Adhesive Dentistry and Endodontics: Materials, Clinical Strategies and Procedures for Restoration of Access Cavities: A Review

A clinical dilemma: Performing or avoiding root instrumentation in the treatment of the acute phase of endodontic-periodontal lesions? A case report

BACKGROUND

This study presents the diagnois, management, and tissue response to an acute periodontal lesion with deep pocketing affecting a maxillary central incisor in a young patient devoid of caries or a history of periodontitis.

METHODS

Clinical and radiographic examinations facilitated the diagnosis of the pathology as an endoperiodontal lesion (EPL) with root damage, exhibiting supracrestal invasive root resorption. Orthograde endodontic therapy was employed to decontaminate and seal the endodontic space. The resorptive site was treated through the endodontic access, debrided, and sealed. No periodontal therapy (surgical or nonsurgical) was performed. No mechanical instrumentation was performed within the pocketed root surface.

RESULTS

At 6-month and 1-year follow-ups after endodontic therapy the periodontium displayed a physiologically healthy condition without pus or inflammation, exhibiting a circumferential probing depth of 2 mm, and absence of tooth mobility. These favorable outcomes persisted throughout a 4-year follow-up period.

CONCLUSIONS

The spontaneous healing of pocketing and abscess occurred without mechanical root instrumentation following endodontic therapy and treatment of external invasive root resorption in an EPL.

KEY POINTS

Accurate diagnosis and identification of relevant etiologic factors are pivotal for effectively managing endodontic-periodontal lesions. Once a diagnosis is established, the therapy focuses on eliminating the primary cause, followed by a subsequent diagnostic phase after healing. The definitive understanding of the diagnosis and etiology of endodontic-periodontal lesions often becomes clear in retrospect, based on the outcomes of the therapy. When probing acute periodontal lesions, deep probing depths may occur without permanent loss of periodontal attachment. If the acute lesion was not induced by a periodontal cause and if no periodontal etiology arises secondarily, resolving the primary cause of the endoperiodontal lesion can lead to the spontaneous resolution of the pocketing. This results in spontaneous healing of periodontium without the need for intentional periodontal therapy. A clinical dilemma arises when considering periodontal treatment during the acute inflammatory phase of endo-periodontal pathology. It is advisable to refrain from mechanical root instrumentation particularly if a clear periodontal cause is not apparent, to prevent from iatrogenic damage to periodontal fibers and the potential risk of gingival recessions. However, this does not imply avoiding periodontal therapy entirely for every case. Rather, it is recommended to delay the decision on root instrumentation until a new diagnostic phase is conducted following the healing of the endodontic etiology.

Evaluation of Bond Strength of Three Glass Fiber Post-systems Cemented to Large Root Canals

The aim of this study was to evaluate the push-out bond strength and the failure mode of single adjustable posts (SPLENDOR SAP), anatomical posts (AP), or computer-aided design/computer-aided manufacturing (CAD-CAM) posts cemented to flared root canal dentin with self-adhesive dual-cure resin cement. Thirty single-rooted premolars received endodontic treatment with gutta-percha and a calcium hydroxide-based endodontic cement. After 24 hours, the canal spaces were enlarged with burs. The tooth specimens were divided equally into three groups (n=10), according to the glass fiber post (GFP) system: AP-prefabricated GFP (Reforpost #2, Angelus) was relined with composite resin (Filtek Z350 XT, 3M ESPE); SPLENDOR SAP-GFP was used with a glass fiber sleeve to adjust the adaptation (Splendor SAP, Angelus); and CAD-CAM-a resin pattern was obtained and scanned to produce a CAD-CAM GFP (Fiber CAD Lab, Angelus) milled using a subtractive technique. The three GFP systems were cemented with self-adhesive resin cement (Rely X U200, 3M ESPE). The roots were fixed to an acrylic resin plate used to section them into specimens of cervical, middle, and apical thirds. Then, the slices were attached to a universal testing machine to perform the push- out test at a speed of 0.5 mm/min and a load of 50 Kgf. The posttest specimens were examined under a stereoscopic microscope to evaluate the failure mode. The bond strength variable was analyzed using a generalized linear model, following a split-plot design. Failure mode analysis was performed using Fisher exact test. The significance level adopted was 5%. There was no significant difference among the GFP systems or among the thirds, in terms of bond strength (p>0.05), nor was there any significant association between the systems and the failure mode (p>0.05). Most specimens presented mixed or adhesive failure between resin cement and dentin. It was concluded that the bond strength to flared root dentin was not influenced by the GFP system or the root third.

Comparative Evaluation of Different Post Materials on Stress Distribution in Endodontically Treated Teeth Using the Finite Element Analysis Method: A Systematic Review

The aim of this systematic review is to summarize and conclude findings to reveal the stress ranges developed by various post materials by finite element analysis. This, in turn, aids in the selection of better post material clinically. The electronic databases PubMed and Google Scholar were searched in this review by using specific inclusion and exclusion criteria. Among 14586 articles, 22 articles were included in this systematic review, as they satisfied the eligibility criteria. The search covered all articles published from 1997 to December 2021. All records identified were retrieved and imported into the Rayyan bibliographic software, which is a systematic review screening software. Later, data extraction and analysis of 22 articles were done. Twenty-two articles, which were all finite element analysis studies, were included. Among these, 18 studies used maxillary central incisor scanned models, two studies used a maxillary canine model, and the remaining two used the mandibular premolar model for finite element analysis. All these tooth models are restored with post models made of different materials. This systematic review revealed a difference in stress distribution in endodontically treated teeth when using different post materials. Among 22 studies, 15 studies evaluated glass fiber posts and the results showed that they induce less stress on restored endodontically treated teeth when compared to other posts, with maximum stress concentration at the cervical third of the root. Prefabricated posts like stainless steel and Titanium showed more stress on the restored tooth structure with stress concentration at the cervical and apical third of the root. Prefabricated zirconia also showed more stress on the restored tooth with maximum stress concentration at the middle third of the root.

Cleaning and microstructural effects of amyl acetate on pulp chamber dentin impregnated with epoxy resin-based endodontic sealer

OBJECTIVE

To evaluate the cleaning potential of 95% ethanol, acetone, and amyl acetate solutions used solely or in association, to remove epoxy resin-based sealer residues from pulp chamber dentin and their microstructural effects.

MATERIALS AND METHODS

One hundred and eighty bovine incisor specimens were divided into nine groups according to the cleaning protocol: ET (ethanol); AC (acetone); AA (amyl acetate); E1: AA+AC; E2: AA+ET; E3: AC+ET; E4: AA+AC+ET; PC (positive control), and NC (negative control). All groups were impregnated with epoxy resin-sealer, except NC. Ninety specimens were divided into groups (n = 10) for evaluation of persistence of residues and amount of open dentinal tubules by SEM analysis and evaluation of chemical compounds on the dentin surface after cleaning with electron dispersive spectroscopy. The others 90 specimens were submitted to Knoop microhardness evaluation. Persistence of residues data were submitted to the Kruskal Wallis and Dunn tests (α = 0.05). Open dentinal tubules and microhardness data were submitted to one-way ANOVA and Mann Whitney tests (α = 0.05).

