الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
This in-vitro study was designed to evaluate the trueness of custom post cervical diameter scans using different scanning techniques with two cervical diameters.
Fourteen freshly extracted lower second single canal premolars were endodontically treated using Wave-One single file technique taper 6% with apical size iso 25. Obturation was done using Continuous Wave Condensation technique with master cone ISO 25 taper 6% followed by Obtura root canal filling system. Teeth were mounted in acrylic blocks parallel to long access using a dental surveyor below level of CEJ by 2mm.Teeth were decoronated to a level above CEJ by 2mm. Drilling of post spaces using dental surveyor to two different cervical diameters 2.5 mm and 3 mm.
All teeth were scanned using the (inEos X5 Sirona- Germany) to produce a reference scan, then scanning of post cervical diameter directly using intraoral scanner for all teeth. Scanning of the impressioned post cervical diameters for all teeth which was taken using Vinylsiloxanether (VSXE) impression material using desktop scanner, Finally scanning of the poured impressions of the post cervical diameter to create models for all teeth using desktop scanner.
For all the sampled teeth each scanning technique used was superimposed to the reference scan with the help of a reverse engineering 3D analysis software to calculate the amount of deviation between them.
A color-difference map (qualitative data) and a report (quantitative data) of the projections were obtained for every single superimposition process.
Data was recorded, tabulated and analyzed. Statistical work was done using t test.
Our Results showed:
1. There was a significant difference between different groups (p<0.001). The lowest value was found in scanned IOS (D.S) (46.24±6.07), followed by scanned impression (I.S) (80.93±14.01), while the highest value was found in scanned model (M.S)(99.69±23.19) Post hoc pairwise comparisons showed different groups to have significantly different values from each other (p<0.001).
2. Samples with 3(group B) mm post cervical diameter (66.33±20.18) had a significantly lower RMS value than samples with 2.5(group A) mm post cervical diameter (84.91±30.88) (p=0.001).