Augmenting the lateral ridge with decalcified cortical bone plate to prepare it for implants
It’s not uncommon for significant resorption to occur after extraction, which may be more prominent in the anterior maxilla because of its lower density, compared with the mandibular arch. How much resorption occurs relates to a multitude of factors, including the patient’s age, healing ability and medical health, and the reason for extraction (periodontal, endodontic, trauma or a combination).
Also, bone maintenance relates to stimulation of the bone through function related to load transmission through the teeth (or implants). When that stimulation is removed through extraction of the teeth, the surrounding bone resorbs or atrophies, with some patients demonstrating only minimal bone loss while others present with significant loss over time.
Bone loss occurs more significantly in bone that is less dense than in bone that has a higher density; therefore, the facial/buccal aspects of either arch will demonstrate more bone loss than the lingual/palatal aspects. The anterior maxilla (premaxilla), specifically in the area of the central and lateral incisors, is more prone to bone loss after extraction. This relates to the lower density of the facial bone, typically thinner bone over the facial aspect of the teeth with possible dehiscences and fenestrations that naturally can be present, as well as the concavity in the vestibule related to the trajectory of bone present.
Resorption related to extraction or even periodontal disease over a period of time requiring extraction may leave the area insufficient to house implants that had planned to replace the missing teeth. This will require an increase in the width of the ridge in the facial–palatal dimension to provide bone volume, through osseous grafting and permit implant placement.
Frequently this situation will require a two-stage approach: First, osseous grafting is performed and allowed to heal and mature, then implants are placed when adequate bone volume is present to allow primary stability of the implants during their healing phase.
The techniques to be described may also be used when there is sufficient ridge width crestally to place the implants but a fenestration presents at placement, exposing a portion of the apical half of the implant.
A 52-year-old patient presented missing his left central and lateral maxillary incisors, wanting implants to replace those missing teeth and a fixed prosthetic approach. The patient indicated that the teeth had been extracted eight years ago, and clinical examination noted a deficient facial aspect of the ridge at the extraction sites and healthy soft tissue (Fig. 1).
A cross-sectional CBCT view of the edentulous space confirmed inadequate width of the ridge in the facial–palatal dimension to house implants at the adjacent sites (Fig. 2). The patient was told this and that it would be necessary to augment the site with an osseous graft. Because insufficient bone would not permit simultaneous implant placement at the time of grafting, a healing period of four to six months would be needed between graft placement and implants placement, followed by another four to six months to allow the implants to osseointegrate before any restoration could be placed on the implants. The patient agreed to this plan.
The patient presented for Phase 1 of treatment: ridge augmentation by lateral grafting. After review of the written consent, the patient signed the consent form. Blood was drawn from the patient’s left antecubital fossa to fill four glass tubes (Becton, Dickinson and Co.) to be used to prepare the most current 2018 variations of the original platelet-rich plasma, or PRP. Two tubes were placed into a PRP centrifuge (MedEquip Dental Supplies) and spun for three minutes at 3,500 rpm. The short centrifuging time does not allow the blood in the tube to fully clot, but “pre-clots” the blood.
While the blood was being centrifuged, local anesthetic was administered for local infiltration at the maxillary facial edentulous area and at the posterior buccal right, with addition to an IAN block in the lower right. Two tubes were placed in a separate centrifuge for 12 minutes at 1,500rpm.
With a #15 scalpel, we created a vertical releasing incision between the right canine and lateral incisors and also between the left first and second premolars. These were connected by a facial sulcular incision medial to the vertical releasing incisions and a midcrestal incision at the edentulous area. A full-thickness flap was elevated, extending past the mucogingival junction to expose the deficient area as well as bone covering the roots of the adjacent teeth (Fig. 3). A thin ridge with a notable concavity at the edentulous area was confirmed, correlating with what was accessed on the CBCT exam.
A three-sided 1.2mm bur from MedEquip Dental Supplies in a surgical handpiece was used to create multiple decortication points through the cortical bone to the underlying cancellous bone (Fig. 4). This is performed to allow endosteal osteoblasts from the cancellous bone to interact with the graft, grow bone around and within the particulate graft particle, and to accelerate vascularization of the graft and incorporation to the osseous bed.
Next, the donor site would be addressed. A vertical releasing incision was created with a #15 scalpel blade between the right mandibular first molar and second premolar (Fig. 5). A buccal sulcular incision was made on the first and second molars and continued as a crestal incision in the retomolar area buccal to the crestal midline, and a full-thickness flap was elevated to expose the lateral aspect of the mandibular bone (Fig. 6).
An MX-grafter (Maxilon) was used to scrape the exposed bone at the external oblique ridge to harvest autogenous bone that would be incorporated into the graft to be placed in the maxillary anterior. The harvested bone was placed into a sterile dish (Fig. 7). Cortico-Cancellous 100-to-850-micron particle size Particulate graft material (OsteoLife Biomedical) was added to the dish to increase the graft’s volume.
