Prevalence and C-shaped root canal configuration in lower molars in the metropolitan region, Chile / Prevalencia y configuración de conductos en C en molares inferiores de la región metropolitana, Chile

Objetive: The aim of this study was to determine the prevalence, demographics, and root configuration of C-shaped canals of mandibular molars by means of cone beam computed tomography in the population of the Metropolitan Region, Chile. Material and Methods: 912 molars (456 first and 456 second molars) resulting from the analysis of 228 mandibular CT scans were evaluated. The root configuration was established by means of a panoramic reconstruction and axial tomographic sections, classifying the presence and type of canals through the analysis of five sections or cuts along the root. Data were statistically analyzed using a 5% confidence interval. Results: Of the 912 molars analyzed, 70 were classified as C-shaped canals (7.68%), corresponding to 58.33% of those molars that presented fused roots. 95.7% of this root canal configuration was observed in lower second molars, occurring more frequently in females (n=45, 64.29%). 45.65% of the cases that presented C-shaped canals were bilateral and the most frequent configuration was C3 (n=401, 66.63%) according to the Melton classification.Conclusion: The C-shaped canals of the mandibular molars in the studied population were observed mainly in second molars, showing a clear prevalence among females and a high percentage of bilaterality. The presence of fused roots significantly increases the possibility of finding this type of root configuration.

Objetivo: El objetivo del presente estudio fue determinar, por medio de tomografía computarizada de haz cónico, la prevalencia, demografía y configuración radicular de los conductos en forma de C de molares inferiores en la población de la Región Metropolitana, Chile. Material y Métodos: 912 molares (456 primeros y 456 segundos molares) resultantes del análisis de 228 tomografías mandibulares fueron evaluados. Mediante una reconstrucción panorámica y cortes tomográficos axiales se estableció la configuración radicular, clasificando la presencia y tipo de conducto por medio del análisis de 5 cortes a lo largo de la raíz. Los datos fueron analizados estadísticamente con un intervalo de confianza del 5%. Resultados: De los 912 molares analizados, 70 fueron clasificados como conductos en forma de C (7.68%), correspondiendo al 58.33% de aquellos molares que presentaron raíces fusionadas. El 95.7% de esta configuración de conductos fue observada en segundos molares inferiores, presentándose con mayor frecuencia en mujeres (n=45, 64.29%). El 45.65% de los casos que presentaron conductos en C se manifestaron bilateralmente y la configuración más frecuente observada fue la C3 (n=401, 66.63%) según la clasificación de Melton. Conclusión: Los conductos en forma de C de los molares mandibulares en la población estudiada fueron observados principalmente en segundos molares, marcando una clara predilección por el sexo femenino y un alto porcentaje de bilateralidad. La presencia de raíces fusionadas aumenta significativamente la posibilidad de encontrar este tipo de configuración radicular.

Root resorption pattern in panoramic radiographs of pediatric patients with unilateral posterior crossbite: a cross-sectional and retrospective study / Patrón de reabsorción radicular en radiografías panorámicas de pacientes pediátricos con mordida cruzada posterior unilateral: estudio transversal y retrospectivo

SUMMARY: temporary mandibular molars in panoramic radiographs of pediatric patients with unilateral posterior crossbite (UPCB). This cross-sectional and retrospective study analyzed 114 orthopantomograms of patients between 6 - 9 years of age with unilateral posterior crossbite diagnosis. The first and second mandibular molars were analyzed. Their root resorption stage was typified, and the root lengths were measured; to later compare the data obtained depending on the malocclusion side. 86.4 % of molars showed a linear resorption pattern, and atypical resorption prevalence in patients with UPCB was 13.5 %. The total length average of the first molars on the side of the malocclusion was 8.20 mm, while the contralateral exhibited a mean of 9.29 mm. Lastly, the second molars had a mean length of 11.12 mm in crossbite side and 12.30 mm in the normal occlusion side. UPCB could affect physiological resorption by observing a resorption alteration in those mandibular molars located on the malocclusion side.

RESUMEN: El trabajo de este estudio se realizó en molares mandibulares temporales en radiografías panorámicas de pacientes pediátricos con mordida cruzada posterior unilateral (MCPU). Este estudio transversal y retrospectivo analizó 114 ortopantomografías de pacientes entre 6 - 9 años de edad con diagnóstico de mordida cruzada posterior unilateral. Se analizaron los primeros y segundos molares mandibulares. Se tipificó su estado de reabsorción radicular y se midió la longitud de las raíces; para luego comparar los datos obtenidos según el lado de la maloclusión. El 86,4 % de los molares mostró un patrón de reabsorción lineal y la prevalencia de reabsorción atípica en pacientes con MCPU fue del 13,5 %. El promedio de longitud total de los primeros molares del lado de la maloclusión fue de 8,20 mm, mientras que el contralateral exhibió una media de 9,29 mm. Por último, los segundos molares tenían una longitud media de 11,12 mm en el lado de mordida cruzada y de 12,30 mm en el lado de oclusión normal. La MCPU podría afectar la reabsorción fisiológica al observar una alteración de la reabsorción en aquellos molares mandibulares ubicados en el lado de la maloclusión.

