Peri‐implant Tissue Stability Part 3

5.4 Classification of Implant‐related Gingival Recession

Replacement of the natural dentition in the esthetic zone often requires a prosthesis of optimal form and shade, which, in turn, necessitates the establishment of natural and harmonious gingival architecture surrounding the prosthesis. Moreover, Chen and Buser (2009) concluded that advanced mid‐facial recession is common following immediate implant placement (see Figure 5.28a–c).There are many clinical pictures of implant related gingival recession, therefore it would be invaluable to present a classification system that helps communication between the dental team as well as presenting a proposed clinical intervention for each classification.

Accordingly, the author introduced a new basic clas- sification system for implant‐related gingival recession. Class I (minor recession) presents less than 1 mm of recession from the mid‐facial aspect with the height of interdental papillae intact. Class II (moderate reces- sion) may be categorized as: class II is an implant‐ related gingival recession that ranges between 1 and 2 mm from the mid‐facial aspect, with both proximal papillae heights intact; it has two subdivision class II division 1, where the labial plate of bone is resorbed while the palatal plate of bone is intact, and class II divi- sion 2, where both plates of bone (labial and palatal) are resorbed, confirmed by the CBCT scan. Class III (severe recession) presents more than 2 mm recession from the mid‐facial aspect, where one or both peri‐implant papillae have lost height (see Figure 5.29a–c and Table 5.1) (Elaskary et al. 2016).

5.5 Recession Scoring Template

Several attempts have been made to measure apical tissue migration around natural teeth. Cabello, Rioboo and Fabrega (2012) observed the soft tissue level changes in relation to immediate implant placement using a rigid acrylic stent overlapping the incisal edges of the adjacent teeth with three reference dimples placed in the stent corresponding to the mesial and distal interdental papilla and the level of the gin- gival zenith. An electronic caliber was then used to measure the distance approximated to a tenth of a millimeter.
On the study cast, a rigid stent is prepared with light‐ cured resin, covering the incisal edges of at least one adja- cent tooth on each side of the target tooth. The stent is >2 mm thick so can be modified to allow seating over the final restoration. Distances are found from the stent to the distal papilla (DP), the mesial papilla (MP), and the gingival zenith (Z). Distances are measured using a precision digital caliper. Three dimples are ditched in the stent, approxi- mately in the vertical projection of the papillae and zenith.
Elaskary et al. (2016) introduced an innovative easy to use scoring method for assessing the level of peri‐implant soft tissue mid‐buccal gain, to be used before and after treatment to assess the progress of the treatment using a custom fabricated acrylic resin template. The device con- sists of a custom‐designed template that rests on the incisal edges of the maxillary teeth adjacent to the dental implant and has an acrylic extension protruding to the mid‐buccal gingival contour of the affected implant‐sup- ported crown and its adjacent teeth. The template is used to record implant‐related gingival recession, as it reflects the amount of existing recession prior to treatment as a base line to indicate the amount of soft‐tissue correction needed, which is represented by a line connecting the mid‐buccal point of the two adjacent teeth. This method is subjective because it involves an observer who grades the amount of recession on a 0‐to‐2 scoring system.
After treatment of the gingival recession, the same acrylic template will be used again to compare the difference in the levels of the gingival margin and to follow the stability of tissue margins over the years. This is assessed by measuring the deepest point in the mid‐buc- cal curve around the old implant‐supported restoration and comparing it with the soft tissue margin around the new implant‐supported restoration after completion of the treatment. This offers a simple and accurate method to measure the gingival recession treatment outcome. After the recession treatment is completed, the acrylic template can be placed again and the difference in the gin- gival margin levels compared. This technique focuses mainly on monitoring implant‐related gingival recession (see Figures 5.30a and b, 5.31a and b, and 5.32a and b).

5.6 Treatment of Implant‐related Gingival Recession
The treatment of implant‐related recession has not been studied as much as the causes for it (Zucchelli et al. 2013). Peri‐implant tissue architecture thus takes a major share in the esthetic set‐up of any implant‐supported restoration (Buser et al. 1991; Hansson, Albrektsson and Brånemark 1983; Strid 1985). Many authors (Cardaropoli, Lekholm and Wennstrom 2006; De Rouck et al. 2008; Evans and Chen 2008; Juodzbalys and Wang 2007; Kan et al. 2003; Small and Tarnow 2000) have reported various degrees of implant‐related mid‐facial gingival recession; however, proposed repair attempts have been limited mainly to connective tissue grafts (CTGs) (Garber 1981; Lai et al. 2010; Seibert 1993; Shibli, d’Avila and Marcantonio 2004; Wennstrom 1996) or acellular dermal matrix grafts (Mareque‐Bueno 2011).

Investigating the etiology of implant‐related tissue migra- tion is becoming a cornerstone in setting the treatment protocol, because if the reason behind recession is not allocated then any treatment used will be valueless. Another significant factor is the armamentarium available for the clinician to use when considering esthetic zone. Maximum results are obtained with microsurgical instruments that are sharp and precise, and the use of loupes, microscopes, etc. The surgical skills of the clinician is yet another impor- tant factor that will ultimately predict the success or failure of the treatment, and which involves the ability to manage both soft and hard tissue components. Selecting the right candidate for the procedure is important because not all candidates are suitable to receive the treatment.

Several other factors that contribute to the selection of the correct treatment are the degree of recession, oral hygiene level, the intellectual level of the patient to understand the complexity of the treatment, patient will- ingness to treatment commitment, and financial consid- erations; for instance, the additional fees of the treatment.

5.6.1 Preventive Treatment Options
Nowadays practitioners must comprehend and manage an extremely esthetically aware population. Often unreasonable demands from patients and occasionally unrealistic promises by practitioners can lead to unsatis- factory experiences for all parties. The main goal of preventive measures is to decrease the possibility of recession occurring.

