Cyclic and Torsional Fatigue Resistance of Seven Rotary Systems.

Introduction: This study aims to evaluate the cyclic and torsional fatigue resistance of seven rotary systems. Methods and Materials: A total of 140 instruments were tested, 20 of each system including Genius (GN) 25/0.04, TruShape (TS) 25/0.06, Logic (LOG) 25/0.06 taper, Vortex Blue (VB) 25/0.06, ProTaper Gold (PTG) 25/0.08, Hyflex CM (HCM) 25/0.06 and Hyflex EDM (EDM) 25/0.08 taper. Cyclic fatigue resistance testing was performed using an artificial stainless steel canal with a curvature (60° angle and 5-mm radius) located at 5 mm from the tip. The files (n=10) rotated until fracture, and time was recorded in seconds. The torsional test was evaluated according to ISO 3630-1. Data were analysed with one-way ANOVA and Tukey's tests (α=5%). The fractured surface of the instruments were assessed using scanning electron microscopy to confirm the type of fracture. Results: The cyclic fatigue resistance value of EDM was significantly higher than those of all tested instruments (P<0.05). LOG showed a higher cyclic fatigue resistance than GN or TS (P<0.05). There was no difference among the other groups (P>0.05). The torsional test showed that PTG 25/0.08 had the highest torsional strength value of all instruments tested followed by VB and EDM (P<0.05). The LOG showed significant difference only with GN (P<0.05). No difference was found among the other groups (P>0.05). In relation to angular deflection, the GN; TS; HCM, and EDM showed significantly higher values until fracture than the other groups (P<0.05). No difference was found among PTG, LOG, and VB (P>0.05). Conclusion: Our in vitro study EDM group had the highest cyclic fatigue resistance among all the tested instruments. For the torsional test, the PTG showed highest torsional strength and lowest angular deflection values.

The MB3 canal in maxillary molars: a micro-CT study.

OBJECTIVES: To assess the internal and external morphologies of the mesiobuccal (MB) root of maxillary molars presenting a third root canal (MB3), using micro-computed tomography (micro-CT). MATERIAL AND METHODS: Two-hundred and sixty-five extracted maxillary first and second molars with different root configurations were imaged in a micro-CT scanner at 19.6-µm pixel size. Sixteen teeth presenting MB3 canal were selected and evaluated regarding root configuration, minimal dentine thickness 2 mm under the furcation area, canal configuration of the MB root, MB3 canal morphology (location, independent or confluent orifice, and anatomy types), and the apical anatomy (aspect ratio, number of accessory canals and foramina, presence of isthmus, and independent MB3 foramen). RESULTS: Overall, a high variability in canal configuration was detected in the MB root. MB3 canal was observed in 10 maxillary first molars and 6 maxillary second molars (n = 16). Minimal dentine thickness related to the MB3 canal at the coronal third was smaller than that of the MB1 canal. A complex internal anatomy comprising 13 different root canal configurations was observed. A high number of independent MB3 orifices at the pulp chamber floor was observed in the first molars (7 out of 10 teeth), while most of the specimens (n = 14) showed a confluent anatomy of the MB3 canal. A varied number of accessory canals and foramina were observed. At the apical third, isthmus could be observed in 6 specimens, while an independent MB3 foramen was present in 37.5% of the MB roots. CONCLUSIONS: MB3 canal is a rare anatomical variation present in maxillary first and second molars. Its presence can be associated to a complex internal anatomy of the MB root which includes the presence of isthmuses and multiple accessory canals and foramina at the apical third, but also a thin dentine thickness at the coronal third and a confluent anatomy of the MB3 with the other main canals.

Laser therapy as an adjunct in the treatment of sodium hypochlorite extrusion through a root perforation: a case report.