Prevalence of radix entomolaris in mandibular first molars by cone-beam computed tomography in a southern Chilean sub-population / Prevalencia de radix entomolaris en primeros molares mandibulares usando tomografía computarizada cone-beam en una subpoblación del sur de Chile

SUMMARY: The aim of this of this study was to evaluate the prevalence and morphology of radix entomolaris (RE) in the mandibular first molar (MFM) in a southern Chilean sub-population by cone-beam computed tomography (CBCT). Two hundred ten CBCT images of MFM were analysed. To detect the presence of RE, the observation and measurements were standardised, advancing 1 mm to apical from the floor of the pulp chamber to the most apical zone of the tooth. The data were analyzed using descriptive statistics, with a value of P < 0.05 being statistically significant. The prevalence of a third root in the permanent MFM was 5.7 % (12/210). The incidence of RE was the same in male patients (2.9 %) as in female patients (2.9 %) (p=0.324). The occurrence of an RE in the left MFM was 7.3 % (3/41 patients) for male patients and 4.5 % (3/66) for female patients (p=0.398). The right MFM in male patients had an incidence of 8.1 % (3/37) and 4.5 % (3/66) for female patients (p=0.340). When the presence of an RE was compared between the left (5.6 %) and right side (5.8 %), no statistically significant differences were found (p=0.998). The frequency of bilateral three-rooted MFM was 71.43 % (5/7) and 28.57 % (2/7) were unilateral. The prevalence of RE in MFM in a southern Chilean sub-population was 5.7 %. The occurrence was bilateral in the majority of cases and no significant differences were observed by sex or side. The commonest type of RE was Type 1 (83.3 %). The use of CBCT can improve the endodontic treatment outcome.

RESUMEN: El objetivo de este estudio fue evaluar la prevalencia y morfología de radix entomolaris (RE) en el primer mo- lar mandibular (MFM) en una subpoblación del sur de Chile mediante tomografía computarizada de haz cónico (CBCT). Se analizaron doscientas diez imágenes CBCT de MFM. Para detectar la presencia de OD se estandarizó la observación y las medidas, avanzando 1 mm apical desde el suelo de la cámara pulpar hasta la zona más apical del diente. Los datos fueron analizados mediante estadística descriptiva, siendo estadísticamente significativo un valor de P < 0,05. La prevalencia de una tercera raíz en el MFM permanente fue de 5,7 % (12/210). La incidencia de ER fue la misma en pacientes masculinos (2,9 %) que en pacientes femeninas (2,9 %) (p=0,324). La aparición de un ER en el MFM izquier- do fue del 7,3 % (3/41 pacientes) para los pacientes masculinos y del 4,5 % (3/66) para las pacientes femeninas (p=0,398). El MFM derecho en pacientes masculinos tuvo una incidencia de 8,1 % (3/ 37) y 4,5 % (3/66) para pacientes femeninos (p=0,340). Cuando se comparó la presencia de un OD entre el lado izquierdo (5,6 %) y derecho (5,8 %), no se encontraron diferencias estadísticamente significativas (p=0,998). La frecuencia de MFM de tres raíces bilaterales fue 71,43 % (5/7) y 28,57 % (2/7) fueron unilaterales. La prevalencia de RE en MFM en una subpoblación del sur de Chile fue de 5,7 %. La presentación fue bilateral en la mayoría de los casos y no se observaron diferencias significativas por sexo o lado. El tipo de ER más frecuente fue el tipo 1 (83,3 %). El uso de CBCT puede mejorar el resultado del tratamiento endodóntico.

Occlusal polygon area of the molars in six Colombian ethnic groups / Área del polígono oclusal de molares en seis grupos étnicos de Colombia

SUMMARY: Descriptive observational cross-sectional study to determine the AOP of the second molars (55, 65, 75, 85) and the first permanent molars (16, 26, 36 and 46) in 459 study models corresponding to six ethnic groups in Colombia, Embera indigenous of Alto Baudó (Chocó), Caucasoid mestizos of Cali (Valle del Cauca), African descent of Cali (Valle del Cauca), Misak indigenous of Silvia (Cauca), Nasa indigenous of Morales (Cauca), and indigenous of Leticia (Amazonas). There were no significant differences of AOP among the six ethnic groups except when compared to the Amazon Indians with African descent of Cali, Embera indigenous and Nasa indigenous. There was no sexual dimorphism except tooth 65 for all ethnic groups. There was bilateral symmetry except between teeth 16 and 26. The distance matrix showed that Caucasoid mestizos of Cali were grouped with microdont populations, Amazon indigenous, Embera indigenous, Misak indigenous and Nasa indigenous, and African descendants of Cali were grouped with mesodont populations. The Embera and Amazon indigenous had the highest values of OAP associated with the relative isolation and less mestizaje. Overall, there was no sexual dimorphism or bilateral asymmetry. This study coincides with the different theories about reducing the size of the teeth as evolutionary characteristic of hominids.

