Rebonding strengths of lithium disilicate and feldspathic veneers debonded by Er, Cr: YSGG laser / Resistência de recolagem de facetas de dissilicato de lítio e feldspáticas descoladas por laser Er, Cr: YSGG

Objective: The aim of this study is to identify the shear bond strength of rebonded CAD/CAM laminates made of lithium disilicate or feldspathic ceramics after debonding using Er,Cr:YSGG lasers. Material and Methods:Eighty bovine teeth (N=80) were used as a bonding substrate, which were divided into four main groups (20 each) according to the ceramic material and cement-curing mode used as follows: Group AL: lithium disilicate (IPS E.max) with light-cured resin cement, Group AD: lithium disilicate (IPS E.max) with dual-cured resin cement, Group BL: feldspathic porcelain (VITA MARK II) with light-cured resin cement, and Group BD: feldspathic porcelain (VITA MARK II) with dual-cured resin cement. Half the number of each subgroup (n=10/subdivisions) were tested for their shear bond strength without debonding, while the other half of the specimens were tested after Er,Cr:YSGG laser debonding and rebonding. A three-way ANOVA test was used to study the effect of ceramic and curing on shear bond strength. Bonferroni's post-hoc test was used for pairwise comparisons when the ANOVA test was significant. Results: After rebonding and using the light-cure mode, there was no statistically significant difference between the mean shear bond strength of the two ceramics (P-value = 0.065). However, after rebonding and using the dual-cured mode, E.max showed significantly lower shear bond strength than VITA (P-value < 0.001). Conclusion: Ceramic type, the cement's curing mode, and rebonding after laser irradiation all had a significant effect on the mean shear bond strength (AU)

Objetivo: Identificar a resistência de cisalhamento de laminados CAD/CAM recolados, feitos de cerâmica de disilicato de lítio ou feldspática, após descolamento utilizando lasers Er,Cr:YSGG. Material e Métodos: Oitenta dentes bovinos (N=80) foram utilizados como substrato de colagem, divididos em quatro grupos principais (20 cada) de acordo com o material cerâmico e o modo de cura do cimento utilizado da seguinte forma: Grupo AL: disilicato de lítio (IPS E.max) com cimento resinoso fotopolimerizável, Grupo AD: disilicato de lítio (IPS E.max) com cimento resinoso de dupla cura, Grupo BL: porcelana feldspática (VITA MARK II) com cimento resinoso fotopolimerizável, e Grupo BD: porcelana feldspática (VITA MARK II) com cimento resinoso de dupla cura. Metade do número de cada subgrupo (n=10/subdivisões) foi testada quanto à resistência de cisalhamento sem descolamento, enquanto a outra metade dos espécimes foi testada após descolamento e recolagem a laser Er,Cr:YSGG. Um teste ANOVA de três vias foi usado para estudar o efeito da cerâmica e da cura na resistência de cisalhamento. O teste post-hoc de Bonferroni foi usado para comparações pareadas quando o teste ANOVA foi significativo. Resultados: Após a recolagem e usando o modo de fotopolimerização, não houve diferença estatisticamente significativa entre a resistência de cisalhamento média das duas cerâmicas (valor de P = 0,065). No entanto, após a recolagem e usando o modo de dupla cura, o E.max apresentou resistência de cisalhamento significativamente menor que o VITA (valor de P < 0,001). Conclusão: O tipo de cerâmica, o modo de cura do cimento e a recolagem após irradiação a laser tiveram efeito significativo na resistência de cisalhamento média (AU)

Avaliação dos Efeitos da Remoção da Resina Residual e do Polimento na Superfície do Esmalte após Descolagem do Braquete / Evaluation of the Effects of Residual Resin Removal and Polishing on the Enamel Surface after Bracket Debonding

Considerando o uso de brocas para remoção da resina residual após descolagem do braquete e a possibilidade de injúrias à superfície do esmalte após o uso dessas brocas, este trabalho teve como objetivo realizar um estudo experimental, para avaliar a variação do aspecto superficial do esmalte de forma qualitativa, por meio da avaliação com imagens topográficas do esmalte dentário, utilizando-se a Microscopia Eletrônica de Varredura (MEV), a qual permitiu ilustrar e avaliar a superfície do esmalte após a fase de polimento final, realizada por dois métodos: taça de borracha ou escova Robinson. Foram utilizados 25 dentes pré-molares humanos, obtidos a partir de exodontias em pacientes que procuraram voluntariamente o curso de Residência em Cirurgia da Clínica Odontológica Universitária da Universidade Estadual de Londrina. Os dentes foram divididos em quatro grupos: A, B, C e D, contendo 6 dentes cada, de acordo com as brocas utilizadas para a remoção do remanescente adesivo e o polimento escolhido, além de um dente como "controle". Foi avaliada a rugosidade superficial do esmalte após a remoção da resina e a superfície do esmalte após o polimento com as duas opções apresentadas. Os resultados mostraram que, por observação e inspeção, as brocas removeram a resina residual de todos os dentes, porém, causaram riscos e ranhuras, como evidenciado nas imagens em MEV. Concluiu-se que não houve diferença estatística entre os métodos de polimento e que ambos foram importantes para a redução das marcas abrasivas, proporcionando uma superfície mais lisa do esmalte.

Considering the use of specific burs to remove residual resin after bracket debonding and the possibility of injuries to the dental enamel after using these burs, this study aimed to verify the variation in the enamel surface appearance in a qualitative way and evaluation with topographic images of the dental enamel. The use of Scanning Electron Microscopy (SEM) allowed to illustrate and evaluate the enamel surface after the final polishing phase using two methods: rubber cup or Robinson brush. Twenty-five human premolar teeth were obtained from extractions in patients who voluntarily sought the Oral Maxillofacial Surgery Residency at the Dental School from the State University of Londrina; the teeth were divided into four groups A, B, C and D containing 6 teeth each according to the burs used to remove the remaining adhesive and the chosen polishing, in addition to one tooth as a "control". Dental enamel surface roughness was evaluated after resin removal and enamel surface after polishing with the two methods presented. The results showed that by observation and inspection, the burs removed residual resin from all teeth, however, caused scratches and grooves as evidenced in the SEM images. Based on the results, there was no statistical difference between the polishing methods, and both were important for the reduction of abrasive marks and provided a smoother enamel surface.

