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The aim of this study was to evaluate the efficacy of activated irrigants (EDTA e NaOCL) during the cleansing of root walls, of the smear layer, of the debris, and gutta-percha after the preparation of the restorative space. Twenty single and multi-rooted (n = 20) have been collected. All samples were prepared by the same operator, using Nickel-titanium rotating instruments (Mtwo) through the Simultaneous Shaping Technique. The continuous-wave of condensation technique of obturation was used. To all specimens, the restorative space has been made, leaving 5 mm of apical gutta-percha, and postoperative periapical X-rays were performed. The samples were randomly divided into two groups: Group (A): cleansing of the root walls with ultrasonic activation of the irrigants (NEWTRON P5 XS; Satelec Acteon); Group (B): radicular walls wash without ultrasonic activation of endodontic irrigants (NaOCl 5.25% and EDTA 17%). Both dental sample groups were cut longitudinally with a low-speed saw (Isomet); the samples were observed by using a scanning electron microscope (Jeol, Jsm-6060LV) in order to evaluate: (1) the amount of debris/smear layer; (2) the mount of obstruction of dentinal tubules found in the two groups; and (3) evaluation of the presence of gutta-percha. Then, the other five samples each group (with and without ultrasonic activation) were prepared following the same protocol. Then, a universal bonding system (G-Praemio Bond, GC) and a layer of a flowable resin composite (Gaenial Flow, GC) were light-cured and used on top of the prepared root canal walls. The samples were cut in two pieces along the long axis of the root. Then, half sample teeth were kept in an acidic solution (37% HCl) for 48 h in order to completely dissolve dental structures and to have a direct view of resin tags formation under SEM. The other half was prepared to observe the adhesive interface under SEM. The amount of debris was not satisfactory in 9 out of 10 cases in Group B, while in Group A, which has been treated with ultrasounds, the result was either good or great in most of the samples. For the sample group treated with ultrasound, the tubules were evaluated as perfectly clean in 9 out of 10 cases, instead, the results are unsatisfactory for 9 out of 10 cases of group B not treated with ultrasound. Differences between Group A and B were statistically significant. With respect to the presence of debris and tubules obstruction treatment with ultrasonic activation, it offers with no doubt better results. When ultrasonic activation is used in combination with endodontic irrigants, a clean dentin substrate is be obtained for the adhesion of restorative materials, but in order to confirm the findings of this study, further in vivo trials are needed.

To assess the influence of multiple uses on the cyclic flexural fatigue and torsional resistance of Reciproc R25 (REC25) instruments.Overall, 256 canals (two for each mandibular molar) were prepared using Reciproc R25 instruments. A total of 96 25-mm-long Reciproc R25 instruments were divided in six groups (N.=8) on the basis of different number of canals shaped: new instruments (control group), one, two, three, four, or six canals shaped during simulated clinical use for other groups respectively. Sixteen files were used for each of the six groups (eight instruments for cyclic fatigue test and eight ones for torsional test). Times to fracture (TtF) for cyclic fatigue and ultimate torsional strength and angle of rotation to fracture for torsional resistance were recorded. Data were statistically evaluated by the analysis of variance (ANOVA) with P0.05.As for cyclic fatigue resistance, there was no significant difference between new REC25 and REC25 used in one, two and three canals respectively (P0.05). REC25 used in four and six canals showed significant lower times to fracture when compared with other groups (P0.05) with REC25 used in six canals showing the significant lowest times to fracture (P0.05). Considering torsional resistance parameters, no significant difference was observed between the new and used instruments (P0.05).REC25 files showed a significant decrease in cyclic fatigue resistance only when used in four or more molar canals while their torsional behavior was not affected by multiple uses.

The aim of this study was to assess if the curing mode and the etching mode could affect the push-out bond strength of different post cementation systems using two universal adhesives.A total of 100 single-rooted teeth were divided into PrimeBond Elect (PBE), PrimeBond Active (PBA), and PrimeBond XP (PBXP) as a control. The PBE, PBA, and PBXP were used in the self-etch (SE) and etch and rinse (ER) mode. Post cementation was performed using Core X flow used in dark-cure and in light-cure. Data were analyzed using the one-way ANOVA test andBond strength was significantly influenced by the adhesive strategies. The PBE and PBA obtained higher values when used in the SE mode (The PBA and PBE universal adhesives obtained higher PBS values when used in the SE mode and followed by the light-curing of resin cement.Universal adhesives represent a good alternative to the conventional total-etch adhesive system for fiber post cementation. Since they perform better in SE, they would be recommendable in clinical practice, as they can be used with a simplified technique.

