Introduction

Replacing missing teeth with dental implants in partially or fully edentulous patients has become a routine treatment modality [1, 2]. While osseointegration remains the predominant parameter in recognizing the success of dental implants, other parameters related to implant fixtures, peri-implant soft tissue, prosthesis, and patient satisfaction have been introduced [3]. Following tooth extraction, soft and hard tissue alterations can occur as a result of the biological and clinical modifications of the alveolar ridge [4]. Due to these changes, adequate treatment planning, including implant placement in the correct 3D position and reconstruction of lost soft and hard tissues, is recommended for reliable long-term implant success [5]. Despite various techniques suggested for bone grafting before implant placement [6], there are scenarios where soft tissue grafting can compensate for bone loss, provide better esthetic results, and achieve stable peri-implant soft tissue [7•].

Hard and soft tissue deficiencies around dental implants are common clinical findings that are caused by tooth extraction and resorptive ridge processes, periodontitis, endodontic infections, and trauma prior to implant placement, and by improper implant position, poor prosthetic design, peri-implantitis, and continued facial growth after implant placement [8]. As a result, complications such as poor esthetics, marginal bone loss, soft tissue inflammation, recession, and implant loss may arise [9,10,11]. While all implant locations in the mouth are prone to soft tissue deficiencies, there are distinctions in their occurrence and impact between implants placed in the esthetic zone and those placed in posterior areas.

The most commonly encountered soft tissue discrepancies in the anterior zone include facial recession related to lack of buccal bone [12, 13], insufficient papilla height [14, 15], and gingival asymmetry between teeth and implants due to life-long skeletal changes [16]. In contrast, posterior implants typically present with lack of keratinized mucosa (KM) as the predominant soft tissue deficiency.

Soft tissue grafting around dental implants has been recommended to enhance functional, biological, and esthetic outcomes. Several techniques have been proposed to maintain and augment peri-implant soft tissue including various flap designs, graft materials, and suturing techniques. Two major indications include the increase of the KM width and the increase of soft tissue volume using autogenous or alternative-type grafts [17, 18•, 19•]. Furthermore, these grafting procedures are performed at different timepoints: (a) prior to implant placement, (b) at the time of implant placement, (c) at the time of second-stage surgery, (d) during implant bone healing, or (e) after implant restoration. The first four usually yield more predictable results when compared to grafting after implant loading as the latter is typically performed to repair an implant biologic or esthetic complication that might have a non-soft tissue–related etiology [20].

The aim of this review is to present pertinent literature on peri-implant soft tissue including its role, indications for augmentation, techniques used to change the quality and quantity of the soft tissue, and corresponding timing of those procedures.

Gingival Tissue and Peri-implant Mucosa

Despite similar clinical appearances, it is critical to highlight various histological differences that distinguish peri-implant mucosa from gingival tissues around teeth:

  • Peri-implant mucosa has more collagen and less fibroblasts, when compared to gingival tissue [21, 22].

  • The connective tissue length around implants varies between 1.1 and 1.7 mm [23]. The fiber bundles of the peri-implant mucosa run parallel to the implant or abutment surface without attaching to the implant, while periodontal fibers insert into the root via Sharpey’s fibers and run perpendicular to the root surface [24]. Some human studies suggested direct attachment of collagen fibers into laser microgrooved implant surfaces [25, 26].

  • Although the junctional epithelium is considered to be structurally similar around teeth and implants, it is approximately 2 mm long around implants whereas it averages 1 mm of length around teeth [23, 27].

  • Supracrestal vascular topography around the implant is reduced and differently arranged compared to gingival tissues [24, 28]. Implants lack a periodontal ligament and the only vascular supply of the peri-implant soft tissue originates from the supraperiosteal blood vessel and intraalveolar supply [24].

