CBCT analysis of the relative position between maxillary central incisors and alveolar bone in Southern Chinese adults / 口腔疾病防治

Objective@#Exploring the position and bone wall thickness characteristics of the maxillary central incisors in Southern Chinese adults to provide a clinical reference for the design of immediate maxillary central incisor implantation surgery.@*Methods@#The hospital ethics committee approved the study, and the patients provided informed consent. CBCT images of 990 adult patients (aged 20-79 years) from the Stomatology Hospital (January 2018 to December 2021) were categorized based on the dental arch form and age-sex groups. Sagittal CBCT images of the maxillary central incisors were used to measure the labial and palatal bone thickness wall at 4 mm the CEJ to apical, the middle of the root, and the angle between the tooth long axis and the long axis of the alveolar process, to compare the thickness of the labial and palatal bone walls in samples of male and female patients, and to explore the relationship between the angle between the tooth long axis and the alveolar process long axis in samples of male and female patients in different age groups (20-39 years; 40-59 years; 60-79 years).@*Results@#Significant differences were found in the labiopalatine side of the alveolar bone of the maxillary incisor root position. A total of 95.8% (948/990) of the maxillary incisors were positioned more buccally, 4.1% (41/990) were positioned more midway, and 0.1% (1/990) were positioned more palatally. The thicknesses of the bone wall at the CEJ of 4 mm below the palatal side, the middle of the root, and at the apex were greater (1.82 ± 0.56 mm, 3.20 ± 1.10 mm, and 7.70 ± 2.00 mm, respectively) than those at the labial side (1.21 ± 0.32 mm, 0.89 ± 0.35 mm, and 1.86 ± 0.82 mm, respectively), with statistical significance (P<0.05). Male bone wall thickness was generally greater than female bone wall thickness (P<0.05). The angle between the long axis of male teeth and the alveolar bone was 14.77° ± 5.66°, while that of female teeth was 12.80° ± 5.70°, with a statistically significant difference (P<0.05). The angle between the long axis of teeth and the alveolar bone in the 40-59-year-old group and the 60-79-year-old group was greater than that in the 20-39-year-old group, and the difference was statistically significant (P<0.05).@*Conclusion@#A total of 95.8% of adults in South China have maxillary central incisors with root deviation toward the labial bone cortex. The thickness of the labial bone wall is much thinner than that of the labial bone wall, which is the middle of the thickness of the root. In Southern Chinese adults, the angle between the upper central incisor and the long axis of the alveolar bone in males is greater than that in females, and the degree of the angle increases with age. It is recommended to pay attention to the thickness of the bone wall around the root and the angle between the teeth before immediate implantation surgery to choose a reasonable implantation plan.

An atypical presentation of talon cusp: Double talon cusps

Talon cusp is an uncommon developmental anomaly resulting in an extra cusp or cuspal projection on an anterior tooth consisting of normal enamel, dentin, and varying degrees of pulp tissue. Talon cusp shows varied presentations of which the palatal talon cusp has been the most common of all. The management requires an extensive understanding of this clinical entity and the complications associated with its occurrence. In this case series, we are reporting double talon cusps which is a rarity itself, involving the palatal aspect of maxillary central incisors

Effects of Implant Sites and Axial Direction on Stress of Maxillary Central Incisors with Immediate Implantation under Immediate Weight-Bearing: A Three-Dimensional Finite Element Analysis / 医用生物力学

