Colour stability of temporary restorations with different thicknesses submitted to artificial accelerated aging

This study evaluated the colour stability of temporary prosthetic restorations with different thicknesses submitted to artificial accelerated aging. The occlusal surfaces of 40 molars were grinded to obtain flat enamel surfaces. Twenty acrylic resin specimens [Polymethyl methacrylate (Duralay) and Bis-methyl acrylate (Luxatemp)] were made with two different thicknesses, 0.5 mm and 1.0 mm. Temporary restorations were fixed on enamel and CIE L*a*b* colour parameters of each specimen were assessed before and after artificial accelerated aging. All groups showed colour alterations above the clinically acceptable limit. Luxatemp showed the lowest colour alteration regardless its thickness and Duralay showed the greatest alteration with 0.5 mm.

Effect of cigarette smoke on color stability and surface roughness of dental composites

OBJECTIVE

To evaluate the color stability and surface roughness of 3 dental composites subjected to cigarette smoke and brushing.

METHODS

Twenty specimens were prepared for each type of restorative material used: nanohybrid (Tetric N-Ceram); hybrid (Z250-3M ESPE) and silorane-based microhybrid (Filtek P90-3M ESPE), which were divided into 2 groups (n=10), according to the type of finishing/polishing received: Group 1 - papers with decreasing abrasive grit and Group 2 - polyester matrix (without polishing). After initial readouts of color (Easy Shade-VITA) and surface roughness (SJ-201P Mitutoyo), specimens were subjected to action of smoke from 20 cigarettes, (Marlboro Red-Philip Morris). After each cigarette, the samples were submitted to brushing in a standardised device. After this, final readouts were taken to calculate change in color (ΔE and ΔL) and roughness (ΔRa), which were statistically analysed (2-way ANOVA, Bonferroni, and Student's-t tests respectively, p<0.05).

RESULTS

Tetric N-Ceram presented color change at clinically unacceptable levels (ΔE>3.3) when the polyester strip was used for finishing, a result differing (p<0.05) from those of the other composites, which presented no difference between them (p>0.05). Unpolished composites presented higher Ra values than those that were polished (p<0.05), with exception of the silorane based composite.

CONCLUSION

Absence of polishing increases cigarette capacity to stain composites and surface roughness of composites, with exception of the silorane based type.

Bacterial survival rate on toothbrushes and their decontamination with antimicrobial solutions

The purpose of this study was to evaluate bacterial survival rate on toothbrushes after brushing and the efficacy of their decontamination by spraying antimicrobial solutions. Thirty subjects were instructed to spray the solutions on toothbrush bristles after brushing. Each volunteer tested three sprays, one solution per week; the sprays were labeled spray 1 (cetylpyridinium chloride - CPC - and basic formulation), 2 (basic formulation only) and 3 (control - sterile tap water). At the end of each week, the brushes were collected and sonicated in Letheen Broth®; the suspensions were ten-fold diluted and the dilutions were plated on various culture media. Anaerobic bacteria, evaluated by colony count of black pigment producing organisms on Ask medium, were recovered from 83.3% of the samples, Streptococci from 80% and aerobic Gram-negative bacilli from 46.7% of them in the control tests. There was a significant decrease in toothbrush contamination with antimicrobial sprays 1 and 2, the first showing the greatest decrease on bacterial counts.

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.

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.

A influência da disposição das cerdas de escovas dentais manuais na remoção de placa dental

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.

Influência da temperatura de sinterização sobre a rugosidade superficial de três porcelanas odontológicas

