Resistance Form of Lithium Disilicate Full Coverage Restorations Milled with 3-Axis and 5-Axis Milling Units
Abstract
Introduction: Caputo and Standlee stated resistance form is the most important factor of restoration success. Currently, the most popular means of fabricating a CAD/CAM full coverage restoration is by subtractive manufacturing utilizing either a 3 or 5-axis milling unit. There is a lack of literature to support whether one or the other produces restorations with superior resistance form. Objective: To compare the resistance form of lithium disilicate restorations milled with a 3-axis (Sirona inLabMCXL) or 5-axis milling unit [Amman Girbach (AG) Ceramill Motion 2]. It was hypothesized the 5-axis unit would provide superior resistance form. Materials and Method: A chrome cobalt master die was scanned by a 3-axis (Sirona Omnicam) and a 5-axis system (AG Ceramillmap400). A lithium disilicate restoration was digitally designed using each systems digital software (Sirona CEREC 4.3 and Exocad) and milled ten times (N=10). The 20 restorations were polished, crystalized, and individually cemented on the master die with calcium hydroxide (Dycal) using a cementation jig under 10lbs of pressure. They were loaded with an off axis load at crosshead speed of 0.02mm/sec until dislodgement (MTS Insight Universal Testing Machine) and the peak loads were recorded. Results: The results revealed a median peak load of 114.1N for the 3-axis system and 120.7N for the 5-axis system. The p-value was 0.23. Statistical significance could not be determined due to the wide range of failure loads for each milling unit. Conclusion: This study found no significant difference in resistance form of full coverage lithium disilicate restorations milled with a 3 or 5 axis milling machine.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 08, 2018
- Accession Number
- AD1128261
Entities
People
- Benjamin D. Fitzharris
Organizations
- Uniformed Services University of the Health Sciences