Evaluation of the bonding mechanism of an adhesive material to primary teeth.
OBJECTIVE
The aim of this study was to evaluate with scanning electron microscopy (SEM) the bonding mechanism of the one-bottle adhesive Prime&Bond NT (Dentsply, PBNT) to enamel and dentin of deciduous teeth, following different methods of substrate treatment.


METHODS
Eighteen extracted posterior deciduous teeth were randomly divided into 6 groups (N=3). The experimental groups differed for substrate and method of substrate conditioning prior to bonding with PBNT. Group 1: 36% phosphoric acid (PA)/PBNT on dentin; group 2: PA/PBNT on enamel; group 3: non-rinsing conditioner (NRC) (Dentsply)/PBNT on dentin; group 4: NRC/PBNT on enamel; group 5: PBNT on dentin without any previous conditioning; group 6: PBNT on enamel without any previous conditioning. On all the specimens, following the application of the adhesive solution, Dyract AP was layered on top and light-cured. The bonded specimens were processed for SEM observations.


RESULTS
When used in combination with 36% phosphoric acid, PBNT was able to form a hybrid layer with resin tags on both enamel and dentin. Following conditioning with NRC, a thinner hybrid layer with shorter resin tags was developed on dentin; on enamel an etching pattern was still detectable. When only PBNT was applied without any previous conditioning, on dentin neither hybrid layer nor resin tags were visible; no sign of micromechanical bonding could be seen on the untreated enamel.


CONCLUSIONS
The bonding mechanism of the one-bottle adhesive Prime&Bond NT on enamel and dentin of deciduous teeth is effective only following substrate conditioning with 36% phosphoric acid or NRC.
Department of Dental Materials, College of Dental Medicine, University of Siena, Italy.
Gaia
G
Gotti
Cecilia
C
Goracci
Franklin
F
García-Godoy
Marco
M
Ferrari
D000134:Acid Etching, Dental; D001840:Dental Bonding / Q000379:methods*; D003743:Dental Enamel; D003745:Dental Enamel Permeability; D003804:Dentin; D003806:Dentin Permeability; D017220:Dentin-Bonding Agents; D006801:Humans; D008298:Maleates; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids; D011109:Polymethacrylic Acids; D019279:Resin Cements; D014094:Tooth, Deciduous
D017220:Dentin-Bonding Agents; D008298:Maleates; D010756:Phosphoric Acids; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D019279:Resin Cements; C444699:non-rinse conditioner; C030242:phosphoric acid