Vascularized Buccal Inversion Flap

Postextraction ridge collapse and loss of attached gingiva are inevitable, even with the many current ridge preservation techniques.^1–4  At the time of implant placement, the clinical presentation of the edentulous ridge is often less than 100% of its original full contour due to a combination of buccal lingual ridge resorption and the thinning of the overlying mucosa. Even in the event of immediate implant placement at the time of extraction there is loss of buccal plate thickness.^3,4 

In spite of the great advancements in the past decades in the understanding of the gingival complex around dental implants, there is very little consensus about the significance of the degree of connective tissue surrounding dental implants.^5–7  According to some researchers, there is no correlation between the width of keratinized tissue around natural teeth and the maintenance of peri-implant health.⁸  Some systematic reviews concluded that there is no evidence that the adequacy of peri-implant keratinized tissue has any effect on the health conditions of dental implants.⁷  Likewise, some believe the lack of attached gingiva around dental implants is inconsequential if there is no inflammation in the area. Others have noted, however, that insufficient attached gingiva may result in more buccal bone loss and subsequent loss of gingival attachment.⁹  There is evidence that adequate amounts of keratinized tissue around dental implants may decrease peri-implant gingival inflammation.^10,11  Lang and Loe¹²  suggested that there should be a minimum of 2 mm of keratinized tissue around dental implants.¹³  Regardless of the peri-implant significance of keratinized tissue, the maintenance of buccal contour has beneficial effects from an esthetic perspective and it minimizes the potential of food impaction into a buccal concavity at the implant site.

Various perioplastic techniques using a variety of graft material have been proposed in the literature. These include full-thickness connective tissue grafts, partial thickness subepithelial connective tissue grafts, free gingival grafts, pedicle grafts, and various dermal substitute allografts and xenografts. Most are challenged by the morbidity of having a second surgical site, the added expense of the graft material, or the lack of vitality of the donor graft. The vascularized buccal inversion flap (VBIF) allows the surgeon to achieve minor soft tissue augmentation at the time of implant placement that will enhance the esthetic outcome while increasing the buccal soft tissue thickness around implant sites.

Considering the current lack of consensus on the benefit of increasing soft tissue thickness around dental implants, the opportunity to achieve this end should involve the most cost-effective and simplest technique. The procedure should be one that the clinician can justify by the notion that “it wouldn't hurt to do so.” The efficacy of soft tissue augmentation around dental implants has been examined, and various techniques have been described. Systematic reviews have concluded that for soft tissue volume augmentation, autogenous tissue has to be considered the treatment of choice. Techniques such as an apically positioned flap, while it has the advantages of a vascularized graft, requires a denuded or, at best, a split-thickness exposure of the medial and distal interproximal area of the implant surgical site for healing by secondary intention. Subepithelial connective tissue grafts, however, involve the use of a remote donor surgical site, which results in increased morbidity and patient discomfort.

The modified roll flap technique was originally described by Abrams in 1980¹⁴ to correct soft tissue defects. Adaptations of the technique for use around dental implants were described by Scharf and Tarnow in 1992,¹⁵  Barone et al in 1999,¹⁶  Hurzeler et al in 2010,¹⁷  Giordano et al in 2011,¹⁸  Park and Wang in 2012,¹³  and Saade et al in 2015.¹⁹  In their version of this technique, called the pouch roll technique, Park and Wang use a buccal tunnel rather than buccal vertical relaxing incisions, and the tissue overlying the implant site is de-epithelialized before rolling the tissue to the buccal. A resultant 2–3 mm increase in tissue thickness was reported.¹³ 

More recently. in 2013, Barakat et al²⁰  evaluated the modified roll flap in a randomized clinical trial. They reported that this technique produced a similar increase in tissue thickness of 1.2–3.0 mm and concluded that it was very comparable to the standard palatal connective tissue grafts.

The following cases illustrate the use of VBIF, another version of the original Abrams concept.

This case presents a Div A-w ridge. There appears to be a large quantity of attached gingiva preoperatively (Figure 1a). Most of the crestal tissue, however, would be discarded or apically repositioned by traditional methods. An apically repositioned graft would not allow for primary closure of the flap around the healing abutment, which presents a compromise in the maintenance of the crestal bone during healing.

