[A study of dynamics of orthodontic archwire on the dental arch. 1. Distribution of orthodontic forces during labial movement of bilateral incisors].

The study on labial movement of maxillary unilateral incisor had been reported previously. This study was the case of maxillary bilateral incisors. Orthodontic forces during labial movement of maxillary bilateral incisors which were produced by stainless steel archwire with vertical loops and nickel titanium archwire, were measured and were examined the distribution of orthodontic forces to the dental arch in the experimental apparatus with strain gauges. The following results were found: 1. In nickel titanium archwire, orthodontic forces were distributed to the entire dental arch, and the distribution of orthodontic forces could be classified into three types, which were similar to the previous study. 2. In stainless steel archwire with vertical loops, orthodontic forces were distributed only to bilateral incisors and adjacent tooth to bilateral incisors. 3. When bilateral incisors displaced lingually, it showed that there were additional orthodontic forces distributions as if two unilateral distributions were overlapped. 4. For maxillary bilateral incisors were moved in optimum force, some consideration to adjust the loops of stainless steel archwire was needed.