RCT on posterior partial crowns made by two different lithium disilicate materials: 8-year results

Background This trial wants to evaluate the clinical behavior of two lithium disilicate systems after 8 years of clinical service. Methods 60 patients in need of receiving a partial adhesive crown on natural abutment posterior teeth were made. 60 restorations were realized. Sample crowns were divided into two groups: Group 1 IPS e.max press (Ivoclar-Vivadent, Schaan, Liechtenstein), and Group 2 Initial LiSi press (GC Co., Tokyo, Japan). The restorations were followed up for 8 years, and the FIT evaluation was used FOR each recall to evaluate their clinical performances. Accordingly, with the FIT system, 7 clinical parameters (Interproximal, Occlusion, Design, Mucosa, Bone, Biology and Margins) WERE evaluated, using a 0–1-2 scoring scheme, by an oral radiograph and occlusal and buccal pictures. Statistical analysis was made using Mann-Whitney 'U' test and the level of significance was set at p < 0.05. Also, the "success" of the crowns (restoration in place without any biological or technical complication) and "survival" (restoration still in place with biological or technical complication) were evaluated. Results Regarding FIT scores, when compared to the 3-years results all partial crowns showed a slight decrease in scores, mainly due to bone loss of alveolar crest in the radiographic evaluation and consequent recession of gingival tissue. Similarly happened to several partial crowns of both groups about interproximal contact parameters, were also related to a modification of the contour of the crowns. Any way all evaluated parameters showed high scores, and no statistically significant differences were noted between the two groups in any of the assessed variables (p > 0.05). All FIT scores were compatible with the outcome of clinical success no one restoration was replaced or repaired and the survival and success rate were 100%. Conclusions The two groups of lithium disilicate systems showed similar results after 8 years of clinical service and no statistically significant differences were found. Both systems were shown to be clinically predictable and reliable.