Objective To compare the fracture resistance of mandibular incisors′ preparations for veneers and crowns, mandibular incisors restored with Empress 2 veneers and crowns. Methods 50 human mandibular incisors were randomly divided into five groups. Each group consisted of ten teeth and the treatment obtained as follows: A, tooth preparations for veneers; B, tooth preparations for crowns; C, teeth restored with veneers; D, teeth restored with crowns; E, untreated group. The teeth received standardized preparation and the restorations were manufactured with Empress 2 system and cemented with resin luting agent. The fracture resistances of teeth were measured by Instron universal testing machine and statistically analyzed with one-way ANOVA. Results The fracture resistances of A, B, C, D, E were （576.11±91.53）, （204.13±85.88）, （451.50±116.81）, （386.16±117.75） and （566.05±121.37）N, respectively. The statistical analysis demonstrated significant differences between five groups. There were no significant differences between group A and E, group C and D. Conclusion Tooth preparations for veneers did not significantly reduce the fracture resistance of mandibular incisor. The fracture resistance of teeth restored with Empress 2 veneers and crowns did not significantly differ from each other.
