الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
This in-vitro study investigated the effect of divergence angle and intra-pulpal depth on the marginal adaptation and Internal fit of endo-crowns and the accuracy of two intraoral scanners.
Hence the accuracy of intraoral scanners are described according to ISO 12836 as trueness and precision. the deviation of measurements between the reference model and the intraoral scan model is termed the ‘trueness’ of impression technique, and the deviation of measurements between digital models of the same intraoral scanner is ‘precision’ of impression technique.
The aim of the study is to Evaluate Effect of preparation design Divergence Angle. (12o , 6o) and Intra-pulpal Depth. (3mm, 5mm) On Marginal Adaptation and Internal Fit of Premolar Endo-crowns using Two Intraoral Scanners: 3Shape “Trios 4” and Cerec “Prime Scan”.
The preparation was done on a Four extracted endotreated premolars, preparations were done using Carbide Carburundom diamond Endmil.
Two intra oral scanners took part in our study the Trios 4, Prime Scam.
All the preparations were scanned with the intraoral scanners 7 times (n=7) with each scanner and then with the help of an Exo-cad Software used to design endocrowns for each sample to be milled.
All the samples were designed with Exo-cad software milled in a PMMA material using VHF Milling Machine.
For the Marginal Adaptation and Internal fit the Measurements were done by using Dino-lite digital microscope after Replica technique.
Data was recorded, tabulated and analyzed. Statistical work was done using t test.
Our results showed that:
1- Significant difference between Prime Scan (74.26±16.31) which had a significantly higher value than Trios (44.61±8.52) (p<0.001) as a result of Marginal adaptation.
2- Significant difference between 6° (68.65±19.68) which had a significantly higher value than 12° (50.22±15.20) (p<0.001) as a result of Marginal adaptation.
3- Significant difference between 5 mm depth (66.25±19.34) which had a significantly higher value than 3 mm depth (52.62±18.00) (p<0.001) as a result of Marginal adaptation.
4- Significant difference between Prime Scan (225.17±20.70) which had a significantly higher value than Trios (209.82±18.58) (p<0.001) as a result of Internal Fit.
5- Significant difference between 6° (230.57±18.71) which had a significantly higher value than 12° (204.43±13.71) (p<0.001) as a result of Internal Fit.
6- Significant difference between with 5 mm depth (224.55±16.85) which had a significantly higher value than 3 mm (210.44±22.56) (p=0.001) as a result of Internal Fit.
CONCLUSIONS
Within the limitation of our study, the following conclusions may be drawn:
1. Trios 4 is superior in accuracy than the Prime Scan in both 3 mm and 5 mm sample groups According Internal Fit.
2. Trios 4 is superior in accuracy than the Prime Scan in both 6° and 12° sample groups according internal fit.
3. Trios 4 is superior in accuracy than the Prime Scan in both 3 mm and 5 mm sample groups According Marginal Adaptation.
4. Trios 4 is superior in accuracy than the Prime Scan in both 6° and 12° sample groups According Marginal Adaptation.
LIMITATIONS
1. Sample Size One limitation of this study is the small sample size. The study only used four extracted teeth, which may not be representative of the larger population. Future studies should consider using larger sample sizes to improve the generalizability of the findings.
2. In-vitro Setting Another limitation of this study is that it was conducted in an in-vitro setting. As such, the findings may not necessarily reflect the clinical reality of placing endo-crowns in living patients. Future studies should consider conducting in-vivo studies to confirm the findings of this study.