title: Micromechanical Intervention in Sandwich Restoration.
abstract: OBJECTIVE
  To evaluate the sealing ability of two different types of Glass Ionomer Cements (GICs) used for sandwich restorations and assess the effect of acid etching of GIC on microleakage at GIC-resin composite interface.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Department of Operative, DIEKIOHS (DUHS) and NED University, Karachi, from February to June 2011.
  
  
  METHODS
  Eighty cavities were prepared on the proximal surfaces of 40 permanent human premolars (2 cavities per tooth), assigned to 4 groups (n=20) and restored as follows: Group CIE - Conventional GIC (CI) was applied onto the axial and cervical cavity walls, allowed setting for 5 minutes and acid etched (E) along the cavity margins with 37% phosphoric acid for 15 seconds, washed for 30 seconds and dried; the adhesive system was applied and light cured for 10 seconds, completing the restoration with composite resin light cured for 40 seconds; Group CIN - same as Group CIE, except for acid etching of the CI surface; Group RME - same as CIE, but using a resin modified GIC (RMGIC); Group RMN - same as Group RME, except for acid etching of the RMGIC surface. Specimens were soaked in 1% methylene blue dye solution at 37&ordm;C for 24 hours, rinsed under running water for 15 minutes, bisected mesiodistally and dye penetration was measured following the ISO/TS 11405-2003 standard. Kruskal Wallis and post Hoc tests significant differences in the microleakage among all the four groups.
  
  
  RESULTS
  There was a significant difference between the two groups of GICs (RMGIC and CI, p=0.001). There was no significant difference in between the two sub-groups that is between CIN and CIE (p=0.656), and between Groups RME and RMN (p=0.995).
  
  
  CONCLUSIONS
  Phosphoric acid etching of GIC, prior to the placement of composite resin, does not improve the sealing ability of sandwich restorations. RMGIC was more effective in preventing dye penetration at the GIC-resin composite dentine interfaces than CI.
authors.affiliation: Department of Dental Materials, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Science, (DUHS), Karachi.
authors.forename: Tabinda Nawaz
authors.initials: TN
authors.lastname: Khan
authors.affiliation: Department of Operative Dentistry, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Science, (DUHS), Karachi.
authors.forename: Syed Yawar
authors.initials: SY
authors.lastname: Ali Abidi
authors.affiliation: Department of Pathology, Dow International Medical College, Karachi.
authors.forename: Khush Bakht
authors.initials: KB
authors.lastname: Nawaz Khan
authors.affiliation: Department of Operative Dentistry, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Science, (DUHS), Karachi.
authors.forename: Shahbaz
authors.initials: S
authors.lastname: Ahmed
authors.affiliation: Department of Operative Dentistry, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Science, (DUHS), Karachi.
authors.forename: Fazal Ur
authors.initials: FU
authors.lastname: Rehman Qazi
authors.affiliation: Department of Oral Pathology, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Science, (DUHS), Karachi.
authors.forename: Noureen
authors.initials: N
authors.lastname: Saeed
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D003188:Composite Resins / Q000737:chemistry*; D003737:Dental Cavity Preparation / Q000379:methods; D003738:Dental Cements / Q000737:chemistry*; D003763:Dental Leakage / Q000145:classification*; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D003804:Dentin; D017220:Dentin-Bonding Agents / Q000737:chemistry; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D019279:Resin Cements / Q000737:chemistry*; D012117:Resins, Synthetic / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003738:Dental Cements; D003764:Dental Materials; D017220:Dentin-Bonding Agents; D005899:Glass Ionomer Cements; D019279:Resin Cements; D012117:Resins, Synthetic