The bactericidal effect of an atmospheric-pressure plasma jet on Porphyromonas gingivalis biofilms on sandblasted and acid-etched titanium discs

PURPOSE: Direct application of atmospheric-pressure plasma jets (APPJs) has been established as an effective method of microbial decontamination. This study aimed to investigate the bactericidal effect of direct application of an APPJ using helium gas (He-APPJ) on Porphyromonas gingivalis biofilms on sandblasted and acid-etched (SLA) titanium discs. METHODS: On the SLA discs covered by P. gingivalis biofilms, an APPJ with helium (He) as a discharge gas was applied at 3 different time intervals (0, 3, and 5 minutes). To evaluate the effect of the plasma itself, the He gas–only group was used as the control group. The bactericidal effect of the He-APPJ was determined by the number of colony-forming units. Bacterial viability was observed by confocal laser scanning microscopy (CLSM), and bacterial morphology was examined by scanning electron microscopy (SEM). RESULTS: As the plasma treatment time increased, the amount of P. gingivalis decreased, and the difference was statistically significant. In the SEM images, compared to the control group, the bacterial biofilm structure on SLA discs treated by the He-APPJ for more than 3 minutes was destroyed. In addition, the CLSM images showed consistent results. Even in sites distant from the area of direct He-APPJ exposure, decontamination effects were observed in both SEM and CLSM images. CONCLUSIONS: He-APPJ application was effective in removing P. gingivalis biofilm on SLA titanium discs in an in vitro experiment.

Application of plasma sprayed zirconia coating in dental implant: study in implant / 中华口腔医学杂志

Objective@#To investigate the osseointegration of a novel coating-plasma-sprayed zirconia in dental implant.@*Methods@#Zirconia coating on non-thread titanium implant was prepared using plasma spraying, the implant surface morphology, surface roughness and wettability were measured. In vivo, zirconia coated implants were inserted in rabbit tibia and animals were respectively sacrificed at 2, 4, 8 and 12 weeks after implantation. The bond strength between implant and bone was measured by push-out test. The osseointegration was observed by scanning electron microscopy (SEM), micro CT and histological analyses. Quantified parameters including removal torque, and bone-implant contact (BIC) percentage were calculated.@*Results@#The surface roughness (1.6 µm) and wettability (54.6°) of zirconia coated implant was more suitable than those of titanium implant (0.6 µm and 74.4°) for osseointegration. At 12 weeks, the push-out value of zirconia coated implant and titanium implant were (64.9±3.0) and (50.4±2.9) N, and BIC value of these two groups were (54.7±3.6)% and (41.5±3.6)%. All these differences had statistical significance.@*Conclusions@#The surface characters of zirconia coated implant were more suitable for osseointegration and present better osseointegration than smooth titanium implant in vivo, especially at early stage.

Effect of photodynamic therapy and non-thermal plasma on root canal filling: analysis of adhesion and sealer penetration

Abstract Objective The aim of this study was to evaluate the effect of photodynamic therapy (PDT) and non-thermal plasma (NTP) on adhesion and sealer penetration in root canals. Material and Methods Sixty single-rooted premolars were used. The teeth were prepared using a crown-down technique. NaOCl and EDTA were used for irrigation and smear layer removal, respectively. The root canals were divided into three groups: control, PDT, and NTP. After treatments, the roots were filled using gutta-percha and either AH Plus (AHP) or MTA Fillapex (MTAF) sealers. Samples were sectioned at 4, 8, and 12 mm from the apex (1-mm slices)and analyzed by the push-out bond strength test (adhesion) and confocal laser scanning microscopy (sealer penetration). Data were statistically evaluated using Kruskal-Wallis, Dunn's, and Spearman's tests. Results Regarding AHP, bond strength was similar in the NTP group and in the control group, but significantly lower in the PDT group. As to MTAF, both therapies showed lower values than the control group. In the confocal analysis of AHP, maximum and mean penetration, and penetrated area were statistically higher in the control group than in the PDT and NTP groups. Penetrated perimeter was similar among groups. Regarding MTAF, all parameters yielded better results in the NTP than in the control group. The PDT and control groups showed similar results except for penetrated area. Conclusion PDT and plasma therapy affected the adhesion and sealer penetration of root canals filled with AH Plus and MTA Fillapex and there is no positive correlation between adhesion and sealer penetration.

