Dental caries one of the world’s commonest chronic diseases has been estimated to affect almost 50% of the world’s population. It is a sugar-dependent biofilm disease that is modulated by multiple factors with environmental and host factors affecting caries risk. However, there is variation in disease onset and prevalence among individuals exposed to the same risk factors that may indicate a genetic influence although no consensus. As monozygotic twins have identical genetic codes, and dizygotic twins share half of their genes the use of comparative studies between them have been used to estimate the participation of genotype and environment in the occurrence of dental caries.
The aim of this review was to assess the agreement of dental caries experience between monozygotic (MZ) and dizygotic twins (DZ).
Methods
The review protocol was registered on the PROSPERO database. Searches were conducted on the Embase, Medline/PubMed, Scopus, Google Scholar (first 300 articles) and OpenGrey databases. This was supplemented by hand searches of the Journals, Archives of Oral Biology, Caries Research, Community Dentistry and Oral Epidemiology, International Journal of Paediatric Dentistry, Journal of Dental Research and Paediatric Dentistry for the last 5 years. Observational studies (cross-sectional, case- control, and prospective and retrospective cohorts) that compared dental caries agreement between dentate MZ and DZ twins of all age groups were considered. Two reviewers independently selected studies extracted data and assessed risk of bias using the Joanna Briggs Institute checklists (JBI-CAT). Odds Ratio (OR) and 95% confidence intervals were calculated for each study and meta-analyses conducted. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) scale was used to assess the certainty of evidence.
Results
- 19 studies (11 cross-sectional,7 longitudinal, 1 case-control) were included.
- Studies were published between 1958 – 2020 from 11 countries.
- The studies involved a total of 42,536 people aged between 18 months to 97 years of age.
- 21% of studies were considered to be at high risk of bias, 47.7% at moderate risk and 31.6% at low risk.
- 6 studies contributed to the meta-analyses.
- Meta-analysis for general agreement of dental caries showed a greater change of agreement between MZ twins for: –
- primary dentition, OR = 68 (95%CI: 1.23 to 26.35) [1 study].
- both dentitions, OR = 6.58 (95%CI: 1.55 to 27.88) [4 studies].
- Overall, OR = 5.94 (95%CI: 2.00 to 17.57) [ 5 studies].
- Two studies evaluated agreement of DMF one in the primary and one in the permanent dentition No difference was seen between MZ and DZ twins, OR = 86 (95%CI: 0.25 to 32.79).
- The certainty of evidence was assessed as very low.
Conclusions
The authors concluded: –
with very low certainty of the evidence, there was a greater agreement of dental caries between monozygotic twins than in dizygotic twins, suggesting the influence of genetics on the development of the disease.
Comments
The authors registered their protocol with the PROSPERO database and searched a good reange of databases to identify relevant studies. In a change from the protocol, they used the JBI tools to assess risk of bias rather than the Agency for Healthcare Research and Quality (AHRQ) scale for cross-sectional studies and the Newcastle-Ottawa Scale. While 31% of the included studies were considered to be at low risk of bias all 19 of the included studies did not address one of more of the eight JBI checklist questions. Only 7 of the included studies identified potential confounders with just one study controlling for confounders. The authors also raised other concerns related to the primary studies in relation to lack of details on the selection of participants criteria for assessing zygosity and measurement of caries. Consequently, although the analysis is suggestive of a genetic influence the certainty of evidence is very low so the findings should be interpreted very cautiously.
Links
Primary Paper
Dos Anjos AMC, Moura de Lima MD, Muniz FWMG, Lima CCB, Moura LFAD, Rösing CK, de Moura MS. Is there an association between dental caries and genetics? Systematic review and meta-analysis of studies with twins. J Dent. 2023 Aug;135:104586. doi: 10.1016/j.jdent.2023.104586. Epub 2023 Jun 18. PMID: 37339689.
Other references
Dental Elf – 11th Jun 2021
https://www.nationalelfservice.net/dentistry/caries/early-childhood-caries-global-prevalence/
Dental Elf – 9th Mar 2015
https://www.nationalelfservice.net/dentistry/caries/untreated-caries-a-significant-global-problem/
Picture Credits
Photo by Keisha Montfleury on Unsplash