The aim is to evaluate the influence of remaining tooth substance and post-endodontic restoration on fracture strength of endodontically treated maxillary incisors. 150 maxillary central incisors were divided into three groups, Group 0, intact teeth; Group 1, removal of distal wall; Group 2, removal of mesial and distal walls, and further into two subgroups A0,A1,A2 and B0,B1,B2 according to post-endodontic restoration (post/no-post), then loaded to fracture. Interactions among variables and intergroup significance were tested with two-way ANOVA and Kruskal Wallis's tests (p≤0.05). Tukey's test was applied for multiple comparisons. Statistically significant differences were found between groups B1-A1, and B2-A2, but they were not found between B0-A0. Intragroup analysis showed statistically significant differences in both groups post/no-post with decreasing dental substance. Fiber post placement causes an increase in fracture strength and a reduction of irreparable fractures in endodontically treated maxillary central incisors that lost at least one wall.

BACKGROUND Finishing and polishing procedures play a crucial role to achieve the best aesthetic result of direct restorations. Many manufacturers to the clinicians offer different finishing and polishing systems. This study aims to examine the behavior of four different finishing and polishing systems on the roughness, gloss and morphology surface of one resin composite. METHODS Twelve Filtek XTE Supreme (3M ESPE) discs were prepared and divided into 4 groups (N.=3), depending on the different finishing and polishing systems: Group 1 (GP1) Sof-Lex Extra-Thin XT discs; Group 2 (GP2) Sof-Lex Coarse black disc, multi-fluted bur, Sof-Lex Diamond Polishing System Spirals; Group 3 (GP3) Sof-Lex Coarse black disc, multi-fluted bur, Sof-Lex Diamond Polishing System Spirals, Diamond Twist SCL; Group 4 (GP4) with Sof-Lex Coarse black disc, multi-fluted bur and Occlubrush. The roughness and gloss were evaluated and then samples examined by Scanning Electron Microscopy (SEM) to analyse the morphology after finishing and polishing. RESULTS Regarding the surface roughness, GP1 and GP2 showed similar values for Ra, Ry, Rz and Rq parameters; while GP3 displayed the lowest values in all parameters; GP4 had the highest Ra value. Regarding the gloss, the values decreased as follows: GP3>GP2=GP4>GP1 (P

This study assessed push-out strength, cement layer thickness, and interfacial nanoleakage of luted fiber posts fabricated with computer-aided design/computer-assisted manufacture (CAD/CAM) technology after use of 1 of 3 scanning techniques, namely, direct scanning of the post space (DS), scanning of a polyether impression of the post space (IS), and scanning of a plaster model of the post space (MS). Thirty premolars were randomly assigned to three groups corresponding to the scanning technique. Posts were computer-designed and milled from experimental fiber-reinforced composite blocks. The mean (±SD) values for push-out strength and cement thickness were 17.1 ± 7.7 MPa and 162 ± 24 μm, respectively, for DS, 10.7 ± 4.6 MPa and 187 ± 50 μm for IS, and 12.0 ± 7.2 MPa and 258 ± 78 μm for MS specimens. Median (interquartile range) interfacial nanoleakage scores were 3 (2-4) for DS, 2.5 (2-4) for IS, and 3 (2-4) for MS. Post retention was better for fiber posts fabricated by DS technique than for those fabricated by IS and MS. Cement thickness did not differ between DS and IS specimens, but the cement layer was significantly thicker in the MS group than in the other two groups. Scanning technique did not affect sealing ability, as the three groups had comparable nanoleakage values.

This in vitro study assessed morphological changes and efficiency of reciprocating files after multiple uses. Sixty standardized Endo Training Blocks and 10 ReciprocR25 files were selected (six blocks for each file). Each file was its own control (before use vs. after each instrumentation). The instruments were used according to the manufacturer's instructions, and scanning electron microscopy was used to observe fatigue cracks, metal strips/metal flash, pitting, fretting, debris, disruption of the cutting edge, and plastic deformations after each instrumentation. The presence of seven wear variables was scored semiquantitatively by viewing micrographs collected before and after use. The prepared areas in resin blocks were calculated and compared by using AutoCAD software. The control group had significantly lower values for all wear variables except fretting and plastic deformation. The presence of fatigue cracks and metal strips/metal flash significantly differed between unused instruments and instruments used four or five times, in all observed sections. The area of instrumented Endo Training Blocks significantly differed in relation to the number of instrument uses. The Reciproc files wore progressively, and repeated use affected their shaping efficiency in simulated canals.

