Tooth vitality will be confirmed with cold test (ethyl chloride) and registrated. Bleeding of the gingiva will be recorded using a periodontal probe. Local anesthesia will be applied to prevent pain and discomfort during cavity preparation. Tooth surface will be cleaned using a commercial non fluoride prophy paste (Cleanic, fluoride free, Kerr dental). The cavity preparations will be performed by removing old fillings or/and opening carious lesions using rounded and cylindric diamond burs (Komet). Round tungsten carbide burs (Komet) and hand instruments will be used to excavate carious dentine in both groups. For composite resin restoration, sound dentin verification will be based on probing and tactile sensation. No marginal bevel will be prepared and a horizontal platform (avoid apical shift) in approximal box will be made. Before placement of the materials, impressions will be taken to registrate cavity depth.