Bacterial microleakage of a bioactive pit &fissure sealant.

PURPOSE: To compare the sealing properties of three pit and fissure (P&F) sealants, Embrace Wet Bond (EWB), a bioactive P&F sealant Embrace Wet Bond through the addition of modified calcium phosphate (MCP) (EWBMCP) and ClinPro (CLPR). The sealing properties of the materials were tested by means of a bacterial microleakage test. METHODS: 30 extracted intact human third molars were randomly assigned to three groups of 10 (n=10) teeth each. The teeth were cleaned with two passes of air abrasion, followed by rinsing for 20 seconds and then dried with compressed air for another 20 seconds leaving the enamel surface slightly moist. The coronal portion of each tooth was sectioned perpendicular to the long axis at the level of 4 mm below the top of the central fossa of the enamel. A parallel vertical channel 1 mm in diameter was prepared in the central fossa through the entire sample. All samples were sterilized with Gamma radiation. After etching the occlusal surface with 35% phosphoric acid gel followed by rinsing, the sealants were applied. The samples were stored at 37°C in SPB for 3 weeks, thermal cycled for 2,000× (5-55°C) and coated with nail varnish leaving 1 mm uncovered around the P&F material. Samples were then tested for microleakage of E. faecalis culture using a dual chamber leakage model. The broth in the lower chamber was checked daily for turbidity up to 90 days. Statistical significance was determined at P< 0.05. RESULTS: The median survival time for EWBMCP was significantly higher (P< 0.05) than for EWB and CLPR. With respect to bacterial microleakage frequency, EWBMCP and CLPR behaved significantly better than EWB. The bioactive sealant EWBMCP outperformed the other two tested sealants in terms of resistance to bacterial microleakage. Long-term clinical studies are recommended to confirm these in vitro findings. CLINICAL SIGNIFICANCE: Long term resistance to bacterial leakage of occlusal pit and fissure sealants will be beneficial to resisting the development of decay. A recently developed bioactive pit & fissure sealant offers that possibility and it is recommended that the findings are confirmed by clinical studies.

Effect of Ferrule Location with Varying Heights on Fracture Resistance and Failure Mode of Restored Endodontically Treated Maxillary Incisors.

PURPOSE: To investigate the effect of the location of a partial ferrule on 2 walls and the influence of ferrule height variations on remaining walls, fracture resistance, and failure mode of maxillary incisors endodontically treated and restored with fiber posts. MATERIALS AND METHODS: Sixty intact human maxillary central incisors were divided into 6 groups (n = 10): no ferrule (NF), 2-mm ferrule (CF2), absence of lingual wall and 1 proximal wall with remaining walls' height, 1 mm (IF1), 2 mm (IF2), 3 mm (IF3), and 4 mm (IF4). They were restored with a fiberglass post and composite resin core. Complete metal crowns were then cemented on all specimens. Completed specimens were subjected to thermal cycling (6000 cycles, 5°C/55°C) followed by the immediate testing of fracture resistance. After failure, the specimens were sectioned buccolingually and evaluated to identify the mode of failure. The data were analyzed with an ANOVA and the Student-Newman-Keuls multiple comparison tests (α = 0.05). RESULTS: An incomplete ferrule (IF2) with the lingual wall missing and 1 proximal wall had a fracture resistance of 494 ± 137 N, which was significantly less that of a complete ferrule (CF2) (707 ± 162 N, p = 0.002). An increase of 3 to 4 mm in height of the remaining walls had negligible influence on the fracture resistance: 514 ± 117 N (IF3), 557 ± 177 N (IF4). Partial decementation was observed in all specimens of IF3 and IF4, in 9 of IF1 and IF2, in 6 in NF, and in 3 in CF2. Root fractures occurred in 7 specimens, 4 in CF2, 1 in IF1, 1 in IF2, and 1 in IF4. Cracks under the cemento-enamel junction occurred in 4 specimens (NF and IF1), in 5 (IF2 and IF3), and in 6 (CF2 and IF4) and were considered catastrophic failures. CONCLUSIONS: Specimens with a complete ferrule of 2 mm height were more resistant to fracture than specimens with 2 mm height and absence of the lingual wall and 1 proximal wall. A 3 or 4 mm wall height increase was associated with an insignificant increase in fracture resistance and cannot compensate for the absence of the lingual wall and 1 proximal wall.

