title: Early complications and performance of 327 heat-pressed lithium disilicate crowns up to five years.
abstract: OBJECTIVE
  The prospective follow-up aimed to assess the performance of lithium disilicate crowns and clinical reasons of adverse events compromising survival and quality.
  
  
  METHODS
  58 patients were treated with 375 heat-pressed monolithic crowns, which were bonded with resin cement. Annual recalls up to five years included a complete dental examination as well as quality assessment using CDA-criteria. Any need for clinical intervention led to higher complication rate and any failure compromised the survival rate. Kaplan-Meier-method was applied to all crowns and a dataset containing one randomly selected crown from each patient.
  
  
  RESULTS
  Due to drop-outs, 45 patients (31 females, 14 males) with the average age of 43 years (range = 17-73) who had 327 crowns (176 anterior, 151 posterior; 203 upper jaw, 124 lower jaw) were observed and evaluated for between 4 and 51 months (median = 28). Observation revealed 4 chippings, 3 losses of retention, 3 fractures, 3 secondary caries, 1 endodontic problem, and 1 tooth fracture. Four crowns had to be removed. Survival and complication rate was estimated 98.2% and 5.4% at 24 months, and 96.8% and 7.1% at 48 months. The complication rate was significantly higher for root canal treated teeth (12%, P<.01) at 24 months. At the last observation, over 90% of all crowns showed excellent ratings (CDA-rating Alfa) for color, marginal fit, and caries.
  
  
  CONCLUSIONS
  Heat pressed lithium disilicate crowns showed an excellent performance. Besides a careful luting, dentists should be aware of patients' biological prerequisites (grade of caries, oral hygiene) to reach full success with these crowns.
authors.affiliation: Department of Prosthodontics, Centre for Dentistry, Oral Medicine, and Maxillofacial Surgery, Eberhard-Karls-Universität Tübingen, Tübingen, Germany.
authors.forename: Fabian
authors.identifier: 0000-0002-7253-5923
authors.initials: F
authors.lastname: Huettig
authors.affiliation: Department of Prosthodontics, Centre for Dentistry, Oral Medicine, and Maxillofacial Surgery, Eberhard-Karls-Universität Tübingen, Tübingen, Germany.
authors.forename: Ulf Peter
authors.identifier: 0000-0002-9413-9788
authors.initials: UP
authors.lastname: Gehrke
keywords: Dental bonding; Dental marginal adaptation; Dental porcelain; Dental restoration failure; Follow-up studies; Survival analysis