title: A multicenter longitudinal clinical trial of a new system for restorations.
abstract: BACKGROUND
  A new method for fabrication of crowns and fixed partial dentures (Procera system) that involves electric discharge machining and copy milling has been developed. The metal used is unalloyed titanium, which can be processed as a single coping or multiple units joined to a pontic by laser welding.
  
  
  OBJECTIVE
  The single-unit coping or the fixed partial denture (FPD) substructure is then veneered with a low-fusing porcelain.
  
  
  METHODS
  In this article the clinical application of this technique was evaluated by six major universities in the United States. A total of 114 patients participated in this study, which involved 126 restorations (55 maxillary and 71 mandibular prostheses). There were 179 abutments, of which 73 were crowns and 53 were three-unit FPDs. Surface and color, anatomic form, and margin integrity were assessed 1 month after cementation and at 1 year with the California Dental Association (CDA) quality assessment evaluation system.
  
  
  RESULTS
  No statistically significant differences in CDA scores between the 1 month evaluations and the 1 year assessments were found for surface and color (p = 0.68), anatomic form (p > 0.99), or margin integrity (p = 0.57). By use of the lowest ranking in the three categories as the overall quality of the restoration, only 3.3% (two crowns and two FPDs) were not acceptable at the 1-month visit and 4.5% (two crowns and three FPDs) were not acceptable at the 1-year evaluation. At-the 1-month visit 96.6% (114) of the restorations were considered to be satisfactory, whereas 95.5% (107 restorations) were evaluated similarly at the 1-year evaluation.
  
  
  CONCLUSIONS
  The Procera system demonstrated, by use of the CDA criteria, its capability to produce quality prostheses that were rated satisfactory more than 95% of the time after insertion and maintained this high rating at least for 1 year.
authors.affiliation: Nobel Biocare Center for Excellence, School of Dentistry, University of Michigan, Ann Arbor, USA.
authors.forename: J
authors.initials: J
authors.lastname: Chai
authors.forename: G P
authors.initials: GP
authors.lastname: McGivney
authors.forename: C A
authors.initials: CA
authors.lastname: Munoz
authors.forename: J E
authors.initials: JE
authors.lastname: Rubenstein
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D003442:Crowns; D000044:Dental Abutments; D018772:Dental Marginal Adaptation; D003775:Dental Polishing / Q000379:methods*; D003776:Dental Porcelain; D017267:Dental Prosthesis Design / Q000379:methods* / Q000592:standards; D003830:Denture, Partial, Fixed; D004560:Electricity; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D016876:Metal Ceramic Alloys; D008669:Metallurgy; D008875:Middle Aged; D010512:Periodontal Index; D011446:Prospective Studies; D017797:Prosthesis Coloring; D012015:Reference Standards; D018709:Statistics, Nonparametric; D014025:Titanium; D016896:Treatment Outcome
chemical_list: D016876:Metal Ceramic Alloys; C077451:Procera; D003776:Dental Porcelain; D014025:Titanium