Mean Retentive Strength Research Articles

The effect of ascorbic acid, QMix and other conditioning solutions on the bond strength of adhesively luted glass fiber-reinforced composite posts to root dentin, a laboratory study

PurposeThis study was designed to investigate the effect of post space conditioning with different solutions on the bond strength of glass FRC posts and evaluate the mode of resin failure. MethodsSixty extracted human single rooted teeth were root filled using a resin sealer and suitable gutta-percha cones. Post spaces were prepared, and the teeth randomly allocated into 5 groups according to their irrigation regimens which included the following solutions: 17 % EDTA, 2 % CHX, 3 % NaOCl, 10 % ascorbic acid and QMix solutions. Post spaces were irrigated with 5 ml of the solution for 15 s and subsequently washed with distilled water and dried with paper points. Glass FRC posts were cemented into their spaces using a self-adhesive resin cement. The specimens were mounted in plexiglass molds using autopolymerizing acrylic resin. A universal testing machine was used to measure post retention at a crosshead speed of 2 mm/min. The results were analyzed by one-way ANOVA followed by Tukey HSD test (α = 0.05). Dislodged posts and post spaces were examined microscopically to evaluate retention failure. ResultsThe Ascorbic acid group exhibited the highest mean retentive strength value at 229 N, followed by QMix at 198 N, NaOCl at 186 N, CHX at 170 N, and EDTA at 124 N. The mean value of the ascorbic acid group was significantly higher than EDTA group, p = 0.012. The failure category was primarily mixed. ConclusionsRinsing post spaces with ascorbic acid exhibited significantly superior bond strength. The failure mode was mixed. Clinical significanceIrrigating post spaces with ascorbic acid solution before luting FRC posts significantly improves their bond strength compared to irrigation with EDTA solution. Irrigation with QMix solution produced the second highest retentive strength but showed no statistical significance when compared to using ascorbic acid, NaOCl, CHX, or EDTA solutions.

Retentive strength and marginal discrepancies of a ceramic-reinforced calcium phosphate luting agent: An in vitro pilot study

Statement of problemInformation on the properties of a relatively new luting agent with a unique formulation (ceramic-reinforced calcium phosphate) is limited. PurposeThe purpose of this in vitro study was to compare the retentive strengths and marginal discrepancies of a ceramic-reinforced calcium phosphate luting agent (CM) with a self-adhesive resin luting agent (RX) and to determine and compare the mode of failure of dislodged cemented copings. Material and methodsForty extracted human molar teeth were prepared to receive zirconia copings. After cementation, the specimens were divided into 4 subgroups (n=10): CM A (axial loading), CM OA (off-axis loading), RX A (axial loading), and RX OA (off-axis loading). For each subgroup, 9 of the specimens received experimental treatment (thermocycling and dynamic loading), and the tenth received no experimental treatment. Eight copings were pulled off in a universal testing machine (MTS Insight; MTS). The ninth specimen was treated experimentally but was not pull tested. The marginal discrepancy and the dentin interface of the specimens that were not pull tested were analyzed with scanning electron microscopy and energy dispersion spectroscopy. The mode of failure of the dislodged copings was also subjectively evaluated. ResultsThe mean retentive strengths were 5.92 MPa for CM A, 5.81 MPa for CM OA, 5.75 MPa for RX A, and 5.69 MPa for RX OA. The marginal discrepancy recorded for both CM and RX ranged from 30 to 45 μm, (mean, 36 ±4.6 μm). Energy dispersion spectroscopy analysis showed the presence of calcium, phosphorus, silicon, and aluminum for the CM marginal discrepancy and the presence of aluminum in the dentinal tubules adjacent to the CM. Calcium and phosphorus were detected in lesser amounts adjacent to the RX marginal discrepancy. The mode of failure for CM was primarily adhesive to the tooth preparation, and, for RX, the failure mode was predominantly adhesive to the coping. ConclusionsCM had statistically significantly higher mean retentive strength compared with RX. Subgroups loaded axially had statistically significantly higher retentive strengths compared with those loaded off axis.

