Showing papers in "International Endodontic Journal in 2009"

The properties and applications of chlorhexidine in endodontics

Abstract: Microorganisms and their by-products are considered to be the major cause of pulp and periradicular pathosis. Hence, a major objective in root canal treatment is to disinfect the entire root canal system, which requires that all contents of the root canal system be eliminated as possible sources of infection. This goal may be accomplished using mechanical instrumentation and chemical irrigation, in conjunction with medication of the root canal system between treatment sessions. To reduce or eliminate bacteria, various irrigation solutions have been advocated. Chlorhexidine is a cationic molecule, which can be used during treatment. It has a wide range of antimicrobial activity. Its cationic structure provides a unique property named substantivity. The purpose of this paper is to review the structure and mechanism of action of CHX, its antibacterial and antifungal activity, its effect on biofilm, its substantivity (residual antibacterial activity), its tissue solvent ability, its interaction with calcium hydroxide and sodium hypochlorite, its anticollagenolytic activity, its effect on coronal and apical leakage of bacteria, its toxicity and allergenicity and the modulating effect of dentine and root canal components on its antimicrobial activity. A Medline search was performed from 1981 to the end of March 2008 and was limited to English-language papers. The keywords searched on Medline were 'chlorhexidine AND endodontics', 'chlorhexidine AND root canal therapy', 'chlorhexidine AND substantivity' and 'chlorhexidine AND toxicity'. The reference lists of each article were manually checked for additional articles of relevance.

New dimensions in endodontic imaging: part 2. Cone beam computed tomography

Abstract: Cone beam computed tomography (CBCT) has been specifically designed to produce undistorted three-dimensional information of the maxillofacial skeleton, including the teeth and their surrounding tissues with a significantly lower effective radiation dose compared with conventional computed tomography (CT). Periapical disease may be detected sooner using CBCT compared with periapical views and the true size, extent, nature and position of periapical and resorptive lesions can be assessed. Root fractures, root canal anatomy and the nature of the alveolar bone topography around teeth may be assessed. The aim of this paper is to review current literature on the applications and limitations of CBCT in the management of endodontic problems.

New dimensions in endodontic imaging: part 1. Conventional and alternative radiographic systems

Abstract: Conventional radiographs used for the management of endodontic problems yield limited information because of the two-dimensional nature of images produced, geometric distortion and anatomical noise. These factors often act in combination. This review paper assesses the limitations of periapical radiographs and seeks to clarify three-dimensional imaging techniques that have been suggested as adjuncts to conventional radiographs. These include tuned aperture computed tomography, magnetic resonance imaging, ultrasound, computed tomography and cone beam computed tomography (CBCT). Of these techniques, CBCT appears to be an effective and safe way to overcome some of the problems associated with conventional radiographs.

Pulp revascularization of necrotic bilateral bicuspids using a modified novel technique to eliminate potential coronal discolouration: a case report

Abstract: Reynolds K, Johnson JD, Cohenca N. Pulp revascularization of necrotic bilateral bicuspids using a modified novel technique to eliminate potential coronal discolouration: a case report. International Endodontic Journal. Aim To present a case report in which the pulp of two bilateral mandibular premolars with dens evaginatus were revascularized using a modified novel technique to avoid undesired crown discolouration. Summary Recently, regeneration of necrotic pulps has become an alternative conservative treatment option for young permanent teeth with immature roots and is a subject of great interest in the field of endodontics. This novel procedure exploits the full potential of the pulp for dentine deposition and produces a stronger mature root that is better able to withstand the forces than can result in fracture. However, the current protocol has potential clinical and biological complications. Amongst them, crown discolouration, development of resistant bacterial strains and allergic reaction to the intracanal medication. In the case presented, a modified technique to avoid undesired crown discolouration was applied sealing the dentinal tubules of the chamber, thus avoiding any contact between the tri-antibiotic paste and the dentinal walls. Key learning points • Sealing the dentinal tubules of the chamber prevents the undesirable crown discolouration produced by tri-antibiotic medication whilst maintaining the revascularization potential of the pulp. • Further research is warranted to seek an alternative infection control protocol capable of preventing possible allergic reactions and development of resistant strains of bacteria, as well as a biological material capable of inducing angiogenesis and allow a more predictable scaffold and tissue regeneration.

The detection and management of root resorption lesions using intraoral radiography and cone beam computed tomography – an in vivo investigation

Abstract: Patel S, Dawood A, Wilson R, Horner K, Mannocci F. The detection and management of root resorption lesions using intraoral radiography and cone beam computed tomography ‐ an in vivo investigation. International Endodontic Journal, 42, 831‐838, 2009. Aim To compare the accuracy of intraoral periapical radiography with cone beam computed tomography (CBCT) for the detection and management of resorption lesions.

Detection of periapical bone defects in human jaws using cone beam computed tomography and intraoral radiography.

