title: Chair-side generated posterior lithium disilicate crowns after 4 years.
abstract: OBJECTIVE
  The objective of this prospective clinical study was to evaluate the performance of chair-side generated crowns after 48 months.
  
  
  METHODS
  Forty-one posterior full contour crowns made of a machinable lithium disilicate ceramic (e.max CAD LT) were inserted in 34 patients applying a chair-side CAD/CAM technique. One crown per patient was randomly selected for evaluation at baseline, after 6, 12, 24, 36, and 48 months according to modified US Public Health Service criteria.
  
  
  RESULTS
  After a mean observation time of 51 months (min, 48 months; max, 56 months; SD ± 2.3 months), 29 crowns were available for re-examination. Within the observation period, one failure occurred due to a crown fracture after 2.8 years. Four abutment teeth revealed signs of biological complications: Two abutment changed sensibility perception from positive to negative within the first 13 month. Two abutment teeth showed secondary caries below the crown margin, one after the 24, and another after the 48 month recall. Both abutments received cervical adhesive composite fillings. The failure-free rate was 96.3 % after 4 years according to Kaplan-Meier (CI: upper bound, 4.4 years; lower bound, 4.7 years).
  
  
  CONCLUSIONS
  Due to the fact that the secondary caries was not caused as a result of an inaccuracy of the crown margins and the endodontic complications were in a normal range, the clinical performance of the crowns was completely satisfying.
  
  
  CONCLUSIONS
  The chair-side application of lithium disilicate crowns can be recommended.
authors.affiliation: Department of Prosthodontics, Implantology and Biomaterials, Medical Faculty, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany. sreich@ukaachen.de
authors.forename: Sven
authors.initials: S
authors.lastname: Reich
authors.forename: Oliver
authors.initials: O
authors.lastname: Schierz
mesh_terms: D000328:Adult; D000368:Aged; D003442:Crowns; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013997:Time Factors
chemical_list: C520133:IPS e.max CAD LT; C493120:lithia disilicate; D003776:Dental Porcelain