Introduction Advance in new nano-composite materials and adhesive systems has provided stronger bond with hard dental tissue as well as possibility for minimal cavity preparation. The aim of this study was to evaluate, using dye method, marginal seal of direct composite veneers placed on intact and abraded anterior teeth and polymerized with classical and soft start light curing technique. Material and Methods The study was conducted on 40 extracted human anterior teeth. They were extracted for periodontal reasons and divided into two groups: intact teeth (20) and abraded teeth (20). 10 teeth in each group were polymerized with classical and soft start technique. Dye penetration was measured using stereo loupes with micrometer scale and six times magnification. Results Linear dye penetration on the gingival wall when direct composite veneers were placed in intact teeth and polymerized with classical technique was 2.50 μm, while on the incisal wall it was 0.5 μm. Linear dye penetration on the gingival wall in intact teeth polymerized with soft start technique was 2.25 μm, while on the incisal wall it was 2.0 μm. Average dye penetration of direct composite veneers in abraded teeth polymerized with classical technique on the gingival wall was 3.0 μm while on the incisal wall it was 1.25 μm. Linear dye penetration in abraded teeth polymerized with soft start technique was greater on the gingival wall (3.50 pm) than on the incisal wall (3.25 μm). Conclusion Smaller microcrack was observed on the incisal wall than on the gingival wall in all teeth regardless of the technique of polymerization used. The least dye penetration was observed in the group of intact teeth polymerized with classical technique of polymerization.