RESUMEN: Estudio observacional descriptivo de corte transversal en el que se determinó el APO de los segundos molars deciduos (55, 65, 75, 85) y de los primeros molares permanentes (16, 26, 36, 46) en 459 modelos de estudio correspondientes a seis grupos étnicos de Colombia: Indígenas embera del Alto Baudó (Chocó), mestizos caucasoides de Cali (Valle del Cauca), afrodescendientes de Cali (Valle del Cauca), indígenas misak de Silvia (Cauca), indígenas nasa de Morales (Cauca) e indígenas de Leticia (Amazonas). No se encontraron diferencias significativas en el APO de los seis grupos étnicos, excepto entre indígenas del Amazonas y de afrodescendientes de Cali, e indígenas embera e indígenas nasa. No se evidenció dimorfismo exual en ninguno de los seis grupos. Hubo simetría bilateral, excepto entre los dientes 16 y 26. La matriz de distancias demostró que los mestizos caucasoides de Cali se agrupan con poblaciones microdontes, indígenas del amazonas, indígenas embera, indígenas misak e indígenas nasa; mientras que los afrodescendientes de Cali se agrupan con poblaciones mesodentes. Los indígenas embera y del Amazonas presentaron altos valores del APO, asociado a su aislamiento relativo y bajo mestizaje. En términos generales, no hubo dimorfismo sexual ni asimetría bilateral. Los resultados de este estudio concuerdan con diferentes teorías sobre la reducción del tamaño dental como una característica evolutiva de los himínidos.

Bilaterality and symmetry of c-shaped mandibular second molars in a Mexican Maya and non-Maya population: a CBCT in vivo study / Bilateralidad y simetría de los segundos molares mandibulares en forma de c en una población mexicana Maya y no Maya: estudio in vivo mediante CBCT

SUMMARY: The objective of this study was to evaluate the bilaterality and symmetry in C-shaped mandibular second molars in Mexican Maya and non-Maya populations using cone-beam computed tomography (CBCT). Five-hundred-twenty-five CBCT scans of patients with left and right mandibular second molars were analyzed to determine the prevalence and bilaterality. The teeth were assessed for the presence of C-shaped root canals, according to Fan et al. (2004) criteria. The sample was subdivided by ethnicity, sex, unilateral/bilateral presence, side of the longitudinal groove, and the C-shaped root canal configuration and symmetry, at the cervical, middle, and apical cross- sections of the root. C-shaped mandibular second molars were present in 24.95% of the individuals. Most (60.30%) of those showing this trait had it bilaterally. When comparing by ethnicity, sex, and side, we detected no significant differences. The vast majority (97.33%) presented the groove along the lingual side. The C3 was the most prevalent configuration in the overall sample, while in the Maya group, the C1 was the most common configuration. When analyzed by sex and ethnic group, the non-Maya females tended to deviate from the other groups in terms of bilaterality. Overall, 55.70% of bilateral C-shaped mandibular second molars were also symmetric in the three radicular thirds. The prevalence of C-shaped mandibular second molars was similar to that reported for northernAsian populations, which is consistent with the evolutionary origins of Native American populations. Most of the sample showed bilaterality and half were symmetric. Clinicians must be aware of the ethnic background of their patients and consider the possible variations to do more predictable root canal treatments.

RESUMEN: El objetivo de este estudio fue evaluar la bilateralidad y simetría de los segundos molares mandibulares en forma de C en una población Mexicana Maya y no-Maya mediante tomografía computarizada de haz cónico (CBCT). Material and Métodos: Se analizaron quinientos veinticinco tomografías de pacientes con segundos molares mandibularesderecho e izquierdo para determinar la prevalencia y bilateralidad. Los dientes fueron evaluados según la presencia de conductos en forma de C de acuerdo a los criterios de Fan et al. La muestra fue subdividida por etnicidad, sexo, presencia bilateral/unilateral, lado del surco y configuración y simetría de los conductos en los cortes transversales cervical, medio y apical. Los segundos molares mandibulares en forma de C estuvieron presentes en el 24.95 % de los individuos. La mayoría (60.30%) de los que mostraron este rasgo lo hicieron de forma bilateral. El comparar por etnicidad, sexo y lado, no se encontraron diferencias estadísticamente significativas. La gran mayoría (97.33%) presentó el surco por lingual. C3 fue la configuración más prevalente en la muestra general, mientras que en el grupo Maya el C1 fue la más común. El análisis por sexo y grupo étnico arrojó que las mujeres no Mayas tendieron a desviarse de los otros grupos en términos de bilateralidad. El 55.70% de los segundos molares mandibulares bilaterales fueron simétricos en sus tres tercios radiculares. La prevalencia de los segundos molars mandibulares en forma de C fue similar a la reportada para las poblaciones del norte de Asia, lo cual es consistente con los orígenes evolutivos de las poblaciones nativas americanas. La mayor parte de la muestra presentó el rasgo de forma bilateral y la mitad de éstos fueron simétricos. Los odontólogos deben tomar en cuenta el origen étnico de sus pacientes y considerar las posibles variaciones para realizar tratamientos endodónticos más predecibles.

