Meta-analysis of the efficacy of invisible orthodontic appliances for maxillary molar distalization in adult patients / 口腔疾病防治

Objective@#To evaluate the clinical efficacy of invisible orthodontic appliances without brackets for the distal movement of maxillary molars to improve the ability of orthodontists to predict treatment outcomes.@*Methods@#Web of Science, Cochrane Library, Embase, PubMed, Wanfang Database, CNKI Database, and VIP Database were searched for studies investigating the efficacy of invisible orthodontic appliances for distal movement of maxillary molars in adult patients and published from database inception to August 1, 2023. A total of three researchers screened the studies and evaluated their quality and conducted a meta-analysis of those that met quality standards.@*Results@#This study included 13 pre- and postcontrol trials with a total sample size of 281 patients. The meta-analysis revealed no significant differences in the sagittal or vertical parameters of the jawbone after treatment when compared with those before treatment (P>0.05). The displacement of the first molar was MD=-2.34, 95% CI (-2.83, -1.85); the displacement was MD=-0.95, 95% CI (-1.34, -0.56); and the inclination was MD=-2.51, 95% CI (-3.56, -1.46). There was a statistically significant difference in the change in sagittal, vertical, and axial tilt of the first molar before and after treatment. After treatment, the average adduction distance of the incisors was MD=-0.82, 95% CI (-1.54, -0.09), and the decrease in lip inclination was MD=-1.61, 95% CI (-2.86, -0.36); these values were significantly different from those before treatment (P<0.05).@*Conclusion@#Invisible orthodontic appliances can effectively move the upper molars in a distal direction and control the vertical position of the molars. When the molars move further away, there is some degree of compression and distal tilt movement, which is beneficial for patients with high angles. The sagittal movement of incisors is beneficial for improving the patient's profile.

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.

Maxillary Molar Root Canal Morphology Using Cone-Beam Computed Tomography: An Epidemiological Study from Shandong Province, China / Morfología del Conducto Radicular del Molar Maxilar Mediante Tomografía Computarizada de Haz Cónico: Un Estudio Epidemiológico de la Provincia de Shandong, China

SUMMARY: The objective of this study was to evaluate the maxillary molar root canal morphology in individuals from the Shandong province, China, using cone-beam computed tomography (CBCT) and classify it based on Ahmed et al. (2017) classification system to obtain a reference for clinical diagnosis and treatment. From December 2020 to June 2021, we screened CBCT data of 1,619 patients at the Jinan Stomatological Hospital who had been indicated for CBCT because of various oral abnormalities. The root and root canal morphologies of all teeth were statistically analyzed, and the root canal morphology was classified based on Ahmed et al. (2017) classification system. In the maxillary molars, three roots were the most common, accounting for 99.24 % and 74.61 % of all maxillary first and second molars, respectively. Two roots were the second most common, accounting for 0.66 % and 17.29 % of all maxillary first and second molars, respectively. Root morphology variation, e.g., fusion or furcation defect, was present in 22 (0.76 %) maxillary first molars and 765 (25.39 %) maxillary second molars, with the most common being mesiobuccal and distobuccal root fusion. Detection rates of a second mesiobuccal canal (MB2) in the maxillary first and second molars were 48.5 % and 26.5 %, respectively. Among age groups, the frequency of MB2 was the highest in the 15-24-year-old group and lowest in the 55-64-year-old group. Bilateral MB2 root canals were present in 64.8 % and 48.4 % of the maxillary first and second molars, respectively. Men and women accounted for 60.6 % and 67.8 % of the maxillary first molars, respectively, and 51.7 % and 45.6 % of the maxillary second molars, respectively. According to Ahmed et al. (2017) classification of root canal morphology, 18 and 22 root canal configurations were found in 1,453 right maxillary first molars and 1,444 left maxillary first molars, respectively. The right maxillary first molars showed three two-rooted, 14 three-rooted, and one four-rooted type. The left maxillary first molars showed two one-rooted, six two-rooted, and 14 three-rooted types. According to Ahmed et al. (2017) classification of root canal morphology, 43 and 45 root canal configurations were found in 1,507 right maxillary second molars and 1,506 left maxillary second molars, respectively. The right maxillary second molars showed 17 one-rooted, 16 two- rooted, eight three-rooted, and two four-rooted types. The left maxillary second molars showed 19 one-rooted, 13 two-rooted, 12 three- rooted, and one four-rooted type. This study showed that the maxillary molar root canal morphology is diverse in the Shandong province. Ahmed et al. (2017) classification system provides a clear description of the root canal morphology. CBCT can be used to study complex root and root canal morphologies.

