10.1 The Dilemma of Whether or Not to Augment the Band of Keratinized Tissue
As defined by the American Academy of Periodontology (AAP), gingiva [1] is a term that designates “the fibrous investing tissue, covered by keratinized epithelium that immediately surrounds a tooth and is contiguous with its periodontal ligament and with the mucosal tissues of the mouth.” Microscopically, the oral epithelium of the gingiva presents four layers with the corneum stratum consisting of squamous keratinocytes that are believed to serve as a “mechanical barrier” against mechani- cal/environmental trauma to the gingival tissues (Fig. 10.1). For instance, in a recent systematic review, Chambrone and Tatakis [2] evaluated the long-term outcomes of untreated buccal gingival recessions through the assessment of potential factors influencing the development and progression of these defects. These authors found that (1) within individuals presenting good oral hygiene standards, approximately 80% of the untreated gingival recessions progressed/worsened (i.e., experienced recession depth increase) during long-term follow-up and (2) the keratinized tissue (KT) band appears as an important component in preventing such detrimental changes in the gingival margin position overtime (i.e., sites lacking KT seemed to be more prone to additional clinical attachment loss) [2].
Regarding to the importance of KT, it has long been suggested that a minimum 2 mm band of KT (with at least 1 mm of attached tissue) appears to be required to preserve the health of periodontal tissues [3]. Furthermore, the dilemma as to the need to augment the band of KT was thoroughly reviewed by the AAP in 2015 dur- ing its most recent Regeneration Workshop. According to the authors of that sys- tematic review [4] and the base of evidence available to October 2013, there are unprecise definitions on the least extent of KT necessary to maintain periodontal stability (i.e., there are no specific dimensions fully acceptable in the literature). On the other hand, clinical data included in this AAP commissioned paper [4] provided conclusions/responses to the five most common clinical scenarios found in daily practice (these are reproduced as reported in the original publication):
1. What circumstances require an increased zone of KT, or is KT important? [4] Conclusions/Response: “Authors have noted the limitation of recent clinical studies, randomized clinical trials (RCTs), and systemic reviews to answer this question. However, clinical observations would suggest that sites with minimal or no gingiva and associated with restorative margins are more prone to gingival recession and inflammation. Thus, gingival augmentation is indicated for sites with minimal or no gingiva that are receiving intracrevicular restorative margins based on clinical observations (SORT [Strength-of-Recommendation Taxonomy criteria] level B [inconsistent or limited-quality patient-oriented evidence])” [4].
2. What is the ideal thickness of an autogenous gingival graft? Is a thick autog- enous gingival graft more effective than a thin autogenous gingival graft? [4] Conclusions/Response: “A palatal graft should be ≥1-mm thick. Thin grafts tend to result in more esthetic outcomes, whereas thick grafts provide more func- tional resistance. Thick grafts tend to follow significant primary contraction, whereas thin grafts are more prone to secondary contraction. The type of biotype may play an important role in maintaining optimal periodontal health, but disagreements exist among clinicians when describing the types of biotypes (SORT level B [inconsistent or limited-quality patient-oriented evidence])” [4].
3. What are the alternatives to autogenous gingival grafting to increase the zone of attached gingiva? [4] Conclusions/Response: “Modified apically positioned flap may be an effec- tive technique in increasing the apico-coronal dimension of the KT and attached gingiva without donor areas or use of commercial products”….“alternative methods and materials (i.e., acellular dermal matrix grafts, extracellular matrix, xenogenic porcine bilayer collagen matrix and living cellular construct) have been shown to provide enough attached KT to correct areas lacking or with mini- mal gingiva (<2 mm) around teeth in short-term and in small–sample size stud- ies. The advantages of these approaches are avoidance of donor areas and unlimited supply. However, long-term follow-up studies and RCTs should be conducted to strengthen this treatment approach (SORT level C [consensus, disease-oriented evidence, usual practice, expert opinion, or case series for stud- ies of diagnosis, treatment, prevention, or screening])” [4].
4. Does orthodontic intervention affect soft tissue health and dimensions? [4] Conclusions/Response: “Historic clinical observations and recommenda- tions can be referenced to answer this question. The direction of the tooth move- ment and the bucco-lingual thickness of the gingiva play important roles in soft tissue alteration during orthodontic treatment. There is a higher probability of recession during tooth movement in areas with <2 mm of gingiva. Gingival aug- mentation can be indicated before the initiation of orthodontic treatment in areas with <2 mm (SORT level C [consensus, disease-oriented evidence, usual prac- tice, expert opinion, or case series for studies of diagnosis, treatment, prevention, or screening])” [4].
5. What is the patient-reported outcome for minimal KT compared with that for an enhanced zone of KT? [4]Conclusions/Response: “Alternative methods and materials appear to result in less patient discomfort after gingival augmentation procedures when com- pared with FGG. They have also shown to result in better color and texture match to surrounding tissue when compared with FGG. However, study investigators need to standardize how they collect the patient-reported outcomes so the obtained results can be compared with other studies (SORT level C [consensus, disease-oriented evidence, usual practice, expert opinion, or case series for stud- ies of diagnosis, treatment, prevention, or screening])” [4].
