title: Effect of aging on coronal microleakage in access cavities through metal ceramic crowns restored with resin composites.
abstract: OBJECTIVE
  The purpose of this in vitro study was to determine if packable resin composite with/without flowable resin composite has the ability to prevent coronal leakage in restored endodontic access openings following aging.
  
  
  METHODS
  Eighty simulated standardized access cavities of metal-ceramic crowns were fabricated and fixed on Vitrebond cavities filled with an epoxy resin. The specimens were randomly divided into two main groups: (1) Group A-Access cavities filled with only packable composite (Filtek P60); (2) Group B-Access cavities filled with Filtek P60 and a flowable composite (Filtek Z350) as liner. Each main group was further subdivided randomly into four subgroups according to water storage and thermocycling periods. All specimens were immersed in blue ink solution for 24 hours and then sectioned into quadrants. The extension of blue ink along the metal-ceramic crown/composite resin interface was measured linearly using image analyzer and then analyzed by three-way ANOVA and independent t-test with a Mann-Whitney test. The level of significance was set at p < 0.05.
  
  
  RESULTS
  All tested subgroups demonstrated different levels of microleakage. There was no significant difference related to restorative technique; however, there was a significant difference related to water storage and thermocycling.
  
  
  CONCLUSIONS
  All tested techniques and materials in this study showed microleakage. Packable composite while a flowable liner showed a marginally better result than packable composite alone. Excessive thermocycling resulted in significant differences among the test groups.
authors.affiliation: Department of Conservative Dentistry, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia.
authors.forename: Ali Abdullah Alwan
authors.initials: AA
authors.lastname: Al-Maqtari
authors.forename: Joo Loon
authors.initials: JL
authors.lastname: Lui
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry*; D003442:Crowns; D003722:Dental Alloys / Q000737:chemistry; D003763:Dental Leakage / Q000145:classification*; D003764:Dental Materials / Q000737:chemistry*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D004853:Epoxy Resins / Q000737:chemistry; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007281:Ink; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012390:Root Canal Therapy / Q000379:methods*; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D004396:Coloring Agents; D003188:Composite Resins; D003722:Dental Alloys; D003764:Dental Materials; D017220:Dentin-Bonding Agents; D004853:Epoxy Resins; C438835:Filtek P60 Composite Resin; D005899:Glass Ionomer Cements; D016876:Metal Ceramic Alloys; D017680:Potassium Compounds; C528569:Rely-X; D019279:Resin Cements; C425844:Scotchbond Multi-Purpose Plus; C533204:filtek Z350; D014867:Water; C016447:feldspar; C067790:Vitrabond; C047040:Vita VMK 68