O objetivo do presente trabalho foi verificar a influência da variação da temperatura de sinterização na rugosidade superficial em três sistemas de porcelana odontológica. Noventa amostras de porcelana dos sistemas VITA VMK-68, IPS CLASSIC e WILLIAMS foram empregados a três diferentes temperaturas de sinterização: temperatura recomendada pelos fabricantes (R); temperatura 20oC acima (+20oC) e 20oC abaixo da recomendada (- 20oC). Para a observação da rugosidade superficial dos corpos de prova das porcelanas foi utilizado um rugosímetro digital (PRAZIS - RUG 03), realizando seis leituras em cada espécime. Considerando as comparações entre as médias de rugosidade medidas nos três níveis de temperatura a que foram submetidas os três sistemas de porcelana, a rugosidade com a temperatura -20°C foi significativamente mais elevada do que a verificada com a temperatura recomendada e a +20°C, e que a rugosidade obtida com a temperatura recomendada foi também significativamente mais elevada do que a obtida a temperatura +20°C. Isto indica que a temperatura +20°C foi a que se associou com menor índice de rugosidade, independentemente do tipo de porcelana. Pequenas variações na temperatura de sinterização das porcelanas odontológicas resultam em diferentes graus de rugosidade superficial. Os profissionais envolvidos na confecção das restaurações que utilizam porcelanas feldspáticas devem, periodicamente, aferir a temperatura dos fornos utilizados na sinterização, a fim de evitar alterações indesejáveis na sua lisura superficial.

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.

Desensitizing bioactive agents improves bond strength of indirect resin-cemented restorations: preliminary results

Objective:

The aim of this study was to assess the bond strength of indirect composite restorations cemented with a resin-based cement associated with etch-and-rinse and self-etching primer adhesive systems to dentin treated or not with a bioactive material.

Materials and Method:

Twenty bovine incisor crowns had the buccal enamel removed and the dentin ground flat. The teeth were assigned to 4 groups (n=5): Group I: acid etching + Prime & Bond NT (Dentsply); Group II: application of a bioactive glass (Biosilicato®)+ acid etching + Prime & Bond NT; Group III: One-up Bond F (J Morita); Group IV: Biosilicato® + One-up Bond F. Indirect composite resin (Artglass, Kulzer) cylinders (6x10mm) were fabricated and cemented to the teeth with a dualcure resin-based cement (Enforce, Dentsply). After cementation, the specimens were stored in artificial saliva at 37^oC for 30 days and thereafter tested in tensile strength in a universal testing machine (EMIC) with 50 kgf load cell at a crosshead speed of 1 mm/min. Failure modes were assessed under scanning electron microscopy. Data were analyzed statistically by ANOVA and Tukey's test (95% level of confidence).

Results:

Groups I, II and III had statistically similar results (p>0.05). Group IV had statistically significant higher bond strength means (p<0.05) than the other groups. The analysis of the debonded surfaces showed a predominance of adhesive failure mode for Group III and mixed failure mode for the other groups.

Conclusion:

The use of desensitizing agent did not affect negatively the bonding of the indirect composite restorations to dentin, independently of the tested adhesive systems.

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.

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.

Shear-bond strength between a new format of intra-buccal acrylic bioadhesive drug delivery system and adhesive systems

AIM

An intra-buccal acrylic bioadhesive device designated for drug programmed release that can stay adhered to dental enamel, and also on removable prosthetic restorations, with preventive and/or therapeutic purpose for a large clinical applications based on polymethyl methacrylate/methyl methacrylate/2 hydroxyethyl methacrylate (PMMA/MMA/HEMA) was developed, using the sodium fluoride as an active principle. This bioadhesive was evaluated for its shear bond strength when bonded with different adhesive systems.

METHODS

Two substrates (recently extracted human teeth and acrylic prosthesis basis) were used to obtain the 96 test-specimens. Four adhesive systems (Cyanoacrylate ester, 3M Concise Enamel Bond Resin with or without previous enamel etching, MMA/HEMA or PMMA/MMA/ HEMA) were chosen for the fixation of the bioadhesives to substrate. Artificial saliva or distilled water was used as medium for maintaining the specimens until test.

RESULTS

Statistical analysis showed that the interaction bioadhesives/acrylic prosthesis basis/cyanoacrylate ester adhesive was the most resistant to the physical removal by shearing.

CONCLUSION

The newly rounded semi-convex format of acrylic device developed in this study presented satisfactory shear bond strength and might contribute to the comfort of intra-buccal use.

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.

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.