Furthermore, recent clinical long-term data (18–35 years) by Agudio et al. [5, 6] reported in several practice-based studies comprising of patients with high stan- dards of oral hygiene shed light on the importance of gingival/KT augmentation. In the first study, it was found that teeth with single recession defects and lacking a minimum KT band of 2 mm undergoing gingival augmentation (via free gingival graft-based procedures) may display a phenomenon called “creeping attachment” (i.e., a coronal shift of the gingival margin), leading to noteworthy gingival reces- sion reduction 10–27 years after treatment [5]. In the second publication, the authors confirmed that gingival augmentation might influence the biologic remodeling of periodontal dimensions associated with the aging process, as well as that use of free gingival grafts can produce more beneficial KT band proportions and reduce gingi- val recession depth [6]. The second study also reported that some degree of shrink- age will occur, thus “the corono-apical dimension of the graft should be calculated on the basis of the KT width of adjacent untreated teeth plus an additional 1.00– 1.50 mm considering an estimated tissue contraction during the early healing, and long follow-up period” [6]. As a result, the authors suggested that clinicians prepare grafts with an additional apical dimension of 1.00–1.50 mm of the mucogingival junction of adjacent untreated teeth [6]
Similar to the concepts established for natural teeth, current evidence (even though minimal) clearly indicates the positive gains of increasing the KT band at dental implant sites [7, 8]. Improvements in KT width and thickness at periodontal and peri- implant sites may be essential to create a “mechanical/physical and biological epithe- lial barrier” that will give protection to peri-implant structures in view of cytokine, chemokine, and antimicrobial peptide production (i.e., interleukin-1α, interleukin-1β, interleukin-6, interleukin-8, and tumor necrosis factor-α) in response to toothbrushing trauma and dental biofilm [8, 9]. In general terms, it has been shown that an increase in KT in areas of elastic peri-implant mucosa by gingival augmentation procedures (i.e., free gingival graft and apically positioned flap) may promote the formation of a firm KT band and thus reduce the probability for gingival recession [7, 8].
Consequently, the above reported studies and reviews support the key role of KT dimensions in the maintenance of the gingival margin stability around natural teeth and dental implants. In addition, these aspects rationally indicate that such grafting procedures will promote a “biotype modification” (i.e., KT width and thickness gain) and should be considered when deemed necessary.
10.2 Surgical Procedures Used for Gingival Augmentation Around Natural Teeth and Dental Implants
As stated above, accumulating evidence supports the importance of KT around den- tal implants. Recent systematic reviews have demonstrated that the lack of KT is related to plaque accumulation, gingival recession, and attachment loss, which indi- cates that implants with insufficient KT may be prone to developing peri-implant mucositis and peri-implantitis [10, 11].
The following treatment modalities can be selected to attain a sufficient dimension of KT and vestibular depth: apically positioned flap (vestibuloplasty), free gingival graft (FGG), and use of collagen matrix (CM). Regarding the use of CM, this xenograft was developed to compensate for the disadvantages of free gingival grafts in terms of the reduction of patients’ morbidity and esthetic enhancement. However, there has been limited evidence on the stability of the reestablished tissue long-term [12–15].
10.3 Free Gingival Graft-Based Procedures
Reports on the use of palatal soft tissue graft (harvested from “the region located behind the third molar”) were originally described in 1902 at the American Dental Club of Paris meeting and published in 1904 in Dental Cosmos [16]. Nonetheless, the use of palatal free gingival grafts (FGG) and deepening the vestibular fornix was reported in 1963 [17], with surgical standardization occurring some years later [18].
10.3.1 Indications
The following types of defects or conditions may benefit from FGG-based procedures:
• Treatment of periodontal or peri-implant sites lacking a minimum 2 mm band of attached KT
• Treatment of periodontal or peri-implant sites presenting a “thin periodontal bio- type” (i.e., “delicate and tiny highly scalloped gingival and osseous architecture and few or non-keratinized tissue” [8, 19–21])
• Treatment of periodontal or peri-implant sites associated with toothbrushing or other environmental discomfort (i.e., pain)
10.3.2 Contraindications
The following types of defects or conditions may not benefit from FGG-based procedures:
• Treatment of periodontal or peri-implant sites located in esthetic areas—these sites may be improved by the use of FGG-based procedure, but the final tissue color will be different from adjacent gingiva.
• Treatment of sites presenting attached KT width ≥2 mm.
• Treatment of sites presenting “thick and flat” (i.e., “dense, flat gingival and osse- ous architecture and ample width of KT tissue” [8, 19–21]) or even “thick and scalloped” (i.e., “a clear thick fibrotic gingiva and narrow zone of KT” [8, 19– 21]) periodontal biotypes.
10.3.3 Principles of the Surgical Sequence
As previously reported in a prior Springer publication [8], the general basic principles involving FGG-based procedures are noted below (Figs. 10.2, 10.3, 10.4, and 10.5):
• Local anesthesia.
• A number 15C surgical scalpel blade should be used to perform a horizontal inci- sion in the interdental papillae at the level of the cement enamel junction (for marginal FGG), and an intrasulcular incision is made at the tooth/teeth receiving the graft (i.e., it should encompass the entire operative site). A submarginal approach may be used when the free gingiva is considered “thick” [5, 6].
• Two vertical incisions made at the ends of the horizontal incision and extended to the alveolar mucosa follow, and a thin, partial-thickness flap is dissected up to the apical limits of the vertical incision and afterward completely excised.
• After the recipient site/bed is completely de-epithelized, a FGG is harvested from the palate according to the size required to cover the recipient bed (Fig. 10.4c). However, the graft harvest may be influenced by the palatal vault anatomy. Reiser et al. [22] found that the average distance from the cementoe- namel junction to the neurovascular bundle varies according to the size and shapes of hard palate, from 7 mm for shallow to 17 mm for high (U-shaped) pal- ates. Usually, FGG can be harvested between the distal aspect of the canine and the midpalatal region of the second molar, in order to prevent potential damage and complications associated with severing the greater palatine artery and their major branches, such as hemorrhage.
• The graft should be sutured to the recipient site using 5-0 or 6-0 interrupted/ suspensory nylon/Teflon sutures and without leaving “dead spaces” between the lamina propria and the connective tissue side of the graft and root surface (Figs. 10.4e and 10.5b).
• The sutures may be carefully removed 7–14 days after surgery to avoid injury to the graft (Fig. 10.5c). Patients should be instructed not to perform toothbrushing of the treated area during this period and directed to rinse gently with a mouth- wash containing 0.12% chlorhexidine gluconate twice a day for 2–3 weeks, or until safe and comfortable, toothbrushing can be performed.
