Effects of orthodontic treatment with first molar extraction of 14 cases

Objective To evaluate the effects of the orthodontic treatment with first molar extraction and to investigate the relative treatment principles,space closure and third molar occlusion results.Methods 14 patients with the first molar extraction treatment in the past ten years were analyzed.Model PAR index and cephalograms were used to evaluate space closure,occlusal relationship,and soft tissue lateral profile after treatment.Panoramic films were used to evaluate root resorption,alveolar crest height and root paralleling of second molars.Results The average treatment time was (29.5±4.3) months.9 cases(64.3％)were evaluated as greatly improved,5 cases (35.7％) as improved,and none were evaluated as worse or no difference.Extraction spaces of first molars were closed; good occlusalrelationships and soft tissue profiles were achieved in all cases.The roots of second premolar,second molars and third molars were paralleled.The root and alveolar crest height of the second molars showed no significant difference after treatmen.Conclusions The first molar extraction cases could receive satisfactory results under strict plan,appropriate anchorage control and careful clinical operation. Key words: First molar extraction;  Orthodontic extraction treatment;  Effect evaluation;  MBT technique