Abstract: AIM To compare the diagnostic accuracy of intraoral digital periapical radiography with that of cone beam computed tomography (CBCT) for the detection of artificial periapical bone defects in dry human jaws. METHODOLOGY Small and large artificial periapical lesions were prepared in the periapical region of the distal root of six molar teeth in human mandibles. Scans and radiographs were taken with a charged couple device (CCD) digital radiography system and a CBCT scanner before and after each periapical lesion had been created. Sensitivity, specificity, positive predictive values, negative predictive values and Receiver Operator Characteristic (ROC) curves as well as the reproducibility of each technique were determined. RESULTS The overall sensitivity was 0.248 and 1.0 for intraoral radiography and CBCT respectively, i.e. these techniques correctly identified periapical lesions in 24.8% and 100% of cases, respectively. Both imaging techniques had specificity values of 1.0. The ROC Az values were 0.791 and 1.000 for intraoral radiography and CBCT, respectively. CONCLUSIONS With intraoral radiography, external factors (i.e. anatomical noise and poor irradiation geometry), which are not in the clinician's control, hinder the detection of periapical lesions. CBCT removes these external factors. In addition, it allows the clinician to select the most relevant views of the area of interest resulting in improved detection of the presence and absence of artificial periapical lesions.

The effects of canal preparation and filling on the incidence of dentinal defects

Abstract: Aim To evaluate ex vivo the incidence of defects in root dentine before and after root canal preparation and filling. Methodology Eighty extracted mandibular premolars were divided equally in four groups. Group 1 was left unprepared. All other root canals were prepared using Gates Glidden drills and System GT files up to size-40, 0.06 taper at the working length. Group 2 was not filled while the canals of the other groups were filled with gutta-percha and AH26, either with a master cone and passive insertion of secondary gutta percha points (group 3) or lateral compaction (group 4). Roots were then sectioned horizontally 3, 6, and 9 mm from the apex and observed under a microscope. The presence of dentinal defects (fractures, craze lines or incomplete cracks) was noted and the differences between the groups were analysed with the Fisher’s exact test. Results No defects were observed in the roots with unprepared canals. The overall difference between the groups was significant (P < 0.05). Canal preparation alone created significantly more defects than unprepared canals (P < 0.05). The total number of defects after lateral compaction was significantly larger than after noncompaction canal filling. Conclusion Root canal preparation and filling of extracted teeth created dentine defects such as fractures, craze lines and incomplete cracks.

Effects of ethylenediaminetetraacetic, etidronic and peracetic acid irrigation on human root dentine and the smear layer.

Abstract: Aim To evaluate the effects of ethylenediaminetetraacetic (EDTA), etidronic (EA) and peracetic acid (PA) when used in conjunction with sodium hypochlorite (NaOCl) as root canal irrigants on calcium eluted from canals, smear layer, and root dentine demineralization after instrumentation/irrigation. Methodology Single-rooted human premolars were irrigated as follows (n = 12 per group): (1) 1% NaOCl during instrumentation, deionized water after instrumentation, (2) 1% NaOCl during, 17% EDTA after instrumentation, (3) a 1 : 1-mixture of 2% NaOCl and 18% EA during and after instrumentation, and (4) 1% NaOCl during, 2.25% PA after instrumentation. Irrigant volumes and contact times were 10 mL/15 min during and 5 mL/3 min after instrumentation. The evaluated outcomes were eluted calcium by atomic absorption spectroscopy, smear-covered areas by scanning electron microscopy in secondary electron mode and apparent canal wall decalcifications on root transsections in backscatter mode. For the smear layer analysis, sclerotic dentine was taken into consideration. Results were compared using appropriate parametric and nonparametric tests, alpha = 0.05. Results The statistical comparison of the protocols regarding calcium elution revealed that protocol (1) yielded less calcium than (3), which yielded less than protocols (2) and (4). Most of the instrumented canal walls treated with one of the decalcifying agents were free of smear layer. Protocols (1) and (3) caused no decalcification of root dentine, whilst (2) and (4) showed substance typical demineralization patterns. Conclusions The decalcifying agents under investigation were all able to remove or prevent a smear layer. However, they eroded the dentine wall differently.

Irrigant flow within a prepared root canal using various flow rates: a Computational Fluid Dynamics study

Abstract: Aim To study using computer simulation the effect of irrigant flow rate on the flow pattern within a prepared root canal, during final irrigation with a syringe and needle. Methodology Geometrical characteristics of a side-vented endodontic needle and clinically realistic flow rate values were obtained from previous and preliminary studies. A Computational Fluid Dynamics (CFD) model was created using FLUENT 6.2 software. Calculations were carried out for five selected flow rates (0.02–0.79 mL sec−1) and velocity and turbulence quantities along the domain were evaluated. Results Irrigant replacement was limited to 1–1.5 mm apical to the needle tip for all flow rates tested. Low-Reynolds number turbulent flow was detected near the needle outlet. Irrigant flow rate affected significantly the flow pattern within the root canal. Conclusions Irrigation needles should be placed to within 1 mm from working length to ensure fluid exchange. Turbulent flow of irrigant leads to more efficient irrigant replacement. CFD represents a powerful tool for the study of irrigation.

Laser-activated irrigation within root canals: cleaning efficacy and flow visualization.

