Influence of Different Surface Treatments on the Bond Strength of Yttria-Stabilized Tetragonal Zirconia Ceramic.

Objective: This in vitro study evaluates the shear bond strength (SBS) of yttria-stabilized tetragonal zirconia (Y-TZP) and resin cement after different surface treatments. Materials and methods: Forty-eight ceramic cubes were divided into four groups (n = 12): G1 (control) sandblasting with Al2O3; G2-sandblasting with silica-coated Al2O3 (Rocatec); G3-Rocatec + CO2 laser; and G4-CO2 laser + Rocatec. A metallic primer was applied to the pretreated ceramic. A rubber ring was adapted on the central area, and then, the resin cement was inserted into the matrix and photoactivated. The samples were evaluated regarding surface roughness (Ra), SBS, failure type, and qualitatively with scanning electron microscopy (SEM). The data were analyzed by one-way analysis of variance followed by Tukey's test (p < 0.05). Results: The mean values of Ra (µm) were as follows: G1-4.52a, G2-4.24a,b, G3-4.10a,b, and G4-2.90b and the mean values of SBS (MPa) were as follows: G1-7.84a , G2-4.41b , G3-4.61b and G4-6.14a,b. SEM analyses showed superficial irregularities for all groups, being more prominent for G1. The presence of silica deposits was observed for G2, G3, and G4, but in the last two groups there were some linear areas, promoted by the fusion of silica, due to the thermomechanical action of the CO2 laser. Conclusions: The surface treatment with CO2 laser + Rocatec, using one MDP-based cement, can be an alternative protocol for the adhesion cementation of Y-TZP ceramic since it was as effective as the conventional pretreatment with aluminum oxide sandblasting.

Ultraviolet-C decontamination of a dental clinic setting: required dose and time of UVC light / Utilização de radiação ultravioleta-C para descontaminação de um consultorio odontológico: tempo e dose de UVC necessária

Viruses can spread to the environment, and it can be challenging to clear it. A direct approach to limit airborne transmission of pathogens in dental clinic offices is to inactivate viruses within a short time of their production and block the person-to-person transmission routes in dental clinics. For this, we can use chemical substances on surfaces and germicidal ultraviolet light (UV), typically at 254 nm, for complementary disinfection of surfaces and air contaminated by aerosols produced by high-speed handpiece or ultrasound scaler. Based on the literature review and the similarity of Sars-Cov-2 with other previously studied corovaviruses, COVID-19 is sensitive to UV irradiation that can break the genome of this virus, inactivating it. In our study, we performed the calculation of the time required to decontaminate a dental care room between each patient change. We can conclude that the use of UVC can be incorporated into the dental care routine to reduce cross contamination. (AU)

Os vírus podem se espalhar para o meio ambiente e pode ser um desafio eliminá-lo. Uma abordagem direta para limitar a transmissão aérea de patógenos nos consultórios de clínicas odontológicas é inativar os vírus o mais rápido possivel após sua produção e bloquear as rotas de transmissão de pessoa para pessoa nas clínicas odontológicas. Para isso, podemos usar substâncias químicas para limpar as superfícies e luz ultravioleta (UV) germicida (UV), normalmente a 254 nm, para desinfecção complementar de superfícies e ar contaminado por aerossóis produzidos pelo altarotação ou ultrassom periodontal. Com base na revisão de literatura e na semelhança do SarsCov-2 com outros corovavirus previamente estudados, o COVID-19 é sensível à irradiação UV que podem quebrar o genoma desse vírus, inativando-o. Em nosso estudo, realizamos o cálculo de tempo necessário para descontaminar uma sala de atendimento odontológico entre cada troca de paciente. Podemos concluir que a utilização de UVC pode ser incorporada à rotina de atendimento odontológico para reduzir a contaminação cruzada entre atendimentos. (AU)

Effects of near infrared laser radiation associated with photoabsorbing cream in preventing white spot lesions around orthodontic brackets: an in vitro study.