Correlation Between Mesio-Distal Teeth Diameters and Arch Width

ABSTRACT Objective: To verify the existence of a correlation between the mesio-distal size of teeth and the arch width by analyzing the data separately for maxillary and mandibular arch in patients with ideal occlusion Material and Methods: 58 patients with ideal occlusion were studied, for a total of 276 files analyzed. Dental casts were then scanned using a professional scanner (Epson Perfection v 330) and images were obtained in TIFF format at 600 dpi. All single teeth measurements were carried out for all teeth of both arches using the VAM software (Vectra, Canfield Scientific, Fairfield, NJ, USA). The repeatability and reproducibility of the measurement method were evaluated using the Gauge R&R method. In case a correlation between tooth size and arch size is found to be significant, a linear regression analysis can be applied through the following statistical relationship: y=a+b*x, where y is the result (inter-molar distance "AvgB66" or inter-canine distance "Cusp 33"), and x the specific tooth. The a and b respectively represent the intercept (point of intersection between the line and the y axis) and the slope of the line that describes the regression ratio. Results: The statistical analysis highlights a significant correlation (p<1%) between the results of the mesio-distal measurements of each tooth and the two variables considered to define the size of each arch ("AvgB66" and "Cusp 33"). Based on these results, a numerical relationship "y=a+b*x" has been extrapolated. Thus, it is possible to calculate the estimated inter-molar or inter canine distance necessary to have the teeth aligned. Conclusion: The inter-canine and inter-molar distances can be estimated starting from measuring the mesio-distal diameter of a single tooth.

Dentin Thickness of Pulp Chamber Floor in Primary Molars: Evaluation by Cone-Beam Computed Tomography

ABSTRACT Objective: Use cone-beam computed tomography (CBCT) images to evaluate the dentin thickness of the pulp chamber floor in primary molars. Material and Methods: Cross-sectional study, conducted with CBCT images of teeth of children. Primary molars with preserved pulp chamber floor were included. The dentin thickness of the pulp chamber floor in the primary molars was measured linearly in CBCT cross-sections. Data were descriptively analyzed and the Mann-Whitney test was applied (p<0.05). Results: 27 CBCT exams and 123 primary molars of children aged 4 to 13 years were analyzed; the majority was female (52.0%). In maxillary molars, the median dentin thickness was 1.50 (0.6-2.2) mm in the first and 1.65 (0.6-2.3) mm in the second (p=0.049) molars. In mandibular molars, the median was 1.20 (0.3-1.7) mm in the first and 1.60 (1.0-2.2) mm in the second (p<0.001) molars. Children aged 4 to 8 years showed less dentin thickness (p<0.001). Conclusion: The median dentin thickness of the pulp chamber floor in primary molars was 1.50 mm, ranging from 0.3 to 2.3 mm. Less dentin thickness was associated with younger children, teeth in the mandibular arch, and first molars.

Influence of Isolation Technique on the Survival of Resin-Modified Glass-Ionomer Restorations in Primary Molars: A 9-Months Randomized Controlled Trial

ABSTRACT Objective: To compare the survival of occlusal and occlusal-proximal restorations performed with resin-modified glass-ionomer cement (RMGIC) in deciduous molars using rubber dam and cotton rolls isolation. Material and Methods: Ninety-two patients were included and 200 deciduous molars with cavitated occlusal or occlusoproximal dentin caries lesions were randomized into two groups: cotton rolls (n = 100) and rubber dam (n = 100) and RMGIC restorations were placed. At baseline and in the follow-up visit, presence, severity and activity of caries lesions were registered. Two independent, blinded examiners evaluated the treated teeth clinically using the USPHS criteria and radiographically after 9 months. Descriptive analysis, survival curve (log-rank test) and Cox regression were performed to assess risk factors related to failure. Results: Out of the 179 teeth (92 cotton rolls group and 87 rubber dam group) evaluated at 9-month follow-up period. No lesion progression was observed radiographically. The overall treatment success rate was 85.47% (83.47% for cotton rolls and 87.35 rubber dam group). No significant difference between isolation methods was observed in the log-rank test (p = 0.16). Cox regression showed no risk factors related to failure. Conclusion: No difference was found in the survival of occlusal and occlusal-proximal restorations performed with RMGIC in deciduous molars using a rubber dam and cotton rolls isolation after a 9-month follow-up period.

