J Adv Prosthodont.  2019 Apr;11(2):128-137. 10.4047/jap.2019.11.2.128.

Physical characteristics of ceramic/glass-polymer based CAD/CAM materials: Effect of finishing and polishing techniques

• Ekici MA
• Egilmez F
• Cekic-Nagas I
• Ergun G

• KMID: 2444147
• DOI: http://doi.org/10.4047/jap.2019.11.2.128

Abstract

PURPOSE
The aim of this study was to compare the effect of different finishing and polishing techniques on water absorption, water solubility, and microhardness of ceramic or glass-polymer based computer-aided design and computer-aided manufacturing (CAD/CAM) materials following thermocycling.
MATERIALS AND METHODS
150 disc-shaped specimens were prepared from three different hybrid materials and divided into five subgroups according to the applied surface polishing techniques. All specimens were subjected up to #4000 grit SiC paper grinding. No additional polishing has been done to the control group (Group I). Other polishing procedures were as follows: Group II: two-stage diamond impregnated polishing discs; Group III: yellow colored rubber based silicone discs; Group IV: diamond polishing paste; and Group V: Aluminum oxide polishing discs. Subsequently, 5000-cycles of thermocycling were applied. The analyses were conducted after 24 hours, 7 days, and 30 days of water immersion. Water absorption and water solubility results were analyzed by two-way ANOVA and Tukey post-hoc tests. Besides, microhardness data were compared by Kruskal-Wallis and Mann-Whitney U tests (P<.05).
RESULTS
Surface polishing procedures had significant effects on water absorption and solubility and surface microhardness of resin ceramics (P<.05). Group IV exhibited the lowest water absorption and the highest microhardness values (P<.05). Immersion periods had no effect on the microhardness of hybrid ceramic materials (P>.05).
CONCLUSION
Surface finishing and polishing procedures might negatively affect physical properties of hybrid ceramic materials. Nevertheless, immersion periods do not affect the microhardness of the materials. Final polishing by using diamond polishing paste can be recommended for all CAD/CAM materials.

Keyword

Computer-aided design and computer-aided manufacturing (CAD/CAM); Hybrid ceramics; Dental polishing; Water hardness; Water solubility

MeSH Terms

Absorption
Aluminum Oxide
Ceramics
Computer-Aided Design
Dental Polishing
Diamond
Immersion
Rubber
Silicon
Silicones
Solubility
Water
Aluminum Oxide
Diamond
Rubber
Silicon
Silicones
Water

Figure

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  Fig. 1 Schematic study design.

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  Fig. 2 Box-plot diagram of the distribution of WSP data according to tested groups. The central line in the box represents the median, and the box represents the middle 50% of values. The whiskers show the extent of the data. The black unfilled circles represent outliers.

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  Fig. 3 Box-plot diagram of the distribution of WSO data according to tested groups. The central line in the box represents the median, and the box represents the middle 50% of values. The whiskers show the extent of the data. The black unfilled circles represent outliers.

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  Fig. 4 Representative SEM micrographs in order to show the surface morphology of CS (GC Cerasmart) in each polishing group at × 4000 magnifications. (A) Group I (Control), (B) Group II (diamond impregnated two-stage spiral polishing system) (C) Group III (yellow colored rubber-based silicon abrasive), (D) Group IV (diamond polishing paste), (E) Group V (aluminum oxide abrasive discs).

• 

  Fig. 5 Representative SEM micrographs in order to show the surface morphology of LU (Lava Ultimate) in each polishing group at × 4000 magnifications. (A) Group I (Control), (B) Group II (diamond impregnated two-stage spiral polishing system), (C) Group III (yellow colored rubber-based silicon abrasive), (D) Group IV (diamond polishing paste), (E) Group V (aluminum oxide abrasive discs).

• 

  Fig. 6 Representative SEM micrographs in order to show the surface morphology of VE (Vita Enamic) in each polishing group at × 4000 magnifications. (A) Group I (Control), (B) Group II (diamond impregnated two-stage spiral polishing system), (C) Group III (yellow colored rubber-based silicon abrasive), (D) Group IV (diamond polishing paste), (E) Group V (aluminum oxide abrasive discs).

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