Influence of remaining coronal tooth structure on fracture resistance and failure mode of restored endodontically treated maxillary incisors.

STATEMENT OF PROBLEM: Limited information is available on the effect of an incomplete ferrule because of the varying residual axial wall heights and the volume of residual tooth structure on the fracture resistance of endodontically treated and restored maxillary incisors. PURPOSE: The purpose of this in vitro investigation was to examine the effect of varying residual axial wall heights, residual coronal tooth structure, and the absence of 1 proximal axial wall on the fracture resistance and failure mode of endodontically treated teeth restored with metal posts. MATERIAL AND METHODS: Sixty intact human maxillary central incisors were divided into 6 groups (n=10): no ferrule (NF), 2-mm complete ferrule (CF2), 2-mm (IF2), 3-mm (IF3), and 4-mm (IF4) incomplete ferrules missing a single interproximal wall, and a control group that had a 6-mm incomplete ferrule (IF6). Cast metal post-and-cores were placed in all experimental specimens except for controls. Control specimens received 1 interproximal cavity preparation extending to the root canal access and a composite resin restoration. Complete metal crowns were then cemented on all specimens. Completed specimens were subjected to thermocycling (6000 cycles, 5°C/55°C) followed by the immediate testing of fracture resistance. Failed specimens were sectioned buccolingually and evaluated to identify the failure mode. The data were analyzed with an analysis of variance (ANOVA) and the Student-Newman-Keuls multiple comparison test (α=.05). RESULTS: An incomplete ferrule (IF2) with 1 interproximal wall missing had significantly reduced fracture resistance (697 N) compared with a complete ferrule (932 N). An increase of 3 to 4 mm of remaining wall height improved fracture resistance, from 844 N (IF3) to 853 N (IF4). Partial decementation was noticed in 8 NF and 5 IF2 specimens. IF3 and IF4 had no decementations. Radicular fractures and cracks (catastrophic failure) were observed in all IF2, IF3, and IF4, 9 CF2, and 6 NF specimens. In 7 specimens without posts (IF6, control), composite resin foundation and/or coronal dentin fracture were observed and the failure was considered repairable. CONCLUSIONS: The results of this in vitro study indicated that specimens with a 2-mm ferrule of uniform height were more resistant to fracture than specimens with a 2-mm ferrule and 1 missing interproximal wall. An increased wall height of 3 or 4 mm was associated with a significant increase in fracture resistance and can compensate for the missing interproximal wall.

Flexural strength and flexural fatigue properties of resin-modified glass ionomers.

OBJECTIVE: To determine the physical properties of several resin-modified glass ionomers (RMGIs) by means of flexural strength and flexural fatigue testing, and to compare them to conventional glass ionomer cements (GICs) and flowable composite resins. METHODS: RMGI samples were fabricated according to ISO 4049 standard. Rectangular specimens were produced using a polytetrafluoroethylene (PTFE) mold with dimensions of 2 x 2 x 25 mm. Flexural strength and flexural fatigue were measured by means of the 3-point bending tests using an Instron universal testing machine at 0.75 mm/min and 0.03 Hz for 100 cycles, respectively. Flexural stress, load, and displacement were recorded for all tests. Data were statistically compared (ANOVA, SNK, p < 0.05). Statistical data analysis for flexural fatigue was achieved through the least frequent events method (failures versus non-failures). The following RMGIs, flowable composites, and GICs were tested: 1) Activa Bioactive-Restorative; 2) Activa Bioactive-Base/Liner; 3) Tetric EvoFlow; 4) Beautifil Flow Plus; 5) Geristore; 6) Fuji Filling LC; 7) Fuji Lining LC; 8) Ketac Nano; 9) Fuji Triage; 10) Ketac Nano; and 11) Vitrebond Plus. RESULTS: The flexural strength of Activa-enhanced RMGIs was statistically significantly greater than all other RMGIs and GICs (p < 0.001). The flexural fatigue of Activa-enhanced RMGIs and flowable composites was significantly greater than all other materials (p < 0.00 1). The flexural fatigue of the Activa-enhanced RMGIs was comparable to the two flowable composites tested. CONCLUSION: The Activa-enhanced RMGIs demonstrated comparable flexural strength and flexural fatigue to flowable composites. Activa-enhanced RMGIs and flowable composites demonstrated flexural strength and flexural fatigue significantly greater than all other tested materials.

