Blood-derived growth factors have been utilized in dental surgery for well over a decade. Their increase in surgical application is due to their ability to easily and practically introduce growth factors at wound and surgical sites to maximize heal- ing while decreasing inflammation. They are relatively inexpensive and practical to
a b c
d e f
g h i
Fig. 11.4 In this procedure, a laterally sliding flap is performed with the addition of a subepithe- lial connective tissue graft (SECTG). In this situation, the pontic site makes an excellent donor site given the abundance of keratinized gingiva without the worry of underlying root anatomy. The SECTG is obtained from the palate and placed over the severely receded root of the molar prior to sliding the flap from the pontic site and suturing it to place. By utilizing an SECTG, the gingival tissues are augmented while also covering the severe recession on the upper molar
use, and because the products come from the patient’s own blood, they are safe. The can also be used in a variety of different forms such as a liquid, a membrane, or a plug. They are often used in a mixture or in combination with other regenerative materials such as bone replacement grafts. Generally speaking, they improve wound healing by accelerating the processes of hemostasis, inflammation, cell prolifera- tion, and tissue remodeling. Most of their dental application has been in the area of regenerative surgery, specifically as it relates to bone regeneration. In its relatively recent history compared to periodontology and implantology, blood-derived growth factors have not been widely studied in periodontal plastic surgery. Nonetheless, a review of the various blood-derived products is offered, and potential for their use in root coverage surgery such as the lateral sliding flap will be reviewed.
11.5.1 Platelet-Rich Plasma (PRP)
Like all of the blood-derived growth factors, PRP requires the use of a centrifuge to procure its contents. What makes PRP “platelet-rich” is that the final product, which is a liquid or gel form, contains at least 1,000,000/1 L in a 5 mL volume of plasma.
Normal platelet counts are 150,000/1 L to 350,000/1 L [30]. The growth factors associated with PRP are the following: Platelet-derived growth factor (PDGF), epi- dermal growth factor (EGF), transforming growth factor-beta (TGF-b), vascular endothelial growth factor (VEGF), and insulin-like growth factor I (IGF-1). Its gel form is derived by mixing PRP with thrombin and calcium chloride. Because of its liquid or gel form, it is not an ideal graft material for root coverage surgery. While it is not an ideal graft material, the growth factors released in its application have been associated with accelerated hard and soft tissue healing mediated through the formation of a fibrin clot [31].
PRP has been reviewed to a fair extent with mixed results in regard to periodontal regenerative therapy and oral surgery. Data in treating gingival recession is limited.
In one study using PRP in combination with subepithelial connective tissue grafts on 40 patients and followed up to 48 weeks, the authors reported no benefit with the use of PRP [32].
In addition to the contradictory clinical benefits, the cost of application of PRP as well as the availability and practicality of using thrombin with the centrifuged blood makes it a less attractive product in root coverage surgery.
11.5.2 Platelet-Rich Fibrin (PRF)
Of all the blood-derived biologic modifiers, perhaps PRF has shown the most prom- ise based on recent studies. While PRP is considered the first-generation platelet concentrate, PRF is considered the second generation. It differs from PRP in that its growth factors are released more slowly over time compared to a quick burst, and the levels of the growth factors remain higher over a period of 10 days [33]. There are several procedural differences in the preparations of PRP versus PRF, but in
summary, PRF has a simpler and quicker preparation and less equipment and mate- rials involved, and it is completely autologous. The primary difference that makes PRF more of an ideal graft material is that it is a three-dimensional fibrin scaffold that closely resembles the types of membranes and soft-tissue grafts used in periodontology.
The big question with PRF is whether or not it can act as a substitute for tradi- tional graft materials such as the common subepithelial connective tissue graft (SECTG). Presently, a few studies have demonstrated similar root coverage results when comparing PRF grafts to the SECTG (Table 11.1). In reviewing this data, several key observations should be made. The longest follow-up period was 12 months. All of the recession defects that were studied were either Miller class I or class II defects. As far as root coverage is concerned, the PRF membranes per- formed statistically comparable (not superior) to the SECTGs.
