Introduction

The development of a satisfactory, esthetically pleasing and stable emergence profile in implant dentistry is impacted by a variety of factors, such as implant design, of which there are many, prosthetic platforms, optimal three‐dimensional (3D) implant placement, appropriate depth of implant placement, gingival phenotype (thin/medium/thick) and contour, original tooth shape and form (rectangular‐square/triangular), use of a carefully designed transitional restoration, types of abutment connections and restorative material options. [1] It is essential then that the clinician understands clearly how to develop an effective emergence profile and recognizes the role played by the critical and subcritical contours of transitional and definitive restorations [1–4]. The careful fabrication of provisional restorations and the precise transfer of the soft tissue contours obtained to the final prostheses will allow the achievement of natural results similar to the tooth being replaced.

Implant Selection and its Relation to the Emergence Profile

To generate a pleasing emergence profile, it is important to start from the basics, the selection of the implant itself. The implant design will dictate its correct apicocoronal and 3D positioning [5]. Given that the shapes of implants and those of the teeth being replaced are vastly different, achieving a harmonious transition from the implant platform to the restoration can be challenging. The distance between the implant prosthetic platform and the gingival margin is decisive. It must be precise (not too deep or too superficial) so as not to compromise long‐term gingival biology [6]. Different dental implant designs can have different prosthetic connections, some being more stable than others [5,7–9], and require different depths of implant placement in relation to local crestal bone levels (Figure 10.1). For instance, external and internal hexagonal connections do not achieve high stability, so affected implants are recommended to be installed in shallower positions (i.e. at the level of the crestal bone) to minimize the impact of micro‐movements and bacterial accumulations at the abutment–implant interface on crestal bone [10, 11]. As a result, the space for emergence profile development is reduced. This could compromise long‐term gingival stability, especially if the the gingival phenotype is thin and/or the implant design does not include a platform‐switch feature. Additionally, this type of implant usually prevents the use of intermediate abutments, resulting in restorations being directly connected to the implant. Therefore, to fabricate the final restoration, multiple connections and disconnections at the implant platform level would be required. If a platform switch has not be used, this could lead to marginal bone loss and unfavorable biologic changes in overlying soft tissues [12, 13].

On the other hand, implants with conical or Morse taper connections have greater stability and therefore can be positioned subcrestally 1–2 mm without risk of micromovement‐related bone loss [8, 14] and a negative impact on gingival margins or the size of papillae. Therefore, the subcrestal implant placement will establish enough space to generate a natural emergence profile more easily [15]. Nonetheless, these implants should not be oversubmerged, as this could result in excessive soft tissue height [6] and risk of developing peri‐implant mucositis, which is not easily resolved [16]. Avoiding the risk of bone resorption due to multiple connections and disconnections during the rehabilitation process can easily be achieved with the use of intermediate or transmucosal abutments [17–19]. In this way, the peri‐implant sulcus ends up being shallower, moving the restoration away from the implant platform, without compromising the prosthetic result (Figure 10.2).

Implant Placement in the Esthetic Zone

Once the characteristics of the implant planned have been identified, it is essential to achieve a prosthetically guided implant position to provide the necessary space to shape the optimal emergence profile. As outlined in other chapters of this book, achieving the correct 3D implant position can become challenging in the esthetic zone, making a clear understanding of the anatomy of the region essential. In the hands of highly experienced clinicians, freehand installation is feasible; otherwise, guided surgery using a customized surgical stent is essential (Figure 10.3a–f) [20]. Nonetheless, it is important to remember that, if guided surgery is used, errors can occur if the surgical stent is not correctly designed and handled [21]. Strict protocols regarding any necessary simultaneous bone augmentation, gap grafting, and soft tissue enhancement must be followed closely [22].

The Emergence Profile Contours

The shape of a restoration in the esthetic zone, whether it be provisional or definitive, is fundamental to achieving a natural‐looking outcome that complements the adjacent soft tissues and adjacent teeth. The shape of a crown has two clearly differentiated areas. One is visible in the mouth and defines the shape of the tooth crown, and the other is more apical hidden by the peri‐implant soft tissues and is responsible for their support. These two regions were described and defined by Su et al. [2] as the “critical” and “subcritical” contours respectively (Figure 10.4).

The critical contour determines the visible crown shape and its buccal contour is of particular importance as it determines the position of the future gingival margin, the position of its zenith and ultimately the crown length. Clinically, this contour design should correlate with the anatomy of the contralateral tooth or restoration. (Figure 10.5).