Abstract: Aim: To test ex vivo the efficiency of laser-activated irrigation in removing dentine debris from the apical part of the root canal and to visualize in vitro the fluid dynamics during the activation of the irrigant by laser, using high-speed imaging at a relevant timescale. - Methodology: Root canals with a standardized groove in one canal wall filled with dentine debris were irrigated with syringe irrigation, ultrasonically or laser-activated irrigation (LAI) using 2% sodium hypochlorite as irrigant. The quantity of dentine debris after irrigation was determined. Visualization of the fluid dynamics during activation was achieved using a high-speed camera and a glass model. - Results: Laser-activated irrigation was significantly more effective in removing dentine debris from the apical part of the root canal than passive ultrasonic irrigation or hand irrigation when the irrigant was activated for 20 s. - Conclusions: The in vitro recordings suggest that streaming, caused by the collapse of the laser-induced bubble, is the main cleaning mechanism of LAI.

Limitations of previously published systematic reviews evaluating the outcome of endodontic treatment

Abstract: The aim of this work was to identify the limitations of previously published systematic reviews evaluating the outcome of root canal treatment. Traditionally, periapical radiography has been used to assess the outcome of root canal treatment with the absence of a periapical radiolucency being considered a confirmation of a healthy periapex. However, a high percentage of cases confirmed as healthy by radiographs revealed apical periodontitis on cone beam computed tomography (CBCT) and by histology. In teeth, where reduced size of the existing radiolucency was diagnosed by radiographs and considered to represent periapical healing, enlargement of the lesion was frequently confirmed by CBCT. In clinical studies, two additional factors may have further contributed to the overestimation of successful outcomes after root canal treatment: (i) extractions and re-treatments were rarely recorded as failures; and (ii) the recall rate was often lower than 50%. The periapical index (PAI), frequently used for determination of success, was based on radiographic and histological findings in the periapical region of maxillary incisors. The validity of using PAI for all tooth positions might be questionable, as the thickness of the cortical bone and the position of the root tip in relation with the cortex vary with tooth position. In conclusion, the serious limitations of longitudinal clinical studies restrict the correct interpretation of root canal treatment outcomes. Systematic reviews reporting the success rates of root canal treatment without referring to these limitations may mislead readers. The outcomes of root canal treatment should be re-evaluated in long-term longitudinal studies using CBCT and stricter evaluation criteria.

Apexification: the beginning of its end.

Abstract: Apexification is a procedure for treating and preserving immature permanent teeth that have lost pulp vitality. It contrasts apexogenesis in terms of its outcome in that apical maturation and normal root thickness cannot be obtained. Apexification has been a routine practice for such teeth for many decades, and despite a literature replete with discussion, including recent artificial barrier methods with mineral trioxide aggregate, ultimately there has been no major breakthrough to improve this treatment. Recently, two new clinical concepts have emerged. One involves a revitalization approach to achieve tissue generation and regeneration. In this method, new living tissue is expected to form in the cleaned canal space, allowing continued root development in terms of both length and thickness. The other is the active pursuit of pulp/dentine regeneration via tissue engineering technology to implant or re-grow pulps. Although the technology is still at its infancy, it has the potential to benefit immature pulpless teeth by allowing continued growth and maturation. With this understanding, it may be predicted that apexification will become less needed in years to come. This study will overview the recent concept of pulp revitalization in the treatment of immature teeth with nonvital pulps and the emerging research on pulp tissue engineering and regeneration.

Dislocation resistance of ProRoot Endo Sealer, a calcium silicate‐based root canal sealer, from radicular dentine

Abstract: Aim To examine the dislocation resistance of three root canal sealers from radicular dentine with and without immersion in a simulated body fluid (SBF), using a modified push-out test design that produced simulated canal spaces of uniform dimensions under identical cleaning and shaping conditions. Methodology Sixty single-rooted caries-free human canine teeth were used. Standardized simulated canal spaces were created using 0.04 taper ProFile instruments along the coronal, middle and apical thirds of longitudinal tooth slabs. Following NaOCl/ethylenediamine tetra-acetic acid cleaning, the cavities were filled with ProRoot Endo Sealer, AH Plus Jet or Pulp Canal Sealer. After setting, half of the cavities were tested with a fibre-optic light-illuminated push-out testing device. The rest were immersed in SBF for 4 weeks before push-out evaluation. Failure modes were examined with stereomicroscopy and field emission (FE)-scanning electron microscopy. Results Location of the sealer-filled cavities did not affect push-out strengths. ProRoot Endo Sealer exhibited higher push-out strengths than the other two sealers particularly after SBF storage (P < 0.001). Failure modes were predominantly adhesive and mixed for Pulp Canal Sealer and AH Plus Jet, and predominantly cohesive for ProRoot Endo Sealer. Spherical amorphous calcium phosphate-like phases that spontaneously transformed into apatite-like phases were seen in the fractured specimens of ProRoot Endo Sealer after SBF storage. Conclusions When tested in bulk without a main core, both ‘sealer type’ and ‘SBF storage’ were significant in affecting push-out results. The ProRoot Endo Sealer demonstrated the presence of spherical amorphous calcium phosphate-like phases and apatite-like phases (i.e. ex vivo bioactivity) after SBF storage.