Resistance against bacterial leakage of four luting agents used for cementation of complete cast crowns.

PURPOSE: To assess the sealing properties of four luting materials used for cementation of full cast crowns. METHODS: 40 human premolars were prepared with a chamfer finish line. Stone dies were fabricated and copings were waxed, invested and cast in gold. Ten samples (n = 10) were randomly assigned to four groups. In two groups, resin modified glass-ionomer cements were used, ACTIVA BioACTIVE-CEMENT/BASE/LINER and FujiCem2; the third group received the self-adhesive resin cement Embrace WetBond, while the fourth group served as control with a zinc phosphate cement. After cementation, excess cement was removed followed by bench-set for 10 minutes. All samples were stored in water at 37 degrees C and subjected to thermal cycling (x2000 between 5 and 55 degrees C). Subsequently the occlusal surface was reduced exposing the dentin. After sterilization the specimens were subjected to bacterial microleakage with E. faecalis in a dual chamber apparatus for a period of 60 days. Bacterial leakage was checked daily. Data were analyzed using the Kaplan-Meyer survival test. Significant pairwise differences were analyzed using the Log Rank test and the Fishers' exact test at P < 0.05. RESULTS: ACTIVA BioACTIVE-CEMENT/BASE/LINER, FujiCem2 and Embrace WetBond showed the lowest microleakage scores and differed statistically significantly (P < 0.05) from zinc phosphate cement.

Prospective observation of a new bioactive luting cement: 2-year follow-up.

PURPOSE: A pilot study was conducted to determine the 2-year clinical performance of a new bioactive dental cement (Ceramir C&B, formerly XeraCem) for permanent cementation. MATERIALS AND METHODS: The cement used in this study is a new formulation class, a hybrid material comprising calcium aluminate and glass ionomer. Thirty-eight crowns and fixed partial denture (FPD) abutments were cemented in 17 patients. Thirty-one of the abutment teeth were vital, 7 nonvital. Six reconstructions were FPDs comprising 14 abutment teeth (12 vital/2 nonvital). A two-unit fixed splint was also included. Preparation parameters and cement characteristics (dispensing, working time, seating characteristics, ease of cement removal) were recorded. Baseline and postcementation data were recorded for marginal integrity, marginal discoloration, secondary caries, retention, and gingival inflammation. Tooth sensitivity was assessed at pre- and postcementation time points using categorical and visual analogue scale (VAS) assessment measures. RESULTS: Mixing of the cement was reported as "easy." Clinical working time for this cement was deemed acceptable. Assessment of seating characteristics indicated all restorations were seated completely after cementation. Cement removal was determined to be "easy." Fifteen of 17 subjects were available for 1-year recall examination; 13 patients were available for the 2-year recall examination. Restorations at 2-year recall examination included 17 single-unit, full-coverage crown restorations, four 3-unit FPDs comprising 8 abutments, and one 2-unit splint. No retentive failures or sensitivity were recorded at 2-year recall. Marginal integrities of all restorations/abutments at 2 years were rated in the "alpha" category. Average VAS score for tooth sensitivity decreased from 7.63 mm at baseline to 0.44 mm at 6-month recall, 0.20 mm at 1-year recall, and 0.00 mm at 2-year recall. The average gingival index score for gingival inflammation decreased from 0.56 at baseline to 0.11 at 6-month recall, then 0.16 at 1-year recall, and 0.21 at 2-year recall. CONCLUSIONS: Two-year recall data yielded no loss of retention, no secondary caries, no marginal discolorations, and no subjective sensitivity. All restorations rated "alpha" for marginal integrity at the 2-year recall. After periodic recalls up to 2 years, the new bioactive cement tested thus far has performed favorably as a luting agent for permanent cementation.