Presented here is a step-by-step illustration of the VBIF at the time of placement of a root form implant in the upper right second premolar position (Figure 1b through j).

Split-thickness manipulation of the crestal tissue allows for an increase in connective tissue height as well as thickness at the buccal aspect of the implant. The result is an enhanced buccal contour and improved gingival biotype around the implant (Figure 1k through m).

This case illustrates the use of the VBIF at the time of implant exposure. In this case, the site has a relatively thin gingival biotype (Figure 2a) and the mucogingival junction is quite high on the crest of the ridge. An apical repositioning flap will require the interproximal areas to be split thickness and left exposed for regranulation. This case illustrates the steps involved in preparing the crestal attached gingiva to be repositioned buccally (Figure 2b through i). The advantage of the VBIF is the ability to achieve a tidy and accurate closure of the soft tissue around the healing abutment. The improved buccal contour is evident upon completion of the procedure (Figure 2j).

There are many techniques to increase the thickness of the connective tissue over implants. Free gingival grafts and subepithelial connective tissue grafts, however, do not enhance the thickness of the marginal gingiva because they are inserted into a pouch incision.²¹ 

All of the aforementioned versions of the Abrams modified roll flap, with the exception of the pouch roll, were used at the time of second-stage implant exposure. They all involve the de-epithelization of the pedicle graft. The VBIF technique has unique advantages when performed at the time of single-stage implant placement, and it uses the entire column of donor keratinized tissue. Similar to the pouch roll technique, a slight split-thickness preparation is performed to provide a vascularized hinge to invert the pedicle tissue extension. Marginal gingival thickness, and therefore gingival biotype, may be improved. The pouch roll technique, however, requires a tissue thickness of at least 3 mm because the pedicle is de-epithelialized.³²

Since the VBIF technique uses the entire thickness of the tissue overlying the implant site, the surface keratinized epithelium is buried when inverted into the buccal mucosa. This author observed that there is no need for de-epithelialization as long as the entire surface of the keratinized tissue is inverted into the flap. In the horizontal split variation of the technique, as illustrated in case 2, the surface epithelium is oriented in the correct labial direction once inverted. If the entire column of tissue is used, the surface epithelium would in fact be inverted. The epithelial cells, however, appear to clinically reorient without requiring further intervention. The published literature on epithelial cell orientation suggests that it is a highly sophisticated and self-regulated process with specific cell polarity and modulation influenced by complexes of intergrins, adherens, and domain proteins.^22–26  Histologic evidence of this phenomenon would be beneficial to further validate this technique.

With the VBIF technique, a vascularized pedicle graft is prepared using the normally discarded tissue overlying the implant. The column of attached gingiva may be further split horizontally if it is desired to increase the height of the connective tissue labial to the implant, or it may be inverted in its entirety to maximize the increase in tissue thickness. By using the entire thickness of tissue the VBIF is a more versatile technique. This technique modification allows the clinician to fine tune the gingival biotype to harmonize to that of the adjacent teeth by varying the thickness of the inverted flap.

Another feature of the VBIF is the use of a papilla-sparing omega incision extending just to the mucogingival junction. This allows the surgeon to carve out the circular pedicle flap, thereby adjusting the flap to accurately close the interproximal areas around the healing abutment. The papilla on either side of the implant space is spared whenever possible with the omega incision. The exact position of the implant is, therefore, not as critical to achieve accurate closure around the implant abutment. All of the aforementioned techniques require the surgeon to define the exact location of the implant before placement. The omega incision of the VBIF, when used for single-stage implant placement, allows the surgeon the flexibility to achieve primary closure in the event that single-stage surgery is deemed inappropriate during implant placement because the decision to perform the inversion is made after the implant is placed. If additional particulate bone grafting is anticipated for the case, the surgeon may choose an alternative flap design by extending the omega incision to an intrasulcular incision, thereby allowing adequate flap release to accommodate the increased bulk of the particulate graft at the site.

The VBIF is a minimally invasive, simple, and economical technique that is easily implemented to improve the outcome of implant placements. It is uniquely different from previously mentioned techniques because it provides versatility to the surgeon.

Abbreviation

VBIF

vascularized buccal inversion flap