Efeito do plasma de oxigênio na dentina previamente exposta ao NaOCl / Effect of oxygen plasma on dentin exposed to NaOCl

Introdução: O tratamento de plasma é uma tecnologia eficaz que pode manter as propriedades internas dos materiais inalteradas após o tratamento, modificando apenas a superfície. Objetivo: Avaliar o efeito do plasma de oxigênio na dentina previamente exposta ao NaOCl 6%. Material e método: Foram utilizados 60 incisivos bovinos. A coroa foi removida, a raiz foi dividida e as faces planificadas, totalizando 120 segmentos referentes ao terço cervical. As amostras foram divididas em dois grupos: controle (imersa em NaOCl 6%, lavada com água destilada, seca, imersa em EDTA 17%, lavada e seca) e plasma de oxigênio (após tratamento descrito no grupo controle, plasma de oxigênio foi aplicado por 30 s). As amostras foram avaliadas qualitativamente em relação à topografia por microscopia eletrônica de varredura, utilizando-se microfotografias com ampliação de 1.000×. O goniômetro Ramé-hart foi utilizado para a mensuração do ângulo de contato entre as superfícies e as seguintes soluções foram utilizadas: água, etilenoglicol e di-iodometano. Em seguida, a energia de superfície, representada pelas componentes polar e dispersiva, foi calculada. Avaliou-se também o escoamento dos cimentos Pulp Canal Sealer EWT (PCS) e Real Sal SE (RS) na superfície dentinária. Os dados foram analisados estatisticamente utilizando os testes Kruskal-Wallis e Mann-Whitney U (p<0,05). Resultado: O tratamento com plasma levou à formação de uma camada semelhante à smear layer na superfície dentinária. Este tratamento levou a um aumento da energia de superfície e da componente polar, favorecendo a hidrofilicidade da superfície. Entretanto, desfavoreceu o escoamento do cimento PCS e não influenciou no escoamento do cimento RS. Conclusão: O plasma de oxigênio ocasionou mudanças topográficas na superfície dentinária, favorecendo a hidrofilicidade desta. Contudo, não favoreceu o escoamento dos cimentos endodônticos na dentina.

Introduction: Plasma treatment is an effective technology since the internal properties of the material is kept unchanged after treatment, modifying only the surface. Objective: To evaluate the effect of oxygen plasma on dentin previously exposed to 6% NaOCl. Material and method: 60 bovine incisors were used. The crown was removed, the root splited and the faces planned amounting 120 segments related to the cervical third. The samples were divided into 2 groups, control (immersed in 6% NaOCl, washed with distilled water, dried, immersed in 17% EDTA, washed and dried) and oxygen plasma (after treatment described in the control group, oxygen plasma was applied for 30s). The samples were evaluated qualitatively in relation to topography by scanning electron microscopy using photomicrographs at 1000× of magnification. The Ramé-hart goniometer was used to measure the contact angle between the surfaces and the following solutions: water, ethyleneglycol, and diiodomethane. Then, surface energy, polar and dispersive components, was calculated. Additionally, it was evaluated the flow of Pulp Canal Sealer EWT (PCS) and Real Salt SE (RS) sealers on dentin surface. Data were statistically analyzed using Kruskal-Wallis e Mann-Whitney U (p<0.05). Result: Plasma treatment caused topographical changes on dentin surface. This treatment led to an increase in surface energy and polar component, favoring the hydrophilicity of the surface. However, it disfavors the wettability of PCS and did not influence the RS wettability. Conclusion: The oxygen plasma caused topographical changes on dentin surface, favoring its hydrophilicity. However, it did not favor the sealers wettability on dentin.