AIM The aim of the present study was to evaluate the resistance to cyclic fatigue of heat-treated single files used in proper or in reciprocating optimum torque reverse motions. METHODS Ninety-six HyFlex electrical discharge machining (EDM), Reciproc R25 (Rec), WaveOne Primary (WO), and WaveOne Gold (WOG) Primary were used. Resistance to cyclic fatigue was determined by recording time to fracture in a stainless steel artificial canal. Differential scanning calorimetric analysis was performed. Data were analyzed by two-way analysis of variance and Bonferroni post-hoc tests at 0.05. RESULTS In both movements, HyFlex EDM showed higher time to fracture than other files (P

To evaluate the resistance to cyclic fatigue of ProTaper Next (PTN; Dentsply Sirona, Ballaigues, Switzerland), Revo-S (Micro-Mega, Besançon, France), Mtwo (SwedenMartina, Padova, Italy), Twisted Files (TF, SybronEndo, Orange, CA, USA) and EndoWave (J Morita Corporation, Osaka, Japan) used in continuous rotation or in reciprocation of Optimum Torque Reverse motion (OTR).A total of 120 nickel-titanium files were tested. Twenty-four instruments for each brand were divided into two groups (n = 12) on the basis of the motion tested: continuous rotation (Group 1) or reciprocation of OTR motion (Group 2). Resistance to cyclic fatigue was determined by recording time to fracture (TtF) in a stainless steel artificial canal with a 60° angle of curvature and 5 mm radius of curvature. The TtF data were analysed by using two-way analysis of variance (anova) and Bonferroni's post hoc tests at 0.05.Mtwo and TF had significantly higher TtF when compared with all other instruments, both in continuous rotation and in reciprocation of OTR motion (P 0.0001 and P 0.05, respectively). No difference was observed between Mtwo and TF (P 0.05), in both motions. PTN was associated with higher cyclic fatigue resistance than Revo-S and EndoWave, both in continuous rotation and in reciprocation of OTR motions (P 0.0001). No difference was observed between Revo-S and EndoWave, in both motions (P 0.05). Reciprocating OTR motion improved TtF of all instruments (P 0.0001).Reciprocation of OTR motion improved significantly cyclic fatigue resistance of all instruments tested compared with continuous rotation. Mtwo and TF had significantly higher cyclic fatigue than the other instruments, in both continuous rotation and reciprocation of OTR motion.

The purpose of this study was to evaluate the reinforcing effect of fibre-reinforced composites (FRC) applied in premolar teeth with different techniques and minimally invasive post space preparation. Fifty extracted and endodontically treated premolar teeth were used. The teeth were divided into five groups (n = 10) depending on the restorative technique (Groups 1-5). Group 1: one single conventional post, Group 2: one main conventional and one collateral post, Group 3: one elastic post, Group 4: one main elastic and one collateral post, and Group 5: individual post formed of elastic posts. After cementation and core build-up, the specimens were submitted to static fracture resistance test. Fracture thresholds and fracture patterns were measured and evaluated. Group 4 showed the highest average fracture resistance among the tested groups. The multi-post techniques (group 2 and 4) exhibited statistically higher fracture resistance compared to group 1. Regarding fracture patterns, there was no statistically significant difference between the tested groups. Within the limitations of this study, the application of multiple elastic or conventional FRC posts or a single elastic post in the same root canal is beneficial in terms of fracture resistance compared to a single conventional FRC post. The elasticity or the number of posts did not influence the fracture patterns.

Mollo A, Botti G, Prinicipi Goldoni N, Randellini E, Paragliola R, Chazine M, Ounsi HF, Grandini S. Efficacy of two Ni-Ti systems and hand files for removing gutta-percha from root canals. International Endodontic Journal, 45, 1–6, 2012. Abstract Aim To compare the effectiveness of two Ni-Ti systems and hand files for removing gutta-percha and sealer from root canals. Methodology The root canals of 60 single-rooted human teeth were prepared, filled with gutta-percha and sealer (Pulp Canal Sealer; SybronEndo, Orange, CA, USA). Specimens were then divided into three groups (n = 20), and root filling material was removed using MTwo Retreatment Files (group 1); R-Endo (group 2); K-files and Gates-Glidden drills (group 3). After retreatment, the efficacy of each technique was assessed using radiographs that were later digitized and the images analysed using AutoCAD 2004. The percentage of residual gutta-percha was calculated for the whole canal as well as for the coronal, middle and apical thirds. Time required, apically extruded debris and the number of fractured instruments were also recorded. Data were statistically analysed using Kruskal–Wallis and Mann–Whitney U-tests. Results All instrumentation techniques left gutta-percha and sealer remnants inside the root canals. Ni-Ti systems were significantly faster (P

– Objectives: When coronal fracture occurs in anterior teeth, fragment reattachment can be a valid alternative to a direct restoration. The aim of this study was to evaluate the influence of the material and the technique used to reattach the fragment. Materials and methods: Eighty sound maxillary and mandibular incisors were selected and randomly divided into eight groups (n = 10). The incisal third of each tooth was removed using a saw machine. The fragments in groups 1–4 were reattached using resin-based materials: group 1 adhesive, group 2 flow, group 3 composite, group 4 cement; in groups 5–8, the same materials mentioned before were used but a bevel was also performed on both labial and lingual surfaces. Shear bond strength (SBS) was calculated by applying a load incisal to the reattachment line. A two-way Anova was used to evaluate the influence of materials and techniques on the SBS. Results: The technique used was statistically significant (P

