A Comparative Evaluation of Dimensional Stability and Accuracy of Zinc Oxide Eugenol Paste and Modelling Wax as Interocclusal Recording Materials. An In Vitro Study

Background: Accurate interocclusal records are essential for the successful fabrication of indirect dental prostheses. Dimensional stability of the recording material plays a critical role in maintaining the accuracy of maxillomandibular relationships. Among the commonly used interocclusal recording materials, Zinc Oxide Eugenol (ZOE) paste and modelling wax continue to be widely employed because of their availability and ease of manipulation. Objective: To compare the dimensional stability and accuracy of Zinc Oxide Eugenol paste and modelling wax as interocclusal recording materials at different time intervals. Methods: This comparative in vitro study was conducted in the Department of Prosthodontics, Faculty of Dentistry, BSMMU, Dhaka from June 2009 to June 2010. Forty duplicated disks were prepared from a custom-made stainless-steel die. Ten specimens each were fabricated using polyvinyl siloxane, ZOE paste, alginate and modelling wax. For the present comparison, data from Group B (ZOE paste) and Group D (modelling wax) were analyzed. Horizontal linear distances between reference lines A and C were measured using a travelling micrometer microscope at 1 hour, 24 hours, 48 hours and 72 hours. Results: Both ZOE paste and modelling wax demonstrated progressive dimensional changes over time. In Group B, mean horizontal distance decreased from 5.81±0.06 mm at 1 hour to 5.51±0.07 mm at 72 hours. In Group D, the corresponding values decreased from 5.69±0.08 mm to 5.47±0.03 mm. All intragroup comparisons showed statistically significant dimensional changes (p<0.05). Intergroup comparison revealed significant differences at 1 hour and 48 hours, whereas differences at 24 and 72 hours were not statistically significant. Conclusion: Zinc Oxide Eugenol paste demonstrated superior dimensional stability compared with modelling wax and may be considered a more reliable interocclusal recording material when delayed articulation is anticipated.