• Analgesics, anti-inflammatory drugs, and/or systemic antibiotics may be pre- scribed if necessary.
• Pain and bleeding may occur at the donor site during the early phase of healing due to exposure of the connective tissue layers of the palatal gingival tissue. On the other hand, these adverse effects will not promote alterations in the final anticipated outcomes.
10.4 Vestibuloplasty-Based Procedures
A 25-year longitudinal study conducted by Tallgren revealed a continuing reduction in the height of the maxilla after tooth extraction in complete denture wearers. In the mandible, this reduction was particularly marked in the height of the anterior ridge, being approximately four times as great as that of the anterior maxilla [23]. The lack of an adequate residual alveolar ridge and basal seat severely compromises the suc- cess of prosthodontic treatment. It has been suggested that expansion of the denture- bearing area by means of a vestibuloplasty would reduce denture load per square unit of supporting bone and thus reduce the bone resorption caused by transfer of occlusal force [24]. Other authors also reported important ridge alterations after tooth extraction and related these findings to the loss of periodontal ligament where the alveolar bone is unable to reform leading to resorption [25–27]. This phenome- non shows variation in rate with rapid bone loss noted at the first 6 months after extraction and the following 2 years [28].
The oral rehabilitation of patients after tooth loss has made much progress, and many different methods have been described for regenerating or replacing bone for secondary implant placement. Vestibuloplasty, ridge augmentation, and different types of implants were used to overcome the challenges of a flat alveolar ridge [29], but until now, little substantial progress has been made in soft tissue management.
Vestibuloplasty techniques can be generally categorized as mucosal advance- ment, secondary epithelization, and grafting vestibuloplasty. Physical status and age of patient are prime factors for the selection of the surgical technique to be utilized [30]. Success of the submucosal vestibuloplasty depends on availability of adequate bone and free mobile mucosa so that deepening can be achieved without tension [31, 32]. If available mucosa is not adequate or of poor quality, then submucosal vestibuloplasty is not indicated. Instead, secondary epithelization technique is pre- ferred [31, 33].
There are two basic techniques of vestibuloplasty by secondary epithelization with several variations. In one technique (Kazanjian) a mucosal flap is raised to the lip and transferred to align with the osseous side of the deepened sulcus [33]. In the other (Clark) a flap of alveolar mucosa is raised and transferred to align with the soft tissue side of the sulcus [31]. Variations in these two basic techniques relate to the periosteum. The aim is therefore to create adequate vestibular depth and limit the traction of fiber and muscle attachments [29, 34].
10.4.1 Indications
The following types of defects or conditions may benefit from vestibuloplasty- based procedures:
• Treatment of advanced alveolar resorption
• Treatment of sites with a narrow band of remaining keratinized mucosa
• Treatment of sites with a shallow vestibule
• Treatment of areas presenting prominent muscle attachments, particularly the vestibular mentalis, the lingual mylohyoideus, and the genioglossus
• Treatment of sites requiring jaw optimization for prosthesis integration
• Treatment of sites lacking sufficient height of the residual alveolar ridge
10.4.2 Contraindication
The following types of defects or conditions may not benefit from vestibuloplasty- based procedures:
• Treatment of small, localized areas
• Treatment of non-edentulous/dentate areas
• Treatment of sites requiring alveolar ridge height gain
• Treatment of areas where morbidity control might be required [22, 35, 36]
10.5 Basic Principles of the Surgical Sequence: Kazanjian Vestibuloplasty
The general basic principles involving the use of Kazanjian vestibuloplasty are reproduced below:
• Local anesthesia.
• An incision is made through the mucosa from one premolar region via the inner lower lip to the contralateral premolar region.
• The mucosa is reflected to the highest part of the alveolar crest, which is fol- lowed by epiperiosteal dissection of the mental muscles into the vestibular depth.
• The pedicle flap is sutured to the periosteum at the depth of the vestibulum. At this point a rubber catheter stent can be placed into the deepened sulcus and fixed through the lip to the outer surface with percutaneous sutures. The catheter helps to hold the flap in its new position and to maintain the depth of vestibule during the initial stages of healing.
• The catheter is removed after 7 days and the wound in the vestibulum and inner lip is left to heal secondarily. The patient is directed to rinse gently with a mouth- wash containing 0.12% chlorhexidine gluconate twice a day for 2–3 weeks, or until safe and comfortable, cleansing can be performed. This method can be used with or without simultaneous insertion of dental implants.
• Analgesics, anti-inflammatory drugs, and/or systemic antibiotics may be pre- scribed if required.
10.6 Basic Principles of the Surgical Sequence: Clark Vestibuloplasty
This can be considered as the reverse of Kazanjian’s technique using the following principles:
(a) Raw surfaces on connective tissue contract, whereas the same surfaces undergo minimal contraction when covered with epithelium.
(b) Raw surface on the overlying bone cannot contract.
(c) Epithelial flaps must be undermined sufficiently to permit repositioning and fixation without tension.
(d) Soft tissues undergoing plastic revision have a tendency to return to their former position, so overcorrection and firm fixation are necessary.
The general basic principles involving the use of Clark vestibuloplasty are repro- duced below [31] and highlighted in Fig. 10.6:
• Local anesthesia.
• An incision is made on the alveolar ridge, and a supraperiosteal dissection is performed to the desired depth (the mucosa of the lip is undermined to the ver- milion border) (Fig. 10.6c).
• Nonabsorbable mattress sutures are placed in the free margin of the mucosal flap (Fig. 10.6g–i) and are carried through the skin and tied over a cotton roll.
• The soft tissue side of the sulcus is covered with mucosa, whereas, on the osseous side, the raw periosteal surface is left to granulate and epithelialize. Additionally, a free gingival graft may be associated with the procedure (Fig. 10.6j, k).
• The sutures may be removed 7–14 days after surgery. The patient is directed to rinse gently with a mouthwash containing 0.12% chlorhexidine gluconate twice a day for 2–3 weeks, or until safe and comfortable, cleansing can be performed. Analgesics, anti-inflammatory drugs, and/or systemic antibiotics may be pre- scribed if required.
