Surface degradation and digital volumetric loss in ceramic and hybrid CAD/CAM surfaces after simulated toothbrushing with activated charcoal vs. whitening toothpaste.

objectiveActivated charcoal (AC) toothpaste has gained popularity for its whitening properties. However, its abrasive effect on computer-aided design and computer-aided manufacturing (CAD/CAM) surfaces compared to conventional whitening toothpaste (WH) remains unclear. This study aimed to evaluate and compare the abrasive impact of AC and WH toothpastes on the surfaces of CAD/CAM materials. MATERIALS AND

methodsA total of ninety-six specimens were prepared from four different types of CAD/CAM materials: Feldspathic ceramic (Vita Mark II, Group VM), lithium disilicate-reinforced glass ceramic (IPS e.max CAD, Group EMC), polymer-infiltrated network hybrid ceramic (Vita Enamic, Group VE), and resin nanoceramic (Lava Ultimate, Group LU). Each specimen was prepared to a thickness of 2 mm and manually polished. Initial surface roughness was determined with profilometric analyses. The materials were then divided into subgroups (n = 8) based on three different brushing mediums: distilled water (DW), whitening toothpaste (WH), and activated charcoal toothpaste (AC). A toothbrushing simulator was used to simulate short-term (10,000 cycles-10k, about 1 year) and long-term (30,000 cycles-30k, about 3 years) brushing. After simulation, roughness measurements were repeated on the brushed surfaces, and changes in surface topography were evaluated using scanning electron microscopy images. Volumetric loss was calculated via digital volumetric analyses. Two-way repeated mixed analysis of variance was conducted to assess the effects of material type, brushing medium, and brushing time on the surface roughness, with significance set at α = 0.05.

resultsGroup VM exhibited a significant increase in surface roughness after 10k cycles with AC, surpassing the clinical threshold (Ra > 0.2 μm). EMC showed no change at 10k but demonstrated a statistically significant increase at 30k cycles, also exceeding the threshold. Hybrid ceramics displayed increased roughness values, but all remained below the clinically relevant limit. Brushing with AC tended to produce greater roughness than WH in all materials. Digital volumetric analysis revealed that VM, VE, and LU groups experienced comparable volumetric loss, whereas EMC showed the least volumetric loss among all materials.

conclusionAC-containing toothpaste increased surface roughness and volumetric loss in CAD/CAM materials, with more pronounced effects than whitening toothpaste. Feldspathic ceramics were particularly vulnerable to surface roughening, lithium disilicate showed higher resistance but was affected in the long term, while hybrid ceramics exhibited more evident volumetric loss. Therefore, the use of charcoal-based toothpaste is questionable, especially for patients with ceramic restorations.