5.6.1.1 Innovative Implant-related Designs
The currently available micro and macro designs of implant fixtures have offered many advantages for keep- ing bone loss at minimal levels or allowing epithelial attachment to the neck of the implant fixture and thus minimizing the recession tendency. One examples of a breakthrough in implant fixture microdesign is laser etching of the implant collar, which was developed to create the optimal implant surface design. It includes a series of precision‐engineered cell‐sized channels that are laser‐machined on to the surface of the dental implant’s collar (Nevins et al. 2006). Hermann et al. (2001) described surface micro channels as micro- grooves with a specific size and depth. Nevins et al. (2006) reported eight micrometer microchannels that are 6 μm deep and are present in the upper zone of an implant collar that has limited epithelial cell down-growth along the implant surface by inhibiting cell migration and enhanced soft tissue attachment, 12 μm microchannels that are 12 μm deep present in the lower zone of implant collar that inhibited the fibrous tissue growth, and an enhanced proliferation of osteoblastic cells. Weiner et al. (2008) demonstrated limited epithe- lial downgrowth due to closer adaptation of the bone to the laser microtexture collars.

In the study undertaken by Nevins et al. (2006), they described supracrestal oriented collagen fibers running towards microgrooves using polarized light microscopy, whereas micro‐computerized tomography demonstrated a higher bone implant contact covering all threads of the implant (see Figure 5.33a–c).


Iezzi et al. (2006) carried out a histological evaluation  of three immediately loaded Laser‐Lok implants and demonstrated a more stable crestal bone level after four months. Shapoff et al. (2010) have also proved the role of laser etching in preventing crestal bone loss and concluded that it minimized bone loss of up to 0.46 mm. Pecora et al. (2009) concluded that Laser‐Lok implants showed a reduction in bone loss of 70% (1.35 mm) compared to adjacent conventional implants after 37 months of their placement and no clinical difference was noted between mandible and maxilla. Nevins et al. (2006) infer that until now Laser‐Lok has been the only surface treatment that has shown a true physical connec- tive tissue attachment of implant to bone. Therefore, using a laser-etched implant collar might halt implant recession by stopping crestal bone resorption, and stabi- lize soft tissue margins.

Yet another factor that aims to minimize bone loss around the implant fixture is platform switching of the prosthetic components. A traditional horizontally matching implant–abutment connection is less reliable in keeping bone stable compared to implants with a platform‐switched connection. Implants with a tradi- tional platform are positioned equally with the bone crest where a microgap is located near the bone and bone resorption may start. In implants with platform switching, the microgap is horizontally moved away from the bone; thus, less bone loss occurs (Lazzara and Portar 2006). Ericsson et al. (1992) proved that the microgap is contaminated and inflammatory cell infil- trate forms in the connective tissue zone, contacting the implant–abutment interface.

Lazzara and Portar (2006) studied the biologic process that resulted in the loss of crestal bone height, which may be altered when the outer edge of the implant abutment interface is horizontally repositioned away from the outer edge of the implant platform. Towards the mid axis, a radiographic follow‐up over the years demonstrated a smaller than expected vertical change in osseous height. A study found a mean bone loss of 0.7 mm for 30 platform‐switched implants compared to 2.5 mm bone loss for 30 control implants, carried out six months after attachment of the abutment. Another study examined the biomechanical advantage of platform switching using three‐dimensional finite element mod- els. They found that the stress concentration at the cervi- cal bone interface was greatly reduced when a narrow diameter abutment was connected. Canullo and Rasperini (2007) performed a study where in limited cases, implants were placed in the extraction sockets and it was observed that immediate loading with platform‐ switched implants provided peri‐implant hard tissue sta- bility and papilla preservation.

Degidi et al. (2008) examined histologically removing a human implant twomonths after placement and specu- lated that an inward shift of the inflammatory connective tissue zone at the implant–abutment junction could be the reason for bone preservation. Degidi et al. (2008) reported no resorption of coronal bone at a human implant onemonth after loading. Hürzeler et al. (2007) performed a study including 15 patients who received 14 wide‐diameter implants with platform‐switched abut- ments and 8 implants with a regular diameter. Lesser mean crestal bone resorption (0.12 versus 0.29 mm) of 0.12 ± 0.40 mm was observed in platform‐switched cases compared to 0.29 ± 0.34 mm in control cases, oneyear after final restoration. Cappiello et al. (2008) observed that oneyear after loading, a vertical bone loss in 75 plat- form‐switched implants varied between 0.6 and 1.2 mm (mean: 0.95 ± 0.32 mm), while for 56 control implants, the bone loss was between 1.3 and 2.1 mm (mean: 1.67 ± 0.37 mm). A two‐year follow‐up revealed a mean bone loss of 0.04 ± 0.22 mm on 60 platform‐switched implants, while for 60 control implants the mean was 0.27 ± 0.46 mm.

Another study looked at the effect of microthreads and platform switching on crestal bone stress levels using finite element analysis. This study showed that when the abutment diameter decreased from 5.0 to 4.5 mm and then to 4.0 mm, the microthread model showed a reduction of stress at the crestal bone level from 6.3 to 5.4% after vertical loading. Therefore, the value of using platform switching in minimizing apical tissue migration around dental implants was found to be high. Using plat- form‐switched implants definitely minimizes the bone resorption and hence implant‐related gingival recession; those platform‐switched surfaces are proven to improve the peri‐implant mucosa condition.

5.6.1.2 Thickness Doubling of the Labial Tissue Volume
It may not be an overstatement that the majority of surgical implant procedures in the esthetic region include an indication for soft tissue grafting. The inev- itable alteration of alveolar ridge dimensions that fol- lows a tooth extraction often results in the placement of the implant in a site that has undergone a reduction in soft and hard tissue volume in comparison to its neighboring dentate sites. This discrepancy is even more pronounced in single‐implant sites where a con- cavity forms between the edentulous site and the root prominences of the neighboring dentition (Ioannou et al. 2015). The long‐term stability of pink esthetics around dental implant-supported prostheses has been strongly correlated with adequate peri‐implant soft tis- sue thickness, that is, a thick peri‐implant phenotype (Fu et al. 2011; Geurs, Vassilopoulos and Reddy 2010; Kan et al. 2011).

