Durability of surface treatments and intermediate agents used for repair of a polished composite.
OBJECTIVE
To evaluate the effects of surface treatment and intermediate agent hydrophilicity on durability of the composite repair by means of the microtensile bond strength test (microTBS) and silver nitrate uptake (SNU) and the effects of surface treatment on composite roughness (Ra) and micromorphological features (SEM).


METHODS
Thirty resin composite blocks (4x6x6 mm) (Opallis, FGM) were polished after seven days and divided into three groups: no treatment (NT); roughening with a fine-grit diamond bur (DB); 50 microm aluminum oxide sandblasting (AO). A hydrophobic (Adhesive bottle, Scotchbond MultiPurpose [SBMP]) or hydrophilic adhesive (Adper Single Bond 2 [SB]) was then applied. The same composite was used for repair. Composite-composite bonded sticks (0.6 mm2) were tested immediately ([IM) or after six months (6 M) of water storage in tension (1.0 mm/minute). Two bonded sticks from each resin composite block were immersed in a 50% (w/v) solution of silver nitrate, photo-developed and analyzed by SEM. The composite specimens after surface treatments were analyzed with a contact profilometer (Ra) and SEM. Three-way repeated measures and one-way ANOVA were used to analyze data from the microTBS and Ra, respectively (alpha = 0.05).


RESULTS
AO showed the highest composite repair strength (MPa) and Ra (microm) (52.7 +/- 6.4; 4.1 +/- 0.5), while the no treatment group (36.1 +/- 6.1; 0.57 +/- 0.5) showed the low est. DB (44.1 +/- 5.6; 1.5 +/- 0.2) had an intermediate performance. The Ra results were confirmed by SEM images. SNU was observed only in SB specimens after 6M for all groups.


CONCLUSIONS
Aluminum oxide treatment provides the highest composite repair strength, regardless of the hydrophilicity of the intermediate agent and storage period. Early signs of degradation were detected for SB after six months as silver nitrate deposits within the adhesive layer.
Costa
Thays R F
TR
School of Dentistry, University Estadual de Ponta Grossa, Faculdade de Odontologia, Ponta Grossa, Paraná, Brazil.
Ferreira
Sabrina Queji
SQ
Klein-Júnior
Celso Afonso
CA
Loguercio
Alessandro Dourado
AD
Reis
Alessandra
A
D000537:Aluminum Oxide; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003775:Dental Polishing; D017269:Dental Prosthesis Repair / Q000379:methods; D003793:Dental Restoration, Permanent; D003799:Dental Stress Analysis; D008855:Microscopy, Electron, Scanning; D011897:Random Allocation; D019279:Resin Cements; D012835:Silver Nitrate; D013499:Surface Properties; D013718:Tensile Strength
D003188:Composite Resins; D019279:Resin Cements; C084018:Scotchbond Multi-Purpose; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; D012835:Silver Nitrate; D000537:Aluminum Oxide