One step pulp revascularization treatment of an immature permanent tooth with chronic apical abscess: a case report

Abstract: Aim To describe a case in which a mandibular right second premolar with a necrotic pulp, sinus tract, periradicular radiolucency and an immature apex underwent revascularization via a single treatment approach. Summary Revascularization procedures have the potential to heal a partially necrotic pulp, which can be beneficial for the continued root development of immature teeth. However, it is not clear which revascularization protocols are the most effective. This case report details the outcome of a successful revascularization procedure on tooth 45 (FDI) in a 12-year-old patient, eliminating the associated periapical pathosis within 19 months. The tooth was treated using coronal root irrigation with 6% NaOCl and 2% chlorhexidine without instrumentation in a single visit. The successful outcome of this case report suggests that this conservative revascularization treatment approach can preserve the vitality of the dental pulp stem cells and create a suitable environment for pulp regeneration, resulting in the completion of root maturation. Key learning points • The noninstrumentation procedure using 6% NaOCl and 2% chlorhexidine coronal irrigation may help preserve the remaining vital dental pulp stem cells believed to be critical for pulp revascularization. • A single visit pulp revascularization protocol can be a favourable treatment option for an immature permanent tooth with a partially necrotic pulp.

Antibiotic prescribing in dental practice in Belgium.

Abstract: Mainjot A, D’Hoore W, Vanheusden A, Van Nieuwen-huysen J-P. Antibiotic prescribing in dental practice inBelgium. International Endodontic Journal, 42, 1112–1117, 2009. Aim To assess the types and frequency of antibioticprescriptions by Belgian dentists, the indications forantibiotic prescription, and dentists’ knowledge aboutrecommended practice in antibiotic use.Methodology In this cross-sectional survey, dentalpractitioners were asked to record information about allantibiotics prescribed to their patients during a 2-weekperiod. The dental practitioners were also asked tocomplete a self-administered questionnaire regardingdemographic data, prescribing practices, and knowl-edge about antibiotic use. A random sample of 268Belgian dentists participated in the survey.Results During the 2-week period, 24 421 patientencounters were recorded; 1033 patients were pre-scribed an antibiotic (4.2%). The median number ofprescriptions per dentist for the 2 weeks was 3. Broadspectrum antibiotics were most commonly prescribed:82% of all prescriptions were for amoxycillin, amoxy-cillin-clavulanic acid and clindamycin. Antibiotics wereoften prescribed in the absence of fever (92.2%) andwithout any local treatment (54.2%). The mostfrequent diagnosis for which antibiotics were prescribedwas periapical abscess (51.9%). Antibiotics were pre-scribed to 63.3% of patients with periapical abscess and4.3% of patients with pulpitis. Patterns of prescriptionswere confirmed by the data from the self-reportedpractice.Conclusions Discrepancies between observed andrecommended practice support the need for educationalinitiatives to promote rational use of antibiotics indentistry in Belgium.Keywords: antibiotics, audit, dentistry, drug usereview, prescription.

Rubber dam usage for endodontic treatment: a review.

Abstract: Rubber dam has been available to the dental profession for over 140 years. During this time, the use of rubber dam has been perfected, universally taught and recommended by professional organizations. Unfortunately, its consistent use has been rejected by many in the profession. The literature suggests that rubber dam is not used routinely by dental practitioners for root canal treatment. Many unfounded reasons have been cited for its lack of use, including concerns over patient acceptance, time required for application, cost of equipment and materials, insufficient training, difficulty in use and low treatment fees. Failure to use rubber dam has been shown to influence the choice of root canal irrigant, has a negative impact on treatment outcome and places the patient at risk of swallowing or aspirating materials and instruments. Methods to popularize rubber dam amongst general practitioners are discussed.

A comparative study of physicochemical properties of AH Plus, Epiphany, and Epiphany SE root canal sealers.

Abstract: MD. A comparative study of physicochemical properties of AH Plus, Epiphany, and Epiphany SE root canal sealers. International Endodontic Journal, 42, 785–793, 2009. Aim To assess the physicochemical properties and the surface morphology of AH Plus, Epiphany, and Epiphany SE root canal sealers. Methodology Five samples of each material were employed for each test according to ANSI/ADA specification 57. The samples were assigned to four groups: (i) AH Plus; (ii) Epiphany; (iii) Epiphany + Thinning Resin; (iv) Epiphany SE. The distilled water used during the solubility test was submitted to spectrometry to verify the release of calcium ions. The morphologies of the external surface and the cross-section of the samples were analysed by means of a scanning electron microscope (SEM). Statistical analysis was performed by using One-Way anova and post hoc Tukey–Kramer tests with the null hypothesis set as 5%. Results Setting time, flow and radiopacity results were in accordance with ANSI/ADA requirements whereas the dimensional change of all sealers and solubility of Epiphany did not fulfil ANSI/ADA protocols. AH Plus and Epiphany SE were similar in terms of flow, radiopacity, solubility and dimensional change. The spectrometry test revealed significant calcium ion release from Epiphany with and without the thinning resin. SEM analysis revealed essentially a homogeneous surface with compact layer and some rough areas. Conclusions Setting time, flow, and radiopacity tests conformed to ANSI/ADA standardization. The dimensional change in all groups and the solubility of Epiphany were greater than values considered acceptable, with higher amounts of calcium ion release. Epiphany SE revealed more organized, compacted, and homogeneous polymers in a reduced resin matrix when compared with the other groups.

