Implant supported restorative complications

Implant supported restorative treatment options have been increasingly popular among dental practitioners as well as among those patients who are interested in replacing teeth either due to partial or complete edentulism. However, as the number of implants placed has increased substantially, so have the incidence of complications associated with this choice of treatment. Stuart Froum [1] in his textbook on ‘implant complications’ notes several reasons for this increase in the number of dental implant associated complications. These include; a. increasing numbers of implants being placed and an associated increase in the number of complications, b. an increasing number of dentists placing and restoring implants with varying degrees of clinical experience, c. varying levels of competence in the course offerings to train dentists in both surgical and restorative aspects of implant dentistry, d. increasingly aggressive patient selection protocols, e. possibly over simplifying the levels of success associated with implant restorative outcomes giving practitioners a false sense of security.

Implant treatment associated complications can be both surgical and restorative in nature. According to a retrospective study by McDermott et al [2], a frequency of 13.9% implant complications occurred over a time period of 8 years, with operative complications (1%), prosthetic (2.7%), and inflammatory (10.2%).  It is possible in most instances to avoid complications by good pre-treatment patient evaluation, followed by careful treatment planning using all appropriate diagnostic aids. However in spite of good treatment planning, intra-operative and post-operative complications can result. It is thus important that the practitioner become familiar with the potential complications associated with implant placement and its subsequent restoration, and learn about the different management options. The purpose of this article is to review some of the complications associated with implant supported restorative treatment and to highlight some of these complications using case reports.

Implant supported restorative complications can be considered as: Pre-Operative Complications, Intra-Operative Complications, and Post-Operative Complications.

Patient examination and an accurate recording of the medical history presented by the patient are paramount for any dental procedure. However, when it comes to surgical procedures, especially those dealing with implant treatment, there is an added significance due to the positive long term treatment outcomes that are expected of implant supported restorative treatments. The 1996 Annals of Periodontology [3] had the statement that “there was no evidence in the literature to support any absolute contraindication for implant therapy”. However, they went on to add that there may be various levels of relative contraindications, which may decrease the predictability of implant supported restorative treatment. As practitioners dealing with implant placement and restoration, we recognize that not all patients are candidates for implant placement. Some of the listed systemic patient exclusion criteria include: insulin dependent/ uncontrolled diabetes, hemodialysis, collagen disorders, mentally incompetent, chronic and active hepatitis, immune-compromised disorders, leukemia, terminal illness, long-term steroid therapy, radiation therapy to potential implant sites, heart surgery within the last 6 months, and patients with a classification of ASA IV or V. While many of these exclusion criteria are obvious to the practitioner, they bear re-stating. In addition, there are several relative contradictions that are commonly ignored leading to ailing and failing outcomes. These include; uncontrolled systemic diseases, bleeding disorders, heavy smoking, patients of advanced age, patients still undergoing skeletal growth, post-irradiation, unstable psychological profiles and uncontrolled periodontal disease.

Implant placement in patients with periodontal disease has gained significant attention in the literature. The progression of periodontitis leads to tooth loss, and consequently many patients requesting implants to replace missing teeth are those with a history of periodontitis. Although the soft tissue attachment apparatus around an implant is different than that around a natural tooth, peri-implant soft tissues are similarly susceptible to invasion by bacteria that cause periodontitis.

Loss of bone combined with a soft tissue inflammatory lesion around a previously successfully integrated implant is considered a late implant failure termed “peri-implantitis.” [4] Several studies have shown that the composition of bacteria isolated from peri-implantitis lesions is similar to the putative pathogens present in chronic periodontitis. [5, 6]  Karoussis et al [7] reported that in individuals with a history of chronic periodontitis, the incidence of peri-implantitis was 4-5 times higher than in individuals with no history of periodontitis. In light of this research-based evidence, it is important that the patients’ periodontal condition is considered in the pre-treatment evaluation and the appropriate steps are taken to optimize the patient prior to implant placement.

Patient examination and assessment of the site or sites in which the implants are to be placed would then follow. A typical examination and data gathering would include [8]

1. Extra and intra-oral examination.
2. Evaluation of the patients’ periodontal condition, assessment of inflammation, width of attached gingiva.
3. Evaluation of mouth opening to account for length of the surgical drills along with the additional height needed to accommodate the surgical guide.
4. Evaluation of the patients’ occlusion and inter-occlusal space.
5. Diagnostic wax-ups as needed.
6. Radiographic examination consisting of intra-oral peri-apical radiographs and panoramic radiographs. The use of CBCT imaging has also become a routine imaging option and should be considered.

Once the data has been gathered and evaluated, an assessment of the length, width, number and the implant system used should be made. Most practitioners are familiar with one or two implant systems and accordingly, the decision on the implant system is usually pre-determined. Distance from the maxillary sinus, inferior alveolar nerve, mental nerve, nasal fossa, palpation of undercuts in bone should all be made and done prior to implant placement.

Intra-operative complications are primarily surgical. However, in some instances, they can also be associated with mechanical failure of the implant system. Commonly noted intra-operative complications include; hemorrhage, with associated petechiae, hematomas and bruising, nerve injuries [9, 10], cortical plate perforation, de-vitalization of adjacent teeth, sinus membrane complications, mandibular fracture, lack of primary stability [11]. Occasionally, intra-surgical complications involve the swallowing of smaller components of the implant system, such as cover screws or healing abutments. It was reported in a 10-year retrospective institutional study only 36 cases of ingestion were reported with one case of aspiration [12]. The practitioner that chooses to either place or restore implants, or both, should be well versed in managing these complications.

Several post-operative complications have been reported and do occur. Some of the more common post-operative complications include; infections, bleeding, cortical plate perforation, sinus perforation, de-vitalization of adjacent teeth [11], implant failure, esthetic failure, mandible fracture, implant fracture [8], and peri-implantitis [5, 6, 7]. Implant failures can be either “early” failures or “late” failures [4]. An early failure occurs within weeks to a few months after placement and is caused by factors that interfere with the normal healing process such as infection or an existing systemic disease. Late failures arise from a pathologic process that occurs around a previously integrated implant, such as peri-implantitis. It is imperative that the clinician realizes when an implant has failed in order to stop an on-going infection, or prevent an ensuing infection.