Photosensitization of in vitro biofilms formed on denture base resin.

STATEMENT OF PROBLEM: Proper sterilization or disinfection of removable prostheses and surgical guides has been problematic in dental practice because of the absence of simple and low-cost techniques that do not cause damage to acrylic resins. PURPOSE: The purpose of this study was to study the effect of photodynamic therapy against Streptococcus mutans, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans biofilms formed on acrylic resin specimens. MATERIAL AND METHODS: The specimens were sterilized in ethylene oxide gas and submitted to in vitro biofilm growth. The photodynamic therapy consisted of the application of 0.05% methylene blue (P+) conjugated to irradiation with a light-emitting-diode of 630 nm and 150 mW (L+). The specimens were randomly divided into groups (n=5): negative control (P-L-); stained and irradiated at 10 J/cm(2) (P+L+ 10); stained and irradiated at 30 J/cm(2) (P+L+ 30); stained and not irradiated (P+L-); not stained and irradiated at 10 J/cm(2) (P-L+ 10); not stained and irradiated at 30 J/cm(2) (P-L+ 30); and gold standard (GS), sterilized. Afterward, the specimens were submitted to contact with culture medium agar for 10 minutes in petri plates, which were incubated for 48 hours at 37°C. The number of colony-forming units was obtained, and the data were expressed according to scores (1=0; 2=1-10; 3=11-100; 4=101-1000) and analyzed by the Friedman and Dunn tests (α=.05). RESULTS: Streptococcus mutans was sensitized by (P+L-); P aeruginosa and C albicans were also sensitized by the dye but showed a slight microbial reduction with (P+L+ 30), as did S aureus (P>.05); E coli presented an initial score of 3 and achieved a bacterial reduction to score 2 with (P+L+ 30) (P=.039). CONCLUSIONS: Photodynamic therapy was effective in reducing E coli counts on biofilms formed on acrylic resin specimens. The inhibition of microorganism growth tended to be directly proportional to the amount of energy provided by the light-emitting diode.

Antimicrobial Photodynamic Therapy as a Technique for Decontamination of Acrylic Resin Devices Provided by Different Dental Laboratories.

Introduction: Dentures, occlusal splints, surgical guides and orthodontic appliances are examples of acrylic resin devices made in dental laboratories, which must be disinfected and even sterilized before insertion into the oral cavity. This study evaluated the antimicrobial effect of photodynamic therapy (PDT) applied to acrylic resin specimens received from different laboratories. Methods: Three hundred standardized specimens were ordered from six randomly selected laboratories registered in the Council of Dentistry of Ceará (n=50). The PDT consisted in the association of 22 µM erythrosine, as a photosensitizer (P), and a 520-nm LED at 38 J/cm2 (L). The specimens of each laboratory were randomly distributed into five groups: positive control, sterilized with ethylene oxide; negative control, untreated (P-L-); erythrosine control, only stained (P+L-); LED control, only irradiated (P-L+); PDT (P+L+). Then, the specimens were individually sonicated in saline solution; the suspension was diluted, plated on culture mediums (blood agar, sabouraud dextrose agar and a non-selective chromogenic agar), and incubated for 48 hours at 37°C. Colony-forming-unit (CFU) counts were done and statistical tests of Kruskal-Wallis/Dunn were carried out. Results: The specimens from all laboratories were contaminated with bacteria and yeasts. Staphylococcus aureus, Staphylococcus saprophyticus, Escherichia coli, Enterococcus spp., Klebsiella and Pseudomonas spp. were identified. The PDT significantly reduced CFU counts (P<0.0001), compared to P-L-. Conclusion: PDT was able to effectively decontaminate the acrylic resin specimens provided from dental laboratories.

Candida biofilm matrix as a resistance mechanism against photodynamic therapy.

BACKGROUND: Antimicrobial photodynamic therapy (aPDT) efficiency on Candida albicans is recognized in free-floating cultures. Though, the lack of aPDT effectiveness against C. albicans organized in biofilms is still unclear. This study aimed to explore the role of the extracellular matrix (ECM) in the protection against aPDT in C. albicans biofilms. METHODS: C. albicans SN 425 wild-type and two mutant strains CNJ 2302; Δ/Δefg1 and CJN 2330; Δ/Δtec1 (ECM deficient) were used. Biofilms were grown on 24-well plates and exposed twice-daily to aPDT with 44 µM toluidine blue-O (TBO) for 5 min followed by red light (635 nm) for 1 min (87.6 J/cm²) or 2 min (175.2 J/cm2). Application of just TBO, light, 0.12% chlorhexidine, and ultrapure water were used as controls. After 48 h, biofilms were assessed for dry-weight (DW), colony forming units (CFU), extracellular DNA (eDNA), soluble and insoluble protein (SP/IP), water-insoluble (alkali-soluble) polysaccharide (ASP), water-soluble polysaccharides (WSP), and confocal scanning laser microscopy. RESULTS: The strains with ECM deficient were affected by aPDT. For the mutant strain Δ/Δefg1, aPDT significantly reduced CFU, ASP, DW, eDNA, WSP and IP when compared to NC (p<0.001) and for the Δ/Δtec1, aPDT significantly reduced CFU, eDNA, IP and SP. Whereas CFU, DW, ASP of the wild-type strain biofilms were not reduced (p>0.05). CONCLUSIONS: C. albicans strains with reduced ECM compounds were more sensitive to aPDT suggesting that the ECM may have a significant protection role from aPDT in C. albicans biofilms.

Regimen and different surfaces interfere with photodynamic therapy on Candida albicans biofilms.

