Abstract: Objective: To explore the application of silicone rubber impression positioning paralleling technique in clinic practice. Methods: 24 periodontitis patients needed repair of periodontal bone defects and 24 endodontic patients needed root canal treatment were performed silicone rubber impression positioning paralleling technique and bisecting-angle technique respectively. The length of the tooth along the long axis of the tooth and the width of tooth at enamelo-cemental junction were measured on the digital periapical radiograph,which were divided into anterior teeth + maxillary molar group and mandibular molar group. Paired t test and reliability test was used to compare the differences and correlations of the periapical radiograph before and after treatment, SPSS 22.0 was used for analysis. Results: Although there was no significant differences of the length and width on periapical radiograph before and after treatment using paired t-test(P>0.05), compared with the bisecting-angle technique, the silicone rubber impression positioning paralleling technique showed stronger correlation, which suggested silicone rubber impression positioning paralleling technique was more stable. Conclusion: The silicone rubber impression positioning paralleling technique is reliable, stable, and relatively simple technique. It is suitable for the diagnosis and analysis of various dental diseases requiring longitudinal quantitative comparison.

Key words: Silicone rubber impression, Paralleling technique, Bisecting-angle technique