Is one dental mini-implant biomechanically appropriate for the retention of a mandibular overdenture? A comparison with Morse taper and external hexagon platforms.

STATEMENT OF PROBLEM: Limited information is available to clinicians on the use of dental mini-implants (MI) as opposed to standard-diameter implants (SDIs) for the stabilization of implant-retained mandibular overdentures (MOs). PURPOSE: The purpose of this in vitro and finite element analysis study was to analyze and compare the biomechanical behavior of MOs with either 1 or 2 implants with external hexagon (EH), Morse taper (MT) SDIs, and MIs. MATERIAL AND METHODS: Thirty photoelastic models (n=30) of each group (n=5) of SDIs (EH-1, EH-2, MT-1, MT-2) and MI (MI-1, MI-2) were fabricated for posterior, peri-implant, and total maximum shear stress evaluation by quantitative photoelastic analysis. One specimen of each group was further used to create the 6 computational models to be analyzed by finite element analysis. The maximum von Mises values and stress maps were plotted for each ductile component. Two types of load were applied to the overdenture: a150-N load bilaterally and simultaneously on the first molar and a 100-N load on the incisal edge of the central incisors at a 30-degree angle. The data were subjected to the 2-way ANOVA test and the Tukey honestly significant difference test (α=.05). RESULTS: The EH-2 and MT-2 showed the lowest posterior (P<.001) and total (P<.05) mean shear stress values. For peri-implant shear stress, no difference was found among all groups (P>.05). Regardless of the loading area, the MI-1 and MI-2 groups showed the lowest von Mises stress values. However, for implant housing, the MI-1 group, under incisor loading, presented greater stress, followed by MT-1, EH-1, EH-2, MI-2, and MT-2. The attachment was the most overloaded structure, with high values under incisor loading, especially for the groups with 2 implants (MT-2, EH-2) as compared with the other models. CONCLUSIONS: Biomechanically, regardless of the implant number, MI is a promising rehabilitation method with similar peri-implant shear stress and lower von Mises stress on the implant when compared with SDIs for MOs.

Comparison between donor nerves to motorize the free functional gracilis muscle transfer for elbow flexion: Retrospective study of 38 consecutive cases in traumatic adult brachial plexus injuries.

PURPOSE: Elbow flexion deficit is a frequent problem in traumatic brachial plexus injuries and reestablishment of this function is the primary treatment goal. When management is delayed, or the initial acute approach fails, free functional transfer of the gracilis muscle for elbow flexion is the treatment of choice. In this report, the authors present the results of a comparison study on different donor nerves (spinal accessory and ulnar) in elbow flexion reconstruction with gracilis flap for traumatic adult brachial plexus injuries. METHODS: Retrospective analysis of patients with both total or partial traumatic brachial plexus injuries was carried out. Of the 38 patients enrolled, 37 were male (97.4%) with a mean age of 28.3 years. The mean follow-up period was 25 months. Postoperative function of the gracilis muscle flap was recorded and patients were divided into two groups according to donor nerve: spinal accessory nerve (SAN) (18 cases), and motor fascicles of the ulnar (ULNAR) (20 cases). RESULTS: Twenty-six cases obtained elbow flexion strength M3 or M4 (68.4%): 0 M0 (0.0%), 4 M1 (10.5%), 8 M2 (21.1%), 9 M3 (23.7%) and 17 M4 (44.7%). The mean interval to first recorded M3 muscular strength was 12.4 months. Functional elbow flexion strength (≥ M3) had the following distribution: SAN 83.3% (15/18) and ULNAR 55.0% (11/20) (p = .086). CONCLUSION: No statistical difference for final muscle strength was found between donor nerve groups.

Biomechanical behavior of 2-implant- and single-implant-retained mandibular overdentures with conventional or mini implants.

STATEMENT OF PROBLEM: The use of single or mini dental implants to retain mandibular overdentures is still questionable. PURPOSE: The purpose of this finite element analysis (FEA) study was to investigate the biomechanical behavior of 2- and single-implant-retained mandibular overdentures with conventional or mini implants. MATERIAL AND METHODS: Four 3-dimensional (3D) finite element models were constructed with the following designs of mandibular overdentures: 2 (group 2-C) and single (group 1-C) conventional external hexagon implants with ball or O-ring attachment and 2 (group 2-M) and single (group 1-M) 1-piece mini implants. A 150-N axial load was applied bilaterally and simultaneously on the first molar. Overdenture displacement, von Mises equivalent stress (implants and/or prosthetic components), and maximum principal stresses (peri-implant bone) were recorded numerically and then color-coded and compared among the groups. RESULTS: The overdenture displacement (in mm) was higher for the 1-M (0.16) and 2-M (0.17) groups when compared with 1-C (0.09) and 2-C (0.08). Irrespective of the type of implant, the single-implant groups presented higher values of stress (in MPa) on the implants than did the 2-implant groups (1-C=52.53; 1-M=2.95; 2-C=34.66; 2-M=2.37), ball attachment (1-C=201.33; 2-C=159.06), housing or O-ring (1-C=125.01; 1-M=1.96; 2-C=88.84; 2-M=1.27), and peri-implant cortical bone (1-C=19.37; 1-M=1.47; 2-C=15.70; 2-M=1.06). The mini implant overdentures presented lower stress values on the implants, housing or O-ring, and peri-implant bone than did the conventional implant overdentures, regardless of the number of implants. CONCLUSIONS: The 2-implant-retained overdentures exhibited lower stresses than the single- implant-retained overdentures, irrespective of the type of implant. The mini implants demonstrated higher overdenture displacement and lower stresses than did conventional implant overdentures for single- and 2-implant-retained overdentures.