10.7 Additional Vestibuloplasty Procedures
A third option has gained an important role in preprosthetic surgery, the standard- ized Edlan vestibuloplasty. In this technique, an incision is made through the mucosa from one premolar region to the inner lower lip and to the contralateral premolar region. The mucosa is reflected to the highest point of the alveolar ridge; the perios- teum is incised at the alveolar ridge and prepared under direct vision of the mental nerve down to the required vestibular depth. The periosteum is sutured to the muco- sal crest of the inner lip. The pedicled mucosal flap is sutured to the periosteum at the vestibular depth [37]. This method is mainly used in combination with the inser- tion of acrylic stents, graft materials, or implants.
One should note that after vestibuloplasty, a short period of rapid bone resorption can occur. Subperiosteal preparation in Edlan-plasty cases was followed by a consid- erable rate of bone resorption up to 2 years postoperatively [34, 35]. In a prospective study of Edlan- and Kazanjian-plasty, a high amount of bone resorption was not observed. The authors suggest that this procedure when combined with implant placement might have prevented progressive bone resorption. Nevertheless, the Edlan-plasty was followed by a small amount of bone resorption, which was even less so in the Kazanjian-plasty. On the other hand, the Kazanjian-plasty was followed by an increased loss of attached mucosa. However, 10% of implants of the study showed a total loss of attached mucosa, necessitating a repeat vestibuloplasty [34].
10.8 Clinical Highlights on the Use of Gingival Augmentation Procedures at Periodontal and Peri-implant Sites
Although the periodontium and peri-implant supporting structures share similar histo- logic and clinical features, there are several fundamental differences between the anchorage and attachment of teeth and implants. A key difference is that there is no periodontal ligament or cementum around dental implants, with the alveolar bone in direct contact with the implant surface. As is the case with teeth, the transmucosal component of implants needs to provide a physical and physiological barrier between the external oral environment and the underlying tissues. The implant-mucosa interface also includes a sulcus resembling that associated with teeth, as well as an attachment apparatus. Indeed, the architecture of the supra-alveolar transmucosal components, consisting of a sulcus, junctional epithelium, and connective tissue attachment, is simi- lar around implants and teeth. Although both the transmucosal component of implants and the transgingival component of teeth have a sulcus (in health) or pocket (in disease) and a connective tissue attachment, important differences exist, which have clinical implications for the maintenance of peri-implant mucosal health, as well as for the diagnosis and management of peri-implant disease [38].
Soft tissue around teeth is subdivided into gingiva and mobile mucosa. The attached keratinized gingiva is composed of a keratinized epithelium, dense connective tissue, and periosteum which plays an essential role in the protection of periodontal struc- tures. The attached gingiva provides increased resistance of the periodontium to exter- nal injury, contributes to the stabilization of the gingival margin position, and aids in the dissipation of physiological forces that are exerted by the muscular fibers of the alveolar mucosa onto the gingival tissues [39]. The width of keratinized tissue around natural teeth does not seem to be correlated with the maintenance of periodontal health. According to several reports, a 2.0 mm of attached gingiva is sufficient for the maintenance of periodontal health [3, 40] even in cases in which subgingival restora- tion margins are placed [41–43]. Apically repositioned flap as described by Friedman [44] has been successfully used to increase the width of attached gingival around natu- ral teeth. Moreover, this procedure can be modified and used around implants in cases where a thick gingival biotype is present (when there is no need of improving peri- implant mucosa thickness) (Fig. 10.7), with the advantages of promoting low morbid- ity to the patient (as it precludes the need of second surgical site) and better esthetic color blending [45]. The characteristics of the transmucosal passage-junctional epi- thelium and connective tissue attachment of the implant are established when healing of the ridge mucosa following implant surgery is in progress. In this context it should be realized that an essential role of epithelium in wound healing is to cover any con- nective tissue surface that is severed, such as during surgery. Thus, the epithelial cells at the periphery of the mucosal wound, produced at implant installation, are geneti- cally programmed to divide and migrate across the injured part until epithelial conti- nuity is restored. The epithelial cells also have the ability to adhere to the implant surface, synthesize basal lamina as well as hemidesmosomes, and establish an epithe- lial barrier that has features in common with a junctional epithelium. Equally impor- tant is the capacity of a normal, uninflamed connective tissue to form an attachment to the titanium surface below the epithelium and in a more superficial location to support the junctional epithelium. The maintenance of normal connective tissue is of critical importance for normal turnover of the epithelial and connective tissue attachments to the titanium implant
10.9 Concluding Remarks on Gingival Augmentation (KT Increase) and Vestibuloplasty: Implications for Practice and Clinical Decision-Making
Gingival augmentation procedures have long been used in clinical practice and appear as an important factor for maintaining periodontal health. The use of FGG can safely increase the keratinized tissue width and modify the periodontal biotype (Fig. 10.8). Although the results of FGG may be improved over time by the coronal displacement of the gingival margin (creeping attachment), the amount of this “beneficial” out- comes may not be anticipated [5, 6]. On the other hand, some degree of soft tissue shrinkage may be anticipated during the initial phase of healing, as well as during long-term follow-up. The available evidence suggests that this KT contraction seems more evident at implant sites (up to 50%) in the short-term (up to 3 months) [7]. For natural teeth, nearly 82% of KT gain achieved at short-term (i.e., 6 months) may be maintained long-term (i.e., up to 25 years). With respect to implant sites, early animal [47] and human studies [48, 49] reported no correlation between implant success and the presence of keratinized mucosa (KM). In contrast, recent systematic reviews con- cluded that an inadequate width of peri-implant KM is associated with more plaque accumulation, signs of inflammation, soft tissue recession, and attachment loss [2, 3, 18, 50]. Furthermore, the peri-implant mucosa appears to possess less potential for an immune response against external irritants (plaque accumulation)
As defined by the American Academy of Periodontology (AAP), gingiva [1] is a term that designates “the fibrous investing tissue, covered by keratinized epithelium that immediately surrounds a tooth and is contiguous with its periodontal ligament and with the mucosal tissues of the mouth.” Microscopically, the oral epithelium of the gingiva presents four layers with the corneum stratum consisting of squamous keratinocytes that are believed to serve as a “mechanical barrier” against mechani- cal/environmental trauma to the gingival tissues (Fig. 10.1). For instance, in a recent systematic review, Chambrone and Tatakis [2] evaluated the long-term outcomes of untreated buccal gingival recessions through the assessment of potential factors influencing the development and progression of these defects. These authors found that (1) within individuals presenting good oral hygiene standards, approximately 80% of the untreated gingival recessions progressed/worsened (i.e., experienced recession depth increase) during long-term follow-up and (2) the keratinized tissue (KT) band appears as an important component in preventing such detrimental changes in the gingival margin position overtime (i.e., sites lacking KT seemed to be more prone to additional clinical attachment loss) [2].
