Implant treatments in the visible zone aim to restore function, phonetics and esthetics when a natural tooth requires extraction and replacement. Dental implants have become an accepted treatment modality for the replacement of failing natural teeth with a high degree of predictability, however there are esthetic risks that can compromise the outcome.

When replacing a single tooth in the esthetic zone, the contra-lateral tooth becomes the reference point to which the restoration is compared. Symmetry around the patient’s center line is critical if the restoration is to be viewed as harmonious and natural in appearance. The implant and overlying restoration combine to replicate the lost hard tissue of the natural tooth, however the form of the peri-implant soft tissue creates a scaffold or curtain around the restoration contour. These soft tissue scaffolds must resemble the contour and form surrounding the natural contra-lateral tooth in order for the restoration to mimic the natural dentition it replaces (Chang et al.1999, Belser et al. 1998). The closer the restoration is to the center line, the more significant will any anomaly between the two structures appear to the patient. Hence, the esthetic outcome, relies heavily on the contour of the soft tissue scaffold for the implant replacement of the natural tooth being seen as being symmetrical and pleasing to the eye (Figs 1 - 2)

When the patient has a naturally high smile line that reveals tooth, interdental papilla and gingival zenith, these discrepancies are more obvious and result in treatment failure from an esthetic perspective, in spite of successful osseointegration of the implant (Fig. 3). If there is a low smile line, the alteration in gingival zenith position may not be visible during normal functions (Fig. 4), and a compromised outcome may be tolerated.

In recent years, objective assessment criteria have been proposed as a means to assess the mucosal and restoration esthetics of fixed implant restoration (Furhauser et al. 2005, Belser et al. 2008). The use of the Pink Esthetic Score – PES – (Table 1) provides clinicians and researchers with the possibility to objectively assess the important factors that comprise the scaffold of mucosa surrounding the dental implant. The mesial and distal papilla form, curvature of the facial mucosa, level of facial mucosa, root convexity and soft tissue color and texture all form part of the assessment. These criteria are assigned a score of 0, 1, and 2 to develop an assessment score, with 14 being the highest possible outcome (Furhauser et al. 2005).

The White Esthetic Score – WES – (Table 2) considers tooth form, tooth outline/volume, color, surface texture and translucency for a maximum score of 10.

Figs 5 - 6 demonstrate the clinical application of PES and WES.

There is a relationship between the inherent restoration-related tooth and tissue forms, and a deficient score in one of the parameters in the PES is usually reflected in a reduction of the corresponding related score of the WES assessment. Thus the overall objective assessment of the restoration is demonstrated with a low score value recorded.

Immediate placement of the dental implant into the alveolus at the time of tooth removal, with or without simultaneous restoration, is a technique that has often been proposed to enhance the outcome of the esthetic success and reduce the period of edentulism (Lazzara 1989, Kan et al. 2003). Whilst short-term success is sometimes seen with these techniques, several recent systematic reviews, as well as long-term retrospective reviews, have demonstrated unpredictability of the results (Kan et al. 2011, Chen & Buser 2014; Cosyn et al. 2012). More than 1 mm loss of the mid-facial peri-implant tissue contour is generally accepted as the cut-off point where patients will notice an alteration in mucosal gingival zenith outcome compared to the contra-lateral site. In a recent systematic review of the frequency of advanced recession following single immediate implant therapy, Cosyn et al. stated that limited risk was observed for interproximal recession greater than 1 mm (Cosyn et al. 2012). However, the mean mid-facial recessions reported from the 13 publications reviewed ranged from 0 - 1.16 mm. One publication from this group reported more than 50% incidence of advanced mid-facial recession, and two others, reported the incidence at just under 10%. Whilst the authors report that the use of an immediate provisional restoration is a likely reason why one publication reports a higher percentage of cases with greater mid-facial recession, great caution should be exercised in inferring that this one differentiating factor in study design was the critical difference in achieving optimized outcomes. This is a profound conclusion based on a single RCT, and clinical experience has shown that other factors contribute to achieving esthetic success. A comprehensive systematic review of the literature was completed by Chen and Buser, whose methodology allowed for a larger number of publications to be reviewed and clearly showed the variability in outcome and a risk of mid-facial recession in the range of 20-30%. They reported that many of the studies after 2008 describe the use of strict inclusion criteria with adjunctive surgical procedures, such as grafting with low substitution bone fillers and varied restoration protocols in order to combat the onset of facial recession (Chen & Buser 2014). Unfortunately there is still the high risk of variable outcomes.

