Compensatory bone formation in young and old rats during tooth movement.

The aim of this study was to investigate compensatory lingual alveolar bone formation during tooth movement in young and old rats, using the vital bone marker tetracycline. Wistar male rats were separated into the following groups: 13-week-old rats without appliances (13C: control, n = 5), 60-week-old rats without appliances (60C: control, n = 5), 13-week-old rats with appliances (13E: experimental, n = 10), and 60-week-old rats with appliances (60E: experimental, n = 10). The upper first molars of the 13E and 60E groups were moved lingually using fixed appliances. On the third day of tooth movement, tetracycline (TC) was intra-peritoneally injected in all animals including the controls. On the 21st day of tooth movement, the animals were killed and unfixed, and undecalcified, 5-microm frozen frontal sections of the rat first molar areas in both control and experimental groups were examined under light and fluorescent microscopes. In the 13C group without tooth movement, tetracycline labelling lines were obvious in the alveolar crest, apical areas, and interradicular septum, indicating vertical alveolar bone growth. However, in the 60C control group, tetracycline labelling was almost undetectable throughout the alveolar bone. Although the lingual alveolar crest was resorbed from the periodontal side after lingual tooth movement, the sharp, bright labelling lines were still present from the crest to the lingual periosteal alveolar bone in the 13E group. In the 60E group the lines appeared in the lingual periosteal alveolar bone containing the crest, indicating considerable new bone formation. The results indicate that compensatory bone formation occurs in the alveolar crest area and, consequently, alveolar bone height is maintained, even in aged rats.

The reconstruction of bilateral clefts using endosseous implants after bone grafting.

This article presents the orthodontic reconstruction of an adult bilateral cleft patient with a severe Class III malocclusion in which endosseous implants were inserted after secondary alveolar bone grafting. The patient was a 21-year-old Japanese male whose lateral incisors were congenitally missing and whose premaxilla was inclined lingually. The occlusion was classified as Angle Class III with an overjet of -8 mm. Orthodontic alignment was initiated to correct the position of the maxillary incisors before bone grafting. After the anterior occlusal relationship was corrected, bilateral alveolar clefts were reconstructed by bone grafting with autogenous particulate marrow and cancellous bone harvested from the iliac crest. ITI-SLA fixtures (Institute Straumann, Waldenburg, Switzerland) (length, 10 mm; diameter, 4.1 mm) were placed into the grafted bone for prosthetic restoration of the missing lateral incisors. The results illustrate that this protocol can be expected to provide an acceptable occlusion and good dentoalveolar stability in adult cleft patients.