Accidental sodium hypochlorite extrusion can occur during endodontic irrigation procedures. The symptoms appear immediately and include severe pain, swelling, and probable tissue necrosis adjacent to the root of the treated tooth. Treatment of sodium hypochlorite extrusion involves immediate and copious saline irrigation to neutralize the area and prescription of analgesic, anti-inflammatory, and antibiotic medications. Low-level laser therapy (LLLT) might be useful as an adjuvant treatment for damaged soft tissues to improve healing. This case report describes the treatment of accidental extrusion of 1% sodium hypochlorite through a root canal perforation in a mandibular incisor during endodontic treatment. The extrusion caused minor swelling within the mentolabial sulcus and a large area of necrosis in the gingivolabial mucosa and right edentulous premolar area. Conventional treatment was performed in association with LLLT. Clinical and radiographic examinations after 6 months showed complete healing of the necrotic area without paresthesia and the repair of apical tissues.

Cyclic and Torsional Fatigue Resistance of Reciprocating Single Files Manufactured by Different Nickel-titanium Alloys.

INTRODUCTION: The aim of this study was to evaluate the cyclic and torsional fatigue resistance of the following reciprocating single-file systems: ProDesign R 25.06 (Easy Equipamentos Odontológicos, Belo Horizonte, Brazil), Reciproc R25 (VDW GmbH, Munich, Germany), and Unicone L25 (Medin SA, Nové Mesto in Morave, Czech Republic). METHODS: Sixty instruments of the ProDesign R, Reciproc R25, and Unicone L25 systems (n = 20) were used. Cyclic fatigue resistance was tested measuring the time to failure in an artificial stainless steel canal with a 60° angle and a 5-mm radius of curvature (n = 10). Torque and angle of rotation at failure of new instruments (n = 10) in the 3 mm from the tip portion were measured during torsional testing according to ISO 3630-1. The fractured surface of each fragment was examined by scanning electron microscopy. Data were analyzed using 1-way analysis of variance and Tukey tests, and the level of significance was set at 5%. RESULTS: The cyclic fatigue resistance values of ProDesign R 25.06 were significantly higher than the other groups (P < .05). Reciproc R25 showed higher fatigue resistance than Unicone L25 (P < .05). In relation to the torsional test, the ProDesign R 25.06 and Unicone L25 systems showed higher angular rotation until fracture than Reciproc R25 (P < .05). However, Reciproc R25 and Unicone L25 showed higher torque load than ProDesign R 25.06 (P < .05). Scanning electron microscopic analysis showed similar and typical features of cyclic and torsional failure for all instruments tested. CONCLUSIONS: ProDesign R presented the highest cyclic fatigue resistance and angular rotation to failure compared with Reciproc and Unicone. However, Reciproc showed higher torsional strength to failure.

Respuesta inflamatoria de Bioceramic a la implantación de tubos de dentina en tejido subcutáneo de ratas / Inflammatory response of Bioceramic material to dentin tube implantation in rats' subcutaneous tissue

El propósito fue evaluar la respuesta inflamatoria a la implantación del material Bioceramic en tejido subcutáneo de ratas. Se utilizaron nueve ratas machos Wistar (Rattus norvegicus) a las que les implantaron cuatro tubos de dentina rellenos con cemento sellador Bioceramic y un tubo vacío como grupo control. Se analizaron en tres periodos de tiempo (96 horas, 10 y 21 días). Los animales fueron sacrificados por sobredosis y las muestras obtenidas se procesaron mediante tinción con hematoxilina y eosina para ser analizadas microscópicamente. Los resultados mostraron a las 96 horas inflamación moderada en 75% y severa en 25%. 10 días después disminuyó la inflamación de moderada (67%) a severa (25%). En el periodo final de 21 días se observó inflamación moderada a leve (50%). Se concluye que existió inflamación de moderada a severa en los periodos iniciales, disminuyó a leve en el último periodo. Bioceramic presenta una aceptable respuesta biológica en tejido subcutáneo de ratas.

The aim of the present article was to assess inflammatory response caused by implantation of Bioceramic material in rats' subcutaneous tissue. Nine male Wistar rats were used (Rattus Norvegicus) to which four dentin tubes filled with Bioceramic sealing cement material and one empty tube (control group) were implanted. Results were analyzed in three time periods (96 hours, 10 and 21 days). Animals were sacrificed by anesthetic overdose. Obtained samples were processed by hematoxylin and eosin staining in order to be analyzed with microscope. Results after 96 hours revealed moderate inflammation in 75% of all cases and severe inflammation in 25% of all cases. Ten days later, inflammation decreased from moderate (67%) to mild (25%). At the final period of 21 days, moderate to mild inflammation was observed (50%). It was concluded that there was presence of moderate to severe inflammation at initial periods which decreased to mild inflammation at the final period. «Bioceramic¼ brand material exhibits acceptable biological response in rats' subcutaneous tissues.

