Color change of composite resins subjected to accelerated artificial aging.

AIM: The aim of this study was to evaluate the influence of accelerated artificial aging (AAA) on the color change of composite resins used in dentistry. MATERIALS AND METHODS: Three composite resins were evaluated: Two microhybrids and one hybrid of higher viscosity, with different amounts and sizes of filler particles, shades C2 and B2. A total of 54 specimens were obtained (18 for each composite resin), made of a Teflon matrix (15 mm in diameter and 2 mm in height). The color measurements were obtained with a Spectrophotometer, (PCB 6807 BYK Gardner) before and after AAA. Data were submitted to the Kolmogorov-Smirnov test (α >0.05), ANOVA and Tukey test (α <0.05). After statistical analysis, the color difference among composite resins with the same shades was analyzed. RESULTS: All composite resins showed unacceptable color changes after AAA (ΔE > 3). Considering the variable ∆E, it was observed that the color tone C2 was already statistically different for the microhybrid composite resin prior to AAA (P < 0.05) and in shade B2 for hybrid of higher viscosity and microhybrid with barium glass fluoride aluminum and silica dioxide (P < 0.01). After this process, a statistically significant difference was observed only for shade B2 between microhybrid composite resins (P < 0.01) and for hybrid of higher viscosity and microhybrid with barium glass fluoride aluminum and silica dioxide (P < 0.05). Regarding the color difference within a same composite resin group, before aging the composite resin hybrid of higher viscosity B2 showed the highest color variation rate and microhybrid with zirconium/silica C2 showed the lowest. CONCLUSIONS: All composite resins presented unacceptable color changes after 382 h of aging and different composite resins with same hue, presented different colors before being subjected to the aging process (B2 and C2) and after (B2). It was also observed color difference within a group of the same composite resin and same hue.

Drug-induced gingival overgrowth: a case report.

A variety of systemic drugs can lead to adverse effects in the oral environment. This article reports the case of a 61-year-old man who had a severe drug-induced gingival overgrowth (DIGO) caused by nifedipine. DIGO is relevant due to severe gingival enlargement, which causes disfigurement and blocks physiological and social functions such as mastication and speaking. Management of DIGO is always a challenge due to the patient's systemic condition. This article shows, step-by-step, how the treatment was executed and how the DIGO was reversed.

Evaluation of the flexural strength and elastic modulus of resins used for temporary restorations reinforced with particulate glass fibre.

OBJECTIVE: The flexural strength and the elastic modulus of acrylic resins, Dencor, Duralay and Trim Plus II, were evaluated with and without the addition of silanised glass fibre. MATERIALS AND METHODS: To evaluate the flexural strength and elastic modulus, 60 test specimens were fabricated with the addition of 10% ground silanised glass fibres for the experimental group, and 60 without the incorporation of fibres, for the control group, with 20 test specimens being made of each commercial brand of resin (Dencor, Duralay and Trim Plus II) for the control group and experimental group. After the test specimens had been completed, the flexural strength and elastic modulus tests were performed in a universal testing device, using the three-point bending test. For the specimens without fibres the One-Way Analysis of Variance and the complementary Tukey test were used, and for those with fibres it was not normal, so that the non-parametric Mann-Whitney test was applied. RESULTS: For the flexural strength test, there was no statistical difference (p > 0.05) between each commercial brand of resin without fibres [Duralay 84.32(±8.54), Trim plus 85.39(±6.74), Dencor 96.70(±6.52)] and with fibres (Duralay 87.18, Trim plus 88.33, Dencor 98.10). However, for the elastic modulus, there was statistical difference (p > 0.01) between each commercial brand of resin without fibres [Duralay 2380.64 (±168.60), Trim plus 2740.37(±311.74), Dencor 2595.42(±261.22)] and with fibres (Duralay 3750.42, Trim plus 3188.80, Dencor 3400.75). CONCLUSION: The result showed that the incorporation of fibre did not interfere in the flexural strength values, but it increased the values for the elastic modulus.

