Effect Of Sacrolisthesis Of Maxillary On Protrusion Of Incisors In Orthognathic Surgery Of Skeletal Class â…¢ Malocclusion

ObjectiveBy comparing sacrolisthesis of maxillary and variation of U1-NA distance before orthognathic surgery and after the orthognathic surgery of skeletal classⅢmalocclusion patients who maxillary sacrolisthesis, inquire into their relation,aims to direct the preoperative orthodontics, lead to a high standard coordinate beauty.MethodsTen skeletal classⅢmalocclusion patients who were treated by orthodontics and orthognathic surgery in the China Medical University who maxillary sacrolisthesis were selected,the cephalometric examination of the patients was taken before orthognathic surgery and after the orthognathic surgery (one or two weeks after orthognathic surgery).Take N as standard point,SN plane circle 7°uptime as X axle,make a vertical line cross N as Y axle, than measure the distance A-S of A to Y axle, reckon sacrolisthesis of maxillary during orthognathic surgery;Compare U1-NA distance before and after the orthognathic surgery, reckon variation of U1-NA distance. At last, reckon the effect of sacrolisthesis of maxillary on U1-NA distance.ResultsAfter the preoperative orthognathic surgery treatment,the A-S and U1-NA distance were statistically significant changed. The U1-NA distance were reduced by 1.48±0.81mm mm on average, it showed a statistically significant change; The maxillary sacrolisthesis by 3.32±1.27mm on average, it showed a statistically significant change. The ratio between them was 1.48±0.81 mm/3.32±1.27mm (≈0.416mm/mm).Namely, the maxillary moved forward by 1 mm on average, the U1-NA distance reduced by 0.416 mm on average.ConclusionIn orthognathic surgery treatment,maxillary moved forward may has impact on Ul-NA distance. the maxillary sacrolisthesis by 1 mm on average, the U1-NA distance were reduced by 0.416 mm on average.Orthognathic doctors can predict variation of U1-NA distance according to the maxillary sacrolisthesis during orthognathic surgery, control Ul-NA distance preoperate, obligate compensate preoperative,it could lead to a better surgical result, it is also an important part for the treatment of skeletal class III malocclusion.Key wordsSkeletal class III malocclusion;Orthognathic surgery;Antedisplacement of maxillary bone; U1-NA distance; Preoperative orthodontics...