A comparison of retentive strength of implant cement depending on various methods of removing provisional cement from implant abutment

PURPOSE: This study evaluated the effectiveness of various methods for removing provisional cement from implant abutments, and what effect these methods have on the retention of prosthesis during the definitive cementation. MATERIALS AND METHODS: Forty implant fixture analogues and abutments were embedded in resin blocks. Forty cast crowns were fabricated and divided into 4 groups each containing 10 implants. Group A was cemented directly with the definitive cement (Cem-Implant). The remainder were cemented with provisional cement (Temp-Bond NE), and classified according to the method for cleaning the abutments. Group B used a plastic curette and wet gauze, Group C used a rubber cup and pumice, and Group D used an airborne particle abrasion technique. The abutments were observed using a stereomicroscope after removing the provisional cement. The tensile bond strength was measured after the definitive cementation. Statistical analysis was performed using one-way analysis of variance test (alpha=.05). RESULTS: Group B clearly showed provisional cement remaining, whereas the other groups showed almost no cement. Groups A and B showed a relatively smooth surface. More roughness was observed in Group C, and apparent roughness was noted in Group D. The tensile bond strength tests revealed Group D to have significantly the highest tensile bond strength followed in order by Groups C, A and B. CONCLUSION: A plastic curette and wet gauze alone cannot effectively remove the residual provisional cement on the abutment. The definitive retention increased when the abutments were treated with rubber cup/pumice or airborne particle abraded to remove the provisional cement.

An evaluation of retention and marginal seating of Ni-Cr alloy cast restorations using three different luting cements: An in vitro study.

Context: Clinical and laboratory studies regarding performance of recently introduced luting cements: Adhesive resin cement and resin-modified glass ionomer cement (GIC), are limited. Aims: To compare the retention and marginal seating of Ni-Cr alloy restorations using newer luting cements: Resin-modified GIC and adhesive resin cement with those of the oldest cement, zinc phosphate. Materials and Methods: Thirty maxillary premolars of similar sizes were prepared to receive cast metal copings. Copings were placed on the prepared teeth and the marginal opening was examined using a Nikon Measuroscope. The specimens were randomly assigned to three groups. Group I castings were luted with zinc phosphate, Group II castings luted with resin-modified GIC, and Group III castings luted with adhesive resin cement. After cementation marginal seating was measured. Tensile loads required to dislodge the crowns were obtained using MTS machine. Statistical Analysis Used: Tukey's test, Analysis of Variance (ANOVA). Results: For zinc phosphate cement, mean marginal seating was 31 microns. Mean retentive strength was 287 Newtons. For resin-modified GIC, mean marginal seating was 29.6 microns. Mean retentive strength was 610 Newtons. For adhesive resin cement, mean marginal seating was 49 microns. Mean retentive strength was 613 Newtons. Conclusions: Marginal seating of adhesive resin cement was significantly greater than that of zinc phosphate and resin-modified GIC. Retentive strength of adhesive resin cement and resin-modified GIC was significantly greater than that of zinc phosphate There was no significant difference of retentive strength between adhesive resin cement and resin-modified GIC.

Evaluation of the effect of different surface treatments on the retention of posts: A laboratory study.

Background and Objectives : There are numerous post and core systems variety of materials. Several methods are used to increase the retentive strength.The present study was conducted with the purpose of analysis of the effect of surface treatment with ethyl alcohol, resin primer and air-borne alumina particle abrasion on retention of glass fiber posts, carbon fiber posts and cast metal posts Materials and Methods : Surface treatment of glass fiber posts, carbon fiber posts and cast metal posts was done with ethyl alcohol, resin primer and air-borne alumina particle abrasion and cemented with dual cure resin cement into the post spaces prepared in the teeth. For the Retentive force test, a screw driven universal testing machine was used to apply tensile load to the post. The force required to dislodge each post from prepared post space was recorded. Statistical Analysis : Comparison of the mean retentive strength was done using two-way Analysis of Variance (ANOVA) followed by Bonferroni method for multiple comparisons. Results : Significant difference in the retentive strength between air borne alumina particle abrasion and resin primer treated posts was (P < 0.001) noticed. Further, there was no significant difference between ethyl alcohol and resin primer treated posts Conclusion : Air-borne alumina particle abrasion increased the retentive strength of all the type of posts used in this study. Treating the surface of the posts with resin-primer and ethyl alcohol produced no statistically significant difference in the retentive strength.

