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Xenograft vs. autograft

Using a 3-D collagen matrix for vestibuloplasty

09.07.2018
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No painful graft harvest and very good color and texture match surrounding tissue - these are major advantages when performing a vestibuloplasty with Geistlich Mucograft®. Now there is long-term data over five years.

Dr. Christian Schmitt | Germany

2 mm of keratinized mucosa around an implant seems to have a positive impact on peri-implant tissue health.1 The most common methods for widening of the keratinized mucosa are an apically positioned flap or a vestibuloplasty.2 A secondary granulation of the resultant wound surface is not ideal due to postoperative morbidity and wound contraction with a high tendency for muscular reattachment.2-4


Autologous grafts from the palate

Autologous soft tissue grafts from the palate – such as free mucosal grafts or connective tissue grafts – are the gold standards for covering a wound surface. They reduce postoperative contraction and improve the regenerative result.2,3,5,6 Furthermore, autologous grafts show reproducible clinical results in terms of treatment, integration, shrinkage and long-term stability (Fig. 1). However, disadvantages of autologous tissue grafting are:
• Necessity for palatal harvest with additional surgical risks,2–4
• Patients’ harvest site morbidity,6
• Limited availability of grafts,3,4
• Prolonged surgery time,2–4,6
• Poorly matched texture and color, when using free mucosal grafts.4,6



Biological adaptation to the surrounding epithelium

When using autologous mucosa from the palate, directly after healing and also long-term over five-years, the regenerated soft tissue in the target region shows no change in texture and color in comparison to the original graft.3 This effect, which is detrimental to esthetics, can be explained by the biological determination of the mucosa removed from the palate, which remains unchanged over time.
This confirms the hypothesis that autologous mucosa from the palate is revascularized basally after grafting into the target region. Therefore, free mucosal grafts are contraindicated in the exposed esthetic zone.3
When using connective tissue grafts or Geistlich Mucograft®, a clinical appearance comparable to the surrounding tissue manifests after integration. The reason is that the biological information from the epithelium is absent, and an epithelial layer matching the target region forms after neo-epithelialization of the graft.6 (Fig. 3)


Long-term stability of the grafted mucosa

Measurements of the shrinkage of the augmentation zone over time have revealed that a substantial shrinkage reduces graft width and takes place from initial healing until three months after surgery.3,4,6 The regeneration result then stabilizes with only minimal changes (follow-up: currently five years).3 Anticipated shrinkage should be planned in order to avoid unsatisfactory results and disease recurrence. We recommend an “over-augmentation” equivalent to anticipated shrinkage.
After five years with free mucosa grafts, the keratinized peri-implant soft tissue has a width of 8.4 ± 2.4 mm and 6.2 ± 1.2 mm with Geistlich Mucograft®.3


Surgery time

As for operation time, the literature concurs that using collagen matrices in comparison to using autologous transplants from the palate shortens operation time significantly by approximately 15–20 minutes.4,9 This, however, depends on the size of the region to be augmented and the number of grafts taken4 and is relative when small grafts are harvested.

Dr. Christian Schmitt

Dr. Christian Schmitt | Germany

Clinic of Oral and Maxillofacial Surgery

University Clinic Erlangen-Nuremberg

Erlangen

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