Insights Newsletter 2005

Precision Procera Prosthetics
Esthetic Reconstruction Using Procera All Ceramic Crowns

Balshi, TJ & Wolfinger, GJ

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Ceramometal crowns have been used successfully in prosthodontics for over 30 years. These crowns enable restoration of tooth form and function with reasonable esthetics. Since then many unsuccessful attempts have been made to fabricate ceramic crowns without a metallic substructure. The introduction of Procera all ceramic crowns (Nobel Biocare AB, Göteborg Sweden), however, has been a break through in providing well fitting, esthetically superior crowns.

All ceramic crowns are required in prosthodontics for a number of reasons. Some patients that require full coverage restorations may have an allergy or aversion to metals. Others may demand superior esthetics. All ceramic crowns never show a metallic facial margin; and translucency is possible due to the nature of the core material. In addition, the new computer technology for fabrication (CAD/CAM) insures consistent precision fit of the core while the low fusing porcelain veneering material provides more favorable wear characteristics when opposing enamel.

This issue of Prosthodontic Insights reviews some of the literature supporting the Procera All Ceram System from Nobel Biocare. The following clinical treatment is one of many successful cases restored at Pi Dental Center using this innovative Procera System.

A 32 year white female presented for initial consultation with the chief complaint of temporomandibular dysfunction, missing teeth and poor esthetics (Fig 1). A thorough clinical and radiographic evaluation was performed. A comprehensive prosthodontic and orthodontic treatment plan was coordinated to address the symptomatic dental malocclusion, replace missing teeth and restore proper form and function. A total of six root form implants were placed before and during orthodontic treatment, many of which were used to facilitate orthodontic movement. Orthodontic treatment was completed 2 ½ years later at which time prosthodontic reconstruction was initiated.

Procera crowns were selected for restoration of the maxillary anterior region due to their enhanced esthetic capability and favorable wear characteristics (Fig 2). The old ill-fitting opacious ceramometal crowns were removed from teeth #’s 6, 8 and 9. Post and cores were used to build up endodontically treated teeth #’s 8, 9 and 10. A final impression was taken of teeth #’s 6 through 11. The natural teeth were prepared with chamfered margins and the implant in the area of #7 was impressioned at the fixture level.

In the lab, a custom gold alloy abutment was fabricated for the implant upon which opaque was fired to mask out the gray abutment color. The five dies and the one custom abutment were scanned by the Procera scanning unit (Fig 3a,b) The margins were marked on the computer by the laboratory technician and the information was sent via modem to Sweden for fabrication of the densely sintered aluminous cores (Fig 4). After fabrication, the cores were returned to the laboratory and tried on the appropriate abutments. After the fit was verified, a liner was placed on the cores to facilitate bonding. Additional layers of liner may be placed to block out dark areas in the abutments. Low fusing veneering porcelain (AllCeram, Ducera Dental) was placed over the liner to build the teeth to proper form and function (Fig 5).

The crowns were tried in the mouth and interproximal and occlusal adjustments were made. The low fusing porcelain enables easy adjustments to the porcelain due to the softer texture. Finishing and polishing can be done chairside using rubber wheels if color alterations are not necessary.

The custom abutment on tooth #7 was screwed (Fig 6) into place and the access hole was covered with composite material. The composite material along with the opaque liner on the implant abutment will mask out any grayness shining through on the translucent Procera cores.

All six crowns were cemented using zinc phosphate cement (Flecks Zinc Phosphate Cement, Mizzy, Inc., Cherry Hill, NJ) (Fig 7). Different shades of zinc phosphate cement are available to further create slight modifications within the translucent crowns at the time of cementation. These Procera crowns provide the patient with an esthetically enhanced reconstruction without sacrificing marginal fit (Fig 2,8a,b). The low fusing porcelain will exhibit more favorable wear characteristics on the enamel of the opposing natural teeth over time.

The Procera® AllCeram System has changed the way dental laboratories fabricate crowns by incorporating computer technology to provide precision fit using esthetically superior all ceramic restorations. The next phase in the Procera® System will involve all ceramic fixed bridges for short spans in esthetically demanding situations.
Acknowledgments:
Robert Winkelman, CDT, MDT, Owner
Peter Kim, Ceramist
Fort Washington Dental Lab, Inc.
Tel: 215-628-4994
Email: fortwdental@aol.com
Web site: http://ftwashingtondentallab.com

 

Hacker et al

 Mean wear materials opposed by enamel sample Mean wear of opposed enamel
Olympia gold 0.32 um 9.0 um
AllCeram porcelain 4.3 um 60 um
Ceramco porcelain 3.7 um 230 um

Hacker CH, Wagner WC, Razzoog ME. An in vitro investigation of the wear of enamel on porcelain and gold in saliva. J Prosth Dent 1996; 75: 14-17.

 

October 1999 Newsletter

Procera Article
Research Evaluations
Precision of Fit
Flexure Test
5-Year Clinical Follow-Up
Investigation of Enamel Wear
Biaxial Flextural Strength
Use of Procera CAD/CAM System

Download Prosthodontic Insights Newsletter - October 1999 Vol. 12, No. 2

Scientific Articles and Ongoing Research

 

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