Chemical composition and morphology study of bovine enamel submitted to different sterilization methods.

OBJECTIVES: The morphology and chemical composition of enamel submitted to different sterilization methods was studied. METHODS: X-ray photoelectron spectroscopy (XPS), field emission gun scanning electron microscopy (FEG-SEM), and energy-dispersive X-ray spectroscopy (EDS) were performed to evaluate 50 bovine enamel specimens sterilized using four methods: microwaving (MI), gamma irradiation (GI), ethylene oxide (EO), and steam autoclave (SA). Non-sterilized specimens were used as control. RESULTS: XPS indicated that the concentration of P (phosphorus), CO3 (carbonate), and CO3/P was not changed in all groups. GI produced no significant change on elemental composition. SA produced the major decrease in calcium (Ca), Ca/P ratio, and increase in N (nitrogen). MI was found to decrease Ca, Ca/P ratio and O (oxygen), and increase in C (carbon) and N. EO produced decrease in Ca and O with increased C concentration. FEG-SEM revealed surface and in-depth morphological changes on SA specimens. Minor surface alterations were observed for EO and for MI groups, and no alteration was observed on GI group. EDS indicated no difference on elemental composition of enamel bulk among groups. CONCLUSIONS: SA produced mineral loss and morphological alterations on surface and in depth. MI and EO sterilization caused mineral loss showing only slight alteration on enamel surface. GI sterilization preserves the morphological characteristics of enamel. The sterilization methods could be classified from lower to high damage as GI < MI < EO < SA. CLINICAL RELEVANCE: This is a comprehensive comparative study where different methods for enamel sterilization were investigated in terms of chemical changes. The results presented here may help researchers to choose the most appropriate method for their research setting and purpose.

Correction: In vivo evaluation of photodynamic inactivation using Photodithazine® against Candida albicans.

Correction for 'In vivo evaluation of photodynamic inactivation using Photodithazine® against Candida albicans' by J. C. Carmello, et al., Photochem. Photobiol. Sci., 2015, 14, 1319-1328.

In vivo photodynamic inactivation of Candida albicans using chloro-aluminum phthalocyanine.

This study evaluated the photoinactivation of Candida albicans in a murine model of oral candidiasis using chloro-aluminum phthalocyanine (ClAlP) encapsulated in cationic nanoemulsions (NE) and chloro-aluminum phthalocyanine (ClAlP) diluted in DMSO (DMSO) as photosensitizer (PS). Seventy-five 6-week-old female Swiss mice were immunosuppressed and inoculated with C. albicans to induce oral candidiasis. PDT was performed on the tongue by the application of the photosensitizers and LED light (100 J cm(-2) -660 nm). Twenty-four hours and 7 days after treatments, microbiological evaluation was carried out by recovering C. albicans from the tongue of animals (CFU ml(-1) ). Then, mice were sacrificed and the tongues were surgically removed for histological and biomolecular analysis of pro- and anti-inflammatory cytokines. Data were analyzed by ANOVA followed by Tukey's post hoc test. ClAlP-NE-mediated PDT reduced 2.26 log10 of C. albicans recovered from the tongue when compared with the control group (P-L-) (P < 0.05). PDT did not promote adverse effects on the tongue tissue. Seven days after treatment, all animals were completely healthy. In summary, PDT mediated by chloro-aluminum phthalocyanine entrapped in cationic nanoemulsions was effective in reducing C. albicans recovered from the oral lesions of immunocompromised mice.

In vivo evaluation of photodynamic inactivation using Photodithazine® against Candida albicans.

This study describes the photoinactivation of Candida albicans in a murine model of oral candidosis, mediated by Photodithazine® (PDZ). Six-week-old female Swiss mice were immunosuppressed, and inoculated with C. albicans to induce oral candidosis. After five days, photodynamic inactivation (PDI) mediated by PDZ at concentrations of 75, 100, 125 and 150 mg L(-1) was applied on the tongue of mice. Next, microbiological evaluation was performed by recovering C. albicans from the tongue via colony forming units (CFU mL(-1)). After 24 h of treatment, the animals were killed and the tongues were surgically removed for histological analysis. PDI was effective in reducing C. albicans on the tongue of mice using 100 mg L(-1) of PDZ, when compared to the positive control group (without treatment). No adverse effect on the tongue tissue was verified after PDI. Therefore, PDI was effective for inactivation of C. albicans without causing any harmful effects on host tissues, which is promising for future clinical trials.

Photodynamic inactivation of clinical isolates of Candida using Photodithazine®.

