Hemisection of primary molars to support orthodontic tooth movement

Objectives: The absence of the second premolar is one of the most common forms of aplasia in the permanent dentition, but is orthodontically difficult to handle. The normal extraction of the decidious tooth results in a vertically and bucco-lingualy bone loss which makes orthodontic tooth movement very complicated. The hemisection of a primary molar during the orthodontic tooth movement prevents the loss of the alveolar bone. The remaining distal part of the hemisectioned tooth reinforces the anchorage of the first permanent molar as an additional benefit for the orthodontic treatment. The aim of our study was to proof the suitability of the hemisection in the primary dentition. Methods: In five cases primary second molars were anesthesized and rubber dam was applicated. The pulp was extirpated and the distal canal was shaped. After that the root canal was filled with a temporary sealer (calciumhydroxide) and the cavity was provided with a temporary filling. Than the crown was separated vertically with a diamond burr, the two parts were divided using a lever and the mesial part of the tooth was extracted. Every eight weeks the root canal filling was changed. After the eruption of the second permanent molar the distal part of the deciduous molar was extracted, so that the permanent molars could be integrated. Results: During the observation time of four to six month all teeth were symptom free; there were no complications like pain, fistula, swelling or inflammation, so that the orthodontical treatment could go on regularly. Conclusions: More clinical studies are necessary to proof our results, but hemisection of primary second molars seems to be a useful procedure in reducing negative effects of aplasia referring to orthodontic treatment.