Maristela Barbosa Portela

Resins-based denture soft lining materials modified by chlorhexidine salt incorporation: An in vitro analysis of antifungal activity, drug release and hardness

OBJECTIVES To evaluate the in vitro growth inhibition of Candida albicans, the rate of chlorhexidine release and shore A hardness from resins-based denture soft lining materials modified by chlorhexidine diacetate (CDA) or chlorhexidine hydrochloride (CHC) incorporation. METHODS Resin discs were prepared from soft denture liners based on poly (methyl methacrylate) (PMMA) or poly (ethyl methacrylate) (PEMA) containing 0.5, 1.0 and 2.0 wt.% of CDA or CHC. For antifungal activity resin discs were placed on agar plates inoculated with C. albicans, after 48 h at 37°C the diameters of inhibition zones were measured. For the chlorhexidine release, discs were immersed into distilled water at 37°C, and spectral measurements were made after 48 h. Shore A hardness was evaluated at the baseline, 2 and 7 days, using 6mm thick rectangular specimens also immersed into distilled water at 37°C. Data were statistically processed by SigmaStat software using ANOVA and all pairwise multiple comparison procedures was done using the Holm-Sidak method, with α=0.05 (p<0.001). RESULTS CDA added to PMMA soft liner and PEMA soft liner had a dose-related inhibitory effect on C. albicans and on chlorhexidine release rate (p<0.001). The PMMA and PEMA hardness increased statistically by time but not for the different CDA concentrations. CHC had no inhibitory effect on C. albicans. SIGNIFICANCE Chlorhexidine diacetate released from resins-based soft lining materials can be convenient to reduce the biofilm development on the material surface and treat denture stomatitis, without depending on patient compliance.

A novel nerolidol-rich essential oil from Piper claussenianum modulates Candida albicans biofilm.

Candidiasis is a major opportunistic fungal infection in humans, and its incidence has increased steadily over the last two decades. Candida albicans, the main species of the genus, has a large arsenal of virulence attributes that contribute to successful infections, such as dimorphism and biofilm formation. The adverse effects of eukaryotic antimicrobial therapies associated with an increase in resistance to the compounds presently available have boosted efforts to improve the therapeutic arsenal against candidiasis with a newer and cheaper range of drugs. In this study, a novel nerolidol-rich essential oil (EO) derived from Piper claussenianum (Miq.) C. DC., Piperaceae, was tested on the growth, transition (yeast to hyphae), formation and stability of biofilms produced by C. albicans. Both inflorescence and leaf EOs were evaluated and revealed MIC values ranging from 0.04 to 0.1 % and 0.2 to 1.26 %, respectively. Furthermore, leaf EO managed to downregulate the yeast-to-hyphae transition by 81 %, as well as reducing biofilm formation by about 30 and 50 % after incubation for 24 and 48 h, respectively. The EO was also able to reduce the viability of pre-formed biofilm by 63.9 %. Finally, the association between the leaf EO and fluconazole was evaluated and revealed an interesting synergistic effect. Taken together, these results demonstrate that this novel compound could be a promising agent and could reinforce the arsenal of therapeutic alternatives for the treatment of candidiasis. Furthermore, it may represent a novel and natural source of nerolidol, which could be of interest pharmaceutically.

Salivary lactoferrin in HIV-infected children: Correlation with Candida albicans carriage, oral manifestations, HIV infection and its antifungal activity

OBJECTIVES This study aimed to evaluate the concentration of lactoferrin in the saliva of HIV infected and healthy children and analyze the associations between lactoferrin levels, Candida sp. colonization, oral manifestations and medical data. Also, the antifungal ability of lactoferrin to inhibit the growth of Candida albicans isolated from saliva of these children was investigated in vitro. SUBJECTS AND METHODS Saliva was collected from 70 HIV-infected and 50 healthy children, followed by oral manifestation assessments. The salivary lactoferrin was quantified using an ELISA Kit. The salivary samples were cultured and the Candida spp. colonies counted and then identified by sugar assimilation and fermentation. The antifungal activity of lactoferrin was analyzed in vitro with 10 isolates of C. albicans from each group. RESULTS The HIV infected children (mean age 9.8 ± 2.8) had higher lactoferrin levels (median 6.13 μg/ml (3.58-7.89)) and were colonized three times more by Candida sp. than the control group (mean age 9.4 ± 2.4) (median 5.74 μg/ml (3.12-6.86)) (p=0.003). Statistical associations were found considering the salivary lactoferrin levels and Candida sp. and oral manifestations between the groups. No associations between lactoferrin concentrations and oral manifestations, immunosuppression, presence of AIDS and use of HAART were observed in the HIV group. The percentage of dead C. albicans due to lactoferrin was inversely proportional to C. albicans cell density for both groups (p<0.001). CONCLUSIONS HIV-infected children have higher concentrations of lactoferrin and it was associated with Candida sp. colonization but no association with medical data was found. Also, both groups showed similar lactoferrin antifungal activity.

