The genetic control of early odontogenesis

Impact of genetic variations in the WNT family members and RUNX2 on dental and skeletal maturation: a cross-sectional study

BACKGROUND

This study evaluated if genetic variations in the WNT family members and RUNX2 are associated with craniofacial maturation, investigating dental and skeletal maturity in children and teenagers.

METHODS

Radiographs from pre-orthodontic treatment of Brazilian patients (7 to 17 years-old) were used to assess dental (panoramic radiographs) and skeletal maturity (cephalometric radiographs). The chronological age (CA) was calculated based on the date of birth and the time the radiographs were performed. For the dental maturity analysis, the Demirjian (1973) method was used and a delta [dental age - chronological age (DA-CA)] was calculated. For the skeletal maturity analysis, the Baccetti et al. (2005) method was used and the patients were classified as "delayed skeletal maturation", "advanced skeletal maturation" or "normal skeletal maturation". DNA isolated from buccal cells was used for genotyping of two genetic variations in WNT family genes: rs708111 (G > A) in WNT3A and rs1533767 (G > A) in WNT11; and two genetic variations in RUNX2: rs1200425 (G > A) and rs59983488 (G > T). A statistical analysis was performed and values of p < 0.05 indicated a significant difference.

RESULTS

There were no associations between dental maturity and genotypes (p > 0.05). In the skeletal maturity analysis, the allele A in the rs708111 (WNT3A) was statistically more frequent in patients with delayed skeletal maturation (Prevalence Ratio = 1.6; 95% Confidence Interval = 1.00 to 2.54; p-value = 0.042).

CONCLUSIONS

The rs708111 in the WNT3A gene impacts on skeletal maturation.

Family and case–control genetic study of MSX1 polymorphisms in peg-shaped teeth Jordanian population

Background

This study aimed to investigate the genetic association of specific Single Nucleotide Polymorphisms (SNPs) within the muscle segment homeobox gene 1 (MSX1) with susceptibility to the peg-shaped teeth in 36 Jordanian Arab families and case–control samples in the Jordanian Arab population.

Methods

This cohort involved 108 individuals (36 trios families), which were used for family-based genetic study. Additionally, 56 patients and 57 controls were used for case–control study. Genomic DNA samples from both families and case–control were extracted according to distinguished processes. Then, polymerase chain reaction technique (PCR) was conducted using specific primers for the axons of the MSX1. Moreover, DNA sequencing genotyping method analysis of SNPs was used to detect specified SNPs in the MSX1 linked with peg-shaped teeth. Hardy–Weinberg Equilibrium and Chi-square were used to evaluate the data quality and the presence of any genotypic error. In addition, Transmission Disequilibrium Test (TDT) was used identify family-based association in which trios of parents and proband are used.

Results

The results of this study showed fourteen polymorphic sites in this gene, eight of them (rs121913129, rs104893852, rs104893853, rs121913130, rs104893850, rs1095, rs3775261, and rs1042484) were none-polymorphic. Meanwhile, the minor allele frequencies of the rest of the SNPs were polymorphic (rs8670, rs12532, rs3821949, rs4464513, rs1907998, and rs6446693). However, none of these SNPs were associated with peg-shaped teeth. Moreover, the haplotype genetic analysis revealed that there was no genetic association with peg-shaped teeth disorder susceptibility (P > 0.05) in the Jordanian families of Arab descent.

Conclusions

The present findings can be used in estimation of prevalence of peg-shaped teeth in the Jordanian population. However, our findings revealed that there is no evidence that the MSX1 polymorphisms had a crucial role in the peg-shaped teeth phenomenon, emphasizing that other genes might have this role. These findings are beneficial for clinicians to comprehensively understand the molecular aspects of teeth abnormalities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02051-2.

Histology of Tooth Development in 3D Animation Video and Images - A Preliminary Report

The process of tooth development is both, fascinating and well-described aspect of embryology. Although a big deal of the dental literature is being focused to the understanding of early stages of tooth development, still huge gap exist in our knowledge on how the dental hard tissues are formed, based on available images and descriptions. Tooth development process takes place in 3D form, inside our body. Therefore, histology should also be additionally explained with the help of additional 3D images and a video, which have not been reported so far. Methodology: Therefore, this brief article is a technical note and preliminary attempt to showcase 3D animation images and video of stages of tooth development which have been designed by the author herself using various the 3D animation softwares such as 3D max (Autodesk Media and Entertainment, San Rafael, California) and Adobe Premiere Pro 5.5 software which is a video-editing software (Adobe Systems, San Rafael, California).