Unicone: um novo sistema reciprocante para preparo dos canais radiculares / Unicone: a new reciprocating system for root canal shaping

O preparo biomecânico é uma das etapas mais importantes para o sucesso do tratamento endodôntico. A instrumentação mecanizada revolucionou o preparo dos canais radiculares, proporcionando preparos rápidos, demandando menor tempo clínico e menor estresse ao operador. A cinemática reciprocante surgiu como alternativa a rotação continua, utilizando menor número de instrumentos para o preparo, menor tempo e menor curva de aprendizado. Na atualidade tem sido dado um destaque especial aos sistemas reciprocantes sendo representados pelo Reciproc e Wave-One. A Medin apresentou um novo sistema reciprocante, o sistema Unicone. O objetivo deste artigo é a apresentação desse novo sistema, suas vantagens e performance na realização do tratamento endodôntico.

Mechanical preparation is one of the most important steps for successful endodontic treatment. The mechanized instrumentation modernized the root canals treatment, providing fast preparations and requiring less clinical time and less stress to the operator. The reciprocating kinematics emerged as an alternative to continuous rotation, using less instruments and less time to prepare the root canal system. It also shortens the learning curve. Currently has been given a special emphasis on reciprocating systems being represented by Reciproc and Wave-One files. The Medin introduced a new reciprocating system called Unicone. The purpose of this article is to presentate this new system, its advantages and performance in accomplishing the endodontic treatment.

Regeneração óssea em alvéolos de ratos após enxerto de osso bovino inorgânico medular e biocerâmica sintética densa / Alveolar bone regeneration in rats after grafting of anorganic bovine bone and thick synthetic bioceramic

Introdução: é incerto se o uso de biomateriais em cirurgiasparendodônticas é capaz de facilitar ou induziro processo de regeneração óssea. Esse estudo analisou,comparativamente, os efeitos do preenchimento de alvéolosde ratos com osso bovino inorgânico medular euma biocerâmica sintética densa no processo de regeneraçãoóssea. Material: Quarenta e oito ratos albinosWistar foram distribuídos, aleatoriamente, em três grupos,que, após a extração dentária, tiveram os alvéolos preenchidosda seguinte forma: GI (n = 12) coágulo (controle);GII (n = 18) osso bovino inorgânico medular; GIII (n = 18)biocerâmica sintética densa. As amostras foram obtidasem 7, 15 e 30 dias pós-cirurgia. Foram realizadas análisesmicroscópicas quantitativas do infiltrado inflamató-rio, densidade fibroblástica, densidade angioblástica eneoformação óssea. Os dados foram submetidos ao testede Kruskal-Wallis (α < 0,05) para detectar diferenças entreos grupos no mesmo intervalo de tempo. Resultados:apesar de terem sido detectadas algumas diferenças entreos grupos experimentais e o controle para infiltrado inflamatórioe densidade angioblástica em 07 dias, e formaçãoóssea em 15 dias, no período de 30 dias o processo de reparofoi semelhante para todos os grupos. Conclusões:não houve diferença entre os dois materiais empregados,os quais não atrasaram o processo de regeneração óssea,e, se usados em cirurgias parendodônticas, podem atuarcomo materiais osteocondutores e osteopreenchedoresnos grandes defeitos ósseos.

O uso dos localizadores foraminais na endodontia: revisão de literatura / The use of apex locator in endodontics: a literature review

A correta determinação do comprimento real de trabalho (CRT) é um fator importante que corrobora no sucesso do tratamento endodôntico. Diversos estudos mostram que o uso de localizadores foraminais eletrônicos é recomendado devido à sua eficácia e benefícios quando utilizados na terapia endodôntica. O princípio de ação desses aparelhos está relacionado às propriedades que os tecidos orais apresentam quando submetidos a diversos componentes elétricos como resistência, frequência e impedância. Os localizadores foraminais podem ser utilizados em diversas situações na prática clínica, como nos tratamentos de dentes vitais e não vitais até nos casos de retratamentos. O objetivo deste estudo é analisar por meio de revisão da literatura a eficácia dos localizadores foraminais eletrônicos na determinação do comprimento real de trabalho durante a realização do tratamento endodôntico.