Preparation and Antimicrobial Activityof Gelatin Microparticles Containing Propolis Against Oral Pathogens

Gelatin microparticles containing propolis ethanolic extractive solution were prepared by spray-drying technique. Particles with regular morphology, mean diameter ranging of 2.27 microm to 2.48 microm, and good entrapment efficiency for propolis were obtained. The in vitro antimicrobial activity of microparticles was evaluated against microorganisms of oral importance (Enterococcus faecalis, Streptococcus salivarius, Streptococcus sanguinis, Streptococcus mitis, Streptococcus mutans, Streptococcus sobrinus, Candida albicans, and Lactobacillus casei). The utilized techniques were diffusion in agar and determination of minimum inhibitory concentration. The choice of the method to evaluate the antimicrobial activity of microparticles showed be very important. The microparticles displayed activity against all tested strains of similar way to the propolis, showing greater activity against the strains of E. salivarius, S. sanguinis, S. mitis, and C. albicans.

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.

Semisolid systems containing propolis for the treatment of periodontal disease: in vitro release kinetics, syringeability, rheological, textural, and mucoadhesive properties

Formulations containing poloxamer 407 (P407), carbopol 934P (C934P), and propolis extract (PE) were designed for the treatment of periodontal disease. Gelation temperature, in vitro drug release, rheology, hardness, compressibility, adhesiveness, mucoadhesion, and syringeability of formulations were determined. Propolis release from formulations was controlled by the phenomenon of relaxation of polymer chains. Formulations exhibited pseudoplastic flow and low degrees of thixotropy or rheopexy. In most samples, increasing the concentration of C934P content significantly increased storage modulus (G'), loss modulus (G''), and dynamic viscosity (eta'), at 5 degrees C, G'' exceeded G'. At 25 and 37 degrees C, eta' of each formulation depended on the oscillatory frequency. Formulations showed thermoresponsive behavior, existing as a liquid at room temperature and gel at 34-37 degrees C. Increasing the C934P content or temperature significantly increased formulation hardness, compressibility, and adhesiveness. The greatest mucoadhesion was noted in the formulation containing 15% P407 (w/w) and 0.25% C934P (w/w). The work of syringeability values of all formulations were similar and very desirable with regard to ease of administration. The data obtained in these formulations indicate a potentially useful role in the treatment of periodontitis and suggest they are worthy of clinical evaluation.

Evaluation of Fluorescence of Dental Composites Using Contrast Ratios to Adjacent Tooth Structure: A Pilot Study

STATEMENT OF THE PROBLEM

Fluorescence is an optical signal that is present in natural teeth and some dental restorative materials as a consequence of its molecules energetic decrease. Restorative materials need to match the fluorescence properties of surrounding tooth structure to achieve the best esthetics and appear undetectable.

PURPOSE

The fluorescence of 10 commercial composites (shade A2 or equivalent) was tested against that of tooth structure using contrast differences.

MATERIALS AND METHODS

Thirty-three standard preparations (3.0-mm wide and 2.00-mm depth) were done on mean maxillaries incisors and divided into 10 groups containing three test samples each. High-definition images of the restored areas and adjacent tooth structure were obtained both under white light of the visible spectrum (control) and ultraviolet light (UV-A=300/ 400 nm). The contrast between composites and tooth structure, expressed in absolute values, was analyzed through digital processing Matlab and Origin softwares and by one-way analysis of variance and Tukey's test (p<or= 0.05; statistical differences between groups*).

RESULTS

Based on mean values, the composites were ranked in four groups, according to least fluorescence contrast with tooth structure: (Esthet-X [YE]=Esthet-X [A2]=TPH Spectrum [A2]) < (TPH Spectrum [A2] <or= Esthet x [A20]=Fill Magic [A2]) < (Charisma [A2]=Filtek Supreme [A2B]) < (Filtek Supreme [A2E] =Z250 [A2]=Z100 [A2]).

CONCLUSION

There is a considerable variation of fluorescence between the composites and the natural tooth structure. CLINICAL SIGNIFICANCE Ideal restorative materials should have fluorescence similar to that of natural teeth. Therefore, it is important to select a composite that possesses adequate fluorescence.

