Related Experiment Video
Updated: Jan 16, 2026
Quasistatic Mechanical Testing for Computer-Aided Design and Manufacturing Occlusal Veneers Cemented to Milled Dentin Analog Material
Published on: December 20, 2024
Colour Stability and Optical Properties of Provisional Crowns Fabricated With Milling, 3D Printing, and Direct
Tommaso Rinaldi1, Carlos Serrano Granger2, Andrea Santamaría Laorden2
1School for Doctoral Studies and Research, European University of Madrid, Villaviciosa de Odón, Madrid, Spain.
Statement Of Problem:
Colour stability and optical performance of acrylic provisional restorations can be compromised by exposure to chromogenic agents. Additionally, the behaviour of different fabrication techniques under these conditions needs further assessment.
Purpose:
To evaluate the colour stability and optical properties of polymethyl methacrylate (PMMA) provisional crowns fabricated by three methods: CAD/CAM milling, 3D printing, and direct technique, after exposure to chromogenic agents.
Material And Methods:
A total of 180 PMMA provisional crowns were fabricated using three techniques: milled (n = 60), 3D printed (n = 60), and direct (n = 60). After undergoing thermocycling protocol, each group was divided into five subgroups (n = 12) and exposed to the following chromogenic agents: coffee, tea, cola, red wine, and tobacco. Colour changes (ΔE) were measured using a spectrophotometer (VITA Easyshade V; VITA Zahnfabrik) with the CIELab system over 4 weeks. Optical properties (translucency, opalescence, contrast ratio) were analysed over black and white substrates. Surface deterioration was examined by scanning electron microscopy, and the pH of each solution was recorded. One-way ANOVA and Tukey's posthoc test were used for statistical analysis (P < .05).
Results:
Significant differences in colour stability were observed among the groups (P < .05). The direct technique showed the highest ΔE values, followed by the printed group. Milled crowns had the greatest colour stability. Tobacco caused the most discolouration. Milled crowns also showed the best optical performance.
Conclusions:
Fabrication techniques significantly affected colour stability and optical performances. Milled PMMA crowns showed superior results compared to printed and direct methods.
Clinical Significance:
The fabrication technique influences the esthetic durability of provisional restorations. Milled PMMA crowns provided superior colour stability and optical outcomes, making them ideal for long-term aesthetics. Direct technique crowns were more prone to discolouration and surface degradation. Tobacco had the strongest chromogenic effect. Selecting the right technique and considering patient habits are essential for lasting aesthetic results.
