Influence of chronic unpredictable emotional stress on the ultrastructures of temporomandibular joint in rats / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To study the influence of emotional stress on the ultrastructures of temporomandibular joint in rats.</p><p><b>METHODS</b>Sixteen male Wistar rats, aged 12 weeks, were divided into 2 groups randomly, experimental group and control group. Animal model of chronic unpredictable stress was established in the experimental group. After 6 weeks, all rats in both groups were killed and their condyles and articular discs were dissected, taken out and observed by scanning electron microscope.</p><p><b>RESULTS</b>Under scanning electron microscope, the surface gelatum of the condyles in experimental group were cracked, and collagen fibrils in disorder and broke, and deep layer collagen fibrils were exposed. The articular discs' surface gelatum were still integrated, but the gyri dispose were irregular. In control group, there were no such changes in condyles and articular discs.</p><p><b>CONCLUSIONS</b>The long-term emotional chronic unpredictable stress could induce the injuries of temporomandibular joint in rats in ultrastructure level.</p>

Bone density and biomechanics study of alveolar ridge augmentation with titanium nickel shape memory alloy distractor and acellular dermal matrix / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To observe the dynamic changes of bone density and bone strength after alveolar ridge augmentation with Titanium Nickel shake memory alloy (TiNi-SMA) distractor and acellular dermal matrix (ADM).</p><p><b>METHODS</b>Twelve adult healthy male dogs were selected. After the animal model of alveolar atrophy was set up, on one side of mandible, two S-shaped distractors were placed. The diameter of S-shaped distractor was 1 mm and the rebound temperature was 33 degrees C. The ADM was placed on the distraction gap and fixed by the feet of distractors. The other side was placed only with distractors, serving as control side. Six dogs' mandibles were harvested after 1 and 3 months respectively. Dual energy X-ray absorptiometry (DEXA) was used to scan bone density around the distraction gap. Mechanical machine was used to test compression strength and elastic modulus.</p><p><b>RESULTS</b>Months after distraction, the bone density of upper distraction gap, distraction gap and low distraction gap were respectively (0.714 +/- 0.238) g/cm2, (0.512 +/- 0.435) g/cm2 and (0.615 +/- 0.043) g/cm2 on experimental side. The compression strength and elastic modulus were (36.54 +/- 7.32) MPa and (1674.10 +/- 256.43) MPa. All of above were higher than those of control side.</p><p><b>CONCLUSIONS</b>ADM can improve the bone quality, increase bone density and intensity and is an ideal guided bone regeneration(GBR) membrane for alveolar ridge augmentation with TiNi-SMA distractor.</p>

Reconstruction of segmental mandibular defect of canine using titanium-nickel distractor / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To establish a continuous and automatic distraction osteogenesis technique in reconstruction of segmental mandibular defect by using embedded titanium-nickel alloy distractor with characteristics of shape-memory and super-elasticity.</p><p><b>METHODS</b>Adult hybrid canines were used as the animal model. Segmental defects of 1-3 cm in the body of mandible were created by surgical osteotomy. Bi-focal distraction osteogenesis was applied using embedded titanium-nickel distractor designed by the authors. The canines were sacrificed 3 months after the operation and the mandibles were harvested to examine the results of bone regeneration.</p><p><b>RESULTS</b>The histocompatibility of titanium-nickel distractors was good. Distraction osteogenesis was completed automatically and the defects were elementarily restored. Radiological and histological examination showed well bone regeneration in distraction area.</p><p><b>CONCLUSIONS</b>Distraction osteogenesis using embedded self-loading titanium-nickel distractor could be a hopeful and useful technique. It might help to solve the problems of functional mandibular reconstruction in the near future.</p>