Purpose: To evaluate the morphological alterations in enamel and dentin of primary teeth following radiotherapy (RT) and to determine the best adhesive technique and time to carry out restorative procedures.<br/> Methods: Enamel and dentin fragments of primary teeth were randomly assigned into four groups (n=30): G1 (control)-non-irradiated, only restorative procedure; G2- restorative procedure immediately before RT; G3-restorative procedure 24 hours after RT; and G4-restorative procedure six months after RT. Each group was divided into one of two subgroups according to the adhesive system used for restoration: (1) AdperSingle Bond 2 (SB); and (2) ClearfillSE Bond (CL). The specimens were submitted to fractionated RT until they reached the final dose of 60 Gy. They were then subjected to confocal microscopy and the shear bond strength test. Data were analyzed using two-way analysis of variance followed by Tukey's tests ( α = five percent).<br/> Results: Morphological changes were first observed in enamel and dentin after 40 Gy of irradiation. G4 bond strength values were similar to G1 in the CL and SB groups for enamel and in the CL group for dentin (P >0.05). G2 showed the lowest values for enamel and dentin (P <0.05). In G3, CL presented the highest strength values in enamel; for G4, the highest values were found in dentin (P <0.05).<br/> Conclusions: Radiotherapy affected the morphological surface of enamel and dentin. The restorations placed immediately after RT had the weakest shear bond strength, and the restorations placed six months after RT had similar means of bond strength compared to the nonirradiated teeth in enamel, regardless of the adhesive system used. In dentin, CL showed better performance than SB.