This study evaluated the photodynamic inactivation (PDI) mediated by Photodithazine(®) (PDZ) against 15 clinical isolates of Candida albicans, Candida glabrata and Candida tropicalis. Each isolate, in planktonic and biofilm form, was exposed to PDI by assessing a range of PDZ concentrations and light emitting diode fluences. Cell survival of the planktonic suspensions was determined by colony forming units (CFU ml(-1)). The antifungal effects of PDI against biofilms were evaluated by CFU ml(-1) and metabolic assay. Data were analyzed by non-parametric tests (α = 0.05). Regardless of the species, PDI promoted a significant viability reduction of planktonic yeasts. The highest reduction in cell viability of the biofilms was equivalent to 0.9 log10 (CFU ml(-1)) for C. albicans, while 1.4 and 1.5 log10 reductions were obtained for C. tropicalis and C. glabrata, respectively. PDI reduced the metabolic activity of biofilms by 62.1, 76.0, and 76.9% for C. albicans, C. tropicalis, and C. glabrata, respectively. PDZ-mediated PDI promoted significant reduction in the viability of Candida isolates.

Comparison of Photodynamic Therapy versus conventional antifungal therapy for the treatment of denture stomatitis: a randomized clinical trial.

In this randomized clinical trial, the clinical and mycological efficacy of Photodynamic Therapy (PDT) was compared with that of topical antifungal therapy for the treatment of denture stomatitis (DS) and the prevalence of Candida species was identified. Patients were randomly assigned to one of two groups (n = 20 each); in the nystatin (NYT) group patients received topical treatment with nystatin (100,000 IU) four times daily for 15 days and in the PDT group the denture and palate of patients were sprayed with 500 mg/L of Photogem(®), and after 30 min of incubation, were illuminated by light emitting-diode light at 455 nm (37.5 and 122 J/cm(2), respectively) three times a week for 15 days. Mycological cultures taken from dentures and palates and standard photographs of the palates were taken at baseline (day 0), at the end of the treatment (day 15) and at the follow-up time intervals (days 30, 60 and 90). Colonies were quantified (CFU/mL) and identified by biochemical tests. Data were analysed by Fisher's exact test, analysis of variance and Tukey tests and κ test (α = 0.05). Both treatments significantly reduced the CFU/mL at the end of the treatments and on day 30 of the follow-up period (p <0.05). The NYT and PDT groups showed clinical success rates of 53% and 45%, respectively. Candida albicans was the most prevalent species identified. PDT was as effective as topical nystatin in the treatment of DS.

Evaluation of fungal adherence to plasma-modified polymethylmethacrylate.

There is a propensity for fungal adherence to the polymethylmethacrylate used for making denture bases. Therefore, this study investigated whether surface modifications with plasma treatments would reduce the adherence of Candida albicans to a denture base resin. Samples (n = 180) with smooth and rough surfaces were made and divided into five groups: control - non-treated; experimental groups - submitted to plasma treatments to obtain surfaces with different hydrophobicities (Ar/50 W; ArO(2) /70 W; AAt/130 W) or with incorporated fluoride (Ar/SF(6) 70 W). Contact angles were measured immediately after treatments and after samples were immersed in water for 48 h. For each group, half the samples were incubated with saliva before the adherence test. The number of adhered C. albicans was evaluated by counting after crystal violet staining. The plasma treatments were effective in modifying the polymethylmethacrylate surface. However, there was a significant alteration in the contact angle measured after immersion in water. No statistically significant difference in the adherence of C. albicans was observed between the experimental and control groups, irrespective of the presence or absence of saliva, and surface roughness.

Disinfection of bovine enamel by microwave irradiation: effect on the surface microhardness and demineralization/remineralization processes.

Enamel specimens need to be disinfected before being used in intraoral appliances and the disinfection method must not affect the integrity of the tooth. This study evaluated the effectiveness of microwave bovine enamel disinfection and its effect on the surface microhardness (SMH) and cross-sectional microhardness (CSMH) of sound, demineralized and remineralized enamel. Forty enamel specimens were divided into two groups (n = 20): control (nonirradiated) and microwave. Microwave specimens were immersed in water and irradiated (650 W/3 min). Specimens were incubated at 37 degrees C for 7 days under aerobic and anaerobic conditions. An aliquot was removed for counting, plated at serial dilutions on blood agar plates, which were incubated aerobically and anaerobically. The colony-forming units were calculated. Other 20 enamel specimens (4 x 4 mm) were embedded in acrylic resin, polished and sliced into two halves: one of the fragments was reserved as control while the other was microwaved. SMH and CSMH of sound enamel were analyzed for both groups. The CSMH was further evaluated after demineralization and remineralization cycles. The Knoop integral (DeltaKI) was also calculated. Data were analyzed statistically by paired Student's t test (alpha = 0.05). While control specimens showed microbial growth, those microwaved were disinfected. There were no significant differences in SMH, CSMH and DeltaKI between the control and microwave groups. Microwave irradiation for 3 min at 650 W was effective for the complete disinfection of bovine enamel specimens without affecting the SMH and CSMH of sound, demineralized and remineralized enamel.