RESULTS

AA and E4 protocols showed the lowest persistence of residues. E4 group had the highest incidence of open dentinal tubules. E3 and E4 groups showed no changes in the atomic ratio Ca/P, which was similar to NC group. E4 group did not present W, an element presents in all the other groups. ET and E4 protocols showed the smallest reduction in dentin microhardness.

CONCLUSIONS

The combination of amyl acetate, acetone and ethanol is the most effective and safe protocol to remove epoxy sealer residues on pulp chamber dentin. Moreover, it has the lowest microhardness reduction.

CLINICAL SIGNIFICANCE

The combined use of amyl acetate, acetone, and ethanol enhanced the cleaning of pulp chamber dentin with minimal microstructural damage.

Quantitative Microbial Leakage Evaluation of Restorative Materials with/without Antibacterial Primer as an Intracoronal Barrier: An Ex Vivo Study

AIM

Aim of this research was to assess the microbial leakage of restorative materials with/without antibacterial primer as an intracoronal barrier.

MATERIALS AND METHODS

Fifty-five extracted single-rooted teeth were included in this study. The canals were cleaned, shaped, and obturated with gutta-percha and AH plus sealer at the established working length. After removing 2 mm of coronal gutta-percha, the teeth were incubated for 24 hours. The teeth were divided into groups according to the materials used as intracoronary orifice barriers as follows: • Group I: Clearfil Protect Bond/Clearfil AP-X • Group II: Xeno IV/Clearfil AP-X • Group III: Chemflex (glass ionomer) • Group IV: Positive control (no barrier) • Group V: Negative control (no barrier and inoculated with sterile broth) Sterile 2 chambers bacterial technique was used to assess the microleakage and Enterococcus faecalis was considered as a microbial marker. The percentage of samples leaked, the time taken for leakage, and the number of colony-forming units (CFUs) in the leaked samples were calculated and analyzed statistically.

RESULTS

There was no statistically significant difference found in bacterial penetration among the three investigated materials after 120 days of use as an intracoronal orifice barrier. This study can also infer that the leaked sample from the Clearfil Protect Bond showed the least mean number of CFUs (43 CFUs) followed by Xeno IV (61 CFUs) and glass ionomer cement (GIC) (63 CFUs).

CONCLUSION

This study concluded that all three experimental antibacterial primers performed better as intracoronal barrier. However, Clearfil Protect Bond with an antibacterial primer showed promising results as an intracoronal orifice barrier in reducing the number of bacterial leakages.

CLINICAL SIGNIFICANCE

The significance of intracoronal orifice barriers in the success of endodontic treatment depends on the ability of the materials to prevent microleakage. This helps clinicians to provide successful antibacterial therapy against endodontic anaerobes.

Effect of mechanical cleaning protocols in the fiber post space on the adhesive interface between universal adhesive and root dentin

The aim of this study was to evaluate the effects of cleaning protocols on the presence of residues, open dentinal tubules, and bond strength of a self-etch adhesive plus a dual-cure resin cement to dentin in the fiber-post space. The methods for cleaning utilized were conventional irrigation (CI), rotary brush with continuous rotary movement (RB), and continuous ultrasonic irrigation (CUI). Sixty bovine incisors were used for fiber-post space preparation. Thirty roots were divided into three groups (n = 10) according to the cleaning protocols and submitted to scanning electron microscope to evaluate presence of residues and relative quantity of open dentinal tubules on dentin surface. Similar protocols were performed in the other thirty roots (n = 10) using a self-etching adhesive system (Scotchbond Universal) and a dual-cure resin cement (Relyx Unicem 2). After 6 months cervical, middle, and apical thirds sections of fiber-post space were submitted to push-out testing. To data ANOVA and Tukey's test were employed (α = 5%). RB and CUI showed the lowest presence of residues on dentin surface (p = .015) and the highest bond strength values (p < .001), regardless of the dentin third. CUI presented the highest quantity of open dentinal tubules in middle and apical thirds (p < .001). CI presented the lowest bond strength value of resin cement, regardless of dentin third (p < .001). Mechanical cleaning protocols, such as RB and CUI, presented better surface cleaning capabilities and higher bond strength than CI with dual-cure resin cement employed. The use of a mechanical cleaning protocol seems to cause appropriate condition on the root dentin surface. Mechanical cleaning of root dentin provided greater bond strength of the self-etching system with dual resin cement. Conventional irrigation did not provide adequate root dentin cleaning.

Probing the mineralized tissue-adhesive interface for tensile nature and bond strength

The mechanical performance of the dentin-adhesive interface contributes significantly to the failure of dental composite restorations. Rational material design can lead to enhanced mechanical performance, but this requires accurate characterization of the mechanical behavior at the dentin-adhesive interface. The mechanical performance of the interface is typically characterized using bond strength tests, such as the micro-tensile test. These tests are plagued by multiple limitations including large variations in the test results. The challenges associated with conventional tensile tests limit our ability to unravel the complex relationships that affect mechanical behavior at the dentin-adhesive interface. This study used the diametral compression test to overcome the challenges inherent in conventional bond strength tests. The bovine femur cortical bone tissue was considered as a surrogate material (the mineralized tissue) for human dentin. Two different adhesive formulations, which differed by means of their self-strengthening properties, were studied. The tensile behavior of the mineralized tissue, the adhesive polymer, and the bond strength of the mineralized tissue - adhesive interface was determined using the diametral compression test. The diametral compression test improved the repeatability for both the tensile and bond strength tests. The rate dependent mechanical behavior was observed for both single material and interfacial material systems. The tensile strength and bond strength of the mineralized tissue-adhesive interface was greater for the self-strengthening formulation as compared to the control.

Clinical and Radiographic Outcomes of Immature Teeth Treated with Different Treatment Protocols of Regenerative Endodontic Procedures: A Retrospective Cohort Study

Regenerative endodontic procedure (REP) is a progressive treatment modality for immature permanent teeth with necrotic pulp. The ambiguousness about the predictability of REP outcome in relation to complete disinfection of the root canal system and the occurrence of discoloration still exists. The aim of this retrospective study was to analyze two treatment protocols on clinical success rate, radiographic root development and the occurrence of discoloration. Eighteen patients were treated by a single operator by either treatment protocol according to the American Association of Endodontists (AAEP, n = 9) or a modified protocol (MP, n = 9) with the use of 5% sodium hypochlorite and sandblasting. Patients were followed up after 3, 6, 9, 12, 18 and 24 months and clinical success, radiographic root development and the occurrence of discoloration were assessed. The clinical success of MP was significantly higher in two years follow-up (p = 0.015), but the change in radiographic root area was higher for AAEP (p = 0.017) and the occurrence of discoloration was higher in AAEP (p = 0.029). The use of 5% sodium hypochlorite for a longer period of time leads to a higher success rate. The sandblasting of the access cavity reduces the occurrence of discoloration.

