The effect of root canal sealers and timing of cementation on the microlekage of the parapost luted with resin cement

Objectives

The objectives of the study were to study the effect of root canal sealers either eugenol or non-eugenol and timing of cementation on microleakage of the parapost luted with resin cement.

Materials and methods

Seventy extracted human, single-rooted teeth were instrumented using a crown-down technique. All teeth were instrumented up to a size 50 .04 taper ProFile followed by the use of Gates Glidden drills from size 2 up to 5. Following instrumentation, the teeth were randomly divided into four experimental groups of fifteen teeth each, based on type of root canal sealer (eugenol or non-eugenol sealer) and timing of post cementation (immediate or delayed). The remaining ten teeth were divided into two control groups with five teeth per group. All teeth were tested for microleakage using a fluid filtration method.

Results

The microleakage of the paraposts luted with resin cement increased over time, irrespective of sealer type or timing of post cementation. Immediate post cementation following obturation with AH26 (non-eugenol sealer) produced the least microleakage at all three time periods at 24 h, 2 months and 3 months.

Conclusions

The microleakage paraposts luted with resin cement was not influenced by either sealer type or timing of post placement. All experimental groups demonstrated a significant increase in microleakage over time as well as the presence of voids at the resin–dentin interface.     

Retention of fiber posts to the optimally and over-prepared dowel spaces

PURPOSE

To assess the retention of glass fiber post cemented with self-adhesive resin cement into optimum and over-prepared root canals following obturation in the presence of either eugenol (EB) or calcium hydroxide (CB)-based sealers.

MATERIALS AND METHODS

Roots of extracted premolars were endodontically-treated in 5 groups (n = 10). Roots of Group 1 (control) were left with no obturation and then optimally prepared to receive endodontic dowels. Other root canals were obturated with gutta-percha in the presence of either eugenol-based (Groups 2 and 4) or calcium hydroxide-based (Groups 3 and 5) sealer. Dowel spaces were prepared with optimal diameter in Groups 2 and 3, one size larger in Groups 4 and 5. Standardized fiber posts were luted to the prepared spaces using self-adhesive resin cement and itsretention was then tested on an universal testing machine. Both one-way ANOVA and Tukey''s HSD comparisons (α=0.05) were used to identifythe significance of inter-group retention differences. Scanning electron microscopy (SEM) of both optimally and over-prepared dowel spaces was also considered to figure the nature of their interior out.

RESULTS

The post retention was significantly higher to the non-obturated, optimally-prepared dowel spaces of Group 1 compared to the obturated, optimally-prepared ones of Groups 2 and 3. For each dowel space diameter, root canals obturated using CB of Groups 3 and 5 showed significantly higher dowel retention compared to those obturated using EB of Groups 2 and 4. Post retention to the over-prepared dowel spaces of Groups 4 and 5 was significantly higher than that recorded for the optimally-prepared ones of Groups 1-3. SEM images revealed traces of endodontic sealer and gutta-percha on the walls of the optimally-prepared dowel spaces.

CONCLUSION

Despite the adverse effect of endodontic sealers on the retention of fiber posts, the over-preparation of dowel spaces helps to improve the retention.     

Post retention: the effect of sequence of post-space preparation, cementation time, and different sealers.

Many endodontic sealers contain constituents that have been shown to inhibit the polymerization of resin cements. This may be important when prefabricated posts are cemented at the same appointment as root canal obturation. This study evaluated the effects of cementing posts with a resin cement immediately or at a delayed time period after obturation using Roth's 801 Elite Grade or AH26 sealer cements. The contribution of mechanical post-space preparation was also assessed as a critical variable. One hundred twenty extracted canines were randomly divided into eight experimental groups. The variables evaluated were the order of post preparation (either before or after obturation), the type of sealer used, and the time of post cementation. All teeth received a stainless steel #6 Parapost XP cemented with a resin cement, Panavia 21. Each experimental group underwent tensile testing for retention using an Instron universal testing machine. For both sealers posts cemented in teeth in which the canal was obturated before post-space preparation and thus had sealer-contaminated dentin removed by the space preparation procedure had significantly higher retentive values than those obturated after post-space preparation in which contaminated dentin might remain. Sealer used and time of cementation had no specific effect on retention. Achieving a clean, "freshened" dentinal surface during mechanical post-space preparation seems to be a critical variable for post retention when a resin cement is used.     

