Human permanent tooth sizes are associated with genes encoding oestrogen receptors

Frequency and variability of nonmetric dental crown traits of primary and permanent molars in a group of orthodontic patients

BACKGROUND

The present study aimed to assess the frequency and variation of 13 nonmetric dental crown traits (NDCT) in permanent and primary molars in German orthodontic patients.

METHODS

Dental records from orthodontic patients were screened and evaluated. First and second permanent and primary upper and lower molars (from left and right sides) were assessed. Teeth with cavitated dental caries, occlusal wear, restorations and obvious dental deformities were not evaluated. The NDCT for permanent molars were identified and scored according to the odontoscopic system developed by Arizona State University Dental Anthropology System (ASUDAS). The NDCT for primary molars were identified and scored according to ASUDAS, Hanihara's method and Sciulli's method. The χ2 test was used to investigate side preference and sexual dimorphism at a significance level of p ≤ 0.050.

RESULTS

A total of 163 orthodontic patients (82 males and 81 females) aged 8-14 years were included. A sexual dimorphism was observed for the hypocone in first upper permanent molar (p = 0.041). The protostylid was observed in lower permanent molars (range 2.1-10%). Males presented more hypoconulid than females (p = 0.019). Only females presented the distal trigonid crest in lower first permanent molars (p = 0.002). The most common groove pattern in primary molars was Y; male presented more Y grade than females in the lower second primary molar (p = 0.039). Asymmetry was observed in some traits, ranging from 0 to 100%.

CONCLUSION

The present study showed the frequency of NDCT of molars in German orthodontic patients and demonstrated that some traits present sexual dimorphism.

Mandibular and dental measurements for sex determination using machine learning

The present study tested the combination of mandibular and dental dimensions for sex determination using machine learning. Lateral cephalograms and dental casts were used to obtain mandibular and mesio-distal permanent teeth dimensions, respectively. Univariate statistics was used for variables selection for the supervised machine learning model (alpha = 0.05). The following algorithms were trained: logistic regression, gradient boosting classifier, k-nearest neighbors, support vector machine, multilayer perceptron classifier, decision tree, and random forest classifier. A threefold cross-validation approach was adopted to validate each model. The areas under the curve (AUC) were computed, and ROC curves were constructed. Three mandibular-related measurements and eight dental size-related dimensions were used to train the machine learning models using data from 108 individuals. The mandibular ramus height and the lower first molar mesio-distal size exhibited the greatest predictive capability in most of the evaluated models. The accuracy of the models varied from 0.64 to 0.74 in the cross-validation stage, and from 0.58 to 0.79 when testing the data. The logistic regression model exhibited the highest performance (AUC = 0.84). Despite the limitations of this study, the results seem to show that the integration of mandibular and dental dimensions for sex prediction would be a promising approach, emphasizing the potential of machine learning techniques as valuable tools for this purpose.

Polymorphisms in hormonal-related genes might be associated with variations in permanent tooth crown size

BACKGROUND

The variability in tooth crown size (TCS) is influenced by genetic factors and might be regulated by the difference in hormonal response.

MATERIALS AND METHODS

This study aimed to evaluate the association between variations in TCS of permanent teeth with associated factors and genetic polymorphisms in hormonal-related genes (ESR1, ESR2 and PTH). This cross-sectional study involved dental casts from 86 individuals of both sexes. Dental casts were used to determine the maximum TCS of all fully erupted permanent teeth (except third molars) in the mesiodistal (MD) and buccolingual (BL) dimensions. Data such as sex, ethnicity, dental group (incisor, canine, premolar and molar), dental arch (upper and lower) and genetic polymorphisms of hormonal-related genes were used. The DNA from each patient was collected to evaluate the genetic polymorphisms in ESR1 (rs2234693 and rs9340799), ESR2 (rs1256049 and rs4986938) and PTH (rs694, rs6256 and rs307247) through real-time PCR. The data were submitted to statistical analysis with a significance level of 0.05.

RESULTS

In the MD dimension, the sex, dental group and dental arch were associated with variation in TCS (P < .05). In the BL dimension, the sex, dental group, dental arch and polymorphism in rs694 and rs307247 were associated with variation in TCS.

CONCLUSIONS

In short, this study suggests that genetic polymorphisms of PTH are associated with variations in the BL TCS of permanent human teeth.

Investigating the association between dental age and polymorphisms in genes encoding estrogen receptors

BACKGROUND

Genetic polymorphisms have been shown to influence several physiological traits, including dental and craniofacial characteristics. Understanding the clinical relevance of genetic polymorphisms in dental practice is crucial to personalize treatment plans and improve treatment outcomes.

OBJECTIVE

to evaluate the association between dental age and genetic polymorphisms in genes encoding estrogen receptors alpha and beta (ESR1 and ESR2, respectively) in a sample of Brazilian children.

