Longitudinal changes in maxillary alveolar bone after molar extraction in young and adult male rats

To study the changes in maxillary alveolar bone dimensions after unilateral molar extraction, considering the ipsilateral versus contralateral alveolar process cross-sectional area (CSA) and the height of the alveolar bone crest in relation to age.

A total of 28 4-week-old (young) and 28 26-week-old (adult) male rats were randomly assigned to control (n = 12) and experimental (n = 16) groups at each age. The experimental groups underwent unilateral upper right molar extraction, and all rats were euthanized after 12 weeks. The skulls were longitudinally scanned immediately after extraction and at 4, 8, and 12 weeks after extraction using in vivo micro-CT. The CSA and alveolar bone height were measured using five standardised transverse sections of the maxillary first molars.

The CSA and alveolar bone height in the young and adult control rats constantly increased, although to a lesser extent in the adults. Molar extraction caused a substantial decrease in the CSA and alveolar ridge heights in the edentulous region in young and adult rats, whereas those contralateral to the extraction side increased in the young and adult rats similar to that in the controls. The reduction in the CSA 12 weeks after extraction was more extensive in young than in adult rats.

The unilateral loss of maxillary molars reduced alveolar bone mass, as measured using the changes in the alveolar process CSA and alveolar process heights on the edentulous sides. These measures increased contralateral to the extraction and control sides, with some differences related to age and function.