Assessment of antimicrobial effect of Biosilicate® against anaerobic, microaerophilic and facultative anaerobic microorganisms.

This study assessed the antimicrobial activity of a new bioactive glass-ceramic (Biosilicate®) against anaerobic, microaerophilic, and facultative anaerobic microorganisms. Evaluation of the antimicrobial activity was carried out by three methods, namely agar diffusion, direct contact, and minimal inhibitory concentration (MIC). For the agar diffusion technique, bio glass-ceramic activity was observed against various microorganisms, with inhibition haloes ranging from 9.0 ± 1.0 to 22.3 ± 2.1 mm. For the direct contact technique, Biosilicate® displayed activity against all the microorganisms, except for S. aureus. In the first 10 min of contact between the microorganisms and Biosilicate®, there was a drastic reduction in the number of viable cells. Confirming the latter results, MIC showed that the Biosilicate® inhibited the growth of microorganisms, with variations between ≤ 2.5 and 20 mg/ml. The lowest MIC values (7.5 to ≤ 2.5 mg/ml) were obtained for oral microorganisms. In conclusion, Biosilicate® exhibits a wide spectrum of antimicrobial properties, including anaerobic bacteria.

Evaluating an experimental dentifrice containing chloramine-T: a preliminary study.

PURPOSE: The aim of the present study was to evaluate the clinical efficacy of an experimental dentifrice (CH) containing an antimicrobial agent (1% chloramine-T). MATERIALS AND METHODS: A clinical, fully randomised, double-blind comparative study was designed for 30 selected patients aged 15 to 50 years, with no periodontal disease, decay or other oral diseases, good general health and the presence of dental plaque and sulcus bleeding. Baseline Turesky modified plaque index (PI) and sulcus bleeding index (SBI) were scored for all patients. Volunteers randomly received the experimental dentifrice (CH) or a commercial-brand dentifrice containing triclosan (TR). Both dentifrices were provided in identical, number-labelled tubes, and the subjects were instructed to use the supplied dentifrice only for their usual oral hygiene, three times a day for a duration of 7 days. After 7-day use of dentifrices, the PI and SBI were assessed again. The data obtained were subjected to the Kruskal­ Wallis test, followed by Dunn's post hoc test. RESULTS: After 7-day use of dentifrices, the PI scores diminished significantly for both evaluated dentifrices. The SBI values decreased significantly for both experimental and commercial-brand dentifrices. CONCLUSIONS: Both dentifrices reduced PI and SBI. By comparing the experimental and gold-standard dentifrice, it was found that there was no statistically significant difference between the PI and SBI scores after their use, suggesting that they exerted a similar effect on the oral health indexes.

A novel bioactive glass-ceramic for treating dentin hypersensitivity.

Dentin hypersensitivity (DH) is a painful response to stimulus applied to the open dentinal tubules of a vital tooth. It's a common oral condition, however, without an ideal treatment available yet. This work evaluated in vitro the effect of micron-sized particles from a novel bioactive glass-ceramic (Biosilicate) in occluding open dentinal tubules. A dentin disc model was employed to observe comparatively, using scanning electron microscopy (SEM), dentinal tubule occlusion by different products and deposition of hydroxyl carbonate apatite (HCA) on dentin surface by Biosilicate, after a single application: G1 - Dentifrice with potassium nitrate and fluoride; G2 - Two-step calcium phosphate precipitation treatment; G3 - Water-free gel containing Biosilicate particles (1%); G4 - Biosilicate particles mixed with distilled water in a 1:10 ratio; all of them after 1, 12 and 24 hours of immersion in artificial saliva. Fourier transform infrared spectroscopy (FTIR) was performed to detect HCA formation on dentin discs filled with Biosilicate after 2 minutes, 30 minutes and 12 hours of immersion in artificial saliva. SEM showed a layer of HCA formed on dentin surface after 24 hours by G4. G1, G2 and G3 promoted not total occlusion of open dentinal tubules after 24 hours. FTIR showed HCA precipitation on the dentin surface induced by Biosilicate after 30 minutes. The micron-sized particles from the bioactive glass-ceramic thus were able to induce HCA deposition in open dentinal tubules in vitro. This finding suggests that Biosilicate may provide a new option for treating DH.

