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  • Resumo IPEN-doc 29676
    Effect of Er,Cr:YSGG laser and fluoride application on enamel demineralization
    2007 - ANA, P.A.; TABCHOURY, C.P.M.; CURY, J.A.; ZEZELL, D.M.
    This study evaluated the influence of sub-ablative Er,Cr:YSGG laser and topical fluoride application on incipient caries development in vitro. One hundred and sixty human enamel slabs were ramdomly divided into eight equal groups: (1) untreated (control); (2–4) irradiated with Er,Cr:YSGG laser at 0.25, 0.50 and 0.75 W, respectively; (5) treated with acidulated phosphate fluoride (APF; 1.23% F) for 4 min; (6–8) pre-irradiated with Er,Cr:YSGG laser at 0.25, 0.50 and 0.75 W, respectively and subjected to APF application. All groups were submitted to pH-cycling simulating a cariogenic challenge, and after 10 cycles mineral loss ( Δ Z) was measured in enamel. Calcium, inorganic phosphorus (P i ) and fluoride concentrations were also measured in the demineralizing and remineralizing pH-cycling solutions. Data were analyzed by ANOVA ( α = 0.05). No differences in Δ Z were found between laser irradiation at 0.25 W, 0.50 W and controls, while after laser irradiation at 0.75 W (Group 4) and application of APF (Group 5) there was a significant decrease in Δ Z. Laser irradiation at 0.50 and 0.75 W prior to APF application there was a significantly lower Δ Z than in other groups. A significant increase in Ca and P i concentrations was observed in demineralizing solutions compared to the initial concentrations, but no significant changes in Ca and P i concentrations were detected between any groups. A significant decrease in fluoride concentration was observed in pH-cycling solutions of control and 0.25 W laser groups, while the association of laser at 0.50 and 0.75 W with fluoride promoted an increase of fluoride content in remineralizing solutions. In conclusion, Er,Cr:YSGG laser irradiation at 0.50 and 0.75 W, associated with fluoride, seems to be a good alternative for reducing enamel demineralization.
  • Resumo IPEN-doc 28988
    Análise de microdureza de esmalte irradiado com laser Er,Cr:YSGG em baixas fluências
    2004 - ANA, P.A.; BLAY, A.; TURBINO, M.L.; ZEZELL, D.M.
    As modificações nas propriedades químicas do esmalte irradiado provocadas por laser podem indicar o uso deste tratamento como um mecanismo para prevenção da cárie. Este estudo in vitro objetivou avaliar o efeito da irradiação do laser Er,Cr:YSGG em baixas fluências na microdureza do esmalte. Quinze blocos de esmalte foram obtidos de dentes terceiros molares humanos recém-extraídos. As amostras foram embutidas em resina acrílica e foram seccionadas transversalmente em duas porções, sendo uma parte irradiada e outra mantida como controle. Após o polimento, as amostras foram divididas em três grupos e irradiadas de acordo com as seguintes fluências: 2,8 J/cm2 (12,5 mJ/pulso), 5,6 J/cm2 (25 mJ/pulso), e 8,5 J/cm2 (37,5 mJ/pulso). As irradiações foram realizadas com taxa de repetição de 20 Hz, com ausência de spray ar-água e sob a forma de varredura. As superfícies seccionadas das amostras foram submetidas à análise de microdureza Vickers, realizando-se vinte indentações por amostra. Os resultados foram convertidos em porcentagens e submetidos à análise de variância, com p < 0,05. Os resultados mostraram que a microdureza do esmalte dental foi significativamente aumentada nas amostras irradiadas em comparação com as não-irradiadas e as mudanças obtidas foram dependentes das fluências utilizadas. A irradiação com laser Er,Cr:YSGG em baixas fluências pode aumentar a microdureza superficial do esmalte, o que pode indicar um aumento na sua resistência ácida. Conseqüentemente, o laser Er,Cr:YSGG tem potencial para ser utilizado na prevenção da cárie.
  • Resumo IPEN-doc 28987
    Estudo morfológico da superfície de canais radiculares irradiados com laser Er,Cr:YSGG
    2004 - ANA, P.A.; ROCHA, R.M.M.; BLAY, A.; AUN, C.E.; LAGE-MARQUES, J.L.; ZEZELL, D.M.
