Khalil Aleisa

Effect of three endodontic sealers on the bond strength of prefabricated fiber posts luted with three resin cements

STATEMENT OF PROBLEM There is limited information in the literature regarding the effect of eugenol-based sealers on the bond strength of resin-bonded endodontic posts. PURPOSE The purpose of this study was to evaluate the effect of 1 resin-based and 2 different eugenol-based endodontic sealers on the bond strength of prefabricated fiber posts luted with 3 different resin cements. MATERIAL AND METHODS One hundred thirty-five prefabricated fiber posts were luted into extracted single-rooted teeth with 1 of 3 composite resin cements (Rely X Unicem, Paracore, and Variolink II). Specimens were divided into 3 groups with 45 teeth each. The first 2 groups were obturated with gutta percha and 1 of 2 eugenol-based endodontic sealers (Endofil, Tubli-Seal). The third group was obturated with a resin-based root canal sealer (AH26). The forces required for dislodgment of posts from their prepared post spaces were recorded by using a universal testing machine. Data were collected and a 2-way ANOVA was applied to the mean retentive strengths of various combinations of sealer and cement. A Tukey multiple comparison test was performed to determine which groups were significantly different (α=.05). RESULTS Endofil and Tubli-Seal (eugenol-based sealers) groups had significantly lower bond strengths for the posts than the AH26 group (P<.001). There was no significant difference between the means of post bond strength for the Endofil and Tubli-Seal groups. There was significant difference among the means of post bond strength for all 3 cement groups (P<.05). CONCLUSIONS Endofil and Tubli-Seal (eugenol-based) sealers demonstrated significantly reduced mean bond strength for prefabricated fiber posts luted with resin cement. Rely X Unicem resin cement exhibited higher mean bond strength than with Paracore and Variolink II resin cements when a eugenol sealer was used.

In Vitro Evaluation of the Effect of Different Endodontic Sealers on Retentive Strength of Fiber Posts

PURPOSE There is limited information in the literature regarding the effect of different endodontic sealers on the bond strength of fiber posts luted with core buildup materials. The purpose of this study was to evaluate the effect of three different root canal sealers on the retentive strength of prefabricated fiber posts luted with a composite resin cement. MATERIALS AND METHODS Fifty-four extracted single-rooted mandibular premolar teeth were prepared and randomly divided into three groups. The first two groups were obturated with gutta-percha and one of two eugenol-based root canal sealers (Endofil, Tubli-Seal). The third group (control) was obturated with gutta-percha and a resin-based root canal sealer (AH26). Prefabricated fiber posts were luted into the prepared post spaces with a composite resin cement (Multicore Flow). The pullout forces required for dislodgment of posts from their prepared post spaces were recorded. Data were collected and statistically analyzed. RESULTS The AH26 group had significantly greater retentive strengths for the posts when compared with the Endofil and Tubli-Seal (eugenol-based sealers) groups (p<0.0001). There was no significant difference between the means of the retentive strengths for the Endofil and Tubli-Seal groups (p=0.745). CONCLUSION The chemical formulation of root canal sealers significantly affected the retentive strength for prefabricated fiber posts luted with a resin cement. Eugenol-based sealers significantly reduced the bond strength of prefabricated fiber posts luted with resin cement.

Effect of luting agents on the tensile bond strength of glass fiber posts: An in vitro study

STATEMENT OF PROBLEM Fiber posts can fail because of loss of retention; and it is unknown which luting agent provides the highest bond strength. PURPOSE The purpose of this study was to investigate the tensile bond strength of glass fiber posts luted to premolar teeth with 6 resin composite luting agents. MATERIAL AND METHODS Ninety-six single-rooted extracted human mandibular premolars were sectioned 2 mm coronal to the most incisal point of the cementoenamel junction. Root canals were instrumented and obturated with laterally condensed gutta percha and root canal sealer (AH26). Gutta percha was removed from the canals to a depth of 8 mm and diameter post spaces with a 1.5 mm were prepared. The specimens were divided into the following 6 groups according to the luting agent used (n=16): Group V, Variolink II; Group A, RelyX ARC; Group N, Multilink N; Group U, RelyX Unicem; Group P, ParaCore; Group F, MultiCore Flow. Each specimen was secured in a universal testing machine and a separating load was applied at a rate of 0.5 mm/min. The forces required to dislodge the posts were recorded. A 1-way analysis of variance (ANOVA) was applied to the mean retentive strengths of various cement materials (α=.05). RESULTS Significant differences were recorded among the 6 cement types (P<.001). Three materials provided statistically equivalent mean bond strengths (RelyX Unicem, Paracore, and MultiCore Flow) that were significantly greater than for the other 3 materials. CONCLUSIONS Fiber posts luted with RelyX Unicem, Paracore, and MultiCore Flow demonstrated significantly higher bond strengths.