The interference of the cleaning procedure of root walls with two different solvents on the adhesion of fiberglass intraradicular posts

Aim: This study was undertaken to examine the effect of root canal (RT) sealers content and the cleaning procedure of RT walls on bond strength (BS) of a fiber reinforced composite (FRC) post cemented with resin-based or zinc phosphate cement. Materials and methods: Forty bovine roots were divided into 2 groups (n = 20) and obturated with gutta-percha points plus Sealer 26 sealer or gutta-percha points plus N-Rickert sealer. In each group, half (n = 10) of intracanal walls was cleaned with ethanol and the other half with sulfuric ether. In each of these subgroups, half of intracanal posts (n = 5) were cemented with Bistite resin-based cement and half with zinc phosphate cement. Specimens were submitted to pull-out test and tensile force until post dislodgement. The maximum forces required for post removal was expressed in MPa, means were submitted to statistical analysis (Analysis of Variance Test, a = 0.05). Results: Fiber reinforced composite cemented with zinc phosphate were significantly more retentive than those cemented with Bistite (p < 0.05). Regarding the influence of eugenol-based sealer on post retention, there was a statistically significant difference (p < 0.05) only between groups cemented with Bistite, in which canals filled with N-Rickert + gutta-percha showed lower BS than canals filled with Sealer 26 + gutta-percha. Conclusion: Despite endodontic cement used, higher pull-out bond strength were obtained when posts were cemented with zinc phosphate. Clinical significance: The importance of ethanol or sulphuric ether application to properly replace water from intraradicular dentine still requires further investigations, especially to clarify if this technique may reduce the effect of aging and improve the stability of the bond, when used to cement fiber posts into the root canal. Keywords: Laboratory research, Dentin, Eugenol, Resin cements, Root canal filling material, Pull-out test, Cleaning procedure. How to cite this article: Gomes MF, Botta SB, Matos AB, Garone- Netto N. The Interference of the Cleaning Procedure of Root Walls with Two Different Solvents on the Adhesion of Fiberglass Intraradicular Posts. J Contemp Dent Pract 2012;13(3):275-279. Source of support: Nil Conflict of interest: None declared.     

Effect of eugenol-based root canal sealers on retention of prefabricated metal posts luted with resin cement

Objective

This study evaluated the effect of two different eugenol-based root canal sealers on the retention of prefabricated metal posts luted with adhesive resin cement.

Materials and methods

Thirty prefabricated ParaPosts randomly divided among three groups of 10 each were luted into extracted single-rooted teeth with adhesive resin cement. Two of the groups had been obturated with Gutta–Percha and one of two eugenol-based root canal sealers (Endofil and Tubli-Seal), respectively. The third group was not obturated and served as the control. The forces required for dislodgment of posts from their prepared post spaces were recorded using a universal testing machine. Data were statistically analyzed using one-way ANOVA and Tukey’s multiple range test was used to determine the mean differences.

Results

Endofil and Tubli-Seal groups demonstrated significantly reduced retention compared to the unobturated (control) group (P < 0.05).

Conclusion

Eugenol-based sealers significantly reduced the retention of prefabricated posts luted with adhesive resin cement.     

Effects of post surface conditioning before silanization on bond strength between fiber post and resin cement

PURPOSE

Post surface conditioning is necessary to expose the glass fibers to enable bonding between fiber post and resin cement. The purpose of the present study was to evaluate the effect of different surface conditioning on tensile bond strength (TBS) of a glass fiber reinforced post to resin cement.

MATERIALS AND METHODS

In this in vitro study, 40 extracted single canal central incisors were endodontically treated and post spaces were prepared. The teeth were divided into four groups according to the methods of post surface treatment (n=10): 1) Silanization after etching with 20% H₂O₂, 2) Silanization after airborne-particle abrasion, 3) Silanization, and 4) No conditioning (Control). Adhesive resin cement (Panavia F 2.0) was used for cementation of the fiber posts to the root canal dentin. Three slices of 3 mm thick were obtained from each root. A universal testing machine was used with a cross-head speed of 1 mm/minute for performing the push-out tests. Two-way ANOVA and Tukey post hoc tests were used for analyzing data (α=0.05).

RESULTS

It is revealed that different surface treatments and root dentin regions had significant effects on TBS, but the interaction between surface treatments and root canal regions had no significant effect on TBS. There was significant difference among H₂O₂ + Silane Group and other three groups.