Introduction Four generations of methacrylate resin–based sealers have been available commercially. Three of these were introduced during the last 5 years when the concept of simultaneous bonding of root canal sealers to root filling materials and dentin was popularized. Methods This article presents an overview of methacrylate resin–based sealers, with the objectives of clarifying the behavior of these materials and delineating their limitations in clinical application. Results The first generation sealer was introduced in the mid-1970s. The initial enthusiasm associated with its use eventually diminished as a result of its suboptimal physical, biologic, and clinical properties. With advances in self-etching adhesive technology acquired from adhesive dentistry, methacrylate resin–based sealers were reintroduced in the beginning of the 21st century to support the introduction of bondable root canal filling materials. Three different generations of these sealers have since been available commercially. Although some in vitro studies on the sealing ability, self-etching potential, biocompatibility, and removability of the sealers showed better potential over conventional nonbonding sealers, accomplishing the ideal goal of a monoblock in the root canal space with these materials is still regarded as a major challenge. Conclusions On the basis of the in vitro and in vivo data available to date, there appears to be no clear benefit with the use of methacrylate resin–based sealers in conjunction with adhesive root filling materials at this point in their development.

Adhesive dentistry should effectively restore the peripheral seal of dentin after enamel removal. We hypothesize that non-rinsing, simplified, one-step self-etch adhesives are effective for minimizing dentin permeability after tooth preparation procedures. Crown preparations in vital human teeth were sealed with Adper Prompt, Xeno III, iBond, or One-Up Bond F. Epoxy resin replicas were produced from polyvinyl siloxane impressions for SEM examination. Dentin surfaces from extracted human teeth were bonded with these adhesives and connected to a fluid-transport model for permeability measurements and TEM examination. Dentinal fluid droplets were observed from adhesive surfaces in resin replicas of in vivo specimens. In vitro fluid conductance of dentin bonded with one-step self-etch adhesives was either similar to or greater than that of smear-layer-covered dentin. TEM revealed water trees within the adhesives that facilitate water movement across the polymerized, highly permeable adhesives. Both in vitro and in vivo results did not support the proposed hypothesis.

Objective. The objective of this clinical report was to evaluate the effectiveness of a microbrush as a carrier of priming-adhesive solution in formation of resin tags, adhesive lateral branches, and resin-dentin interdiffusion zone (RDIZ) when the brush was used to bond fiber posts under clinical conditions. Study Design. Twenty endodontically treated teeth, already scheduled for extraction for endodontic or periodontal reasons, were selected for this study. The patients were informed, and their written consent was obtained. The samples were randomly divided into 2 groups of 10 samples each. In group 1, One-Step (Bisco, Schaumburg, Ill) was applied with a brush with Duo-Link resin cement (Bisco). In group 2, One-Step was applied with a microbrush with Duo-Link resin cement (Bisco). Use of the adhesive systems and resin cements was strictly according to manufacturers' instructions. The priming-adhesive solution was light-cured before the dual resin cement and the post were placed. Twenty Aestheti-Plus posts (white quartz fiber posts; RTD, St. Egreve, France) were used. A week after application, the root samples were extracted and processed for SEM observations. Results. Both adhesive systems showed RDIZ and resin tag and adhesive lateral branch formation. In Group 2 samples, RDIZ morphology was easily detectable and uniform along root canals. Also, resin tag formation was well represented in all thirds. In group 1 samples, resin tag formation at the apical third and RDIZ formation was less evident. Statistically significant differences were found among the two groups at the apical third. Conclusion. The microbrush permitted a more uniform RDIZ and resin tag formation along the entire length of the canal than did the standard brush. The microbrush can be routinely used for bonding fiber posts into root canal preparations. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2002;94:627-31)