Biofilm of Candida albicans from oral cavity of an HIV-infected child: challenge on enamel microhardness

OBJECTIVE The aim of this study was to analyze the effect of C. albicans on enamel microhardness in vitro. STUDY DESIGN Candida albicans was isolated from the oral mucosa (M) and dentin carious lesion (D) of an HIV+ child. Three groups of 12 enamel blocks each were placed in Petri plates (yeast carbon base agar/1% bovine serum albumin): G1, exposed to biofilm formed by C. albicans from M; G2, exposed to biofilm formed by C. albicans from D; G3, no biofilm. Three enamel blocks from each group were removed on days 3, 5, 8, and 10 after biofilm formation to measure the cross-sectional Knoop microhardness (CSMH) of the enamel areas, exposed and not exposed to biofilm. RESULTS CSMH decreased in G1 and G2: in G1 on day 5, and in G2 on day 3 (analysis of variance: P < .05; Mann-Whitney test: P < .05), with a similar mean percentage reduction for both groups. CONCLUSIONS Candida albicans can reduce enamel microhardness in vitro.

The oral health of HIV-infected Brazilian children.

BACKGROUND The number of HIV-infected people has increased almost continuously. Paediatric dentists should be concerned about the oral findings in HIV-infected children and their aetiologic factors, to promote adequate treatment. AIM To present the oral health aspects of Brazilian HIV-infected children and to verify the aetiological factors. DESIGN A cross-sectional study was conducted with HIV-infected children. During the medical appointments, children were submitted to visual-tactile exams of oral soft tissues and teeth. All parents answered questions in a structured interview. Data were analysed using the SPSS, release 10.0 (Chicago, IL, USA). RESULTS Of the 57 children examined, 39 (69.6%) presented one or more oral soft tissue manifestations. More than a half suffered from gingivitis and only 12.5% had no visible dental biofilm. A high prevalence of dental surfaces with active carious lesions was observed; mean DMFS-m and dmfs-m scores were 5.41 ± 5.61 and 16.77 ± 19.52, respectively. Caries activity and gingivitis were correlated with the presence of mature dental biofilm. CONCLUSIONS Prevalence of soft tissue lesions, dental caries and gingivitis in HIV-infected children was high and correlated to lack of satisfactory oral hygiene habits, suggesting the need of therapeutic programmes that allow these children to recover their oral health.

Effect of the secretory leucocyte proteinase inhibitor (SLPI) on Candida albicans biological processes: A therapeutic alternative?

OBJECTIVES The aim of this study was to evaluate the effect of SLPI on the growth and biological processes of Candida albicans. METHODS Two C. albicans strains were used in this study, a clinical isolate resistant to fluconazole (PRI) and a reference strain ATCC 24433. The minimal inhibitory concentration (MIC) was determined according to the CLSI methodology. The influence of SLPI on secreted serine proteinase activities (SSP) was measured by the cleavage of specific substrate, and surface hydrophobicity was determined by the aqueous-hydrocarbon biphasic separation method. Flow cytometry was performed to investigate receptors for SLPI and variations in the cell wall mannoprotein expression. Interaction between yeast and epithelium was assessed using the MA-104 cells lineage. Ultrastructure was analyzed by transmission electron microscopy (TEM). RESULTS MIC values were calculated as 18 and 18.9μM for the PRI and ATCC 24433, respectively. SSP activity was reduced by 48.8% by 18μM of SLPI and cell surface hydrophobicity increased by 11.1%. Flow cytometry suggest the existence of SLPI binding sites on the surface of the yeast. Results showed a reduction in the expression of mannoproteins in 20.8% by the cells treated with 80μM of SLPI, and 18μM reduced the adhesion of yeasts to mammalian cells in 60.1%. TEM revealed ultrastructural changes in cells treated with 80μM of SLPI, such as the presence of membrane-like structures within the cytoplasm. CONCLUSIONS SLPI exerts a significant influence on C. albicans viability and biological processes. Considering its constitutive and physiologic features, SLPI may become a promising tool for the development of new methodologies for the treatment and control of candidiasis.

Bruxism Control in a Child with Cerebral Palsy

Cerebral palsy (CP) is one of the most severe childhood disabilities due to a lesion in the developing brain. Oral conditions often observed in this pathogenic are a tendency for the delayed eruption of permanent molars, higher percentages of malocclusion and parafunctional habits, including bruxism. The significance of oral conditions observed in CP patients demonstrates the need for intensive home and professional care for these individuals. This paper presents a 7-year-old boy, with cerebral palsy, severe mental retardation, who had high abrasion wear of the primary teeth related to bruxism. Dental care was carried out under oxide-induced sedation, and management of the bruxism was achieved after the use of a resin acrylic protective appliance fixed on both sides of the mandibula. The treatment performed offered efficiency advantages, was clinically viable, and should be a valuable option to practitioners considering appliance therapy to control parafunctional behavior.

