Revolution in Provisional Restoration:Meet the New Generation of Materials

Abstract

Objectives: The provisional or interim phase represents an important aspect of restorative treatment. It
serves as a crucial tool for assessing whether the tooth preparation is sufficient for a definitive prosthesis.
A provisional restoration can be either prefabricated or custom-made, and a wide variety of materials can be
used. Fabrication technologies include subtractive (milling), additive (three-dimensional [3D] printing), and
conventional (using self-cured materials) techniques. This study aimed to evaluate the flexural strength of three
different types of provisional restorative materials after simulation of oral conditions using a thermocycling
protocol. Materials and Methods: Three provisional restorative materials were evaluated for flexural strength
after thermocycling; Pre-polymerized computer-aided design (CAD) and manufacturing resin block (VITA,
computer-aided design temporary [CAD-Temp]), 3D-printed resin (NextDent, Crown and Bridge micro filled
hybrid [C&B MFH]), and Auto-polymerized polymethyl methacrylate (GC, Unifast III). 30 bar-shaped (25 ×
2 × 2 mm ±0.1 mm) specimens were prepared from each resin material. Specimens of each material were
divided into three groups (n = 10/group): Baseline (BL), 10,000, and 20,000 thermocycles. Flexural strength
was determined using a three-point bending test performed with a universal testing machine. Statistical analysis
was performed by two-way analysis of variance with Tukey-Kramer Honestly Significant Difference multiple
comparison tests at α = 0.05 significance level. Results: The flexural strength of all tested materials significantly
decreased after thermocycling (P < 0.05). At BL, the milled CAD-Temp exhibited the highest flexural strength
(102.51 MPa), followed by the 3D-printed C&B MFH (73.96 MPa) and the self-cured Unifast III (63.90 MPa).
After 10,000 thermocycles, all materials showed a significant reduction in flexural strength, which further
declined after 20,000 thermocycles. Despite aging, CAD-Temp maintained the highest flexural strength at both
10,000 and 20,000 thermocycles (80.48 and 70.77 MPa, respectively), while Unifast III consistently exhibited
the lowest. Significant differences were observed among all materials within each thermocycling interval
(P < 0.05). Conclusion: Thermocycling significantly reduced the flexural strength of all tested provisional
materials. Milled CAD-Temp showed the highest flexural strength across all intervals, while 3D-printed C&B
MFH demonstrated moderate strength. Unifast III consistently exhibited significantly lower flexural strength
across the study.