الفهرس 
LIST OF CONTENTOnly 14 pages are availabe for public view
 |  | from | 130 |  |  |
| | | from | 130 | | |
Abstract
Aim: to assess the fracture resistance of interim restorations fabricated by 3D printing
technique compared to milling technique.
Methodology: Typodont model of maxillary 1st molar was preprared for full coverage
crowns. The prepared model was digitally scanned by extraoral scanner. Duplication of
master die into sixteen epoxy resin dies. Sixteen interim crowns were constructed by two
techniques include: CAD/CAM technology using TelioCAD PMMA disc and 3D printing
technology using Nextdent C&B resin material. The specimens were divided into 2 equal
groups (n=8). All interim crowns were cemented on their corresponding resin dies using
cementation loading device. All samples were subjected to thermal cycles(1250cycles,5-
55c) and mechanical cycles (37,000cycles,50N). Using SEM to assess the surface
topography for samples in both groups and EDX microanalysis was used to evaluate the
elemental compositions with relative values expressed in wt% and K ratio.The specimens
were loaded to failure in Newton (N) using universal testing machine. Stereomicroscope
was used to investigate the fracture pattern. Data was statistically analyzed used
Kolmogorov-Smirnov and Shapiro-Wilk tests & Student’s t tests (α = 0.05) and failure
mode (%) by the Fisher exact test & chi2 test (p≤0.05).
Results: The mean ± SD values of fracture resistance were recorded for milled group
(933.46 ±104.49 N) meanwhile the mean ± SD value recorded with printed group were
(1226.48±48.33 N). It was found that printed group recorded statistically significant
higher fracture resistance mean value than milled group. Conclusions: Interim crowns
constructed using 3-D printing technique showed higher fracture resistance compared to
milled interim crowns under thermo- mechanical loading .