What Is the Best Technique for Growing Vertical Bone in an Edentulous Area with Thin Buccal- Lingual Dimensions?
J.F. “Eric” Hamrick, DMD | Karl “Tony” Rose, DDS | Scott Frank, DDS
J.F. “Eric” Hamrick, DMD: Vertical bone augmentation, especially in edentulous sites with thin buccal-lingual bone, presents one of the more significant challenges to dental implant surgeons today. It should be noted that the anatomic differences between the two arches require different approaches, especially when dealing with flap release and closure over the grafted site.
For example, when treating a bone defect where teeth Nos. 18, 19, and 20 are missing, it is common to encounter limited keratinized tissue, so the clinician must decide whether to complete a soft-tissue graft before, during, or after the bone graft has been completed. When deemed necessary, I often complete the soft-tissue graft prior to the bone graft, especially in cases where minimal to no keratinized gingiva is present. This improves my ability to retain soft-tissue coverage over the bone graft during the entire duration of graft healing.
In my clinical experience, guided bone regeneration using a combination of autogenous bone chips mixed with bovine particulate (ie, 50-50 ratio) and a non-resorbable barrier (ie, titanium mesh or titanium-reinforced Cytoplast™) has been the most predictable technique to treat these types of defects. If I am unable to procure enough autogenous bone, I sometimes add human bone allograft to the graft mix. With regard to the use of growth factors, I routinely incorporate autogenous platelet-rich plasma and platelet-rich fibrin into the bone graft.
Steps involved in this surgical technique include the following:
1. Use of full thickness incisions over the midcrestal aspect of the surgical site with vertical incisions located anteriorly and posteriorly (ie, at least one tooth beyond the defect being treated).
2. Reflection of full thickness flaps buccally and lingually, well beyond the mucogingival junctions, to gain surgical access for graft placement, and in the case of the posterior mandible, autogenous bone harvesting (ie, ramus buccal shelf). Flap reflection must be adequate for barrier fixation beyond the grafted site.
3. Decortication of the defect.
4. Release of the buccal flap with a periosteal releasing incision, and in cases involving the posterior mandible, blunt release of the mylohyoid muscle fibers in the lingual flap. This is a critical step because inadequate flap release will cause tension at the site of flap closure, possibly resulting in early wound opening and graft failure.
5. Barrier fixation with either bone tacks or fixation screws. When using titanium mesh, tenting screws are often needed to prevent the meshing from collapsing the graft vertically during fixation. Generally, titanium-reinforced Cytoplast requires no tenting screws when correctly pre-shaped. My preference in most cases involves the use of titanium-reinforced Cytoplast (ie, high-density PTFE).
6. Passive, tension-free flap closure with non-resorbable sutures. Horizontal mattress sutures (ie, 5.0 PTFE sutures) are especially helpful directly over the grafted site.
Patient compliance with dietary restrictions and the elimination of temporary prosthetic pressure by whatever means possible are also critical in achieving predictable success in vertical bone augmentation.
This guided bone regeneration technique will provide the implant surgeon with a predictable modality for 3-dimensional bone regeneration, both in width and vertical height. In my opinion, the steepest part of the learning curve involves mastering the critical steps in flap release and barrier fixation. Anatomical variations, especially in the posterior mandible, can make lingual fixation challenging.
Karl “Tony” Rose, DDS:The two “Holy Grails” in dentistry's realm of plastic, reconstructive surgery are rebuilding interdental papillae and vertically constructing the alveolar process. Having been instrumental in the development of guided bone regeneration in the late 1980s, I know that increasing the width of the alveolar process is relatively easy to accomplish when compared with building that same bone's vertical dimension. For proof of clinicians' interest in this topic, one only need look at the American Academy of Periodontology's 2017 Annual Meeting list of courses to see that the vertical ridge augmentation classes were completely sold out.