Study of Dental Caries and PTH Gene

Parathyroid hormone (PTH) is essential for calcium and phosphate homeostasis in odontogenesis-related cells. Therefore, the present study aimed to investigate the association between single nucleotide polymorphisms in the gene encoding PTH, and dental caries in Brazilian children. Three hundred and fifty-three children (170 boys and 183 girls, age ranging from 8 to 11 years old) were included in this study. The International System for Detection and Assessment of Carious Lesions (ICDAS) was used for diagnosis of dental caries. Visible biofilm was also evaluated during the clinical examination. Genomic DNA was extracted from saliva for real-time PCR to evaluate the single nucleotide polymorphisms rs6256, rs307247 and rs694 in PTH gene. Dental caries was classified in ICDAS0 vs. ICDAS1−6 or ICDAS1−2 vs. ICDAS3−6. Chi-square test, binary logistic regression adjusted by biofilm and haplotype analyses were performed (p &lt; 0.05). Biofilm was associated with dental caries (p &lt; 0.05). There were no associations between dental caries and rs6256, rs307247, rs694 in none of the analyses performed (p &gt; 0.05). In conclusion, the present study supports that the single nucleotide polymorphisms rs6256, rs307247, and rs694 in the PTH-encoding gene are not associated with dental caries in Brazilian children.

Association between Tooth Agenesis and Skeletal Malocclusions

Objectives

The aim of this study was to evaluate the association between tooth agenesis and skeletal malocclusions in Brazilian non-syndromic orthodontic patients.

Material and Methods

Pretreatment orthodontic records of 348 patients of both genders and with various skeletal malocclusions were examined. Tooth agenesis was evaluated in panoramic radiographs. Angular measurements were taken from lateral cephalometric radiographs to classify the patient’s malocclusion as skeletal Class I, Class II and Class III. Subjects were divided into 2 groups, “with tooth agenesis” and “without tooth agenesis”. Chi-square or Fisher exact test was used to compare categorical data. ANOVA with Tukey’s post-test was used for means comparisons. An alpha of 5% was established.

Results

From 348 analysed patients, 28 presented tooth agenesis. There was no difference between genders (P = 0.27) nor mean age (P = 0.16). The most prevalent skeletal malocclusion was Class I (63.11%), followed by Class II (25.94%), and Class III (10.95%). The mean of congenitally missing teeth was 1.3 (SD 0.13). Thirteen subjects had premolar agenesis, 13 upper lateral incisor agenesis, 4 lower incisor agenesis and 2 molars agenesis. The group with tooth agenesis presented A point-nasion-B point (ANB) angle smaller (1.66 [SD 2.52]) than the group without tooth agenesis (2.86 [SD 2.49]) (P = 0.01). ANB angle had a negative correlation with the number of congenitally missing teeth (P = 0.039; r = -0.39).

Conclusions

Tooth agenesis is associated with a smaller A point-nasion-B point angle and is negatively correlated with the number of congenitally missing teeth.

Developmental Structural Tooth Defects in Dogs - Experience From Veterinary Dental Referral Practice and Review of the Literature

Developmental tooth abnormalities in dogs are uncommon in general veterinary practice but understanding thereof is important for optimal management in order to maintain masticatory function through preservation of the dentition. The purpose of this review is to discuss clinical abnormalities of the enamel and general anatomy of dog teeth encountered in veterinary dental referral practice and described in the literature. More than 900 referral cases are seen annually between the two referral practices. The basis of the pathogenesis, resultant clinical appearance, and the principles of management for each anomaly will be described. Future research should be aimed toward a more detailed analysis of these conditions so rarely described in the literature.

Single rooted primary first molar with nonsyndromic hypodontia: A rare case report

Dental anomalies of number, shape and size are the most common to dental literature, the most common being the agenesis and morphologic dental anomalies. However, very few cases have been reported regarding the presence of single root in primary molars. The purpose of this article was to present a rare case of single root in primary mandibular first molar associated with nonsyndromic hypodontia.

