Advances in dental implant therapy have created choices to enhance the expectations of dental practitioners and their patients with respect to oral rehabilitation at any age after childhood and regardless of, in most cases, medical disabilities. The medical status of the patient however can significantly influence the success rate of dental implant therapy. This article applies the hierarchy of scientific evidence ranging from case reports, retrospective, prospective cohort investigations, systematic reviews, and meta-analyses criteria in order to determine whether dental implant placement in medically compromised patients yields any detrimental sequelae.
Key points
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Dental implant therapy in medically complex patients is predicated on a well-thought-out surgical and restorative foundation that promotes both long-term function and improved health-related quality of life.
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Dental implant therapy in medically compromised patients involves a multiplicity of presurgical and postsurgical and pharmacologic considerations.
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There is no consensus as to whether medically complex patients’ risk for early or late implant failure exceeds those of healthy cohorts.
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There is no consensus as to whether dental implant therapy in immunocompromised patients results in an implant survival rate that is comparable with normal healthy cohorts.
Introduction
Advances in dental implant therapy have created choices to enhance the expectations of dental practitioners and their patients with respect to oral rehabilitation. The bioactivity of implant surface design, as well as the use of hard and soft tissue augmentation, provides a greater opportunity in the rehabilitation of the edentulous and partially edentulous jaw. Well-published studies of long-term dental implant success and survival provide more realistic options for restoration of function and esthetics regardless of postchildhood age, and, in most cases, medical disabilities. The 10-year implant survival is very high in the non–medically compromised patient population. However, dental implant placement, even in healthy patients, has the potential for adverse outcomes caused by failure of osseointegration or as a result of periimplantitis. Although the past few decades have provided an increased demand by patients for dental implants, failures in treatment are still prevalent because of poor patient selection.
With respect to medically complex patients, doctors must determine whether or not implants are the best option in the functional restoration of a partially or fully edentulous jaw. Controversy still remains with respect to systemic illness and its influence on short-term and long-term dental implant survival and success. Systemic morbidity caused by chronic illnesses can significantly compromise treatment planning outcomes. Studies by Scully and colleagues have examined how dental implant therapy can be altered by systemic illnesses in terms of success and survival over time. Vissink and colleagues crafted 6 questions, listed in Box 1 , to help practitioners determine whether dental implant therapy is a reasonable option in a medically compromised patient. Diz and colleagues and others have written in-depth reviews on implant survival and the risk of periimplantitis in patients with systemic illnesses. Many have recommended placing compromising medical conditions into groups of absolute versus relative contraindications when considering dental implant placement ( Box 2 ). Full disclosure of the proposed treatment plan and the potential complications and risks versus benefits is essential. This disclosure is the first step in developing a therapeutic alliance between practitioner and patient so that shared decision making can improve surgical outcomes.
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Does implant placement cause a health risk to the patient?
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Are specific precautions needed when placing the dental implants?
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Can immediate implant complications be controlled when they occur?
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Will an implant system be used and a surgical approach applied that has been proved to have favorable long-term outcomes with regard to implant survival and peri-implant health?
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Is there well-organized postoperative care and long-term follow-up?
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Is the patient compliant enough to adhere to strict oral care?
Absolute contraindications: recent myocardial infarction; stroke; organ transplant; valvular prosthetic heart valve; profound immunosuppression; severe bleeding dyscrasia; active malignancy; alcohol and drug abuse; psychiatric illnesses; osteoporosis; oral mucosal diseases; use of intravenous bisphosphonates or antiresorptive agents.
Relative contraindications: titanium allergy; smoking; immunotherapy.
This article applies the hierarchy of scientific evidence ranging from case reports, retrospective and prospective cohort investigations, systematic reviews, and meta-analyses that examine relative and absolute contraindications for the placement of dental implants in medically compromised patients. A review of the current literature is used to apply evidence-based criteria that determine whether dental implant placement in medically compromised patients yields significant increased risks of complications and implant failure. Attention is directed toward medically compromised patients who are immunocompromised, such as those with human immunodeficiency virus (HIV), diabetic patients, patients with autoimmune dysfunction, and patients who have been exposed to radiation therapy for malignancies. These systemic conditions are chosen to examine the most current scientific evidence addressing the controversies in dental implant placement in affected patients.