Factors that should be considered when evaluating the need for soft tissue grafting include the level of clinical attachment on an adjacent tooth to support papillary height, the thickness of the coronal soft tissue margin to ensure a proper emergence profile, the thick- ness of labial soft tissue to simulate root eminence and prevent transillumination of underlying metallic struc- ture show up, and the position of the mucogingival junction and amount of keratinized tissue to produce a harmonious blend with that of the adjacent teeth. It was proposed that if tissue thickness is 2 mm or less, the formation of biological width around implants will involve bone loss (Grunder 2011). Later, this statement was confirmed clinically in a study by Linkevicius et al. (2011) showing that up to 1.35 mm of bone loss might be expected if implants are placed in thin mucosal tis- sues. As a possible solution, Linkevicius et al. (2009) suggested investigating the option to thicken soft tis- sues before or during implant placement to reduce crestal bone loss. First described by Edel (1974), the technique of autologous CTG emerged steadily as an indispensable therapeutic tool. Subepithelial connec- tive tissue grafts (SCTGs) or free gingival grafts (FGGs) can be employed to reconstruct the buccal dimensions of the site, improving the tissue thickness and also the esthetic outcome. These grafts create the illusion of root prominence and increase the width of the crestal peri‐implant mucosa to provide an emergence profile for the restoration and to enable the constructed site to closely resemble a natural tooth (Farmer and Darby 2014; Schropp et al. 2003).

When a thin phenotype is diagnosed, an SCTG or an FGG can be used to prevent potential long‐term reces- sion of the facial mucosal margin or permeation of a gray color from the implant transmucosal components (Cosyn et al. 2012a) and by increasing the gingival thick- ness. Gingival thickness augmented with a CTG has been proven to be a successful procedure in preserving soft tissue levels and improving clinical attachments and overall tissue stability when performed in conjunction with implant placement. The use of connective tissue autografts or allografts for thickening the mucosa might add 1.3 mm to tissue thickness. Each graft has its indica- tions and clinical applications. For example, thickening of thin tissues might have an impact on reducing crestal bone loss by an average of 1.8 mm after a one year fol- low‐up (Strub and Gaberthuel 1992; Grunder 2000; Hermann et al. 2007) (see Figure 5.34).

Covani et al. (2004) reported the use of free CTG as a biologic barrier to cover residual alveolar defects associ- ated with an immediate implant to allow undisturbed healing of peri‐implant deep tissue. Studies have shown that this protocol is a valuable procedure to obtain excellent function and cosmetic implant restoration. Bianchi and Sanfilippo (2004) reported that the newly created soft tissue graft was well maintained for up to twoyears and that the facial gingival margin receded on an average of 0.4 mm in twoyears. Kan et al. (2011) reported mid‐facial margin recession of approximately 0.5 mm even after oneyear of immediate implant placement with placing CTG. Papilla levels showed slightly increased tendencies in height of 0.5 mm mesially and 0.3 mm distally from the time the prosthesis was in place. The cumulative implant success rate following single immediate tooth replacement with dental implants and a SCTG was 90% after a one‐year follow‐up. Shibli et al. (2004) studied the use of a SCTG to augment a soft tissue margin discrepancy for a single‐implant crown in the anterior maxilla and concluded that the use of soft tissue grafts to correct an esthetic deficiency may be consid- ered a feasible approach to establish new and stable peri‐ implant soft tissue contours. Covani et al. (2007) and Marconcini et al. (2013) both conducted a study on 10 patients (5 men and 5 women) in the age group of 42–55 years. The teeth were extracted and implants were placed without consideration of a mucoperiosteal flap. Immediately after implantation, a CTG was placed over the implants to treat the gingival recession. The second stage of surgery was performed sixmonths after the initial procedure. Esthetic outcomes were evaluated using the measurements before implant placement and 12 months after surgery for the width of the keratinized mucosa, the emergence profile of the crown, and patient satisfaction. It was concluded that the surgical approach used can be considered as a treatment option in cases with non‐salvageable teeth showing gingival recession and the absence of attached gingiva.

However, the timing of implant placement following tooth removal may be important to take advantage of soft tissue healing without losing bone volume. Thickening of the connective tissue interface between the implant and the soft tissue seems to ensure long‐ term stability of the biologic width and thus the esthetic profile (see Figure 5.35a–l).

Tsuda et al. (2011) conducted a study on 10 patients (4 men, 6 women) with a mean age of 48 years (range from 35 to 70) who underwent extraction and immediate tooth replacement with SCTG. It was found that at one year, all implants remained osseointegrated, with an overall mean marginal bone change of +0.10 mm and a mean facial gin- gival level change of −0.05 mm. Papilla Index scores indi- cated that at 12 months more than a 50% papilla fill was observed in 80% of all sites. The results of this case series suggest that, in addition to a favorable implant success rate and peri‐implant tissue response, the facial gingival level around single immediately placed implants can also be maintained following connective tissue grafting when proper three‐dimensional implant positioning is achieved and bone is grafted into the implant socket gap.

In a study by Grunder et al. (2010), 24 patients were treated consecutively with implants placed in the maxillary anterior area at the time of tooth extraction. Among the study sub- jects, 12 patients were treated without raising a flap, whereas the remaining 12 patients were treated with a subepithelial connective graft that was placed using the tunnel technique in the labial area at the time of tooth extraction and implant placement. An average loss of soft tissue volume in the non‐ grafted group was 1.063mm, whereas in the grafted group there was a slight gain of 0.34mm.
It is the author’s opinion that with any thin tissue phe- notype, a CTG should be undertaken routinely to stabilize peri‐implant tissues, to minimize bone resorption, and to prevent possible future recession.