Noninvasive Endodontic Periapical Biopsy of a Periapical Fibrous Scar: Case Report.

Postendodontic periapical fibrous scars (PFScs) comprise a type of radiolucent healing that is frequently misinterpreted as a pathological lesion. A combined clinical, radiologic, and histologic correlation is essential for a reliable diagnosis. This report presents a case of a patient with a long-term persistent asymptomatic postendodontic radiolucency that was misdiagnosed as endodontic failure and referred for endodontic retreatment and periapical surgery. To reach a definitive diagnosis, a core bone biopsy needle (CBBn) technique was performed on the area of the radiolucency. The material obtained was processed for histologic analysis and the lesion was determined to be a PFSc. In conclusion, the use of a CBBn before any invasive treatment allowed the clinician to distinguish between PFSc and other persisting pathosis, such as periapical granuloma or cystic lesions.

Frequency and distribution of teeth requiring endodontic therapy in an Argentine population attending a specialty clinic in endodontics.

OBJECTIVES: To determine the frequency and distribution of 975 teeth in need of endodontic treatment in an Argentine patient pool and to compare the results with previously published surveys. METHODS: Of the 975 teeth from 860 individuals (age range 7-86 years) were endodontically treated during 2007 by postgraduate students enrolled in a specialisation programme in Endodontics. All patients were examined clinically and radiographically. For each case, information was collected in a questionnaire including location of the affected tooth, age and gender and reasons for endodontic treatment. Data were analysed by the Student t-test, the Fisher exact test, and the chi-square test with a significance of P < 0.05. RESULTS: Of the 975 treated teeth, 543 (55.69%) were maxillary and 432 (44.30%) mandibular teeth. 635 (65.13%) were from females and 340 (34.87%) from males. Significant differences were found between the maxillary and mandibular arch (P = 0.01). Molars and premolars required significantly more frequent endodontic treatment than canines and incisors (P < 0.001). The most frequently treated tooth was the mandibular right first molar (9.12%) followed by the mandibular left first molar (7.07%). The most frequently diagnosed pathosis was irreversible pulpitis (36.00%), pulp necrosis (30.80%), apical periodontitis or the presence of easily discernible periapical radiolucent areas (27.20%). Caries (59.18%) and failure of previous endodontic treatment (26.97%) were responsible for most of the affected teeth. CONCLUSIONS: Comparison with previous surveys revealed that more females than males received endodontic treatment and that mostly molars and premolars were in need of endodontic treatment. The high number of root filled teeth requiring retreatment is in agreement with a pattern similar to that observed in other countries and supports the need for more specialists in endodontics in the Republic of Argentina.

Pit and fissure depth in the enamel of mandibular third molars: An open gate for microleakage?

The aim of this descriptive ex vivo study was to evaluate qualitatively the depth of pit and fissures (P&F) of the enamel in human mandibular third molars. Fifty (n=50) extracted human mandibular third molars were cleaned and disinfected. All tooth surfaces were coated with nail varnish except for a 1-mm margin around the periphery of the occlusal surface. The teeth were immersed for 48 hours at 37 °C in 1% methylene blue dye solution prepared in artificial saliva. After cleaning, the crowns were separated from the root at the cementoenamel junction and subsequently sectioned longitudinally in buccolingual direction at the location of the central fossa. All sections were examined using a stereoscopic microscope and photographed. The images were downloaded on a computer. The length of penetration of the P&F was recorded using the following scoring system: C1: P&F extended to half of the enamel thickness; C2: P&F extended beyond half of the enamel thickness without reaching the dentine-enamel junction; C3: P&F extended to the dentine-enamel junction. For pits, C1, C2 and C3 were observed in 35, 9 and 6 teeth, respectively, while for fissures, C1, C2 and C3 were observed in 15, 18 and 17 teeth, respectively. The P&F detected in the samples extended to the deepest portions of enamel, quite frequently reaching the enamel-dentine junction. Clinicians should recognize that even if pits and fissures are not clinically obvious, they penetrate deep into the enamel and frequently reach the dentine-enamel junction. Effective treatment is recommended to block access to P&F, thus preventing ingress of bacteria.