Objectives: The objective of this investigation was to evaluate the effectiveness of three ‘one-bottle’ and two ‘three step’ adhesive systems (as controls) in the formation of resin tags, adhesive lateral branches and a resin dentin interdiffusion zone (RDIZ) when used to bond fiber posts under clinical conditions. This study was performed using standardized SEM observations and scoring resin tag formation and density. Methods: Fifty root canal treated teeth, already scheduled for extraction for endodontic or periodontal reasons, were selected for this study. The patients were informed and their written consent was obtained. The samples were randomly allocated to five groups of ten samples each. Group 1: All Bond 2 with C & B (Bisco); Group 2: Scotchbond Multipurpose Plus with Opal Luting Composite (3M); Group 3: Scotchbond 1 in combination with Rely X ARC resin cement (3M); Group 4: One-step with C & B resin cement (Bisco); Group 5: All Bond Experimental with Post Cement HI–X (Bisco). The adhesive systems and resin cements were used strictly according to the manufacturers’ instructions. The priming-adhesive solution of each ‘one-bottle’ system was light-cured before placing the resin cement and the post. Fifty Aestheti-Plus posts (white quartz fiber posts, RTD, France) were used. A week later, the roots were extracted and processed for SEM observations. Results: All the adhesive systems showed a RDIZ and resin tag and adhesive lateral branch formation. Microscopic examination of the restored interfaces of Groups 1 and 2 showed a higher percent of RDIZ than those found in samples of Groups 3, 4 and 5. RDIZ morphology was easily detectable and uniform in the first two thirds of the root canals, whilst in the apical third the RDIZ was not uniformly present. Resin tag morphology and formation were significantly more detectable in the cervical and middle areas than in the apical zone. No statistically significant differences were found among the five groups coronally, while in the apical and middle thirds two ‘one-bottle’ systems (Groups 3 and 4) showed significantly less resin tags than the control Groups 1, 2 and the experimental Group 5. No statistically significant differences were found among the three ‘one-bottle’ systems in the three evaluated areas. The standardization of SEM observations and scoring resin tag formation allowed statistical evaluation. Conclusions: The ‘three step’ adhesive systems can create a wider micromechanical interlocking between adhesive materials and etched dentin than ‘one-step’ systems.

Objective: Different single-file instruments and kinematics have been introduced on the market. It is important to know the cyclic fatigue performance of these instruments in these new kinematics such as reciprocation of Optimum Torque Reverse (OTR) motion. The aim of this study was to evaluate the resistance to cyclic fatigue of F6 SkyTaper and OneShape used in continuous rotation (proper rotation) or in reciprocating OTR motion. Methods: A total of forty-eight nickel-titanium files were tested. Twenty-four instruments of both brands were divided into two groups (n=12) on the basis of the motion tested: continuous rotation (group 1) or reciprocating OTR motion (group 2). Resistance to cyclic fatigue was determined by recording time to fracture (TtF) in a stainless steel artificial canal with a 60° angle of curvature and 5 mm radius of curvature. Data were analysed by two-way analysis of variance and post-hoc Bonferroni tests for multiple comparisons with P

Objective: The aim of this study was to evaluate the shear bond strength to dentin of primary molars of a new self-adhering flowable resin composite with two ionomer-based cements and one flowable resin composite in combination with two different adhesive systems. Study design: Fifty primary molars were grinded on the occlusal surface to obtain flat dentin substrate and randomly divided into 5 groups (n=10): OFL:Phosphoric Acid/Optibond FL/Premise Flow; OAO:Optibond All-In-One/Premise Flowable; II:Polyacrylic Acid/Fuji II; IX:Polyacrylic Acid/Fuji IX; V:Vertise Flow. Cylinders (3mm diameter – 5mm height) of restorative material were built-up in three increments over the dentin surfaces. A shear load was applied until failure. Bond strength values were statistically analysed with Kruskall-Wallis ANOVA followed by Dunn's test (P

This study was designed to determine if the alloy composition shares an influence with the geometric design on the physical behavior of nickel-titanium rotary endodontic instruments. ProTaper, HERO, and K3 files were selected. After sterilized and cleaning with alcohol, surface analysis was performed using energy dispersive spectroscopy. Measurements were performed on the active part and on the shank. SEM images of fractured instruments were also obtained and assessed. All three types of instruments were composed mainly of Nickel (54.3%, SD +/- 0.8) and Titanium (45.2%, SD +/- 0.9). SEM images revealed similar aspect with the presence of Kirkendall voids regularly distributed in the alloy. The results indicate that the difference in properties and behavior of these three endodontic rotary shaping instruments is solely related to the respective geometric characteristics of the instrument design.

Objectives: To evaluate interfacial nanoleakage expression of the combination of different cementation procedures and different crown systems. Methods: Forty-five human premolars prepared to receive single crowns were randomly divided into three groups (n = 15) based on the materials to be used for crown fabrication and cementation: group 1: Zirc (Ivoclar-Vivadent) cemented with Multilink Automix; group 2: Ivoclar disilicate IPS Empress 2 luted with Excite DSC in combination with Variolink II; group 3: AAdva Zirconia (GC) cemented with G-Cem Automix. The specimens were then assessed for interfacial nanoleakage expression and the amount of silver deposits along the interface was quantified. The thickness of the cement was assessed at 5 different levels: cervical margins, midway between the cervical margin and the occlusal wall along the axial walls and at the occlusal wall. The nanoleakage scores and the cement thickness were analyzed with Kruskall-Wallis non-parametric Analysis of Variance and Dunn's Multiple-range post hoc test. Results: Group 2 showed significantly less nanoleakage expression than group 1 (p < 0.05). The groups can be ranked in the following order 3 < 1 < 2 with regard to the cement thickness. Conclusions: There was no correlation among combination of different cementation procedures and different crown systems and interfacial nanoleakage. Also the cement thickness and the degree of nanoleakage cannot be related. The amount of cement found at the cervical margins of all groups showed discrepancies within a clinical acceptable range. © 2012 Academy of Dental Materials.

