“…3,4 However, a recurrent question regarding inlay restorations relates to cavity design, especially regarding the occlusal isthmus extension, and to when the cusps should be overlapped. 5,6,7,8,9 In the literature, recommendations can be found indicating that when the limits of the inlay cavity preparations are closer than 1.5 mm to the functional cusp, or when there is a less than 2 mm remaining thickness, an onlay preparation should be included, with a 2 mm axial reduction. 10 This principle of cavity preparation with cuspal coverage or overlap is based on metal cast restorations that do not adhere to dental substrates, and that are recommended to strengthen a weakened tooth declaration of interests: The authors certify that they have no commercial or associative interest that represents a conflict of interest in connection with the manuscript.…”