AlloDerm®: An Effective Alternative to Palatal Donor Tissue for Treatment of Soft Tissue Alveolar Ridge Defects

April 28, 2009
AlloDerm cover image

When I was in dental school, I did a graft on my cousin and fellow dental student, David, with the help of one of our instructors. David was getting ortho done at the school and had minimal attached gingival on the facial of an upper bicuspid. Since the archwire was going to slightly expand his upper arch, the graft was necessary prior to starting the orthodontics. Cutting into your cousin’s palate with a Bard-Parker in the first year of clinical dentistry was a little scary for me. Anesthetizing the entire left hand side of his palate was a little out of my comfort zone as well. However, both of those paled in comparison to watching him try to eat and drink in the days afterwards since we were roommates. He had a lot of pain in that next week, especially when the perio pack fell off about five minutes after the surgery. Dr. Edward Allen shows an elegant method of avoiding using donor tissue from the palate when performing a graft. I can think of many patients who have refused this type of esthetic periodontal surgery because of the palatal surgery, and the option Dr. Allen demonstrates allows patients to have the graft done without the palatal procedure.

Soft tissue grafting using palatal donor tissue, primarily to increase the zone of attached gingiva, was introduced more than 40 years ago.1 Subsequently, there have been numerous reports describing use of palatal connective tissue grafts for treatment of gingival recession defects and soft tissue alveolar ridge defects.2-14 Surgical applications of soft tissue grafting have been improved by the introduction of microsurgery with more precise incisions, closer wound apposition, reduced hemorrhage and reduced trauma at the surgical site.15 Microsurgery uses smaller instruments and smaller suture, providing less invasive surgery and less complicated postoperative sequellae.

Additionally, in patients who seek treatment, anatomical or medical concerns may be present that rule out use of the palate as a donor source. For these reasons, an effective substitute for palatal donor tissue is necessary.

In spite of significant refinements in surgical technique, many patients remain fearful of palatal surgery and resist recommendations for treatment involving soft tissue grafting.

AlloDerm® Regenerative Tissue Matrix

AlloDerm® (LifeCell Corporation; Branchburg, N.J.), widely used in both medical and dental surgery over the past 12 years, is an acellular dermal matrix derived from donated human skin tissue supplied by tissue banks in the United States, utilizing the standards of the American Association of Tissue Banks and Food and Drug Administration (FDA) guidelines. Human skin consists of both epidermis and dermis. In nature, the dermis contains a framework of cells and structural components that allow it to regenerate and replace itself continually throughout life.

After determining that donated skin tissue is eligible for transplantation, LifeCell processes the tissue. When AlloDerm is prepared, the human donor tissue undergoes a multi-step proprietary process that removes both the epidermis and the cells in the dermis that can lead to a recipient response, tissue rejection and graft failure, without altering the structural and biochemical components of the matrix. The resulting extracellular matrix is freeze-dried by a proprietary method to preserve the tissue without the formation of damaging ice crystals. This entire process is performed under stringent documented quality-controlled systems that have been demonstrated to reduce HIV-l and the surrogate for hepatitis C virus to nondetectable levels (>99.9%). Histology testing is completed on each lot of final product to verify cell removal. Cell removal ensures against viral replication and renders free particles more susceptible to detergent inactivation. In addition to viral safety, both incoming tissue and final products are screened for bacterial and fungal growth and deemed negative. The remaining fibrous framework of biologically active components and vascular channels stimulates the recipient to initiate the intrinsic tissue regeneration process, integrating and replacing the graft tissue with newly formed dense, collagenous connective tissue.16,17,18 Thus, AlloDerm provides a viable biologic substitute for palatal donor tissue.