A novel bioactive glass-ceramic for treating dentin hypersensitivity

Dentin hypersensitivity (DH) is a painful response to stimulus applied to the open dentinal tubules of a vital tooth. It's a common oral condition, however, without an ideal treatment available yet. This work evaluated in vitro the effect of micron-sized particles from a novel bioactive glass-ceramic (Biosilicate) in occluding open dentinal tubules. A dentin disc model was employed to observe comparatively, using scanning electron microscopy (SEM), dentinal tubule occlusion by different products and deposition of hydroxyl carbonate apatite (HCA) on dentin surface by Biosilicate, after a single application: G1 - Dentifrice with potassium nitrate and fluoride; G2 - Two-step calcium phosphate precipitation treatment; G3 - Water-free gel containing Biosilicate particles (1 percent); G4 - Biosilicate particles mixed with distilled water in a 1:10 ratio; all of them after 1, 12 and 24 hours of immersion in artificial saliva. Fourier transform infrared spectroscopy (FTIR) was performed to detect HCA formation on dentin discs filled with Biosilicate after 2 minutes, 30 minutes and 12 hours of immersion in artificial saliva. SEM showed a layer of HCA formed on dentin surface after 24 hours by G4. G1, G2 and G3 promoted not total occlusion of open dentinal tubules after 24 hours. FTIR showed HCA precipitation on the dentin surface induced by Biosilicate after 30 minutes. The micron-sized particles from the bioactive glass-ceramic thus were able to induce HCA deposition in open dentinal tubules in vitro. This finding suggests that Biosilicate may provide a new option for treating DH.

Evaluation of the abrasiveness of dentifrices for complete dentures.

PURPOSE: This study analyzed the surface roughness and weight loss in Plex Glass specimens caused by dentifrices, one conventional (Sorriso) and three specific for dentures. MATERIALS AND METHODS: Specimens (n = 6) of Plex Glass were divided into 5 groups including: negative control (water); positive control 1 (Sorriso) and 2 (Corega Brite); Experimental 1 (containing Chloramine T, antimicrobial agent); and Experimental 2 (containing Zonyl, detergent). Brushing was performed in a toothbrushing machine (Pepsodent) with a soft brush and a suspension of toothpaste and distilled water for 300 minutes, representing 6 years of brushing. Weight was measured initially and after the trial period; roughness was measured after the trial period only. The results of roughness and weight loss were analyzed using ANOVA and Tukey tests at 5%. RESULTS: The negative control (2.82 +/- 4.41 mg) showed the lowest weight loss. Experimental 1 (13.62 +/- 4.29 mg) and Experimental 2 (15.4 +/- 5.80 mg) were equal statistically, and Sorriso (23.22 +/- 7.23 mg) and Corega (28.83 +/- 6.34 mg) produced the greatest weight loss. Concerning roughness, the negative control group (0.03 +/- 0.01 microm) showed the lowest value. No significant differences were found between Corega (13.43 +/- 1.65 microm), Experimental 1 (12.28 +/- 0.85 microm), and Experimental 2 (10.68 +/- 2.56 microm). The Sorriso toothpaste produced the greatest amount of surface roughness (19.15 +/- 2.36 microm). CONCLUSION: Of the tested dentifrices, the experimental preparations proved to be the least abrasive and resulted in the lowest weight loss after brushing of the acrylic. Based on these findings, the use of these experimental dentifrices is advocated. Further evaluation based on the ability of these preparations to remove biofilms is required.

