Compressive strength recovery by composite onlays in primary teeth. Substrate treatment and luting agent effects.
OBJECTIVE
To evaluate 1% NaOCl treatment and two resin luting agent effects on compressive strength recovery in composite onlays on primary teeth and to analyze the fractures type.


METHODS
Forty sound primary molars crowns were prepared in the standard machine and randomly divided into four groups (n=10): G1 (1% NaOCl/ 30 min+EnForce); G2 (without 1% NaOCl EnForce); G3 (1% NaOCl/ 30 min+Rely X); G4 (without 1% NaOCl+Rely X). The onlays were made using Z250 composite on plaster models. Ten sound teeth were used as control group (CG). All groups were submitted to compression mechanic test in a universal test machine INSTRON at 1mm/min cross-head speed. After that, the data (kgf) were submitted to ANOVA test (alpha=0.05). Finally, the fracture types were classified in a crescent scale (1-5) related with severity degree and submitted to Fisher's Exact Test (p<0.05). Scanning electronic microscope analysis was done in order to illustrate the fractures sites.


RESULTS
The values of compressive strength of experimental groups did not differ each others neither from control group (p>0.05). The results from fracture type showed that types 5 and 4 fractures (most severe) present the highest percentage to experimental groups. Conversely, the CG showed higher percentage of fracture types 2 and 3.


CONCLUSIONS
This research found that the composite onlays recovered the compressive strength compared to sound teeth, regardless of the substrate treatment and cement agent used. Nevertheless, no group showed similar type of fractures to CG, which had more frequency of less severe fracture types.
Borges
Ana Flávia Sanches
AF
Dental Materials and Pediatric Dentistry Departments of the Piracicaba Dental School, State University of Campinas, Piracicaba, Av. Limeira, 901, Piracicaba, SP 13414-903, Brazil.
Correr
Gisele Maria
GM
Sinhoreti
Mário Alexandre Coelho
MA
Consani
Simonides
S
Sobrinho
Lourenço Correr
LC
Rontani
Regina Maria Puppin
RM
D000096:Acetone / Q000737:chemistry; D000134:Acid Etching, Dental; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D019245:Compressive Strength; D003737:Dental Cavity Preparation / Q000379:methods; D003738:Dental Cements / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D017220:Dentin-Bonding Agents / Q000737:chemistry; D004202:Disinfectants / Q000627:therapeutic use*; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D007284:Inlays; D008855:Microscopy, Electron, Scanning; D008963:Molar / Q000187:drug effects / Q000503:physiopathology; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D019228:Tooth Crown / Q000187:drug effects / Q000503:physiopathology; D014082:Tooth Fractures / Q000145:classification / Q000503:physiopathology; D014094:Tooth, Deciduous / Q000187:drug effects / Q000503:physiopathology*
D003188:Composite Resins; D003738:Dental Cements; D003764:Dental Materials; D017220:Dentin-Bonding Agents; D004202:Disinfectants; C103503:EnForce-Sure Cure; C444701:Filtek Z250; D005899:Glass Ionomer Cements; D011109:Polymethacrylic Acids; D019279:Resin Cements; C084550:Vitremer; C444444:prime and bond 2.1; C115612:single bond; D000096:Acetone; D017438:Bisphenol A-Glycidyl Methacrylate; D012973:Sodium Hypochlorite