Regarding to the importance of KT, it has long been suggested that a minimum 2 mm band of KT (with at least 1 mm of attached tissue) appears to be required to preserve the health of periodontal tissues [3]. Furthermore, the dilemma as to the need to augment the band of KT was thoroughly reviewed by the AAP in 2015 dur- ing its most recent Regeneration Workshop. According to the authors of that sys- tematic review [4] and the base of evidence available to October 2013, there are unprecise definitions on the least extent of KT necessary to maintain periodontal stability (i.e., there are no specific dimensions fully acceptable in the literature). On the other hand, clinical data included in this AAP commissioned paper [4] provided conclusions/responses to the five most common clinical scenarios found in daily practice (these are reproduced as reported in the original publication):
1. What circumstances require an increased zone of KT, or is KT important? [4] Conclusions/Response: “Authors have noted the limitation of recent clinical studies, randomized clinical trials (RCTs), and systemic reviews to answer this question. However, clinical observations would suggest that sites with minimal or no gingiva and associated with restorative margins are more prone to gingival recession and inflammation. Thus, gingival augmentation is indicated for sites with minimal or no gingiva that are receiving intracrevicular restorative margins based on clinical observations (SORT [Strength-of-Recommendation Taxonomy criteria] level B [inconsistent or limited-quality patient-oriented evidence])” [4].
2. What is the ideal thickness of an autogenous gingival graft? Is a thick autog- enous gingival graft more effective than a thin autogenous gingival graft? [4] Conclusions/Response: “A palatal graft should be ≥1-mm thick. Thin grafts tend to result in more esthetic outcomes, whereas thick grafts provide more func- tional resistance. Thick grafts tend to follow significant primary contraction, whereas thin grafts are more prone to secondary contraction. The type of biotype may play an important role in maintaining optimal periodontal health, but disagreements exist among clinicians when describing the types of biotypes (SORT level B [inconsistent or limited-quality patient-oriented evidence])” [4].
3. What are the alternatives to autogenous gingival grafting to increase the zone of attached gingiva? [4] Conclusions/Response: “Modified apically positioned flap may be an effec- tive technique in increasing the apico-coronal dimension of the KT and attached gingiva without donor areas or use of commercial products”….“alternative methods and materials (i.e., acellular dermal matrix grafts, extracellular matrix, xenogenic porcine bilayer collagen matrix and living cellular construct) have been shown to provide enough attached KT to correct areas lacking or with mini- mal gingiva (<2 mm) around teeth in short-term and in small–sample size stud- ies. The advantages of these approaches are avoidance of donor areas and unlimited supply. However, long-term follow-up studies and RCTs should be conducted to strengthen this treatment approach (SORT level C [consensus, disease-oriented evidence, usual practice, expert opinion, or case series for stud- ies of diagnosis, treatment, prevention, or screening])” [4].
4. Does orthodontic intervention affect soft tissue health and dimensions? [4] Conclusions/Response: “Historic clinical observations and recommenda- tions can be referenced to answer this question. The direction of the tooth move- ment and the bucco-lingual thickness of the gingiva play important roles in soft tissue alteration during orthodontic treatment. There is a higher probability of recession during tooth movement in areas with <2 mm of gingiva. Gingival aug- mentation can be indicated before the initiation of orthodontic treatment in areas with <2 mm (SORT level C [consensus, disease-oriented evidence, usual prac- tice, expert opinion, or case series for studies of diagnosis, treatment, prevention, or screening])” [4].
5. What is the patient-reported outcome for minimal KT compared with that for an enhanced zone of KT? [4]Conclusions/Response: “Alternative methods and materials appear to result in less patient discomfort after gingival augmentation procedures when com- pared with FGG. They have also shown to result in better color and texture match to surrounding tissue when compared with FGG. However, study investigators need to standardize how they collect the patient-reported outcomes so the obtained results can be compared with other studies (SORT level C [consensus, disease-oriented evidence, usual practice, expert opinion, or case series for stud- ies of diagnosis, treatment, prevention, or screening])” [4].
