PURPOSE: The purpose of this study was to assess and compare the retentive nature of common dental cements that have been adapted for use in the implant abutment cement-retained crown (CRC) technique with those specifically formulated for this purpose. MATERIALS AND METHODS: Ten regular diameter implant analogs were embedded in stainless steel disks. Unmodified CRC abutments were attached and torqued to 30 Ncm. Test crowns were waxed and cast with base metal alloy. Castings were fitted, cleaned with aluminum oxide, and steam cleaned prior to application of the cement. The cements used were: (1) Temp Bond, (2) UltraTemp, regular, (3) UltraTemp firm, (4) ImProv with petroleum jelly coating of crown, (5) ImProv without petroleum jelly, (6) Premier Implant with KY Jelly coating of abutment, (7) Premier Implant without KY jelly, (8) TR-2, (9) Fleck's, (10) Ketac Cem Aplicap, and (11) Fuji Plus Capsule. After cementation, assemblies were stored for 24 hours. Each sample was subjected to a pull-out test using an Instron universal testing machine at a crosshead speed of 5.0 mm/min. Loads required to remove the crowns were recorded, and mean values for each group determined. A one-way ANOVA and a post hoc least square difference (LSD) test were done for pairwise comparison at a confidence interval of 95%. RESULTS: The mean values (+/-SD) of loads at failure (n = 10) for various cements were as follows (N): Ultratemp, regular 358.6 (+/-38.2) (Group A), ImProv without petroleum jelly 172.4 (+/-59.6) (Group B), Fleck's 171.8 (+/-62.2) (Group B), Ketac Cem 167.8 (+/-69.1) (Group B), UltraTemp firm 158.8 (+/-62.7) (Group BC), Fuji Plus 147.5 (+/-69.7) (Group BC), Premier without KY jelly 131.6 (+/-31.8) (Group BC), ImProv using petroleum jelly 130.8 (+/-42.5) (Group BC), Temp Bond 117.8 (+/-48.3) (Group C), TR-2 41.2 (+/-16.6) (Group D), and Premier with KY jelly 31.6 (+/-24.8) (Group D). Groups with the same letter were not significantly different. CONCLUSIONS: Within the limitations of this in vitro study, it is not suggested that any one cement is better than another at retaining cement-retained crowns (CRCs) to implant abutments or that a threshold value must be accomplished to ensure retention. The ranking of cements presented is meant to be a discretionary guide for the clinician in deciding the amount of desired retention between castings and implant abutments.
PURPOSE: The purpose of this study was to assess and compare the retentive nature of common dental cements that have been adapted for use in the implant abutment cement-retained crown (CRC) technique with those specifically formulated for this purpose. MATERIALS AND METHODS: Ten regular diameter implant analogs were embedded in stainless steel disks. Unmodified CRC abutments were attached and torqued to 30 Ncm. Test crowns were waxed and cast with base metal alloy. Castings were fitted, cleaned with aluminum oxide, and steam cleaned prior to application of the cement. The cements used were: (1) Temp Bond, (2) UltraTemp, regular, (3) UltraTemp firm, (4) ImProv with petroleum jelly coating of crown, (5) ImProv without petroleum jelly, (6) Premier Implant with KY Jelly coating of abutment, (7) Premier Implant without KY jelly, (8) TR-2, (9) Fleck's, (10) Ketac Cem Aplicap, and (11) Fuji Plus Capsule. After cementation, assemblies were stored for 24 hours. Each sample was subjected to a pull-out test using an Instron universal testing machine at a crosshead speed of 5.0 mm/min. Loads required to remove the crowns were recorded, and mean values for each group determined. A one-way ANOVA and a post hoc least square difference (LSD) test were done for pairwise comparison at a confidence interval of 95%. RESULTS: The mean values (+/-SD) of loads at failure (n = 10) for various cements were as follows (N): Ultratemp, regular 358.6 (+/-38.2) (Group A), ImProv without petroleum jelly 172.4 (+/-59.6) (Group B), Fleck's 171.8 (+/-62.2) (Group B), Ketac Cem 167.8 (+/-69.1) (Group B), UltraTemp firm 158.8 (+/-62.7) (Group BC), Fuji Plus 147.5 (+/-69.7) (Group BC), Premier without KY jelly 131.6 (+/-31.8) (Group BC), ImProv using petroleum jelly 130.8 (+/-42.5) (Group BC), Temp Bond 117.8 (+/-48.3) (Group C), TR-2 41.2 (+/-16.6) (Group D), and Premier with KY jelly 31.6 (+/-24.8) (Group D). Groups with the same letter were not significantly different. CONCLUSIONS: Within the limitations of this in vitro study, it is not suggested that any one cement is better than another at retaining cement-retained crowns (CRCs) to implant abutments or that a threshold value must be accomplished to ensure retention. The ranking of cements presented is meant to be a discretionary guide for the clinician in deciding the amount of desired retention between castings and implant abutments.