Periosteal releasing incisions are indicated when it is necessary to mobilize a flap to ensure that primary wound closure is achieved. This surgical technique is often required when grafting procedures are performed to augment the bone at the implant site. It is critical that the bone graft is completely covered by the flap during the entire healing period. Premature exposure of the graft increases risk of infection and may lead to loss of graft material or even failure of the entire augmentation procedure. A PRI allows the flap to be advanced to cover the extra volume of hard tissue created by the graft. PRI are indicated for both staged and simultaneous bone augmentation procedures.

In extraction sites, there is a deficit of soft tissue over the socket. Periosteal releasing incisions are sometimes used for primary wound closure when grafting materials are placed in the socket for ridge preservation or in conjunction with Type 1 immediate implant placement. However, clinicians should be aware that this can significantly disrupt the position of the mucogingival junction, especially when the zone of keratinized gingiva is narrow. Secondary soft tissue correction procedures are often necessary to correct the position of the mucogingival junction. For this reason, PRI is not the technique of choice for closing extraction sockets. Most clinicians favor other socket closure techniques such as soft tissue grafts or pedicle flaps from the palate.

The periosteum is a dense layer of fibrous connective tissue that covers the bone. When a full-thickness mucoperiosteal flap is raised, the periosteum is stripped off the surface of the bone with periosteal elevators, forming part of the flap. The periosteum is dense and fibrous, with very little elasticity; as a result, the flap cannot be readily mobilized and coronally advanced. When the periosteum is incised with a periosteal releasing incision, the flap is no longer tethered by the periosteum and has greater mobility, and it can then be moved in a coronal direction. Sometimes, releasing the periosteum is not sufficient, particularly if the mucosa contains scar tissue or muscle attachments. In these situations, deeper dissection may be required to mobilize the flap.

Before performing a periosteal releasing incision, the clinician needs to have a good understanding of the anatomical structures in the vicinity of the surgical site in order to reduce the risk of complications. Neural, vascular, and other anatomical structures may be found within the soft tissues of a mucoperiosteal flap. Without understanding the location of the structures within the soft tissues, the clinician may inadvertently damage or sever major blood vessels and nerves. The lingual nerve and blood vessels in the floor of the mouth on the lingual aspect of the mandible can be harmed if a PRI is performed in this region. Although PRI can be performed on the lingual aspect of the mandible, it is a high-risk procedure and is not recommended. The mental nerve and blood vessels are located on the buccal aspect of the mandible in the region of the premolar teeth, and the infraorbital nerve and blood vessels are located on the buccal aspect of the maxilla in the infraorbital fossa. The duct of the parotid gland is located in the maxillary posterior buccal region. For this reason, deeper PRIs that extend 10 millimeters or more beyond the mucogingival junction should be avoided in the posterior maxilla.

The periosteal releasing incision needs to be planned as part of the overall surgical procedure, commencing with the design and elevation of the mucoperiosteal flap. This must be a full-thickness flap with at least one vertical releasing incision. For maximum mobility of the flap, two releasing incisions are preferred. The vertical releasing incisions need to be extended sufficiently beyond the mucogingival junction to allow good exposure of the surgical site and to allow the PRI to be made. PRIs should not be made in keratinized attached mucosa as this tissue is not elastic and will remain immobile even if the periosteum is incised. For this reason, PRIs are performed on the buccal aspect of the maxilla and not on the palatal side. In the mandible, PRIs should also be performed on the buccal aspect. Although a lingual PRI can be made, there is a significant risk of injury to the lingual blood vessels and nerve. A lingual PRI is therefore not recommended in the mandible.

The clinician also needs to decide when to perform the periosteal releasing incision. In most cases, it is helpful to perform PRI after raising the flap, prior to bone augmentation procedures. This allows the clinician to decide whether the flap can be sufficiently mobilized to cover the volume of graft that is planned and also allows time for initial hemostasis to occur before bone or bone substitutes are grafted to the site. This is also a good stage at which to collect venous blood for mixing with particulate graft material if a guided bone regeneration procedure is planned. In the case of block bone grafts, the PRI can be made after block fixation. However, it is recommended that the PRI is performed before application of particulate grafts and barrier membranes to ensure that the particulate material is not dislodged due to excessive bleeding.

As the PRI is made, the tension in the flap should begin to release. Sufficient mobility in the flap will allow it to be advanced by 3 to 5 millimeters over the lingual or palatal side of the ridge. This should be adequate to cover the planned bone graft. If there is insufficient mobility of the flap, further release of flap tension can be achieved with slightly deeper cuts in the muscle layer using dissection scissors or a second PRI parallel to the first incision. The second PRI can be either coronal or apical to the original PRI according to the flap design and surgical access and visibility. If the second PRI is placed apically, the vertical releasing incisions must be extended.