Collectively, these histological differences document that the peri-implant mucosa is less cellular and vascular than gingival tissue and that it confers a close adaptation to the collar of implant abutments and restorations rather than a functional attachment. Therefore, it is imperative that this peri-implant soft tissue attachment is not compromised by aggressing factors such as plaque-induced inflammation, thin phenotype, trauma from improper tooth brushing, reduced vestibular depth, and muscle pull at the marginal tissue.

Overall, probing depths around implants are greater than those around teeth [29]. There is no defined range of probing depth measurements compatible with peri-implant health and a stable peri-implant soft tissue [29]. Signs including edema, erythema, suppuration, and bleeding on probing and bone levels are considered in determining health from disease around dental implants.

Soft Tissue Grafting to Increase the Width of Keratinized Mucosa

Similar to keratinized gingiva, KM clinically extends from the mucosal margin to the mucogingival junction. It is frequently reduced at implant sites following tooth loss, especially at sites where advanced bone augmentation procedures have been performed, in which the mucogingival complex is coronally displaced to achieve tension-free closure at time of ridge reconstruction.

Overall, inconclusive evidence exists regarding the need for an adequate KM width to facilitate proper oral hygiene and maintain long-term implant health. KM width ≥ 2 mm was shown to have a favorable effect on overall tissue health, plaque and bleeding scores [30,31,32], and long-term maintenance of implants [33]. On the contrary, the maintenance of peri-implant bone level [34], risk for peri-implant disease [35], and implant health and soft tissue stability [36] did not seem influenced by the amount of KM. However, a recent systematic review [7•] and a consensus report [37] favored soft tissue grafting to increase KM width resulting in greater reduction of inflammation signs and a greater maintenance of crestal bone levels.

Types of Soft Tissue Grafts

Various techniques have been presented in periodontal plastic surgeries to widen the zone of KM around dental implants with different success rates. These techniques include apically positioned flap/vestibuloplasty, free gingival graft (FGG), subepithelial connective tissue graft (SCTG), acellular dermal matrix (ADM), and xenogenic bilayer collagen matrix (XCM) [38].

Autogenous grafts (i.e., FGG and SCTG), harvested from the patient’s palate, are considered the gold standard in soft tissue augmentation procedures with the most predictable results [38]. It was clearly shown that these grafts were able to transplant the characteristics of the palatal tissue to the recipient site, owing to the genetic information carried by the connective tissue inducing epithelial keratinization [39]. To compensate for FGG shrinkage and achieving optimal outcomes, there is always a tendency to harvest larger grafts which is associated with significant patient morbidity. Minimally invasive techniques such as the “strip gingival autograft” were introduced to limit the volume of harvested grafts where two thin strips of FGGs are harvested and placed parallel to each other leaving exposed periosteum between these strips at the recipient site [40]. As a result, a significant decrease in patient morbidity along with widening the KM zone is achieved. Despite various advantages for FGG, unfavorable esthetic outcomes, donor site morbidity, limited graft amount, increased hemorrhage risk from donor sites, and unpleasant patient experience are all considered drawbacks for using autogenous grafts.

Xenogeneic collagen matrix (XCM) was recently introduced as a viable alternative for autogenous grafts in soft tissue augmentation procedures [41]. It consists of types I and III collagen in two layers, a superior thin layer that is cell occlusive and a porous thick layer that is placed on the periosteum of the recipient site to aid in cell ingrowth, tissue integration, and stabilization of the blood clot [42,43,44].

Another alternative for autogenous grafting is the acellular dermal matrix (ADM) allograft that is derived from human skin. ADM, originally used for treating burn wounds [45], is an epithelium free, freeze-dried matrix containing types I and III collagen bundles where elastic fibers are its main components [46, 47]. ADM acts as a bioactive scaffold that integrates in host tissue and permits the migration of fibroblasts and epithelial and endothelial cells through vascular channels of the recipient sites [48]. Since its initial use, ADM has been widely used in dental practice, in particular for soft tissue grafting of gingival recession [49] or to change the quality of peri-implant/teeth mucosa [50].

