title: Bond strength of restorative materials to hydroxyapatite inserts and dimensional changes of insert-containing restorations during polymerization.
abstract: OBJECTIVE
  To determine the shear bond strength (SBS) between synthetic controlled porous hydroxyapatite (HAP) inserts and restorative materials and dimensional changes of insert-containing restorations during curing.
  
  
  METHODS
  Cylinder-shaped HAP inserts (4mm in diameter, 1.6mm thick) were cemented in dentin discs (5mm×1.6mm), cut mid-coronally from human third molars, using one of the following materials: universal microhybrid composite Filtek Z250, flowable composite Filtek Ultimate or glass-ionomer Vitrebond (all 3M ESPE). SBS of the same materials to HAP inserts was tested in a universal testing machine. Three-dimensional digital image correlation system Aramis (GOM) was used to measure strains and displacements. Data were statistically analyzed using one-way ANOVA with Tukey's post-test (α=0.05).
  
  
  RESULTS
  SBS of restorative materials to HAP inserts ranged between 12.2±2.1MPa (Filtek Z250) and 0.7±0.4MPa (Filtek Z250 without an adhesive). The 'total-etch' approach of adhesive application significantly increased SBS of both Filtek Z250 (12.2±2.1MPa) and Filtek Ultimate flowable (9.5±2.5MPa) compared to the 'self-etch' approach (8.2±1.6MPa and 4.4±0.9MPa, respectively) (p<0.05). HAP inserts reduced polymerization shrinkage to below 0.5% as well as displacements in the central region of the restorations. Peripheral shrinkage of restorative materials was similar with and without HAP inserts as were displacements of Filtek Z250 and Vitrebond.
  
  
  CONCLUSIONS
  Replacing major part of dentin clinically, especially in large cavities, HAP inserts may shorten clinical working time, improve dimensional stability of the restoration by reducing central shrinkage and displacements and provide adhesive bonding to universal composites following a 'total-etch' approach.
authors.affiliation: University of Belgrade, School of Dental Medicine, DentalNet Research Group, Rankeova 4, Belgrade, Serbia.
authors.forename: Maja
authors.initials: M
authors.lastname: Lezaja
authors.affiliation: University of Belgrade, Faculty of Technology and Metallurgy, Karnegijeva 4, Belgrade, Serbia.
authors.forename: Djordje
authors.initials: D
authors.lastname: Veljovic
authors.affiliation: University of Belgrade, School of Dental Medicine, DentalNet Research Group, Rankeova 4, Belgrade, Serbia.
authors.forename: Dragica
authors.initials: D
authors.lastname: Manojlovic
authors.affiliation: University of Belgrade, Innovation Center of Faculty of Mechanical Engineering, Kraljice Marije 16, Belgrade, Serbia.
authors.forename: Milos
authors.initials: M
authors.lastname: Milosevic
authors.affiliation: University of Belgrade, Faculty of Mechanical Engineering, Kraljice Marije 16, Belgrade, Serbia.
authors.forename: Nenad
authors.initials: N
authors.lastname: Mitrovic
authors.affiliation: University of Belgrade, Faculty of Technology and Metallurgy, Karnegijeva 4, Belgrade, Serbia.
authors.forename: Djordje
authors.initials: D
authors.lastname: Janackovic
authors.affiliation: University of Belgrade, School of Dental Medicine, DentalNet Research Group, Rankeova 4, Belgrade, Serbia. Electronic address: vesna.miletic@stomf.bg.ac.rs.
authors.forename: Vesna
authors.initials: V
authors.lastname: Miletic
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D066298:In Vitro Techniques; D055115:Light-Curing of Dental Adhesives; D008963:Molar; D058105:Polymerization; D013499:Surface Properties
chemical_list: D000538:Aluminum Silicates; C075816:Ceram-Fil; D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C000590992:Filtek Supreme Ultra; C000621148:Filtek Ultimate Flowable; C444701:Filtek Z250; D005899:Glass Ionomer Cements; C075815:IPS-Empress ceramic; D003776:Dental Porcelain; C067790:Vitrabond; D017886:Durapatite
keywords: Adhesive; Bond strength; Composite; Dentin; Glass-ionomer; Hydroxyapatite; Inserts; Polymerization shrinkage