title: A clinical study comparing marginal and occlusal accuracy of crowns fabricated from double-arch and complete-arch impressions.
abstract: BACKGROUND
  The double-arch impression technique is widely used in the provision of laboratory fabricated restorations. However, there is little clinical evidence to support or refute its use. The aim of this prospective clinical study was to evaluate the occlusion and marginal fit of posterior full crowns made from double-arch impressions, and to compare these to control crowns fabricated from conventional complete-arch impressions.
  
  
  METHODS
  Ten patients requiring single posterior ceramo-metal full crowns had both double-arch and complete-arch impressions taken of the prepared tooth. Two crowns were fabricated for each tooth, using the casts made from both impression methods. Both crowns were tried in and the occlusion and margins evaluated. The results were composed using nonparametric statistical analysis with the probability level for significance at alpha=0.05.
  
  
  RESULTS
  The crowns fabricated from the double-arch impression were found to be more accurate in closure to the intercuspal position and had fewer interferences in lateral excursions. There were no significant differences between the two crown groups regarding protrusive interferences and margin quality.
  
  
  CONCLUSIONS
  Crowns fabricated from the double-arch impressions were equivalent in marginal accuracy and superior occlusally to crowns fabricated from the complete-arch impressions.
authors.affiliation: jeffcox74@hotmail.com
authors.forename: J R
authors.initials: JR
authors.lastname: Cox
mesh_terms: D003442:Crowns; D003724:Dental Arch / Q000033:anatomy & histology; D003760:Dental Impression Materials; D003761:Dental Impression Technique; D003768:Dental Occlusion, Centric; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D006801:Humans; D016876:Metal Ceramic Alloys; D011446:Prospective Studies; D012826:Silicone Elastomers; D013499:Surface Properties; D019231:Tooth Preparation, Prosthodontic
chemical_list: D003760:Dental Impression Materials; D016876:Metal Ceramic Alloys; D012826:Silicone Elastomers; D003776:Dental Porcelain