Table 1 summarizes available studies that evaluated KM increase using various types of grafts. The majority of investigations included the use of autogenous tissue as a control group in mostly equivalence studies to advocate for an alternative graft type, i.e., ADM or XCM. It is noteworthy that greater KM increase was consistently found with autogenous grafting in the reviewed studies.

Table 1 Summary of studies on soft tissue grafting to increase KM
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The timing of soft tissue augmentation for KM increase seems to vary depending on the clinical situation and clinician preferences. It is uncommonly performed prior to implant placement, in particular prior to ridge augmentation procedures to improve the volume of soft tissue and KM width in preparation for the subsequent treatment phases. However, this approach has been proposed by some clinicians [51, 52]. Studies comparing outcomes of soft grafting before and after implant placement are lacking. Figure 1 illustrates a case of FGG prior to ridge augmentation and implant placement.

Fig. 1
figure 1

FGG prior to ridge augmentation and implant placement. a Lack of KM on crestal and buccal aspects of edentulous ridge no. 18–19, b split-thickness APF preparation, c FGG secured to adjacent tissue and periosteum with sutures, and d wide band of KM is noted after 12 weeks

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The following sections will discuss those grafting techniques according to the timing at which they are performed.

Grafting at Time of Second-Stage Surgery

Irrespective of the graft type, the recipient bed is prepared with a split-thickness flap design with a horizontal incision at the MGJ and two vertical incisions outlining the mesial-distal extension of the graft. The flap is apically positioned (APF) and sutured. The graft is trimmed to allow appropriate adaptation to recipient site without interfering with flap margins or any movement caused by lips and cheeks. An example of KM augmentation at time of implant uncovery is illustrated in Fig. 2.

Fig. 2
figure 2

FGG at time of implant uncovery. a Initial presentation of mandibular posterior right sextant. Note absence of KM around tooth no. 29 and ridge, b APF and periosteal bed preparation, c FGG sutured around uncovered implants site no. 30 and tooth no. 29, and d 4 months healing after FGG

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FGG is considered to be the gold standard for augmentation of the KM width around implants; however, it is less desirable in esthetic areas due to poor blending characteristics in color and texture with adjacent gingival tissue. A range of KM width gain between 3.35 and 8.93 mm has been reported with FGG [41, 53, 54].

When comparing three grafting techniques at time of implant uncovery, i.e., (a) APF without a graft material, (b) roll flap, and (c) APF combined with SCTG, the mean KM gain was 4.63 mm, 1.35 mm, and 4.10 mm respectively [55]. The ability to displace KM with an APF, with or without additional FGG or SCTG, to the facial aspect of an implant is prevalent in the maxilla where keratinized tissue is readily available in the palate, whereas the use of FGG or SCTG in the mandible is far more common [18•].

Another treatment modality to establish an adequate band of KM at the time of uncovery is APF in combination with XCM after relocating and securing the existing KM apically to XCM. This technique was shown to result in a mean of 4.81 mm of KM after 3 months with comparable histological findings between native and regenerated KM biopsies [56]. A similar concept was applied by harvesting a 2–3-mm FGG strip from the palate and suturing it at the apical extension along with XCM covering the coronal aspect of the recipient site [44]. A mean KM width of 6.33 mm was reported with a 43% shrinkage rate of the grafted area at 6 months. The authors theorized that the FGG strip acts as a barrier and provides a source of keratinization. In a 5-year study, an average KM width gain of 8.4 mm and 6.15 mm was reported using APF with FGG and XCM respectively. The reported shrinkage from time of grafting was 40.65% for FGG and 52.89% for XCM [54].

A systematic review concluded that either a vestibuloplasty or an APF combined with FGG or XCM achieved acceptable results for KM increase whereas only a combination of APF with either FGG or XCM yielded acceptable results in the mandible at time of implant uncovery [18•].

