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Genetics and environmental factors play important roles in the risk for periodontal disease and edentulism
HARM / ETIOLOGY
A R T I C L E A N A LY S I S & E VA L U AT I O N Genetics and environmental factors play important roles in the risk for periodontal disease and edentulism SUMMARY Subjects Subjects were recruited from the Swedish Twin Registry. A total of 10,578 complete twin pairs aged 42 years and older participated in the study. This included 1567 monozygotic (MZ) and 2127 dizygotic (DZ) female twin pairs, 1180 MZ and 1696 DZ male pairs and 4008 DZ opposite sex pairs. Zygosity was determined by self-report when both twins reported being as similar as ‘‘two peas in a pod’’ or not more alike than general siblings. Oral health status was by self-report. Complete edentulism was reported in 6% of the twins, periodontal disease in 18%, and gingivitis in 24% of twins.
Exposure The primary exposure in this study is the genetic background or zygosity of the twin pairs.
Main Outcome Measure The main outcome measure was the genetic contribution to the risk for periodontal disease (including edentulism).
Main Results The relative risk of edentulism when the individual’s co-twin was edentulous was 4.2 for MZ twins and 2.6 for DZ twins. One third of the risk for periodontal disease for both men and women could be accounted for by genetic factors.
Conclusions This study shows that the greatest variation in risk for periodontal disease comes from nonshared environmental factors (such as smoking) while a moderate and important contribution comes from genetic factors.
COMMENTARY AND ANALYSIS This is a very powerful, well-designed study that provides convincing evidence for the important contribution of genetics in the risk for periodontal disease. Previous studies of unrelated adults and of twins raised apart had similar conclusions.1,2 In these studies, the authors reported the heritability of periodontal disease to be between 13% and 30% for aggressive periodontal disease1 and 50% for adult periodontitis.2 Although there are potential limitations to the current study, including self-reporting of periodontal status and zygosity, both of these limitations would result in an underestimation of disease and zygosity and would result in more conservative estimates of the genetic contribution to disease risk. Historically, dental professionals have used a ‘‘one size fits all’’ approach to the prevention of oral diseases. This was based on the assumption that dental disease is completely preventable and is primarily the result of behavioral and environmental influences such as diet, oral hygiene, smoking, alcohol use, and presence of bacterial pathogens. This study provides evidence that in addition to environmental factors, there are important genetic factors that influence susceptibility to periodontal disease. This component of risk should be con-
ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION Environmental and heritable factors in the etiology of oral diseases—a population-based study of Swedish twins. Mucci LA, Bjorkman L, et al. J Dent Res 2005;84(9):800-5.
LEVEL OF EVIDENCE 2b
PURPOSE/QUESTION To determine the contributions of genetics, shared environmental factors, and nonshared environmental factors within twin pairs for the risk of periodontal disease, gingivitis, and edentulism.
SOURCE OF FUNDING Government – NIH/NIDCR
TYPE OF STUDY/DESIGN Cohort study
J Evid Base Dent Pract 2006;6:238-9 1532-3382/$35.00 Ó 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.jebdp.2006.06.011
JOURNAL OF EVIDENCE-BASED DENTAL PRACTICE
sidered when providing oral health counseling to patients. A number of genes have been identified that have been shown to be associated with an increased risk for periodontal disease. These include Cathepsin C in Papillon-Lefevre Syndrome3 and interleukin-14 and CD145 in adult periodontal disease. Although there is a specific test for interleukin-1, there is currently not a test that is capable of predicting the genetic risk of periodontal disease for all individuals. Until such a test is available, clinicians should be aware that genetics plays an important role in the overall risk for periodontal disease and that an important part of the overall assessment of risk should include a family history of periodontal disease and/or tooth loss.
REFERENCES 1. Diehl SR, Wu T, Michalowicz BS, et al. Quantitative measures of aggressive periodontitis show substantial heritability and consistency with traditional diagnoses. J Periodontol 2005;76(2):279-88.
Volume 6, Number 3
2. Michalowicz BS, Diehl SR, Gunsolley JC, et al. Evidence of a substantial genetic basis for risk of adult periodontitis. J Periodontol 2000;71(11): 1699-707. 3. Cagli NA, Hakki SS, Dursun R, et al. Clinical, genetic, and biochemical findings in two siblings with Papillon-Lefevre Syndrome. J Periodontol 2005;76(12):2322-9. 4. Kornman KS, Crane A, Wang HY, et al. The interleukin-1 genotype as a severity factor in adult periodontal disease. J Clin Periodontol 1997; 24(1):72-7. 5. Laine ML, Morre SA, Murillo LS, van Winkelhoff AJ, Pena AS. CD14 and TLR4 gene polymorphisms in adult periodontitis. J Dent Res 2005; 84(11):1042-6.
