The periosteal releasing incision (PRI) is very common in intraoral surgical procedures, especially when flap advancement is indicated, that is, when vertical or horizontal augmentations take place. This technical note describes the surgical skills for sufficient flap advancement. Complications due to improper PRI are also discussed.
The periosteal releasing incision (PRI) is a very common surgical procedure in daily practice. To repair or cover oroantral fistulas and/or augmented sites, the clinician often has to deal with problems, such as inadequate tissue (flap) length for complete coverage of the bone, the defect, or the augmented site. In bone grafting procedures, sufficient soft tissue closure is a key factor for uneventful healing.
Postoperative complications, such as flap dehiscences and bone graft exposures have been reported very often in the recent literature. The incidence of wound dehiscence is reported as 2.5%–10%1 especially in patients who smoke.2 Therefore, resorption of the graft and an insufficient, unsuccessful final clinical result may be associated with flap dehiscence. However, a recent literature search/analysis of the clinical outcome of different augmentation procedures showed different clinical results using guided bone regeneration and/or block grafting procedures and showed higher success using the guided bone regeneration (GBR) technique.3
Extensive discussion among clinicians regarding success of augmentations and the management of complications is typically related to the osteogenic potential of the grafting material, the immobilization of the graft during the surgical procedure, and issues with sufficient coverage of the recipient site due to flap advancement. There are important biological and postsurgical considerations, but an insufficient releasing incision of the periosteum for flap advancement is often the most important criteria for success or failure. Complete coverage of the surgical site is important to control the contamination of the grafted site and to support the osteogenic potential of the grafting material.
The exact technique of the PRI is not precisely described in any current surgical textbook or scientific journals. The aim of this report, therefore, is to demonstrate the exact surgical technique so that sufficient coverage of the augmentation site may be achieved.
The author, who is fully trained in the field of periodontology and oral maxillofacial surgery, noticed that there is not enough focus on this very important surgical procedure in textbooks. Based on the author's experience of PRI to advance flaps and cover augmented sites, especially after vertical augmentations of the maxilla or mandible, this technical note describes the most important steps for successful results.
Surgical guidelines for successful result:
The flap has to be a mucoperiosteal flap and must be raised sufficiently over the mucogingival junction in an apical direction for at least 10 mm.
With conventional dental forceps (surgical forceps may lead to flap perforations) hold (but do not pull) the flap in a coronal direction to evaluate the tension during coverage of the augmentation site.
With a new scalpel (blade No. 15 or 15c), start at the distal part of the flap perpendicular (or at a 60° angle) to the periosteum and, without stopping (that is, in one shot), cut the periosteum in a depth of 1–3 mm always moving the blade in a direction from distal to mesial.
The blade should cut the tissue in a level apical to the mucogingival junction (to avoid flap perforation, do not cut the area of keratinized mucosa). To avoid flap perforation, do not cut the area of the keratinized mucosa.
Pull and evaluate (in a coronal direction) the flap and check for a tension-free flap advancement. In case of insufficient closure, stay at the same area and cut more deeply in the muscle layer or use a new PRI in a parallel direction to the previous one, more apically.
Always check the final result in such a way that the buccal flap margin covers the lingual or palatal site at least of 3–5 mm. If this overlapping does not occur, there is a lot of tension in the flap, which means the closure is insufficient. Muscle release can be performed using dissection scissors (Figures 1 through 3). This is very important, especially in vertical or horizontal augmentations of the alveolar ridge with corticocancellous bone grafts or advanced applications of the GBR-technique to avoid graft exposure.
Intraoperative surgical complications due to PRI, like advanced bleeding from perforated blood vessels, should be controlled before final closure using electro- or laser-assisted coagulation. If advanced arterial bleeding occurs, surgical ligation of the blood vessels should be done. In that way, postoperative problems such as bleeding from the surgical site, ecchymosis, or hematoma can be controlled. Before starting the PRI procedure, be aware of certain anatomic structures, such as parotid duct, in case of flap advancement in the maxilla. Special considerations may take place at the lingual flap advancement, where a PRI may damage the lingual nerve. This nerve is oriented parallel to the lingual part of the mandibular body and close to the periosteum. For lingual flap advancement, it is of great importance to raise the lingual flap much more mesially in full thickness and/or to release the mylohyoid muscle.
A common surgical error, which typically takes place 1–4 weeks after surgery when flap dehiscence occurs, is the closure of the flap with a new suture with or without cutting the margin (dependent on the healing stage) of a flap for a new reepithelization. Premature exposure of the membranes in augmented sites is often caused by excessive pressure of a removable prosthesis.4 To obtain complete closure of the flap, a new PRI should be performed with tension-free closure (check for overlapping). Different suturing techniques, like mattress techniques, may improve the better flap adaptation. An adequate suction of the blood after incision is mandatory to allow a better flap closure without swelling. I recommend following the surgical steps reported here and using interrupted silk or other suture materials for better drainage of the blood compared with the mattress suturing techniques. However, healing by secondary intention would be the best alternative in such cases of flap dehiscence until the maturation of the soft tissue is complete. Certainly, sufficient antibiotic administration is of great importance to protect from bacterial invasion in the augmented site or underneath the flap. Frequent mouth rinse with salt water or chlorhexidine solution irrigations are also recommended for chemical plaque control.
There is no doubt that flap advancement is associated with insufficient vestibule depth, which has to be retreated later on, in terms of a preprosthetic mucogingival surgical procedure. A vestibuloplasty with or without a free gingival (or skin) grafting procedure (the use of connective tissue grafts or allografts, such as Alloderm [Biohorizons, Birmingham, Ala]) is indicated before or in combination with implant surgery. Alternative surgical techniques, like the use of laser surgery to increase the vestibule depth, have also been also reported.5,6 Moreover, the thickness of the tissue is important, and this may be reached by the use of thick free gingival grafts.
Eastman Institute of Oral Health, University of Rochester, Rochester, NY; Department of Oral Surgery and Implant Dentistry, Dental School, Frankfurt, Germany.