Objectives: Minimal intervention concepts introduced for caries management demand early treatment of incipient caries lesions. This study evaluated a new technique for treating early enamel lesions by using a paste composed of 45S5 bioglass and phosphoric acid. Methods: Enamel flat surfaces were obtained from the buccal surfaces of 80 extracted human non-carious third molars. The enamel surfaces were covered with nail varnish leaving a circular window of 2 mm in diameter. All of the specimens were acid challenged in an acidic buffer solution (pH 4.5) for 4 days at 37oC. 45S5 bioglass powder (NovaMin®, 5µm average particle donated by NovaMin Technology, USA) was mixed with 50% phosphoric acid and applied on the enamel surfaces of 40 specimens, while the remaining samples were used as control. All specimens were stored in artificial saliva solution for 7 days. Twenty specimens from each group were exposed to 6000 cycles of brushing-abrasion challenge under wet conditions with a load of 250 gf using a tabletop robot. The top surface and cross-cut surfaces of the specimens were observed by FE-SEM/EDS before/after the brushing-abrasion challenge. The percentage of enamel coverage before and after abrasion challenge were compared using Kruskal-Wallis test (p<0.05). The top enamel surfaces were examined by X-ray diffraction technique before/after the 45S5 bioglass application and before/after the abrasion challenge Results: The enamel surfaces on which the bioglass was applied showed 100% coverage of all specimens by a layer rich in calcium-phosphate crystals. The brushing-abrasion challenge did not significantly affect the percentage of enamel surfaces coverage by the calcium-phosphate crystals (p<0.05). Conclusion: An abrasion durable crystallized calcium-phosphate rich layer was formed upon using the aforementioned technique suggesting its possible application during treatment of incipient enamel caries lesions. This study was supported by grant in aid from JSPS and the GCOE Program, ICTB at TMDU.