Objetivos: El objetivo del presente estudio descriptivo fue evaluar cualitativamente mediante un ensayo ex vivo la profundidad de las fosas y fisuras (F&F) del esmalte en terceros molares inferiores humanos. Materiales y métodos: Cincuenta (n=50) terceros molares inferiores sanos extraídos se lavaron, se descontaminaron y se recubrieron con esmalte para uñas hasta 1 mm menos del área de las F&F. Luego se sumergieron durante 48 horas a 37°C en una solución de azul de metileno al 1% (pH 7,4) preparada con saliva artificial. Posteriormente se lavaron y se separaron las coronas a nivel del límite amelocementario. En cada molar se realizó una sección longitudinal de 1 mm de espesor con orientación vestíbulo-lingual a nivel de la fosa central. Las secciones fueron analizadas con microscopio estereoscópico y fotografiadas. Las imágenes se transfirieron a una computadora. Se determinó cualitativamente la extensión de las F&F en el espesor del esmalte y se las clasificó de acuerdo a 3 categorías. C1: extensión hasta la mitad del espesor del esmalte; C2: extensión que supera la mitad del espesor del esmalte sin afectar el límite amelodentinario; C3: extensión que llega al límite amelodentinario. Resultados: Para las fosas, 35, 9 y 6 especimenes correspondieron a las categorías C1, C2 y C3 respectivamente. Para las fisuras, 15, 18 y 17 especimenes correspondieron a las categorías C1, C2 y C3 respectivamente. Conclusiones: Las fosas y fisuras de la muestra analizada se extienden hasta la zona más profunda del espesor del esmalte. Con cierta frecuencia llegan hasta el límite amelodentinario.

Effect of immediate and delayed post space preparation on coronal bacterial microleakage in teeth obturated with a methacrylate-based sealer with and without accelerator.

PURPOSE: To investigate the sealing properties of root fillings with resin-coated gutta-percha cones and a methacrylate-based resin endodontic sealer with and without an accelerator component in root canals subjected to immediate or delayed post space preparation. METHODS: Forty-eight extracted human teeth with single straight root canals were treated endodontically. Specimens were then assigned to four groups of 10 teeth each (n=10). After autoclaving, the following operative procedures were carried out under strict aseptic conditions. In Group 1 the root canals were filled with resin-coated gutta-percha cones and a methacrylate based resin endodontic sealer (EndoREZ). Post space preparations were performed 2 minutes after the sealer had set. In Group 2 the root canals were filled as in Group 1 but with the addition of a chemical accelerator. The post space preparations were also performed 2 minutes after the sealer had set. Groups 3 and 4 were filled as in Groups 1 and 2 respectively, however the post space preparations were done 7 days after the root canal filling was completed. One positive and one negative control tooth per group was added. All specimens were subjected to a coronal bacterial leakage of E. faecalis during a 60-day period using a dual chamber microbial leakage model. Data was analyzed among groups with the Kaplan-Meier survival analysis while significant pairwise differences were analyzed with the log-rank test (P<0.05). RESULTS: No significant differences (P>0.05) in bacterial leakage were observed between Groups 1 and 2 and between Groups 3 and 4. However, Groups 1 and 2 differed significantly from Groups 3 and 4 (P<0.05).

Sealing properties of a calcium aluminate luting agent.

