Elsevier

Dental Abstracts

Volume 62, Issue 3, May–June 2017, Pages 134-135
Dental Abstracts

Hands On
Marginal and internal fit

https://doi.org/10.1016/j.denabs.2016.12.019Get rights and content

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Background

Marginal and internal fit are measures of the clinical quality and success of fixed dental prostheses (FDPs). Marginal fit is important to the success of the restoration even though marginal discrepancy by itself does not correlate with marginal microleakage. Internal fit has an effect on the seating of the crown and, therefore, the marginal fit. Conventional impressions are obtained using polyether (PE) and polyvinyl siloxane (PVS), which have excellent dimensional stability and precision

Methods

A systematic review of the literature using the Medline, Cochrane, and EMBASE databases yielded two clinical and nine in vitro studies comparing the marginal and internal fit of FDPs and single crowns (SCs) made using digital methods and those made using conventional impression techniques. Factors affecting the fit and their impact on the accuracy of fit outcomes were evaluated.

Results

Restorations made using digital impression methods and those made using conventional impression techniques had statistically similar marginal discrepancies. The marginal and internal discrepancies of digital restorations were smaller than those with stereolithographic (SLA)/polyurethane dies.

A comparison of the conventional and digital groups was also done with respect to the “pressing” and CAD-CAM fabrication techniques. The marginal and internal discrepancies were similar between the two

Discussion

Overall, the digital impression technique was associated with similar or better marginal and internal fit for restorations regardless of the material used or the fabrication technique compared to the conventional impression technique. Most of the information came from in vitro studies, so further investigation is needed.

Clinical Significance

Digital methods are becoming widely available and are likely to represent the future for obtaining dental impressions. Digital impression accuracy is

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Chochlidakis KM, Papaspyridakos P, Geminiani A, et al: Digital versus conventional impressions for fixed prosthodontics: A systematic review and meta-analysis. J Prosthet Dent 116:184-190, 2016

Reprints available K Chochlidakis, 625 Elmwood Ave, Rochester, NY 14620; e-mail: [email protected]

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