated AI remain largely unknown. Here, we characterized 2 AI1J families and identified a novel ACP4 disease-causing mutation: c.774_775del, p.Gly260Aspfs*29. To investigate the role of ACP4 during amelogenesis, we generated and characterized Acp4R110C mice that carry the p.(Arg110Cys) loss-of-function mutation. Mouse Acp4 expression was the strongest at secretory stage ameloblasts, and the protein localized primarily at Tomes' processes. While Acp4 heterozygous (Acp4+/R110C) mice showed no phenotypes, incisors and molars of homozygous (Acp4R110C/R110C) mice exhibited a thin layer of aplastic enamel with numerous ectopic mineralized nodules. Acp4R110C/R110C ameloblasts appeared normal initially but underwent pathology at mid-way of secretory stage. Ultrastructurally, sporadic enamel ribbons grew on mineralized dentin but failed to elongate, and aberrant needle-like crystals formed instead. Globs of organic matrix accumulated by the distal membranes of defective Tomes' processes. These results demonstrated a critical role for ACP4 in appositional growth of dental enamel probably by processing and regulating enamel matrix proteins around mineralization front apparatus.

In vitro evaluation of pediatric restorative materials on human dental pulp stem cells.

This in vitro study aimed to compare the cellular viability of four different restorative materials on human dental pulp stem cells (hDPSCs). The necessary tissues of isolated hDPSCs were obtained from 10 impacted third molars of healthy individuals 19-25 years old undergoing surgical extraction. The effects of GC Fuji IX GP, GC EQUIA Forte, APA Glass Carbomer, and APA Esthetic Fill eluates on hDPSCs' viability on the first, third, and seventh days were examined by flow cytometry using an Annexin V binding assay. The cell viability ratios differed significantly between the restorative material groups (p < 0.001). When the restorative materials and the control group were compared, the control group had the highest cell viability on all experiment days, while the Glass Carbomer group had the highest percentage of viable cells of all the restorative material groups. A significant difference between days in terms of cellular viability (p < 0.001) was found. Considering the early apoptotic cell ratios, no significant difference was found between the groups and days (p > 0.05). Furthermore, based on time, except for the first day of the GC Fuji IX GP group, no statistically significant difference was observed in the early apoptotic cell ratios in each group (p > 0.05). When the rates of late apoptotic cells were compared between the groups, no significant difference was observed, except for with the control group, which had the lowest rate of late apoptotic cells (p < 0.001). However, there was a significant difference in necrotic cell ratios between groups and days (p < 0.001; p = 0.001). The lowest rates of necrotic cells were found in the control group and Glass Carbomer groups, while the rates of necrotic cells were similar among the other groups. Therefore, we concluded that APA Glass Carbomer presents the highest cellular viability among the materials.

Translated Mutant DSPP mRNA Expression Level Impacts the Severity of Dentin Defects.

Hereditary dentin defects are conventionally classified into three types of dentinogenesis imperfecta (DGI) and two types of dentin dysplasia (DD). Mutations in the dentin sialophosphoprotein (DSPP) gene have been identified to cause DGI type II and III and DD type II; therefore, these are not three different conditions, but rather allelic disorders. In this study, we recruited three families with varying clinical phenotypes from DGI-III to DD-II and performed mutational analysis by candidate gene analysis or whole-exome sequencing. Three novel mutations including a silent mutation (NM_014208.3: c.52-2del, c.135+1G>C, and c.135G>A; p.(Gln45=)) were identified, all of which affected pre-mRNA splicing. Comparison of the splicing assay results revealed that the expression level of the DSPP exon 3 deletion transcript correlated with the severity of the dentin defects. This study did not only expand the mutational spectrum of DSPP gene, but also advanced our understanding of the molecular pathogenesis impacting the severity of hereditary dentin defects.

Assessment of Dental Arch Parameters in Turkish Twins.