Objectives To compare, by means of the push-out test, the interfacial strength of two dual resin cements and one light-curing cement when used in translucent fiber post cementation. Methods Thirty-nine, endodontically treated, single canal, extracted human bicuspids were selected. Translucent fiber posts (RelyX Fiber Post) were luted into the root canal using three resinous luting systems ( n = 13). Dual-curing technique (DC): the specimens were treated with Excite DSC and RelyX ARC, which were light-cured simultaneously through the post for 60 s. Self-adhesive dual-curing technique (SADC): the specimens were treated with RelyX Unicem, which was light-cured through the post for 60 s. Light-curing technique (LC): the specimens were treated with Excite DSC and Tetric Flow, which were simultaneously light-cured through the post for 60 s. The specimens were transversally sectioned into six slices in order to perform the push-out test. Data were analyzed by two-way ANOVA followed by the Tukey–Kramer test for post-hoc comparisons at α = 0.05. Results At every region, results did not show any statistical difference between the DC and LC techniques. With the LC technique bond strength values were lower at the apical region than those recorded at the coronal and middle regions. At the coronal and middle regions, bond strength values for the SADC technique were lower than those resulting when using the other two techniques. At the apical region, there was not significant difference in bond strength between the luting techniques tested. Conclusions The interfacial strength between light-curing cement and root canal is equivalent to the interfacial strength between dual-curing cement and root canal.

The study aimed at assessing and estimating the fatigue resistance of different fiber posts and to observe their ultrastructures through SEM. Six types of fiber posts were used: GC Fiber Post (Group 1), ParaPost Fiber White (Group 2), FibreKor (Group 3), DT Light-Post radiopaque (Group 4), FRC Postec (Group 5), and Luscent Anchors (Group 6). Ten out of 15 posts within each group were used for the fatigue test, and the other five were processed for SEM evaluation. The fatigue test revealed that Groups 1, 4, and 5 performed better than all the other groups, and that their performance differed significantly from the other tested groups from a statistical standpoint. For SEM analysis, Groups 1, 4, and 5 also obtained better results. Through correlation analysis, an absence of correlation between fatigue resistance and structural characteristics suggested that the latter reflected more of the divergence inherent in the manufacturing process of fiber posts.

This study compared the effect of two drills and five cleaning regimens on post space debridement. One hundred extracted premolars were instrumented and obturated with warm vertical compaction of gutta percha. The teeth were divided into two groups according to the drill used to remove gutta percha/sealer and for post space preparation: a Largo drill (Largo; Dentsply, St Quentin en Yvelines, France) or a MTwo-PF drill (Sweden&Martina, Due Carrare, Padova, Italy). The following cleaning regimens were used: EDTA, ultrasonics, ultrasonics + EDTA, phosphoric acid, and distilled water. Scanning electron microscopic images of the post spaces were taken, and the presence of debris and of open dentin tubules were evaluated. The ultrasonics + EDTA, phosphoric acid, and EDTA groups were comparable in open tubules scores for both drills and in debris scores after the use of MTwo-PF (p > 0.05). The ultrasonics and control groups performed significantly worse (p lt 0.05). The MTwo-PF drill resulted as effective as the Largo drill in obtaining a good post space cleaning, especially when followed by ultrasonics + EDTA irrigant regimen.

Objectives This review aimed at summarizing the laboratory evidence collected on the retentive ability of adhesive posts since their introduction in dentistry. Data Data were searched in articles published or in press in peer-review journals listed in MEDLINE. Sources Papers were retrieved through PubMed. Study selection To collect the evidence of interest, the following search terms were used: bond* AND fiber post AND in vitro; lut* AND fiber post AND in vitro; push-out AND fiber post; pull-out AND fiber post; microtensile AND fiber post. “Related Links” were also considered and articles cited in the initially retrieved papers were included if relevant. No time limit was given to the query. Conclusions Seventy relevant papers were reviewed. The retentive ability of adhesive posts has been tested with the microtensile technique, post-pull-out and push-out tests. If small-sized specimens are obtained, such as in microtensile and thin-slice push-out, stress uniformity is favoured, local differences in bonding conditions can be discerned, and the number of teeth needed for the test can be reduced. Although adhesion to intraradicular dentin is more challenging to achieve than bonding to crown tissues, the post-retention achieved with current luting systems and techniques is adequate to ensure the clinical success of adhesive post-retained restorations. To enhance the bond at the post-core and post-cement interfaces, several chemical pre-treatments of the post-surface have been tested with positive results. Self-adhesive resin cements, recently proposed to simplify the post-luting procedure, should be investigated further with regard to durability.

