In vitro study on cyclic fatigue resistance of three types of nickel titanium files in preparation for bending root canals / 口腔疾病防治

Objective@#The purpose of this study was to investigate the differences in the anti cyclic fatigue performance of Woride KS (WKS), Proteper Gold (PTG), and Hyflex CM (HCM) nickel titanium instruments with different tip diameters in curved root canal models, and to provide reference for the targeted selection of suitable nickel titanium instruments in clinical preparation of curved root canals.

Anatomía de la cámara pulpar y sistema de conductos radiculares: Estrategias pedagógicas unarevisión de literatura / Anatomy of the pulp chamber and the root canal system: Pedagogical strategiesAliterature review

Antecedentes: El conocimiento anatómico de la cámara pulpar y del sistema de conductos radiculareses fundamental para el correcto diagnóstico y planificación del tratamiento en endodoncia. Las herramientas pedagógicasdirigidasa los estudiantes de odontologíacomo apoyo en los procesos formativosde la asignatura de endodoncia favorecen la apropiación del conocimiento e identificación de las variantes morfológicas del sistema de conductos radiculares, que permiten al estudiantela integración del conocimiento. Objetivo:Identificar mediante una revisión de la literatura las estrategias pedagógicas que se utilizan para la enseñanza de morfología del sistema de conductos radiculares en endodoncia. Materiales y métodos: Se realizó una búsqueda bibliográfica de estudios originales en las bases de datos Medline (Pubmed), SciELO, Lilacs, Medline (Ovid), Web of science, Scopus, Embase, Google académico, eligiendo estudios publicadosa partir del año 2010 al 2022, para la selección de los artículos definitivos se seleccionaron estudios concernientes a procesos pedagógicos en endodoncia, excluyendo así otros tipos de enfoques en el área de odontología. Resultados: Se identificaron un total de 63 referencias, los cuales fueron analizados y seleccionados16, siendo excluidos 47 por no cumplir los criterios de inclusión. Conclusión: El uso de herramientas pedagógicas virtuales, didácticas y tecnológicas propician un efecto positivo en el estudiante de pregrado de odontología durante el aprendizaje de anatomía de sistemas de conductos radiculares que aumentan la confianza y seguridad al momento de realizar un tratamiento endodóntico en pacientes

Background: Anatomical knowledge of the pulp chamber and the root canal system is essential for correct diagnosis and treatment planning in endodontics. The pedagogical tools aimed at dental students as support in the training processes of the endodontics subject favor the appropriation of knowledge and identification of the morphological variants of the root canal system, which allow the student the integration of knowledge. Objective: To identify, through a review of the literature, the pedagogical strategies used to teach morphology of the root canal system in endodontics. Materials and methods: A bibliographic search of original studies was carried out in the Medline (Pubmed), SciELO, Lilacs, Medline (Ovid), Web of Science, Scopus, Embase, and Google academic databases, choosing studies published from 2010 to 2022. , for the selection of the definitive articles, studies concerning pedagogical processes in endodontics were selected, thus excluding other types of approaches in the area of dentistry. Results: A total of 63 references were identified, 16 of which were analyzed and selected, 47 being excluded for not meeting the inclusion criteria. Conclusion: The use of virtual, didactic and technological pedagogical tools favor a positive effect on the dentistry undergraduate student while learning the anatomy of root canal systems that increase confidence and security when performing endodontic treatment in patients.

Bioactivity and biocompatibility of bioceramic sealers in endodontics: an integrative review

Introduction: Bioceramic sealers have been gaining prominence in endodontics, meaning a great advance for endodontic therapy, mainly due to their biocompatibility and bioactivity. Objectives: research and discuss the literature about the bioactivity and biocompatibility of bioceramic sealants. Materials and methods: An integrative review was performed. The systematic plan consisted of four steps. In the first stage, a bibliographic survey was carried out in the Capes Periódicos Portal database. The search criteria were articles published between 2017 and 2022, found in the "advanced search" mode, using cross-references with the following keywords: bioceramics sealers AND endodontology AND root canals AND endodontic sealer AND bioactivity AND biocompatibility. Only documents found and published in full were evaluated. In the second stage, the titles and abstracts of the articles were read. In the third stage, a selection was made of those containing 3 to 5 keywords and a wording equal to or close to the proposed keywords. The fourth step consisted of reading the texts in full, followed by checking for duplicity and building a table with the collected information. Results: In view of the research carried out, 23 articles were obtained in the first stage. After reading the titles and abstracts, 21 articles were obtained. After selecting those containing 3 to 5 keywords, 10 articles met the criteria. One article was deleted due to duplicates. 9 articles met the exclusion and inclusion criteria and were selected to be part of the integrative review. Discussion: The selected studies in this literature review showed that bioceramic endodontic sealants perform well in endodontic therapy. Conclusion: To advance in its clinical application, more in vivo and in vitro studies with precise methods are needed to obtain more reliable data about its properties.