This 55-year-old patient required the extraction of 2 periodontally compromised maxillary incisors with existing periapical cysts following previous endodontic treatment. The treatment plan is to place one implant in the right lateral incisor site for a single crown and one implant in the left central incisor site to support a two-unit implant fixed dental prosthesis. Staged bone grafting for augmentation before implant placement is planned. For better primary wound closure, surgery is scheduled 8 weeks after the extractions. A periosteal releasing incision is indicated to achieve tension-free wound closure following completion of the procedure. A full thickness mucoperiosteal flap has been raised with one vertical releasing incision on the adjacent left canine. The releasing incision has been extended apically beyond the mucogingival junction. The horizontal incision has been extended as a sulcular incision up to the right canine. Using fine tissue forceps, the tension in the flap is evaluated by gently pulling the flap coronally. This gives the surgeon an idea of how much the periosteum will need to be released to give the flap enough mobility to achieve primary closure after the grafting procedure. Starting from the left vertical releasing incision, a horizontal incision in the periosteum is made towards the midline with a 15 D blade. The key point here is that the angulation of scalpel movements could be blocked by the tooth. A second incision is made slightly deeper into the tissues for better release of the periosteum. Tension in the flap is maintained throughout the procedure by gently pulling on the flap with the tissue forceps. As the incision is made, the surgeon is able to feel the tension in the flap releasing. The right periosteal releasing incision is then made, commencing from the canine region through the midline. A second incision is then made to further release the tension in this portion of the flap. As there is no vertical releasing incision on this side, the mobility of the flap is limited. Surgical scissors are now being used to make a deeper dissection into the tissues. Surgical scissors provide good tactile feedback and control and are safer to use than a scalpel blade in areas where access is limited or when vision is obscured. The surgeon holds and retracts the flap gently through every step of the periosteal incision procedure. The left and right incisions meet and continue through the midline. Deeper cuts in the periosteum on the left hand side are also performed with scissors. Once again, the flap is gently pulled and the muscle fibers are dissected deeply to achieve sufficient mobility of the flap. This procedure is repeated on the right side. The flap is pulled gently towards the palatal side to check that the increased flap mobility permits primary wound closure of the site. Here sufficient flap elasticity is obtained to accommodate the additional volume needed for the guided bone regeneration procedure. The surgeon notes that there is still some tension remaining in the flap. An additional periosteal releasing incision is performed apical to the previous incision for increased flap mobility on the side of the vertical releasing incision. The increased flap mobility allows the buccal flap to overlap the palatal flap margin. Primary closure has been achieved. After 3 days, the flap edges have remained closed and wound healing is progressing uneventfully. After 7 days, uneventful healing of the site is observed. Provisional prosthesis intraoral view. Provisional prosthesis extraoral view.

This 27 year old patient requires early implant placement following extraction of a maxillary central incisor due to root resorption. The treatment plan is to place an implant in the right central incisor site to support a single crown. Simultaneous bone grafting for contour augmentation is planned. A periosteal releasing incision is therefore indicated to achieve tension free wound closure following completion of the procedure. Tension on the flap can be clearly seen. A full thickness mucoperiosteal flap has been raised with one vertical releasing incision on the mesial side of the right canine. The flap has been extended apically beyond the mucogingival junction. Using fine tissue forceps, the flap is pulled gently to provide good visibility and access to the periosteum. With a 15 blade, a horizontal incision in the periosteum is made commencing at the base of the right vertical releasing incision towards the midline. Tension in the flap is maintained throughout the procedure by gently pulling on the flap with tissue forceps. As the incision is made, the surgeon can feel the tension in the flap releasing. The periosteal releasing incision is then extended distally to ensure that it joins the base of the vertical releasing incision. Once this is done, the increase in mobility of the flap can be seen. The flap is then pulled gently towards the palatal side to check that there is sufficient mobility of the flap for primary closure. This will give the surgeon an idea of whether the flap is sufficiently mobile for wound closure after contour augmentation. Primary wound closure has been achieved. An occlusal view shows the position of the sutures in primary wound closure. Postoperative appearance at 8 weeks is the result of tension-free healing. Postoperative appearance at 8 weeks, occlusal view.