El objetivo de este estudio fue evaluar la morfología del conducto radicular del molar superior en individuos de la provincia de Shandong, China, utilizando tomografía computarizada de haz cónico (CBCT) y clasificarla con base en el sistema de clasificación de Ahmed et al. (2017) para obtener una referencia para diagnóstico clínico y tratamiento. Desde diciembre de 2020 hasta junio de 2021, analizamos los datos de CBCT de 1619 pacientes en el Hospital Estomatológico de Jinan a quienes se les indicó CBCT debido a diversas anomalías orales. Las morfologías de la raíz y del conducto radicular de todos los dientes se analizaron estadísticamente, y la morfología del conducto radicular se clasificó según el sistema de clasificación de Ahmed et al. (2017). En los molares superiores, tres raíces fueron las más comunes, representando el 99,24 % y el 74,61 % de todos los primeros y segundos molares superiores, respectivamente. Dos raíces fueron las segundas más comunes, representando el 0,66 % y el 17,29 % de todos los primeros y segundos molares superiores, respectivamente. La variación de la morfología de la raíz, por ejemplo, fusión o defecto de furcación, estuvo presente en 22 (0,76 %) primeros molares superiores y 765 (25,39 %) segundos molares superiores, siendo la fusión radicular mesiovestibular y distovestibular la más común. Las tasas de detección de un segundo canal mesiovestibular (MB2) en los primeros y segundos molares superiores fueron del 48,5 % y 26,5 %, respectivamente. Entre los grupos de edad, la frecuencia de MB2 fue más alta en el grupo de 15 a 24 años y más baja en el grupo de 55 a 64 años. Los conductos radiculares MB2 bilaterales estaban presentes en el 64,8 % y el 48,4 % de los primeros y segundos molares superiores, respectivamente. En los hombres y en las mujeres representaron el 60,6 % y el 67,8 % de los primeros molares superiores, respectivamente, y el 51,7 % y el 45,6 % de los segundos molares superiores, respec- tivamente. Según la clasificación de la morfología del conducto radicular de Ahmed et al. (2017) se encontraron configuraciones de conducto radicular 18 y 22 en 1453 primeros molares superiores derechos y 1444 primeros molares superiores izquierdos, respectivamente. Los primeros molares superiores derechos mostraron tres tipos de dos raíces, 14 de tres raíces y uno de cuatro raíces. Los primeros molares superiores izquierdos mostraron dos tipos de una raíz, seis de dos raíces y 14 de tres raíces. Según la clasificación de la morfología del conducto radicular de Ahmed et al. (2017) se encontraron configuraciones de conducto radicular 43 y 45 en 1507 segundos molares superiores derechos y 1506 segundos molares superiores izquierdos, respectivamente. Los segundos molares superiores derechos mostraron 17 tipos de una raíz, 16 de dos raíces, ocho de tres raíces y dos de cuatro raíces. Los segundos molares superiores izquierdos mostraron 19 de una raíz, 13 de dos raíces, 12 de tres raíces y uno de cuatro raíces. Este estudio mostró que la morfología del conducto radicular del molar superior es diversa en la provincia de Shandong. El sistema de clasificación de Ahmed y colaboradores proporciona una descripción clara de la morfología del conducto radicular. CBCT se puede utilizar para estudiar morfologías complejas de raíces y conductos radiculares.

COMPARISON BETWEEN SINGLE BUCCAL INFILTRATION VERSUS CONVENTIONAL BUCCAL AND PALATAL INFILTRATION FOR REMOVAL OF MAXILLARY MOLAR TEETH.