The resistance of ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) nickel-titanium rotary instruments to cyclic fatigue was examined after their initial use in straight or curved canals in vivo. These instruments were rotated freely inside a steel phantom until separation. The number of rotations before failure and the lengths of the separated fragments were compared with data derived from new instruments under the same experimental setup (n = 20). With the exception of F1 and F3, instruments previously used in curved canals were more susceptible to cyclic fatigue than those previously used in straight canals (p < 0.05). Separation occurred predominantly at the D10 to D12 level. For the F series, a negative correlation (p < 0.05) was observed between the number of rotations before failure and the file diameters at their separation levels. ProTaper F3 instruments are highly susceptible to cyclic fatigue failure and should be reused with caution irrespective of whether they are initially used for shaping straight or curved canals.

Fluid transudation through simplified dentin adhesives can occur in bonded vital crown dentin, since these adhesives behave as permeable membranes after polymerization. The effect of adhesive permeability in endodontically treated teeth is unknown. This study examined the hypothesis that in vivo fluid movement through simplified adhesives occurs when they are applied to root canals. Dowel spaces were prepared in endodontically treated teeth with single root canals. Six adhesives were applied to the intra-radicular dentin of canal walls. Impressions were obtained with polyvinyl siloxane, and replicas were fabricated with the use of polyether impression material. Replica hemisections were gold-coated for SEM examination. Fluid transudation was evident on the adhesive surfaces of all simplified total-etch and self-etch adhesives. Conversely, most of the specimens bonded with the control three-step total-etch adhesive were devoid of fluid droplets. Permeability of simplified adhesives results in water movement, even in root-treated dentin. This may adversely affect the coupling of auto-/dual-cured resin cements.

Objectives . The aim of the present study was to assess the fatigue resistance of different types of fiber posts, and to observe their ultrastructure through scanning electron microscopy (SEM) before and after undergoing the fatigue test. Methods . Eight types of fiber posts were selected for this study. Easypost (Group 1), Para Post Fiber White (Group 2), FibreKor (Group 3), Ghimas White (Group 4), DT Light-Post radiopaque (Group 5), FRC Postec (Group 6), Luscent Anchors (Group 7), Snowpost (Group 8). Ten out of fifteen posts in each group were used for the fatigue test, and the other five were processed for SEM. A three-point bending machine, loading at an angle of 90° and a frequency of 3 Hz was employed for fatigue testing. The test was carried out until two million cycles were completed or until fracturing of the post. SEM evaluation was performed using a three-step scale method to assess the fiber/resin ratio and fiber dimension. Results . The fatigue test showed statistically significant differences among the different posts. Groups 5 and 6 performed better than all the other groups, withstanding practically all the stipulated number of load cycles. All the other posts fractured before the end of the test. SEM observations of the surface integrity of the fiber posts showed that Groups 4–6 obtained better scores for both longitudinal sections and cross-sections. Significance . There was a large variation in the response of different kinds of fiber posts a fatigue resistance test. The absence of correlation between results of fatigue testing and parameters of structural integrity suggests that the latter mostly reflect random variations in the fiber post manufacturing process.

The purpose of this study was to evaluate the influence of two brushes used as carriers of a primer-adhesive solution as to the formation of resin tags, adhesive lateral branches, and a hybrid layer when used to bond translucent fiber posts. Twenty endodontically treated teeth, extracted for periodontal reasons, were used. The samples were randomly divided into two groups of 10 samples each (Group 1: Microbrush + Scotchbond 1 + Rely X ARC resin cement; Group 2: small plastic brush + Scotchbond 1 + Rely X ARC resin cement). The adhesive system and resin cement were used strictly following manufacturers' instructions. The priming-adhesive solution of the one-bottle system was light-cured before placing the resin cement and the post. Twenty translucent fiber posts were used. After luting procedures, root samples were processed for SEM observations. The adhesive system showed a resin dentin interdiffusion zone (RDIZ), resin tag, and adhesive lateral branch formation. Microscopic examination of restored interfaces of group 1 showed a higher percentage (p < 0.05) of RDIZ than those found in samples of group 2. In group 1 samples, RDIZ morphology was well detectable and uniform in all thirds of the root canals. In group 2, RDIZ was not visible in the apical third. No statistically significant differences were found among the two groups coronally and at the middle third, but the apical third of group 1 showed significantly more resin tag formation than group 2. The characteristic reverse cone shape of resin tags was always noted in the coronal and middle third of the root canals of both groups and in the apical third of group 1. In the apical third of group 2 root canals, the resin tags showed a less uniform morphology and a shorter length than those found in the other observed thirds.