Grafting Around Healed and Loaded Implants

As previously mentioned, soft tissue augmentation after implant loading is more challenging because the soft tissue defect may be related to other complications. Among all techniques to increase peri-implant KM, the application of FGG seems to be the treatment of choice with mean gains ranging between 2.36 and 2.57 mm [57, 58]. A statistically significant advantage was shown for combining vestibuloplasty and FGG versus vestibuloplasty alone in terms of KM increase (2.36 mm and 1.15 mm respectively) [57].

When evaluating alternatives to autogenous grafts, a 2.3-mm mean gain of KM width was reported with the use of APF in combination with either SCTG or XCM [59]. Another study used a combination of APF and CTG instead of FGG and found a significant gain in KM width (mean 2.3 mm) [59]. Similar esthetic results were reported in both groups with more favorable pain perception outcomes with XCM [59].

Similarly, ADM use was reported in the treatment of mucogingival defects around uncovered or loaded implants. In a pilot study, a mean gain of 2.2 mm at 6 months and a significant decrease in plaque index was reported [60]. However, limitations of this study were the small number of subjects and the lack of a control group; thus, those results should be interpreted carefully. When compared to FGG, ADM achieved significantly lesser KM gain (2.57 mm for FGG vs 1.58 mm for ADM) at 6 months after grafting [58]. In this study, ADM shrinkage was considered a drawback, yet the indication to use ADM or other substitutes to autogenous grafts may be justified by decreasing patient morbidity.

In summary, the use of APF in combination with either FGG, SCTG, or XCM achieved comparable and significant increase in KM width [19•]. Nevertheless, according to available evidence, the amount of KM gained with FGG and XCM was significantly greater than ADM [19•]. Overall, surgical intervention after restoring the implants seems to be more challenging and has a higher level of complications [20]. Figure 3 represents a KM augmentation procedure after loading of implant prosthesis.

Fig. 3
figure 3

FGG after implant loading. a Initial presentation of minimal tissue thickness and KM width at implants supporting mandibular fixed detachable prosthesis, b APF and periosteal bed preparation, c FGG sutured around uncovered implants, and d 6 months healing after FGG

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Soft Tissue Grafting to Increase Soft Tissue Volume

Graft type selection for volume augmentation is largely similar to that in procedures to increase KM width. One difference is that most autogenous grafts used for this application tend to be SCTGs as they are typically combined with a bilaminar technique.

From a treatment indication standpoint, there are largely three clinical situations for soft tissue augmentation to increase soft tissue volume: phenotype modification and/or recession coverage, papillary reconstruction, and increase of vertical tissue thickness.

Increasing peri-implant tissue thickness has not been shown to influence clinical parameters such as plaque control, probing depth, and bleeding on probing in a recent systematic review [7•]. However, implants with augmented tissue thickness were found to maintain marginal bone levels better than thinner non-grafted sites in the same review which recommends soft tissue thickness augmentation [7•].

It has been advocated that the typical “saucerization” of peri-implant bone level happens both horizontally and vertically and is considered to be related to the establishment of the biologic width around implants, especially in thin mucosal tissue < 2 mm prior to abutment connection [61].

Initial peri-implant bone remodeling is widely reported in the healing phase and its amount seems to depend on implant design, location of implant-abutment interface, and prosthetic connection [62,63,64]. Tissue-level implant designs allow for a vertical shift of the implant-abutment interface owing to their transmucosal portion and have also been shown to have minimal bone loss during the first year of loading [65]. For bone-level implants, platform switching is currently a standard feature in the design of implant-abutment interface. Its concept is to horizontally displace the micro-gap between implant and abutment in a medial direction, and has been shown to minimize crestal bone remodeling when compared to regular-matched platforms [66,67,68,69,70]. It is noteworthy that platform switching of implants was not found to have less marginal bone loss in other randomized trials [71, 72]. Other factors have been proposed to influence crestal bone loss including submerged implant polished collars and vertical soft tissue thickness. The positive effect of platform switching designs on the amount of crestal remodeling was challenged in the presence of thin soft tissue defined as < 2 mm [73, 74]. When investigating vertical and horizontal mucosal thickness around implants, it was reported that a thin peri-implant tissue phenotype was associated with more bone loss (average = 1.76 mm) [73] compared to thick peri-implant phenotype (average bone loss = 1.18 mm) [74]. A systematic review demonstrated that there is a short-term advantage for implants placed in initially thicker peri-implant soft tissue (≥ 2 mm). Implants that were crestally and supracrestally placed had 0.35 mm and 1.29 mm less bone remodeling, respectively, when placed in thicker soft tissue height. Hence, soft tissue augmentation to increase tissue thickness at time of implant placement may be considered to minimize marginal bone loss [75•].

