Laboratory model to evaluate the influence of stress and corrosion in the formation of non-carious cervical lesions

Objetivo: Idealizar e testar um modelo laboratorial para simulação da etiologia multifatorial de lesões cervicais não cariosas, que permita avaliar o desenvolvimento dessas lesões com níveis crescentes de complexidade, com ênfase na tensão e na corrosão, visando contribuir com o esclarecimento dos mecanismos que conduzem à sua formação. Métodos: Os corpos de prova foram construídos com incisivos bovinos cortados na forma de palitos com 18 × 3 × 3 mm, com um entalhe na região cervical da parede voltada para a polpa, a fi m de concentrar as tensões na superfície da junção cemento-esmalte quando engastados no extremo apical e carregados em dobramento no extremo incisal. Um grupo foi imerso em água destilada e outro em solução tampão de acetato pH 4,5 durante 72 h. Cada grupo foi dividido em três subgrupos: sem carga e com carga (800 gf) para provocar tração ou para provocar compressão. Após o ensaio, os espécimes foram processados para histologia em lamelas de 0,05 mm, fotografados em microscópio de luz, e os danos foram avaliados. Conclusão: O modelo laboratorial desenvolvido permite a medida precisa da profundidade de perda e desmineralização de tecido dentário de corpos de prova submetidos ou não à tensão, bem como observar a ocorrência de outros danos como trincas e fraturas, o que torna possível inferir a influência da tensão de tração e compressão na etiologia das lesões cervicais não cariosas. O modelo poderá ser futuramente enriquecido com a possibilidade de aplicação cíclica de cargas e desafi os abrasivos intercalados.Objective: To conceive and test a laboratory model that simulates the multifactorial etiology of non-carious cervical lesions. The model enables researchers to assess the pathological process with increasing levels of complexity, focusing on tension and corrosion. The model is aimed at clarifying the mechanisms that lead to the development of these lesions. Methods: Specimens were manufactured from bovine incisors cut into 18 × 3 × 3 mm sticks, with a notch in the cervical region facing the pulp, in order to concentrate the stresses on the surface of the cementum-enamel junction when fi xed at the apical end and loaded for bending on the incisal edge. One group was immersed in distilled water and the other in pH 4.5 acetate buffer for 72 h. Each group was divided into three subgroups: one subgroup without loading, and two subgroups submitted to loading (800 gf) to cause either compression or tensile stress. After the test, 0.05 mm histological lamellae of the specimens were processed and photographed using a light microscope, and the damages were assessed. Conclusion: The laboratory model that was developed enabled the precise measurement of the depth of loss and demineralization of tooth tissue in the specimens, whether submitted to stress or not. The formation of other damages, such as cracks and fractures, could also be observed; this made it possible to infer the infl uence of compressive and tensile stresses on the etiology of non-carious cervical lesions. The model can be further enhanced by making it possible to apply cyclic loads and interspersed abrasive challenges

The effect of photoactivation technics in the marginal adaptation and Knoop hardness of a restorative when used three light curing units

