Influence of postprinting cleaning duration and glazing agents on the mechanical and surface properties of three-dimensionally printed dental resins: An in vitro study.

STATEMENT OF PROBLEM: The performance of additively manufactured dental resin restorations has been reported to depend on postprocessing, but the combined effects of cleaning duration and surface glazing on mechanical, surface, and optical outcomes remain insufficiently defined.

PURPOSE: The purpose of this in vitro study was to investigate the effects of material composition, cleaning duration, and glazing agents on the flexural strength, surface roughness (Ra), and color stability (ΔE00; CIEDE2000) of 3-dimensionally (3D) printed resin composites.

MATERIAL AND

METHODS

Four A2-shade 3D printed resin composites were evaluated. Bar-shaped (25×2×2 mm) and disk-shaped (Ø10×2 mm) specimens were fabricated. Specimens received 1 of 4 cleaning protocols (minimal cleaning [15-second immersion in 96% isopropyl alcohol without ultrasonic cleaning] or 2, 5, or 10 minutes of ultrasonic cleaning) and 1 of 4 surface conditions (nonglazed control, Palaseal, EQUIA Forte Coat, and COAT-IT), yielding 16 groups per material (n=15/group). Flexural strength (3-point bending; International Organization for Standardization (ISO) 10477:2020), surface roughness (atomic force microscopy), and color stability (ΔE00) were assessed. Data were analyzed by 3-way analysis of variance (ANOVA) with Bonferroni and Dunnett post hoc tests (α=.05).

RESULTS

Material type, cleaning duration, and glazing agent significantly affected all outcomes (P<.001). Two-way interactions were significant for flexural strength (material×cleaning duration and material×glazing agent, P<.001; cleaning duration×glazing agent, P=.027), but the 3-way interaction was not (P=.560). Longer cleaning generally increased flexural strength and increased Ra in nonglazed specimens, whereas glazing reduced Ra and improved color stability (P<.001 for both). Glazing also increased flexural strength (P<.001), with Palaseal best overall.

CONCLUSIONS

The performance of 3D printed restorations depends strongly on postprocessing protocols. Surface glazing enhanced mechanical and esthetic properties, whereas optimal cleaning duration remained material-specific.