In cases with a thin or fenestrated facial plate wall in the anterior maxilla mostly due to the facial position of anterior teeth roots, undergoes substantial resorption following tooth extraction (Araujo and Lindhe 2005; Cardaropoli et al. 2005). Preoperative diagnostic proce- dures and risk assessments should include CBCT scan, because it yields submillimeter accuracy for linear measurements (Loubele et al. 2008).

The facial bone wall should ideally measure at least 2 mm thick to ensure proper soft tissue support and to avoid resorption of the facial wall following restoration (Buser et al. 2006, 2009; Grunder et al. 2005). Whenever labial plate bone is deficient or thin, bone augmentation procedures are recommended to achieve an adequate bony contour (Belser et al. 2009) (see Figure 5.36a–k).

In a study by Braut et al. (2012), CBCT was used to examine the facial bone wall of teeth in the anterior maxilla. The results indicated that the facial bone wall in the ante- rior maxilla is mostly thin, with a mean thickness between 0.5 and 0.7 mm. The analysis yielded a trend towards decreasing thickness from posterior (first premolars) towards anterior tooth positions (central incisors).

A thin facial bone wall undergoes a substantial resorp- tion process within the first four to eightweeks following tooth extraction, leading to a reduction in bone height of approximately 2–3 mm on the facial aspect (Araujo and Lindhe 2005). This bone resorption is a biologic phe- nomenon, caused mainly by the interruption of blood supply through blood vessels within the periodontal liga- ment. Nevins et al. (2006) confirmed these results in their study, where the ridges of non‐grafted extraction sockets showed a more than 20% loss of crest height. In consequence, an implant site with a missing or a thin facial bone wall requires a bone augmentation procedure if a reasonable esthetic and functional outcome are desired. The goal of such a procedure is to build up the bony contour necessary to resist against recession for adequate support of esthetically pleasing soft tissues (Buser et al. 2008, 2009).

Several treatment modalities have been described for osseous augmentation of the labial plate of bone prior to or along with implant placement (thickness doubling). These include GBR (Buser 1993) with or without particulate bone grafting with bone blocks harvested intraorally or extraorally. The mandibular symphysis and ramus buccal shelf are excellent intraoral sources to obtain a corticocancellous or pure mono‐cortical bone block, respectively, for alveolar ridge augmentation.

The symphysis has been reported to provide sufficient bone to augment a deficient ridge by 4–6 cm in the horizontal dimension and up to 4 mm of thick- ness covering a length of up to a three‐tooth defect (Pikos 2000; Schwartz‐Arad and Chausu 1997). With an average bone volume of approximately 860 mm (Buser 1993; Wang, Misch and Neiva 2004) (see Figure 5.37a–d).
 
The symphysis offers a larger graft volume of over 50% than can be obtained from the mandibular ramus, with much easier surgical access (Wang et al. 2004). The average symphysis graft is composed of 65% cortical bone and 36% cancellous bone, as opposed to the mandibular ramus, which is nearly 100% cortical (Schwartz‐Arad and Chausu 1997).

The corticocancellous nature of bone harvested from this site facilitates faster vascular in‐growth once the block has been placed, resulting in more rapid integra- tion and less potential resorption during healing (Hammack and Enneking 1960). However, for thicken- ing a thin plate of bone, only a small bone graft size is required. Most cases can be resolved with a 1 mm thick monocortical block. As these monocortical block grafts compensate for the lost ridge width successfully, lamellar bone sheaths may be used to augment the ridge width and replace or thicken the resorbed bone plates (see Figures 5.38a–c and 5.39a–l).

In a study by Hämmerle, Araújo and Simion (2012), bone growth along the implant surface achieved using lamellar bone sheath along with a membrane to act as a scaffold, measured 91% for the membrane only group, 52% for the lamellar bone group, and 42% for the non‐grafted group. The width of the regenerated bone was 1.5 mm above the bottom of the original defect. In conclusion, the lamellar bone sheets exhibited osteoconductive properties and hence can be recommended for GBR procedures in dehiscence defects (see Figure 5.40a–o).
 
5.6.1.3 Subcrestal Implant Placement
Many authors have advocated subcrestal positioning of dental implants to minimize the future potential for recession. Barros, Novaes and Korn (2015), in a histologic study in dogs, found that vertical bone resorption was decreased in the subcrestal groups compared to the equicrestal groups. Weng, Nagata and Bell (2008) and Welander, Abrahamsson and Berglundh (2009), in two different experiments in dogs, found that healing of implants placed in a subcrestal position could result in osseointegration to the abutment region of the implant (i.e. coronal to the IAJ). The location of the implant shoul- der subcrestally avoids metal exposure and allows an ade- quate vertical dimension with an esthetic emergence profile. Changes in the buccal soft tissue margin were observed by Chen et al. (2007), with a mean follow‐up of 18 months, marginal tissue recession of greater than 1 mm occurred in 33% of the sites. The occurrence of recession was significantly associated with the position of the implant shoulder in relation to the buccal bone plate. Recession of 16.7% occurred in the position of the implant shoulder and 58.3% in the buccal bone plate. Thicker bone and soft tissue around an implant is essential for ensuring long‐term success. Placing an implant >2 mm from the facial bone and 1 mm subcrestally has resulted in greater preservation of the crestal bone. However, it is the author’s recommendation that subcrestal implant positioning needs to be performed with extreme caution to avoid implant positioning that might be too deep; future peri‐ implant soft tissue thickness should be properly calculated prior to undertaking this maneuver.

