Influence of masticatory hypofunction on the alveolar bone and the molar periodontal ligament space in the rat maxilla

Abstract

Previous studies have established that complete absence of masticatory function results in a narrower alveolar process and periodontal ligament (PDL). The aim of our study was to investigate, for the first time, both the alveolar process and the PDL in masticatory hypofunction. Twenty-six rats, 3 wk of age, were randomly assigned to either a hard- or a soft-diet group (n = 13 each group). The rats were killed after 6 wk and their skulls were scanned using micro-computed tomography (micro-CT). We measured the cross-sectional width of the space occupied by the PDL, as well as the cross-sectional alveolar socket surface (AS) and the cross-sectional root surface (RS). We also measured the width of the alveolar process. The alveolar process was narrower, the PDL width was thinner, and the AS was smaller in rats fed a soft diet compared with rats fed a hard diet. The PDL width was correlated to the alveolar process width and the AS. The narrower alveolar process found in rats fed a soft diet is the result of alterations to both the alveolar bone and the PDL. The correlation between them provides evidence that a reduction of occlusal loading induces a simultaneous response in both tissues.

Effects of decreased occlusal loading during growth on the mandibular bone characteristics

“…In rats with reduced masticatory function by a soft diet, the alveolar bone of the mandible, was thinner [28,29] and taller [28] and its bone density [28][29][30] was lower. Balazs et al also indicated differences in the alveolar process and evidence that a reduction of occlusal loading induces a simultaneous response in both tissues [31]. This is in line with the increased mineralization below the teeth found in the current study.…”

Influence of differences in the hardness and calcium content of diets on the growth of craniofacial bone in rats

“…Two measures were replicated to assess method error. 15 Two replicated cases have been described as the number required to acquire an estimate of method error. Random error was calculated according to Dahlberg's formula 16 :…”

Impact of hypofunctional occlusion on upper and lower molars after cessation of root development in adult mice

“…Another advantage of mice is that they have the same number of roots as humans, 3 roots in the upper first and second molars (M 1 , M 2 ), and 2 roots in the lower first and second molars (M1, M2) making them a better and simpler model when compared to rats which have more roots; upper 1 st molar (M 1 ) has 5 roots, upper 2 nd molar (M 2 ) has 4 roots, upper 3 rd molar (M 3 ) has 3 roots and lower 1 st molar (M1) has 3 roots (19,23). These differences in root number may influence the response of the tooth generally and the roots specifically to hypofunctional occlusion.…”