Bioinspired multifunctional adhesive system for next generation bio-additively designed dental restorations

Resin-based composite has overtaken dental amalgam as the most popular material for the repair of lost or damaged tooth structure. In spite of the popularity, the average composite lifetime is about half that of amalgam restorations. The leading cause of composite-restoration failure is decay at the margin where the adhesive is applied. The adhesive is intended to seal the composite/tooth interface, but the adhesive seal to dentin is fragile and readily degraded by acids, enzymes and other oral fluids. The inherent weakness of this material system is attributable to several factors including the lack of antimicrobial properties, remineralization capabilities and durable mechanical performance - elements that are central to the integrity of the adhesive/dentin (a/d) interfacial seal. Our approach to this problem offers a transition from a hybrid to a biohybrid structure. Discrete peptides are tethered to polymers to provide multi-bio-functional adhesive formulations that simultaneously achieve antimicrobial and remineralization properties. The bio-additive materials design combines several functional properties with the goal of providing an adhesive that will serve as a durable barrier to recurrent decay at the composite/tooth interface. This article provides an overview of our multi-faceted approach which uses peptides tethered to polymers and new polymer chemistries to achieve the next generation adhesive system - an adhesive that provides antimicrobial properties, repair of defective dentin and enhanced mechanical performance.

Effect of phytic acid as an endodontic chelator on resin adhesion to sodium hypochlorite-treated dentin

Objectives

Phytic acid (IP6), a naturally occurring agent, has been previously reported as a potential alternative to ethylenediaminetetraacetic acid (EDTA). However, its effect on adhesion to sodium hypochlorite (NaOCl)-treated dentin and its interactions with NaOCl have not been previously reported. Thus, in this study, the effects of IP6 on resin adhesion to NaOCl-treated dentin and the failure mode were investigated and the interactions between the used agents were analyzed.

Materials and Methods

Micro-tensile bond strength (µTBS) testing was performed until failure on dentin treated with either distilled water (control), 5% NaOCl, or 5% NaOCl followed with chelators: 17% EDTA for 1 minute or 1% IP6 for 30 seconds or 1 minute. The failed specimens were assessed under a scanning electron microscope. The reaction of NaOCl with EDTA or IP6 was analyzed in terms of temperature, pH, effervescence, and chlorine odor, and the effects of the resulting mixtures on the color of a stained paper were recorded.

Results

The µTBS values of the control and NaOCl with chelator groups were not significantly different, but were all significantly higher than that of the group treated with NaOCl only. In the failure analysis, a distinctive feature was the presence of resin tags in samples conditioned with IP6 after treatment with NaOCl. The reaction of 1% IP6 with 5% NaOCl was less aggressive than the reaction of the latter with 17% EDTA.

Conclusions

IP6 reversed the adverse effects of NaOCl on resin-dentin adhesion without the chlorine-depleting effect of EDTA.

In Vitro Comparison of Porcelain Fused to Metal Crown Retention after Endodontic Access and Subsequent Restoration: Composite, Amalgam, Amalgam with Composite Veneer, and Fiber Post with Composite

INTRODUCTION

The aim of this study was to evaluate the effect of different access opening restorative materials on crown retention.

METHODS

Thirty-eight extracted molars were mounted in resin and prepared for porcelain fused to metal (PFM) crowns. The crowns were fabricated and cemented with zinc phosphate, and the force to displace it was measured with a tensile-testing machine before and after endodontic access preparations. The endodontic access area, crown preparation axial wall, and preparation surface area were measured for comparison. The crowns were then recemented, and access openings were restored with either amalgam or composite before displacement force was remeasured. The restorative material was removed from each access opening; access area was measured and restored again (amalgam with composite or fiber post with composite) for displacement force to be remeasured. Paired t test was used to compare the means of displacement between groups. One-way analysis of variance was used to compare the mean outcome measure within the groups.

RESULTS

Statistical analyses showed retention after unfilled access was significantly lower than intact crowns. Amalgam, composite, amalgam + composite, and fiber post + composite increased retention beyond the original value. There was no statistical difference among the different restorative protocols. Qualitative results indicate that the restorative material remains in the crown after displacement regardless of the material used to restore the access.

CONCLUSIONS

The results from this study suggest that an endodontic access cavity decreases retention of a PFM crown. However, subsequent restoration with amalgam, composite, amalgam + composite, or post + composite may increase the original retention of the crown.

Endodontic Access Effect on Full Contour Zirconia and Lithium Disilicate Failure Resistance

Objectives:

To evaluate the effect of endodontic access on the failure load resistance of both adhesively and conventionally luted, full-contour monolithic yttria-stabilized zirconium dioxide (Y-TZP) and adhesively luted lithium disilicate (LD) crowns cemented on prepared teeth.

Methods and Materials:

Seventy-two human maxillary molars were prepared per respective guidelines for all-ceramic crowns with one group (n=24) restored with LD and the other (n=48) receiving Y-TZP crowns. Preparations were scanned using computer-aided design/computer-aided milling (CAD/CAM) technology, and milled crowns were sintered following manufacturer recommendations. All LD crowns and half (n=24) of the Y-TZP crowns were adhesively cemented, while the remaining Y-TZP specimens were luted using a conventional glass ionomer cement (GIC). One LD group, one Y-TZP adhesive group, and one GIC-luted group (all n=12) then received endodontic access preparations by a board-certified endodontist: the pulp chambers were restored with a dual-cure, two-step, self-etch adhesive and a dual-cure resin composite core material. The access preparations were restored using a nano-hybrid resin composite after appropriate ceramic margin surface preparation. After 24 hours, all specimens were loaded axially until failure; mean failure loads were analyzed using Mann-Whitney U test (α=0.05)

Results:

Endodontic access did not significantly reduce the failure load of adhesively luted LD or Y-TZP crowns, but Y-TZP crowns with GIC cementation demonstrated significantly less failure load.

Conclusions:

These initial findings suggest that endodontic access preparation may not significantly affect failure load resistance of adhesively luted Y-TZP and LD crowns. Definitive recommendations cannot be proposed until fatigue testing and coronal seal evaluations have been accomplished.

Effect of Repairing Endodontic Access Cavities on Survival of Single Crowns and Retainer Restorations

INTRODUCTION

This retrospective study aimed to analyze the effect of repairing endodontic access cavities with composite on the survival of single crowns and retainer restorations of fixed or removable dental prostheses.

METHODS

Dental records of patients attending a university dental clinic were retrospectively screened for single crowns and retainer restorations receiving endodontic treatment after crown placement. Survival (no further intervention) and failure (removal, loss or replacement of crown, replacement of access restoration, or recementation of restoration) of crowns and retainers with repaired endodontic access cavities were recorded. The mean annual failure rates were calculated, and the effect of individual-, tooth-, and restoration-related variables on survival was assessed by univariate log-rank tests and multivariate Cox regression analyses with shared frailty (P < .05).

RESULTS

One hundred eighty repaired crowns/retainers placed in 151 patients were included (4.5 ± 3.3 years follow-up). Survival after 2, 5, 7, and 10 years amounted to 82.7%, 71.5%, 67.3%, and 48.8% (mean annual failure rate = 9.0%, 6.5%, 5.5%, and 6.9%), respectively. Although tooth type, kind of restoration, endodontic irrigant, repair conditioning methods, and kind of composite affected survival in the univariate regression analyses, only the kind of restoration (single crown vs retainer restoration) remained significant in the multivariate Cox regression model.

CONCLUSIONS

Repairing endodontic access cavities with composite increases the longevity of single crowns and retainer restorations.

The effect of an intraorifice barrier and base under coronal restorations on the healing of apical periodontitis: a randomized controlled trial

AIM

To evaluate the effect of intraorifice barriers and bases on the healing of apical periodontitis following root canal treatment in mandibular molars.