Efficacy of a bioactive glass-ceramic (Biosilicate) in the maintenance of alveolar ridges and in osseointegration of titanium implants.

OBJECTIVES: The aims of this research were to evaluate the efficacy of a bioactive glass-ceramic (Biosilicate) and a bioactive glass (Biogran) placed in dental sockets in the maintenance of alveolar ridge and in the osseointegration of Ti implants. MATERIAL AND METHODS: Six dogs had their low premolars extracted and the sockets were implanted with Biosilicate, Biogran particles, or left untreated. After the extractions, measurements of width and height on the alveolar ridge were taken. After 12 weeks a new surgery was performed to take the final ridge measurements and to insert bilaterally three Ti implants in biomaterial-implanted and control sites. Eight weeks post-Ti implant placement block biopsies were processed for histological and histomorphometric analysis. The percentages of bone-implant contact (BIC), of mineralized bone area between threads (BABT), and of mineralized bone area within the mirror area (BAMA) were determined. RESULTS: The presence of Biosilicate or Biogran particles preserved alveolar ridge height without affecting its width. No significant differences in terms of BIC, BAMA, and BABT values were detected among Biosilicate, Biogran, and the non-implanted group. CONCLUSIONS: The results of the present study indicate that filling of sockets with either Biosilicate or Biogran particles preserves alveolar bone ridge height and allows osseointegration of Ti implants.

A influência da disposição das cerdas de escovas dentais manuais na remoção de placa dental / The influence of manual toothbrush bristle arrangement on dental plaque removal

This crossover study aimed to compare plaque removal efficiency of two manual toothbrushes with identical design, the exception being the pattern of bristle arrangement. Twenty-six subjects were selected following inclusion and exclusion criteria. Dental plaque was scored before and after seven days of use of each toothbrush (Sanifill Smooth® – T1 andSanifill Active Smooth® – T2) employing the Turesky Plaque Index. Plaque Index values were handled with parametrical statistics employing Analysis of Variance (p<0.05) and, later, the Tukey Test. At the end of the trial, each subject was asked which toothbrush they preferred. Results: plaque scores for toothbrush T1 were not statistically different from those for toothbrush T2. Subjects showed a distinct preference for toothbrush T1. Conclusion: there was no differencein terms of plaque removal when toothbrushes T1 and T2 were compared, although patients showed a higher preference for toothbrush T1. Thus the different toothbrushes bristles arrangements did not influence the dental plaque removal.

Este estudo cruzado se propôs a comparar a eficiência de remoção de placa dental de duas escovas manuais com modelos idênticos, exceto para o padrão da disposição das cerdas. Vinte e seis sujeitos foram selecionados de acordo com critérios de inclusão e exclusão. Placa dental foi mensurada antes e após sete dias de uso com cada uma das escovas (Sanifill Smooth® – T1 and Sanifill Active Smooth® – T2) utilizando-se o Índice de Placa de Turesky. No final do estudo, cada paciente foi questionado sobre qual a escova preferida. Os valores do Índice de Placa para T1 não foram estatisticamente diferentes para os da escova T2. Não houve diferença em termos de remoção de placa quando as escovas T1 e T2 foram comparadas, embora os pacientes tenham demonstrado grande preferência pela escova T1. Assim, as diferenças nas disposições das cerdas das escovas dentais manuais não influenciaram na remoção de placa dental.