Guided endodontic access of severe calcified tooth without incisal edge ­ case report / Acesso endodôntico guiado de dente calcificado severamente sem borda incisal ­ relato de caso

Pulp tissue may suffer calcification because of trauma, operative procedures or carious lesions. This paper aimed to report and discuss the guided endodontic access as an alternative treatment. A 52 years old female patient had severe root canal calcification of tooth #11 associated with a radiolucent periapical lesion. Firstly, the crown and metal post and core were removed. A digital impression and cone-beam computed tomography "CBCT" scans were performed and imported to implant planning software (SimPlant Version 11; Materialise Dental, Leuven, Belgium).The guided endodontic access template was designed to allow the drill to reach a distance of 2 mm short of the apical foramen, once printed, it was tested in the mouth to evaluate its insertion and stability in the dental arch. The calcified root canal was penetrated using the access drill rotating by a low-speed hand-piece (10,000 rpm) under saline solution irrigation through advancing movements. Then, the apical foramen was negotiated with C-Pilot files #10 and #15. The working length was measured using the iPex-II apex locator. The instrumentation was carried out with Reciproc R50 and 2.5% sodium hypochlorite. One week later, a full-ceramic crown preparation was performed, and polyvinyl siloxane impression was carried out. A total of three follow-up sessions were performed after one week, one and twelve months. Bone neoformation was observed in the site of the periapical lesion and the patient had no signs or symptoms of any discomfort. Therefore, guided endodontics is indicated for severe calcified root canals.(AU)

O tecido pulpar pode sofrer calcificação por trauma, procedimentos cirúrgicos ou como resposta a lesões cariosas. Este trabalho teve como objetivo relatar e discutir o acesso endodôntico guiado como opção de tratamento. Paciente do sexo feminino, 52 anos, com calcificação severa do canal radicular do dente 11 associada a lesão periapical radiolucida. Na primeira intervenção clínica, a coroa e o pino de metal foram removidos. Uma impressão digital e imagens de CBCT foram realizadas e importadas para o software de planejamento de implante (SimPlant Versão 11; Materialize Dental, Leuven, Bélgica) tentando projetar um modelo de acesso endodôntico guiado para permitir que a broca alcance uma distância de 2 mm antes do forame apical, uma vez impresso, foi testado na boca para avaliar sua inserção e estabilidade na arcada dentária. O canal radicular calcificado foi penetrado com broca de acesso girando por peça de mão de baixa velocidade (10.000 rpm) sob irrigação com solução salina por meio de movimentos de avanço. Em seguida, o forame apical foi negociado com as limas C-Pilot nº 10 e nº 15. O comprimento de trabalho foi determinado usando o localizador de ápice iPex-II. A instrumentação foi realizada com Reciproc R50 e hipoclorito de sódio 2,5%. Uma semana depois, foi realizado o preparo da coroa total em cerâmica e a moldagem com polivinilsiloxano. Um total de três sessões de acompanhamento foram realizadas após uma semana, um e doze meses. A neoformação óssea foi observada no local da lesão periapical e a paciente não apresentava sinais ou sintomas de qualquer desconforto. Portanto, o acesso endodôntico guiado é indicado para canais radiculares calcificados severamente.(AU)

Mandibular pre-molars endodontic anatomy and role in sex dimorphism for Western Asia population using CBCT 3d imaging technique / Anatomía endodóntica de premolares mandibulares y papel en el dimorfismo sexual para la población de Asia Occidental utilizando la técnica de imagen 3d CBCT

