Maxillary Tuberosity: An Overlooked Site for Block Grafts Rich in Cortical-Cancellous Bone

Dr. Steven L. Rasner
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An Overlooked Site for Block Grafts Rich in Cortical-Cancellous Bone

A well-known consequence of tooth loss is the concomitant loss of the supporting alveolus. The literature demonstrates 29% to 63% horizontal bone loss and 11% to 22% vertical bone loss occurring within 6 months after an extraction.1 At 12 months, as much as 50% reduction in width of the alveolar ridge has been reported.2 Ideal implant position is the foundation for maximum aesthetics and functional predictability. Many socket preservation therapies have been prescribed. Numerous studies have repeatedly demonstrated that autogenous bone remains the gold standard for its obvious osteogenic capabilities.3 For years, surgeons have searched for the ideal donor area to assist in dental alveolar reconstruction. Possible harvesting sites have ranged from extraoral areas, such as the iliac crest, to more traditional intraoral areas, such as the ramus shelf and mandibular symphysis. The literature is rich with numerous reports on the advantages and disadvantages of each site. The maxillary tuberosity has typically been regarded as a site that is useful primarily for harvesting particulate bone for filling defects. This article is intended to re-examine the tuberosity as a predictable source for the block graft. Although the tuberosity was described as a donor source by many, Dr. Carlos da Rosa offered considerable contributions to this exciting alternative, culminating in 2014 with his book, Immediate Dentoalveolar Restoration: Immediate-loaded Implants in Compromised Alveolar Sockets.4

Figure 1. Incision for a tuberosity harvest. Figure 2. Full donor site reflection.
Figure 3. Donor site preparation (with 1.0 mm decortication). Figure 4. Harvesting chisels.
Figure 5. Use of a wedge-shaped chisel. Figure 6. Harvested tuberosity block graft.
Figure 7. The block fixated with 1.2- × 6.0-mm screws. Figure 8. Plasma-rich fibrin—last layer over 100% autogenous.

ADVANTAGES OF THE MAXILLARY TUBEROSITY AS A DONOR SITE
One of the unique properties of a tuberosity block is the combination of the cortical portion for structural support and the osteogenic qualities of the underlying cancellous bone.5 Another significant advantage is relatively simple access with minimal complications.6 The harvesting of this site begins with a careful analysis of the patient’s tuberosity via a CT scan to assess bone quantity, width, and height and the proximity of adjacent structures. Access requires a simple mid-crestal or slightly palatally displaced incision from the distal of the terminal molar through the most distal aspect of the tuberosity (Figure 1).4 This is typically carried out with a 12 blade, although angled blades are preferred. In some instances, an oblique vertical releasing incision is made on the buccal of the terminal tooth. This opens up access and visibility. The flap is then reflected with #2-4 Molt elevators (Figure 2). This part of the surgical procedure is undertaken only after the recipient site has been fully prepared to receive the donor bone (Figure 3).

Figure 9. Pre-block axial CBCT (Dentsply Sirona). Figure 10. Post-block axial CBCT (Dentsply Sirona).
Figure 11. Clinical implant placement.

HARVESTING THE GRAFT
To optimize outcomes, it is recommended that the surgeon procure chisels (Karl Schumacher) designed for this harvest. They are typically available in widths of 6, 8, and 10 mm. The chisels have millimeter-calibrated cutting edges (Figure 4). You should select a chisel that is 2.0 mm wider than the expected graft size. The chisels are available in straight and wedge-shaped. The straight chisel is used for obtaining several “layers” from the harvest for multiple defects. It requires a patient with adequate opening ability. It can also be employed on the buccal aspect of the tuberosity of a patient whose ability to open is compromised. The wedge-shaped chisels are utilized when more volume (thickness) is desired and access is limited4 (Figures 5 and 6). The harvested site is temporized with moist surgical gauze while the recipient site is addressed. The harvested graft is placed in sterile saline. Additional particulate cancellous bone can be harvested from the same site with a Molt elevator to fill in any gaps around the block graft. The donor area is then irrigated, inspected for any possible sharp edges that require filing, and sutured in an anterior-to-posterior direction. The reader should perform further research on the chisel technique in the referenced article by Aboushara et al.5

TREATING THE DEFECT
The graft is then carefully modified with a rongeur, not a handpiece. In this case, micromovement is prevented with 2 bone screws of 1.2 mm in diameter and of the appropriate length (BioHorizons). Gaps are filled with particulate, and the graft is covered with a cross-linked collagen membrane and/or platelet-rich fibrin. The recipient site is then closed with non-resorbable PTFE suture (Figures 7 and 8).

A second surgery for implant placement is planned at 16 weeks. At this surgery, a full-thickness flap is again elevated, the bone screws are removed, and the implant is placed (Figures 9 to 11).

CONCLUSION
This article was intended to provide the implant surgeon with an accessible donor site that has been previously overlooked for block graft potential. Although the author’s present sample is limited, the reduced postsurgical morbidity and early augmentation analysis yield encouraging signs of a predictable source of bone harvest.


References

  1. Tan WL, Wong TLT, Wong MCM, et al. A systematic review of post-extractional alveolar hard and soft tissue dimensional changes in humans. Clin Oral Implants Res. 2012;23(suppl 5):1-21.
  2. Schropp L, Wenzel A, Kostopoulos L, et al. Bone healing and soft tissue contour changes following single-tooth extraction: a clinical and radiographic 12-month prospective study. Int J Periodontics Restorative Dent. 2003;23:313-323.
  3. Sakkas A, Wilde F, Heufelder M, et al. Autogenous bone grafts in oral implantology—is it still a “gold standard”? A consecutive review of 279 patients with 456 clinical procedures. Int J Implant Dent. 2017;3:23.
  4. da Rosa JCM. Immediate Dentoalveolar Restoration: Immediate-loaded Implants in Compromised Alveolar Sockets. Quintessence Publishing; 2014.
  5. Aboushara MA, Eldibany MM, Hassan NP. Evaluation of the use of alveolar block from maxillary tuberosity for augmentation of anterior maxillary defects. Alexandria Dental Journal. 2018;43:111-116.
  6. Khojasteh A, Behnia H, Shayesteh YS, et al. Localized bone augmentation with cortical bone blocks tented over different particulate bone substitutes: a retrospective study. Int J Oral Maxillofac Implants. 2012;27:1481-1493.

Dr. Rasner earned his DMD degree from the University of Pennsylvania. He has completed the Misch International Implant Institute curriculum and the Pikos Institute continuum. Dr. Rasner has been teaching for 20 years. His courses, “Atraumatic Extractions for the GP” and “The Bulletproof Guide to Implant Success,” have been popular at ADA and AGD component society meetings, as well as at the national ADA meeting. His newest course, “Hands-on Atraumatic Extractions for the GP,” features 2 days of live-patient experience in his office. He has authored 3 books and more than 50 industry and journal publications. He can be reached at drrasner@aol.com.

Disclosure: Dr. Rasner reports no disclosures.

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