The aim of this study is to compare antimicrobial photodynamic therapy (aPDT) against Candida albicans biofilms formed on two different substrates - acrylic resin or bottom of polystyrene plate; and two aPDT application regimens - twice-daily over the course of 48 h or single treatment after 48 h biofilm formation. C. albicans SN425 biofilms cultivated on Roswell Park Memorial Institute medium were incubated for 5 min with toluidine blue O (44 µM) used as a photosensitizer before red light (635 nm; 175.2 J/cm2) exposure for 2 min. As negative control, ultrapure water, and as positive control 0.12% chlorhexidine (CHX) were used. Biofilms were analyzed for colony forming units (CFU) and cells morphology by confocal scanning laser microscopy. Single treatment and twice-daily aPDT on polystyrene plate and single treatment on acrylic resin did not significantly reduce the CFU (p > 0.05); in contrast, twice-daily aPDT on acrylic resin has reduced C. albicans below the detection limit, similarly to CHX treatment. Single aPDT treatment on polystyrene plate and on the resin presented a bulky and homogeneous biofilm predominantly formed by pseudohyphae. In contrast, in the resin group, the biofilm treated twice-daily with aPDT was predominantly formed by yeast cells, whilst pseudohyphae were occasionally visible. In conclusion, biofilms formed on polystyrene plates are more resistant to aPDT than biofilms formed on acrylic resin. Moreover, applying aPDT twice-daily reduces C. albicans biofilm development on acrylic resin and is a better approach against C. albicans biofilms than one single application on the mature biofilm.

Reabilitação estética associando pilar personalizado sobre implante e laminados cerâmicos - relato de caso / Aesthetic rehabilitation associating personalized abutment on implants and ceramic veneers ­ case report

Reabilitações por meio de coroas implanto-suportadas em pacientes que perderam um elemento dentário em região anterior é uma abordagem bem consolidada e pode ser associada a outras técnicas, como o uso de laminados cerâmicos. No entanto, alcançar um resultado estético satisfatório por meio da associação dessas duas abordagens pode ser um desafio para o clínico e o técnico. Objetiva-se relatar um caso clínico de reabilitação estética por meio de laminados cerâmicos, descrevendo uma técnica de confecção de pilar personalizado para laminados sobre implante. Paciente gênero feminino apresentava falta de harmonia da prótese sobre implante do elemento 21 com os demais dentes superiores e apresentava o anseio pela obtenção de dentes com a aparência mais natural. Elaborou-se um planejamento clínico com a realização de adequação do meio bucal seguida por cirurgia periodontal para correção da margem gengival, troca da coroa sobre implante do elemento 21 por um pilar personalizado para receber um laminado cerâmico e confecção de laminados cerâmicos dos dentes 14 a 24. Esse desenho diferenciado do pilar do elemento 21 foi motivado pela dificuldade de acerto de cor, visando uma aparência natural, uma vez que a espessura da cerâmica utilizada para a confecção dos laminados e das coroas totais, e os substratos em que elas são cimentadas são diferentes. A associação de um pilar personalizado sobre implante aos laminados cerâmicos permitiu uma melhor caracterização de cor, otimizando os resultados estéticos.

Efeitos do tratamento com plasma não térmico em superfícies de titânio e materiais cerâmicos

Propriedades adesivas dos materiais odontológicos, como molhamento e rugos idade de superfície são importantes para estudos de efeitos de cimentações de peças protéticas, restaurações e reparos, unindo diferentes materiais e, até mesmo,adesão de células em implantes dentais. Modificações nas superfícies desses materiais podem contribuir para melhoria dessas propriedades. Este estudo analisou os efeitos do tratamento com plasma não térmico em superfícies de titânio puro,cerâmicas vítreas reforçadas por dissilicato de lítio e cerâmica feldspática. Espécimes de titânio foram distribuídos em três grupos (n=5): sem tratamento (ST);tratamento com gás argônio, 6 minutos; e tratamento com plasma de argônio, 6minutos, 10W/1 bar. Foram analisados: ângulo de contato logo após o tratamento(TI), após uma hora (TH) e após uma semana (TS); rugosidade de superfície (Sa); etopografia de superfície (MEV). Espécimes das cerâmicas foram distribuídos em dois grupos (n=5): ST e plasma de argônio 6 minutos, 10W/1bar. Foram analisados:ângulo de contato logo após o tratamento (TI), após uma hora (TH) e após uma semana (TS); rugosidade de superfície (Sa); topografia de superfície (MEV) e resistência de união (MPa)...

Adhesive properties of dental materials such as wetting and surface roughness areimportant for studies of cementing effects of prosthetic devices, repairs andrestorations, combining different materials and even cell adhesion in surgicalbiomaterials. Modifications in the surfaces of these materials can contribute toimprove these properties. This study examined the effects of treatment with argonplasma on surfaces of pure titanium, glass-ceramics reinforced by lithium disilicateand feldspar ceramic. Titanium specimens were divided into three groups (n=5): notreatment (NT); treatment with argon gas, 6 minutes; and treatment with argonplasma, 6 minutes, 10W/1 bar. Contact angle after treatment (IT) - after one hour(HT) and after one week (WT); surface roughness (Sa); and evaluation in a scanningelectron microscope (SEM) were analyzed. Ceramic specimens were divided into twogroups (n=5): NT and argon plasma 6 minutes, 10W / 1 bar. Contact angle aftertreatment (IT) – after one hour (HT) and after one week (WT); and surface roughness(Sa) and SEM evaluation and microtensile (MPa) were analyzed...