Hypodontia as a risk marker for epithelial ovarian cancer: a case-controlled study

Non-syndromic tooth agenesis in Latvian adolescent dental patients: a retrospective study with relevant literature review

AIM

To investigate the prevalence of tooth agenesis and associated dental anomalies in Latvian adolescent dental patients and compare it to other European countries.

DESIGN

Cross-sectional study of 2692 11-to-14-year-old patients (39.9% males and 60.1% females) attending Riga Stradins University Institute of Stomatology with panoramic radiographs taken between August 2020 and September 2021. Patients with any genetic syndromes were excluded. Data on tooth agenesis (excluding third molars) and other dental anomalies were recorded.

RESULTS

The prevalence of tooth agenesis in Latvian adolescent dental patients was 9.3% with no statistically significant difference between genders (χ2 test, p = 0.472). The most commonly missing teeth were mandibular second premolars, followed by upper lateral incisors and upper second premolars. There was a statistically significant association with the presence of other dental anomalies in tooth agenesis patients (p < 0.001).

CONCLUSIONS

This study found that the prevalence of non-syndromic tooth agenesis in Latvian adolescent dental patients was 9.3% with no statistically significant differences between the genders. Patients with tooth agenesis have a statistically significant possibility of the presence of other dental anomalies (p < 0.001).

"Examining the link between tooth agenesis and papillary thyroid cancer: is there a risk factor?" Observational study

BACKGROUND

Mutations in one or multiple genes can lead to hypodontia and its characteristic features. Numerous studies have shown a strong genetic influence on the occurrence of hypodontia, and identified several genes, including AXIN2, EDA, FGF3, FGFR2, FGFR10, WNT10A, MSX1, and PAX9, that are directly associated with dental agenesis and carcinogenesis. The objective of this study was to investigate the occurrence and pattern of tooth agenesis, microdontia, and palatally displaced canine (PDC) in women diagnosed with papillary thyroid cancer (PTC), compared to a control group of women without any malignancy or thyroid disease.

MATERIALS AND METHODS

This case-control study was carried at the Department of Orthodontics, School of Dental Medicine University of Zagreb, and Department of Oncology and Nuclear Medicine Sestre Milosrdnice University Hospital Centre. The study involved a clinical examination and evaluation of dental status, panoramic X-ray analysis, and assessment of medical and family history of 116 female patients aged 20-40 with PTC, as well as 424 females in the control group who were of similar age.

RESULTS

The prevalence of hypodontia, microdontia, and PDC was statistically higher in women with PTC than in the control group. The prevalence rate of hypodontia was 11.3% in the experimental group and 3.5% in the control group. The experimental group showed a higher occurrence of missing upper lateral incisors, lower left central incisors, and all the third molars (except the upper left) compared to the control group. Women with PTC showed the prevalence of PDC significantly higher than the control group (3.5%, 0.7%, p = 0.002). The probability of hypodontia as a clinical finding increases 2.6 times, and microdontia occurs 7.7 times more frequently in women with PTC.

CONCLUSION

Our study suggests a possible link between odontogenesis and PTC. The absence of permanent teeth may increase the likelihood of PTC in women. Leveraging the age-7 orthopantomogram to identify women at high risk for PTC within a critical early detection window could significantly improve oral health outcomes and PTC prognosis through proactive interventions.

Congenital Tooth Agenesis and Risk of Early-Onset Cancer

Importance

There is some evidence that tooth agenesis (congenital absence of 1 or more teeth) is associated with cancer risk, especially carcinomas of the colon and ovaries, but results of previous studies are conflicting, and associations have not yet been evaluated in a population-based setting.

Objective

To examine the association between tooth agenesis and specific cancer types before 40 years of age.

Design, Setting, and Participants

This population-based cohort study used linking data from nationwide registries in Denmark to assess all Danish live-born singletons born from January 1, 1977, to December 31, 2018, and followed up for up to 40 years. Data were analyzed from January through June 2023.

Exposure

Tooth agenesis as documented by the Danish Central Registry of Odontology (Danish municipal pediatric dental care) from January 1, 1988, to December 31, 2018, and from hospital encounters in the Danish National Patient Registry within the entire study period.

Main Outcome and Measures

The primary outcome was first cancer diagnosis before 40 years of age obtained from the Danish Cancer Registry. Associations between tooth agenesis and specific cancers were estimated by Cox proportional hazards regression as hazard ratios (HRs) with 95% CIs. Analyses were split into age groups: younger than 1 year, 1 to younger than 3 years, 3 to younger than 10 years, 10 to younger than 20 years, 20 to younger than 30 years, and 30 to younger than 40 years. Associations with nonsyndromic tooth agenesis were evaluated after exclusion of individuals with known syndromes.

