The effects of estrogen receptor α polymorphism on the prevalence of symptomatic temporomandibular disorders.
The aim of this study is to identify any association between variants of the polymorphic estrogen receptor gene and various symptoms of temporomandibular disorder (TMD) including pain in the temporomandibular joint and masticatory muscles, joint crepitus, limited range of jaw movement, and bone changes in the condylar head. Seventy-four patients with TMD were selected according to the Research Diagnostic Criteria for TMD for the study group. Sixty-four patients without TMD were selected as the control group. Genomic DNA was extracted from the epithelial layer of buccal mucosa. After amplification by polymerase chain reaction, direct haplotyping was undertaken to study the restriction fragment length polymorphism of PvuII and XbaI for the α estrogen receptor. Genomic prevalences in each of the symptom categories were analyzed by use of the χ(2) test. The haplotypes PX, Px, and px constituted 23.0%, 18.9%, and 58.1%, respectively, of the total α estrogen receptor alleles in the study group. The haplotype Px was found to be relatively more prevalent in subjects who had mouth opening limitation, and the haplotype PX was more prevalent in those patients with condylar head bone changes. However, neither of these observations carried statistical significance. Although certain symptoms of TMD were found to have a relatively higher prevalence of one form or another of the estrogen receptor allele, no haplotype was confirmed to be a significant marker of TMD risk.