Growth and Development of Dentofacial Complex influenced by Genetic and Environmental Factors using Monozygotic Twins

Genetic Polymorphisms of Estrogen Receptors α and β are Associated with Craniofacial Measurements in Patients With Dentofacial Deformity

Dentofacial deformities are characterized by abnormalities in craniofacial development that affects the individual's skeletal and occlusion, often causing functional and esthetic problems. In literature, there is an involvement of polymorphisms in estrogen receptor 1 (ESR1) and estrogen receptor 2 (ESR2) genes in craniofacial measurements. The aim of this study was to evaluate a possible association between polymorphisms in ESR1 (rs2234693 and rs9340799) and ESR2 (rs1256049 and rs4986938) genes with cephalometric measurements in individuals with dentofacial deformities. This cross-sectional study was performed with 158 individuals in the preoperative period of orthognathic surgery. The cephalometric measurements obtained through lateral cephalogram using Dolphin Imaging software. For genetic analysis, the DNA extracted from epithelial cells of the oral mucosa and were genotyped using the real-time polymerase chain reaction. The data found submitted to statistical analysis, through the Kolmogorov-Smirnov, Mann-Whitney, and Kruskal-Wallis tests, using the IBM SPSS software version 24.0. Considered a significance level of 0.05. We found association between polymorphisms and cephalometric measurements just in the female sex. The polymorphisms ESR1/rs9340799 ( P= 0.003), ESR1/rs2234693 ( P= 0.026), and ESR2/rs1256049 ( P= 0.046) were associated with the upper gonial angle (Ar-Go-N). The polymorphism ESR2/rs1256049 was also associated with the facial axis-rickets (NBa-PtGn) ( P= 0.004), anterior cranial base (SN) ( P= 0.036), and Y-axis (SGn-SN) ( P= 0.031).

Longitudinal changes in the dental arch width and symmetry in identical and fraternal twins

INTRODUCTION

This study aimed to assess growth-related dental and symmetry changes in the dental arch within and between identical and fraternal twins in mixed and permanent dentition.

METHODS

Three-dimensional scanned dental models of eligible subjects were selected from the Forsyth-Moorrees Twin Study sample. This retrospective cohort study was carried out on 36 identical (18 pairs) and 28 fraternal (14 pairs) twins in mixed dentition and 36 identical (18 pairs) and 38 fraternal (19 pairs) twins in permanent dentition stages on the basis of the availability of the dental casts scanned each year from each group (Table I). Linear measurements from dental casts were performed in patients aged 8-16 years. Student t test and Pearson's correlation were used to compare the symmetry between and within the identical and fraternal twins. The resemblance and heritability patterns were retrospectively obtained from the Pearson correlation coefficient and Falconer's heritability test (H2 = 2 × b). Adjusted mixed-effects estimates and 95% confidence intervals were calculated to test the association between age and dental parameters for both mixed and permanent dentition groups.

RESULTS

Intercanine and intermolar widths significantly increased (P <0.05) during the mixed dentition but became stable after 13 years old. No statistically significant differences were found in arch symmetry between the 2 groups (ie, identical and fraternal) in any of the included measurements. Evaluation of the resemblance and heritability pattern showed nonsignificant results for all variables measured (H2 range, -0.67 to 0.56).

CONCLUSIONS

The dental arch becomes wider at a higher rate in the canine region than the molar region in both the mixed and early permanent dentition. The dental arches of twins develop symmetrically, and their growth is not mainly affected by genetics. Asymmetrical teeth will maintain their relative position to reference planes throughout growth.

Single nucleotide polymorphisms in runt-related transcription factor 2 and bone morphogenetic protein 2 impact on their maxillary and mandibular gene expression in different craniofacial patterns - A comparative study

Introduction:

This study aimed to evaluate if single nucleotide polymorphisms (SNPs) in runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein 2 (BMP2) are associated with different craniofacial patterns. Furthermore, we also investigated if RUNX2 and BMP2 expression in the maxilla and mandible are differently expressed according to facial phenotypes and influenced by the SNPs in their encoding genes. Orthognathic patients were included.

Materials and Methods:

Lateral cephalometric radiographs were used to classify facial phenotypes based on Steiner's ANB and Ricketts’ NBa-PtGn angles. Bone samples from 21 patients collected during orthognathic surgery were used for the gene expression assays. DNA from 129 patients was used for genotyping the SNPs rs59983488 and rs1200425 in RUNX2 and rs235768 and rs1005464 in BMP2. The established alpha was 5%.

Results:

A statistically significant difference was observed in the relative BMP2 expression in the mandible between Class I and III participants (P = 0.042). Homozygous GG (rs59983488) had higher RUNX2 expression (P = 0.036) in the mandible. In maxilla, GG (rs1200425) had a higher BMP2 expression (P = 0.038).

Discussion:

In conclusion, BMP2 is expressed differently in the mandible of Class I and Class III participants. Genetic polymorphisms in RUNX2 and BMP2 are associated with their relative gene expression.

