Retention of Crowns Cemented on Implant Abutments with Temporary Cements

Objective: This study examined the retentive force of crowns retained on implant abutments with different temporary cements.

Methods: Six different commercially available temporary cements [HY-Bond Temporary cement Soft (A, Shofu, polycarboxylate cement); HY-Bond Temporary cement (Hard) (B, Shofu, polycarboxylate cement); Temp Bond (C, Kerr, paste-mix type with eugenol); Temp Bond NE (D, Kerr, paste-mix type without eugenol); Freegenol temporary pack (E, GC, paste-mix type without eugenol); and Eugenol cement (F, GC, zinc oxide-eugenol cement)] were used. Cast crowns (copings) were fabricated conventionally using gold alloy for PFM (TPW, TOKURIKI HONTEN) to fit the implant abutment (Easy Abutment, Nobel Biocare, 5mm dia., 5mm high). The inner surface of each crown was sandblasted with glass beads. The crown specimens and implant abutments were cemented using each cement mixed according to the manufacturer's recommendations. Ten minutes after the start of mixing, each specimen was stored in 100% relative humidity at 37℃ up to 168 hours. The retentive force of the crown on the abutment was then determined using a universal testing machine (Instron 4302). The results were analyzed using ANOVA/Scheffe's test (a=0.05).

Results: The measured retentive force values (N, mean ± sd, n=5) for each cement were as follows: 78.0±6.4 (A); 132.3±14.3 (B); 65.5±9.6 (C); 94.2±16.9 (D); 81.4±9.9 (E) and 14.1±3.7 (F). Zinc oxide-eugenol cement F had the lowest (p<0.05) retentive force among the cements tested. The greatest (p<0.05) retentive force was obtained for polycarboxylate cement B. The trend for the retentive force for the temporary cements was similar to that found for the compressive strength of the cements, as reported in our previous study (JDR 84 Special Issue A, abst. #532, 2005).

Conclusion: The mechanical properties of the temporary cements, particularly their compressive strength, affected the retention of crowns cemented on implant abutments under the present experimental conditions.