Background: Although less painful injection techniques have been developed, most individuals still find palatal injection to be unpleasant. Aims: The purpose of this study was to evaluate the efficacy of single buccal infiltration versus conventional buccal and palatal infiltration for the removal of maxillary molar teeth. Fifty patie Materials and Methods: nts participated in a prospective randomized, split-mouth study, Group 1: 4% Articaine HCL infiltration – Only buccal, Group 2: 2% Lignocaine HCL – Buccal and palatal infiltration. Checking VAS score and Facial pain scale during Infiltration and during extraction. Factor analysis was used to determine the significance of the difference in mean scores between the two groups using both the independent sample t-test. Even though the Results: difference was not statistically significant (P > 0.05), patients in the articaine group reported much less discomfort during having their vital maxillary molars extracted compared to the lignocaine group. As was previously m Conclusion: entioned, it is feasible to avoid the palatal injection while removing molars from the maxilla. Specifically, the extraction of the upper molars, and buccal infiltration with articaine is a viable alternative to the use of traditional local anaesthetic.

C-shaped Canal System in Maxillary Molars Evaluated by Cone- Beam Computed Tomography in an Argentine subpopulation / Conductos en C en molares superiores evaluados mediante tomografía cone-beam en una sub-población Argentina

ABSTRACT The aim of the present study was to evaluate the presence of maxillary first and second molars with a C-shaped canal system in an Argentine subpopulation, and to classify them. Materials and Method: Of the 332 CBCTs initially evaluated, 120 met the selection criteria. Once the presence of a C-shaped canal system had been established, the teeth were classified following Martins et al. Data were expressed as absolute frequencies, percentages with of 95% confidence intervals, according to the score test. Comparisons were analyzed by Chi-square test and Fisher' exact test, with 5% significance level. Results: It was found that 5 out of 120 first molars (4%) and 17 out of 152 second molars (11%) had a C-shaped canal system. Regarding the classification applied, of 5 C-shaped first molars, 2 corresponded to type E2 (40%), 2 corresponded to type C (40%), and 1 corresponded to type B1 (20%). Of 17 C-shaped second molars, 4 resembled a type A (24%), 7 resembled a type B1 (41%), 5 resembled a type B2 (29%), and 1 resembled a type C (6%). UC1 and UC2 configurations were the most common at all levels except apical level. Conclusion: The prevalence of C-shaped canal system pattern in maxillary first and second molars was estimated for the first time in an Argentine subpopulation, in vivo. Knowledge of these data should help clinicians during endodontic treatment.

RESUMEN El objetivo del presente estudio fue evaluar la presencia de conductos en C en primeros y segundos molares superiores, en una subpoblación de Argentina. Materiales y Método: Se observaron 332 CBCTs, de las cuales 120 cumplieron los criterios de selección. Una vez determinada la presencia de conducto en C se clasificaron según Martins et al. Los datos fueron descriptos mediante frecuencias absolutas y porcentajes, con intervalos de confianza al 95% (IC95), según método score. Las comparaciones fueron analizadas mediante la prueba de Chi-cuadrado o exacta de Fisher con un nivel de significación del 5%. Resultados: De 120 primeros molares, 5 presentaron conductos en C, es decir un 4% y de 152 segundos molares, 17 presentaron conductos en C, es decir un 11%. Según la clasificación aplicada, de 5 primeros molares en C, 2 correspondieron al tipo E2 (40%), 2 al tipo C (40%) y 1 al tipo B1 (20%). De 17 segundos molares en C, 4 pertenecieron al tipo A (24%), 7 al tipo B1 (41%), 5 al tipo B2 (29%) y 1 al tipo C (6%). Las clasificaciones UC1 y UC2 fueron las más representativas en todos los niveles, excluyendo el tercio apical. Conclusión: La prevalencia de conductos en C en primeros y segundos molares superiores, fue estimada por primera vez en una subpoblación Argentina, in vivo. Los datos obtenidos en el presente estudio, resultan de interés para el abordaje de los tratamientos endodónticos.

