The marginal fit of lithium disilicate crowns: Press vs. CAD/CAM

Abstract

The marginal fit of lithium disilicate crowns: Press vs. CAD/CAM Abstract: This study aimed to compare the vertical marginal gap of teeth restored with lithium disilicate crowns fabricated using CAD/CAM or by pressed ceramic approach. Twenty mandibular third molar teeth were collected after surgical extractions and prepared to receive full veneer crowns. Teeth were optically scanned and lithium disilicate blocks were used to fabricate crowns using CAD/CAM technique. Polyvinyl siloxane impressions of the prepared teeth were made and monolithic pressed lithium disilicate crowns were fabricated. The marginal gap was measured using optical microscope at 200× magnification (Keyence VHX-5000, Japan). Statistical analysis was performed using Wilcoxon test. The lithium disilicate pressed crowns had significantly smaller (p = 0.006) marginal gaps (38 ± 12 µm) than the lithium disilicate CAD/CAM crowns (45 ± 12 µm). This research indicates that lithium disilicate crowns fabricated with the press technique have measurably smaller marginal gaps compared with those fabricated with CAD/CAM technique within in vitro environments. The marginal gaps achieved by the crowns across all groups were within a clinically acceptable range.

Do lithium disilicate ceramic manufacturing techniques affect the degree of conversion of light-cured resin cement?

“…During indirect restoration luting, the ceramic attenuates the light intensity and reduces the amount of photons that reach the resin-based cement [4,12]. Thus, dualcured resin cements are indicated to compensate the light attenuation caused by the interposition of an indirect restorative material, as well as to assure proper resin cement polymerization processes [23].…”

“…The material is available in pre-sintered blocks for chairside milling using CAD/CAM systems [3]. Lithium disilicate restorations can also be manufactured based on the lostwax, pressed ceramic technique [4]. The pressed system enables a smaller marginal gap between restoration margin and the finishing line in tooth preparation, besides being significantly stronger than other systems [4].…”

“…Lithium disilicate restorations can also be manufactured based on the lostwax, pressed ceramic technique [4]. The pressed system enables a smaller marginal gap between restoration margin and the finishing line in tooth preparation, besides being significantly stronger than other systems [4]. However, there is growing demand for the milled ceramic system, which enables intraoral digital impressions and in-office milling, thus reducing its production time [4].…”

“…The pressed system enables a smaller marginal gap between restoration margin and the finishing line in tooth preparation, besides being significantly stronger than other systems [4]. However, there is growing demand for the milled ceramic system, which enables intraoral digital impressions and in-office milling, thus reducing its production time [4]. Resin cement polymerization can be affected by some factors linked to the restoration, among them: ceramic thickness, color and type, crystalline structure, grain size, defects, intrinsic porosity and stratification technique [5][6][7].…”

Comparison of marginal adaptation of fixed ceramic restorations prepared with the ceramic heat-pressed technique and CAD/CAM technology – review of literature

“…Crowns made using the traditional method showed statistically significantly better marginal adaptation (38 μm) than those made in the CAD/CAM system (48 μm). 19 The above work presents in vitro studies comparing the marginal integrity of ceramic prosthetic restorations made utilizing a traditional impression and CAD/CAM technology throughout the entire cycle. Despite the widespread use of digital technologies, and the continuous development of laboratory materials and procedures, 20 the research analysed in this study does not show clearly whether they allow a tighter seal of prosthetic restorations.…”