| Periodontium is a very important structure in keeping tooth stable and bearingocclusal force. It can maintain balanced metabolism and keep normal periodontal tissueform as well as physiology funcation under the stimulation of occlusal force inphysiological range.When occlusal force is too big, pathological remodeling ofperiodontium will happen. The big occlusal force leads to the destruction of periodontiumappearing clinicl attachment loss, alveolar bone absorbtion, loosening of tooth and toothloss at last. Studying the rule of periodontium remodeling after reducing the occlusal forceon teeth with clinical attachment loss plays an important role in diagnosis and treatment ofteeth in clinic.The study of periodontium remodeling was focused on animal experiments, histologyand molecular biology. The effect of occlusal adjustment on periodontium remodeling of teeth with different heights of periodontal tissue has not yet been reported. In clinic, theprimary indexes of evaluating the effect of periodontium remodeling are alveolar bone lossand periodontal attachment level, which can’t comprehensively reflect the condition ofperiodontium. Teeth are fixed in alveolar socket by elastic periodontal ligament. Teeth andperiodontal tissue established a vibration system. Teeth can vibrate under impact force.Teeth vibration frequency is the inherent characteristic of periodontal tissue, and it’s closedto the area, thickness and mechanical properties of the periodontal ligament as well as theheight and density of alveolar bone. Vibration is the inherent property of objects. Thevibration frequency is closely related to the elastic modulus, density, Poisson’s ratio andboundary condition. Many researches about evaluating the osseointegration of implant byvibration frequency have been reported. Using teeth vibration frequency as an index toobserve the change of periodontal condition in periodontium remodeling, few relatedstudy is reported.In order to investigate the effect of time and range of occlusal adjustment onperiodontium remodeling, anterior teeth with periodontal attachment loss were selectedand performed an occlusal adjustment on which bear too big occlusal force. The law ofperiodontium remodeling was studied by analyzing the change of clinical attachmentloss(CAL), alveolar bone loss(BL), tooth mobility(TM) and tooth vibrationfrequency(TVF) after occlusal adjustment.The study can be divided into three parts.1. Determination of the subjects and grouping:Anterior teeth with periodontal attachment loss were selected as the subjects, andthey were divided into three groups according to the periodontal level and alveolar boneheight measured in X-ray photo. There groups of periodontal attachment level were0~2mm,2~4mm and4~6mm.2. The analysis of occlusion and measurement of vibration frequency to anterior teeth:(1) Measure and analyze the occlusal force on anterior teeth by means of T-ScanⅢocclusal analyzing system. After the patient informed and consented, occlusal adjustmentwas performed on the teeth with overload. (2) The relationship between impact force and tooth vibration frequency was studiedby measuring the teeth vibration frequency under different impact force.(3) Evaluate the condition of periodontium of the subjects by measuring and analzingthe teeth vibration frequency and tooth mobility of teeth with periodontal attachment loss.3. The effect of occlusal adjustment on periodontium remodeling of teeth with differentperiodontal attachment levels:Under the direct of T-ScanⅢ occlusal analyzing system, occlusal adjustment werepreformed to the teeth with big occlusal force. The effect of periodontium remodeling wasstudied by analyzing the change of CAL, BL, TM and TVF after occlusal adjustment.The results of this study s howed as following.1. After a rigorous screening of clinical, there were393anterior teeth were selected.According to the periodontal attachment level, the teeth were divided into0~2mm,2~4mm and4~6mm. The sizes of each group were140,136and117.2. Referring to the normal occlusal force distribution,281teeth with big occlusal forcewere determined to receive occlusal adjustment. The results of anterior teeth vibrationfrequency test shows that there is a significantly linear relationship between the impactforce and the TVF (P<0.05).At the same periodontal attachment level, TM and TVF ofteeth with big occlusal force were significantly lower than those with normal occlusalforce (P<0.05). And the most significant change were shown in teeth after reducing5~10%of the occlusal force.3.(1) Anterior teeth with CAL under2mm, TM decreased significantly (P<0.05) andTVF increased rapidly (P<0.05) at the first month. The changes of them decreasedgradually and turned to be stable at the third month. And the most significant change wereshown in teeth after reducing5~10%of the occlusal force.(2)Anterior teeth with CAL in the range of2~4mm, TM decreased gradually and TVFincreased slowly, and the change turned to be stable at the third month.(3)To anterior teeth CAL in the range of4~6mm, adjustment range and time havelittle effect on TM but TVF shown significantly increased(P<0.05).Conclusion: 1. Under20N, the teeth vibration frequency increases as the increasing of impactforce.Teeth vibration frequency measured under the same impact force can as an index ofevaluating the condition of periodontium.2. At the same periodontal attachment level, the periodontal conditions of teeth withbig occlusal force are worse than those with normal occlusal force, which need to reducethe occlusal force properly.3．Occlusal adjustment of10%can obviously improve the periodontium remodelingof teeth with CAL under4mm.There is little effect on teeth with CAL in the range of4~6mm. As the increasing of the CAL, the effect decreases of periodontium remodeling. |
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