BACKGROUND: The aim of this study is to investigate the relative contributions of genetic and environmental factors to variations in dental dimensions in a sample of Turkish twins, and to estimate heritability using dental casts. STUDY DESIGN: The study samples were selected from the twin children between 3-15 years old who referred for their first dental examination. Fifty nine monozygotic and one hundred and forty three dizygotic twin pairs were examined in the study. The alginate impression material used to create the plaster model of maxilla and mandible. Anterior arch width, posterior arch width, arch length and arch circumference were measured on models prepared from measurements taken for both maxilla and mandible with digital caliper. The similarities and differences of the measurements were compared between pairs of twins and zygocytes. Morever, the effects of bad oral habits, bruxism, a result of psychosocial factors on measurements were examined. Statistical analysis was performed using Paired T Test, Wilcoxon Test and Mann Whitney U test. RESULTS: A total of 404 dental models of 118 (29.2%) monozygotic and 286 (70.8%) dizygotic twins were evaluated. There was no statistical difference between sibling pairs in both monozygotic and dizygotic twins. The measurement similarity between twin siblings differed according to zygosity in all measurements (p<0.05). It has been observed that the finger sucking and mouth breathing affect the dental arch measurements (p<0.05). CONCLUSION: These results indicate that the differences in dental arch dimensions between monozygotic twin pairs are less than the difference between dizygotic twin pairs.

The Modified Shields Classification and 12 Families with Defined DSPP Mutations.

Mutations in Dentin Sialophosphoprotein (DSPP) are known to cause, in order of increasing severity, dentin dysplasia type-II (DD-II), dentinogenesis imperfecta type-II (DGI-II), and dentinogenesis imperfecta type-III (DGI-III). DSPP mutations fall into two groups: a 5'-group that affects protein targeting and a 3'-group that shifts translation into the −1 reading frame. Using whole-exome sequence (WES) analyses and Single Molecule Real-Time (SMRT) sequencing, we identified disease-causing DSPP mutations in 12 families. Three of the mutations are novel: c.53T>C/p.(Val18Ala); c.3461delG/p.(Ser1154Metfs*160); and c.3700delA/p.(Ser1234Alafs*80). We propose genetic analysis start with WES analysis of proband DNA to identify mutations in COL1A1 and COL1A2 causing dominant forms of osteogenesis imperfecta, 5'-DSPP mutations, and 3'-DSPP frameshifts near the margins of the DSPP repeat region, and SMRT sequencing when the disease-causing mutation is not identified. After reviewing the literature and incorporating new information showing distinct differences in the cell pathology observed between knockin mice with 5'-Dspp or 3'-Dspp mutations, we propose a modified Shields Classification based upon the causative mutation rather than phenotypic severity such that patients identified with 5'-DSPP defects be diagnosed as DGI-III, while those with 3'-DSPP defects be diagnosed as DGI-II.

Cytotoxic effects of different detergent containing children's toothpastes on human gingival epithelial cells.

BACKGROUND: This study aimed to evaluate possible cytotoxic effects to gingival epithelial cells exposed to children toothpastes containing different detergent. METHODS: Tissues required for the isolation of human gingival epithelial cells were obtained by biopsy during the extraction of the impacted third molar tooth. Toothpaste solutions of different concentrations were prepared from five different children's toothpastes with different detergent contents. Isolated gingival epithelial cells were stimulated with experimental groups consisting of toothpaste solutions (Colgate, Sensodyne, Splat, Nenedent, Perlodent) at different concentrations and a control group consisting of complete Dulbecco's modified eagle medium. After the experiments, cell viability was evaluated using flow cytometry. 2 Way ANOVA was used to see the interaction effect of the main effects of toothpaste solution and concentration factors. Pairwise comparisons were made by Tukey post hoc tests. In the study, the significance level was taken as 0.05. RESULTS: As a result of the analysis, it was seen that the toothpaste solution and concentration factors and the interactions of these 2 factors were effective on the viable, early apoptotic, late apoptotic and necrotic cell rates. The statistically highest live cell ratios were detected in Splat's toothpaste solutions (90.14% at 0.4% concentration) after the control group (90.82%) and the group with the lowest viability values was determined in Colgate group (75.74% at 0.4% concentration) (p < 0.05). CONCLUSIONS: According to the results of the study, it was observed that toothpastes containing SLS affected the viability of cells more negatively than toothpastes with other detergent contents.