Effectiveness of ozone against endodontopathogenic microorganisms in a root canal biofilm model.

Abstract: Aim To assess the antimicrobial efficacy of aqueous (1.25-20 microg mL(-1)) and gaseous ozone (1-53 g m(-3)) as an alternative antiseptic against endodontic pathogens in suspension and a biofilm model. Methodology Enterococcus faecalis, Candida albicans, Peptostreptococcus micros and Pseudomonas aeruginosa were grown in planctonic culture or in mono-species biofilms in root canals for 3 weeks. Cultures were exposed to ozone, sodium hypochlorite (NaOCl; 5.25%, 2.25%), chlorhexidine digluconate (CHX; 2%), hydrogen peroxide (H(2)O(2); 3%) and phosphate buffered saline (control) for 1 min and the remaining colony forming units counted. Ozone gas was applied to the biofilms in two experimental settings, resembling canal areas either difficult (setting 1) or easy (setting 2) to reach. Time-course experiments up to 10 min were included. To compare the tested samples, data were analysed by one-way anova. Results Concentrations of gaseous ozone down to 1 g m(-3) almost and aqueous ozone down to 5 microg mL(-1) completely eliminated the suspended microorganisms as did NaOCl and CHX. Hydrogen peroxide and lower aqueous ozone concentrations were less effective. Aqueous and gaseous ozone were dose- and strain-dependently effective against the biofilm microorganisms. Total elimination was achieved by high-concentrated ozone gas (setting 2) and by NaOCl after 1 min or a lower gas concentration (4 g m(-3)) after at least 2.5 min. High-concentrated aqueous ozone (20 microg mL(-1)) and CHX almost completely eliminated the biofilm cells, whilst H(2)O(2) was less effective. Conclusion High-concentrated gaseous and aqueous ozone was dose-, strain- and time-dependently effective against the tested microorganisms in suspension and the biofilm test model.

Root and canal morphology of mandibular first and second molar teeth in a Jordanian population

Abstract: Aim To examine the root and canal morphology of mandibular permanent first and second molar teeth in a Jordanian population. Methodology A total of 685 extracted mandibular first and second permanent molar teeth were collected from dental clinics within north Jordan. The teeth were examined visually and the root number and morphology were recorded. After that, access cavities were prepared, pulp tissue dissolved by sodium hypochlorite and the root canals injected with Indian ink. Stained teeth were decalcified with 10% nitric acid, dehydrated with ascending concentrations of alcohol and rendered clear by immersion in methyl salicylate. The following observations were evaluated: (i) number of canals per root; (ii) number of root canals per tooth; (iii) canal configuration in each root; (iv) number and location of lateral canals and (v) presence of intercanal communications. Results Of 330 mandibular first molars, the majority had three (48%) or four (46%) canals, whilst 4% had a third disto-lingual root. Of 355 mandibular second molars, 58% had three canals, 19% two and 17% had four canals, whilst 10% had C-shaped roots. The most prevalent canal configuration in the mesial root of both first (53%) and second (40%) molars was type IV, and in distal roots was type I (54% in first and 79% in second molars). Conclusions Jordanian mandibular first and second molar teeth exhibit features close to the average Caucasian root and canal morphology.

Mechanical response of nickel-titanium instruments with different cross-sectional designs during shaping of simulated curved canals.

Abstract: Aim To evaluate how different cross-sectional designs affect stress distribution in nickel–titanium (NiTi) instruments during bending, torsion and simulated shaping of a curved canal. Methodology Four NiTi rotary instruments with different cross-sectional geometries were selected: ProFile and HeroShaper systems with a common triangle-based cross section, Mtwo with an S-shaped rectangle-based design and NRT with a modified rectangle-based design. The geometries of the selected files were scanned in a micro-CT and three-dimensional finite-element models were created for each system. Stiffness characteristics for each file system were determined in a series of bending and torsional conditions. Canal shaping was simulated by inserting models of the rotating file into a 45° curved canal model. Stress distribution in the instruments was recorded during simulated shaping. After the instruments were retracted from the canal, residual stresses and permanent bending of their tips due to plastic deformation were determined. Results The greatest bending and torsional stiffness occurred in the NRT file. During simulated shaping, the instruments with triangle-based cross-sectional geometry had more even stress distributions along their length and had lower stress concentrations than the instruments with rectangle-based cross sections. Higher residual stresses and plastic deformations were found in the Mtwo and NRT with rectangle-based cross-sectional geometries. Conclusions Nickel–titanium instruments with rectangle-based cross-sectional designs created higher stress differentials during simulated canal shaping and may encounter higher residual stress and plastic deformation than instruments with triangle-based cross sections.

Articaine buccal infiltration enhances the effectiveness of lidocaine inferior alveolar nerve block.

