Compensatory bone formation in young and old rats during tooth movement

Abstract

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.

Factors related to the rate of orthodontically induced tooth movement

“…However, when a lingual molar movement was performed in young and old rats, the compensatory alveolar bone apposition was similar in both groups. 18 The age effect on orthodontic movement in rats was studied by Ren et al, 19 who reported faster mesiodistal initial tooth movement in juvenile rats than in adult rats. Once tooth movement had reached the linear phase, the rate of tooth movement did not differ between the 2 groups.…”

Novel device for application of continuous mechanical tensile strain to mammalian cells

“…Cells in the PDL are subjected to continuous mechanical strain and are forced to adapt to the new environment by synthesis and secretion of several cytokines and growth factors (Arai et al, 2010; Baba et al, 2011; Saito et al, 1991; Tsuge et al, 2016). As a result, reconstruction of the PDL and alveolar bone occur both in the tension and compression zones of the PDL (Nakamura et al, 2003; Shimpo et al, 2003; Takahashi et al, 2003, 2006). However, the detailed mechanisms of the cellular response in reconstruction of the PDL and alveolar bone have not been clarified.…”

Three-dimensional evaluation of upper anterior alveolar bone dehiscence after incisor retraction and intrusion in adult patients with bimaxillary protrusion malocclusion

“…However, Decker and Chen (2009) demonstrated good upper alveolar bone adaptation after 32 years of follow-up by case report. Shimpo et al (2003) thought that lingual alveolar bone height was maintained due to bone formation during moving first molar lingually in rats. Further research is necessary for alveolar bone dehiscence involving large incisor retraction and intrusion in adult patients with maximum anchorage.…”