SUMMARY: Cone Beam Computerized Tomography (CBCT) imaging technique can be used for identifying the root canal anatomy and its use in determining sexual dimorphism. The aim of current study was to identify the commonly found root canal morphology and gender dimorphism for mandibular pre-molars in Western Asia population according to Vertucci's classification using CBCT 3D imaging technique. On ethical approval 470 patients from Western Asia population with intact healthy mandibular first and second pre-molars were included in the study. The selected patients were sent to radiology department of Riyadh Elm University, Saudi Arabia for CBCT images. The observations recorded included: i) number of roots; and ii) type of root canal morphology based on Vertucci's classification. All the mandibular first and second pre-molars had single root both in males and females. The type of Vertucci's classification commonly observed was Type I both in males (88.94 %) and females (100 %) in mandibular first pre-molars. Similarly Type I was identified as a common root canal configuration in mandibular second pre-molars for males (82.77 %) and females (100 %). The two canal configurations Type IV and V were only observed in the males. It can be concluded from the results mandibular first and second pre-molars in the Western Asia population are single rooted with common Vertucci's Type I canal configuration in the females with rare evidence of two canals in males. Additionally CBCT is an effective technique and should be used for detection of root canals in the mandibular pre-molars which can aid dentists in providing a successful endodontic therapy.

RESUMEN: La imagen de la tomografía computarizada de haz cónico (CBCT) se puede utilizar para identificar la anatomía del conducto radicular y para determinar el dimorfismo sexual. El objetivo del estudio fue identificar la morfología del conducto radicular y el dimorfismo de sexo, comúnmente encontrados en los premolares mandibulares en la población de Asia occidental, de acuerdo con la clasificación de Vertucci, utilizando la técnica de imágenes CBCT 3D. Tras la aprobación ética, se incluyeron en el estudio 470 pacientes de la población de Asia occidental con primeros y segundos premolares mandibulares sanos intactos. Los pacientes seleccionados fueron enviados al departamento de radiología de la Universidad de Riyadh Elm, Arabia Saudita, para las imágenes CBCT. Las observaciones incluyeron: i) número de raíces; y ii) tipo de morfología del conducto radicular según la clasificación de Vertucci. Se observó solamente una raíz en los primeros y segundos premolares mandibulares tanto en hombres como en mujeres. El tipo de clasificación de Vertucci comúnmente observado fue Tipo I tanto en hombres (88,94 %) como en mujeres (100 %) en los primeros premolares mandibulares. El Tipo I se identificó como una configuración común del conducto radicular en los segundos premolares mandibulares para hombres (82,77 %) y mujeres (100 %). Ambas configuraciones de canal Tipo IV y V solo se observaron en los varones. Se puede concluir a partir de los resultados de los primeros y segundos premolares mandibulares en la población de Asia occidental, que éstos tienen una sola raíz con una configuración de canal de Vertucci Tipo I común en mujeres con una evidencia de dos canales infrecuente en los hombres. La CBCT es una técnica eficaz y debe usarse para la detección de conduc- tos radiculares en los premolares mandibulares, lo que puede ayu- dar a los dentistas a proporcionar una terapia endodóntica exitosa.

A CBCT based digital analysis of shaping ability of Max Wire® alloy file in the treatment of large and curved root canals

Aim: To evaluate the limits of the shaping ability of MaxWire® alloy file in the treatment of pre-created large and curved root canals with different apical sizes by using cone-beam computed tomography (CBCT). Materials and methods: Forty-five permanent maxillary first molars with moderately curved palatal roots (20°-30°) were divided into three groups, and large root canals were created with apical diameter #35 (Group 1), #40 (Group 2) or #50 (Group 3) by using BioRace NiTi System. Then, they were reshaped with the MaxWire alloy file, XP-endo Shaper®. Canals were scanned before and after instrumentation by using the CBCT scanner. Canal transportation (CT), centering ratio (CR), % increased prepared area (PA), and % increased prepared outline (PO) at 2, 3, and 4 mm from the apex were calculated. Data were statistically analyzed at P < 0.05. Results: There was a significant difference in the mean increase in PO in all apical sizes and all three levels. At both 3 mm and 4 mm levels the maximum PA and PO were achieved in apical size 35, while at 2 mm level the maximum values were obtained in apical size 40. There was no statistically significant difference in CT and CR within groups at 2 mm distance from the apex. Conclusion: Max Wire alloy technology of this novel instrument makes it possible to clean and touch the dentin walls of large and curved root canals. Small FOV and small voxel size of CBCT could also be used in shaping ability studies in endodontics.

