J Korean Acad Pediatr Dent.  2020 May;47(2):205-212. 10.5933/JKAPD.2020.47.2.205.

Fracture Strength and Translucency of CAD/CAM Zirconia Crown for Primary Anterior Tooth

• Ong SH
• Kim J
• Kim J
• Shin J
• Yoo S

• KMID: 2511432
• DOI: http://doi.org/10.5933/JKAPD.2020.47.2.205

Abstract

The purpose of this study is to evaluate the validity of primary anterior zirconia crown made with Computer Aided Design/Computer Aided Manufacturing (CAD/CAM) technology by analyzing fracture strength and translucency parameter.
Zirconia crown was designed with CAD software, using 3D scanned data of #61 tooth model. Crown fabrication was performed with CAM machine using zirconia block. Zirconia crowns were divided into 3 groups according to thickness(0.3, 0.5, and 0.7 mm), and fracture strength was compared with 1.0 mm thickness of resin strip crown. The compressive force was applied with universal testing machine at 30° along the incisal edge at increments of 1 mm/min. For translucency evaluation, 0.3, 0.5, and 0.7 mm thickness of zirconia specimens were fabricated and translucency was measured with spectrophotometer.
Among zirconia groups, there was a significant increase in fracture strength as thickness increased (p < 0.05). The fracture strength of zirconia crown was significantly higher than resin strip crown in all groups (p < 0.05). Translucency parameter was highest in 0.3 mm group, and significantly decreased as thickness increased to 0.5 and 0.7 mm (p < 0.05).
Thin primary anterior zirconia crown can be designed and fabricated according to individual needs by using CAD/CAM. Restoration with thin crown would reduce the amount of tooth reduction, risk of pulp exposure, and make more esthetic restoration possible.