Trueness of Four Different Milling Procedures Used in Dental CAD/CAM Systems

Overview

Journal Clin Oral Investig

Specialty Dentistry

Date 2016 Jul 30

PMID 27469100

Citations 30

Authors

Corinna Kirsch

Andreas Ender

Thomas Attin

Albert Mehl

Affiliations

Soon will be listed here.

Abstract

Objectives: Milling is a crucial step in producing restorations using computer-aided design and computer-aided manufacturing (CAD/CAM) systems. In this study the trueness of currently available milling devices was evaluated.

Materials And Methods: Thirty clinical cases (ten inlays, ten crowns, ten onlays) were milled from ceramic blocks using four different milling approaches: five axis with IMES CORiTEC 450i, four axis with CEREC MCXL, four axis with CEREC MCXL-EF and five axis with inLab MCX5. The milled restorations were scanned and the occlusal and inner surfaces compared to the originally calculated 3D surface using difference analysis software. The (90-10 %) / 2 percentile of the distances were calculated and analysed using one-way ANOVA with the post hoc Scheffé test (α = 0.05). Chipping of marginal areas were visually examined and analysed using one-way ANOVA with a post hoc Tamhane test (α = 0.05).

Results: At inner surfaces, the milling trueness of IMES (33.9 ± 16.3 μm), X5 (32.3 ± 9.7 μm) and MCXL-EF (34.4 ± 7.5 μm) was significantly better (p < 0.001) than that of MCXL (62.1 ± 17.1 μm). At occlusal surfaces, MCXL-EF (25.7 ± 9.3 μm) showed significant higher accuracy (p < 0.001) than MCXL (48.7 ± 23.3 μm) and X5 (40.9 ± 20.4 μm). IMES produced the most chipping (p < 0.001).

Conclusions: Five-axis milling devices yield high trueness. MCXL-EF is competitive and may allow chairside fabrication with good milling results.

Clinical Relevance: Accurate milling is required for well-fitting restorations and thereby requires fewer manual finishing steps, yields smaller marginal gaps, resistance to secondary caries and longevity of restorations.

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