The subcritical contour is located immediately apical to the critical contour and extends from this point to the implant platform. It is hidden beneath the marginal soft tissues and can be customized in shape to achieve different results [3]. For instance, providing horizontal space to allow increases in soft tissue thickness, or if thickness is not an issue, pushing the existing tissues buccally can give the impression of greater volume. Nonetheless, if the implant position is too shallow, the subcritical contour of the restoration will be significantly shortened and may impact negatively on the marginal tissues.

Timing of Implant Placement and its Relation to Emergence Profile

Depending on the timing of implant placement and provisionalization, there are specific objectives related to the management of the emergence profile. In the case of immediate implant placement, the main objective is to maintain the gingival architecture with a provisional restoration, provided that it was initially favorable (Figure 10.6) and that the implant was sufficiently stable at placement (i.e. 35 Ncm) [23]. When this implant stability level is not achieved, the use of a customized healing abutment becomes a viable option to maintain the gingival architecture [24]. For this approach, a primary stability of at least 25 Ncm is recommended. If on the other hand, modifications to the gingival architecture are necessary, such as shifting the gingival zenith apically or coronally, the objective would be to allow the gingival architecture to be guided by both the critical and subcritical contours of the provisional restoration, although optimal outcomes may also require the use of connective tissue grafts placed buccally.

Provided that the 3D position of the implant is adequate, the critical contour of the provisional restoration should begin at the desired position of the gingival margin [25]. The buccal subcritical contour (Figure 10.7) should be as concave as possible, to provide space for the formation of thick buccal soft tissues. Thick tissue is also essential in avoiding tissue transparency problems with unwanted color changes due to the underlying abutment shining through. According to Jung et al. [26], buccal soft tissue thickness at the level of the subcritical contour should be at least 3 mm to hide any restorative material underneath. However, it must be recognized that compression of these tissues by the provisional restoration is to be avoided as it could lead to ischemia of the peri‐implant soft tissues, poor healing and recession.

Prosthetic Modification of the Emergence Profile

If the gingival contours are not as anticipated after soft tissue healing, it is still possible to condition them to achieve the desired result [27]. Strategic augmentations using composite or acrylic resin can be used to modify the contour by taking advantage of the elastic nature of soft tissues. Polishing is mandatory after any modifications so as not to affect healing or induce inflammation. Modifications should be controlled so as not to exceed the tissue tolerance. Controlled pressure on the tissues is characterized by generating a transient ischemia only. Prolonged ischemia for more than 10 minutes is indicative of excessive pressure, which can affect vascularization and result in soft tissue necrosis. It is recommended that modifications be made gradually with breaks of at least 1 week between adjustments to allow the tissues to adapt slowly to the changes made. Figure 10.8 shows the recreation of lost gingival architecture by modifying the prosthesis emergence profile.

Transfer of the Emergence Profile

Once a favorable emergence profile has been achieved through modifications and adjustments of the provisional restoration, it becomes essential to replicate it in fabricating the final restoration (Figures 10.9). Therefore, communication between the clinician and the dental laboratory becomes a key factor. A deficient transfer of the emergence profile will undoubtedly decrease the predictability of the restoration, compromising the expected result.

Accurate transfer of the peri‐implant soft tissue contours to the final model is difficult and, in many cases, impossible with standard impression copings, even if a natural and harmonious emergence profile has been achieved. It is important to realize that once the provisional restoration is removed, the soft tissues at the level of the emergence profile will collapse within seconds. To prevent this collapse from impacting the final result, customizing a transfer impression coping is crucial. This can be done digitally with the aid of an intraoral scanner (Figure 10.10) [28].

Restorative Materials and their Relation to the Emergence Profile

Various restorative materials have been promoted for implant‐supported restorations in the esthetic region, from metal–ceramic to metal‐free zirconia. The latter are becoming more common as there are fewer color issues with thin, transparent soft tissues (Figure 10.11). Most recently, it has been proposed that highly polished zirconia without the application of a glaze is preferable for the subcritical region as it favors epithelial cell adhesion. However, scientific evidence is still limited in this regard.

Conclusions

Obtaining an esthetically pleasing implant‐supported restoration that emerges naturally from soft tissues is challenging. As reviewed in this chapter, several stages are necessary to achieve adequate results. A proper assessment of the patient and an understanding of their wishes and expectations is fundamental for the establishment of an appropriate treatment plan. Coupled with knowledge of the biologic responses in soft tissues and careful attention to the details involved in each of the steps needed to ensure maintenance of the original gingival contours prior to extraction with carefully shaped transitional restorations can help to achieve predictable and satisfying results.