Assessment of Mesial Canals Morphology of Mandibular First Molars Using CBCT: An In-vitro Study / Avaliação da morfologia dos canais mesiais dos primeiros molares inferiores usando TCCB: um estudo in vitro

Objective: The current study aimed to investigate the relationship between canal configuration, distance between mesiobuccal (MB) and mesiolingual (ML) orifices and the degree of canals curvature in the mesial root of permanent mandibular first molars in a sample of Sudanese population using cone-beam computed tomography (CBCT). Material and Methods: A total of 143 extracted mandibular first molars were processed and scanned with CBCT to determine the configuration of the mesial root canals according to the Vertucci classification. The interorificial distance and the degree of canal curvature in clinical (CV) and proximal (PV) views using Schneider technique were assessed. Results: The commonest canal configuration was type IV (53.1%). The interorificial distance was significantly shorter in type VI compared to other types (P < 0.05). Significant association was found for type IV between the MB and ML canal in the primary curvature regarding CV and PV, and for type II regarding PV in primary and secondary curvature (P < 0.05). In type IV the degree of secondary curvature of MB canal regarding PV, and in the ML canal in CV was significantly lower compared to other types (P < 0.05). Significant correlation was seen in PV of primary curvature in the MB for type VI (P < 0.05). Conclusion: The interorificial distance and secondary curvatures in CV for MB canal were found to be key factors for predicting root canal patterns in PV (AU)

Objetivo: O presente estudo teve como objetivo investigar a relação entre a configuração do canal, a distância entre os orifícios de entrada dos canais mesiovestibular (MB) e mesiolingual (ML) e o grau de curvatura dos canais na raiz mesial dos primeiros molares inferiores permanentes em uma amostra da população sudanesa usando tomografia computadorizada cone-beam(TCCB). Material and Methods: Um total de 143 primeiros molares inferiores extraídos foram processados e escaneados com TCCB para determinar a configuração dos canais radiculares mesiais de acordo com a classificação de Vertucci. A distância inter orificios e o grau de curvatura do canal nas vistas clínica (CV) (acredito que a tradução seja essa mesma, seria como uma foto intra oral clínica/perguntei a um endodontista, mas não soube me responder) e proximal (PV) usando a técnica de Schneider foram avaliados. Resultado: A configuração mais comum do canal foi do tipo IV (53,1%). A distância inter-orificios foi significativamente menor no tipo VI em comparação com outros tipos (P <0,05). Correlação significativa foi observada na PV da curvatura primária no MB para o tipo VI (P <0,05). Conclusão: A distância inter orifícios e as curvaturas secundárias na CV para o canal MB foram consideradas fatores-chave na predição dos padrões do canal radicular na PV (AU)

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.

Identification of Apical and Cervical Curvature Radius of Human Molars

To determine the frequency of apical and cervical curvatures in human molars using the radius method and cone-beam computed tomography (CBCT) images. Four hundred images of mandibular and maxillary first and second molars were selected from a database of CBCT exams. The radius of curvature of curved root canals was measured using a circumcenter based on three mathematical points. Radii were classified according to the following scores: 0 - straight line; 1 - large radius (r>8 mm, mild curvature); 2 - intermediate radius (r>4 and r<8 mm, moderate curvature); and 3 - small radius (r≤4 mm, severe curvature). The frequency of curved root canals was analyzed according to root canal, root thirds, and coronal and sagittal planes, and assessed using the chi-square test (significance at α=0.05). Of the 1,200 evaluated root canals, 92.75% presented curved root canals in the apical third and 73.25% in the cervical third on coronal plane images; sagittal plane analysis yielded 89.75% of curved canals in the apical third and 77% in the cervical third. Root canals with a large radius were significantly more frequent when compared with the other categories, regardless of root third or plane. Most root canals of maxillary and mandibular first and second molars showed some degree of curvature in the apical and cervical thirds, regardless of the analyzed plane (coronal or sagittal).

