Scientists in the US have discovered a happy side-effect of hormone replacement therapy for post-menopausal women. Oestrogen, when taken in association with calcium and vitamin D, can help prevent tooth loss.
A daily dose of oestrogen, calcium and the vitamin was found to strengthen the jaw, potentially reducing the risk of tooth loss. Women who had regular check-ups at the dentist but took only calcium and vitamin D also improved jaw mass and density, though to a significantly lesser extent than those who received oestrogen.
The study was conducted at Washington University School of Medicine in St Louis and will appear in the 24 June issue of Archives of Internal Medicine.
"Tooth loss is fairly prevalent in the ageing population, particularly in people over 65, about 40 per cent of whom have lost all their teeth," said Roberto Civitelli, professor of medicine and of cell biology and physiology, and leader of the research team.
"The risk is higher for women aged 65 or older, and continues to increase the longer a women has been post-menopausal. There are so many people with dentures that I think this really requires more attention, particularly as the population ages."
Estrogen already has been shown to help reverse the effects of osteoporosis and to improve bone density in post-menopausal women, but Civitelli's team wanted to find out whether these benefits elsewhere in the skeleton also translated to the facial bones, particularly the alveolar bone, which surrounds the teeth. Bone loss in these areas also increases with age and is believed to be a risk factor for tooth loss when combined with periodontal disease.
The team randomly assigned 135 post-menopausal women with no evidence of periodontal disease into one of two groups. One group took an oestrogen tablet once a day while the second group took a placebo. All women received daily calcium and vitamin D supplements as well as regular dental care and yearly cleanings. All participants continued treatment for three years.
Women who received hormone replacement therapy had a significantly greater increase in alveolar bone mass (1.84 per cent) compared with those who took the placebo (0.95 per cent gain).
Researchers also measured changes in bone mineral density of the lumbar spine and the left femur, the leg bone attached to the hip. Women taking oestrogen had a significant increase in bone mineral density in the femur (3.59 per cent), whereas their placebo counterparts did not (0.22 per cent). Women in the oestrogen group gained 1.01 percent bone mineral density in the lumbar spine compared with 0.17 per cent gain in the placebo group, though these changes were not statistically significant.
The effects of oestrogen on jawbone density seemed to reflect an overall effect on the skeleton, since improvements in the facial bones of women on estrogen correlated with increases in the lumbar spine and femur and there were no such correlations in women taking placebos.
"This means that perhaps you can prevent bone erosion in the jaw with calcium and vitamin D, but those supplements are not sufficient to restore bone loss," said Civitelli. "However, oestrogen does appear to restore bone throughout the body."
Civitelli's team now plans to examine whether oestrogen alternatives provide similarly beneficial results. They also are working on new methods to test jawbone density to try to identify women at risk for overall skeletal loss and osteoporosis.