Abstract: Aim To compare mandibular tooth pulpal anaesthesia and reported discomfort following lidocaine inferior alveolar nerve block (IANB) with and without supplementary articaine buccal infiltration. Methodology In this prospective randomized double-blind cross-over study, thirty-six healthy adult volunteers received two IANB injections of 2 mL lidocaine 2% with epinephrine 1 : 80 000 over two visits. At one visit, an infiltration of 2 mL of articaine 4% with epinephrine 1 : 100 000 was administered in the mucobuccal fold opposite a mandibular first molar. At the other visit, a dummy injection was performed. Injection discomfort was recorded on 100 mm visual analogue scales. Pulpal anaesthesia of first molar, premolar, and lateral incisor teeth was assessed with an electronic pulp tester until 45 min post-injection. A successful outcome was recorded in the absence of sensation on two or more consecutive maximal pulp tester stimulations. Data were analysed using McNemar and Student’s t-tests. Results The IANB with supplementary articaine infiltration produced more success than IANB alone in first molars (33 volunteers vs. 20 volunteers respectively, P < 0.001), premolars (32 volunteers vs. 24 volunteers respectively, P = 0.021) and lateral incisors (28 volunteers vs. 7 volunteers respectively, P < 0.001). Buccal infiltration with articaine or dummy injection produced less discomfort than IANB injection (t = 4.1, P < 0.001; t = 3.0, P = 0.005 respectively). Conclusions The IANB injection supplemented with articaine buccal infiltration was more successful than IANB alone for pulpal anaesthesia in mandibular teeth. Articaine buccal infiltration or dummy buccal infiltration was more comfortable than IANB.

Ex vivo study on root canal instrumentation of two rotary nickel–titanium systems in comparison to stainless steel hand instruments

Abstract: Aim To investigate instrumentation time, working safety and the shaping ability of two rotary nickel–titanium (NiTi) systems (Alpha System and ProTaper Universal) in comparison to stainless steel hand instruments. Methodology A total of 45 mesial root canals of extracted human mandibular molars were selected. On the basis of the degree of curvature the matched teeth were allocated randomly into three groups of 15 teeth each. In group 1 root canals were prepared to size 30 using a standardized manual preparation technique; in group 2 and 3 rotary NiTi instruments were used following the manufacturers’ instructions. Instrumentation time and procedural errors were recorded. With the aid of pre- and postoperative radiographs, apical straightening of the canal curvature was determined. Photographs of the coronal, middle and apical cross-sections of the pre- and postoperative canals were taken, and superimposed using a standard software. Based on these composite images the portion of uninstrumented canal walls was evaluated. Results Active instrumentation time of the Alpha System was significantly reduced compared with ProTaper Universal and hand instrumentation (P < 0.05; anova). No instrument fractures occurred in any of the groups. The Alpha System revealed significantly less apical straightening compared with the other instruments (P < 0.05; Mann–Whitney U test). In the apical cross-sections Alpha System resulted in significantly less uninstrumented canal walls compared with stainless steel files (P < 0.05; chi-squared test). Conclusion Despite the demonstrated differences between the systems, an apical straightening effect could not be prevented; areas of uninstrumented root canal wall were left in all regions using the various systems.

Root canal morphology of the mesiobuccal root of maxillary first molars: a micro-computed tomographic analysis

Abstract: Somma F, Leoni D, Plotino G, Grande NM, Plasschaert A. Root canal morphology of the mesiobuccal root of maxillary first molars: a micro-computed tomographic analysis. International Endodontic Journal, 42, 165‐174, 2009. Aim To investigate ex vivo, the root canal morphology of the MB root of maxillary first molar teeth by means of micro-computed tomography. Methodology Thirty extracted intact human maxillary first molar teeth were selected for micro-tomographic analysis (SkyScan 1072, Aartselaar, Belgium) with a slice thickness of 38.0 lm. The following data regarding the MB root were analysed and recorded: number and type of root canals, prevalence of isthmuses, prevalence of intercanal connections, presence of accessory canals, presence of loops and number of apical foramina. Results The MB2 canal was present in 80% of specimens and was independent in 42% of these cases. When present, the MB2 canal merged with the MB1 canal in 58% of cases. Communications between the two canals were found in all specimens, with isthmuses in 71% of the cases. These communications and isthmuses were respectively in 42% and 54% of the cases in the coronal third, in 59% and 79% of the cases in the middle third and in 24% and 50% of the cases in the apical third. A single apical foramen was found in 37% of specimens, two apical foramina were present in 23% of the cases, with three or more separate apical foramina occurring in 40% of the specimens. Conclusions The MB root canal anatomy was complex: a high incidence of MB2 root canals, isthmuses, accessory canals, apical delta and loops was found.

The mysterious appearance of enterococci in filled root canals.