From a timeline standpoint, these soft tissue grafting procedures may be performed at time of implant placement, at time of second stage implant surgery, or after implant loading.

It is noteworthy that a recent systematic review did not demonstrate any significant impact for the intervention timing of soft tissue grafting procedures on clinical outcomes when performed to increase KM or tissue thickness in simultaneous or staged approaches [76]. Nonetheless, the following sections will discuss the available evidence and techniques to augment soft tissue volume at different stages of implant therapy (Table 2).

Table 2 Summary of studies on soft tissue grafting to increase tissue thickness and volume
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Grafting at Time of Implant Placement

Soft tissue grafting during implant placement may be performed for tissue phenotype modification in anterior cases, to increase the vertical soft tissue thickness in posterior cases (Fig. 4) or to achieve soft tissue coverage at sites of immediately placed and non-loaded implants.

Fig. 4
figure 4

Vertical tissue thickening with ADM at time of implant placement. a Preparation of ADM graft using healing abutment, b positioning of graft secured with abutment at implant no. 30 and extending over buccal and lingual aspects of ridge, c flap adaptation around abutment with sutures, and d final radiograph demonstrating abutment fit

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The concept of vertical thickening of the peri-implant mucosa at time of implant placement has been based on animal histological study [61] and advocated by clinical studies [73, 74, 75•, 77,78,79,80] to minimize crestal bone remodeling. Initially, subepithelial connective tissue grafts were reported as means to increase vertical tissue thickness without demonstrating an influence on the amount of bone remodeling [81]. The use of acellular dermal matrix (ADM) allografts has been proposed in a double-layer approach to create a 2–3-mm increase in thickness, requiring periosteal releasing incisions and coronal advancement of buccal and lingual flaps for tension-free closure over graft, and reporting increase in tissue thickness and less bone remodeling [77]. Similarly, the use of collagen xenograft matrix was supported by a clinical and histological study in the increase of tissue thickness and tissue integration [82].

Several techniques have been proposed to achieve soft tissue closure over immediately placed and non-loaded implants, including the use of FGG [83, 84], CTG [85], or pedicle split- or full-thickness palatal flaps [86,87,88,89] to seal the socket orifice during implant healing. While these grafting procedures dramatically improve the soft tissue volume, their effect on implant survival or esthetic outcomes long term has not been evaluated.

Tissue phenotype modification using facial soft tissue grafting at sites of immediate implants has been performed to minimize the risk of future recession and tissue translucency in the presence of thin bone and soft tissue. Most techniques describe minimally invasive procedures using sulcular incisions and a pouch preparation to insert the graft on the facial of the ridge. SCTG has been supported in randomized controlled studies in minimizing future recession [90], increasing facial thickness and improving esthetic outcomes [91]. In a short-term study, ADM was found to increase facial thickness similarly to SCTG [92]. While these grafts enhance the facial tissue thickness and ridge contour, conclusive evidence to support their influence on mid-facial mucosal margin positions is lacking [93].

