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Comparison of marginal and internal fit of press-on-metal and conventional ceramic systems for three- and four-unit implant-supported partial fixed dental prostheses: An in vitro study

https://doi.org/10.1016/j.prosdent.2015.01.002Get rights and content

Abstract

Statement of problem

Adaptation is an important factor in the long-term clinical success of implant supported ceramic restorations. Ceramic firings may affect the adaptation of the restoration.

Purpose

The purpose of this study was to compare the marginal and internal adaptation of 3 different restorative materials and the effect of veneering/pressing on the material used for 3- and 4-unit implant supported fixed dental prostheses.

Material and methods

One mandibular epoxy cast was prepared for 3-unit restorations and one for 4-unit restorations. Impressions of the casts were made and 60 stone die casts (30 3-unit, 30 4-unit) produced. The casts were divided into 3 subgroups: group MCR, conventional metal ceramic restorations; group POM, press-on-metal restorations; group ZIR, computer-aided design/computer-aided manufacturing CAD/CAM) zirconia restorations. A replica technique was used to examine the marginal and internal gap values. A total of 2400 measurements were made by making 40 measurements of each restoration. The data were evaluated statistically using analysis of variance and the least significant difference post hoc test (α=.05).

Results

The lowest marginal gaps were found in group POM (81.58 μm) and the highest in group MCR (103.82 μm). The differences in marginal adaptation measurements were found to be statistically significant. The highest values for internal adaptation were found at the occlusal surface in all groups.

Conclusions

Although veneering metal ceramic restorations increased the misfit of the restoration, the marginal discrepancy of the materials (81 to 120 μm) can be considered clinically acceptable.

Section snippets

Material and Methods

Two different partially edentulous mandibular casts were fabricated from epoxy resin (Moravia; Boyman Boya Kimya Ltd). In one of the casts, the mandibular left premolars and first molar teeth were missing, and in the other, the mandibular left premolars and molars were missing. Two implants (Astra Implants, AstraTech; Dentsply Implants) were inserted in the first premolar and first molar region in the first cast, and 2 implants were inserted in the first premolar and second molar region in the

Results

The internal and marginal adaptation measurements of all study groups are shown in Table 1, Table 2, Table 3, Table 4, Table 5.

Mean marginal gap values of 89.60 ±23.43 μm for MCR, 85.57 ±24.31 μm for POM, and 109.30 ±46.44 μm for ZIR restorations were recorded. Marginal gap values recorded in ZIR were significantly higher than those in MCR (P<.05) (Table 1, Table 2). MCRb showed statistically significantly lower marginal gaps than MCRa. ZIRa showed statistically significantly lower marginal

Discussion

Marginal and internal adaptation is considered one of the most important criteria for the clinical success of implant-supported partial fixed dental prostheses.3 In this study, a replica technique was used to evaluate the marginal and internal gaps at different fabrication stages and with different restorative materials. The replica technique is less costly and time consuming than other techniques for generating test specimens.4, 20 In addition, the evaluations can be performed at different

Conclusions

Within the limitations of this study, the following conclusions can be drawn:

  • 1.

    Mean marginal gap measurements were 103.8 μm ±20.6 for conventionally veneered metal ceramic restorations, 81.6 μm ±18.3 μm for press-on-metal ceramic restorations, and 98.2 μm ±34.6 μm for CAD/CAM zirconia restorations. These mean values are considered clinically acceptable.

  • 2.

    When the measurements before and after the fabrication of superstructures were compared, the ceramic veneering process statistically increased

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