Influence of spark erosion on the fit of screw-retained Co-Cr fixed complete denture frameworks veneered with different materials.

STATEMENT OF PROBLEM: Spark erosion is a fit corrective technology that can be used even after the veneering material has been applied. The framework does not require sectioning, thus preserving its mechanical resistance. However, the spark erosion effect on veneered Co-Cr fixed complete denture (FCD) frameworks has not been investigated. PURPOSE: The purpose of this in vitro study was to evaluate whether spark erosion is effective in improving marginal fit on screw-retained Co-Cr FCD frameworks veneered with different materials. A comparison between ceramic applications and simulated ceramic firing cycles was also investigated. MATERIAL AND METHODS: Forty FCD frameworks were fabricated with a Co-Cr alloy. Four groups (n=10) were obtained according to the veneer material used on frameworks: HR (heat-polymerized resin); LR (light-polymerized resin); C (ceramic); and SC (simulated ceramic firing cycle). The spark erosion process was conducted for all groups. The marginal fit was analyzed according to the single-screw test protocol, and the measurements were performed at 3 evaluation times: initial, after veneer material application, and after spark erosion process. The results were submitted to a 2-way repeated measures ANOVA and the Tukey honest significant differences test (α=.05). RESULTS: Poorer marginal fit (in micrometers) was noted after veneer material application, where the HR and C groups presented the worst values (HR: 170; LR: 72; C: 165; SC: 86; P<.05). The spark erosion process was effective in improving the fit for all groups (HR: 109; LR: 52; C: 110; SC: 60; P<.05). CONCLUSIONS: Spark erosion improved the fit of Co-Cr FCD frameworks veneered with different materials. An actual ceramic application should be used to assess distortions generated by veneer material application instead of using only simulated ceramic firing cycles.

A Qualitative Study on Patients' Perceptions of Two Types of Attachments for Implant Overdentures.

The aim of this qualitative study was to gain a deeper understanding of patient perceptions of wearing implant-retained overdentures with ball-shaped or cylindrical attachment systems. Twenty-two wearers of implant-supported overdentures participated in this qualitative study based on a randomized crossover clinical trial that aimed to compare a cylindrical attachment and a ball attachment. In phase I of the study, group A experienced ball attachments (n = 11) and group B Locator attachments (n = 11) for 1 year. Afterward, in phase II, the attachments were changed; group A received Locator attachments and group B received ball attachments. One week after the attachment's replacement, semistructured individual interviews were conducted. All interviews were audiotaped and transcribed. The analysis was guided by thematic content analysis. Most of the patients from both groups preferred the attachment they received in phase II, regardless the type. A major theme raised by the participants to justify their preference between the attachment types was prosthesis retention/stability, sometimes considered as a positive and other times as a negative factor. Other themes were also explored: oral function, pain, hygiene, previous experiences, confidence on the dentist's work, and esthetic. Aspects related to the retention/stability of the overdentures are the main concerns associated with the perceptions of most patients treated with implant overdentures regardless of the type of attachment. Adequate retention level should be identified and adjusted on an individual basis and maintained overtime as possible. Therefore, follow-up appointments should be planned for readjustment of the attachment's retention. Overretention should be avoided.

Correlation between the elbow flexion and the hand and wrist flexion after neurotization of the fascicles of the ulnar nerve to the motor branch to the biceps.

OBJECTIVE: Gain in elbow flexion in patients with brachial plexus injury is extremely important. The transfer of a fascicle from the ulnar nerve to the motor branch of the musculocutaneous nerve (Oberlin surgery) is a treatment option. However, in some patients, gain in elbow flexion is associated with wrist and finger flexion. This study aimed to assess the frequency of this association and the functional behavior of the limb. METHODS: Case-control study of 18 patients who underwent the Oberlin surgery. Group 1 included patients without disassociation of range of elbow flexion and that of the fingers and wrist; Group 2 included patients in whom this disassociation was present. In the functional evaluation, the Sollerman and DASH tests were used. RESULTS: It was observed that 38.89% of the patients did not present disassociation of elbow flexion with flexion of the wrist and fingers. Despite the existence of a favorable difference in the group with disassociation of the movement, when the Sollerman protocol was applied to the comparison between both groups, this difference was not statistically significant. With the DASH test, however, there was a statistically significant difference in favor of the group of patients who managed to disassociate the movement. CONCLUSION: The association of elbow flexion with flexion of the wrist and fingers, in the group studied, was shown to be a frequent event, which influenced the functional result of the affected limb.