Objective To investigate the influence of implant location and axial direction on stress distributions at the implant bone interface of maxillary central incisors with different alveolar fossa morphology by immediate implantation under immediate weight-bearing. Methods With reference to dental cone beam computed tomography (CBCT) image data from a healthy adult, the three-dimensional ( 3D) finite element models of maxillary central incisors with three types of alveolar fossa ( buccal, mediate, and palatal type) by immediate implatation under immediate weight-bearing were established. Different implant sites ( apical site, palatal / labial site) and axial directions (long axis of the tooth, long axis of the alveolar bone) were simulated. The established models were subjected to 100 N force at different angles (0°, 30°, 45°, 60°, 90°). The stresses in the alveolar bone around the implant were analyzed by the ANSYS software. Results Twelve 3D finite element models of maxillary central incisors with different alveolar fossa morphology by immediate implantation under immediate weight-bearing were successfully established. When alveolar fossa with buccal and mediate shape was applied with immediate implantation under immediate weight-bearing, it was easier to obtain good biomechanical properties of the implant-bone interface when implants were placed at palatal site along long axis of the alveolar bone. When alveolar fossa with palatal shape was applied with immediate implantation under immediate weight bearing, the equivalent stresses on peri-implant alveolar bone were much smaller than those on apical site, regardless of whether the implant was placed along long axis of the tooth or the long axis of the alveolar bone. Conclusions Different alveolar fossa morphology, implant location and axial direction will affect characteristics of implant-bone interface of maxillary central incisors with immediate implantation under immediateweight-bearing. In clinical practice, surgical planning on different axial direction and location of implantation should be developed for alveolar fossa with different morphology.

Three-dimensional finite element analysis of the influence of implant site and axial direction on the immediate weight bearing stress of central incisors in different alveolar fossa shapes / 口腔医学

Objective@#To analyze and investigate the effects of implant location and axial direction on the stress distribution of implants, abutments, central screws, and crowns during immediate loading of maxillary mesial incisors with different alveolar fossa morphology based on three-dimensional finite element method.@*Methods@#Referring to the oral CBCT images of a healthy adult, a three-dimensional finite element model was established for immediate implant loading of maxillary central incisors with three alveolar fossa morphs: labial, intermediate, and palatal; different implant sites(apical site, palatal/labial site) and axes(tooth long axis, alveolar bone long axis) were simulated; the established model was loaded with a force of 100 N. ANSYS software was applied to analyze the stress values of the implants, abutments, central screwss, and crownss. @*Results@#The 3D finite element models of 12 maxillary central incisors with different alveolar sockets were successfully established;the implants and their superstructures were least stressed when the maxillary central incisors with partial labial and partial palatal shape were placed along the long axis of the alveolar bone in the palatal/labial position for immediate implant loading;the implants and their superstructures were least stressed when the maxillary central incisors with central shape were placed along the long axis of the tooth in the palatal position for immediate implant loading. The implant and its superstructure were subjected to the least stress when the implant was placed along the long axis of the tooth in the immediate loading position. @*Conclusion@#The bio-mechanical characteristics of the implant and its superstructure are influenced by the different socket morphology, implantation sites and axes. Therefore, in clinical practice, different implantation axes and implantation sites should be developed for different socket morphs.

Síndrome del incisivo central maxilar único: reporte de caso

El síndrome del incisivo central maxilar único es una rara alteración en el desarrollo y formación de órganos ubicados principalmente en la línea media; el cual ocurre de manera temprana entre los días 35 al 38 de vida intrauterina. Su etiología es desconocida, aunque se ha asociado a deleciones de los cromosomas 7 (7q.36.1) y 8, y a mutaciones en el gen Sonic Hedgehog. Presenta una prevalencia de 1/50.000 nacidos vivos y aunque es una anomalía poco frecuente del desarrollo craneofacial, su diagnóstico y tratamiento temprano son importantes para los odontólogos generales o especialistas ya que puede ser un signo de otras anomalías congénitas o del desarrollo graves. Por lo tanto, el objetivo de este caso es reportar la fase inicial de tratamiento en un niño con el síndrome de incisivo central maxilar único quien no había sido diagnosticado anteriormente con este síndrome. Caso Clínico: Paciente masculino de 10 años de edad, procedente de Jamundí, Valle del Cauca- Colombia. Reporta ausencia de órgano dentario superior. En el examen intraoral se observa un incisivo central único sobre la línea media del maxilar, ausencia de frenillo labial y papila incisiva, paladar oval y retrognatismo mandibular. Fue tratado en una primera fase con ortopedia funcional maxilar para mejorar la clase II y está a la espera de iniciar la segunda fase de tratamiento con ortodoncia. Conclusiones: El síndrome de incisivo central maxilar único es un síndrome poco frecuente el cual conlleva múltiples afecciones que interfieren en el normal desarrollo y crecimiento de estructuras anatómicas.

