J Korean Acad Prosthodont.  2007 Jun;45(3):354-361.

The dimensional change of cast implant bars after laboratory procedure

• Kwon JY
• Kim CW
• Lim YJ
• Kim MJ

Abstract

STATEMENT OF PROBLEMS: The precision of fit between the bearing surfaces of implant abutments and the prosthesis framework has been considered fundamental to implant prosthodontic protocol. PURPOSE: The study aimed to investigate the effect of laboratory procedure on the dimensional accuracy of cast implant bars. MATERIAL AND METHODS: Thirty implant bars were fabricated on a metal master model. The gap distances were measured at the right implant abutment replica-gold cylinder interface after casting procedure. The bar length data of precasting and postcasting state were collected and analyzed.
RESULTS
The mean gap distance found after casting was 106.3 micrometer for buccal side, 122.1 micrometer for distal side and 117.1 micrometer for the lingual side. The mean bar length was 17964.7 micrometer at precasting measurement, 17891.6 micrometer at postcasting measurement. The mean change of bar length was - 73.1 micrometer.
CONCLUSION
Even though the techniques used in this study strictly followed the guidelines established in the literature, the 30 cast implant bars evaluated all yielded gap distances that were beyond acceptable accuracy. There was a statistically significant difference between precasting and postcasting bar length (P<0.01). There was a decreasing tendency in bar length after casting procedure. It was necessary to correct this dimensional change from laboratory procedure by some corrective methods.

Keyword

Cast implant bar; Coordinate measuring machine; Gap distance; Passive fit

MeSH Terms

Prostheses and Implants
Prosthodontics