When patients seek care to replace missing or failing teeth with dental implant-supported prostheses, they are normally looking for an esthetic outcome. It is important to recognize that clinical situations differ from one another and that there are a number of clinical variables that may compromise the chances of achieving a predictable esthetic result. These clinical images show examples of various clinical scenarios that may pose different esthetic challenges in terms of the number of teeth that are to be replaced and the amount of soft and hard tissue present in the implant site.

In order to better understand the criteria to achieve esthetic outcomes, it is first necessary to define the characteristics of an esthetic implant-supported prosthesis. The ITI accomplished this during its Consensus Conference in 2004. The definition is: An esthetic implant-supported prosthesis is one that is in harmony with the dentofacial structures of the patient. There are two components: the peri-implant tissues and the prosthesis. In terms of the peri-implant tissue, an esthetic result means: The health, height, volume, color and contours of the peri-implant tissues must be in harmony with the healthy surrounding tissue. The prosthesis should imitate the natural appearance of the missing dental units in color, form, texture, size and optical properties.

All patients who are to receive an implant-supported prosthesis should undergo a general risk assessment that includes their past medical history, current medications, allergies, smoking habits, periodontal status and occlusal function. Patients who carry a high risk indicator in one or more of these aspects should be informed of the increased potential for esthetic challenges associated with their treatment. The medical risk factors include diseases that impair bone healing, immunological diseases, treatment of medical conditions requiring high doses of corticosteroids, uncontrolled diabetes mellitus and irradiated bone. This list is not exhaustive and every patient's medical status needs to be evaluated on an individual basis. A compromised medical status carries the risk of impaired wound healing and a compromised result that could negatively affect the esthetic outcome. Patients with medical risk factors are therefore considered high risk patients. Patients with a history of chronic periodontitis have a high risk of developing biological complications such as peri-implantitis during the maintenance phase. These patients need to be carefully assessed and monitored closely once the treatment has been completed. Lack of oral hygiene is also a significant risk factor for developing biological complications. Patients with poor oral hygiene should not be given implant treatment until a high level of motivation and compliance can be demonstrated. Parafunctional habits such as bruxism increase the risk of technical and mechanical complications with implants and the attached prostheses.

In addition to the general risk factors for implant treatment, patients will present with several clinical factors that can have either positive or negative influences on the potential to achieve the aforementioned esthetic requirements. In the first volume of the ITI Treatment Guide Series from 2007, twelve clinical factors were presented in a tabular form that identify potential esthetic risk factors related to implant therapy. The esthetic risk factors in order of their listing in the table are: medical status, smoking habit, patient's esthetic expectations, lip line, Periodontal phenotype (biotype), shape of tooth crowns, infection at the site, bone level at adjacent teeth, restorative status of adjacent teeth, width of edentulous span, soft tissue anatomy and bone anatomy at alveolar crest. Each factor may be categorized as having a low, moderate or high esthetic risk depending upon the clinical presentation. Utilizing this Esthetic Risk Assessment system prior to the initiation of care will assist the treatment team in identifying patients who carry a high risk of a negative esthetic outcome. In the following slides, we will highlight each of these factors and discuss the influence they may have on achieving an esthetic result.

As previously stated, patients who carry a medical risk factor should be informed of the increased challenges regarding the esthetic outcome. While an intact immune system is a low risk factor, a reduced immune system carries a high risk for an inadequate esthetic result mainly due to impaired wound healing.

Patients who plan to undergo implant surgery and report a history of smoking should be made aware of the increased risk for surgical complications and resulting negative esthetic outcomes. Especially when augmentation of hard or soft tissue is planned, smoking may lead to a failure of the graft as can be seen in the clinical example. The resulting situation may be worse than the initial situation. Patients are usually classified as mild smokers when they smoke less than 10 cigarettes per day. They have a moderate esthetic risk. Patients smoking more than 10 cigarettes per day are classified as heavy smokers and have a high esthetic risk. In both groups there is a significantly increased risk of complications when compared to non-smokers. Every attempt should be made to explain this to the patient and offer smoking cessation options. When necessary, treatment alternatives should be considered.

