Abstract
ObjectiveThe objective of this study was to assess the histological alterations that occurred in the periodontal area of rat molars submitted to induced tooth movement (ITM) right after an intentional trauma (subluxation). MethodsForty adult male Wistar rats (Rattus norvegicus albinus) were selected. The animals were divided into eight groups (n = 5), according to the combination of variables: Group 1 - control (neither trauma nor ITM); Group 2 - ITM; Groups 3, 4, 5 and 6 - dentoalveolar trauma groups corresponding, respectively, to 1, 3, 8 and 10 days after trauma; Groups 7 and 8 - the animals' molars were subjected to a 900 cN impact and, one and three days after the trauma event, tooth movement was induced. The rats' maxillary first molars were mesially moved during seven days with a closed coil (50 cN). After the experimental period of each group, the animals were sacrificed by anesthetic overdose and the right maxillas were removed and processed for histological analysis under light microscopy. ResultsIn the animals of group 3, 4, 5 and 6, the histological alterations were not very significant. Consequently, the effect of induced tooth movement right after a subluxation event (groups 7 and 8) was very similar to those described for Group 2. ConclusionThere was no difference in the quality of periodontal repair when ITM was applied to teeth that had suffered a subluxation trauma.
Highlights
In the groups of animals submitted to induced tooth movement (Groups 2, 7 and 8), a device similar to the model proposed by Heller and Nanda[17] (Fig 1) composed of a closed section coil (Morelli, Sorocaba, São Paulo, Brazil - code 35.20.061) and two 0.25 mm wire ligatures (Morelli, Sorocaba, São Paulo, Brazil code 55.01.210) were placed on the right maxillary first molar in order to promote molar mesial movement by applying controlled force of 50 cN, measured with the aid of a tensiometer (Zeusan Exporting Ltda Campinas, São Paulo, Brazil)
In the animals submitted to induced tooth movement (Group 2), the root surface was intact throughout the entire extension of its mesial portion
The characteristics of tissues under induced tooth movement in normal rats have been widely studied and the morphological features described were similar to those seen in human teeth.[19,20,21]
Summary
The objective of this study was to assess the histological alterations that occurred in the periodontal area of rat molars submitted to induced tooth movement (ITM) right after an intentional trauma (subluxation). In opposition to the state of the art with regard to movement of traumatized teeth, other authors suggest that movement of luxated teeth may relieve the areas of compression in the periodontium and pulp, and, facilitate the repair of these tissues.[3,12] As a secondary consideration, Mine et al[3] inferred that calculated mechanical stimuli, such as orthodontic forces, would be important so that after injury, the process of migration and proliferation of periodontal ligament cells would occur, preventing the occurrence of ankylosis and inflammatory root resorption. This study assessed the histological alterations that occurred in the periodontal tissue of rat molars submitted to induced tooth movement (ITM) right after an intentional trauma (subluxation)
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