Changes in canine position during maxillary molar distalization with mini-implant and CD appliance: an in vitro study / 口腔疾病防治

Objective@#To investigate changes in the three⁃dimensional position of the maxillary canine during the distal movement of the maxillary first molar by a mini⁃implant combined with a CD appliance.@*Methods@#Ten typodont models of class II malocclusion were selected, and one side was randomly chosen as the experimental group. The CD ap⁃ pliance was bonded to the maxillary canine and first molar of the experimental group, and 1.2 mm stainless steel wire was bent as the anchorage, which was fixed on the model to simulate mini⁃implants implanted in the zygomatic alveolar ridge. Then, 180 g orthodontic force was applied to the canine of the experimental group; the other side was recognized as the control group and was not used for strengthening. Six mini⁃implants were implanted in different parts of the mod⁃ el and used as a reference before and after the experiment. The models were placed in an incubator and heated at 56 ℃ in a water bath for 2 min. The models were scanned before and after thermostatic water bath treatment with a 3⁃shape scanner. Then, the digital models were overlapped through the reference points, and the positions of the canines and first molars were measured before and after the experiment.@*Results@#The sagittal movement distance of the first molar in the experimental group was ( 0.25 ± 0.33) mm, and the vertical movement distance was (0.25 ± 0.28 )mm, which was significantly different from the control group (P < 0.05), while the transverse change was not significantly different (P > 0.05). There was no significant difference in the root position of the first molar in the experimental group (P > 0.05). The lateral and vertical displacement distances of the maxillary canine crown in the experimental group were (4.03 ± 2.11) mm and (1.86 ± 1.01) mm, respectively, which were significantly different from those in the control group (P < 0.001), while the sagittal changes showed no significant differences (P > 0.05). In the experimental group, there was no significant difference in the position of the apex of the maxillary cusp (P > 0.05).@*Conclusion@#Our in vitro study showed that the maxillary canines inclined buccally accompanied by a small amount of intrusion during molar distaliza⁃ tion by a mini⁃implant combined with a CD appliance.

Fused roots of maxillary molars: characterization and prevalence in a Latin American sub-population: a cone beam computed tomography study

OBJECTIVES: The upper molars generally have three roots; therefore, different combinations of fusion can occur, increasing the possibility of finding more complex root canal systems. The purpose of this study was to evaluate the prevalence and characterization of fused roots in first and second maxillary molars using cone-beam computed tomography (CBCT) in a Colombian population. MATERIALS AND METHODS: A total of 1274 teeth were evaluated, of which 534 were maxillary first molars and 740 were maxillary second molars. Axial sections were made at the cervical, middle, and apical levels to determine the prevalence of root fusion and the types of fusion. RESULTS: Overall, 43% of the molars (n = 551) presented some type of fused root. Root fusion was present in 23.4% of the maxillary first molars. The most frequent type of fused root was type 3 (distobuccal-palatal; DB-P) (58.9%). Root fusion was observed in 57.6% of the maxillary second molars, and the most prevalent type of fused root was type 6 (cone-shaped) (45.2%). Of the maxillary molars, 12.5% were classified as C-shaped. CONCLUSION: Within the limitations of this study, there was a high prevalence of fused roots in maxillary molars in the Colombian population, mainly in the maxillary second molars. In first molars, the most common type of fused root was type 3 (DB-P) and in second molars, the most common type was type 6 (cone-shaped). Additionally, molars with root fusion presented variation at different levels of the radicular portion, with implications for treatment quality.

Immediate implantation following tooth extraction in fresh maxillary molar socket with poor bone quality / 南方医科大学学报

