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.
Highlights
With the advancement of cancer treatment [1] and early diagnosis of the disease [2], survival and cure rates increased
The hypothesis of this study was partially confirmed, since only the resin-modified glass ionomer cement showed adherence similar to that obtained by the use of orthodontic composite
It was chosen to evaluate the bonding of brackets with glass ionomer cement on teeth subjected to ionizing radiation, due to the absorption property and fluoride release of this material
Summary
With the advancement of cancer treatment [1] and early diagnosis of the disease [2], survival and cure rates increased. More and more Orthodontists will be required to treat patients with cancer history [3]. Changes in the organic and inorganic substrate of the tooth can make them more susceptible to demineralization [8,9,10]. The combination of these factors enables development of caries lesions, which may arise from three weeks to one year after radiotherapy [8]
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