OBJETIVO: O ganho da flexão do cotovelo em pacientes com lesão no plexo braquial é de suma importância. A cirurgia de transferência de fascículo do nervo ulnar para ramo motor do nervo musculocutâneo (cirurgia de Oberlin) é uma opção de tratamento. Contudo, o ganho da flexão do cotovelo, em alguns pacientes, vem associado à flexão do punho e dos dedos. O objetivo deste trabalho é avaliar a frequência dessa associação e o comprometimento funcional do membro. MÉTODOS: Estudo tipo caso-controle de 18 pacientes submetidos à cirurgia de Oberlin. No Grupo 1 foram incluídos os pacientes que não apresentavam dissociação do ganho da flexão do cotovelo com a dos dedos e do punho; no Grupo 2, os pacientes em que havia dissociação. Os testes de Sollerman e Disabilities of the Arm, Shoulder and Hand (Dash) foram usados na avaliação funcional. RESULTADOS: Observou-se que 38,89% dos pacientes não dissociavam flexão de cotovelo de flexão de punho e dos dedos. Apesar de existir uma diferença favorável ao grupo que dissociava o movimento quando aplicado o protocolo de Sollerman na comparação entre os pacientes dos dois grupos, essa não se mostrou estatisticamente significante. Já no teste Dash, observou-se diferença estatisticamente significante, favorável ao grupo de pacientes que consegue dissociar o movimento. CONCLUSÃO: A associação da flexão do cotovelo com a flexão de punho e dos dedos no grupo estudado mostrou ser um evento frequente, teve influência no resultado funcional do membro acometido.

Correlation between the elbow flexion and the hand and wrist flexion after neurotization of the fascicles of the ulnar nerve to the motor branch to the biceps / Correlação da flexão do cotovelo com a flexão da mão e do punho após neurotização dos fascículos do nervo ulnar para ramo motor do bíceps

ABSTRACT OBJECTIVE: Gain in elbow flexion in patients with brachial plexus injury is extremely important. The transfer of a fascicle from the ulnar nerve to the motor branch of the musculocutaneous nerve (Oberlin surgery) is a treatment option. However, in some patients, gain in elbow flexion is associated with wrist and finger flexion. This study aimed to assess the frequency of this association and the functional behavior of the limb. METHODS: Case-control study of 18 patients who underwent the Oberlin surgery. Group 1 included patients without disassociation of range of elbow flexion and that of the fingers and wrist; Group 2 included patients in whom this disassociation was present. In the functional evaluation, the Sollerman and DASH tests were used. RESULTS: It was observed that 38.89% of the patients did not present disassociation of elbow flexion with flexion of the wrist and fingers. Despite the existence of a favorable difference in the group with disassociation of the movement, when the Sollerman protocol was applied to the comparison between both groups, this difference was not statistically significant. With the DASH test, however, there was a statistically significant difference in favor of the group of patients who managed to disassociate the movement. CONCLUSION: The association of elbow flexion with flexion of the wrist and fingers, in the group studied, was shown to be a frequent event, which influenced the functional result of the affected limb.

RESUMO OBJETIVO: O ganho da flexão do cotovelo em pacientes com lesão no plexo braquial é de suma importância. A cirurgia de transferência de fascículo do nervo ulnar para ramo motor do nervo musculocutâneo (cirurgia de Oberlin) é uma opção de tratamento. Contudo, o ganho da flexão do cotovelo, em alguns pacientes, vem associado à flexão do punho e dos dedos. O objetivo deste trabalho é avaliar a frequência dessa associação e o comprometimento funcional do membro. MÉTODOS: Estudo tipo caso-controle de 18 pacientes submetidos à cirurgia de Oberlin. No Grupo 1 foram incluídos os pacientes que não apresentavam dissociação do ganho da flexão do cotovelo com a dos dedos e do punho; no Grupo 2, os pacientes em que havia dissociação. Os testes de Sollerman e Disabilities of the Arm, Shoulder and Hand (Dash) foram usados na avaliação funcional. RESULTADOS: Observou-se que 38,89% dos pacientes não dissociavam flexão de cotovelo de flexão de punho e dos dedos. Apesar de existir uma diferença favorável ao grupo que dissociava o movimento quando aplicado o protocolo de Sollerman na comparação entre os pacientes dos dois grupos, essa não se mostrou estatisticamente significante. Já no teste Dash, observou-se diferença estatisticamente significante, favorável ao grupo de pacientes que consegue dissociar o movimento. CONCLUSÃO: A associação da flexão do cotovelo com a flexão de punho e dos dedos no grupo estudado mostrou ser um evento frequente, teve influência no resultado funcional do membro acometido.

Soft denture liners and sodium perborate: sorption, solubility and color change

Abstract Aim: To evaluate the sorption, solubility and color change in two lining materials after 120 days of immersion in either sodium perborate or artificial saliva. Methods: Thirty disk-shaped specimens (15×3 mm) of each material, Mucopren(r) soft (MS) and Elite(r) soft (ES) were manufactured and divided into two groups. The specimens in the control group (CG, n=15) were stored in artificial saliva at 37 °C. The specimens in the experimental group (EG, n=15) were stored in artificial saliva at 37 °C and immersed in sodium perborate daily for 5 min. The analysis of sorption and solubility was based on the initial dry weight and on the wet and dry weights after immersion. The color was assessed with a portable spectrophotometer and the NBS system. ANOVA and Tukey test (p<0.05) were used to analyze color and sorption. The solubility was analyzed by KruskalWallis test (p<0.05). Results: Sorption was higher in the EG group (0.31±0.08) than in the control group (0.26±0.05), and higher in Elite(r) soft relining (0.34±0.07) than in Mucopren(r) soft (0.23±0.06). There was no interaction between the factors. Elite(r) Soft presented a higher solubility when immersed in artificial saliva (CG: 0.16±0.07 and EG: 0.13±0.06; p=0.00). Mucopren(r) soft showed no solubility in either treatment. Regarding the color changes, there was a significant difference between the groups (CG: 9.2±1.2 and EG: 9.9±1.2; p=0.025) but not between the materials (Mucopren(r) soft: 9.4±1.3 and Elite(r)soft: 9.7±1.0; p=0.34). Using the NBS system, we verified that both materials presented a high color change. Conclusions: The daily use of sodium perborate promoted changes in the liners' sorption and color. Elite(r) soft relining was more prone to changes than Mucopren(r) soft.