CONCLUSION

There were significant differences among the mean TBS values of different surface treatments. Application of hydrogen peroxide before silanization increased the bond strength between resin cements and fiber posts. The mean TBS mean values was significantly greater in the coronal region of root canal than the middle and apical thirds.     

INFLUENCE OF LUTING AGENTS ON TIME REQUIRED FOR CAST POST REMOVAL BY ULTRASOUND: AN IN VITRO STUDY

Objective:

This in vitro study evaluated the influence of luting agents on ultrasonic vibration time for intraradicular cast post removal.

Material and Methods:

After endodontic treatment, 30 roots of extracted human canines were embedded in resin cylinders. The post-holes were prepared at 10 mm depth and their impressions were taken using autopolymerizing acrylic resin. After casting procedures using a nickel-chromium alloy, the posts were randomly distributed into 3 groups (n=10) according to the luting material: G1- zinc phosphate (SS White) (control group), G2 - glass ionomer cement (Vidrion C; SS White), and G3- resin cement (C&B; Bisco). In G3, the adhesive procedure was performed before post cementation. After 24 h, the cement line was removed at the post/tooth interface using a fine diamond bur, and the ST-09 tip of an Enac ultrasound unit was applied at maximum power on all surfaces surrounding the posts. The application time was recorded with a chronometer until the post was completely dislodged and data were analyzed by ANOVA and Tukey''s test (p<0.05).

Results:

The roots were removed from the acrylic resin and inspected to detect cracks and/or fractures. The means for G1, G2, and G3 were 168.5, 59.5, and 285 s, respectively, with statistically significant differences among them. Two G3 posts resisted removal, one of which developed a vertical fracture line.

Conclusions:

Therefore, the cement type had a direct influence on the time required for ultrasonic post removal. Compared to the zinc phosphate and glass ionomer cements, the resin cement required a longer ultrasonic vibration time.     

Effects of curing protocol and storage time on the micro-hardness of resin cements used to lute fiber-reinforced resin posts

Objectives

To determine the micro-hardness profile of two dual cure resin cements (RelyX - U100^®, 3M-ESPE and Panavia F 2.0^®, Kuraray) used for cementing fiber-reinforced resin posts (Fibrekor^® - Jeneric Pentron) under three different curing protocols and two water storage times.

Material and methods

Sixty 16mm long bovine incisor roots were endodontically treated and prepared for cementation of the Fibrekor posts. The cements were mixed as instructed, dispensed in the canal, the posts were seated and the curing performed as follows: a) no light activation; b) light-activation immediately after seating the post, and; c) light-activation delayed 5 minutes after seating the post. The teeth were stored in water and retrieved for analysis after 7 days and 3 months. The roots were longitudinally sectioned and the microhardness was determined at the cervical, middle and apical regions along the cement line. The data was analyzed by the three-way ANOVA test (curing mode, storage time and thirds) for each cement. The Tukey test was used for the post-hoc analysis.

Results

Light-activation resulted in a significant increase in the microhardness. This was more evident for the cervical region and for the Panavia cement. Storage in water for 3 months caused a reduction of the micro-hardness for both cements. The U100 cement showed less variation in the micro-hardness regardless of the curing protocol and storage time.

Conclusions

The micro-hardness of the cements was affected by the curing and storage variables and were material-dependent.     

Effect of eugenol-based endodontic cement on the adhesion of intraradicular posts

The present study evaluated, in vitro, the influence of an eugenol-based endodontic sealer (EndoFill) on the adhesion of intra-radicular posts cemented with a resin-based cement (Enforce) ou a zinc phosphate cement. Twenty-four single-rooted maxillary canines were divided into 2 groups (n=12) and obturated with either gutta-percha points plus EndoFill or gutta-percha points alone (no cement). In each group, half of intracanal posts (n=6) were cemented with Enforce resin-based cement and half with zinc phosphate cement. Specimens were submitted to pull-out test in an Instron machine and tensile force was applied at a crosshead speed of 0.5 mm/min until post dislodgement. The maximum forces required for post removal was recorded (N) and means were submitted to statistical analysis by Kruskal-Wallis test (p<0.01). Posts cemented with zinc phosphate cement were significantly more retentive (353.4 N) than those cemented with Enforce (134.9 N) (p<0.01). Regarding the influence of the eugenol-based cement (EndoFill) on post retention, there was statistically significant difference (p<0.01) only between the groups cemented with Enforce, i.e., in the canals filled with EndoFill + guta-percha there was lower bond strength than in the canals filled with gutta-percha points alone (101.5 and 168.2 N, respectively). In conclusion, the zinc-phosphate-based cement showed greater post retention than the resin-based cement. The findings of this study suggest that the eugenol-containing sealer interfered with the adhesive properties of the resin-based cement.     