Determinar a frequência de curvaturas apicais e cervicais em molares humanos usando o método do raio de curvatura e imagens de Tomografia Computadorizada de Feixe Cônico (TCFC). Quatrocentas imagens de primeiros e segundos molares superiores e inferiores foram selecionadas a partir de um banco de dados de exames de TCFC. O raio de curvatura dos canais foi medido usando um circuncentro com base em três pontos matemáticos e classificado de acordo com os seguintes escores: 0 - linha reta; 1 - raio grande (r > 8 mm, curvatura suave); 2 - raio intermediário (r > 4 e r < 8, curvatura moderada); 3 - raio pequeno (r ≤ 4 mm, curvatura severa). A frequência de curvaturas foi analisada em função do canal radicular, dos terços da raiz, e dos planos de avaliação (coronal e sagital); e avaliados usando o teste Qui-Quadrado (significância de α=0.05). Dos 1200 canais radiculares avaliados, 92,75% apresentaram curvatura no terço apical e 73,25% no terço cervical quando da análise no plano coronal; a análise do plano sagital revelou 89,75% de canais curvos no terço apical e 77% no terço cervical. Canais radiculares com curvatura suave foram significantemente mais frequentes quando comparados com as demais categorias, independentemente do terço radicular ou do plano. A maioria dos canais radiculares dos primeiros e segundos molares superiores e inferiores apresentou algum grau de curvatura nos terços apical e cervical, independentemente do plano analisado (coronal ou sagital).

Study on distolingual root canal curvature on permanent mandibular first molars by the cone-beam computed tomography / 实用医学杂志

Objective To measure the curvatures of the distolingual root canals of permanent mandibular first molars by cone-beam computed tomography (CBCT). Methods The CBCT was used to collect 230 cases of mandibular first molar distalingual root from 513 patients. The images were created by 3-D reconstruction based on the BECT data. Images were analyzed by NNT image analysis software. Each tooth was captured in clinical (CV) and proximal view (PV) image, and measured by the Schneider method. Results The average curvature of the distallingual canal was (13.27 ± 8.57)° in CV, and (30.96 ± 11.63)° in PV. Most of the distallingual root in the buccolingual view was mild bending or moderate bending , and the proximal view was severe bending. The distal lingual root bending was the most common in the crown third of the root , next in the apical third of the root, in the middle third of the root. Conclusion CBCT is an effective tool for the detection of additional distolingual roots and is a valuable aid for dentists in root canal treatment.

Piecewise straight line approximation of curve existing in slightly curved mesiobuccal root canal of mandibular first molar: a radiographic investigation / Aproximación a segmentos de línea recta en la curva existente del canal radicular mesiobucal ligeramente curvado del primer molar inferior: una investigación radiográfica

The aim of this study was to radiographically investigate the curve existing in slightly curved mesiobuccal canal of mandibular first molar by applying Piecewise straight line approximation. Extracted human mandibular molars were radiographed and one hundred radiographs were selected whose mesiobuccal canal showed slight curvature (10-20°) according to Schneider's method. The curves were traced and analyzed using Piecewise straight line method. Each curve was considered as a unit consisting of six different pieces of straight lines joining at seven specific points and the angle of curvature at these points was determined using the slope formula. All curves analyzed in this study had varying degrees of curvatures at different points on the curve. Maximum curvature (0.40°) was recorded at the middle third of the root canal. Within the limitation of the study, significant curvature occurs through out the curve existing in the mesiobuccal canal of mandibular first molar and the middle third of the curve showing greater degree of curvature. There is a possibility of greater curvature occurring in the coronal third of the curve. Though three dimensional studies would be more appropriate, Piecewise straight line approximation may be a better method than existing methods to simulate canal geometry.

El objetivo de este estudio fue investigar radiográficamente la curva existente en el canal radicular mesiobucal ligeramente curvado del primer molar inferior mediante la aplicación de aproximaciones a segmentos de línea recta. Se utilizaron molares inferiores humanos extraídos que fueron radiografiados. Fueron seleccionadas, según el método de Schneider, 100 radiografías cuyo canal mesiobucal mostró una ligera curvatura (10-20°). Las curvas fueron delineadas y analizadas mediante el método de aproximación a segmentos de línea recta. Cada curva se consideró como una unidad que consta de seis diferentes segmentos de línea recta que unen a siete puntos específicos y el ángulo de curvatura en estos puntos se determinó utilizando la fórmula de la pendiente. Todas las curvas analizadas en este estudio tenían diversos grados de curvaturas en diferentes puntos de la curva. La curvatura máxima (0,40°) se registró en el tercio medio del canal radicular. Dentro de la limitación del estudio, una curvatura significativa se produce a través de la curva existente en el canal mesiobucal del primer molar inferior y el tercio medio de la curva que muestra un mayor grado de curvatura. Existe la posibilidad que ocurra una mayor curvatura en el tercio coronal de la curva. Aunque un estudio tridimensional sería más apropiado, la aproximación a segmentos de línea recta puede ser un mejor método que los existentes para simular la geometría del canal.