Biomechanical study of the sacroiliac fracture fixation with titanium rods and pedicle screws.

OBJECTIVES: To assess biomechanically different fixations means of the sacroiliac joint with pedicle screws and to compare the traditional head height with reduced ones. METHODS: We used a polyethylene model representing the pelvic ring and simulated a unilateral sacroiliac dislocation. We set up three different constructions: 1) two screws attached to a rod; 2) two rods connected to two small head screws each; and 3) two rods connected to two average headed screws each. We conducted tests in a biomechanical testing and a mechanized processing laboratory. RESULTS: Group 1 supported an average maximum load of 99.70 N. Group 2 supported an average maximum load of 362.46 N. Group 3 endured an average maximum load of 404.15 N. In the assembly with one rod, the resistance decreased as compared with the one with two bars: 72.5 % compared to small-headed screws and 75.3 % to the traditional screw. CONCLUSION: The assembly with a single bar presented inferior results when compared to the double bar assembly. There was no statistical difference in the results between the screws used. Experimental Study.

Estudo biomecânico da fixação da fratura sacroilíaca com barras de titânio e parafusos pediculares / Biomechanical study of the sacroiliac fracturefixation with titanium rods and pedicle screws

Objetivos: Avaliar biomecanicamente diferentes tipos de fixação da articulação sacroilíaca com parafusos pediculares e comparar parafusos de perfil baixo e tradicional. Métodos: Foi utilizado um corpo de prova de polietileno representando o anel pélvico e simulou-se uma luxação sacroilíaca unilateral. Foram montadas três fixações diferentes:1) dois parafusos ligados a uma haste; 2) duas hastes conectadas adois parafusos de baixo perfil cada; e 3) a mesma montagem com parafusos de perfil tradicional. Foram realizados testes em um laboratório de ensaios biomecânicos e mecanográficos. Resultados: No grupo 1 houve suporte de carga máxima média de 99,70 N. O grupo 2suportou carga máxima média de 362,46 N. O grupo 3 suportou carga máxima média de 404,15 N. Na montagem com uma haste houve diminuição de resistência, quando comparado com as montagens com duas barras: 72,5% comparando com parafusos de baixo perfile 75,3% com parafuso tradicional. Conclusão: A montagem com barra única apresentou resultados muito inferiores comparada com a barra dupla. Não houve diferença estatística na comparação dos resultados entre os parafusos utilizados. Estudo Experimental.

Objectives: To assess biomechanically different fixations means of the sacroiliac joint with pedicle screws and to compare the traditional head height with reduced ones. Methods: We used a polyethylene model representing the pelvic ring and simulated a unilateral sacroiliac dislocation. We set up three different constructions: 1) two screws attached to a rod; 2) two rods connected to two small head screws each; and 3) two rods connected to two average headed screws each. We conducted tests in a biomechanical testing and a mechanized processing laboratory. Results: Group 1 supported an average maximum load of 99.70 N.Group 2 supported an average maximum load of 362.46 N. Group3 endured an average maximum load of 404.15 N. In the assembly with one rod, the resistance decreased as compared with the one with two bars: 72.5 % compared to small-headed screws and75.3 % to the traditional screw. Conclusion: The assembly with a single bar presented inferior results when compared to the double bar assembly. There was no statistical difference in the results between the screws used. Experimental Study.

In vitro antimicrobial activity of an experimental dentifrice based on Ricinus communis.

This study evaluated the antimicrobial activity of a Ricinus communis-based experimental dentifrice for denture hygiene against the following standard strains: Staphylococcus aureus, Escherichia coli, Streptococcus mutans, Enterococcus faecalis, Candida albicans and Candida glabrata. The minimum inhibitory concentration (MIC) assay was performed with R. communis in pure oil at 2.5%. Only E. coli was not inhibited by R. communis, but the MIC (0.0781%) was effective against the other microorganisms. From these results it was determined the R. communis concentrations for experimental dentifrices, 1, 2, 5 and 10%, which were evaluated by the test-well diffusion in agar. The commercial dentifrices Colgate, Trihydral and Corega Brite were tested for comparative purposes. The diameter of the zones of bacterial growth inhibition produced around the wells was measured (in mm) with a rule under reflected light. Data were analyzed statistically by analysis of variance and Tukey's post-hoc test (α=0.05). Neither the commercial nor the experimental dentifrices were effective against E. coli. The experimental dentifrices containing R. communis at 2, 5 and 10% presented action against S. mutans, S. aureaus and E. faecallis. The experimental dentifrices showed no antimicrobial activity against Candida spp. and E. coli in any of the tested concentrations. Trihydral was the most effective. Comparing the experimental dentifrices, the product with 10% R. communis produced the largest zones of bacterial growth inhibition and had similar antimicrobial activity to the commercial dentifrices, except against S. aureus.

