To assess the in vivo marginal and internal fit of single tooth-supported single crowns fabricated using digital (Align iTero and 3M True-Definition intraoral scanners) and conventional impression techniques.
Marginal and internal fit are two of the main clinical criteria used for quality assessment of fixed restorations.1-3
In previous studies, an acceptable marginal gap ranged from 34 to 119 μm,4 and fixed restorations with marginal gaps less than 120μm were considered more likely to be successful.5
The internal fit is an important criterion as well, and has an effect on the seating of the crown and consequently the marginal fit. Indeed, a 25 μm thickness of die spacer has been shown to improve the seating of a crown and increase the retention of the restoration by 25%.6
The most common conventional impression materials used for fixed prosthodontics final impressions are the elastomeric materials, polyether (PE) and vinyl poly-siloxane (VPS). These materials exhibit great dimensional stability and precision and have been successfully used in fixed prosthodontics for many decades.7,8
Recent advances in technology have introduced new digital impression and crown fabrication procedures, with their use steadily increasing in clinical practice.9,10 Advances in computer-aided design/computer-aided manufacturing (CAD/CAM) technology have led to the production of more accurately fitting milled restorations,9,10 and more widespread use of a digital workflow for prosthesis fabrication.
While there are some in vitro studies measuring the marginal and internal fit of tooth-supported all-ceramic dental restorations fabricated with conventional and digital techniques, there is unfortunately a lack of clinical studies comparing these two different techniques in vivo.