Orientador: Lourenço Correr SobrinhoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O objetivo deste estudo foi avaliar a adaptação marginal e a dureza Knoop da resina Filtek Z250, cor A2 (3M-ESPE) utilizada para restaurar 90 cavidades, com margens em dentina, confeccionadas na face vestibular de incisivos bovinos, empregando três técnicas e três métodos de fotoativação. As cavidades foram padronizadas com dimensões de 3mm no sentido mesio-distal; 3mm no sentido inciso-cervical e 1,5mm de profundidade. Os grupos, com 10 restaurações cada, foram divididos de acordo com a técnica de fotoativação: direta; transdental ou mista, e método de fotoativação, que correspondem a variações na fonte de luz: halógena com 600mW/cm² (XL 2500/3M), arco de plasma de xenônio com 1340mW/cm² (Apollo 95E/DMD) e LED com 500mW/cm² (Ultrablue IS/DMC). Os tempos para cada etapa de fotoativação foram estabelecidos em 20s para os aparelhos fotoativadores Ultrablue IS e XL 2500 e 9s para o Apollo 95E. A análise da adaptação marginal foi realizada em fotos digitais, obtidas das superfícies das restaurações, após 24 horas de armazenagem, polimento padronizado e pigmentação com vermelho ácido a 1% em propileno glicol (Caries Detector- Kuraray). Foi utilizado o programa analisador de imagens, UTHSCSA - Image Tool, tendo como referência a medida de 1mm de um paquímetro digital (Mitutoyo, Japão) escaneado junto com cada restauração. As medidas de dureza Knoop foram obtidas no topo e na base da restauração, usando o microdurômetro HMV 2 (Shimadzu-Japão) com carga de 50 gramas atuando por 15 segundos. Em cada corpo-de-prova foram feitas seis endentações. Os dados foram submetidos à Análise de Variância e as médias comparadas pelo teste de Tukey (5%) e mostraram que independente do tipo de unidade fotoativadora, o emprego da técnica mista reduziu o percentual de fendas entre o material restaurador e o dente, determinando melhor adaptação marginal em relação à técnica direta, sendo que a técnica transdental não diferiu estatisticamente das demais. A adaptação marginal não foi influenciada pelas diferentes unidades de fotoativação utilizadas neste estudo, quando comparadas dentro da mesma técnica. A técnica de fotoativação direta apresentou as maiores médias de dureza em relação à mista e transdental, sendo que a transdental apresentou os menores valores de dureza. Independente da técnica de fotoativação empregada, o aparelho LED (Ultrablue IS) apresentou os maiores valores de dureza em relação ao Apollo 95E. Nenhuma diferença estatística foi observada nos valores de dureza Knoop entre os aparelhos LED e XL 2500 e XL 2500 e Apollo 95EAbstract: The aim of this study was to evaluate marginal adaptation and Knoop hardness of the resin Filtek Z250 A2 (3M-ESPE). Ninety cavities, with margins in dentine, in the vestibular face of incisive bovine teeth were restored using three techniques and three photoactivation methods. The cavities were standardized with dimensions: 3mm mesio-distal; 3mm incisive-cervical, and 1.5mm deep. The groups, with 10 restorations each, were divided according to the photoactivation technique: direct; transdental or mixed, and method of photoactivation that correspond to variations in the light source: halogen light with 600mW/cm² (XL 2500/3M), xenon plasma arc with 1340 mW/cm² (Apollo 95E/DMD) and LED with 500mW/cm² (Ultrablue IS/DMC). The periods for each photoactivation stage were established in 20s for the units Ultrablue IS and XL 2500 and 9 s for the Apollo 95E. Marginal adaptation analysis was carried out in digital photografy, obtained from the surfaces of restorations, 24 hours after storage, with standard polish and with red acid pigmentation at 1% in propylene glycol (Cáries Detector - Kuraray). The program image analyzer, UTHSCSA - Image Tool was used , having as reference the measure of 1mm of a digital caliper (Mitutoyo, Japan) scanned with each restoration. The measures of Knoop hardness were obtained on the top and on the base of the restoration, using the microhardness unit HMV 2 (Shimadzu-Japan) with load of 50 grams for 15 seconds. In each specimen were made six indentations. The data were submitted to the Analysis of Variance and the averages compared by Tukey's test (5%) and showed that independent of the type of photoactivating unit the use of the mixed technique reduced the percentile of gaps between the restoring material and the tooth, determining better marginal adaptation in relation to the direct technique. The transdental technique did not differ statistically from the others. The marginal adaptation was not influenced by the different photoactivation units used in this study, when compared inside the same technique. The technique of direct photoactivation showed the highest averages of hardness in relation to the mixed and transdental ones, and the transdental presented the lowest hardness values. Independent of the photoactivation technique used, the Ultrablue IS nit presented the highest hardness values in relation to Apollo 95E. No statistical difference was observed on hardness values between the units Ultrablue IS and XL 2500 and XL 2500 and Apollo 95EDoutoradoMateriais DentariosDoutor em Materiais Dentário