Bacterial, fungal and yeast contamination in six brands of irreversible hydrocolloid impression materials

This study assessed the level of contamination of six commercially available irreversible hydrocolloids (two containing chlorhexidine) and identified the contamination present in the materials. Petri dishes containing selective and enriched culture media were inoculated with alginate powder (0.06 g), in triplicate. After incubation (37 degrees C/7 days), the colony-forming units (CFU) were counted and Gram stained. Biochemical identification of the different morphotypes was also performed. The contamination levels for the materials were: Jeltrate--389 CFU/g; Jeltrate Plus--516 CFU/g; Jeltrate Chromatic--135 CFU/g; Hydrogum--1,455 CFU/g; Kromopan--840 CFU/g; and Greengel--59 CFU/g. Gram staining revealed the presence of Gram-positive bacillus and Gram-positive cocci. The bacteria Staphylococcus epidermidis, Bacillus subtilis, Bacillus sp., Bacillus coagulans, Bacillus licheniformis, Bacillus cereus, Micrococcus luteus, and Nocardia sp.; the filamentous fungi Aspergillus niger, Aspergillus flavus, Rhizopus sp., Neurospora sp.; and the yeast Candida sp. were isolated. The contamination detected in the impression materials points out the need for adopting measures to improve the microbiological quality of these materials. The use of contaminated materials in the oral cavity goes against the basic principles for controlling cross-contamination and may represent a risk for debilitated or immunocompromised patients.

In vitro osteogenesis on a highly bioactive glass-ceramic (Biosilicate®)

One of the strategies to improve the mechanical performance of bioactive glasses for load-bearing implant devices has been the development of glass-ceramic materials. The present study aimed to evaluate the effect of a highly bioactive, fully-crystallized glass-ceramic (Biosilicate) of the system P(2)O(5)-Na(2)O-CaO-SiO(2) on various key parameters of in vitro osteogenesis. Surface characterization was carried out by scanning electron microscopy and Fourier transform infrared spectroscopy. Osteogenic cells were obtained by enzymatic digestion of newborn rat calvarial bone and by growing on Biosilicate discs and on control bioactive glass surfaces (Biosilicate) parent glass and Bioglass(R) 45S5) for periods of up to 17 days. All materials developed an apatite layer in simulated body fluid for 24h. Additionally, as early as 12 h under culture conditions and in the absence of cells, all surfaces developed a layer of silica-gel that was gradually covered by amorphous calcium phosphate deposits, which remained amorphous up to 72 h. During the proliferative phase of osteogenic cultures, the majority of cells exhibited disassembly of the actin cytoskeleton, whereas reassembly of actin stress fibers took place only in areas of cell multilayering by day 5. Although no significant differences were detected in terms of total protein content and alkaline phosphatase activity at days 11 and 17, Biosilicate supported significantly larger areas of calcified matrix at day 17. The results indicate that full crystallization of bioactive glasses in a range of compositions of the system P(2)O(5)-Na(2)O-CaO-SiO(2) may promote enhancement of in vitro bone-like tissue formation in an osteogenic cell culture system.

Dental plaque removal efficacy of three toothbrushes with different designs: A comparative analysis

PURPOSE

This study aimed to compare dental plaque removal efficacy of three manual toothbrushes.

MATERIALS AND METHODS

Three toothbrushes (Colgate Flexível - Colgate (T1), Oral B Advantage Control Grip - Oral B (T2), Comfort Clean - Johnson & Johnson - Reach (T3) were evaluated for dental plaque removal in 17 subjects. Dental plaque was scored before and after seven days' use of each toothbrush, employing an adaptation of Quigley-Hein Index modified by Turesky (Plaque Index). Assessments were performed at days 0, 7, 14, 21, 28, and 35. At the end of the trial each subject was asked which toothbrush was preferred.

RESULTS

Final dental plaque scores for toothbrush T3 were statistically different from toothbrushes T1 and T2, which in turn did not differ from each other. Subjects showed preference towards toothbrush T3.

CONCLUSION

Toothbrush T3 was more efficient in terms of dental plaque removal when compared with toothbrushes T2 and T1.

