Bone remodeling in maxilla, mandible, and femur of young dogs.

Bone remodeling in the jaw is essential for metabolic needs, mechanical demands and for growth of the skeleton. Currently, there is no information on remodeling in the jaw of young dogs. Four approximately 5-month-old male dogs were given a pair of calcein bone labels. After killing, bone sections were obtained from the maxilla, mandible, and femur. The jaw specimens were obtained from regions associated with erupting permanent teeth. Undecalcified specimens were prepared for examination by histomorphometric methods to evaluate mineral apposition rate (microm/d), mineralizing surface/bone surface (%), and bone formation rate (BFR, %/yr) in the bone supporting erupting teeth and in the femurs. Only intracortical secondary osteonal remodeling units were measured. There were significant (P < 0.05) differences in the BFR for the three sites examined, with the highest BFR (72%/yr) being in the femur. The mandible had a BFR twofold greater than the maxilla (51%/yr vs. 25.5%/yr). The rate of turnover in the jaw and femur of young dogs is distinct from a similar comparison between the jaw and appendicular skeleton of adult ( approximately 1 yr old) dogs. Although BFR decreases with age in the femur, it remains elevated in the jaws.