Evaluation of glide path preparation and shaping ability of two nickel-titanium engine driven systems in moderate curved root canals / 上海交通大学学报（医学版）

Objective:To evaluate the clinical application effect of two nickel-titanium engine driven systems on moderate curved root canals. Methods:Ninety mesial root canals with moderate curvature of extracted human first mandibular permanent molar were randomly divided into three groups: M3 PRO Group, MTwo group and K group. The glide path was firstly prepared by using #10/04 file in M3 PRO group and MTwo group and #10 file in K group respectively.Then the preparation of root canals up to #25 was performed according to the instruction manual in each different group using standardized technique. All data including time required in glide path preparation, shaping preparation, total root canals preparation and changes of working length in root canal were recorded and analyzed statistically by using Analysis of Variance (ANOVA) and LSD-t tests (P<0.05). Results:Root canal glide path preparation time: MTwo group showed significantly less preparation time while M3 PRO group exhibited significantly the longest preparation time. There was significant difference between MTwo group and M3 PRO group (P=0.001). Root canal shaping preparation time: M3 PRO group showed significantly less preparation time while K group exhibited significantly the longest preparation time. Both MTwo group and M3 PRO group showed significantly less preparation time than K group (P=0.004, P=0.001), but there was no significant difference between MTwo group and M3 PRO group (P=0.573). Total root canal preparation time: MTwo group showed the shortest time while K group exhibited the longest time. There were significant differences between MTwo group, M3 PRO group and K group (P=0.004, P=0.033), but no significant difference between MTwo group and M3 PRO group (P=0.451). Changes of root canal working length: There were significant differences among the three groups (P=0.037, P=0.037, P=0.000). M3 PRO group showed a minimal change while K group exhibited significant changes. Conclusion:MTwo nickel-titanium engine driven system with #10/04 file preform a high efficiency in glide path preparation, whilst M3 PRO nickel-titanium engine driven system show less changes in working length. Under the circumstances where the total time required for root canal preparation is not significant, M3 PRO nickel-titanium engine driven system is more suitable for root canal preparation in moderate curved root canals.

Cleaning Efficiency of Root Canals using Differ ent Rotary Instrumentation Systems: A Comparative In vitro Study

Background: Smear layer is always formed during the instrumentation process due to the action of endodontic instruments during the shaping process and it should be removed as it might decrease the overall success of endodontic therapy. Aim of the study: To compare the cleaning efficiency of different rotary Ni-Ti systems: ProTaper Next, Xpendo Shaper and WaveOne Gold by assessing their ability to remove the smear layer from root canals walls. Methods and materials: A total of 24 palatal roots of maxillary molars were used in this study and randomly assigned into 3 groups (n=8) as follows: Group 1: instrumentation with ProTaper Next system (Dentsply Maillefer, Switzerland), Group 2: instrumentation with Xp-endo Shaper system (FKG Dentaire, Switzerland) and Group 3: instrumentation with WaveOne Gold system (Dentsply Maillefer, Switzerland). The samples were irrigated with 5.25% NaOCl. All samples were then examined by scanning electron microscope (SEM) at the center of the coronal, middle and apical thirds. The data was statistically analyzed using Kruskal Wallis and Mann-Whitney U tests. Results: ProTaper Next files showed a lower average mean of smear layer when compared to WaveOne Gold and Xp-endo Shaper files at the coronal third. No significant differences between the average means of smear layer were found at the middle and apical thirds. Conclusion: None of the tested groups showed a completely smear layer free root canal walls. In general, ProTaper Next files showed the best performance at the coronal third. All the files showed comparable performance at the middle and apical thirds.

Comparison of the shaping ability of different nickel-titanium instruments in simulated root canals in resin / 口腔疾病防治