Surface roughness of a dental ceramic after polishing with different vehicles and diamond pastes

During fabrication of bonded ceramic restorations, cervical adaptation, occlusal adjustment and final finishing/polishing are procedures to be performed at the dental office after adhesive cementation. Final adjustments may result in loss of ceramic glaze, which requires new polishing of the ceramic surface, with special attention for selection of adequate materials and instruments. The purpose of this study was to evaluate the efficiency of different vehicles associated with diamond pastes indicated for dental ceramic polishing. Two polishing pastes (Crystar Paste and Diamond Excell) associated with four vehicles (rubber cup, Robinson bristle brush, felt wheel and buff disc) were evaluated. Disc-shaped specimens were fabricated from Ceramco II dental ceramic. Surface roughness means (Ra) of the ceramic specimens were determined with a rugosimeter. Data were analyzed statistically by two-way ANOVA and Tukey's test at 5% significance level. There was no statistically significant difference (p>0.01) between the polishing pastes. However, there were statistically significant differences (p<0.01) among the tested vehicles. Vehicle-paste interaction showed statistically significant difference (p<0.05) as well. It may be concluded that: 1) Robinson bristle brush, felt wheel and buff disc were efficient vehicles to be used in association with a diamond polishing paste; 2) The use of rubber cup as a vehicle showed poor efficiency for mechanical polishing of the ceramic surfaces; 3) Both pastes provided similar and efficient polishing and may be recommended for use with an appropriated vehicle.

Bond strength of three dental porcelains to Ni-Cr and Co-Cr-Ti alloys

Ceramometal bond strength has played an important role for the replacement of gold alloys by nickel-chromium alloys in dentistry. This study evaluated the metal/porcelain bond strength of three ceramic systems (Vita VMK 88, Williams and Duceram) associated with three nickel-chromium alloys (Durabond, Lite Cast B and Resistal P) and one experimental cobalt-chromium-titanium alloy. Thirty cast cylinder specimens (15 mm in height; 6 mm in diameter) were obtained for each alloy, in away that 10 specimens of each alloy were tested with each porcelain. Bond strength was measured with an Emic screw-driven mechanical testing machine by applying parallel shear forces to the specimens until fracture. Kruskal-Wallis and Mann-Whitney U tests were used for statistical analysis of the alloy/ceramic combinations (p<0.05). Resistal P/Duceram had significantly higher bond strength (44.38±9.12 MPa) (p<0.05) than the other combinations, except for Co-Cr-Ti alloy/Vita VMK 88 (38.41±12.64 MPa). The association of the experimental Co-Cr-Ti alloy with Williams porcelain had significantly higher bond strength (28.20±3.86 MPa) than the combination of other alloys with the same porcelain (p<0.05). Based of these results and within the limitations of an in vitro study, it may be concluded that the bond strength of the three ceramic systems to the Ni-Cr and Co-Cr-Ti alloys varied significantly, indicating that metal/ceramic compatibility was very important to the bond strength.

Permeability of remaining endodontic obturation after post preparation

This study assessed the correlation between leakage from the cervix to the apex and from the apex to the cervix for different post preparation techniques. Sixty roots were obturated with gutta-percha lateral condensation and AH Plus sealer and divided into two groups of 30 roots each. Immediate post preparation was used for one group and delayed preparation was used for the other. Two subgroups of 15 roots each were formed to investigate leakage from cervix-to-apex and from apex-to-cervix. The extent of leakage was determined using a dye, India ink, and a clearing technique that rendered the teeth transparent. Linear measurement of the dye penetration was recorded and examined with a stereomicroscope. Eight teeth were used as positive and negative controls. Leakage was observed in all samples. No statistically significant differences were found between the immediate and delayed post preparation techniques regarding apex-to-cervix leakage; however, the values of cervix-to-apex leakage were significantly lower for the immediate technique than for the delayed technique.

