Abstract
A single-visit zirconia restoration can be easily achieved if direct milling of a fully sintered zirconia block can be performed without much effort. However, no studies have yet been reported regarding the evaluation of the trueness of crown fabricated from chairside-milling of a fully sintered zirconia block in the chairside computer-aided design and computer-aided manufacturing (CAD–CAM) system for single-visit dentistry. This in vitro study aimed to evaluate the trueness of crowns fabricated by milling a fully sintered zirconia block in the chairside CAD–CAM system and investigate the clinical implications for single-visit chairside restoration. Crowns were fabricated either by chairside-milling a fully sintered block of niobium oxide containing yttria-stabilized tetragonal zirconia polycrystals ((Y, Nb)-TZP) without the sintering process (n = 12) in a chairside single-visit dentistry system (Chairside group) or by laboratory-milling a partially sintered 3 mol% block of yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) followed by the sintering process (n = 12) in a conventional laboratory system (Labside group). Crown fabrication time, milling tool diameter and the trueness of each crown were evaluated. All trueness values of both groups were within the clinically acceptable range, although a significant difference between the Chairside (43.0 ± 3.67 μm) and Labside groups (37.4 ± 2.41 μm) was observed (P < 0.05). Mean fabrication time was 0.52 h and 1.42 h for Chairside and Labside groups, respectively. A decrease in the tool diameter was observed for the Chairside group.
Highlights
Along with the development of computer-aided design and computer-aided manufacturing (CAD–CAM) technology, the manufacturing process for dental prosthesis can be divided into either the chairside or the laboratory system
RMSThe values means and standard deviations of root mean square (RMS) values of the inner surfaces of monolithic zirconia crowns of both the Chairside and Labside groups were less than 50 μm in this study, even with tool wear
Even though the Chairside group showed a significantly greater RMS value than the Labside group, all RMS values of both the Chairside and Labside groups were less than 50 μm and were in the clinically acceptable range [18]
Summary
Along with the development of computer-aided design and computer-aided manufacturing (CAD–CAM) technology, the manufacturing process for dental prosthesis can be divided into either the chairside or the laboratory system. The chairside system allows clinicians to design and manufacture the dental prosthesis in their own dental clinics, which enables single-visit restorative treatment [1]. A partially sintered monolithic zirconia cannot be used for a single-visit treatment because of the time-consuming fabrication, as post-milling sintering can take up to 12 h [2,3,4]. A speed (60 to 120 minutes) or high-speed (10 minutes) sintering process for the partially sintered zirconia has been developed, which greatly reduces the total fabrication time [2,3]. The mechanical or Materials 2019, 12, 3253; doi:10.3390/ma12193253 www.mdpi.com/journal/materials
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