Abstract: In this narrative review, the potential reasons for the high occurrence of enterococci in filled root canals are explored. The pulpless root canal appears to be a habitat for these bacteria, particularly for Enterococcus faecalis. However, re-surveying the literature in caries research, it can be concluded that, contrary to earlier belief, enterococci are rare if ever found at the advancing front of dentinal lesions. The same is the case for true primary endodontic infections, but some uncertainty remains, because the coronal seal and the history of teeth harbouring enterococci have rarely been accurately investigated. Furthermore, from longitudinal studies with a known infection at the initiation of treatment, which was carried out under controlled asepsis, it is questionable whether enterococci are as difficult to eliminate from the canal system as is commonly held. A more likely explanation for the high occurrence of enterococci in filled root canals is that they enter after treatment, but from which source? The intriguing finding in this context is that enterococci do not appear to be colonizers of the oral cavity. They are merely transient oral bacteria, unless there is a predilection site such as the unsealed necrotic or filled root canal. The origin of this infection is most likely food. Using the example of enterococci in filled root canals, this paper highlights the possible importance of transient microorganisms in the oral cavity and changes in a microenvironment that can create favourable conditions for infection.

On the local applications of antibiotics and antibiotic‐based agents in endodontics and dental traumatology

Abstract: Mohammadi Z, Abbott PV. On the local applications ofantibiotics and antibiotic-based agents in endodontics anddental traumatology. International Endodontic Journal, 42,555–567, 2009. Antibiotics are a valuable adjunctive to the armamen-tarium available to health professionals for the man-agement of bacterial infections. During endodontictreatment and when managing trauma to the teeth,antibiotics may be applied systemically (orally and/orparenterally) or locally (i.e. intra-dentally via irrigantsand medicaments). Due to the potential risk of adverseeffects following systemic application, and the ineffec-tiveness of systemic antibiotics in necrotic pulplessteeth and the periradicular tissues, the local applicationof antibiotics may be a more effective mode for deliveryin endodontics. The aim of this article was to review thehistory, rationale and applications of antibiotic-containing irrigants and medicaments in endodonticsand dental traumatology. The search was performedfrom 1981 to 2008 and was limited to English-language papers. The keywords searched on Medlinewere ‘Antibiotics AND endodontics’, ‘Antibiotics ANDroot canal irrigation’, ‘Antibiotics AND intra-canalmedicament’, ‘Antibiotics AND Dental trauma’ and‘Antibiotics AND root resorption’. The reference sectionof each article was manually searched to find othersuitable sources of information. It seems that localroutes of antibiotic administration are a more effectivemode than systemic applications. Various antibioticshave been tested in numerous studies and each hassome advantages. Tetracyclines are a group of bacte-riostatic antibiotics with antibacterial substantivity forup to 12 weeks. They are typically used in conjunctionwith corticosteroids and these combinations have anti-inflammatory, anti-bacterial and anti-resorptive prop-erties, all of which help to reduce the periapicalinflammatory reaction including clastic-cell mediatedresorption. Tetracyclines have also been used as part ofirrigating solutions but the substantivity is only for4 weeks. Clindamycin and a combination of threeantibiotics (metronidazole, ciprofloxacin and minocy-cline) have also been reported to be effective atreducing bacterial numbers in the root canal systemsof infected teeth.Keywords: antibiotics, endodontics, irrigants, medi-caments.

Effect of acid-etching procedure on selected physical properties of mineral trioxide aggregate.

Abstract: P>Aim To evaluate the effect of acid-etch procedures on the compressive strength and surface microhardness of tooth-coloured mineral trioxide aggregate (MTA). Methodology White ProRoot MTA (Dentsply Tulsa Dental) was mixed and packed into cylindrical tubes of 4 mm in diameter and 6 mm in height. Three groups, each of 15 specimens were subjected to an acid-etch procedure either 4, 24 or 96 h after mixing. The compressive strength was measured and compared with unetched control groups. Differences between groups were analysed using the Kruskall-Wallis test. A further batch of cylindrical specimens of 6 mm in diameter and 12 mm in height were prepared for testing surface microhardness. Three groups of 15 specimens were subjected to the acid-etch procedure at either 4, 24 or 96 h following mixing. Data were subjected to one-way anova. Changes in the surface microstructure before and after the acid-etch procedures were analysed using a scanning electron microscope (SEM). Results There was a general trend for the compressive strength and surface microhardness of specimens to increase with time. In terms of compressive strength, the increase was significant between 4 h and the other time periods for both experimental and control groups (P < 0.0001); however, there was no significant difference between 24 and 96 h. The increase in surface microhardness was significant between 4, 24 and 96 h (P < 0.0001). In addition, there was a significant difference between experimental and control groups at all time periods (P < 0.0001). SEM examination revealed morphological differences between the intact and the etched MTA surfaces. Conclusions Acid-etch procedures affected the compressive strength and surface microhardness of ProRoot MTA. This indicates that it may be better to postpone restorative procedures for at least 96 h after mixing MTA. Etching created surface changes that might have the potential to enhance bonding of resinous materials.

