Does the method of caries induction influence the bond strength to dentin of primary teeth?

Comparison of Different Adhesive Systems on Bond Strength of Resin Composite Posts Placed in Primary Teeth

Background

This study evaluated the push-out bond strength of resin composite posts to the intracanal dentin in primary teeth using different adhesive systems.

Materials and Methods

In this experimental study, sixty-eight primary lateral incisors were randomly allocated in four groups (n = 17): Adper Single Bond 2 (ASB), Clearfil SE Bond 2 (CSE), G-Premio Bond in etch-and-rinse mode (GP-ER), and G-Premio Bond in the self-etch mode (GP-SE). The coronal one third of root canals was filled with resin composite. The push-out test was performed using a universal testing machine. ANOVA and LSD tests were used to analyze the data (P < 0.05).

Results

One-way ANOVA showed significant differences between the four groups in push-out bond strength (P = 0.002). The ASB and GP-SE groups showed lower and higher bond strengths, respectively. The failure mode distribution did not differ between the bonding agents used (P = 0.763). Adhesive and mixed failures were more frequent.

Conclusion

The GP-SE, GP-ER, and CSE exhibited significantly higher push-out bond strength than ASB. A universal adhesive system and 6th generation self-etch adhesives are recommended for use with resin composite posts in primary anterior teeth. Regarding the advantages of these bonding agents, such as fewer clinical steps, lower technical sensitivity, and easy application, they can be a good option for restoring primary teeth with short resin composite posts.

Does silver diammine fluoride concentration influence on bonding to carious dentinal lesions in primary teeth?

PURPOSE

This in vitro study evaluated the microshear bond strength (μSBS) of a universal adhesive after silver diammine fluoride (SDF) application at different concentrations on carious dentinal lesions in primary teeth.

METHODS

Flat dentin carious-induced surfaces from 40 primary molars were randomly assigned to four experimental groups: without SDF treatment (control), 12% SDF, 30% SDF, or 38% SDF application. After 14 days of storage in artificial saliva at 37 °C, a universal adhesive system (Scotchbond Universal, 3 M ESPE) was applied in the etch-and-rinse mode and resin composite cylinders were built (0.72 mm²). After 24 h of water storage, the μSBS test was performed and the failure mode was determined. Data were analysed using one-way ANOVA and Tukey's post hoc tests (α = 0.05).

RESULTS

The application of 38% SDF resulted in higher μSBS mean than control and use of 12% SDF (p = 0.006). No significant differences were observed among control, 12% SDF, and 30% SDF. All specimens tested showed adhesive/mixed failure.

CONCLUSION

The use of SDF does not jeopardise the bonding of a universal adhesive applied in the etch-and-rinse mode to carious dentinal lesions in primary teeth, irrespective of the product concentration.

The impact of artificially caries-affected dentin on bond strength of multi-mode adhesives

Aim:

The aim of this study is to evaluate the impact of dentin condition on bond strength of multi-mode adhesive systems (MMAS) to sound and artificially induced caries-affected dentin (CAD).

Methods:

Flat dentin surfaces of 112 bovine incisors were assigned to 16 subgroups (n = 7) according to the substrate condition (sound and CAD– pH-cycling for 14 days); adhesive systems (Scotchbond Universal, All-Bond Universal, Prime and Bond Elect, Adper Single Bond Plus and Clearfil SE Bond) and etching strategy (etch-and-rinse and self-etch). All systems were applied according to the manufacturer's instructions, and resin composite restorations were built. After 24 h of water storage, specimens were sectioned (0.8 mm²) and submitted to the microtensile test.

Statistical Analysis:

Data (MPa) were analyzed using three-way analysis of variance and Tukey's test (α = 0.05).

Results:

MMAS presented similar bond strength values, regardless etching strategy in each substrate condition. Bond strength values were lower when MMAS were applied to CAD in the etch-and-rinse strategy.

Conclusion:

The etching strategy did not influence the bond strength of MMAS to sound or CAD, considering each substrate separately. However, CAD impact negatively on bond strength of MMAS in etch-and rinse mode.

Effect of method of caries induction on aged resin-dentin bond of primary teeth

Background

To investigate the influence of chemical and microbiological methods of caries induction on bond degradation of adhesive systems to primary dentin.

Methods

Flat dentin surfaces from 36 primary molars were assigned to three groups (n = 12) according to method to induce caries-affected dentin: (1) control (sound dentin); (2) pH-cycling; and (3) microbiological caries induction model. Teeth were submitted to caries induction for 14 days for both methods, and the sound dentin was stored in distilled water during the same period. Specimens from each experimental group were then randomly reassigned to two subgroups (n = 6) according to the adhesive system tested: two-step etch-and-rinse adhesive (Adper Single Bond 2 - SB) or two-step self-etch system (Clearfil SE Bond - CSEB). Composite buildups were constructed and sectioned to obtain bonded sticks to be subjected to microtensile (μTBS) testing immediately or after 12 months of water aging. The μTBS means were analyzed by three-way repeated measures ANOVA and Tukey’s tests (α = 0.05).

Results

The μTBS values obtained to artificially-created caries-affected dentin were lower compared with sound dentin, but were not affected by method of caries induction. Water storage for 12 months reduced bond strengths, except to CSEB bonded to sound dentin.

Conclusion

Chemical and microbiological methods affect similarly the stability of resin-dentin bonds in primary teeth.