In Vitro Antimicrobial Activity of an Experimental Dentifrice Based on Ricinus Communis

This study evaluated the antimicrobial activity of a Ricinus communis-based experimental dentifrice for denture hygiene against the following standard strains: Staphylococcus aureus, Escherichia coli, Streptococcus mutans, Enterococcus faecalis, Candida albicans and Candida glabrata. The minimum inhibitory concentration (MIC) assay was performed with R. communis in pure oil at 2.5%. Only E. coli was not inhibited by R. communis, but the MIC (0.0781%) was effective against the other microorganisms. From these results it was determined the R. communis concentrations for experimental dentifrices, 1, 2, 5 and 10%, which were evaluated by the test-well diffusion in agar. The commercial dentifrices Colgate, Trihydral and Corega Brite were tested for comparative purposes. The diameter of the zones of bacterial growth inhibition produced around the wells was measured (in mm) with a rule under reflected light. Data were analyzed statistically by analysis of variance and Tukey's post-hoc test (α=0.05). Neither the commercial nor the experimental dentifrices were effective against E. coli. The experimental dentifrices containing R. communis at 2, 5 and 10% presented action against S. mutans, S. aureaus and E. faecallis. The experimental dentifrices showed no antimicrobial activity against Candida spp. and E. coli in any of the tested concentrations. Trihydral was the most effective. Comparing the experimental dentifrices, the product with 10% R. communis produced the largest zones of bacterial growth inhibition and had similar antimicrobial activity to the commercial dentifrices, except against S. aureus.

Este estudo avaliou a atividade antimicrobiana de um dentifrício experimental a base de Ricinus communis para higiene de prótese contra as seguintes cepas padrão: Staphylococcus aureus, Escherichia coli, Streptococcus mutans, Enterococcus faecalis, Candida albicans e Candida glabrata. O ensaio de concentração inibitória mínima foi realizado com R. communis em óleo puro a 2,5 % . Apenas a E. coli não foi inibida por R. communis, no entanto, a concentração mínima (0,0781%) foi eficaz contra os outros microrganismos. A partir destes resultados foram determinadas as concentrações dos dentifrícios experimentais: 1, 2, 5 e 10 %, as quais foram avaliadas pelo teste de difusão em Agar. Os dentifrícios comerciais Colgate, Trihydral e Corega Brite foram testados para fins comparativos. O diâmetro dos halos de inibição do crescimento bacteriano, em torno dos poços, foi medido (em mm) com uma régua sob uma luz refletida. Os dados foram analisados estatisticamente por meio de análise de variância e teste post-hoc de Tukey (α=0,05). Nem os dentifrícios comerciais nem os experimentais foram eficazes contra E. coli. Os dentifrícios experimentais contendo R. communis a 2 , 5 e 10 % apresentaram ação contra S. mutans, S. aureaus e E. faecallis. Os dentifrícios experimentais não mostraram atividade antimicrobiana contra Candida spp e E. coli em nenhuma das concentrações testadas . O Trihydral foi o mais eficaz. Comparando os dentifrícios experimentais, o produto com 10% de R. communis produziu os maiores halos de inibição do crescimento microbiano e apresentou atividade antimicrobiana.

Trial of an experimental castor oil solution for cleaning dentures.

Denture hygiene is essential because denture biofilm is involved in oral infections and systemic diseases. Although there are chemical agents available on the market, none of them have ideal properties and research on such products is still necessary. The aim of this study was to evaluate the efficacy of a castor bean (Ricinus communis)-based solution for removing denture biofilm, compared to two traditional products (sodium hypochlorite and alkaline peroxide). Fifty maxillary complete denture wearers were instructed to brush their dentures after meals and to immerse their dentures once a day in the following solutions: Saline (20 min; control), Polident alkaline peroxide (3 min), NaOCl (20 min) and 2% castor oil solution (20 min). Participants used each solution for a period of 7 consecutive days, according to a random sequence. After each period, the internal surfaces of maxillary complete dentures were stained with a disclosing solution (1% neutral red), photographed and the disclosed biofilm was quantified with the aid of specific software. The influence of treatments on results was verified by the Friedman test (α=0.05). Tested solutions presented significant difference (Fr=51.67; p<0.001). Saline and NaOCl were significantly different (median: 2.0% and 0.0%) whereas Polident and castor oil presented intermediate results (median: 1.0% and 1.5%, respectively). It can be concluded that the castor oil solution tested in this study was comparable to alkaline peroxide in terms of efficiency in denture biofilm removal.

Microstructural characterization and evaluation of the properties of polymeric materials for maxillofacial prosthetics.

This study evaluated the Shore A hardness, colour and microstructural alterations of an experimental silicone for maxillofacial prostheses. As a control, the MDX 4-4210 silicone was used. Eighty specimens of each material were randomly divided into groups of pigmentation and ageing. For microstructural analysis by Thermogravimetry, Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry, three specimens of each group were used. Anova and Tukey test (p < 0.05) was used in statistical analysis. There was significant difference in hardness depending on the materials, pigmentation and ageing and interaction between all the factors evaluated (p = 0.00). The colour change was significant due to ageing (p = 0.00) and the interaction between the factors evaluated (p = 0.00). The microstructural analyses have shown that ageing methods and pigmentations did not cause structural alterations. The results suggest that the alterations in hardness and colour do not represent important structural changes.

