2000 Judson C. Hickey Scientific Writing Award. Effect of impression materials on hybridized dentin.
BACKGROUND
Tooth sensitivity after crown preparation is not an uncommon complication. For dentin bonding agents to be effective in preventing postoperative sensitivity, they must remain intact throughout the fixed prosthodontic procedures.


OBJECTIVE
This study evaluated, by analyzing the change in dentin permeability, whether a dentin bonding agent was removed from the surface of prepared teeth in the process of making an impression.


METHODS
Eighty extracted human molars were cut horizontally apical to the cemento-enamel junction and horizontally through the middle of the clinical crown. The specimens were prepared to measure dentin permeability (fluid flow rate, Lp). The specimens (n = 40) were randomly assigned to either the primer-only group (PO) or the primer + adhesive group (PA). Five different impression materials were tested: vinyl polysiloxane, polyether, polysulfide, irreversible hydrocolloid, and reversible hydrocolloid. Dentinal permeability was measured after smear layer removal (control, etched Lp = ELp), after coating the dentin with either PO or PA (coated Lp = CLp), and again after making an impression (impression Lp = ILp). A 1-way ANOVA of differences, followed by a Student-Newman-Keuls test (alpha=.05), was performed to compare the ELp, CLp, and ILp values.


RESULTS
A statistically significant difference was found between the CLp and ELp for all 5 impression materials in both groups (PO and PA). No difference was found between the CLp and ILp values for any of the impression materials. No significant differences were found between any of the 5 impression materials or either of the dentin surface treatments (PO or PA) when measuring the CLp and ILp.


CONCLUSIONS
The dentin bonding agent had a significant effect in decreasing the Lp of the treated specimens. None of the impression materials significantly affected the measured CLp. There was no significant difference between the PO or PA (CLp) values.
Nahon
M
M
School of Dentistry, The Medical College of Georgia, Augusta, Ga 30912-1260, USA. mnahon@mail.mcg.edu
Dentkos
T R
TR
Nelson
S K
SK
Gardner
F M
FM
Rillman
E A
EA
D000134:Acid Etching, Dental; D000269:Adhesives / Q000737:chemistry; D000464:Alginates / Q000737:chemistry / Q000494:pharmacology; D000704:Analysis of Variance; D003102:Colloids / Q000737:chemistry / Q000494:pharmacology; D001840:Dental Bonding; D003760:Dental Impression Materials / Q000737:chemistry / Q000494:pharmacology*; D003804:Dentin / Q000187:drug effects*; D003806:Dentin Permeability / Q000187:drug effects*; D017220:Dentin-Bonding Agents / Q000737:chemistry* / Q000494:pharmacology; D019234:Dentinal Fluid / Q000187:drug effects / Q000378:metabolism; D004987:Ethers / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D008689:Methacrylates / Q000737:chemistry / Q000494:pharmacology; D011145:Polyvinyls / Q000737:chemistry / Q000494:pharmacology; D019279:Resin Cements / Q000737:chemistry / Q000494:pharmacology; D012117:Resins, Synthetic / Q000737:chemistry / Q000494:pharmacology; D012833:Siloxanes / Q000737:chemistry / Q000494:pharmacology; D016369:Smear Layer; D013223:Statistics as Topic; D013440:Sulfides / Q000737:chemistry / Q000494:pharmacology
D000269:Adhesives; D000464:Alginates; D003102:Colloids; D003760:Dental Impression Materials; D017220:Dentin-Bonding Agents; D004987:Ethers; C022821:Impregum; D008689:Methacrylates; D011145:Polyvinyls; D019279:Resin Cements; D012117:Resins, Synthetic; D012833:Siloxanes; D013440:Sulfides; C067789:Visilux 2; C034183:vinyl polysiloxane; C100742:All-Bond 2; C032915:polysulfide