Prior to the initiation of treatment, the patient's desires and expectations should be reviewed. Low expectations are associated with a low risk while high expectations are associated with a high risk of not achieving a satisfying esthetic result. The discussion of the rehabilitation options and their esthetic risk should focus on three aspects: form, function and esthetics of the dentition that needs to be replicated in the dental prosthesis, as reported by Garber and co-workers in 1995. Reviewing these aspects with the patient will help to generate an initial risk profile. With respect to form, the question is whether the edentulous space can be adequately restored. If so, it has to be evaluated whether the resulting restoration will have similar contours to the contralateral teeth. If not, hard or soft tissue grafting procedures may be needed to allow for the ideal tooth form. Problems in achieving adequate results in terms of the form may introduce a moderate to high esthetic risk to the treatment. An evaluation of the occlusion is necessary to determine if a prosthesis can be fabricated to create a harmonious functional environment. When the contours of the prosthesis need to be modified to address a compromised clinical situation, for example in the case of overerupted teeth, the esthetic risk is elevated. Where necessary, diagnostic wax-ups or existing interim restorations can aid in evaluating function. Patients that have high esthetic demands and several moderate to high esthetic risk factors should be informed about on the potential difficulty in achieving these results. This discussion with the patient may help to avoid disappointed patients upon delivery of the implant prosthesis.

The lip line is associated with the amount of tooth structure and supporting tissue that is visible during function, speech and smile. Patients with a low lip line have a low esthetic risk. Patients who exhibit a medium lip line typically display most of their teeth and only very little, if any, of the supporting periodontal structures. The esthetic risk of these patients is elevated due to the increased demand placed on appearance of the prosthesis. This includes tooth size, color, shape, texture, optical properties and embrasure form. In addition, the gingival margins and papillae also need to be considered when planning the reconstruction. Patients characterized by a high lip line often display their teeth in entirety as well as a significant portion of the supporting soft tissues. The esthetic risk of these patients is greatly increased, mostly due to the visibility of the gingival tissue. There are several clinical situations where it may be difficult to develop healthy, symmetric, contoured soft tissues, particularly when restoring adjacent implants in a patient with a high lip line. In such cases it may be difficult to achieve an optimal esthetic outcome.

Patients who exhibit a thick periodontal phenotype are usually at low risk when single teeth are replaced. The gingiva in these patients is characterized by thick, broad bands of keratinized tissue that can also mask the color of the implant and abutment, thereby reducing the esthetic risk. This tissue phenotype is resistant to recession, but can be more prone to post-surgical scar formation when augmentation procedures have been performed. When adjacent implants are required, the character of the thick tissue reduces the likelihood of inter-implant papillae formation.

In contrast, patients with a thin periodontal phenotype have a high level of risk. They are often associated with excellent single-tooth implant esthetics when the surrounding dentition is periodontally healthy and the bone crest has sufficient height. The gingiva in these patients is characterized by thin and friable soft tissue with high scalloped papillae. This tissue type has been associated with a higher risk of post-surgical recession, which is one of the main reasons for the high risk profile. Predictable long-term results can only be achieved when careful attention to detail is drawn with regard to implant position, supporting bone and prosthesis emergence profile. When adjacent implants are needed, periodontal surgery to alter the phenotype is often required in conjunction with the implant placement. Due to the high risk level, implant therapy in these patients should be approached with caution.

The shape of the missing and adjacent teeth can greatly influence the risk level associated with the implant-supported prosthesis. Since the esthetic outcome is strongly influenced by the final gingival architecture, the risk is usually reduced in the case of rectangular teeth since these are often associated with thick periodontal phenotypes. This tooth shape is also characterized by broad contact areas and closed embrasure forms which make it easier to obtain symmetry with the adjacent teeth. In contrast, triangular tooth forms pose a greater risk as they are more often associated with thin, high scalloped gingiva when they are surrounded by teeth with good periodontal health. A high risk factor is especially noted in cases with periodontal defects and loss of the interproximal papillae. These cases will require an implant prosthesis with a rectangular shape to avoid the appearance of interproximal spaces that are also called black triangles. However, this prosthesis form will in turn have a negative effect on the esthetic outcome due to a lack of symmetry with the adjacent teeth.