The removal of three kinds of occlusal veneers by Er: Yag laser / 华西口腔医学杂志

OBJECTIVES@#This study aimed to remove occlusal veneers of varied thicknesses and compositions by Er:Yag laser in vitro and analyze the interfacial microstructure between veneers and tooth that irradiated by laser, by which experimental evidence could be provided to support the non-invasive removal of occlusal veneerby laser.@*METHODS@#Fresh mandibular premolars extracted for orthodontic requirements were collected for tooth preparation. Three kinds of ceramic materials (Vita Suprinity, Vita Mark Ⅱ, and Upcera Hyramic) were selected to fabricate occlusal veneer with different thicknesses (1.0, 1.5, and 2.0 mm). One week later, Er:Yag laser (2.5 W and 3.5 W) was used to irradiate and remove the occlusal veneer and recorded the timespan. After the removal operation, the micro-morphologies of samples were examined by scanning electron microscope.@*RESULTS@#Upcera Hyramic veneer failed to be removed (>20 min); the operation span at 2.5 W, Vita Suprinity (96.0 s±16.0 s) was longer than Vita MarkⅡ(84.5 s±19.5 s) in the 1.0 mm group (P<0.05), and Vita Suprinity (246.5 s±13.5 s) was longer than Vita MarkⅡ(170.0 s±14.0 s) in the 1.5 mm group (P<0.05). At 3.5 W, Vita Suprinity (381.0 s±24.0 s) was longer than Vita MarkⅡ(341.5 s±26.5 s) in the 2.0 mm group.@*CONCLUSIONS@#Increasing laser power could shorten the operation span and facilitate the removal of occlusal veneers with the same thickness and composition. The occlusal veneer was sustained when insufficient laser power was applied. With the same laser power and ceramic thickness, laser penetration could interfere with the integral of the ceramic structure when the laser interacted with the bonding layer. With the same ceramic composition and laser power, the operation span and laser power increased with the thickness of the occlusal veneer. However, the laser was incapable of removing occlusal resin veneer directly.

Erbium laser in the debonding of ceramics: a literature review / Laser de érbio na remoção de cerâmicas: uma revisão de literatura

Background: The debonding of crowns and ceramic veneers with laser is already a reality in the clinic. It presents benefits in comparison to traditional removal with the use of a rotating instrument; however, there is still no consolidated protocol and many professionals use it without the necessary scientific basis. Objective: The aim of this work was to perform a literature review on the debonding of indirect ceramic restorations using the Er:YAG and Er,Cr:YSGG lasers to provide clinical professionals and the scientific community a careful analysis, and also to guiding the use of irradiation at laser for such procedures. Methods: Bibliographic searches were performed in the following databases: Pubmed, Web of Science and Google Scholar. According to the inclusion criteria adopted, twenty-seven clinical and in vitro studies were selected in the period from 2007 to 2021. In the present work, the composition of the crowns and facets, as well as the types of cement and the laser irradiation protocols adopted in the selected studies is detailed. Conclusions: It was concluded that the use of erbium lasers for debonding of indirect ceramic restorations proved to be more selective and conservative when compared to removal with a rotary diamond instrument. Furthermore, it was shown to be in more efficient in debonding different types of ceramics. However, there are great variations in the "debonding" protocols, which emphasizes the need for further studies that seek to standardize the irradiation protocols considering the different clinical situations (AU)

Antecedentes: A remoção de coroas e facetas cerâmicas com laser já é uma realidade clínica e apresenta benefícios em relação à remoção tradicional com uso de instrumento rotatório diamantado; entretanto, ainda não existe um protocolo consolidado e muitos profissionais o utilizam sem o embasamento científico necessário. Objetivos: O objetivo deste trabalho foi realizar uma revisão da literatura sobre a remoção de restaurações cerâmicas indiretas utilizando os lasers Er:YAG e Er,Cr:YSGG para fornecer uma análise cuidadosa aos profissionais clínicos e à comunidade científica, além de orientar o uso da irradiação a laser para tal aplicação. Métodos: As buscas bibliográficas foram realizadas, nas seguintes bases de dados: Pubmed, Web of Science e Google Scholar. De acordo com os critérios de inclusão adotados, foram selecionados vinte e sete estudos clínicos e in vitro no período de 2007 a 2021. No presente trabalho, a composição das coroas e facetas, bem como os tipos de cimento e os protocolos de irradiação laser adotados nos estudos selecionados foram detalhados. Conclusão: Concluiu-se que o uso dos lasers de érbio para remoção de restaurações cerâmicas indiretas mostrou-se mais seletivo e conservador quando comparado à remoção com instrumento rotatório diamantado, além de ser eficiente na remoção de diferentes tipos de cerâmicas. No entanto, existem grandes variações nos protocolos de "debonding", o que enfatiza a necessidade de novos estudos que busquem uma padronização dos protocolos de irradiação considerando as diferentes situações clínicas.(AU)

Comparative evaluation of three methods of adhesive remnant removal after orthodontic bracket debonding

ABSTRACT Objective: This study aimed to assess the effects of three methods of adhesive remnant removal (carbide bur and low speed handpiece, carbide bur and high speed handpiece, and zircon-rich glass fiber reinforced composite bur), after orthodontic bracket debonding, on tooth color and enamel surface roughness. Methods: Ninety sound premolar teeth were selected. The baseline tooth color was assessed using Vita spectrophotometer. The teeth were subjected to bracket bonding processes and then randomly divided into three equal groups. In each group, composite remnant was removed by one of the three methods of adhesive removal, and the teeth were then subjected to color assessment again. To measure the surface roughness, a scanning electron microscope (SEM) with x400 magnification was used. Results: ANOVA showed that the effect of the three methods of adhesive remnant removal on ∆L, ∆b and ∆E was statistically significant (p=0.01), but without significant effect on ∆a. Comparison of the means showed that composite bur and high speed carbide bur yielded the highest ∆E (p=0.05), and had a significant difference when compared to carbide bur and low speed handpiece. The highest ∆L and ∆b values belonged to samples approached with composite bur and carbide bur with high speed handpiece, respectively. SEM analysis showed that the composite bur created a very smooth surface, compared to the other two methods. Conclusion: Zircon-rich glass fiber reinforced composite created the smoothest enamel surface and highest color change, when compared to the other two methods.