Results

Among 2 501 715 included individuals (1 284 292 [51.3%] male), 70 288 (2.8%) had a diagnosis of tooth agenesis (mean [SD] age at diagnosis, 13.2 [4.1] years) and 26 308 (1.1%) had a diagnosis of early-onset cancer within the study period; 778 individuals had co-occurrence of tooth agenesis and cancer. Overall, tooth agenesis was positively associated with several cancer types, including neuroblastoma (age 1 to <3 years; HR, 4.20; 95% CI, 2.24-7.88), nephroblastoma (age 1 to <3 years; HR, 4.59; 95% CI, 2.37-8.91), hepatoblastoma (age 1 to <3 years; HR, 7.10; 95% CI, 2.70-18.68), osteosarcoma (age 10 to <20 years; HR, 2.19; 95% CI, 1.11-4.32), colorectal carcinomas (age 30 to <40 years; HR, 2.81; 95% CI, 1.38-5.71), and carcinomas of bladder (age 20 to <30 years; HR, 3.35; 95% CI, 1.35-8.30).

Conclusions and Relevance

This cohort study found associations between congenital tooth agenesis and several cancer types, from childhood to early adulthood. Further evaluation of these associations is needed to assess possible clinical implications.

Non-syndromic supernumerary teeth and association with a self-reported family history of cancer

BACKGROUND

Supernumerary teeth are an alteration of dental developmental and result in the formation of teeth above the usual number. Epidemiologic studies suggested that patients with dentofacial anomalies and their family members may present an increased risk of developing cancer, including female breast cancer and gynecologic cancers. These observations indicate that genetic alterations that result in dental anomalies may be related to cancer development. Thus, the aim of the present study was to evaluate the association between supernumerary teeth and a family history of female breast cancer and gynecologic cancers.

METHODS

The diagnosis of supernumerary teeth was based on clinical and radiographic examinations. For data collection, a questionnaire asking for information regarding ethnicity, age, gender, and self-reported family history of cancer up to the second generation was used. Statistical analysis was performed using the Χ2 test and Fisher's exact test with an established α of 5%.

RESULTS

A total of 344 patients were included; 47 of them had one or more non-syndromic supernumerary teeth (not associated with any syndrome or cleft lip and palate) and 297 were control patients. Age, ethnicity, and gender distribution were not statistically different between the group with supernumerary teeth and the control group (p > 0.05). The supernumerary teeth were most commonly observed in the incisors area. Breast cancer (n = 17) was the most commonly self-reported type of cancer, followed by uterine cervical (n = 10), endometrial (n = 2), and ovarian (n = 1) cancers. Endometrial cancer was significantly associated with the diagnosis of supernumerary teeth (p = 0.017).

CONCLUSION

This study suggests that patients with supernumerary teeth possess a higher risk of having family members with endometrial cancer.

The genetic basis of hypodontia in dental development

Dental agenesis is one of the most common developmental anomalies in humans, characterised by the developmental absence of one or more teeth. It can present as an isolated condition (non-syndromic hypodontia) or associated with a syndrome (syndromic hypodontia). This paper aims to review the genetic basis of hypodontia with reference to aetiology, classification and the subsequent clinical features.Significant progress has been made to identify the developmental basis of tooth formation, though there is still a lack of knowledge within the literature of the aetiological basis of inherited tooth loss.Gene anomalies or mutations in WNT10A, MSX1, PAX9, AXIN2 and EDA appear to be most critical during tooth development, leading to various forms of tooth agenesis.

Genetic Factors of Teeth Impaction: Polymorphic and Haplotype Variants of PAX9, MSX1, AXIN2, and IRF6 Genes

In recent research, there has been a growing awareness of the role of genetic factors in the positioning and eruption of teeth in the maxilla and mandible. This study aimed to evaluate the potential of specific polymorphic markers of single nucleotide polymorphisms (SNPs) located within the PAX9, MSX1, AXIN2, and IRF6 genes to determine the predisposition to tooth impaction. The study participants were divided into two groups: the first group consisted of individuals with at least one impacted secondary tooth. In contrast, the second group (control group) had no impacted teeth in their jaws. To analyze the genes, real-time PCR (polymerase chain reaction) and TaqMan probes were utilized to detect the selected polymorphisms. The findings suggest that disruptions in the structure and function of the mentioned genetic factors such as polymorphic and haplotype variants of PAX9, MSX1, AXIN2, and IRF6 genes, which play a direct role in tooth and periodontal tissue development, might be significant factors in tooth impaction in individuals with genetic variations. Therefore, it is reasonable to hypothesize that tooth impaction may be influenced, at least in part, by the presence of specific genetic markers, including different allelic variants of the PAX9, AXIN2, and IRF6 genes, and especially MSX1.

Non-syndromic hypodontia of maxillary lateral incisors and its association with other dental anomalies

BACKGROUND

Tooth agenesis (TA) is the developmental absence of one or more teeth and is the most common craniofacial disorder in humans. Maxillary lateral incisor agenesis (MLIA) is a specific subtype of TA and can have esthetic, functional, and psychosocial implications for patients. The aim of this study was to evaluate the prevalence of MLIA amongst patients with non-syndromic tooth agenesis, as well as its association with other dental anomalies.

MATERIALS AND METHODS

The dental records of 240 patients with non-syndromic congenitally missing teeth treated at the University of Alabama at Birmingham Department of Orthodontics were reviewed. Dolphin Imaging software was used to identify missing teeth, microdonts, peg laterals, impactions, and transpositions. Data were analyzed using chi-square or Fisher's exact test. All the tests were two-sided at the significance level of 0.05 (SAS 9.4).