Effect of luting space and cements on retention of implant supported crowns fabricated by laser sintering

Background: The aim of this study was to evaluate the retention strength of five different cements used for implant supported crowns with two cement gap values. Methods: Standard titanium abutments were scanned by means of a 3D digital laser scanner. 100 standard metal copings were designed by a CAD/CAM system with two cement gap values (20 and 40μm). The copings were cemented to the abutments using the following five cements (n=10). Poly F (PF), GC FujiCEM (GCF), Rely X (RX), MIS Crown Set(MCS) and Multilink N (MN). The specimens were placed in 100% humudity for 24 hours then specimens were thermal cycled 1000 times. After thermal cycling specimens were subjected to a pull-out test using a universal testing machine at a 0.5 mm/min crosshead speed. The test results were analyzed with two-way ANOVA, followed by multiple comparisons using Tamhane tests (α=0.05). Results: Statistical analysis revealed that significant differences were observed among cement groups (p<0.05). PF and MN had the highest and the least mean retentive strength, respectively. No significant difference was found between RX and MCS. Increasing the cement gap from 20 to 40 μm improved retention significantly for each cement group (p<0.05). Conclusion: The ranking of cements presented in the study is meant to be an arbitrary guide for the clinician in deciding the appropriate cement selection for CAD/CAM fabricated metal copings onto implant abutments.

A comparative study to evaluate retention of full metal crowns cemented with various luting agents with and without application of dentine conditioners: An in vitro study

Aim: The aim of the study is to assess the effect of dentin conditioners and luting cements on the retention of full metal crowns. Materials and Methods: Sixty recently extracted caries free molar teeth were prepared using airotor hand piece mounted to a surveyor with a custom made jig, to obtain a standardized 26° total convergence and 4 mm of axial height. Individual crowns were fabricated using base metal alloy. Thus prepared specimens were divided into six groups: 1) Two groups with no dentin conditioning (Control groups A and B), 2) Two groups, dentin conditioned with 10% polyacrylic acid conditioner (First test groups C and D), and 3) Two groups, dentin conditioned with 17% Ethylenediaminetetraacetic acid (EDTA) (Second test groups E and F). Groups A, C, and E were cemented with conventional glass ionomer whereas Groups B, D, and F were cemented with resin-modified glass ionomer. De-cementation was done using universal testing machine at a cross head speed of 1 mm/min after 48 hours of cementation. The obtained results were analysed using One-way analysis of variance (ANOVA) and Post hoc test. Results: The mean retentive (tensile) strength of Group A specimens was 2.26 ± 0.15 MPa, Group B specimens was 2.71 ± 0.15 MPa, Group C specimens was 12.26 ± 0.67 MPa, Group D specimens was 14.28 ± 1.47 MPa. Similarly, Group E specimens was 5.23 ± 0.62 MPa, and Group F specimens was 7.36 ± 0.51 MPa. Conclusion: Within the limitations of the study, retentive (tensile) strength required to dislodge the metal crowns was higher with the combination of resin-modified glass ionomer luting cement and 10% polyacrylic acid dentin conditioner.

The Effect of Compressive Cyclic Loading on the Retention of Cast Single Crowns Cemented to Implant Abutments

The aim of this study was to evaluate and compare the retention strength of three cements commonly used in implant-supported prostheses before and after compressive cyclic loading. The working model consisted of five solid abutments, 7 mm in height and with a 6-degree taper, screw retained to five implant analogs secured in a rectangular block of self-curing acrylic. On the abutments, 30 metal Cr-Ni alloy copings were cemented using three luting agents: glass ionomer, resin urethane-based, and compomer cement (n = 10). Two tensile tests were conducted with a universal testing machine, before and after 100,000 cycles of 100 N and 0.72 Hz compressive cyclic loading in a humid environment. Before applying the compressive load, the retention strength of the resin urethane-based cement was slightly higher than that of the compomer cement and 75% greater than the glass-ionomer cement. After compressive loading, the resin urethane-based cement showed the highest percentage of loss of retention (64.45%, compared with 50% for glass-ionomer and compomer cement). However, the glass-ionomer cement showed the lowest mean retentive strength with 50.35 N as opposed to 75.12 N for the compomer cement and 71.25 N for the resin urethane-based. Compressive cyclic loading significantly influences the retention strength of the luting agents tested. All three cements may favor the retrievability of the crowns.

An In Vitro Study to Evaluate Retentive Property of Resinous Dental Adhesives and other Dental Luting Cements