METHODOLOGY

A total of 120 permanent mandibular molars with necrotic pulps and periapical radiolucencies (PAI score ≥ 3) were recruited. Root canal treatment was performed in all teeth using a standard protocol, following which they were randomly allocated to one of the three treatment groups: intraorifice barrier group: coronal 3-mm gutta-percha was removed and replaced with glass-ionomer cement (GIC) barrier. The floor of the pulp chamber was then sealed with 2-mm-thick GIC base followed by final composite resin restoration; base group: received 2-mm-thick GIC base before placement of composite resin restoration; and control group: had pulp chamber entirely filled with composite resin only. Follow-up was done at 3, 6, 9 and 12 months. Combination of clinical and radiographic parameters were used to assess treatment outcome. The data were analysed using Kruskal-Wallis, chi-square and Wilcoxon signed-rank tests and logistic regression analysis.

RESULTS

At the end of 12 months, the base group had the most favourable healing (97.1%), whilst the control group had the least favourable healing (83.8%). The intraorifice barrier group had healing of 92.1%. However, there was no significant difference in healing between groups at the end of the follow-up period (P > 0.05). Additional subgroup analysis revealed a nonsignificant effect of periodontal status and root filling level on periapical healing.

CONCLUSION

The use of an additional barrier under permanent restorations did not significantly improve the outcome of primary root canal treatment in posterior teeth after 12 months. However, its influence in the long term requires further evaluation.

Performance of Monolithic and Veneered Zirconia Crowns After Endodontic Treatment and Different Repair Strategies

Objectives:

To investigate failure loads of monolithic and veneered all-ceramic crowns after root canal treatment and to analyze marginal integrity of repair fillings.

Methods and Materials:

Seventy-two human molars were restored with monolithic (Zr-All) or veneered (Zr-Ven) zirconia crowns. Molars were assigned to six groups (n=12 per group) depending on restoration material, access type (no access cavity [control] or endodontic treatment [test]), and type of filling (one-step [1-st] or two-step [2-st]). For type of filling, molars were treated using a self-etch universal adhesive and cavities were either filled with layered composite (1-st) or filled until the crown material was reached, which was additionally conditioned and then filled (2-st). Scanning electron microscopic analysis of the restoration margins was performed before and after thermomechanical loading (TML), and the percentage of continuous margins was assessed. Crowns were then loaded to failure.

Results:

Preparation of the access cavity required more time in monolithic (445 s) than in veneered crowns (342 s). Loads to failure were higher in control groups (Zr-All: 5814 N; Zr-Ven: 2133 N) and higher in monolithic test (2985 N) than in veneered test crowns (889 N). In monolithic crowns, 1-st had lower fracture loads than 2-st fillings (2149 N vs 3821 N). Continuous margins of 66% to 71% were achieved, which deteriorated after TML by 39% to 40% in Zr-All, by 34% in Zr-Ven-1-st, and by 24% in Zr-Ven-2-st.

Conclusions:

Endodontic access and adhesive restorations resulted in reduced fracture load in monolithic and veneered zirconia crowns. Two-step fillings provided higher fracture loads in Zr-All and better marginal quality in Zr-Ven crowns.

Bacterial microleakage of temporary filling materials used for endodontic access cavity sealing

Background/purpose

Providing a tight coronal seal is key for the success of endodontic treatment, therefore the study aimed to assess bacterial microleakage of materials used for short- and long-term temporization.

Materials and methods

One hundred and twenty-eight human upper-third molars were divided into six experimental groups (n = 20) and two control groups: negative (n = 4) and positive (n = 4). The standardized access cavities were prepared and filled with: (1) Cavit; (2) Fuji II LC; (3) Fuji IX; (4) Voco Clip; (5) AdheSE and Tetric EvoCeram; (6) Excite and Tetric EvoCeram. The crown of each tooth was sectioned to obtain 5.5-mm-high disks, which were assembled in a standard setup for bacterial microleakage studies using Streptococcus mutans. The monitoring lasted 90 days. Kaplan-Meier survival analysis was performed.

Results

The lowest amount of leaking samples was found in AdheSE and Tetric EvoCeram (31.3%), Cavit (33.3%), and Excite and Tetric EvoCeram groups (35.3%), followed by Fuji II LC (66.7%), Voco Clip (83.3%). and Fuji IX (88.2%) groups. According to the day of microleakage, materials could be classified in three groups with statistically significant differences (P < 0.05). In the first group were Cavit (70 days), AdheSE and Tetric EvoCeram (68 days), and Excite and Tetric EvoCeram (65 days), in the second group were Voco Clip (44 days) and Fuji II LC (43 days), and in the third group was Fuji IX (21 days).

Conclusion

None of the tested materials were able to completely prevent bacterial microleakage. Adhesively bonded composites and Cavit offer better sealing compared with glass ionomer cements, resin modified glass ionomer cements, and composites without the use of an adhesive system.

Effect of different gutta-percha solvents on the microtensile bond strength of various adhesive systems to pulp chamber dentin

OBJECTIVES

The aim of this study was to evaluate the effect of different endodontic solvents on the microtensile bond strength (μTBS) of various adhesives to pulp chamber dentin.

MATERIAL AND METHODS

A total of 120 human third molars were selected. Canals were prepared with the ProTaper Universal system and obturated. The access cavities were then restored with resin composite. After 1 week, a retreatment procedure was applied as follows: control, no solvent was applied to the pulp chamber and experimental groups, three different solvents (chloroform, eucalyptol, and orange oil) were applied to the pulp chamber for 2 min. The canal filling was removed and calcium hydroxide (Ca[OH]₂) was placed into the canals. After 7 days, the Ca(OH)₂ was removed from the canals and the canals were re-obturated. Teeth were then divided into three subgroups according to the adhesive used. The samples were restored with a nanohybrid resin composite using three different adhesives: Clearfil SE Bond (CSE), Adper Easy One (AEO), and Single Bond 2 (SB2). The samples were aged with thermocycling. Teeth were sectioned, and a total of 20 dentin sticks were obtained for each subgroup. μTBS testing was then performed. The debonded surfaces were evaluated using scanning electron microscopy (SEM) analysis. Data were analyzed using two-way ANOVA and Tukey's post hoc tests.

RESULTS

Chloroform showed statistically lower mean μTBS values (14 ± 7.2 MPa) than control group did (19.2 ± 6.1 MPa) (p < 0.05). Orange oil (18.1 ± 6.3 MPa) and eucalyptol (16.9 ± 6.8 MPa) did not reduce the mean μTBS statistically (p > 0.05). Chloroform showed significantly lower bond strength for all adhesives (p < 0.05). Whereas orange oil did not reduce the mean μTBS values of all adhesive systems significantly (p > 0.05), eucalyptol reduced the μTBS values of all the groups, but the results were only statistically significant for SB2 (p < 0.05). CSE showed statistically higher bond strength (20.4 ± 6.8 MPa) than AEO (14.6 ± 5.3 MPa) and SB2 (16.3 ± 7.2 MPa) did (p < 0.05). There were no statistical differences between AEO and SB2 (p > 0.05). According to the SEM analysis of the debonded surfaces, adhesive failures were the most common type in all the groups, followed by mixed failures.

