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tÉlÉcharger contemporary implant dentistry carl e.misch pdf

Chapter 20
Medical Evaluation of the Dental Implant
Carl E. Misch, Randolph R. Resnik
The medical evaluation of patients considering implant
therapy is an important aspect to consider for every patient. A retrospective analysis of Veterans’ Administration
Registry data found that the medical status of patients (i.e.,
medical history, American Society of Anesthesiologists
[ASA] category, and medication history) correlated with
implant failure.1 This chapter is specific for an implant
candidate and is developed in three sections. The first
section focuses on the importance of the patient interview, with primary emphasis on the medical history
questionnaire and the physical examination. The medical
history includes those medical conditions most likely
to influence implant treatment decisions. The physical
examination consists of a hands-on evaluation and
recording of the patient’s vital signs. The second section
(Laboratory Evaluation) reviews those laboratory tests
of interest to implant dentistry. The evaluation includes
a complete blood cell count (CBC), basic metabolic
panel (BMP), comprehensive metabolic panel (CMP),
or bleeding disorder tests. The third section relates the
medical and dental implications of the most common
systemic diseases found in implant patients.
The medical evaluation remains of paramount importance in implant dentistry, perhaps more so than in other
disciplines of dentistry.2 Implant treatment is primarily
a surgical, prosthetic, and maintenance discipline for
an older segment of the population. The need for
implant-related treatment increases with the age of the
patient; as a result, the implant dentist treats more elderly
patients than do other specialists in dentistry.3,4
An estimated 12% of the U.S. population is 65 years
of age or older; this number is expected to reach 21%
(64.6 million) in the year 2030.5 A 65-year-old person
has a life expectancy of another 16.7 years, and an
80-year-old person can expect to live an additional
8 years.6 These patients often request implant support
for their failing fixed restorations or to improve the conditions of their removable prostheses. An increased life
span means the number of elderly patients in the dental
practice is likely to increase. Therefore it is important
to design the medical and physical evaluations to
accommodate the special conditions of these patients.
Physiologic Changes in the Elderly
Physiologic changes associated with aging and their
pharmacologic counterparts modify the physical, social,
and economic life of the patient. Although important
individual variations exist, the biologic systems of the
elderly patient must cope with a decrease in function
and physiologic reserve. These physiologic changes may
predispose or increase the aging patient’s susceptibility
to disorders.
In general, a healthy older person demonstrates only
half the lung function of a healthy young adult. The
blood flow of an older patient is 80% that of the
healthy 30 year old, the cardiac output is only 70%,
the renal plasma flow is only 50%, and the glomerular
filtration is only 60%. A decrease in the elasticity of the
arterial system is illustrated by an increase in systolic
blood pressure. The vital capacity is reduced to 70% of
a 17-year-old patient and corresponds to a decrease in
the arterial partial pressure of oxygen.7 Gastric motility
and intestinal absorption are also decreased.
The total body weight of the patient is often reduced,
especially if masticatory deficiency from lack of teeth
and bone is present; however, there is an increase in
body fat. Consequently, any medications administered
will follow modified pharmacokinetics and dynamics.
Drug kinetics are modified, especially in the distribution
phase, as a result of the increased water weight,
decreased plasma albumin, and decreased cardiac
output. The decreased plasma albumin concentration
causes a greater percentage of the drug to remain free
and active. The decreased ability to metabolize drugs,
related to the decreased renal function, is responsible
for the decreased excretion of the drugs. Therefore the
intervals between drug administration should be longer
and dosages should be decreased, except for liposoluble
drugs and antibiotics, to compensate for the increase in
body fat and the reduced immune response.
The decreased gastric motility of the elderly patient
affects the use of oral analgesics such as codeine.
Pharmacodynamic alterations include an increased
sensitivity to central nervous system (CNS) depressant
drugs. The individual variations are greater than in
other segments of the population; the dosage should be
assessed for each patient.
Chronic illness and multiple disease states are
characteristics of aging. Patient surveys indicate that
80% of the elderly have at least one chronic disease.
Half of the people older than 65 years have arthritis,
42% have hypertension, 34% have other cardiovascular
problems, and more than 40% have hearing impairments. Other conditions associated with aging are
the increased frequency of diabetes (8.5%), immune
response problems, orthopedic (osteoporosis) problems
(17%), and sensory deficiencies as well as degenerative
diseases.8,9 The influence of chronic disease states doubles