| In recent years,the number of elderly patients is gradually increased,and the number of dentition defect or edentulous jaw caused by dental caries,periodontosis and other factors is gradually increasing,too.For these patients,how to ensure a restoration better retention and stabilization has become a hard work.In order to increase the retention and stabilization properties of a restoration,we can place a magnet and a keeper on the abutment and on the denture inner surface respectively,increasing the retention and stability by relying on the magnetic force.The complete overdenture with magnetic attachment is a mechanical system which composed with the abutment,the magnet attachment,the denture and bone tissue.In the normal chewing process,the bite force was sent to the jaw tissue through "denture-attachment-abutment" and "denture-base-mucosa".When the abutment bears appropriate occlusal force,it can stimulate the reconstruction of the periodontal tissue of the abutment and maintain the health of the periodontal tissue;if overloading,it will cause periodontal tissue trauma and the alveolar bone absorbtion.There is a conclusion in some reports that the bite force distribution of the complete overdenture,the alveolar bone density and height will change after a period time,and we can also find this phenomenon in our clinical work.However,to date,no such systematically research has focused on the relationship between the bite force distribution of the complete overdenture and the periodontal tissue of the abutment.To analyze the relationship between the bite force distribution of complete overdenture retained by magnetic attachment and the periodontal tissue's condition of abutment,85 patients were selected as the subjects in this study.The periodontal tissue's condition was checked 1 to 2 years after the patients wore the denture,and the bite force was analyzed using the T-Scan? system.Finally,the relationship between the bite force distribution and the periodontal condition of abutment was analyzed.On the basis of the above experiment,32 cases of COD were enrolled,and got a further consultation about the distribution of bite force after three months,six months and one year later.The bite force was adjusted if the distribution of the bite force is irrational,and then the relationship between adjustment of the bite force and the remodeling of periodontal tissue was observed.Such,the results would provide references for maintaining the health of the abutment and prolonging the life of prosthesis.The whole experiment can be divided into two parts: 1.The clinical study about complete denture with magnetic attachmentIn order to evaluate the effect of the COD retained by magnetic attachment and analyze the relationship between the bite force distribution and the periodontal tissue's condition of abutment,85 patients with COD retained by magnetic attachments treated in the Department of Stomatology of the Fourth Military Medical University as the subjects in this study.The periodontal tissue's condition was checked and the bite force distribution was analyzed using T-Scan? system.Finally,the relationship between the bite force distribution and the periodontal condition of abutment was studied,in order to provide references for the clinical research.The results showed that:(1)The satisfaction rate of denture was high and the repairing effect of retention,stabilization and chewing reached more than 90%;(2)The periodontal examination(PLI?PD and GI)had no obvious abnormalities,but there were some patients with poor oral hygiene and periodontitis;alveolar bone density of the abutment decreased obviously from X-ray after a period time,especially for the abutments of COD retained by attachment in the unilateral;but there was no significant difference in the alveolar bone loss;(3)Bite force distribution over the denture retained by magnetic attachment is not balanced,the bite force distributed in anterior teeth area was higher than that of posterior;the bite force distributed in the abutment and the side of abutment in the unilateral were higher than those of the contralateral;but no significant differences were observed in the denture retained in the bilateral;there was a significant correlation between the distribution of bite force and the alveolar bone density in the abutment region,it means that the density of the abutment alveolar bone decreased with the increasing of bite force loading on the abutment.2.The effect of bite force adjustment on abutment and periodontal tissueThe results of the first part experiment showed that there was a certain relationship between the periodontal health and the bite force distribution.In order to further explore the effect of bite force adjustment on the periodontal tissue remodeling of the abutment,32 patients were followed up regularly,the distribution of the bite force of the denture was measured by T-Scan III and adjusted accordingly if the bite force distribution was irrational.The process of reconstruction of the periodontal tissue in the process of bite force adjustment was observed.Finally,the relationship between adjustment of the bite force and the remodeling of periodontal tissue was analyzed.The results showed that: the bite force distribution was rational through determination and adjustment accordingly after 3?6 or 12 month later.The gap of bite force between the left and right was less than 20%,the bite force of the anterior teeth was less than 30%,and the bite force of the abutment was less than 15%.There was no significant changes in the periodontal tissue(PLI?PD and GI),and the height and mineral density of alveolar bone had not significantly reduced yet.In conclusion:1.The COD with magnetic attachment has good properties about retention and stabilization,and the periodontal tissues of the most abutments were health.2.In the course of the use of the denture,the distribution of the bite force over the denture would change,bringing about the distribution of the bite force unbalanced.The bite force distributed in anterior teeth area was overload and the bite force distributed in the abutment and the side of abutment of the COD in the unilateral were higher than those of the contralateral3.There is a relationship between bite force of the abutment and the alveolar bone density,it is that alveolar bone density of the abutment decreased with the increasing of bite force distributed on the abutment.4.In the process of using the denture,the alveolar bone density could be prevented to decline in a certain degreed by regularly adjusting the distribution of bite force.In conclusion,in the process of using the denture,in order to maintain the health of the abutment and prevent the alveolar bone density decreased,we should regularly check the distribution of bite force and adjust the distribution of full denture bite force balanced,so that to prevent the abutment overloading. |
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