Evaluation and comparison of different polymerization techniques, curing cycles, and thicknesses of two denture base materials

Purpose: The study aimed to compare the effect of different materials, thicknesses, and polymerization methods and cycles, on the surface porosity of acrylic denture base resins. Materials and Methods: Conventional heat-polymerized polymethyl methacrylate (PMMA) and specially designed acrylic resin (Acron MC) were used to make 84 rectangular samples. They were divided into three groups to evaluate and compare the polymerization techniques, curing cycles, and thicknesses of the two denture base materials (28 samples each). Group A contained PMMA samples polymerized using water bath method (control group); Group B contained Acron MC samples polymerized by microwave method, and Group C contained PMMA samples polymerized by microwave method. Each group was further divided based on sample thickness and polymerization cycles. Each sample was scanned for surface porosity and area of each pore was measured using optical microscope. Data was analyzed using ANOVA, Bonferroni, and student t-tests. Unpaired student t-test was performed to compare the means of surface porosity with polymerization cycles and thicknesses among the groups. The power of study was kept at 80%. Results: Group C showed highest mean % of porosity depending on method of polymerization, different polymerization cycles (short and long) and polymerization cycles within the group. Group B showed the highest mean % of porosity depending on thickness and thickness within the groups. Conclusions: Microwavable acrylic resin polymerized by microwave energy exhibited statistically insignificant increase in porosity when compared to conventional heat cured acrylic resin by water bath method. Conventional acrylic resin polymerized by microwave energy exhibited high statistically significant porosity irrespective of sample thickness. There was statistically insignificant increase in porosity depending on sample thickness irrespective of material and method of polymerization.

Guarda oclusal gnatológica: técnica de elaboración, procesado y polimerizado por microondas / Gnathological occlusal guard: technique of elaboration, processing and polymerization by microwaves

Los trastornos temporomandibulares (TTM) constituyen un problema en la población en general cuyos signos y síntomas tienen un carácter multifactorial que debe ser abordado de manera interdisciplinaria para poder brindar una mejor oportunidad de éxito y estética en los tratamientos. Las guardas oclusales forman parte del tratamiento en los TTM, se deben conocer sus indicaciones, contraindicaciones, ventajas y desventajas, debido a que las guardas oclusales cumplen ciertas funciones y objetivos. La guarda oclusal elaborada por la técnica de polimerización en microondas (GOTMI) reduce signifi cativamente el tiempo de elaboración en el laboratorio, proporciona un aparato de alta calidad y baja porosidad. La GOTMI es un aparato que proporciona un método indirecto y no invasivo modifi cando la oclusión, recuperando el tejido u órganos dentales perdidos, reorganiza la actividad refl eja neuromuscular, relaja la musculatura, promueve el reposicionamiento del disco articular, protege los dientes, oclusión y estructuras de sostén periodontal, además de mejorar la estética y la autoestima del paciente. La GOTMI disminuye el dolor en la ATM y la neuromusculatura, proporciona alivio a las cefaleas tensionales, elimina las interferencias oclusales, es un distribuidor de fuerzas oclusales, además de provocar un mayor número de contactos de igual intensidad de fuerza contra la superfi cie oclusal en todos los dientes. Existen varios métodos para la confección de las guardas oclusales, en el presente trabajo se describe la elaboración de una guarda oclusal programada con los principios de oclusión orgánica. La técnica de polimerización por microondas es innovadora debido a que este proceso consiste en la generación de calor dentro de la resina mediante ondas electromagnéticas producidas por un generador llamado magnetrón. Las moléculas de metilmetacrilato son capaces de orientarse por el campo electromagnético a una frecuencia de 2,450 MHz, y cambian su dirección cinco billones de veces por segundo aproximadamente, lo que implica numerosas colisiones intermoleculares y causa una rápida polimerización (AU)

Temporomandibular disorders (TMD) are a problem in the general population whose signs and symptoms have a multifactorial character that must be addressed by an interdisciplinary team to provide a better chance of success and aesthetic treatments. Occlusal guards are part of TMD treatment, you should know the indications, contraindications, advantages, and disadvantages, because the occlusal guards perform certain functions and objectives. The occlusal guard by Iztacala modifi cation provides an indirect and noninvasive method modifying occlusion, recovering the lost dental tissue or organs, reorganizes the neuromuscular refl ex activity, relaxes the muscles, promotes articular disc repositioning, protecting the teeth and supporting occlusion structures, it also improves aesthetics and self-esteem. The occlusal guard Iztacala modifi cation has the advantage of decreasing TMJ pain, provides relief to tension headaches, elimination of occlusal interferences, is a distributor of occlusal forces as well as causing a greater number of contacts equal intensity of force against the occlusal surface of all teeth. There are several methods for the fabrication of occlusal guards, in this paper the development of an occlusal guard programmed with the principles of organic occlusion is described, using as a basis a rigid acetate and acrylic for programming, in addition to providing your cosmetic use and function. The acquisition or denial of treatment with an occlusal splint depends on the choice, preparation, occlusal guard adjustment and patient cooperation (AU)

Assessment of the impact strength of the denture base resin polymerized by various processing techniques.

Aim : To measure the impact strength of denture base resins polymerized using short and long curing cycles by water bath, pressure cooker and microwave techniques. Materials and Methods: For impact strength testing, 60 samples were made. The sample dimensions were 60 mm × 12 mm × 3 mm, as standardized by the American Standards for Testing and Materials (ASTM). A digital caliper was used to locate the midpoint of sample. The impact strength was measured in IZOD type of impact tester using CEAST Impact tester. The pendulum struck the sample and it broke. The energy required to break the sample was measured in Joules. Data were analyzed using Student's " t" test. Results: There was statistically significant difference in the impact strength of denture base resins polymerized by long curing cycle and short curing cycle in each technique, with the long curing processing being the best. Conclusion: The polymerization technique plays an important role in the influence of impact strength in the denture base resin. This research demonstrates that the denture base resin polymerized by microwave processing technique possessed the highest impact strength.

Influence of the processing technique on the flexural fatigue strength of denture base resins: An in vitro investigation.

Background : Though acrylic resins possess many desirable properties, denture fracture due to flexural fatigue or impact failure is a common problem. One major factor influencing the flexural fatigue strength of denture base resins is the processing technique used. Aim: To measure the flexural fatigue strength of denture base resins polymerized using short and long curing cycles using water bath, pressure cooker, and microwave polymerization techniques. Materials and Methods: Flexural fatigue strength of 60 samples (n=10) were measured using a cyclic 3-point loading method on a dynamic universal testing machine. Data were analyzed using a Student 't' test. Results : Comparative evaluation using Student's 't' test of mean flexural fatigue strength of samples processed by water bath processing (660.6) and the microwave technique (893.6) showed statistically significant (P <0.01) result with microwave processing being higher. Comparison of water bath (660.6) and pressure cooker (740.6) processing and microwave (893.6) and pressure cooker (740.6) processing using Student's 't' test was not statistically significant (P >0.05). In the intra-group analysis, it was found that there was statistically significant difference in samples processed using the short and long curing cycle, the latter being better in all groups, P-values being <0.05, <0.001, and <0.001 for water bath, microwave, and pressure cooker polymerization techniques, respectively. Conclusion : The polymerization procedure plays an important role in influencing the flexural fatigue strength of denture base resins, and the microwave long curing processing technique produced denture bases with highest flexural fatigue strength.