Dental implant therapy is generally successful. However, when such therapy fails, considerations for implant replacement must be carefully considered. The survivability of implants placed into previously implanted sites must be considered. Appraisal of early implant loss versus late implant loss is important in presurgical planning for implant replacement. This review highlights the factors that can impact the success of implant reimplantation.
Key points
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A comprehensive understanding of the indications for, risks associated with, and long-term outcomes of implant reimplantation is critical for surgeons.
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There are few evidence-based guidelines regarding the management of explanted sites and protocols for reimplantation.
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Key factors to assess when determining whether or not to perform implant reimplantation include evaluating presurgical conditions, reasons for initial implant failure, and factors leading to long-term reimplantation success.
Introduction
In the modern era, dental implants are now considered to be a gold standard treatment of edentulism with success rates of 95% to 97%. While implants are largely advantageous, many factors influence their success. Despite advances in technology and surgical techniques, complications following implant placement still exist. When implant failures occur, clinicians must design a new plan to replace the failed implant. It is important for the clinician to optimize the preoperative, intraoperative, and postoperative phases of care. A significant amount of research has been conducted pertaining to placing implants into sites of previously failed implants (termed “reimplantation”). While many factors can influence reimplantation success, studies have shown that the failure of reimplantation is more adversely affected by patient factors over implant factors. Reimplantation into sites previously with implants has been studied relatively well. In this clinical review, the authors discuss reimplantation and highlight clinical considerations when placing implants into previously failed sites. This article will serve as a useful tool to guide surgeons as they decide how to best treat ailing implants.
Diagnosis of ailing implants
Defining Implant Failure
The historic definition of implant failure developed in 1998 involved the following criteria :
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Greater than 1.0 mm of bone loss around the implant in the first year and greater than 0.2 mm per year after
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Lack of osseointegration
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Mobility or dislodgement of the implant
Major advancements and ongoing rapid progress in dental implantology have motivated participants of the International Congress of Oral Implantologists Consensus Conference to update the traditional definitions of dental implant success, survival, and failure as well as establish a quality health scale for dental implants. The group proposed categorizing implants into 4 clinical scenarios:
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Implant success (no pain, no mobility, no exudate, less than 2 mm of radiographic bone loss);
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Satisfactory survival (no pain, no mobility, no exudate, 2–4 mm of radiographic bone loss);
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Compromised survival (no mobility, radiographic bone loss of more than 4 mm [less than half the length of the implant body], probing depth of greater than 7 mm);
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Failure (pain in function, mobility, radiographic bone loss of more than half the length of implant body, uncontrolled exudate).
This consensus group recommended the removal of any implants manifesting conditions listed under implant “failure.” However, as discussed in the subsequent section, with significant improvements in managing peri-implant disease, the decision to extract or treat a nonmobilecompromised implant has become a challenging decision. Furthermore, improper prosthetic rehabilitation (eg, a loose crown) could manifest as pain in function and may not necessitate implant removal. In the early stages of implant failure (eg, an “ailing” implant), the implant is losing bone and showing signs of peri-implantitis, but it is not yet mobile. Once an implant is mobile, it is considered to have failed and must be explanted. Nevertheless, failed implants can go clinically unnoticed when the implant is part of a multi-unit splinted prosthesis. In such scenarios, radiographic examinations coupled with probing depth measurements are critical. ,
Reasons for implant failure
While implant failure is a relatively uncommon phenomenon, many factors can contribute to the timely osseointegration of dental implants, or lack thereof. Implant failures can be divided into early and late failures depending on when clinical mobility and lack of osseointegration manifest.
