title: 18-year survival of posterior composite resin restorations with and without glass ionomer cement as base.
abstract: OBJECTIVE
  Advantages and disadvantages of using intermediate layers underneath resin-composite restorations have been presented under different perspectives. Yet, few long-term clinical studies evaluated the effect of glass-ionomer bases on restoration survival. The present study investigated the influence of glass-ionomer-cement base in survival of posterior composite restorations, compared to restorations without base.
  
  
  METHODS
  Original datasets of one dental practice were used to retrieve data retrospectively. The presence or absence of an intermediate layer of glass-ionomer-cement was the main factor under analysis, considering survival, annual failure rate and types of failure as outcomes. Other investigated factors were: patient gender, jaw, tooth, number of restored surfaces and composite. Statistical analysis was performed using Fisher's exact test, Kaplan-Meier method and multivariate Cox-regression.
  
  
  RESULTS
  In total 632 restorations in 97 patients were investigated. Annual failure rates percentages up to 18-years were 1.9% and 2.1% for restorations with and without base, respectively. In restorations with glass-ionomer-cement base, fracture was the predominant reason for failure, corresponding to 57.8% of total failures. Failure type distribution was different (p=0.007) comparing restorations with and without base, but no effect in the overall survival of restorations was found (p=0.313).
  
  
  CONCLUSIONS
  The presence of a glass-ionomer-cement base did not affect the survival of resin-composite restorations in the investigated sample. Acceptable annual failure rates after 18-years can be achieved with both techniques, leading to the perspective that an intermediate layer, placed during an interim treatment, may be maintained without clinical detriment, but no improvement in survival should be expected based on such measure.
authors: School of Dentistry, IMED Faculdade Meridional, Rua Senador Pinheiro, 304, 99070-220 Passo Fundo, Brazil; Graduate Program in Dentistry, Federal University of Pelotas, Gonçalves Chaves, 457, 96015-560 Pelotas, Brazil. Electronic address: fvandesande@gmail.com.
authors: Françoise H
authors: FH
authors: van de Sande
authors: Av. Duque de Castilhos, 1348, s. 203, 95010-000 Caxias do Sul, Brazil.
authors: Paulo A Da Rosa
authors: PA
authors: Rodolpho
authors: Graduate Program in Dentistry, Federal University of Pelotas, Gonçalves Chaves, 457, 96015-560 Pelotas, Brazil.
authors: Gabriela R
authors: GR
authors: Basso
authors: Graduate Program in Dentistry, Federal University of Pelotas, Gonçalves Chaves, 457, 96015-560 Pelotas, Brazil.
authors: Rômulo
authors: R
authors: Patias
authors: Graduate Program in Dentistry, Federal University of Pelotas, Gonçalves Chaves, 457, 96015-560 Pelotas, Brazil.
authors: Quéren F
authors: QF
authors: da Rosa
authors: Graduate Program in Dentistry, Federal University of Pelotas, Gonçalves Chaves, 457, 96015-560 Pelotas, Brazil.
authors: Flávio F
authors: FF
authors: Demarco
authors: Radboud University Medical Center, Philips van Leydenlaan 25, 6525 EX Nijmegen, The Netherlands.
authors: Niek J
authors: NJ
authors: Opdam
authors: Graduate Program in Dentistry, Federal University of Pelotas, Gonçalves Chaves, 457, 96015-560 Pelotas, Brazil.
authors: Maximiliano S
authors: MS
authors: Cenci
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D019232:Dental Restoration Failure; D003793:Dental Restoration, Permanent / Q000379:methods*; D005260:Female; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008297:Male; D008689:Methacrylates; D011140:Polyurethanes; D019279:Resin Cements; D012189:Retrospective Studies; D012822:Silicon Dioxide; D013499:Surface Properties; D015040:Zirconium
chemical_list: C084111:Charisma composite resin; D003188:Composite Resins; D005899:Glass Ionomer Cements; D008689:Methacrylates; C404623:P-50 APC; D011140:Polyurethanes; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; C121818:Tetric ceram; C083568:Z100 composite resin; C065770:Herculite XR; C067788:scotchbond 2; C070604:XR Bond; D012822:Silicon Dioxide; D015040:Zirconium
keywords: Composite resin; Glass ionomer cement; Permanent dental restoration; Retrospective studies; Survival analysis