Use of AlloDerm in Periodontics

AlloDerm is used as a substitute for palatal connective tissue in the treatment of gingival recession and soft tissue alveolar ridge defects. Randomized controlled clinical trials have demonstrated that root coverage with AlloDerm is equivalent to that obtained with palatal donor tissue in the treatment of gingival recession.18-22 An increase in marginal tissue thickness equivalent to palatal tissue grafts has been demonstrated at six and 12 months postoperatively, by both clinical and histometric analysis.18,21 Equivalent attachment to the root surface has been found by histologic evaluation of human bock sections at six months postoperatively.18 Case reports have demonstrated effective restoration of buccal alveolar ridge defects with AlloDerm grafts.23,24 A recent case series described the successful repair of oronasal fistulae with AlloDerm grafts.25 This report describes techniques for using AlloDerm in the treatment of one- and two-tooth buccal alveolar ridge defects.

Ridge Augmentation Surgical Technique

For a single missing tooth site, place a semilunar incision with a #15 blade beginning at the deficient ridge crest, curving facially; do not cross over the papillae into sulci of the adjacent teeth (Fig. 1). This incision should extend to the bone surface. Create a facial pouch in the defect area by sharp supraperiosteal dissection, extending approximately 6–10 mm apical to the ridge crest. Place incisions in the proximal sulcus of each adjacent tooth to mobilize the papillae. Measure the width and depth of the pouch, approximately 6–10 mm horizontally and 8–10 mm vertically. Following two successive washes in normal saline, the AlloDerm is trimmed to create a graft of proper width and a length two times the depth of the pouch.

Fold the graft in half longitudinally, approximating the basement membrane surface (Fig. 2), and while grasping the approximated ends with Microsurgical Corn Suture Pliers (Hu-Friedy; Chicago, Ill.), introduce the folded end of the AlloDerm graft into the recipient pouch with an Allen Micro-elevator (Hu-Friedy) (Fig. 3). Place an interrupted suture through the two exposed ends of the AlloDerm graft coronally (Fig. 4), recapture the needle, then push the graft ends just under the lip of the pouch. Pass the needle through the palatal wall of the pouch to secure the coronal aspect of the graft (Fig. 5). Replace the provisional fixed partial denture (FPD) with the ovate pontic lightly contacting the graft.

For two adjacent missing teeth (Fig. 6), place a semilunar incision at the ridge crest as described above at the location of each missing tooth, leaving the papillary area between the missing teeth intact (Fig. 7). Create a supraperiosteal pouch by sharp dissection facial to both missing teeth, tunneling under the papillary area. Measure the width and depth of the pouch and trim an AlloDerm graft with a width equal to the span of the two-tooth site and a length twice the pouch depth. Fold the AlloDerm graft in half longitudinally and secure the margins with 6-0 resorbable suture (Fig. 8). Introduce the graft into the pouch through one of the semilunar incisions (Fig. 9), align horizontally within the pouch, and secure the coronal graft border to the palatal pouch wall with 6-0 suture (Fig. 10). Replace the provisional FPD with the ovate pontics lightly contacting the graft (Fig. 11).

Figure 1

Figure 1: Semilunar crestal incision avoiding sulci of adjacent teeth.

Figure 2

Figure 2: Folding AlloDerm graft in half longitudinally, basement membrane surface approximating itself.

Figure 3

Figure 3: Inserting AlloDerm graft into the pouch with an Allen Micro-elevator.

Figure 4

Figure 4: Passing the suture through the two ends of the folded AlloDerm graft.

Figure 5

Figure 5: Suture tied to palatal wall of pouch.

Figure 6

Figure 6: Moderate to severe buccal alveolar ridge defect at the site of the missing left lateral incisor and canine.

Figure 7

Figure 7: Semilunar crestal incisions approximating each missing tooth.

Figure 8

Figure 8: AlloDerm folded and sutured.

Figure 9

Figure 9: Inserting AlloDerm into the pouch through the crestal opening.

Figure 10

Figure 10: AlloDerm positioned within pouch over defect area and sutured to palatal wall of pouch.

Figure 11

Figure 11: Provisional FPD placed following conversion of ridge-lap pontics to ovate form.

