ALVEOLAR BONE TURNOVER IN MALE-RATS - SITE-SPECIFIC AND AGE-SPECIFIC CHANGES

Background: This study compares alveolar bone turnover adjacent to dis tally drifting maxillary first molar teeth of rapidly and slowly growi ng rats. Methods: Two groups of forty male rats (1 and 3 months) were sacrificed, Sera were analyzed for acid (AcP), alkaline (AlkP), and ta rtrate-resistant acid phosphatase (TRAP), Bone histomorphometry was do ne on parasagittal sections of maxillary molars, Molar drift was quant ified cephalometrically. Results: Distal surfaces contained more osteo clasts and higher osteoclast percents than mesials at both ages (P<0.0 01). There were also more osteoclasts on the distals of the older rats as compared to the young (P<0.001). Osteoblast percents were higher ( P<0.001) in the older rats on both surfaces. Mesials had higher double -labeled surface, MAR and BFR than distals in the younger rats (P<0.00 1). The younger rats had higher (P<0.001) AlkP, AcP, and TRAP. There w ere no age-specific differences in rate of molar drift. A model of rat e of molar drift (P<0.0015) containing bone formation measures account s for 54.9% of the variability, Conclusions: We conclude that the bone turnover dynamics adjacent to maxillary first molars represent predom inantly remodeling on the distal in both groups and modeling on the me sial only in the young rats, that distal molar tooth drift reflects al veolar bone turnover, and that alveolar bone manifests the marked redu ction in bone cell activity that occurs in the rat skeleton after 8 we eks but that this reduction is compensated by recruitment or maintenan ce of more bone cells at these sites. (C) 1995 Wiley-Liss, Inc.