Objective: To investigate the relationship between estrogen receptor (ER) and vitamin D receptor (VDR) gene polymorphisms and tooth loss, oral bone loss, and postcranial bone mineral density (BMD) in Japanese postmenopausal women.
Design: Polymorphisms at the ER Pvu II and Xba I and VDR Bsm I gene sites, number of teeth remaining, oral bone mass, and BMD of the lumbar spine and the hip were evaluated in 149 Japanese postmenopausal women.
Results: The distribution of ER Pvu II and Xba I and VDR Bsm I restriction fragment length polymorphisms was as follows: pp, 30.2%; Pp, 49.7%; PP, 20.1%; xx, 71.8%; Xx, 22.5%; XX, 2.7%; bb, 76.5%; Bb, 22.2%; and BB, 1.3%. Analysis of covariance adjusted for confounding variables revealed that participants with pp allele had fewer teeth remaining than did those with P allele. There were no significant differences in oral bone mass and postcranial BMD among three alleles at the Pvu II site. Participants with X and bb allele had less oral bone mass and lower postcranial BMD than did those with xx and B allele, respectively. We could not clarify the positive associations between Xba I and Bsm I polymorphism and number of teeth.
Conclusions: Pvu II polymorphism was associated with tooth loss, but not with oral bone mass and postcranial BMD. Xba I and Bsm I polymorphisms may be associated with bone mass or density; however, Pvu II polymorphism might contribute to another unknown pathway related to tooth loss.
Poor dentition status may be related to alteration of dietary intake, leading to deterioration in the systemic health of older adults. 1,2 The causes of tooth loss include dental caries, periodontal disease, eruption problems, trauma, orthodontics, and other reasons. 3 In Japan, women lose more teeth after 50 years of age than do men, although women have a high frequency of tooth brushing, fewer untreated teeth than men, and a low rate of gum disease. 4 The life span of all teeth in women is shorter than that in men. This fact implies the possibility that estrogen deficiency after menopause may in part cause tooth loss as a consequence of oral bone loss. Recent studies, 5–7 whose results have shown that estrogen replacement therapy (ERT) can protect against tooth loss and reduce the risk of edentulism, demonstrate this hypothesis. Jacobs et al 8 reported that ERT had a positive effect on the oral bone mass as well as the lumbar spine. Civitelli et al 9 concluded in their randomized trial that hormone/ERT produced significant improvement in oral bone mass.
It has been widely recognized that tooth loss among older women is influenced by environmental factors such as daily use of sugar-containing drinks, frequency of tooth brushing, or tobacco use. We first reported that both tooth loss and oral bone loss may be in part influenced by Pvu II and Xba I polymorphisms of the estrogen receptor (ER) gene in Japanese postmenopausal women. 10 It is likely that ER gene polymorphisms may contribute to tooth loss and oral bone loss because some reports support a beneficial effect of ERT on tooth retention 5–7 and improved oral bone. 8,9 One of the possible pathways relating ER genotypes with tooth loss and oral bone loss is that general skeletal bone loss regulated by ER genotypes may contribute to tooth loss and oral bone loss. Several studies have indicated the associations between postcranial bone mineral density (BMD) and oral bone mass or BMD 11–20 and between postcranial BMD and tooth loss. 21–25 However, little is known as to whether this pathway relating ER genotypes with tooth loss and oral bone loss is acceptable because there has been no information about the relationship between ER genotypes, tooth loss, oral bone loss, and postcranial BMD in the same participants.
Krall et al 26 suggests that intake levels of calcium and vitamin D aimed at preventing osteoporosis also have a beneficial effect on tooth retention. A recent report of the Veterans Administration Dental Longitudinal Study suggested that Apa I and Taq I polymorphisms of the VDR gene may be associated with periodontal progression and tooth loss in Caucasian men, 27 but there was no evidence about the association of VDR gene polymorphism with tooth loss in women.
The aims of our study were, therefore, to clarify the relationship between ER genotypes, tooth loss, oral bone loss, and postcranial BMD and to investigate whether VDR gene polymorphism may also contribute to tooth loss and oral bone loss in Japanese postmenopausal women.