Shear bond strength of dental porcelains to nickel-chromium alloys

The continuous technological advance and increasing availability of new base metal alloys and ceramic systems in the market, coupled to the demands of daily clinical practice, have made the constant evaluation of the bond strength of metal/porcelain combinations necessary. This study evaluated the metal/porcelain shear bond strength of three ceramic systems (Duceram, Williams and Noritake) in combination with three nickel-chromium (Ni-Cr) alloys (Durabond, Verabond and Viron). Thirty cast cylinder specimens (15 mm high; 6 mm in diameter) were obtained for each alloy, in a way that 10 specimens of each alloy were tested with each porcelain. Bond strength was measured with an Emic screw-driven mechanical testing machine by applying parallel shear forces to the specimens until fracture. Shear strength was calculated using the ratio of the force applied to a demarcated area of the opaque layer. Mann-Whitney U test was used for statistical analysis of the alloy/ceramic combinations (p<0.05). Viron/Noritake had the highest shear bond sregnth means (32.93 MPa), while Verabond/Duceram (16.31 MPa) presented the lowest means. Viron/Noritake differed statistically from other combinations (p<0.05). Viron/Duceram had statistically significant higher bond strengths than Verabond/Duceram, Verabond/Williams and Durabond/Noritake (p<0.05). It was also found significant difference (p<0.05) between Verabond/Noritake, Verabond/Duceram and Durabond/Noritake. No statistically significant difference (p>0.05) were observed among the other combinations. In conclusion, the Noritake ceramic system used together with Viron alloy presented the highest resistance to shear forces, while Duceram bonded to Verabond presented the lowest bond strength. Viron/Duceram and Verabond/Noritake provided intermediate results. The combinations between the Williams ceramic system and Ni-Cr alloys had similar shear strengths among each other.

Antimicrobial spray for toothbrush disinfection: an in vivo evaluation

OBJECTIVE

The aim of this study was to evaluate the efficacy of a spray containing an antimicrobial solution for toothbrush disinfection.

METHODS AND MATERIALS

Three different solutions were sprayed on toothbrush bristles among 30 adults after they had brushed: (1) basic formulation (base) plus chlorhexidine; (2) base only, and (3) sterile tap water (control). Each solution was tested for 1 week. After that, the toothbrushes were collected and sonicated in Letheen Broth, diluted in 10-fold series, and plated on selective and nonselective media for detection of anaerobes, aerobes, streptococci, and gram-negative bacilli. After incubation, the colonies of those microorganisms were counted. Presence of mutans streptococci on the bristles was also confirmed.

RESULTS

Spray 1 produced a significant reduction in the microbial contamination of toothbrushes for all the microorganisms, spray 2 provided some reduction of contaminants, and spray 3 demonstrated the least antimicrobial effect.

CONCLUSION

The antimicrobial spray with chlorhexidine proved to be an effective and practical means for toothbrush disinfection.

Comparison of two cleansing pastes for the removal of biofilm from dentures and palatal lesions in patients with atrophic chronic candidiasis

The efficacy of 2 oral hygiene products, an experimental toothpaste specific for complete denture cleansing and a regular standard toothpaste, was compared in terms of denture biofilm removal and cure of palatal lesions in patients with atrophic chronic candidiasis. The degree of correlation between presence of biofilm and mucosa erythema was also evaluated. Twenty-four complete denture wearers (45-80 years old) were divided into 2 groups: experimental paste and standard toothpaste (Sorriso-Kolynos, Brazil). Both groups received soft toothbrushes. The internal surfaces of upper dentures were stained using 1% sodium fluorescein and photographed at a 45 masculine angle at 0, 15, 30 and 60 days. The slides were scanned and the areas of interest (denture total area and biofilm area) were measured (Image Tool software). The degree of erythema was evaluated on slides according to the Prosthesis Tissue Index. There was a significant reduction (1%) in the degree of biofilm (ANOVA/Tukey) between the two initial visits (0 and 15 days) and the two final visits (30 and 60 days), and in the average erythema scores (Kruskal-Wallis) between 0 and 60 days, in both groups. The Mann-Whitney test showed a significant difference (1%) between pastes in terms of biofilm degree, but no difference was found for the erythema score. Correlation values between biofilm and erythema degree were 0.3801 (experimental paste) and (0.3678 (standard toothpaste). We may therefore conclude that the experimental product was efficient for the removal of denture plaque biofilm.