Influence of root canal curvature on the screw-in effect of nickel-titanium rotary files in simulated resin root canal / 대한치과보존학회지

OBJECTIVES: Nickel-titanium (Ni-Ti) rotary instruments have some unexpected disadvantages including the tendency to screw-in to the canal. The purpose of this study was to evaluate the influence of root canal curvatures on the screw-in effect of Ni-Ti rotary files. MATERIALS AND METHODS: A total of 80 simulated root canals in clear resin blocks were used in the study. Canals with curvature of 0, 10, 20 and 30 degrees were instrumented with ProTaper instruments SX, S1, S2 and a ProFile of #25/0.06 to 1.0-2.0 mm beyond the initial point of root curvature. The screw-in force was measured with a specially designed device while canal was instrumented with a ProFile of #30/0.06 at a constant speed of 300 rpm. The data were subjected to one-way ANOVA and Scheffe multiple range test for post-hoc test. RESULTS: Larger degree of canal curvature generated significantly lesser screw-in forces in all groups (p < 0.001). CONCLUSIONS: More attention needs to be paid when using rotary instruments in canals with less curvature than canals with more curvatures to prevent or reduce any accidental overinstrumentation.

Method for determination of root curvature radius using cone-beam computed tomography images

This article describes and discusses a method to determine root curvature radius by using cone-beam computed tomography (CBCT). The severity of root canal curvature is essential to select instrument and instrumentation technique. The diagnosis and planning of root canal treatment have traditionally been made based on periapical radiography. However, the higher accuracy of CBCT images to identify anatomic and pathologic alterations compared to panoramic and periapical radiographs has been shown to reduce the incidence of false-negative results. In high-resolution images, the measurement of root curvature radius can be obtained by circumcenter. Based on 3 mathematical points determined with the working tools of Planimp® software, it is possible to calculate root curvature radius in both apical and coronal directions. The CBCT-aided method for determination of root curvature radius presented in this article is easy to perform, reproducible and allows a more reliable and predictable endodontic planning, which reflects directly on a more efficacious preparation of curved root canals.

O objetivo deste estudo foi discutir um método para obter o raio de curvatura a partir de imagens de tomografias computadorizadas cone beam (CBCT). A severidade da curvatura do canal radicular é essencial para selecionar o instrumento e a técnica de instrumentação. O diagnóstico e o planejamento do tratamento endodôntico tem sido feito com o auxílio da radiografia periapical. Contudo, a precisão da imagem obtida por CBCTpara identificar alterações anatômicas e patológicas reduz os resultados falso-negativos. Em imagens com alta qualidade de resolução a mensuração do raio de curvatura pode ser obtida a partir do circuncentro. Baseado em três pontos matemáticos com a ferramenta de trabalho de um software (Planimp®) pode-se calcular o raio de curvatura em ambas as direções, tanto para frente em sentido apical, como para trás em direção cervical. Este método para se determinar o raio de curvatura auxiliado por imagens de tomografia computadorizada é fácil, reprodutível e favorece o planejamento do tratamento endodôntico o que influencia na eficácia do preparo de canais radiculares curvos.

Change of working length in curved canals by various instrumentation techniques / 대한치과보존학회지

To evaluate the change of working length with various instrumentation techniques in curved canals, working length and canal curvature were determined before and after canal instrumentation in buccal or mesial canals of extracted human molars. Stainless steel K-files (MANI(R), Matsutani Seisakusho Co. Takanezawa, Japan), nickel-titanium K-files (Naviflex NT(TM), Brassler, Savannah, USA), ProFile(R), and ProTaper(TM) (Dentsply-Maillefer, Ballaigues, Switzerland) were used to prepare the canals with crown-down technique. In two hand instrumentation groups, coronal flaring was made with Gates Glidden burs. Apical canals were instrumented until apical diameter had attained a size of 30. Positional relation between the tooth apex and the #10 K-file tip was examined by using AutoCAD 2000 (Autodesk Corp., San Rafael. CA, USA) under a stereomicroscope before and after coronal flaring, and after apical instrumentation. Degree of canal curvature was also measured with Schneider's method in radiographs. Data of working length and canal curvature changes were statistically analyzed with one-way ANOVA and Tukey's studentized range test. Working length and canal curvature were decreased significantly in each step in all instrumentation groups. Coronal flaring using Gates Glidden burs in hand instrument groups and whole canal instrumentation using stainless steel hand K-files caused significantly more working length change than in ProFile instrumentation group (p < 0.05). The result of this study demonstrates that all of the above kinds of instrumentation in curved canals cause reduction of working length and canal curvature at each instrumentation steps, and hand instrumentation causes more working length change than ProFile.