Effectiveness of microwave disinfection of complete dentures on the treatment of Candida-related denture stomatitis.

UNLABELLED: The effectiveness of microwave disinfection of maxillary complete dentures on the treatment of Candida-related denture stomatitis was evaluated. Patients (n = 60) were randomly assigned to one of four treatment groups of 15 subjects each; CONTROL GROUP: patients performed the routine denture care; Mw group: patients had their upper denture microwaved (650 W per 6 min) three times per week for 30 days; group MwMz: patients received the treatment of Mw group in conjunction with topical application of miconazole three times per day for 30 days; group Mz: patients received the antifungal therapy of group MwMz. Cytological smears and mycological cultures were taken from the dentures and the palates of all patients before treatment at day 15 and 30 of treatment and at follow-up (days 60 and 90). The effectiveness of the treatments was evaluated by Kruskal-Wallis and Mann-Whitney tests. Microbial and clinical analysis of the control group demonstrated no significant decrease in the candidal infection over the clinical trial. Smears and cultures of palates and dentures of the groups Mw and MwMz exhibited absence of Candida at day 15 and 30 of treatment. On day 60 and 90, few mycelial forms were observed on 11 denture smears (36.6%) from groups Mw and MwMz, but not on the palatal smears. Miconazole (group Mz) neither caused significant reduction of palatal inflammation nor eradicated Candida from the dentures and palates. Microwaving dentures was effective for the treatment of denture stomatitis. The recurrence of Candida on microwaved dentures at follow-up was dramatically reduced.

Clinical evaluation of abutment teeth of removable partial denture by means of the Periotest method.

Prosthodontics should be one of the means of establishing conditions for the maintenance of periodontal health. The forces applied to the abutment teeth and their effects are very important considerations in the design and construction of the removable partial dentures. This 6-month follow-up clinical study evaluated the degree of mobility of abutment teeth of distal extension and tooth supported removable partial dentures by using Periotest. Two types of clasp design were selected for evaluation. In cases with unilateral and bilateral distal-extension, a clasp design including a T clasp of Roach retentive arm, a rigid reciprocal arm and a mesial rest were used. For the abutments of tooth-supported removable partial dentures, a second clasp design with a cast circumferential buccal retentive arm, a rigid reciprocal clasp arm and a rest adjacent to the edentulous ridges was selected. A total of 68 abutment teeth was analysed. Periotest values were made at the time of denture placement (control) and at 1, 3 and 6 months after the denture placement. The statistical analysis was performed using Friedman test. All analysis was performed at a 0.05 level of significance. The results revelled that no significant changes in tooth mobility were observed during the 6-months follow-up (P > 0.05). In conclusion, our findings suggest that adequate oral hygiene instructions, careful prosthetic treatment planning and regular recall appointments play an important role in preventing changes in abutment tooth mobility caused by removable partial denture placement.

Molecular fingerprinting methods for the discrimination between C. albicans and C. dubliniensis.

Opportunistic fungal pathogens are becoming increasingly important causes of both community-acquired and nosocomial infections. The most important fungal pathogens are yeast species belonging to the genus Candida. These species show differences in levels of resistance to antifungal agents and mortality. Consequently, it is important to correctly identify the causative organism to the species level. Identification of Candida dubliniensis in particular remains problematic because of the high degree of phenotypic similarity between this species and Candida albicans. However, as the differences between both are most pronounced at the genetic level, several studies have been conducted in order to provide a specific and rapid identification fingerprinting molecular test. In most candidal infectious, no single DNA fingerprinting technique has evolved as a dominant method, and each method has its advantages, disadvantages and limitations. Moreover, the current challenge of these techniques is to compile standardized patterns in a database for interlaboratory use and future reference. This review provides an overview of most common molecular fingerprinting techniques currently available for discrimination of C. albicans and C. dubliniensis.

Phenotypic methods and commercial systems for the discrimination between C. albicans and C. dubliniensis.

