Evaluation of five CAD/CAM materials by microstructural characterization and mechanical tests: a comparative in vitro...

Current dental restoration techniques rely on materials that either lack sufficient mechanical strength or degrade over time. Traditional glass-matrix ceramics and resin composites have known limitations, including susceptibility to fracture and wear. Recent innovations have introduced polymer-infiltrated ceramics and nano-ceramic resins as alternatives. These materials aim to balance durability with biocompatibility. However, the performance of these new materials remains unclear in long-term clinical settings. Prior research has shown that mechanical properties like flexural strength and fracture toughness are critical for dental applications. No prior work had resolved how these new CAD/CAM materials perform under simulated aging conditions. This gap motivated the current study to compare the mechanical and microstructural characteristics of five CAD/CAM materials. The uncertainty around material behavior under thermocycling led to the need for in vitro analysis. The study aimed to provide data on how simulated aging affects material properties. This paper's contribution is to offer a comparative framework for material selection in dental restorations.

The study aimed to assess the mechanical and microstructural properties of five CAD/CAM materials under controlled and simulated aging conditions. The specific problem addressed was the lack of comparative data on how these materials perform when exposed to thermocycling. The motivation stemmed from the need to understand material behavior under conditions that mimic oral environments. The authors sought to determine how simulated aging affects mechanical properties like flexural strength and fracture toughness. The study also aimed to evaluate the impact of thermocycling on polymer-infiltrated ceramics and nano-ceramic resins. The goal was to provide clinicians and researchers with evidence-based insights into material performance. The study focused on five specific CAD/CAM blocks from different manufacturers. The findings could inform material selection for dental restorations.

The study involved five CAD/CAM materials: VITA Enamic, Lava Ultimate, IPS e.max CAD, IPS Empress CAD, and VITA Mark II. A total of 22 specimens were prepared from each material. Two specimens per group were analyzed using XRD and EDS for microstructural evaluation. The remaining specimens were divided into two subgroups of ten each. One subgroup underwent thermocycling between 5°C and 55°C for 10,000 cycles. The other subgroup remained unexposed. Mechanical tests measured flexural strength, Vickers hardness, and fracture toughness. Statistical analysis included two-way ANOVA, one-way ANOVA, Tukey's HSD, and Student's t tests at α = .05. Fractured specimens were examined using SEM to assess surface morphology. The experimental design allowed for comparison of material performance under different conditions.

VITA Mark II showed the highest Vickers microhardness (p < .001) but had the lowest flexural strength and fracture toughness (p < .05). IPS e.max CAD exhibited the highest flexural strength (p < .001) and fracture toughness (p < .001) among all materials. Lava Ultimate and VITA Enamic showed reduced mechanical properties after thermocycling (p < .05). Their microhardness, flexural strength, and fracture toughness were similar to VITA Mark II and IPS Empress CAD groups. Thermocycling had a more significant impact on polymer-polymer composite materials than on glass ceramics. The statistical analysis confirmed significant differences between material groups. SEM analysis revealed surface characteristics that correlated with mechanical performance. The results highlight the importance of material composition in determining mechanical behavior.

The study found that simulated aging through thermocycling significantly affected polymer-infiltrated ceramics and nano-ceramic resins more than glass ceramics. VITA Mark II had the highest microhardness but lowest flexural strength and fracture toughness. IPS e.max CAD demonstrated superior mechanical properties. Lava Ultimate and VITA Enamic showed reduced performance after thermocycling. The authors suggest that material composition influences how CAD/CAM materials respond to aging. These findings imply that material selection should consider both mechanical properties and aging effects. The results do not suggest that one material is universally superior to others. The authors emphasize the need for further studies on material behavior in clinical settings.