Comparison of luting cements for minimally retentive crown preparations.
OBJECTIVE
The purpose of this study was to compare the retentive strengths of resin, glass-ionomer, and zinc phosphate cements under adverse conditions.


METHODS
Thirty extracted teeth were mounted and prepared in their long axis. The axial wall height was 3 mm and the convergence angle was 28 degrees. These conditions increased the role of the cement and decreased the role of the preparation in providing retention of the casting. The axial surface area was determined. Copings were fabricated with a ring aligned in the long axis to facilitate removal of the crown. They were cemented with a resin cement, a glass-ionomer cement, or a zinc phosphate cement. A block randomization scheme was used to assign cements so that the mean surface areas of the teeth were equivalent in all groups. The copings were loaded in tension, and the amount of force required to remove the coping was recorded. The stress required to remove the coping was calculated.


RESULTS
The mean stress required to remove the copings was 9.4, 5.0, and 3.1 MPa for the resin, glass-ionomer, and zinc phosphate cements, respectively.


CONCLUSIONS
The resin cement group was significantly stronger than both the glass-ionomer cement and the zinc phosphate cement groups. The glass-ionomer cement was significantly stronger than the zinc phosphate cement.
Browning
William D
WD
Department of Oral Rehabilitation, Medical College of Georgia, School of Dentistry, 1120 15th Street, Augusta, Georgia 30912-1260, USA. wbrownin@mail.mcg.edu
Nelson
Stephen K
SK
Cibirka
Roman
R
Myers
Michael L
ML
D000704:Analysis of Variance; D002484:Cementation; D016009:Chi-Square Distribution; D003442:Crowns; D005899:Glass Ionomer Cements; D006801:Humans; D008277:Magnesium Oxide; D008422:Materials Testing; D011076:Polycarboxylate Cement; D011897:Random Allocation; D019279:Resin Cements; D013718:Tensile Strength; D015034:Zinc Oxide; D015036:Zinc Phosphate Cement
C061504:Flecks; D005899:Glass Ionomer Cements; D011076:Polycarboxylate Cement; D019279:Resin Cements; C458820:permalute; D008277:Magnesium Oxide; D015036:Zinc Phosphate Cement; C040235:Ketac-cem; D015034:Zinc Oxide