This study evaluated retention force and fatigue resistance of two overdenture attachment systems. Twenty samples (O-ring and Bar-Clip) from two manufacturers (Conexão Sistemas de Prótese and Lifecore Biomedical) were prepared and divided into four groups: (i) Conexão/O-ring; (ii) Conexão/Bar-Clip; (iii) Lifecore/O-ring and (iv) Lifecore/Bar-Clip, with five samples in each group. They were submitted to mechanical fatigue test using a servohydraulic machine performing 5500 cycles of insertion and removal (f=0.8 Hz), immersed in artificial saliva. Retention force values were obtained three times (0, 3000 and after 5500 cycles) simulating the clinical service, using a tensile strength at 1 mm min(-1) and load cell of 1 kN. Data were analysed with analysis of variance and Tukey's test at 5% level. Results showed that Conexão/Bar-Clip specimens had significantly higher retention values than Lifecore/Bar-Clip (44.61 and 18.44 N, respectively), Conexão/O-ring specimens had significantly lower values than Lifecore/O-ring (13.91 and 19.75 N, respectively). Conexão/Bar-Clip values were always significantly higher than those of Conexão/O-ring group (44.61 and 13.91 N, respectively). Lifecore (O-ring and Bar-Clip) presented similar values (19.75 and 18.44 N, respectively). The systems evaluated showed satisfactory retention force values, before and after fatigue testing. Conexão/Bar-Clip specimens presented the highest values. A 5-year simulation of insertion and removal did not decrease retention values or fracture components.

Despite presenting greater bond strength, thermocycling had a deleterious effect in Dentuflex; Ufi-gel may be adequate for short-term use.

Retention forces are significantly affected by abutment type because the metal retainer was more retentive than plastics, possibly providing better fixation of the prosthesis in position, and more difficult to remove. After 6 months of simulation, retentiveness of both plastic components was similar. There was no fracture of any component.

This study aimed at establishing the polymerization time of a microwave-cured acrylic resin (AcronTM MC), simultaneously processing 2, 4, and 6 flasks. Required time was measured according to the parameters: monomer release in water, Knoop hardness, and porosity. Samples were made with AcronTM MC in different shapes: rectangular (32 x 10 x 2.5 mm) for monomer release and porosity; and half-disc (30 mm in diameter x 4 mm in height) for Knoop hardness. There were four experimental groups (n = 24 per group): G1) one flask (control); G2) two flasks; G3) four flasks, and G4) six flasks. At first, polymerization protocol was similar for all groups (3 min/450 W). Time was then adjusted for G2, G3, and G4, based on monomer release evaluation in the control group, obtained by spectrophotometer Beckman DU-70, with emitting wave of 206 nm. Knoop hardness test was performed using a Shimadzu HMV 2000 hardness tester, and 10 indentations were performed on each specimen's surface. Porosity was assessed after specimens were immersed in black ink and the pores counted in a microscope. Results showed that the complete polymerization of the resin occurred in 4.5 min for two flasks (G2); 8.5 min for four flasks (G3); and 13 min for six flasks (G4), all with 450 W. Statistical analysis revealed that the number of flasks does not interfere with polymerization, Knoop hardness, and porosity of the resin. Results showed that polymerization of microwave-curing resin with more than one flask is a viable procedure, as long as polymerization time is adjusted.

ObjectiveTo evaluate the Knoop hardness, composition, and wear resistance of acrylic-resin artificial teeth exposed to mechanical toothbrushing. Methods Artificial under a 200-g load and at a frequency of 250 cycles per minute, using a soft-bristled toothbrush (IndicatorPlus 30, Oral-B) soaked in a 1:1 toothpaste/water slurry (Oral B Pró Saúde). Microhardness testing was performed using a 25-g load for 15 seconds in an HMV-2 hardness tester (Shimadzu). The composition of teeth from different brands was determined by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS) (Jeol JSM 5800). Results Wear results after mechanical brushing were compared by means of the paired t-test, whereas those obtained in microhardness testing were compared by ANOVA with Bonferroni correction. There was no statistically significant difference between brands in either trial. ConclusionComposition analysis revealed that all of the artificial teeth analyzed contain carbon and oxygen. Trilux and Soluut PX brand teeth also contain silicon; however, the presence of filler particles did not result in increased resistance.

SatiSfaction level and maSticatory capacity in removable partial denture wearerSResumo objetivo: O objetivo deste estudo foi avaliar o nível de satisfação e a capacidade mastigatória em pacientes usuários de Próteses Parciais Removíveis antigas comparando com novas próteses, associando aos fatores determinantes para a substituição das mesmas. métodos: Foram selecionados 22 pacientes que procuraram atendimento na disciplina de Prótese Dental da Faculdade de Odontologia da Universidade Federal do Rio Grande do Sul, para substituição de suas próteses. Os pacientes responderam a questionários sobre nível de satisfação e capacidade mastigatória antes e após a instalação das novas próteses, além de especificarem o que os motivou a procurar atendimento. resultados: Os fatores determinantes citados para a substituição das próteses foram: dificuldade na fonética (2%), desgaste oclusal (3%), dificuldade na mastigação (8%), falta de conforto (10%), perda de dentes pilares (11%), fratura da prótese (16%), falta de estética (21%), falta de retenção (24%). A média de satisfação e de capacidade mastigatória com a prótese antiga foi de 54% e 61% respectivamente, passando para 82% e 85% após a substituição das mesmas. conclusão: Com base nos dados obtidos, é possível concluir que os pacientes, em geral, tendem a perceber o benefício gerado pela substituição das próteses, o que implica em impacto na qualidade de vida dos indivíduos, apresentando melhora tanto em seu nível de satisfação quanto em sua capacidade mastigatória. palavras-chave: satisfação do paciente; reabilitação bucal; mastigação; qualidade de vida; prótese parcial removível. gabriela sant'anna moreira daniela maffei botega cristiane machado mengatto

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In the severely eroded dentition, full-mouth adhesive rehabilitation is particularly challenging because of the large number of affected teeth, loss of VDO, esthetics, and anatomy. This article presents a case report of prosthetic rehabilitation in a patient with generalized dental wear. A 32-year-old male patient presented with clinically significant dental wear affecting all teeth, with dentin exposure and short clinical crowns. A treatment approach with all-ceramic crowns and veneers was proposed. All-ceramic indirect restorations proved durable, aesthetic, and protected the tooth structure, restoring the vertical dimension of occlusion to a very satisfactory degree. Indirect restorations based on the new vertical dimension of occlusion (VDO) can restore anatomy and function.