An important operatory stage that can determine the success of the endodontic treatment is the correct determination of the real working length. Several studies recommended the use of apex locators due to their effectiveness and benefits when they were used in endodontic therapy. The operating principles of these devices are related to the oral tissues properties when submitted to different electrical components such as resistance, frequency and impedance. Apex locators can be used in a variety of clinical situations, such as vital or non-vital teeth and retreatment. The aim of this study was to analyze the literature regarding the effectiveness of apex locators in endodontic treatments under different situations and compares their accuracy in determination of the apical foramen location.

The antimicrobial effect of new and conventional endodontic irrigants on intra-orally infected dentin.

OBJECTIVES: To evaluate if the incorporation of antimicrobial compounds to chelating agents or the use of chelating agents with antimicrobial activity as 7% maleic acid and peracetic acid show similar disinfection ability in comparison to conventional irrigants as sodium hypochlorite or iodine potassium iodide against biofilms developed on dentin. MATERIALS AND METHODS: The total bio-volume of live cells, the ratio of live cells and the substratum coverage of dentin infected intra-orally and treated with the irrigant solutions: MTAD, Qmix, Smear Clear, 7% maleic acid, 2% iodine potassium iodide, 4% peracetic acid, 2.5% and 5.25% sodium hypochlorite was measured by using confocal microscopy and the live/dead technique. Five samples were used for each irrigant solution. RESULTS: Several endodontic irrigants containing antimicrobials as clorhexidine (Qmix), cetrimide (Smear Clear), maleic acid, iodine compounds or antibiotics (MTAD) lacked an effective antibiofilm activity when the dentin was infected intra-orally. The irrigant solutions 4% peracetic acid and 2.5-5.25% sodium hypochlorite decrease significantly the number of live bacteria in biofilms, providing also cleaner dentin surfaces (p < 0.05). CONCLUSIONS: Several chelating agents containing antimicrobials could not remove nor kill significantly biofilms developed on intra-orally infected dentin, with the exception of sodium hypochlorite and 4% peracetic acid. Dissolution ability is mandatory for an appropriate eradication of biofilms attached to dentin.

Antimicrobial activity of triantibiotic paste, 2% chlorhexidine gel, and calcium hydroxide on an intraoral-infected dentin biofilm model.

INTRODUCTION: The purpose of this study was to evaluate the antimicrobial activity of calcium hydroxide, 2% chlorhexidine gel, and triantibiotic paste (ie, metronidazole, minocycline, and ciprofloxacin) by using an intraorally infected dentin biofilm model. METHODS: Forty bovine dentin specimens were infected intraorally using a removable orthodontic device in order to induce the biofilm colonization of the dentin. Then, the samples were treated with the medications for 7 days. Saline solution was used as the control. Two evaluations were performed: immediately after the elimination of the medication and after incubation in brain-heart infusion medium for 24 hours. The Live/Dead technique (Invitrogen, Eugene, OR) and a confocal microscope were used to obtain the percentage of live cells. Nonparametric statistical tests were performed to show differences in the percentage of live cells among the groups (P < .05). RESULTS: Calcium hydroxide and 2% chlorhexidine gel did not show statistical differences in the immediate evaluation. However, after application of the brain-heart infusion medium for 24 hours, 2% gel chlorhexidine showed a statistically lesser percentage of live cells in comparison with calcium hydroxide. The triantibiotic paste significantly showed a lower percentage of live cells in comparison with the 2% chlorhexidine gel and calcium hydroxide groups in the immediate and secondary (after 24 hours) evaluations. CONCLUSIONS: The triantibiotic paste was most effective at killing the bacteria in the biofilms on the intraorally infected dentin model in comparison with 2% chlorhexidine gel and calcium hydroxide.

Efficacy of the NaviTip FX irrigation needle in removing calcium hydroxide from root canal.

