A Preliminary Study Of T-Scan In Occlusal Characteristics Analysis In Patients With Vertical Root Fracture

Objectives1. To investigate the clinical characteristics in patients with vertical root fracture and to assess the etiology of vertical root fracture.2. To analyze the occlusal characteristics in patients with vertical root fracture and to provide theoretical basis for the etiology,diagnosis and prevention of the vertical root fracture. Methods1. 98 cases of vertical root fracture patients were included in the study, with 103 involved teeth. The age and gender, tooth type and root distribution, as well as clinical manifestations and the X-ray film were observed and evaluated. All statistical analyses were performed using SPSS17.0 software package,to explore clinical features and distribution of vertical root fracture,to analyze the possible causes and regularity of vertical root fracture.2. 8 patients with vertical root fracture from the department of endodontics were selected as the observational group.8 people with normal occlusion were also randomly selected and matched with the observational group based on the similar condition,which were regarded as the control group.The occlusal characteristics in patients with vertical root fracture were analyzed and compared with the people with normal occlusion.The occlusal courses were recorded by T-ScanIII system in intercuspal position and lateral movement.The distribution of tooth occlusal force percentages and two sides occlusal force percentages, occlusion time and disclusion time,as well as asymmetry index of occlusal force were examined by Wilcoxon matched-pairs signed-ranks sum test. The distribution of premature contact,laterotrusive interference and the position of center of force were examined by Fisher’s Exact Test.All tests were used at two-tailed significant level 0.05.The result was significantly differen when P<0.05. Results1. Vertical root fracture used to be appear in middle aged and elderly people, male greater than female. 57.3% of affected roots were mesial roots in the mandibular molars and mesial buccal roots in the maxillary molars. 5 were affected 2 or more roots simultaneously.13(13.3%) patients had symmetric or multiple teeth with vertical root fracture.Among those 103 vertical root fracture teeth, 45(43.69%) were teeth with root cannal therapy and 58(56.31%) were teeth without root cannal therapy. Vertical root fracture in teeth with root cannal therapy most occurred in patients aging 36 to 45 years and the ratio of male to female stood at 1: 1, 95.6% of affected teeth crown were non-natural.While the frequently age range of vertical root fracture teeth without root cannal therapy was 46 to 55 years, male greater than female, 74.1% of affected teeth were natural coronal integrity with different degree abrasion of the occlusal surfaces. The teeth with root cannal therapy were more than which without root cannal therapy when vertical root fracture affected the mesial roots in the mandibular molars.While the teeth with root cannal therapy were less than which without root cannal therapy when vertical root fracture affected the distal roots in the mandibular molars. Clinical manifestations of vertical root fracture were complicated and various,which was similar to pulp disease, periodontal disease, and dull discomfort or pain when biting. X-ray examination is necessary in diagnosis, which show abnormal broadening in middle lower part of root canal, projective fracture linear and shift fracture fragment.2. Tooth occlusal force percentages, occlusion time and disclusion time,as well as asymmetry index of occlusal force in vertical root fracture group was more than control group, Wilcoxon matched-pairs signed-ranks sum test showed that the difference between the two groups was statistically significant(P<0.05).Two sides occlusal force percentages had no significant differences between the two groups(P > 0.05).The COF in vertical root fracture group were mostly out of the gray ellipse, while the COF in the control group were all within the gray ellipse, Fisher’s Exact Test showed that there was a significant difference between the two groups(P<0.05).While the excursion direction of COF, as well as the incidence of premature contact had no significant differences between the two groups(P>0.05).The incidence of laterotrusive interference in vertical root fracture group was more than control group.There was a significant differences between the two groups(P<0.05). Conclusions1. There was unbalanced occlusion in patients with vertical root fracture. The force percentages loaded on the vertical root fracture teeth was more than control group. The force percentages loaded on the affected side was more than unaffected side. Unbalance and poor stability of occlusion contact can contribute to the occurance of VRF.2.The state of occlusion with abnormal occlusal surface morphology,deep overbite,as well as abnormal intercuspal position was highly significant for the occurance of vertical root fracture.