Effect of endodontic sealer and resin luting strategies on pull-out bond strength of glass fiber posts to dentin

The aim of this study was to evaluate the influence of eugenol-containing endodontic sealers and luting strategy on the pull-out bond strength of glass fiber posts to dentin. Sixty-four bovine incisors were randomly assigned into two groups of 32 specimens each for obturation procedure with gutta-percha only, or with Pulp Canal Sealer EWT Subsequently, the roots were prepared for the fiber post Reforpost and all specimens of each endodontic sealing procedure were allocated to four groups (n = 8), according to the strategies for post cementation: A) Single Bond 2 and RelyX ARC; B) All Bond 2 and C&B cement; C) All Bond 2 and RelyX ARC; D) Single Bond 2 and C&B Cement. The posts were cemented immediately after the endodontic treatment. The pull-out test was performed at a cross-head speed of 0.5 mm/min in a universal testing machine (EMIC). Data (Kgf) were submitted to a two-way ANOVA and Tukey test (p < or = 0.05). The eugenol-based sealer did not influence the pull-out bond strength of fiber posts regardless of the luting strategy. RelyX ARC showed higher bond strength than C&B Cement when used with Single Bond 2 adhesive system, when the eugenol-based sealer was present. All Bond 2, when associated to all cements studied, promoted similar bond strength, regardless of the eugenol-containing endodontic sealer In conclusion, eugenol-containing sealer did not influence the pull-out bond strength values of the resin luting systems for glass fiber post cementation. The bond system and resin cement association from the same manufacturer had similar bond strength values for dentin.     

Effect of ultrasonic vibration and various sealer and cement combinations on titanium post removal

The purpose of this study was to determine the effect of ultrasonic vibration on the force required to remove prefabricated posts. Ninety-six extracted human canines were divided into eight groups, which were prepared and obturated with gutta-percha and either a eugenol-containing (Roth's 801 Elite) or eugenol-free (AH26) sealer. Titanium #6 Parapost XH posts were cemented with either zinc phosphate or Panavia 21 resin cement. One half of the sample was subjected to ultrasonic vibration for 16 min at the post-dentin interface, whereas the other half received no vibration (controls). Each combination of sealer, cement, and vibration status was subjected to tensile load to failure using an Instron testing machine. Posts cemented in teeth obturated with gutta-percha and AH26 sealer demonstrated significantly greater resistance to dislodgement, compared with teeth obturated with gutta-percha and Roth's 801 Elite sealer. There was no statistical difference in retention of posts cemented with either zinc phosphate or Panavia 21, regardless of the sealer used. Additionally ultrasonic vibration increased post retention for both cements.     

Effect of dowel space preparation and composite cement thickness on retention of a prefabricated dowel

PURPOSE: This investigation examined what effect cement thickness had on retention of prefabricated endodontic dowels luted with a composite resin cement (Panavia 21 OP; J Morita, Irvine, CA) into canals previously obturated with gutta percha and a eugenol-based sealer. MATERIALS AND METHODS: Sixty-four single-rooted teeth were decoronated, filed, cleaned, and sequentially shaped with sizes 2-5 Gates Glidden drills (Dentsply/Maillefer, Tulsa, OK) and 0.12 taper rotary instrumentation. Teeth were then divided into 4 groups of 16 specimens each. All specimens were obturated with gutta percha and a eugenol-based sealer. Dowel space preparation and dowel cementation were completed 1 week after obturation. Ten-millimeter-deep dowel spaces were prepared using dowel drills with 4 different diameters: size 5 Parapost drill (Group 1; Coltene/Whaledent, Mahwah, NJ); size 5.5 Parapost drill (Group 2; Coltene/Whaledent); size 6 Gates Glidden drill (Group 3; Dentsply/Maillefer); size 6 Parapost drill (Group 4; Coltene/Whaledent). Size 5 Paraposts were then cemented with Panavia 21 OP. After 48 hours of storage, specimens were mounted in polyvinyl chloride (PVC) pipe with acrylic, and the dowels were removed in tensile mode using a universal testing machine at 1 mm/min, with data recorded in kilograms. RESULTS: (all values in kilograms) Group 1 (Parapost 5) mean = 15.07, 95% confidence interval (CI) = +/-6.11; Group 2 (Parapost 5.5) mean = 25.60, 95% CI = +/-7.39; Group 3 (Gates-Glidden 6) mean = 43.15, 95% CI = +/-7.81; Group 4 (Parapost 6) mean = 37.75, 95% CI = +/-6.35. Analysis of variance and Bonferroni tests revealed that Group 3 had significantly greater mean retention strength values than Group 1 and Group 2 (p <.05), and that Group 4 had significantly greater mean retention strength values than Group 1 (p <.05). CONCLUSIONS: Paraposts cemented with Panavia 21 OP showed significantly greater retention in oversized dowel spaces compared with dowel spaces prepared with the manufacturers' matched dowel-drill set.     

