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Soft Tissue Assessment and Enhancement in Implant Dentistry
Edgard El Chaar
Department of Periodontics, University of Pennsylvania, Dental Medicine, Philadelphia, PA, USA
Introduction
With the advent in Implant surface technology, the need of having keratinized tissue (KT) became an important point in the long run in order to have a sustainable healthy dental implant. In the world work shop in periodontics (Berglundh et al. 2018), it has been stated that a minimum of 2 mm appears to be the magical number to achieve this goal. Before a dental implant is placed and from the moment of treatment planning, the clinician has to assess both the hard and soft tissues. The parameters to place a dental implant have been set and well established as the 3D implant placement (Buser et al. 2004) in relation to the amount of bone facial to the placed implant and its relation to the adjacent teeth especially in partially edentulous patients. Now we will need to add to the agreed‐on amount of KT. That is now known as the phenotype would it be around natural tooth, a site to be extracted or a site for implant placement. Clinicians today must balance biology, functionality, and esthetics when treatment planning and executing implants.
In most of the instances, these procedures will be used to correct an esthetic or functional failure of placed implants. Failures that compromise the health of an implant fixture are inflammatory in nature and include peri‐implantitis and peri‐implant mucositis. While the result of these pathologic changes is often unesthetic, the underlying cause of the disease must first be addressed before steps can be made to restore the esthetics. When an implant is healthy but the result of the surgical and prosthetic placement is unsatisfactory to both the patient and clinician, immediate steps can be taken to achieve a more desirable esthetic result. As with all dental treatment, the disease process and pathology must be eliminated or controlled before steps can be taken to repair the damage that it has caused. It is best to take measures to prevent both infectious and esthetic implant failures through proper planning and surgical execution.
Some common esthetic failures are loss of interdental papilla “black triangles,” midfacial gingival recession, a non‐harmonious gingival margin, buccal concavities, and translucency of the implant body or prosthetic margins. There are steps that can be taken to avoid these failures during the planning and surgical execution of implant placement including augmentation prior to implant placement, flap design during placement, and soft tissue management during second stage. The fundamental point is to assess the hard and soft tissue prior to implant placement in order to determine if there is a need for augmentation prior to the placement. Bone height and thickness are major determinants of soft tissue contours, which will affect the implant placement subsequently will dictate the tooth morphology, which will determine the contact point from the crest of bone and finally this will lead to the tissue quality and quantity important for the long term success of the dental implant.
This chapter will discuss manipulation and/or augmentation of existing soft tissue, rather than prosthetic gingiva, in combination with implant‐supported crowns, to achieve an ideal esthetic result.
Techniques to Create Contour, Thickness, and Increase Keratinized Tissue
A‐Flap Management
Over the years we all have been faced with the concept of flapless versus flap and many designs have been promoted for the latter. The clinician has to always remember that we are replacing a lost dental organ which is our ultimate goal. By setting that goal we need to start thinking from it backwards which I often quote as “set your goal and walk your way back.” Would it be an anterior or posterior tooth, it has a specific shape at its coronal level. A central maxillary incisor is triangular, canine is oval, transitioning from the premolars to the molars it becomes a rectangle; yet the coronal part of the implant is a circle regardless of that implant diameter. All of that takes place at the flap level.
Gomez‐Roman (2001) showed that even if there is adequate crestal bone height prior to implant placement, the flap design can affect the amount of crestal bone resorption following placement. By preserving the proximal tissue of the adjacent teeth “limited flap design” a 0.29 mm bone was noted versus a 0.79 mm versus “widely mobilized flap procedure,” which includes the proximal tissue. Another advantage of preserving that tissue is giving the clinician a visual marker to keep the 1.5 mm from adjacent teeth during the placement (Buser et al. 2004; Esposito et al. 1993).
For years, I personally used and taught my residents and colleagues to use the H design, in which you evaluate the position of the adequate amount of KT and you initiate your crestal incision followed by two cross arches on the buccal and lingual, extending up to mucogingival line (MGL) on the buccal side and enough on the lingual to allow exposure of the crestal bone. On the buccal side, it can extend passed MGL in case an apically repositioning is needed. Although it covers all the criteria cited earlier, suturing the flap and controlling the level of it either coronal or apical becomes a challenge since we have a raised flap on the lingual and we need to suture together the buccal and lingual component. To avoid this hurdle, I designed a flap that I call the U shape, where the crestal incision is made depending on the adequate KT that the clinician judged is necessary coupled with two buccal only crestal incisions extending up to MGL. The lingual portion at the crestal level is elevated without being mobilized. The major advantage of this design is the clinician can control the positioning of the flap either coronal or apical depending on the esthetic assessment done during the treatment planning, namely, the Pink Esthetic score, assessment of papilla height, and pink and white esthetic score in gingival display (Figures 20.1–20.5).