OBJECTIVE: To evaluate the effectiveness of the NaviTip FX, brush-covered irrigation needle, in removing calcium hydroxide from the root canal. STUDY DESIGN: Thirty single-rooted teeth were randomly divided into three groups: A - irrigation with a hypodermic needle inserted as far as possible without binding and activation with #30 K-type file; B - Irrigation with a hypodermic needle without activation; C - irrigation with NaviTip FX needle. Sodium hypoclorite 1% was used in irrigation. The root canals were examined trough scanning electron microscopy. Calcium hydroxide removal was recorded at 1, 5, and 10mm from the working length (WL) and the data were analysed using one-way ANOVA test (p<0.05). RESULTS: NaviTip FX and hypodermic needle activated with #30K-type file showed lower score at 10 and 5mm with no significant difference between them. Comparison within groups did not show significant differences. All groups showed significantly better smear layer removal at 5 and 10 mm from the WL. CONCLUSION: The apical third (1mm) of the root canal was found to be the most critical site for Ca(OH)2 removal. Key words:Calcium hydroxide, irrigation, scanning electron microscope, NaviTip FX.

Micro-computed tomography study of the internal anatomy of mesial root canals of mandibular molars.

INTRODUCTION: The aim of this study was to determine the mesiodistal and buccolingual diameter, apical volume, and the presence of isthmuses at the apical level of mesial root canals of mandibular molars. METHODS: Sixty extracted first and second mandibular molars were scanned by using a SkyScan 1076 micro-computed tomography system with a voxel size of 18 µm. The apical thirds of the samples were reconstructed to allow a perpendicular section of the apical third by using the multiplanar reconstruction tool of the OsiriX software. The mesiodistal and the buccolingual distances of root canals were measured between the 1- to 4-mm levels. The type of root canal isthmuses present at these levels was classified by using modified criteria of Hsu and Kim. The volume of the root canal anatomy between the 1- to 3-mm apical levels was obtained by using the CTAN-CTVOL software. RESULTS: The medians of the mesiodistal diameter at the 1-, 2-, 3-, and 4-mm levels in the mesiobuccal and mesiolingual canals were 0.22 and 0.23 mm, 0.27 and 0.27 mm, 0.30 and 0.30 mm, and 0.36 and 0.35 mm, respectively. The buccolingual lengths at the 1-, 2-, 3-, and 4-mm levels were 0.37-0.35 mm, 0.55-0.41 mm, 0.54-0.49 mm, and 0.54 and 0.60 mm, respectively. The presence of isthmuses was more prevalent at the 3- to 4-mm level. However, 27 cases presented complete or incomplete isthmuses at the 1-mm apical level. The mean of the volume of the apical third was 0.83 mm(3), with a minimum value of 0.02 and a maximum value of 2.4 mm(3). CONCLUSIONS: Mesial root canals of mandibular molars do not present a consistent pattern. A high variability of apical diameters exists. The presence of isthmuses at the apical third was not uncommon even at the 1-mm apical level.

Physical properties and interfacial adaptation of three epoxy resin-based sealers.

INTRODUCTION: The aim of the study was to evaluate the radiopacity, solubility, flow, film thickness, setting time, and adaptation to the root canal walls of 3 epoxy resin-based sealers: AH Plus, Acroseal, and Adseal. METHODS: Physical tests were performed following American National Standards Institute/American Dental Association's requirements. For interfacial adaptation analysis, 30 maxillary canines were shaped by using ProTaper instruments. The specimens were divided into 3 groups (n = 10): group 1, AH Plus; group 2, Acroseal; and group 3, Adseal. The sealers were mixed with rhodamine B dye, and the canals were filled by using the lateral compaction technique. The percentage of gaps and voids area was calculated at 2, 4, and 6 mm levels from the apex. Statistical evaluation was performed by using analysis of variance for physical analysis and nonparametric Kruskal-Wallis and Dunn tests for interfacial adaptation (P < .05). RESULTS: No statistical differences were found for adaptation, percentage of voids, solubility, flow, and film thickness among the sealers (P > .05). AH Plus was significantly more radiopaque (P < .05). For the setting time, there were statistical differences among all the studied sealers (P < .05). CONCLUSIONS: AH Plus, Acroseal, and Adseal presented similar root canal adaptation, solubility, flow, and film thickness. Statistical differences were found for radiopacity and setting time (P < .05).