Postoperative care includes the following:

  1. Systemic antibiotics for 10 days
  2. Chlorhexidine mouthrinse for two to three weeks
  3. Pain medication, as needed
  4. Ice applied to face for 24 hours, intermittently, at 10 minute intervals
  5. Cold liquids for the first three meals
  6. No mastication or toothbrushing at surgical site for two to three weeks
  7. Remove surface sutures at two to four weeks

Initial postoperative swelling peaks approximately three days after surgery and gradually subsides over a two-week period. By six to eight weeks postoperatively, the gain of ridge contour will approximate the thickness of the layers of AlloDerm placed (Fig. 12). If additional contour is needed in larger buccal defects, a second augmentation may be performed at eight weeks following the initial procedure. The soft tissue form gained will be maintained long-term provided ovate pontics remain in contact with the restored ridge.

Figure 12

Figure 12: Improved ridge form three months after surgery. A second graft at the lateral incisor site would result in complete restoration of ridge contour. Esthetic crown lengthening was performed on the right side at the same time as the ridge augmentation.

Discussion

Developed more than 10 years ago, AlloDerm is a safe and effective biomaterial for use as a substitute for palatal connective tissue in root coverage grafting and soft tissue ridge augmentation procedures. There have been no reports of disease transmission as a result of AlloDerm use in medical or dental applications. AlloDerm has proven equivalence to palatal connective tissue for root coverage procedures in randomized controlled clinical trials.19,20,21,22 AlloDerm provides distinct advantages over palatal connective tissue in that it does not require a second surgical site to obtain donor tissue, and provides an unlimited amount of tissue to treat multiple sites at one appointment. Patient acceptance of recommended treatment is increased due to elimination of the fear associated with use of the palate for harvesting donor tissue. When compared to the use of palatal donor tissue, the postoperative experience with AlloDerm is less complicated, without the sequellae associated with palatal donor surgery. Further, patients are not as reluctant to return for additional AlloDerm grafting procedures when required.

A successful surgical outcome is dependent on proper pontic and abutment form beginning the day of surgery and continuing through the healing phase. The same is true for the final restorations in order to ensure long-term maintenance of ridge form.

AlloDerm grafting is effective for restoring buccal ridge form at sites of ridge deformities due to developmental defects, trauma or natural ridge resorption. Complete restoration of form is related to the anatomy of the site and the number of contiguous missing teeth. Results are best at sites without loss of proximal bone or soft tissue on the teeth adjacent to the edentulous ridge and at one- and two-tooth sites. A gain in tissue thickness of approximately 3 mm can be expected from a single surgery using a folded AlloDerm graft. At sites with greater than 3 mm of buccal deficiency, a second surgery may be necessary. Minimal increase in vertical dimension can be achieved with the technique described.

Long-term maintenance of the soft tissue form achieved is dependent on the support of the adjacent bony walls proximally and the ovate pontic form crestally. Without the support of the ovate pontic during the healing phase, there will be loss of the coronal portion of the augmented site. Shrinkage of the ridge will occur without the support from the convex form of the pontic maintaining the concave pontic site in the ridge. Such shrinkage is commonly seen where modified ridge-lap pontics are used. A successful surgical outcome is dependent on proper pontic and abutment form beginning the day of surgery and continuing through the healing phase. The same is true for the final restorations in order to ensure long-term maintenance of ridge form.

Conclusion

The surgical techniques outlined represent a refinement in the approach to soft tissue ridge augmentation. The procedures are minimally invasive microsurgical techniques that enhance wound stability while reducing morbidity due to the use of AlloDerm. Reduced discomfort and improved patient satisfaction characterize the postoperative period.

To contact Dr. Edward Allen, call 877-696-1414, email center@epallendds.com or visit dredwardpallen.com.

References

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  2. ^Miller PD Jr. Root coverage using a free soft tissue autograft following citric acid application. Part 1: Technique. Int J Periodontics Restorative Dent. 1982;2(1):65-70.
  3. ^Raetzke PB. Covering localized areas of root exposure employing the “envelope” technique. J Periodontol. 1985 Jul;56(7):397-402.
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