There is some suggestion in other reports, however, that the keratinized tissue may be less stable after treatment with PRF compared to the palatal grafts (Fig. 11.5a–f). Therefore, it is recommended that when thin biotypes are present or more advanced recession defects such as Miller class III recessions are treated, that SECTGs are used in conjunction with PRF [30]. The primary reason for this recom- mendation is in understanding the differences in SECTGs and PRF as graft materi- als. SECTGs result in more keratinized tissue by genesis, where the graft transfers the genetic potential of the palatal tissue (the typical donor site) to the recipient bed and therefore influences the tissue phenotype of the surrounding tissue [39]. PRF, on the other hand, is a biological matrix of fibrin. It helps to cover exposed roots by promoting and inducing angiogenesis and new tissue at the site of the recession.
Therefore, if the recipient site is keratinized, PRF will enhance this quality of the existing tissue; if it is nonkeratinized, the use of PRF will not result in its
Table 11.1 The results of PRF on root coverage gingival recession defects Author Study design
# of patients
Follow-up
period Treatments studied
Root coverage %
P value Aleksic
(2010) [34]
Split- Mouth;
Miller Class 1 and II defects
19 12 months Coronally advanced flap (CAF) + SECTG vs.
CAF + PRF
88.6 79.9
N/S
Jankovic (2012) [35]
Split- Mouth;
Miller Class 1 and II defects
15 6 months CAF + SECTG
vs.
CAF + PRF
88.7 92
N/S
Eren (2014) [36]
Split- Mouth;
Miller Class 1 and II defects
22 6 months CAF + SECTG
vs.
CAF + PRF
94.2 92.7
N/S
Tunaliota (2015) [37]
Split- Mouth;
Miller Class 1 and II defects
22 12 months CAF + SECTG
vs.
CAF + PRF
77.4 76.6
N/S
Keceli (2015) [38]
Split- Mouth;
Miller Class 1 and II defects
40 3 and
6 months
CAF + SECTG vs.
CAF + SECTG + PRF 79.9 89.6
<0.05
keratinization. This is the rationale behind utilizing both a SECTG and PRF together when grafting Miller class III recessions or recessions where thin, nonkeratinized tissue is present.
11.5.3 Fibrin-Assisted Soft-Tissue Promotion (FASTP) [40]
From Table 11.1, it is noted that various percentages of root coverage were achieved despite comparing only two treatment groups: SECTG vs. PRF. In addition, these results are also supported in a recent systematic review and meta-analysis [41]. As mentioned, PRF and conventional graft materials heal via two very different mecha- nisms. In order to maximize the volume and characteristics of gingival tissue using PRF for root coverage surgery, the FASTP technique was introduced.
FASTP for root coverage differs from the previously mentioned studies in two ways: First of all, the flap design used is not a conventional coronally advanced flap.
Instead, it uses a papillae-sparing flap design that utilizes vertical incisions in the mucosa which provides the access for the PRF to be placed over the root surfaces.
This flap design is very similar to that described for the vestibular incision subperi- osteal technique access (VISTA) technique [42]. Second, rather than use PRF mem- branes in a conventional grafting manner where only one membrane/graft is placed over the teeth, the authors recommend using three to four membranes for every two teeth. Like typical grafting procedures, proper flap management, adequate release of the tissue, space maintenance, and tension-free passive closure are the keys to success for this procedure. Given the recent introduction of FASTP, lessons to learn from it for future study in lateral sliding flaps are to utilize more PRF membranes per tooth and realizing that they are not the same as conventional graft materials such as SECTGs. The use of more PRF membranes during root coverage surgery to capitalize on the increase in growth factors and leukocytes is an idea that will be observed and evaluated in the future.
a
d e f
b c
Fig. 11.5 When PRF was first introduced in root coverage surgery, it was used as shown here, like a traditional graft material. This case demonstrates a typical result when grafting with PRF in the absence of preestablished adequate keratinized gingiva in a Miller class III recession defect involv- ing the loss of interproximal bone. Notice how root coverage is achieved, but the facial gingival tissues remain thin and nonkeratinized