Patients who report a history of infection at or adjacent to the implant site can pose a higher esthetic risk than patients without infections. Local infections associated with periodontal disease, endodontic lesions, post-traumatic lesions or foreign bodies are capable of directly reducing the quantity and quality of the hard and soft tissues at the proposed implant sites or the adjacent sites. Effective treatment of the local infection may result in loss of esthetically important tissue that may compromise the esthetic outcome of the prosthesis. The characteristics of the local infection, whether it is chronic or acute in nature, will determine the degree of risk associated with the infection control therapy. Chronic infections, in particular chronic periapical lesions of teeth to be replaced by implants, bear a moderate risk for complications with esthetic significance if they are not resolved prior to implant placement. In acute situations, the highest risk is associated with infections that exhibit suppuration and local swelling.

In situations with single missing teeth, the interproximal dental papillae depend on the height of the bone crest of the adjacent teeth. Therefore, the contours of the prosthesis, specifically the positions and extent of the contact areas and therefore the overall esthetic outcome also depend on the height of the bone adjacent to the implant site. In situations where local infections have resulted in vertical bone loss around adjacent teeth, the risk of a negative esthetic outcome is greatly increased. Furthermore, the regeneration of crestal bone along a previously infected root surface is unpredictable and unlikely with currently available treatment options. Therefore, the risk increases with the degree of vertical bone loss on the adjacent teeth. A loss of 5 millimeters or less to the contact points is a situation with a low risk. A loss of 5.5 to 6.5 millimeters is considered to be a moderate risk, while a loss of 7 millimeters and more indicates a high esthetic risk.

When teeth adjacent to an edentulous area are virgin and healthy from a restorative perspective, no additional risk to the esthetic outcome is expected. Adjacent teeth with restorations extending into the gingival sulcus, however, represent an increased risk. Subgingival crown margins are often associated with recession subsequent to the placement of an implant. Esthetic complications can also arise from exposed prostheses margins or an altered gingival architecture. For these patients, meticulous treatment planning is vital and may include the replacement of the adjacent restoration as part of the treatment, or a modification of the surgical incision technique to reduce risks.

The chances of achieving an esthetic outcome are high for patients requiring replacement of a single missing tooth. In these situations, healthy adjacent teeth and supporting structures will aid in supporting the soft tissues and optimizing the emergence profile of the implant prosthesis. This support is provided by the proximal bone crest at the adjacent teeth when the distance from this bone to the prosthesis contact points is short. The risk level is low when the restorative span is at least 7 millimeters in width. The esthetic result could be compromised when the edentulous site is associated with unfavorable periodontal conditions or when the span has an inadequate width of less than 7 millimeters.

The presence of adjacent missing teeth increases the esthetic risk to a high level. The inter-implant soft and hard tissue level is unpredictable because the implant/abutment configuration may cause a loss of coronal bone. The location of the adjacent missing teeth is important in the assessment of the esthetic risk. Missing central incisors provide the best opportunity for an esthetic result due to the potential presence of redundant tissue located in the nasopalatine area and due to the symmetry of the gingival architecture required after healing. In situations where a central and lateral incisor need to be replaced, the esthetic challenge is extremely high since anatomically correct gingival zenith positions need to be provided. Furthermore, the emergence of appropriately contoured adjacent prostheses through the connective tissue is critical. Sufficient papillary support has to be gained, increasing the reliance on appropriate implant selection in both size and shape. In these situations, treatment options should be considered to avoid the placement of adjacent implants and introduce a high esthetic risk.

When examining the available soft tissue in an area that will receive a dental implant, the esthetic risk is low when the soft tissue is intact, but is high when there is a tissue deficiency. Soft tissue deficiencies can be recognized if the tooth to be replaced is still present. The position of the gingival margins on this tooth is then compared to the ones on the adjacent teeth. When a soft tissue deficiency is evident, procedures will be needed to address this. These patients should be made aware of the increased risk in achieving symmetrical margins in the definitive prosthesis. When the tooth to be restored is already missing, an evaluation of the available keratinized tissue should be made with respect to the adjacent teeth. Any deficits in this area are also accompanied by an increased esthetic risk.