In vitro fluoride release and tensile bond Strength of a polymeric intra-buccal bioadhesive / Liberación in vitro de flúor y fuerza de tracción de un bioadhesivo polimérico intra-bucal

The intra-buccal polymeric bioadhesive systems that can stay adhered to the oral soft tissues for drug programmed release, with the preventive and/or therapeutic purpose has been employed for large clinical situations. A system based on hydroxypropyl methyl cellulose/Carbopol 934'/magnesium stearate (HPMC/Cp/StMg) was developed having the sodium fluoride as active principle. This kind of system was evaluated according to its resistance to the removal by means of physical test of tensile strength. Swine buccal mucosa extracted immediately after animals' sacrifice was employed as substrate for the physical trials, to obtain 16 test bodies. Artificial saliva with or without mucin was used to involve the substrate/bioadhesive system sets during the trials. Artificial salivas viscosity was determined by means of Brookfield viscometer, showing the artificial saliva with mucin 10.0 cP, and the artificial saliva without mucin 7.5 cP. The tensile strength assays showed the following averages: for the group "artificial saliva with mucin" - 12.89 Pa, and for the group "without mucin" - 12.35 Pa. Statistical analysis showed no significant difference between the assays for both artificial salivas, and it was possible to conclude that the variable mucin did not interfered with the bioadhesion process for the polymeric devices. The device was able to release fluoride in a safe, efficient and constant way up to 8 hours.

Los sistemas bioadhesivos poliméricos intra-bucales pueden permanecer adheridos a los tejidos blandos orales para una liberación programada de fármacos, con finalidad preventiva y/o propósito terapéutico han sido empleados en diversas situaciones clínicas. Un sistema basado en Hidroxipropilmetilcelulosa/Carbopol934Ô/ estearato de magnesio (HPMC/Cp/StMg) fue desarrollado con fluorato de sodio como principio activo. Este tipo de sistema fue evaluado de acuerdo a su resistencia a la eliminación física por medio de pruebas de resistencia a la tracción. Mucosas bucales de cerdos fueron tomadas inmediatamente después del sacrificio de los animales y se utilizaron como sustrato para las pruebas físicas, obteniendo 16 cuerpos de prueba. Saliva artificial con o sin mucina fue utilizada para participar como parte del sistema sustrato/bioadesivo durante los ensayos. La viscosidad de la saliva artificial, se determinó mediante un viscosímetro Brookfield, mostrando la saliva artificial con mucina 10,0 cP y saliva artificial sin mucina 7,5 cP. Las pruebas de resistencia a la tracción mostraron los siguientes promedios: para la "saliva artificial con mucina" - 12,89 Pa, y para el grupo "sin mucina" - 12,35 Pa. El análisis estadístico no mostró diferencias significativas entre las pruebas de saliva artificial, y es posible concluir que la variable de mucina no interfiere con el proceso de bioadhesión del dispositivo polimérico. El dispositivo fue capaz de liberar fluor de forma segura, eficiente y constante durante un máximo de hasta 8 horas.

In vitro and clinical evaluation of specific dentifrices for complete denture hygiene.

OBJECTIVES: To study the physical properties of two experimental dentifrices for complete denture hygiene, their effect on denture biofilm removal and antimicrobial properties by means of a clinical trial. MATERIALS AND METHODS: The experimental dentifrices comprised two compositions. One was based on the addition of 1% chloramine T (D1) and the other on the presence of 0.01% fluorosurfactant (D2). Measurements of density, pH, consistency, rheological features and abrasiveness were conducted. Sixty complete denture wearers were randomly assigned to three groups and were instructed to brush their dentures with a specific toothbrush: (1) Water (control); (2) D1; or (3) D2. Each method was used for 21 days. Denture biofilm was disclosed by a 1% neutral red solution and quantified by means of digital photos taken from the internal surface. Microbiological assessment was conducted to quantify Candida sp. and mutans streptococci. Data were evaluated by one-way anova and Tukey HSD, or Kruskal-Wallis (alpha = 0.05). RESULTS: Both dentifrices decreased biofilm coverage when compared with the control group. D1 was the most efficacious treatment to reduce mutans streptococci, whereas D2 showed an intermediate outcome (ANOVA, p < 0.040). No treatment influenced Candida albicans or non-albicans species (Kruskal-Wallis, p = 0.163 and 0.746, respectively). CONCLUSION: It can be concluded that brushing complete dentures with the experimental dentifrices tested could be effective for the removal of denture biofilm.

