Medical Contraindications to Implant Therapy: Part II: Relative Contraindications

Abstract

Systemic conditions and habits influence dental implant survival to varying degrees. Illnesses that impair the normal healing cascade worsen surgical success. The mere presence of a disease, however, does not necessarily preclude implant therapy or affect significantly long-term outcomes. Certain disorders, when controlled, or other situations allow implant survival rates that match those in health. This paper reviews these relative contraindications, which include adolescence, aging, osteoporosis, smoking, diabetes, positive interleukin-1 genotype, human immunodeficiency virus positivity, cardiovascular disease, and hypothyroidism.

Examination and Diagnosis

“…There are different studies, mainly retrospective ones, that deal with the impact of medical/systemic factors and/ or medications on the outcome osseointegrated implants, but the extrapolation of their results should be cautious, since it is not possible to collect much information from such studies if not much insight into the occurrence and nature of systemic disease is given [ 18,19 ]. Several authors have also identified diseases for which dental implants are not recommended, or are at least questionable, but it often remains unclear what type of evidence these statements are based on [20][21][22][23]. Therefore, it still remains a debated question whether some systemic factors/medications compromise the achievement of an intimate bone to implant interface and what their role is during the healing time [ 18,19 ].…”

“…A thorough and exhaustive medical examination will help not only to determine the specific measures that must be adopted for a medically compromised patient but also to carry out the estimation of the patient's risk. The system proposed by the ASA [ 16 ] to the dental patient is commonly used to define the patient's risk [ 23 ]. These classifications and the medical history allow the dentist to identify the systemic disease and the success rate expected in the medically compromised patient that is going to be rehabilitated with dental implants [ 2 ].…”

“…However, in a recent systematic review the authors were unable to find any strong evidence to either support or contradict the use of hyperbaric oxygen therapy for improving implant outcome, concluding that the use of hyperbaric treatment in patients undergoing implant treatment does not seem to provide significant benefits [ 48,49 ]. Radiotherapy could be responsible for the reduction in the success rate of dental implants when it is administered in doses exceeding 50 Gy, as has already been proven for extraoral implants [ 23 ]. An animal case-control study with irradiated maxilla and mandible (24-120 Gy) showed a decrease of implant stability quotient values long term in irradiated bone when compared with nonirradiated bone [ 50 ].…”

“…A diagnosis of osteoporosis is made when the bone mineral density level T is at least 2.5 standard deviations below that in the mean young population ( T ≤ 2.5 ) [ 69 ]. The major concern about osteoporosis with respect to implant placement is the possibility that the disease modifies bone quality, formation, or healing to an extent that osseointegration is compromised [ 23 ]. When evaluating whether dental implants in osteoporotic patients have a different longterm outcome, even though failure rates have been reportedly higher in animal models [ 70 ] and patients [ 71,72 ], a systematic review revealed no association between systemic bone mineral density (BMD) status, mandibular BMD status, bone quality, and implant loss, concluding that the use of dental implants in osteoporosis patients is not contraindicated [ 73 ].…”

“…Another study found no relation between osteoporosis and periimplantitis [ 74 ], and even patients with severe osteoporosis have been successfully rehabilitated with dental implant-supported prostheses [ 22 , 75 ]. The authors in a recent study concluded that taking into consideration the existing evidence, osteoporosis alone does not affect implant success [ 23 ]. A recent review, though, showed a weak association between osteoporosis and the risk of implant failure [ 3 ].…”