Marginal/Internal Crown Fit Evaluation of CAD/CAM versus Press-Laboratory All-Ceramic Crown

Objectives: To evaluate in vitro marginal and internal fit of all-ceramic between conventional press-laboratory made all ceramic crowns and CAD/CAM systems

Methods: Tooth #14 was prepared per standard specification to receive an all-ceramic crown restoration on typodont.  The preparation had well-defined, 1 mm circumferential shoulder gingival margin, 2 mm occlusal reduction, rounded internal angles, and less than 20° total occlusal convergence. Forty-five tooth #14 were duplicated and poured in dental stone type V. Each tooth was randomly divided into 3 groups (n=15) and placed in full-dentate typodont. All-ceramic CAD/CAM crowns (Group 1) were fabricated with E4D system according manufacturer's instructions. For press-laboratory made crowns, impressions were taken on the posterior left region area with two-step impression techniques using a custom triple tray with light and putty consistency VPS.  Impressions were sent to two dental laboratories (Group 2 and 3) for fabricating the monolithic press lithium disilicate crown. All crowns were cemented using Multilink®Automix (Ivoclar Vivadent) under constant pressure of 100N. Samples were embedded in acrylic and sectioned buccolingually. Sections were evaluated under digital microscope measured on 3 locations per buccal and lingual side of section: marginal-edge, mid-axial wall, and cusp-tip. Statistically analysis was accomplished with Kruskal-Wallis one-way ANOVA. Significance was predetermined at p<.05.

Results: No Significant difference was found at the buccal and lingual margins in all groups. However, there was significance difference for cement thickness in midaxial, cusp and occlusal within the group.

	Buccal			Occlusal	Lingual
(µm±SD)	Margin	Mid-Axial	Cusp		Cusp	Mid-Axial	Margin
Group1	(44.88±32.06)	(120.45±45.95)	(95.47±59.99)	(161.05±29.11)	(95±34.53)	(154.6±57.94)	(39.07±32.44)
Group2	(33.46±38.77)	(183.95±43.16)	(178.15±56.33)	(215.71±35.8)	(167.99±45.12)	178.89±77.2)	(36.09±38.47)
Group3	(45.22±41.87)	(150.51±57.96)	(249.42±54.67)	(221.89±111.03)	(238.97±81.14)	(117.51±50.13)	(62.02±49.96)

Conclusions: Based on the statistical results there was no statistical difference in marginal fit of all-ceramic crowns made by CAD/CAM system or laboratory press ceramic.