Effect of Non-Thermal Argon Plasma on Bond Strength of a Self-Etch Adhesive System to NaOCl-Treated Dentin

Abstract Studies have been showing a decrease of bond strength in dentin treated with sodium hypochlorite (NaOCl). The aim of this study was to evaluate the effect of non-thermal argon plasma on the bond strength of a self-etch adhesive system to dentin exposed to NaOCl. Thirty-two flat dentin surfaces of bovine incisors were immersed in 2.5% NaOCl for 30 min to simulate the irrigation step during endodontic treatment. The specimens were divided into four groups (n=8), according to the surface treatment: Control (without plasma treatment), AR15 (argon plasma for 15 s), AR30 (argon plasma for 30 s) and AR45 (argon plasma for 45 s). For microtensile bond strength test, 5 specimens were used per group. In each group, the specimens were hybridized with a self-etch adhesive system (Clearfil SE Bond) and resin composite buildups were constructed. After 48 h of water storage, specimens were sectioned into sticks (5 per tooth, 25 per group) and subjected to microtensile bond strength test (μTBS) until failure, evaluating failure mode. Three specimens per group were analyzed under FTIR spectroscopy to verify the chemical modifications produced in dentin. μTBS data were analyzed using ANOVA and Tamhane tests (p<0.05). AR30 showed the highest μTBS (20.86±9.0). AR15 (13.81±6.4) and AR45 (11.51±6.8) were statistically similar to control (13.67±8.1). FTIR spectroscopy showed that argon plasma treatment produced chemical modifications in dentin. In conclusion, non-thermal argon plasma treatment for 30 s produced chemical changes in dentin and improved the μTBs of Clearfil SE Bond to NaOCl-treated dentin.

Resumo Estudos vêm demonstrando uma diminuição na resistência adesiva em dentina tratada com hipoclorito de sódio (NaOCl). O objetivo desse estudo foi avaliar o efeito do plasma de argônio não-térmico na resistência de união de um sistema adesivo autocondicionante à dentina exposta ao NaOCl. Trinta e duas superfícies dentinárias lisas de incisivos bovinos foram imersas em NaOCl a 2,5% por 30 min para simular o passo de irrigação durante o tratamento endodôntico. Os espécimes foram divididos em 4 grupos (n=8), de acordo com o tratamento de superfície: Controle (sem tratamento de plasma), AR15 (plasma de argônio por 15 s), AR30 (plasma de argônio por 30 s) e AR45 (plasma de argônio por 45 s). Para teste de resistência de união por microtração, cinco espécimes foram utilizadas por grupo. Em cada grupo, os espécimes foram hibridizados com um sistema adesivo autocondicionante (Clearfil SE Bond, Kuraray) e blocos de resina composta foram construídos. Após 48 h de armazenamento em água, os espécimes foram seccionados em palitos (5 por dente - 25 por grupo) e submetidos ao teste de resistência de união por microtração (μTBS) até a fratura, avaliando o padrão de fratura. Três amostras por grupo foram analisadas sob espectroscopia por FTIR para verificar as modificações químicas produzidas pelos tratamentos na dentina. Os dados de microtração foram avaliados estatisticamente utilizando os testes de ANOVA e Tamhane (p<0,05). AR30 apresentou o maior μTBS (20,86±9,0). AR15 (13,81±6,4) e AR45 (11,51±6,8) foram estatisticamente semelhantes ao controle (13,67±8,1). A espectroscopia por FTIR mostrou que o tratamento de plasma produziu modificações químicas na dentina. Como conclusão, o tratamento de plasma de argônio não-térmico por 30 s produziu alterações químicas na dentina e melhorou o μTBS do Clearfil SE Bond à dentina tratada com NaOCl.

Effect of Argon Plasma on Root Dentin after Use of 6% NaOCl

Abstract The aim of this study was to evaluate the effect of argon plasma on dentin surface after use of 6% NaOCl. Sixty bovine incisors had their crowns removed, the roots split, and the segments planed. One hundred twenty segments of the cervical third were used. The samples were divided in two groups (n=60): Control group: immersed in 6% NaOCl, washed, dried and then immersed in 17% EDTA, washed and dried and Argon group: after treatment described for the Control group, non-thermal argon plasma was applied for 30 s. Ten samples were evaluated by scanning electron microscopy in each group. Other ten samples were analyzed by Fourier transform infrared spectroscopy (FTIR). Thirty samples were analyzed with a goniometer to measure the contact angle between the dentin surfaces and solutions, to determine the surface free energy. The last ten samples were used to evaluate the wettability of AH Plus sealer. Data were statistically analyzed using Kruskal Wallis and Mann-Whitney tests (p<0.05). The results of this study showed that argon plasma did not modify the surface topography. FTIR analysis showed chemical modifications after plasma treatment. Argon plasma increased the surface free energy of dentin and AH Plus wettability. In conclusion, argon plasma treatment modified chemically the dentin surface. This treatment increased the surface free energy and wettability of an epoxy resin root canal sealer, favoring its bonding to dentin surfaces.

