Material and methods

Twelve consecutive adult patients (9 females and 3 males), mean age of 28 years and age range 22-41 years, with 1 mandibular incisor presenting either buccal or lingual gingival recession and the root clearly positioned outside the alveolar bone were enrolled for orthodontic root correction before mucogingival surgery. Apart from the gingival recession of the displaced incisor, none of the patients exhibited periodontal inflammation, radiological signs, or clinically detectable defects, which would indicate a past history of periodontitis. Informed consent to participate in the study was obtained. The orthodontic root corrections were performed with a segmented appliance consisting of a torque arch made of 0.019 × 0.025-inch titanium-molybdenum alloy delivering a desired torque equal to the force applied to hook the arch onto the base arch anteriorly to the molar multiplied by the sagittal distance between the displaced tooth and the point of force application. The undesired vertical force was neutralized by a steel base arch resting on the displaced tooth ( Figs 1-3 ). The base arch also prevented undesired proclination during lingual root torque and undesired retroclination during buccal root torque. As a consequence, only the torque needed for the root movement was expressed, and the center of rotation was at the bracket without side effects on the adjacent teeth. In some patients, finishing corrections were performed with a continuous wire ( Fig 3 , C ). All patients were treated by the same orthodontist. After orthodontic treatment, the patients were referred to the periodontist for mucogingival surgery ( Fig 3 , D ).

A and B, Root of the mandibular left central incisor (tooth 31) positioned outside the alveolar housing exhibiting gingival recession. C, Beginning of treatment. The force system, generating lingual root torque of the incisor, without side-effect on adjacent teeth, was obtained by a 0.019 × 0.025-inch titanium-molybdenum alloy torque arch inserted into the bracket of the malpositioned tooth and hooked onto a 0.020-inch SS base arch that controlled the vertical position of the incisor and the arch perimeter. D, During lingual root torque of tooth 31. The root of 31 is moving into the alveolar bone. E , One week after orthodontic treatment. The root position is corrected, and the recession is reduced in depth and width. SS , stainless steel.

The appliance with the torque arch deactivated. The terminal ends of the torque arch are hooked onto the base arch for lingual root torque of the incisor. The base arch is activated for intrusion of the incisor to counteract extrusion. The tendency to displace the incisor labially during lingual root torque is controlled by cinching back the base arch distal to the molars.

A, Root of the mandibular right central incisor (tooth 41) positioned outside the alveolar housing and with gingival recession. B, The appliance delivers lingual root torque to tooth 41 with a torque arch inserted into the bracket of the displaced tooth and hooked onto a base arch that controlled the vertical position of the incisor and the arch length. C, Before referral back to the periodontist after finishing in a continuous arch wire. D, Five months after mucogingival surgery with a coronally advanced flap combined with enamel matrix proteins.

At baseline and after orthodontic treatment, the following variables were measured clinically with a calibrated periodontal probe (University of North Carolina-15 probe) and on standardized intraoral photographs: (1) recession depth from the free gingival margin to the cemento-enamel junction, (2) recession width at the cemento–enamel junction, (3) recession area (on photographs), and (4) keratinized tissue height at the midbuccal or midlingual aspect of the exposed root. Furthermore, pocket probing depth was measured using the same calibrated periodontal probe also at the midbuccal or midlingual aspect, and the recessions were classified according to Miller’s classification.

The measurements were performed by the referring periodontist and the orthodontist treating the patients. The reported measurements of recession width and depth were made to the nearest 0.25 mm on magnified (factor 10) intraoral photographs of good quality and calibrated to the true value using the clinically assessed widths of maxillary and mandibular incisors as reference. The area of the recession was calculated on the clinical photographs with an open source image processing software (ImageJ, version 2.0.0; National Institutes of Health, Bethesda, MD). Measurements on the photos were repeated after a minimum of 15 days on 12 patients for calculation of the error of the method.