Segundo Conducto Mesiovestibular en Molares Superiores: Prevalencia y Análisis Anatómico Mediante Tomografía Computarizada de Haz Cónico / Second Mesiobuccal Canal in Maxillary Molars: Prevalence and Anatomical Analysis Through Cone Beam Computed Tomography

El objetivo de este estudio fue utilizar la Tomografía Computarizada de Haz Cónico (TCHC) para investigar la configuración anatómica, prevalencia y distribución del conducto mesiovestibular Dos (MV2) en molares superiores de una subpoblación chilena, considerando variables como la presencia del conducto MV2, la clasificación de Vertucci, el género y edad. Estudio observacional de corte transversal. La muestra consistió en Tomografías Computarizadas de Haz Cónico tomadas en la clínica odontológica de la Universidad Andrés Bello (Viña del Mar). Se calculó el tamaño muestral utilizando la fórmula de población conocida, lo que resultó en 262 tomografías. Los examinadores se calibraron utilizando el coeficiente Kappa de Cohen, para luego analizar las variables mediante un estudio imagenológico utilizando el software I-CAT Visión. Se analizaron 439 primeros y segundos molares superiores. La prevalencia del conducto MV2 en primeros molares fue del 63,74 %, mientras que, en segundos molares, fue del 20,04 %. La prevalencia en primeros molares fue mayor en hombres (73,86 %) que en mujeres (58,62 %), mientras que, en segundos molares, fue del 15,81 % en mujeres y del 28,41 % en hombres. En relación con la edad, en los primeros molares la diferencia fue significativa en el rango de 18 a 40 años (66,49 %). En cuanto al tipo de configuración según Vertucci (2005), el 70 % de los primeros molares presentó una configuración Tipo II, y un 23,65 % Tipo IV, con resultados similares en los segundos molares. El presente estudio demostró que los conductos MV2 son frecuentes en la población analizada, especialmente en los primeros molares, y que la configuración Tipo II es la más prevalente. Además, se observó una mayor prevalencia en hombres y en el rango de 18 a 40 años. Estos hallazgos proporcionan información relevante sobre la anatomía radicular en la población y pueden contribuir a mejorar los resultados de tratamiento.

SUMMARY: The aim of this study was to use Cone-beam Computed Tomography (TCHC) to investigate the anatomical configuration, prevalence, and distribution of the Second Mesiobuccal (MB2) canal in upper molars of a Chilean subpopulation, considering variables such as the presence of MB2 canal, Vertucci classification, gender, and age. Cross-sectional observational study. The sample consisted of TCHC scans taken at the dental clinic of Universidad Andrés Bello (Viña del Mar). The sample size was calculated using the formula for known population, resulting in 262 scans. The examiners were calibrated using Cohen's Kappa coefficient, then the variables were analyzed through an imaging study using I-CAT Vision software. 439 first and second upper molars were analyzed. The prevalence of MB2 canal in first molars was 63.74 %, while in second molars, it was 20.04 %. The prevalence in first molars was higher in males (73.86 %) than in females (58.62 %), while in second molars, it was 15.81 % in females and 28.41 % in males. Regarding age, in first molars the difference was significant between the age range of 18 to 40 years (66.49 %). Regarding the type of configuration according to Vertucci, 70 % of the first molars had Type II configuration, and 23.65 % had Type IV, with similar results in second molars. The present study demonstrated that MB2 canals are frequent in the analyzed population, especially in first molars, and Type II configuration is the most prevalent. Additionally, a higher prevalence was observed in males and in the age range of 18 to 40 years. These findings provide relevant information about root anatomy in the studied population and can contribute to improving treatment outcomes.

Assessment of Mesial Root Morphology and Frequency of MB2 Canals in Maxillary Molars using Cone Beam Computed Tomography / Determinación de la Morfología de la Raíz Mesial y la Frecuencia del Canal MB2 en Molares Maxilares usando Tomografía Computadorizada de Haz Cónico

The aim of this study was to assess the morphology of the mesial root canal system of maxillary molars and the frequency of MB2 canals using cone-beam computed tomography (CBCT). A total of 1374 teeth, first maxillary (1MS, n= 802) and second maxillary molars (2SM, n= 572) of 508 Chilean patients between 8 to 77 years were evaluated through CBCT. The mesiobuccal root was evaluated in all three thirds. Root canal morphology was classified according to Vertucci's method. Data were analyzed by Pearson's Chi-square and Cuzick trend tests. MB2 canal frequency in 1MS was 73.44% and in 2MS 42.48%. The most frequent morphology in 1MS and 2MS were Vertucci type II and I, respectively. No statistically significant association was found between frequencies and side or according to gender (P>0.05). A positive association was found as the age increased in both 1MS and 2MS (P<0.001 and P= 0.023, respectively). Given the anatomical complexity of the mesiobuccal root and the frequent presence of the MB2 canal, the clinician must assume the existence of two canals in this root. CBCT scanning is a good way to initially identify this canal in the different root thirds.