Evaluation of Masticatory Performance and Patient Satisfaction Before and After Posterior Implant Restoration

ABSTRACT Objective: To evaluate the improvement in masticatory performances two weeks after posterior implant restoration. Material and Methods: Nine patients with missing first and second molars were included in the study. Masticatory performances were evaluated using subjective and objective methods utilizing color-changeable chewing gum and the visual analog scale (VAS) assessment. The subjects were asked to chew the color-changeable chewing gums before and two weeks after the posterior implant restoration. Their expectations regarding aesthetics and function were verified on the VAS before implant placement. Additionally, the VAS was used for the posttreatment completion rating two weeks after the implant restoration. Results: Significant differences in masticatory performance were noted at baseline (before implant posterior restoration) and two weeks after implant restoration (p<0.05). The posttreatment aesthetic and functional expectations ratings significantly exceeded the expectations (p<0.05). Conclusion: Masticatory performances were improved two weeks after implant restoration. In addition, the significant posttreatment ratings of the patients exceeded their initial expectations. In particular, patients with poor masticatory functions demonstrated significant improvements and satisfaction following implant restoration compared to those with good mastication. These findings indicate that a posterior implant restoration can increase the masticatory performance.

Tooth Coronal Index: A Novel Tool For Age Estimation on Cone-Beam Computed Tomography

ABSTRACT Objective: To evaluate dental age assessment reliability through Tooth Coronal Index (TCI) method. Material and Methods: The cone-beam computed tomography (CBCT) scans of 160 individuals aged between 20-70 years were analyzed in the present study. The height of the crown, i.e., coronal height, and the height of the coronal pulp cavity, i.e., coronal pulp cavity height, of mandibular second premolars and first molars were calculated and then TCI was measured. The actual age of a subject was compared with TCI of tooth and the acquired data were subjected to Pearson's correlation and unpaired t-tests. Results: Negative correlation was observed between the real age and TCI of mandibular first molar (r = -0.094, p=0.382) and second premolar (r = -0.176, p=0.0961. Statistically significant difference was observed between actual age and TCI for mandibular second premolar and first molar (p<0.001). Conclusion: Tooth coronal index has the potential to estimate age of an individual on CBCT scans. It is simple, cost-effective than histological methods and can be applied to both living and unknown dead.

Clinical and radiographic examination compared to microscopic examination in the detection of anatomical features of mesiobuccal canals in maxillary first molars: a diagnostic study / Comparación entre examen radiológico y clínico con examen microscópico en la detección de características anatómicas de los canales mesiobucales en los primeros molares maxilares: un estudio diagnóstico

SUMMARY: The aim of the present study was to determine the accuracy, sensitivity, and specificity of the clinical and radiographic examination (CRE) method compared to the examination with the dental operating microscope (DOM) on the detection of anatomical features of mesiobuccal canals in maxillary first molars. One hundred maxillary first molars were selected to assess the number of canals orifice entrances, accessibility, and ending of their mesiobuccal canals using the CRE method and the examination with the DOM. The diagnostic tests of the CRE exhibited, in general, high levels of accuracy, sensitivity, and specificity. However, low levels of these outcomes occurred, mainly, on the detection of the number of canals entrance orifices of the mesiobuccal root. The statistically significant differences (p<0.05) occurred for accessibility and ending of canals in 61 of the 62 cases (out of 100) when two of them were present: 2 accessible root canals (48 cases; 77.42 %), and 1 accessible and 1 inaccessible canals (13 cases; 20.97 %); 1 foramen after fusion (18 cases; 29.03 %), 2 foramens (30 cases; 48.39 %), and 1 foramen and 1 blind foramen (13 cases; 20.97 %). This study proves that the clinical and radiographic method (still the most commonly used worldwide) can't be trusted absolutely in situations of complex internal anatomy regarding the mesiobuccal root canals of maxillary first molars.

RESUMEN: El objetivo del presente estudio fue determinar la precisión, sensibilidad y especificidad del método de examen clínico y radiográfico (ECR) en comparación al examen con el microscopio quirúrgico dental (MQD) en la detección de características anatómicas de los canales mesiovestibulares en primeros molares maxilares.Se seleccionaron 100 primeros molares maxilares para evaluar el número de entradas de los canales, la accesibilidad y la terminación de sus canales mesiovestibulares utilizando el método ECR y el examen con el MQD.Las pruebas de diagnóstico del ECR exhibieron, en general, altos niveles de precisión, sensibilidad y especificidad. Sin embargo, también hubo niveles bajos de estos resultados, principalmente, en la detección del número de orificios de entrada a los canales de las raíces mesiovestibulares. Hubo diferencias estadísticamente significativas (p<0,05) para la accesibilidad y terminación de los canales en 61 de los 62 casos (del total de 100), cuando dos de ellos estaban presentes: 2 canales radiculares accesibles (48 casos, 77,42 %), y 1 accesible y 1 inaccesible (13 casos, 20,97 %). Después de la fusión, un orificio (18 casos, 29,03 %), 2 orificios (30 casos, 48,39 %) y 1 orificio más otro, ciego (13 casos, 20,97 %). Este estudio demuestra que no se puede confiar plenamente en el método clínico y radiográfico (todavía el más utilizado en todo el mundo), cuando existe una anatomía interna compleja de los canales de la raíz mesiovestibular de los primeros molares superiores.

