Abstract: Orthodontic bonding systems are submitted to demineralization and remineralization dynamics that might compromise their surface smoothness, and favor biofilm aggregation and caries development. The aim of the present study was to evaluate the effects of a cariogenic challenge model (in vitro pH-cycling model) on the surface roughness and topography of 3 bonding materials: Transbond™ XT (XT), Transbond™ Plus Color Change (PLUS) and Fuji Ortho™ LC (FUJI), by means of Atomic Force Microscopy (AFM). Six specimens with standardized dimensions and surface smoothness were fabricated per group, and the materials were manipulated in accordance with the manufacturers' instructions. No polishing was necessary. AFM tests were performed before and after pH-cycling, taking 3 readouts per specimen. The roughness results (Ra) were obtained at nanometric levels (nm) and surface records were acquired in two- and three-dimensional images of height and lock-in phase of the material components. The surfaces of all groups analyzed in the study were morphologically altered, presenting images suggestive of matrix degradation and loss of matrix-load integrity. FUJI presented the greatest increase in surface roughness, followed by XT and PLUS, respectively (p≤0.001). Nevertheless, the roughness values found did not present sufficient degradation to harbor bacteria. The surface roughness of all tested materials was increased by pH-cycling. The use of materials capable of resisting degradation in the oral environment is recommended, in order to conserve their integrity and of the surrounding tissues.

OBJETIVO: avaliar a influência da contaminação salivar na resistência estrutural e integridade de cimentos de ionômero de vidro convencionais utilizados para cimentação de bandas ortodônticas na ausência e na presença de um verniz protetor de superfície. MÉTODOS: quarenta e oito corpos de prova foram confeccionados a partir de três cimentos ortodônticos, com auxílio de matrizes metálicas padronizadas com 10mm de diâmetro e 2mm de altura. Os cimentos utilizados foram: Meron (Voco), Ketac-Cem (3M ESPE) e Vidrion C (DFL), compondo os grupos A, B e C, respectivamente. Metade dessas amostras não recebeu nenhum tipo de proteção superficial, constituindo os subgrupos A1, B1 e C1, enquanto, os subgrupos A2, B2 e C2 tiveram suas superfícies isoladas com verniz Cavitine (SS White) após manipulação e aplicação do cimento, com intuito de proteger a superfície do cimento. As amostras foram armazenadas em saliva artificial por 24 horas a 37ºC. Foi realizado um ensaio de microdureza (Vickers) para avaliação da dureza de superfície do grupo não-tratado (sem isolamento) e do grupo tratado (agente protetor). RESULTADOS: os materiais previamente isolados com o verniz obtiveram valores de microdureza significativamente maiores que os não-isolados. O cimento Ketac-Cem apresentou, estatisticamente, a maior microdureza entre os materiais protegidos. CONCLUSÃO: o isolamento com verniz mostrou-se necessário para preservação do cimento e, consequentemente, de sua capacidade de evitar possíveis desmineralizações dentárias. Os cimentos de ionômero de vidro devem ser protegidos para manutenção de sua integridade, contribuindo para saúde dental durante o tratamento ortodôntico.

OBJECTIVE: The aim of the present study was to assess the influence of saliva contamination over the structural strength and integrity of conventional glass-ionomer cements used for cementing orthodontic bands in the absence and presence of a surface-protecting varnish. METHOD: 48 samples were prepared by inserting 3 types of glass-ionomer cements into standardized metallic matrixes of 10 mm of diameter and 2 mm of depth. The cements used were: Meron (VOCO), Ketac-Cem (3M ESPE) and Vidrion C (DFL), all of which comprised groups A, B and C, respectively. Subgroups A1, B1 and C1 comprised samples with no surface protection, whereas subgroups A2, B2 and C2 comprised samples of which surface was coated with Cavitine varnish (SS White), after cement manipulation and application, in order to protect the cement applied. All samples were stored in artificial saliva for 24 hours at 37ºC. A Vickers diamond micro-durometer was used to produce indentations on the non-treated group (non-varnished) and the treated group (varnished). RESULTS: Varnished materials had significantly higher microhardness values in comparison to non-varnished materials. Ketac-Cem had the highest microhardness value among the varnished materials. CONCLUSION: Varnish application is necessary to preserve the cement and avoid enamel decalcification. Glass-ionomer cements should be protected in order to fully keep their properties, thus, contributing to dental health during orthodontic treatment.

