| Severe occlusal attrition (SOA) is a common disease in oral clinical work, and is alsoone of the major causes of occlusal disease. As the common prosthodontics method fortreating severe occlusal attrition，the occlusal reconstruction has become a hotspot ofclinical research all over the world. In the traditional concepts, the occlusal verticaldimension (OVD)loss more4mm should be increased2-3mm once, and increased stepby step, when OVD should be increased more than3mm. Our research team havededicated to the study of occlusal reconstruction of SOA for many years. In our clinicalwork, many SOA patients have been treated by one-visit occlusal rehabilitation, with theincrease of OVD more than3mm. All these patients satisfied the treatment results, andnever reported adverse reactions such as occlusion disorder after one-visit occlusalrehabilitation for many years. It conflicts with the traditional treatment concept. Up to now,the research of the SOA treatment by occlusal reconstruction still stay at the stage ofevidence based medicine, lack of sufficient theoretical bases and statistics data to supporthow to choose the method of occlusal reconstruction. Therefore, we need to confirm the feasibility of one-visit occlusal reconstruction for treating SOA, and provide reliableexperimental theoretical basis for clinical treatment.ObjectiveThe present study was to establish SOA rat model, and then treat SOA rat withone-visit occlusal reconstruction. The morphological changes of temporomandibular joint(TMJ) will be observed and analyzed at different stage. It will provide theoretical basisfor the clinical features of SOA and the feasibility of one-visit occlusal reconstruction fortreating SOA.Methods1. The rats were executed to passive mouth opening with different opening distanceswith self-made regulative mouth gag, to investigate the effects of different mouth openingdegree on TMJ morphology and body weight.2. With the help of operating microscope and special bur, the height of rat crownheight were decreased progressively and evenly.The animal model of SOA wasestablished. With the help of HE stain and micro-CT analyzing the variation, wereanalyzed at different time-points.3. With two-step impression technique, the occlusal splints were made, and thenadhered to the surface of the upper molars by resin bonding technology, to establish theanimal model of one-visit occlusal reconstruction for treating SOA. With the help of HEstain and micro-CT analyzing the variation, were analyzed at different time-points.Results1. With the distance of passive mouth-opening at0mm,10mm,15mm,20mm,0.5h perday, the histological morphology of condylar cartilage of the SD rats were changednon-significantly after7days.,but25mm were changed significantly.2. The adaptative remodeling changes can be induced by SOA in rat condyle. Theresults of HE staining showed that the morphology changes, such as disorderedarrangement of cell layer, the obscure dividing lines, homogenous cell-free area, andthickening in middle region of condylar cartilage, can be found at early stage after SOA.At28d, all changes recovered. The results of Micro-CT showed that the remodeling site ofrat’s TMJ focuses on the middle and posterior regions of condyle. The condylarsubchondral bone also showed bone resorption in early stage, and then recovered.3. The adaptative remodeling changes can also be induced by one-visit occlusalreconstruction for treating SOA. The results of HE staining showed that the morphology changes, such as thickening in middle region of condylar cartilage, the obscure dividing lines, homogenouscell-free area, and ossification of cartilage, can be found at early stage after one-visit occlusalreconstruction. At28d, all changes recovered. The results of Micro-CT showed that the remodelingsite of rat’s TMJ focuses on the middle and anterior regions of condyle. The condylar subchondralbone also showed bone resorption in early stage, and then recovered.Conclusion1. Thus, the oral operation of rat should be less than0.5h, with the opening distanceis25mm in follow-up study.2. In the present study, the high-emulational SOA animal model was successfullyestablished.，obvious morphological changes can be found in condylar cartilage andcondylar subchondral bone, and recover with time.3. On this basis, the animal model of one-visit occlusal reconstruction for treatingSOA was also established, obvious morphological changes can be found in condylarcartilage and condylar subchondral bone, and recover with time. |
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