5.6.2 Treatment for Class I Recession
Marginal soft tissue stability is considered to be a significant factor for achieving any esthetic outcome with implant‐ supported restorations (Zucchelli et al. 2013) for which a stable architecture of the peri‐implant soft tissues plays a pivotal role in the esthetic outcome. The facial gingival margin around the restored dental implant must be of the same emergence as that of the contralateral tooth, that is, in harmony with the adjacent teeth. The occurrence of gin- gival recession related to dental implant‐supported resto- ration in the facial aspect becomes a dilemma for both patients and clinicians (Gracco et al. 2009). Moreover, the thin gingival phenotype fails to act as a strong barrier against bacterial invasion of the peri‐implant tissue (Cairo, Pagliaro and Nieri 2008). In contrast, the thick gingival tis- sue phenotype will eventually resist against future gingival recession due to the enhanced quality of soft and hard tis- sue (Linkevicius et al. 2010) and will react to trauma by forming a periodontal pocket (Fu et al. 2011). It has also been observed that the influence of tissue phenotype on a peri‐implant tissue response seemed to be limited only to facial gingival recession and does not influence interproxi- mal papilla or proximal marginal bone levels (Kan et al. 2011). Thus, the clinician must identify the type of tissue phenotype at the implant site before starting treatment so likelihood of soft tissue recession can be minized.

Long‐term changes have been reported in the position of the facial soft tissue margins following restoration of 106 stage I ITI implants in 39 patients, in both maxillary and mandibular anterior regions. After twoyears, a 1 mm mid‐facial soft tissue recession was present in 61% of the patients (see Figure 5.41a, b).

Unlike natural teeth where a minimal recession of 1–2mm might not always produce esthetic discomfort, a minimal amount of titanium exposure can jeopardize the overall treatment outcome, as it may be unacceptable to the patient. Ideally, clinicians should select the technique for treating these situations (class I implant‐related gingival recessions) based on the best available evidence. Unfortunately, most systematic reviews on mucogingival therapy (Cairo et al. 2008; Oates, Robinson and Gunsolley 2003; Roccuzzo et al. 2002) have not presented information regarding the treat- ment of peri‐implant soft tissue recession. They managed recession reduction on natural teeth, which represents the mean percentage of root coverage. Depending on the surgical technique utilized, it is within the 50–90% range, the latter value being considered clinically satisfying (see Figure 5.42a–e).

At the 6th European Workshop on Periodontology, Cairo et al. (2008) presented a narrative review, based mainly on expert opinions, case reports, and case series. Literature analysis showed that (1) the width of keratinized tissues did not influence the survival rate of dental implants; (2) there is no evidence to recommend a specific technique to preserve/augment keratinized tis- sue; and (3) factors including bone level, keratinized tissue, and implant features have not been shown to be associated with future mucosal recession around dental implants. The only possible conclusion, approved by the Consensus Report (Palmer and Cortellini 2008), was that although scientific evidence in most part is lacking, soft tissue augmentation at implant sites may be considered in some clinical situations (see Figure 5.43a–e).
 

One prospective cohort study (Burkhardt, Joss and Lang 2008) tried to evaluate the outcome of soft tissue dehiscence coverage around single‐implant restoration. A coronal advanced flap (CAF) with CTG techniques was used to treat 10 patients and they evaluated healing up to six months. After one month, the mean of soft tis- sue dehiscence coverage was 75%, 70% at threemonths, and 66% at six months. They concluded that a clinically significant improvement of soft tissue dehiscence was obtained with a combination of CAF and CTG, but com- plete “recession” coverage was not possible.

Shibli et al. (2004) described the use of a subepithelial CTG to repair a soft tissue margin discrepancy for a single‐implant crown in the anterior maxilla. Lai et al. (2010) presented a resubmerged implant technique with connective tissue grafting for implant coverage around a maxillary left central incisor of a 39‐year‐old woman. Mareque‐Bueno (2011) described a surgical procedure for coronally advancing the peri‐implant mucosa to treat a soft tissue dehiscence in a single‐ tooth implant‐supported restoration. The results for all these reported the possibility of achieving only partial soft tissue coverage over an implant‐supported restoration with the combined use of an acellular dermal matrix and a coronally positioned flap (see Figure 5.44a–d).

In a study on 20 patients, Zucchelli et al. (2012) presented a treatment consisting of the removal of the implant‐ supported crown, reduction in the implant abutment, a cor- onally advanced flap in combination with CTG, and final restoration. At oneyear the mean coverage was 96.3% and complete coverage was achieved in 75% of the treated sites. Esposito et al. (2012) attempted a systematic review for the Cochrane Collaboration Group, but he was not able to find a single acceptable randomized control trial in the literature to provide recommendations on which would be the best incision/suture techniques/materials to correct/augment peri‐implant soft tissues (see Figure 5.45a–g).

Wilson et al. (2013) performed a study with 16 patients, who presented a peri‐implant buccal soft tissue recession and consequent exposure of the collar of the implant. A thick gingival cuff of the maxillary tuberosity area was selected as the donor site. After local anesthesia of the recipient and donor sites with mepivacaine plus epinephrine 1:100000, an intracrevicular incision was performed and a partial thickness flap was elevated. After preparing the recipient site, the gingival cuff was excised. The donor soft tissue was de‐epithelialized and trimmed with a mucotome to give a U‐shape to facilitate an opti- mal adaptation to the collar of the implant. The prepared connective tissue was placed in the recipient bed and immobilized. Complete coverage was achieved in 9 of the 16 cases (56.3%) (see Figure 5.46a and b).
 
A modified socket seal surgery has been developed by Misch et al. (1999). A composite autograft made of con- nective tissue periosteum and bone is used to seal the socket. A CTG has the advantage over a keratinized graft by blending into the surrounding attached gingival regions offering similar color and texture of the epithe- lium. The composite graft also contains autogenous bone. The major advantage of autologous bone is a more rapid and predictable osteogenic activity. The composite graft technique is indicated when a non‐infected tooth is extracted with defective socket walls and an implant is planned as a replacement. It is not indicated for infection in the socket area or if bone removal was required to extract the tooth (see Figure 5.47a and b).