Effectiveness of a new toothbrush design versus a conventional tongue scraper in improving breath odor and reducing tongue microbiota.

For centuries, specific instruments or regular toothbrushes have routinely been used to remove tongue biofilm and improve breath odor. Toothbrushes with a tongue scraper on the back of their head have recently been introduced to the market. The present study compared the effectiveness of a manual toothbrush with this new design, i.e., possessing a tongue scraper, and a commercial tongue scraper in improving breath odor and reducing the aerobic and anaerobic microbiota of tongue surface. The evaluations occurred at 4 moments, when the participants (n=30) had their halitosis quantified with a halimeter and scored according to a 4-point scoring system corresponding to different levels of intensity. Saliva was collected for counts of aerobic and anaerobic microorganisms. Data were analyzed statistically by Friedman's test (p<0.05). When differences were detected, the Wilcoxon test adjusted for Bonferroni correction was used for multiple comparisons (group to group). The results confirmed the importance of mechanical cleaning of the tongue, since this procedure provided an improvement in halitosis and reduction of aerobe and anaerobe counts. Regarding the evaluated methods, the toothbrush's tongue scraper and conventional tongue scraper had a similar performance in terms of breath improvement and reduction of tongue microbiota, and may be indicated as effective methods for tongue cleaning.

Effectiveness of a new toothbrush design versus a conventional tongue scraper in improving breath odor and reducing tongue microbiota

For centuries, specific instruments or regular toothbrushes have routinely been used to remove tongue biofilm and improve breath odor. Toothbrushes with a tongue scraper on the back of their head have recently been introduced to the market. The present study compared the effectiveness of a manual toothbrush with this new design, i.e., possessing a tongue scraper, and a commercial tongue scraper in improving breath odor and reducing the aerobic and anaerobic microbiota of tongue surface. The evaluations occurred at 4 moments, when the participants (n=30) had their halitosis quantified with a halimeter and scored according to a 4-point scoring system corresponding to different levels of intensity. Saliva was collected for counts of aerobic and anaerobic microorganisms. Data were analyzed statistically by Friedman's test (p<0.05). When differences were detected, the Wilcoxon test adjusted for Bonferroni correction was used for multiple comparisons (group to group). The results confirmed the importance of mechanical cleaning of the tongue, since this procedure provided an improvement in halitosis and reduction of aerobe and anaerobe counts. Regarding the evaluated methods, the toothbrush's tongue scraper and conventional tongue scraper had a similar performance in terms of breath improvement and reduction of tongue microbiota, and may be indicated as effective methods for tongue cleaning.

Assessment in vitro of brushing on dental surface roughness alteration by laser interferometry.

Noncarious cervical lesions (NCCLs) are considered to be of multifactorial origin, normally associated with inadequate brushing. This study assessed the influence in vitro of simulated brushing on NCCL formation. Fifteen human premolars were submitted to brushing in the cementoenamel junction region, using hard-, medium- and soft-bristled brushes associated with a toothpaste of medium abrasiveness under a 200 g load, at a speed of 356 rpm for 100 minutes. The surface topography of the region was analyzed before and after brushing, by means of a laser interferometer, using "cut-off" values of 0.25 and considering roughness values in mm. The initial roughness (mm) results for dentin (D / bristle consistency: 1--soft, 2--medium and 3--hard) were as follows: (D1) 1.25 +/- 0.45; (D2) 1.12 +/- 0.44; (D3) 1.05 +/- 0.41. For enamel (E / bristle consistency: 1--soft, 2--medium and 3--hard), the initial results were: (E1) 1.18 +/- 0.35; (E2) 1.32 +/- 0.25; (E3) 1.50 +/- 0.38. After brushing, the following were the values for dentin: (D1) 2.32 +/- 1.99; (D2) 3.30 +/- 0.96; (D3) Over 500. For enamel, the values after brushing were: (E1) 1.37 +/- 0.31; (E2) 2.15 +/- 0.90; (E3) 1.22 +/- 0.47. Based on the results of the ANOVA and Tukey statistical analyses (a = .05) it was concluded that soft, medium and hard brushes are not capable of abrading enamel, whereas dentin showed changes in surface roughness by the action of medium- and hard-bristled brushes.