METHODOLOGY

This retrospective cross-sectional study was performed with children undergoing orthodontic treatment. Patients with syndromes, congenital anomalies, craniofacial deformities, under hormonal or systemic treatment, and with a previous history of facial trauma were excluded. Panoramic radiographs were used to assess dental age according to the Demirjian, Goldstein, and Tanner method. A delta [dental age-chronological age (DA-CA)] was obtained, which shows whether the patient tends to have a normal, delayed (negative values), or advanced (positive values) dental age. DNA isolated from buccal cells was used to genotype four genetic polymorphisms: rs9340799 (A>G) and rs2234693 (C>T), located in ESR1; and rs1256049 (C>T) and rs4986938 (C>T), located in ESR2. A statistical analysis was performed and values of p<0.05 indicated statistical difference.

RESULTS

A total of 79 patients were included, 44 (55.70%) girls and 35 (44.30%) boys. The Demirjian, Goldstein, and Tanner method, in general, overestimated patients' age by 0.75 years. There was no difference in the delta of dental age between the sexes (p>0.05). Genetic polymorphisms in ESR1 and ESR2 were not associated with dental age (p>0.05).

CONCLUSION

The studied genetic polymorphisms in ESR1 and ESR2 were not associated with dental age in Brazilian children.

Prevalence of malocclusions under conditions of prolonged introduction of systemic fluorides in variable concentrations: Literature review

The pathogenesis of malocclusions, which are common among the population of  all  countries, is  well represented in the professional literature. The occurrence of  malocclusions is associated with genetic and various environmental factors. Among the latter, fluorides which affect the prevalence of some dental diseases are of particular interest. However, there are few publications reflecting the frequency of malocclusion among the population in the regions with different levels of fluoride in drinking water. This problem seems to be significant in the context of the increasing impact of fluorine compounds on human health, including dental health.

The aim of the study. To analyze the literature on the frequency of malocclusion among the population living in conditions of variable fluoride content in drinking water. A manual search of domestic and foreign literature was performed in the search databases PubMed, Medline and Google Scholar. From the initial list of publications, eighteen articles that met the inclusion criteria for the study were selected for analysis. We revealed significant variability of the research results. Some authors note a higher prevalence of malocclusions among the population under conditions of increased fluoride intake, others note a lower one, and still others did not reveal any differences between the values obtained in both samples. Most of the assessed publications did not methodologically meet modern international standards, and therefore were of little evidence.

The literature data do not provide grounds for an unambiguous assessment of fluorine compounds as an environmental factor that indirectly affects the process of occlusion formation in humans and animals.

The review did not allow to make a definitive conclusion on the possible impact of  systemic fluorides on the prevalence and pattern of malocclusion in humans and animals. It requires the implementation of studies that comply with the principles of evidence-based medicine. 

Odontogenesis-related candidate genes involved in variations of permanent teeth size

OBJECTIVE

The aim of the study was to evaluate the association between genetic polymorphisms in RUNX2, BMP4, BMP2, TGFβ1, EGF, and SMAD6 and variations in permanent tooth size (TS).

MATERIALS AND METHODS

This cross-sectional study evaluated 110 individuals' dental casts to determine the maximum tooth crown size of all fully erupted permanent teeth (third molars were excluded) in the mesiodistal (MD) and buccolingual (BL) dimensions. Genomic DNA was obtained from the epithelial cells of the oral mucosa to evaluate the genetic polymorphisms in RUNX2 (rs59983488 and rs1200425), BMP4 (rs17563), BMP2 (rs235768 and rs1005464), TGFβ1 (rs1800470), EGF (rs4444903), and SMAD6 (rs2119261 and rs3934908) through real-time PCR. The data were submitted to statistical analysis with a significance level of 0.05.

RESULTS

The genetic polymorphisms rs59983488, rs1200425, rs17563, rs235768, rs1005464, rs1800470, and rs4444903 were associated with MD and BL TS of the upper and lower arches (p < 0.05). The polymorphism rs2119261 was associated with variation in TS only in the upper arch (p < 0.05). The rs3934908 was not associated with any TS measurement (p > 0.05).

CONCLUSIONS

In summary, this study reports novel associations between variation in permanent TS and genetic polymorphisms in RUNX2, BMP4, BMP2, TGFβ1, EGF, and SMAD6 indicating a possible role of these genes in dental morphology.

CLINICAL RELEVANCE

Polymorphisms in odontogenesis-related genes may be involved in dental morphology enabling a prediction of permanent TS variability. The knowledge regarding genes involved in TS might impact the personalized dental treatment, considering that patients' genetic profile would soon be introduced into clinical practice to improve patient management.