OBJECTIVE@#To explore the feasibility of immediate implantation after tooth extraction in the maxillary molar socket with poor bone quality beneath the sinus.@*METHODS@#We collected the data from the patients undergoing extraction of maxillary molars with poor bone quality between the sockets and sinuses. Sinus lifting and immediate implant following the extraction were performed simultaneously in these cases, and the primary stability of the implants, wound healing, and changes of the sinus were observed. At 6 months after the operations, the crowns were installed on the implants. The masticatory function was observed, and the growth of the alveolar bones and their changes after the operations were examined using microcomputed tomography (MCT).@*RESULTS@#We analyzed 32 extraction cases with immediate implantation in the maxillary molar sockets with poor bone quality beneath the sinus. The average age of the patients was 59.8 years, and the length and diameter of the implant ranged from 8.5 to 10 mm and from 4.5 to 5.5 mm, respectively. The torque force of the implants varied from the minimum (in which cases the implants remained fixed after insertion with fingers) to the maximum of 30 N·cm. The postoperative recovery was uneventful in all the cases and no failed or movable implants were found. At 6 months after the operation, none of the patients showed abnormalities in the sinus, and in all the cases the crowns were successfully installed on the implants with good recovery of the masticatory functions. Follow-up of the patients for 12 to 96 months after the operation showed successful immediate implantation in all the cases. After the operation, the changes of the mean alveolar ridge heights on the buccal, palatal, mesial, and distal sides of the patients were 0.8069±0.6253 mm (=1.2904, >0.1), 0.5272± 0.3331 mm (=1.5836, >0.05), 0.5416±0.4048 mm (=1.3379, >0.05), and 0.5172±0.3874 mm (=1.3351, >0.05), respectively; the change of the alveolar ridge width was 0.5522±0.4381 mm (=1.2604, >0.1) mm. The dimension of the alveolar bone underwent no significant changes after the operation in these patients.@*CONCLUSIONS@#Immediate implantation in the maxillary extraction socket with a poor bone quality can avoid damages to the sinus and achieve good outcomes with such advantages of less trauma, full use of the innate gingiva and alveolar ridge, and well preserved morphology of the alveolar ridge as compared with delayed implantation.

Morphology of Maxillary First Molars Analyzed by Cone-Beam Computed Tomography among Malaysian: Variations in the Number of Roots and Canals and the Incidence of Fusion

Introduction: A few studies investigated the numerous potential endodontic uses of CBCT, including the examination of root canal morphology and presumed that CBCT was effective for the initial identification of such morphology; moreover CBCT is a reliable method for the detection of the MB2 canal when compared with the gold standard of physical sectioning of the specimen. The aim of this study was to identify the root and canal morphology of the maxillary first molars among Malaysians analysed by cone-beam computed tomography (CBCT) images. Materials and Methods: Maxillary first (n = 421) molars from Malaysian patients (n = 241) of Malay, Chinese and Indians inceptions were examined by two Endodontists using in vivo CBCT methods. The number and configuration of roots, the number of root canals, and the canal configuration according to Vertucci’s classification were determined. Results: Single roots were not found in maxillary first molars. The incidence of fused roots was 1.995% in the first molars between mesiobuccal and distobuccal roots. In (421) 3-rooted maxillary first molars, additional canals were found in 45.6% of the mesiobuccal (MB) roots and 0% of the distobuccal (DB) roots. Bilateral symmetry of the MB roots was found in 82.36% of the first molar. Only one tooth was found to have pulp stone inside the pulp chamber. Conclusions: The root and canal configuration of a Malaysian population showed different features from those of other populations. CBCT scans can enhance the understanding of root canal anatomy, with the potential of improving the outcome of endodontic treatment.

Maxillary first molar with 7 root canals diagnosed using cone-beam computed tomography

Root canal anatomy is complex, and the recognition of anatomic variations could be a challenge for clinicians. This case report describes the importance of cone beam computed tomographyic (CBCT) imaging during endodontic treatment. A 23 year old woman was referred by her general dental practitioner with the chief complaint of spontaneous pain in her right posterior maxilla. From the clinical and radiographic findings, a diagnosis of symptomatic irreversible pulpitis was made and endodontic treatment was suggested to the patient. The patient underwent CBCT examination, and CBCT scan slices revealed seven canals: three mesiobuccal (MB1, MB2, and MB3), two distobuccal (DB1 and DB2), and two palatal (P1 and P2). Canals were successfully treated with reciprocating files and filled using single-cone filling technique. Precise knowledge of root canal morphology and its variation is important during root canal treatment. CBCT examination is an excellent tool for identifying and managing these complex root canal systems.

Analysis of C-shaped root canal configuration in maxillary molars in a Korean population using cone-beam computed tomography