PURPOSE: To determine the self-sealing properties of Ceramir C&B, a new calcium aluminate-based luting material and to compare it to two commercially available cements, using a bacterial model system. METHODS: 30 premolars were prepared in a standardized fashion with a total angle of convergence of approximately 10-12 degrees for complete cast restorations. All margins were placed in dentin. Gold copings were fabricated in a Type III alloy using standardized laboratory methods. Thirty teeth were randomly assigned to three groups of 10: Group 1: Ceramir C&B (CM), a calcium aluminate/glass ionomer hybrid (formerly XeraCem), Group 2: Ketac-Cem (KC), a glass-ionomer cement (control) and Group 3: Rely X Luting Plus (RX), a resin-modified glass-ionomer cement. After cementation the samples were allowed to bench set for 10 minutes, after which they were subjected to thermal cycling (x2000, between 5 and 55 degrees C, dwell time 35 seconds) and then stored in sterile phosphate buffer for 7 days at 37 degrees C. Subsequently the occlusal surface was carefully reduced exposing the dentin. Finishing on wet sand paper removed the gold flash from grinding. After sterilization the specimens were subjected to bacterial microleakage in a dual chamber apparatus for a period of 60 days. Turbidity was recorded daily. The data were analyzed using the Kaplan-Meyer survival analysis and the log-rank test (P<0.05). RESULTS: A statistical analysis demonstrated that the groups cemented with CM and RX showed no significant difference in microleakage patterns (P>0.05), while both recorded significantly lower microleakage scores (P<0.05) than the group cemented with KC.

Peroxide penetration from the pulp chamber to the external root surface after internal bleaching.

PURPOSE: To quantify the amount of peroxide penetration from the pulp chamber to the external surface of teeth during the walking bleaching technique. METHODS: Seventy-two bovine lateral incisors were randomly divided over five experimental groups and one control (n = 12 per group): (1) 35% hydrogen peroxide (HP); (2) 35% carbamide peroxide (CP); (3) sodium perborate (SP); (4) (HP+SP); (5) (CP+SP) and (6) Control (CG), deionized water. All groups were treated according to the walking bleach technique. After 7 days at 37 degrees C in an acetate buffer solution, 100 microl violet leukocrystal coloring and 50 microl peroxidase was added, producing a blue stain that could be measured in a spectrophotometer and then converted into peroxide microg/ml. RESULTS: G5 exhibited the greatest penetration, while G2 and G3 produced the lowest values. All bleaching agents penetrated from the pulp chamber to the external root surface. There was a direct correlation between the presence of oxidative agents and penetration potential. Sodium perborate in distilled water was less oxidative and appeared to be the least aggressive bleaching agent.

Conservative approach to dental extractions in patients on anticoagulant therapy: A clinical study.

This clinical study reviewed dental surgical extractions that were performed on 532 patients diagnosed at risk of thromboembolism without interrupting their anticoagulant therapy. The results confirmed that anticoagulant therapy can be modified successfully and does not need to be interrupted, which can carry significant risks.

Influence of a Retentive Shoulder Design to Prevent Early Failure of Three Core Build-Ups.

This study evaluated the influence of a retentive shoulder design to prevent early failure of three resin composite build-ups on molars. Ninety-six intact extracted human maxillary third molars were assigned to two groups (n=48) based on occlusal, buccal cusps only and all cusps reduction. The groups were divided into two subgroups: pin retained and non-pin retained build-ups resulting in four groups (n=24), according the cusps reduction: pin retained/partial, pin retained/complete, non-pin retained/partial, non-pin retained/complete. Occlusal reduction was 3 mm with a semi-lunar retentive shoulder of 3 mm and an axial wall height of 1.5 mm. Groups were restored using a microhybrid, flowable or titanium reinforced resin composite. Modified self-curing acrylic resin provisional crowns were fabricated, cemented with non-eugenol temporary cement and thermal cycled. An instron machine applied tension to the provisional crowns parallel to the long axis of the tooth until dislodgement. A three-way analysis of variance was conducted on the influence of the variables on the retention of the core build-up. Ninety-three build-ups were retained under tensile load, while three core build-ups without pins were dislodged. Three-way analysis of variance showed no statistically significant difference between core build-ups using a retentive shoulder and pin retained core build-ups when tested under tensile load. With the advent of adhesive systems, increased surface area and retentive shoulder design can provide a retentive core foundation to prevent early failures of core build-ups during indirect restoration fabrication which will contribute to the longevity of final restorations.

Significance of moist root canal dentin with the use of methacrylate-based endodontic sealers: an in vitro coronal dye leakage study.

