Effect of cement space settings on the marginal and internal fit of 3D-printed definitive resin crowns

Abstract

Statement of problem. The cement gap setting affects the marginal and internal fits depending on

the crown material and manufacturing method (subtractive or additive manufacturing). However,

information on the effects of cement space settings in the computer-aided design (CAD)

software program, which is used to aid the manufacturing with 3-dimensional (3D) printing-type

resin material, is lacking, and recommendations for optimal marginal and internal fit are needed.

Purpose. The purpose of this in vitro study was to evaluate how cement gap settings affect the

marginal and internal fit of a 3D-printed definitive resin crown.

Material and methods. After scanning a prepared typodont left maxillary first molar, a crown was

designed with cement spaces of 35, 50, 70, and 100 mm by using a CAD software program. A total of

14 specimens per group were 3D printed from definitive 3D-printing resin. By using the replica

technique, the intaglio surface of the crown was duplicated, and the duplicated specimen was

sectioned in the buccolingual and mesiodistal directions. Statistical analyses were performed

using the KruskaleWallis and the ManneWhitney post hoc tests (a=.05).

Results. Although the median values of the marginal gaps were within the clinically acceptable

limit (<120 mm) for all the groups, the smallest marginal gaps were obtained with the 70-mm

setting. For the axial gaps, there was no observed difference in the 35-, 50-, and 70-mm groups,

and the 100-mm group showed the largest gap. The smallest axio-occlusal and occlusal gaps

were obtained with the 70-mm setting.

Conclusions. Based on the findings of this in vitro study, a 70-mm cement gap setting is

recommended for optimal marginal and internal fit of 3D-printed resin crowns. (J Prosthet Dent

2023;-:---)