Role of saliva in the caries experience and calculus formation of young patients undergoing hemodialysis

ObjectivesThe aims of this study were to investigate the caries experience, periodontal status, oral hygiene habits, and salivary parameters of children and adolescents undergoing hemodialysis (HD) and to compare them with their healthy counterparts.MethodsFifty-two HD patients were matched for age, sex, ethnicity, and social class with 52 healthy subjects for analysis of the number of decayed, missing and filled teeth, plaque and gingival index, dental calculus accumulation, measurements of pocket depth, clinical attachment level, gingival recession, and bleeding on probing. Stimulated saliva samples were collected to assess salivary flow rate, pH and buffer capacity, and salivary concentrations of calcium, phosphate, and urea by colorimetric method.ResultsHD patients had lower dental caries (p = 0.004), greater plaque and calculus accumulation (p = 0.001), and reported flossing less often than the controls (p = 0.013). Regarding salivary analysis, HD patients showed significantly higher values of pH, buffer capacity, and salivary urea concentration when compared to the controls (p = 0.001).ConclusionHD patients had lower caries experience, higher accumulation of dental plaque, and calculus deposition than their healthy counterparts, probably due to the differences found in their salivary biochemical parameters.Clinical significanceA significant number of children and adolescents undergoing hemodialysis are candidates for kidney transplantation and should receive complete pre-transplant dental exams and dental treatment. Our results open the way for the development of an individualized dental protocol for these patients with preventive measures and treatment of the poor oral health in HD patients.

Is dental caries experience increased in HIV-infected children and adolescents? A meta-analysis

Abstract Objective. To undertake a systematic review to assess if HIV-infected children and adolescents have an increased dental caries experience. Methods. A search of MEDLINE, BIREME, EMBASE, GOOGLE SCHOLAR, SIGLE (Grey Literature) and reference lists of included studies was carried out. To be eligible the studies had to present HIV-infected and non-infected children/adolescents between 0–18 years old. To assess the methodological quality, the studies were categorized in scores from ‘A’ to ‘C’. To perform a meta-analysis a random effect model was used with 95% confidence intervals and two distinct sub-group analyses were carried out in terms of caries progression: data for cavitated and non-cavitated lesions (sub-group 1) and data only for cavitated lesions (sub-group 2). Results. Five studies fulfilled the selection criteria. Four studies (two ranked A and two B in the quality assessment) revealed higher caries scores in primary teeth in the HIV-infected patients with mean dmft/dmfs scores of 3.8–4.1/7.8–11.0 compared to the control group 1.5–2.4/3.4–5.1. No differences in caries index were found for permanent dentition. The meta-analysis excluded caries data of permanent teeth and showed a significant association between caries experience in primary dentition and HIV infection considering cavitated and non-cavitated lesions (OR = 2.33, 95% CI = 1.48–3.68) or only cavitated lesions (OR = 2.98, 95% CI = 1.59–5.59). Conclusion. Evidence exists that suggests HIV-infected children/adolescents have an increased caries experience in primary dentition.

Model resin composites incorporating ZnO-NP: activity against S. mutans and physicochemical properties characterization

Abstract Although resin composites are widely used in the clinical practice, the development of recurrent caries at composite-tooth interface still remains as one of the principal shortcomings to be overcome in this field. Objectives To evaluate the activity against S. mutans biofilm of model resin composites incorporating different concentrations of ZnO-nanoparticles (ZnO-NP) and characterize their physicochemical properties. Materials and Methods Different concentrations of ZnO-NP (wt.%): E1=0, E2=0.5, E3=1, E4=2, E5=5 and E6=10 were incorporated into a model resin composite consisting of Bis-GMA-TEGDMA and barium borosilicate particles. The activity against S. mutans biofilm was evaluated by metabolic activity and lactic acid production. The following physicochemical properties were characterized: degree of conversion (DC%), flexural strength (FS), elastic modulus (EM), hardness (KHN), water sorption (Wsp), water solubility (Wsl) and translucency (TP). Results E3, E4, E5 and E6 decreased the biofilm metabolic activity and E5 and E6 decreased the lactic acid production (p<0.05). E6 presented the lowest DC% (p<0.05). No significant difference in FS and EM was found for all resin composites (p>0.05). E5 and E6 presented the lowest values of KHN (p<0.05). E6 presented a higher Wsp than E1 (p<0.05) and the highest Wsl (p<0.05). The translucency significantly decreased as the ZnO- NP concentration increased (p<0.05). Conclusions The incorporation of 2 – 5 wt.% of ZnO-NP could endow antibacterial activity to resin composites, without jeopardizing their physicochemical properties.