Novel KLK4 Mutations Cause Hypomaturation Amelogenesis Imperfecta.

Amelogenesis imperfecta (AI) is a group of rare genetic diseases affecting the tooth enamel. AI is characterized by an inadequate quantity and/or quality of tooth enamel and can be divided into three major categories: hypoplastic, hypocalcified and hypomaturation types. Even though there are some overlapping phenotypes, hypomaturation AI enamel typically has a yellow to brown discoloration with a dull appearance but a normal thickness indicating a less mineralized enamel matrix. In this study, we recruited four Turkish families with hypomaturation AI and performed mutational analysis using whole exome sequencing. These analyses revealed two novel homozygous mutations in the KLK4 gene: a nonsense mutation in exon 3 (NM_004917.4:c.170C>A, p.(Ser57*)) was found in families 1, 2 and 3 and a missense mutation in exon 6 (c.637T>C, p.(Cys213Arg)) in family 4. Functional analysis showed that the missense mutation transcript could not translate the mutant protein efficiently or generated an unstable protein that lacked functional activity. The two novel inactivating KLK4 mutations we identified caused a hypomaturation AI phenotype similar to those caused by the four previously described KLK4 nonsense and frameshift mutations. This study improves our understanding of the normal and pathologic mechanisms of enamel formation.

Evaluation of the predictors of oral health-related quality of life among 3-5-year-old children with dental trauma

Abstract This study evaluated the influence of socio-demographic, clinical, and parental psychological factors on oral health-related quality of life (OHRQoL) and determined their predictors in preschool-aged children with traumatic dental injury (TDI). The study sample consisted of 324 dyads of children and their parents attending the Clinics of Pediatric Dentistry at Istanbul University. After clinical examination, the Sense of Coherence (SOC), Generalized Self-Efficacy Scale, Early Childhood Oral Health Impact Scale, and Multidimensional Health Locus of Control Scale-MHLC questionnaires were administered to the parents. The statistical analyses included Spearman correlation coefficients, Mann-Whitney U tests, Kruskal-Wallis tests, multiple linear regression, and confirmatory factor analysis. Having mixed TDI, a non-nuclear family, fewer children, and weak parental SOC were important predictors of worse overall OHRQoL and its sections of child and family. Lower internal health locus of control and dental pain due to TDI were predictors of worse overall OHRQoL and child impact, respectively. Consideration of these predictors may help oral health professionals to develop prevention and treatment programs for TDI and oral health literacy programs for families.

Assessment of Dental Arch Parameters in Turkish Twins.

BACKGROUND: The aim of this study is to investigate the relative contributions of genetic and environmental factors to variations in dental dimensions in a sample of Turkish twins, and to estimate heritability using dental casts. STUDY DESIGN: The study samples were selected from the twin children between 3-15 years old who referred for their first dental examination. Fifty nine monozygotic and one hundred and forty three dizygotic twin pairs were examined in the study. The alginate impression material used to create the plaster model of maxilla and mandible. Anterior arch width, posterior arch width, arch length and arch circumference were measured on models prepared from measurements taken for both maxilla and mandible with digital caliper. The similarities and differences of the measurements were compared between pairs of twins and zygocytes. Morever, the effects of bad oral habits, bruxism, a result of psychosocial factors on measurements were examined. Statistical analysis was performed using Paired T Test, Wilcoxon Test and Mann Whitney U test. RESULTS: A total of 404 dental models of 118 (29.2%) monozygotic and 286 (70.8%) dizygotic twins were evaluated. There was no statistical difference between sibling pairs in both monozygotic and dizygotic twins. The measurement similarity between twin siblings differed according to zygosity in all measurements (p<0.05). It has been observed that the finger sucking and mouth breathing affect the dental arch measurements (p<0.05). CONCLUSION: These results indicate that the differences in dental arch dimensions between monozygotic twin pairs are less than the difference between dizygotic twin pairs.