Aim: to evaluate the possible benefit on wound healing and flap stability of periosteum inclusion, comparing a "split-full-split" thickness flap elevation versus a "split" thickness approach performed during CAF for the treatment of isolated-type gingival recessions in the upper jaw.

Material and Methods: forty patients were randomized, 20 were treated with "split-full-split" (test group) and 20 with a "split" approach (control group). Analyzed parameters at 1 year were: CRC, percentage of Recession Coverage (RC), Keratinized tissue (KT) gain, patient-related outcome measurements.

Treatment of buccal gingival recession (GR) is the common clinical requirement from patients who are mainly concerned about aesthetics. Noteworthy are also requests linked to root sensitivity, difficulty in oral hygiene procedures, presence of root caries and non-carious cervical lesions. GR defects, when left untreated, do not improve spontaneously and may progress toward increased recession depth (RD) and clinical attachment loss which increase the patient's aesthetic concern and the clinical discomfort due to augmented dental hypersensitivity.

Complete root coverage (CRC) can be considered the primary clinical outcome and selecting the surgical technique depends mainly on the local anatomical characteristics and on the patient's demands.

In patients with a residual amount of keratinized tissue apical to the recession defect, the coronal advanced flap (CAF) may be recommended. This surgical technique results in optimal root coverage, good color blending of the treated area with respect to adjacent soft tissues and a complete recovery of the original (pre-surgical) soft tissue marginal morphology. Furthermore, post-operative morbidity is reduced to a single area of surgical intervention and the overall chair time is limited.

When utilizing CAF technique, critical factors in CRC have been described in the literature. Flap positioning coronal to the CEJ and a tension-free flap design are among the most important ones. Moreover, flap thickness has been shown to influence the clinical outcomes of CAF procedure .

Coronally advanced flap has been widely validated by the literature for the treatment of single recession defects and, currently, different flap designs and technical modifications are available to clinicians.

De Sanctis and Zucchelli have recently introduced the "split-full-split" flap elevation modality. According to the authors, the modulation of flap thickness, produced by the inclusion of periosteum in the central area, increases flap thickness in the portion of the flap residing over the previously exposed avascular root surface. This, in turn, would give better stability to the flap. However, the partial-thickness flap approach is still commonly performed in the clinical practice and it is validated in the literature.

To date, evidence is still lacking on the influence of including the periosteum in the flap when compared with a split thickness approach in obtaining a CRC.

Thus, the aim of this double blind, controlled and randomized clinical trial was to evaluate the possible benefit on wound healing and flap stability of periosteum inclusion comparing a "split-full-split" flap elevation versus a "split" thickness approach when CAF is performed for the treatment of isolated-type gingival recessions in the upper jaw.

Inclusion Criteria:

• age >18 years,
• no systemic diseases or pregnancy,
• smoking ≤10 cigarettes/day,
• full-mouth plaque score and full-mouth bleeding score ≤20%,
• presence of at least one Miller class I or II isolated recession defect (Miller, 1985) in the upper jaw and at least 2 mm of keratinized tissue apical to the recession,
• recession depth (RD) equal to or greater than 2mm,
• identifiable cemento-enamel junction (CEJ),
• vital teeth, free from caries or prosthetic crown,

Exclusion Criteria:

• systemic diseases or pregnancy,
• history of periodontal surgery at experimental sites.