Stress analysis of maxillary central incisors endodontically -treated with varying ferrule heights and three different post dowel materials - a finite element analysis / Análisis de tensión de los incisivos centrales superiores tratados endodónticamente con diferentes alturas de férula y tres materiales diferentes de clavija posterior: un análisis de elementos finitos

Statement of problem : fracture of endodontically treated teeth is reduced by the use of a post with ferrule, but the effect of different ferrule configurations and dowel materials is not clear. Purpose: to evaluate the effect of ferrules with different configurations and heights on the stress of endodontically treated teeth restored with three different post and dowel materials. Materials and Methods: fifteen models of maxillary central incisors restored with porcelain fused to metal crowns were obtained using pro engineer software. the models were divided into three groups, each consisting of five models with ferrule heights of 0mm, 2mm, 4mm, 2mm with oblique fracture, 4mm with oblique fracture, the models under group GFR were restored with fiberglass reinforced post (GFR) and composite core build-up, group NiCr with a custom cast post metal alloy (NiCr), and group Zr with zirconia post (Zr) and composite core build-up. an oblique load of 100N and 150N at an angle of 135 degrees was applied to the palatal surface of the tooth, a vertical load of 100N and 150N at an angle of 90 degrees was applied to the incisal tip of the tooth. The maximum principal stress and the von mises stress was calculated for the remaining tooth structure and post apex using the finite element analysis (FEA) software. Results: the maximum von misses stress was observed in the apex of the post (p<0.05). Group Zr showed the highest mean stress (6.39Mpa) followed by group NiCr (5.65Mpa). There was a significant difference between post and between NiCr and Zr post for 2mm and 4mm ferrule height, while for 0mm ferrule there was a significant difference between the GFR and NiCr groups (p<0.05). Under oblique load, the maximum mean stress was observed in remaining tooth structures while for vertical load, it was observed at the apex of the post. Regarding ferrule heights, there were significant differences between 0mm-2mm, and 0mm-4mm uniform ferrule in post apex in the case of NiCr posts (p<0.05). Absence of ferrule resulted in higher stress for the NiCr group. Conclusion: higher loads that led to fracture were observed only at the apex of the post. Zirconia posts (group Zr) had higher fracture loads, whereas absence of ferrule resulted in higher fracture load with custom cast posts (group NiCr). Fracture thresholds were high on the remaining tooth structure for all the dowel systems especially for composite core build up irrespective of ferrule height and configuration. Clinical implications: appropriate selection of post and dowel materials in different configurations of ferrule heights ensures clinical success.

Indicación del problema: la fractura de los dientes tratados endodónticamente se reduce mediante el uso de un poste con férula, pero el efecto de diferentes configuraciones de férula y materiales de clavija no está claro. Propósito: evaluar el efecto de los casquillos con diferentes configuraciones y alturas sobre el estrés de los dientes tratados endodónticamente restaurados con tres materiales diferentes de postes y tacos. materiales y métodos: quince modelos de incisivos centrales superiores restaurados con porcelana fundida a coronas de metal se obtuvieron con el software Pro Engineer. Los modelos se dividieron en tres grupos, cada uno de los cuales consta de cinco modelos con alturas de casquillo de 0mm, 2mm, 4mm, 2mm con fractura oblicua, 4mm con fractura oblicua. los modelos del grupo GFR fueron restaurados con poste reforzado con fibra de vidrio (GFR) y acumulación de núcleo compuesto, grupo nicr con una aleación de metal de poste fundido personalizado (NiCr) y grupo Zr con poste de zirconia (Zr) y acumulación de núcleo compuesto. se aplicó una carga oblicua de 100N y 150N en un ángulo de 135º a la superficie palatina del diente. se aplicó una carga vertical de 100N y 150N en un ángulo de 90º a la punta incisal del diente. la tensión principal máxima y la tensión de von mises se calcularon para la estructura dental restante y después del vértice utilizando el software de análisis de elementos finitos (FEA). Resultados: el estrés máximo de von falta se observó en el vértice de la publicación (p<0.05). El grupo Zr mostró el mayor estrés medio (6.39Mpa) seguido del grupo NiCr (5.65Mpa). Hubo una diferencia significativa entre la publicación NiCr y Zr para la altura de la férula de 2mm y 4mm, mientras que para la férula de 0mm hubo una diferencia significativa entre los grupos GFR y NiCr (p<0,05), bajo la carga oblicua, la tensión media máxima en las estructuras dentales restantes, mientras que para la carga vertical, se observó en el vértice del poste. En cuanto a las alturas de la férula, hubo diferencias significativas entre la férula uniforme de 0mm-2mm y de 0mm-4mm en el post-apex en el caso de los postes de NiCr (p<0.05), la ausencia de férula dio como resultado un mayor estrés para el grupo NiCr. Conclusión: las cargas más altas que llevaron a la fractura se observaron solo en el vértice del poste; Los postes de zirconia (grupo Zr) tuvieron mayores cargas de fractura, mientras que la ausencia de férula dio como resultado una mayor carga de fractura con postes moldeados personalizados (NiCr de grupo). Los umbrales de fractura fueron altos en la estructura dental restante para todos los sistemas de clavijas, especialmente para la acumulación de núcleos compuestos independientemente de la altura y configuración de la férula. Implicaciones clínicas: la selección adecuada de materiales de postes y tacos en diferentes configuraciones de alturas de férulas asegura el éxito clínico.