Furthermore, recent clinical long-term data (18–35 years) by Agudio et al. [5, 6] reported in several practice-based studies comprising of patients with high stan- dards of oral hygiene shed light on the importance of gingival/KT augmentation. In the first study, it was found that teeth with single recession defects and lacking a minimum KT band of 2 mm undergoing gingival augmentation (via free gingival graft-based procedures) may display a phenomenon called “creeping attachment” (i.e., a coronal shift of the gingival margin), leading to noteworthy gingival reces- sion reduction 10–27 years after treatment [5]. In the second publication, the authors confirmed that gingival augmentation might influence the biologic remodeling of periodontal dimensions associated with the aging process, as well as that use of free gingival grafts can produce more beneficial KT band proportions and reduce gingi- val recession depth [6]. The second study also reported that some degree of shrink- age will occur, thus “the corono-apical dimension of the graft should be calculated on the basis of the KT width of adjacent untreated teeth plus an additional 1.00– 1.50 mm considering an estimated tissue contraction during the early healing, and long follow-up period” [6]. As a result, the authors suggested that clinicians prepare grafts with an additional apical dimension of 1.00–1.50 mm of the mucogingival junction of adjacent untreated teeth [6]
Similar to the concepts established for natural teeth, current evidence (even though minimal) clearly indicates the positive gains of increasing the KT band at dental implant sites [7, 8]. Improvements in KT width and thickness at periodontal and peri- implant sites may be essential to create a “mechanical/physical and biological epithe- lial barrier” that will give protection to peri-implant structures in view of cytokine, chemokine, and antimicrobial peptide production (i.e., interleukin-1α, interleukin-1β, interleukin-6, interleukin-8, and tumor necrosis factor-α) in response to toothbrushing trauma and dental biofilm [8, 9]. In general terms, it has been shown that an increase in KT in areas of elastic peri-implant mucosa by gingival augmentation procedures (i.e., free gingival graft and apically positioned flap) may promote the formation of a firm KT band and thus reduce the probability for gingival recession [7, 8].
Consequently, the above reported studies and reviews support the key role of KT dimensions in the maintenance of the gingival margin stability around natural teeth and dental implants. In addition, these aspects rationally indicate that such grafting procedures will promote a “biotype modification” (i.e., KT width and thickness gain) and should be considered when deemed necessary.
10.2 Surgical Procedures Used for Gingival Augmentation Around Natural Teeth and Dental Implants
As stated above, accumulating evidence supports the importance of KT around den- tal implants. Recent systematic reviews have demonstrated that the lack of KT is related to plaque accumulation, gingival recession, and attachment loss, which indi- cates that implants with insufficient KT may be prone to developing peri-implant mucositis and peri-implantitis [10, 11].
The following treatment modalities can be selected to attain a sufficient dimension of KT and vestibular depth: apically positioned flap (vestibuloplasty), free gingival graft (FGG), and use of collagen matrix (CM). Regarding the use of CM, this xenograft was developed to compensate for the disadvantages of free gingival grafts in terms of the reduction of patients’ morbidity and esthetic enhancement. However, there has been limited evidence on the stability of the reestablished tissue long-term [12–15].
10.3 Free Gingival Graft-Based Procedures
Reports on the use of palatal soft tissue graft (harvested from “the region located behind the third molar”) were originally described in 1902 at the American Dental Club of Paris meeting and published in 1904 in Dental Cosmos [16]. Nonetheless, the use of palatal free gingival grafts (FGG) and deepening the vestibular fornix was reported in 1963 [17], with surgical standardization occurring some years later [18].
10.3.1 Indications
The following types of defects or conditions may benefit from FGG-based procedures:
• Treatment of periodontal or peri-implant sites lacking a minimum 2 mm band of attached KT
• Treatment of periodontal or peri-implant sites presenting a “thin periodontal bio- type” (i.e., “delicate and tiny highly scalloped gingival and osseous architecture and few or non-keratinized tissue” [8, 19–21])
• Treatment of periodontal or peri-implant sites associated with toothbrushing or other environmental discomfort (i.e., pain)
10.3.2 Contraindications
The following types of defects or conditions may not benefit from FGG-based procedures:
• Treatment of periodontal or peri-implant sites located in esthetic areas—these sites may be improved by the use of FGG-based procedure, but the final tissue color will be different from adjacent gingiva.
• Treatment of sites presenting attached KT width ≥2 mm.
• Treatment of sites presenting “thick and flat” (i.e., “dense, flat gingival and osse- ous architecture and ample width of KT tissue” [8, 19–21]) or even “thick and scalloped” (i.e., “a clear thick fibrotic gingiva and narrow zone of KT” [8, 19– 21]) periodontal biotypes.
10.3.3 Principles of the Surgical Sequence
As previously reported in a prior Springer publication [8], the general basic principles involving FGG-based procedures are noted below (Figs. 10.2, 10.3, 10.4, and 10.5):
• Local anesthesia.
• A number 15C surgical scalpel blade should be used to perform a horizontal inci- sion in the interdental papillae at the level of the cement enamel junction (for marginal FGG), and an intrasulcular incision is made at the tooth/teeth receiving the graft (i.e., it should encompass the entire operative site). A submarginal approach may be used when the free gingiva is considered “thick” [5, 6].
• Two vertical incisions made at the ends of the horizontal incision and extended to the alveolar mucosa follow, and a thin, partial-thickness flap is dissected up to the apical limits of the vertical incision and afterward completely excised.
• After the recipient site/bed is completely de-epithelized, a FGG is harvested from the palate according to the size required to cover the recipient bed (Fig. 10.4c). However, the graft harvest may be influenced by the palatal vault anatomy. Reiser et al. [22] found that the average distance from the cementoe- namel junction to the neurovascular bundle varies according to the size and shapes of hard palate, from 7 mm for shallow to 17 mm for high (U-shaped) pal- ates. Usually, FGG can be harvested between the distal aspect of the canine and the midpalatal region of the second molar, in order to prevent potential damage and complications associated with severing the greater palatine artery and their major branches, such as hemorrhage.
• The graft should be sutured to the recipient site using 5-0 or 6-0 interrupted/ suspensory nylon/Teflon sutures and without leaving “dead spaces” between the lamina propria and the connective tissue side of the graft and root surface (Figs. 10.4e and 10.5b).
• The sutures may be carefully removed 7–14 days after surgery to avoid injury to the graft (Fig. 10.5c). Patients should be instructed not to perform toothbrushing of the treated area during this period and directed to rinse gently with a mouth- wash containing 0.12% chlorhexidine gluconate twice a day for 2–3 weeks, or until safe and comfortable, toothbrushing can be performed.
• Analgesics, anti-inflammatory drugs, and/or systemic antibiotics may be pre- scribed if necessary.