Randomized clinical trial of the effect of NovaMin and CPP-ACPF in combination with dental bleaching

Objective This randomized, controlled, double-blind clinical study evaluated the effect of calcium sodium phosphosilicate (NovaMin) and casein phosphopeptide-amorphous calcium phosphate with fluoride (CPP-ACPF) on the prevention of post-operative sensitivity and on the effects of clinical bleaching treatment. Material and Methods Sixty volunteers were selected according to inclusion and exclusion criteria and were randomly assigned into three groups (n=20): CG (control group) patients, who were treated with 35% hydrogen peroxide; NOVAG (NovaMin group) patients, who were treated with 35% hydrogen peroxide followed by the application of NovaMin; and CPPG (CPP group) patients, who were treated with 35% hydrogen peroxide followed by the application of CPP-ACPF. Both bioactive agents were applied for five minutes. An evaporative stimulus associated with a modified visual scale was used to analyze sensitivity 24 hours after each bleaching session. The color evaluation was performed on the maxillary central incisors using a spectrophotometer. Associations between the intervention group, bleaching session, and reported sensitivity were tested using Chi-square partitioning. Results Color change values (ΔE) were analyzed using analysis of variance (ANOVA). The significance level used for both tests was 5%. In the intragroup assessment, the Friedman test showed that only the CPP-ACPF group showed no statistically significant difference (p<0.05) between baseline and first bleaching session. In the intergroup assessment, the Kruskal–Wallis test showed that the CPPG had less postoperative sensitivity after the first session, when compared to the other groups (p<0.05). Color change analysis (ΔE) showed a significant difference between the means obtained in the different bleaching sessions in all groups (p<0.05). Conclusions This study showed that the combination of CPP-ACPF with 35% hydrogen peroxide significantly reduced post-operative sensitivity in the first session, compared with the other evaluated treatments. The association of CPP-ACPF and NovaMin did not affect the color change induced by tooth bleaching

Randomized clinical trial of the effect of NovaMin and CPP-ACPF in combination with dental bleaching

Abstract Objective This randomized, controlled, double-blind clinical study evaluated the effect of calcium sodium phosphosilicate (NovaMin) and casein phosphopeptide-amorphous calcium phosphate with fluoride (CPP-ACPF) on the prevention of post-operative sensitivity and on the effects of clinical bleaching treatment. Material and Methods Sixty volunteers were selected according to inclusion and exclusion criteria and were randomly assigned into three groups (n=20): CG (control group) patients, who were treated with 35% hydrogen peroxide; NOVAG (NovaMin group) patients, who were treated with 35% hydrogen peroxide followed by the application of NovaMin; and CPPG (CPP group) patients, who were treated with 35% hydrogen peroxide followed by the application of CPP-ACPF. Both bioactive agents were applied for five minutes. An evaporative stimulus associated with a modified visual scale was used to analyze sensitivity 24 hours after each bleaching session. The color evaluation was performed on the maxillary central incisors using a spectrophotometer. Associations between the intervention group, bleaching session, and reported sensitivity were tested using Chi-square partitioning. Results Color change values (ΔE) were analyzed using analysis of variance (ANOVA). The significance level used for both tests was 5%. In the intragroup assessment, the Friedman test showed that only the CPP-ACPF group showed no statistically significant difference (p<0.05) between baseline and first bleaching session. In the intergroup assessment, the Kruskal–Wallis test showed that the CPPG had less postoperative sensitivity after the first session, when compared to the other groups (p<0.05). Color change analysis (ΔE) showed a significant difference between the means obtained in the different bleaching sessions in all groups (p<0.05). Conclusions This study showed that the combination of CPP-ACPF with 35% hydrogen peroxide significantly reduced post-operative sensitivity in the first session, compared with the other evaluated treatments. The association of CPP-ACPF and NovaMin did not affect the color change induced by tooth bleaching

Modelo laboratorial para avaliar a infl uência da tensão e da corrosão na formação de lesões cervicais não cariosas

