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The effect of environmental pressure changes during diving on the retentive strength of different luting agents for
K M Lyons1, J C Rodda, J A Hood
1Department of Restorative Dentistry, School of Dentistry, University of Otago, Dunedin, New Zealand.
Statement Of Problem:
The effect of pressure cycling on the bond strength of cement luting agents is largely unknown.
Purpose:
This study investigated the effect of pressure cycling on the retention of full cast crowns to extracted teeth.
Material And Methods:
Sixty extracted single-rooted premolar teeth had full cast crowns cemented, 20 with a zinc phosphate cement, 20 with a glass ionomer, and 20 with a resin cement. After 7 days of storage, each of the teeth in the experimental groups was pressure cycled 15 times from 0 to 3 atmospheres (304 KPa), after which the force required to dislodge the crowns was tested in an Instron testing machine.
Results:
A significant difference was found (Students t test; p > 0.01) between the force required to remove the crowns in the zinc phosphate control (142.10 +/- 36.42 N) and experimental (15.93 +/- 11.13 N) groups and the glass ionomer cemented control (186.33 +/- 24.33 N) and experimental (91.50 +/- 33.07 N) groups; no difference was found between the resin cemented control (291.15 +/- 78.48 N) and experimental (281.32 +/- 85.43 N) groups.
Conclusion:
This study showed that the retention of full cast crowns to extracted teeth is reduced after pressure cycling if the crowns are cemented with either zinc phosphate cement or glass ionomer cement. Dentists should consider using a resin cement when cementing crowns and fixed partial dentures for patients, such as divers, who are likely to be exposed to pressure cycling.