A study of precise fit of the CAM zirconia all-ceramic framework

Jeon, Mi Hyeon; Jeon, Young Chan; Jeong, Chang Mo; Lim, Jang Seop; Jeong, Hee Chan

Abstract

STATE OF PROBLEM: Zirconia all-ceramic restoration fabricated with CAM system is on an increasing trend in dentistry. However, evaluation of the marginal and internal fits of zirconia bridge seldomly have been reported. PURPOSE: This study was to evaluate the fit of margin and internal surface in posterior 3-unit zirconia bridge framework fabricated with CAM system(DeguDent, Germany). MATERIAL AND METHOD: Preparations of secondary premolar and secondary molar on artificial resin model were performed for fabrication of 3-unit posterior bridge framework. Fits of 5 zirconia bridge framework were compared with 5 precious ceramo-metal alloy framework(V-GnathosPlus, Metalor, Switzerland), and prepared margins were designed to chamfer and shoulder finishing line. Each framework was cemented to epoxy resin model with reinforced glass ionomer(FujiCEM, GC Co., Japan), embedded in acrylic resin and sectioned in two planes, mesiodistal and buccolingual. Samples were divided into six pieces by sectioning and had two pieces of each surface(i.e. mesial, distal, buccal and lingual surface) per abutment, so there were eight measuring points in each abutment. External gap was measured at the margin and internal gaps were measured at the margin, axial and occlusal surface. Gaps were observed under the measuring microscope(Compact measuring microscope STM5; Olympus, Japan) at a magnification of * 100. T-test were used to determine the statistic significance of the different gaps between zirconia and metal framework. RESULTS AND CONCLUSION: 1. External and internal marginal gaps of zirconia and metal framework were in clinically acceptable range. External marginal gaps were not different significantly between zirconia(81.9 micrometer) and metal(81.3 micrometer) framework and internal marginal gaps of zirconia(44.6 micrometer) were smaller than those of metal framework(58.6 micrometer). 2. Internal axial gaps of zirconia framework(96.7 micrometer) were larger than those of metal framework(78.1 micrometer) significantly and adversely, internal occlusal gaps of zirconia framework(89.4 micrometer) were smaller than those of metal framework(104.9 micrometer) significantly. 3. There were no significant differences in external and internal marginal gaps between chamfer and shoulder finish line when zirconia frameworks were fabricated.