Determinar la morfología del sistema de canales de la raíz mesial de molares maxilares y la frecuencia del canal MB2 usando tomografía computadorizada de haz cónico (TCHC). Un total de 1374 dientes, primeros molares maxilares (1MS, n= 802) y segundos molares maxilares (2MS, n= 572) de 508 pacientes Chilenos entre 8 y 77 años fueron evaluados a través de la TCHC. Se evaluó la raíz mesiobucal en todos sus tercio. La clasificación de Vertucci fue utilizada para determinar la morfología del sistema de canales. Los datos fueron analizados con los test Chi-Cuadrado de Pearson y la prueba de tendencia de Cuzick. La frecuencia del canal MB2 para el 1MS fue 73,44% y el 2MS 42,48%. La morfología mas frecuente en el 1MS y 2MS fueron el tipo II y I de Vertucci, respectivamente. No se encontró asociación significativa entre la frecuencia y el lado o sexo (p>0,005). Una asociación positive fue encontrada a medida que aumentaba la edad en ambos 1MS y 2MS (p<0,001 y p= 0,023, respectivamente). Dada la complejidad de la anatomía de la raíz mesiobucal y la frecuente presencia del canal MB2, el clínico debe asumir la existencia de dos canales en esta raíz. La TCHC es una buena manera de identificar tempranamente el canal en los diferentes tercio radiculares.

Construction of conditionally replicative adenovirus vector carrying TRAIL gene and its mRNA and protein expressions induced by ionizing radiation / 吉林大学学报(医学版)

Objective To construct the conditionally replicative adenovirus vector pAd-Egr1-TRAIL-hTERT-E1A-E1Bp-E1B55K carrying early growth response gene-1 (Egr1)promoter and tumor necrosis factor related apoptosis inducing ligand (TRAIL)gene, and to observe the effects of the vector combined with 2 Gy irradiation on the TRAIL expression in MDA-MB-231 cells.Methods Egr-1 promotor sequence was cloned from pMD18 T-Egr1, TRAIL was constructed the downstream of Egr1 promoter, pShuttle-Egr1-TRAIL-hTERT-E1A-E1Bp-E1B55K (CRAd.pEgr1-TRAIL)was constructed,after the adenovirus vector was packaged successfully,MDA-MB-231 cells were infected with them and irradiated with X-rays.Real time PCR method and ELISA were used to detect the expression levels of TRAIL mRNA and protein, respectively. Six groups in the experiment were set up:control, 2 Gy,CRAd.p,CRAd.pEgr1-TRAIL,CRAd.p + 2 Gy and CRAd.pEgr1-TRAIL + 2 Gy. Results The recombinant adenovirus vector pAd-Egr1-TRAIL-hTERT-E1A-E1Bp-E1B55K was constructed and packaged successfully.The expression level of TRAIL mRNA in MDA-MB-231 cells transfected with the vector of 5 MOI for 24 h following 2.0 Gy X-rays irradiation began to increase and arrived to the top 8 h later in various groups,then declined.The expression level of TRAIL protein in MDA-MB-231 cells began to increase 6 h after irradiation and reached to the peak 24 h later,then declined 48 h later.There were significant differences in the expression levels of TRAIL protein between CRAd.pEgr1-TRAIL + 2.0 Gy and other groups at the same time point (P<0.01). Conclusion The recombinant adenovirus vector is obtained successfully, and the TRAIL mRNA and protein expression levels in MDA-MB-231 cells can be increased significantly by the vector combined with 2.0 Gy X-rays irradiation.

MB2 canal detection using dental loupe and ultrasonic tip

Background: In Vietnam, using dental loupe and ultrasonic tip to detect MB2 canal in mesiobuccal roots of maxillary molars is appropriate and necessary. Objective: The purpose of this study is to assess the effectiveness of magnification and dentine removal when locating the second mesiobuccal canal (MB2) in mesiobuccal roots of maxillary molars. Subject and methods: 49 mesiobuccal roots of maxillary molars were collected and studied. Conventional access of the cavity was prepared. After that, the MB1 and 2 canals in mesiobuccal roots were located in three stages. Stage 1: canals were located with no magnification. Stage 2: additional canals in the same teeth were located under magnification with a dental loupe. Stage 3: additional canals in the same teeth were located by removing dentine from the pulp chamber floor within 3mm from the MB1 canal towards the palatal canal in a groove 2 mm deep using ultrasonic tip (P5, Salatec). Result: The frequency of MB2 canal detection for an ultrasonic tip, dental loupes, and no magnification groups was 77.6%, 59.2% and 24.5%, respectively. Conclusion: Based on these results, more emphasis should be placed on the importance of using magnification dental ultrasonic tip to locate the MB2 canal.

Clinical feature and treatment of the second mesiobuccal canals of maxillary molars / 实用口腔医学杂志

Objective:To discuss the clinical feature and treatment of second mesiobuccal canal (MB2)of permanent maxillary molars. Methods:The root canals of 106 maxillary first molars and 80 maxillary second molars were explored with small size K files. The frequency and morphology of root canals were recorded. The canals of all cases were instrumented by Ni-Ti rotary instruments Hero 642, and obturated with lateral condensation technique. The efficiency of preparation and obturation was analyzed with radiographs before and after treatment. Results:The frequency of MB2 canal in maxillary first and second molars were 82.1% and 45.0%. Most MB2 was very fine and negotiated by size 8 or 10 file combined with EDTA. No transportation, ledge, or perforation was found except that one hand file was separated. Good result of treatment was achieved in most cases. Conclusion:The incidence of MB2 canals of maxillary first molars was higher than that of second molars, and most of them were very fine. The MB2 canals can be negotiated with small size file combined with EDTA, and shaped well with Ni-Ti rotary instruments.