Second Class Functional Treatment: Andreasen Activator vs Twin Block

Aim

The purpose of this research is to analyze and compare the dental and skeletal changes induced by two functional devices, Andreasen Activator and Clark's twin block, on the sagittal and vertical plane, by means of cephalometric analysis, of the lateral cephalograms prescribed at the beginning and at the end of the treatment for a second skeletal class, first division with normal or deep bite.

Materials and methods

Twenty patients, 8 females and 12 males, fulfilling criteria for inclusion, were divided randomly into two groups: group I was treated with Andreasen activator, the second group with Clark's twin block. The duration of the therapy was about 18 months plus less 2 months. Pretreatment and posttreatment cephalometric radiographs were analyzed using angular (SNA, SNB, ANB, SnaSnp–GoGn angles), linear (Sna–Snp, Co–Gn, Co–Go, Go–Gn) skeletal parameters and dental one (U1–SnaSnp angle, L1–GoGn angle, Overjet and Overbite). To evaluate the posttreatment changes in the single groups and between them, paired and unpaired t-test was used.

Results

In both of the two groups analyzed, all the sagittal and vertical, angular and linear, skeletal measurements appear to be increased in a statistically significant way, except SNA angle and the distance Sna–Snp. Regarding the dental parameters, in the group treated with Andreasen activator, only Overjet and Overbite showed statistically significant differences. On the other hand, twin block induced statistical changes about Overjet, Overbite and also U1/SnaSnp, but not about L1/GoGn. The advancement of the mandible determines a greater prominence of the chin and lower lip, an increment of the labial mental angle and a reduction of the convexity of the profile. Also, the decrease of the overjet and, consequently, of the dental exposure improve the esthetic appearance of the patient's face.

Conclusion

Both functional treatments showed a lower jaw advanced on the sagittal plane and increased in size. In the upper jaw no significant changes were observed. It was also evident a dental compensation both on sagittal and vertical planes.

Clinical significance

The functional devices studied, Andreasen activator and twin block, seem to obtain more skeletal than dental results when the patients were treated at the peak of pubertal growth.

How to cite this article

Baccaglione G, Rota E, Ferrari M, et al. Second Class Functional Treatment: Andreasen Activator vs Twin Block. Int J Clin Pediatr Dent 2020;13(2):144–149.

Craniofacial Analysis May Indicate Co-Occurrence of Skeletal Malocclusions and Associated Risks in Development of Cleft Lip and Palate

Non-syndromic orofacial clefts encompass a range of morphological changes affecting the oral cavity and the craniofacial skeleton, of which the genetic and epigenetic etiologic factors remain largely unknown. The objective of this study is to explore the contribution of underlying dentofacial deformities (also known as skeletal malocclusions) in the craniofacial morphology of non-syndromic cleft lip and palate patients (nsCLP). For that purpose, geometric morphometric analysis was performed using full skull cone beam computed tomography (CBCT) images of patients with nsCLP (n = 30), normocephalic controls (n = 60), as well as to sex- and ethnicity- matched patients with an equivalent dentofacial deformity (n = 30). Our outcome measures were shape differences among the groups quantified via principal component analysis and associated principal component loadings, as well as mean shape differences quantified via a Procrustes distance among groups. According to our results, despite the shape differences among all three groups, the nsCLP group shares many morphological similarities in the maxilla and mandible with the dentofacial deformity group. Therefore, the dentoskeletal phenotype in nsCLP could be the result of the cleft and the coexisting dentofacial deformity and not simply the impact of the cleft.

Association between facial measurements and polymorphisms in human epidermal growth factor and transforming growth factor β1

The aim of the study was to evaluate the association between genetic polymorphisms in human epidermal growth factor (EGF) (rs4444903) and transforming growth factor β1 - (TGF-β1) (rs1800470) with facial measurements in patients with dentofacial deformities. A total of 144 adult patients with dentofacial deformities were included. Facial linear and angular measurements were traced in lateral cephalometric radiographs used Dolphin 2D software. Cells from oral mucosa were collected for DNA to be extracted. The polymorphisms were genotyped using real-time polymerase chain reaction (PCR). Probabilites of less than 0.05 were accepted as significant. The rs4444903 heterozygous patients had a decrease in the mandibular length (p=0.043) and the length of the mandibular base (p=0.008), and homozygous A patients also had a reduction in the length of the mandibular base (p=0.013) compared with homozygous G patients. Patients AG had an increase in measurement of the anterior facial height (p=0.032) and in ANS-Me distance (p=0.022) when compared with homozygous A. To the rs1800470, heterozygous patients had an increase in the length of the mandibular base (p=0.043) when compared with homozygous A. Heterozygous AG patients had an increase in angular measurements in TGF-β1 polymorphism for the upper gonial angle, when compared with the homozygous AA (p=0.032). Genetic polymorphisms in EGF and TGF-β1 are associated with facial measurements in a Brazilian population of patients with dentofacial deformities.