A síndrome do incisivo central superior único é uma alteração rara no desenvolvimento e formação de órgãos localizados principalmente na linha média; que ocorre precocemente entre os dias 35 a 38 de vida intrauterina. Sua etiologia é desconhecida, embora tenha sido associada a deleções dos cromossomos 7 (7q.36.1) e 8, e mutações no gene Sonic Hedgehog. Tem uma prevalência de 1/50.000 nascidos vivos e, embora seja uma anomalia rara do desenvolvimento craniofacial, seu diagnóstico e tratamento precoces são importantes para dentistas gerais ou especialistas, pois pode ser sinal de outras anomalias congênitas ou de desenvolvimento graves. Portanto, o objetivo deste caso é relatar a fase inicial do tratamento em uma criança com síndrome do incisivo central superior único que não havia sido previamente diagnosticada com essa síndrome. Caso clínico: Paciente do sexo masculino, 10 anos, procedente de Jamundí, Valle del Cauca- Colômbia. Relata ausência de órgão dentário superior. O exame intraoral mostra um único incisivo central na linha média maxilar, ausência de frênulo labial e papila incisiva, palato oval e retrognatismo mandibular. Foi tratado numa primeira fase com ortopedia funcional maxilar para melhorar a classe II e aguarda para iniciar a segunda fase do tratamento ortodôntico. Conclusões: A síndrome do incisivo central superior único é uma síndrome rara que envolve múltiplas condições que interferem no desenvolvimento e crescimento normal das estruturas anatômicas.

Solitary maxillary central incisor syndrome is a rare alteration in the development and formation of organs located mainly in the midline; which occurs early between days 35 to 38 of intrauterine life. Its etiology is unknown, although it has been associated with deletions of chromosomes 7 (7q.36.1) and 8, and mutations in the Sonic Hedgehog gene. It has a prevalence of 1/50,000 live births and although it is a rare anomaly of craniofacial development, its early diagnosis and treatment are important for general dentists or specialists since it can be a sign of other serious congenital or developmental anomalies. Therefore, the objective of this case is to report the initial phase of treatment in a child with solitary maxillary central incisor syndrome who had not been previously diagnosed with this syndrome. Clinical case: Male patient, 10 years old, from Jamundí, Valle del Cauca- Colombia. Reports absence of upper dental organ. Intraoral examination shows a solitary central incisor on the maxillary midline, absence of labial frenulum and incisive papilla, oval palate and mandibular retrognathism. He was treated in a first phase with maxillary functional orthopedics to improve class II and is waiting to start the second phase of orthodontic treatment. Conclusions: Solitary maxillary central incisor syndrome is a rare syndrome which involves multiple conditions that interfere with the normal development and growth of anatomical structures.

Comparison of Maxillary Central Incisor Labial Crown-Root Angle with Collum Angle in Class I and Class II Division 2 Malocclusion.

To anticipate difficulties with intrusion, extrusion, or torqueing mechanics in certain malocclusions, a thorough understanding of crown-root relationships in the bucco-lingual plane is warranted. This study aimed at examining the collum angle of the maxillary central incisor in Angle’s class I and class II division 2 malocclusion and compare these values with the Labial Crown Root Angle (LCRA). MethodsThis study was conducted on two groups i.e., group 1 comprising of 26 Angle’s Class 1 subjects and group 2 comprising of 26 Class II div 2 subjects. Cephalometric measurements of collum angle and LCRA of maxillary central incisors were recorded for each subject and were compared between the two groups. ResultsThe mean Labial Crown-Root Angle was 28.35 ± 4.01 and 38.51 ± 5.80 for class I and class II division malocclusions respectively. Compared to the LCRA of Angle’s class I malocclusion, the mean LCRA of Angle’s class II division 2 was found to be greater, and is statistically significant. There was no significant gender variation. The mean difference between class I and class II div 2 malocclusion was found to be 9.42 ± 2.23 for collum angle and 10.16 ± 1.79 in LCRA respectively. ConclusionsThe Labial Crown Root Angle and collum angle of Angle’s Class II div 2 malocclusion were greater than the corresponding values in Angle’s Class I malocclusion. Also, the LCRA is a more simplified method for measuring the crown root angle and can be used as an adjunct to collum angle.

