Study Of Dental Arch Width In Angle Classâ…± Division 1

Angle Classâ…¡Division 1 is a common type of malocclusion incidence of which is about 23% in teenagers of permanent teeth period. It features Classâ…¡relationship molar, generally accompanied with deep overbite,deep overjet and irregularity of maxillary and mandibular dental arch width. many observations hand been made on dental arch width for Classâ…¡Division 1 malocclusion, providing different conclusions. Some scholars believe that width of anterior,middle and posterior dental arch of Classâ…¡Division 1 are all less than that of normal occlusion with a trend of crossbite in posterior teeth. Some concluded that although width of normal maxillary molar was greater than Classâ…¡Division 1, the width of mandibular canines less than that of Classâ…¡Division 1. In this study, 3DSS- STDC- II Scanner was used to scan the models of normal occlusion and class Classâ…¡Division 1 malocclusion .Then, width of dental arch was measured to observe the morphological characteristics of arch width of Classâ…¡Division 1 malocclusion. The experiments were divided two stages as following:Experiment 1:Compared Study of Dental Arch Width between Angle Class â…¡Division 1 and Normal Occlusion.Objective: To observe the characteristics of arch width of Angle classâ…¡,division 1 malocclusion.Methods: 60 patients with Angle class II division I malocclusion and 60 persons with normal occlusion were selected, ages between 12-16 years old.Study models were routimely made. After the study models being scanned by 3DSS,the data were treated by image fitting with Geomajic software. The width of anterior,middle, posterior segment of the upper and lower dental arch was measured, then the difference of arch width between Angle classâ…¡division1 and normal occlusion was analyzed.Results:(1)Boys with normal occlusion had statistically significant wider dental arch width values on the upper posterior dentition and the lower anterior dentition than girls'counterparts. (2) In addition, boys with Classâ…¡Division 1 malocclusion also had statistically significant wider lower posterior dental arch width than girls'counterparts. (3) The palatal upper posterior dental width values on the normal occlusion were statistically significantly larger than those on the Classâ…¡Division 1 malocclusion for both sexes.Conclusion: There was centain differences between the arch width in upper and lower arch in Classâ…¡Division 1 malocclusion. Experiment 2: The expanding effect of Quad-Helix on the arch width in Classâ…¡Division 1 malocclusion.Objective: To observe the effect of Quad-Helix on Classâ…¡Division 1 malocclusion in early permanent dentitionMethod: 12 pair of patients of 12~16 years old with Classâ…¡Division 1 malocclusion were treated during 2007-2008 in, whose upper archs were expanded by Quad-Helix appliance the departmant of Orthodontics,Qindu Dental Hospital, Fourth Military Medical University. Scanned with 3DSS Raster Scanner followed by image processing with Geomajic software and measurement of width changes of anterior, middle and posterior dental arch of upper and lower jaws before and after orthodontic treatment.Result: The widths of mandibular anteriors, maxillary molars and premolars were increased significantly after treatment.Conclusion: Quad-Helix appliance is frequently used to expand narrow dental arch clinically. It has the advantages of simple fabrication, convenience for inserting and removing and efficient improvement of dental arch width, which is suitable for patients of Classâ…¡Division 1 with narrow upper arch.