Mechanical Assistance to Dentin Bonding

Objectives:

Questions have been voiced concerning the long term stability of dentin bonding. One suggestion is to place “pot-holes” into dentin to create mechanical retention. The purpose of this study was to determine if the incorporation of pot-holes increases retention of composite bonded to dentin.

Methods:

36 human molars were ground exposing dentin then sagittally sectioned to create 72 dentin specimens. Each specimen was imbedded into 1 inch diameter methylmethacrylate cylinders, ground flat, then aged in water at 37o C for 2 months prior to testing. Upon removal from water test specimens were polished with 320 grit silicon-carbide paper and randomly separated into 6 groups. Using a ˝ round (.61mm) carbide bur “pot-holes” were prepared into one section of each dentin specimen. Specific adhesives were applied to each group as per manufacturer's instructions.

Adhesives selected for testing

Adper Prompt™

Prelude™

Clearfil SE™

Simplicitytm

G-Bond™

Surpass™

Two 2.38mm diameter X 2 mm high composite posts, Z-100™ (3 M ESPE), were placed on each specimen and polymerized using a 750mW/cm2 FlashLite 1401™ LED (Discus Dental) for 40 seconds. One post incorporated the pot-hole and one was placed on flat dentin. Specimens were stored in water at 37o C for 180 days. Using a Universal Testing Machine notched blade apparatus with a crosshead speed of 1mm per minute specimens were stressed to fracture. Results were analyzed by t- test.

Results:

Averaged (std dev) were as follows:

Pot-holes Flat

Adper Prompt 17.4Mpa(3.2) Adper Prompt 21.6MPa(5.8)

Clearfil SE 33.6MPa(8.2) Clearfil SE 42.7MPa(12.8)

G-Bond 31.5MPa(6.3) G-Bond 36.8MPa(4.4)

Prelude 23.7MPa(7.3) Prelude 31.7MPa(6.1)

Simplicity 34.2MPa(3.4) Simplicity 45.6MPa(6.9)

Surpass 36.1MPa(2.2) Surpass 54.2MPa(8.9)

All Adhesives 27.25MPa All Adhesives 33.77MPa

Conclusion:

Those samples incorporating “potholes” showed a marked decrease in shear bond strength compared to those placed on flat dentin surfaces.