OBJECTIVE: The present study aims to investigate the effect of a low-power infrared laser on the inhibition of bovine enamel demineralization around orthodontic brackets. BACKGROUND DATA: Near infrared lasers have been suggested as alternative approaches because they may produce an increase in resistance to dental caries. METHODS: Forty-eight blocks of enamel obtained from bovine incisor teeth were divided into six groups: Group 1 (control), without treatment; Group 2 (C), photoabsorbing cream; Group 3 (CF), photoabsorbing cream with fluoride; Group 4 (L), irradiation with low-level infrared laser (λ=830 nm) at an energy density of 4.47 J/cm2; Group 5 (L+C), photoabsorbing cream followed by low-level infrared laser irradiation; and Group 6 (L+CF), photoabsorbing cream with fluoride followed by low-level infrared laser irradiation. After these procedures, the enamel blocks received an assortment of orthodontic brackets and were then submitted to pH cycling to simulate a highly cariogenic challenge. The enamel surface demineralization around the orthodontic brackets, according to the different treatments, was quantified by fluorescence loss analysis by quantitative light-induced fluorescence (QLF). The fluorescence loss, expressed as ΔF (percentage of loss fluorescence), was statistically examined by analysis of variance and the Tukey test. RESULTS: The control group (-10.48±2.85) was statistically similar to Group C (-14.52±7.80), which presented the lowest values of ΔF when compared with Groups FC (-3.67±3.21), L (-2.79±1.68), CL (-1.05±0:50), and CFL (-0.60±0:43). However, Groups FC, L, CL, and CFL showed no statistically significant differences among them. CONCLUSIONS: It can be concluded that both the low-level infrared laser and photoabsorbing cream with fluoride were effective in inhibiting the development of caries in enamel around orthodontic brackets, even in situations of high cariogenic challenge.

Effect of CO2 laser on root caries inhibition around composite restorations: an in vitro study.

The aim of the present study was to investigate the in vitro effect of CO2 laser on the inhibition of root surface demineralization around composite resin restorations. For this purpose, 30 blocks obtained from human molar roots were divided into three groups: group 1 (negative control), cavity prepared with cylindrical diamond bur + acid etching + adhesive + composite resin restoration; group 2, cavity prepared with cylindrical diamond bur + CO2 laser (5.0 J/cm(2)) + acid etching + adhesive + composite resin; and group 3, cavity prepared with cylindrical diamond bur + CO2 laser (6.0 J/cm(2)) + acid etching + adhesive + composite resin. After this procedure, the blocks were submitted to thermal and pH cycling. Root surface demineralization around the restorations was measured by microhardness analysis. The hardness results of the longitudinally sectioned root surface were converted into percentage of mineral volume, which was used to calculate the mineral loss delta Z (ΔZ). The percentage of mineral volume, ΔZ, and the percentage of demineralization inhibition of the groups were statistically analyzed by using analysis of variance and Tukey-Kramer test. The percentage of mineral volume was higher in the irradiated groups up to 80 µm deep. The ΔZ was significantly lower in the irradiated groups than in the control group. The percentage of reduction in demineralization ranged from 19.73 to 29.21 in position 1 (50 µm), and from 24.76 to 26.73 in position 2 (100 µm), when using 6 and 5 J/cm(2), respectively. The CO2 laser was effective in inhibiting root demineralization around composite resin restorations.

Adhesion to eroded dentin submitted to different surface treatments / Adesão a dentina erodida submetida a diferentes tratamentos de superfícies

Objective: This in vitro study measured the microshear bond strength (μSBS) of a composite resin to sound and artificially eroded dentin, submitted to surface treatment with diamond bur (DB) or Er,Cr:YSGG laser (L). Material and Methods: Bovine radicular dentin samples were randomly divided into six groups (n = 11): G1- positive control (sound dentin), G2- negative control (eroded dentin), G3-eroded dentin treated with Er,Cr:YSGG laser at 1.5 W, G4-eroded dentin treated with Er,Cr:YSGG laser at 2.0 W, G5-eroded dentin treated with Er,Cr:YSGG laser at 2.5 W and G6-eroded dentin treated with diamond bur. Erosive cycling was performed by immersion in 0.05M citric acid (pH 2.3; 10 min; 6x/day) and in remineralizing solution (pH 7.0, 1 h, between acid attacks), for 5 days. Three composite resin cylinders were bonded to the samples with etchand-rinse adhesive system and after 24 h storage in distilled/deionized water (37 ºC), samples were submitted to microshear bond strength test and mean values (MPa) were analyzed by one-way ANOVA and Tukey tests (α = 0.05). Results: G1 (19.9 ± 7.6A) presented the highest μSBS mean followed by G6 (12.2 ± 3.8B), which showed no statistically significant difference compared with the other groups, except from G4. The lowest μSBS value was found for G4 (7.1±1.5C), which did not differ statistically from G2 (7.5 ± 1.8B,C), G3 (8.4 ± 1.8B,C) and G5 (8.6 ± 3.2B,C). Analysis of the fracture pattern revealed a higher incidence of adhesive fractures for all experimental groups. Conclusion: The results indicate none of the surface treatments (diamond bur and Er,Cr:YSGG laser irradiation at the parameters used in this in vitro study), associated with the etch-and-rinse adhesive system, did not enhance composite resin bonding to eroded dentin...