Third molars and premolars extraction in conventional orthodontics and in treatments based on maxillary bone remodeling with temporary anchorage: indications and care

ABSTRACT A bone is an anatomic structure in constant remodeling, with different, mutant and wonderfully inconstant designs. With every new and immediate functional demand, there are changes in cortical thickness, trabecular bone density and also in direction and size of trabeculae. Bones' non-stopping search is for adjusting to the functions induced by forces and movements required by a certain life style. Conventional orthodontic planning or with temporary anchorage based on bone remodeling takes into consideration the spaces that are - or may be - occupied by the teeth, in the formation of a functional and esthetic dental arch for the patient. In case it is necessary to extract a tooth and the options are the third molars, partially or totally unerupted, and teeth that belong to other dental groups, obviousness recommends - due to mouth anatomy and physiology, as well as pathologic reasons - extracting the third molars, due to of the several reasons described in the present study.

RESUMO O osso é uma estrutura anatômica em constante remodelação, com designs diferentes, mutantes e maravilhosamente inconstantes. A cada nova e imediata demanda funcional, mudam a espessura das corticais, a densidade do trabeculado, a direção e o tamanho das trabéculas. A busca incessante do osso é para se adequar às funções induzidas pelas forças e movimentos decorrentes do modo de viver. O planejamento ortodôntico convencional ou com ancoragem transitória baseada na remodelação óssea leva em consideração os espaços que os dentes ocupam, ou podem ocupar, na formação de uma arcada dentária funcional e estética para o paciente. Se for necessário extrair algum dente e houver a opção entre os terceiros molares, parcial ou totalmente não irrompidos, e os dentes de outros grupos dentários, a obviedade recomenda - por conta da anatomia e fisiologia bucal, assim como por razões patológicas - optar pela extração dos dentes do siso, pelos várias motivos que serão descritos no presente trabalho.

mean visible labial length of maxillary and mandibular anterior teeth at rest

To determine the mean visible labial length of maxillary and mandibular anterior teeth at rest. Cross-sectional study. Department of Prosthodontics, Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Karachi, from October 2012 to March 2013. A total of 200 subjects were included. Measurements were carried out using digital caliper from the border of the lip to the incisal edges of incisor and to the cusp tip for the canines. The length of the upper lip was measured from subnasale to stomion. Statistical analyses were performed by Mann Whitney-U test and Kruskal Walli's test. The age of the participant ranged between 20 and 65 years. At rest, females significantly displayed more of the maxillary central incisor [2.93 +/- 1.57 mm; p=0.003], lateral incisor [1.87 +/- 1.12 mm; p=0.005] and canine [0.59 +/- 0.62 mm; p=0.031]. With increasing age, the amount of maxillary anterior teeth visible at rest significantly decreased [p < 0.001], and increased for the mandibular teeth [p < 0.001]. Subjects with shorter upper lips significantly displayed more maxillary anterior incisor structure than subjects with longer upper lip [p < 0.001]. Females displayed significantly more labial length of the maxillary anterior teeth. The mean visible labial length of maxillary anterior teeth significantly decreased with increasing age and increased for the mandibular teeth. As the upper lip length increased, the mean visible labial length of maxillary anterior teeth significantly decreased

