| BackgroundThe Class ? division 2 subdivision was observed common clinically which a complex type of malocclusion was.First,the upper anterior teeth were inclined with the mandiblar retraction.Second,the molars were characterized by one side of the distal relationship,one side of the neutral relationship with asymmetrical arch and midline deviation.These characteristics caused the occlusion function abnormal.First,the teeth contact could not be simulataneous and even in maximum intercuspid position,and interfered in protrusive and lateral position because of the abnormal occlusion guidance.Second,the molar relationship asymmetry made the imbalance of the craniofacial muscles.It even caused the abnormality in the structure or function of the temporomandibular joint,which had a serious impact on the functional stability of the oral and maxillofacial system.Contemporary orthodontic treatment not only pursued a good static occlusion goal,but also pursued the ideal dynamic occlusion function.Accurate quantitative analysis of the improvement of occlusal function during orthodontic treatment in patients with Class ? division 2 subdivision had become a popular topic and has strong clinical significance.The digital occlusion analysis system such as T-Scan was a tool that could simultaneously record static and dynamic changes of occlusion.The evaluation of orthodontic occlusion measurement and occlusion improvement was accurate and fast.Therefore,this study evaluated the changes in occlusal function status changed before and after aligning and leveling.ObjectiveThe Class ? division 2 subdivision malocclusion patients were selected,who wear the brackets on permanent tooth,with no extraction.Before and after aligning and leveling,T-Scan ?I system was measured to analyze the changes in occlusal contact characteristics.In order to investigated the changes of the occlusal movement stability because of the changes of occlusal function.Meanwhile it would provide the guidance for clinical diagnosis and treatment for Class ? division 2 subdivision malocclusion patients before and after aligning and leveling.MethodsIn the study,14 patients who had Class ? division 2 subdivision malocclusion were selected as the treatment group.In addition,14 volunteers aged who had Class I occlusion were selected as the control group.Before the beginning of the orthodontic treatment,all the patients were scanned by T-Scan ?I system.Meanwhile,all the volunteers were measured by T-Scan ?I system.At the beginning,all the patients wear the fixed appliances on permanent tooth,with no extraction.After the anterior teeth bite was open,while the posterior stable occlusion established.All the patients and volunteers were scanned by T-Scan ?I system.The data was compared and analyzed by SPSS 24 software.ResultsThe results of T-Scan ?I system are as follow.Maximum intercuspid positionOcclusal time: Before and after aligning and leveling,occlusal time reduced(0.60±0.29)s.Before treatment,the occlusal time of treatment group was higher than of control group(t=9.111).After treatment,the occlusal time of treatment group was higher than of control group(t=4.062).The changes had statistically difference(P <0.05).Occlusal force distribution: Before treatment,the force of class I subgroup(t=-4.685)was lower than of control group,with of anterior teeth(t=5.027)higher,of posterior teeth(t=-7.471)lower and of canine teeth and premolar(t=-4.571)lower.The force of class ? subgroup(t=4.673)was higher than of control group,with of anterior teeth(t=5.119)higher,of canine teeth and premolar(t=13.636)higher.After treatment,the force of anterior teeth(t=-5.030)was lower than of control group,with of canine teeth and premolar(t=-3.337)lower in class I subgroup.The force of anterior teeth(t=-3.213)was lower than of control group,with of canine teeth and premolar(t=6.048)higher in class ? subgroup.Before treatment,the force of class ? subgroup(t=-7.508)was higher than of class I subgroup,with of anterior teeth(t=-2.999)higher,of posterior teeth(t=-5.557)higher and of canine teeth and premolar(t=-7.187)higher.After treatment,the force of class ? subgroup(t=-7.005)was higher than of class I subgroup,with of posterior teeth(t=-5.557)higher.After treatment,the force of Class I subgroup increased(7.26±4.89)%,with of anterior teeth decreased(4.89±4.53)% and of posterior teeth increased(6.61±11.44)%.After treatment,the force of Class ? subgroup decreased(7.22±4.87)%,with of anterior teeth decreased(10.43±7.28)%,of canine teeth and premolar decreased(10.43±7.28)% and of posterior teeth increased(10.43±7.28)%.The changes had statistically difference(P<0.05).Occlusal contact number: Before treatment,the number of class I subgroup(t=2.733)was higer than control group,with of anterior teeth(t=3.774)higher.The number of class ? subgroup(t=-6.677)was lower than control group,with of anterior teeth(t=4.103)higher,of posterior teeth(t=-9.212)lower and of canine teeth and premolar(t=-5.469)lower.After treatment,the number of class I subgroup(t=-2.091)was lower than control group,with of anterior teeth(t=-5.055)lower and of canine teeth and premolar(t=-4.725)lower.The number of class ? subgroup(t=-4.272)was lower than control group,with of anterior(t=-6.220)lower and of canine teeth and premolar(t=-5.365)lower.Before treatment,the number of posterior teeth(t=7.125)of class I subgroup was higher than of class ? subgroup,with of canine teeth and