Biofilm dissolution and cleaning ability of different irrigant solutions on intraorally infected dentin.

INTRODUCTION: The aim of this study was to evaluate the biofilm dissolution and cleaning ability of different irrigant solutions on intraorally infected dentin. METHODS: One hundred twenty bovine dentin specimens were infected intraorally by using a removable orthodontic device. Thirty samples were used for each irrigant solution: 2% chlorhexidine and 1%, 2.5%, and 5.25% sodium hypochlorite (NaOCl). The solutions were used for 5, 15, and 30 minutes and at 2 experimental volumes, 500 µL and 1 mL. The samples were stained by using acridine orange dye before and after the experiments and evaluated by using a confocal microscope. The percentage of biofilm, isolated cells, and noncolonized dentin was measured by using a grid system. Differences in the reduction or increase of the studied parameters were assessed by using nonparametric methods (P < .05). RESULTS: The higher values of biofilm dissolution and noncolonized dentin were found in the 30-minute NaOCl group and in the 5-minute and 15-minute groups of 5.25% NaOCL. The use of 2% chlorhexidine solution did not improve the biofilm dissolution or increase the cleaning of the dentin in comparison with the NaOCl solutions (P < .05). CONCLUSIONS: Two percent chlorhexidine does not dissolve the biofilms. Thirty minutes of NaOCl are necessary to have higher values of biofilm dissolution and to increase the cleaning of the dentin independently of the concentration in comparison with the 5-minute and 15-minute contact times.

The influence of cone-beam computed tomography and periapical radiographic evaluation on the assessment of periapical bone destruction in dog's teeth.

OBJECTIVE: The aim of this study was to determine the influence of periapical radiographs, cone beam computed tomography (CBCT) sections, and cone beam volumetric data on the determination of periapical bone destruction in endodontically treated distal root canals of premolar canine teeth. Nontreated mesial roots were used as controls. STUDY DESIGN: Enterococcus faecalis strain (ATCC 29212) was inoculated into 30 root canals of 2 mongrel dogs to induce apical periodontitis. After 60 days, the root canals of the distal roots of the 11 mandibular and 4 maxillary premolars were endodontically treated (n = 15). The mesial root canals were used as controls (no treatment). The bone destruction was evaluated after 6 months by 5 evaluators using periapical radiographs and by CBCT (coronal and sagittal sections). After the experimental period, the area of the lesions in periapical radiographs and CBCT sections were measured in mm(2) using the ImageTool software. A single evaluator measured the volumetric data using the OsiriX software. The comparison between the diagnosis methods in treated root canals and controls was performed using parametric and nonparametric criteria. The Pearson correlation coefficient was computed between radiographic values and CBCT volumetric data in treated root canals and controls. RESULTS: The results showed the presence of chronic apical periodontitis in every inoculated tooth. After 6 months, periapical radiographs, coronal CBCT sections, and volumetric data showed lower bone destruction in endodontically treated teeth in comparison with the control group (P < .05). The 5 evaluators found no differences between the apical periodontitis area of treated teeth and controls when CBCT sagittal sections were used (P > .05). No correlation was found between x-ray and CBCT volumetric values in treated root canals. CONCLUSIONS: Although selected CBCT sagittal sections showed similar values of bone destruction in endodontically and nontreated root canals, volumetric CBCT data showed that periapical lesions of endodontically treated root canals had half of the volume of periapical lesions in nontreated root canals. No relationship could be found between the periapical values of bone destruction and volumetric data found in CBCT of treated rood canals.