CONCLUSIONS

While chloroform reduced the mean bond strength of the adhesive resins, orange oil did not affect the bond strength of the adhesives. The effect of eucalyptol on bond strength depended on the type of adhesive system.

CLINICAL RELEVANCE

This study shows that endodontic solvents could affect the microtensile bond strength of adhesives to pulp chamber dentin.

Push-out bond strength and dentinal tubule penetration of different root canal sealers used with coated core materials

Objectives

The aim of this study was to compare the push-out bond strength and dentinal tubule penetration of root canal sealers used with coated core materials and conventional gutta-percha.

Materials and Methods

A total of 72 single-rooted human mandibular incisors were instrumented with NiTi rotary files with irrigation of 2.5% NaOCl. The smear layer was removed with 17% ethylenediaminetetraacetic acid (EDTA). Specimens were assigned into four groups according to the obturation system: Group 1, EndoRez (Ultradent Product Inc.); Group 2, Activ GP (Brasseler); Group 3, SmartSeal (DFRP Ltd. Villa Farm); Group 4, AH 26 (Dentsply de Trey)/gutta-percha (GP). For push-out bond strength measurement, two horizontal slices were obtained from each specimen (n = 20). To compare dentinal tubule penetration, remaining 32 roots assigned to 4 groups as above were obturated with 0.1% Rhodamine B labeled sealers. One horizontal slice was obtained from the middle third of each specimen (n = 8) and scanned under confocal laser scanning electron microscope. Tubule penetration area, depth, and percentage were measured. Kruskall-Wallis test was used for statistical analysis.

Results

EndoRez showed significantly lower push-out bond strength than the others (p < 0.05). No significant difference was found amongst the groups in terms of percentage of sealer penetration. SmartSeal showed the least penetration than the others (p < 0.05).

Conclusions

The bond strength and sealer penetration of resin-and glass ionomer-based sealers used with coated core was not superior to resin-based sealer used with conventional GP. Dentinal tubule penetration has limited effect on bond strength. The use of conventional GP with sealer seems to be sufficient in terms of push-out bond strength.

Análise comparativa da resistência de união de um cimento convencional e um cimento autoadesivo após diferentes tratamentos na superfície de pinos de fibra de vidro

Resumo Introdução Os pinos de fibra de vidro são uma alternativa aos núcleos metálicos e apresentam vantagens, tais como: estética, módulo de elasticidade semelhante à dentina e cimentação imediata após o término do tratamento endodôntico. Ainda, apresentam a capacidade de aderir ao cimento resinoso e este, à dentina, por meio de técnicas adesivas. Objetivo Comparar a adesão de um cimento resinoso convencional e um autoadesivo a pinos de fibra de vidro, e os efeitos de diferentes tratamentos de superfície na resistência adesiva dos pinos. Material e método Trinta pinos foram divididos em três grupos: Controle: sem tratamento na superfície; Jateamento: jateamento com óxido de alumínio por 30 segundos, e Peróxido: imersão em peróxido de hidrogênio 24% por um minuto. Em seguida, corpos de prova foram obtidos a partir de cilindros de cimento resinoso contendo o pino de fibra posicionado no centro de seu longo eixo. Em cada grupo, cinco pinos foram associados ao adesivo Âmbar + cimento convencional AllCem Core e os outros cinco pinos, ao cimento autoadesivo RelyX U200. O conjunto pino/cimento foi segmentado e avaliado em relação à resistência de união (RU) por push-out. Os dados foram analisados estatisticamente pelos testes de ANOVA e Tukey (p<0,05). Resultado Os cimentos avaliados exibiram valores de RU semelhantes. Em relação aos tratamentos de superfície, os maiores valores de RU foram encontrados no grupo Jateamento. Conclusão O cimento convencional, AllCem Core, e o cimento autoadesivo, RelyX U200, mostraram valores de resistência de união semelhantes. Ainda, o jateamento com óxido de alumínio favoreceu a adesão dos pinos aos cimentos.

Polytetrafluoroetylene tape as temporary restorative material: a fluid filtration study

Purpose:

The purpose of this study was to compare the sealing ability of temporary restorative materials at 24 hrs and 1 week.

Materials and Methods:

Endodontic access cavities were prepared in 56 extracted lower incisor-teeth and divided into 5 groups (n=10). Standard 5 mm deep access preparations were completed and root canals were prepared to size ISO #30 file. The access cavities were restored as follows: Group 1: temporary restorative material (Ceivitron); Group 2: glass ionomer cement (Fuji II); Group 3: zinc oxide-eugenol cement (IRM); Group 4: zinc phosphate cement (Adhesor); Group 5: polytetrafluoroetylene tape (PTFE). The quality of the coronal sealing of each specimen was measured (24 hrs and 1 week) using fluid transport model. The data was analyzed with repeated measurements ANOVA, Tukey' HSD and Paired samples T-Tests.

Results:

A significant difference was found among the groups at all time-periods (p<0.05). At 24 hrs, PTFE showed similar leakage with Ceivitron, IRM, and Fuji II but it showed higher leakage than Adhesor. At 1 week, Ceivitron showed higher leakage than PTFE, meanwhile PTFE showed similar leakage with IRM, Fuji II, and Adhesor (p>0.05). Sealing ability of IRM and PTFE groups significantly increased by time (p<0.05 and p<0.001 respectively).

Conclusion:

Within the limitations of this study, PTFE showed an acceptable short-term sealing capability when compared to the other commonly used temporary restorative materials at 1 week measurements.

Effects of endodontic tri-antibiotic paste on bond strengths of dentin adhesives to coronal dentin

Objectives

The aim of this study was to evaluate the effects of tri-antibiotic paste (TAP) on microtensile bond strengths (MTBS) of dental adhesives to dentin.

Materials and Methods

Sixty extracted molars had their occlusal surfaces flattened to expose dentin. They were divided into two groups, i.e., control group with no dentin treatment and experimental group with dentin treatment with TAP. After 10 days, specimens were bonded using self-etch (Filtek P90 adhesive) or etch-and-rinse (Adper Single Bond Plus) adhesives and restored with composite resin. Teeth were sectioned into beams, and the specimens were subjected to MTBS test. Data were analyzed using two-way ANOVA and post hoc Tukey tests.

Results

There was a statistically significant interaction between dentin treatment and adhesive on MTBS to coronal dentin (p = 0.003). Despite a trend towards worse MTBS being noticed in the experimental groups, TAP application showed no significant effect on MTBS (p = 0.064).

Conclusions

The etch-and-rinse adhesive Adper Single Bond Plus presented higher mean bond strengths than the self-etch adhesive Filtek P90, irrespective of the group. The superior bond performance for Adper Single Bond when compared to Filtek P90 adhesive was confirmed by a fewer number of adhesive failures. The influence of TAP in bond strength is insignificant.

Intraorifice sealing ability of different materials in endodontically treated teeth: An in vitro study

Background:

Microbial contamination of the pulp space is one of the major factors associated with endodontic failure. Thus, in addition to a three dimentional apical filling a coronal seal for root canal fillings has been recommended.

Aim:

The present study was conducted to evaluate and compare the intra-orifice sealing ability of three experimental materials after obturation of the root canal system.

