Morphological changes in the mandible of male mice associated with aging and biomechanical stimulus.
Degenerative changes in the temporomandibular joint (TMJ) associated with aging can affect mandibular shape and reduce growth potential when stimulated by functional appliance therapy. This study was designed to evaluate the morphological changes in the mandibles of male mice associated with aging and biomechanical stimulus. Every 3 days over the course of 1 month, the lower incisors were trimmed by 1 mm to induce mandibular advancement (MA) when the animal was feeding. The left mandibles of the 23 experimental and 27 control animals were subsequently dissected, and digital images were obtained to analyze nine linear/angular measurements. Because mandibular morphology depends on the maintenance of condylar cartilage, the surfaces of the condylar cartilage and the ascending ramus of the mandible were also analyzed by scanning electron microscopy (SEM). The linear measurements of the mandible showed changes according to age in the control group and a growth response in the mandibular condyle in 7- and 15-month-old mice after MA. Moreover, SEM analysis revealed depressions in the anterior region of the condylar cartilage and inclined vascular grooves in the ascending ramus in the 7- and 15-month-old experimental mice. Although the growth potential is reduced in mice after 6 months of age, the results showed that continuous growth of the mandible occurs after maturation, except in the condyle, and that biomechanical stimulus of the TMJ of male mice leads to condylar growth. These results suggest that mature and old individuals can favorably respond to maxillary functional orthopedic therapy.
Tagliaro
Maria Luisa
ML
Morphophysiological Sciences Department, Biosciences Faculty, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Prédio 12, Av. Ipiranga, Porto Alegre, RS, Brazil.
De Oliveira
Raquel Mattos
RM
Padilha
Dalva Maria Pereira
DM
Callegari-Jacques
Sidia Maria
SM
Jeckel-Neto
Emílio Antônio
EA
D000375:Aging / Q000502:physiology*; D000818:Animals; D001835:Body Weight; D008297:Male; D008334:Mandible / Q000033:anatomy & histology* / Q000254:growth & development / Q000648:ultrastructure; D019186:Mandibular Advancement / Q000379:methods*; D008335:Mandibular Condyle / Q000648:ultrastructure; D051379:Mice; D008855:Microscopy, Electron, Scanning; D013704:Temporomandibular Joint / Q000033:anatomy & histology* / Q000254:growth & development / Q000648:ultrastructure