OBJECTIVES: The purpose of this study was to investigate the incidence of root fusion and C-shaped root canals in maxillary molars, and to classify the types of C-shaped canal by analyzing cone-beam computed tomography (CBCT) in a Korean population. MATERIALS AND METHODS: Digitized CBCT images from 911 subjects were obtained in Chosun University Dental Hospital between February 2010 and July 2012 for orthodontic treatment. Among them, a total of selected 3,553 data of maxillary molars were analyzed retrospectively. Tomography sections in the axial, coronal, and sagittal planes were displayed by PiViewstar and Rapidia MPR software (Infinitt Co.). The incidence and types of root fusion and C-shaped root canals were evaluated and the incidence between the first and the second molar was compared using Chi-square test. RESULTS: Root fusion was present in 3.2% of the first molars and 19.5% of the second molars, and fusion of mesiobuccal and palatal root was dominant. C-shaped root canals were present in 0.8% of the first molars and 2.7% of the second molars. The frequency of root fusion and C-shaped canal was significantly higher in the second molar than the first molar (p < 0.001). CONCLUSIONS: In a Korean population, maxillary molars showed total 11.3% of root fusion and 1.8% of C-shaped root canals. Furthermore, root fusion and C-shaped root canals were seen more frequently in the maxillary second molars.

Analysis of C-shaped root canal configuration in maxillary molars in a Korean population using cone-beam computed tomography

OBJECTIVES: The purpose of this study was to investigate the incidence of root fusion and C-shaped root canals in maxillary molars, and to classify the types of C-shaped canal by analyzing cone-beam computed tomography (CBCT) in a Korean population. MATERIALS AND METHODS: Digitized CBCT images from 911 subjects were obtained in Chosun University Dental Hospital between February 2010 and July 2012 for orthodontic treatment. Among them, a total of selected 3,553 data of maxillary molars were analyzed retrospectively. Tomography sections in the axial, coronal, and sagittal planes were displayed by PiViewstar and Rapidia MPR software (Infinitt Co.). The incidence and types of root fusion and C-shaped root canals were evaluated and the incidence between the first and the second molar was compared using Chi-square test. RESULTS: Root fusion was present in 3.2% of the first molars and 19.5% of the second molars, and fusion of mesiobuccal and palatal root was dominant. C-shaped root canals were present in 0.8% of the first molars and 2.7% of the second molars. The frequency of root fusion and C-shaped canal was significantly higher in the second molar than the first molar (p < 0.001). CONCLUSIONS: In a Korean population, maxillary molars showed total 11.3% of root fusion and 1.8% of C-shaped root canals. Furthermore, root fusion and C-shaped root canals were seen more frequently in the maxillary second molars.

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.

Micro-CT Evaluation of Root Filling Removal after Three Stages of Retreatment Procedure

The aim of this study was to quantify the residual filling material after filling removal, re-preparation with rotary or reciprocating files and passive ultrasonic irrigation (PUI). Twenty maxillary molars were prepared using ProTaper instruments up to F1. The teeth were filled with AH Plus and ProTaper gutta-percha points using the single-cone technique. Thereafter, the specimens were scanned using a micro-computed tomography system (Micro-CT #1). Then, the root canal filling was removed using ProTaper Retreatment files, and a new scan was performed (Micro-CT #2). The specimens were divided into two groups according to the instrument used for re-preparation: ProTaper rotary or WaveOne reciprocating files (Micro-CT #3). Finally, PUI was performed, and a new micro-CT scan was performed (Micro-CT #4). Intragroup and intergroup analyses were performed using Friedman and Dunn's post hoc test and the Kruskal-Wallis and Dunn post hoc tests, respectively. Palatal canal presented the highest volume of residual filling material in all stages of endodontic retreatment (p<0.05). The main reduction of filling volume was achieved after using ProTaper Retreament (p<0.05). The amount of remaining filling material after using ProTaper Retreatment was similar to that achieved with rotary and reciprocating files and after PUI (p>0.05). Rotary and reciprocating files achieved similar removal of the root canal filling (p>0.05). The greatest reduction in filling material was achieved after using ProTaper Retreatment files. Rotary and reciprocating instruments and PUI did not improve the removal of root canal filling materials.

