An in vitro evaluation of marginal fit zirconia crowns fabricated by a CAD-CAM dental laboratory and a milling center

Abstract

Background Marginal fit is critical for the success and longevity of a dental restoration. Zirconia crowns can be fabricated either chair-side, in a dental laboratory or in a milling center; each can give different marginal fits results. However, discussion of the marginal fit of zirconia crowns when different fabrication methods are compared is lacking in the literature. Purpose To compare the marginal discrepancy (MD) and absolute marginal discrepancy (AMD) of computer-aided design, and computer-aided manufacturing (CAD-CAM) used in a dental laboratory and a milling center for producing monolithic zirconia crowns. Methods The marginal fit of 30 zirconia crowns cemented to typodont teeth was evaluated by means of a sectioning technique. Fifteen crowns were fabricated with a CEREC inLAB MC X5 from IPS e.max ZirCAD blocks. Fifteen crowns were fabricated using a LAVA milling center from LAVA Plus Zirconia Blocks. The 30 crowns were sectioned with a precision saw, and MD and AMD were subsequently measured using a light microscope. Data were analyzed using the one-way ANOVA technique to investigate significant differences in the marginal fit between the two fabrication systems (α = .05). Results The AMD dimension of the CEREC inLAB system was significantly smaller ( P < .05). Mean AMD values for zirconia crowns fabricated by the CEREC inLAB were 85 μm, and for the LAVA milling center 133 μm. There was no significant difference between the two systems regarding the MD dimensions. The MD values for zirconia crowns fabricated by the CEREC inLAB were 53 μm and for the LAVA milling center 61 μm. Conclusions The CEREC inLAB system demonstrated significantly better marginal fit in relation to the AMD. However, no difference between the systems was found in the MD. Monolithic zirconia crowns fabricated by the CAD-CAM CEREC inLAB system and the LAVA system milling center showed MD values of less than 120 μm, which is within the clinically acceptable range.

Marginal and internal fit of full ceramic crowns milled using CADCAM systems on cadaver full arch scans

“…These results are comparable to this study's CEREC data, considering the difference between the marginal gap and AMD. However, other studies measured AMD with CEREC systems and obtained lower values, between 53 and 94 μm [19,22,53]. The lower values of these studies may come from ideal in vitro conditions obtained by scanning a single typodont tooth instead of a full dentate arch dentate.…”

“…This means that AMD is higher than or in an ideal condition perhaps equal to the marginal gap. In studies measuring both parameters, the AMD was found to be 30-118% greater than the marginal gap [52][53][54]. Literature regarding marginal fit with chairside systems is available for CEREC, but most of them scanned typodont specimens.…”

Zirconia crowns cemented on titanium bars using CAD/CAM: a five-year follow-up prospective clinical study of 9 patients

“…In this case prospective clinical study no chipping nor delamination of ceramic veneering were observed in 5 years. This good result achieved thanks to the marginal fit, which is critical for the success and longevity of a dental restoration [26]. The protocol adopted in this clinical trial leads to a substantial and advantageous reduction in costs and treatment times; it is supported by a high, long-term prognosis that, according to the studies carried out, ranges from 92 to 100% [19][20][21].…”

An Experimental Strategy for Capturing the Margins of Prepared Single Teeth with an Intraoral Scanner: A Prospective Clinical Study on 30 Patients

“…This can result in the fabrication of an incongruous prosthetic restoration [10,11]. An incongruous restoration, which presents non-optimal adaptation (for example, horizontal, vertical, or absolute marginal discrepancies), can produce a series of negative effects, such as greater accumulation or retention of plaque and therefore gingival inflammation (gingivitis) that can subsequently develop into periodontal pocket formation [17,18]; in addition, in the long term, complications such as secondary caries [19] and, in some susceptible biotypes, recessions can occur [20]. For all these reasons, the precision of a restoration does not exclusively represent the search for an optimal transition between the natural element and the prosthesis, but it is key to the longevity (or survival) of the restoration itself [2,11,[17][18][19][20].…”

“…An incongruous restoration, which presents non-optimal adaptation (for example, horizontal, vertical, or absolute marginal discrepancies), can produce a series of negative effects, such as greater accumulation or retention of plaque and therefore gingival inflammation (gingivitis) that can subsequently develop into periodontal pocket formation [17,18]; in addition, in the long term, complications such as secondary caries [19] and, in some susceptible biotypes, recessions can occur [20]. For all these reasons, the precision of a restoration does not exclusively represent the search for an optimal transition between the natural element and the prosthesis, but it is key to the longevity (or survival) of the restoration itself [2,11,[17][18][19][20]. To date, numerous techniques have been proposed for the correct scanning and visualization of the margins of prosthetic preparations on natural teeth, including traditional techniques used also with conventional impressions with polyethers/polyvinylsiloxane, such as placement of one or two gingival retraction cords [21,22], the use of retraction pastes [23], gels [24] or strips [25], and the use of a laser [26].…”