Precursor system of liquid crystalline phase containing propolis microparticles for the treatment of periodontal disease: development and characterization.

Precursor systems of liquid crystalline phase were prepared using the surfactant PPG-5-Ceteth-20, isopropyl myristate, and water; gelatin microparticles containing propolis were then added into these systems. Homogeneity of dispersion, the in-system microparticle morphology, and sedimentation behavior of each formulation were evaluated. The rheological and mechanical properties (hardness, compressibility, and adhesiveness), the work of syringing, and the propolis release profile were also evaluated. All the formulations exhibited pseudoplastic flow and thixotropy, and they displayed storage modulus, loss modulus, dynamic viscosity, and loss tangent that depended on temperature, frequency, and composition. Mechanical properties varied significantly among the formulations being affected by changes in the composition and temperature. Raising the concentration of surfactant and adding propolis microparticles significantly decreased the work of syringing. The drug release was non-Fickian (anomalous) and there was no significant difference between the tested systems in the times required for 10%, 30%, and 50% release of the initial drug loading.

Assessment in vitro of brushing on dental surface roughness alteration by laser interferometry

Noncarious cervical lesions (NCCLs) are considered to be of multifactorial origin, normally associated with inadequate brushing. This study assessed the influence in vitro of simulated brushing on NCCL formation. Fifteen human premolars were submitted to brushing in the cementoenamel junction region, using hard-, medium- and soft-bristled brushes associated with a toothpaste of medium abrasiveness under a 200 g load, at a speed of 356 rpm for 100 minutes. The surface topography of the region was analyzed before and after brushing, by means of a laser interferometer, using "cut-off" values of 0.25 and considering roughness values in mm. The initial roughness (mm) results for dentin (D / bristle consistency: 1 - soft, 2 - medium and 3 - hard) were as follows: (D1) 1.25 ± 0.45; (D2) 1.12 ± 0.44; (D3) 1.05 ± 0.41. For enamel (E / bristle consistency: 1 - soft, 2 - medium and 3 - hard), the initial results were: (E1) 1.18 ± 0.35; (E2) 1.32 ± 0.25; (E3) 1.50 ± 0.38. After brushing, the following were the values for dentin: (D1) 2.32 ± 1.99; (D2) 3.30 ± 0.96; (D3) Over 500. For enamel, the values after brushing were: (E1) 1.37 ± 0.31; (E2) 2.15 ± 0.90; (E3) 1.22 ± 0.47. Based on the results of the ANOVA and Tukey statistical analyses (a = .05) it was concluded that soft, medium and hard brushes are not capable of abrading enamel, whereas dentin showed changes in surface roughness by the action of medium- and hard-bristled brushes.

Antimicrobial and mechanical properties of acrylic resins with incorporated silver-zinc zeolite - part I.