RESUMO Objetivo: O presente estudo teve como objetivo avaliar os efeitos de três métodos de remoção de adesivo remanescente (broca carbide e peça de mão em baixa rotação, broca carbide e peça de mão em alta rotação, e broca de compósito reforçado com fibra de vidro rica em zircônia), após a descolagem de braquetes ortodônticos, sobre a cor dos dentes e rugosidade superficial do esmalte. Métodos: Noventa pré-molares hígidos foram selecionados. A cor inicial dos dentes foi avaliada usando um espectrofotômetro Vita. Os dentes foram submetidos à etapa de colagem dos braquetes e, então, divididos aleatoriamente em três grupos. Em cada grupo, o adesivo remanescente foi removido usando um dos três métodos de remoção, e os dentes foram novamente submetidos à avaliação de cor. Para medir a rugosidade superficial dos dentes, foi usado um microscópio eletrônico de varredura (MEV) com aumento de 400x. Resultados: A ANOVA mostrou que os três métodos de remoção do adesivo remanescente tiveram efeito estatisticamente significativo (p=0,01) em ∆L, ∆b e ∆E, mas sem efeito significativo em ∆a. A comparação das médias mostrou que a broca de compósito e a broca carbide em alta rotação produziram o maior ∆E (p=0,05) e tiveram uma diferença significativa quando comparadas com a broca carbide e a peça de mão em baixa rotação. Os maiores valores de ∆L e ∆b foram encontrados, respectivamente, nos grupos com broca de compósito e broca carbide usando peça de mão em alta rotação. A análise MEV mostrou que o uso da broca de compósito resultou em uma superfície muito lisa, em comparação com os outros dois métodos. Conclusão: Em comparação aos outros métodos, a broca de compósito reforçado com fibra de vidro rica em zircônia criou a superfície de esmalte mais lisa e resultou em uma maior mudança de cor.

Effect of the different debonding strength of metal and ceramic brackets on the degree of enamel microcrack healing

ABSTRACT Objective: This study aims to determine shear debonding strength of metal and ceramic brackets, and the degree of enamel crack healing. Material and Methods: Extracted human maxillary premolars were flattened on the buccal surface, and randomly separated into five groups (n = 15). In control groups (groups 1 and 2), metal and ceramic brackets were bonded on flat polished enamel, while in experimental groups (groups 3 and 4), metal and ceramic brackets were bonded on the surface with boundary where corner cracks were created. Additionally, fifteen specimens (group 5) were also prepared for an indentation procedure with no bracket installation. The degree of crack healing was measured. All brackets were detached with a universal testing machine, and the adhesive remnant index (ARI) was also identified. Healing degree and apparent fracture toughness were then calculated. Results: Between groups with similar bracket types, there was no statistically significant difference in debonding strength. Regarding bracket types, ceramic brackets provided significantly higher debonding strength than metal brackets. There was a significant difference in ARI scores between metal and ceramic brackets. The corner cracks showed signs of healing in both horizontal and vertical directions. No statistically significant difference in the healing rates among the groups was found and the apparent fracture toughness increased from the initial to the final measurement. Conclusions: Within the limitations of this study, even though ceramic brackets required significantly higher debonding force compared to metal brackets, debonding stress was limited to the bonding site and did not affect the surrounding cracks on enamel.

RESUMO Objetivo: O presente estudo teve como objetivo determinar a resistência ao cisalhamento de braquetes metálicos e cerâmicos, e o grau de reparo de fraturas no esmalte. Métodos: Pré-molares superiores, extraídos de humanos, foram aplainados na face vestibular e aleatoriamente divididos em cinco grupos (n = 15). Nos grupos controle (Grupos 1 e 2), os braquetes metálicos e cerâmicos foram colados em esmalte liso e polido; enquanto nos grupos experimentais (Grupos 3 e 4), os braquetes metálicos e cerâmicos foram colados em superfície delimitada, em cujos cantos foram criadas fissuras. Adicionalmente, foram também preparados 15 espécimes (Grupo 5) para um teste com indentação, sem a instalação de braquetes. O grau de reparo das fraturas foi avaliado. Todos os braquetes foram descolados usando uma máquina universal de testes, e o índice de adesivo remanescente (ARI) também foi avaliado. O grau de reparo e a tenacidade à fratura aparente foram então calculados. Resultados: Entre os grupos com o mesmo tipo de braquetes, não houve diferença estatisticamente significativa na força de descolagem. Com relação aos tipos de braquetes, os cerâmicos apresentaram uma força de descolagem significativamente maior do que os metálicos. Houve uma diferença significativa nos escores ARI entre os braquetes metálicos e os cerâmicos. As fraturas de canto mostraram sinais de reparo nos sentidos horizontal e vertical. Não foi detectada diferença estatisticamente significativa no grau de reparo entre os grupos, e a tenacidade à fratura aparente aumentou da mensuração inicial para a final. Conclusão: Considerando-se as limitações desse estudo, apesar de os braquetes cerâmicos necessitarem de força de descolagem significativamente maior do que os braquetes metálicos, a tensão de descolagem foi limitada ao sítio de colagem, não afetando as fraturas de esmalte ao redor.

Pain and removal force associated with bracket debonding: a clinical study

Abstract Objective: Pain is a problem during bracket removal, and more comfortable treatment is needed. This study examined the association of pain with the removal force required for ceramic brackets, compared with metal and plastic brackets, to determine which removal method resulted in less pain and discomfort. Methodology: 81 subjects (mean age, 25.1 years; 25 males and 56 females) were enrolled, from whom 1,235 brackets (407 ceramic, 432 plastic, and 396 metal) were removed. Measured teeth were distinguished at six segments. Pain was measured with a visual analogue scale (VAS) during the removal of each bracket. An additional grip was placed on the grips of debonding pliers with right-angled beaks; a mini loading cell sensor pinched by the grips was used to measure removal force during debonding. VAS and force values were statistically analyzed. The Kruskal-Wallis test followed by the Mann-Whitney U test with Bonferroni correction were performed for multiple comparisons; multiple regression analysis was also performed. Results: Forces in the upper and lower anterior segments were significantly smaller (p<0.05) than those in the other segments. Pain tended to be greater in the upper and lower anterior segments than in the posterior segments. In all segments, the removal force was greater for metal brackets than for plastic or ceramic brackets. Ceramic brackets caused significantly greater pain than plastic brackets for the upper and lower anterior segments. Debonding force was involved in the brackets, following adjustments for pain, upper left segment, age, and sex. Conclusions Pain and discomfort are likely to occur during bracket debonding.