To achieve vertical growth of the alveolar process or basal bone, all of the principles of plastic surgery must be employed, including the following:
• Maintenance of adequate bone and soft-tissue blood supply without any compromises that would lead to incision line opening and/or soft-tissue fenestration/dehiscence.
• Primary wound closure and maintenance thereof.
• Creation of space for the bone to grow without pressure from soft tissues, dental appliances, teeth, or environmental swelling.
• Physical wound stabilization to ensure that the newly placed bone, whether block graft, particulate graft, or other material, is rigidly secured and protected from forces that would create movement.
• Pre- and postprocedure antibiotic medication.
Personally, I use a graft mixture of human freeze-dried bone allograft, freeze-dried decalcified bone allograft, platelet-rich plasma, platelet-rich fibrin, stem cells, and bone morphogenetic protein-2. The graft is secured by a titanium mesh that is screwed or tacked into place.
Regardless of the technique and materials used, applying the above principles, coupled with a bit of luck, will result in the vertical increase in bone dimension that you seek to achieve on a consistent basis.
Scott Frank, DDS:Reconstructing vertical bone defects continues to be a significant surgical challenge. First, it is important to be realistic when defining what result is considered “successful” or acceptable. In most cases, multiple procedures are required, and the results may be less than ideal. Clearly communicating realistic expectations with the patient and restorative doctor regarding the treatment time, need for multiple surgeries, expected results, and cost is critical. In esthetic cases, clinicians often say that “if you need a little pink (ie, restorative material), then use a lot of pink.” Essentially, if the final result will still require “a little pink” acrylic or porcelain, then it may be more desirable to avoid pursuing significant bone and tissue reconstruction and plan to use more acrylic or porcelain from the outset, such as with an implant-supported hybrid prosthesis.
The risk of complications in the reconstruction of large vertical defects with thin buccal-lingual dimensions is high. To mitigate risk, plan for multiple, staged lower-risk procedures. First, attention should be directed toward reconstruction of the horizontal defect. Typically, I employ guided bone regeneration techniques using mineralized freeze-dried bone and a resorbable membrane or occasionally, a titanium-reinforced non-resorbable membrane. To achieve greater horizontal bulk, the guided bone regeneration also may be combined with block grafting. A wide, aggressive flap is required with tension-free closure. Connective tissue grafting is beneficial to create bulk for the soft tissue as well. Next, address the vertical reconstruction. For smaller vertical defects (ie, 1 to 3 mm), I prefer a non-resorbable titanium-reinforced guided bone regeneration or a screw tent-pole approach. The materials and approach are similar to those used in reconstruction of the horizontal defect, but with attention focused on vertical bulk. For larger defects (ie, 3 to 5 mm), an osteotomy procedure is indicated in addition to guided bone regeneration. For very large defects (ie, greater than 5 mm), an osseous distraction technique is indicated. Again, using a wide, aggressive flap with tension-free closure is very important with vertical reconstructive procedures. The next stage is dental implant placement. Oftentimes, I will complete simultaneous horizontal bone or tissue grafting at this stage. Finally, additional soft-tissue procedures may be required, such as vestibuloplasty or more soft-tissue grafting.
Generally, I am a proponent of immediate implant placement with bone grafting. However, for vertical bone defects, the phrase “one miracle at a time” is applicable. Be sure to allow adequate time for each stage to fully mature and critically evaluate the progress. Expect and become comfortable managing complications such as exposures, poor tissue response, and the possible need for retreatment of a staged procedure.
J.F. “Eric” Hamrick, DMD,
maintains a private practice in Greenville, South Carolina, and has extensive training and experience in periodontal therapy, cosmetic periodontal surgery, pre-prosthetic surgery, and dental implant therapy.
Karl “Tony” Rose, DDS,
maintains a private practice in Chevy Chase, Maryland, and is a faculty member at the University of Maryland.
Scott Frank, DDS,
maintains a private practice focusing on oral and maxillofacial surgery in Buffalo Grove, Illinois, and serves as the director of the local Seattle Study Club chapter, The Elite Dental Group.