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

Effect of different finishing and polishing systems on surface properties of universal single shade resin-based composites

BACKGROUND

Recently, universal single-shade resin composites have become increasingly available in the dental market. The modification of their composition can have an inadvertent effect on their physical and surface properties, and subsequently determinantal effect on their clinical function and longevity. Therefore, this study aimed to evaluate the effect of different finishing and polishing (F/P) systems on surface roughness (Ra), surface gloss (GU), and Vickers microhardness (VMH) of universal single-shade RBCs.

MATERIALS AND METHODS

Four commercial RBCs were used; the universal single-shade RBCs were Omnichroma, Charisma® Diamond ONE, and Vittra APS Unique, and a conventional nanocomposite Filtek™ Z250 XT was used as a control. The 3 F/P systems were Sof-Lex™ XT, Enhance®/PoGo®, and Diacomp® Plus Twist. A total of 160 discs were used for the 3 F/P system groups for all RBCs (n = 10). After F/P, the Ra, GU, and VMH were assessed. The data were analyzed using 2-way ANOVA at p-value < 0.05.

RESULTS

Significant differences were found among the four RBCs and the 3 F/P systems (p < .000). Omnichroma showed the lowest Ra and acceptable GU, but the lowest VMH. Charisma showed the highest Ra, acceptable GU, and VMH. Vittra showed acceptable Ra, GU, and VMH and Filtek showed the highest GU, VMH, and acceptable Ra.

CONCLUSION

Although conventional nanohybrid RBC (Filtek Z250 XT) showed better GU and VMH values, the universal single-shade RBCs demonstrated comparable surface properties. The highest GU & VMH and lowest Ra were achieved by Diacomp followed by Enhance and Soflex.

Color stability and surface roughness of resin-ceramics with different surface treatments: A systematic review and meta-analysis of in vitro studies

STATEMENT OF PROBLEM

Surface treatments for resin-ceramics have been developed to obtain a smooth surface and improve color stability. However, a consensus on the best treatment for these materials is lacking.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate the color stability and roughness of glass-ceramics versus resin-ceramics with different surface treatments.

MATERIAL AND METHODS

The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed, and the study was registered in the open science framework (OSF) for in vitro studies. The population, intervention, control, and outcome (PICO) question was "Is there a difference in color stability and roughness between resin-ceramic vs vitreous ceramics in different surface treatment protocols?" A literature search was performed in PubMed/MEDLINE, Embase, Web of Science, Scopus, Cochrane Library, and ProQuest databases up to January 2023. The Joanna Briggs Institute's critical assessment guidelines for quasi-experimental studies were used for quality assessment. The meta-analysis was based on the inverse variance (IV) method (α=.05).

RESULTS

A total of 18 laboratory studies were published between 2015 and 2022, with a total of 2160 specimens, all of which were analyzed qualitatively. The meta-analysis indicated significantly less optical alteration for lithium disilicate ceramics (P<.01; MD: 2.69; 95% CI: 2.00-3.39; I²=89%, P<.01), even when compared with resin-ceramics with polish or sealants (P<.01; MD: 2.45; 95% CI: 1.59-3.30; I²=87%, P<.01) and (P<.01; MD: 3.24; 95% CI: 2.02-4.47; I²=89%, P<.01), while there was no significant difference in surface roughness (P=.08; MD: -0.71; CI 95%: -1.52 to 0.09; I²=87%, P<.01) (P=.33; MD: -0.31; CI 95%: -0.94 to 0.32; I²=87%, P<.01), respectively.

CONCLUSIONS

Resin-ceramics that have been polished or treated with sealants have lower color stability than glazed glass-ceramics; however, they are similar in terms of surface roughness.

Retention Assessment of High Performance Poly-etheretherketone Removable Partial Denture Frameworks Constructed by Various Techniques (in vitro Study)

STATEMENT OF THE PROBLEM

Poly-etheretherketone is a novel material used in the construction of the removable partial dentures frameworks instead of the metal frameworks. This material can be fabricated by various techniques. Most common methods are the injection molding or Computer Aided Design/Computer Aiding Manufacturing (CAD/CAM) milling techniques. The fabrication technique may affect the adaptation of the frameworks by influencing the retention.

PURPOSE

To assess the effect of the processing techniques of high performance Poly-etheretherketone either by injection molding (pressing) or CAD/CAM milling techniques on removable partial denture frameworks retention for rehabilitation of upper class I Kennedy classification.

MATERIALS AND METHOD

This in vitro study was performed on one epoxy resin model representing the partially edentulous maxillary arch with natural teeth extending from first premolar to first premolar. First premolars and canines were reduced to receive porcelain fused to metal crowns with 0.50mm mesio-buccal retentive undercuts, distal guiding planes and mesial occlusal rest seat on first premolars and cingulum rest seat on canines. Considering the construction technique of frameworks, twenty samples were divided into two groups. In the group I, ten frameworks were fabricated by injection molding, and in the group II, ten frameworks were fabricated by CAD/CAM. The removal and insertion was carried out at 120, 720 and 1440 cycles for both groups, respectively. The retention values were measured by using Universal Testing Machine before cycling and after each interval.

RESULTS

Independent t-test showed significant difference on retention at different simulation cycles between groups. Group II exhibited significantly less retention than group I (p< 0.001), while comparing the retention at different cycles within each group by paired sample t-test exhibited significant decrease of retention till the end of the cycling (p< 0.001).

CONCLUSION

From the retention point of view, high performance poly-etheretherketone frameworks fabricated by injection molding technique provided a promising method over CAD/CAM technique milling method.

Review on Polymer, Ceramic and Composite Materials for CAD/CAM Indirect Restorations in Dentistry-Application, Mechanical Characteristics and Comparison

The aim of this review article is to present various material groups, including ceramics, composites and hybrid materials, currently utilized in the field of CAD/CAM. The described technology is amongst the most important in modern prosthetics. Materials that are applicable in this technique are constantly tested, evaluated and improved. Nowadays, research on dental materials is carried out in order to meet the increasing demand on highly aesthetic and functional indirect restorations. Recent studies present the long-term clinical success of restorations made with the help of both ceramic and composite materials in the CAD/CAM method. However, new materials are developed and introduced that do not have long-term in vivo observations. We can outline a monolithic polymer-infiltrated ceramic network and zirconia teeth support that show promising results to date but require further assessment. The materials will be compared with regard to their mechanical and clinical properties, purpose, advantages and limitations.