Tooth color alteration after debonding in orthodontic patients with adhesive removal using composite bur or tungsten carbide bur: a single center, randomized controlled clinical trial / Alteração da cor do dente após descolagem de braquetes em pacientes ortodônticos pela remoção de adesivo usando broca de compósito ou broca carbide de tungstênio: ensaio clínico unicêntrico randomizado e controlado

Objective: The objective of this study was to determine whether recently developed fiber reinforced composite burs provided better results by comparing tooth discoloration after debonding of orthodontic brackets. Material and Methods: A split-mouth, randomized controlled trial was carried out in one orthodontic office; including 23 patients with intact, vital and caries-free four upper incisors aged 12 to 30 years who completed their fixed orthodontic treatment. For each patient, upper central and lateral incisors on each side of the mouth were randomly selected to remove the adhesive with either a tungsten carbide bur (TC) (n = 46) or a fiber-reinforced composite bur (FC) (n=46). Color evaluation of each tooth was conducted at two time points: immediately after finishing and polishing procedure and two months afterwards. The primary outcome would be the amount of color change in each group during the post treatment phase. The participants, the person assessing the color change and the statistician were blinded to TC group assignment. Color changes in each group were analyzed with the Paired T-test. The color change corresponding to the resin removal method was also statistically analyzed with the Independent T-test at α=0.05 as the level of significance. Results: 86 teeth, 43 in each group, were analyzed. The ΔE value was 3.713±1.161, for teeth finished TC and 2.114±0.514 for teeth finished with FC (p<0.01). Conclusion: Adhesive removal with FC bur results in a more color-resistant tooth surface in comparison with tungsten carbide bur. (AU)

Objetivo: O objetivo deste estudo foi determinar se as brocas de material compósito reforçadas com fibras, recentemente desenvolvidas, proporcionam melhores resultados, pela comparação da descoloração dentária após a remoção de braquetes ortodônticos. Material e Métodos: Um ensaio clínico controlado randomizado com boca dividida foi realizado em um consultório ortodôntico, incluindo 23 pacientes, com idade entre 12 e 30 anos, com incisivos superiores intactos, vitais e livres de cárie, que completaram o tratamento ortodôntico com aparelho fixo. Para cada paciente, incisivos centrais e laterais superiores de cada lado da boca foram selecionados aleatoriamente para remover o adesivo ortodôntico com uma broca carbide de tungstênio (TC) (n = 46) ou uma broca de compósito reforçada com fibra (FC) (n = 46). A avaliação da cor de cada dente foi realizada em dois momentos: imediatamente após o acabamento e polimento e dois meses após. O resultado primário foi a quantidade de mudança de cor em cada grupo durante a fase pós-tratamento. Os participantes, a pessoa que avaliou a mudança de cor e o estatístico não tinham conhecimento da atribuição ao grupo TC. As mudanças de cor em cada grupo foram analisadas com o teste-t pareado. A mudança de cor correspondente ao método de remoção da resina também foi analisada estatisticamente com o teste-t independente considerando um nível de significância α = 0,05. Resultados: foram analisados 86 dentes, 43 em cada grupo. O valor de ΔE foi 3,713 ± 1,161, para dentes finalizados com broca TC e 2,114 ± 0,514 para dentes finalizados com broca FC (p <0,01). Conclusão: A remoção do adesivo com broca FC resulta em uma superfície de dente mais resistente à cor em comparação com a broca carbide de tungstênio (AU)

Feasibility of Different Methods after Debonding of Orthodontic Brackets: An In Vivo Study

Aim: This study aims to evaluate and compare the discomfort levels during debonding using different three methods and adhesive remnant index (ARI) scores compared. Materials and Methods: Sample comprised 50 female patients from single clinic of an average age of 24 years and 5 months. Three methods used were lift-off debonding instrument (LODI), straight cutter, and Howe plier. At the end of debonding in each quadrant, discomfort levels were assessed using visual analog scale (VAS). Remaining adhesive on enamel surface was studied with the help of ARI. Results: Pain scores were significantly higher for SC method. LODI group showed least discomfort. ARI showed significantly different results with three methods used. Conclusion: Patients showed least discomfort when LODI method was used.

The contribution of ceramic thickness and adhesive type on the de-bonding strength of dental ceramic veneers using Er, Cr: YSGG laser / La contribución del espesor de la cerámica y el tipo de adhesivo a la resistencia de desunión de las carillas dentales de cerámica con láser Er, Cr: YSGG

Purpose: De-bonding strength of ceramic veneers by laser use needs to be evaluated in detail. The aim of this study, is to determine the contribution of ceramic thickness and cementing agents to the de-bonding strength of ceramic veneers using Er,Cr:YSGG laser. Methods: A total of 120 maxillary central incisors specimens were randomly divided into twelve groups on the basis of disc thickness, cementing agent, and Er,Cr:YSGG laser use. Under laboratory conditions, 120 IPS Empress II system discs 0.5mm, 1mm, and 2mm in thickness were applied to the tooth surfaces, for laser use. An Er,Cr:YSGG laser system was applied to the central surface of the IPS Empress II discs on specimens in all laser groups (Groups 1,3,5,7,9,11). Then the shear bond strength (SBS) for all specimens were tested with a testing machine at a speed of 0.5mm/min. The SBS values were considered as the de-bonding strength. Results: The mean de-bonding strength values for Groups 9 and 11 (0,5 mm disc thickness + laser application) have the lowest median load (0.000 N), while Group 4 (2mm disc thickness + no laser) has the highest median load (573.885 N). The de-bonding strengths of all the groups without laser application were higher than those of all groups with laser use. When laser is applied, the mean de-bonding strength decreases with decreasing disc thickness, and it reaches zero at 0.5mm thickness of discs cemented by self- or total-etch adhesives. Conclusions: The de-bonding strength decreases with laser use, and decreasing disc thickness. In the absence of laser, the mean de-bonding values of discs cemented by a total etch adhesive system are always higher than those of discs cemented with a self-etch adhesive system. Without any extra load, all 0.5mm thick discs were dislodged from teeth while applying or testing the laser.