Incisivo central único de la línea media del maxilar, holoprosencefalia y estenosis congènita del orificio nasal anterior en un recién nacido prematuro: a propósito de un caso / Solitary median maxillary central incisor, holoprosencephaly and congenital nasal pyriform aperture stenosis in a premature infant: case report

El síndrome del incisivo central único de la línea media del maxilar es un trastorno raro que implica anomalías de la línea media, como holoprosencefalia, anomalías de las fosas nasales, fisura palatina, labio leporino, hipotelorismo, microcefalia y panhipopituitarismo. La estenosis congénita del orificio nasal anterior es una causa mortal de dificultad respiratoria neonatal debido al estrechamiento del orificio nasal anterior, y podría confundirse con la atresia de coanas. En este informe, presentamos el caso de un recién nacido con síndrome del incisivo central único de la línea media del maxilar acompañado de otras anomalías, tales como holoprosencefalia, estenosis del orificio nasal anterior, microcefalia y panhipopituitarismo. El cariotipado mostró una deleción heterocigota en el gen SIX3 en la región 2p21, que produjo una forma más grave de holoprosencefalia.

Solitary median maxillary central incisor syndrome is a rare disorder involving midline abnormalities such as holoprosencephaly, nasal cavity anomalies, cleft palate-lip, hypotelorism, microcephaly, and panhypopituitarism. Congenital nasal pyriform aperture stenosis is a lethal cause of neonatal respiratory distress due to narrowing of the pyriform aperture anteriorly and it can be confused with choanal atresia. In this report, we present a newborn infant with solitary median maxillary central incisor syndrome accompanied by other abnormalities including holoprosencephaly, nasal pyriform aperture stenosis, microcephaly and panhypopituitarism. Chromosomal analysis showed heterozygous SIX3 gene deletion at 2p21 region resulting in a more severe form of holoprosencephaly.

The Effect of Apical Resection on Biomechanical Properties of Maxillary Central Incisor by Three- / 医用生物力学

Objective To study the tooth and periodontal stress distribution and tooth displacement after apical root resection, so as to provide data support for clinicians to perform apical root surgery and improve the cure rate of apical root surgery. Methods Three-dimensional (3D) finite element model of normal maxillary central incisor with its periodontal tissues was established based on Micro CT image data. Then periapical periodontitis and apical root resection surgery were simulated. The model of periapical periodontitis and maxillary central incisor with different apical root resection length (3, 4, 5, 6, 7, 8 mm) and their supporting tissues were established. With the occlusal force applied, the biomechanical behavior of postoperative healing teeth was studied by 3D finite element analysis. The optimal apical resection length was obtained by comparing biomechanical effects of surgical restoration. Results The completely healed model reduced the stress (by 26.8%) and displacement (by 7.3%) compared with the apical periodontitis model. With the increase of apical root resection length, the stress of the teeth neck and periodontal ligament increased by 11.14% and 29.27%, respectively, when the root resection was 8 mm. The stress of the alveolar bone increased by 83.11%. The stress of new apical root at the section increased on the whole compared with the same part of normal tooth. The displacement of the tooth along the long axis also increased. The displacement significantly increased by 18.39% when the resection length was over 5 mm. Conclusions Apical root resection significantly improves the biomechanical properties of refractory apical periodontitis tooth. The recommended resection length was 3-5 mm and the crown-to-root ratio (CRR) should be larger than 0.84.

Factors and Treatments Influencing the Unilaterally Unerupted Maxillary Central Incisor / 대한소아치과학회지

