Effect of dentin desensitizers and cementing agents on retention of full crowns using standardized crown preparations.
BACKGROUND
Past research has not controlled preparation surface area when examining the influence of dentin desensitizers on the retentive strength of cemented cast crowns, leading to inconsistent results.


OBJECTIVE
This research controlled crown preparation surface area and evaluated the effect of various dentin desensitizers and conventional cementing agents on the in vitro retentive strength of cast crowns.


METHODS
Freshly extracted human molars were prepared for a standardized crown preparation (26 degrees total convergence, 4 mm axial height) with a custom-made pantograph. Dentin desensitizers included none (control), a polymerizable material (All-Bond 2), and a nonpolymerizable desensitizer (Gluma Desensitizer). Cementing agents included zinc phosphate (Fleck's), glass ionomer (Ketac-Cem), resin-modified glass ionomer (Fuji II), and resin cement (Panavia 21). Twelve teeth were prepared for each test condition (144 teeth total). Individual castings were made from a base metal alloy (Rexillium III). Crowns were removed after storage at 26 degrees C for 48 hours at 100% relative humidity using a universal testing machine at a crosshead speed of 1.27 mm/min. The proportion of cement retained on the tooth and casting after debonding was quantified according to treatment. Statistical treatment included 1- and 2-way ANOVAs, followed by the Tukey-Kramer post hoc test at a preset alpha of 0.05.Results. Resin cement exhibited the highest retentive strength and all dentin treatments resulted in significantly different retentive values (All-Bond 2 (5.68 +/- 0.70 MPa) > control (4.67 +/- 0.48 MPa) > Gluma (4.12 +/- 0.37 MPa)). Retention of resin-modified glass ionomer was between the resin cement and glass ionomer groups: All-Bond 2 (3.46 +/- 0.26 MPa) > Gluma (2.81 +/- 0.15 MPa) = control (2.96 +/- 0.18 MPa). Conventional glass ionomer values were between those of Fuji Plus and zinc phosphate groups: All Bond 2 (2.23 +/- 0. 20 MPa) = control (2.36 +/- 0.20 MPa) > Gluma (1.98 +/- 0.23 MPa). Zinc phosphate had the lowest retention values: control (1.68 +/- 0. 08 MPa) > Gluma (0.81 +/- 0.11 MPa) > All-Bond 2 (0.67 +/- 0.14 MPa). The majority of cement was retained on the debonded tooth surface versus the casting, with the exception of zinc phosphate when used with dentin pretreatments.


CONCLUSIONS
Controlled crown surface areas reduced the variation in strength values permitting high discrimination among retention values of desensitizer/cement combinations. In all but 1 combination, Gluma desensitizer significantly decreased crown retention. With resin cement and resin-modified glass ionomer, use of All-Bond 2 desensitizer significantly increased crown retention values.
Yim
N H
NH
School of Dentistry, The Medical College of Georgia, Augusta, GA 30912-1260, USA.
Rueggeberg
F A
FA
Caughman
W F
WF
Gardner
F M
FM
Pashley
D H
DH
D000704:Analysis of Variance; D002858:Chromium Alloys / Q000737:chemistry; D003442:Crowns; D003722:Dental Alloys; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry*; D017268:Dental Prosthesis Retention; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003807:Dentin Sensitivity / Q000188:drug therapy*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry; D005976:Glutaral / Q000737:chemistry; D006801:Humans; D006813:Humidity; D008277:Magnesium Oxide / Q000737:chemistry; D008689:Methacrylates / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry; D011076:Polycarboxylate Cement / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D015034:Zinc Oxide / Q000737:chemistry; D015036:Zinc Phosphate Cement / Q000737:chemistry
D002858:Chromium Alloys; D003722:Dental Alloys; D003738:Dental Cements; D017220:Dentin-Bonding Agents; D005899:Glass Ionomer Cements; D008689:Methacrylates; C093719:Panavia TPN-S; D010710:Phosphates; D011076:Polycarboxylate Cement; D019279:Resin Cements; C111486:gluma desensitizer; C084541:Fuji glass-ionomer lining cement; C100742:All-Bond 2; D008277:Magnesium Oxide; C036884:Rexillium III; D015036:Zinc Phosphate Cement; C040235:Ketac-cem; D015034:Zinc Oxide; D005976:Glutaral