Propósito: La resistencia de desunión de las carillas de cerámica mediante el uso del láser debe evaluarse en detalle. El objetivo de este estudio es determinar la contribución del espesor de la cerámica y los agentes de cementación a la resistencia de desunión de las carillas de cerámica utilizando el láser Er, Cr: YSGG. Métodos: Un total de 120 incisivos centrales maxilares se dividieron al azar en doce grupos según el grosor del disco, el agente de cementación y el uso del láser Er, Cr: YSGG. En condiciones de laboratorio, se aplicaron en las superficies de los dientes 120 discos del sistema IPS Empress II de 0,5mm, 1mm y 2mm de grosor, para uso con láser. Se aplicó un sistema láser Er, Cr: YSGG a la superficie central de los discos IPS Empress II en muestras de todos los grupos de láser (Grupos 1,3,5,7,9,11). Luego, la resistencia de la unión al cizallamiento (SBS) para todas las muestras se probó con una máquina de prueba a una velocidad de 0.5mm/min. Los valores de SBS se consideraron como la fuerza de desunión. Resultados: Los valores medios de resistencia de desunión para los Grupos 9 y 11 (espesor de disco de 0,5mm + aplicación de láser) demostró la carga media más baja (0,000 N), mientras que el Grupo 4 (espesor de disco de 2 mm + sin láser) tuvo la carga media más alta (573.885 N). Las fuerzas de desunión de todos los grupos sin aplicación de láser fueron superiores a las de todos los grupos con uso de láser. Cuando se aplica el láser, la fuerza media de desunión disminuye al disminuir el grosor del disco, y llega a cero con el grosor de 0,5mm de los discos cementados, para ambos adhesivos de grabado. Conclusiones: la fuerza de desunión disminuye con el uso del láser y disminuye con el grosor del disco. En ausencia de láser, los valores medios de desunión de los discos cementados con un sistema de adhesivo de grabado total son siempre más altos que los de los discos cementados con un sistema de adhesivo de autograbado. Sin ninguna carga adicional, todos los discos de 0,5mm de grosor se desprendieron de los dientes al aplicar el láser.

Comparison of Shear Bond Strength of Occlusal Pad Debonding Pliers Before and After Er-YAG Laser Application: An In vitro Study

Background: Er-YAG laser showed to be effective in debonding ceramic bracket from the enamel surface. Until lately, no previous study was conducted to assess the outcome of the laser in debonding ceramic brackets from tooth surface comparing it with conventional occlusal pad debonding pliers. Materials and methods: Total 60 ceramic brackets were bonded on the tooth surface which was divided randomly into 2 groups. One was assigned as a control non-lased group and the other was experimental lased groups. Er-YAG laser irradiated the experimental groups at the power of 5 W for 10 seconds with swiping motion and 50% air-water cooling. In the lased experimental group, the laser was applied at energy of 250 mJ, 20 Hz frequency, and pulse duration of 100 μs. Results: Shear bond strengths and adhesive remnant index scores were statistically calculated. A highly significant difference of SBS between the non-lased control group and the lased experimental group was observed (p<0.000). A non-significant difference in ARI scores was observed when the non-lased control group was compared with the lased experimental group. Conclusion: It could be concluded that Er-YAG laser is effective in ceramic bracket debonding. This protocol promotes debonding without bracket fracture or enamel surface cracks or damage.

Influence of Defects at Bonding Interface on Stress Distributions in Monolithic Ceramic Crown / 医用生物力学

Objective To explore the effects of the interfacial debonding caused by water environment in the mouth and the interfacial defects between the crown and cement on stress distributions in all-ceramic crowns. Methods The three-dimensional solid model of lithium disilicate CAD/CAM crowns for the first mandibular molar was established. Seven debonding states between inferior surface of the crown and top surface of the cement (Stage 1-7) as well as two interfacial defects (Case I and II) were defined in finite element software ABAQUS. The bottom of nine models was completely constrained. For stress calculation, the 600 N vertical load was applied at occlusal surface via an analytical rigid hemisphere with the diameter of 5 mm. Results Under occlusal vertical load, the stress on interior of the crown and top surface of the cement was mainly distributed at the boundary of the debonding areas and margin of the defects. The first principle stress on interior of the crown did not exceed its ultimate tensile strength, but the maximum tensile stress of the cement exceeded its ultimate tensile strength, leading to cohesive failure in the cement. Conclusions The axial wall played a critical role in maintaining the principal tensile stress of the crown at a lower level. The defects at bonding interface between the crown and cement had a more significantly impact on load capacity of the crown than the increase in debonding areas. In order to improve load bearing capacities of all-ceramic crowns, attention should be paid to avoid defects in clinical prosthodontic practices.

Influence of Defects at Bonding Interface on Stress Distributions in Monolithic Ceramic Crown / 医用生物力学

Objective To explore the effects of the interfacial debonding caused by water environment in the mouth and the interfacial defects between the crown and cement on stress distributions in all-ceramic crowns. Methods The three-dimensional solid model of lithium disilicate CAD/CAM crowns for the first mandibular molar was established. Seven debonding states between inferior surface of the crown and top surface of the cement (Stage 1-7) as well as two interfacial defects (Case I and II) were defined in finite element software ABAQUS. The bottom of nine models was completely constrained. For stress calculation, the 600 N vertical load was applied at occlusal surface via an analytical rigid hemisphere with the diameter of 5 mm. Results Under occlusal vertical load, the stress on interior of the crown and top surface of the cement was mainly distributed at the boundary of the debonding areas and margin of the defects. The first principle stress on interior of the crown did not exceed its ultimate tensile strength, but the maximum tensile stress of the cement exceeded its ultimate tensile strength, leading to cohesive failure in the cement. Conclusions The axial wall played a critical role in maintaining the principal tensile stress of the crown at a lower level. The defects at bonding interface between the crown and cement had a more significantly impact on load capacity of the crown than the increase in debonding areas. In order to improve load bearing capacities of all-ceramic crowns, attention should be paid to avoid defects in clinical prosthodontic practices.

