Influence of Energy Drinks on Surface Microhardness of CAD/CAM Materials

Objectives: The purpose of this in vitro study was to evaluate the influence of energy drinks on surface microhardness (HV) of 3 mechanically polished CAD/CAM materials; a resin infused hybrid ceramic, Vita Enamic (ENA; Vita Zahnfabrik), a nano-particle and nano-cluster-filled resin, Lava Ultimate Restorative (LVU; 3M ESPE), a nano-particle-filled resin, Cerasmart (CES; GC) and a nanohybrid composite Essentia (ES; GC) used as a control over a two month period.
Methods: 18 CAD/CAM blocks were cut into 12x14x16mm specimens (n:30 from each type of material), and wet finished with 320-grit and then polished with 600-800-1200-grit SIC papers in order to simulate intra-oral finishing and polishing. A total of 30 composite specimens were prepared using a metal mold in 2mm thickness and 10 mm in diameter and polymerized using a LED curing unit (Demi Ultra; Kerr), stored in distilled water at 37 ^oC for 24 hours. Initial HV of the specimens were evaluated with a microhardness tester (Shimatzu). Then the specimens in each group were randomly divided into three groups according to one of the energy drinks (Burn BR); n:10, Redbull (RB); n:10) and control (n:10). Control group specimens were aged in distilled water while experimental group specimens were immersed in energy drinks for 2 minutes daily and HV evaluations were performed after one and two months aging. Data were analyzed by three-way ANOVA and a post-hoc Bonferroni test (p<0.05).
Results: All the tested materials showed significant HV reduction in distilled water and energy drinks after one and two months aging (p=0.0001). Energy drinks yielded higher HV reduction than distilled water for all the tested materials at one and two months evaluations (p=0.0001). The difference between two energy drinks were not significant for CSE and ENA (p>0.05) while BR resulted in higher HV reduction than RB in LVU and ES groups at one and two months (p<0.05).
Conclusions: The effect of energy drinks on surface microhardness of CAD/CAM materials depends on the composition of the material. Similar to direct composite, resin based CAD/CAM materials are also prone to degradation.