A comparative study on the canal configuration after shaping by ProFile, ProTaper(TM) and K-Flexofile in simulated canals with different angles of curvature / 대한치과보존학회지

The purpose of this study was to evaluate the canal configuration after shaping by ProFile, ProTaper and K-Flexofile in simulated resin canals with different angles of curvature. Three types of instruments were used : ProFile, ProTaper, K-Flexofile. Simulated root canals, which were made of epoxy resin, were prepared by ProFile, ProTaper with rotary instrument using a crown-down pressureless technique, and hand instrumentation was performed by K-Flexofile using a step-back technique. All simulated canals were prepared up to size 25 file at end-point of preparation. Pre and post instrumentation images were recorded with Scanner. Assessment of canal shape was completed with Image Analysis program. Measurements were made at 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 mm from the apex. At each level, outer canal width, inner canal width, total canal width, and amount of transportation from original axis were recorded. Instrument deformation and fracture were recorded. Data were analyzed by means of one-way ANOVA analysis of variance and the Sheffe's test. The result was that ProFile and ProTaper maintain original canal shape regardless of the increase of angle of curvature than K-Flexofile. ProFile show significantly less canal transportation and maintained original canal shape better than ProTaper.

The change of canal configuration after instrumentation by several nickel-titanium files in the simulated canal with abrupt curvature / 대한치과보존학회지

The purpose of this study was to evaluate which type of Ni-Ti files are able to maintain canal configuration better in the simulated canal with abrupt curvature near it's apex. Ninety six simulated root canals were made in epoxy resin and #15 finger spreader was used as root canal templates. The simulated root canals were made with radius of curvature of 1.5 mm, 3.0 mm, 4.0 mm, 6.0 mm respectively and the angle of curvature of all simulated canals were adjusted to 90 degree. The simulated canals were instrumented by ProFile, ProTaper, Hero 642, and K3 at a 300 rpm using crown-down pressureless technique. Pre-instrumented and post-instrumented images were taken by digital camera and were superimposed with Adobe Photoshop 6.0 program. Images were compared by image analysis program. The changes of canal width at the inner and outer side of the canal curvature, canal transportation were measured at 9 measuring point with 1 mm interval. Statistical analysis among the types of Ni-Ti files was performed using Kruskal-Wallis test and Mann-Whitney U-test. The result was that ProFile maintain original canal configuration better than other engine driven Ni-Ti files in the canals above 3.0 mm radius of curvature, and in the 1.5 mm radius of curvature, most of Ni-Ti flies were deformed or separated during instrumentation.

Root canal curvature of anterior teeth in the Han nationality in Shaanxi province / 实用口腔医学杂志

Objective: To investigate the root canal curvatures of anterior teeth in the Han nationality in Shaanxi province.Methods:392 permanent anterior teeth were examined by indirect digital radiography both from labiolingual and mesiodistal directions according to Schneider method, root canal curvatures were analyzed by electronic rule.Results:Root canals of the anterior teeth were mainly of type I. High rate of root canal curvature was found in maxillary canines (68.5%), and most of curves were in the apical third. There was a relationship between the root canal curvatures of maxillary canine and age(P=0.03). Conclusion:Root canal curvatures of maxillary canine are complicated,especially in maxillary canines. The root canal curvatures of maxillary canine decreased with aging.

A mathematical analysis of the relationship between Schneider's method and Weine's method for the measurement of root canal curvature / 实用口腔医学杂志

Objective:To study the mathematical relation between the measurements of root canal curvature obtained by Schneider's method(?_S) and Weine's method(?_W).Methods:The axis of a curved root canal was simplified by an arc (whose radius was r and central angle ?) and 2 tangent line segments (whose lengths were l_1 and l_2),the relation of ?_S and ?_W was studied with the help of mathematical analysis according to the different ways of determining the measured angles on the simplified axis.The graphs of the function were analysed.Results:The following formulas were proved:(1)tan?_S=(1-cos?_W+ ksin?_W)/(sin?_W+kcos?_W),k=l_2/r;(2)?_W/2≦?_S≦?_W.If ?_W was in the interval [0,?],a proximate linear correlation existed between ?_S and ?_W.Conclusion:There is a complex function between the 2 angles(?_S and ?_W) measured by Schneider's method and Weine's method,the ratio of the length of the apical straight part to the radius of the canal curvature is an important factor determining the different values of ?_S and ?_W.