Fit Accuracy of Pressed and Milled Lithium Disilicate Inlays Fabricated From Conventional Impressions or a Laboratory-Based Digital Workflow

European Journal of Prosthodontics and Restorative Dentistry (2019) 27, 18–25

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Fit Accuracy of Pressed and Milled Lithium Disilicate Inlays Fabricated From Conventional Impressions or a Laboratory-Based Digital Workflow

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Inlay Lithium Disilicate CAD-CAM

Dr. Foudda Homsy *
(DCD, DES, DScO)

Matteo Bottin §

Ba

(BSc)

Prof. Mutlu Özcan ^
(Dr Med Dent, PhD)

Prof. Zeina Majzoub *

Dr. Foudda Homsy *
Email: loubab3@hotmail.com

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Address for Correspondence

is

(DCD, DMD, MScDd)

* Lebanese University, Faculty of Dental Medicine
Biesse Dental Srl, Montà, PD, Italy

§

Purpose: The impact of material on the adaptation of lithium disilicate inlays is poorly
documented. This in vitro study aims at comparing the fit accuracy of pressed and
milled inlays obtained from conventional impression and laboratory-based computeraided design and computer-aided manufacturing. Material and Methods: A typodont
molar was prepared for a mesio-occlusal ceramic inlay. The stone die generated from
one conventional impression was scanned once using a laboratory scanner and the
same design was used to produce 15 pressed lithium disilicate inlays from milled wax
patterns (group CIDW), and 15 inlays from lithium disilicate blanks (group CICAD) with
a 5-axis milling machine. Marginal and internal discrepancies were measured using the
replica technique. Mixed-model ANOVA was applied to assess differences according to
material and gap location at P<0.05. Results: Material and discrepancy location had a
significant effect on fit measurements. Group CIDW showed significantly smaller marginal (37.4 µm) and internal (69.2 µm) discrepancies than group CICAD (59.6 µm and
93.7 µm respectively). Marginal discrepancies were significantly smaller than internal
discrepancies within both groups. Conclusions: Pressed inlays generated from conventional impression and milled wax patterns yielded better fit accuracy than milled inlays
obtained from conventional impression and subtractive manufacturing.

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^ University of Zurich, Dental Materials Unit

Received: 13.06.18
Accepted: 11.01.19

Metal-free restorations are increasingly being incorporated into prosthodontic rehabilitations as a result of greater esthetic demands. Among ceramic materials, lithium disilicate glass ceramics are widely used in the fabrication of tooth- and implant-supported prostheses because of their excellent esthetic and mechanical properties.1 Lithium disilicate restorations can be made by using either lost-wax hot pressing techniques or computer-aided-designed and computer-aided-manufacturing (CAD/CAM) digital milling of monolithic blocks.2 Pressed restorations are usually produced by burning out wax patterns that are conventionally shaped by laboratory technicians from conventional impressions. The wax patterns can also be produced by milling wax blocks

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