Objective @#To compare the shaping ability of 3 different nickel (Ni)-titanium (Ti) systems in simulated root canals in resin and to provide a reference for clinicians.@*Methods@#Forty-eight resin blocks were prepared using the F360 (Komet, Brasseler GmbH & Co., Lemgo, Germany) (Group 1), F6 SkyTaper (20/06) (Komet, Brasseler GmbH & Co., Lemgo, Germany) (Group 2), F6 SkyTaper (25/06) (Komet, Brasseler GmbH & Co., Lemgo, Germany) (Group 3) and Reciproc R25 systems (VDW, Munich, Germany) (Group 4) (n=12 canals/group). The images taken before and after preparation were superimposed and analyzed by Adobe Photoshop v7.0. The amount of resin removed by each system was measured, and the centering ability was assessed. The data were statistically analyzed using SPSS 20.0.@*Results @#At the 1 mm point, the transportation in Group 4 [(0.10 ± 0.03) mm] was significantly greater than that in Groups 2 [(0.05 ± 0.03) mm] and 3 [(0.05 ± 0.03) mm] (P < 0.05). At the 8 mm and 9 mm points, the transportation values in Group 4 [(0.12 ± 0.06) mm and (0.13 ± 0.05) mm] were significantly higher than those in Groups 2 [(0.05 ± 0.05) mm and (0.05 ± 0.05) mm] and 3 [(0.05 ± 0.04) mm and (0.06 ± 0.05) mm] (P < 0.05). At the 10 mm point, the transportation was significantly greater in Group 4 [(0.13 ± 0.06) mm] than in Group 2 [(0.06 ± 0.06) mm].@*Conclusion@#F6 SkyTaper exhibits better centering ability than Reciproc.

Study on the application of cone-beam CT in root canal morphology of first deciduous molars / 口腔疾病防治

Objective@#To analyze the number, distribution of root canals in children's first deciduous teeth through a retrospective study of cone-beam computed tomography (CBCT). @* Methods@#A total of 185 first deciduous molars were selected from 91 children aged 4 to 8 years old in the Stomatology Department of Mianyang Hospital of Traditional Chinese Medicine. The number, distribution of root canals were analyzed.@* Results @#All 46 maxillary first deciduous molars had three roots; 139 mandibular first deciduous molars had two roots (77.70%) and three roots (22.30%). The root canals of all maxillary first deciduous molars are type Ⅰ, while the main root canal type of mandibular first deciduous molars is type Ⅳ. Of 51 children with bilateral mandibular first deciduous molars, 48 (94.12%) had symmetrical root and canal distributions.@*Conclusion @#The first deciduous molars usually have 2 to 3 roots. Root canals are mainly type I and IV. The distribution of root canals is symmetrical.

Molar superior con dos raíces palatinas: descripción de un caso / Upper molar with two palatine roots: a case description / Molar superior com duas raízes palatinas: uma descrição do caso

Antecedentes: La morfología radicular en molares superiores presenta menos variabilidad anatómica, sin embargo, es muy importante tener en cuenta que existen alteraciones anatómicas, y que aun no están bien fundamentadas, se asocia a hiperactividad en la vaina epitelial de Hertwig o bien asociados a factores externos durante la odontogénesis. Descripción del caso: El presente artículo relata un caso de un segundo molar superior derecho con pulpitis irreversible sintomática, en el examen radiográfico se observa la existencia de una raíz supernumeraria palatina. Se realizó tratamiento endodontico con ProtaperNext® y se obturó con técnica lateral modificada con ultrasonido. Conclusión: Los molares con raíces supernumerarias requieren del conocimiento y experiencia del clínico para integrar los métodos de diagnóstico tales como exámenes radiográficos, tomográficos, de microscopía así como técnicas para el tratamiento endodóntico.

Background: Radiographic examination in upper molars is often deficient in order to diagnose abnormalities in the root canal system and to be able to choose the ideal treatment. Description of the case: This article shows the clinical case of a second right upper molar with symptomatic irreversible pulpitis. An accessory root on the palatal is observed in a radiographic examination. A therapy of the canal was carried out with ProtaperNext ® and the sealing was made by cold lateral condensation with ultrasonic condensation. Conclusión: It is very important to know the root canal system morphology of the tooth to be treated in order to offer the patient an adequate treatment.

Antecedentes: O exame radiográfico em molares superiores é frequentemente deficiente para diagnosticar anormalidades no sistema de canais radiculares e para poder escolher o tratamento ideal. Descrição do caso: Este artigo mostra o caso clínico de um segundo molar superior direito com pulpite irreversível sintomática. Uma raiz acessória no palato é observada em um exame radiográfico. A terapia do canal foi realizada com ProtaperNext ® e a vedação foi feita por condensação lateral fria com condensação ultra-sônica. Conclusão: É muito importante conhecer a morfologia do sistema de canais radiculares do dente a ser tratado, a fim de oferecer ao paciente um tratamento adequado.

