Oral Applications of Cyanoacrylate Adhesives: A Literature Review.

Cyanoacrylate adhesives have been used in medicine and dentistry with some controversial opinions. The aim of this review was to summarize the relevant literature regarding the use of cyanoacrylate adhesives for oral wounds during dental and surgical procedures, with focus on the applications, indications, advantages, and disadvantages. In conclusion, in vivo and clinical studies have demonstrated in the last few years convincing results regarding the safety, efficacy, ease of application, and feasibility of all types of cyanoacrylate adhesives used in intra- and extraoral procedures.

A New Tridimensional Insight into Geometric and Kinematic Characteristics of Masticatory Cycles in Participants with Normal Occlusion.

The aim of this study was to analyze the general, geometric, and kinematic characteristics of the masticatory cycle's movements in a tridimensional way, using a method developed by our study group to provide a new insight into the analysis of mandibular movements due to advancement in the potential of computational analysis. Ten individuals (20.1 ± 2.69 years), molar class I, without mandibular movement problems participated in this study. The movements of the masticatory cycles, frontal and sagittal mandibular border movements, were recorded using 3D electromagnetic articulography and processed with computational scripts developed by our research group. The number of chewing cycles, frequency (cycles/s), chewing cycle areas/mandibular border movements areas ratios, and the mouth opening and closing speeds on the 3D trajectory of the chewing cycle were compared. The cycles were divided and analyzed in thirds. The masticatory cycles showed high variation among the individuals (21.6 ± 9.4 cycles); the frequency (1.46 ± 0.21 cycles/s) revealed a moderate positive correlation (R = 0.52) with the number of cycles. The frontal area ratios between the cycle area and the mandibular border movement presented higher values in the first third (6.65%) of the masticatory cycles, and the ratios of sagittal areas were higher and more variable (first, 7.67%; second, 8.06%; and third, 10.04%) than the frontal view. The opening and closing mouth speeds were greater in the second third of the masticatory cycles (OS, 57.82 mm/s; CS, 58.34 mm/s) without a significant difference between the opening and closing movements when the same thirds were evaluated. Further studies are necessary to improve the understanding of the masticatory cycles regarding the standardization of parameters and their values.

Systematic Standardized and Individualized Assessment of Masticatory Cycles Using Electromagnetic 3D Articulography and Computer Scripts.

Masticatory movements are studied for decades in odontology; a better understanding of them could improve dental treatments. The aim of this study was to describe an innovative, accurate, and systematic method of analyzing masticatory cycles, generating comparable quantitative data. The masticatory cycles of 5 volunteers (Class I, 19 ± 1.7 years) without articular or dental occlusion problems were evaluated using 3D electromagnetic articulography supported by MATLAB software. The method allows the trajectory morphology of the set of chewing cycles to be analyzed from different views and angles. It was also possible to individualize the trajectory of each cycle providing accurate quantitative data, such as number of cycles, cycle areas in frontal view, and the ratio between each cycle area and the frontal mandibular border movement area. There was a moderate negative correlation (-0.61) between the area and the number of cycles: the greater the cycle area, the smaller the number of repetitions. Finally it was possible to evaluate the area of the cycles through time, which did not reveal a standardized behavior. The proposed method provided reproducible, intelligible, and accurate quantitative and graphical data, suggesting that it is promising and may be applied in different clinical situations and treatments.

Magnitude and distribution of stresses in composite resin and sound dentine interface with mechanical retentions.

BACKGROUND: Adhesive systems are constantly subjected to mechanical and chemical stresses that negatively impact the integrity and durability of the dentine-adhesive interface. Despite the lack of evidence to support or reject the clinical indication for mechanical retention, the potential further contribution of these preparations to the behavior of the composite resin-sound dentine bond has been rarely addressed. The authors evaluated by finite element analysis the effect of mechanical retention on the magnitude and distribution of stresses in a composite resin-sound dentin bonding interface when subjected to tensile and shear forces. MATERIAL AND METHODS: A three-dimensional model was created based on three cylindrical volumes representing the sound dentin, adhesive system, and composite resin. From this main model, two models were designed to simulate dentine bonding: 1) a model with no mechanical retention, which considered flat adhesion; and 2) a model with retention, which considered four hemispherical holes on the dentine surface. Both groups were subjected to linear static analysis under tensile and shear loading of 200N. RESULTS: At the model with retentions' bonding interface under tensile and shear loading, a concentration of Von Mises equivalent stress was observed within the retentions, with a reduction of those stresses on the bonding boundary surface. CONCLUSIONS: Additional mechanical retention increases the tensile strength of the sound dentin-composite resin bonding interface, promoting a decrease in the magnitude of the stresses and their redistribution under tensile and shear loading. Key words:Adhesion, composite resins, dentine, finite element analysis.