Resumo O objetivo do presente estudo foi avaliar o efeito do plasma de argônio na superfície dentinária após o uso de NaOCl 6%. As coroas de 60 incisivos bovinos foram removidas, as raízes clivadas e os segmentos planificados. Cento e vinte segmentos referentes ao terço cervical foram utilizados. As amostras foram divididas em dois grupos (n=60): Grupo Controle: imersos em NaOCl 6%, lavados, secos, imersos em EDTA 17%, lavados e secos e Grupo Argônio: após o tratamento descrito no grupo controle, foi aplicado plasma de argônio não térmico por 30 s. Em cada grupo, 10 amostras foram avaliadas por microscopia eletrônica de varredura. Outras dez amostras foram analisadas por espectroscopia no infravermelho por transformada de Fourier (FTIR). Trinta amostras foram analisadas com um goniômetro para medir o ângulo de contato entre a superfície dentinária e as soluções e determinar a energia livre de superfície. As últimas dez amostras foram utilizadas para avaliar a molhabilidade do cimento AH Plus. Os dados foram analisados estatisticamente usando os testes de Kruskal Wallis e Mann-Whitney (p<0,05). Os resultados do estudo mostraram que o plasma de argônio não modificou a topografia de superfície. A análise por FTIR mostrou modificações químicas após o tratamento de plasma. O plasma de argônio aumentou a energia livre da superfície dentinária e a molhabilidade do cimento AH Plus. Conclusão, o tratamento com plasma de argônio modificou quimicamente a superfície dentinária. Este tratamento aumentou a energia livre de superfície e a molhabilidade de um cimento endodôntico à base de resina epóxi, favorecendo as características adesivas da superfície dentinária.

Efeitos do plasma de baixa temperatura sobre os substratos esmalte e dentina

O plasma de baixa temperatura (PBT) tem tido seu uso investigado na destruição dosbiofilmes orais, no entanto,seu efeito sobre os substratos dentários ainda não estácompletamente esclarecido. O objetivo deste trabalho foi avaliar o efeito do PBT na durezasuperficial, no ângulo de contato, na morfologia das superfícies e composição química doesmalte e dentina bovinos. Para tanto, foram analisados a dureza de superfície Knoop (DS), asalterações nos ângulos de contato (AC), a morfologia de superfície por MicroscopiaEletrônica de Varredura (MEV) e sua composição química através da EspectofotometriaRaman (ER). Inicialmente, foram confeccionados blocos de esmalte e dentina com dimensõesde 4x4x2 mm preparados a partir de dentes bovinos. Todos os blocos foram polidos e dividosem três grupos (n=6): Plasma de Argônio, Gás de Argônio e Controle. A MS foi avaliadaantes e depois de cada tratamento, realizando-se cinco penetrações em cada espécime (50g/5spara esmalte e 25g/5s para dentina). A determinação do AC foi realizada dispersando umagota de água sobre a superfície tratada e observando o ângulo de contato obtido em 1 min e 1hora, utilizando fotografias digitais de alta resolução e o programa Image J. As alteraçõesfísicas na morfologia do esmalte e dentina submetidos ao PBT foram observadas a partir daMEV. Adicionalmente, a proporção relativa do conteúdo orgânico e mineral do esmalte edentina após os tratamentos foram analisados por ER. . Os dados foram avaliados por análisede variância (ANOVA) – 1 via para MS e 2 vias (tratamento e tempo) para AC, após Tukeyteste (α < 0,05). Os resultados da MS demostraram não haver diferença significativa noesmalte (p = 0,087) após os tratamentos. No entanto, a MS da dentina diminuiu após otratamento de plasma de argônio (p = 0,005)...

