ABSTRACT
Background and Objectives: This study was done with the objectives to determine the range of functional zone between the intercuspal positions and edge to edge position, the range of incomplete and complete disclusion of posterior teeth in canine-guided occlusion, and to have a gender comparison and comparison between right and left sides of the obtained values. Materials and Methods: Thirty-five subjects showing canine-guided occlusion and Angle's class I canine and molar relation were chosen for the study. Maxillary midline and a corresponding line on the mandible were marked in maximum intercuspation with marker pen in the patient's mouth. Lines from 1 to 5 mm were marked on maxillary central incisor with marker pen. A dental floss was looped around the distal surface of mandibular last molar and the subject was asked to make left lateral movement (working side) at 1-mm intervals. The point at which floss was freed posteriorly was considered as initial disclusion and the point at which edges of maxillary and mandibular canines contacted was considered as complete disclusion. Results: Most of the male and female subjects in the study showed progressive disclusion on right side and delayed disclusion on left side. The range of complete disclusion was 3-4 mm in males and 2-3 mm in females irrespective of the side. The range of functional zone was 1-4 mm irrespective of side or gender. Interpretation and Conclusion: There is a need to redefine canine guidance in terms of immediate disclusion, delayed disclusion, and progressive disclusion.
ABSTRACT
Objectives: This study aims to compare the curve of Spee in human permanent healthy dentitions in two age groups to the disclusion in the premolar and molar region during protrusion. Materials and Methods: Sixty subjects were chosen and equally divided into two age groups of 18-25 years and 35-44 years. The left side of the mandibular dental casts was photographed using a digital camera to measure the curve of Spee. The canine cusp, mesiobuccal cusp of the first molar and the distal cusp of the second molar were marked and joined to form an arc. Using AUTOCAD software, the radius for this arc was obtained. A protrusive interocclusal record was made using rigid bite registration material to measure the amount of posterior disclusion during edge to edge protrusion. A dial gauge with an accuracy of 1/100 of a millimeter was used to measure the distance between the cusp tip indentations at the region of the buccal cusp of the mandibular 2nd premolar and distobuccal cusp of mandibular 1st molar. The results obtained were statistically analyzed. Results: The radius of curve of Spee increased nonsignificantly with age. The mean disclusion values measured in premolar and molar region showed a nonsignificant decrease with age. Conclusion: As age advances, there is a flattening of the curve of Spee and a concurrent reduction in the disclusion values during protrusion.