Additionally the variability in submergence profile design and abutment material choice is often left unspecified in the studies. What remains critical in achieving an ideal hard and soft tissue replacement for the single implant restoration is that a correct 3-dimensional placement of the implant shoulder within the alveolus, relative to the planned replacement tooth is of paramount importance. Boney remodeling is known to occur around the shoulder of the dental implant to re-establish a biologic width after abutment connection to the implant. If the implant shoulder is facially malposed, these normal and natural remodeling processes will create a vertical loss of bone on the facial aspect of the implant away from the implant shoulder. The soft tissue at the mid-facial position will thus retreat in an apical direction as the bone is lost (Buser et al. 2004). The optimal placement of the implant shoulder in the correct orofacial position, irrespective of a bone level or tissue level implant design, still remains one of the most significant factors relating to esthetic outcomes and the risk of mid-facial recessions (Evans & Chen 2008). This correct 3D position ensures that an intact buccal wall is preserved around the restoration to support the facial mucosal margin and allows the restorative dentist the option to develop an idealized emergence profile (Steigmann et al. 2014). Thus in order to maintain an adequate thickness of buccal bone overlying the shoulder of the implant, the buccal position of the implant shoulder should be kept placed 2 mm lingual to that of the CEJ of the adjacent natural tooth (Grunder et al. 2005). This will serve to preserve facial bone overlying the dental implant.

Pre-treatment planning should ideally involve careful CBCT analysis and clear visualization of the planned final tooth position relative to the alveolar housing. If there is an inadequate volume of alveolar tissue, grafting procedures to re-establish the contour of the peri-implant soft and hard tissue are necessary either at the time of implant placement or as a separate interventional procedure (Buser et al. 2013) (Fig. 7). 

Immediate implant placement at the time of tooth extraction is considered an advanced surgical procedure. Whilst acceptable esthetic outcomes are possible with immediate placement of the implant at the time of tooth removal, the alveolar socket from which the root of the tooth is removed often dictates the direction that the drill path will follow during osteotomy preparation. It takes high surgical skill and diligence to re-direct the drill path away from the socket to allow re-angulation within a correct 3D position (Fig. 8). 

Careful assessment of other esthetic risk factors (Dawson & Chen 2009), such as tooth shape and tissue biotype, as well as angulation of the alveolar anatomy to that of the proposed implant and crown alignment is essential to determine if the risk of recession can be minimized and an acceptable result guaranteed. Whilst excellent outcomes can be achieved in a limited number of cases, the risk of adverse outcomes is high and mal-position will guarantee a poor long-term esthetic outcome (Fig. 9).

Recent CBCT analysis of the thickness of facial bone overlying the roots of anterior teeth was shown to be either thin or missing in 90% of almost 500 cases that were reviewed (Braut et al. 2011). This thin boney plate overlying the root surface is frequently comprised of bundle bone, a structure that is dependent on cementum found in tooth root surfaces. Placement of the dental implant will not prevent loss of the bundle bone on the facial aspect and the ridge contour will lose volume resulting in a lower PES score with noticeable facial concavity (Fig. 10). Therefore, if immediate implant placement strategies are followed – performed in a flapless surgical approach without recognizing the high risk of losing such thin boney walls – facial recession will ensue and a poor esthetic result is guaranteed (Chen & Buser 2014).

Whilst in many instances, immediate implant placement is considered as a means to avoid the short-term inconvenience to the patient of a missing fixed replacement tooth, it is the long-term outcome that should be stressed as of high importance to the patient. Esposito et al. compared the outcomes of three different loading protocols after tooth removal from a patient perspective. After two years, the patients still perceived a shorter treatment time and better outcome with implants placed in the immediate-delayed group. However, five years post-placement these differences had completely disappeared and more complications were observed in the immediate-delayed group (Esposito et al. 2012). When an immediate placement and/or loading option is considered, the transitional immediate loading prosthesis may in fact appear to be esthetically worse than a conventional transitional prosthesis (Fig. 11) and the realization of a a successful long-term outcome should be stressed to the patient.

In 2015, in order to provide patients with a predictable outcome that is stable in the long-term, our preference is to perform delayed implant placement and restoration protocols. The option of immediate implant placement and/or restoration is now limited to a number of highly selective cases.