Resumo O objetivo dente estudo foi quantificar o material obturador residual após remoção da obturação, repreparo do canal com instrumentos de rotação contínua e reciprocantes e após irrigação ultrassônica passiva (IUP). Vinte molares superiores foram preparados usando instrumentos ProTaper sequencialmente até F1. Os dentes foram obturados com AH Plus e cones de guta percha ProTaper utilizando a técnica de cone único. Em seguida, os espécimes foram submetidos à microtomografia computadorizada (Micro-CT #1). Então, o material obturador foi removido utilizando instrumentos ProTaper Retratamento e novo escaneamento foi realizado (Micro-CT #2). Os espécimes foram divididos em dois grupos de acordo com o instrumento usado para o repreparo: de rotação contínua (ProTaper) ou reciprocante (WaveOne) (Micro-CT #3). Finalmente, IUP foi realizada e nova micro-CT foi conduzida (Micro-CT #4). As análises intra-grupo e inter-grupos foram realizadas utilizando os testes de Friedman e de Dunn e o teste de Kruskal-Wallis e Dunn, respectivamente. O canal palatino apresentou o maior volume de material obturador remanescente em todos os estágios do tratamento endodôntico (p<0,05). A maior redução do volume da obturação foi obtida após usar os instrumentos ProTaper Retratamento (p<0,05). A quantidade de material obturador remanescente após utilizar instrumentos ProTaper Retratamento foi similar àquela obtida após repreparo com instrumentos de rotação contínua e reciprocantes e após a IUP (p>0,05). Instrumentos de rotação contínua e reciprocantes proporcionaram similar remoção de material obturador (p>0,05). A maior redução do volume de material obturador foi obtida após utilizar os instrumentos ProTaper Retratamento. Instrumentos de rotação contínua e reciprocantes, assim como a IUP, não reduzíram o volume de material obturador remanescente.

Dentoalveolar and skeletal changes consequent to maxillary molar distalization with the modified pendulum appliance in classII malocclusion / 安徽医科大学学报

21 classII malocclusion adolescents (9 boys and 12 girls) were selected as the subjects, aged from 10.6 to 14.5 years, and the initial mean age was 12.8 years. All were treated with the modified Pendulum appli-ance. The duration for distalization of maxillary molars was from 3.2 to 5.7 months (4.3 months on average). Lat-eral cephalograms were obtained before and after distalization. Changes produced by the modified Pendulum appli-ance were analyzed with paired t tests. The mean space opening on lateral cephalograms was 7.31 mm, and maxil-lary first molar distalization accounted for 64.8% of the space,with a mean distal crown tipping of 18.64o. The rate of molar movement was 1.27 mm per month. The maxillary first molars intruded 0.69 mm,and the premolars extru-ded 1.02 mm. Lower anterior facial height increased 2.19 mm. The maxillary incisors had increased 3.39oof labial tipping and 1.13 mm of protrusion.

A study of the anatomical variations in the position of the greater palatine foramen in adult human skulls and its clinical significance / Variaciones anatómicas en la posición del foramen palatino mayor en cráneos humanos adultos y su significación clínica

Pain is a common distressing symptom in dental practice. Depending upon the cases, different techniques are used to relieve pain. One of these is peripheral trigeminal nerve block. Peripheral trigeminal nerve block anaesthesia has proved to be an effective and convenient way to anaesthetise large regions of oral and maxillofacial complex. This block can be intraoral or extra oral. The intraoral route is through the greater palatine foramen in which the dental surgeons enter into the pterygopalatine fossa, where the maxillary nerve is situated. The morphological variations in the position of greater palatine foramen may be of clinical importance in the administration of local anaesthesia and in palatal surgery. In the present study, the distance of greater palatine foramen from the median palatine suture, and from the posterior border of hard palate have been noted, and the position of greater palatine foramen relative to the maxillary molars, as well as the direction of the foramen have been examined.

El dolor es un síntoma común y preocupante en la práctica dental. Dependiendo de los casos, diferentes técnicas se utilizan para aliviar el dolor. Una de ellas es el bloqueo periférico del nervio trigémino. Esta, ha demostrado ser una forma eficaz y conveniente para anestesiar grandes regiones del complejo oral y maxilofacial. Este bloqueo puede ser intraoral o extraoral. La vía intraoral es a través del foramen palatino mayor en la cual se ingresa en la fosa pterigopalatina, donde se encuentra el nervio maxilar. Las variaciones morfológicas en la posición del foramen palatino mayor puede ser de importancia clínica en la administración de anestesia local y en la cirugía del paladar. En el presente estudio, se examinó la distancia del foramen palatino mayor desde la sutura palatina mediana y el margen posterior del paladar duro, y su posición relativa a los molares superiores, así como la dirección del foramen palatino mayor.

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.