The risk of a negative esthetic outcome increases with the degree of horizontal bone loss. In cases as seen in this example, implant positioning can be compromised when the deficiency is not addressed and implants are positioned more palatally and often also facially angulated in the available bone. This improper implant positioning can be detrimental to esthetic outcomes as it can negatively affect the symmetry of the restorations, their emergence profiles and optical properties. Such situations can usually effectively be addressed with horizontal bone augmentation and/or soft tissue grafting.

Deficiencies in vertical bone height greatly increase the risk of not achieving an adequate esthetic outcome, as vertical augmentation procedures are still not entirely predictable. In most cases, regenerative procedures increase the oro-facial width of the implant sites but do not recapture an adequate height. This can often result in a compromised gingival and restorative appearance. When vertical deficiencies are present in multi-tooth edentulous areas, localized grafting techniques such as onlay grafts, free gingival grafts or distraction osteogenesis should be seriously considered. However, the esthetic risk level is very high.

Esthetic Risk Factors, Key Learning Points. The factors to be considered in assessing esthetic risk are: medical status, smoking habit, patient's esthetic expectations, lip line, Periodontal phenotype, shape of tooth crowns, infection at the implant site, bone level at adjacent teeth, Prosthodontic status of adjacent teeth, width of edentulous span, soft tissue anatomy and finally bone anatomy of the alveolar crest. Each factor may be categorized as having low, moderate or high esthetic risk. An evaluation of the risk factors is important to prevent esthetic complications.

When the Esthetic Risk Assessment is utilized during an implant consultation, the identification of each risk factor will generate a scale of categories as seen in this example. This can be used by the treatment team and patient to evaluate the overall esthetic risk. This assessment system can be valuable in explaining to the patient which procedures are necessary to obtain an optimal esthetic result. In addition, this system provides information that will prevent the treatment team from promising outcomes that may not be achievable with current treatment protocols. This example of an esthetic risk profile was generated for a patient with an overall high esthetic risk. In the following slides you will see the clinical images of the patient that led to this assessment.

Both the patient and her parents want to have an esthetic result similar to her original situation prior to the accident, resulting in a high expectation risk factor. Upon full smile, the papillae and gingival margins of the teeth adjacent to the edentulous space are visible, denoting a high risk factor for lip line. When examining the interim prosthesis, it should be noted that pink acrylic resin is visible, highlighting the deficit in soft and hard tissue in the edentulous area. In addition, the patient's general malocclusion with anterior crowding and her periodontal status will need to be addressed prior to initiating any implant therapy.

The adjacent teeth are free of restorations. The patient has an extended edentulous space due to a missing central and lateral incisor. As stated earlier in this module, using adjacent implants in this situation would carry a very high esthetic risk. Adjacent implants are contraindicated in this patient since it is not possible to assure sufficient inter-implant bone support for papillae formation. A single implant with a cantilevered restoration should be considered in the proposed treatment plan along with alternative conventional approaches.

The bone anatomy of the edentulous span has the greatest impact on the esthetic risk. In this case a horizontal defect is apparent when comparing the situation to the contra-lateral side. When evaluating a transverse section of a cone-beam computed tomography at the level of the cemento-enamel junction, both the buccal and lingual plate are missing. This results in a vertical defect that extends beyond the apices of the adjacent teeth. The combined horizontal and vertical defect creates an extremely high risk in achieving a result that will not require prosthetic tissue replacement like pink porcelain.

Upon completion of the Esthetic Risk Assessment, the treatment team can present the esthetic risk profile visually to the patient. If the patient decides to proceed with the implant therapy, she will be better prepared for potentially suboptimal outcomes. The profile may also change her expectations to more realistic ones.

Summary of Risk Assessment Module. The factors to be considered in assessing esthetic risk are: medical status, smoking habit, patient's esthetic expectations, lip line, periodontal phenotype, shape of tooth crowns, infection at the implant site, bone level at adjacent teeth, restorative status of adjacent teeth, width of edentulous span, soft tissue anatomy, and bone anatomy of the alveolar crest.

Each factor may be categorized as having low, moderate or high esthetic risk depending on the clinical situation. An evaluation of the risk factors is important to prevent esthetic complications. Utilizing the Esthetic Risk Assessment during the consultation phase of implant therapy will allow the treatment team to identify the esthetic risk of the proposed treatment. It also allows the team to advise the patient on the likelihood of achieving an optimal esthetic result.