Magister Scientiae Dentium - MSc(Dent) / Restorative systems classified as polyacid modified composite resins, or compomers, have appeared on the market. An example of this is Dyract AP. Dyract AP must be used with the Prime & Bond NT bonding system. Prime & Bond NT can be applied without any form of prior etching, or it can be applied after application of Non Rinse Conditioner, or it can be applied after etching with 36% phosphoric acid. The purpose of the study was to determine the qualitative microleakage of Dyract AP and its bonding systems, as well as the influence of saliva contamination there of. Freshly extracted, non-carious, human premolars were randomly divided into 8 groups of 18 teeth each. Apiseetomies coated with Polivar varnish and restored with amalgam were performed on all teeth. Class V type cavities of 3 mm diameter and 1,5 mm depth were prepared on the CEJ junction on the buccal side of all teeth. Dyract AP restorations were placed using the bonding procedures indicated: Group 1: P&B NT (Prime & Bond NT); group 2: acid (36% phosphoric acid) + P&B NT; group 3: NRC (Non Rinse Conditioner) + P&B NT; group 4: P&B NT + Saliva; group 5: acid + Saliva + P&B NT; group 6: acid + P&B NT + Saliva; group 7: NRC + Saliva + P&B NT; group 8: NRC + P&B NT + Saliva. Restorations were finished with Sof-Lex discs. After 24 hours storage in distilled water the teeth were removed and coated with two layers of nail varnish, except for 1 mm around the restorations. The teeth were then thermocycled in a 0.5% basic fuchsin solution for 500 complete cycles between 8°C and 50°C, with a dwell time of 15 seconds.