Effect of intrapulpal pressure simulation in vitro on shear bond strengths and hybrid layer formation.
OBJECTIVE
To test the hypothesis that simulation of an intrapulpal pressure during the application of dentin bonding systems influences hybrid layer formation in vitro.


METHODS
180 teeth and three different bonding agents were used for shear bond strength measurements and for confocal laser scanning microscopy studies on the dentin-composite interface. The bonding agents (30 teeth each material) were applied without (90 teeth, Group A) and with intrapulpal pressure simulation of 34 cm H20 with water (90 teeth, Group B). 45 specimens from each group were sheared in a testing machine, and 45 teeth from each group were used for CLSM studies after labeling the primer components of the bonding agents with a fluorescent dye.


RESULTS
After simulation of pulpal pressure the bond strengths decreased significantly in all groups (Syntac [without/with]: 16.0 +/- 4.5/8.0 +/- 3.7, P= 0.001; Gluma: 13.3 +/- 4.6/8.4 +/- 4.4, P= 0.008; Prime & Bond NT: 14.8 +/- 5.8/8.7 +/- 5.7, P= 0.007; n = 15 each; U-tests). There were no significant differences between the hybrid layer thickness without/with simulation of pulpal pressure (Syntac: 3.6 +/- 0.6/4.1 + 1.2, P= 0.35; Gluma: 3.5 +/- 0.6/3.7 + 0.9, P= 0.49; Prime & Bond NT: 3.5 +/- 0.9/3.8 + 0.8, P= 0.44; n = 15 each; U-tests). In the case of simulation of an intrapulpal pressure, CLSM examination revealed a distinctly shallower penetration of the adhesives into dentin compared to the samples treated without intrapulpal pressure.
Pioch
T
T
Department of Conservative Dentistry and Periodontology, Dental School, University of Heidelberg, Germany. thomas_pioch@med.uni-heidelberg.de
Staehle
H J
HJ
Schneider
H
H
Duschner
H
H
Dörfer
C E
CE
D000134:Acid Etching, Dental; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003782:Dental Pulp / Q000502:physiology*; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D005456:Fluorescent Dyes; D005976:Glutaral / Q000737:chemistry; D006801:Humans; D018613:Microscopy, Confocal; D011109:Polymethacrylic Acids / Q000737:chemistry; D011312:Pressure; D019279:Resin Cements / Q000737:chemistry; D012235:Rhodamines; D013223:Statistics as Topic; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D013499:Surface Properties
D003188:Composite Resins; D017220:Dentin-Bonding Agents; D005456:Fluorescent Dyes; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D019279:Resin Cements; D012235:Rhodamines; C078484:Syntac dentine adhesive; C044372:Gluma; C027755:rhodamine isothiocyanate; D005976:Glutaral