The antimicrobial effect of iodine-potassium iodide after cleaning and shaping procedures in mesial root canals of mandibular molars

The aim of this study was to evaluate the antibacterial activity of 2% iodine potassium iodide (IKI) used as a final rinse after the cleaning and shaping procedures in mesial root canals of mandibular molars infected with Enterococcus faecalis. Seventy two mandibular first molars were used. The root canals were infected with Enterococcus faecalis for 30 days. After the infection procedures, the root canals were cleaned and shaped by using the ProTaper rotary system and manual files. The teeth were randomly assigned to four experimental groups (N=18). In group 1, the root canals were irrigated with sterile distilled water (control). In group 2, the root canals were irrigated with 1% Sodium hypochlorite (NaOCl) during instrumentation. In group 3, root canals were irrigated with 1% NaOCl during instrumentation and a five minute final irrigation using 2 % IKI. In group 4, the root canals were irrigated with 1% NaOCl during instrumentation and a 15 minutes final irrigation with 2 % IKI. Bacteria colony-forming units (CFU) from root canals were semi-quantified and the presence of negative cultures among the groups was compared using Fisher’s test (p < 0,05). The order of effectiveness was: 1% NaOCl plus 2% IKI for 15 minutes (95%), 1% NaOCl plus 2% IKI for 5 minutes (44%), 1% NaOCl (17%) and sterile distilled water (0%). Fisher’s exact test showed a significant difference among the groups (p<0.05). It was concluded that under in vitro conditions, IKI was able to eliminate the Enterococcus faecalis from infected dentin significantly in a 15-minute time frame after the cleaning and shaping procedures.

El objetivo del presente trabajo fue determinar el efecto in vitro del yoduro de potasio yodado al 2% posterior a la preparacion quimiomecanica en conductos radiculares infectados con Enterococcus faecalis. Para este estudio, se emplearon 72 primeras molares inferiores permanentes de humanos, los cuales fueron infectados con Enterococcus faecalis ATCC 29212. Los conductos fueron preparados mediante instrumentacion rotatoria y distribuidos de manera aleatoria en cuatro grupos de acuerdo al irrigante empleado: Grupo 1, agua destilada esteril; Grupo 2, NaOCl al 1%; Grupo 3: NaOCl al 1% IKI al 2% durante cinco minutos; y, Grupo 4: NaOCl al 1% mas IKI al 2% durante 15 minutos. Se tomaron muestras pre y postoperatorias de los conductos y se realizo la semicuantificacion microbiologica de las unidades formadoras de colonias de las bacterias. Fue comparada la presencia de cultivos negativos en los grupos mediante el test de Fisher utilizando un nivel de significancia de p < 0.05. El orden de efectividad para la desinfeccion de los conductos radiculares de mayor a menor fue: NaOCl al 1 % mas IKI al 2% durante 15 minutos (95%), NaOCl al 1% mas IKI al 2% durante 5 minutos (44%), NaOCl al 1% (17%) y agua destilada (0%). Se concluye, que bajo las condiciones in vitro de este estudio, el yoduro de potasio yodado empleado despues de la instrumentacion fue capaz de eliminar significativamente a la bacteria Enterococcus faecalis en un tiempo de 15 minutos.

Effect of sputter-coating on cracking of root-end surfaces after ultrasonic retrograde preparation--a SEM study of resected root apices and their respective impressions.

The aim of this study was to evaluate in vitro the effect of sputter-coating for SEM analysis on the formation of cracks on root-end surfaces after retrograde cavity preparation with ultrasonic tips. Root-end cavities were prepared with either Satelec S12/90 degrees D diamond-coated or S12/90 degrees non-coated stainless steel retrotips. Impressions were taken before and after retrograde cavity preparation. The resected root apices and their respective impressions were examined using a scanning electron microscope, and the presence, extension and numbers of cracks were recorded after each procedure. The number of cracks observed directly on the ultrasonically prepared root-end surfaces was larger than that observed in their respective impressions taken after root-end cavity preparation, which suggests that cracking was mostly produced by the sputter-coating process required for SEM analysis. Impressions of the root-end cavities prepared with non-coated ultrasonic stainless steel retrotips showed a greater incidence of cracks (3/10 impressions) than those that replicated cavities prepared with diamond-coated retrotips (1/10 impressions). No statistical difference was found between the diamond and stainless steel retrotips.

Antimicrobial effects of calcium hydroxide and chlorhexidine on Enterococcus faecalis.

