Patients belonging to the intervention group presented abfraction lesions in upper and/or lower premolars. These abfraction lesions consist of a loss of dental hard tissue at the cervical level of more than 1 mm, and are associated with type 1 gingival recession of the Cairo classification.

The steps to follow for the treatment of abfraction using composite resin and the B.O.P.T. technique will consist of:

• Selection of the color of the composite, placement of the retraction cord and chamfering of the coronal margin of the lesion;
• Application of 37% phosphoric acid etching and adhesive in 3 steps; placement of the composite by layers, following the conventional obturation technique.
• Execution of an overfilling with the composite at the level of the cervical emergence profile of the tooth, with the aim of emphasizing said anatomical particularity.
• Removal of the retraction cord.
• Diamond milling with red rim flame diamond bur and contra-angle, positioned from the most apical point of the restoration at an angle of 45º without touching the restored dental portion, with the aim of performing a level rotary gingival curettage from the margin of the restoration.
• Polishing with a fine-grain flame bur, and polishing discs of decreasing granulometry.

The gingival recession associated with the abfraction lesion is digitally measured (in mm) through intraoral scanning of the same. Gingival recession is measured from the most coronal portion of the gingival margin to the cementoenamel junction at 3 fixed points (in mesial, medial, and distal).

A software allows to overlay the initial scan with the post treatment scan; thus, the changes obtained thanks to the treatment in the height of the gingival margin are objectively measured.

The volume of the gingival tissue at the level of the margin, is measured through an initial intraoral scan, at 3 fixed points (the same points measured in the gingival recession, see outcome 1), from the outermost part of the gingiva to the outermost portion of the tooth root, seen in an occlusal view.

A software allows to overlay the initial scan with the post treatment scan; thus, the volumetric changes obtained thanks to the treatment in the gingival margin are objectively measured.

Value measured with a Williams periodontal probe with markings at 1-2-3-5-7-8-9-10 mm, from the bottom of the gingival sulcus to the gingival margin at 3 points (mesial, medial and distal).