الفهرس 
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Abstract
Purpose: The aim of the present study was to assess the marginal fit and fracture resistance of
interim restorations fabricated by 3D printing technique compared to conventional technique.
Method: Typodont model of maxillary 1st molar was prepared for full coverage crowns. The
prepared model was digitally scanned by 3D scanner. Duplication of master die into 20 epoxy
resin dies. Interim crowns were constructed by two techniques: conventional chair side
technology using a bis-acrylic based self-cure temporary material (structure-2- Voco, Germany)
and 3D printing technology using (Next-dent C&B resin) material. The specimens were divided
into 2 equal groups (n=10). Marginal adaptation was evaluated using stereomicroscope and
image analyzing software to measure the amount of marginal gap at 20 reference points. The
interim crowns were cemented on their corresponding epoxy resin dies using Zinc Oxide NonEugenol cement (Cavex). All samples were subjected to thermal cycles (1250 cycles, 5-55°c).
The specimens were loaded to failure in Newton (N) using universal testing machine. Digital
microscope was used to investigate the fracture pattern. Data was statistically analyzed used
Student’s t tests (α = 0.05) and failure mode (%) by the chi test (p≤0.05).
Results: The mean marginal gap value of 3D printing provisional crowns (38.76 ±27.21μm)
was significantly lower than that of conventional chair-side crowns (120.43 ± 32.63μm).
Also, 3D printed group recorded statistically significant higher fracture resistance mean value
(1027± 156.25 N) than conventional chair-side group (401.2 ± 132.92 N).
There was no significant difference between failure modes in both groups.
Conclusions:
Provisional crowns fabricated by 3D printing showed superior marginal accuracy and higher
fracture resistance than conventionally constructed crowns. Mode of fracture was consistent
with fracture resistance in both tested groups; since 3D printed group had minimum cracks in
their crowns, while conventionally constructed ones showed severe type of fracture, following
their fracture strength test.
Keywords: Interim crown, 3D printing, Conventional chair-side, Marginal fit, Fracture
resistance, Failure mode.