Apical stress distribution on maxillary central incisor during various orthodontic tooth movements by varying cemental and two different periodontal ligament thicknesses: A FEM study.

Context: During fixed orthodontic therapy, when the stress levels in the periodontal ligament (PDL) exceedsan optimum level, it could lead to root resorption. Aims: To determine an apical stress incident on the maxillary central incisor during tooth movement with varying cemental and periodontal ligament thickness by Finite Element Method (FEM) modeling. Settings and Design: A three dimensional finite element model of a maxillary central incisor along with enamel, dentin, cementum, PDL and alveolar bone was recreated using EZIDCOM and AUTOCAD software. ALTAIR Hyper mesh 7.0 version was used to create the Finite Element meshwork of the tooth. This virtual model was transferred to Finite Element Analysis software, ANSYS where different tooth movements were performed. Materials and Methods: Cemental thickness at the root apex was varied from 200 μm to 1000 μm in increments of 200 μm. PDL thickness was varied as 0.24 mm and 0.15 mm. Intrusive, Extrusive, Rotation and Tipping forces were delivered to determine an apical stress for each set of parameters. Results: Results indicated that an apical stress induced in the cementum and PDL, increased with an increase in cementum and PDL thickness respectively. Apical stress induced in the cementum remained the same or decreased with an increase in the PDL thickness. Apical stress induced in the PDL decreased with an increase in the cementum thickness. Conclusion: The study concluded that the clinical delivery of an orthodontic forces will cause stress in the cementum and PDL. Hence, it is necessary to limit the orthodontic force to prevent root resorption.

Three-dimensional finite element analysis of the stress distribution pattern in the design modifications of U-shaped palatal major connector.

Background: The U-shaped maxillary major connector is considered to be the least-desirable design by many prosthodontists as it lacks rigidity, which is a primary requisite for a major connector. Aims and Objectives: Design modifications in the U-shaped palatal major connector are desired because it lacks rigidity. The study also aimed to determine the best design when a U-shaped palatal major connector is indicated for clinical use. Materials and Methods: The normal design and the design-modified models (modification 1, 2, 3, 4) were loaded at the functional cusps of the premolars and the molars with a magnitude of 200 N, 250 N and 300 N at angulations of 60 o and 90 o on both sides of the maxillary arch. Results for each loading were obtained as stress distribution colored images and numerical values were recorded. A three-dimensional finite element analysis study of the design-modified models was performed using two finite element softwares, namely PRO-E and IDEAS. Results: The least stress value of 7.86 Megapascals (MPa) at 200 N, 60 o was recorded for the double-thickness design, followed by design 1, which was 8.03 MPa. The least stress value for the palatal mucosa and ligament was provided by design modification 1 (0.5 mm-thick U-shaped connector, 9 mm anteroposteiorly, 14.6 mm laterally), which was 9.78 MPa and 2.98 MPa, respectively. Conclusion: The double-thickness group exhibited the least internal stress for the U-shaped major connector. However, it delivered the greatest stress to the palatal mucosa and the periodontal ligaments.

Area premaxilar: su remodelación / Premaxillary area: its remodeling

Se describe una metodología de trabajo producto de nuestra investigación que dio por resultado una técnica de nuestra creatividad personal, por medio de la cual aplicamos fuerzas ortopédicas fuertes directamente sobre cada diente incisivo superior permanente, sin utilizar arcos alámbricos, para efectuar una protracción del área premaxilar.

