Objective To analyze the risk factors of root caries.Methods With randomly stratified cluster sampling method,we selected 600 elderly in Tangshan city and performed oral examination.Data was analyzed by Logistic regression analysis.Results Gingival recession,age,oral calculus index,false tooth restoration were the risk factors of root caries.The vertical brushing tooth method and using fluoride toothpaste were the protective factors.Conclusion Gingival recession,age,oral calculus index(CI-S),false tooth restoration were the major risk factors of root caries.

Objective To observe the effects of individual prehabilitation on the functional outcome six weeks after total knee arthroplas-ty (TKA). Methods The patients undergoing TKA from March, 2013 to August, 2015 were randomly divided into prehabilitation group (n=30) and control group (n=29). The prehabilitation group received individual rehabilitation since enrolled in the study. The control group re-ceived no prehabilitation. All the patients received regular pre-surgical education, surgery and post-surgical rehabilitation. Both groups were evaluated with Numerical Rating Scale (NRS) of pain, active range of motion (AROM), Manual Muscle Test (MMT), fall index, TimedUp and Go(TUG), and Hospital for Special Surgery-Knee Scale (HSS-KS). Results The scores of NRS reduced six weeks after TKA (t>2.342, P<0.05) in both groups, and was lower in the prehabilitation group than in the control group before and six weeks after TKA (t>2.827, P<0.01). There was no significant difference in AROM of knee flexion when enrolling and before TKA in both groups (t<0.648, P>0.05), and it increased in the control group six weeks after TKA (t>3.555, P<0.01), and no increasement was found in the prehabilitation group (t<1.608, P>0.05);the AROM of knee extension increased before TKA in the control group (Z=-2.257, P=0.024), and no increasement was found in the prehabilitation group (Z=0, P=1.000), and it decreased six weeks after TKA in both groups (Z>2.247, P<0.05). The muscle strength of trunk extention and flexion enhanced before TKA in the prehabilitation group (t>2.387, P<0.05), and no change was found in the control group (t<0.940, P>0.05). The muscle strength of trunk extensor and the upside of rectus abdominis showed no statistical difference between two groups six weeks after TKA (t<1.656, P>0.05), the muscle strength of the downside of rectus abdominis and external oblique was more in the prehabilitation group than in the control group (t=2.585, P=0.013). There was no significant difference in the fall index be-fore TKA (t<0.350, P>0.05), and it was lower in the prehabilitation group than in the control group six weeks after TKA (t=-2.837, P=0.007). The time of TUG shortened before TKA in the prehabilitation group (t=3.554, P=0.002), and it prolonged in the control group (t=-4.507, P<0.001), there was no significant difference in it between two groups six weeks after TKA (t=-0.497, P=0.622). The score of HSS-KS increased before TKA (t=-2.621, P=0.015) in the prehabilitation group, and no increasement was found in the control group (t=2.073, P=0.053), and they were higher in the prehabilitation group than in the control group before and six weeks after TKA (t>2.092, P<0.05). Conclusion Individual prehabilitation could reduce pain, and improve the trunk muscles, the ability of walking and the function of the knee before and six weeks after TKA.