OBJECTIVE: The purpose of this in vitro study was to evaluate the antimicrobial activity of acrylic resins containing different percentages of silver and zinc zeolite, and to assess whether the addition of zeolite alters the flexural and impact strength of the resins. BACKGROUND: The characteristics of acrylic resins support microorganism development that can threaten the health of the dentures user. MATERIAL AND METHODS: A microwave-polymerised (Onda-Cryl) and two heat-polymerised (QC20 and Lucitone 550) acrylic resins were used. The materials were handled according to the manufacturers' instructions. Fifty rectangular-shaped specimens (8 x 10 x 4mm) were fabricated from each resin and assigned to 5 groups (n = 10) according to their percentage of Irgaguard B5000 silver-zinc zeolite (0%- control, 2.5%, 5.0%, 7.5% and 10%). Flexural strength and Izod impact strength were evaluated. The antimicrobial activity against two strains of Candida albicans and two strains of Streptococcus mutans was assessed by agar diffusion method. Data were analysed statistically by one-way anova and Tukey's test at 5% significance level. RESULTS: The addition of 2.5% of Irgaguard B5000 to the materials resulted in antimicrobial activity against all strains. Flexural strength decreased significantly with the addition of 2.5% (QC20 and Lucitone 550) and 5.0% (Onda-Cryl) of Irgaguard B5000. The impact strength decreased significantly with the addition of 2.5% (Lucitone 550) and 5.0% (QC20 and Onda-Cryl) of zeolite. CONCLUSION: The addition of silver-zinc zeolite to acrylic resins yields antimicrobial activity, but may affect negatively the mechanical properties, depending on the percentage of zeolite.

In vitro antimicrobial activity of irreversible hydrocolloid impressions against 12 oral microorganisms.

This study evaluated in vitro the antimicrobial activity of irreversible hydrocolloids (one containing an antimicrobial agent) prepared with water or with a 0.2% chlorhexidine digluconate solution against 12 strains of the oral microbiota. Twenty specimens (0.5x1.0 cm) for each group (1. Jeltrate mixed with water; 2. Jeltrate mixed with 0.2% chlorhexidine digluconate solution; 3. Greengel mixed with water; 4. Greengel mixed with 0.2% chlorhexidine digluconate solution) were prepared under sterile conditions and placed in culture media inoculated with the indicator strains. After incubation in aerobiosis or microaerophilia, inhibition of the microbial growth was measured and the results were interpreted. The normal adherence curve revealed a non-normal distribution of the data, so the non-parametric Friedman Test was performed (p<0.05). The antimicrobial activity of the groups was classified in the following order: 1, 3, 4, and 2. The results suggest that the method of preparing irreversible hydrocolloids with a 0.2% digluconate chlorhexidine solution is more effective than the incorporation of an antimicrobial agent in the powder to reduce cross-contamination caused by impressions.

Análise da capacidade de reprodução de detalhes expressa por diferentes materiais de modelagem / Analysis of the capacity to reproduce details expressed by different modeling materials

Este estudo objetivou avaliar a capacidade de reprodução de detalhes presentes no molde por materiais de modelagem à base de gipsita Gesso pedra tipo IV, Durone, (Dentsply); Gesso pedra tipo IV, Fuji Rock EP,(GC); Gesso pedra tipo IV, Resinado Rock Plus, (Polidental); Gesso pedra tipo V, Durone, (Dentsply) epolímeros: resinas epóxicas Epoxiglass 1504, (Epoxiglass), resina epóxica Epoxiglass 1504 modificada com diatomita pura e silanizada. A resina e seu endurecedor foram carregados com diatomita numa relação de30%. A diatomita foi tratada com Silano Silquest A 187, (Crompton S/A). A resina modificada foi manipuladaem uma relação de 35%. Empregando-se silicona de adição Presidente (Kit de silicona leve e pesada, Coltène) realizaram-se três moldagens de uma matriz metálica com quatro hastes contendo sulcos dimensionados. Os corpos de prova foram analisados em microscópio óptico com aumento de 40 vezes (Measurescope Nikon, procedência Nippon Kogaru K. K.). Os resultados expressos por gessos e resinas foram analisados com o teste Variância e Tukey (p<0,05). Verificou-se que não há diferenças estatisticamente significantes entre os gessos e resinas analisadas. Concluiu-se que o carregamento da resina epóxica com diatomita ou com diatomita silanizada não reduz a sua capacidade em reproduzir detalhes presentes no molde. Com a metodologia empregada, não houve diferença entre gessos tipo IV e V e resina epóxica pura ou modificada com diatomita na capacidadede reprodução de detalhes presentes no molde.