P90 system adhesive

A low shrinking silorane-based resin composite Filtek LS (Shade A₃, 3M ESPE, St Paul, MN, USA) and its corresponding adhesive system two-step self-etch adhesive system P90 System Adhesive (3M ESPE, St Paul, MN, USA) were used in this study. Table 1 shows the material brand names, compositions, manufacturers, and batch numbers.
A total of 39 sound upper human premolars; extracted from an age group of 18–20 years, were stored in phosphate buffer solution containing 0.2% sodium azide at 4 °C pending uses within 1 month [8] (link).

The name of products used, their composition and their manufacturing companies are summarized in Table 1. Three types of restorative materials were used in this study: a methacrylate-based microhybrid composite resin (Filtek Z250, 3M-ESPE, St. Paul, MN, USA) and Adper Prompt L-Pop bonding (self-etch adhesive, 3M-ESPE), a methacrylate-based nanofilled composite resin (Filtek Z350, 3M-ESPE) and Adper Prompt L-Pop bonding, and a silorane-based composite resin (Filtek P90, 3M-ESPE) and self-etch bonding and primer (P90 System adhesive, 3M-ESPE). Day white home bleaching system (Discus Dental, Culver City, CA, USA) containing 38% carbamide peroxide was used for bleaching.