OBJECTIVE: The aim of this study was to evaluate the antimicrobial and fluoride releasing capacity of 3 bonding materials. MATERIAL AND METHODS: Thirty nine specimens with standardized surface smoothness and dimensions were prepared. The antimicrobial capacity of the materials against S. mutans, L. casei and C. albicans was evaluated by determining the percentage of growth inhibition of these microorganisms in an inoculated medium, obtained by optical density readouts on a spectrophotometer. The potential to interfere in microbial growth on the surface of the studied materials was observed by means of scanning electron microscopy (SEM). The fluoride release capacity in ultrapure water for 14 days was analyzed by means of ion chromatography. RESULTS: The PLUS group presented the highest percentage of microbial inhibition and the most contamination-free surface. The FUJI group presented the best fluoride release capacity. CONCLUSIONS: The TransbondTM Plus Color Change was the one that presented the best general behavior considering the evaluated aspects.

O objetivo do presente estudo foi avaliar o efeito do flúor na prevenção da erosão do esmalte circunjacente a braquetes ortodônticos sob desafio erosivo. Braquetes edgewise foram colados com resina TransbondTM XT na superfície vestibular de 40 incisivos bovinos. Os dentes foram divididos em 4 grupos (n = 10): G1: Saliva remineralizadora; G2: Desafio erosivo; G3: Grupo experimental submetido à aplicação tópica de flúor gel neutro (NaF a 2%) antes do desafio erosivo; G4: Grupo experimental submetido à três aplicações diárias de dentifrício fluoretado (1500 ppmF PFM) durante o desafio erosivo. Após 14 dias de desafio erosivo, foi realizado exame visual e táctil por dois examinadores calibrados e treinados (Kappa = 0,867). Os escores utilizados foram: 0 = Esmalte hígido, 1 = Esmalte desmineralizado sem cavidade, 2 = Esmalte desmineralizado com cavidade, 3 = Esmalte remineralizado sem cavidade, 4 = Esmalte remineralizado com cavidade. Foram utilizados os testes de Kruskal-Wallis e Mann-Whitney para determinar os níveis de erosão, estabelecendo um intervalo de confiança de 95% (p<0,05). O G2 e G3 apresentaram 100% de grau 2, com grandes cavidades, apresentando superfície rugosa e opaca. O G4 apresentou 50% de escore 3 e 50% de escore 4. Considerando as condições estudadas, verificou-se uma diferença significativa entre G2 e G4 e entre G3 e G4 (p<0,01). Diferentemente da aplicação única de gel fluoretado neutro, a elevada frequência de utilização de dentifrício com flúor em baixa concentração apresentou grande influência durante a dinâmica de erosão.

The aim of the present study was to evaluate the effect of fluoride in prevention of tooth erosion around orthodontic brackets under erosive challenge. Edgewise brackets were bonded with TransbondTM XT composite on vestibular surface of 40 bovine incisors. The teeth were assigned to 4 groups (n=10): G1: Remineralizing saliva; G2: Erosive challenge; G3: Experimental group submitted to topical application of neutral fluoride gel (2% NaF) before erosive challenge; G4: Experimental group submitted to three daily applications of fluoride dentifrice (PFM 1500 ppmF) during erosive challenge. After 14 days of erosive challenge, direct visual and tactile examination were performed by two calibrated and trained examiners (Kappa = 0.867). The following scores were used: 0 = Intact enamel, 1 = Demineralized enamel without cavity, 2 = Demineralized enamel with cavity, 3 = Remineralized enamel without cavity, 4 = Remineralized enamel with cavity. Kruskal-Wallis and Mann-Whitney tests were applied to determine erosion levels, establishing a confidence interval of 95% (p<0.05). G2 and G3 presented 100% of score 2, with large cavities, presenting rough and opaque surface. G4 showed 50% of score 3 and 50% of score 4. Considering the studied conditions, it was found a significant difference between G2 and G4 and between G3 and G4 (p<0.01). By contrast to single application of neutral fluoride gel, the high frequency of use of fluoride at low concentration had a great influence during the dynamics of erosion.