REVIEWER Rebecca L. Slayton, MS, DDS, PhD Associate Professor, Pediatric Dentistry School of Dentistry University of Washington Seattle, WA 98195 [email protected]
Mucci et al
239
A R T I C L E A N A LY S I S & E VA L U AT I O N Genetics and environmental factors play important roles in the risk for periodontal disease and edentulism SUMMARY Subjects Subjects were recruited from the Swedish Twin Registry. A total of 10,578 complete twin pairs aged 42 years and older participated in the study. This included 1567 monozygotic (MZ) and 2127 dizygotic (DZ) female twin pairs, 1180 MZ and 1696 DZ male pairs and 4008 DZ opposite sex pairs. Zygosity was determined by self-report when both twins reported being as similar as ‘‘two peas in a pod’’ or not more alike than general siblings. Oral health status was by self-report. Complete edentulism was reported in 6% of the twins, periodontal disease in 18%, and gingivitis in 24% of twins.
Exposure The primary exposure in this study is the genetic background or zygosity of the twin pairs.
Main Outcome Measure The main outcome measure was the genetic contribution to the risk for periodontal disease (including edentulism).
Main Results The relative risk of edentulism when the individual’s co-twin was edentulous was 4.2 for MZ twins and 2.6 for DZ twins. One third of the risk for periodontal disease for both men and women could be accounted for by genetic factors.
Conclusions This study shows that the greatest variation in risk for periodontal disease comes from nonshared environmental factors (such as smoking) while a moderate and important contribution comes from genetic factors.
COMMENTARY AND ANALYSIS This is a very powerful, well-designed study that provides convincing evidence for the important contribution of genetics in the risk for periodontal disease. Previous studies of unrelated adults and of twins raised apart had similar conclusions.1,2 In these studies, the authors reported the heritability of periodontal disease to be between 13% and 30% for aggressive periodontal disease1 and 50% for adult periodontitis.2 Although there are potential limitations to the current study, including self-reporting of periodontal status and zygosity, both of these limitations would result in an underestimation of disease and zygosity and would result in more conservative estimates of the genetic contribution to disease risk. Historically, dental professionals have used a ‘‘one size fits all’’ approach to the prevention of oral diseases. This was based on the assumption that dental disease is completely preventable and is primarily the result of behavioral and environmental influences such as diet, oral hygiene, smoking, alcohol use, and presence of bacterial pathogens. This study provides evidence that in addition to environmental factors, there are important genetic factors that influence susceptibility to periodontal disease. This component of risk should be con-
ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION Environmental and heritable factors in the etiology of oral diseases—a population-based study of Swedish twins. Mucci LA, Bjorkman L, et al. J Dent Res 2005;84(9):800-5.
LEVEL OF EVIDENCE 2b
PURPOSE/QUESTION To determine the contributions of genetics, shared environmental factors, and nonshared environmental factors within twin pairs for the risk of periodontal disease, gingivitis, and edentulism.
SOURCE OF FUNDING Government – NIH/NIDCR
TYPE OF STUDY/DESIGN Cohort study
J Evid Base Dent Pract 2006;6:238-9 1532-3382/$35.00 Ó 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.jebdp.2006.06.011
JOURNAL OF EVIDENCE-BASED DENTAL PRACTICE
sidered when providing oral health counseling to patients. A number of genes have been identified that have been shown to be associated with an increased risk for periodontal disease. These include Cathepsin C in Papillon-Lefevre Syndrome3 and interleukin-14 and CD145 in adult periodontal disease. Although there is a specific test for interleukin-1, there is currently not a test that is capable of predicting the genetic risk of periodontal disease for all individuals. Until such a test is available, clinicians should be aware that genetics plays an important role in the overall risk for periodontal disease and that an important part of the overall assessment of risk should include a family history of periodontal disease and/or tooth loss.
REFERENCES 1. Diehl SR, Wu T, Michalowicz BS, et al. Quantitative measures of aggressive periodontitis show substantial heritability and consistency with traditional diagnoses. J Periodontol 2005;76(2):279-88.
Volume 6, Number 3
2. Michalowicz BS, Diehl SR, Gunsolley JC, et al. Evidence of a substantial genetic basis for risk of adult periodontitis. J Periodontol 2000;71(11): 1699-707. 3. Cagli NA, Hakki SS, Dursun R, et al. Clinical, genetic, and biochemical findings in two siblings with Papillon-Lefevre Syndrome. J Periodontol 2005;76(12):2322-9. 4. Kornman KS, Crane A, Wang HY, et al. The interleukin-1 genotype as a severity factor in adult periodontal disease. J Clin Periodontol 1997; 24(1):72-7. 5. Laine ML, Morre SA, Murillo LS, van Winkelhoff AJ, Pena AS. CD14 and TLR4 gene polymorphisms in adult periodontitis. J Dent Res 2005; 84(11):1042-6.
REVIEWER Rebecca L. Slayton, MS, DDS, PhD Associate Professor, Pediatric Dentistry School of Dentistry University of Washington Seattle, WA 98195 [email protected]
Mucci et al
239