Diagnosis and endodontic treatment in a mandibular first premolar with two canals: case report / Diagnóstico e tratamento endodôntico em primeiro pré-molar inferior com dois condutos radiculares: relato de caso

Objective: The objective of this article was to describe the diagnosis and the endodontic treatment of a mandibular first premolar with two root canals. Case report: A 67-year-old female patient presented to the dental clinic referring pain in the right mandibular first premolar. The patient reported induced pain and the sensation of "grown tooth". Clinical examination revealed a marked degree of dental abrasion associated with a slight swelling in the periapical region and positive percussion and cold tests. The radiographic examination revealed an apical radiolucency. A pulpal diagnosis of necrotic pulp and chronic perirradicular periodontitis were made. After access cavity, the canals were prepared using K-files, Gates-Glidden drills and 2.5% sodium hypochlorite. Gutta-percha cones and AH-Plus sealer were used during obturation with the lateral condensation technique. Conclusion: After a period of 23 months of follow-up, clinical and radiographic examinations revealed total regression of the lesion.

Objetivo: O objetivo deste artigo foi descrever o diagnóstico e tratamento endodôntico de um primeiro pré-molar inferior com dois canais radiculares. Relato de caso: Paciente de 67 anos de idade apresentou-se à clínica odontológica referindo dor no primeiro pré-molar inferior. A paciente relatava dor espontânea e sensação de "dente crescido". O exame clínico revelou um grau acentuado de abrasão dentária associada a ligeiro inchaço na região periapical e respostas positivas aos testes de percussão e frio. O exame radiográfico revelou a presença de uma radiolucência apical. Foi realizado o diagnóstico de polpa necrótica e periodontite perirradicular crônica. Após a realização da cavidade de acesso, os canais foram preparados utilizando limas tipo K, brocas Gates-Glidden e hipoclorito de sódio a 2,5%. Cones de guta-percha e cimento obturador AH-Plus foram utilizados na obturação com a técnica de condensação lateral. Conclusão: Após um período de 23 meses de acompanhamento, os exames clínicos e radiográficos revelaram regressão total da lesão.

Research progress on the middle mesial root canal in the mandibular molar / 口腔疾病防治

@#Of the various root canal morphologies in mandibular molars, the middle mesial root canal is located between the mesiobuccal root canal and the mesiolingual root canal. The middle mesial root canal is a partial or completely independent extra root canal. Because of its fine structure, concealment and even calcification of the root canal orifice, it is difficult to completely clean and fill this root canal and it is easily omitted by dentists. The current study reviewed recent progress in terms of the incidence rate, classification, influencing factors, and exploration and preparation techniques of the middle mesial root canal of the human mandibular molar to provide a reference for clinical diagnoses and treatment.

AN in vitro study of 4 instruments in the preparation of curved root canals / 实用口腔医学杂志

Objective: To compare ProTaper Universal(PU),ProTaper Next(PN),WaveOne(WO) and M3 in the preparation of simulated curved canals. Methods: 40 simulated root canals were made from translucent resin and randomly divided into 4 groups(n = 10),the canals were prepared by PU,PN,WO and M3 respectively. The efficacy of canal preparation was analyzed. The pre-instrumentation and post-instrumentation images were recorded and the assessment of the canal shape was completed with Photoshop cs6 and Image Pro Plus6. 0. The apical transportation indexes and the amounts of apically extruded debris were measured. Results: WO was the most time-saving in mean working time(P ＜ 0. 05). PN and M3 took less time than PU in shaping the canals at the most levels(P ＜ 0. 05; PN vs M3,P＞ 0. 05). The amounts of apically extruded debris by PN was less than by PU,WO and M3(P ＜ 0. 05). The apical transportation by PN and M3 was less than that by PU and WO(P ＜ 0. 05). Conclusion: WaveOne is the most time-saving in shaping root canals. ProTaper Next and M3 are more effective and time-saving than ProTaper Universal in shaping root canals. ProTaper Next and M3 are comparable for optimally enlarge root canal.