Background: Retention of crowns depends on various factors such as the retentive properties of the luting cements and the type of cast metal. Limited information is available regarding the retentive strengths of crowns, cemented with resin cements. Objective: The purpose of the study was to evaluate the retentive property of resinous dental adhesives with three other luting cements. Material and methods: Twenty freshly extracted human sound first mandibular molar was used for the study. The root of each tooth was embedded into a cylindrical shape block of self cured resin. Each of the tooth samples was prepared to receive a full metal crown. Total samples were divided into four groups, each containing five samples, for cementation of the metal crown in order to compare retentive properties of resinous adhesive and other luting agents; group A- resinous adhesive Panavia, group B - Zinc Phosphate cement, Group C- Glass ionomer cement, and group D- polycarboxylate cement. After 10min of cementation, the retention test was performed in an Instron tensile testing machine, to analyze the retentive properties of different luting cements. A one-way analysis of variance was used to analyze the data, with a significance level of alpha =.05. Results: Result showed a maximum mean retentive strength in Panavia Ex. (281.34kg), followed by Glass Ionomer (70.21kg), Polycarboxylate (63.06kg), and least in Zinc Phosphate cement (40.31 kg), which was statistically significant. Conclusion: Within the limitation of the present study, it was concluded that resinous adhesive Panavia Ex. cement has better retentive properties compare to other luting cements.

Retentiveness of Metal Coping Luted to Teeth of Uremic Patients Undergoing Hemodialysis Using Five Different Luting Cements

This study aimed to assess the retention of metal copings luted to uremic teeth with five different luting agents. A total of 35 sound natural molars was collected from uremic patients and randomly assigned into five groups (n=7). The teeth were prepared for metal copings using diamond tips and water coolant. Metal copings with a loop on the occlusal surface were fabricated using base metal alloy (Rexillium III). The copings were luted using Fuji I, glass ionomer (GI); Fuji Plus, resin-modified glass ionomer (RMGI); Panavia F 2.0, resin cement; Rely X Unicem, self-adhesive cement (SA); and Adhesor, zinc phosphate cement (ZPh). All specimens were incubated at 37°C for 24 hours, conditioned in artificial saliva for 7 days, and then thermocycled for 5000 cycles (5°C-55°C). The dislodging force was measured using a universal testing machine at a crosshead speed of 2 mm/min. The mode of failure of the loaded adhesive copings was evaluated. Statistical analyses were performed using one-way analysis of variance and Tukey post hoc test. GI and SA cements had the highest and the lowest mean retentive strength, respectively (580.90±17.3, 406.6±12.7). There was no significant difference between ZPh, SA, and resin cements. These cements were inferior to GI and RMGI cements (p<0.05), which showed statistically similar retentive strengths. The results of this study support the use of glass ionomer and resin-modified glass ionomer cements for luting of metal copings to uremic teeth with retentive preparations.

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

Clinical and laboratory studies regarding performance of recently introduced luting cements: Adhesive resin cement and resin-modified glass ionomer cement (GIC), are limited. 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. 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. Tukey's test, Analysis of Variance (ANOVA). 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. 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.

The effect of retentive groove, sandblasting and cement type on the retentive strength of stainless steel crowns in primary second molars - An in vitro comparative study

This in vitro study was conducted to find out the effect of retentive groove, sand blasting and cement type on the retentive strength of stainless steel crowns in primary second molars. Thirty-two extracted intact human maxillary and mandibular primary second molars were embedded in aluminum blocks utilizing autopolymerising acrylic resin. After tooth preparation, the 3M stainless steel crown was adjusted to the prepared tooth. Then weldable buccal tubes were welded on the buccal and lingual surfaces of each crown as an attachment for the testing machine. A full factorial design matrix for four factors (retentive groove placement on the tooth, cement type, sandblasting and primary second molar) at two levels each was developed and the study was conducted as dictated by the matrix. The lower and upper limits for each factor were without and with retentive groove placement on the tooth, GIC and RMGIC, without and with sandblasting of crown, maxillary and mandibular second primary molar. For those teeth for which the design matrix dictated groove placement, the retentive groove was placed on the middle third of the buccal surface of the tooth horizontally and for those crowns for which sandblasting of the crowns are to be done, sandblasting was done with aluminium oxide with a particle size of 250 mm. The crowns were luted with either GIC or RMGIC, as dictated by the design matrix. Then the retentive strength of each sample was evaluated by means of an universal testing machine. The obtained data was analyzed using ANOVA for statistical analysis of the data and 't'- tests for pairwise comparison. The mean retentive strength in kg/cm 2 stainless steel crowns luted with RMGIC was 19.361 and the mean retentive strength of stainless steel crowns luted with GIC was 15.964 kg/cm 2 with a mean difference of 3.397 kg/cm 2 and was statistically significant. The mean retentive strength in kg/cm 2 of stainless steel crowns, which was not sandblasted, was 18.880 and which was sandblasted was 16.445 kg/cm 2 with a mean difference of 2.436 kg/cm 2 . These results were again statistically significant. It was found that the crowns luted with resin-modified glass ionomer cements (RMGIC's) offered better retentive strength of crowns than glass ionomer cements (GIC) and stainless steel crowns which were cemented without sandblasting showed higher mean retentive strength than with sandblasting of crowns. The presence of groove did not influence the retentive strength of stainless steel crowns.