Mylos root in terminologia anatomica / Raíz mylos en terminologia anatomica

The current International Terminologia Anatomica is written in latin and from it, the translation into the corresponding language is carried out. There are terms of greek origin that sometimes do not fully describe the anatomical structure. In this context, the mylos root, present in mylohyoid word, is defined in greek " like a mill" or "resembling a tooth". However, this definition does not accurately represent the mylohyoid structures that it describes. Therefore the question arises: is the mylos root the most appropriate one for naming these structures?.

La actual Terminologia Anatomica (TA), se encuentra redactada en latín y a partir de ella se realiza la traducción al idioma correspondiente. Existen en ella términos de origen griego que en ocasiones no describen a cabalidad la estructura anatómica. En este contexto la raíz mylos, presente en milohioideo(a), se define en griego "como de un molino" o "semejante a una muela", sin embargo, esta definición no precisa las estructuras milohioideas que se desean describir. Entonces surge la interrogante, ¿es la raíz mylos la más adecuada para denominar esas estructuras?.

Prevalencia y morfología del segundo conducto en la raíz mesiovestibular de primeros molares superiores en base a cuatro técnicas ex vivo / Prevalence and morphology of second mesiobuccal canal in maxillary first molars based on four ex vivo techniques

Los objetivos principales del tratamiento de endodoncia no quirúrgico son la prevención y/o tratamiento de periodontitis apical junto con la resolución de signos y síntomas de las lesiones pulpares irreversibles. Debido a la compleja morfología del sistema de conductos radicular, la persistencia de un conducto no tratado puede mantener la contaminación y sintomatología pulpar y periapical. La prevalencia para MV2 reportado a nivel mundial para el primer molar superior varía ampliamente según las técnicas in vivo o ex vivo empleadas en cada estudio, es por esto que el presente trabajo tiene por objetivo evaluar la prevalencia de MV2 en primeros molares superiores en base a cuatro técnicas diagnósticas aplicadas ex vivo. Se realizó un estudio transversal observacional en 101 primeros molares superiores extraídos bajo consentimiento informado para determinar la prevalencia del conducto MV2 y su morfología en base a las técnicas de radiografía ortoradial, tomografía Cone Beam, apertura coronaria con microscopio quirúrgico (16x) y cortes radiculares axiales de aplicación ex vivo. La prevalencia encontrada para MV2 por cada técnica fue de 81,1 % para cortes radiculares y tomografía Cone Beam, 59,4 % para la apertura coronal con microscopio (16x) y 32,6 % con radiografía ortoradial. En el 3,96 % de la muestra se encontró un tercer conducto mesiovestibular en base a la técnica de corte radicular. La morfología interna del sistema de conductos radiculares fue de 36 % clase II, 19 % clase I y 16 % clase IV de Vertucci. Los resultados del presente estudio están en concordancia con lo reportado en la literatura y confirman la mayor prevalencia reportada en estudios ex vivo para esta situación. La presencia de MV2 en el primer molar superior es una condición frecuente que el endodoncista debe considerar, empleando técnicas imagenológicas y tecnologías de magnificación para asegurar el éxito terapéutico en estos dientes.

The main objectives of non-surgical endodontic treatment are the prevention and / or treatment of apical periodontitis, as well as resolving signs and symptoms of irreversible pulpal lesions. Considering the complex morphology of the root canal system, the a canal left untreated, can generate contamination, pulp and periapical symptoms. The prevalence for MV2 reported worldwide for the upper first molar, varies depending on the ex vivo or ex vivo techniques used in each study. Consequently, the present work aims to assess the prevalence of MV2 in first upper molars based on four ex vivo diagnostic techniques applied. An observational crosssectional study was performed in 101 upper first molars extracted under informed consent to determine the prevalence of the MV2 duct and its morphology based on orthoradial radiography, Cone Beam tomography, coronary opening with a surgical microscope (16x), and axial root cuts applied ex vivo. The prevalence found for MV2 by each technique was 81.1 % for root cuts and Cone Beam tomography, 59.4 % for coronal opening with a microscope (16x) and 32.6 % with orthoradial radiography. In 3.96 % of the sample, a third mesiovestibular canal was found based on the root cutting technique. The internal morphology of the root canal system was 36 % Vertucci´s class II, 19 % class I and 16 % class IV. The results of the present study coincide with that reported in the literature, and confirm the higher prevalence reported in ex vivo studies for this situation. The presence of MV2 in the upper first molar is a frequent condition that the endodontist must consider, using imaging techniques and magnification technology to ensure therapeutic success in these teeth.