Use of morphometric analyses to assess the efficacy of the technique of resin composite bonded to cervical dentin with additional mechanical retentions / Uso de análisis morfométrico para evaluar la eficacia de la técnica de resina compuesta unida a dentina cervical con retenciones mecánicas adicionales

The structural changes and morphological derivatives of progressive dentin hypermineralization determine the bonding to its surface. A planimetric study and fracture volume estimate were conducted to assess the efficacy of resin composite bonded to hypermineralized cervical dentin with and without retentions by applying a shear test. Thirty-four premolars from adult patients were used to obtain a flat cervical dentin surface. The specimens were distributed randomly into two groups: 1) experimental, where hemispherical retentions were carved into the cervical dentin, and 2) control, where the flat dentin was maintained. Using a jig, a resin column was built into the dentin surface fitted with bonding in specimens from both groups, which were then subjected to the shear test. The morphological analysis was performed with a microscope while the percentage of remnant surface from each component of the adhesive bond was calculated planimetrically. The volume of lost tissue was determined using Scherle's method. In the planimetric study, the average remnant resin on the surface was significantly higher in the experimental group and there was less intact dentin in the control group. The volumetric assessment also showed a much higher loss of dentin substrate than the experimental group. Consequently, the complementary use of morphometric and volumetric techniques enables the evaluation of the efficacy of a technique, demonstrating that the inclusion of mechanical retentions in hypermineralized cervical dentin improves the bonding properties.

Los cambios estructurales y morfológicos derivados de la hipermineralización dentinaria progresiva determina la adhesión a su superficie. Fue realizado un estudio planimétrico y el volumen de fractura estimado para evaluar la eficacia de resina compuesta adherida a dentina cervical hipermineralizada con y sin retenciones a través de la prueba de cizalla. Treinta y cuatro premolares obtenidos de pacientes adultos fueron utilizados para obtener una superficie dentinaria cervical plana. Las muestras fueron distribuidas aleatoriamente en dos grupos: 1) experimental, donde se realizaron retenciones hemiesféricas a la dentina cervical, y 2) control, donde la dentina plana fue mantenida. Usando un dispositivo, una columna de resina fue construida en la superficie dentinaria y adaptada con adhesivos en las muestras de ambos grupos, las cuales fueron sometidas al test de cizalla. El análisis morfológico fue realizado con un microscopio mientras que el porcentaje de superficie remanente para cada componente del adhesivo fue calculado planimetricamente. El volumen del tejido perdido fue determinado utilizado el método de Scherle. En el estudio planimétrico, el promedio de resina remanente en la superficie fue significativamente mayor en el grupo experimental y con menos dentina intacta en el grupo control. El análisis volumétrico mostró una mayor perdida de sustrato dentinario en el grupo control. De esta manera, el uso de técnicas morfométricas y volumétricas permite la evaluación de la eficacia de una técnica, demostrando que la inclusión de retenciones mecánicas en la dentina hipermineralizada cervical mejora las propiedades de adhesión.

Método para la generación de modelos de elementos finitos de dientes / Method to generation of finite element models of teeth

El objetivo del estudio fue realizar una modelación 3D con la características morfológicas de un primer premolar superior a partir de su morfometría. Teniendo como referencia un diagrama anatómico de un primer premolar superior y sus variables morfométricas, se realizó el trazado de su contorno (software Catya) considerando al menos tres cortes transversales de la figura: vista oclusal, mesio-distal (AP) y uno vestíbulo-palatino (L). El modelo 2d obtenido se completó mediante extrapolación para obtener una imagen tridimensional en malla que, posteriormente, se transforma a elementos triangulares, quedando el modelo de premolar listo para ser importado al software de análisis de elementos finitos (Ansys). Aquí, estos elementos son transformados a su vez en elementos placa, unidos por haces, lo que le confiere un comportamiento lineal e isométrico. A éstos, se ingresan los valores de las propiedades mecánicas correspondiente a cada tejido para proceder al análisis. La figura así obtenida, permite reproducir la morfología del premolar y las relaciones entre sus componentes. Además, la linealidad e isometría conferida permite estudiar el comportamiento mecánico en cualquier sección del modelo. El diseño computacional de estructuras anatómicas, a partir de un dibujo de contorno en base a su morfología y morfometría con la técnica descrita, resulta un alternativa complementaria para estudiar la morfología y realizar análisis mecánicos de dientes u otras estructuras anatómicas.

The aim of this study was making a 3D modeling with the morphological characteristics of a first premolar from its morphometry. With reference to an anatomical diagram of a first upper premolar and morphometric relationships, it performs its contour plot (software Catya) considering at least three cross-sections of the figure seen occlusal, mesial-distal (AP) and one vestibulo-palatal (L). 2d obtained model is completed by extrapolation to obtain a three-dimensional mesh which subsequently transforms triangular elements premolar model being ready to be imported into the software of the finite element analysis (Ansys) where these elements are transformed into the once plate elements connected by beams which gives a linear and isometric to which also inputs values ??of mechanical properties for each tissue for the analysis. Thus the figure obtained allows us to reproduce the morphology of the premolar and the relationships among its components, including linearity and isometry conferred allows us to study the mechanical behavior in any section of the model. Computational design of anatomical structures from a contour drawing based on their morphology and morphometry using the technique described results in a complementary alternative to study the morphology and mechanical analyzes of teeth or other anatomical structures.