In conclusion, CTGs can treat minimal tissue discrep- ancies, provided that the implant is in the correct 3D position. However, the use of CTGs to treat class 1 reces- sion is not as successful as when used with anural teeth, because they don’t offer a high success rate. The smaller the recession size, the more chances for CTG to succeed.

5.6.3 Treatment for Class II Recession
Class II (moderate recession) is an implant‐related gingival recession that ranges between 1 and 2 mm from the mid‐facial aspect, with both proximal papillae intact heights. It has two subdivisions: class II division 1, where the labial plate of bone is resorbed while the palatal plate of bone is intact, and class II division 2, where both plates of bone (labial and palatal) are resorbed and confirmed by the CBCT scan (see Figure 5.48a–d).

The author introduced a novel proposed treatment protocol called the combo protocol, since it is a combina- tion of two soft tissue procedures: (1) the double papilla approximation flap and (2) the subepithelial pedicle pala- tal flap. The combo protocol is used in conjunction with any osseous grafting technique, no matter what the osse- ous corrective procedure is. In other words, it is a pure soft tissue discipline with a complementary osseous grafting of the defective socket walls. Before starting with the correction procedure, the availability and quality of the soft tissue should be inspected. The partial‐thickness palatal pedicle graft technique was first proposed by Cohen and Ross (1968) who reported more than an 85% success rate in covering denuded roots. The double papilla approximation flap also gives predictable useful results (see Figures 5.49a, b, 5.50a and b, and 5.51a–d).

Burkhardt and Lang (2005) investigated the surgical cov- erage of reseeded roots caused by trauma or inflammatory reactions that seem to be a common feature of the buccal tissue morphology. Mathews (2000) demonstrated that, for immediate implants, the palatal subepithelial connective tissue pedicle provides an underlying tissue bed for the double papilla approximated flaps in the presented combo protocol. All the prosthetic parts should be removed at the time of surgery to allow the optimal graft positioning (see Figures 5.52a, b, 5.53a–i, and 5.54a–g).
 
In the study by Elaskary et al. (2016), 10 patients (5 females and 5 males) between 24 and 63 years of age presented with class II division 2 gingival recession (1–2 mm recession from the mid‐facial aspect with inter- dental papilla intact, where both buccal and palatal plates of bone are deficient by >3 mm. Detailed medical histo- ries were obtained, and exclusion criteria included smok- ing and alcoholism. Informed consent forms were signed after an explanation was given of the procedure. All 10 patients received preoperative clinical and radiographic examinations (CBCT) and baseline plaque index scores were documented. Baseline markings of gingival reces- sion were recorded using a specially designed acrylic template. Measurements were again recorded at four, six, and ninemonths, postoperatively. The protocol used involved a double papillary flap approximation and rotated palatal subepithelial connective tissue pedicle graft used together and covering any particulated or autogenous bone graft material (Elaskary and Pipco 2000) (see Figures 5.55a–i and 5.56a–e).

All surgeries were performed under local anesthesia after removing all existing prosthetic parts. The surgery involved three stages: soft‐tissue preparation, implant removal and replacement with a new implant, and finally bone grafting of the osseous defect.

The double papillary approximation flap was per- formed buccally and a No. 15c blade was used to make a V‐shaped incision labially around the recession location, following the outline of the gingival recession. This incision provided a fresh wound surface for tissue approximation. Two relaxing horizontal incisions were made on the adjacent mesial and distal interdental papilla coronally parallel to the cementoenamel junction with a No. 15c blade to allow better relaxation of the flap, fol- lowed by two releasing oblique incisions made at the line angles of the adjacent teeth and extended beyond the mucogingival junction. At the base of the flap, the peri- osteum was scored to prepare a tension‐free flap closure. The V‐section was then raised together and sutured together using a suture needle 6–0 proline interrupted sutures (Ethicon, Agnthos AB, Sweden). A palatal flap was dissected to obtain SCTG directly opposite to the reces- sion location, which would be later rotated to the buccal recession area labially. Dissection of the mucoperiosteal flap and the underlying preparation of a subepithelial connective tissue flap to a depth of 5–8 mm were then performed (Khoury and Happe 2000). A sharp incision of the subepithelial tissues was then made parallel to the first incision to harvest a SCTG, but leaving it attached in the anterior region as a pedicle (see Figure 5.57a–e).

The failed implant was then removed and fol- lowed by inserting a new implant (BioHorizons, Birmingham, Alabama, USA) simultaneously. Then the osseous defect around the new implant was grafted with a particulated autogenous bone grafting mix. The bone graft mix was formed of autogenous bone chips harvested from the operating site using bone scraper and bone allograft particles. The par- ticulated bone graft was then stabilized and covered with a poly‐DL‐lactic acid membrane (PDLLA) (KLS Martin, Germany) and four thermal screws (see Figure 5.58a–v).

The palatal subepithelial connective tissue pedicle was then rotated labially to cover the bone graft and sutured to the shield membrane using a 6–0 coated VICRYL™ (Ethicon, Agnthos AB, Sweden). The palatal wound at the donor site is then sutured along with the labial flap using 6.0 proline (Ethicon, Agnthos AB, Sweden). The new implant was left submerged during the healing period and a resin‐bonded bridge was used as a provisional prosthe- sis. Postoperative instructions were given to the patients along with postoperative antibiotics (see Figure 5.59a–h).


