الفهرس 
Effect of remineralization on bond strengthOnly 14 pages are availabe for public view
 |  | from | 160 |  |  |
| | | from | 160 | | |
Abstract
This in vitro study was designed to investigate the effect of different remineralizing regimens and acid etch pretreatment on bonding to two self-etch adhesive systems. A total of 48 bovine incisors were used in this study, 32 for micro shear bond strength, and 16 for scanning electron microscopy examination (SEM).
For micro shear bond strength testing, half of the labial surfaces of all teeth were demineralized with lactic acid, while the other half remains untreated. Then, teeth were divided into four equal groups of 12 specimens each according to the remineralizing regimens. In the first group, no remineralization was done (control), while remineralization with natural saliva was done for the second group. Remineralization with fluoride containing agent (Fluocal Mouth Wash), and casein containing agent (Tooth Mousse) for the third and the fourth groups respectively. Each group was further subdivided into two subgroups of 6 specimens each, according to the self-etch adhesive system used. In the first subgroup, the mild self-etch adhesive system (G-Bond) was applied, while the aggressive self-etch adhesive system (Adper Prompt L-Pop) for the second subgroup. Each subgroup was further divided into two smaller divisions of 3 specimens each, according to whether an extra acid etching (Scotchbond etchant) preceded the bonding agent application. FiltekP60 resin composite was used in conjunction with the tested self-etch adhesive systems. The specimens were tested using a shear bond strength testing protocol in a computer-controlled universal testing machine at crosshead speed of 0.5 mm/min. For SEM examination, the same grouping was utilized for 16 teeth for resin/enamel interface examination.
Micro shear bond strength testing results revealed that enamel samples remineralized with Fluocal Mouth Wash or Tooth Mousse showed the statistically significantly highest mean micro shear bond strength values compared to other groups. Meanwhile, different self-etch adhesive systems did not statistically affect the mean micro shear bond strength values of the tested groups. However, etched enamel samples with phosphoric acid prior to bonding procedures significantly increases the mean micro shear bond strength values compared to non etched enamel samples. Also, demineralized/remineralized enamel samples showed higher micro shear bond strength values than untreated or remineralized groups.
SEM examination of resin/enamel interfaces revealed that deepening of the etching pattern was consistent with increase in the length of resin tags and is dependent on phosphoric acid preconditioning of enamel rather than type of self-etch adhesive system used.
Conclusions:
1. The use of remineralizing agents has positive effect on bonding of self-etch adhesive system to enamel.
2. Both tested remineralizing agents (fluoride or casein containing agents) have similar effect on shear bond strength to resin composite.
3. Natural saliva has lower remineralizing potential than commercial fluoride or casein containing remineralizing agents.
4. In general, the aggressiveness of the self-etching adhesive systems has no influence on the bond strength to enamel, however the effect was substrate dependent.
5. Phosphoric acid pretreatment of enamel is recommended before bonding procedures of mild or aggressive self-etch adhesive systems.
6. Application of self-etch adhesive systems without phosphoric acid pre etching is preferable in case of restoring remineralized incipient enamel carious lesions.
Acid etching improves the immediate bond to enamel. However, the cohesive enamel failure in enamel may compromise the long term durability of the adhesive bond. Therefore, further studies are needed to investigate the acid pre etching step in terms of concentration and/or time of application to reach the optimum conditions that enhance the bond strength without jeopardizing the enamel substrate.