Morphometric, densitometric and mechanical properties of mandibular deciduous teeth in 5-month-old Polish Merino sheep

Background

Caries, enamel hypoplasia, molar incisor hipomineralization, amylogenesis imperfecta, dentine dysplasia, hypophosphatasia and other dental disorders lead to tooth mineralization disturbances and structural abnormalities, decreasing masticatory organ functions. Dental disorders in sheep can lead to premature slaughter before they have attained final stage of their reproductive life and induce economic loss due to high flock replacement costs. Growth rate, health status and meat quality of sheep depends on tooth properties and quality determining in large extent efficiency of the masticatory apparatus and initial food break up. Considering lack of basic anatomical and physiological data on teeth properties in sheep, the aim of the study was to evaluate morphometric, densitometric and mechanical traits of deciduous mandibular incisor, canine and the second premolar obtained at the slaughter age of 5 months of life.

Results

The obtained results have shown the highest values of weight, total tooth volume, enamel volume and dentine volume in second premolar. Morphometric and mechanical parameters of incisors reached the highest values in first incisor and decreased gradually in second and third incisor, and in canine. Densitometric measurements have not revealed significant differences of the volumetric tooth mineral density in hard dental tissues between the investigated teeth.

Conclusions

In conclusion, proposed methodological approach is noninvasive since the deciduous teeth undergo physiological replacement with permanent teeth. Deciduous teeth can be easy collected for analyses from large animal population and may reflect mineral status and metabolism resulting from postnatal growth and development of the whole flock. In individual cases, evaluation of properties of deciduous teeth may serve for breeding selection and further reproduction of sheep possessing favorable traits of teeth and better masticatory system functions.

The genetic basis of dental anomalies and its relation to orthodontics

The interruption of odontogenesis by any etiological factor may result in dental anomalies. Apart from the environmental factors, the impact of genetics in dental anomalies was found to be a factor in different levels. Many authors had questioned a common genetic defect resulting in different phenotypic conditions such as absent, malformed, malposed or ectopic teeth. Because the multidisciplinary treatment of these dental anomalies such as hypodontia, impaction etc., involves orthodontic intervention, orthodontists must be aware of the etiology and possible correlative conditions with dental anomalies.

The orthodontic-restorative interface in patients with hypodontia: the patient's journey

Congenitally absent teeth may pose aesthetic and functional problems for patients. Treatment is often complex and involves a multidisciplinary team. Using retrospective data, the patient's pathway, when a combined orthodontic-restorative dentistry approach was used, will be summarized. It was found that the number of teeth missing ranged from 1 to 8 with a mean of 3.4 per patient. Combined treatment was found to take on average around 38 months, using over 20 appointments.

CLINICAL RELEVANCE

Hypodontia is a relatively common condition. It is important that practitioners and patients are aware of the length of time treatment can take.

Interrelationships between tooth properties and biochemical bone turnover markers investigated on six-month-old pig model

The aim of the study was to determine interrelationships between bone tissue metabolism indices and morphological, biomechanical and densitometric properties of hard dental tissues. First primary maxillary incisor from 6-month-old pigs (N=27) was evaluated in terms of weight and length. Mean volumetric tooth mineral density, total tooth volume, enamel total volume, enamel volumetric mineral density, dentine total volume and dentine volumetric mineral density were estimated with the use of quantitative computed tomography and micro computed tomography techniques. Tooth mineral density and tooth mineral content were evaluated with the use of dual-energy X-ray absorptiometry. Microhardness of enamel was measured using Vicker's test. Evaluations of total calcium, ionized calcium, magnesium, phosphorus, alkaline phosphatase, bone alkaline phosphatase, osteocalcin, C-terminal telopeptide of type-I collagen (CTX), insulin-like growth factor-1, growth hormone and parathyroid hormone were performed in plasma and serum samples. Pearson's correlation coefficients were determined between all the investigated variables, and P<0.05 was considered as statistically significant. The obtained results have shown mainly mutual dependences between biochemical indicators of bone metabolism. Evaluation of CTX concentration in serum of pigs has shown the highest predictive value in relation to morphological, densitometric and biomechanical properties of teeth.