The centrifuged blood taken at the beginning of the appointment had the buffy coat portion (middle layer) drawn from the tubes and placed into the sterile dish with the harvested autogenous bone and particulate graft (Fig. 8). After stirring, the mixture was allowed to sit for 10–15 minutes to allow completion of the clotting phase. The PRP buffy coat contains high levels of platelets that will act as a glue to hold the graft as a flexible mass and prevent displacement during initial healing. The plasma also has high levels of platelet-derived growth factors (PDGF-AB), transforming growth factor (TGF-beta1) and cytokines that can positively affect inflammation, angiogenesis, stem cell migration and cell proliferation.
The flap at the donor site was repositioned and closed with 4-0 interrupted PLA resorbable sutures (Violet, OsteoLife Biomedical) to achieve primary closure.
A 2mm-thick piece of Flexo-Plate Plus (Osteolife Biomedical), sized 15x30mm, was checked over the site to ensure adequate coverage of the defect and extension beyond its lateral borders (Fig. 9). Flexo-Plate Plus is a bendable partially decalcified allograft with a thickness of 0.75–1mm; the bone matrix composing the allograft is ultimately resorbed by the body, eliminating the need for surgical removal of the matrix. This would serve to stabilize the graft to be placed into the facial defect and, upon healing, become the new facial cortical plate. The plate comes with holes predrilled on the left and right aspects to accommodate fixation screws.
The Flexo-Plate Plus was soaked in saline to make it pliable and more easily adapted to the ridge’s curvature. This was adapted to the arch and fixated with a single titanium screw on the left distal to the canine and on the right distal to the right central incisor (MedEquip Dental Supplies, Fig. 10).
The graft mixture of PRP, autogenous bone shavings and particulate graft had coalesced into a flexible mass in the sterile dish with the consistency of a gummy bear candy and is referred to as “gummy bone” (Fig. 11). This was carried intraorally and packed between the fenestrated facial plate and the stabilized Flexo-Plate to create what would be the new ridge width dimensions when healing had completed (Fig. 12).
The graft and Flexo-Plate were covered with a PRP membrane, also referred to by some authors as “PRF,” which would act as a short-term barrier to prevent soft-tissue ingrowth and a source of growth factors while the graft was healing and maturing (Fig. 13). The flap is reapproximated in a tension-free manner and the margins are fixated with 5–0 polypropylene sutures in an interrupted pattern (Fig. 14, p. 74). Postoperative instructions were given and a booklet with instructions was provided to the patient.1 These instructions included:
Applying an ice bag over the affected area—
20 minutes on, 20 minutes off, for two to four hours—to help prevent excessive swelling and discomfort.
Avoiding hot liquids and foods during the first 24 hours after surgery, and then warm salt water rinses four to five times daily for the next week.
The patient was prescribed 24 tabs of Vicodin (5mg hydrocodone bitartrate/30mg acetaminophen) and instructed to take one tablet every six hours for pain. A prescription for a Medrol Dosepak was also given and the patient was instructed to take the pack as recommended.
The patient returned after two weeks for suture removal and site-healing evaluation. Both the donor and recipient sites flaps remained approximated and no gap was noted at the incisions, and healing was progressing with an absence of inflammation. The patient reported he was comfortable and was instructed to continue with warm saltwater rinses for another week to aid in additional soft tissue healing.
The next stage
Four and a half months after surgery, the patient returned; the soft tissue over and next to the site demonstrated an absence of inflammation and appeared healthy, with palpation of the grafted site feeling dense to the touch (Figs. 15a and 15b). A CBCT helped evaluate graft maturation and alterations to the ridge width as a result of grafting; a cross-section of the graft revealed incorporation of the graft and dimensional changes to the ridge width that would now allow implant placement (Fig. 16).
Local anesthetic was administered to the site via infiltration and a full-thickness flap was elevated. The graft was not discernable from the adjacent nongrafted bone and appeared dense to instrument touch, and the defect was filled, resulting in adequate width for implant placement (Fig. 17).
Osteotomies were created to accommodate a 3.7x13mm implant (ImplantVision) at the left central site and a 3.2x13mm implant at the left lateral site, and implants were placed and cover screws attached (Fig. 18). The site was closed with polypropylene sutures in an interrupted pattern and the patient dismissed. Restoration of the implants would occur after an integration period of three to five months. A CBCT taken after implant placement (Fig. 19) demonstrates adequate thickness of the facial bone at the implant to house the implant and allow long-term stability.
A frequent occurrence of loss of teeth in the anterior maxilla is loss of the facial plate, creating osseous dimensions that will not accommodate implant placement. Resorption of the facial plate may present at time of extraction when the tooth has undergone endodontic, periodontic or structural (vertical root fracture) changes. This is often complicated by natural dehiscences and fenestrations found on healthy teeth that worsen when pathology arises.