Materials and Methods:

Fourty single rooted mandibular premolars were decoronated, cleaned, shaped and obturated. Gutta-percha was removed to the depth of 3.5 mm from the orifice with a heated plugger. Ten specimens each were sealed with Light Cure Glass Ionomer Cement (LCGIC), Flowable Composite (Tetric N-Flow), and Light Cure Glass Ionomer Cement with Flowable Composite in Sandwich Technique along with a positive control respectively and roots submerged in Rhodamine-B dye in vacuum for one week. Specimens were longitudinally sectioned and leakage measured using a 10X stereomicroscope and graded for depth of leakage.

Results:

According to the results of the present study LC GIC + Tetric N Flow demonstrated significantly better seal (P < 0.01) than LC GIC. However there was no statistically significant difference in leakage (P > 0.01) between Tetric N-Flow and LCGIC+Tetric N-Flow groups.

Conclusion:

In the current study LCGIC+Tetric N-Flow was found to be superior over other experimental materials as intra-orifice barriers.

Immediate shear bond strength of resin cements to sodium hypochlorite-treated dentin

INTRODUCTION

The purpose of this in vitro study was to evaluate the immediate shear bond strength of different categories of resin cements on sodium hypochlorite (NaOCl)-treated dentin and to evaluate if the bond was improved by a subsequent treatment with 10% sodium ascorbate before adhesive procedures.

METHODS

This study tested immediate shear bond strengths to human dentin of 5 resin cements: Variolink II (Ivoclar Vivadent, Schaan, Liechtenstein), Multilink (Ivoclar Vivadent), Clearfil Esthetic Cement EX (Kuraray, Tokyo, Japan), SpeedCEM (Ivoclar Vivadent), and Clearfil SA Cement (Kuraray). All cements were tested with no NaOCl pretreatment of the dentin (negative control) and with a 20-minute exposure of the dentin to 6% NaOCl before bonding procedures. The cements found to have decreased bond strengths to NaOCl-treated dentin were tested with the dentin exposed to 10% sodium ascorbate after NaOCl exposure. The sodium ascorbate exposure times tested were 5 seconds and 1 minute.

RESULTS

The mean and standard deviation values for immediate shear bond strength (MPa) for the negative control group were as follows: Variolink II, 18.8 ± 4.2; Multilink, 29.1 ± 7.1; Clearfil Esthetic Cement EX, 20.7 ± 4.9; SpeedCEM, 17.8 ± 4.2; and Clearfil SA Cement, 7.2 ± 2.8. The results for the NaOCl exposure group were as follows: Variolink II, 24.0 ± 6.7; Multilink, 34.1 ± 6.1; Clearfil Esthetic Cement EX, 20.7 ± 6.8; SpeedCEM, 0.0 ± 0.0; and Clearfil SA Cement, 0.1 ± 0.1. The results for the 5-second sodium ascorbate group were the following: SpeedCEM, 8.5 ± 2.6, and Clearfil SA Cement, 4.3 ± 2.0. The following results were found for the 1-minute sodium ascorbate group: SpeedCEM, 12.2 ± 3.2, and Clearfil SA Cement, 4.8 ± 1.0.

CONCLUSIONS

The resin cements tested varied in their capacity to adhere to NaOCl-treated dentin. Some resin cements exhibited equal or improved bond strengths (P < .05), whereas others exhibited significantly decreased bond strengths (P < .05). For the susceptible resin cements, a rinse of 10% sodium ascorbate provided an immediate restoration of at least 50% of the original bond strength (P < .05). The efficacy of sodium ascorbate may vary among resin cements.

Four-year Survival of Endodontically Treated Premolars Restored with Fiber Posts

The objective of this prospective clinical trial was to investigate the influence of the residual coronal structure of endodontically treated teeth and the type of cement used for luting fiber posts on four-year clinical survival. Two groups (n = 60) were defined, depending on the amount of residual coronal dentin after abutment build-up and final preparation: (1) more than 50% of coronal residual structure; and (2) equal to or less than 50% of coronal residual structure. Within each group, teeth were randomly divided into 2 subgroups (n = 30) according to the material used for luting fiber posts: (A) resin core build-up material, Gradia Core; or (B) self-adhesive universal cement GCem Automix. The rate of success was assessed based on clinical and intra-oral radiographic examinations at the follow-up after 6, 12, 24, 36, and 48 months. The highest 48-month success and survival rates were recorded in group 1A (90% and 100%, respectively), whereas teeth in group 2B exhibited the lowest performance (63.3% success rate, 86.6% survival rate). Cox regression analysis revealed that neither the amount of coronal residual structure nor the luting material significantly influenced the failure risk (p > .05) (ClinicalTrials.gov, NCT01532947).

Synthesis and evaluation of novel dental monomer with branched carboxyl acid group

To enhance the water miscibility and increase the mechanical properties of dentin adhesives, a new glycerol-based monomer with vinyl and carboxylic acid, 4-((1,3-bis(methacryloyloxy)propan-2-yl)oxy)-2-methylene-4-oxobutanoic acid (BMPMOB), was synthesized and characterized. Dentin adhesive formulations containing 2-hydroxyethyl methacrylate (HEMA), 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy) phenyl]propane (BisGMA), and BMPMOB were characterized with regard to real-time photopolymerization behavior, water sorption, dynamic mechanical analysis, and microscale three-dimensional internal morphologies and compared with HEMA/BisGMA controls. The experimental adhesive copolymers showed higher glass transition temperature and rubbery moduli, as well as improved water miscibility compared to the controls. The enhanced properties of the adhesive copolymers indicated that BMPMOB is a promising comonomer for dental restorative materials.

Effect of chlorhexidine and ethanol-wet bonding with a hydrophobic adhesive to intraradicular dentine

PURPOSE

To evaluate the effect of adjunctive application of ethanol-wet bonding and chlorhexidine (CHX) with a hydrophobic adhesive on bond durability of fibre posts to intraradicular dentine.

METHODS

Ninety-six extracted human teeth with a single root and root canal were prepared for post placement after endodontic treatment. The teeth were randomly divided into four groups (n=24) after etching and rinsing for rewetting: Group 1: water-wet bonding, Group 2: water-wet bonding with CHX, Group 3: ethanol-wet bonding and Group 4: ethanol-wet bonding with CHX. Teeth in Groups 1 and 2 were treated with either distilled water or distilled water with 2% CHX for 60 s; while teeth in Groups 3 and 4 were treated with either 100% ethanol or 100% ethanol with 2% CHX. Two coats of primer, followed by neat resin were applied and light-cured for 40 s. Fibre posts were luted to bonded root dentine using dual-cure resin cement. Bonded roots were subjected to push-out bond strength testing and interfacial nanoleakage evaluation after 24 h, 6 and 12 months of storage. Data were analyzed using 3-way ANOVA (rewetting solutions, time and post space regions) and SNK tests.

RESULTS

Groups 3 and 4 showed significantly (p<0.05) higher bond strengths and lower nanoleakage than Groups 1 and 2 after 12 months of ageing. Addition of 2% chlorhexidine to ethanol-wet bonding with a hydrophobic adhesive did not further improve the bonding of a fibre post to intraradicular dentine, when compared to ethanol-wet bonding alone after 12 months of ageing.