RESULTS

In the patient cohort, MLIA prevalence was 37.5% (second most common) and no gender or ethnic differences were identified. We also observed the bilaterally missing lateral incisors more frequently than the unilateral presentation (p = 0.0006). Additionally, 62.5% of patients with unilateral MLIA displayed a contralateral tooth that was a peg (p = 0.0001); however, no association was found with other microdonts. Furthermore, of the 90 patients missing at least one maxillary lateral incisor, 42.2% were missing another tooth type and 10% of MLIA patients also had an impacted tooth (mainly maxillary canines). However, these were not statistically significant. Finally, no transposed teeth were found in our patients.

CONCLUSIONS

This study found that maxillary lateral incisors were the second most frequently missing teeth. When clinicians diagnose congenital absence of a maxillary lateral incisor, the patient should be evaluated for other missing teeth, peg lateral incisors, or potential impactions, especially maxillary canines.

Congenitally missing second permanent molars in non‑syndromic patients (Review)

Hypodontia (tooth agenesis) is regarded as the most common congenital dental anomaly. The present review discusses the epidemiological characteristics of congenitally missing second permanent molars (CMSPMs) within a systematic review of the literature. The review was based on Pubmed library associated with the search of various scientific databases or academic resources, improved by hand search of reference lists. The terms ‘hypodontia’ or ‘anodontia’ in combination with ‘prevalence’ or ‘epidemiology’ were searched in the data sources for studies published between January 2001 and December 2020. Abstracts of non-English papers were also analyzed. The inclusion criteria were as follows: i) Study provided precise data about CMSPMs, even if no second permanent molar was reportedly missing; ii) the number of CMSPMs distributed by jaw was provided and iii) studies on subjects >3 years were used. The exclusion criteria were as follows: i) Studies on patients with history of trauma of the maxilla or the mandible, any type of syndrome affecting bone metabolism, metabolic disorders, previous extraction or tooth loss due to dental caries, cleft lip and palate; ii) studies performed on cohorts of patients with hypodontia and iii) studies reporting data including third molars, except for those that presented sufficient data to perform correct calculations. A total of 79 studies were selected, accumulating a population of 281,968 people, with an average sample size of 3,524.60±11,255.25. The prevalence of CMSPMs (IpHSPM) was 2.79±3.16% among all missing teeth (1.03±1.59% for upper CMSPMs and 1.76±2.32% for lower CMSPMs; P=0.011). There were no significant differences (P=0.250) in IpHSPM between men (1.59±1.52%) and women (2.13±1.67%). However, significant differences were recorded between continents. Furthermore, lower CMSPMs were found more frequently in orthodontic samples (P=0.033). The prevalence of CMSPMs is low compared with the overall prevalence of CM teeth. Despite the rarity of these anomalies, early detection is important to enable practitioners to plan and start treatment at the best time for optimal results.

Association between tooth agenesis and cancer: a systematic review

The congenital absence of multiple teeth may share the same genetic background of the development of some types of cancer. Objective: This systematic review aimed to investigate the possible association between dental agenesis and cancer, and the perspective of agenesis as an early predictor for cancer risk. Methodology: The electronic databases PubMed, Scopus, Web of Science, Cochrane Library, LILACS, and OpenGrey were searched and the risk of bias was evaluated using the Newcastle-Ottawa tool. The GRADE tool was used to evaluate the certainty of the evidence. Results: Six studies met the eligibility criteria. A positive co-occurrence between ovarian cancer and hypodontia was found in two articles. Three studies evaluated the association between dental agenesis and colorectal cancer and only one showed common genes for these conditions. One paper found individuals with hypodontia had a higher risk of family history of cancer. Five studies had a fair quality and one a good quality. The certainty of evidence was classified as very low. Conclusion: Notwithstanding the limited scientific evidence, there may be a possible association between dental agenesis and cancer due to genes involved in both conditions. Agenesis of multiple teeth could be an early indicator of cancer risk. Nevertheless, studies with a better level of evidence are needed to confirm this possible association.

Tooth agenesis: What do we know and is there a connection to cancer?

Like all developmental processes, odontogenesis is highly complex and dynamically regulated, with hundreds of genes co-expressed in reciprocal networks. Tooth agenesis (missing one or more/all teeth) is a common human craniofacial anomaly and may be caused by genetic variations and/or environmental factors. Variants in PAX9, MSX1, AXIN2, EDA, EDAR, and WNT10A genes are associated with tooth agenesis. Currently, variants in ATF1, DUSP10, CASC8, IRF6, KDF1, GREM2, LTBP3, and components and regulators of WNT signaling WNT10B, LRP6, DKK, and KREMEN1 are at the forefront of interest. Due to the interconnectedness of the signaling pathways of carcinogenesis and odontogenesis, tooth agenesis could be a suitable marker for early detection of cancer predisposition. Variants in genes associated with tooth agenesis could serve as prognostic or therapeutic targets in cancer. This review aims to summarize existing knowledge of development and clinical genetics of teeth. Concurrently, the review proposes possible approaches for future research in this area, with particular attention to roles in monitoring, early diagnosis and therapy of tumors associated with defective tooth development.