Evaluation of pain perception during orthodontic debonding of metallic brackets with four different techniques

Abstract Objective The aim of this study was to evaluate patients' pain levels during four different debonding procedures. The null hypothesis was that the pain perception of the patients undergoing four different debonding applications was not statistically significant different. Material and Methods One hundred and twenty orthodontic patients who underwent orthodontic debonding were included in this study. The patients were randomly divided into 4 groups according to technique used in the patients. Debonding groups were as follows: Group 1) Conventional debonding group, Group 2) Medication group (acetaminophen was given 1 hour before debonding), Group 3) Soft bite wax group, and Group 4) Soft acrylic bite wafer group. The patients' levels of anxiety and fear of pain were evaluated before debonding, and Numerical Rating Scale (NRS) was applied to evaluate their pain perception during debonding. Mann-Whitney U and Kruskal-Wallis tests were used to evaluate non-normally distributed data. Categorical data analysis were carried by chi-square and McNemar tests. The significance level was set at p<0.05. Results Anxiety scores of the patients were not statistically significant between both genders and debonding groups. In the quadrants in which the patients were perceived, the highest pain level was in the left side of the mandible. The teeth in which the highest pain level was perceived were the lower left and upper right lateral incisors. Although there was no statistically significant difference among the pain scores of the patients in each group, quadrant scores of female patients showed significant differences, being the lowest scores in the soft bite wax group. Conclusions Majority of the patients had no fear of pain before debonding. Pain levels of the patients in the conventional debonding group were not significantly different from those of the other groups, except quadrant scores of females in the soft bite wax group. The null hypothesis was accepted.

Debonding forces of different pads in a lingual bracket system

ABSTRACT Objective: To evaluate the shear bond strength of lingual orthodontic brackets with resin or metal pads, the location of bond failure and the adhesive remnant index (ARI). Methods: A total of 40 extracted upper premolars were randomly divided into two groups of 20 each: bonding with brackets having (1) pads with extended resin directly on the lingual surface of teeth, and (2) pads with metal custom base on the lingual surface of teeth. The debonding force was measured with an Instron universal testing machine. A Student's t-test was used to assess the difference between groups (α = 0.05). Results: The results showed a significant difference between the groups (p < 0.001). The shear bond strength of metal pads was significantly higher than resin pads. Conclusions: Within the limitations of this in vitro study, it was concluded that the bond strength of lingual brackets with metal pads was higher than that of brackets with composite resin pads, due to the metal part being a single unit and welded. The failure location in the region between the bracket and the resin pad affected a higher percentage of the resin pads than the metal pads.

RESUMO Objetivo: avaliar a resistência de união ao cisalhamento de braquetes ortodônticos linguais com pads em resina e metálicos, assim como os locais de ocorrência das falhas, além do Índice de Adesivo Remanescente (ARI). Métodos: 40 pré-molares superiores extraídos foram aleatoriamente divididos em dois grupos de 20 espécimes cada, para a colagem de braquetes com: 1) pads em resina, estendida diretamente na face lingual dos dentes; e 2) pads com base metálica customizada, na face lingual dos dentes. A força de descolagem dos braquetes foi mensurada por meio de uma máquina de ensaio universal (Instron). O teste t de Student foi utilizado para avaliar diferenças intergrupos (α = 0,05). Resultados: os resultados demonstram haver diferença significativa intergrupos (p < 0,001). A resistência de união ao cisalhamento dos pads metálicos foi significativamente maior em comparação aos pads em resina. Conclusões: dentro das limitações desse estudo in vitro, foi possível concluir que a resistência de união de braquetes linguais com pads metálicos foi superior à resistência de braquetes com pads em resina composta, uma vez que os pads metálicos customizados e os braquetes são fundidos, formando uma única unidade. A porcentagem de falhas de colagem na região entre o braquete e o pad foi maior para os pads em resina, em comparação aos pads metálicos.

Six-month bracket failure rate with a flowable composite: A split-mouth randomized controlled trial

ABSTRACT INTRODUCTION: The use of flowable composites as an orthodontic bonding adhesive merits great attention because of their adequate bond strength, ease of clinical handling and reduced number of steps in bonding. OBJECTIVE: The aim of this Randomized Controlled Trial was to comparatively evaluate over a 6-month period the bond failure rate of a flowable composite (Heliosit Orthodontic, Ivoclar Vivadent AG, Schaan) and a conventional orthodontic bonding adhesive (Transbond XT, 3M Unitek). METHODS: 53 consecutive patients (23 males and 30 females) who fulfilled the inclusion and exclusion criteria were included in the study. A total of 891 brackets were analyzed, where 444 brackets were bonded using Heliosit Orthodontic and 447 brackets were bonded using Transbond XT. The survival rates of brackets were estimated with the Kaplan-Meier analysis. Bracket survival distributions for bonding adhesives, tooth location and dental arch were compared with the log-rank test. RESULTS: The failure rates of the Transbond XT and the Heliosit Orthodontic groups were 8.1% and 6% respectively. No significant differences in the survival rates were observed between them (p= 0.242). There was no statistically significant difference in the bond failure rates when the clinical performance of the maxillary versus the mandibular arches and the anterior versus the posterior segments were compared. CONCLUSIONS: Both systems had clinically acceptable bond failure rates and are adequate for orthodontic bonding needs.

RESUMO INTRODUÇÃO: o uso de resinas compostas fluidas como agentes de cimentação em Ortodontia tem merecido grande atenção, em função de sua adequada capacidade adesiva, facilidade de uso clínico e número reduzido de etapas de colagem. OBJETIVO: o objetivo deste estudo randomizado controlado foi avaliar o índice de falhas nos 6 meses após a colagem com uma resina composta fluida (Heliosit Orthodontic, Ivoclar Vivadent AG, Schaan), em comparação com um adesivo ortodôntico convencional (Transbond XT, 3M Unitek). MÉTODOS: 53 pacientes consecutivos (23 homens e 30 mulheres) que se enquadravam nos critérios de inclusão adotados foram incluídos no presente estudo. No total, 891 braquetes foram analisados, sendo 444 colados com o Heliosit Orthodontic e 447 colados com o Transbond XT. As taxas de sobrevivência dos braquetes foram estimadas por meio da análise de Kaplan-Meier. As distribuições das taxas de sobrevivência dos braquetes em função do adesivo usado, do dente e da arcada dentária em questão foram comparadas por meio do teste de log-rank. RESULTADOS: os índices de falhas para os grupos Transbond XT e Heliosit Orthodontic foram, respectivamente, de 8,1% e 6%. Não foram observadas diferenças significativas entre os grupos quanto às taxas de sobrevivência dos braquetes (p= 0,242). Também não foram observadas diferenças estatisticamente significativas quanto aos índices de falhas quando se comparou a performance clínica nas arcadas dentárias superior e inferior, e nos segmentos anterior e posterior da boca. CONCLUSÕES: ambos os sistemas apresentaram índices de falhas clinicamente aceitáveis, podendo ser considerados adequados para a colagem ortodôntica.