Objective: To conceive and test a laboratory model that simulates the multifactorial etiology of non-carious cervical lesions. The model enables researchers to assess the pathological process with increasing levels of complexity, focusing on tension and corrosion. The model is aimed at clarifying the mechanisms that lead to the development of these lesions. Methods: Specimens were manufactured from bovine incisors cut into 18 × 3 × 3 mm sticks, with a notch in the cervical region facing the pulp, in order to concentrate the stresses on the surface of the cementum-enamel junction when fi xed at the apical end and loaded for bending on the incisal edge. One group was immersed in distilled water and the other in pH 4.5 acetate buffer for 72 h. Each group was divided into three subgroups: one subgroup without loading, and two subgroups submitted to loading (800 gf) to cause either compression or tensile stress. After the test, 0.05 mm histological lamellae of the specimens were processed and photographed using a light microscope, and the damages were assessed. Conclusion: The laboratory model that was developed enabled the precise measurement of the depth of loss and demineralization of tooth tissue in the specimens, whether submitted to stress or not. The formation of other damages, such as cracks and fractures, could also be observed; this made it possible to infer the infl uence of compressive and tensile stresses on the etiology of non-carious cervical lesions. The model can be further enhanced by making it possible to apply cyclic loads and interspersed abrasive challenges.Objetivo: Idealizar e testar um modelo laboratorial para simulação da etiologia multifatorial de lesões cervicais não cariosas, que permita avaliar o desenvolvimento dessas lesões com níveis crescentes de complexidade, com ênfase na tensão e na corrosão, visando contribuir com o esclarecimento dos mecanismos que conduzem à sua formação. Métodos: Os corpos de prova foram construídos com incisivos bovinos cortados na forma de palitos com 18 × 3 × 3 mm, com um entalhe na região cervical da parede voltada para a polpa, a fi m de concentrar as tensões na superfície da junção cemento-esmalte quando engastados no extremo apical e carregados em dobramento no extremo incisal. Um grupo foi imerso em água destilada e outro em solução tampão de acetato pH 4,5 durante 72 h. Cada grupo foi dividido em três subgrupos: sem carga e com carga (800 gf) para provocar tração ou para provocar compressão. Após o ensaio, os espécimes foram processados para histologia em lamelas de 0,05 mm, fotografados em microscópio de luz, e os danos foram avaliados. Conclusão: O modelo laboratorial desenvolvido permite a medida precisa da profundidade de perda e desmineralização de tecido dentário de corpos de prova submetidos ou não à tensão, bem como observar a ocorrência de outros danos como trincas e fraturas, o que torna possível inferir a influência da tensão de tração e compressão na etiologia das lesões cervicais não cariosas. O modelo poderá ser futuramente enriquecido com a possibilidade de aplicação cíclica de cargas e desafi os abrasivos intercalados

Effect of the casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF) and photobiomodulation (PBM) on dental hypersensitivity: A randomized controlled clinical trial.

ObjectiveThis randomized controlled clinical trial aimed to evaluate the effect of the casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF) and photobiomodulation (PBM) in the treatment of dentin hypersensitivity (DH), and the impact of this on the health-related quality of life (HRQL).MethodsEighty teeth with DH were randomized into four groups and received three treatment sessions: PLACEBO = placebo + LASER application mimicking; CPP-ACPF = CPP-ACPF + LASER application mimicking; PBM = placebo + LASER active application; CPP-ACPF+PBM = CPP-ACPF + LASER active application. Tactile (exploratory probe) and evaporative (triple syringe) stimuli were used to measure DH and were recorded with the aid of a visual analogue scale (VAS) after the 1st, 2nd and 3rd treatment sessions and one-month follow-up. The HRQL was recorded in the DH experience questionnaire (DHEQ).ResultsThe intragroup comparison showed a significant reduction in DH (p ConclusionAfter one-month follow-up, the association of CPP-ACPF with PBM was effective in the reduction of DH and promoted a positive impact on the HRQL of the participants of this study