The bilaminar zone (BZ) in the human temporomandibular joint (TMJ) of toothed adults (GI) and toothless, elderly humans (GII) were analysed using light and scanning electron microscopy (SEM). In both groups the BZ consists of an upper and a lower stratum of connective tissue separated by a vascularized middle region. The superior stratum contains bundles of collagen fibres disposed in different directions. The fibres are fairly thick and transversely oriented immediately posterior to the TMJ disc. The initial part of the inferior stratum contains curved bundles of collagen fibres oriented anterio-posteriorly. From the middle to the posterior part of the inferior stratum, the fibres are right-aligned in GI and clearly sinuous in nature in GII. In both groups, the middle and posterior portions of the middle region are distinguished by the presence of vessels and vascular spaces. Loosely arranged connective and adipose tissues are also evident. The vascular spaces are wider in GII than in GI. The predominance of type I collagen fibres is clear in all regions of the BZ in both groups. The elastic fibres lie parallel to the collagen fibres in both groups and they are thicker and more abundant in GI, apparently decreasing in GII.
Twelve adult male Wistar rats (220 g average weight) were divided in 3 experimental groups: GI-15. GII-30 and GIII-60 days, after mandibular molar extraction, with three experimental animals and one control per group. Qualitatively, ultrastructural changes of protein filaments from myofibrils of these muscles and ipsilateral to the extractions were observed. Ultrastructure asymmetry and disorganization of Z line and I band, in the experimental group GII, of Medial Pterigoid muscle (MPT) were observed. The temporomandibular dysfunction, stimulated by the unilateral extractions of mandibular molars in rats may lead to modifications in the Z line and I band, which showed to be sensitive to this dysfunction. Changes in the MPT muscle, probably related to its own functional characteristics and major participation in the dynamics of mastication, compared to Masseter were also observed. However, the muscular fibres seem to adapt to the new conditions along the experiment.
The studies about bone resorption contributed greatly to the advancement of rehabilitation with dental implants and Buccomaxillo facial Surgery and Traumatology. This phenomenon leads to a more superficial localization of the mandibular canal in relation to the alveolar ridge when teeth are lost, limiting and hindering the installation Bone tissue, of implants, as well as other surgical procedures. This anatomical study aimed to analyze and interpret the distances from the mandibular canal to the alveolar ridge, in groups of dentate individuals and toothless, comparing them statistically, so 20 adult male cadavers divided into two groups, namely group A, formed by 10 dentate and group B, consisting of 10 toothless individuals. All their teeth were dissected and then, were checked the measurements of the distances between the roof of the mandibular canal and the alveolar ridge. The averages found were enlightening to say that bone resorption has consequences for treatment and surgery for dental implants, due to the decreasing bone support for the implantation and other surgical procedures, increasing the risk of injury to the inferior alveolar neurovascular bundle.
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