Comparison of the shaping ability of novel thermally treated reciprocating instruments

OBJECTIVES: The present study aimed to evaluate the shaping ability of 2 thermally treated nickel-titanium reciprocating systems in simulated curved canals. MATERIALS AND METHODS: Forty simulated canals were prepared to apical size 25 using Reciproc Blue R25 (VDW) and WaveOne Gold Primary (Dentsply Sirona) instruments. Standard pre- and post-preparation images were taken and superimposed. The removal of resin material was measured at 5 standard points: the canal orifice, halfway between the canal orifice and the beginning of the curve, the beginning of the curve, the apex of the curve, and the end-point of the simulated canal. The data were analysed using the independent sample t-test with a 5% significance threshold. RESULTS: The canals in which Reciproc Blue R25 was used showed a significantly greater widening than those in which WaveOne Gold was used at 4 of the 5 measurement points (p < 0.05). The Reciproc Blue R25 instrument removed significantly more resin from the inner aspect of the curve at 2 of the 5 points and similar amounts at the remaining 3 points. At the 2 apical points, there was no significant difference between the Reciproc Blue R25 and WaveOne Gold Primary instruments. CONCLUSION: Both instruments respected the original canal anatomy; however, WaveOne Gold resulted in a more conservative shape with less transportation.

Progress in the study of calcium hydroxide in different vehicles / 口腔疾病防治

@#Calcium hydroxide is widely used as disinfectant of root canals recently. The vehicle is a substance which is added into calcium hydroxide to form a paste. It can be classified into water soluble, viscous and oily. Different vehicles for calcium hydroxide may produce different disinfectant effects. Searching for an ideal vehicle for calcium hydroxide is a hot research topic in recent years. This article will make a review on progress in the study of calcium hydroxide in different vehicles.

Clinical study of root canal numbers in maxillary second primary molars / 口腔疾病防治

Objective@#To investigate the root canal numbers of maxillary second primary molars.@*Methods @#216 max illary second primary molars from 204 children aged 3-8 years old were selected. All the teeth need to do the root canal therapy. After opening the pulp chamber, the root canal were examined and determined with small size K file and 17％ethylene diaminetetraacetic acid (EDTA). Hand instruments were used for root canal preparation and then zinc-oxide iodoform paste was used for filling. @*Results @#216 maxillary second p rimary molars, 122 teeth had three root canals(56.5%), and 94 teeth had four root canals (43.5%). The incidence of second mesiobuccal canal (MB2) was 41.2%. There was no correlation between the incidence of the MB2 canal and gender and tooth position. @*Conclusion@# The root canals of maxillary second primary molars had more variations, and there was a high incidence of the second mesiobuccal canal.

Clinical report and literature review of right mandibular canine with two roots and two root canals / 口腔疾病防治

@#The mandibular canine usually has a single root with a single canal. It is rarely to see a mandibular canine with two roots and two toot canals. A case of a patient who has a right mandibular canine with two roots and two root canals was reported. Cone beam computed tomography (CBCT) comprehensively demonstrated the root canal system and especially provided the information of canal varieties and complex canal before operation. CBCT can improve the discovery rate of canal varieties, guide root canal treatment and prevent missed roots in tooth extraction.

Clinical report and literature review of mandibular first premolar with three roots and three root canals / 口腔疾病防治

@#The mandibular first premolar has complicated morphology of root canal, it has more variation which increases the incidence of multiple root canals. A successful root canal therapy not only need strict cleaning, disinfection and filling, but also need a correct understanding of root canal morphology and anatomy. Otherwise there might be a risk of missing canals that resulting the failure of the therapy. Also crown closure is one of the successful elements of root canal therapy. This is a case report accompanied by a review of the literature that shows the unusual anatomy of the mandibular first molar with three roots and three root canals.

Clinical analysis of the shaping ability of Hyflex CM rotary NiTi files in curved root canals / 实用口腔医学杂志

60 curved root canals of permanent teeth with angles of curvature ranging from 15°to 40°(Schneider's methodology)were prepared using the instruments of Hyflex CM(HC) and ProTaper(PT) Universal respectively(n=30).Using standardized pre-and post-instrumentation paralleling periapical radiographs,canal curvature was determined by image analysis software and the clinical shaping effect of Hyflex CM and ProTaper rotary NiTi files were compared.The canal curvature in group HC and PT decreased by 4.54°±3.25° and 5.63°±3.84° respectively(between pre-and post-treatment in both groups,P0.05).Hyflex CM can meet the clinical necessity for the instrumentation of curved root canals.