Study On The Enfluence Of Shortened And Posterior Interrupted Dental Arches On Occlusal Stability And Temporomandibular Joint

Dentition defect is defined as the station that one or more teeth in the dental arches lost. Generally there are two types of dentition defect:shortened dental arches (SDA) and interrupted dental arches (IDA). They may exist separately or simultaneously. All the posterior teeth lost left only anterior teeth form an extreme shortened dental arch (ESDA). There are two types of IDA:anterior interrupted dental arches (AIDA) and posterior interrupted dental arches (PIDA). Also they may exist separately or simutanously. Caries and periodontitis usually happens on molars and results in teeth extract, that makes SDA and PIDA the most common types of dentition defect.Recently, researches found that the influence of SDA on oral functions such as masticatory function, occlusal stability, periodontal stability and temporomandibular stability is acceptable. While oral functions will be seriously impacted in the situation of ESDA. Studies about PIDA are not that much. The existing studies claim that displacement of the rest teeth in PIDA is inevitable. This study compared the effect of SDA and PIDA on oral function, especially temporomandibular function, discussed the influence of prosthetic treatment on patients with TMD and SDA/PIDA. There were three parts in this study:Part oneInvestigation about the feature of dentition defect and prosthetic treatment of Chinese citizens.Aim:Investigate the feature of dentition defect and prosthetic treatment of Chinese citizens.Materials and methods:Subjects were recruited from the patients of Stomatological hospital of Wuhan University from 15th February,2009 to 15th June,2009. Subjects were asked to finish a questionnaire and a clinical examination which included the situation of dentition defect and prosthetic treatment, as well as their will about prosthetic treatment if they had untreated edentulous spaces in dental arches.Results:The proportion of posterior lost is the highest among all types of dentition defect. The rate of restoration, however, is relatively low. The result of restoration is not satisfaction. The cost of prosthetic treatment is beyond many subjects can afford. The rate of restoration of anterior teeth is highest but the effect is not good, too.Conclusions:The rate of restoration of dentition defect is low in Chinese citizen. It is advisable to distribute medical resources properly to make it more effective.Part TwoComparison between posterior interrupt dental arch and shortened dental archAim:This study was designed to find the effects of posterior interrupt dental arches and shortened dental arches on occlusion and temporomandibular joint dysfunction signs and symptoms comparing to complete dental arches.Material and Method:In this study, occlusion stability and signs and symptoms of temporomandibular dysfunction (TMD) were compared between subjects with posterior interrupt dental arches (PIDA, n=52), subjects with shortened dental arches (SDA, n=40) and subjects with complete dental arches (CDA, n=60). Of all the 152 subjects,88 were male and 64 were female. The age limit was 18-70 years old and the average age was 43.5. Anterior occlusion stability was measured by (â…°) occlusion contact; (â…±) over bite. Posterior occlusion stability was measured by (â…°) interdentally spacing; (â…±) over eruption of unopposed teeth; (â…²) tilting of teeth adjacent to space. Signs and symptoms of TMD was measured by (â…°) clinical examination including clicking/ crepitus of the TMJ, active maximal mouth opening, vertical over bite and the path of mouth opening; (â…±) questionnaire about recipes, pain in or around TMJ, noises/clicking during mandibular movement and mandibular movement restriction.Result:For group SDA, proportion of anterior teeth occlusion contact (p=0.046) and posterior interdental spacing (p=0.023) increased. While the eruption of unopposed teeth (p=0.302) and tilts of adjacent teeth are not so serious as group IDA. More subjects were detected clicking/crepitus (p=0.045). More subjects choose soft food (p=0.000) and felt pain in the TMJ or adjacent area (p=0.044). For group IDA, the proportion of anterior teeth occlusion contact is similar to group CDA (p=0.537). Compared to group SDA, the over eruption of unopposed teeth was more serious (p=0.003). Signs and symptoms of TMJ are not detected.Conclusion:The anterior occlusion of interrupt dental arches are more stable than shortened dental while the protrusion of unopposed posterior teeth and tilt of teeth adjacent to the edentulous space are more significant. So it is advisable for interrupt dental arches to be restored.Part threeThe evaluation of the effect of prosthetic treatment of shortened dental arches to the process of temporomandibular dysfunctionAim:To evaluate the effect of prosthetic treatment of shortened dental arches to the process of temporomandibular dysfunctionMaterials and methods:Subjects with shortened dental arches wanted prosthetic treatment were recruited from the patients of the Temporomandibular Department of the Stomatology Hospital of Wuhan University between 15th October,2009 and 15th May,2009. Subjects were divided into treatment group or control group according to their willing. Removable partial dentures were applied to subjects in treatment groups in 2-4 weeks after their routine temporomandibular treatment. Evaluation was made before restoration and 3 months and 6 months after restoration. Evaluation was done at the same time. The sign indexes were pain in or around temporomandibular joint, restriction when mouth opening, time spending for a meal, and hardness of food they can take. The symptom indexes were tender pain around the temporomandibular joint, clicking/ crepitus of the temporomandibular joint, vertical over bite and the path of mouth opening. Result:Compared to the control group, subjects in the treatment group choose softer food (p=0.04). But the tender pain around temporomandibular joint released (p=0.003). Other differences were not significant.Conclusions:Prosthetic treatment with RPD after routine temporomandibular treatment will make people with shortened dental arches choose softer food but can releave the tender pain around temporomandibular.Part fourThe evaluation of the effect of prosthetic treatment of posterior interrupted dental arches to the process of temporomandibular dysfunctionAim:To evaluate the effect of prosthetic treatment of posterior interrupted dental arches to the process of temporomandibular dysfunction.Material and methods:Subjects with posterior interrupted dental arches wanted prosthetic treatment were recruited from the patients of the Temporomandibular Department of the Stomatologycal Hospital of Wuhan University between 15th October,2009 and 15th May,2009, Subjects were divided into treatment group or control group according to their willing. Removable partial dentures were applied to subjects in treatment groups in 2-4 weeks after their routine temporomandibular treatment. Evaluation was made before restoration and 3 months and 6 months after restoration. Evaluation was done at the same time. The sign indexes were pain in or around temporomandibular joint, restriction when mouth opening, time spending for a meal, and hardness of food they can take. The symptom indexes were tender pain around the temporomandibular joint, clicking/ crepitus of the temporomandibular joint, vertical over bite and the path of mouth opening.Results: Compared to the control group, subjects in the treatment group spend less time for a meal (p=0.021). Besides, the tender pain around temporomandibular joint of those in treatment group released (p=0.001).Conclusions:Prosthetic treatment with RPD after routine temporomandibular treatment will make people with posterior interrupted dental arches choose eat faster and can released the tender pain around temporomandibular.