Trial of an Experimental Castor Oil Solution for Cleaning Dentures

Denture hygiene is essential because denture biofilm is involved in oral infections and systemic diseases. Although there are chemical agents available on the market, none of them have ideal properties and research on such products is still necessary. The aim of this study was to evaluate the efficacy of a castor bean (Ricinus communis)-based solution for removing denture biofilm, compared to two traditional products (sodium hypochlorite and alkaline peroxide). Fifty maxillary complete denture wearers were instructed to brush their dentures after meals and to immerse their dentures once a day in the following solutions: Saline (20 min; control), Polident alkaline peroxide (3 min), NaOCl (20 min) and 2% castor oil solution (20 min). Participants used each solution for a period of 7 consecutive days, according to a random sequence. After each period, the internal surfaces of maxillary complete dentures were stained with a disclosing solution (1% neutral red), photographed and the disclosed biofilm was quantified with the aid of specific software. The influence of treatments on results was verified by the Friedman test (α=0.05). Tested solutions presented significant difference (Fr=51.67; p<0.001). Saline and NaOCl were significantly different (median: 2.0% and 0.0%) whereas Polident and castor oil presented intermediate results (median: 1.0% and 1.5%, respectively). It can be concluded that the castor oil solution tested in this study was comparable to alkaline peroxide in terms of efficiency in denture biofilm removal.

A higiene de próteses totais é essencial, uma vez que o biofilme da prótese está envolvido com infecções orais e doenças sistêmicas. Apesar de existirem agentes químicos disponíveis no mercado, nenhum deles apresenta propriedades ideais e pesquisas com esses produtos ainda são necessárias. O objetivo neste estudo foi avaliar a eficácia de uma solução de mamona (Ricinus communis) para a remoção do biofilme de prótese total, comparada com dois produtos comerciais (NaOCl e peróxido alcalino). Cinqüenta usuários de próteses totais maxilares foram instruídos a escovar as próteses após as refeições e imergi-las uma vez por dia nas seguintes soluções: soro fisiológico (20 min), Peróxido alcalino Polident (3 min), NaOCl a 1% (20 min) e solução de mamona (20 min). Os participantes utilizaram cada solução por um período de sete dias consecutivos, de acordo com uma sequência aleatória. Após cada período, as superfícies internas das próteses totais superiores foram coradas com solução evidenciadora (vermelho neutro a 1%), fotografadas e o biofilme evidenciado foi quantificado com software. A influência dos tratamentos sobre os resultados foi verificada pelo teste de Friedman (α=0,05). Houve diferença significativa entre as soluções (Fr=51,67;p<0,001). O soro fisiológico e o NaOCl foram significativamente diferentes (mediana: 2,0% e 0,0%), enquanto o Polident e a solução de mamona apresentaram resultados intermediários (mediana: 1,0% e 1,5%, respectivamente). Concluiu-se que a solução de mamona avaliada é comparável ao peróxido alcalino, em termos de remoção do biofilme de prótese total.

Clinical trial of an experimental cleaning solution: antibiofilm effect and integrity of a silicone-based denture liner.

AIM: This study evaluated the antibiofilm effect of an experimental solution of 2% Ricinus communis (R. communis) on a silicone-based denture liner by means of a randomized clinical trial, as well as the integrity of such liner following a cleansing regimen with such solution. MATERIALS AND METHODS: About 30 complete denture wearers had their lower dentures relined with a silicone-based denture liner and randomly allocated to cleanse their dentures by means of: (A) a specific toothbrush for complete dentures and dentifrice; (B) soaking in an experimental 2% R. communis solution; and (C) association of A and B. Considered outcomes were biofilm coverage area (%), microbial counts by means of the deoxy-ribonucleic acid (DNA) checkerboard hybridization technique and physical integrity of the soft liner, assessed during a time interval of 60 days. Mean group values were compared by analysis of variance (ANOVA) and Tukey tests or generalized linear method (α = 0.05). RESULTS: The mechanical method presented the lowest biofilm percentage (1.45 ± 1.03) if compared to the chemical method (2.96 ± 1.98) and the associated one (2.71 ± 1.76). After 60 days (3.37 ± 2.04), biofilm accumulation was higher than at 15 days (1.28 ± 0.77) and 30 days (2.46 ± 1.54). The denture liner was less deteriorated and kept its physical integrity when the mechanical method was applied. The chemical method presented higher effectiveness against microorganisms, including some Candida species. CONCLUSION: The 2% R. communis solution presented stronger antimicrobial capacity than brushing on a silicone-based denture liner after immersion. However, it was not superior to the mechanical method in preserving the physical integrity of the material and in biofilm removal. CLINICAL SIGNIFICANCE: Soft denture liners hygiene is a very important issue and not conclusive in the literature. The experimental solution of 2% R. communis evaluated presented promising antimicrobial potential and should be more explored to be recommended as cleanser.

Electromyography of masticatory muscles after denture relining with soft and hard denture liners.