Studies have shown that patient factors are more likely to cause implant failure than structural implant failures. There remains relative and absolute contraindications to implant placement ( Table 1 ). The absolute contraindications can include osteoradionecrosis, neoplasm, and medication-related osteonecrosis. Relative contraindications include uncontrolled diabetes, periodontal disease, bruxism, osteoporosis, and hospice care ( Table 2 ).
| Preoperative Considerations | Implant Failure | Peri-Implantitis |
|---|---|---|
| Tobacco | Increase | Increase |
| Diabetes | None | Increase |
| Radiation | Increase | Increase |
| Macronutrients | Function | Oral Cavity Effect |
|---|---|---|
| Vitamin A | Soft tissue formation | Decreased epithelial tissue formation |
| Vitamin B | DNA repair, DNA maintenance, collage synthesis | B2, B3, B12—Gingivitis B2—impaired wound healing and oral cavity inflammation |
| Vitamin C | Collagen synthesis, antioxidant | Gingivitis, impaired wound healing |
| Vitamin D | Maturation of osteoblasts and osteoclasts, bone formation | Poor bone formation |
| Iron | Hemoglobin synthesis, oxygen transport | Salivary dysfunction, glossitis, angular cheilitis |
It is essential to analyze the factors leading to implant failure as the presence of these factors during reimplantation will likely lead to a higher rate of failure (see Table 1 ). Many of these key factors are discussed in later studies and will only be discussed briefly here. Key presurgical considerations include the following
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Smokers have a 140.2% higher chance of implant failure than nonsmokers. An increase in smoking was found to be directly correlated with an increase in implant failure—patients who smoked more than 10 cigarettes a day had higher failure rates than patients who smoked less than 10 cigarettes a day.
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Some studies conclude diabetes is associated with a greater risk of peri-implantitis associated with peri-implant mucositis. Shang and Gao showed that there was an increased peri-implant bone loss and peri-implantitis; however, there was no significant difference in the rates of implant failure between diabetic and nondiabetic patients which was reportedly due to implant failure patients in the diabetic group failing to return for follow-up.
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Prospective cohort studies show that malnourished surgical patients have worse clinical outcomes, greater odds of complications, and increased health care costs. There are multiple objective measures of nutrition which take into account body mass index, weight loss, food intake, albumin levels, and vitamin D levels ( Table 3 ).
Table 3Absolute and relative contraindications to implant placementAbsolute Contraindications Relative Contraindications Osteoradionecrosis
Neoplasm
Medication-related osteonecrosisUncontrolled diabetes
Smoking
Periodontal disease
Bruxism
Osteoporosis
Hospice case/short expected life span - •
Radiation can directly damage osteoclasts and decrease the proliferation of bone marrow, collagen, and blood vessels. Granstrom and colleagues showed that some consequences of radiation involve reduced osseointegration for implants placed into irradiated jaws.
Early failure
Early implant failure is defined as an implant showing clinical mobility before the placement of the final prosthesis and has been reported to be twice as common as late implant failure ( Figs. 1 and 2 ) . Various factors contributing to early implant failure include those related to smoking, infection, lack of primary stability, uncontrolled diabetes, osteoporosis, corticosteroids, bisphosphonates, and poor bone quantity as well as quality. Furthermore, a lack of prophylactic antibiotic therapy has been reported to be associated with implant failure. In patients who received prophylactic antibiotic therapy, 48 of 1037 implants failed (4.6%). On the other hand, in the group who did not receive prophylactic antibiotic therapy, 25 of 56 (44.6%) implants failed. , Age is another factor as Moy and colleagues showed that older age was associated with early implant failure. Implant diameters are important because narrow implants showed a high risk of early failure in a study by Yari and colleagues Furthermore, tapered implants had similar failure rates to cylindrical implants.
Late failure
In contrast, late implant failure occurs after the implant has been restored ( Fig. 3 ). Causes of late failure include excessive loading, peri-implantitis, and inadequate prosthetic construction. Implant overloading was a common risk for late implant failure. Failures secondary to overloading can be related to improper abutment connection or occlusion of the prosthesis resulting in unfavorable loads. Additionally, radiation therapy increases the rate of late implant failure. Poor bone quality such as type IV bone increases the rate of late implant failure and is associated with low primary stability. , Finally, conus-type connections, a specific type of low-profile connection, were also reported to have a risk for late failure.