This in vitro study compared the effect of different levels of moisture of root canals, from none to wet, on the coronal seal after filling with resin-coated gutta-percha cones/EndoRez [RGPC/ER (groups 1-4)], Resilon/Epiphany [RE/EP (groups 5-8)], and gutta-percha/Grossman's cement [GP/G (groups 9-12)]. The length of 76 single-rooted extracted human teeth was standardized to approximately 17 mm. After instrumentation with size 10 K-Files, #2 and #3 Gates Glidden burs, and preparation to the working length with K-Type files, the smear layer was removed with 17% ethylenediaminetetraacetic acid followed by flooding with distilled water. On the basis of similarities of canal shape determined by x-rays, roots were assigned to the groups (n = 5 per group) and treated according to one of the following protocols. (I) ETOH: excess distilled water was removed with paper points followed by dehydration with 95% ethanol; (II) PAPER POINTS: the canals were blot-dried with paper points with the last one appearing dry; (III) MOIST: the canals were dried with low vacuum by using a luer adapter for 5 seconds followed by 1 paper point for 1 second; and (IV) WET: the canals remained totally flooded. The roots were then filled with one of the obturation systems outlined above. The teeth were coated with 2 layers of nail varnish and 1 layer of sticky wax, except for the coronal access. In addition, positive and negative controls were added. After immersion in 2% methylene blue dye for 7 days, the samples were embedded in clear orthodontic resin and cross-sectioned at 0.5-mm intervals along the length of the roots. Dye penetration was evaluated by an independent investigator with a stereomicroscope at 40x magnification. The results indicated that dye leakage was affected by the degree of moisture. All materials evaluated showed some evidence of dye penetration, however, root canals filled with resin-coated gutta-percha/EndoRez and Resilon/Epiphany demonstrated significantly less leakage (P < .05) when moist conditions II and III were present.

Nonvital tooth bleaching: a review of the literature and clinical procedures.

Tooth discoloration varies in etiology, appearance, localization, severity, and adhesion to tooth structure. It can be defined as being extrinsic or intrinsic on the basis of localization and etiology. In this review of the literature, various causes of tooth discoloration, different bleaching materials, and their applications to endodontically treated teeth have been described. In the walking bleach technique the root filling should be completed first, and a cervical seal must be established. The bleaching agent should be changed every 3-7 days. The thermocatalytic technique involves placement of a bleaching agent in the pulp chamber followed by heat application. At the end of each visit the bleaching agent is left in the tooth so that it can function as a walking bleach until the next visit. External bleaching of endodontically treated teeth with an in-office technique requires a high concentration gel. It might be a supplement to the walking bleach technique, if the results are not satisfactory after 3-4 visits. These treatments require a bonded temporary filling or a bonded resin composite to seal the access cavity. There is a deficiency of evidence-based science in the literature that addresses the prognosis of bleached nonvital teeth. Therefore, it is important to always be aware of the possible complications and risks that are associated with the different bleaching techniques.

The effectiveness of manual and mechanical instrumentation for the retreatment of three different root canal filling materials.

The aim of this study was to compare the effectiveness of the Mtwo R (Sweden & Martina, Padova, Italy), ProTaper retreatment files (Dentsply-Maillefer, Ballaigues, Switzerland), and a Hedström manual technique in the removal of three different filling materials (gutta-percha, Resilon [Resilon Research LLC, Madison, CT], and EndoRez [Ultradent Products Inc, South Jordan, UT]) during retreatment. Ninety single-rooted straight premolars were instrumented and randomly divided into 9 groups of 10 teeth each (n = 10) with regards to filling material and instrument used. For all roots, the following data were recorded: procedural errors, time of retreatment, apically extruded material, canal wall cleanliness through optical stereomicroscopy (OSM), and scanning electron microscopy (SEM). A linear regression analysis and three logistic regression analyses were performed to assess the level of significance set at p = 0.05. The results indicated that the overall regression models were statistically significant. The Mtwo R, ProTaper retreatment files, and Resilon filling material had a positive impact in reducing the time for retreatment. Both ProTaper retreatment files and Mtwo R showed a greater extrusion of debris. For both OSM and SEM logistic regression models, the root canal apical third had the greatest impact on the score values. EndoRez filling material resulted in cleaner root canal walls using OSM analysis, whereas Resilon filling material and both engine-driven NiTi rotary techniques resulted in less clean root canal walls according to SEM analysis. In conclusion, all instruments left remnants of filling material and debris on the root canal walls irrespective of the root filling material used. Both the engine-driven NiTi rotary systems proved to be safe and fast devices for the removal of endodontic filling material.

