# Comparative Evaluation of Fracture Resistance in Implant-Supported Provisional Crowns Fabricated by Computer-Aided Design and Manufacturing, Three-Dimensional Printing, and Conventional Self-Curing

## TL;DR

This study compares how different fabrication methods affect the durability of temporary dental crowns, finding that 3D printing produces the strongest ones.

## Contribution

The study provides a direct comparison of fracture resistance in implant-supported provisional crowns made using CAD-CAM, 3D printing, and conventional methods.

## Key findings

- 3D-printed crowns showed the highest fracture resistance compared to CAD-CAM and conventional methods.
- Conventional self-curing crowns had the lowest fracture resistance and may only be suitable for low-load situations.
- CAD-CAM milled crowns had intermediate strength, acceptable for clinical use.

## Abstract

Aim and objectives

This study aimed to assess the influence of three fabrication techniques, computer-aided design (CAD) and computer-aided manufacturing (CAM) milling, three-dimensional (3D) printing, and conventional self-curing, on the fracture resistance of implant-supported polymethyl methacrylate (PMMA) resin-based provisional crowns.

Methods

An in vitro comparative study was conducted using 45 implant analogs with straight titanium abutments, equally distributed into three groups. Each analog was embedded vertically in custom acrylic resin blocks (20 × 20 × 20 mm). Abutments were torqued to 25 Ncm, and screw access channels were sealed with Teflon pellets and composite resin. Provisional crowns were fabricated using CAD-CAM milling, 3D printing, and conventional self-curing methods. All crowns were cemented and subjected to axial loading in a universal testing machine until fracture. Fracture resistance values were recorded and statistically analyzed.

Results

Crowns made with 3D printing showed the greatest average resistance to fracture, followed by CAD-CAM milling, and the crowns fabricated using the conventional self-curing method had the lowest fracture resistance. Statistical tests confirmed that these differences between the three groups were significant (p <0.05). The stronger performance of the 3D-printed crowns points to better overall durability, suggesting they could be especially useful for implant-supported provisional restorations in clinical practice.

Conclusion

Taking into account the limitations of this laboratory study, 3D-printed PMMA crowns showed the highest fracture resistance compared to the other fabrication methods tested. Crowns made by CAD-CAM milling also had strength levels that are acceptable for clinical use, making them a good alternative option. On the other hand, crowns produced with conventional self-curing methods were the least resistant to fracture, which means they might only be suitable for situations where the load is minimal. Ultimately, the choice of fabrication technique should be based on specific clinical requirements, material properties, and cost considerations.