The aim of this study is to assess the in vitro shear bond strength and adhesive remnant index (ARI) of one and two-step fluoridated orthodontic resins under conditions that simulate high cariogenic challenge. Edgewise brackets for maxillary central incisors were randomly bonded to 80 bovine incisors, using either TransbondTM Plus Color Change orthodontic resin and a self-etching primer adhesive (G1; n = 40) or Orthodontic Fill Magic with a conventional acid-etch technique (G2; n = 40). Each group of resin (n = 10) was divided into: immediate shear (A- pre-cycling control), immersion in artificial remineralizing saliva (neutral saliva) for 14 days (B- post-cycling control) and pH cycling with high cariogenic challenge (C- acid saliva with pH 5.5 and D- acid saliva with pH 4.5). After 14 days of pH cycling, the shear bond strength and ARI were evaluated. Considering the shear bond strength, TransbondTM Plus Color Change resin was stronger than Orthodontic Fill Magic when it was submitted to high cariogenic challenge (p < 0.05). Also TransbondTM Plus Color Change resin showed better adhesion to enamel than Orthodontic Fill Magic, in all situations evaluated (p < 0.05). It could be concluded that TransbondTM Plus Color Change resin presented better shear bond strength and adhesive remnant index when submitted to high cariogenic challenge, in comparison with Orthodontic Fill Magic.

O objetivo do presente estudo foi avaliar in vitro o efeito preventivo a cárie de resinas ortodônticas fluoretadas submetidas à ciclagem de pH utilizando dois tipos de saliva desmineralizadora. Bráquetes de incisivos centrais foram colados em 60 incisivos bovinos, utilizando a resina ortodôntica Transbond Plus Color Change (n=30) ou Fill Magic (n=30). Cada grupo foi dividido em 3 subgrupos (n=10): imersão em saliva artificial remineralizante por 14 dias e simulação de alto desafio cariogênico com ciclagem de pH em saliva ácida com pH 5,5 ou pH 4,5. Após 14 dias de ciclagem de pH, o efeito preventivo de cárie foi avaliado por meio da formação de halo de inibição da mancha branca, adotando-se os escores: 0-ausência e 1-presença. Os testes Kruskal Wallis e Man-Whitney (a=0,05) foram aplicados. A formação de lesões de mancha branca foi observada somente na ciclagem de pH com saliva ácida a pH 4,5; sendo o Transbond Plus Color Change significantemente mais efetivo na prevenção ao desenvolvimento de mancha branca quando comparados ao Fill Magic (p<0,05). O pH da solução desmineralizante influenciou na formação de lesões de mancha branca circunjacentes aos bráquetes em condições de alto desafio cariogênico. A Transbond Plus Color Change apresentou maior efeito preventivo de cárie em relação ao Fill Magic.

The aim of the present study was to evaluate the in vitro caries preventive effect of fluoridated orthodontic resins under pH cycling with two types of acid demineralizing saliva. Brackets were bonded to 60 bovine incisors, using either Transbond Plus Color Change (n=30) or Orthodontic Fill Magic (n=30) orthodontic resins. Each group of resin was divided into 3 subgroups (n=10): immersion in remineralizing artificial saliva for 14 days, pH cycling with high cariogenic challenge in acid saliva with pH 5.5, and acid saliva with pH 4.5. After 14 days of pH cycling, the caries preventive effect on the development of white spot lesion was evaluated considering the presence of inhibition zones to white spot lesions using two scores: 0= absence and 1= presence. Kruskal Wallis and Mann-Whitney tests (a=0.05) were used. Formation of white spot lesions was observed only under pH cycling using acid saliva with pH 4.5; with Transbond Plus Color Change being significantly more effective (p<0.05) in preventing the appearance of white spot lesions effect than Orthodontic Fill Magic. The acidity of the demineralizing solution influenced the formation of white spot lesions around orthodontic brackets under highly cariogenic conditions. Transbond Plus Color Change resin presented higher caries preventive effect than Orthodontic Fill Magic.