EFFECT OF RELINING ON FIBER POST RETENTION TO ROOT CANAL

One of the clinically relevant problems dentists face when restoring endodontically treated teeth is the mismatch between fiber post and post space diameters, which results in an excessively thick resin cement layer. Fiber post relining appears as a solution for this problem.

Objectives:

The aim of this study was to evaluate the effect of fiber post relining with composite resin on push-out bond strength.

Material and Methods:

Twenty bovine incisors were selected to assess post retention. The crowns were removed below the cementoenamel junction and the root canals were treated endodontically and flared with diamond burs. The roots were allocated into two groups (n=10): G1: fiber posts without relining and G2: fiber posts relined with composite resin. The posts were cemented with a dual-cured resin cement and the specimens were sectioned transversally. Three 1.5-mm thick slabs were obtained per root and identified as cervical, medium and apical thirds. The push-out test was performed at a crosshead speed of 0.5 mm/min until post dislodgement occurred. The failure mode of fractured specimens was analyzed under scanning electron microscopy. Data were analyzed by split-plot ANOVA and post-hoc Tukey''s test at a pre-set alpha of 0.05.

Results:

Relined fiber posts presented higher retention values than non-relined post in all thirds. No statistically significant differences (p>0.05) were found among thirds for relined posts. All failures occurred at the interface between resin cement and root dentin.

Conclusions:

Relining with composite resin seems to be an effective method to improve the retention of fiber posts to flared root canals.     

Push-out bond strength of fiber posts to root dentin using glass ionomer and resin modified glass ionomer cements

Objective

The purpose of this study was to assess the push-out bond strength of glass fiber posts to root dentin after cementation with glass ionomer (GICs) and resin-modified glass ionomer cements (RMGICs).

Material and Methods

Fifty human maxillary canines were transversally sectioned at 15 mm from the apex. Canals were prepared with a step back technique until the application of a #55 K-file and filled. Post spaces were prepared and specimens were divided into five groups according to the cement used for post cementation: Luting & Lining Cement; Fuji II LC Improved; RelyX Luting; Ketac Cem; and Ionoseal. After cementation of the glass fiber posts, all roots were stored at 100% humidity until testing. For push-out test, 1-mm thick slices were produced. The push-out test was performed in a universal testing machine at a crosshead speed of 0.5 mm/minute and the values (MPa) were analyzed by Kolmogorov-Smirnov and Levene''s tests and by two-way ANOVA and Tukey''s post hoc test at a significance level of 5%.

Results

Fiber posts cemented using Luting & Lining Cement, Fuji II LC Improved, and Ketac Cem presented the highest bond strength to root dentin, followed by RelyX Luting. Ionoseal presented the lowest bond strength values (P>0.05). The post level did not influence the bond strength of fiber posts to root dentin (P=0.148). The major cause of failure was cohesive at the cement for all GICs and RMGICs.

Conclusions

Except for Ionoseal, all cements provided satisfactory bond strength values.     

EVALUATION OF APICAL MICROLEAKAGE OF TEETH SEALED WITH FOUR DIFFERENT ROOT CANAL SEALERS

Objectives:

to compare the apical sealing ability of four root canal sealers. Materials and methods: forty extracted human maxillary canines were instrumented 1 mm short of the anatomical apex and randomly assigned to four groups (n=10), according to the root canal sealer used for obturation: Endofill, AH Plus, EndoREZ and Epiphany. Root canals were obturated with guttapercha points, except for the Epiphany group, in which resin points (Resilon) were used. The teeth were immersed in India ink for seven days and clarified using methyl salicylate. The extent of apical dye penetration was measured with a measuroscope in all aspects of the canal.