A micro-CT evaluation of the performance of rotary and reciprocating single-file systems in shaping ability of curved root canals

Abstract To compare the shaping ability of different single-file systems in the preparation of mesial curved canals of mandibular molars using micro-CT technology. Fifteen mesial roots of mandibular molars with two independent and curved canals (n = 30) were selected, scanned at a resolution of 26.7 μm anatomically matched, and distributed into three groups (n = 10), according to the preparation system: WaveOne 25.08, Reciproc 25.08, and OneShape 25.06. A final micro-CT scanning was performed, data sets were registered with their respective counterparts, and compared regarding the three-dimensional (volume, surface area, and structure model index - SMI) and two-dimensional (perimeter, area, roundness, major and minor diameters) parameters, as well as, canal transportation, using ANOVA and post hoc Tukey tests (α = 5%). Overall, no difference was observed between groups regarding area, perimeter, volume, surface area, and canal transportation (p > 0.05). Within group, no canal transportation was significantly higherobserved in the apical third (0.10 ± 0.05 mm) compared to coronal (0.08±0.040 mm) and middle (0.07 ± 0.03 mm) thirds (p < 0.05). Structure model index (SMI) was statistically higher after preparation with OneShape instrument (0.36 ± 0.26) compared to other systems (p < 0.05). Within the parameters of this study, similar shaping ability was observed in the preparation of mesial curved root canals of mandibular molars with Reciproc, OneShape and WaveOne systems.

Consideraciones Metodológicas en el Estudio Histomorfométrico del Hueso Interradicular de los Primeros Molares Inferiores de Ratas Wistar / Methodological Considerations in the Histomorphometric Study of the Interradicular Bone of the First Lower Molars of Wistar Rats

El objetivo fue evaluar el volumen óseo BV/TV (%) del hueso interradicular en ratas Wistar: A) en relación a la edad; B) en relación a la zona de estudio en animales de la misma edad. Se utilizó Grupo A) 15 ratas Wistar hembras de 6 (I), 10 (II) y 14 (III) semanas, Grupo B) 9 ratas Wistar macho de 8 semanas. Tras la eutanasia, se extrajeron los maxilares inferiores y se procesaron histológicamente para obtener cortes mesio-distales del primer molar inferior coloreados con H.E. Sobre microfotografías digitales se evaluó el BV/TV (%). El análisis estadístico se realizó en A) mediante ANOVA y Bonferroni test y en B) se calculó el rango (R). Los resultados en A) el BV/TV (%) aumenta significativamente con la edad de los animales; en B) se encontró que el BV/TV (%) varía hasta un 20% si se considera el volumen total y este rango disminuye a 8.3% al estudiar su mitad coronal. En conclusión, el BV/TV (%) del hueso interradicular del primer molar inferior de ratas Wistar varía considerablemente con la edad de los animales y en animales de una misma edad -según se considere evaluar todo el hueso interradicular del espacio alveolar o la mitad superior del mismo-. Los resultados de este trabajo recomiendan emplear animales de la misma edad y realizar mediciones histomorfométricas empleando la mitad coronal de dicho hueso, especialmente en los diseños de periodontitis experimental (AU)

Prevalencia del Molar en C: estudio Transversal / Prevalence of C-Shaped Molar: cross-sectional Study

El objetivo fue evaluar mediante tomografía computarizada de haz cónico (CBCT), la prevalencia y tipología de conductos en C en molares inferiores. Se analizaron 422 CBCT y 1105 molares inferiores de pacientes de ambos géneros, mayores de 10 años, obtenidas en 2018. Variables registradas: género, número de pieza, y tipología, según clasificación anatómica de Fan, en los tres tercios. Se observaron cortes coronario, medio y apical. Se compararon frecuencias observadas con frecuencias esperadas bajo suposición de independencia, se utilizó prueba de bondad de ajuste de Chi-cuadrado. La comparación de pares de porcentajes se realizó con prueba de diferencia de proporciones de Pearson Chi-cuadrado con p-valores simulados por prueba de Monte Carlo. Según los resultados, el molar en C no se distribuyó homogéneamente en las tomografías analizadas. Chi-cuadrado (X2=264.13 p-valor <2,2) (p-valor dos colas <0.001), tampoco se distribuyó homogéneamente en el total de piezas dentarias Chi-cuadrado (X2=1011,1, p-valor <2.2e-16) (p-valor dos colas <0.001). Las variables género y presencia de molar en C no se distribuyeron independientemente, Chi-cuadrado (X2=4.7367, p-valor =0,042) (p-valor<0,05). Las variables tipología y piezas dentarias no se distribuyeron independientemente, Pearson Chi-cuadrado (p-valor<0.001), al igual que las variables tipología y tercios, Pearson Chi-cuadrado (p-valor<0.001). En conclusión, la CBCT es valiosa para identificar estas anatomías. Haber encontrado mayor prevalencia de tipología I confirma lo establecido en la literatura. Tienen alta prevalencia en las poblaciones asiáticas pero en caucásica son poco frecuentes (3%) (AU)

