| Objective Temporomandibular disorders(TMD)is a common disease in the field of stomatology at present,and the trend of increasingly highlight,so that the exploration of the etiology of TMD has long been a hotspot in the researches of the scholars;The relationship between occlusion and the occurrence and development of TMD has been studied by scholars both at home and abroad from multiple aspects for many years,but there is no consistent conclusion.Some studies believe that occlusion or jaw position factors may affect the function of TMJ and lead to the occurrence of TMD.The purpose of this experiment is to use the advanced T-scan digital electronic occlusal analysis system to record dynamic occlusal contacts in subjects with TMD.Compared with subjects with no symptoms,occlusal characteristics and time characteristics of mandibular movement from reference position(RP)and intercupal position(ICP)were analyzed,so as to further explore the correlation of mandibular movement characteristics of occlusion and TMD,and to provide more reference for orthodontic clinical diagnosis and treatment.Methods1.Pre-treatment adult patients admitted to the orthodontic department of our hospital from October 2017 to October 2019 were selected,and volunteers were selected from the students of Tianjin Medical University,aged 18-30 years old,with an average age of 23.04 ± 2.95 years old.According to the DC/TMD,the involved subjects were divided into Group 1 and Group 2.2.All subjects will undergo the following procedures:(1)Making full-mouth impression and filling super-anhydrite model;(2)Medical history inquiry,muscle palpation and temporomandibular joint examination and questionnaire filling;(3)Adjusting the position of the subjects and keeping the Frankfort plane parallel to the horizontal plane;(4)Subjects were trained to perform mandibular movements,including open-close movement,mandibular protrusion movement and mandibular lateral movement,until the subjects mastered and met the experiment requirements;(5)Selecting the appropriate T-scan diaphragm and occlusal fork;(6)The width of bilateral maxillary central incisor of the subject was recorded,and the virtual dental arch was generated in the T-scan software,and then adjusted according to the plaster model of the subject;(7)Biting to select the appropriate sensitivity;(8)Recording the occlusal processes of subjects from ICP;(9)Muscle deprogramming,muscle memory removal,and searching for subjects’ RP;(10)Recording the occlusal processes of subjects from RP.3.Selecting measurement indexes:(1)Mandibular movement time indexes:Occlusion Time(OT),Disclusion Time(DT),Protrusion Disclusion Time(Pro-DT),Left lateral Disclusion Time(Le-DT),Right lateral Disclusion Time(Ri-DT);(2)The measurement indexes of subjects’ ICP maximum occlusion:The left and right force percentages were recorded and the force asymmetry index was calculated;the position of the center of force(COF)was recorded and the lateral COF offset and COF offset distance were measured.(3)The incidence of occlusal interference during the subjects’ mandibular protrusion and lateral movement from ICP.4.Input all collected data into Excel for sorting,and use SPSS 20.0 statistical analysis software for statistical analysis.Results1.In Group 1,OT was significant longer when subjects occlude into RP than that into ICP(P<0.01);Moreover,the time of mandibular movement from RP was longer than that from ICP,the differences in DT and Le-DT were statistically significant(P<0.05),whereas that were not significant in Pro-DT and Ri-DT.In Group 2,OT was significant longer when subjects occlude into RP than that into ICP(P<0.01);The time of mandibular movement from RP was longer than that from ICP,and the differences in Le-DT and Ri-DT were statistically significant(P<0.05),whereas the differences in DT and Pro-DT were not statistically significant.2.Comparing Group 1 with Group 2,except for DT,the time of mandibular movement of Group 1 in different jaw positions was shorter than that of Group 2.The differences in Le-DT and Ri-DT were statistically significant when the mandibular movement started from RP(P<0.05);When the mandibular movement started from ICP,the difference in Pro-DT was statistically significant(P<0.05).There was no significant difference in the rest of the indexes(P>0.05).3.When the maxillary and mandibular teeth reached into ICP maximum occlusion frame,the mean occlusal asymmetry index of Group 1 was lower than that of Group 2,with statistically significant difference(P<0.01).The mean lateral offset and migration distance of COF in Group 1 was less than those in Group 2,with statistically significant difference(P<0.05)..4.There were 3 subjects in Group 1 who had occlusal interference during mandibular protrusion movement from ICP,and 15 subjects in Group 2,and the difference was statistically significant(P<0.01).There were 8 subjects in Group 1 who had occlusal interference during lateral mandibular movement from ICP,and 15 subjects in Group 2,and the difference was not statistically significant(P>0.05).Conclusion1.There were time differences in the movement of mandibular from RP and ICP in adult patients with TMD,which were manifested as the prolonged occlusion time and lateral disclusion time from RP.2.The distribution of left and right side bite force in adult patients with TMD is more unbalanced than that in those without TMD symptoms.3.In adult patients with TMD,the incidence of occlusal interferences in the posterior teeth is higher in the mandibular protrusion movement from ICP,and most of the occlusal interferences occur on the second molar.4.The incidence of non-working side occlusion interferences in lateral mandibular movement from ICP in adults patients with TMD was not significantly different from that of asymptomatic patients.. |