We evaluated electromyograms of masticatory muscles after denture relining with soft and hard liners. In total, 44 patients with complete dentures were studied: 22 underwent chairside relining of mandibular dentures with a soft, silicone-based liner (Mucopren Soft); the other 22 underwent relining with a hard, acrylic resin-based liner (Kooliner). Electromyograms of the masseter and temporal muscles were obtained before (T0) and 90 days after (T90) relining. Participants performed a maximum voluntary contraction (static test), on which percentage-overlapping coefficient (%), mandibular displacement (%), and standardized electromyographic activity, i.e., impact, (µV / µVs %) were analyzed. Participants were also asked to chew a wafer, cereal bar, and peanuts (dynamic test) to determine symmetrical mastication index (SMI%), frequency (Hz), and impact. The data were analyzed using a generalized linear model (α= 0.05). On the static test, mandibular displacement was lower and impact was higher at T90, as compared with baseline. On the dynamic test, SMI and impact were higher after relining for all foods. Frequency at T90 was higher only during cereal and peanut mastication. There were no differences between groups except for greatest impact during wafer chewing in patients with hard liners. Relining with hard and soft materials increased electromyographic activity and improved masticatory function. There was little difference between groups.

Color stability, surface roughness and flexural strength of an acrylic resin submitted to simulated overnight immersion in denture cleansers.

This study evaluated color stability, surface roughness and flexural strength of acrylic resin specimens after immersion in alkaline peroxide and alkaline hypochlorite, simulating a period of one and a half year of use of overnight immersion. Sixty disc-shaped (16x4 mm) and 80 rectangular specimens (65x10x3.3 mm) were prepared from heat-polymerized acrylic resin (Lucitone 550) and distributed into 4 groups (n=20): C1: without immersion, C2: 8 h immersion in distilled water; AP: 8 h immersion in alkaline peroxide effervescent tablet; SH: 8 h immersion in 0.5% NaOCl solution. Properties were evaluated at baseline and after the immersion. Color data were also calculated according the National Bureau of Standards (NBS). Results were analyzed statistically by ANOVA and Tukey's HSD test (α=0.05). AP (2.34 ± 0.41) caused color alteration significantly higher than C2 (0.39 ± 0.30) and SH (1.73 ± 0.52). The mean ΔE values were classified as indicial for C2 (0.36 ± 0.29) and noticeable for AP (2.12 ± 0.39) and SH (1.59 ± 0.48). SH (0.0195 ± 0.0150) caused significantly higher ΔRa (p=0.000) than the C2 (0.0005 ± 0.0115) and PA (0.0005 ± 0.0157) groups. There was no statistically significant difference (p=0.063) among the solutions for flexural strength (C1: 105.43 ± 14.93, C2: 100.30 ± 12.43, PA: 97.61 ± 11.09, SH: 95.23 ± 10.18). In conclusion, overnight immersion in denture cleansing solutions simulating a year and a half of use did not alter the flexural strength of acrylic resin but caused noticeable color alterations, higher for alkaline peroxide. The 0.5% NaOCl solution caused increase in surface roughness.

Color Stability, Surface Roughness and Flexural Strength of an Acrylic Resin Submitted to Simulated Overnight Immersion in Denture Cleansers

This study evaluated color stability, surface roughness and flexural strength of acrylic resin specimens after immersion in alkaline peroxide and alkaline hypochlorite, simulating a period of one and a half year of use of overnight immersion. Sixty disc-shaped (16X4 mm) and 80 rectangular specimens (65X10X3.3 mm) were prepared from heat-polymerized acrylic resin (Lucitone 550) and distributed into 4 groups (n=20): C1: without immersion, C2: 8 h immersion in distilled water; AP: 8 h immersion in alkaline peroxide effervescent tablet; SH: 8 h immersion in 0.5% NaOCl solution. Properties were evaluated at baseline and after the immersion. Color data were also calculated according the National Bureau of Standards (NBS). Results were analyzed statistically by ANOVA and Tukey's HSD test (α=0.05). AP (2.34 ± 0.41) caused color alteration significantly higher than C2 (0.39 ± 0.30) and SH (1.73 ± 0.52). The mean ΔE values were classified as indicial for C2 (0.36 ± 0.29) and noticeable for AP (2.12 ± 0.39) and SH (1.59 ± 0.48). SH (0.0195 ± 0.0150) caused significantly higher ΔRa (p=0.000) than the C2 (0.0005 ± 0.0115) and PA (0.0005 ± 0.0157) groups. There was no statistically significant difference (p=0.063) among the solutions for flexural strength (C1: 105.43 ± 14.93, C2: 100.30 ± 12.43, PA: 97.61 ± 11.09, SH: 95.23 ± 10.18). In conclusion, overnight immersion in denture cleansing solutions simulating a year and a half of use did not alter the flexural strength of acrylic resin but caused noticeable color alterations, higher for alkaline peroxide. The 0.5% NaOCl solution caused increase in surface roughness.