Figure 20.1 Occlusal view showing the mucogingival line buccal more coronal with less than 1 mm keratinized tissue buccal.
Figure 20.2 The U shape incision to the buccal with parallel vertical incisions.
Figure 20.3 Full thickness flap elevated, exposing the implant.
Figure 20.4 Flap sutured at the needed coronal level matching the adjacent margins.
Figure 20.5 Six weeks healing revealing a good band of keratinized tissue with buccal contour continuous with the adjacent teeth and coronal levels of tissue similar to the adjacent as well.
As a side technical important note, to position the flap coronally you position the flap at the level needed and you place the first suture coronally on both sides. It is important that the two cross arch incisions on the buccal are parallel and not widened at the apical part to avoid shrinkage of the coronal part of the flap. If so, it will difficult to have enough width to cover the buccal aspect. For the apical position, it’s the opposite, you place the flap in the desired place and you suture first the apical part followed by the coronal.
Roll Technique
A roll flap procedure was developed by Abrams in 1980 as a means of correcting small Seibert class I ridge defects that result in a buccal concavity. This technique is useful in correcting a ridge defect at a future site for a pontic, or a small buccal concavity present in the area where an implant has been placed. If there is an implant present in the site, this technique can be used in combination with the uncovery procedure. This technique employs a pedicle connective tissue graft that is harvested from the palate and then folded under into a pouch created on the buccal. The augmentation provided by the pedicle is meant to match the root eminences of the adjacent teeth therefore if the edentulous span is greater than one tooth multiple pedicle grafts may prepared.
The roll technique presented here is a modification to the roll technique introduced by Scharf and Tarnow in 1992 (Scharf and Tarnow 1992) and will be illustrated in the series of figures (Figures 20.6–20.11). The main modifications, no vertical incisions on both sides and the shape of the harvested connective tissue is trapezoidal not rectangular as designed by Schaarf and Tarnow. It begins with making three measurements. First measure from the crest of the ridge or the anticipated gingival margin of the future crown to the most apical extent of the concavity, second measure the apical width 1 mm from mesial side of each adjacent apex of the adjacent teeth, and third measure the interproximal distance between the adjacent teeth coronally accounting for the papillary like tissue to be left on the side of each tooth. Those lines of measurements will form a trapezoid shape. These measurements will determine the size of the pedicle that needs to be harvested from the palatal area. The buccal limit of the donor site is the mid‐crest of the pontic site preparation or above the middle of the cover screw for implants. Delineate the donor site with incisions extending to the underlying bone in all areas except the crestal limit, which will serve as the base of the pedicle. Once the site is delineated de‐epithelialize that area and sharply elevate the connective tissue pedicle to full thickness leaving exposed bone on the palate. Some authors suggested dissecting the pedicle graft leaving behind periosteum, but doing so risks severing the supra‐periosteal capillary bed that may lead to flap necrosis and jeopardize the end result. Full thickness elevation also reduces risk of perforation of the pedicle flap, allows for a thicker graft, and maintains the supra‐periosteal blood supply to the graft. Once the pedicle is elevated to the buccal transition area, create a full thickness pouch in the area of the defect on the buccal following the planned trapezoidal architecture. After elevation of the pouch, roll the pedicle graft into the area of the buccal defect. At this time the pedicle may be trimmed and adjusted to fit. Once the graft is in place, place two stabilizing sutures coronally on either side of the trapezoid. At this point, the healing abutment can be placed and any periosteum or any osseous structure over the implant cover screw should be removed.
Figure 20.6 Buccal view showing the soft tissue buccal discrepancy.
Figure 20.7 (a) The implant was disconnected to let the tissue grow over it and bury it (b).
Figure 20.8 The trapezoidal shaped incisions were made on the palate to accommodate the needed tissue on the buccal, full thickness of that tissue were made after de‐epithelizing the surface.
Figure 20.9 Tissue was rolled under the pouch made buccal and part of it was kept coronal to match the adjacent tooth. A narrow healing abutment was placed to support the tissue.
Figure 20.10 Eight weeks healing of the rolled tissue (a) buccal view and (b) palatal showing the fill of the donor site and the placed healing abutment.