Literature search
A literature search was undertaken using Medline within the PubMed portal to choose articles within the last 20 years. Only articles in English were chosen for inclusion. Each article’s bibliography was evaluated for relevant publications and reviewed by the authors for inclusion. The keywords chosen include “patient assessment,” “medically complex patient selection for implants,” “medical contraindications for dental implants,” “immunocompromised patients and implants,” “diabetes and dental implants,” “hepatitis and dental implants,” “HIV and implants,” “radiation therapy and dental implant survival/success,” and “medical controversies and dental implants.” The level of evidence chosen was based on Sackett’s hierarchy of evidence and were predominantly levels 1A, 2A, 3A, 4, and 5 ( Table 1 ).
| Level of Evidence | Description |
|---|---|
| 1A | Systematic review/randomized trials (RCTs) |
| 1B | RCTs with narrow confidence limit |
| 1C | All or none case series |
| 2A | Systematic cohort |
| 2B | Cohort study/low-quality RCT |
| 3A | Systematic review of case-controlled studies |
| 3B | Case-controlled study |
| 4 | Case series/poor cohort case-controlled studies |
| 5 | Expert opinion |
Overview: medically compromised patients and dental implant therapy
Much debate has centered on whether dental implants are a preferred restorative solution in medically compromised patients who most often are candidates in need of complex restorative rehabilitation. The challenges faced include increased risk of periimplantitis, recurrence of mucosal disease, poor wound healing, and/or development of osteonecrosis caused by pharmacotherapy (ie, the use of certain drugs for osteoporosis/bone cancers), and patients who have been exposed to radiation therapy. Scully and colleagues suggested the risk/morbidity of dental implant placement should be predicated on careful patient work-up because new evidence supports successful implant survival in these patients. Kotsakis and colleagues, in a systematic review evaluating implant placement in the maxilla of medically compromised patients, concluded that implant survival is acceptable based on disease type and seems more predictable in the mandible than the maxilla. Vissink and colleagues, in a recent review, differentiated between absolute and relative contraindications for dental implant therapy (discussed earlier). Table 2 is an adaptation of these considerations with measures to improve the feasibility of dental implant placement in patients who are medically challenged. , The following medical conditions have provided much controversy with respect to long-term implant success and survival in several medically compromised patient populations seen in oral health care practices.
| Condition | (Relative) Contraindication | Implant Survival Rate | Precautions/Recommendations |
|---|---|---|---|
| Alcoholism | No | Similar | Assure that patients will keep adequate oral health maintenance. |
| Bleeding disorder | No | Similar | Check coagulation status before placement of implants. |
| Bone disease | |||
| Osteoporosis | No | Similar | Be aware of a slightly higher risk on MRONJ in patients on oral antiresorptive drugs. Bone augmentation surgery is allowed. |
| Bisphosphonate use | Yes | Similar/reduced | Antibiotic prophylaxis. Risk of MRONJ is high in patients treated for bone metastasis. When implants in latter patients are indicated, do it early after start of antiresorptive therapy. Also, no augmentation surgery in patients on i.v. administration unless early after start of usage. |
| Other antiresorptive drugs, for example, denosumab | Yes | Similar/ reduced | Antibiotic prophylaxis. Risk on MRONJ is high in patients treated for bone metastasis. When implants in latter patients are indicated, do it early after start of antiresoprtive therapy. Also, no augmentation surgery in patients on i.v. administration unless early after start of usage. |
| Cardiac Disease | No | Similar | Assure that patient will keep adequate oral health maintenance. Also with regard to control of cardiac disease. |
| Diabetes mellitus | |||
| Uncontrolled | No | Similar/ reduced | Antibiotic prophylaxis. Assure that patient will keep adequate oral health maintenance, also with regard to control of diabetes. |
| Controlled | No | Similar | Assure that patient will keep adequate oral health maintenance, also with regard to control of diabetes. |
| Drugs | |||
| Anticoagulants | No | Similar | See bleeding disorder. |
| Antiresorptive drugs | No | Similar/Reduced | See bone disease. |
| Biologicals | No | Similar | See Immunocompromised patients. |
| Chemotherapy | No | Similar | See head neck cancer. |
| Immunotherapy | Yes | Unknown | Implant treatment often can be postponed until end of therapy. |
| Xerostomic drugs | No | Similar | See hyposalivation. |
| Head and Neck Cancer | |||
| Chemotherapy | No | Similar | Assure that patient will keep adequate oral health maintenance during the course of chemotherapy. After completion, the risk of developing peri-implant health problems is comparable to healthy subjects. |
| Radiotherapy | Yes | Reduced | Preferably place dental implants during ablative surgery. When placed after completion of radiotherapy, implant should be placed under antibiotic coverage (e.g., amoxicillin 500 mg t.i.d. for 2 weeks, starting 1 day before placement of the implants). If cumulative radiation dose in the implant area is >40 Gy, it is recommended to apply hyperbaric oxygen therapy pre- and post-implant placement. |
| Hypersalivation | No | Similar | |