premolar(t=8.758)higher.After treatment,the number of posterior teeth(t=3.329)of class I subgroup was higher than of class ? subgroup.After treatment,the number of class I subgroup decreased(25.14±19.07),with of anterior teeth(21.79±11.45)decreased and canine teeth and premolar(13.79±11.92)decreased.The number of anterior teeth(21.50±4.69)decreased of class ? subgroup,with of posterior teeth(23.71±13.26)increased.The changes had statistically difference(P<0.05).COF: After treatment,the COF of observation group(t=-5.891)was lower than of control group.The COF of observation group decreased(5.86±8.64)mm.The changes had statistically difference(P<0.05).Protrusive edge-to-edge contact positionDisclusion time: Before and after treatmen,disclusion time reduced(0.43±0.25)s.Before treatment,disclusion time(t=8.853)of treatment group was higher than of control group.After treatment,disclusion time(t=3.528)of treatment group was higher than of control group.The changes had statistically difference(P <0.05).Occlusal force distribution: Before treatment,the force of class I subgroup(t=-18.448)was lower than of control group,with of class ? subgroup(t=18.421) higher.After treatment,the force of class I subgroup(t=-15.317)was lower than of control group,with of class ? subgroup(t=15.293)higher.Before treatment,the force of class I subgroup(t=-37.913)was higher than of class ? subgroup.After treatment,the force of class I subgroup(t=-5.557)was higher than of class ? subgroup.The changes had statistically difference(P<0.05).After treatment,the force of class I subgroup increased(2.86±8.60)%,with of class ? subgroup decreased(2.86±8.60)%.The changes had no statistically difference(P>0.05).Occlusal contact number: Before treatment,the number of class I subgroup(t=-10.539)was lower than of control group,with of class ? subgroup(t=2.283)higher.After treatment,the force of class I subgroup(t=-2.960)was lower than of control group,with of class ? subgroup(t=2.627)higher.After treatment,the number of class I subgroup increased(1.57±1.70).The changes had statistically difference(P<0.05).Before and after treatment,the number of class I subgroup(t=0.325 and 0.400)was higher than of class ? subgroup.The changes had no statistically difference(P>0.05).Left edge-to-edge position(Class ? Subgroup)Disclusion time: Before and after treatment,the time of observation group(t=6.406 and 9.452)was higher than of control group.The changes had statistically difference(P <0.05).After treatment,the time increase(0.10±0.25)s.The changes had no statistically difference(P>0.05).Occlusal force distribution: Before treatment,the force of working side(t=-3.786)was lower than of control group,with of non working side(t=3.786)higher.The changes had statistically difference(P<0.05).After treatment,the force of working side(t=-1.942)was lower than of control group,with of non working side(t=1.942)higher.The changes had no statistically difference(P>0.05).After treatment,the force of working side increase(2.78±4.52)%,with non working side decreased(2.78±4.52)%.The changes had statistically difference(P<0.05).Occlusal contact number: Before and after treatment,the number of working side(t=-8.033 and-7.042)was lower than of control group.The changes had statistically difference(P<0.05).After treatment,the number of working side decreased(0.71±6.62),with non working side increased(0.14±1.35).The changes had no statistically difference(P>0.05).Right edge-to-edge position(Class I Subgroup)Disclusion time: Before and after treatment,the time of observation group(t=6.201 and 4.587)was higher than of control group.The changes had statistically difference(P <0.05).After treatment,the time increase(0.05±0.25)s.The changes had no statistically difference(P>0.05).Occlusal force distribution: Before treatment,the force of working side(t=-4.407)was lower than of control group,with of non working side(t=4.407)higher.The changes had statistically difference(P<0.05).After treatment,the force of working side(t=2.118)was higher than of control group,with of non working side(t=-2.118)lower.The changes had statistically difference(P<0.05).After treatment,the force of working side increase(14.64±26.74)%,with non working side decreased(19.55±15.20)%.The changes had statistically difference(P<0.05).Occlusal contact number: Before treatment,the number of working side(t=-9.316)was lower than of control group,with of non working side(t=4.039)higher.After treatment,the number of working side was lower(t=-6.180)than of control group.After treatment,the number of working side decreased(18.93±23.06),with non working side increased(2.14±2.63).The changes had statistically difference(P <0.05).ConclusionsFor Class ? division 2 malocclusion,before and after aligning and leveling,there was significant changes about the dental and skeletal characteristics.The standard orthodontic treatment in the malocclusion patients could enhance the correction of anterior deep overbite.For Class ? division 2 subdivision malocclusion,before and after aligning and leveling,there was obvious improvement about the occlusal time,disclusion time,occlusal force distribution and occlusal contact number.The standard orthodontic treatment in the malocclusion patients could eliminate some obvious imblance occlusion factors.The T-Scan ?I system could be expected to become a useful way to analyze the stability of occlusal movement before and after aligning and leveling. |
PDF Full Text Request