991 Marginal fit of all-ceramic crowns using conventional and digital impressions

Friday, March 23, 2012: 3:30 p.m. - 4:45 p.m.
Presentation Type: Poster Session
J. PHARK1, A.L. OLIVEIRA2, N. SARTORI3, E.M.A. GIRO4, R. KAHN5, and S. DUARTE5, 1Herman Ostrow School of Dentistry - Divison of Restorative Sciences, University of Southern California, Los Angeles, CA, 2Universidade Est. Paulista Julio Mesquita, São Carlos, Brazil, 3Universidade Federal de Santa Catarina, Florianopolis, Santa Catarina, Brazil, 4Faculdade de Odontologia de Araraquara da UNESP, Universidade Est. Paulista Julio Mesquita, Araraquara, Brazil, 5Division of Restorative Sciences, University of Southern California, Los Angeles, CA

Objectives: To compare the marginal fit of pressed all-ceramic crowns made on dies obtained from conventional vinyl polysiloxane (VPS) and digital impression system.

Methods: A partial maxillary posterior typodont with ideal teeth shape and interproximal contact was used. An all-ceramic full-coverage crown preparation with shoulder margins and 90o finishing line was performed on the first maxillary molar. The full-coverage preparation was used as master preparation from which VPS and digital scans were made.

Ten conventional VPS impressions were made by double-mix technique using a light and heavy body material (Extrude WASH, Extrude EXTRA, Kerr). Impressions were poured-up with die stone (Hard Rock, Whip Mix), sectioned and trimmed. The master preparation and typodont were scanned 10 times using iTero (Cadent) to obtain the digital impressions. A milled polyurethane model (iTero Model, Cadent) was obtained from each scan. Pressed all-ceramic crowns (e.max Press, Ivoclar) were fabricated on each die. Marginal fit was evaluated using the replica technique: each crown was filled with a light body PVS (Imprint 3, 3M ESPE) and seated onto the master preparation under a pressure of 1 kg. After removal of the crown the thin VPS film was embedded in heavy body VPS material. Cross-sectional slices in mesio-distal and facio-lingual direction of the replica were photographed and analyzed under a stereomicroscope. Thickness of the VPS film was measured to evaluate marginal gap width. The data were submitted to t-Test (α=.05).


Marginal gap width in μm:


Mesial margin

Distal margin

Facial margin

Lingual margin













No statistically significant differences were found between conventional and digital impressions.

Conclusions: Marginal fit of pressed all-ceramic crowns obtained from conventional VPS or digital impressions are comparable.

Keywords: CAD/CAM, Ceramics, Digital impression, Impression materials and Prosthodontics