Subphenotypes in Non-Syndromic Orofacial Cleft Patients Based on the Tooth Agenesis Code (TAC)

Prevalence of tooth agenesis and supernumerary teeth related to different Thai cleft lip and cleft palate populations

BACKGROUND

Pattern of dental anomalies encountered in cleft patients shows subtle signs of genetic involvement. This study aimed to evaluate the prevalence and pattern of tooth agenesis and supernumerary teeth in Thai cleft population according to the cleft type.

METHODS

Data collected from patients with cleft lip and palate, who had been treated at Tawanchai Cleft Center, Khon Kaen University, Thailand, available during year 2012-2022, were investigated. Records from 194 patients with non-syndromic clefts met the inclusion criteria. Standard dental records, and at least either orthopantomogram (OPG) or cone beam computed tomography (CBCT), were examined. Statistical analysis was performed using chi-square and binominal test (p ≤ 0.05).

RESULTS

Prevalence of tooth agenesis was higher (77.3%) than that of supernumerary teeth (5.7%) and was more common in bilateral cleft lip and palate (BCLP) (88.1%) than in unilateral cleft lip and palate (UCLP) (72.6%) (p = 0.017). The upper lateral incisor was more frequently affected (46.4%), followed by the upper second premolar. The number of missing teeth observed on the left side was significantly higher. Patients with left UCLP (ULCLP) had the highest prevalence of tooth agenesis. A total of 41 tooth agenesis code (TAC) patterns was found. The prevalence of supernumerary teeth was comparable with 6.6% of ULCLP, 5.1% of BCLP, and 4.5% of URCLP. Tooth-number anomalies were observed more often in the BCLP and were most likely to occur on the left side of the maxilla. Both types of anomalies could be featured in a small proportion of cleft patients.

CONCLUSIONS

More than half of the patients with non-syndromic cleft lip and palate in this study, presented with tooth-number anomalies. Tooth agenesis was approximately 10-time more prevalent than supernumerary teeth. Tooth agenesis was likely to appear on the left-side of the maxilla regardless of the laterality of the cleft.

Global Trends and Hotspots in Research on Tooth Agenesis: A 20-Year Bibliometric Analysis

Tooth agenesis, one of the most common developmental defects in humans, not only impairs oral function but can also lead to craniofacial deformities. Bibliometric analysis can reveal significant shifts in research and publishing trends within specific fields. This study aims to provide a comprehensive overview of the research hotspots in tooth agenesis and predict future trends through bibliometric analysis. We searched for English-language publications related to tooth agenesis from 2001 to 2021 on the Web of Science. The publications were limited to original and review articles, and bibliometric parameters such as publication year, country, institution, author, journal, citations, and keywords were extracted and analyzed using VOSviewer, Microsoft Excel 2010, and CiteSpace. A total of 2,287 papers were ultimately selected. The results show that the USA holds a leading position in the field of tooth agenesis research. A total of 9,803 authors participated in these studies, with Alexandre R Vieira from the USA being the most prolific and most cited author. This study indicates that multidisciplinary management has become the consensus first choice for treating dental agenesis. Gene mutations related to tooth agenesis continue to be a research hotspot attracting scholarly attention. Exploring the relationship between tooth agenesis and cancer may be a future research direction. These findings contribute to potential collaborations among experts in future research on the genetic causes of tooth agenesis and tumor development and to assist the scientific community by identifying research gaps in this field.

Characterization of SHH, SOX3, WNT3A and WNT9B Proteins in Human Non-Syndromic Cleft Lip and Palate Tissue

Orofacial clefts have been associated with specific cleft candidate genes which encode regulatory proteins required for orofacial region development. Cleft candidate genes encode proteins involved with the cleft morphopathogenesis process, but their exact interactions and roles are relatively unclear in human cleft tissue. This study evaluates the presence and correlations of Sonic Hedgehog (SHH), SRY-Box Transcription Factor 3 (SOX3), Wingless-type Family Member 3A (WNT3A) and 9B (WNT9B) protein containing cells in different cleft tissue. Non-syndromic cleft-affected tissue was subdivided into three groups-unilateral cleft lip (UCL) (n = 36), bilateral cleft lip (BCL) (n = 13), cleft palate (CP) (n = 26). Control tissue was obtained from five individuals. Immunohistochemistry was implemented. The semi-quantitative method was used. Non-parametric statistical methods were applied. A significant decrease in SHH was found in BCL and CP tissue. SOX3, WNT3A and WNT9B had a significant decrease in all clefts. Statistically significant correlations were found. The significant decrease in SHH could be associated with BCL and CP pathogenesis. SOX3, WNT3A and WNT9B could have morphopathogenetic involvement in UCL, BCL, and CP. Similar correlations imply the presence of similar pathogenetic mechanisms in different cleft variations.

Novel Candidate Genes for Non-Syndromic Tooth Agenesis Identified Using Targeted Next-Generation Sequencing

Non-syndromic tooth agenesis (ns-TA) is one of the most common dental anomalies characterized by the congenital absence of at least one permanent tooth (excluding third molars). Regarding the essential role of genetic factors in ns-TA aetiology, the present study aimed to identify novel pathogenic variants underlying hypodontia and oligodontia. In a group of 65 ns-TA patients and 127 healthy individuals from the genetically homogenous Polish population, the coding sequences of 423 candidate genes were screened using targeted next-generation sequencing. Pathogenic and likely pathogenic variants were identified in 37 (56.92%) patients, including eight nucleotide alternations of genes not previously implicated in ns-TA (CHD7, CREBBP, EVC, LEF1, ROR2, TBX22 and TP63). However, since only single variants were detected, future research is required to confirm and fully understand their role in the aetiology of ns-TA. Additionally, our results support the importance of already known ns-TA candidate genes (AXIN2, EDA, EDAR, IRF6, LAMA3, LRP6, MSX1, PAX9 and WNT10A) and provide additional evidence that ns-TA might be an oligogenic condition involving the cumulative effect of rare variants in two or more distinct genes.

Tooth Agenesis Patterns in Orofacial Clefting Using Tooth Agenesis Code: A Meta-Analysis

Individuals with orofacial clefting (OFC) have a higher prevalence of tooth agenesis (TA) overall. Neither the precise etiology of TA, nor whether TA occurs in patterns that differ by gender or cleft type is yet known. This meta-analysis aims to identify the spectrum of tooth agenesis patterns in subjects with non-syndromic OFC and controls using the Tooth Agenesis Code (TAC) program. An indexed search of databases (PubMed, EMBASE, and CINAHL) along with cross-referencing and hand searches were completed from May to June 2019 and re-run in February 2022. Additionally, unpublished TAC data from 914 individuals with OFC and 932 controls were included. TAC pattern frequencies per study were analyzed using a random effects meta-analysis model. A thorough review of 45 records retrieved resulted in 4 articles meeting eligibility criteria, comprising 2182 subjects with OFC and 3171 controls. No TA (0.0.0.0) was seen in 51% of OFC cases and 97% of controls. TAC patterns 0.2.0.0, 2.0.0.0, and 2.2.0.0 indicating uni- or bi-lateral missing upper laterals, and 16.0.0.0 indicating missing upper right second premolar, were more common in subjects with OFC. Subjects with OFC have unique TA patterns and defining these patterns will help increase our understanding of the complex etiology underlying TA.