All patients, were followed for four, six, and ninemonths after surgical recession coverage. Table 5.2 presents the recordings of the presurgical degree of implant‐related gingival recessions (mm) and postoperative amount of soft‐tissue gain (mm) throughout the study period. Moreover, the mean±SD amount of implant‐related gingival recession (mm) at different follow‐up periods is represented in Table 5.3. On average, the baseline gingi- val recession was 1.9 ± 0.5 mm, which decreased signifi- cantly (P < 0.05) during the study to reach 0.6 ± 0.9 mm after four months. Furthermore, at six and nine months postoperative, gingival recession observed was 0.7 ± 0.9 mm, which was also statistically significant compared to baseline values (P < 0.05). On comparing gingival recession values at four, six, and nine months postoperatively, no statistically significant difference was evident, proving that the amount of soft tissue gained after the surgical procedure did not deteriorate and showed good stability during the follow‐up period.

At the end of the nine‐month follow‐up period, all cases showed improved soft tissue coverage of the recession area (Table 5.4) except two patients who failed to show soft tissue gain, one was a smoker and the other had a higher plaque index with a score of 2.

At the early clinical attempts to search for the best clini- cal protocol offering a high clinical predictably, it has been found that using coronal repositioning flaps alone does not offer any improvement of recession around den- tal implant sites. The discipline of the combo proposed clinical protocol offers mainly a soft tissue solution to provide an optimal and adequate housing for the bone graft of your choice. That means that the soft tissue pro- vides the optimal housing for any bone graft to be used, which favors the improvement of the receded areas. The decision to remove or retain the implant depends on the degree of bone resorption around the implant. In class II division 1, the implant should not be removed; in such case, the exposed threads get decontaminated, and then grafted. In class II division 2, the implant must be com- pletely removed and replaced with a new one (if the bone resorption is more than 4 mm on the platal side).

Identifying the tissue phenotype and the reason for the implant‐related gingival recession becomes a vital part of the treatment. CTG solutions alone usually offer less con- sistent success rates for the treatment of class I implant‐ related gingival recession (see Figure 5.60a–c).

Each time a soft tissue surgery is performed, soft tis- sue scarring and soft tissue stiffness will be anticipated. This explains the benefit of the non‐staged grafting approach where soft and hard tissue are augmented and repaired in one session, along with the complete removal of the inflammatory tissue in the site (see Figure 5.61 a and b).


5.6.4 Treatment for Class III Recession
Class III implant‐related gingival recession presents more than a 2‐mm recession from the mid‐facial aspect where the peri‐implant papillae vertical height is dropped. A cus- tomized treatment approach is proposed for class III reces- sion. The available options involve inlay grafts, interposition grafts, biocritical grafts, and onlay grafts. Below are some treatment suggestions for class III recessions. All the cases presented with class III recession should have a custom- ized approach, no single protocol is described for these cases, because it has variable degrees of tissue damage and profile collapse (Jensen and Terheyden 2009).

To increase the vertical height of mandibular and max- illary edentulous ridges, onlay grafting using bone blocks was first introduced in the early 1990s (Pikos 2000). The classic block augmentation technique involves the use of an autologous bone block fixed to the recipient ridge with osteosynthesis screws or dental implants (Cordaro et al. 2010). After performing recipient site corticotomy to encourage nourishment the graft, the latter is laid over the defective recipient bed and immobilized (Levin, Nitzan and Schwartz‐Arad 2007).

Onlay autogenous grafts can be used to treat horizon- tal ridge deficiencies; however, when used to treat verti- cal ridge defects, it would be used from both aspects of the defective ridge labial and palatal plates. The bone healing cascade occurs with the infiltration of inflamma- tory cells, followed by in‐growth of new vessels and the replacement of necrotic tissues (Lee and Butler 1997). These events vary depending on the status of graft vascularity, the characteristics of the graft, and the con- dition of the recipient bed. Nonvascularized grafts undergo necrosis, as only the osteocytes on the surface re-establish blood supply and survive (Manson 1994). The remainder of the graft is infiltrated by blood vessels from the recipient site and repopulated by recipient MSCs (Lee and Butler 1997) (see Figure 5.62a–e).

For larger defects, cortical bone shells can be used to augment both labial and palatal sides. Bone shells are harvested with a special cutting wheel from the retromolar region, then the bone granules inserted between the two shells from resorption. Additional harvesting of bone chips is also necessary (Khoury and Khoury 2007). A corticocancellous bone block was har- vested from the lateral side of retromolar area using piezosurgery and had a thickness of about 3 mm. A bone mill was used to produce bone chips, then the block spliced into two pieces with a cutting wheel and used as the shells (Stimmelmayr et al. 2012). The milled bone chips were mixed with autogenous blood and placed between the shells after fixation, and collagen fleece placed to fill the donor site defect (Khoury and Khoury 2006) (see Figure 5.63a–q).



By elevating a full‐thickness flap with a crestal inci- sion, it is shifted palataly and two further vertical reliev- ing incisions, allows complete visibility and access.
The bone shells were trimmed and adjusted with a round bur and anchored in the host bone with tita- nium micro screws. Space between two shells and the alveolar bone can be filled with a mix of milled bone chips and blood or allograft alone, or particulate allo- graft. The bone graft was covered with a resorbable collagen membrane then flap closure performed. The major advantage of this technique is the abundant restoration of the natural bone architecture, with a minimal resorption rate (see Figure 5.64a–o).

Another clinical application that can increase the vertical dimension of the alveolar bone is the use of sandwich‐interpositional osteoplasties. When com- pared to onlay grafts, there is a major advantage because the soft tissue remains attached to the alveo- lar ridge of the place to be grafted (Kawakami et al. 2013), thus minimizing the tendency for wound- related complications. Sandwich osteotomies present the possibility for the good healing tendencies of inlay and interpositional osteoplasties (sandwich) with angiogenesis from all sides of the graft, i.e. closed compartment (see Figure 5.65a–f ).

The sandwich technique, which uses a bone block graft positioned between osteotomized bony segments, was successfully combined with the visor osteotomy to augment a severely atrophic edentulous mandible (Stoelinga et al. 1986) (see Figure 5.66a–d).

