Study Of The Non-Extraction Cases Treated With The Self-Ligating Brackets And Conventional Bracket System

Objective: To evaluate the dental arch and soft-and-hard tissue changes in patients with arch crowding treated with self-ligating and conventional bracket systems.Dental arch changes include the dental arch width and the arch depth and the arch length.Methods:40non-extraction orthodontic cases were selectd,20cases used conventional brackets.And the orthers used slef-ligament brackets.We made upper and jaw models,and then taken the selected index point to a number of measurement:2)Measure the upper and lower arch crowding, measure maxillary arch width.(Include:canine width、first premolar buccal cusp width、 first premolar fovea central width、second premolar buccal cusp width、second premolar fovea central width、first molar mesiobuccal cusp width、first molar fovea central width); measure the upper and lower arch depth and length.2)Measures model three times by the same orthodontist used a vernier caliper (accuracy0.02mm,Hensen, Shanghai), repeated3times and Calculated the average.Results:1) There were no statistically significant difference in the changes of the two groups of arch crowding before the treatment(P>0.05) 2) Both the maxillary arch width of two groups were increased after treatment, especially the maxillary premolar width increased significantly (P<0.05).In the self-ligating brackets group, the intermolar width increased significantly then the conventional brackets.But there were no statistically significant difference in the changes between two groups.3) Both the upper and lower arch depth of two groups were increased after treatment(P<0.05). In the self-ligating brackets group, the anterior arch depth increased significantly then the conventional brackets.While the middle arch depth increased significantly in the self-ligating brackets group.But there were no statistically significant difference in the changes between two groups (P>0.05)4) Both the upper and lower arch length of two groups were increased after treatment(P<0.05). In the self-ligating brackets group, the double jaw arch length increased significantly then the conventional brackets. But there were no statistically significant difference in the changes between two groups (P>0.05)5) Cephalometric results shows:Patients of self-ligating brackets group appeared lower incisor inclination after treatment. But there were no statistically significant difference in the changes between two groups (P>0.05)...