Measurement And Analysis Of The Mandibular Movement Curves Of University Students Without Symptoms

Objective To study the characteristics of mandibular movement curves, ranges of mandibular movements of university students without symptoms, and try to find out related factors of the ranges of mandibular movements.Methods84university students (39males and45females) aged from17to24years in Changsha were randomly selected. All of them are without symptoms. We tested the curves of maximum vertical opening and closing movement and mandibular edge movements with the help of the Arcus DigMa II system (Kavo, Germany). So as to get knowledge of characteristics of the maximum vertical opening and closing movement, and to record the ranges of mandibular edge movements. We also compared differences of the maximum vertical opening and closing movement and ranges of mandibular movements between different gender groups. Related factors of ranges of mandibular movements are also studied in this study.Results1. The curve of opening and closing movement can not exactly come to act as a same curve, but has an average distance of3.13±1.49mm, without difference of statistical significance between different gender groups. When a subject open his/her mouth to the maximum range, the mandibular may swing around, and both condylar processes move downward and forward at first,then move upward and forward smoothly.2. Ranges of mandibular edge movements:opening43.48±5.65mm, protrusive movement7.78±1.64mm, the left side7.11±1.85mm and the rights side6.86±1.87mm. Ranges of the left and right sides edge movement have correlation, but there is no difference of statistical significance between them. Males can open their mouths wider than females, with difference of statistically significance.3. Ranges of opening and protrusion movements are related with the ranges of lateral movements. The height affects the range of opening. Tooth wear and the habit of bruxism affect the range of protrusion. Ranges of lateral movements can be affected by anterior teeth Bolton index, crowding degree and mid-line of dentitions.Conclusions1. The mandibular swing left and right in the process of maximum vertical opening and closing movement. The curve of opening and closing can not act as a same curve. And both condylar processes move smoothly.2. People can move to the left as much as to the right. Males can open their mouths wider than females.3. Ranges of opening and protrusion movements are related with ranges of lateral movements. And ranges of mandibular movements can be affected by height, tooth wear, the habit of bruxism, anterior teeth Bolton index, crowding degree and mid-line of dentitions.