Necrotic pulp tissue dissolution by passive ultrasonic irrigation in simulated accessory canals: impact of canal location and angulation

Abstract: AIM: To evaluate whether passive ultrasonic irrigation (PUI) of 2.5% NaOCl would dissolve necrotic pulp tissue from simulated accessory root canals (SACs) better than passive placement of the irrigant, when temperature was equilibrated between the two treatments. METHODOLOGY: Transparent root canal models (n = 6) were made from epoxy resin. SACs of 0.2 mm diameter were placed at defined angles and positions in the mid-canal and apical area. SACs were filled with necrotic bovine pulp tissue. PUI was performed five times for 1 min each with irrigant replenishment after every minute. Main canal temperature was measured after each minute, and a digital photograph was taken. In control experiments, mock treatments were performed with the same set-up without activation of the file using heated NaOCl to mimic the temperature created by PUI. Experiments were repeated five times. Digital photographs were analysed for the distance of dissolved tissue into the SACs in mm. Overall comparison (sum of dissolved tissue from all five accessory canals) between treatments was performed using paired t-test. Differences between SAC angulation and position after PUI were investigated using anova/Bonferroni (alpha < 0.05). RESULTS: Passive ultrasonic irrigation caused a rise in irrigant temperature in the main canal to 53.5 +/- 2.7 degrees C after the fifth minute. PUI dissolved a total of 6.4 +/- 2.1 mm, mock treatment controlled for heat: 1.4 +/- 0.6 mm (P < 0.05). No significant influence of SAC position or angulation was found. CONCLUSIONS: Passive ultrasonic irrigation promotes positive tissue-dissolving effects beyond a rise in irrigant temperature.

Effectiveness of different laser systems to kill Enterococcus faecalis in aqueous suspension and in an infected tooth model.

Abstract: To assess the antibacterial action of laser irradiation (Nd:YAG, KTP), photo activated disinfection (PAD) and 2.5% sodium hypochlorite (NaOCl) on Enterococcus faecalis, in an aqueous suspension and in an infected tooth model. Root canals of 60 human teeth with single straight canals were prepared to apical size 50, autoclaved, inoculated with an E. faecalis suspension and incubated for 48 h. They were randomly allocated to four treatment and one control groups. After treatment, the root canals were sampled by flushing with physiological saline, and the number of surviving bacteria in each canal was determined by plate count and solid phase cytometry. The same experimental or control treatments were completed on aqueous suspensions of E. faecalis, and the number of surviving bacteria was determined in the same way. In aqueous suspension, PAD and NaOCl resulted in a significant reduction in the number of E. faecalis cells (P < 0.001), whilst Nd:YAG or KTP had no effect. In the infected tooth model, only the PAD and NaOCl treated teeth yielded significantly different results relative to the untreated controls (P < 0.001). The laser systems as well as PAD were less effective than NaOCl in reducing E. faecalis, both in aqueous suspension and in the infected tooth model.

Endodontics or implants? A review of decisive criteria and guidelines for single tooth restorations and full arch reconstructions.

Abstract: This review describes practical criteria and a systematic process to aid the treatment planning decision of whether to preserve teeth by root canal treatment (RCT) or extract and provide an implant. Recommendations presented are based on best available evidence from the literature and the expert views of specialists in endodontics and restorative dentistry, including dental implantology. A MEDLINE search was conducted using the terms 'root canal therapy', 'dental implants', 'decision making', 'treatment planning', 'outcome' and 'human', and supplemented by hand-searching. When evaluating the outcome of root canal treatment, an observation period of 4-5 years is required for complete healing of periapical lesions. Dental implants, however, present a de novo situation and a functional period of at least 5 years is often required before peri-implant diseases are established and detected. Good long-term success rates and greater flexibility in clinical management indicate that RCT or retreatment should be performed first in most instances unless the tooth is judged to be unrestorable. When deciding if a compromised tooth of questionable prognosis should be maintained or replaced by an implant, both local, site-specific and more general patient-related factors should be considered. Following systematic evaluation and consideration of the best treatment option in a particular case, a treatment recommendation may then be given in favour or against tooth retention. Whilst single risks are possibly accepted for single tooth restorations, teeth with questionable prognosis and multiple pre-treatment requirements are better not included as abutments in fixed dental prostheses to reduce the risk to survival of the entire restoration.

Stress distribution of three NiTi rotary files under bending and torsional conditions using a mathematic analysis

Abstract: Aim To compare and evaluate the stress distribution of three NiTi instruments of various cross-sectional configurations under bending or torsional condition using a finite-element analysis model. Methodology Three NiTi files (ProFile, ProTaper and ProTaper Universal) were scanned using Micro-CT to produce a three-dimensional digital model. The behaviour of the instrument under bending or torsional loads was analysed mathematically in software (ABAQUS V6.5-1), taking into consideration the nonlinear mechanical characteristic of NiTi material. Results ProFile showed the greatest flexibility, followed by ProTaper Universal and ProTaper. The highest stress was observed at the surface near the cutting edge and the base of (opposing) flutes during cantilever bending. Concentration of stresses was observed at the bottom of the flutes in ProFile and ProTaper Universal instruments in torsion. The stress was more evenly distributed over the surface of ProTaper initially, which then concentrated at the middle of the convex sides when the amount of angular deflection was increased. Conclusion Incorporating a U-shaped groove in the middle of each side of the convex-triangular design lowers the flexural rigidity of the origin ProTaper design. Bending leads to the highest surface stress at or near the cutting edge of the instrument. Stress concentration occurs at the bottom of the flute when the instrument is subjected to torsion.