This study evaluated the surface of different types of fiber posts after cutting and investigated whether different cutting procedures can affect the integrity of the posts. Six types of fiber posts were selected for this study (Carbon Fiber Posts, Quartz Fiber Posts, Aesthetic Posts, Aesthetic Plus Posts, Translucent Posts, Dentatus, FRC Postec Posts). Fifteen posts of each type were studied. All posts had a diameter of 1.2 to 1.4 mm and were between 14 and 16 mm long. Each group was divided into three subgroups (n = 5) according to cutting method: diamond bur, carborundum disk, or scissors. The samples were then processed for scanning electron microscopic investigation. At low magnifications, no microscopic differences were found among the samples of groups 1-4 and 6. Surfaces from group 5 were more irregular, but only when cut using rotating instruments. All groups showed differences between surfaces cut with scissors and those cut with either diamond bur or carborundum disk. Posts displayed regular surfaces after cutting with a diamond bur. Cutting with a carborundum disk produced a mostly regular surface but sometimes produced irregularities close to the surface borders. The surfaces cut with scissors showed two plane and convergent flanges, and because of the formation of fracture lines these posts lost their integrity not only at the cutting surface but also along their length. The results of this study indicated that fiber posts can be cut using a diamond bur mounted in a handpiece under copious water coolant. Although the carborundum disk cutting procedure showed a less regular post surface, it can be speculated that it might be clinically acceptable. The cutting procedure using scissors should be avoided.

Recently, several adhesives have been proposed for bonding fiber posts into root canals. The aim of this study was to evaluate the influence of four adhesive procedures in resin tag, adhesive lateral branch and resin dentin interdiffusion zone (RDIZ) formation when used to bond fiber posts.Forty anterior teeth, extracted for periodontal reasons and endodontically treated, were selected for this study. The samples were randomly divided into four groups of ten samples each. Group 1: One Step applied with the small brush provided by the manufacturer and LC (Light-cured before resin cement application)+Dual Link resin cement; Group 2: One Step applied with a thin microbrush LC+Dual Link resin cement; Group 3: One Step applied with a small brush (Not light-cured)+Dual Link resin cement; Group 4: All Bond 2+CB resin cement (as control). In Group 2 and 4 the adhesive system and resin cement were used strictly following manufacturers' instructions. In Group 1, One Step was applied using a thin microbrush, while in the other groups by a small brush. In Group 1 and 2 the priming-adhesive solution of the "one-bottle" system was light-cured before placing the resin cement and the post, whereas in Group 3 the adhesive/resin cement combination was light cured through the translucent post. Forty translucent posts (RTD, France) were used. A week later, the root samples were processed for SEM observations.Microscopic examination of restored interfaces of Group 1 showed a higher % (P0.05) of RDIZ than those found in samples of Group 2, 3 and 4. In Group 2, 3 and 4 samples RDIZ morphology was well detectable and uniform in the first two thirds of root canals while in the apical third the RDIZ was not uniformly present. No statistically significant differences were found among the groups coronally, whereas apical and middle thirds of Group 1 showed significantly more resin tags than the other three Groups. In the apical third of Group 2, 3 and 4 samples, the resin tags showed a less uniform morphology and a shorter length than those found in the other two thirds.A microbrush might clinically be used for bonding fiber posts into the root canal. When a microbrush was used, the bonding mechanism created between root canal dentin and bonding system was uniform along canal walls and more predictable.

To evaluate the ability of two luting procedures for bonding translucent fibre posts to form resin tags, adhesive lateral branches, and resin dentine interdiffusion zones (RDIZ).Forty root filled teeth, extracted for periodontal reasons, were selected for the study. The teeth were randomly divided into four groups of 10 each. Group 1: One Step, light-cured (LC) 20 s + dual link resin cement (LC 20 s); group 2: One Step, not light-cured (NLC) + dual link resin cement (LC 30 s); group 3: One Step (NLC) + dual link resin cement (LC 60 s); group 4: One Step (NLC) + dual link resin cement (LC 90 sec). Forty translucent fibre posts (DT posts, RTD) were inserted. Then, root specimens were processed for scanning electron microscope (SEM) observations to assess the continuity of the RDIZ, the presence or absence of gaps and the density and morphology of resin tags using a four-step scale method.With all luting procedures the formation of a RDIZ occurred. However, the microscopic examination of adhesive interfaces revealed that the percentage of RDIZ was significantly higher in group 1 than in the other three groups (P0.05). Group 4 had a higher percentage of RDIZ than group 3, which in turn exhibited a greater percentage than group 2, but these differences were not statistically significant (P0.05). Resin tag formation was evident in all the groups. The characteristic reverse cone shape of resin tags was always noted in the coronal and middle third of all groups, and in the apical third of group 1. In the apical third a shorter length and a less uniform appearance of resin tags were noted in groups 2, 3 and 4.In this laboratory study, when bonding a translucent fibre post into a root canal, the luting procedure including light curing of the adhesive solution before the placement of the cement was more satisfactory, from a SEM standpoint, than the procedure involving the simultaneous curing of adhesive and cement (one step procedure).