3: Evaluation and Selection of the Implant Patient

CHAPTER 3 Evaluation and Selection of the Implant Patient

PATIENT SCREENING AND MEDICAL EVALUATION FOR IMPLANT AND PREPROSTHETIC SURGERY

Implant and preprosthetic surgeries aim to restore normal anatomic contours, function, comfort, esthetics, and oral health. As such, they are not lifesaving procedures. The prime concern, therefore, must be not to undermine the patient’s overall health and safety. The practitioner should meticulously follow every step in selecting the appropriate treatment plan and maximizing the longevity of the implanted system, including the overlying prostheses.

One particularly important factor influences the possibility of subsequent complications: inadequate systemic screening of patients before implants and biomaterial are implanted. The general contraindications to implant procedures no longer can be limited to the traditionally considered malfunctions of the pancreas, liver, and hematopoietic system; the devastating long-term effects of smoking or inadequate dietary habits cannot be ignored. In fact, a number of systemic problems can pose major risk factors.

On the other hand, modern standards of care should not systematically exclude implant surgery in patients with relative or marginal health conditions; the possibility of improving and stabilizing those conditions must be explored. Newer techniques of general anesthesia and intravenous sedation are being used more frequently on an ambulatory basis, allowing implant surgeons to take their patients into various degrees of conscious or deep sedation. Patient screening, therefore, also should take into consideration factors related to this form of management.

An arbitrary guideline for patient selection may be based on the classification system of the American Society of Anesthesiologists (ASA) (this system is discussed in more detail later in the chapter). With very few exceptions, the ASA system restricts intraosseous implants and implant-related graft surgeries to patients who fall into categories ASA1 and ASA2, and those judiciously selected in category ASA3.

Practitioners should consider assigning patients age 65 or older to an ASA category one level higher than the person’s health factors would seem to indicate, depending on the individual’s medical, social, and familial history. For example, a 65-year-old patient has a complete medical evaluation with blood workup, and no underlying systemic disease or disorders are found; therefore, no interventional therapy is indicated, either with medication or a procedure. This individual, if younger than age 65, would be assigned to category ASA1. However, because the patient is 65, he should be assigned to category ASA2, because his metabolic rate has declined, and he does not metabolize medications as rapidly as a younger person. With regard to sedation, it is important to note that older patients (i.e., over age 65) also are more sensitive to sedative drugs and are more likely to develop postoperative delirium.

The body seems to respond much less dramatically to subperiosteal implants inserted for the treatment of advanced mandibular atrophy than it does to endosseous devices. By far, the cortical histoarchitecture and metabolism are less affected by organ disorders than are the deeper endosseous structures. However, when endosteal (osseous) devices are used in purely cortical bone, the prognosis is very poor. To improve the chances of success, extensive bone grafting is required from sites in the patient’s skeleton (i.e., the anterior iliac crest, calvarial spongiosa, and areas in the superior tibia). These procedures fall within the spectrum of significant, invasive surgery, therefore the surgeon must make it clear to the patient that the chances of success may be limited, and the complications are serious.

This chapter presents a number of absolute contraindications to implant procedures and analyzes a series of relative contraindications for which the dental surgeon’s judgment remains the decisive factor. In the latter case, the chapter proposes treatment patterns that could optimize certain marginal heath conditions or stabilize unbalanced biologic functions before or at the time of surgery. As life expectancy in the industrialized countries continues to rise, more and more elderly patients will have implant-supported prosthetics. For these patients, efforts must focus on keeping a regular and watchful eye on their general health and screening for possible geriatric conditions responsible for long-term implant failure.

With advances in technology and improvements in complicated implant devices, optimal knowledge of internal medicine must become a prerequisite for future academic implant education.

INTRODUCTION TO PATIENT SCREENING AND MEDICAL EVALUATION

Technically speaking, contemporary implant surgery is a relatively innocuous procedure. A stable, well-integrated implant is as “clean” as a healthy tooth. However, although the management of complications in patients with minor systemic disorders usually is straightforward and successful, this may not be the case with systemically compromised patients. For example, the dental surgeon should not devise a treatment plan for a patient who recently has undergone heart valve surgery without fully considering the gravity of possible immediate or delayed complications if unexpected problems arise. The implant may not be the only thing that becomes compromised.

Some patients with marginal health conditions also are, in addition, “oral invalids” and urgently need comprehensive dental treatment. In such cases, many implantologists are naturally inclined to give functional oral rehabilitation the same priority as treatment of the critical health condition; they do not readily consider deferral of the implant treatments. However, until such patients’ general health has stabilized, they should be provided with only provisional conventional prostheses that do not require surgery. After the patient has achieved a proper state of health, definitive implant surgery can be undertaken.

Implant dentistry has progressed amazingly during the past 20 years. Every aspect, whether scientific or clinical, is taught in academic institutions around the world with a discipline and demands equal to those of other types of surgical instruction. However, one vital element that has been underemphasized is the meticulous physical evaluation of patients before, during, and after implant treatment. This element is becoming increasingly important because, as mentioned previously, life expectancy in the industrialized nations is increasing, and a growing number of elderly patients will have implant-supported prostheses.