Are developmentally missing teeth a predictive risk marker of malignant diseases in non-syndromic individuals? A systematic review

Background:

Different genes and loci that are associated with non-syndromic developmental tooth agenesis (TA) have the same causation pathway in the development of tumours including breast cancer (BC), epithelial ovarian cancer (EOC), colorectal cancer (CRC) and lung cancer (LC).

Objectives:

To assess the link between TA and the development of cancer.

Search sources:

This registered review included a comprehensive search of electronic databases (Cochrane Central Register of Controlled Trials [CENTRAL], LILACS, Scopus, Web of Science and Medline via Ovid) until 1 April 2020, supplemented by manual, grey literature and reference lists search. There was no restriction in term of date of publication, gender, race or type of hypodontia.

Data selection:

The primary outcome was the relationship between TA and cancer. The secondary outcome was to identify the genetic correlation between TA and cancer.

Data extraction:

Study selection, data extraction and risk of bias assessment were performed independently and induplicate by two reviewers, with disputes resolved by a third reviewer.

Results:

Eight studies with a moderate-high risk of bias were included in the final review, with a total of 5821 participants. Due to the heterogeneity among the included studies, the data were presented narratively. Limited studies reported a high prevalence of EOC (19.2%–20%) and CRC (82%–100%) in individuals with TA (depending on the study) compared to those without TA (3% for EOC and 0% for CRC). While others reported a weak correlation between EOC and CRC and TA ( P > 0.05). Weak evidence suggested a strong correlation between breast, cervical uterine and prostate cancers and TA ( P < 0.05).

Conclusions:

Though low-quality evidence suggests a link between TA and cancer, it was not possible to verify that TA can hold a predictive value as a marker for cancers. Further research is needed to confirm the association.

Registration:

PROSPERO (CRD42020139751).

Variations in AXIN2 predict risk and prognosis of colorectal cancer

Objective

Colorectal cancer (CRC) and hypodontia are frequent and different diseases with common genes are involved in their etiology. The objective of this study was to identify the association between AXIN2 rs2240308 with hypodontia and CRC.

Patients and methods

This study consisted of 50 individuals with hypodontia, 50 individuals with CRC, and 155 healthy individuals from Colombia. SNP genotyping assays of rs2240308 were performed and family history of cancer in individuals with hypodontia was documented. In silico analysis was implemented to define the genomic profile of the AXIN2 gene associated with CRC. Multivariate analysis, chi square, odd ratio tests, and R software were used for statistical analysis.

Results

AXIN2 rs2240308 showed association with CRC (OR = 5.4 CI: 2.7–10.4; p < 0.001) and with other familial cancer in individuals with hypodontia (p < 0.005 OR = 1.75, 95% CI: 1.22–6.91). In silico analysis showed that variations in AXIN2 found in CRC patients, were more frequently in earlier stages of tumor and patients who carry variations in the AXIN2 gene have a worse prognosis (p < 0.05). The association between AXIN2 rs2240308 with hypodontia was not significant.

Conclusions

These results suggest that AXIN2 rs2240308 polymorphism is associated with CRC and AXIN2 could be a risk marker for predisposition and prognosis of CRC.

Diagnosis of Tooth Agenesis in Childhood and Risk for Neoplasms in Adulthood

Background

Tooth agenesis, the congenital absence of one or more teeth, can be diagnosed in children in the first decade of life. Tooth agenesis is a phenotypic feature of conditions such as ectodermal dysplasia, cleft lip, cleft palate, Down syndrome, and Van der Woude syndrome. Tooth agenesis can also be nonsyndromic. Studies have shown an association between the genetic determinants of nonsyndromic tooth agenesis and neoplasms in adulthood.

Methods

This review of the implications of tooth agenesis as a risk indicator for neoplasms in adulthood is based on a search of PubMed to identify published case series, case reports, and review articles. The reference articles were manually searched. The search was limited to articles published in the English language.

Results

Neoplasms reported in patients with tooth agenesis include colorectal neoplasms and epithelial ovarian cancer, as well as family histories of breast cancer, prostate cancer, and cancers of the brain and nervous system.

Conclusion

Although odontogenesis and tumorigenesis may seem to be unrelated processes, the clinical association between the two highlights the overlap of genetic determinants and molecular pathways. Tooth agenesis can be diagnosed during childhood and should be considered a marker for risk of neoplasms in adulthood. Healthcare providers should identify tooth agenesis and provide appropriate anticipatory guidance.

Nonsyndromic cleft lip and palate, gastric cancer and tooth agenesis

Background

To determine the frequency of nonsyndromic cleft lip and/or palate (NSCL/P) in first-degree relatives and to analyze the prevalence of tooth agenesis in patients with gastric cancer.

Material and Methods

This cross-sectional, observational, case-control study included 798 patients attended at hospital Santa Casa in Montes Claros, Minas Gerais and Alfa Institute of Gastroenterology of the Federal University of the Minas Gerais. Information on basic demographic data and tooth agenesis of both groups and their family history of NSCL/P in first-degree relatives were evaluated. The collected information was stored in a database and analyzed using statistical program SPSS® version 21.0 and the values with p<0.05 were considered statistically significant.