Grafting at Time of Second-Stage Surgery

Many clinicians find it opportune to augment or manipulate the peri-implant soft tissue at time of implant uncovery, especially in anterior sites. In maxillary sites, adequate palatal tissue thickness is readily available to be used in different versions of pedicle flaps to augment the facial tissue thickness and tissue height. Studies supporting these approaches are mostly short-term case series that document improvement in papilla fill and facial convex profile (CPF [94]) using a palatal roll flap [95] and facial tissue thickness using a roll envelope flap or an apically positioned flap with SCTG [55]. A trap door technique was also suggested for single or multiple implants incorporating a roll flap for tissue thickening, although no outcome measures could be assessed [96]. A palatal split envelope flap technique for papillary reconstruction of anterior and premolar single implants showed a consistent improvement in papilla fill using the Jemt index [15] in a case series [97]. However, in the absence of the osseous framework and adherence to prosthetic principles, predictable techniques to reconstruct missing papillae do not exist. Minimal or no information is provided about the effect of these grafts on the mucosal margin level.

Despite the relatively weak evidence to support advantages of grafting at second-stage implant surgery, soft tissue manipulation at the edentulous sites is frequently performed to improve the facial thickness and esthetics (Fig. 5).

Fig. 5
figure 5

Roll flap at implant second stage surgery. a Palatal incision for full-thickness flap preparation to uncover implant no. 9 using the Tinti & Parma-Benfenati technique, b de-epithelialization of inner flap in preparation to roll it to facial aspect of abutment and implant, c primary closure and increased facial tissue thickness are achieved, and d final implant restoration after 2 years. Note thicker tissue appearance on facial aspect

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Grafting Around Healed and Loaded Implants

Soft tissue volume augmentation following implant loading is generally performed to treat conditions such as recession, thin phenotype leading to graying of the mucosa or discomfort upon performing oral hygiene, or gingival asymmetry resulting from continued facial growth (Fig. 6).

Fig. 6
figure 6

Correction of gingival line asymmetry with ADM. a Initial presentation of implant no. 8 placed > 20 years ago. Note uneven margins evident due to high smile line. b, c Double-layer ADM to maximize graft thickness in preparation for insertion into facial tunnel. d Healing at 2 weeks. Note coronal advancement of mucosal margin. e Final contour showing convex profile of tissue, and f 1 year follow-up after delivery of new implant restoration

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The treatment of recessions has been mostly described with SCTG and coronally advanced flaps [98,99,100,101]. The vast majority of these studies are case series of a limited number of patients. Nonetheless, 6-month recession mean coverage of 66% of moderate recessions was reported, with an advantage recorded for thicker flaps at baseline [98]. Shallow recession defects appear to be more responsive to this therapy after 5 years with an 86% mean and 50% complete coverage respectively [99]. In another 5-year case series, the removal of the implant prosthesis and its replacement with a supra-mucosal provisional restoration with a narrow transmucosal abutment was deemed critical for the success of the soft tissue grafting to predictably repair moderate recession defects, leading to 99.2% mean and 79% complete coverage, respectively, and a mean tissue thickness of 2.6 mm [101].

The use of ADM in the treatment of implant recessions has been limited and provided limited coverage (28%) in a 6-month study when compared to SCTG (40%) [102]. On the other hand, ADM achieved greater gain of tissue thickness than SCTG (1.75 mm vs 1.00 mm) [102]. It is noteworthy that the soft tissue deficiencies treated in that study were combination of recession, thin tissue, and concavity defects, which renders any comparisons inconclusive. Finally, the use of XCM to specifically treat implant recession defects has not been well documented in the literature.

The increase of mucosal thickness is usually achieved as a collateral objective of using a graft to increase either KM width or recession coverage. However, tissue thickness increase may be an independent treatment objective in cases of thin phenotype and esthetic concerns. A prospective 5-year study did not find a significant influence of tissue thickening with SCTG on the level of mucosal margin when compared to non-grafted sites [100]. The stability of tissue thickening with SCTG at time of provisionalization was demonstrated in a 1-year case series (mean of 0.97 mm) irrespective of baseline tissue phenotype [103].

When XCM was used in a case series to improve facial contour or mucosal graying, it achieved a mean 0.7-mm increase in thickness with no significant changes to mucosal contour or color after 6 months [104].

