ABSTRACT
STATEMENT OF PROBLEM: Modification of the occlusal vertical dimension (OVD) is a significant procedure in prosthodontics. Improper estimation of the space available between opposing teeth may lead to an improper framework design. PURPOSE: The purpose of this clinical study was to evaluate the average opening ratio in the molar area in relation to the extent of opening in the incisor area. MATERIAL AND METHODS: A total 34 adults with a complete dentition and stable occlusion participated in the study. The change in vertical distance was evaluated in 3 areas: between the maxillary and mandibular central incisors, between the maxillary and mandibular canines, and between the maxillary and mandibular first molars. Digital photographs were made at the intercuspal position (ICP) and at a 2-mm and 8-mm OVD increase. The OVD opening was standardized with the aid of a Woelfel sliding guide device. The measurements were made by recording the distance between the maxillary and mandibular teeth at different openings. For calibration and quantitative evaluation of the photographs, image-processing analysis was used. RESULTS: The collected data showed that the average ratio of the opening between the first molars and the opening between the central incisors was 0.73. The average ratio of the opening between the canines and the opening between the central incisors was 0.95. The values were plotted, and a mathematical model was derived. CONCLUSIONS: A vertical dimension opening of 1 mm between the central incisors resulted in 0.73 mm of occlusal clearance in the first molar region and 0.95 mm in the canines.