Influence of high insertion torque on implant placement: an anisotropic bone stress analysis

The aim of this study was to evaluate the influence of the high values of insertion torques on the stress and strain distribution in cortical and cancellous bones. Based on tomography imaging, a representative mathematical model of a partial maxilla was built using Mimics 11.11 and Solid Works 2010 softwares. Six models were built and each of them received an implant with one of the following insertion torques: 30, 40, 50, 60, 70 or 80 Ncm on the external hexagon. The cortical and cancellous bones were considered anisotropic. The bone/implant interface was considered perfectly bonded. The numerical analysis was carried out using Ansys Workbench 10.0. The convergence of analysis (6 percent) drove the mesh refinement. Maximum principal stress (σmax) and maximum principal strain (εmax) were obtained for cortical and cancellous bones around to implant. Pearson's correlation test was used to determine the correlation between insertion torque and stress concentration in the periimplant bone tissue, considering the significance level at 5 percent. The increase in the insertion torque generated an increase in the σmax and εmax values for cortical and cancellous bone. The σmax was smaller for the cancellous bone, with greater stress variation among the insertion torques. The εmax was higher in the cancellous bone in comparison to the cortical bone. According to the methodology used and the limits of this study, it can be concluded that higher insertion torques increased tensile and compressive stress concentrations in the periimplant bone tissue.

O objetivo deste estudo foi avaliar a influência dos altos valores de torque de inserção na distribuição de tensões e deformações no osso cortical e medular. Com base em imagens de tomografia computadorizada, um modelo matemático representativo de um segmento da maxila foi construído utilizando os programas Mimics 11.11 e Solid Works 2010. Seis modelos foram construídos e cada um recebeu um implante com os seguintes torques de inserção no hexágono externo: 30, 40, 50, 60, 70 ou 80 Ncm. O osso cortical e medular foi considerado anisotrópico. A interface osso/implante foi considerada perfeitamente unida. A análise numérica foi realizada através do Ansys Workbench 10.0. A convergência de análise (6 por cento) determinou o refinamento da malha. A tensão máxima principal (σmax) e a deformação máxima principal (εmax) foram obtidos para o osso cortical e medular ao redor do implante. O teste de correlação de Pearson foi utilizado para determinar a correlação entre torque de inserção e de concentração de tensões e deformações no tecido ósseo peri-implantar, considerando o nível de significância de 5 por cento. O aumento no torque de inserção gerou um aumento nos valores σmax e εmax para o osso cortical e medular. O σmax foi menor para o osso medular, com maior variação de tensão entre os torques de inserção. O εmax foi maior no osso medular em relação ao osso cortical. De acordo com a metodologia utilizada e com os limites do estudo, pode-se concluir que torques alto de inserção aumentou as concentrações de tensões de tração e compressão no tecido ósseo peri-implantar.

Clinical assessment of primary stability of endosseous implants placed in the incisor region, using resonance frequency analysis methodology: an in vivo study.

AIM: To evaluate the effect of immediate loading on the primary stability of endosseous implants placed in the anterior incisor region by mapping the stability, using resonance frequency analysis, over a period of time. MATERIALS AND METHODS: A total of eight implants (Zimmer Screw-Vent) were placed in four patients. The Osstell resonance frequency analyzer was used to determine the primary stability at baseline (day 1), 15 th day, 30 th day, 60 th day, and 90 th day for each of the eight implants. Analysis of data was done using SPSS (Statistical Package for Social Science; version 4.0.1). RESULTS: All implants showed adequate initial stability at baseline with an ISQ > 50. Implant nos. 1, 3, 4, 7, and 8 showed a high initial stability at baseline (ISQ > 65), following which a decrease in the stability was recorded during the 15 th day, 30 th day, and 60 th day. By the 90 th day, the stability values were nearly equivalent to those obtained at baseline. The highest mean stability value was recorded on the day of implant placement. The lowest mean stability recording was obtained on the 30 th day after implant osteotomy. By the 90 th day, the mean stability value was nearly equivalent to that obtained at baseline. CONCLUSIONS: Within the limitations of this study, it can be concluded that immediate loading of implants placed in the maxillary and mandibular incisor region does not seem to have an adverse effect on the osseointegration of implants, which achieved a high primary stability. The use of the resonance frequency analyzer as a tool to monitor the variation in the stability of the implants over a period of time has been validated.