Reconstruction of the deficient premaxilla has been proposed with multiple treatment options, including:
• Using cortical blocks retrieved from another site (ramus, illiac crest) and fixated with screws during healing.
• Using titanium mesh to cage graft material, allowing the ridge to be rebuilt.
• Splitting the ridge to create a site that could accommodate implant placement.
These approaches all have negatives to their use:
• Cortical blocks require a donor site, for example, which increases morbidity and decreases patient comfort during the healing phase. Additionally, should the block not integrate with the recipient bed, separation may result either at time of implant placement or when under restorative function. Some healing resorption has been reported, and overbuilding the site may be considered to accommodate that loss of volume during healing.2
• Using titanium mesh requires a second surgery to remove the metal mesh and screws, which is performed when implants are ready to be placed into the healed site, but the main reported complication to use is premature exposure of the mesh.3 This may necessitate early removal of the mesh, decreasing the quality and quantity of bone resulting from the graft that was caged by it.4 (Implant success in areas using titanium mesh to contain grafting does show a high success rate even with the complications typically encountered during the healing phase.5)
• With ridge splitting, a minimum width of ridge is needed to be able to affectively split it. Resorption occurs in the vertical dimension at the expense of the less-dense facial plate. Due to the density of the palatal bone, expansion occurs in the facial direction, so if the ridge has lost significant facial osseous structure, expansion cannot be achieved. Minor complications have been reported to ridge splitting when adequate initial ridge width was present that included wound dehiscence and fracture of the facial plate due to a bad split. But complications were at an equal incidence to block grafted sites.6
The technique illustrated in the case presented here is an alternate method that eliminates the need for cortical bone from a donor site and decreases the complications reported with use of titanium mesh to contain the graft. Additionally, width of the residual ridge does not determine if this technique may be used as is the case with ridge splitting. Because cortical fragments are taken from the patient with the bone scraper and mixed with PRP derived from the patient’s own blood, potential for foreign body reactions is minimized. Stem cells from the patient are able to “kick-start” the healing and conversion to bone that has high enough quality to accommodate implant placement after graft healing.
Ideally, implants should be placed into medullary bone in contact with the majority of its surface because this bone is dynamic and active. Cortical bone is denser but lacks osteoblasts and other bone maintaining cells, which may demonstrate radiographic dense bone on contact with the implant but not be able to respond to changes related to function on the implant as well. Using a flexible bone plate (Flexo-Plate Plus) eliminates the need for titanium mesh to contain the graft and it, like a cortical block, becomes part of the healed graft.
The added benefit of this technique over cortical blocks is the resulting bone for implant placement has a medullary quality, and implant placement into it has active bone progenator cells in contact with the implant’s surface. Risk of exposure of the bone plate, unlike titanium mesh, is eliminated because the body does not identify the bone plate as foreign. The overlaying PRP membranes stimulate soft-tissue healing and the stem cells within penetrate into the bone plate, using it as a scaffold to convert it to host bone over time. The “gummy bone” being sandwiched between the plate and the recipient bed has the added advantage over particulates in that it is moldable and does not displace out of the site, as is often observed with particulates.
Reconstruction of the atrophic maxilla to accommodate implant placement can be challenging. Various techniques have been reported to rebuild the deficient area. The technique described here eliminates some of the potential complications associated with other reported techniques and provides high-quality bone that is suitable for implant placement.
2. Lee HG, Kim YD.: Volumetric stability of autogenous bone graft with mandibular body bone: cone-beam computed tomography and three-dimensional reconstruction analysis. J Korean Assoc Oral Maxillofac Surg. 2015 Oct;41(5):232-9. doi: 10.5125/jkaoms.2015.41.5.232. Epub 2015 Oct 20.
3. Lim HC, Lee JS, Choi SH, Jung UW.: The effect of overlaying titanium mesh with collagen membrane for ridge preservation. J Periodontal Implant Sci. 2015 Aug;45(4):128-35. doi: 10.5051/jpis.2015.45.4.128. Epub 2015 Aug 27.
4. Her S, Kang T, Fien MJ.: Titanium mesh as an alternative to a membrane for ridge augmentation. J Oral Maxillofac Surg. 2012 Apr;70(4):803-10. doi: 10.1016/j.joms.2011.11.017. Epub 2012 Jan 28.
5. Ricci L, Perrotti V, Ravera L, Scarano A, Piattelli A, Iezzi G.: Rehabilitation of deficient alveolar ridges using titanium grids before and simultaneously with implant placement: a systematic review. J Periodontol. 2013 Sep;84(9):1234-42. doi: 10.1902/jop.2012.120314. Epub 2012 Dec 3.
6. Gurler G, Delilbasi C, Garip H, Tufekcioglu S.: Comparison of alveolar ridge splitting and autogenous onlay bone grafting to enable implant placement in patients with atrophic jaw bones. Saudi Med J. 2017 Dec;38(12):1207-1212. doi: 10.15537/smj.2017.12.21462.