A comparative study of the bioactivity of three materials for dental applications.

OBJECTIVES: The aim of this work was to investigate the in vitro bioactivity of two different experimental dental luting cement formulations based on calcium aluminate (CA) in comparison with glass ionomer cement (GIC). One of the CA-based formulations was a hybrid between CA and GIC. METHODS: Samples were submerged in phosphate buffered saline and stored at 37 degrees C for four periods of time: 1 h, 1 day, 7 days and 4 weeks. After storage the samples were analyzed in order to investigate if a surface layer of hydroxyapatite had formed. The analysis techniques used included grazing incidence X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and transmission electron microscopy. RESULTS: Both the CA-containing formulations were found to be bioactive. The highest degree of bioactivity was found on the sample with only CA as active substance. A relatively thick and totally covering layer was already formed after 24 h. On the hybrid material hydroxyapatite was found after 7 days. The GIC showed no bioactivity during the test period. SIGNIFICANCE: The utilization of a bioactive material for tooth restorations will give an opportunity for remineralization and a natural and durable seal of the tooth-material interface. Materials based on CA exhibit bioactivity.

Histological evaluation of mineral trioxide aggregate and calcium hydroxide in direct pulp capping of human immature permanent teeth.

PURPOSE: To evaluate histological findings in human immature permanent premolars scheduled for extraction for orthodontic reasons, in which mechanical pulp exposures were capped with white ProRoot Mineral Trioxide Aggregate (WMTA) or calcium hydroxide (CH). METHODS: Forty-eight human immature premolars in 23 patients (age 10-18 years) were randomly treated with WMTA or CH. After rubber dam isolation Cl I cavities were prepared and the pulps exposed. After hemostasis the pulps were capped with either material. The preparations were restored using an acid etch, bonding agent, flowable composite and composite resin technique. The teeth were extracted after 47 to 609 days and processed for routine histological examination, stained with hematoxylin and eosin and Brown and Brenn for recognition of bacteria. Statistical analyses of inflammation, bridge formation and bacterial leakage were performed using a Chi-square test and ANOVA. RESULTS: Forty-four of 48 teeth were suitable for microscopic evaluation, 30 with WMTA, 14 with CH. Of the WMTA group, 29 teeth were vital, 28 had formed a bridge, and one specimen had failed. Twelve of 14 teeth with CH were vital, while three teeth failed to form a bridge. No statistically significant differences between WMTA and CH were found, except for superficial and deep inflammatory cell response (P < or = 0.05). Pulp capping of intentionally exposed human immature premolars performed slightly better when using MTA.

Clinical and radiographical evaluation of a resin-based root canal sealer: a 5-year follow-up.

A retrospective clinical and radiographical analysis of 5-year postendodontic treatment with a resin-based sealer (EndoRez; Ultradent Products Inc, South Jordan, UT) and gutta-percha was conducted. The results after 14 to 24 months were reported previously. Of 180 patients, 120 responded to the 5-year recall. Success of root canal treatments was based on absence of clinical symptoms, a normal or slightly widened periodontal ligament, and absence or reduction of periapical radiolucencies in patients who had preexisting lesions. Root canals had been adequately filled to the working length in 92 teeth (76.66%) and short in 13 (10.83%). Fifteen cases (12.50%), filled flush at the initiation of the experiment, showed slight resorption of the filling material at the apex within the lumen of the root canal. Of the 10 roots with extrusion, none had radiographic evidence of sealer in the periradicular tissues after 5 years. All patients were free of clinical symptoms. Four cases (3.3%) showed partial healing, whereas 8 cases (6.66%) were judged failures. A life table analysis revealed a cumulative probability of success of 86.3% at the 5-year recall with a 95% confidence interval of 79.7 to 91.0. The clinical and radiographical data suggest that the tested resin-based sealer used in conjunction with gutta-percha performed very well as a root canal sealer over a period of up to 5 years.