title: Influence of surface treatment and cyclic loading on the durability of repaired all-ceramic crowns.
abstract: OBJECTIVE
  This study investigated the durability of repaired all-ceramic crowns after cyclic loading.
  
  
  METHODS
  Eighty In-ceram zirconia crowns were fabricated to restore prepared maxillary premolars. Resin cement was used for cementation of crowns. Palatal cusps were removed to simulate fracture of veneering porcelain and divided into 4 groups (n = 20). Fracture site was treated before repair as follows: roughening with diamond bur, (DB); air abrasion using 50 microm Al2O3, (AA) and silica coating using Cojet system followed by silane application, (SC). Control group (CG) 20 specimens were left without fracture. Palatal cusps were repaired using composite resin. Specimens were stored in water bath at 37 degrees C for one week. Ten specimens of each group were subjected to cyclic loading. Fracture load (N) was recorded for each specimen using a universal testing machine. Two-way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) test (a=.05) were used for statistical analysis.
  
  
  RESULTS
  There was statistically significant difference between control and tested groups, (p<0.001). Post Hoc analysis with the Tukey HSD test showed that cyclic loading fatigue significantly decreased means fracture load of control and test groups as follows (CG, 950.4+/-62.6 / 872.3+/-87.4, P = 0.0004), (DB, 624.2 +/-38 / 425.5+/- 31.7, P <.001), (AA, 711.5 +/-15.5 / 490 +/- 25.2, p <0.001) and (SC, 788.7 +/- 18.1 / 610.2 +/- 25.2, P <.001), while silica coating and silane application significantly increased fracture load of repaired crowns (p<0.05).
  
  
  CONCLUSIONS
  Repair of fractured In-ceram zirconia crowns after chairside treatment of the fracture site by silica coating and silane application could improve longevity of repaired In-ceram zirconia crowns.
authors.affiliation: Department of Conservative Dentistry and Fixed Prosthodontics, Faculty of Dentistry, Mansoura University, Egypt. aattia@mans.edu.eg
authors.forename: Ahmed
authors.initials: A
authors.lastname: Attia
mesh_terms: D000704:Analysis of Variance; D001641:Bicuspid; D020099:Coated Materials, Biocompatible; D003188:Composite Resins; D003442:Crowns; D003776:Dental Porcelain; D017269:Dental Prosthesis Repair; D003799:Dental Stress Analysis; D006801:Humans; D012821:Silanes; D012822:Silicon Dioxide; D018709:Statistics, Nonparametric; D013499:Surface Properties; D015040:Zirconium
chemical_list: D020099:Coated Materials, Biocompatible; D003188:Composite Resins; D012821:Silanes; D003776:Dental Porcelain; D012822:Silicon Dioxide; D015040:Zirconium; C028541:zirconium oxide