The Investigation About The Relationship Between Occlusal Tooth Wear And Dentition Defect Functional Classification

Tooth wear is a very common phenomenon that the hard tissue of the tooth surfacewas lost without caries and trauma. When the natural teeth functionate in the mouth, therewill be a friction between upper and lower teeth, and the occlusal tooth wear may appear.If not control it, occlusal tooth wear can lead to a series of concomitant negative impact onquality of life, such as dentin exposed, tooth sensitivity, vertical distance reduced and soon. With China has gradually entered the aging society stage, this irreversible disease hasbeen a high-incidence oral disease after caries and periodontitis.There are many effect factors of occlusal tooth wear, such as genders, age, diet,dentition functional movement, tooth tissue and so on. However, the influence of dentition defect, especially the function of remained teeth, is not very clear at present.Hierarchical dental functional classification system was proposed, according to thetooth number, distribution of tooth and posterior occluding pairs, by the researchers ofRadboud University Nijmegen Medical Centre. This classification system containsdentition, jaw, anteirior teeth, premolar and molar level, every level has its own criteria.And then the dentition can be recorded according to the dichotomy. The value1meansthat the dentition meet the criteria, and the value0means not. In Europ, Damyanov NDhas made a epidemiological investigation about the Bulgarian adults by the system. InAsia, Nguyen TC and Zhang Qian also have made epidemiological investigations inVietnam and China by the system successfully. The results of their researches havedemonstrated that the hierarchical dental functional classification system could reflect thefunction of dentition well.Objective:257patients who came to the department of prosthodontics of the Schoolof Stomatology of the Fourth Military Medical University from January to July in2012were selected as experimental subjects. The data was collected in a way of questionnairesurvey and clinical examination. The effect factors of the occlusal tooth wear wereresearched in a way of combining with the hierarchical dental functional classificationsystem. We investigated the relationship between the occlusal tooth wear and dentitiondefect and the functional status of dentition defect especially.Materials and methods: The occlusal tooth wear of5930teeth of the257patientswere examined and recorded through the modified Smith and Knight tooth wear index(occlusal tooth wear index, OTWI). And other related informations were collected in away of questionnaire and clinical examination. And then the patients were categorizedaccording to the hierarchical dental functional classification system. Then multiple linearregression and t test were applied to analyze the related factors of occlusal tooth wear.Result:1. Descriptive analysis of occlusal tooth wear and dentition statusOcclusal tooth wear was observed in all subjects of this sample with a mean OTWI score of1.44±0.46. All of subjects (n=257) had a mean number of23.1±6.4teeth and5.1±2.9POPs. Highest OTWI scores were found in molars of males (1.57±0.57) and thelowest were in premolars of females (1.32±0.47).2. Analysis between occlusal tooth wear and gender, ageIn the257subjects, males had higher scores than females. The older subjects hadseverer tooth wear than the younger. OTWI scores were significantly associated with ageand gender (P<0.05).3. Analysis between occlusal tooth wear and chewing side preference, occlusalguidance scheme133subjects (52%) reported a chewing side preference:77(30%) for the right side and56(22%) for the left. Chewing side preference was significantly correlated with OTWIscores (P<0.05). The occlusal tooth wear of chewing side preference was severer than theother side. If analyzed for the different dental regions separately, the significant differenceof OTWI score only existed in the molar region (P=0.038<0.05). Of all subjects,23(8.9%) had canine protected guidance,213(82.9%) had group function,21(8.6%) werenot measurable at the left side. And22(8.6%) subjects had canine protected guidance,217(84.4%) had group function,18(7.0%) were not measurable at the right side. Subjectswith group function had higher mean OTWI scores than those with canine protectedguidance in the molar region(P<0.05).4. Analysis between occlusal tooth wear and dentition defectIn all the levels of the hierarchical dental functional classification system, only―≥10teeth in both upper and lower jaw‖was significantly correlated with OTWI scores(P=0.001<0.05); when the number of tooth in both upper and lower jaw is less than10,anterior teeth and premolars have higher lever occlusal tooth wear than that of the numberof tooth is greater than or equal to10in both upper and lower jaw (B<0, P<0.05). Whenthe number of tooth is greater than or equal to10in both upper and lower jaw, the95%confidence interval for B was (-0.47,0.06) in the anterior teeth region, the95%confidenceinterval for B was (-0.40,0.02) in the premolar teeth region. Conclusion:1. Occlusal tooth wear was significantly associated with age and gender. The age wasolder, the occlusal tooth wear was severer. The male had severer occlusal tooth wear thanfemale.2. Occlusal tooth wear of the chewing side preference was severer than the other side.We suggested that the people who had chewing side preference shuold correct the badhabit to reduce the occlusal tooth wear. The molar region occlusal tooth wear of groupfunction was severer than that of canine protected guidance in the molar region.3. The occlusal condition of having fewer than10teeth in each jaw seems to be a riskfactor for increasing occlusal tooth wear. When the number of tooth is less than10, theocclusal tooth wear will increase significantly. The dentists should repair the missing teethof the patients effectively in the early stage, and try the best to recover the integrality ofthe dentition function. Then we could reduce the occurence and development of theocclusal tooth wear in this way.