Padrões de fala e de deglutição em usuários de aparelho ortopédico funcional com e sem o uso do aparelho / Speech-language and swallowing pattern in functional orthopaedic device’s users with and without the use of the device

Objetivo: verificar se ocorrem modificações na fala e na deglutição em sujeitos usuários de aparelhoortopédico funcional. Métodos: foram realizados testes de fala e deglutição com e sem o uso do aparelho ortopédico funcional dos maxilares em 50 sujeitos de ambos os gêneros, com idade acimados 7 anos, em tratamento há mais de três meses. Os dados, coletados em três instituições, no período de março a dezembro de 2004, foram protocolados, documentados em vídeo e analisados. Naanálise dos dados foram utilizados o teste Binomial e o Teste Exato de Fisher. Resultados: com o uso do aparelho ortopédico funcional dos maxilares houve a necessidade de adaptações funcionais para a realização da fala e da deglutição. Com relação à fala: os itens língua baixa; articulação trancada; sobrearticulação; imprecisão articulatória; maior interposição de língua e distorção na emissãodos sibilantes apresentaram índices estatísticos significantes de interferência do aparelho, o quenão aconteceu com o item ceceio. Quanto à deglutição, foi constatada interferência significante emrelação ao movimento do músculo mentual, movimento de cabeça e sucção. No entanto, os itens movimentação da musculatura orbicular da boca; orbicular da boca e bucinador; escape de água emovimentação de pescoço, mantiveram-se inalterados. Conclusão: o uso do aparelho ortopédico funcional provoca algumas modificações nas funções de fala e de deglutição.

Purpose: to verify if modifications in speech and deglutition occur in individuals who use functionalorthopedic device. Methods: deglutition and speech tests with and without using the jaws’ functional orthopedic device were carried out in 50 individuals of both genders, older than 7-year age and under treatment for more than three months. The data collected in three institutions, from March to December2004, were recorded, documented in video and analyzed. The Binomial test and the Fisher’s Exact Test were used for data analysis. Results: functional adaptations were needed for accomplishing speech and deglutition with the use of functional orthopedic device. As regarding speech, the items:low tongue, blocked articulation, over-articulation, articulatory inaccuracy, higher tongue interposition, and distortion in the emission of sibilants, presented significant statistical indexes of the device’s interference, that did not occur with the item lisp. As for deglutition, significant interference wasobserved in relation to the mentual muscle’s movement, head movement and aspiration. However, theitems: orbicular muscle of the mouth, mouth’s orbicular and buccinator, water escape and neck movement, did not alter. Conclusion: the use of the functional orthopedic device causes some modifications in speech and deglutition functions.

Reporte de un caso clínico utilizando expansión rápida del maxilar: generalidades / Report of a clinical case using rapid maxillary expansion: generalities

Se realizó una extensa y actualizada búsqueda bibliográfica acerca de la E.R.M., sus logros y efectos sobre el complejo craneofacial. Se presentó un caso clínico de E.R.M., donde se obtuvo una verdadera separación de la sutura media maxilar, con leves inclinaciones molares, disminución de ángulo ANB y corrección de la mordida cruzada, con lo cual se pudo comprobar que los cambios citados por diferentes autores se manifestaron en nuestra paciente

Infiltraçäo anestésica da fossa ptérigo-maxilar e do nervo nasociliar: aspectos anátomo-fisiológicos / Anesthetic infiltration of the pterigum-maxilla fossa and nasociliar nerve: anatomo-physiological aspects

Säo discutidos os aspectos anatômicos da fossa ptérigo-maxilar e do nervo nasociliar, cujas infiltraçöes anestésicas säo atos simples, rápidos, eficazes e seguros em vários procedimentos odontológicos e otorrinolaringológicos, possibilitando a realizaçäo de cirurgias nasossinusais bem menos sangrantes com a utilizaçäo de doses bem menores de anestésicos gerais, em virtude da aboliçäo dos estímulos álgicos e consequente näo liberaçäo de catecolaminas