    O objetivo deste estudo foi avaliar a aparência de canais irradiados com laser de Er,Cr:YSGG após preparo do canal radicular. Selecionou-se nove dentes unirradiculares humanos, cujos canais receberam preparo endodôntico com limas tipo K, associado ao Endo PTC e solução de Dakin. As amostras foram irrigadas com solução desmineralizante EDTA-T por 5 minutos e divididas em 4 grupos. As amostras do grupo I não foram irradiadas, enquanto as do grupo II, III e IV foram irradiadas em associação com a solução irrigadora, utilizando as seguintes fluências: GII (12,5 mJ/pulso; 2,8 J/cm²), GIII (25 mJ/pulso; 8,5 J/cm²) e GIV (75 mJ/pulso; 16,98 J/cm²). A irradiação laser foi realizada com frequência de 20 Hz e ausência de spray ar-água. As superfícies irradiadas foram, então, observadas em microscopia eletrônica de varredura (MEV). Observou-se que as áreas irradiadas apresentaram discreta ablação que aumentava com o aumento da fluência do laser. Não foram encontradas diferenças significativas nos terços coronais das amostras irradiadas ou não irradiadas correspondentes ao padrão de superfície e presença de “smear layer”. No terço médio, as amostras irradiadas apresentaram túbulos abertos e menor quantidade de “smear layer”; no terço apical, as amostras irradiadas exibiram túbulos parcialmente abertos e fina camada de magma dentinário. Conclui-se que a irradiação de canais radiculares com laser Er,Cr:YSGG remove a “smear layer” e propicia a abertura dos túbulos dentinários, o que pode melhorar a permeabilidade dos canais radiculares e por sua vez a ação de protocolos terapêuticos.
  • Resumo IPEN-doc 18922
    In vivo study of diode laser 940 nm operating in high intensity mode in the periimplantitis disease
    The evolution of periimplantitis has been associated with several risk factors. The standard treatment consists on subgingival scaling and blasting with sodium bicarbonate. This 6 months longitudinal clinical study evaluated and compared two treatment methods: conventional as described and complemented by irradiation with high intensity diode laser (940 nm, Biolase) aiming to establish a more efficient periimplantitis management. After approval by the Human Research Ethics Committee, 20 patients of both sexes, with implants in function for at least 12 months and with diagnosis of periimplantitis were selected and randomly distributed in two experimental groups. Ten of them were conventionally treated as control group, and the remaining ten were in the laser treated group (1W, 4.24kJ/ cm2 energy density, pulsed mode, 30s, twice). There were six sites for treatment standardization: vestibular region (mesial, central and distal thirds) and buccal region (mesial, central and distal thirds). Results has shown that overall clinical evaluation has no significant difference between groups control and treatment. less bleeding and suppuration, as shallower periodontal pocket indicated a decreasing tendency on laser treated group. Quantitation of total bacteria and Porphyromona gingivalis by real-time PCR shown that laser synergy is a complementary therapy that could act as an additional option to the conventional treatment in difficult response cases.
  • Resumo IPEN-doc 18453
    Effects of Er,Cr:YSGG laser and a bioactive glass on root caries remineralization
    Considering the aging of the population, the greater exposure of the root surfaces and the higher caries risk in these surfaces, the development of strategies that efficiently remineralize root caries lesions in a long-lasting way is strictly necessary. This in vitro blind randomized study evaluated the potential of remineralization of root caries lesions promoted by Er,Cr:YSGG laser irradiation (2.78 μm) associated with a bioactive glass (Biosilicate ®). 60 bovine root dentin slabs with incipient caries lesions were distributed in 6 experimental groups {n:::15l, in order to be treated with laser irradiation (0.25W, 12.5 mJ/pulse, 2.8 J/cm2, 20 Hz, without refrigeration), application of Biosilicate® or association of both. After the treatments, the samples were subjected to an 8-day pH-cycling regimen, and further evaluated by Fourier transformed infrared spectroscopy {FTIR), optical coherence tomography (OCT) and scanning electron microscopy. The data were statistically analyzed at a 5% significance level. The Biosiljcate ® promoted the formation of carbonated hydroxyapatite even before loser irradiation, which was better retained after demineralization in loser irradiated group. The Biosilicote® and the la ser irradiation alone provided the remineralization of the root dentin in a similar way to that promoted by the topical application of acidulated phosphate fluoride, since all groups had comparable optical attenuation coefficients. The association of the Biosilicate® with the loser irradiation showed higher optical attenuation coefficient than the other experimental groups. It was concluded that the association of Biosilicote® with laser irradiation promoted a synergistic effect, augmenting the remineralization of root dentin and preventing the progression of caries.