Effect of types of luting agent on push-out bond strength of zirconium oxide posts

OBJECTIVE The aim of this study was to investigate the effect of different luting agents on the bond strength of zirconium oxide posts in root canals after artificial ageing. MATERIAL AND METHODS Thirty single-rooted extracted teeth were collected. Post spaces were prepared. Custom milled zirconium oxide posts (Cercon, Degudent) were fabricated. Specimens were divided into 3 groups (n=10), according to the luting agents used: group RA, conventional resin luting agent (RelyX ARC); group RU, self-adhesive resin luting agent (RelyX Unicem); and group Z, zinc phosphate luting agent (DeTrey). Specimens were subjected to thermocycling and water storage at 37°C. Specimens were horizontally sectioned into three sections and subjected to a push-out test with 0.5mm/min crosshead speed. The failure mode was assessed by scanning electron microscopy. Data were analysed by using 2-way ANOVA. RESULTS The following bond strength values were obtained: group RA - 8.89 MPa, group RU - 10.30 MPa and group Z - 9.31 MPa. There was no significant difference in bond strength among the groups (P=0.500). Adhesive failure mode at the cement/post bonded interface was seen in 100%, 66.67% and 83.3% of examined sections in groups RA, RU and Z, respectively. There was no significant difference in bond strength among different root regions (P=0.367). CONCLUSION The type of luting agent had no significant effect on the push-out bond strength of zirconium oxide posts after artificial ageing. CLINICAL SIGNIFICANCE Conventional luting agents, such as zinc phosphate cement, seem to provide comparable retention to resin luting agents for cementing custom milled zirconium oxide posts.

Implant Fixture Heat Transfer During Abutment Preparation

The purpose of the study was to evaluate the effect of water flow rate on the heat transmission in implants during abutment preparation using a diamond bur in a high-speed dental turbine. Titanium-alloy abutments (n = 32) were connected to a titanium-alloy implant embedded in an acrylic resin within a water bath at a controlled temperature of 37°C. The specimens were equally distributed into 2 groups (16 each) according to the water flow rate used during the preparation phase. Group 1 had a water flow rate of 24 mL/min, and group 2 had a water flow rate of 40 mL/min. Each abutment was prepared in the axial plane for 1 minute and in the occlusal plane for 1 minute with a coarse tapered diamond bur using a high-speed dental handpiece. Thermocouples embedded at the cervix of the implant surface were used to record the temperature of heat transmission from the abutment preparation. Heat generation was measured at 3 distinct times (immediately and 30 seconds and 60 seconds after the end of preparation). Statistical analyses were carried out using 2-way analysis of variance and the Student t test. Water flow rates (24 mL vs 40 mL) and time interval had no statistically significant effect on the implants temperature change during the abutment preparation stage (P = .431 and P = .064, respectively). Increasing the water flow rate from 24 to 40 mL/min had no influence on the temperature of the implant fixture recorded during preparation of the abutment.

Adhesion of cast metal alloy and lithium disilicate copings luted to different core build-up materials with self-adhesive resin cement

Abstract This study evaluated the shear bond strength of two coping materials (non-nickel chrome-based cast alloy and lithium disilicate ceramic (IPS Empress) to four different core foundation materials (resin composite, cast metal alloy, lithium disilicate, and dentin), luted with adhesive resin cement (RelyX Unicem). Specimens (N = 56) were fabricated and divided into eight groups (n = 7 per group). Each coping material was luted with self-adhesive resin cement (RelyX Unicem) to the core materials. Bond strength was measured in a Universal Testing Machine (0.5 mm/min). Data were statistically analyzed using a two-way analysis of variance (ANOVA) and Tukey’s HSD tests (alpha = 0.05). Both core (p = 0.000) and coping material type (p = 0.000) significantly affected the mean bond strength (MPa) values. Interaction terms were also significant (p = 0.001). The highest bond strength results were obtained when lithium disilicate was bonded to lithium disilicate (21.48) with the resin cement tested. Lithium disilicate in general presented the highest bond results when bonded to all core materials tested (16.55–21.38) except dentin (3.56). Both cast alloy (2.9) and lithium disilicate (3.56) presented the lowest bond results on dentin followed by cast-alloy-cast alloy combination (3.82).

Heat Generation on Implant Surface During Abutment Preparation at Different Elapsed Time Intervals

Purpose: The purpose of this study was to evaluate heat generation at the implant surface caused by abutment preparation using a diamond bur in a high-speed dental turbine in vitro at 2 different water-coolant temperatures. Materials and Methods: Thirty-two titanium-alloy abutments were connected to a titanium-alloy implant embedded in an acrylic resin placed within a water bath at a controlled temperature of 37°C. The specimens were equally distributed into 2 groups (16 each). Group 1: the temperature was maintained at 20 ± 1°C; and group 2: the temperature was maintained at 32 ± 1°C. Each abutment was prepared in the axial plane for 1 minute and in the occlusal plane for 1 minute. The temperature of the heat generated from abutment preparation was recorded and measured at 3 distinct time intervals. Results: Water-coolant temperature (20°C vs 32°C) had a statistically significant effect on the implants temperature change during preparation of the abutment (P < 0.0001). Conclusion: The use of water-coolant temperature of 20 ± 1°C during preparation of the implant abutment decreased the temperature recorded at the implant surface to 34.46°C, whereas the coolant temperature of 32 ± 1°C increased the implant surface temperature to 40.94°C.