Conventional versus CAD/CAM unilateral space maintainers: a fracture resistance test

Introduction
The selection and fabrication of a space maintainer is crucial to ensure its durability and functionality. Currently, resin unilateral spacers have gained popularity due to their esthetic appeal, ease of handling, and chairside adjustability. However, concerns were raised regarding their fracture resistance, especially when compared with metal spaces, which offer superior mechanical properties but may lack esthetic advantages of resins.

Objectives
This study aimed to compare the fracture resistance of both types of spacers.

Material and methods
To investigate fracture resistance, an in vitro experimental setup was designed using standardized protocols. A total of 40 spacers were fabricated, from which 20 were resin-printed using CAD/CAM and 20 were metallic spacers fabricated manually. Fracture resistance was evaluated using a universal testing machine, applying an occlusal load until fracture occurred.

Results
Metallic spacers exhibited significantly higher fracture resistance compared with resin unilateral spacers. This finding indicated that metallic spacers withstand more occlusal forces, and may provide improved durability in clinical settings.

Conclusions
Further research is warranted to investigate clinical performance of both types of spacers as well as their resistance to other failure modes, such as wear and debonding. This study highlights superior fracture resistance of metallic spacers than resin unilateral spacers.