The purpose of this study was to investigate the cause of eruption disturbance in the maxillary central incisor and establish the effective treatment plan by analyzing the vertical distance, angulation of long axis and root development of the tooth with eruption disturbance using the cone-beam CT.The average age of 134 patients diagnosed with unilaterally impacted maxillary central incisor was 7.9 years old and the male was 2.1 times higher than the female. The most common cause of eruption disorder was physical obstruction, especially mesiodens and odontoma. Of the teeth with unilateral eruption disorder, 78 cases erupted spontaneously and 56 cases erupted non-spontaneously after removal of physical obstruction.The possibility of spontaneous or non-spontaneous eruption in the unilaterally impacted maxillary central incisor depended on several factors, such as vertical distance, angulation of long axis and root development of unerupted tooth. The spontaneous eruption of the impacted maxillary cental incisor was most frequent at the angulation of long axis of 50 to 90 degrees, which is similar to the angulation of long axis of the normally erupted maxillary central incisor. In addition, the spontaneous eruption period of impacted maxillary central incisor was more influenced by the vertical distance than the angulation of long axis and the root development. Most of the teeth that showed non-spontaneous eruption had orthodontic traction, and these teeth were usually erupted within about 12 months. The period treated with orthodontic traction was no statistical significance with the vertical distance, the angulation of long axis, and the root development.This study will provide information on the cause of unilaterally impacted maxillary cental incisor and help to establish the future treatment plan.

Analysis of the width ratio and wear rate of maxillary anterior teeth in the Korean population

PURPOSE: The purpose of this study was to compare the width ratio of maxillary anterior teeth according to age in the Korean population and to evaluate the maxillary central incisor width-to-length (W/L) ratio, given differences in age and gender. MATERIALS AND METHODS: Ninety-three Korean adults were divided into 3 groups (n = 31) by age. Group I was 20 - 39 years old, Group II was 40 - 59 years old, and Group III was over 60 years of age. After taking an impression and a cast model of the maxillary arch, the anterior teeth width ratio and central incisor W/L ratio were calculated from standard digital images of the cast models using a graph paper with a digital single lens reflex (DSLR) camera. The calculated ratios were compared among all groups and central incisor W/L ratio were analyzed according to age and gender. All comparative data were statistically analyzed with one-sample t-tests, one-way ANOVAs with Tukey tests, and independent t-tests. RESULTS: No significant differences in maxillary anterior teeth ratios were found among the age groups. The maxillary central incisor W/L ratios in Group III were the greatest and were significantly higher than those in the other groups. The central incisor W/L ratio of men was higher than that of women in Group II. CONCLUSION: Maxillary anterior teeth width ratios were similar in all age groups in the Korean population. The maxillary central incisor was observed as worn teeth in the group over 60 years of age, and a significant difference between genders was found in 40 to 50 year olds.

Retreatment of failed regenerative endodontic of orthodontically treated immature permanent maxillary central incisor: a case report

A revascularization procedure was shown to be the best alternative therapy for immature teeth with necrotic pulp and apical infection. A 12 year old female with a history of trauma to her upper central incisor and a sinus tract was referred for endodontic treatment. She was an active orthodontic patient and had undergone regenerative endodontic treatment for the past 2 years. Clinical examination revealed no response to sensibility, percussion, and palpation tests. The preoperative radiograph showed an open apex and apical rarefaction. The case was diagnosed as previously treated tooth with asymptomatic apical periodontitis. Regenerative endodontic retreatment was performed, and the case was followed for 3 years. Clinical, radiographic, and cone-beam computed tomography follow-up examination revealed an asymptomatic tooth, with evidence of periapical healing and root maturation.

Sexual dimorphism in permanent maxillary central incisor in Kosovo: Albanian population / Dimorfismo sexual en los incisivos centrales superiores permanentes en una población albanesa de Kosovo

The aim of this study was to investigate the sexual dimorphism in permanent maxillary central incisor in Kosovo Albanian population using crown linear diameters, crown module (CM) and crown index (CI). The study sample consisted of 204 dental students, selected from the Dental School, Faculty of Medicine at University of Prishtina, Republic of Kosovo. The measurements of mesiodistal (MD) and buccolingual (BL) crown diameters of left and right permanent maxillary incisor (MCI) were taken in a dental casts using electronic digital caliper Boss, Hamburg ­ Germany, with accuracy± 0.01 mm. The descriptive statistics, t-test and percentage of sexual dimorphism in crown linear diameters and dental indexes of maxillary central incisor were calculated. The results showed a statistically significant difference in MD (p<0.01) and BL diameters (p<0.0001) of maxillary central incisor between males and females. BL diameter of maxillary central incisor showed greater sexual dimorphism (4.78 %) than mesiodistal diameter (2.76 %). CM presented with a higher level of sexual dimorphism (3.76 %) comparing to CI (1.89 %). The findings of this study demonstrated sexual dental dimorphism in crown linear diameters and dental indexes in maxillary central incisor in Kosovo-Albanian population.

