ABSTRACT
<p><b>OBJECTIVE</b>To examine the changes of the ultrastructures of temporomandibular joint after removal of the emotional stress factors in rats.</p><p><b>METHODS</b>Thirty-two 12-week-old male Wistar rats were divided into two groups randomly, experimental group and control group. Each group was divided into two subgroups according to execution time, 9-week subgroup and 12-week subgroup with eight rats in each subgroup. Chronic unpredictable stress animal model were firstly established in experimental group in the first 6 weeks, then all the stimulation factors removed and breed normally. After 9 weeks, rats in 9-week subgroup were killed. After 12 weeks, rats in 12-week subgroup were killed. All condyles and articular discs were dissected and observed by scanning electron microscope.</p><p><b>RESULTS</b>There was some recovery in condyles and articular discs in experimental group under scanning electron microscope. The gelatum on the surface of condyles increased, collagen fibrils became regular and deep layer collagen fibrils less exposed. There were no such obvious changes on the surface of condyles and articular discs in control group.</p><p><b>CONCLUSIONS</b>The ultrastructure injures of temporomandibular joint in rats induced by emotional stress could be reversed if the stress factors were removed.</p>
Subject(s)
Animals , Male , Rats , Extracellular Matrix , Rats, Wistar , Stress, Psychological , Temporomandibular JointABSTRACT
<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>