This 60 year old patient required extraction of 3 periodontally compromised maxillary incisors. The treatment plan is to place an implant in the right and left lateral incisor sites to support a 4-unit implant fixed dental prosthesis. Simultaneous bone grafting for contour augmentation is planned. A periosteal releasing incision is therefore indicated to achieve tension free wound closure following completion of the procedure. A full thickness mucoperiosteal flap has been raised with vertical releasing incisions distal to both canines. The flap has been extended apically beyond the mucogingival junction. Using fine tissue forceps, the tension in the flap is evaluated by gently pulling the flap coronally. As in the previous cases, this allows the surgeon to estimate how much the flap will need to be released in order to achieve primary wound closure. With a 15 C blade, a horizontal incision in the periosteum is made commencing at the right vertical releasing incision towards the midline. It is important to maintain tension in the flap throughout the procedure by gently pulling on the flap with the tissue forceps. The surgeon can feel the release of tension in the flap as the incision is being made. The flap is then pulled towards the palatal side to check that there is sufficient mobility of the flap for primary closure. The procedure is then repeated on the left side of the flap. Commencing at the vertical releasing incision on the left canine, a horizontal incision in the periosteum is made extending mesially towards the midline. The left and right incisions meet at the midline. Once again, the flap is gently pulled towards the palatal side to confirm that there is sufficient mobility of the flap for primary closure. The undersurface of the flap is then inspected to see if there are any residual areas of attachment that may be limiting mobility of the flap. Here, additional elevation of the flap is performed apical to the periosteal releasing incision where an adhesion is noted. Mobility of the flap is then rechecked. In case of insufficient mobility in the flap after the initial periosteal releasing incision, additional steps may be used. Deeper incisions into the muscle attachment can be made in the original horizontal releasing incision. Alternatively, a second horizontal incision slightly coronal and parallel to the original releasing incision can be made. This is the clinical situation after implant placement and guided bone regeneration procedures. Primary closure has been achieved. This is the surgical site after 1 day of healing. After 3 days, the flap edges have remained closed, and wound healing is progressing uneventfully. After 7 days, there has been a minor dehiscence of the flap over the healing abutment on the right implant. This is the clinical appearance after suture removal. This is the frontal image, and this is an extraoral image. The provisional restoration is in place. This is the clinical appearance after 2 weeks of healing, and after 6 weeks of healing. The area of minor dehiscence remains.

This 58-year-old patient requires two implants to replace the upper right lateral and left central incisors with simultaneous bone augmentation. A full thickness mucoperiosteal flap with two vertical incisions has been made. Careful evaluation of the flap with two fine tissue forceps clearly demonstrates the tension in the flap. Defects in the bone can be seen at both sites. As a substantial graft is planned, there is a need for a periosteal releasing incision to mobilize the flap to allow primary wound closure. With a 15 blade, a horizontal incision is made in the periosteum starting at the base of the flap at left vertical releasing incision. The incision is extended mesially towards the midline. Visibility and tension in the flap is maintained throughout the procedure by gently pulling on the flap with the tissue forceps. The periosteal releasing incision is continued from the midline in a distal direction towards the right vertical incision. Note how a single incision line is created. The separation of the periosteum shows how much the length of the buccal flap is increased. The flap now has increased mobility and can easily be advanced coronally to provide primary wound closure. Primary wound closure after surgery is shown.

In this case, the patient requires a periosteal releasing incision in the anterior maxillary region to achieve tension free wound closure following grafting and simultaneous implant placement procedures. This case demonstrates the scissors technique for releasing the periosteum. A full thickness mucoperiosteal flap has been raised with vertical releasing incisions adjacent to right central incisor and left lateral incisor. The flap is extended apically beyond the mucogingival junction. A black silk retraction suture has been used to maintain reflection of the palatal flap. Using a second retraction suture and fine tissue forceps, the flap is gently pulled buccally, providing clear visibility of the undersurface of the flap and the periosteum. The periosteal releasing incision is made by fine overlapping cuts to the periosteum with a pair of dissecting scissors. The surgeon commences the incision on the right side and extends it mesially across the midline to the left side. With this technique, very fine control of the incision can be achieved, as the surgeon can feel for any adhesions within the tissues as the cuts are being made. It is important to combine each scissor cut to create a single horizontal incision in the periosteum. It is also important to check that the horizontal incision meets the base of the vertical incision on both sides. Here the surgeon is confirming this and making additional cuts where necessary. At this point, after creating a clear view of the periosteum, the surgeon checks the horizontal incision to see if there are any adhesions or muscle attachments that are preventing the flap from being released. Additional fine cuts are made where these adhesions are detected. The buccal flap is then pulled gently towards the palatal side. This step confirms that there is enough mobility in the flap to cover the planned bone graft after implant placement and to achieve primary wound closure. This is the clinical appearance immediately after wound closure following surgery. Three days after surgery, normal healing continues. Postoperative healing remains uneventful through the eighth day. This is the clinical image 15 days postoperatively, following suture removal.