This surgical method implies filling the osteotomy cavity with a material – autologous bone or any other filling biomaterial. Interpositional or inlay grafts as a “sandwich” involve the placement of graft material within a three‐walled cancellous compartment. This allows the recipient sites to contain and stabilize the graft material, and the circulating blood flow between the osteotomized bony blocks provide cells, soluble regulators, and nourishment (Kraut 1985) (see Figure 5.67a–l).

The surgical procedure involves an elliptical incision of 10–12 mm from the ridge bone in the labiobuccal gin- giva of the edentulous area. A full thickness flap is raised without detaching the lingual and the crestal mucoperi- osteum to expose the labiobuccal cortical bone of the posterior atrophic mandible and the mental nerve. Two vertical and one horizontal osteotomies are made with a surgical burr and saws. The horizontal osteotomy was located at least 2 mm below the ridge bone and 2 mm above the mandibular canal. The osteotomized segment was then raised in the coronal direction, sparing the lingual periosteum (see Figure 5.68a–c).


A block autograft or xenograft block might be placed as an interpositional graft between the mobilized bone block and the basal bone; a particulated autograft can fill in the gaps around the interpositional graft. The bone block is them stabilized to the basal bone tita- nium miniplates and miniscrews. The grafts can be covered with a collagen resorbable membrane. A flap was sutured in two layers, the inner layer submucosal mattress sutures and the outer layer suturing mucosa. After six months, all the space was filled with viable bone, the moved osteotomy block was stable to place an implant, with an average gain ranged between 5 and 8 mm of vertical gain (Kawakami et al. 2013) (see Figure 5.69a and b).

A similar approach to sandwich osteotomy is the osteoperiosteal flap (OPF) that is achieved through a vascularized segmental moving osteotomy. The biologic principles are acquired from Le Fort I tech- niques in craniomaxillofacial surgery. This technique depends on maintenance of vascularization in bone fragments from the periosteum. The OPF technique has made a strong contribution towards management of these defects. Mobilizing a segment of alveolus attached to the overlying soft tissue can obtain uni‐ or bi‐directional augmentation (Jenson 2010). OPFs through segmental osteotomies are used in combina- tion with interpositional grafts in the gap generated by transposition of the flap in the desired position to achieve a vertical ridge gain. The preoperative plan- ning included fabrication of two surgical splints. The first splint was fabricated for transmucosal position- ing of the implant osteotomy sites in the existing alve- olus position. The second splint was fabricated from the predetermined augmented vertical position of the dentoalveolar segment with ideal inter‐occlusal clear- ance (Tsegga and Wright 2017). The OPF combined with interpositional (inlay) grafts are increasingly being used more for implant site development in ridges with height deficiencies. The main advantage of osteotomy‐based techniques is the preservation of the attached gingiva and even the papillae in some cases (Kramer, Dempf and Bremer 2005).

Sandwich techniques are similar to distraction osteo- genesis in terms of the surgical approach and having similar healing patterns and end results expected for the soft tissue aspect; as with distraction osteogeneses, the liability of soft tissue scar formation is high (Scipioni, Bruschi and Calesini 1994). Distraction oste- ogenesis is a technique used in craniomaxillofacial sur- gery to achieve high bone volume gain in a vertical axis. It is based on the biological principle of bone callus mechanical elongation through slow and progressive separation under tension of two bone fragments sur- rounding the callus to achieve new bone formation (Cheung et al. 2013). The technique includes three phases: (1) the latency phase of seven days, when soft tissues heal around the surgical site where the distrac- tor is placed; (2) the distraction phase, when the two bone fragments are separated incrementally at a rate of 0.5–1 mm day−1; and (3) the consolidation phase, when the newly formed bone mineralizes and matures (Vega and Bilbao 2010). The potential is to achieve sig- nificant vertical bone augmentation to adverse reces- sion. Devices utilized can be of intraosseous or extraosseous configuration. An intraosseous approach with a small‐diameter device that achieved vertical bone augmentation of 9 mm and provided a gain of 4–6 mm of vertical height was reported with prosthetic restorable distractors (Chiapasco et al. 2004).
There are many instances when extensive surgery is refused by patients, in these cases the option of another resolution is also important. Lost peri‐implant tissues can also be corrected by applying gingiva‐colored porcelain on the cervical portion of implant‐supported ceramic restorations, thus saving the hardship of performing complex surgical interventions.

5.7 Conclusion
The management of gingival recession and its sequelae is based on a thorough assessment of the etiological factors, the skills of the clinician, the status of the local tissues, the systemic condition of the patient, and the readiness of the patient to undergo such surgical procedures. Preventive measures should be taken prior to starting the treatment to avoid complications.

Selection of the appropriate treatment modality for implant‐related gingival recession demands knowledge about the underlying causes of the recession. The diag- nosis of the etiology enables a clinician to treat the cause rather than only the manifestation.

Factors like gingival phenotype and labial bone thick- ness should be well studied and managed, soft tissue augmentation procedures can be carried out before or simultaneously with the implant placement. Soft tissue correction should be considered as soon as the clinician recognizes the soft tissue deficiencies at any stage of the implant treatment. The selection of the surgical tech- niques should be dictated by several factors, including the anatomy of the defect site, such as the extent of the recession defect, the presence or absence of keratinized tissue adjacent to the defect, the width and height of the interproximal soft tissue, the operator skills, and the depth of the vestibule or the presence of labial frenum (Zucchelli et al. 2013). Moreover, the selection of the shortest treatment path is advisable (Kerner and Migonney 2010). Attempts to reduce the number of sur- geries and intraoral surgical sites, must be considered together. The surgeon’s clinical experience may be a potential factor influencing judgments, case selection, and surgical skills. However, accurate case selection has proven to enhance a long-term clinical outcome (Haghighati et al. 2009).