Limitation of diagnostic value of cone-beam CT in detecting apical root isthmuses

Abstract Isthmuses are reported as common anatomic complexities in teeth often associated with failures in endodontic treatment. They should be considered before starting treatment and a preoperative computed tomography scan (CT) may demonstrate these complexities. Objective To assess the diagnostic value of the highest resolution settings of a cone-beam CT (CBCT) system in identifying and measuring apical isthmuses, using micro-CT as reference. Methodology After micro-CT scanning, 40 humans' lower first molars with isthmuses in the apical-3 mm of mesial roots were scanned by the highest resolution settings of the New Generation i-Cat ® CBCT equipment. Two blinded observers recorded the detection of isthmuses in CBCT scans. The lengths of isthmuses were compared between micro-CT and CBCT to assess the diagnostic value of CBCT. Quantitative data for sensitivity were represented as percentages (95% confidence interval). The Bland-Altman method was used to assess differences between gold standard lengths (micro-CT) and CBCT lengths. Results BCT demonstrated 30 positive findings, representing sensitivity for isthmus identification of 75% (95% CI=0.4114-1.1364). Differences between the lengths in micro-CT (1.99±0.40 mm) and CBCT (1.53±0.41 mm) were significant (p<0.0001). Conclusion The CBCT device used presented limited diagnostic value in the identification and measurement of apical isthmuses in the mesial roots of lower molars. In some cases, the actual anatomy of the apical root canal may not be completely delineated in this type of CBCT system, even using the highest resolution settings.

Comparative Measurement of Tooth Length: Actual vs. Orthopantomography and CBCT-Based Measurements

Objective: To compare the reliability of cone beam computed tomography (CBCT) in assessing the tooth length in comparison to orthopantomography (OPG). Material and Methods: Forty patients scheduled for extraction as result of caries or periodontal involvements were randomly selected. Panoramic radiographs and CBCT images were obtained and subsequently patients were subjected for extraction. Teeth with poor prognosis were extracted and stored in 10% formalin. Radiographic teeth measurements were carried out on OPG and CBCT images using a software and the actual tooth length (A-L) measurements were carried out with a digital vernier caliper. The data collected were statistically analyzed for paired "t" test significance of differences and Pearson's correlation at 5% level of confidence. Results: There was significant difference comparing all three actual tooth length (A-L) and CBCT- and OPG-measured tooth lengths. A significant positive correlation was observed among all the measurements. Conclusion: CBCT images exhibited accuracy over panoramic images even though the measurements are still significantly different from actual anatomical tooth lengths.

Internal configuration of maxillary molars in a subpopulation of Brazil's Northeast region: A CBCT analysis

Abstract The present study aimed to evaluate the internal configuration of the maxillary molars of a population from the Northeast region of Brazil. Cone-beam computed tomography (CBCT) exams from 512 patients (1501 teeth) were evaluated regarding the anatomical configuration of the root canal system, according to Vertucci's classification. The images were obtained using a Prexion 3D scanner operating at 90 kVp and 4 mA. The voxel size was 0.125 mm and the cut thickness was 1 mm. The images were then analyzed in the Prexion 3D Viewer software. The data were analyzed statistically by Pearson's chi-square test, with 5% of significance. The first and second molars presented three roots in 99.14% and 87.27% of the cases, respectively. In relation to the number of canals, the first and second molars had a significantly higher frequency of three and four root canals respectively, presenting a higher prevalence of types I and II (p < 0.001). The second mesiobuccal canal (MB2) was observed in 48.21% and 22.72% of the first and second molars, respectively (p < 0.001). The identification of the MB2 canal was greater in young and adult patients (p < 0.001), presenting a higher prevalence in male patients (p < 0.001). The internal configuration of the MB root was influenced by gender and by age, presenting a higher prevalence of the MB2 in male patients younger than 50 years of age.

Radix entomolaris: reporte de caso / Radix entomolaris: report of a case

Una de las variaciones anatómicas que pueden presentar los molares inferiores es una tercera raíz que ha sido denominada radix entomolaris o paramolaris dependiendo de su localización, ya sea lingual o vestibular respectivamente. Conocer las variaciones morfológicas de las piezas dentarias es un requisito fundamental para el éxito del tratamiento endodóntico. El objetivo de este artículo es la presentación de un caso clínico de una paciente con ambos primeros molares inferiores con presencia de radix entomolaris; en la pieza dentaria 4.6 se realizó tratamiento endodóntico y en 3.6 con una lesión endoperiodontal combinada verdadera se decidió su exodoncia (AU)