Objetivo: O presente estudo in vitro visou avaliar a resistência de união (RU) de uma resina composta à dentina hígida e dentina erodida artificialmente, submetidas a diferentes tratamentos de superfície: ponta diamantada (DB) ou Er, Cr: YSGG (L) em diferentes parâmetros. Material e Métodos: Amostras de dentina radicular bovina foram aleatoriamente divididas em seis grupos (n =11): G1- controle positivo (dentina hígida sem tratamento); G2 – controle negativo (dentina erodida sem tratamento); G3 - dentina erodida condicionada com laser de Er,Cr:YSGG (L) em 1,5W; G4 – dentina erodida condicionada com Er,Cr:YSGG em 2,0 W; G5 - dentina erodida condicionada com Er,Cr:YSGG em 2,5 W e G6 - dentina erodida tratada com ponta diamantada. A formação da lesão de erosão foi realizada através de 5 dias de ciclagem por imersão alternada em solução desmineralizadora (ácido cítrico 0,05 M; pH 2,3; 10 min; 6x/dia) e em solução remineralizadora (pH 7,0; 1 h, entre os ataques de ácido). Três cilindros de resina composta foram confeccionados na superficie plana das amostras com o auxílio de um sistema adesivo tipo “condicione e lave”. Após o armazenamento em água destilada/ deionizada por 24 h a 37 ºC, os corpos de prova foram submetidos ao ensaio de microcisalhamento e a media dos valores de RU (MPa) obtidos foram analisados pelo teste ANOVA e teste de Tukey (α = 0,05). Resultados: Os resultados mostraram que G1 (19,9 ± 7,6A) apresentou os maiores valores de RU seguido do grupo G6 (12,2 ± 3,8B), que não apresentou diferença estatisticamente significativa em comparação com os outros grupos, com exceção do G4. O menor valor de RU foi encontrado no grupo G4 (7,1 ± 1,5C), que não diferiu estatisticamente do G2 (7,5 ± 1,8B,C), G3 (8,4 ± 1,8B,C) e G5 (8,6 ± 3,2B,C). A análise do padrão de fratura revelou uma maior incidência de fraturas adesivas para todos os grupos experimentais...

Avaliação in vitro das superfícies vestibulares desmineralizadas e restauradas com resina infiltrante / In vitro evaluation of buccal surfaces demineralized and restored with resin infiltration

Nos dias atuais, os pacientes tem uma grande preocupação com a estética dos dentes. Alterações de posicionamento é um exemplo de problema que o paciente tem interesse em resolver com o tratamento ortodôntico. No entanto, o próprio tratamento ortodôntico tem como característica o uso de acessórios que podem facilitar o acúmulo de resíduos alimentares e dificultar a higienização. Facilitando o desenvolvimento de lesões cariosas. Este estudo in vitro se propôs a avaliar o efeito do mascaramento de tecido dental desmineralizado quando restaurado com a resina infiltrante. Vinte superfícies vestibulares obtidas através de incisivos bovinos tiveram suas superfícies planificadas. Cada espécime foi individualizado de modo que toda leitura para recolhimento de dados fosse feita na mesma superfície. Os espécimes foram submetidos a análise por espectrofotômetro, para obtenção de coordenadas de cor, e a análise da perda mineral, através de quantificação de fluorescência induzida por luz (QLF), sendo que essas análises foram feitas nos tempos: inicial, pós ciclagem de pH, após restauração com a resina infiltrante e após hidratação da resina infiltrante. A análise inicial foi feita de modo a ser obtido o valores iniciais de cor e de conteúdo mineral dos espécimes. Após a leitura inicial, os espécimes foram submetidos a ciclagem de pH durante 16 dias, permanecendo diariamente em soluções desmineralizadora e remineralizadora por 6horas e 18 horas respectivamente. Após o desafio ácido, os espécimes foram avaliados, sendo este o tempo denominado Inicial. Em seguida os espécimes foram restaurados utilizando a resina infiltrante seguidos de nova avaliação, sendo este tempo denominado Icon.

Os espécimes permaneceram em água destilada para hidratação da resina e submetidos a nova avaliação, sendo este tempo denominado Hidratado. Pode-se concluir que a variação total de cor (E), é perceptível ao observador comum, quando comparado à cor inicial com a cor após a restauração. Enquanto que a análise feita pelo QLF, a perda mineral não foi detectada após a hidratação da resina infiltrante.

