Introduction: The giomers are a family of dental materials that allow a faster effect and better functional, esthetic and mechanical properties.

Objective: To analyze the restorative ability between giomer and type II glass ionomer in class I cavities.

Methodology: A mouth split design was carried out in which 27 permanent molars ICDAS 4, 5 or 6 were filled with giomer (14) and glass ionomer type II (13), respectively, in patients with high or medium caries risk. Intraoral radiographs and polyvinyl siloxane impressions were taken every 3 months. FDI criteria were used to evaluate radiographic success, material fracture, and marginal adaptation.

Results: Compared to glass ionomer, giomer had better marginal adaptation at 6 and 9 months (p<0.05), was also better in fracture restoration at 3, 6 and 9 months (p<0.05), and better radiographic success at 6 and 9 months (p<0.05).

Conclusions: Giomer has better clinical results in terms of marginal adaptation, radiographic success and fracture of the material than glass ionomer.