Does the CO2 laser reduce bond strength in different types of ceramic brackets?

ABSTRACT OBJECTIVE: The aim of this study was to assess in vitro the influence of the CO2 laser and of the type of ceramic bracket on the shear bond strength (SBS) to enamel. METHODS: A total of 60 enamel test surfaces were obtained from bovine incisors and randomly assigned to two groups, according to the ceramic bracket used: Allure (A); Transcend (T). Each group was divided into 2 subgroups (n = 15): L, laser (10W, 3s); C, no laser, or control. Twenty-four hours after the bonding protocol using Transbond XT, SBS was tested at a crosshead speed of 0.5 mm/min in a universal testing machine. After debonding, the Adhesive Remnant Index (ARI) was evaluated at 10 x magnification and compared among the groups. Data were analyzed by one-way ANOVA, Tukey’s, Mann-Whitney’s and Kruskal-Wallis tests (α = 0.05). RESULTS: Mean SBS in MPa were: AL = 0.88 ± 0.84; AC = 12.22 ± 3.45; TL = 12.10 ± 5.11; TC = 17.71 ± 6.16. ARI analysis showed that 73% of the specimens presented the entire adhesive remaining on the tooth surfaces (score 3). TC group presented significantly higher SBS than the other groups. The lased specimens showed significantly lower bond strength than the non-lased groups for both tested brackets. CONCLUSION: CO2 laser irradiation decreased SBS values of the polycrystalline ceramic brackets, mainly Allure.

RESUMO OBJETIVO: o objetivo deste estudo foi avaliar in vitro a influência do laser de CO2 sobre a resistência ao cisalhamento da colagem (RCC) no esmalte dentário, usando diferentes tipos de braquetes cerâmicos. MÉTODOS: no total, 60 superfícies de esmalte de incisivos bovinos foram obtidas e aleatoriamente divididas em dois grupos, de acordo com o braquete cerâmico utilizado: Allure (A) e Transcend (T). Cada grupo foi dividido em dois subgrupos (n = 15): L, laser (10W, 3s); C, sem laser, ou controle. Vinte e quatro horas após a colagem dos braquetes com o sistema Transbond XT, foi realizado o teste de resistência ao cisalhamento, com velocidade de 0,5 mm/min, em máquina universal de ensaios mecânicos. Após a descolagem, o Índice de Remanescente de Adesivo (IRA) foi avaliado com aumento de 10X e comparado entre os grupos. Os dados foram analisados pelo ANOVA one-way, testes de Tukey’s, Mann-Whitney’s e Kruskal-Wallis (α = 0,05). RESULTADOS: as médias da RCC em MPa foram: AL = 0,88 ± 0,84; AC = 12,22 ± 3,45; TL = 12,10 ± 5,11; TC = 17,71 ± 6,16. A análise do IRA mostrou que 73% dos corpos de prova apresentaram todo o compósito remanescente aderido à superfície do esmalte (escore 3). O grupo TC apresentou valor significativamente maior de RCC do que os outros grupos. Os corpos de prova dos grupos com laser obtiveram valores adesivos significativamente menores do que os corpos de prova dos grupos sem laser, com ambos os tipos de braquetes. CONCLUSÃO: a irradiação com laser de CO2 diminuiu os valores de RCC dos braquetes policristalinos testados, principalmente do Allure.

Influence of Primekote® polymer in orthodontic bonding / Influência do polímero Primekote® na colagem ortodôntica

Objective: The Primekote® (TP) polymer was incorporated to the of Orthodontic Bracket mesh base to improve bond strength and make it more efficient. The purpose of this study was to assess the shear bond strength and adhesive remnant index (ARI) of these brackets. Material and method: The test sample consisted of thirty bovine incisors divided into 2 groups: with a group with TP® brackets (n=15), and a control group with Morelli® brackets (n=15) without Primekote® technology. The TransbondTM XT was used as adhesive system in both groups, following the same protocol and manufacturer’s instructions. Specimens were stored in distilled water for 24 hours and then submitted to shear bond strength test in a universal testing machine (EMIC DL2000). The assessment of ARI was performed under stereomicroscope by two calibrated examiners. Result: No significant differences (p>0.05) in shear bond strength were found between the two groups according to the independent t-test. The Wilcoxon test was used to assess ARI data and statistical difference was found between Morelli® and TP® Nu-Edge brackets; the last one left less remaining adhesive on tooth surface. Conclusion: TP® brackets had higher adherence to the adhesive system as shown by lower ARI scores, but this does not improve its clinical performance.

Objetivo: Avaliar a resistência ao cisalhamento e o índice de remanescente adesivo (IRA) dos bráquetes que tiveram o polímero Primekote® incorporado a suas bases. Material e método: Foram confeccionados trinta corpos de prova com incisivos bovinos, divididos em dois grupos: o colado com bráquete TP® Nu-Edge(n=15) e grupo controle com bráquetes Morelli® (n=15) sem tratamento na base. O sistema adesivo TransbondTM XT foi utilizado nos dois grupos seguindo o mesmo protocolo de colagem e respeitando as instruções do fabricante. Os corpos de prova foram armazenados em água destilada por 24 horas, e posteriormente submetidos ao teste de cisalhamento na máquina de ensaios universais (EMIC-DL2000). O IRA foi avaliado por dois examinadores calibrados utilizando lupa estereoscópica com aumento de 20 vezes. Resultado: Na resistência ao cisalhamento o teste T-independente mostrou não haver diferença estatisticamente significante entre os grupos (p>0,05), ambos tiveram desempenho semelhante. O teste Wilcoxon foi utilizado nos valores obtidos no IRA revelando diferença estatística, sendo que os bráquetes TP® deixaram menos remanescente adesivo na superfície dental que os bráquetes Morelli®. Conclusão: Bráquetes TP® apresentaram maior adesão ao sistema adesivo pois foi encontrado menor IRA nos mesmos, porém esta característica não reflete em melhora no desempenho clínico.

