Experiment Study On Postoperatively Accelerated Orthodontic Tooth Movement In Surgery-first Approach

The traditional approach of orthognathic surgery(OS) involvespreoperative orthodontic(PRO) preparation, proceeding with orthognathicoperation(OO) and postoperative orthodontic(POO) minor adjustments.Instead,a large number of clinical studies have performed in recent years,which adopting surgery-first(SF), without preoperative orthodontictreatment, to achieve the purpose of the treatment of dento-maxillofacialdeformities with orthognathic surgery and rapid postoperative orthodontic,and achieved satisfied results. After the the strict preoperative diagnosisand design,they concentrated orthodontic treatment in postoperativeorthodontic,simplified the complex procedures, reduced the cost oftreatment.In the course of treatment,they found the phenomenon of rapid toothmovement after orthognathic surgery, which reducing the overall time ofthe treatment of dento-maxillofacial deformities.The theory，which surgeryupregulates the cell of periodontal to activity highly benefit for teethmoving in orthodontic treatment,has been proposed. But there is little proof from basic experiment.In the experiment,the animal model of tooth movement had beenestablished, then summed up the rule of the tooth movement in themodel.After that, comparing the speed of tooth movement in postoperativeorthodontic of Surgery-first(SF) to preoperative orthodontic in traditionalprogram,study the fast-moving phenomenon preliminary.In the experiment,New Zealand white rabbits had been adopted,whichwere divided into experimental group (group A) and control group(groupB).In group A, the Surgery-first program model had been established inthe mandibular of rabbit, using75gf as initial force to move mandibularfirst premolar forward. In group B, initial force of75gf movedmandibular first premolar forward only.Results:The distance mandibular first premolar had moved is0.96mmon average in group A,0.91mm in group B,there are no significantdifference between the two groups,p=0.36,more than0.05.Conclusions: Molecular changes induced by injury and postoperativerecovery of orthognathic surgical on mandible do not evidently inducepostoperative rapid orthodontic tooth movement in mandible,local factorssuch as weakening of occlusal function and biomechanics changed causedby improvement of dentofacial relationship could not be ignored.