• Pain and bleeding may occur at the donor site during the early phase of healing due to exposure of the connective tissue layers of the palatal gingival tissue. On the other hand, these adverse effects will not promote alterations in the final anticipated outcomes.
10.4 Vestibuloplasty-Based Procedures
A 25-year longitudinal study conducted by Tallgren revealed a continuing reduction in the height of the maxilla after tooth extraction in complete denture wearers. In the mandible, this reduction was particularly marked in the height of the anterior ridge, being approximately four times as great as that of the anterior maxilla [23]. The lack of an adequate residual alveolar ridge and basal seat severely compromises the suc- cess of prosthodontic treatment. It has been suggested that expansion of the denture- bearing area by means of a vestibuloplasty would reduce denture load per square unit of supporting bone and thus reduce the bone resorption caused by transfer of occlusal force [24]. Other authors also reported important ridge alterations after tooth extraction and related these findings to the loss of periodontal ligament where the alveolar bone is unable to reform leading to resorption [25–27]. This phenome- non shows variation in rate with rapid bone loss noted at the first 6 months after extraction and the following 2 years [28].
The oral rehabilitation of patients after tooth loss has made much progress, and many different methods have been described for regenerating or replacing bone for secondary implant placement. Vestibuloplasty, ridge augmentation, and different types of implants were used to overcome the challenges of a flat alveolar ridge [29], but until now, little substantial progress has been made in soft tissue management.
Vestibuloplasty techniques can be generally categorized as mucosal advance- ment, secondary epithelization, and grafting vestibuloplasty. Physical status and age of patient are prime factors for the selection of the surgical technique to be utilized [30]. Success of the submucosal vestibuloplasty depends on availability of adequate bone and free mobile mucosa so that deepening can be achieved without tension [31, 32]. If available mucosa is not adequate or of poor quality, then submucosal vestibuloplasty is not indicated. Instead, secondary epithelization technique is pre- ferred [31, 33].
There are two basic techniques of vestibuloplasty by secondary epithelization with several variations. In one technique (Kazanjian) a mucosal flap is raised to the lip and transferred to align with the osseous side of the deepened sulcus [33]. In the other (Clark) a flap of alveolar mucosa is raised and transferred to align with the soft tissue side of the sulcus [31]. Variations in these two basic techniques relate to the periosteum. The aim is therefore to create adequate vestibular depth and limit the traction of fiber and muscle attachments [29, 34].
10.4.1 Indications
The following types of defects or conditions may benefit from vestibuloplasty- based procedures:
• Treatment of advanced alveolar resorption
• Treatment of sites with a narrow band of remaining keratinized mucosa
• Treatment of sites with a shallow vestibule
• Treatment of areas presenting prominent muscle attachments, particularly the vestibular mentalis, the lingual mylohyoideus, and the genioglossus
• Treatment of sites requiring jaw optimization for prosthesis integration
• Treatment of sites lacking sufficient height of the residual alveolar ridge
10.4.2 Contraindication
The following types of defects or conditions may not benefit from vestibuloplasty- based procedures:
• Treatment of small, localized areas
• Treatment of non-edentulous/dentate areas
• Treatment of sites requiring alveolar ridge height gain
• Treatment of areas where morbidity control might be required [22, 35, 36]
10.5 Basic Principles of the Surgical Sequence: Kazanjian Vestibuloplasty
The general basic principles involving the use of Kazanjian vestibuloplasty are reproduced below:
• Local anesthesia.
• An incision is made through the mucosa from one premolar region via the inner lower lip to the contralateral premolar region.
• The mucosa is reflected to the highest part of the alveolar crest, which is fol- lowed by epiperiosteal dissection of the mental muscles into the vestibular depth.
• The pedicle flap is sutured to the periosteum at the depth of the vestibulum. At this point a rubber catheter stent can be placed into the deepened sulcus and fixed through the lip to the outer surface with percutaneous sutures. The catheter helps to hold the flap in its new position and to maintain the depth of vestibule during the initial stages of healing.
• The catheter is removed after 7 days and the wound in the vestibulum and inner lip is left to heal secondarily. The patient is directed to rinse gently with a mouth- wash containing 0.12% chlorhexidine gluconate twice a day for 2–3 weeks, or until safe and comfortable, cleansing can be performed. This method can be used with or without simultaneous insertion of dental implants.
• Analgesics, anti-inflammatory drugs, and/or systemic antibiotics may be pre- scribed if required.
10.6 Basic Principles of the Surgical Sequence: Clark Vestibuloplasty
This can be considered as the reverse of Kazanjian’s technique using the following principles:
(a) Raw surfaces on connective tissue contract, whereas the same surfaces undergo minimal contraction when covered with epithelium.
(b) Raw surface on the overlying bone cannot contract.
(c) Epithelial flaps must be undermined sufficiently to permit repositioning and fixation without tension.
(d) Soft tissues undergoing plastic revision have a tendency to return to their former position, so overcorrection and firm fixation are necessary.
The general basic principles involving the use of Clark vestibuloplasty are repro- duced below [31] and highlighted in Fig. 10.6:
• Local anesthesia.
• An incision is made on the alveolar ridge, and a supraperiosteal dissection is performed to the desired depth (the mucosa of the lip is undermined to the ver- milion border) (Fig. 10.6c).
• Nonabsorbable mattress sutures are placed in the free margin of the mucosal flap (Fig. 10.6g–i) and are carried through the skin and tied over a cotton roll.
• The soft tissue side of the sulcus is covered with mucosa, whereas, on the osseous side, the raw periosteal surface is left to granulate and epithelialize. Additionally, a free gingival graft may be associated with the procedure (Fig. 10.6j, k).
• The sutures may be removed 7–14 days after surgery. The patient is directed to rinse gently with a mouthwash containing 0.12% chlorhexidine gluconate twice a day for 2–3 weeks, or until safe and comfortable, cleansing can be performed. Analgesics, anti-inflammatory drugs, and/or systemic antibiotics may be pre- scribed if required.