Low-temperature plasma (LTP) is a promising technology with the potential benefit ofdestroying the matrix of the oral biofilm and also produce antimicrobial effect on the bacterialcell. However, the effect of LTP on dental structures is not clear. The objective of this studywas to evaluate the effect of LTP on enamel and dentin substrates. Therefore, we analyzedKnoop microhardness to calculate the percentage of surface hardness (SH), changes in contactangles (CA), the surface topography by Scanning Electron Microscopy (SEM) and also thechemical composition by Raman spectrometry (RS). Initially, 4x4x2 mm enamel and dentinblocks were prepared from bovine incisors. All blocks were polished and divided into threegroups (n = 6); argon plasma, argon flow rate and control. The SH was assessed before andafter each treatment, performing five penetrations in each specimen (50g / 25g and 5s enamel/ dentin 5s). Contact angles changes were performed by dispersing water drop on the treatedsurfaces and observing the contact angle obtained after 1 min and 1 hour. For that, highresolutiondigital photos and the Image J program was used. Physical changes in the structureof enamel and dentin submitted to LTP were observed from the SEM. Additionally, therelative proportion of the organic and mineral content of the enamel and dentin after treatmentwere analyzed by RS. Data were evaluated by analysis of variance (ANOVA) - 2-way(treatment and time) and Tukey test (α <0.05). For the SH the results showed no significantdifference in the enamel (p=0.087), however, the SH of dentin decreased after treatment withargon plasma (p=0.005)...

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...

Bonding strength of resin and tooth enamel after teeth bleaching with cold plasma / 北京大学学报(医学版)

Objective:To investigate the immediate bond strength and surface structure of resin and the tooth enamel which treated by cold plasma.Methods:In the study,40 bovine incisors were divided into two equal parts.In this sense,all enamel adhesive samples were prepared and then randomly divided into 4 groups(n =20).group 1:acid +single bond 2 +resin composite(control group);group 2:beyond bleaching+acid+single bond 2+resin composite;group 3:treated by cold plasma for 5 minutes+acid+single bond 2+resin composite;group 4:treated by cold plasma for 5 minutes+single bond 2+resin composite.Single bond 2 bonding system and Filtek Z250 resin were used in this experiment.The shear bond strength was tested by universal testing machine.The surface of the enamel in different processes was observed by scanning electron microscope (SEM).Statistical analyses by the single factor analysis of variance and multiple pairwise comparisons were performed with SPSS 1 7 .0 .Results:The shear bond strength of group 4 (8.60 MPa)was significantly lower than that of the other three groups (P<0.05). The shear bond strength of group 2 (1 7.89 MPa)was higher than that of group 4,but lower than group 1 and group 3 (P<0.05).There was no significant difference between group 1 (34.82 MPa)and group 3 (34.69 MPa).Scanning electron microscope indicated that the enamel treated by cold plasma had slight molten form,which was different from etched enamel surface.The fractured surface of group 3 was mix fracture,which was similar to the control group (group 1 ).Conclusion:Compared with the conven-tional clinic bleaching,immediate bond strength of resin-enamel that treated by cold plasma has not been affected.

Effects of plasma on polyethylene fiber surface for prosthodontic application

ABSTRACT Plasma technology has the potential to improve the adherence of fibers to polymeric matrices, and there are prospects for its application in dentistry to reinforce the dental particulate composite. Objectives This study aimed to investigate the effect of oxygen or argon plasma treatment on polyethylene fibers. Material and Methods Connect, Construct, InFibra, and InFibra treated with oxygen or argon plasma were topographically evaluated by scanning electron microscopy (SEM), and chemically by X-ray photoelectron spectroscopy (XPS). For bending analysis, one indirect composite (Signum) was reinforced with polyethylene fiber (Connect, Construct, or InFibra). The InFibra fiber was subjected to three different treatments: (1) single application of silane, (2) oxygen or argon plasma for 1 or 3 min, (3) oxygen or argon plasma and subsequent application of silane. The samples (25x2x2 mm), 6 unreinforced and 60 reinforced with fibers, were subjected to three-point loading tests to obtain their flexural strength and deflection. The results were statistically analyzed with ANOVA and the Bonferroni correction for multiple comparison tests. Results SEM analysis showed that oxygen and argon plasma treatments promote roughness on the polyethylene fiber surface. X-ray photoelectron spectroscopy (XPS) analysis shows that both plasmas were effective in incorporating oxygenated functional groups. Argon or oxygen plasma treatment affected the flexural strength and deflection of a fiber reinforced composite. The application of silane does not promote an increase in the flexural strength of the reinforced composites. Conclusions Oxygen and argon plasma treatments were effective in incorporating oxygenated functional groups and surface roughness. The highest strength values were obtained in the group reinforced with polyethylene fibers treated with oxygen plasma for 3 min.