Results:

AH Plus (0.02 mm ± 0.07), Epiphany (0.00 mm ± 0.00) and EndoREZ (0.32 mm ± 0.62) did not differ statistically to each other (p>0.01). EndoFill presented the highest dye penetration mean (0.83 mm ± 0.73) and was statistically different from the other sealers (p<0.01).

Conclusions:

the resin-based root canal sealers presented lesser apical microleakage than the zinc oxide and eugenol based sealer. No statistical differences were observed among resin based sealers.     

FRACTURE RESISTANCE AND FAILURE PATTERN OF TEETH SUBMITTED TO INTERNAL BLEACHING WITH 37% CARBAMIDE PEROXIDE,WITH APPLICATION OF DIFFERENT RESTORATIVE PROCEDURES

Objective.

This study investigated the compressive fracture strength and failure pattern in premolars submitted to endodontic treatment and internal bleaching with 37% carbamide peroxide for 21 days, with application of different restorative procedures.

Material and methods.

Six groups were employed (n = 10): 1) non-bleached teeth and pulp chamber sealed with IRM; 2) bleached teeth and pulp chamber sealed with IRM; 3) bleached teeth and pulp chamber filled with light cured composite resin; 4) bleached teeth, root canals prepared at 10mm, filling of the root canal and pulp chamber with IRM; 5) bleached teeth, root canals prepared at 10mm, luting of prefabricated metallic post with zinc phosphate and pulp chamber sealed with composite resin; 6) bleached teeth, root canals prepared at 10mm, luting of glass fiber post with resin cement and pulp chamber sealed with composite resin. After 24-hour storage in distilled water, the specimens were submitted to compressive fracture strength testing in a universal testing machine.

Results.

The following values were found: Group 1 – 56.23kgf; Group 2 – 48.96kgf; Group 3 – 53.99kgf; Group 4 – 45.72kgf; Group 5 – 54.22kgf; Group 6 – 60.12kgf. The analysis of variance did not reveal statistically significant difference between groups (p<0.05), suggesting that internal bleaching with 37% carbamide peroxide did not weaken the dental tissues. The largest number of unfavorable fractures was observed for Groups 2 (50%), 4 (40%), and 5 (30%). Group 6 exhibited the most favorable failure pattern.

Conclusions.

The results suggest that internal bleaching with 37% carbamide peroxide did not significantly weaken the teeth. Among the bleached teeth, those with temporary IRM restorations or metallic posts demonstrated the most unfavorable fracture pattern, whereas the most favorable fracture pattern occurred in teeth restored with composite resin and glass fiber posts.     

Effect of calcium silicate-based endodontic sealer on the retention of fiber posts cemented at different time intervals

ObjectiveTo evaluate the effect of BC HiFlow, a new calcium silicate-based endodontic sealer, compared with a resin epoxy-based sealer after 2 different times of cementation on the pull-out bond strength of glass-fiber–reinforced composite posts cemented with a self-adhesive resin cement (RelyX Unicem).MethodologySixty human maxillary central incisors were decoronated, prepared and obturated with gutta-percha and sealer. Roots were distributed into 5 groups according to the sealer and time of post cementation: (1) AH Plus sealer with immediate post fixation, (2) BC HiFlow with immediate post fixation, (3) AH Plus and post fixation after 7 days, (4) BC HiFlow and post fixation after 7 days, and (5) fiber post fixation in canals obturated with gutta-percha only (no sealer). After 1 week of post cementation, the pull-out test was performed and the failure mode was examined under a digital microscope. Data were analyzed using ANOVA followed by Tukey's post hoc and t tests (p < .05).ResultsWith immediate post cementation, AH Plus group showed significantly higher pull-out retentive strength than the BC HiFlow and control groups (p = .009 and p < .001, respectively). There was no significant difference between the groups when the posts were cemented 7 days after obturation (p = .726). The time of post cementation had a significant influence on the canals obturated with AH Plus (p = .003). The time did not significantly affect the canals obturated with BC HiFlow (p = .289). The prominent type of failure was mixed mode in all groups.ConclusionBC HiFlow sealer did not affect the pull-out bond strength of glass-fiber–reinforced composite posts cemented with a self-adhesive resin cement immediately after or 7 days after obturation. For immediate post cementation, AH Plus increased the pull-out bond in comparison to BC HiFlow.     