Results

Of the 798 patients, 113 (14.16%) consisted of the case group and 685 of the control group (85.84%). Non-Caucasian males were the most affected, although no differences among the groups were detected. Of all participants (n=798), 66 (8.27%) presented tooth agenesis and 25 (3.13%) presented oral cleft in first degree relative.

Conclusions

Our results no found increase in the frequency of tooth agenesis in patients with gastric cancer and in the frequency of NSCL/P in the first-degree relatives of patients with gastric cancer.

Key words:Nonsyndromic cleft lip and/or palate, tooth agenesis, gastric cancer.

Nonsyndromic oligodontia : Does the Tooth Agenesis Code (TAC) enable prediction of the causative mutation?

OBJECTIVES

The literature suggests an association between phenotype and causative mutation in nonsyndromic oligodontia. Thus, the present study was designed to verify this hypothesis in a consecutive cohort of patients.

METHODS

All patients with nonsyndromic oligodontia who had been treated at the study center (Department of Orthodontics, University of Giessen, Germany) over the period 1986-2013 were contacted. Candidates were included only if at least one more family member had hypo- or oligodontia (i.e., without regard to the number of congenitally missing teeth). A total of 20 patients were included. After evaluating the dental status of each participant, the Tooth Agenesis Code (TAC) was applied. On this basis, a tentative diagnosis was made to predict which gene (MSX1, AXIN2, EDA, or PAX9) was likely to show mutation. Afterwards this hypothesis was confirmed or rejected by analyzing a saliva sample for mutation of the predicted gene. If confirmed, any available family members were also genetically analyzed.

RESULTS

Based on their TAC scores and sums, gene mutations were predicted for MXS1 in 11, AXIN2 in 3, EDA in 6, and PAX9 in none of the patients. The evaluation of MSX1 yielded variants in 4 of 11 cases, all of which were classified as nonpathogenic since they were not considered as functional mutations. The evaluation of EDA yielded a pathogenic exon-7 mutation in 2 of 6 patients, both being brothers with different TAC scores; the same mutation, which represents a novel missense mutation, was also found in other members of the same family. The evaluation of AXIN2 yielded variants in 3 of 3 cases, all of which were classified as nonpathogenic.

CONCLUSIONS

Our findings obtained in consecutive patients with nonsyndromic oligodontia did not reveal any clinically relevant associations between oligodontia phenotype (based on TAC) and causative mutations for nonsyndromic oligodontia.

Prevalence and Pattern of Non-Syndromic Hypodontia in a Group of Turkish Children

OBJECTIVE

The aim of this study was to assess the prevalence and pattern of congenital missing teeth in the permanent dentition (excluding wisdom teeth), among Turkish children in a 4-year period (2009-2012).

METHODS

The study group comprised 1658 children (873 girls, 785 boys). The children were examined in Department of Pediatric Dentistry, Dental School of Marmara University. A chi square test was used to determine the difference in the prevalence of hypodontia between genders.

RESULTS

The prevalence of hypodontia was 6.2% (6.3% girls, 6% boys) with no statistically significant difference between the genders (P=0.601). The most frequently missing tooth were the mandibular left second premolars, 63 (20.7%), followed by the mandibular right second premolars, 61(20.1%), maxillary left premolars, 31 (10.2%). There were 89 anterior and 214 posterior missing teeth. Bilateral hypodontia was observed in 70 (39 girls, 31 boys) patients (67.9%). The most common bilateral missing teeth were the mandibular second premolar (22 girls, 21 boys) (42.1%) and the maxillary second premolar (6 girls, 15 boys) (20.5%). The mandibular left second premolar (9 boys, 8 girls) was the most frequent unilaterally missing tooth (5.6%) followed by the mandibular right second premolar (10 girls, 6 boys) (5.28%).

CONCLUSION

The obtained results point to the importance of detailed clinical and radiographic examination. These help with long-term treatment planning according to a child's individual requirements.

Hypodontia and ovarian cancer: A systematic review

Hypodontia can be defined as the non-formation of one or more teeth during the developmental period. Mutation in several genes related to tooth formation has previously been correlated with cancer. Regarding the ovarian cancer, there are few studies that associate the presence of hypodontia with ovarian cancer. A systematic literature search was performed in PubMed and Scopus. In total, 385 patients were included in this study. Control group was present in 3 out of 4 studies (340 patients). Hypodontia was present in 56 out of 290 patients (incidence of 19.3%). Only in 2 out of 4 studies, the number of missing teeth was mentioned (47 teeth), while the majority of them were either maxillary second premolars or maxillary lateral incisors. Unilateral distribution of the missing teeth was present in 28 out of 46 patients, while bilateral distribution of the missing teeth was present in 18 out of 46 patients. The presence of ovarian cancer in the family medical history occurred in 12 out of 33 patients. Only 1 out of 4 studies examined the presence of genes with mutations in the included patients. Based on our findings, the lack of clinical studies was the principal obstacle to clarify the possible predictive value of hypodontia in the early prediction of patients with higher risk of ovarian cancer.