This patient required extraction of periodontally compromised mandibular premolars following implant placement in lower first molar region. The treatment plan is to perform bone grafting for ridge augmentation at the lower left premolar sites. A periosteal releasing incision is therefore indicated to achieve tension free wound closure following completion of the guided bone regeneration procedure. A full thickness mucoperiosteal flap has been raised with one vertical releasing incision at the distal corner of the flap. The flap is pulled gently to provide good access and visibility of the periosteum. With a 15 C blade, a horizontal incision in the periosteum is made commencing at the distal vertical releasing incision towards the mesial direction. It is very important to protect the mental nerve during this procedure, so the mental foramen and neurovascular bundle should be identified and protected prior to the surgical procedure. Tension in the flap is maintained at all times throughout the procedure by gently pulling the flap with the tissue forceps. After additional releasing of the periosteum at the base of the vertical incision, the flap is then pulled towards the lingual side to check for sufficient mobility to achieve primary closure. This is the clinical appearance after 8 months of healing.

A common complication in the PRI procedure is hemorrhage, or bleeding. Periosteal releasing incisions result in bleeding because the vessels within the mucosa at the site of incision can be easily cut. Usually, the bleeding is transient and can be controlled by local measures such as direct pressure. However, hemorrhage due to arterial damage can cause heavy bleeding to occur. It is important that bleeding is controlled before the flaps are closed to minimize the risk of ecchymoses or hematoma. The initial measure to control bleeding should be to apply pressure; if this is insufficient, the vessel can be clamped with a hemostat. Laser or electrocoagulation can also be used to achieve stasis. If heavy arterial bleeding occurs, surgical ligation of the blood vessels should be performed.

With deeper dissection, a greater amount of bleeding may be anticipated. It is important to be aware that bleeding may limit the surgeon’s visibility of the surgical field during the procedure, resulting in damage to anatomical structures. This short video demonstrates the amount of bleeding that can occur when performing a deeper PRI with dissecting scissors. Postoperative bleeding can also occur, as the incision can transect the blood vessels within the soft tissues. Postoperative bleeding is a particular risk if deep dissection is performed or if arterial vessels are damaged. The patient should be provided with instructions for controlling postoperative bleeding.

Another common postoperative complication when periosteal releasing incisions are performed is dehiscence of the flap. A dehiscence is the rupture and breakdown of the tissues along a surgical incision. With PRI, the most common site of flap dehiscence is at the crestal incision. Flap dehiscence is most often a result of insufficient release of the periosteum due to an improper technique. Residual tension in the edges of the flap disrupts revascularization and causes the wound to break down. An inadequate suturing technique can contribute to wound breakdown. It is generally recommended that the wound edges be everted using a horizontal mattress suture technique. Flap dehiscences can also occur if there is excessive tissue swelling due to postoperative hemorrhage. The swelling can cause the flap margins to break down. Factors that interfere with wound healing such as cigarette smoking or uncontrolled diabetes mellitus can also result in this complication.

The periosteal releasing incision is a technique sensitive procedure. Several other complications can arise when performing it. The flap can perforate as a result of the PRI. This usually occurs when the horizontal incision is made in keratinized mucosa rather than the unattached non-keratinized mucosa. When the flap is perforated, the vascular supply is compromised. This may cause wound dehiscence and subsequent exposure of the underlying graft. Similarly, nerves in the vicinity of the periosteal releasing incision can be injured, resulting in paresthesia or anesthesia. Therefore, performing the PRI procedure in the correct area is crucial. The parotid duct can also be damaged when periosteal releasing incisions are performed in the posterior maxilla.

The aim of the periosteal releasing incision is to allow the flap to be coronally advanced. This maneuver can result in reduction in the depth of the buccal vestibule, which may complicate seating of an existing removable prosthesis. Care needs to be taken to ensure that all provisional prostheses are adjusted to relieve pressure over the surgical site. Coronal advancement of the flap also alters the position of the mucogingival junction in relation to the adjacent uninvolved teeth. Disruption of the mucogingival line may result in an unesthetic appearance of the soft tissues, which may then need additional soft tissue augmentation. It should also be noted that vertical releasing incisions made to facilitate mobilization of flaps may also result in recession of the gingiva at natural teeth involved in the surgical procedure. There is also a risk of altering the position of frenal attachments that are included in the flap. The most common complication is the frenal attachment being repositioned close to or at the crest of the ridge. This can interfere with the definitive implant prosthesis, creating an esthetic compromise as well as making it difficult for the patient to adequately clean their prosthesis.

Periosteal Releasing Incision, Module Summary: PRI is an essential technique to achieve primary wound closure in augmented sites and to provide closure of oroantral fistulae. The PRI technique must be applied with precaution to avoid damage to anatomical structures such as nerves, blood vessels, and the parotid duct. At least one and preferably two vertical releasing incisions, flap extension beyond the mucogingival junction, and horizontal incisions in non-keratinized mucosa are the key points in performing the PRI technique. Correct step-by-step technique will not only facilitate primary wound closure but will also increase the success of the surgical procedure. To avoid complications such as bleeding, flap dehiscence, and damage to anatomical structures, the surgeon must follow all technical guidelines and must evaluate the flap before closure.