Candida dubliniensis is a recently described Candida species associated with oral candidosis that exhibits a high degree of phenotypic similarity to Candida albicans. However, these species show differences in levels of resistance to antimycotic agents and ability to cause infections. Therefore, accurate clinical identification of C. dubliniensis and C. albicans species is important in order to treat oral candidal infections. Phenotypic identification methods are easy-to-use procedures for routine discrimination of oral isolates in the clinical microbiology laboratory. However, C. dubliniensis may be so far underreported in clinical samples because most currently used identification methods fail to recognize this yeast. Phenotypic methods depend on growth temperature, carbon source assimilation, chlamydospore and hyphal growth production, positive or negative growth on special media and intracellular enzyme production, among others. In this review, some phenotypic methods are presented with a special emphasis on the discrimination of C. dubliniensis and C. albicans.

Effects of chemical disinfectants on the transverse strength of denture base acrylic resins.

The disinfection of dental prostheses by immersion in a chemical solution should be capable of rapid inactivation of pathogenic microorganisms, without causing any adverse effect on the denture base resins. This study evaluated the effect of disinfection immersion on the transverse strength of two heat-cured resins. The denture base resins (Lucitone 550 and QC 20) were polymerized according to the manufacturers' instructions. After polymerization, the specimens were polished, and then stored in water at 37 degrees C for 50 +/- 2 h prior immersion in one of the following solutions for 10 min: 4% chlorhexidine, 1% sodium hypochlorite and 3.78% sodium perborate. The specimens were submitted to disinfection twice, simulating when dentures come from the patient and before being returned to the patient. Ten specimens were made for each group. The transverse strength was evaluated by a 3-point bend test. The flexural strength of the two denture base acrylic resins evaluated remained unaffected after immersion in the three solutions evaluated. In general, the QC 20 resin specimens exhibited lower transverse strength than the Lucitone 550 resin specimens, regardless of immersion solutions.

The effect of disinfectant solutions on the hardness of acrylic resin denture teeth.

This investigation studied the effects of disinfectant solutions on the hardness of acrylic resin denture teeth. The occlusal surfaces of 64 resin denture teeth were ground flat with abrasives up to 400-grit silicon carbide paper. Measurements were made after polishing and after the specimens were stored in water at 37 degrees C for 48 h. The specimens were then divided into four groups and immersed in chemical disinfectants (4% chlorhexidine; 1% sodium hypochlorite and sodium perborate) for 10 min. The disinfection methods were performed twice to simulate clinical conditions and hardness measurements were made. Specimens tested as controls were immersed in water during the same disinfection time. Eight specimens were produced for each group. After desinfection procedures, testing of hardness was also performed after the samples were stored at 37 degrees C for 7, 30, 60, 90 and 120 days. Data were analysed using two-way analysis of variance (anova) and Tukey's test at 95% confidence level. According to the results, no significant differences were found between materials and immersion solutions (P > 0.05). However, a continuous decrease in hardness was noticed after ageing (P < 0.05). It was conclude that the surfaces of both acrylic resin denture teeth softened upon immersion in water regardless the disinfecting solution.

An infection control protocol: effectiveness of immersion solutions to reduce the microbial growth on dental prostheses.

This investigation evaluated the effectiveness of an infection control protocol for cleansing and disinfecting removable dental prostheses. Sixty-four dentures were rubbed with sterile cotton swab immediately after they had been taken from patients' mouths. Samples were individually placed in the culture medium and immediately incubated at 37 +/- 2 degrees C. The dentures were scrubbed for 1 min with 4% chlorhexidine, rinsed for 1 min in sterile water and placed for 10 min in one of the following immersion solutions: 4% chlorhexidine gluconate, 1% sodium hypochlorite, Biocide (iodophors) and Amosan (alkaline peroxide). After the disinfection procedures, the dentures were immersed in sterile water for 3 min, reswabbed and the samples were incubated. All samples obtained in the initial culture were contaminated with micro-organisms. All the lower dentures immersed in Biocide showed positive growth, and the upper dentures were positive for growth in six of eight dentures. The 4% chlorhexidine gluconate, 1% sodium hypochlorite and Amosan solutions have been proved effective to reduce the growth of the micro-organisms in the 10 min immersion period. The protocol evaluated in this study seems to be a viable method to prevent cross-contamination between dental personnel and patients.

