| It is popular to cure deformity and deficiency of jaws with distraction osteogenesis(DO).To increase alveolar ridge with DO is a research hotspot in recent years.At the same time of extending bone,soft tissues produce adaptable response.Temporomandibular joints (TMJS)change with muscles and nerves.Meanwhile,the movement of jaws and oclussion also both make effect on TMJS.There are a great many of articles about TMJS' changes after extending or prolonging jaws,but few about alveolar ridge augmentation.This research aims to study the changes of TMJS and masticatory muscles after alveolar ridge augmentation.The TiNi-shape memory alloy(SMA) distractor to increase alveolar ridge is pint-sized,easy-operated and full-insited,so it has wide foreground to be used in clinic.1.The establishment of animal model to elevate alveolarridge by distraction osteogenesis5 adult mongrel dogs were selected. All dogs' premolars and the first molar were extracted,then the alveorlar ridge were repaired and mucosa were sutured closely. After 1 month, box-shaped oesteotomies of the alveolar bone were carried out and TiNi-SMA(shape memory alloy)distractors wereburied .The bone height was measured before and after the operation,everyday of the first week,and one month after distrction .The radiographs were taken on the day of operation ,and 1.5 week after the operation. Result:The transport segments were lifed up 3-4.5mm immediately after the distractors inserted and the maximal height was 7.5-11.5mm after 3-5 days of operation.One month after distraction ,no bone resorption was found and the radiographs showed the regeneration bone in distraction gap.Conclusion: It is a good animal model to elevate alveolar ridge with canine2. Changes of TMJS after alveolar ridge augmentation18 dogs weighing over 20 kg were selected,of which 3 were selected as contrastive animals.The rest were randomly divided into 3 groups. TiNi-SMA was processed to S shape apparatus.Fistly,all dogs' premolars and the first molar were pulled out,then the alveolar ridge were repaired and the mucosa were sutured closely.After one month,the distractor were buried into one side of mandible.Dogs of each group and one contrastive dog were put to death after 1,3,6 months respectively.TMJS of both sides from each group were respectively taken out and observed under optical microscope,scanning electron-microscope(SEM).Results :No abnormal changes were observed in group of 1 month on both sides, hi group of 3 months,on the distraction side, the gel-like substanse became thin but still integrate ,partial collagen fibers of condyle and joint discs arranged mussily.Casually some collagen fibers could be seen to have been destroyed .In group of 6 months,no abnormal changes were seen on both sides.Conclusion: The alveolar ridgeaugmentation could lead to gentle changes of TMJS,but these changes were slight and reversible.3.Changes of masticatory muscles after alveolar ridgeaugmentation18 dogs weighing over 20 kg were selected,of which 3 were selected as contrastive animals.The rest were randomly divided into 3 groups. All dogs' premolars and first molar were pulled out,then we repaired the alverlar ridge and sutured mucosa closely. TiNi-SMA was processed to S shape distractor.After one month,the distraction apparatus were buried into one side of mandible. Dogs of each group and one contrastive dog were put to death after 1,3,6 months respectively.The histological changes of the masseter muscules,temporal muscle,medial pterygoid muscle and lateral ptetygoid muscle were observed.Results: No abnormal changes were abserved in contrastive group.After one month, in experimental side ,the capillary vessel of masseter muscle,temporal muscle and medial pterygoid muscle dialated slightly,partial tissue congested,a few mitochondria swelled. But more histological changes could found in group 3 months.The wrench and deformation of muscular fibers,the dissolution of partial myofibril,the swelling of mitochondria from the masseter muscles and lateral pterygoid muscles could...
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