Kurol J
Swed Dent J Suppl. 1984;21:1-67.
The aims of this thesis were to estimate the prevalence and familial tendencies of infraocclusion of primary molars and analyse the effect of extraction on occlusal development, and to characterise histologically the ankylosis in infraoccluded primary molars and recommend guidelines for treatment. The thesis is based on five investigations. In the prevalence and familial studies, 1059 children and 138 first-degree sibs were investigated. The three longitudinal clinical studies comprised 215 primary molars in infraocclusion and the children were subjected to clinical and radiographic examination and analysis of model casts every six months. The histological study comprised 62 teeth in infraocclusion and 40 in normal positions. In addition, bone biopsies were analysed histologically and by enzyme histochemical methods. The prevalence of infraocclusion of primary molars was found to be age-related and was significantly higher in sibs than in the studied population, which indicates a familial tendency. Infraoccluded primary molars with a successor present generally exfoliated normally. The permanent successors usually erupted six months later than on the normal contralateral side. Extraction of primary molars in infraocclusion meant definite space loss in some cases. With aplasia of the successor, the infraoccluded tooth did not exfoliate within the normal time range and the root resorption was found to be very slow, especially after 12-13 years of age. Very few of the previously reported negative effects of non-treatment of primary molars in infraocclusion on exfoliation, eruption and occlusal development could be confirmed in this study. Most infraoccluded primary molars were ankylosed histologically. No differences were found in the bone biopsies from the infraoccluded and control group. The results indicate that ankylosis in infraoccluded primary molars is not a static condition but part of a remodelling process following normal resorption of the roots. The general treatment policy should be to wait for normal exfoliation of infraoccluded primary molars to take place if the permanent successor is present and in cases with aplasia consider the aplasia per se, the degree of primary root resorption and the risk of progression of the infraocclusion.
本论文的目的是评估乳牙下沉的患病率及家族倾向，分析拔牙对咬合发育的影响，从组织学角度描述下沉乳牙的粘连情况，并提出治疗指南。本论文基于五项调查研究。在患病率及家族研究中，对1059名儿童和138名一级亲属进行了调查。三项纵向临床研究涉及215颗下沉乳牙，每六个月对这些儿童进行临床和影像学检查，并分析模型石膏。组织学研究包括62颗下沉牙齿和40颗正常位置的牙齿。此外，对骨活检进行了组织学和酶组织化学分析。发现乳牙下沉的患病率与年龄相关，在亲属中的患病率明显高于研究人群，这表明存在家族倾向。有恒牙胚的下沉乳牙通常正常脱落。恒牙胚通常比正常对侧晚六个月萌出。下沉乳牙的拔除在某些情况下意味着明确的间隙丧失。如果恒牙胚发育不全，下沉的牙齿在正常时间范围内不会脱落，并且牙根吸收非常缓慢，尤其是在12 - 13岁之后。本研究几乎无法证实之前报道的乳牙下沉不治疗对脱落、萌出和咬合发育的负面影响。大多数下沉乳牙在组织学上发生了粘连。下沉组和对照组的骨活检未发现差异。结果表明，下沉乳牙的粘连不是一种静态状况，而是牙根正常吸收后重塑过程的一部分。一般治疗策略是，如果有恒牙胚，等待下沉乳牙正常脱落；对于恒牙胚发育不全的情况，要考虑发育不全本身、乳牙牙根吸收程度以及下沉进展的风险。