Retentiveness of implant-supported metal copings using different luting agents

Background:With regard to potential retrievability of cement-retained implant restorations, the retentive strength of the luting agents is critical. The aim of this study was to evaluate the retention values of implant-supported metal copings using different luting agents.Materials and Methods:Twenty ITI implant analogs and solid abutments of 5.5-mm height were embedded vertically in autopolymerizing acrylic resin blocks. Metal copings with a loop on the occlusal surface were fabricated using base metal alloy (Rexillium III). The copings were luted using eight cements with different retention mechanisms (Panavia F2.0, Fuji Plus, Fleck's, Poly F, Fuji I, Temp Bond, GC-free eugenol, and TempSpan) under static load of 5 kg (n=10). All specimens were incubated at 37°C for 24 hours, conditioned in artificial saliva for 7 days and thermocycled for 5000 cycles (5-55°C). The dislodging force was measured using a universal testing machine at a crosshead speed of 5 mm/min. Statistical analyses were performed using Kruskal-Wallis (α=0.05) and Mann-Whitney tests with Bonferroni correction (α=0.001).Results:Fuji Plus and TempSpan had the highest and the least mean retentive strength, respectively (320.97±161.47, 3.39±2.33). There was no significant difference between Fuji Plus, Fleck's, Ploy F, and Panavia F2.0. These cements were superior to provisional cements and Fuji I (P<0.001) which showed statistically same retentive strength.Conclusion:Within the conditions of this study, the resin modified glass ionomer, zinc phosphate, zinc polycarboxylate, and Panavia F2.0 had statistically the same retentive quality and are recommended for definitive cementation of single implant-supported restorations. The provisional cements and glass ionomer may allow retrievability of these restorations.

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

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 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. Comparison of the mean retentive strength was done using two-way Analysis of Variance (ANOVA) followed by Bonferroni method for multiple comparisons. 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. 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.

Chlorhexidine-modified glass ionomer forbandcementation? Anin vitrostudy

To compare the mean retentive strength, predominant site of band failure, amount of cement remaining on the tooth at deband and survival time of orthodontic micro-etched bands cemented with chlorhexidine-modified (CHXGIC) or conventional glass ionomer cement (GIC). In vitro study. Dental Materials Laboratory. One-hundred-and-twenty intact, caries-free third molars were collected from patients attending for third molar surgery. These were stored for 3 months in distilled water and decontaminated in 0.5% chloramine. To assess retentive strength, 80 teeth were randomly selected and 40 were banded with each cement. Testing was undertaken using a Nene M3000 testing machine at a cross-head speed of 1 mm/min. Following debanding, the predominant site of failure was recorded as cement-enamel or cement-band interface. The amount of cement remaining on the tooth surface following deband was assessed and coded. Survival time for another 40 banded specimens, 20 cemented with each cement, was assessed following application of mechanical stress in a ball mill. Retentive strength, predominant site of failure, amount of cement remaining on the tooth surface, survival time. Mean retentive strength for bands cemented with CHXGIC (0.32 MPa, SD 0.09) or GIC (0.28 MPa, SD 0.07) did not differ significantly (p=0.05). All bands failed at the enamel-cement interface. There was no significant difference in the amount of cement remaining on the tooth surface after deband for each cement type (p=0.23). The mean survival time of bands cemented with CHXGIC or GIC was 7.0 and 6.4 hours, respectively (p=0.23). There was no significant difference in mean retentive strength, amount of cement remaining on the tooth after deband or mean survival time of bands cemented with CHXGIC or GIC. Bands cemented with either cement failed predominantly at the enamel-cement interface. The results suggest that CHXGIC may have comparable clinical performance to GIC for band cementation.

