RESUMO
Objective To study the adverse effects on periodontal tissues caused by crownless roots in elderly people with osteoporosis. Methods Totally 60 12?week SD rats(30 male and 30 female)were randomly divided into the control group(10 male and 10 female sham?operated rats)and the osteoporosis group(20 male and 20 female castrated rats). After 12 weeks,the bone mineral density of right femora was measured by dual energy X?ray for all rats to confirm osteoporosis. The right molar crown was pinched off with haemostatic forceps and the molar root was retained. The 10 con?trol rats and the 20 experimental rats were sacrificed respectively at postoperative 2 and 4 weeks. The periodontal tissues of right molar were sampled and the morphology of the parodontium and the alveolar bone was observed by haematoxylin and eosin(HE)staining and the expression of tumour necrosis factor?alpha(TNF?α)and inducible nitric oxide synthase?2(NOS2)was detected by immunohistochemical staining and real time fluores?cent quantitative PCR(qRT?PCR). Results The HE slices indicated that the periodontal tissues in the osteoporosis group were significantly im?paired compared to the control group as the structure of parodontium loosened. Bone impairment aggravated over time. TNF?αstaining showed as a few claybank spots on the parodontium in the control group,while the staining colour was darkened in the osteoporosis group. The expression of TNF?αmRNA was significantly higher in the osteoporosis group than in the control group(P0.05). Conclusion The crownless roots in rats with os?teoporosis cause adverse effects of periodontal tissues as the roots accelerate absorption of the surrounding alveolar tissues. It is indicated that crown?less roots in elderly people with osteoporosis should be removed as soon as possible.