ABSTRACT
Impaction of third molars can be associated with a number of sequelae, each requiring a different type of treatment. The purpose of this study was to assess the changes in the position of lower third molars following extraction and non-extraction orthodontic treatments. Pre- and post-treatment panoramic radiographs of 26 class I malocclusion patients [4 male and 22 female] who were treated on a non-extraction basis were compared with those of 30 class I malocclusion patients [5 male and 25 female] who received orthodontic treatment following the extraction of all first premolars. In each group, the lower third molar angulations and their distance from the lower border of the mandible were assessed. Paired r-tests and independent /-tests detected significant changes in the position of the lower third molars in the extraction group. Both the left and right molars became more upright and their distance from the lower border of the mandible increased. Similar changes were only seen in the position of the right mandibular third molars in the non-extraction group. Tooth extractions can bring about favorable changes in the position of mandibular third molars and possibly reduce their incidence of impaction
ABSTRACT
Mandibular deficiency is one of the most common malocclusions that is treated with functional appliances during growth periods. The aim of this study was to evaluate the histologic changes of the single local injection of rBMP2 in combination with bite jumper therapy in a rabbit model TMJ. Eighteen 8-week old Albino New Zealand white male rabbits were divided into three groups: The first group served as control and in the second and third groups rBMP2 and normal saline were injected respectively. The second and third groups had bite jumper appliance. After 8-weeks of bite jumper therapy, in the second group 12.5 microgr rBMP2 powder plus 2.5cc normal saline and in the third group only 2.5 cc normal saline was injected in the TMJs on both sides. After 16-weeks of treatment, the animals were sacrificed and the joints were examined histologically. The rBMP2 group showed greater cartilage cells and maximum condylar cartilage thickness [in the form of cartilage hyperplasia] than control and normal saline groups. The control group had the lowest disc deformity histologically and the rBMP2 group showed lower disc deformity than normal saline group. rBMP2 is able to accelerate condylar cartilage growth in the form of cartilage hyperplasia