An Evaluation of the Effectiveness of Various Luting Cements on the Retention of Implant-Supported Metal Crowns

Cytotoxicity of dental cement on soft tissue associated with dental implants at different time intervals

Background

To investigate and compare the effect of four commercially used dental cement at 24 hours, 48 hours,72 hours (h) and 6 days on the cellular response of human gingival fibroblast (HGF).

Methods

3 cement pellet samples were made for each 4-test cement (n=12). The cement used for this study were zinc phosphate (ZP), zinc oxide non-eugenol (ZOE), RelyX U200 (RU200), and glass ionomer cement (GIC). The cytotoxicity of peri-implant tissues was investigated using one commercial cell line. All processing was done following International Organization for Standardization (ISO) methods 10993-5 and 10993-12 (MTT assay Test). Cell cultures without dental cement were considered as control. Standard laboratory procedures were followed to permit cell growth and confluence over 48 hrs after sub-cultivation. Before being subjected to analysis, the cells were kept in direct contact with the cement samples for the suggested time period. To validate the results the specimens were tested three times each. Cell death and inhibition of cell growth were measured quantitatively. Results were analyzed using 1-way ANOVA (a=0.05) followed by Tukey B post hoc test.

Results

The study showed the dental cement test material was cytotoxic. ZOE, ZP, GIC, and RU200 were cytotoxic in decreasing order, respectively, significantly reducing cell viability after exposure to HGF (p <0.001).

Conclusions

Within the limitations of this in-vitro cellular study, results indicated that HGF were vulnerable to the test the dental cement. The highest cytotoxicity was observed in ZOE, followed by ZP, GIC, and RU200.

Comparison of marginal leakage and retentive strength of implant-supported milled zirconia and cobalt-chromium copings cemented with different temporary cements

Background

Few studies assessed the effect of coping material (particularly milled metal copings) on the retentive strength of cements and reported contradictory results. Thus, this study aims to assess the marginal leakage and retentive strength of implant-supported milled zirconia and cobalt-chromium (Co-Cr) copings cemented with different temporary cements.

Materials and Methods

In this in vitro study, Zirconia and Co-Cr copings were fabricated on 100 straight titanium abutments. Each group of copings was divided into five subgroups (n = 10) for the use of different cements: permanent zinc-phosphate (ZP) cement, temporary zinc oxide eugenol cement (temp bond [TB]), calcium hydroxide-based temporary cement (Dycal [DC]), polymer-based eugenol-free acrylic-urethane temporary cement (Dentotemp [DT]), and methacrylate-based temporary cement (Implantlink [IL]). The retentive strength and marginal leakage of restorations were assessed. Data were analyzed by one-way ANOVA, Tukey, and Fisher's exact tests (α = 0.05).

Results

In the Co-Cr group, the retentive strength values (in Newtons) were as follows: ZP (411.40 ± 5.19) >DC (248.80 ± 5.01) >IL (200.10 ± 5.06) >DT (157.90 ± 5.19) >TB (98.50 ± 6.88). This order was as follows in the zirconia group: ZP (388.70 ± 5.35) >DC (226.60 ± 5.08) >IL (179.00 ± 3.71) >DT (136.00 ± 4.88) >TB (78.60 ± 3.50). All pairwise comparisons were statistically significant (P < 0.001). The difference in marginal leakage was not significant among the groups (P = 0.480).

Conclusion

The type of coping material and cement type significantly affected retentive strength, but not marginal leakage, of implant restorations. Milled Co-Cr copings showed higher retentive strength than zirconia copings, and ZP cement followed by DC yielded the highest retention.