El objetivo de este estudio fue investigar el dimorfismo sexual en el diente incisivo central superior permanente en una población albanesa de Kosovo utilizando diámetros lineales de las copas, módulo de corona (MC) y el índice de la corona (IC). La muestra del estudio consistió en 204 estudiantes de odontología, seleccionados de la Escuela de Odontología, Facultad de Medicina de la Universidad de Pristina, República de Kosovo. Se tomaron mediciones mesiodistales (MD) y diámetros bucolinguales (BL) de la corona de los dientes incisivos superiores permanentes izquierdo y derecho, en modelos dentales, utilizando un calibrador digital electrónico Boss (Hamburgo ­ Alemania) con una precisión de ± 0,01 mm. Se calculó la estadística descriptiva, t-test y porcentaje de dimorfismo sexual en los diámetros lineales de coronas dentales y los índices del diente incisivo central superior. Los resultados mostraron una diferencia estadísticamente significativa en MD (p <0,01) y diámetros BL (p <0,0001) del diente incisivo central superior entre hombres y mujeres. Se observó un mayor dimorfismo sexual (4,78 %) en el diámetro BL del diente incisivo central superior, que en el diámetro mesiodistal (2,76 %). El MC presentó un nivel mayor de dimorfismo sexual (3,76 %) en comparación con IC (1,89 %). Los resultados de este estudio demostraron la existencia de dimorfismo sexual en los diámetros lineales de la corona dental y de los índices dentales correspondientes al diente incisivo central superior en la población albanesa de Kosovo.

A case series of unusual root canal morphology

Aim: The thorough knowledge of tooth morphology and its variations is essential for successful endodontic treatment. Case report: This article reports an unusual root canal configuration that was detected in a maxillary central incisor with two root canals , mandibular canine with two canals and mandibular canine with two roots and root canals. Conclusions: These case reports increase the awareness of clinicians on variations in the root canal anatomy so that complete disinfection and obturation of the root canal system is possible.

The malformed lingual groove of left maxillary central incisor with two root canals:A case report / 实用口腔医学杂志

Dens invaganatus is a type of abnormal morphological differentiation because of the involution in crown surface before tooth calci-fication,it is mostly found in maxillary lateral incisor teeth and rare in incisor.A case of a malformed lingual groove of left maxillary central incisor with 2 root canals is reported in the paper.

Relaciones de forma y proporción del incisivo central maxilar con medidas faciales, línea mediana dentaria y facial en adultos / Relationships between shape and proportion of the maxillary central incisor with facial measurements, dental and facial midline in adults

El propósito de este estudio fue relacionar la forma y proporción del incisivo central maxilar (ICM) derecho con la forma facial y ubicación de las líneas medianas dentarias y facial. Se realizó un estudio de corte transversal sobre una muestra por conveniencia constituida por 118 pacientes de ambos sexos, con una edad promedio de 25,09±7,71 años, escogidos según criterios de inclusión. En cada caso, fueron medidos el largo y ancho del ICM derecho, proporción dentaria resultante entre estas medidas, líneas medianas dentarias en relación a la línea mediana facial. Estas medidas se correlacionaron con las medidas faciales para forma y clase facial. Los resultados revelaron que la forma dentaria más frecuente encontrada fue la ovoide; las medidas promedio de largo y ancho para el ICM fueron de 10,28±0,91 mm y 8,69±0,57 mm, respectivamente. En mujeres fue 9,98 mm y 8,55 mm, y en hombres de 10,62 mm y 8,86 mm. La proporción dentaria fue de un 85%. Se encontraron coincidencias de las líneas medianas dentarias maxilar, mandibular y facial sólo en un 18% de los casos, y los tipos de contornos gingivales más frecuentes fueron de tipo estético (97%). No hubo relación entre medidas dentarias y faciales para las distintas clases faciales (análisis de varianza, y pruebas de comparaciones múltiples de Scheffe), sin embargo, encontramos que en todas las clases faciales de ambos sexos, predominó el tipo mesofacial y la clase I facial (57%). No se puede establecer una correlación entre forma dentaria y forma facial de manera significativa, por lo que otros parámetros también deben ser tomados en cuenta.

