Assessing the Curve of Spee in Permanent Dentition in Class I, II, III Malocclusions and its Relation with Overjet and Overbite

Abstract

Introduction: The curve of spee is very important in complete oral reconstructions and can be used as a reference for prosthetic and orthodontic reconstructions. This study assessed the curve of spee in the maxilla and mandible and its relationship with the overjet and overbite in class I, II, and III malocclusions in Iranian population. In this descriptive cross- sectional study, 75 pairs of dental casts with permanent dental system and having second molars, available in the clinic of Khorasgan Azad University and private orthodontic offices were selected and divided into three groups of 25 based on malocclusion I, II, and III.
 Materials & Methods: In this descriptive cross- sectional study, 75 pairs of dental casts with permanent dental system and having second molars, available in the clinic of Khorasgan Azad University and private orthodontic offices were selected and divided into three groups of 25 based on malocclusion I, II and III. The radius and depth of curve of spee were obtained. Radius of the curve of spee, the tip of canine cusps, the mesiobuccal of the first molars, and the distobuccal cusps of the second molars were joined together in the form of an arch. To measure the depth of curve of spee, the reference plan was drawn from buccal canine cusp to distobuccal cusp of the second molars. The perpendicular lines were drawn from this line to the edge of the premolars cusp, the first molar and the second molar mesiobuccal cusp and the deepest part was regarded for the measurements. Overjet was measured as an average of 6 upper anterior teeth and overbite as an average of 4 anterior lower teeth and the values of radius and depth of horseshoe curvature and overbite and overjet values were analyzed by One-way ANOVA and Tukey test and Correlation between data was also examined by Pearson correlation coefficient test (p value = 0.05).
 Results: In class II malocclusion, overbite values had a significant relationship with radius (p value = 0.02) and depth of the curve of spee (p value = 0.04), in class III malocclusion, overbite values had a significant relationship with the curve of spee (p value = 0.001) had. In class II malocclusion, the curve of spee was deeper and overbite values were higher, and also in the class III malocclusions, a direct relationship existed between the curve of spee and overbite
 Conclusion: Curve of spee effects the values of overjet and overbite, and the presence of increased overbite results from a deep spee curvature.