CLINICAL SIGNIFICANCE

Ethanol-wet bonding with a hydrophobic adhesive alone could improve the bond durability of fibre post to intraradicular dentine and therefore would increase the success rate of post and core restorations of endodontically treated teeth.

Effect of endodontic irrigation and dressing procedures on the shear bond strength of composite to coronal dentin

This study aimed to evaluate the effects of three sodium hypochlorite (NaOCl)-endodontic irrigation procedures used alone or in combinations with two intermediate dressing materials on bond strengths of two adhesive composite systems to coronal dentin. Surfaces were treated with NaOCl or NaOCl–Glyde-File-Prep (H₂O₂ and EDTA) with or without chlorhexidine (CHX) as a final rinse. Intermediate dressing materials of calcium hydroxide (Ca(OH)₂) and sodium perborate (SP) were combined with surface treatments. Surface treatment groups (n = 10/group) included (1) distilled water (control), (2) 5.25% NaOCl (30 min), (3) NaOCl/Glyde (30 min), (4) NaOCl/Glyde (30 min) + CHX (2 min), (5) NaOCl/Glyde (30 min) + Ca(OH)₂ (5 days) + CHX (2 min), and (6) NaOCl/Glyde (30 min) + SP (9 days) + CHX (2 min). For each surface treatment group, dentin shear bond strengths of two different composite systems (Excite/Tetric Flow Chroma, [EX/TFC], and Clearfil Protect Bond/Protect Liner F [PB/PLF]) were evaluated. Median shear bond strengths (EX/TFC, PB/PLF) for each surface treatment group in MPa were (1) 21, 18; (2) 26, 18; (3) 21, 17; (4) 22, 16; (5) 17, 11; and (6) 14, 11, respectively. NaOCl significantly increased the bond strength of EX/TFC (p < 0.05), but did not significantly affect that of PB/PLF. The use of NaOCl/Glyde with CHX did not significantly affect EX/TFC (p > 0.05), whereas it significantly decreased PB/PLF (p < 0.05). Ca(OH)₂ and SP significantly decreased the bond strengths of both adhesive systems (p < 0.05). Adhesion to coronal dentin is dependent upon the irrigation regimen and the type of adhesive.

Sealing ability of various restorative materials as coronal barriers between endodontic appointments

AIM

To evaluate and compare the microleakage of various restorative materials used as coronal barriers between endodontic appointments.

MATERIALS AND METHODS

Eighty extracted human permanent posterior teeth were prepared for standardized access cavities with dimensions of 4 × 4 × 4 mm. The teeth were then randomly divided into four groups; Kalzinol, Caviton, GC Fuji IX and GC Fuji II LC. After incubation, the samples were immersed in 2% methylene blue for 7 days. The depth of penetration was measured using a digital macroscope after longitudinal sectioning of each tooth. Kruskal-Wallis (p < 0.05) and multiple Mann-Whitney test with Bonferroni correction (p < 0.008) were used for data analysis.

RESULTS

The degree of microleakage varied at the material/ tooth interface among the test materials, and the difference was statistically significant (p < 0.05). GC Fuji II LC group showed the least median microleakage value (0.8105 ± 0.305), followed by Caviton (1.1885 ± 0.396), GC Fuji IX (3.3985 ± 0.305) and Kalzinol (4.161 ± 0.853).

CONCLUSION

Within the limitations of this study, GC Fuji II LC exhibited the best marginal seal, and has the potential to be used as a suitable coronal barrier between endodontic appointments.

CLINICAL SIGNIFICANCE

Given the prime importance that dental practitioners should thoroughly restore any tooth with a suitable coronal barrier between endodontic appointments, this study shows that Fuji II LC has the ability to maintain a hermetic seal for 7 days.

Microbial biofilm proliferation within sealer-root dentin interfaces is affected by sealer type and aging period

INTRODUCTION

Root canal fillings are intended to prevent microbial proliferation over time in the canal after treatment. The objective of this study was to assess biofilm proliferation within the sealer-dentin interfaces of 2 methacrylate resin-based systems, self-etch (SE) and total-etch (TE), and an epoxy resin-based sealer (EP), aged for up to 6 months.

METHODS

Standardized specimens (n = 45) comprising the coronal 5 mm of human roots were filled with the test materials and gutta-percha. Specimens were either not preincubated (control, n = 9) or were incubated in sterile saline for 1 week, 1 month, 3 months, or 6 months (n = 3/group). Monospecies biofilms of Enterococcus faecalis were grown on the specimens for 7 days in a chemostat-based biofilm fermentor mimicking pathogenic oral conditions. The extent of E. faecalis proliferation within the sealer-dentin interface for each material and incubation period group was assessed by using fluorescence microscopy of dihydroethidium-stained specimens.

RESULTS

TE had less biofilm proliferation than both EP and SE (P < .01). Deeper biofilm proliferation was detected in SE and EP specimens aged for 1 and 3 months than those aged for 1 week or 6 months (P < .05). Maximum depth of biofilm penetration was recorded for SE at 1 month (P < .05).

CONCLUSIONS

Within the test model used, the SE and EP sealers were more susceptible to interfacial biofilm proliferation than the TE restorative material. This susceptibility diminished after aging the materials' interfaces for 6 months.

Persistence of endodontic methacrylate-based cement residues on dentin adhesive surface treated with different chemical removal protocols

The aim of this study was to evaluate the persistence of methacrylate-based cement residues on the dentin, after dentin surface cleaning with ethanol or acetone, with or without previous application of a dentin adhesive. Forty bovine crown fragments were obtained and the dentin surface was washed with 1.0 mL of 2.5% sodium hypochlorite (NaOCl), followed by 0.1 mL of 17% ethylenediaminetetraacetic acid application for 3 min, and final irrigation with 2.5% NaOCl. The specimens were air dried and resin-based cement was rubbed onto the dentine surface with a microbrush applicator. In 20 specimens, previously to cement, a dentin adhesive was applied in all surfaces. After 15 min, the surface was scrubbed with a cotton pellet and moistened with ethanol or acetone, compounding the following groups: G1-99.5% ethanol and G2-acetone, without previous use of dentin adhesive; G3-99.5% ethanol and G4-acetone, with previous use of dentin adhesive. The dentin surface was scrubbed until the cement residues could not be visually detected. Sections were then processed for scanning electron microscopy and evaluated at 500× magnification and scores were attributed to each image according to the area covered by residual sealer, and data were subjected to Kruskal-Wallis at 5% significance. The lower residue presence was observed in G3 (P = 0.005). All surface presented cement residues when acetone was used as cleaning solution (P = 0.0005). The cleaning solutions were unable to completely remove the cement residues from both surfaces. The ethanol used after previous application of the dentin adhesive promoted the lower presence of residues.

Push-out strength of root fillings with or without thermomechanical compaction

AIM

To evaluate the influence of thermomechanical compaction (Tagger's hybrid technique - THT) on the push-out strength of several root filling materials to root dentine.

METHODOLOGY

Root canals of eighty roots in human canines were prepared with the ProTaper system and filled with one of the following materials, using either lateral compaction (LC) (n = 40) or THT (n = 40): AH Plus/gutta-percha (GP) (n = 10), Sealer 26/GP (n = 10), Epiphany SE/Resilon (n = 10) and Epiphany SE/GP (n = 10). Three 2-mm-thick dentine slices were obtained from each third of each root. The root filling in the first slice was subjected to a push-out test to evaluate the bond strength of the materials to intraradicular dentine. Data (in MPa) were analysed using anova and post hoc Tukey's test (P < 0.05). Failure mode was determined at × 25 magnification. The other two slices were prepared for scanning electron microscopy (SEM) to examine the surface of the filling materials.

