THE DIMENSIONAL CHANGE OF CAST IMPLANT BARS AFTER LABORATORY PROCEDURE

• Published in: Taehan Chikwa Poch'ol Hakhoe chi Vol. 45; no. 3; pp. 354 - 361
• Main Authors: Kwon, Ji-Yung, Kim, Chang-Whe, Lim, Young-Jun, Kim, Myung-Joo
• Format: Journal Article
• Language: Korean
• Published: 대한치과보철학회 01.06.2007
• Subjects: 치의학; Cast implant bar; Gap distance; Passive fit; Coordinate measuring machine
• ISSN: 0301-2875; 2005-3789

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 $106.3{\mu}m$ for buccal side, $122.1{\mu}m$ for distal side and $117.1{\mu}m$ for the lingual side. The mean bar length was $17964.7{\mu}m$ at precasting measurement, $17891.6{\mu}m$ at postcasting measurement. The mean change of bar length was $-73.1{\mu}m$. 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.