Gnathology in implant-supported fixed restoration in edentulous mandible / 华西口腔医学杂志

OBJECTIVE@#This study aims to investigate the occlusal and myoelectric characteristics of implant-supported fixed denture in the mandibular region and provide reference for the design of fixed restoration.@*METHODS@#Sixty edentulous patients with implant-supported fixed denture were selected and divided into three groups: group A, 20 cases with implant-supported fixed restoration in the maxillary region; group B, 20 cases with natural dentition, and group C, 20 cases with removable partial denture. The T-scan 8.0 digital occlusion analysis system was used to evaluate the occlusal characteristics of patients in the three groups at intercuspal, protrusion, and left and right lateral positions. Electromyography was used to analyze the myoelectric amplitude and bilateral asymmetry index of the anterior temporalis and masseter of the three groups in different states such as resting and clenching. The relationship between occlusion and myoelectricity was also investigated.@*RESULTS@#In the occlusion analysis by T-scan, the occlusion time, the balance of left and right bite force, the left and right asymmetry of the occlusion center, the trajectory of central occlusion force, and the disclusion time were higher in group C than in groups A and B (P<0.05). No significant differences were observed in the anterior and posterior asymmetry of the occlusion center and percentage of bite force at anterior region among the three groups. In the analysis of myoelectricity, the myoelectric amplitude at resting state and the asymmetry index of masticatory muscles in group C were higher than those in groups A and B (P<0.05). The myoelectric amplitude during clenching in groups A and B groups was higher than that in group C (P<0.05).@*CONCLUSIONS@#In implant-supported fixed restoration at edentulous mandibular, when maxillary includes the removable partial denture, degree of occlusal instability and left and right asymmetry of occlusion center are greater than those with the natural dentition and implant-supported fixed denture at maxillary. The myoelectricity is closely related to occlusion. The removable partial denture can increase the myoelectric activity and reduce the potential of the masticatory muscle. The asymmetry of bilateral myoelectricity is related to the occlusion imbalance.

Occlusal analysis of implant-supported fixed denture in edentulous patients / 华西口腔医学杂志

OBJECTIVE@#This study aims to evaluate the occlusal characteristics of full edentulous patients with implant-supported prostheses and to provide a reference with the occlusal situation for clinicians.@*METHODS@#A Teetester occlusal analysis system was used with 30 full edentulous patients of implant-supported fixed denture (test group) in comparison with 30 natural dentition (control group). The percentage of occlusal force distribution were measured, as well as the occlusal time at the intercuspal, protrusion, and left and right lateral positions.@*RESULTS@#Compared with control group, the occlusion time, maximum occlusal force in intercuspal of test group significantly reduced (P<0.05); while control group was obviously superior to test group in the left and right bit force degree. Disclusion time in protrusion, occlusion times in lateral positions of test group also significantly reduced (P<0.05). There were no significant differences in average occlusion force, percentage of total force in anterior teeth, and lateral occlusion between test group and control group.@*CONCLUSIONS@#The maximum occlusal force in intercuspal of full edentulous patients with implant-supported prostheses reduce. The occlusal force in protrusive occlusion is concentrated in the front teeth, and the group function occlusion is the main lateral occlusal pattern.

Relationship between articulation paper mark size and percentage of force measured with computerized occlusal analysis

PURPOSE: Articulation paper mark size is widely accepted as an indicator of forceful tooth contacts. However, mark size is indicative of contact location and surface area only, and does not quantify occlusal force. The purpose of this study is to determine if a relationship exists between the size of paper marks and the percentage of force applied to the same tooth. MATERIALS AND METHODS: Thirty dentate female subjects intercuspated into articulation paper strips to mark occlusal contacts on their maxillary posterior teeth, followed by taking photographs. Then each subject made a multi-bite digital occlusal force percentage recording. The surface area of the largest and darkest articulation paper mark (n = 240 marks) in each quadrant (n = 60 quadrants) was calculated in photographic pixels, and compared with the force percentage present on the same tooth. RESULTS: Regression analysis shows a bi-variant fit of force % on tooth (P<.05). The correlation coefficient between the mark area and the percentage of force indicated a low positive correlation. The coefficient of determination showed a low causative relationship between mark area and force (r2 = 0.067). The largest paper mark in each quadrant was matched with the most forceful tooth in that same quadrant only 38.3% of time. Only 6 2/3% of mark surface area could be explained by applied occlusal force, while most of the mark area results from other factors unrelated to the applied occlusal force. CONCLUSION: The findings of this study indicate that size of articulation paper mark is an unreliable indicator of applied occlusal force, to guide treatment occlusal adjustments.

Relationship between articulation paper mark size and percentage of force measured with computerized occlusal analysis

PURPOSE: Articulation paper mark size is widely accepted as an indicator of forceful tooth contacts. However, mark size is indicative of contact location and surface area only, and does not quantify occlusal force. The purpose of this study is to determine if a relationship exists between the size of paper marks and the percentage of force applied to the same tooth. MATERIALS AND METHODS: Thirty dentate female subjects intercuspated into articulation paper strips to mark occlusal contacts on their maxillary posterior teeth, followed by taking photographs. Then each subject made a multi-bite digital occlusal force percentage recording. The surface area of the largest and darkest articulation paper mark (n = 240 marks) in each quadrant (n = 60 quadrants) was calculated in photographic pixels, and compared with the force percentage present on the same tooth. RESULTS: Regression analysis shows a bi-variant fit of force % on tooth (P<.05). The correlation coefficient between the mark area and the percentage of force indicated a low positive correlation. The coefficient of determination showed a low causative relationship between mark area and force (r2 = 0.067). The largest paper mark in each quadrant was matched with the most forceful tooth in that same quadrant only 38.3% of time. Only 6 2/3% of mark surface area could be explained by applied occlusal force, while most of the mark area results from other factors unrelated to the applied occlusal force. CONCLUSION: The findings of this study indicate that size of articulation paper mark is an unreliable indicator of applied occlusal force, to guide treatment occlusal adjustments.