RESULTS

Lateral compaction (1.34 ± 1.14 MPa) was associated with a significantly higher bond strength (P < 0.05) than the THT (0.97 ± 0.88 MPa). AH Plus/GP (2.23 ± 0.83 MPa) and Sealer 26/GP (1.86 ± 0.50 MPa) had significantly higher bond strengths than the other materials and differed significantly from each other (P < 0.05). There was a significant difference (P < 0.05) between the coronal (1.36 ± 1.15 MPa), middle (1.14 ± 1.05 MPa) and apical thirds (0.95 ± 0.83 MPa). Considering the technique and root filling material interaction, AH Plus/GP-LC was associated with the highest mean values (2.65 ± 0.66 MPa) (P < 0.05). Sealer 26/GP-LC (2.10 ± 0.46 MPa), AH Plus/GP-THT (1.81 ± 0.78 MPa) and Sealer 26/GP-TH (1.63 ± 0.44 MPa) had intermediate values that were not significantly different from each other (P > 0.05). Epiphany SE was associated with the lowest mean values (3.70 ± 0.86 MPa) (P < 0.05), regardless of the root filling technique and type of solid material (cone). Adhesive failures predominated in the specimens filled with Epiphany SE, whilst mixed and cohesive failures were more frequent in those filled with AH Plus and Sealer 26, regardless of the root filling technique. SEM analysis revealed that LC produced a dense and well-compacted filling whilst the use of a hybrid thermomechanical technique resulted in the solid material (GP or Resilon) intermingled within sealer to form a nonhomogenous mass.

CONCLUSION

Lateral compaction was associated with higher bond strengths of the materials to intraradicular dentine than a hybrid technique using thermomechanical compaction. The greatest push-out strengths were obtained when the canals were filled with LC of AH Plus and GP cones.

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.

Influence of luting material filler content on post cementation

Luting of fiber posts to intra-radicular dentin represents the worst-case scenario in terms of control of polymerization shrinkage. This study tested the hypothesis that filler content of resin cements does not influence luting of fiber posts to intra-radicular dentin, by assaying polymerization stress, push-out bond strength, and nanoleakage expression. The polymerization stress of experimental cements containing 10%, 30%, 50%, or 70% in filler content was investigated. Post spaces were prepared in endodontically treated teeth, and fiber posts were cemented with the experimental cements. A push-out test was performed, and interfacial nanoleakage expression was analyzed. Results showed that luting cements with higher filler content were related to increased polymerization stress (p < 0.05), decreased push-out bond strength (p < 0.05), and increased interfacial nanoleakage expression (p < 0.05). Conversely, lower-stress luting materials increased bonding of fiber posts to intra-radicular dentin. Further in vivo studies are needed to investigate the long-term clinical performance of these materials.

Push-out stress for fibre posts luted using different adhesive strategies

The influence of thermocycling on the bond strength of fibre posts cemented with different luting approaches was investigated. A total of 84 human incisors were selected for the study. Sixty teeth were assigned to one of the following adhesive/cement combinations for push-out bond-strength evaluation: group 1, XP Bond/CoreXFlow + DT Light-Post; group 2, Panavia F 2.0 + Tech 21; or group 3, RelyX Unicem + RelyX. Bonded specimens were cut into 1-mm-thick slabs and either thermocycled (40,000 cycles) or stored in artificial saliva (control specimens) before push-out bond-strength testing. Additional specimens were processed for quantitative interfacial nanoleakage analysis. Thermocycling decreased the bond strength in specimens of groups 2 and 3, but did not affect the specimens from group 1. No difference was observed among luting approaches in control specimens. Thermocycling resulted in increased silver nitrate deposition (i.e. interfacial nanoleakage) in all groups. Within the limitations of the study, the use of an etch-and-rinse adhesive in combination with a dual-cure cement to lute fiber posts is the most stable luting procedure if compared with a self-etch resin-based cement or a self-adhesive cement, as assayed by thermocycling of the bonded specimens.

Effect of ethanol application on post-luting to intraradicular dentine

AIM

To examine the effect of the application of an ethanol rinse before luting fibre posts to intraradicular dentine with etch-and-rinse adhesive systems by means of push-out bond strength evaluation and scanning electron microscopic (SEM) analysis.

METHODOLOGY

Fibre posts were luted to single-canal premolars using Dual Link as a luting agent in combination with a three-step (All Bond 2) or a two-step (One Step Plus) etch-and-rinse adhesive system, which were applied as per manufacturers' instructions (control) or with the additional rinse of ethanol on acid-etched dentine prior to the bonding procedures (experimental). Bonded specimens were sectioned into 1-mm-thick slabs and subjected to push-out bond strength testing. In addition, specimens from each group were processed for SEM analysis. Data were analysed by Kruskal-Wallis followed by Dunn's post hoc test at P = 0.05.

RESULTS

Push-out bond strength of All Bond 2 was significantly increased if the adhesive was applied on ethanol-saturated dentine (P < 0.05), whilst no significant difference (P > 0.05) was detected amongst experimental and control groups for One Step Plus. Irrespective of the adhesive, the SEM analysis revealed good impregnation patterns when both bonding techniques were employed.

CONCLUSIONS

The use of the additional ethanol rinse on acid-etched dentine revealed higher bond strength of All Bond 2 when compared with the control application procedure, used in combination with a resin-based cement to lute fibre posts into the dowel space. However, no bond strength improvements were detected using One Step Plus. Further investigations are needed to develop a clinically applicable ethanol/bonding/luting technique.

Evaluation of the adhesion of fiber posts cemented using different adhesive approaches

The aim of this study was to investigate the adhesion of fiber posts cemented with luting agents that utilize three currently available adhesive approaches: etch-and-rinse, self-etch, and self-adhesive. Forty-two intact single-rooted human premolars were used in the study. Teeth were divided into six groups. In each group, a different resin cement with its adhesive system (if needed) and a fiber post were used. The groups were classified, according to the adhesive approach, into the following three categories. (i) Etch-and-rinse groups: Calibra resin cement/XPBond adhesive + self-curing activator (SCA)/RadiX Fiber Post (Dentsply Caulk), FluoroCore 2 core build-up material/XPBond + SCA/RadiX Fiber Post (Dentsply Caulk), and MultiCore Flow luting and core build-up material/Excite DSC adhesive/FRC Postec Plus fiber post (Ivoclar Vivadent). (ii) Self-etch group: Panavia F 2.0/ED primer (Kuraray)/RadiX Fiber Post (Dentsply Caulk). (iii) Self-adhesive groups: experimental self-adhesive cement/RadiX Fiber Post (Dentsply Caulk), and RelyX Unicem/RelyX Fiber Post (3M ESPE). The adhesion between the post and the root canal walls was assessed using the 'thin-slice' push-out test. In the test arrangement used, the self-etching approach may offer less favourable adhesion to root canal dentin in comparison with etch-and-rinse and self-adhesive approaches.