| Hyposalivation | No | Similar | Higher risk of per-implant health problems, assure that patient will keep adequate oral health maintenance. |
| Immunocompromised patients | |||
| Biologicals | No | Similar | Discuss with physician whether administration of biologicals has to be adjusted or specific precautions are needed. |
| Crohn’s disease | No | Similar/Reduced | Antibiotic prophylaxis. Older studies mention that implant survival is decreased compared to controls. Recent studies indicate that survival is similar. |
| Mixed connective | No | Similar | Antibiotic prophylaxis. Higher risk of per-implant health problems, Antibiotic prophylaxis. |
| Tissue disease | |||
| Rheumatoid arthritis | No | Similar | Higher risk of peri-implant health problems, assure that patient will keep adequate oral health maintenance. |
| Scleroderma | No | Similar | Antibiotic prophylaxis. Higher risk of peri-implant health problems, assure that patient will keep adequate oral health maintenance. |
| Sjögren’s syndrome | No | Similar | Antibiotic prophylaxis. Higher risk of per-implant health problems, assure that patient will keep adequate oral health maintenance. |
| Systemic lupus erythematosus | No | Similar | Antibiotic prophylaxis. Higher risk of per-implant health problems, assure that patient will keep adequate oral health maintenance. |
| Mucosal disease | |||
| Epidermolysis bullosa | No | Similar | Antibiotic prophylaxis. Careful treatment if oral mucosa. Slightly higher risk of peri-implant health problems. Assure that patient will keep adequate oral health maintenance. |
| Lichen planus | No | Similar | Antibiotic prophylaxis. Slightly higher risk of peri-implant health problems. Assure that patient will keep adequate oral health maintenance. Place implants when mucosal disease is in control. |
| Others (Crohn, SLE) | No | Similar | Antibiotic prophylaxis. Slightly higher risk of peri-implant health problems. Assure that patient will keep adequate oral health maintenance. Place implants when mucosal disease is in control. |
| Pemphigoid | No | Similar | Antibiotic prophylaxis. Slightly higher risk of peri-implant health problems. Assure that patient will keep adequate oral health maintenance. Place implants when mucosal disease is in control. |
| Pemphigus | No | Similar | Antibiotic prophylaxis. Slightly higher risk of peri-implant health problems. Assure that patient will keep adequate oral health maintenance. Place implants when mucosal disease is in control. |
| Smoking | Yes | Similar/Reduced | Implant survival is reduced, in particular for the maxilla, in heavy smokers. Increased risk of per-implantitis. |
| Titanium allergy | Yes | Reduced | Use alternative implant material, for example, zirconium. |
Immunocompromised Patients
Human immunodeficiency virus
Thirty-three million people have been living with HIV for several decades and millions have died of acquired immunodeficiency syndrome (AIDS). , Within the past decade, the growth rate of HIV infection seems to be plateauing (discussed later). The virus attacks the immune system and causes a reduction in host resistance because of decreased CD4+ T cells that can compromise the normal oral flora. This condition is a concern, especially because there is an increased risk of complications in the oral cavity as a result of oral surgical procedures in patients with HIV. The development of antiretroviral therapy has saved millions of lives and improved the health-related quality of life of many patients with oral health care concerns. However, advances of antiretroviral therapy have led to adverse events in terms of bone disorders (ie, osteoporosis and osteopenia) because the virus affects osteoblast and osteoclast function. As such, the flora of the mouth in concert with immunosuppression can impede long-term success and survival of dental implants. , More recent data since the introduction of highly active antiretroviral therapy (HAART) have recharacterized HIV/AIDS as a chronic disease and improved the ability of patients with HIV to become immunologically resistant and, in many cases (discussed later) have viable choices for oral rehabilitation with dental implants.
Although no consensus has been reached on recommendations for dental implant therapy in patients with HIV, numerous studies and systematic reviews have attempted to determine whether implants are suitable in the dental rehabilitation of HIV-positive patients. , , , , Scully and colleagues suggested that immunologically stable HIV-positive patients may be considered as viable candidates to receive implants. A retrospective chart review by Rubenstein and colleagues considered the placement of dental implants in HIV-positive patients to be successful and safe with several caveats. They did suggest that low bone mineral density as a result of HAART therapy can lead to increased risk of bone fracture and osteoporosis. Most of the patients in the study were more than 50 years of age, positive for tobacco use, and had low body mass. However, HIV-positive patients who were highly compliant with their oral health care showed an absence of periimplantitis and an increase in the survival of dental implants that were placed. Implants were considered successful in this cohort because of lack of mobility and no fixtures showed signs of infection. Although there were study limitations, such as the small sampling size analyzed, the investigators recommended patient follow-up on a regular basis to measure both changes in crestal bone height and hygiene maintenance as indicators for long-term success of implants placed.