An infection control protocol: effectiveness of immersion solutions to reduce the microbial growth on dental prostheses / Um protocolo de controle de infecção: efetividade das soluções de imersão para reduzir o crescimento microbiano em prótese dentária

This investigation evaluated the effectiveness of an infection control protocol for cleansing and disinfecting removable dental prostheses. Sixty-four dentures were rubbed with sterile cotton swab immediately after they had been taken from patients` mouths. Samples were individually placed in the culture medium and immediately incubated at 37 ± 2ºC. The dentures were scrubbed for 1 min with 4 percent chlorhexidine, rinsed for 1 min in sterile water and placed for 10 min in one of the following immersion solutions: 4 percent chlorhexidine gluconate, 1 percent sodium hypochlorite, Biocide (iodophors) and Amosan (alkaline peroxide). After the disinfection procedures, the dentures were immersed in sterile water for 3 min, reswabbed and the samples were incubated. All samples obtained in the initial culture were contaminated with micro-organisms. All the lower dentures immersed in Biocide showed positive growth, and the upper dentures were positive for growth in six of eight dentures. The 4 percent chlorhexidine gluconate, 1 percent sodium hypochlorite and Amosan solutions have been proved effective to reduce the growth of the micro-organisms in the 10 min immersion period. The protocol evaluated in this study seems to be a viable method to prevent cross-contamination between dental personnel and patients

Overlay removable partial dentures for a patient with ectodermal dysplasia: a clinical report.

The orofacial characteristics of ectodermal dysplasia include anodontia or hypodontia, hypoplastic conical teeth, underdevelopment of the alveolar ridges, frontal bossing, a depressed nasal bridge, protuberant lips, and hypotrichosis. Patients with this disease often need complex prosthetic treatment. The options for a definitive treatment plan may include fixed, removable, or implant-supported prostheses, singly or in combination. However, financial constraints and other priorities can prevent patients from choosing the most desirable treatment. This clinical report describes the diagnosis and treatment of ectodermal dysplasia in an 18-year-old man. The treatment included interim removable partial dentures fabricated to establish an acceptable therapeutic occlusal vertical dimension, followed by definitive overlay removable partial dentures and composite restorations.

Bonding strength between a hard chairside reline resin and a denture base material as influenced by surface treatment.

Direct relining of dentures made with hard chairside reline resins is faster than laboratory-processed reline systems and the patient is not without the prosthesis for the time necessary to perform the laboratory procedures. However, a weak bond between the autopolymerizing acrylic reline resins and the denture base material has been observed. This study evaluated the effect of six different surface treatments on the bond strength between a hard chairside reline acrylic resin and a heat-cured acrylic resin. Specimens of the heat-cured acrylic resin were divided into seven groups. One of these groups remained intact. In the other groups, a 10-mm square section was removed from the centre of each specimen. The bonding surfaces were then treated with (i) methyl methacrylate monomer, (ii) isobutyl methacrylate monomer, (iii) chloroform, (iv) acetone, (v) experimental adhesive and (vi) no surface treatment -- control group. Kooliner acrylic resin was packed into the square sections and polymerized. The bonding strength was evaluated by a three-point loading test. The results were submitted to one-way analysis of variance (ANOVA) followed by a Tukey multiple range test at a 5% level of significance. No significant difference was found between the surface treatment with Lucitone 550 monomer or chloroform, but both were stronger than the majority of the other groups. The bond strength provided by all the surface treatments was lower than that of the intact heat-cured resin.

Effect of surface treatments on the bond strength between composite resin and acrylic resin denture teeth.

PURPOSE: This investigation studied the effects of 3 surface treatments on the shear bond strength of a light-activated composite resin bonded to acrylic resin denture teeth. MATERIALS AND METHODS: The occlusal surfaces of 30 acrylic resin denture teeth were ground flat with up to 400-grit silicon carbide paper. Three different surface treatments were evaluated: (1) the flat ground surfaces were primed with methyl methacrylate (MMA) monomer for 180 seconds; (2) light-cured adhesive resin was applied and light polymerized according to the manufacturer's instructions; and (3) treatment 1 followed by treatment 2. The composite resin was packed on the prepared surfaces using a split mold. The interface between tooth and composite was loaded at a cross-head speed of 0.5 mm/min until failure. RESULTS: Analysis of variance indicated significant differences between the surface treatments. Results of mean comparisons using Tukey's test showed that significantly higher shear bond strengths were developed by bonding composite resin to the surfaces that were previously treated with MMA and then with the bonding agent when compared to the other treatments. CONCLUSION: Combined surface treatment of MMA monomer followed by application of light-cured adhesive resin provided the highest shear bond strength between composite resin and acrylic resin denture teeth.