Avaliação do esmalte dental na remoção de resíduos resinoso fluorescente com diferentes fontes luminosas / EvaluaLon of dental enamel in the removal of fluorescent resin residues with different light sources

Objetivo: Avaliar através de simulação clínica a efetividade da remoção de resíduos fluorescentes do esmalte dental bovino, após remoção de bráquetes ortodônticos, utilizando dispositivos emissores de luz branca e fluorescente. Materiais e Métodos: 180 dentes bovinos anteriores hígidos foram seccionados em discos de esmalte/dentina. A remoção do material resinoso cimentante foi realizada por três operadores. Os dentes foram divididos em quatro grupos de estudo. Os fatores em estudo foram: a fonte de iluminação empregada durante a remoção dos materiais resinosos cimentantes de bráquetes ortodônticos em 4 níveis (n = 45): Convencional (C), LED branco (W), LED fluorescente (F) e fotopolimerizador com filtro fluorescente (FL). Foram consideradas como variáveis de resposta: o tempo para remoção dos resíduos das amostras; a área de remanescente resinoso fluorescente superficial e a mensuração da altura de material adesivo fluorescente remanescente (PICO) e a profundada de esmalte desgastado (VALE). Na comparação entre as técnicas empregou-se o teste Kruskal-Wallis seguido do pós-teste Mann-Whitney U (P≤0,05). Resultados: As Técnicas F e FL apresentaram-se, estatisticamente, semelhantes e as menores medianas de tempo consumido para a remoção do resíduo resinoso. As técnicas C e W apresentaram estatisticamente, a presença de maiores e semelhantes medianas de áreas fluorescentes remanescentes e de PICO (altura do remanescente), com relação as técnicas F e FL; enquanto que as técnicas FL e F postaram, estatisticamente, uma maior mediana de VALE que a técnica C. Conclusões: A associação de emissor de luz fluorescente com um material resinoso fluorescente, colaborou significativamente e de forma eficaz, na redução do tempo consumido para remoção e evidenciação dos resíduos resinosos cimentantes fluorescentes, possibilitando uma remoção efetiva, após a remoção dos bráquetes ortodônticos(AU)

Objective: Evaluate, through clinical simulation, the effectiveness on the removal of fluorescent resin residues from bovine dental enamel after brackets debonding using white and fluorescent light emitting devices. Materials and Methods: 180 healthy anterior bovine teeth were sectioned on enamel / dentin disks. The removal of the resinous material was performed by three operators. The teeth were divided into four groups. The factors studied were: the light source used to remove orthodontic resin residue in 4 levels (n = 45): Conventional (C), white LED (W), fluorescent LED (F) and photocuring unit with Fluorescent filter (FL). Response variables were: the time spent to remove the sample residues; The surface area of the fluorescent remaining resin and the depth measurement of the remaining fluorescent adhesive thickness (PEAK) and the enamel thickness removed (VALLEY). In the comparison between the techniques, the Kruskal-Wallis test was used, followed by the Mann-Whitney U post-test (P≤0.05). Results: In terms of time, the groups F and FL were similar to each other and statistically different for groups C and W. The techniques C and W presented statistically, the presence of larger and similar medians of remaining fluorescent areas, in relation to the F and FL techniques. The techniques C and W presented, statistically, a larger and similar median of peaks than the F and FL techniques. The FL technique statistically demonstrated a higher median of valleys than the C technique. The W, F and FL techniques were statistically similar to each other, as were C and W techniques. Conclusions: Fluorescent light with a fluorescent resinous material, significantly and effectively collaborated in the reduction of the time consumed for evidencing and removal of fluorescent resin residues, allowing an efficient removal after removal of orthodontic brackets(AU)

Evaluación de la superficie del esmalte luego de la descementación de brackets metálicos. Revisión sistemática / Enamel Surface Assessment after Metallic Bracket Debonding. A Systematic Review

Antecedentes: A través del tiempo se han propuesto diferentes técnicas para realizar la remoción del adhesivo y resina remanentes luego de retirar los brackets, pero no existe un consenso entre los diferentes autores. Objetivo: el propósito de esta revisión sistemática fue identificar cuál es la técnica más adecuada para evitar injuria al esmalte durante la remoción de la resina remanente después de retirados los brackets. Métodos: Esta revisión sistemática se basó en los lincamientos de PRISMA, Para recolectar la evidencia publicada se realizó una búsqueda electrónica en diferentes bases de datos. Resultados: Se encontraron 8 artículos con una evidencia media (> de 9) los cuales fueron considerados en esta revisión sistemática. Al parecer la remoción de resina y adhesivo remanentes con ultrasonido, fresa de carburo de tungsteno de alta velocidad y piedras blancas generan la mayor pérdida de esmalte, mientras que 6 artículos proponen la fresa de tungsteno de baja velocidad como la mejor técnica. Conclusiones: Se requieren estudios aleatorizados, con grupo control, doble-ciego y una técnica de análisis del esmalte estandarizada para poder generar un nivel de evidencia alto y dar recomendaciones más acertadas para el clínico.

Background: Over time different techniques have been proposed for the removal of the remaining adhesive and resin after the removal of brackets, but there is no consensus among authors. Objective: Evaluate the most appropriate technique to prevent injury to the enamel during the removal of the remaining resin after the brackets are removed. Methods: This systematic review is based on the guidelines of PRISMA, to collect the published evidence there was a various electronic databases search. Results: There were only 8 items with medium evidence (> 9) which were considered in this systematic review. Apparently removing remaining adhesive resin with ultrasound, tungsten carbide cutter high speed and white stones generate the greatest loss of enamel, while 6 articles propose the tungsten bur at low speed as the best technique. Conclusions: Randomized studies with control group, double-blind and a standardized technique of enamel analysis are required to generate a high level of evidence and give more accurate recommendations for clinicians.