A systematic review concluded that both a split-thickness flap (STF) and coronally advanced flap (CAF) in combination with SCTG achieved a significant coverage of recession defects. On the other hand, STF + XCM and CAF + AMD did not produce significant coverage [19•].

Soft Tissue Management with Implant Restorations

The predictability of long-term implant maintenance and the esthetic outcomes of implant restorations greatly depends on an optimal 3D implant position and an adequate implant restoration.

An ideal implant restoration is one that resembles the missing natural tooth in all dental and gingival aspects. Since implants typically have a narrower diameter than teeth, it becomes imperative to use information provided by an ideal surgical guide allowing for an optimal apico-coronal implant position and the subsequent fabrication of an adequate transmucosal portion of the implant restoration. Implant provisionalization plays an important transitional role and results in the shaping of the peri-implant soft tissue following a proper emergence profile [105,106,107,108]. Specifically, a temporary crown at an anterior immediate implant aims to maintain the existing soft tissue architecture in addition to its esthetic benefits. [109, 110]. Soft tissue management via restorative approaches needs to be considered, sometimes in lieu of or in conjunction with soft tissue augmentation, whenever possible. When immediate temporization of an implant is not feasible or indicated, available preliminary information seems to favor the use of custom healing abutments to improve the soft tissue management and esthetic outcomes [111, 112].

Furthermore, the choice of abutment material was shown to influence soft tissue esthetics from a tissue color perspective [113,114,115]. Zirconia or gold abutments are generally recommended when peri-implant soft tissue thickness is less than 2 mm due to their greater colorimetric performances in comparison to titanium.

Conclusions

The role and clinical condition of the peri-implant mucosa can be easily overlooked in treatment planning in implant dentistry. Failure to recognize existing or to anticipate future soft tissue deficiencies may jeopardize the success of dental implants. Implant success is no longer simply defined by the Albrektsson criteria [116] but has additional components that assess the peri-implant soft tissue health, prosthesis, and patient satisfaction.

In light of the available evidence, the authors of this review conclude and propose the following:

  • A minimal KM band or its absence seems to be less tolerated around implants than natural teeth. Due to its relative controversy, increasing KM width around implants may need to be evaluated on an individual basis. Subjects that demonstrate sub-optimal levels of plaque control due to challenging access for hygiene, dexterity shortcomings, or chronic inflammatory signs at mucosal margins may be good candidates for grafting. In addition, patients who undergo advanced ridge reconstruction procedures for implant site preparation may benefit from a bound-down peri-implant mucosa that seems to be more protective than alveolar mucosa. Risk assessment remains key in evaluating benefits and risks for each patient.

  • Soft tissue volume increase is either performed vertically to thicken the supracrestal tissue attachment minimizing crestal bone remodeling, or horizontally to thicken the tissue phenotype to mask future esthetic failures or to treat existing defects on healed and restored implants. Increasing horizontal tissue thickness to mitigate future complications is not well supported with evidence whereas vertical thickening seems to be supported in the literature. However, additional studies by other investigators are recommended to validate this conclusion. The success of soft tissue grafting to treat defects on healed and loaded implants seems to be inconsistent due to potential multifactorial etiologies. Nonetheless, clinical situations requiring soft tissue corrections may be inevitable to avoid further complications leading to implant loss.

  • Timing of soft tissue grafting varies depending on the indication and clinician preferences. Procedures to increase KM are more commonly performed around healed and loaded implants or at second-stage surgery. It is recommended that a risk assessment is performed at the treatment planning phase to incorporate KM augmentation if deemed indicated. Soft tissue thickening seems to occur more often at time of second-stage surgery or implant placement.

  • The implant position remains an imperative influencing factor on the health and/or appearance of the soft tissue. An implant placed too superficially or too facially may cause esthetic complications especially in thin phenotypes. An implant placed too deep may lead to biologic complications and affect the health of hard and soft tissues. The authors recommend a careful and multi-disciplinary approach in treatment planning for implant site development, placement, provisionalization, permanent restoration, and maintenance.