Key points

Osseointegrated endosseous dental implants have been deemed an innocuous and predictable form of rehabilitation that can be used to replace dentition in patients who are completely or partially edentulous and those who are missing only a single tooth. The average survival rate of multiple-implant designs is higher than 90%. The success rate of such implants has also been evaluated, although various criteria have been used and these have changed over time. The criteria for implant success in 1979 permitted 1 mm or less of mobility with some radiographic radiolucency and bone loss, whereas it currently includes absence of mobility, absence of radiographic radiolucency, and minimal bone loss.

Even though the parameters of success have evolved, the early concern in implant dentistry was primarily osseointegration, and even today, osseointegration remains the predominant parameter of success in implant dentistry. However, because of patient and clinician demands and the increased certainty of osseointegration, new parameters are now being used to assess implant success. Some examples of these parameters are peri-implant soft-tissue level, prosthesis level, and patient’s subjective assessments; these parameters should be considered by dentists in evaluating the success or failure of implant dentistry. The focus is shifting from implant survival to the creation of lifelike implant restorations with natural-looking peri-implant soft tissues. Patients today have a high demand for esthetics and want not only improved function but also normal appearance.

Esthetics plays an important role in any implant placement but is crucial for implants placed in the anterior maxilla. An anterior single implant-supported crown restoration must meet a particularly high standard of esthetic quality because the adjacent natural teeth provide an immediate comparison to the crown. Overall, implant dentistry in the esthetic zone is challenging because the implant restoration and surrounding tissues will be visible when the patient smiles fully and because it will be placed in an area of esthetic importance for the patient. According to the Straightforward, Advanced, and Complex International Team for Implantology (ITI) classification, any implant in the esthetic zone must be classified as either advanced or complex, a classification deriving from the technique sensitivity required for replacing missing teeth in the anterior maxilla.

Patients’ and clinicians’ high demands and expectations for esthetics have expanded the criteria for the success of implants from osseointegration alone to a harmonious and natural blending of the restoration with the surrounding tissues and dentition. Higginbottom and colleagues defined an esthetic implant restoration as one that resembles a natural tooth in all aspects. Acknowledging that patients and clinicians consider the esthetics of an implant very important, it should be determined when an implant is considered a failure from an esthetic point of view.

Although the dental literature contains information about esthetic failure in general dentistry, to the authors’ knowledge, no clear consensus is available regarding esthetic failure of dental implants. Late in the 1990s, el Askary and colleagues defined an implant failure as failure of the implant to fulfill its purpose (functional, esthetic, or phonetic). However, the only types of failures associated by the authors were absence of osseointegration, prosthetic fracture, gingival bleeding, and infection. Furthermore, until recently an implant was considered a failure when it was lost, fractured, or mobile, or a source of irreversible pain or infection. In summary, the word failure as applied to dental implants is frequently used in the dental literature to indicate the loss of osseointegration; it has seldom been used to describe a lack of esthetic success. In fact, the word complication is often used when a problem occurs with any of the replaceable components of the implant system.

Most dictionaries define failure as “lack of success.” If this definition is extrapolated to esthetics and dental implants, esthetic failure in implant dentistry would refer to a lack of success in achieving esthetics with dental implant restorations. Consequently, success in implant dentistry needs to be redefined.

The dental literature demonstrates the lack of a consensus about the parameters used to determine esthetic success or esthetic failure in implant dentistry. As mentioned, some authors apparently do not consider these parameters important, because they consider only osseointegration when evaluating the success of their treatments. Other authors report esthetic failures but fail to provide adequate information about how these failures were evaluated. Henry and colleagues reported an esthetic failure rate of 10% in a 5-year multicenter study; nevertheless, the authors did not report the parameters used to determine the cause of these esthetic failures. Similarly, Goodacre and colleagues did not describe poor esthetic outcomes as failures but rather as esthetic complications. As examples of such complications, they reported improper restoration contour, poor shade, and exposure of implant components because of gingival recession.

Esthetics refers to the response of the mind and the emotions to beauty. As Lew Wallace wrote, “Beauty is altogether in the eye of the beholder.” Two important factors influence this concept in dentistry: the patient and the clinician. Esthetics is a subjective perception that varies from individual to individual and is also influenced by sociocultural values. Chang and colleagues demonstrated that the appreciation of esthetic outcomes is higher among patients than among prosthodontists. They indicated that the factors considered by clinicians to be important for an acceptable esthetic result of restorative therapy may not be imperative for patient satisfaction. Dueled and colleagues, on the other hand, found a positive linear correlation between professional and patient evaluations of esthetic outcomes, but this correlation was not statistically significant. In most studies, patients were more satisfied with the overall outcome than was the professional examiner.