Effect of in-office bleaching on surface roughness of additively versus subtractively manufactured tooth-colored materials used for fixed definitive prostheses

In-office dental bleaching is recognized as a conservative and effective approach for achieving tooth whitening. Although previous studies have investigated additively manufactured composite resins, there is limited knowledge in terms of the impact of in-office bleaching on the surface roughness of these materials. The goal of this study was to determine the impact of in-office bleaching on the surface roughness of tooth-colored materials used for definitive fixed prostheses, which were fabricated via two different techniques: subtractive and additive manufacturing. Two additively manufactured resins, Varseosmile crown plus (VS) and Crowntec (CT), and one subtractively manufactured polymer-infiltrated ceramic, Vita enamic (EN), were applied to fabricate rectangular-shaped specimens (14 × 12 × 1 mm) (n = 20). The surface roughness of each sample was measured via a noncontact profilometer before the in-office bleaching material (control) was processed. The bleaching agent (BMS White, Pisa, Italy) was then applied in three consecutive sessions of 15 min each (total 45 min), after which surface roughness was measured again via the same profilometer. For the purpose of statistical evaluation, one-way ANOVA and paired-samples t tests were performed. A p value < 0.05 was considered statistically significant, whereas a p-value < 0.001 was considered highly statistically significant. The mean surface roughness µm prior to exposure to the bleaching material did not differ markedly among the groups. Following application of the bleaching agent, both the VS and CT groups demonstrated a notable increase in surface roughness (P < 0.001). In contrast, the EN group demonstrated a nonsignificant change in surface roughness. The tested additively manufactured resins had greater surface roughness than did the subtractively manufactured polymer-infiltrated ceramic, which was more resistant to roughening after all the in-office bleaching procedures were completed.