Resumo O estudo avaliou a alteração de cor, rugosidade de superfície e força de flexão de espécimes de resina acrílica após imersão em peróxido alcalino e hipoclorito alcalino, simulando um ano e meio de uso seguindo a imersão noturna. Sessenta espécimes circulares (16 X 4 mm) e oitenta retangulares (65 X 10 X 3,3 mm) de resina acrílica termopolimerizável (Lucitone 550) foram distribuídos em 4 grupos (n=20): C1: sem imersão, C2: 8 h de imersão em água destilada; PA: 8 h de imersão em pastilhas efervescentes de peróxido alcalino; HS: 8 h de imersão em hipoclorito de sódio a 0,5%. As propriedades foram avaliadas antes e após as imersões. Os dados de alteração de cor também foram calculados de acordo com o National Bureau of Standards (NBS). Os dados foram analisados estatisticamente pelo teste ANOVA e Tukey HSD (α=0,05). O PA (2,34 ± 0,41) causou alteração de cor significativamente maior que C2 (0,39 ± 0,30) e SH (1,73 ± 0,2). A média ΔE foi classificada como indicial para C2 (0,36 ± 0,29) e perceptível para PA (2,12 ± 0,39) e HS (1,59 ± 0,48). HS (0,0195 ± 0,0150) causou significantemente maior ΔRa (p=0) do que os demais (C2: 0,0005 ± 0,0115 e PA: 0,0005 ± 0,0157). Não houve diferença estatisticamente significante (p=0,063) entre as soluções para a resistência à flexão (C1: 105,43 ± 14,93; C2: 100,30 ± 12,43, PA: 97,61 ± 11,09, HS: 95,23 ± 10,18). A imersão noturna em soluções higienizadores de próteses simulando um ano e meio de uso não alterou a resistência à flexão da resina acrílica, porém causou alterações perceptíveis de cor, sendo maiores com o peróxido alcalino. O hipoclorito de sódio a 0,5% ...

Alteration of the bristles of a toothbrush after brushing of the acrylicresin using different dentifrices / Alteração das cerdas de uma escova dental após escovação da resina acrílica com diferentes dentifrícios

Objective: This study evaluated the change in toothbrush bristles after brushing with water and four dentifrices, one for natural teeth (Sorriso, Colgate-Palmolive Ind e Com. Ltda., Osasco, Brazil) and three for dentures: Corega (GSK - GlaxoSmithKline, Brasil Ltda., Rio de Janeiro, Brazil), Experimental 1 (Zonil) Experiment 2 (Chloramine T). Methods: Soft brushes were used with 26 clumps of bristles with 0.25 mm in diameter and 10 mm high. Brushing was performed on a Pepsodent machine where the toothbrushes and associated dentifrices brushed acrylic specimens (Plex-glass). The brushing time was 50 minutes (one year/17,800 cycles). Ten toothbrush bristles per group were removed. A group of ten unused bristles represented the control group. The bristles were placed on a Plex-glass dish so that they were all in the same plane. The diameter measurement was performed using a profilometer with a precision of tenths of millimeters (0.01 mm) to within 0.02 mm of the tip of the bristle. Ten values were obtained for each combination (toothbrush and toothpaste) tested. Results: Data analysis was performed using Anova Test (P <0.05). The results indicated that only the Sorriso group (Colgate-Palmolive Ind e Com. Ltda., Osasco, Brazil) (0.15 ± 0.02) compared with the control group (0.2 ± 0.02) was statistically significant (P = 0.0117), while the values of the other groups (Water: 0.18 ± 0.02; Corega (GSK - GlaxoSmithKline, Brasil Ltda., Rio de Janeiro, Brazil): 0.17 ± 0.2; Experimental 1: 0.16 ± 0.02; Experimental 2: 0.16 ± 0.02) showed no significant change. Conclusion: The Sorriso toothpaste (Colgate-Palmolive Ind e Com. Ltda., Osasco, Brazil), suitable for natural teeth, caused the biggest change on the tips of toothbrush bristles.

Objetivo: Avaliar a alteração nas cerdas de escovas dentais após escovação com água e quatro dentifrícios, sendo um para dentes naturais (Sorriso, Colgate-Palmolive Ind e Com. Ltda., Osasco, Brasil) e três para próteses totais: Corega (GSK - GlaxoSmithKline, Brasil Ltda., Rio de Janeiro, Brasil), Experimental 1 (Zonil), Experimental 2 (Cloramina T).Métodos: Foram utilizadas escovas macias com 26 tufos de cerdas de 0,25mm de diâmetro e 10 mm de altura. A escovação foi realizada em máquina do tipo Pepsodent, na qual as escovas associadas às suspensões dos dentifrícios escovaram corpos-de-prova de resina acrílica (Plex-glass) por um período de 50 minutos, simulando um ano (17800 ciclos). Foram removidas dez cerdas das escovas por grupo. Um grupo com dez cerdas não utilizadas representou o controle. As cerdas foram posicionadas em uma placa de Plex-glass de forma que ficassem todas em um mesmo plano. A aferição do diâmetro foi realizada em perfilômetro com precisão de décimos de milímetros (0,01 mm) a 0,02 mm da ponta da cerda. Foram obtidos dez valores para cada combinação (escova e dentifrício) testada. Resultados: A análise dos dados foi realizada por meio dos Testes ANOVA (p<0,05). Os resultados indicaram que apenas o grupo Sorriso (Colgate-Palmolive Ind e Com. Ltda., Osasco, Brasil) (0,15±0,02) quando comparado com o grupo controle (0,2±0,02) apresentou significância estatística (p=0,0117), enquanto os outros grupos (água: 0,18±0,02; Corega (GSK - GlaxoSmithKline, Brasil Ltda., Rio de Janeiro, Brasil): 0,17±0,2; Experimental 1: 0,16±0,02; Experimental 2: 0,16±0,02) não apresentaram valores de alteração significantes.Conclusão: O dentifrício Sorriso (Colgate-Palmolive Ind e Com. Ltda., Osasco, Brasil), indicado para dentes naturais, foi o que causou a maior alteração nas pontas das cerdas das escovas.