Background: The purpose of this study was to measure the marginal gaps of CAD/CAM all-ceramic crowns constructed using different cement spaces on crown preparations created by undergraduate students. Methods: Twenty-four Columbia model lower left first molars with assessed tapers and reduction volumes (RV) were recruited to receive complete coverage E.max crowns. Three E.max crowns were digitally designed and milled for each crown preparation using three different cement spaces: 50 lm (CS-50), 100 lm (CS-100), 200 lm (CS-200). Each crown was seated onto its original crown preparation and three vertical marginal gap measurements were taken at four locations (mid-buccal, mid-lingual, mid-mesial, mid-distal) using a stereomicroscope. The mean marginal gap (MMG) was calculated for each crown and each individual tooth surface. Results: The MMG was statistically significantly different for each of the three cement spaces (126 lm for CS-50, 89 lm for CS-100, and 75 lm for CS-200) (P < 0.0001). A taper of between 20 and 30°produced the smallest MMG. Insufficient RV caused significantly larger MMGs. The buccal margin had significantly smaller MMGs than all other measured surfaces. Conclusions: The most accurate margins of digitally designed all-ceramic crowns constructed on simulation teeth prepared by undergraduate students were observed when using a 200 lm cement space. Abbreviations and acronyms: BL = bucco-lingual; CAD/CAM = computer-aided design/computer-aided manufacturing; CS = cement space; MD = mesio-distal; MMGITS = mean marginal gaps for individual tooth surfaces; MMG = mean marginal gap; MPa = megapascals; RV = reduction volume.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.