Prevalence of hypodontia and associated factors: a systematic review and meta-analysis

OBJECTIVES

To determine the prevalence and factors associated with hypotonia.

DESIGN

Systematic review and meta-analysis.

DATA SOURCE

A search strategy was developed along with inclusion criteria and run in MEDLINE and EMBASE (published from 2002 to August 2012) databases to reveal all studies on the prevalence of hypodontia or associated factors. A hand search of reference lists and a Google search aimed to improve the sensitivity of the literature search.

SELECTION CRITERIA

All studies on the prevalence of hypodontia or associated factors published from 2002 onwards were included. Abstracts of non-English papers were also analyzed.

DATA SELECTION AND EXTRACTION

All potential articles were checked against the inclusion criteria independently, and in duplicate by two investigators. A checklist was used to assess the quality of selected studies.

MAIN OUTCOME

Prevalence of hypodontia, excluding third molars.

RESULTS

The overall prevalence of hypodontia was found to be 6.4% (95% CI: 5.7, 7.2). There was a statistically significant difference in the prevalence of hypodontia by continent (Q = 34.18, P<0.001). Prevalence of hypodontia was the highest in Africa: 13.4% (95% CI: 9.7, 18.0), followed by Europe (7% CI: 6.0-8.0%), Asia (6.3% CI: 4.4, 9.1) and Australia (6.3% CI: 5.3, 7.4) with a lower prevalence in North America (5.0% CI: 4.1-5.9) and Latin America and Caribbean (4.4% CI: 3.2-6.1). Females were found to have a higher prevalence than males (combined OR 1.22; 95% CI: 1.14, 1.30). The most commonly affected teeth were mandibular second premolars followed by maxillary lateral incisors and maxillary second premolars. The prevalence of mild, moderate and severe hypodontia was found to be 81.6, 14.3 and 3.1% respectively.

CONCLUSIONS

There was a high variation in the prevalence of hypodontia between the studies. African populations were found to have a higher risk for tooth agenesis and there was an increased risk for females to have hypodontia than males.

The Gene Network Underlying Hypodontia

Mammalian tooth development is a precise and complicated procedure. Several signaling pathways, such as nuclear factor (NF)-κB and WNT, are key regulators of tooth development. Any disturbance of these signaling pathways can potentially affect or block normal tooth development, and presently, there are more than 150 syndromes and 80 genes known to be related to tooth agenesis. Clarifying the interaction and crosstalk among these genes will provide important information regarding the mechanisms underlying missing teeth. In the current review, we summarize recently published findings on genes related to isolated and syndromic tooth agenesis; most of these genes function as positive regulators of cell proliferation or negative regulators of cell differentiation and apoptosis. Furthermore, we explore the corresponding networks involving these genes in addition to their implications for the clinical management of tooth agenesis. We conclude that this requires further study to improve patients' quality of life in the future.

Hypodontia phenotype in patients with epithelial ovarian cancer

BACKGROUND

Ovarian cancer is usually diagnosed in an advanced stage and the present clinical and diagnostic molecular markers for early OC screening are insufficient. The aim of this study was to identify potential relationship between the hypodontia and epithelial ovarian cancer (EOC).

PATIENTS AND METHODS

A retrospective study was conducted on 120 patients with EOC treated at the Department of Gynaecologic and Breast Oncology at the University Clinical Centre and 120 gynaecological healthy women (control group) of the same mean age. Women in both groups were reviewed for the presence of hypodontia and the patients with EOC also for clinicopathological characteristics of EOC according to hypodontia phenotype.

RESULTS

Hypodontia was diagnosed in 23 (19.2%) of patients with EOC and 8 (6.7%) controls (p = 0.004; odds ratio [OR] = 3.32; confidence interval [CI], 1.42-7.76). There was no statistically significant difference in patients with EOC with or without hypodontia regarding histological subtype (p = 0.220); they differed in regard to FIGO stage (p = 0.014; OR =3.26; CI, 1.23-8.64) and tumour differentiation grade (p = 0.042; OR = 3.1; CI, 1.01-9.53). Also, bilateral occurrence of EOC was more common than unilateral occurrence in women with hypodontia (p = 0.021; OR = 2.9; CI, 1.15-7.36). We also found statistically significant difference between the ovarian cancer group and control group in presence of other malignant tumours in subjects (p < 0.001).

CONCLUSIONS

The results of the study suggest a statistical association between EOC and hypodontia phenotype. Hypodontia might serve as a risk factor for EOC detection.

DLX1 and MMP3 contribute to oral clefts with and without positive family history of cancer

OBJECTIVE

It has been suggested that oral clefts and cancer share a common genetic background. This study aimed to investigate the epidemiological and molecular association between oral clefts and cancer.