Tongue-cleaning methods: a comparative clinical trial employing a toothbrush and a tongue scraper

BACKGROUND

It is estimated that approximately 85% of all halitosis cases have their origin within the mouth; of these, 50% are caused by tongue residues. Previous studies have established that hydrogen sulfide and mercaptans are the primary components of halitosis. Thus, tongue cleaning gains importance as a means of halitosis management.

METHODS

This investigation compared the efficacy of two mechanical methods for tongue cleaning through a handheld sulfide monitor. This crossover trial was carried out with 10 healthy subjects, 20 to 50 years old. Before the baseline measurement of the volatile sulfur compounds (VSCs), the subjects were instructed to refrain from any tongue cleaning method for 48 hours. The 10 participants were then placed in one of two groups (five each): 1) first week: tongue scraper, second week: soft-bristle toothbrush; 2) first week: toothbrush, second week: tongue scraper, with a 48-hour wash-out period between each week.

RESULTS

The baseline measurements were compared with those of the end of each week using the Dunn method (alpha = 0.01). The tongue scraper showed a 75% reduction in VSCs, while the toothbrush only achieved a 45% reduction in VSCs.

CONCLUSION

Although the tongue coating was removed by both methods, the tongue scraper performed better in reducing the production of volatile sulfur compounds.

Assessing the surface roughness of a posterior resin composite: effect of surface sealing

This study assessed the in vitro influence of surface sealing on the surface roughness of a posterior resin composite before and after toothbrushing. Thirty specimens (13 mm diameter x 1 mm high) were fabricated from Filtek-P60 resin composite and randomly assigned to three groups (n = 10): a non-sealed control and two groups sealed with one of the tested materials-a surface-penetrating sealant (Protect-it!-PI) and a one bottle adhesive system (Single Bond-SB). The samples were subjected to a surface roughness reading to determine the initial roughness, then submitted to simulated toothbrushing with 35,600 cycles for 100 minutes. Specimens were then cleaned and a post-abrasion surface roughness reading accomplished. Means (microm), recorded before (B) and after (A) toothbrushing, and standard deviations were: Control--(B): 0.032 (+/- 0.005), (A): 0.054 (+/- 0.005); PI-(B): 0.034 (+/- 0.005), (A): 0.060 (+/- 0.034); SB (B): 0.031 (+/- 0.004), (A): 0.047 (+/- 0.007). Data were tabulated and submitted to two-way ANOVA. No statistically significant difference was observed when the control and experimental groups were compared. However, a significant difference (p < 0.05) was found between the measurements performed before and after toothbrushing. Based on these results, it may be concluded that using either a surface penetrating sealant or a one bottle adhesive system did not provide the optimization of superficial integrity. The use of a dentifrice and toothbrush resulted in significant alterations to the surface smoothness of the resin composite.

Tensile bond strength of a polymeric intra-buccal bioadhesive: the mucin role

The intra-bucal polymeric bioadhesive systems that can stay adhered to the oral soft tissues for drug programmed release, with the preventive and/or therapeutic purpose have been employed for large clinical situations. A system based on hydroxypropyl methyl cellulose/Carbopol 934TM/magnesium stearate (HPMC/Cp/StMg), was developed with the sodium fluoride as an 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 a 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 were determined by means of Brookfield viscometer, and they showed 10.0 cP artificial saliva with mucin, and 7.5 cP artificial saliva without mucin. The tensile strength assays showed the following averages: 12.89 Pa for the group "artificial saliva with mucin", and 12.35 Pa for the group "without mucin". Statistical analysis showed no significant difference between the assays for both artificial salivas, and we can conclude that the variable mucin did not interfere with the bioadhesion process for the polymeric devices.

Capacity of denture plaque/biofilm removal and antimicrobial action of a new denture paste

The efficacy of a paste for complete dentures was analyzed in terms of denture plaque/biofilm removal and antimicrobial action against specific microorganisms by determination of colony forming units of mutans group streptococci and yeast from 120 full denture wearers with a healthy palatine mucosa. The patients were given a questionnaire to evaluate the experimental product in terms of important characteristics. The paste was widely accepted by the patients, and effective in denture plaque removal and antimicrobial action. The species of yeasts most frequently isolated were C. albicans, C. tropicalis and C. glabrata. We conclude that it is possible for complete denture wearers to keep their dentures clean with the regular use of a paste-like hygienic product.