Effects of various cements and thermocycling on retentive strengths of cemented implant-supported prostheses / 대한치과보철학회지

STATEMENT OF PROBLEM: In cemented implant-supported porstheses, it is still controversy what kind of cement to use. However, the effect of thermocycling on retentive strength of cemented implantsupported prostheses has not been well investigated. PURPOSE: This study was tested to evaluate the effects of various cements and thermocycling on retentive strengths of cemented implant-supported prostheses. MATERIAL AND METHODS: Prefabricated implant abutments, height 5mm, diameter 6mm, 3- degree taper per side, with light chamfer margins were used. Ten specimens of two-unit fixed partial denture were fabricated. The luting agents used for this study were three provisional luting agents which were Temp bond, Temp bond NE, IRM and four permanent luting agents which were Panavia F, Fuji-cem, Hy-bond Zinc cement, Hy-bond Polycarboxylate cement. 24 hours after cementation, the retentive strengths were measured by the universal testing machine with a cross-head speed of 0.5mm/min. Then cementation procedures were repeated and specimens were thermocycled 1000 times at temperature of 5degrees C and 55degrees C. After thermocycling, the retentive strengths were measured. RESULTS: Before thermocycling, the retentive strengths were decreased with the sequence of Panavia F, Fuji-cem, Hy-bond Zinc cement, Hy-bond Polycarboxylate cement, IRM, Temp bond NE and Temp bond, and there were significant differences among each groups(p0.05). The retentive strengths before and after thermocycling showed significant differences in Hy-bond Zinc cement. IRM, Temp bond NE and Temp bond(p<0.05). CONCLUSION: Within the limitation of this study, thermocycling do not affect the retentive strengths of permanent luting agents but the retentive streng ths of temporary cements were reduced significantly after thermocyling.

THE EFFECT OF CYCLIC LOADING ON THE RETENTIVE STRENGTH OF FULL VENEER CROWNS / 대한치과보철학회지

Dislodgement of a crown or extension bridge and the loosening of a retainer of a bridge is a serious clinical problem in fixed restoration. Generally these problems are considered to be associated with deformation of the restoration. During biting, the restoration is subjected to complex forces and deforms considerably within the limit of its elasticity. Deformation of the restoration under the occlusal force induces excessive stress in the cement film, which then leads to the cement fracture. Such a fracture may eventually cause loss of the restoration. Because most of the past retention tests for full veneer crown were done without fatigue loading, they were not exactly simulating intraoral environment. And the purpose of this study was to evaluate the effect of cyclic cantilever loading on the retentive strength of full veneer crowns depending on different type of cements and taper of prepared abutment. Steel dies with 8degrees or 16degrees convergence angle were fabricated through milling and crowns with the same method. These dies and crowns were divided into 8 groups. Group 1: 16degrees taper die, cementation with zinc phosphate cement, without loading Group 2: 16'taper die, cementation with zinc phosphate cement, with loading Group 3: 8degrees taper die, cementation with zinc phosphate cement, without loading Group 4: 8degrees taper die, cementation with zinc phosphate cement, with loading Group 5: 16degrees taper die, cementation with Panavia 21, without loading Group 6: 16degrees taper die, cementation with Panavia 21, with loading Group 7: 8degrees taper die, cementation with Panavia 21, without loading Group 8: 8degrees taper die, cementation with Panavia 21, with loading After checking the fit of die and crown, the luting surface of dies and inner surface of crowns were air-abraded for 10 seconds. The crowns were cemented to the dies, with cements mixed ac cording to the manufacturer' s recommendations. A static load of 5 kg was then applied for 10 min utes with static loading device. Twenty-four hours later, group 1,3,5,7 were only thermocycled, group 2,4,6,8 were subjected to cyclic loading after thermocycling. Retentive tests were performed on the Instron machine. From, the finding of this study, the following conclusions were obtained. 1. Panavia 21 showed significantly higher retentive strength than zinc phosphate cement for all groups(p0.05). 3. Cyclic loading significantly decreased the retentive strength for all groups (p<0.05) . 4. For zinc phosphate cement, there was 35% reduction of the retentive strength after loading in the 16degrees taper die, 25% in the 8degrees taper die, and for Panavia 21, 21% in the 16degrees taper die, 18% in the 8degrees taper die.