INTRODUCTION: Endodontic treatment is commonly based on nonspecific elimination of intraradicular microorganisms. Although some authors prefer single-visit root canal operations for endodontic treatment, several studies have shown the importance of intracanal medication between sessions to kill microorganisms that biomechanical preparations alone cannot achieve. The purpose of this study was to evaluate the efficacy of calcium hydroxide Ca(OH)(2) and chlorhexidine gel on the elimination of intratubular Enterococcus faecalis. METHODS: Human uniradicular teeth contaminated with E. faecalis were treated with Ca(OH)(2), 2% chlorhexidine gel, Ca(OH)(2) plus 2% chlorhexidine gel, or saline (0.9% NaCl) as a negative control. Samples obtained at a depth of 0 to 100 mum and 100 to 200 mum from these root canal preparations were analyzed for bacterial load by counting the number of colony-forming units (CFUs) and bacterial viability using fluorescence microscopy. RESULTS: A significant decrease in the number of CFUs and the percentage of viable E. faecalis was observed after treatment with either Ca(OH)(2) or chlorhexidine when compared with the control group. Additionally, chlorhexidine gel had a significantly higher antimicrobial efficacy as measured by the number of CFUs and the percentage of viable cells than Ca(OH)(2). No differences were observed between the antimicrobial properties of chlorhexidine gel with and without the addition of Ca(OH)(2). CONCLUSION: Both Ca(OH)(2) and chlorhexidine have antimicrobial effects on E. faecalis. Chlorhexidine had increased antimicrobial activity when compared with Ca(OH)(2.) Ca(OH)(2) combined with chlorhexidine showed similar antimicrobial activity to chlorhexidine alone.

Effect of sputter-coating on cracking of root-end surfaces after ultrasonic retrograde preparation: A SEM study of resected root apices and their respective impressions

The aim of this study was to evaluate in vitro the effect of sputter- coating for SEM analysis on the formation of cracks on root-end surfaces after retrograde cavity preparation with ultrasonic tips. Root-end cavities were prepared with either Satelec S12/90oD diamond-coated or S12/90o non-coated stainless steel retrotips. Impressions were taken before and after retrograde cavity preparation. The resected root apices and their respective impressions were examined using a scanning electron microscope, and the presence, extension and numbers of cracks were recorded after each procedure. The number of cracks observed directly on the ultrasonically prepared root-end surfaces was larger than that observed in their respective impressions taken after root-end cavity preparation, which suggests that cracking was mostly produced by the sputtercoating process required for SEM analysis. Impressions of the root-end cavities prepared with non-coated ultrasonic stainless steel retrotips showed a greater incidence of cracks (3/10 impressions) than those that replicated cavities prepared with diamond-coated retrotips (1/10 impressions). No statistical difference was found between the diamond and stainless steel retrotips.

El objetivo del presente estudio fue evaluar in vitro el efecto del proceso de metalizacion de la dentina, necesaria para la observacion al microscopio electronico de barrido, sobre la formacion de fracturas dentinarias en retropreparaciones apicales realizadas con ultrasonido. Se realizaron retropreparaciones apicales en 20 piezas dentarias utilizando puntas ultrasonicas diamantadas Satelec S12/90° D (N=10) o puntas no diamantadas Satelec S12/90°. Se tomaron impresiones con silicona antes y despues de que fueran realizadas las retropreparaciones. Los apices radicu - lares y sus respectivas impresiones fueron metalizados y examinadas utilizando un microscopio electronico de barrido. La presencia, extension y numero de fracturas en la dentina fue registrada despues de cada procedimiento. El numero de fracturas observados en la dentina en las retropreparaciones fue mayor que el observado en las impresiones tomadas despues de realizado el procedimiento ultrasonico, lo cual indica que gran cantidad de fracturas en la dentina fueron producidas por el proceso de metalizacion requerido para el analisis al microscopio electronico de barrido y no por el procedimiento ultrasonico. El analisis de las impresiones mostro una mayor incidencia de fracturas cuando se utilizaron las puntas ultrasonicas no diamantadas (3/10) que cuando se utilizaron las puntas ultrasonicas diamantadas (1/10). Sin embargo, la diferencia no fue estadisticamente significativa (p>0.05).