The purpose of this study was to relate the shape and proportion of the right maxillary central incisor with facial shape and location of dental and facial median lines. Cross-sectional study on a convenience sample consisting of 118 patients of both sexes was performed, with an average age of 25.09±7.71 years, selected according to inclusion criteria. In each case, were measured the length and width of right maxillary central incisor, tooth ratio resulting of these measures and medium tooth lines in relation to the midline. These measures were correlated with measures of facial shape and facial class. The results revealed that the most common tooth shape found was ovoid; average length and width for the maxillary central incisor were 10.28±0.91 mm and 8.69±0.57 mm, respectively; of 9.98 mm and 8.55 mm in women, and 10.62 mm and 8.86 mm in men. The dental proportion was 85%. Matches between the median lines of maxillary teeth, jaw and face were only found in 18% of cases, and the most common types of gingival contours were aesthetic (97%). There was no relationship between dental and facial for different facial types (analysis of variance and multiple comparison tests of Scheffe) measures, however, we found that all facial classes in both sexes, prevailed mesofacial and class I facial types (57%). Unable to establish a correlation between tooth shape and facial shape significantly, so other parameters should also be taken into account.

Three-dimensional finite element modeling and stress analysis on different posts and cores for repairing the maxillary central incisors / 医用生物力学

Objective To establish four finite element models for repairing root canals of the maxillary central incisors, study the influences from different post and core materials as well as root canal rehabilitations on stress distributions of the maxillary central incisors, so as to provide theoretical references for clinical application. Methods Four finite element models of repairing system were established by CBCT scanning, Mimics software, Rapidform.xor3, Solidworks and Ansys Workbench software. The occlusal loads were simulated and Von Mises stresses on the roots were calculated. Results Four precise 3D finite element models for repairing maxillary central incisors were established, including dentin, all ceramic crow, coping crown, post and core, gutta percha point, periodontal ligament, glue and alveolar bone. The analysis found out that different post and core materials as well as glues had different influences on Von Mises stress of the dentins as the greater elastic modulus of the post was, the smaller Von Mises stresses of the dentin would be. The Von Mises stress on the post and core made of cobalt-chromium alloy was 23.15 MPa, which was the smallest. Conclusions Stress distributions on repairing systems of the maxillary central incisors with different post and core materials can be predicted by establishing such different finite element models and provides a basis for the clinical application of maxillary central incisors repair systems.

A new syndrome with overlapping features of Townes-brocks syndrome and single median maxillary central incisor syndrome.

A 14-month-old boy with overlapping features of Townes-Brocks syndrome (TBS) and single median maxillary incisor syndrome (SMMCIS) is being reported with brief review of the above syndromes and possible differential diagnosis.

Influence of apical foramen lateral opening and file size on cemental canal instrumentation

Since instrumentation of the apical foramen has been suggested for cleaning and disinfection of the cemental canal, selection of the file size and position of the apical foramen have challenging steps. This study analyzed the influence of apical foramen lateral opening and file size can exert on cemental canal instrumentation. Thirty-four human maxillary central incisors were divided in two groups: Group 1 (n=17), without flaring, and Group 2 (n=17), with flaring with LA Axxess burs. K-files of increasing diameters were progressively inserted into the canal until binding at the apical foramen was achieved and tips were visible and bonded with ethyl cyanoacrylate adhesive. Roots/files set were cross-sectioned 5 mm from the apex. Apices were examined by scanning electron microscopy at ×140 and digital images were captured. Data were analyzed statistically by Student’s t test and Fisher’s exact test at 5% significance level. SEM micrographs showed that 19 (56%) apical foramina emerged laterally to the root apex, whereas 15 (44%) coincided with it. Significantly more difficulty to reach the apical foramen was noted in Group 2. Results suggest that the larger the foraminal file size, the more difficult the apical foramen instrumentation may be in laterally emerged cemental canals.

