Genetic and environmental influence on sleep bruxism in preschoolers: A twin study

To evaluate the influence of genetic and environmental factors associated with SB and to compare the coincidence of SB diagnoses among monozygotic (MZ) and dizygotic (DZ) preschool twin pairs.

This was a cross-sectional census study conducted with preschool twins aged 3-5 years enrolled in public and private schools in Teresina, Brazil. Data were collected through questionnaires (socioeconomic status, general health conditions, sleep aspects, and zygosity) answered by parents and through clinical examinations. SB was assessed by positive parental reports combined with the presence of tooth wear on more than three teeth. Coincidence was analyzed using tetrachoric correlation and multinomial regression. Heritability was calculated using Holzinger's formula. Multilevel logistic regression was performed to identify factors associated with SB at the individual and pair levels (p < 0.05).

A total of 219 twin pairs (n = 438) participated in the study. The prevalence of SB was 18.9 %. Attending a private school (OR = 3.02; IC95 % = 1.27-7.13), being male (OR = 2.05; IC95 % = 1.07-3.93), having bronchitis (OR = 3.32; IC95 % = 1.32-8.34), snoring (OR = 2.46; IC95 % = 1.28-4.71), being five years old (OR = 3.00; IC95 % = 1.27-7.03), and being a DZ twin (OR = 2.27; IC95 % = 1.06-4.67) increased the likelihood of SB (p < 0.05). MZ twin pairs showed a very strong correlation for SB (rMZ = 0.943) and a higher likelihood of diagnostic coincidence. The heritability estimate was 94 %.

The very strong correlation for SB among MZ twin pairs and the high heritability suggest a genetic influence on the development of SB.