[In vitro assessment of antibacterial activity of ozonized water against Staphylococcus aureus]

Staphylococcus aureus belongs to the normal flora of the skin, mucosa and nasopharynx of several animal species, including man, but it is also associated to illnesses such as abscesses, bacteremia, endocarditis and osteomyelitis, besides showing resistance to multiple drugs. The purpose of this paper was to evaluate the disinfecting ability of ozone when dissolved in water. Suspensions of Staphylococcus aureus with concentrations varying from 10(6) to 10(16) microorganisms/ml were prepared. One milliliter of each recently prepared suspension was added to 99 ml of distilled water (with or without previous ozonization) contained in a crystal reactor. Aliquots of 0.1 ml of this new suspension were taken at various time intervals and, then, serially diluted and inoculated on plaques. The data indicated that there was difference in the disinfecting effect when distilled water was used with and without previous ozonization.

Comparative study of the direct-lift and platinum foil techniques in the marginal discrepancy of collarless metal ceramic restorations

This study was carried out to evaluate the marginal discrepancy of collarless metal ceramic restorations, using a combination of three different techniques to manufacture the porcelain butt margin with two brands of body porcelain. Statistical analysis showed no significant difference between the techniques or brands of body porcelain used in this study.

Optical transmittance of reflecting wedges

This study quantified the light intensity transmitted by the reflecting wedges perpendicularly to the growth axis. The results demonstrated that the cervical wedges did reflect the light of 180 degrees and original light intensity diminished by 83.9%. The maximal light intensity transmitted to the resin by the wedge was less than 8% of that receiving direct exposure to the curing wand. Differential measurements made on points closely spaced along the sides of the wedge indicated a maximal intensity at approximately 2 mm from the base of the wedge.

[Emission microspectrometric study of the amalgam restoration-tooth interface]

Optical Emission Microspectroscopy was used to identify the corrosion products in the amalgam tooth interface with and without cavity varnish use in different times. The factor time determined new chemical elements in the older specimens. A major mercury concentration was found in the restoration interface which used cavity varnish, at the initial twenty-four hours. The first corrosion product had the tin in its composition, possibly from the degradation of 2 phase.

[Resistance and deformation of acrylic resin reinforced with cut and ground fiberglass. 3. Modus of elasticity]

With respect to the elasticity module, it was observed that the incorporation of fiberglass to acrylic resin makes the test bodies more rigid, decreasing their rupture lengthening. The presence of fibers confers on the material a greater capacity of elastic recovery.

[Resistance and deformation of acrylic resin reinforced with cut and ground fiberglass. 2. Rupture lengthening]

The rupture lengthening test demonstrated the addition of fiberglass to acrylic resin tends to make the test bodies more rigid, making them fracture with a shorter lengthening than unloaded resin. The greatest rigidity was observed with a 20% load.

[Resistance and deformation of acrylic resin reinforced with cut and ground fiberglass. 1. Rupture tension]

Traction trials were carried out on acrylic resin test bodies for denture frames reinforced with cut and ground fiberglass, to determine rupture tension. The results demonstrated that: 1--Cut fibers tend to increase the resistance of acrylic to traction forces, and the increase in load percentage of these fibers also increase resistance. 2--This increase was more marked when treatment with SILANE A 174 was combined with the use of cut fibers, at all concentrations tested.

[Quantitative evaluation of reflectance of some acrylic resins mixed with powdered enamel and/or natural quartz]

Autopolymerizing acrylic resins for temporary prothesis and crown veneering have been mixed with dental enamel and/or quartz in powder form in different percentages, to simulate optical properties of the tooth. The analysis of our measurements of apparent reflectance of those mixings show that is possible to approximate several of those values to the ones corresponding to natural tooth; being sufficient to follow the formulation given++ in this paper.