Histopathology of the Hematopoietic Bone Marrow in the Temporomandibular Joint of Rats Subjected to Undernutrition and to Mandibular Condyle Fracture

Abstract

Undernutrition can cause important functional and morphological alterations in the hematopoietic bone  marrow (HBM). Degeneration of the HBM in malnourished individuals has been observed in the long  bones, but none has been described in the cranial bones. Mandibular condyle fracture can lead to determine  nutritional effects due to the high catabolism needed for the bone healing added to the difficulties of mastication.  The aim of this study is to describe the histological aspect of HBM in the fractured mandibular  condyle and in the temporal bone of malnourished rats. Thirty adult rats suffered unilateral mandibular  condyle fracture and were divided into well-nourished (FG) and malnourished (MG) groups. In the MG the  animals received a hypoproteic diet during the experiment. Histological sections of the temporomandibular  joint were stained to visualize and quantify the HBM in this region at 24h, and 7, 15, 30, and 90 days postfracture.  At 24 hours, FG and MG showed hypocellularity and ischemic degeneration in the mandibular  condyle and in the temporal bone. At 7 days, FG exhibited high cellularity in comparison with MG in the  condyle; the temporal bone of both groups presented hypocellularity and degeneration. At 30 and 90 days,  FG exhibited similar characteristics to those of the control; MG maintained the degeneration level mainly  in the temporal bone. Malnutrition prejudices the regeneration of the HBM during a fracture healing in the  temporomandibular joint. This fact contributes to a complete modification of the bone structure as well as  to an impairment of the healing process.