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(1) Background: Hypodontia has a multifactorial aetiology, in which genetic factors are a major component. Associated with this congenital absence, the formed teeth may show differences in size and shape, which may vary with the specific genetic variants and with the location of the missing teeth. The aims of the present study were to investigate a specific variant of MSX1 , derive morphometric tooth measurements in a sample of patients with isolated maxillary lateral incisor agenesis and matched controls, and model the findings. (2) Methods: Genotyping of the MSX1 rs8670 genetic variant and morphometric measurements with a 2D image analysis method were performed for 26 hypodontia patients and 26 matched controls. (3) Results: The risk of upper lateral incisor agenesis was 6.9 times higher when the T allele was present. The morphometric parameters showed significant differences between hypodontia patients and controls and between the unilateral and bilateral agenesis cases. The most affected crown dimension in the hypodontia patients was the bucco-lingual dimension. In crown shape there was significant variation the Carabelli trait in upper first molars. (4) Conclusions: The MSX1 rs8670 variant was associated with variations in morphological outcomes. The new findings for compensatory interactions between the maxillary incisors indicate that epigenetic and environmental factors interact with this genetic variant. A single-level directional complex interactive network model incorporates the variations seen in this study.

Introduction: Congenital absence of teeth is one of the most prevalent craniofacial malformation and dental disorder. Hypodontia may present with varying degrees of severity. The absence of all teeth (anodontia) is rare. Based on epidemiological studies, it is more common in the permanent dentition, then in deciduous teeth. Objective: The aim of the present study was to compare the dento-alveolar changes, on panoramic radiographs, between patients with hypodontia from the case group and subjects without tooth agenesis from the control group. Method: Measurements were performed on panoramic radiographs. The results were compared between the patients with hypodontia and the subjects from the control group. Dento-alveolar linear and angular measurements were performed. The mean age of the 60 subjects was 14.15 ± 4.48 years, to which a control group was assigned with a mean age 13.98 ± 4.07 years. 70% of the study population were female and 30% were male. Results: We found statistically significant differences between the case group and the control group in the case of transverse measurements and unilateral linear measurements (p<0.01). Conclusion: Hypodontia will affect the transversal development of mandibular dento-alveolar structures, and will cause the decrease of gonial angle.

The etiology of hypodontia is complex, in which both genetic and environmental factors can be related. The main objective of our study was to contribute to elucidating the genetic background of nonsyndromic hypodontia (NSH). In this order, we selected 97 NSH subjects (70 females and 27 males) from patients referred to orthodontic treatment, and we matched to each NSH subject a control by age and sex. DNA was obtained from epithelial cells from the oral mucosa. Genotyping of the PAX9 (rs4904155 and rs61754301), MSX1 (rs8670 and rs12532), and AXIN2 (rs2240308) SNPs was performed by using TaqMan SNP Genotyping Assays on a real-time PCR system. Single-nucleotide polymorphisms (SNPs) were studied for the whole NSH group and for frontal and lateral agenesis NSH subjects separately. Our results showed that the variant genotype ( p =0.0008, OR = 2.9, 95% CI = 1.58-5.3) and variant T allele ( p =0.0002, OR = 2.65, 95% CI = 1.6-4.39) of the MSX1 rs8670 SNP increased the risk of hypodontia in the studied population when the whole NSH group was compared with controls. The variant genotype of the MSX1 rs8670 SNP was the most frequent in frontal agenesis; meanwhile in the lateral agenesis NSH group, the AXIN2 rs2240308 SNP showed a higher frequency of the variant genotype, with a trend towards statistical significance. In conclusion, the results of the present study showed that the variant genotype and variant T allele of the MSX1 rs8670 SNP increased the risk of hypodontia in the studied population. The presence of the variant A allele of AXIN2 rs2240308 is associated with frontal agenesis but not with lateral agenesis., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2019 Krisztina Mártha et al.)

Introduction: The incidence of congenital hypodontia is increasing in daily practice. Early diagnosis of this dental disorder and the associated skeletal malocclusions is crucial for successful and stable final rehabilitation., Aim: Comparison of cephalometric findings of patients with hypodontia of 1-4 teeth with the measurement results of the control group without teeth agenesis., Material and Method: We evaluated the lateral X-ray of 41 patients with 1-4 teeth agenesis selected from patients referred for orthodontic treatment to the Orthodontic Department of the University of Medicine and Pharmacy from Târgu Mureş within a two-year period. The results were compared with the values of the age and sex matched control group., Results: Bilateral upper incisor and lower bicuspid were missing in most of the hypodontia cases. When looking at the NSGn angle predicting the growth direction of the mandible, statistically significant differences were found between the male (p = 0.012), the front (p = 0.010) and the hypodontia group (p = 0.024) and the control group. Regarding the ANB angle, which shows the sagittal position of the maxilla to the mandible, statistically significant differences were found between the subgroups (women, men, anterior or posterior hypodontia) and the control group., Conclusion: Larger number of skeletal class 3 and vertical hypodivergent tendency were observed in the hypodontia group. Orv Hetil. 2019; 160(6): 214-219.

Objective: The associations seen clinically between variations in tooth number, size and shape reflect the repetitive genetic interactions occurring between the epithelium and mesenchyme during the initiation and morphogenetic stages of the Complex Adaptive System that is dental development. The aim of this study was to investigate the clinical relationship further by comparing multiple crown parameters, including cusp numbers, between patients with mild hypodontia and controls in a Romanian sample., Design: Digital images of dental casts of the permanent dentition from 28 patients with mild hypodontia and 28 controls were used. Measurements from the vestibular and occlusal surfaces were performed using a 2D image analysis method and cusps, including the Carabelli trait, were counted. Two-way analysis of variance was performed., Results: The dimensions of the mild hypodontia group had smaller values than the controls, with many measurements being significantly different (significance values varied from p=0.049 to p=0.001). The most affected regions were the upper and lower anterior region in both sexes. Mesio-distal, bucco-lingual and occlusal area and perimeter dimensions were affected. Females from the hypodontia group had significantly less tricuspidated lower premolars when compared with the control group. Carabelli cusps were present in the hypodontia group less frequently, the difference being highly significant (p=0.0002) in women., Conclusions: The hypodontia patients presented with reduced crown dimensions and shape compared with controls. This is the first published study to demonstrate smaller cusp numbers in patients with hypodontia than in controls. The findings are compatible with a model of dental development as a Complex Adaptive System incorporating associations between tooth number, size and shape., (Copyright © 2015 Elsevier Ltd. All rights reserved.)