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There are many critical factors that are important to assess when evaluating a patient for implant reconstruction. Even before the actual clinical assessment is performed, the clinician should have a reasonable idea whether the patient is a candidate for a successful implant treatment outcome. The patient's ability to cooperate with treatment, and subsequent hygiene and maintenance requirements, should be of primary concern when evaluating a patient for dental implant and prosthetic reconstruction. A short‐term successful implant surgical outcome (osseointegration), while important, does not ensure long‐term success of implant rehabilitation if the patient does not possess the understanding, dexterity, and skills to perform ongoing implant maintenance. Additionally, an assessment of patient expectations is key in determining whether the patient is able to consider their own treatment a success, and also the ability to deal with failure and complications if, and when, they may occur.

Table 3.1. Co‐relationship between implant condition and clinical and radiographic findings

Implant condition	Clinical and radiographic examination
Success	No pain/tenderness upon functionNo mobility<2 mm of radiographic bone loss from initial surgeryNo exudate
Satisfactory state	No pain on functionNo mobility2–4 mm of radiographic bone loss from initial surgeryNo exudate
Compromised state	May have sensitivity on functionNo mobility>4 mm of radiographic bone loss from initial surgery or less than half length of an implantProbing depths >7 mmMay have exudate
Failure	Pain upon functionPresence of mobilityRadiographic bone loss less than half length of an implantPresence of continuous exudateNo longer present in the oral cavity

Table 3.2. Stages of implant failure

At implant placementBone overheatingImplant surface contaminationLack of primary implant stabilityInfectionEccentric loading

Delayed (1–2 years)Poor soft tissue healthLack of keratinized tissuePeri‐implantitisPoor oral hygieneSystemic issues (e.g., smoking)Excessive biomechanical loadsProsthodontic issuesImplant and component fractures

Late (>2 years)Progressive steady‐state bone lossPoor hygiene maintenanceProsthodontic issues

There have been a variety of systemic conditions described in the literature that traditionally have been accepted as risk factors for implant integration failure, and a number of studies cite specific conditions that are considered to be absolute or relative contraindications to dental implant placement. Typically, these comorbid conditions have included diabetes mellitus, osteoporosis, corticosteroid use, tobacco smoking, bisphosphonate use, chemotherapy, and head and neck radiation (Table 3.3). Recently, several outcome studies have alluded to the fact that each of these indeed may not be absolute, or even relative, contraindications, and that other factors, not generally included in this list, may be more significant contributors to implant failure. One study [1] analyzed data from 35 other studies that included implant failure rates in diabetics and smokers. The findings suggest that while smoking contributed significantly to implant failure, there was no effect for diabetes. However, a contradictory study reviewing 4680 implants [2] found that there was indeed a significant increase in implant failure in both the diabetic and smoker. Also, additional conditions related to an increased risk for implant failure include patient age greater than 60 years, head and neck radiation, and postmenopausal estrogen use. Conversely, gender, hypertension, coronary artery disease, pulmonary disease, steroid therapy, chemotherapy, and not receiving hormone replacement therapy (in postmenopausal women) were all not associated with an increased incidence of implant failure.

Table 3.3. Factors affecting implant success

Condition	Recommendations
Diabetes mellitus	Glycemic control (HBA1c < 8), antibiotic prophylaxis
Jaw irradiation	Consider dose and field, avoid implants, HBO prophylaxis
Smoking	Smoking cessation or nicotine holiday, avoid implants
Corticosteroids	Controversial, steroid holiday
Periodontal disease	Correct prior to implant, oral hygiene instructions
Advanced age	Accepted risk
Parafunctional habits	Address before implants, bite appliances, physical therapy, medicines (Botox)
Osteoporosis	Controversial
Bisphosphonates	Controversial, avoid implants with intravenous bisphosphonates, consider drug holiday

Although the literature supports the fact that there may not be any absolute contraindications to dental implant placement, the clinician must understand how certain local and systemic conditions may affect the successful integration of dental implants. This knowledge will assist with proper judgment with respect to treatment planning for patients with systemic diseases or disorders. For example, in the diabetic patient, decreased local tissue vascularity and compromised circulation of the recipient tissue bed due to microvascular abnormalities such as thickening of capillary basement membranes may contribute to impaired wound healing in general, and abnormalities in neutrophil chemotaxis and phagocytic activity may make the diabetic patient more susceptible, or less able to combat established infections [3]. In the case of metabolic bone diseases (e.g., osteoporosis, hyperparathyroidism, Paget's disease), the clinician must consider the potential for abnormal bone mineralization that is critical to the process of osseointegration.

In most instances, the literature does not distinguish the difference between implant failure and medical complications associated with implant placement [4]. However, the clinician should differentiate the possible conditions that may simply cause implant failure versus conditions that may directly cause harm to the patient. For example, a patient who has received jaw irradiation or has received a potent antiresorptive bisphosphonate (or other) medication may be at greater risk for osteoradionecrosis or medication‐related osteonecrosis of the jaws, respectively, as well as possible implant failure. While the literature is conflicting, most studies do indicate a higher implant failure rate in the irradiated patient, but no significant increased failure rate in patients who have had bisphosphonate medications. However, in these patients, “… the option of implant therapy should be chosen restrictively, and the patient should be informed specifically, taking into account the current level of uncertainty with regard to the consequences” [4].

In general, if a patient has the proper physical dexterity and mental competence to perform implant hygiene and maintenance after prosthetic restoration, has reasonable expectations, and can safely undergo the surgical procedure without undue risk on their physical well‐being, they are considered a candidate for implant reconstruction. The informed consent discussion should be tailored to each individual patient, taking care to identify issues that may result in an increased risk of implant failure, or impact upon medical or physical harm to the patient.