The retention of complete crowns prepared with three different tapers and luted with four different cements

Statement of problem The role of adhesive properties of cements on the retentive strength of crowns with different degrees of taper is not clear. Purpose This study evaluated the retention of full crowns prepared with 3 different tapers and cemented with 2 conventional and 2 adhesive resin cements. Material and methods One hundred twenty sound human molar teeth were assigned randomly to 1 of 12 groups, (n=10). The groups represented the 4 cements: zinc phosphate (Fleck’s), a conventional glass ionomer (Ketac-Cem); 2 adhesive resin cements (C&B Metabond and Panavia); and 3 tapers of 6-degrees, 12-degrees, and 24-degrees within each cement. Crowns were cast with a high noble alloy. The 6-degree taper was considered the control within each cement group. Retention was measured (MPa) by separating the metal crowns from the prepared teeth under tension on a universal testing machine. Analysis of variance was used to test the main effects on the retentive strength of full crowns, namely cements, tapers, and failure modes. The Fisher’s multiple comparison test was used to evaluate the source of the differences. The χ 2 analyses were used to examine the relationships between failure types, cements, and tapers. All statistical tests were conducted at α=.05. Results There was a significant difference in the main effect cement ( P<.0001) and taper ( P=.0002). The mean retentive strength values of both Fleck’s and Ketac-Cem were significantly lower than the mean retentive strength values of both C&B Metabond and Panavia ( P<.0001). The retention of crowns prepared with 6-degree taper was not significant from the 12-degree taper ( P=.0666). The difference in retention was significant between the 6-degree taper and the 24-degree taper ( P<.0001) and between12-degree taper and 24-degree taper ( P=.0178). The types of failure were adhesive in the cement (65%), cohesive in the tooth (31%), and assembly failure (fracture of embedding resin) (4%). The type of failure was dependent on the degree of taper ( P<.0001) and on the type of cement ( P<.0042). Conclusion Within the limitations of this study, the retentive values of the adhesive resins at 24-degree taper were 20% higher than the retentive values of the conventional cements at 6-degree taper. The use of resin luting agents yielded retention values that were double the values of zinc phosphate or conventional glass ionomer cement.

In vitro comparison of orthodontic band cements

The aim of the study was to compare the mean retentive strength of microetched orthodontic bands cemented to extracted human third molars with a modified composite, a resin-modified glass ionomer cement, and a conventional glass ionomer cement. The mode of band failure and amount of cement remaining on the tooth at deband were also assessed. Finally, survival time of bands with each cement was assessed with simulated mechanical stress in a ball mill. Ninety banded specimens were used to assess retentive strength, and another 30 banded specimens were used to assess survival time. The mean retentive strength of the modified composite (0.415 MPa) was significantly less than that of either the resin-modified (1.715 MPa) or the conventional glass ionomer cement (1.454 MPa; P <.001). Specimens failed predominantly at the cement-enamel interface. The amount of cement remaining on the tooth at deband differed significantly between bands cemented with the resin-modified cement and those cemented with the conventional glass ionomer cement (P <.05). Mean survival time of bands cemented with the resin-modified glass ionomer cement (14.3 hours) was significantly longer (P <.01) than for bands cemented with the conventional glass ionomer cement (9.9 hours) but did not differ significantly from that of bands cemented with the modified composite (11.1 hours; P >.05). Orthodontic bands cemented with the modified composite appear to have a significantly lower mean retentive strength than bands cemented with resin-modified or conventional glass ionomer cement, but mean survival time did not differ significantly for bands cemented with modified composite or resin-modified glass ionomer. (Am J Orthod Dentofacial Orthop 2003;123:15-20)

Use of luting agents with an implant system: Part I

When removal of the provisionally cemented superstructure from a cemented abutment becomes necessary, the retentive strengths of the abutment/fixture and superstructure/abutment luting agents become important considerations. This study compared the retentive strengths of castings cemented to machined titanium implant abutments and to a human premolar with three provisional luting agents. Also tested were the retentive strengths of cast noble metal implant abutments cemented into titanium fixtures with three permanent luting agents both dry and after storage in 0.9% physiologic saline for 30 days at 37 ° C. No significant differences (α <0.05) were noted in retentive values between the cemented castings on the titanium abutments and the natural tooth. The Temp Bond zinc oxideeugenol luting agent exhibited a lower mean retentive strength than the IRM reinforced zinc oxide-eugenol and Life calcium hydroxide luting agents. Ketac Cem glass-ionomer cemented abutments that were stored in saline exhibited a significantly higher mean retentive strength than abutments cemented with either Core Paste or Regiment resin luting agents. On the basis of results from this study, it may be concluded that superstructures provisionally cemented with Temp Bond, IRM, or Life luting agents may be removed from implant abutments without disturbing the abutment/fixture or implant bond.

Retention of castings with glass ionomer cement

The retentive abilities of a glass ionomer cement, a zinc phosphate cement, and a zinc silicophosphate cement were compared using 20 cast-gold inlays. The mean retentive strength of the glass ionomer cement was the greatest and that of the zinc phosphate cement the weakest. The differences between the mean retentive strengths of all three cements were statistically significant (p = .001).