Dislodgement Resistance of Zirconia Copings Cemented onto Zirconia and Titanium Abutments

Abstract

PURPOSE To determine the effect of the cement type and abutment material on the tensile strength required to dislodge zirconia copings. MATERIALS AND METHODS Two experimental groups of abutments were prepared: (1) titanium abutments (n = 30) and (2) zirconia abutments (n = 30). Sixty zirconia copings (custom designed) were fabricated using 3-dimensional computer-assisted design to have a 6-mm projection above the abutment to accommodate a hole, through which a wire was inserted to attach the zirconia coping to a universal testing machine. Each abutment was placed onto an implant analog embedded in acrylic resin blocks to fit onto the universal testing machine. The zirconia copings were cemented onto the abutments with a provisional luting agent, zinc phosphate (ZP) cement, and adhesive resin cement, and after 5500 thermocycles, a tensile force was applied at a crosshead speed of 0.5 mm/min. The removal force was recorded for each specimen. Two-way analysis of variance (ANOVA) and 1-way ANOVA were used for the statistical analysis (P < 0.05). RESULTS The mean forces necessary to remove the zirconia copings from titanium abutments were 6.52, 83.09, and 251.18 N for temporary cement, ZP cement, and resin cement, respectively. For zirconia abutments, the required forces were 17.82, 116.41, and 248.72 N. CONCLUSIONS The abutment material had no effect on retention, but the cement type affected the retention of the zirconia copings.

Retention of different temporary cements tested on zirconia crowns and titanium abutments in vitro

“…Therefore, the first null hypothesis must be rejected since the objective of this study was to demonstrate homogeneous retention values of the three cements tested. Other studies also showed heterogeneous results regarding the retentive strength of different cements [5,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. Therefore, some studies published guidelines for clinicians since no cement served for all demands [40,41].…”

“…Test specimens were stored for 24 h in distilled water and half of the test specimens of each group were subjected to a thermocycling process. The number of cycles was chosen based on other studies that have addressed this issue [21,23,45]. Gale and Darvell proposed that 10,000 cycles might represent approximately 1 year of in vivo conditions, with 20 to 50 cycles considered equivalent to a single day [46].…”

“…However, thermocycling can be used to mimic the clinical situation, but it has no relevance for direct comparisons to in vivo conditions [19]. Some studies have performed thermocycling in order to evaluate retention forces of the cements tested [5,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. For temporary cements, a considerable decrease in regards to the pull-off forces has been proven to be caused by the artificial ageing process [22].…”

Which Factors have an Impact on the Retention of Cemented Crowns on Implant Abutments? A Literature Review

“…The bond strength values differ significantly between the bond to implant abutments and natural teeth. In particular, zinc phosphate, zinc polycarboxylate and glass ionomer cements showed a wide range between retention values [9][10][11][12]. Nevertheless, these cements, including self-adhesive resin cements, are used for permanent cementation of single-tooth crowns on implants [13].…”

“…Previous studies have recommended that definitive cements should be used for the cementation of single-tooth restorations and provisional cements for the cementation of multi-unit restorations [9,20,21], as larger restorations may be more likely to require retrievability. Definitive resin cements are the cement of choice for definitive cementation of single-tooth restorations [9,22,23]. In general, there is a disagreement as to whether temporary or definitive cements should be used for superstructures on implants [17,18,20,24].…”