ABSTRACT
Abstract Patients undergoing radiotherapy treatment present more susceptibility to dental caries and the use of an orthodontic device increases this risk factor due to biofilm accumulation around the brackets. The objective of this study was to evaluate the shear bond strength to irradiated permanent teeth of orthodontic brackets bonded with conventional glass ionomer cement and resin-modified glass ionomer cement due to the fluoride release capacity of these materials. Ninety prepared human premolars were divided into 6 groups (n=15), according to the bonding material and use or not of radiation: CR: Transbond XT composite resin; RMGIC: Fuji Ortho LC conventional glass ionomer cement; GIC: Ketac Cem Easymix resin-modified glass ionomer cement. The groups were irradiated (I) or non-irradiated (NI) prior to bracket bonding. The specimens were subjected to a fractioned radiation dose of 2 Gy over 5 consecutive days for 6 weeks. After the radiotherapy, the brackets were bonded on the specimens with Transbond XT, Fuji Ortho LC and Ketac Cem Easymix. After 24 h, the specimens were subjected to shear bond strength test. The image of enamel surface (classified by Adhesive Remnant Index - ARI) was also evaluated and its frequency was checked among groups/subgroups. The shear bond strength variable was evaluated with ANOVA and Tukey's post-hoc test. GIC group showed the lowest adhesion values among the groups (p<0.05). There was no statistically significant difference among non-irradiated and irradiated groups (p>0.05). As for the ARI, the CR-I group showed the highest material retention on enamel surface among the irradiated groups. RMGIC group showed the highest values for shear bond strength and presented ARI acceptable for clinical practices.
Resumo Pacientes submetidos a tratamento radioterápico apresentam maior suscetibilidade à cárie dentária e o uso de aparelho aumenta esse fator de risco devido ao acúmulo de biofilme dental ao redor dos bráquetes. Assim, o objetivo deste estudo foi avaliar a resistência ao cisalhamento de bráquetes ortodônticos colados com cimento de ionômero de vidro convencional (CIV) e o modificado por resina (CIVMR), devido à capacidade de liberação de flúor desse material em dentes permanentes irradiados. Noventa pré-molares humanos foram divididos em 6 grupos (n=15), de acordo com o materila de colagem e com o uso ou não de radiação: RC: Transbond XT; CIVMR: Fuji Ortho LC; RMGIC: Ketac Cem Easymix. Os grupos for irradiados (I) ou não-irradiados (NI) previamente à colagem dos bráquetes. Os espécimes foram submetidos a doses fracionadas de radiação de 2 Gy/dia, durante 5 dias consecutivos, por 6 semanas. Depois da termociclagem e radioterapia, os bráquetes foram colados sobre os espécimes com Transbond XT, Fuji Ortho LC e Ketac Cem Easymix. Depois de 24 h, os espécimes foram sumetidos ao teste de resistência ao cisalhamento. A imagem da superfície do esmalte (classificado pelo Índice de Remanescente Adesivo-IRA) também foi avaliada. O IRA foi distribuido em tabelas de contingência e analisado quanto à frequência entre grupos/subgrupos. O teste de resistência ao cisalhamento foi avaliado por ANOVA e pós-teste de Tukey. CIVMR apresentou os menores valores de adesão entre os grupos (p<0,05). Entre os grupos irradiados e não-irradiados não houve diferença estatística significante (p>0,05). Quanto ao IRA, RC-I apresentou maior retenção de compósito na superfície do esmalte do que os demais subgrupos. CIVMR pode ser utilizado para colagem de bráquetes metálico e apresentou IRA aceitável para práticas clínicas.
Subject(s)
Humans , Bicuspid/radiation effects , Dental Bonding , Orthodontic Brackets , Glass Ionomer Cements , Neoplasms/radiotherapy , Radiation, Ionizing , Acid Etching, Dental , In Vitro Techniques , Composite Resins/chemistry , Dental Enamel , Shear StrengthABSTRACT
An in-vitro study was carried out on 80 human premolars to study the use of Nd:YAG laser as a potential alternative for acid etching in the surface treatment of enamel prior to sealant application. The determination of bond strength using Universal Testing Machine, Model 1011 and marginal leakage using the spectrophotometric dye recovery method showed no statistically significant difference between the groups with laser and acid surface treatments. But, there was a significantly lower bond strength and increased dye penetration in the group with no surface treatment. Scanning electron microscopic study of the interface between sealant and enamel surface of the acid and laser treated specimens was also carried out.