A systematic review by Lemos and colleagues examined the survival and success of dental implants placed in HIV-positive patients. The risk predictors examined were marginal bone loss and complications (ie, periimplantitis, mucositis, and prosthetic failure over a period of 48 months). Three of the studies in the systematic review found no significant differences between HIV-positive and non-HIV study cohorts in terms of implant survival rate. , , Significant factors common to these results include HAART therapy, which increases the number of CD4+ T cells. The mean CD4+ T-cell count was greater than 400 cells/mm 3 with a failure rate at less than 200 cells/mm 3 when 2 cohorts for implant placement were compared. , The other 3 studies of systematic analyses showed no significant difference with respect to CD4+ T cells and implant survival. Another contributory factor for failure seemed to be the lack of prophylactic and postoperative antibiotic medications given. , , Antibiotic prophylaxis is recommended, especially for their effect on inflammatory cascades seen in HIV-positive patients, which have the potential to reduce the CD4+ T-cell counts after implants are placed. ,
As stated earlier, other complications most often of concern in the HIV-immunocompromised population are (1) bone loss caused by disorders as a result of viral medications/bone metabolic disorders, and (2) periimplantitis. Marginal bone loss, another valid risk predictor for implant success and survival, was measured in these reviews because HAART has the potential to reduce mineral bone density. , In the HIV-positive population, the most frequent bone metabolic disorders were related to bone demineralization as a result of osteoporosis/osteopenia with a prevalence rate of 48% and 23%, respectively. , , Oliveira and colleagues suggested that HAART did not significantly cause marginal bone loss. Ata-Ali and colleagues in their systematic review suggest that bone disturbances may be caused by a combination of factors such as low body weight, suboptimum calcium and vitamin D intake, smoking, alcohol, HIV itself, and HAART. The stimulation of osteoclast and osteoblast activity may be a result of increased production of proinflammatory cytokines secondary to chronic T-cell activation. , All of the systematic review studies discussed earlier support long-term follow-up over a period of greater than 1 year in order to verify the clinical stability of bone morphology in HIV-positive patients. , , ,
Periimplantitis in HIV-positive patients is the most frequently characterized dental implant complication in all systematic reviews examined. , , , Although implant loss was most frequently the result of infection leading to periimplantitis, the periimplant sequela was not caused by immunosuppression but by preexisting periodontal disease. The latter was most often a result of failure to comply with periodontal maintenance. , , Several systematic reviews support this finding. , , Other risk predictors include tobacco (>10 cigarettes/d) and alcohol use. , Gherlone and colleagues evaluated the rate of periimplantitis in prosthetic rehabilitation of HIV-positive patients using a prospective longitudinal study. At the 1-year postoperative follow-up, most fixtures placed had good osseointegration and stability and no infection, whereas, in 15 out of 190 implants placed, failures were the result of periimplantitis and concomitant prosthetic dysfunction. However, there were several limitations to this study, such as lack of consistency in the recording of tobacco use, CD4+ T-cell numbers, and oral hygiene. The investigators concluded that a higher incidence of periimplantitis is likely in the first 6 months after implant therapy and, as such, suggest a need to develop a protocol for strict recall appointments and infection control. This finding is supported by other studies. , ,
The results presented earlier suggest that HIV infection may or may not have an impact on dental implant osseointegration over time. Prophylactic antibiotic treatment, HAART therapy, monitoring of CD4+ T-cell counts, and judicious recall for hygiene maintenance seem to be reliable mitigating risk predictors for success. Future prospective studies are still needed in larger sample sizes with longer follow-up in order to develop a consensus statement when considering HIV positivity to not be a relative or absolute contraindication to dental implant therapy.
Diabetes mellitus
Hyperglycemia (blood glucose level >140 mg/dL) is a frequent condition with a prevalence of 20% to 40% in the general surgery and dental populations. During the perioperative period, it can serve as an independent marker of poor surgical outcomes. Patients with diabetes mellitus, whether type 1 or type 2, are at an increased risk of intraoperative and postoperative morbidity caused by hyperglycemia. It is well known that diabetic patients have an increased frequency of periodontitis and tooth loss, as well as delayed wound healing and increase in infections. Infections result in compromised wound healing caused by endothelial dysfunction, platelet activation, and synthesis of proinflammatory cytokines, which inhibit fibrinolysis and result in subsequent coronary vessel occlusion with myocardial impairment. Chronic hyperglycemia, a potential consequence of surgical stress, can result in significant microvascular and macrovascular disease, such as diabetic neuropathy, retinopathy, cerebrovascular disease, and peripheral vascular disease.
Although there are no prospective randomized trials in relation to blood glucose control during the perioperative period, several laboratory risk predictors can help in perioperative care, such as glycosylated hemoglobin A1c (HbA1c), which is a well-validated variable to monitor the long-term control of diabetes mellitus. In 2018, the American Diabetes Association (ADA) guidelines were updated to reflect limitations in HbA1c measurements caused by hemoglobin variants, ethnicity, age, and altered red blood cell turnover. They have recommended the use of a new term, estimated average glucose (eAG), which expresses the HbA1c in the same units (mg/dL or mmol/L) as the average glucose levels self-monitored by the patients ( Table 3 ).