Tendo em vista que a instrumentação do forame apical tem sido sugerida para a limpeza e desinfecção do canal cementário, a seleção do calibre do instrumento e a posição do forame apical representam passos desafiantes. Este estudo analisou a influência que a saída lateral do forame apical e o calibre do instrumento podem exercer na instrumentação do canal cementário. Trinta e quatro incisivos centrais superiores foram divididos em dois grupos: Grupo 1 (n=17), sem preparo cervical, e Grupo 2 (n=17), com preparo cervical com brocas LA Axxess. Limas K com aumentos de diâmetro foram progressivamente inseridas no canal até ajustar no forame apical e as pontas ficarem visíveis e foram fixadas com adesivo de etil cianoacrilato. Os conjuntos raízes/limas foram seccionados transversalmente a 5 mm aquém do ápice. Os ápices foram examinados por microscopia eletrônica de varredura com aumento de 140x e imagens digitais foram capturadas. Os dados foram examinados estatisticamente pelo teste t de Student e teste exato de Fischer com nível de significância de 5%. A microscopia eletrônica de varredura mostrou que 19 (56%) dos forames apicais saíram lateralmente em relação ao ápice radicular, enquanto que 15 (44%) coincidiram com ele. Dificuldade significantemente maior para chegar ao forame apical foi observada no Grupo 2. Os resultados sugerem que quanto mais calibroso for o instrumento foraminal, mais difícil poderá ser a instrumentação do forame apical em canais cementários que apresentam saída lateral.

Dental trauma clinically mimicking single central incisor syndrome / Traumatismo dentário mimetizando clinicamente a síndrome do incisivo central único

PURPOSE: This paper presents a clinical case in which a patient was missing a median central incisor due to trauma but was referred for orthodontic treatment because of suspicions of solitary median maxillary central incisor (SMMCI) syndrome. CASE DESCRIPTION: A 12-year-old female patient visited the clinic with concerns about the appearance of her teeth. An oral examination revealed the presence of a single central incisor that was located on the midline and was adjacent to the maxillary lateral incisors. The patient reported two episodes of dental avulsion (of teeth 11 and 21) that had occurred approximately four years earlier. Tooth 11 was replanted; however, it was subsequently extracted due to pain. A panoramic radiograph and cephalometric analysis revealed a history of unsuccessful root canal treatment on tooth 21, a straight profile and symmetrical facial features. Tooth 21 was extracted, followed by the traction of the maxillary teeth in the mesial direction and the esthetic transformation of the lateral incisors into central incisors and the canines into lateral incisors. CONCLUSION: Dental trauma followed by tooth loss may mimic solitary median maxillary central incisor syndrome.

OBJETIVO: Apresentar um caso clínico de ausência de um incisivo central perdido por traumatismo e encaminhado ao ortodontista com suspeita de apresentar síndrome do incisivo central único (SMMCI). DESCRIÇÃO DO CASO: Paciente gênero feminino, 12 anos com queixa da aparência de seus dentes. Ao exame intrabucal observou-se a presença de um incisivo central único localizado na linha média sem espaçamentos em relação aos incisivos laterais superiores. A paciente relatou dois episódios de avulsão dos dentes 11 e 21, cerca de quatro anos antes. No entanto, devido a sintomas de dor após reimplante, o dente 11 foi extraído. A radiografia panorâmica e análise cefalométrica revelou a presença de tratamento insatisfatório do canal radicular do dente 21, um perfil reto e padrão de equilíbrio facial. Extração do dente 21 foi realizada, com tração posterior dos dentes superiores na direção mesial, seguido pela transformação estética dos incisivos laterais em incisivos centrais e dos caninos em incisivos laterais. CONCLUSÃO: O traumatismo seguido de perda dentária pode mimetizar um quadro de síndrome do incisivo central único.

Two root canals in maxillary central incisor

Introduction and objective: The success of endodontic treatment requires the knowledge of tooth morphology and its variations. Case report: This clinical article reports an unusual root canal configuration that was detected in a maxillary central incisor with two root canals, demonstrated by radiographic and computerized tomography exams. Conclusion: Knowledge of endodontic anatomy as well as the obtainment of both preoperative radiographs and tomography is important to detect abnormal tooth morphology.