EMMPRIN (basigin/CD147) is involved in the morphogenesis of tooth germ in mouse molars

The pattern of gene expression for extracellular matrix metalloproteinase inducer (EMMPRIN) was revealed in the tooth germ of mouse mandibular molars using quantitative real-time PCR. In situ hybridization and immunohistochemical study demonstrated the characteristic distribution of EMMPRIN in the different stages of tooth germ development. To investigate the functional role played by EMMPRIN in tooth germ development, EMMPRIN siRNA interference approach was carried out in cultured mouse mandibles at embryonic day 11.0 (E11.0). The results showed that EMMPRIN siRNA-treated explants exhibited a marked growth inhibition of tooth germ compared to the control and scrambled siRNA-treated explants. Meanwhile, a significant increase in MT1-MMP mRNA expression and a reduction in MMP-2, MMP-3, MMP-9, MMP-13 and MT2-MMP mRNA expression were observed in the mouse mandibles following EMMPRIN abrogation. The current results indicate that EMMPRIN could thus be involved in the early stage of tooth germ development and morphogenesis, possibly by regulating the expression of MMP genes.

Revisiting the supernumerary: the epidemiological and molecular basis of extra teeth

Supernumerary teeth are a common clinical and radiographic finding and may produce occlusal and dental problems. The aetiological basis of extra teeth is poorly understood in human populations; however, the mouse provides a useful model system to investigate the complex genetics of tooth development. This article describes recent advances in our understanding of the genetic basis of supernumerary teeth. We have reviewed biological evidence that provides insight into why supernumerary tooth formation may occur. Indeed, many of the molecular signalling pathways known to be involved in normal development of the tooth germ can also give rise to additional teeth if inappropriately regulated. These include components of the Hedgehog, FGF, Wnt, TNF and BMP families, which provide a useful resource of candidate genes that may potentially play a role in human supernumerary tooth formation.

Investigation of proliferative activity in the developing human tooth using Ki-67 immunostaining

OBJECTIVE

The aim of this study was to investigate the proliferation of the developing human tooth germ and its surrounding tissues using Ki-67 immunostaining.

MATERIALS AND METHODS

Sections of mandibular dental arch tissues collected from 4 cadaveric human fetuses of 13, 16, 21 and 30 weeks of gestation were used. The immunoreactivity of Ki-67 in the tissue sections was assessed visually under a light microscope. Immunohistochemical controls were performed by replacing the primary antibody with phosphate-buffered saline or normal rabbit lgG.

RESULTS

The control sections did not display Ki-67 immunoactivity. Specimens of 13 weeks of gestation revealed intense Ki-67 immunostaining throughout the entire developing mandibular primary molars. At 16 weeks of gestation, immunostaining was observed in the inner enamel epithelium and dental papilla, in conjunction with the dental lamina showing decreased immunostaining. At 21 weeks, Ki-67 immunostaining was observed only in the inner enamel epithelium and dental papilla. The immunoreactivity of active ameloblasts and odontoblasts decreased, along with the proliferation capacity of the dental lamina. At 30 weeks, both enamel and dentin formation was observed along the cusped aspect of the tooth germ. Ameloblasts and odontoblasts were no longer immunoreactive in this region, while both types of cells were immunoreactive at the cervical regions of the crown. Dental lamina cells showed disintegration and were totally Ki-67-negative at 30 weeks of gestation.

CONCLUSION

The Ki-67 immunoreactivity of the dental lamina decreased during intrauterine tooth development. Positive immunostaining was observed at specific sites in the enamel organ and dental papilla during the cap and bell stages.

Mouse tooth development time sequence determination for the ICR/Jcl strain

To establish the normal dental development pattern of the ICR/Jcl strain of mouse, we analyzed a significant number of observations of the different developmental stages of the first mandibular molar, accurately recording the chronology of their daily embryonic development. Proliferation of the dental sheet began at day 12.5 in utero (E-12.5), the bud stage appeared at days E-13.5 and E-14.5, the cap stage was observed at days E-14.5, E-15.5 and E-16.5 and the early bell stage at day E-17.5. The presence of predentin was observed at day E-18.5 and dentin was observed 1 and 2 days after birth (D-1 and D-2). The late bell stage with presence of enamel was detected more than 3 days after birth. Embryonic and dental development in the ICR/Jcl strain of mouse is faster than in other well-known strains. The establishment of this developmental pattern will be useful for future investigations of transgenic mice.