METHODS

One hundred forty-eight nuclear families with oral clefts and 162 subjects with no birth defect were recruited. Data on self-reported family history of cancer among first, second, and third degree relatives of each patient were collected via a structured questionnaire. We also investigated the association between polymorphisms in the genes AXIN2, BMP2, BMP4, BMP7, DLX1, DLX2, and MMP3 and oral cleft with and without history of cancer. Markers in these genes were genotyped using real time PCR. Chi-square and t-test were used to assess the differences about self-reported family history of cancer between oral cleft and non-cleft individuals. The transmission disequilibrium test (TDT) was used to analyze the distortion of the inheritance of alleles from parents to their affected offspring.

RESULTS

Families with oral clefts had an increased risk of having a family history of cancer (p=0.01; odds ratio=1.79; 95% confidence interval, 1.07-1.87). TDT results showed an association between DLX1 and cleft lip and palate, in which the A allele was undertransmited (p=0.022). For MMP3, G was undertransmited among affected progeny (p=0.019) in cleft palate subgroup.

CONCLUSION

Oral clefts were associated with positive self-reported family history of cancer and with variants in DLX1 and MMP3. The association between oral clefts and cancer raises interesting possibilities to identify risk markers for cancer.

Hypodontia prevalence and pattern in women with epithelial ovarian cancer

OBJECTIVE

To analyze the possible association between hypodontia and epithelial ovarian cancer (EOC), with the special interest in hypodontia pattern.

MATERIALS AND METHODS

One hundred twenty women with EOC treated at the Department of Gynecologic and Breast Oncology at the University Clinical Centre and 120 gynecologically healthy women of the same average age were reviewed for the presence and pattern of hypodontia. Collected data were analyzed for frequency, tooth type, location per jaw and side, number of missing teeth per person, and family history of hypodontia.

RESULTS

The results of the study showed prevalence of hypodontia in 19.2% of women with EOC and in 6.7% of women in the control group (P  =  .004). The most frequently missing teeth for women with EOC and women in the control group were maxillary second premolars and maxillary lateral incisors, respectively. Unilateral occurrence of hypodontia was more common than bilateral occurrence in women with EOC (P  =  .034). Of women with EOC and hypodontia, 21.7% reported a positive family history of hypodontia compared with no report in the control group of women with hypodontia (P  =  .150).

CONCLUSIONS

The results statistically support possible association between EOC and hypodontia. Because hypdontia can be recognized early in life, this finding could possibly help in earlier detection of EOC, resulting in better prognosis and treatment in earlier stages of the disease. Earlier EOC diagnosis and treatment could save many lives.

Prevalence of hypodontia in a sample of Sudanese orthodontic patients

Objective:

The aims of this study were to determine the prevalence of hypodontia in the permanent dentition in a sample of Sudanese patients who sought orthodontic treatment and to compare the results with the reported findings of other populations.

Materials and Methods:

Orthodontic files including orthopantomographs of 1069 patients (760 females and 309 males - more than 8 years old) were examined and inspected for evidence of hypodontia.

Results:

The prevalence of hypodontia of the present sample was 5.1%. Hypodontia was found considerably more frequently in the mandible than in the maxilla. The distribution of missing teeth was noticed in the left side more than in the right side. The most frequently missing teeth were the maxillary lateral incisors, followed by the mandibular second premolars, maxillary second premolars and mandibular left lateral incisor. The majority of patients had two or three teeth missing, but rarely more than 5 teeth missing.

Conclusions:

The prevalence of hypodontia of this study was within the range of that reported in the literature. The incidence of hypodontia in the anterior segment requires great need for orthodontic and prosthodontic treatment. With early detection of hypodontia, alternative treatment modalities can be planned and performed with a multidisciplinary team approach restoring the esthetic and function.

Is there a link between ovarian cancer and tooth agenesis?

An epidemiologic study from the year 2008 found a highly significant increase of congenital tooth agenesis in women with ovarian cancer suggesting that a common genetic etiology may predispose women to both conditions. The finding was reminiscent of a previously described family harboring an AXIN2 mutation which could be shown to segregate with both the tooth agenesis and the predisposition to colon cancer transmitted in this family. Since tooth agenesis as a marker for susceptibility to ovarian cancer would be of great relevance to both oncologists and women with inborn missing teeth, the relationship between the two disorders requires a thorough assessment. We examined DNA samples from the ovarian cancer patients who participated in the original study, to look for a possible genetic connection between their ovarian malignancies and tooth agenesis. MSX1, PAX9, AXIN2, EDA, WNT10A, BARX and BRCA1 genes were selected for sequence analysis as they may cause tooth agenesis, are expressed in the female reproductive system, and/or are involved in tumorigenesis in general or specifically in the ovary. Our study revealed evidence that one half of the dually affected patients had an independent causation of the two conditions, thus reducing the previously estimated ovarian cancer risk for women with congenital tooth agenesis quite significantly.

Genetic background of nonsyndromic oligodontia: a systematic review and meta-analysis

OBJECTIVES

The goal of this work was to identify all known gene mutations that have been associated with the development of nonsyndromic oligodontia.

METHODS

A systematic literature search was performed electronically in two databases (PubMed, Medpilot) supplemented by a hand search. Articles published up to March 2012 were considered. Search terms were combined as follows: oligodontia and genes, oligodontia and mutations, tooth agenesis and genes, and tooth agenesis and mutations. A meta-analysis of the data was conducted based on the Tooth Agenesis Code (TAC).

