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Open Access Publications from the University of California

Bond strength of etch-and-rinse and self-etch adhesive systems to enamel and dentin irradiated with a novel CO2 9.3 μm short-pulsed laser for dental restorative procedures

  • Author(s): Bartolome, Nicole Ong
  • Advisor(s): Rechmann, Peter
  • et al.


The bonding protocol of the dental substrate is essential for successful adhesive restorations. Dental adhesive systems can be classified into two categories: etch-and-rinse (total-etch) and self-etch systems. Highly absorbed 9.6μm CO2 short-pulsed laser prototype irradiation has successfully shown enhancement of enamel caries resistance in laboratory and prospective, randomized controlled clinical studies. Recently, a 9.3µm microsecond short-pulsed CO2-laser was introduced to the dental profession. In addition to caries preventive procedure, this laser can be used for tooth preparation and osseous surgery.


The objective of this study was to evaluate the CO2 9.3µm short-pulsed laser irradiation influence on shear bond strength of composite to enamel and dentin.


200 enamel and 210 dentin samples were irradiated with a 9.3μm carbon-dioxide laser (Solea, Convergent Dental; Needham, MA) with energies enhancing caries resistance for ablation of enamel and dentin. A 5th generation etch-and-rinse bonding agent OptiBond Solo Plus [OptiBondTE] (Kerr Corporation; Orange, CA) and Peak Universal Bond light-cured adhesive [PeakTE] (Ultradent Products) were used on both ablated enamel and dentin. A 6th generation self-etch system Scotchbond Universal [ScotchbondSE] (3M ESPE, St. Paul, MN) and Peak SE self-etching primer with Peak Universal Bond light-cured adhesive [PeakSE] were used on both ablated enamel and dentin. Clearfil APX (Kuraray, New York, NY) composite was bonded to the samples, and after 24 hours storage at 37°C, a single plane shear bond test was performed to determine enamel and dentin bond strengths.


Using the caries preventive setting on enamel resulted in increased shear bond strength values for all bonding agents except for self-etch PeakSE with a slight, statistically non-significant 16.3% decrease. The highest overall bond strength to caries preventive-treated enamel was seen with PeakTE (41.29±6.04MPa), presenting a 6.6% increase over the not laser treated control.

To ablated enamel, etch-and-rinse systems achieved higher bond strength values than the self-etch systems. PeakTE showed the highest shear bond strength with 35.22±4.40MPa (90.9% of the not laser treated control). OptiBondTE reached 93.8% of the control bond strength values. The self-etch system PeakSE presented significantly lower bond strength (41.7 to 53.9% of control value), ScotchbondSE showed a non-significant increase of the bond strength after enamel ablation.

After ablation of dentin the shear bond strength values ranged between 19.15±3.49MPa for OptiBondTE and 43.94±6.47MPa for PeakSE. The shear bond strength was significantly lower (57.2 and 75.4% of the not laser treated control values) for all bonding systems.


Etch-and-rinse systems achieve consistently high bond strengths to short-pulsed CO2 9.3μm laser-ablated enamel. After irradiation with the highest recommended energy for laser dentin removal, PeakSE reached 43.9±6.5MPa bond strength followed by 36.0±7.4MPa for PeakTE and 25.3±3.8MPa for ScotchbondSE. Following dentin ablation, all bonding agents reached higher shear bond strength values than the reported required minimum value.

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