Paper: Marginal fit of all-ceramic crowns using conventional and digital impressions (AADR Annual Meeting (March 21-24, 2012))

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 90^o 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).

Results:

Marginal gap width in μm:

Mean

Mesial margin

Distal margin

Facial margin

Lingual margin

VPS

58.62±47.87

59.52±48.81

51.05±33.62

51.80±38.94

69.15±63.60

iTero

60.85±53.58

60.45±42.03

69.40±53.08

67.95±72.28

54.55±44.48

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

See more of: Prosthodontics Applied Research
See more of: Prosthodontics Research

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