The goal of this research was to assess the impact of orthodontic root movement on gingival recessions.
Twelve consecutive adult patients with a mandibular incisor presenting buccal or lingual gingival recession and with the root positioned outside the alveolar bone were enrolled. The roots were moved toward the center of the alveolar process with a goal oriented segmented appliance. The following variables were measured at baseline and after orthodontic treatment: (1) recession depth, (2) recession width, and (3) recession area. In addition, pocket probing depth, keratinized tissue height, and changes in Miller’s classification were registered.
The depth, width, and area of the gingival recessions were reduced in all patients without increased pocket probing depth. On average, the recession depth decreased with 23%, the width with 38%, and the recession area with 63% of the baseline value. All patients improved in Miller’s classification from Class III and IV to Class I or II.
Orthodontic correction of the root toward the center of the alveolar envelope consistently reduced gingival recessions. The changes in Miller’s classification indicated improved prognosis for full root coverage with mucogingival surgery.
Orthodontic root movement into the alveolar bone consistently reduced gingival recessions.
The recession depth decreased with 23%, the width with 38%, and the recession area with 63%.
All cases improved in Miller’s classification from Class III and IV to Class I or II.
Tooth displacement outside the alveolar bone constitutes a risk for the development of a bony dehiscence that may be accompanied by a recession of the gingiva. Conversely, redirection of a root into the alveolar process can be complemented by improved marginal bone level and spontaneous improvement of gingival recession. According to several authors, the prognosis for a complete root coverage of gingival recessions by a mucogingival surgical intervention is correlated to both the severity of the recession and the position of the recessed tooth. Consequently, it is advocated to position the roots within the alveolar envelope reducing root prominence and allowing creeping of the attachment thereby providing a more optimal surgical site. Movement of the exposed roots toward the center of the alveolus may thus lead to improvement of the gingival recession and to reduction of the bony dehiscence before periodontal plastic surgery. However, the association between orthodontic correction of tooth position and “spontaneous” repair of gingival recession has not previously been systematically investigated in a clinical study.
The aim of this study was to quantify the changes of gingival recessions following orthodontic displacement of exposed roots toward the center of the alveolar bony envelope.
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 ).
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.
The mean and range of the intraindividual changes in recession depth, width, and area were calculated. Intraexaminer reproducibility was assessed by interclass correlation coefficient. Bland-Altman plots were inspected for the systematic error and the Dahlberg’s formula was used for the calculation of the random error. The analysis was performed using Stata software version 14.1 (StataCorp, College Station, Tex).