ORAL HEALTH EVIDENCE-BASED PRACTICE PROGRAM
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Title Direct Digitized Impressions Produce Zirconia Crowns with a More Accurate Marginal and Internal Fit than Indirect Digitized Impressions
Clinical Question In CAD/CAM milled zirconia crowns, is the marginal and internal fit more accurate when fabricated using a direct or indirect digitized impression?
Clinical Bottom Line Although both direct and indirect digitized impressions produce clinically acceptable zirconia crowns, direct digitized impressions produce more accurate marginal and internal fit. This is supported by a double-blinded, randomized clinical trial with a pool of 25 patients which showed statistically significant differences in accuracy. Another clinical trial study with a pool of 20 patients showed similar supportive results.
Best Evidence (you may view more info by clicking on the PubMed ID link)
PubMed ID Author / Year Patient Group Study type
(level of evidence)
#1) 26070435Ahrberg/201525 patients with need for a single crown restoration (17) or 3-unit FPD (8)Double-blinded, randomized clinical trial
Key resultsThere was a statistically significant difference (p<0.05) in the accuracy of marginal and internal fit in all-ceramic crowns produced from direct digitized impressions (mean marginal gap = 61.08 microns) as opposed to indirect digitized impressions (mean marginal gap = 70.40 microns). Both direct and indirect digitized impressions produced clinically acceptable crowns.
#2) 20381576Syrek/201020 patients with a tooth needing treatment with a crownDouble-blinded clinical trial
Key resultsThere was a statistically significant difference (p<0.05) in the accuracy of marginal and internal fit in all-ceramic crowns produced from direct digitized impressions (median marginal gap = 49 microns) as opposed to indirect digitized impressions (median marginal gap = 71 microns). Both direct and indirect digitized impressions produced clinically acceptable crowns.
Evidence Search "CAD/CAM fabricated" [All Fields] AND "digital impressions" [All Fields]
Comments on
The Evidence
Both studies used a double-blinded, clinical trial format. The Ahrberg study added randomization to its study, which could be a point of weakness in the Syrec study as it did not. Other points of weakness shared between the two studies was their small patient population. A large patient population would have provided more reliable and accurate results. Both studies also used only one brand of intraoral scanner, Lava C.O.S.. A study taking into account the differences in accuracy of various intraoral scanners is indicated. It must also be noted that variability is introduced by the milling unit and this is not fully addressed by either study.
Applicability Clinically, the use of either direct and indirect digitized impressions is indicated as they both produce clinically acceptable crowns. The real clinical benefit of direct over indirect digitized impressions is the time it saves. Unless circumstances prevent its use, clinicians should consider using direct digitized impressions as they are more accurate and save time.
Specialty/Discipline (Public Health) (General Dentistry) (Prosthodontics) (Restorative Dentistry)
Keywords CAD/CAM; Scanning; Digital; Impression; Crown; Zirconia; All-Ceramic
ID# 3317
Date of submission: 04/25/2018spacer
E-mail pjeppesen23@midwestern.edu
Author Palmer Jeppesen
Co-author(s)
Co-author(s) e-mail
Faculty mentor/Co-author Dr. Aseel Murad
Faculty mentor/Co-author e-mail amurad@midwestern.edu
Basic Science Rationale
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