Figure 20.11 Final prosthesis in place with marginal tissue matching the adjacent tooth.
Autograft Subepithelial Connective Tissue (CTG), a Free Gingival Graft (FGG), or Allograft Dermis
Used in lack of KT surrounding implant fixture or in case there is not enough tissue present to be displaced apically, or rolled buccally, one may employ a free gingival graft (FGG), connective tissue autograft (CTG), or allograft dermis. Connective tissue grafts can be used to increase tissue thickness and/or to increase attached KT in areas of esthetic concern. An FGG can also be used to increase a zone of KT but will heal with a more blanched looking tissue and it is not advised in areas of esthetic concern. Alternatively, and for the same reason, an allograft dermis can be used to increase KT. The main advantage of using a connective tissue graft is the color match with the surrounding tissue compared with the FGG. These techniques are easiest to perform at time of the second stage surgery or implant placement but can be done with a prosthesis in place if necessary but will require a more diligent and refined execution.
Free Gingival Graft (FGG)
This technique is mainly used to increase the amount of KT while preserving the marginal gingiva. A sub‐marginal incision is made down to the bone in case of implant that is already exposed or sub marginal to the existent KT in a healed ridge. The extent of the incision depends on the extent of the area to be treated. At the margins of this area extend the incisions curved apically. A full‐thickness flap was reflected.
In case when implants are not uncovered, an incision is made at the MGL and a full‐thickness flap was reflected to expose the previously placed implant.
In both instances, the flap is apically positioned and stabilized with tacks to establish the new vestibule. Once the flap is secured, measure the recipient area to determine the amount of tissue that needs to be harvested from the palate. Next, harvest a full thickness graft from the palate to place in the area of deficient tissue. The donor tissue should be taken at least 2 mm from the palatal gingival margin as tissue contractions occurs during healing and recession may occur as a result of the wound edge being too close to teeth. The shape of the donor tissue is outlined with a scalpel at a right angle to the palate at the desired depth, which can be gauged by the bevel on a #15C scalpel blade (approximately 1 mm). The blade is then turned parallel to the palate and a graft of the desired uniform thickness is removed by sharp dissection from the palate. The donor tissue is transferred to the recipient site to check the fit and modified if needed. Suturing techniques vary widely, but stabilization of the graft is the most important principle and can be accomplished using stabilizing structures adjacent to the surgical site. Reducing graft mobility and dead spaces between tissues will improve the graft success and after an average of eight weeks the donor and recipient sites are healed. This technique does give a high discomfort at the palate site reported by most patients regardless of which kind of cover is used over the donor site and does not provide a high esthetic result due to the color mismatch.
Connective Tissue Grafts (CTG)
Following the development and use of FGG, Langer and Calagna in 1980 described the subepithelial connective tissue graft for root coverage and ridge augmentation as the second major type of free soft tissue autograft (Langer and Calagna 1980). The esthetics advantages, healing period, and superior color match of CTG versus FGG make CTG the most widely used soft tissue autograft technique used in periodontal plastic surgery (Langer and Calagna 1982). A connective tissue graft used under a pedicle flap yields to a mean root coverage of 89.3% around natural teeth (Langer and Langer 1993). When the palatal masticatory mucosa is used as autogenous donor material for a connective tissue graft, it is important to control the thickness of the graft harvested. Harvesting a thick graft aids in vascularity and ease of manipulation of the donor tissue but delays the healing period, while use of a thin graft decreases the healing time but often results in graft shrinkage or early necrosis (Mörmann et al. 1981; Sullivan and Atkins 1968). Histologic analysis of the mucosa by Yu et al. showed that the thickness of the lamina propria decreased toward the posterior palatal area and mid‐palatal suture, while that of the submucosa increased (Yu et al. 2014). Yu’s results suggest that the most appropriate donor site for it is the region 3 mm below the cementoenamel junction (CEJ) between the distal surface of the canine and the midline surface of the first molar. When harvesting from this area also keep in mind the anatomical landmarks of the palate. The greater and lesser palatine vessels and nerves lie in a bony groove, the greater palatine groove, which traverses the palate anteriorly at the junction of the horizontal and vertical palate. It is important to avoid the nerves and vessels located along this neurovascular line. The location of this line relative to the CEJ varies with palatal vault depth. In shallow palatal vaults the average distance between the neurovascular line and the CEJ is 7 mm, whereas in high vaults the maximum average distance is 17 mm. In an average vault there is about a distance of 12 mm from the neurovascular line to the CEJ (Reiser et al. 1996; Rose 2004
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