Influence of ultrasound, with and without water spray cooling, on removal of posts cemented with resin or zinc phosphate cements

The efficacy of ultrasound, with and without water spray, was evaluated in vitro on the amount of force necessary to dislodge posts cemented with resin or zinc phosphate. Forty-two samples were divided into six groups: groups 1, 2, and 3, posts cemented with zinc phosphate; groups 4, 5, and 6, posts cemented with resin (Panavia F); groups 1 and 4 (controls), no ultrasound; groups 2 and 5, ultrasound without water spray; and groups 3 and 6, ultrasound with water spray. The Instron testing machine was used. Ultrasound without water spray significantly reduced (71%) the force necessary to displace posts cemented with Panavia F (p < 0.01); however, this value was similar to the efficacy of ultrasound with water spray for posts cemented with zinc phosphate (reduction of 75%). We conclude that cooling with ultrasound interferes with the force necessary for post removal, depending on the type of cement used.     

Microleakage of endodontically treated teeth restored with fiber posts and composite cores after cyclic loading: a confocal microscopic study

STATEMENT OF PROBLEM: The effectiveness of the seal obtained with carbon fiber posts and composite cores is still unclear. Both 3-step dental adhesives and self-etching adhesive primers have been suggested as adhesive systems. PURPOSE: This confocal microscopic study evaluated the microleakage of teeth endodontically treated and restored with fiber posts and composites with 3 adhesive systems. MATERIAL AND METHODS: A total of 72 human mandibular premolars were endodontically treated and divided into 6 groups of 12 teeth each. The first 3 groups were treated with an endodontic sealer containing zinc oxide-eugenol (ZOE) and restored with temporary filling materials containing ZOE. The last 3 groups were treated with ZOE-free materials. Post spaces were prepared in the root canals. The first group treated with ZOE-based materials was restored with fiber posts cemented with zinc phosphate cement and composite cores without adhesive. The other 2 groups of ZOE-treated teeth were restored with fiber posts cemented with All Bond 2 and Panavia 21 dental adhesives, respectively. The last 3 groups were restored with fiber posts cemented with All Bond 2, Panavia 21, and Panavia Fluoro cement, respectively. The teeth were loaded intermittently at 2 cycles per second in a moist environment and, after 300,000 cycles, immersed in a solution of Rhodamine B dye for 48 hours. A confocal microscope was used to observe the teeth. The ratio between the length of the interfaces observed and the length of the dye penetration was evaluated. Two teeth from each group acted as controls and were not subjected to dynamic loads. RESULTS: All resin cement groups leaked significantly less than the group cemented with zinc phosphate cement. No statistically significant difference was found between the microleakage of teeth treated with ZOE-based and non-ZOE-based materials. Teeth restored with All Bond 2 dental adhesive leaked significantly less than those restored with Panavia cement. CONCLUSION: The 3-step dental adhesive (All Bond 2) resulted in a better marginal seal than that obtained with the self-etching primers (Panavia 21 and Panavia F). The use of endodontic sealers and temporary filling materials containing ZOE had no detrimental effect on the marginal seal of carbon fiber post/composite resin core restorations.     

INFLUENCE OF SMEAR LAYER REMOVAL ON THE OBTURATION OF ROOT CANAL RAMIFICATIONS

Objective:

This study evaluated whether smear layer removal has any influence on the filling of the root canal system, by examining the obturation of lateral canals, secondary canals and apical deltas.

Material and Methods:

Eighty maxillary and mandibular canines were randomly divided into two groups, according to their irrigation regimen. Both groups were irrigated with 1% NaOCl during canal shaping, but only the teeth in Group II received a final irrigation with 17% EDTA for smear layer removal. The root canals were obturated with lateral condensation of gutta-percha and the specimens were cleared, allowing for observation under the microscope.

Results:

In Groups I and II, 42.5% and 37.5% of the teeth, respectively, presented at least one filled canal ramification. Although a larger number of obturated ramifications was found in Group I, there were no statistically significant differences between the two groups (p = 0.4957).

Conclusion:

Smear layer removal under the conditions tested in this study did not affect the obturation of root canal ramifications when lateral condensation of gutta-percha was the technique used for root canal filling.