10.7 Additional Vestibuloplasty Procedures
A third option has gained an important role in preprosthetic surgery, the standard- ized Edlan vestibuloplasty. In this technique, an incision is made through the mucosa from one premolar region to the inner lower lip and to the contralateral premolar region. The mucosa is reflected to the highest point of the alveolar ridge; the perios- teum is incised at the alveolar ridge and prepared under direct vision of the mental nerve down to the required vestibular depth. The periosteum is sutured to the muco- sal crest of the inner lip. The pedicled mucosal flap is sutured to the periosteum at the vestibular depth [37]. This method is mainly used in combination with the inser- tion of acrylic stents, graft materials, or implants.
One should note that after vestibuloplasty, a short period of rapid bone resorption can occur. Subperiosteal preparation in Edlan-plasty cases was followed by a consid- erable rate of bone resorption up to 2 years postoperatively [34, 35]. In a prospective study of Edlan- and Kazanjian-plasty, a high amount of bone resorption was not observed. The authors suggest that this procedure when combined with implant placement might have prevented progressive bone resorption. Nevertheless, the Edlan-plasty was followed by a small amount of bone resorption, which was even less so in the Kazanjian-plasty. On the other hand, the Kazanjian-plasty was followed by an increased loss of attached mucosa. However, 10% of implants of the study showed a total loss of attached mucosa, necessitating a repeat vestibuloplasty [34].
10.8 Clinical Highlights on the Use of Gingival Augmentation Procedures at Periodontal and Peri-implant Sites
Although the periodontium and peri-implant supporting structures share similar histo- logic and clinical features, there are several fundamental differences between the anchorage and attachment of teeth and implants. A key difference is that there is no periodontal ligament or cementum around dental implants, with the alveolar bone in direct contact with the implant surface. As is the case with teeth, the transmucosal component of implants needs to provide a physical and physiological barrier between the external oral environment and the underlying tissues. The implant-mucosa interface also includes a sulcus resembling that associated with teeth, as well as an attachment apparatus. Indeed, the architecture of the supra-alveolar transmucosal components, consisting of a sulcus, junctional epithelium, and connective tissue attachment, is simi- lar around implants and teeth. Although both the transmucosal component of implants and the transgingival component of teeth have a sulcus (in health) or pocket (in disease) and a connective tissue attachment, important differences exist, which have clinical implications for the maintenance of peri-implant mucosal health, as well as for the diagnosis and management of peri-implant disease [38].
Soft tissue around teeth is subdivided into gingiva and mobile mucosa. The attached keratinized gingiva is composed of a keratinized epithelium, dense connective tissue, and periosteum which plays an essential role in the protection of periodontal struc- tures. The attached gingiva provides increased resistance of the periodontium to exter- nal injury, contributes to the stabilization of the gingival margin position, and aids in the dissipation of physiological forces that are exerted by the muscular fibers of the alveolar mucosa onto the gingival tissues [39]. The width of keratinized tissue around natural teeth does not seem to be correlated with the maintenance of periodontal health. According to several reports, a 2.0 mm of attached gingiva is sufficient for the maintenance of periodontal health [3, 40] even in cases in which subgingival restora- tion margins are placed [41–43]. Apically repositioned flap as described by Friedman [44] has been successfully used to increase the width of attached gingival around natu- ral teeth. Moreover, this procedure can be modified and used around implants in cases where a thick gingival biotype is present (when there is no need of improving peri- implant mucosa thickness) (Fig. 10.7), with the advantages of promoting low morbid- ity to the patient (as it precludes the need of second surgical site) and better esthetic color blending [45]. The characteristics of the transmucosal passage-junctional epi- thelium and connective tissue attachment of the implant are established when healing of the ridge mucosa following implant surgery is in progress. In this context it should be realized that an essential role of epithelium in wound healing is to cover any con- nective tissue surface that is severed, such as during surgery. Thus, the epithelial cells at the periphery of the mucosal wound, produced at implant installation, are geneti- cally programmed to divide and migrate across the injured part until epithelial conti- nuity is restored. The epithelial cells also have the ability to adhere to the implant surface, synthesize basal lamina as well as hemidesmosomes, and establish an epithe- lial barrier that has features in common with a junctional epithelium. Equally impor- tant is the capacity of a normal, uninflamed connective tissue to form an attachment to the titanium surface below the epithelium and in a more superficial location to support the junctional epithelium. The maintenance of normal connective tissue is of critical importance for normal turnover of the epithelial and connective tissue attachments to the titanium implant
10.9 Concluding Remarks on Gingival Augmentation (KT Increase) and Vestibuloplasty: Implications for Practice and Clinical Decision-Making
Gingival augmentation procedures have long been used in clinical practice and appear as an important factor for maintaining periodontal health. The use of FGG can safely increase the keratinized tissue width and modify the periodontal biotype (Fig. 10.8). Although the results of FGG may be improved over time by the coronal displacement of the gingival margin (creeping attachment), the amount of this “beneficial” out- comes may not be anticipated [5, 6]. On the other hand, some degree of soft tissue shrinkage may be anticipated during the initial phase of healing, as well as during long-term follow-up. The available evidence suggests that this KT contraction seems more evident at implant sites (up to 50%) in the short-term (up to 3 months) [7]. For natural teeth, nearly 82% of KT gain achieved at short-term (i.e., 6 months) may be maintained long-term (i.e., up to 25 years). With respect to implant sites, early animal [47] and human studies [48, 49] reported no correlation between implant success and the presence of keratinized mucosa (KM). In contrast, recent systematic reviews con- cluded that an inadequate width of peri-implant KM is associated with more plaque accumulation, signs of inflammation, soft tissue recession, and attachment loss [2, 3, 18, 50]. Furthermore, the peri-implant mucosa appears to possess less potential for an immune response against external irritants (plaque accumulation)
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