Partial coverage restoration systems on molars – comparison of failure load after exposure to a mastication simulator

Abstract

This in vitro study evaluated the failure load of partial coverage restorations (PCR) made of various materials cemented on natural molars after exposure to the mastication simulator. Sixty-four maxillary molars were divided into four groups of 16 test specimens each. The specimens in one group remained unprepared (group NP); the teeth in the other groups were prepared equally according to standardized guidelines and restored with the following PCR: Group GO (Gold-Pontor-MPF; Metaux Precieux SA, Metalor, Neuchatel, Switzerland), group TA (Targis; Ivoclar Vivadent AG, Schaan, Liechtenstein) and group EM (IPS-Empress; Ivoclar Vivadent AG). The restorations in group GO were cemented conventionally, while those in groups TA and EM were luted adhesively. Groups NP and GO served as control groups. All test specimens were subjected to 1.2 million cycles (F = 49 N) in a mastication simulator. Subsequently, all test specimens were loaded occlusally until fracture occurred using an universal testing machine. All specimens withstood the masticating simulation. The median (IQR = x(0.25)-x(0.75)) failure loads were as follows: group NP: 1960.3(1480.5-2227.5) N, group TA: 1478.6(1293.4-1856.7) N and group EM: 1400.1(1043.1-1721.6) N. All test specimens of group GO achieved fracture strength values which exceeded a fracture load of 5500 N. The values of group GO were statistically significantly higher than those of groups NP, TA and EM (P < 0.00001). Furthermore, the results of group NP were significantly higher (P = 0.0226) than those of group EM. The results of groups NP and TA (P = 0.2022) as well as of groups TA and EM (P = 0.5340) did not differ significantly. The median values of all PCR systems obtained were within the limits of clinical acceptance. Long-term clinical investigations which take additional parameters into consideration are required before the composite-based Targis(R) (Ivoclar Vivadent AG) material can be recommended for indirect PCR.

Influence of adhesive techniques on fracture resistance of endodontically treated premolars with various residual wall thicknesses

“…Other authors have stated that cusp coverage does not strengthen premolars restored with composite onlay 32 or molars with ceramic restorations. 42 This may be due either to the different axial direction of the compressive load used in these studies, or to the different indirect restoration, which involved only a buccal cusp. Moreover, in this study, the insertion of a fiber post within the cuspal coverage restoration did not significantly increase fracture resistance, 19505-rev3-figs edits 13 probably due to the adequate dispersion of compressive stresses already provided by the composite overlay.…”

Fracture behaviors of monolithic lithium disilicate ceramic crowns with different thicknesses

“…Therefore, in the present study, all the crown patterns were fabricated by CAD/CAM technology using PMMA material for accurate control of crown thickness. With the consideration of the fact that the individual differences of the human teeth such as the dimensions, form, and quality may increase the variability of the fracture resistance, 33 the PMMA molar abutments fabricated by CAD/CAM technology ensured the homogeneity and uniformity in each group in the present study. Besides, articial periodontium was not applied to surround the abutment root as some authors postulated that single crowns with articial periodontium would reduce the axial force when the specimen moved in the surrounding elastic layer, and the consequent mobility was neither regulated nor optimized.…”

Fracture Resistance of Teeth Restored With All-ceramic Inlays and Onlays: An In Vitro Study

“…10 The adhesive technique allows dental professionals to restore the morphology, esthetic appearance, and original mechanical loading capacity of natural teeth. 11,12 The use of ceramics with adhesive techniques permits the preservation of tooth structure and more esthetic restorations in posterior teeth. [13][14][15][16] Zirconia is a crystalline dioxide of zirconium.…”