RESULTS

Seven genes are currently known to have a potential for causing nonsyndromic oligodontia. All these genes vary both in terms of number of identified mutations and in terms of number of documented patients: 33 mutations and 93 patients are on record for PAX9, 10 mutations and 51 patients for EDA, 12 mutations and 33 patients for MSX1, 6 mutations and 17 patients for AXIN2, and 1 mutation in 1 patient for EDARADD, NEMO, and KRT17 each. A total TAC score of 250 was found to have cutoff properties, as 100% of MSX1 and 80% of EDA patients exhibited TAC ≤ 250, whereas 96.9% of PAX9 and 90% of AXIN2 patients exhibited TAC >250. Furthermore, 94.3% of EDA patients but only 28.6% of MSX1 patients exhibited odd-numbered TAC scores in at least one quadrant, and 72.7% of PAX9 but none of the AXIN2 patients were found to show TAC scores of 112 in at least one quadrant.

CONCLUSION

In order of decreasing frequency, PAX9, EDA, MSX1, AXIN2, EDARADD, NEMO, and KRT17 are the seven genes currently known to have a potential for causing nonsyndromic oligodontia. TAC scores enabled us to identify an association between oligodontia phenotypes and genotypes in the patients covered by this meta-analysis.

Tooth Agenesis Association with Self-reported Family History of Cancer

It has been proposed that tooth agenesis and cancer development share common molecular pathways. We performed a cross-sectional study to investigate the epidemiological and molecular association between tooth agenesis and self-reported family history of cancer. Eighty-two individuals with tooth agenesis and 328 individuals with no birth defect were recruited from the same institution. Tooth agenesis was assessed in permanent teeth and was defined based on the age of the participants and when initial tooth formation should be radiographically visible. We also investigated the role of genes involved in dental development that have been implicated in tumorigenesis, and 14 markers in AXIN2, FGF3, FGF10, and FGFR2 were genotyped. Individuals with tooth agenesis had an increased risk of having a family history of cancer ( p = 0.00006; OR = 2.7; 95% C.I., 1.6-4.4). There were associations between AXIN2, FGF3, FGF10, and FGFR2 with tooth agenesis [ i.e., individuals who carried the polymorphic allele of FGFR2 (rs1219648) presented higher risk for having premolar agenesis ( p = 0.02; OR = 1.8; 95% C.I., 1.1-3.0)]. In conclusion, tooth agenesis was associated with positive self-reported family history of cancer and with variants in AXIN2, FGF3, FGF10, and FGFR2. Prospective studies are needed to confirm if tooth agenesis can be used as a risk marker for cancer.

The validity of self-reported dental agenesis

The optimal tools for obtaining a diagnosis of dental agenesis (DA) among adults are childhood dental records and radiographs. However, these are often not available, and therefore the present study aimed to assess whether DA in adults could be validly assessed by self-reported information guided by a questionnaire. A questionnaire eliciting information on DA of permanent teeth was constructed, pilot-tested, and subsequently posted to a case group consisting of 334 young adults, for whom the DA status had been ascertained in the period from 1992 to 2002. A control group, consisting of 258 young adults randomly selected from the population from which the cases originated, was also approached with questionnaires. The response rate was 53.7% among cases and 46.4% among controls. The sensitivity and specificity of self-reported DA were estimated to be at least 0.88 (95% CI = 0.82-0.92) and 0.95 (95% CI = 0.89-0.98), respectively. These diagnostic test parameters are clearly inadequate for population-screening purposes. However, when screening patient groups with a higher occurrence of DA than is characteristic of the background population, the self-reported DA status may be a useful tool for identifying risk groups for conditions associated with the presence of DA.

Genetic basis of tooth agenesis

Tooth agenesis or hypodontia, failure to develop all normally developing teeth, is one of the most common developmental anomalies in man. Common forms, including third molar agenesis and hypodontia of one or more of the incisors and premolars, constitute the great majority of cases. They typically affect those teeth that develop latest in each tooth class and these teeth are also most commonly affected in more severe and rare types of tooth agenesis. Specific vulnerability of the last developing teeth suggests that agenesis reflects quantitative defects during dental development. So far molecular genetics has revealed the genetic background of only rare forms of tooth agenesis. Mutations in MSX1, PAX9, AXIN2 and EDA have been identified in familial severe agenesis (oligodontia) and mutations in many other genes have been identified in syndromes in which tooth agenesis is a regular feature. Heterozygous loss of function mutations in many genes reduce the gene dose, whereas e.g. in hypohidrotic ectodermal dysplasia (EDA) the complete inactivation of the partially redundant signaling pathway reduces the signaling centers. Although these mechanisms involve quantitative disturbances, the phenotypes associated with mutations in different genes indicate that in addition to an overall reduction of odontogenic potential, tooth class-specific and more complex mechanisms are also involved. Although several of the genes so far identified in rare forms of tooth agenesis are being studied as candidate genes of common third molar agenesis and incisor and premolar hypodontia, it is plausible that novel genes that contribute to these phenotypes will also become identified.