Research vegarding a risk factor that the vestration of corona dentis exert to periodont diseases

这项调查的目的是找出是否有任何关系龈下缘的修复和牙周病。本研究样本包括170名在大学牙科医院牙科预防科门诊就诊的受试者。测量的参数包括口腔卫生习惯（问卷调查）、修复体边缘和牙周组织的位置、年龄和性别。以齿面为测量单位进行分析。卡方检验显示，修复体延伸到龈下边缘的受试者与修复体延伸到龈上边缘和没有修复体的受试者相比，有统计学意义的出血水平（BOP）和4mm或更多的探探深度。当控制混杂因素后进行逻辑回归分析时，得到相同的结果。结果提示，牙体延伸至龈下缘可能是牙周病的危险因素。很明显，清洁牙齿表面的龈下边缘对受试者来说是困难的，尽管事实上许多参加调查的人进行了定期的口腔护理。因此，在修复牙齿时，避免预备龈下边缘是很重要的。虽然修复的主要目的是防止龋齿，但我们应该意识到，只要有可能，我们可以通过不将特定的修复扩展到龈下边缘来预防牙周病。

The aim of this survey was to find out whether there is any relationship between the subgingival margin of a restoration and periodontal diseases.The study sample comprised 170 subjects attending the ambulatory clinic of the Department of Preventive Dentistry, university dental hospital. The parameters measu red were oral hygiene habits using a questionnaire, the position of the margin of the restorations and periodontium, age and sex. Analysis was carriedout using a tooth surface as the unit of measurement. Chi squared test showed that subjectswith restorations extending to subgingival margin had statistically significant levels of bleeding on probing (BOP) and 4mm or more probing depth compared to those who with restorations extending to supragingival margin and no restorations. When logistic regression analysis was performed after controlling for confounding factors the same results were obtained.The results suggest that the existence of restorations extending to subgingival margin may be a possible risk factor for periodontal diseases. It is apparent that cleaning of subgingival margin of a toothsurface is difficult for subjects in spite of the fact that many of who attended the survey practised regular oral care.As such, it is important to avoid preparation of subgingival margins in restoring teeth. Although the primary intention of a restoration is to prevent dental caries, we should realize that we can prevent periodontal diseases at the same time by not extending a particular restoration to the subgingival margin whenever possible.