  • Resumo IPEN-doc 18341
    Nd:YAG laser irradiation of darkened dental enamel by means of dentrifice use
    As the world population is growing older, dental erosion became a real concern on dentistry. Optical Coherence Tomography and X-Ray fluorescence were used to analyze enamel samples covered by black dentifrice as photoabsorber irradiated with NdYAG laser, then submitted to an erosive cycling. Heat injury risk in deeper tissue decreases because of the dentifrice dark pigment, when the most of photons are absorbed in the surface. Sixty Bmm2 blocks of bovine enamel, were randomized into 4 groups: G1- untreated; G2- treated with acidulated phosphate fluoride (APF, [FJ::1.23%, pH::3.3 to 3.9); G3- irradiated with Nd:YAG laser (1064nm, 0.6W, 10Hz- Lares Research®) using a coal paste as photoabsorber; G4- irradiated with Nd:YAG laser (1064nm, 0.6W, 10Hz), using a black dentifrice (Black is White, Curaprox®). All samples were submitted to a 3-day erosive demineralization (Citric acid 1%, pH::3.6, 5min, 2x/day) under agitation, and remineralization cycling (artificial saliva, pH::7, 120minJ. After treatments and pH cycling, the [Ca]/[P] ratio decreased in the laser irradiated groups. The samples were evaluated by OCT before and after treatment and after erosive cycling. OCT measurements found smaller lesion depths in laser irradiated groups than in the other groups and there were statistically significant differences between G3 and G4 groups (p<0.05). Heating promoted by Nd:YAG laser irradiation changed the morphological and crystallographic enamel surface properties and has shown to be a promissory alternative to prevent erosion.
  • Resumo IPEN-doc 17850
    Shear bond strength of lingual brackets on enamel surface submitted to acid-etching or Nd:YAG laser irradiation
    The patient demand for aesthetic orthodontic solutions is driving for use of lingual brackets and laser irradiation can prevent dental caries in this region. This in vitro study is the first one in literature that aimed to quantify the shear bond strength (SBS) on direct lingual b rackets bonding after different enamel surface pre-treatments. 75 bovine incisor teeth were randomized in 5 groups (n=15): G1- untreated; G2- treated with acidulated phosphate fluoride gel (APF-gel, [F-] =1.23%, pH=3.3 to 3.9); G3- conditioned with 37% phosphoric acid (Condoc 37%, FGM, Brazil) and treated with APF-gel; G4- irradiated with Nd:YAG loser (1064nm, 0.6W, 10Hz- Laser Research) and treated APF-gel; GS- irradiated with Nd:YAG laser + conditioned with 37% phosphoric acid + treated with APF-gel. The positioning of the brackets was standardized during the bonding procedure using a positioner and Transbond XT adhesive (3M Unitek, USA) was used. After bonding, all samples were thermocycled (500 cycles between SoC and 55°C) and submitted to a 48h cariogenic challenge. After cycling, the samples were tested for shear bond strength (SBS) in a universal testing machine (0.5mm/min). SBS test values were statistically higher (p<0.05) in the G3 and G5 groups when compared to the other groups. This study showed that the Nd:YAG loser irradiation improved dental adhesion and increased the mechanical resistance of the enamel because the heating promoted by Nd:YAG laser irradiation changed the morphological and crystallographic properties of enamel; in this way, this treatment also offers the advantage to prevent caries around brackets.
