Figure 3.

Hyperloading initially activates bone resorption, which in response triggers an increase in mineral apposition and alveolar bone accrual. (A) Quantification of TRAP and ALP activity in alveolar bone in response to hyperloading. Values are normalized to TRAP and ALP levels in an intact dentition. (B–F) TRAP activity and (G–K) ALP activity in alveolar bone in the furcation area at time points indicated. (L) Vital dye double-labeling experiment to evaluate mineral apposition rate (MAR) in alveolar bone in response to hyperloading. (M) In mice with intact dentition, calcein (green) dye was injected first, and 7 d later, AR (red) was injected. Two days after the last injection, tissues were harvested. (N) In hyperloading group 1, calcein was injected 2 d before tooth extraction, and AR was injected on day 7 (postextraction day 5). (O) In hyperloading group 2, calcein was injected on day 7 (postextraction day 5), and AR was injected on day 14 (postextraction day 12). Black arrows indicate the load. Double arrows indicate the distance between labels. (P) Quantification of MARs. (Q) The ratio of bone volume (BV) to total volume (TV) and the absolute TV were calculated and compared. The red line connects the lowest points of two roots. The TV was measured above this line and under the furcation (dotted line area). Scale bars = 50 µm. Values are presented as mean ± SD. *P < 0.05. **P < 0.01. ***P < 0.0001. ab, alveolar bone; ALP, alkaline phosphatase; AR, alizarin red; TE, tooth extraction; TRAP, tartrate-resistant acid phosphatase. This figure is available in color online.