The Study Of Fixed Splinting In Patients With Periodontitis

Periodontitis is characterized by loss of connective tissue attachment, periodontal pocket formation and loss of alveolar bone. In advanced stages of periodontal disease, much of the supporting tissue around many teeth has been destroyed. With some teeth, this has occurred to such an extent that they have either spontaneously exfoliated or have been extracted because of exacerbations or discomfort for the patient caused by excessive mobility. In such situation, there is generally a great need not only for cause-related periodontal therapy of high quality but also for relevant prosthetic rehabilitation to restore proper function and aesthetics. However, opinions still differ concerning how much occlusal loading a reduced but healthy periodontium can withstand and what type of prosthetic construction is to be preferred for a good long-range prognosis. The study includes two parts which evaluated the fixed prosthodontics by the clinical and mechanical method separately. The objectives of this study was: 1) to evaluate the periodontal conditions in patients who suffered from chronical periodontitis and the patients' treatment assessment by the questionnaire after the combined periodontal and prosthodontic treatment; and 2)to analyze the stress levels in the teeth, fixed prosthesis and supporting structures in the different reduced bone support with the increase of abutments under the different load direction.Part One The clinical study of fixed splinting in patientswith periodontal diseaseObjective: The aims of this study were: 1) to evaluate periodontal conditions of the abutments, the results of fixed prosthesis in patients who suffered from chronical periodontitis after the combined periodontal and prosthodontic treatment and; 2) to evaluate the patients' treatment assessment after wearing the fixed splinting. Methods:The study included 15 patients provided 28 fixed splintings. Clinical and radiographic examinations were performed at the time of the delivery of the fixed splinting and after 6, 12, 18 months. The periodontal conditions were evaluated by plaque control index (PCIX bleeding of probe (BOPX pocket depth (PD)> clinical attachment loss(CAL)> teeth mobility (TM) JfP fixed partial denture mobility (FPDM) .With parallel radiographic technique and digital subtraction radiography, quantitative analysis of bone support (BS) and bone density (BD) around the abutments were performed. The comfort, aesthetic and function rehabilitation of the patient after wearing the fixed prosthesis were assessed by the questionnaire. Results: The periodontal conditions of abutments keep stable during the maintenance care period following periodontal and restorative therapy. The Bone support in the abutments changed without the statistic significance. The alveolar bone density increased significantly after 12 months. Most patients reported that the fixed splinting could provide the good chewing ability and phonetics after the 6 months follow-up. And 86.7%, 80% patients were satisfied with the aesthetics and hygiene of the fixed splining. Conclusion: It was concluded that combined periodontal and fixed splinting treatment of patients with chronical periodontal disease may provide the good results, provided the proper maintenance care are given.Part Two Three dimensional finite element analysis on thefixed splinting in patients with periodontal diseaseObjective: To investigate the stress distribution, diplacement on the teeth, fixed prosthesis and alveolar bone of the fixed splinting with different bone heights under different loads. Methods: The first experiment was to establish the wireframe model of the normal alveolar bone and teeth by the spiral CT and Pro/Engineer software. The second experiment is to extract the wireframe structure of the right posteriot region from the established wireframe model and to establish the standard three dimensiona finite element model. The variations of the standard finite element model were made by changing the number of splinted teeth and the level of bone support. By three dimensional finite element analysis, the stresses and displacement of each model wereobserved when different loading was applied. Results: (D For the teeth: Under horizontal loading, the stress level and displacement were higher than those under vertical loading. The Von Mises and displacement increased with the reduction of bone height. If the bone loss was the one third of the root, with the increase of the splinting abutments, the Von Mises decreased. ?For the prosthesis: Under horizontal loading, the stress level and displacement are higher than those under the vertical loading. The maximum value mainly distributed in the connectors of prosthesis, especially concentrated on the connector in the mesial surface of the pontic. ?For the alveolar bone: the stress concentration were found in the crest of the edentulous ridge. Under horizontal loading, the stress value and displacement are higher than those under vertical loading.Conclusion: ?The direction of loading can affect the value and distribution of the stress and displacement significantly. The stress value on the teeth, alveolar bone and fixed prosthesis under horizontal loading are higher than those under vertical loading. Therefore, the non-axial load should be avoided after the fixed splinting rehabilitation. ?Stress concentrations were found in the connectors of prosthesis and crest of the alverlar bone.@The stress concentrated in the apical area or near the apical area and cervical dentin ?when the bone loss was one third of the root, increasing one abutment, the VonMises level will decrease. Increasing the number of splinted abutments did not reveal a proportional reduction of stress in the fixed prosthesis and support tissues, ?when the the bone loss was two thirds of the root, the bigger sharing stress will focused on the weaker teeth, which are not recommended as the abutments in the linear fixed splinting .