  • Resumo IPEN-doc 10464
    Fluoride incorporation and acid resistance of dental enamel irradiated with Er:YAG
    Er:YAG effects on dental enamel surface regarding the resistance to demineralization and the fluoride incorporation were evaluated. 80 samples were divided into 8 groups: G1) control - APF application; G2) conditioning with 37% phosphoric acid and APF application; G3) irradiation with 250 mJ/pulse, 7 Hz, 31,84 J/cm2 (contact) and APF application; G4) irradiation with 200 mJ/pulse, 7 Hz, 25,47 J/cm2 (contact) and APF application; G5) irradiation with 150 mJ/pulse, 7 Hz, 19,10 J/cm2 (contact) and APF application; G6) irradiation with 250 mJ/pulse, 7 Hz, 2,08 J/cm2 (non-contact) and APF application; G7) irradiation with 200 mJ/pulse, 7 Hz, 1,8 J/cm2 (non-contact) and APF application; G8) irradiation with 100 mJ/pulse, 7 Hz, 0,9 J/cm2 (noncontact) and APF application. All samples were immersed in 2,0 M acetic-acetate acid solution, pH 4,5 for 8 hours. The fluoride, calcium and phosphorous ions were analyzed, by atomic absorption spectrometry and spectrophotometry. Groups laser irradiated before topic APF application presented better results than the control. There was higher fluoride incorporation on G7 and G8. Calcium and phosphorous analysis reveled a decrease on the enamel demineralization on G2 and G3 groups. The Er:YAG laser on irradiation conditions of this work is a promissory alternative for the Preventive Dentistry.
  • Resumo IPEN-doc 08368
    3D-Finite element and thermographic analysis of human teeth irradiated with ErCrYSGG
    The purpose of this study was to analyse surface and pulpal temperature changes in extracted human teeth subjected to Er,Cr:YSGG laser irradiation by using Finite Element Method (FEM) and comparing with thermal analysis made by thermocouple and thermocamera. Twelve extracted human molar teeth were selected and divided into three groups, according to the following Er,Cr:YSGG laser irradiation conditions: 2.8 J/cm2, 5.6 J/cm2 and 8.5 J/cm2. During laser irradiation, surface temperature was measured using a thermocamera (FLIR Systems - USA) and the pulpal temperature was monitored by means of a thermocouple type T placed in the pulpal chamber. For FEM analysis, it were constructed numerical models that reproduced a typical sound molar teeth and the analysis simulated the absorption of the laser energy and the heat transfer through the tooth in three dimensions, considering the same laser energy and conditions performed in thermocouple and thermocamera measurements. The results showed that theoretical FEM calculation showed good agreement with the thermocamera and thermocouple obtained data, simulating heat transfer and predicting the temperature increase. It was possible to conclude that 3D Finite Element Method gives good results that makes possible to understand the thermal behavior of dental material.
  • Resumo IPEN-doc 08253
    Effects of Er, Cr:YSGG Laser irradiation on endodontics system permeability
    2004 - ANA, P.A.; ROCHA, R.M.M.; BLAY, A.; AUN, C.E.; LAGE-MARQUES, J.L.; ZEZELL, D.M.
    The aim of this study was to evaluate the effects of Er,Cr:YSGG laser irradiation on root dentin permeability. Twenty extracted single-rooted teeth were instrumented with K-files and divided in four groups, according to laser fluences: GI (non-irradiated), GII (12.5 mJ/pulse; 2.8 J/cm2), GIII (25 mJ/pulse; 8.5 J/cm2) and GIV (75 mJ/pulse; 16.98 J/cm2). Lased groups had an association of irrigating solution EDTA-T and Er,Cr:YSGG laser irradiation, which was performed at 20 Hz repetition rate without airwater spray, with four helicoidal movements during approximately 5 seconds. NDP associated with rhodamine B dye was used to evaluate dentin permeability. After the experimental period, the samples were transversely cut into six 2.0 mm thick slices for subsequent reading using the ImageLab software. The results showed that dentin permeability of root canals was decreased when exposed to Er,Cr:YSGG laser irradiation compared with non-irradiated samples, and this alteration was higher when higher fluences were applied. The cervical and middle thirds had permeability values statistically similar (p > 0.05) and significantly greater than the apical third. It can be concluded that the use of Er,Cr:YSGG laser irradiation at the utilized parameters decreases dentin permeability, favoring the root canal sealing.