Clinical fit of all‐ceramic three‐unit fixed partial dentures, generated with three different CAD/CAM systems

Abstract

In this study, the hypothesis was tested that the marginal and internal fit of CAD/CAM fabricated all-ceramic three-unit fixed partial dentures (FPDs) can be as good as in metal-ceramic FPDs. Twenty-four all-ceramic FPDs were fabricated and randomly subdivided into three equally sized groups. Eight frameworks were fabricated using the Digident CAD/CAM system (DIGI), another eight frameworks using the Cerec Inlab system (INLA). Vita Inceram Zirkonia blanks were used for both groups. In a third group frameworks were milled from yttrium-stabilized Zirconium blanks using the Lava system (LAVA). All frameworks were layered with ceramic veneering material. In addition, six three-unit metal-ceramic FPDs served as control group. All FPDs were evaluated using a replica technique with a light body silicone stabilized with a heavy body material. The replica samples were examined under microscope. The medians of marginal gaps were 75 microm for DIGI, 65 microm for LAVA and INLA and 54 microm for the conventional FPDs. Only the DIGI data differed significantly from those of the conventional FPDs. Within the limits of this study, the results suggest that the accuracy of CAD/CAM generated three-unit FPDs is satisfactory for clinical use.

Evaluation of the adaptation of zirconia-based fixed partial dentures using micro-CT technology

“…This finding is in agreement with other studies that investigated the adaptation of Y-TZP FPDs produced with LAVA and other current CAD-CAM systems. 3,5,17,20 An investigation also found significantly different mean gap values as a function of measurement location. 3 The study reported that the occlusal gap width of LAVA three-unit framework was six times larger than the marginal gap width.…”

“…Although the sintering shrinkage of restorations obtained from partially sintered blocks can be compensated by milling enlarged restorations, it is not as yet clear whether this compensation is effective for the production of FPDs with long spans. 4,17 In addition, previous studies reported that the internal adaptation of CAD-CAM restorations is poorer, compared with marginal adaptation. 3,5,17 This finding represents a relevant clinical problem, insofar as wide internal gaps have been associated with decreased fracture strength and loss of retention of the restoration.…”

“…4,17 In addition, previous studies reported that the internal adaptation of CAD-CAM restorations is poorer, compared with marginal adaptation. 3,5,17 This finding represents a relevant clinical problem, insofar as wide internal gaps have been associated with decreased fracture strength and loss of retention of the restoration. 18 There is no standard methodology to measure the marginal and internal adaptation of indirect restorations.…”

Digital dentistry: an overview of recent developments for CAD/CAM generated restorations

“…Thus, production steps 1 and 2 take place in the dental laboratory, while the third step takes place in the centre. 5,8 As a result, the configuration of the prosthe sis remains in the hands of the dental technician. The benefit of outsourcing CAM production is to be found in the small investment requirement, since only the digitalisation tool and soft ware have to be purchased, still having access to a high quality production pro cess.…”

“…5). 8,28 c) Processing in hot isostatic pressing condition Some systems also process zirconium oxide in HIP (hot isostatic pressed) con dition with diamond tools and water cooling. The advantages and disadvan tages are as follows.…”