Tecnologia de plasma na Odontologia: revisão de literatura / Plasma technology in dentistry: literature review

A presente revisão de literatura tem como objetivo realizar uma breve introdução ao plasma, abordando o que é, como ele é gerado, seu mecanismo de ação, assim como seu uso na Odontologia, nas diferentes especialidades. Apesar de ainda não estar disponível rotineiramente para uso clínico, estudos mostram que o plasma, quando utilizado em temperatura ambiente, se mostra como uma inovação promissora apresentando atividade antimicrobiana, efeitos positivos em relação à adesão, clareamento dental e osteointegração, sem gerar danos ao tecido oral. Estes efeitos estão relacionados ao tempo de aplicação e ao gás utilizado.

This literature review aims to conduct a brief introduction to plasma, addressing what it is, how it is generated, its mechanism of action, as well as its use in dentistry, in different specialties. Although it is not yet routinely available for clinical use, studies have shown that the plasma, when used at room temperature, appears as a promising innovation featuring antimicrobial activity, positive effects in adhesiveness, tooth whitening and osseointegration, without causing oral tissue damage. These effects are related to application time and the gas used.

Bone tissue response to plasma-nitrided titanium implant surfaces

A current goal of dental implant research is the development of titanium (Ti) surfaces to improve osseointegration. Plasma nitriding treatments generate surfaces that favor osteoblast differentiation, a key event to the process of osteogenesis. Based on this, it is possible to hypothesize that plasma-nitrided Ti implants may positively impact osseointegration. Objective The aim of this study was to evaluate the in vivo bone response to Ti surfaces modified by plasma-nitriding treatments. Material and Methods Surface treatments consisted of 20% N2 and 80% H2, 450°C and 1.5 mbar during 1 h for planar and 3 h for hollow cathode. Untreated surface was used as control. Ten implants of each surface were placed into rabbit tibiae and 6 weeks post-implantation they were harvested for histological and histomorphometric analyses. Results Bone formation was observed in contact with all implants without statistically significant differences among the evaluated surfaces in terms of bone-to-implant contact, bone area between threads, and bone area within the mirror area. Conclusion Our results indicate that plasma nitriding treatments generate Ti implants that induce similar bone response to the untreated ones. Thus, as these treatments improve the physico-chemical properties of Ti without affecting its biocompatibility, they could be combined with modifications that favor bone formation in order to develop new implant surfaces. .

High-efficiency tooth bleaching using non-thermal atmospheric pressure plasma with low concentration of hydrogen peroxide

Light-activated tooth bleaching with a high hydrogen peroxide (HP; H2O2) concentration has risks and the actual role of the light source is doubtful. The use of conventional light might result in an increase in the temperature and cause thermal damage to the health of the tooth tissue. Objective This study investigated the efficacy of tooth bleaching using non-thermal atmospheric pressure plasma (NAPP) with 15% carbamide peroxide (CP; CH6N2O3) including 5.4% HP, as compared with conventional light sources. Material and Methods Forty human teeth were randomly divided into four groups: Group I (CP+NAPP), Group II (CP+plasma arc lamp; PAC), Group III (CP+diode laser), and Group IV (CP alone). Color changes (∆E) of the tooth and tooth surface temperatures were measured. Data were evaluated by one-way analysis of variance (ANOVA) and post-hoc Tukey's tests. Results Group I showed the highest bleaching efficacy, with a ∆E value of 1.92-, 2.61 and 2.97-fold greater than those of Groups II, III and IV, respectively (P<0.05). The tooth surface temperature was maintained around 37°C in Group I, but it reached 43°C in Groups II and III. Conclusions The NAPP has a greater capability for effective tooth bleaching than conventional light sources with a low concentration of HP without causing thermal damage. Tooth bleaching using NAPP can become a major technique for in-office bleaching in the near future. .