In the present days, patients have a major concern with the aesthetics of teeth. Changes positioning is an example of a problem that the patient is interested in resolve with orthodontic treatment. However, the actual orthodontic treatment is characterized by the use of accessories that can facilitate the accumulation of food residues and hinders hygiene. This facilitates the development of caries lesions. This in vitro study aimed to evaluate the effect of masking demineralized dental tissue when restored with the infiltrant resin. Twenty buccal surfaces obtained from bovine incisors had planned their surfaces. Each specimen was individualized so that the entire data for analysis was done on the same surface. The specimens were analyzed by spectrophotometer for obtaining color coordinates, and the analysis of mineral loss through quantification of light-induced fluorescence (QLF), and these analyzes were made at times: initial pH cycling post, after restoration with resin infiltrating and. The specimens were analyzed by spectrophotometer for obtaining color coordinates, and the analysis of mineral loss through quantification of light-induced fluorescence (QLF), and these analyzes were made at times: initial pH cycling post, after restoration with resin infiltrating and infiltrating resin after hydration. The initial analysis was made in order to obtain the initial values of color and mineral content of the specimens.

After the initial reading, the specimens were subjected to pH cycling for 16 days, daily remaining in demineralizing and remineralizing solution for 6 hours and 18 hours respectively. After the acid challenge, the specimens were evaluated, this time called Inicial. Then the specimens were restored using resin infiltration followed new analysis, this time being named Icon. The specimens remained in distilled water for hydratation of the resin and subjected to new analysis, this time being called Hidratado. It can be concluded, that the total variation of color (E) is perceptible to the casual observer, when compared to the initial color with the color after restoration. While the analysis by QLF, the mineral loss was not detected after hydratation of resin infiltration.

Influence of aluminum oxide sandblasting associated with Nd:YAG or Er:YAG lasers on shear bond strength of a feldspathic ceramic to resin cements.

OBJECTIVE: This in vitro study evaluated the influence of the surface pretreatment of a feldspathic ceramic on the shear bond strength of two different resin cements. BACKGROUND DATA: Although several conventional surface treatments have been used on feldspathic ceramic, few studies have investigated the effects of an alternative surface treatment, the association of aluminum oxide sandblasting with Nd:YAG and Er: YAG lasers. METHODS: Sixty samples made of a feldspathic ceramic were divided into three groups (n = 20) and treated with (1) controlled-air abrasion with Al(2)O(3) + 10% hydrofluoric acid (HF), (2) Al(2)O(3) + Er:YAG laser, and (3) Al(2)O(3) +Nd:YAG laser. Afterward, silane (Dentsply) was applied on each treated surface. Each of the three main groups was divided into two subgroups (n = 10), where a different resin cement was employed for each subgroup. It was built a cylinder with resin cement (RelyX Arc) in subgroup (A) and with self-adhesive cement (RelyX U100) in subgroup (B). After 24 h at 37 degrees C, the prepared specimens were submitted to shear bond strength test and stereoscopic evaluation to determine the type of failure. RESULTS: Bond strength mean values were not statistically significant for the surface treatment methods or resin cements. CONCLUSION: The null surface treatment proposed with aluminum oxide sandblasting associated with the Er:YAG or Nd:YAG laser and using cementation with self-adhesive cement can be an alternative bonding technique for feldspathic ceramic, since it was as effective as the conventional treatment with aluminum oxide sandblasting and hydrofluoric acid using the conventional resin cement.

Grau de polimerização de LED e luz halógena / Degree of polymerization with LED and halogen light

Introdução - Avaliar a efetividade de polimerização dos diferentes aparelhos LED. Material e Métodos - Foram confeccionados 200 corpos-de-prova com resina micro-híbrida, distribuídos em 40 grupos (n=5). Os corpos-de-prova foram confeccionados nas espessuras de 1, 2, 3 e 4 mm e fotoativados nos tempos de 20 e 40 segundos com os aparelhos: Bright Lec - MM Optics; Lec 470 - MM Optics; Optilight CL - Gnatus e Degulux Softstart - Degussa. As medidas de micromicrodureza Vickers foram obtidas com carga de 50 gF por 45 s e submetidas à ANOVA e teste Tukey. Resultados - A fotoativação em 40s promoveu maior microdureza que em 20s. Na comparação entre grupos, os maiores valores de microdureza foram obtidas com a luz halógena e Bright Lec em 0 mm. Entre os valores que obtiveram pelo menos 80% de microdureza máxima, os aparelhos Optilight CL em 0 e 1mm nos tempos de 40s, Lec 470 apenas na superfície irradiada, Bright Lec em 0 e 1mm nos tempos de 20 e 40 s e Degulux Softstart em 0, 1 e 2 mm em 20s e 0 a 3 mm em 40 s (p < 0,05). Conclusão - Concluiu-se que os aparelhos LED: Optilight CL e Bright Lec polimerizaram satisfatóriamente até 1 mm em 40 s, porém com o Lec 470 os valores de microdureza não caracterizavam polimerização suficiente da resina composta