Most patient follow-ups are restricted to local oral evaluation of the implant sites, and these evaluations seldom extend beyond 10 years. The long-term implant complications that arise from impaired health often are neglected. A total of 25 years of clinical experience in implant and preprosthetic surgery has brought us into contact with a significant number of long-term complications (15 to 20 years after implant treatment) that developed completely independently of the oral environment. For this reason, efforts must focus on carefully following patients’ general health and screening for possible geriatric systemic conditions that might cause long-term implant failure.

As mentioned earlier, an arbitrary but practical method of patient selection may be based on the ASA’s classification system. This system defines limiting risk factors in five categories. Because both implant and preprosthetic procedures are elective surgery aimed at restoring function and comfort, they should be restricted primarily to patients categorized as ASA1 (patients with no health problems) or ASA2 (patients with minor health problems who respond well to treatment). Patients whose health conditions put them in category ASA3 (major health problems with partial correction) or higher (ASA4 [major health problems with hospitalization or institutional intervention] and ASA5 [near terminal or death]) should be screened carefully for any absolute or relative contraindications.

++++ + ++

++++ ++++ 0 +++ ++++ 0 ++ ++++ + +++ ++++ 0 + +++ + +++ ++++ 0 +++ ++++ + ++ ++ + ++ ++ +

The number of + relates to the degree of gravity of the complications associated with implant and graft surgery. One + is the least complicated (least predictable), and four ++++ is the most complicated (most predictable). Zero corresponds to total unpredictability.

The following lists presents discussions of the common systemic absolute contraindications. Dental surgeons must make it a top priority to understand these conditions thoroughly and to examine the patient methodically and carefully for them.

3. Coronary stents. The incidence of cardiac disease seems to be on the rise, and more and more patients are undergoing percutaneous coronary angioplasty, with or without placement of coronary stents, instead of open heart surgery. Symptomatic cardiac conditions no longer are the primary indication for interventional therapy. In the absence of symptoms, if patients have a significant family history of cardiac or coronary artery disease or a lifestyle that puts them at risk for such disease, early intervention is recommended, through lifestyle changes with or without medications. Coronary artery disease may be detected in these asymptomatic patients through a positive stress test result. In other cases, coronary artery disease is diagnosed in patients who seek treatment for acute coronary syndrome (unstable angina), which may result in urgent angioplasty and the placement of stents. Coronary stents also are placed when arterial occlusions are identified during an angiogram after an MI. These patients undergo aggressive antiplatelet therapy for at least 6 months and sometimes for an indefinite period. Therefore, no implant surgery should be planned for at least 6 months after placement of the stents, because the stress of surgery on the healing but damaged myocardium may compromise it further, resulting in a dysrhythmia during implant surgery. In addition, achieving proper hemostasis during and after dental surgery could be challenging and could result in significant loss of blood volume or the development of a hematoma, which may compromise the viability of the surgical area.

Fig. 3-1 illustrates daily calcium metabolism. The kidneys initially filter about 10 g of calcium a day into the primary urine.

7. Chronic or severe alcoholism. Chronic or severe alcoholism is a major health disorder that frequently leads to liver disorder, cirrhosis, and medullary aplasia. These in turn give rise to a cascade of possible complications, such as platelet diseases, distress infarction, aneurysm, and the risk of insidious hemorrhage. In patients with severe alcoholism, healing often is retarded, which is aggravated by malnutrition, psychological disorders, inadequate hygiene, and the risk of a major infection. For the purposes of implant surgeons, the most common tests for hepatic disorders measure the following:

Relative Contraindications

Systemic relative contraindications are related directly to the nature and severity of the systemic disorders and whether they can be corrected satisfactorily before surgery. The search for these contraindications requires meticulous screening of the patient’s medical records.

Patient selection with regard to relative contraindications is much more subtle, and among all the criteria, the dental practitioner’s judgment remains the critical factor. If the practitioner is not medically oriented, the patient may need to be referred to a specialist. If a disorder has been adequately corrected, the dental practitioner can carry out the treatment plan; otherwise, treatment should be postponed until optimal conditions prevail. Table 3-2 presents the possible effects of relative contraindications on the success of implant and bone graft surgery.

Table 3-2 Systemic Relative Contraindications to Implant Surgery and Their Impact on Predictability

Health Condition Risks for Patient’s General Health Long-Term Implant Predictability in Absence of Proper Diagnosis or Treatment Patient’s Possible Response to Medical Treatment Before Implant Surgery Long-Term Implant Predictability After Proper Diagnosis and Treatment

(1) ++++
(2) ++ 0
++ ++
++ 0
+++ +++ ++ ++ +++ +++ + ++ +++ +++ ++ ++ ++++ +++ 0 ++ +++ +++ 0 ++ +++ + 0 ++ +++ +++ 0 ++ +++ +++ 0 ++ +++ + + ++? +++ ++ + +++ +++ ++ + ++? +++ 0 + ++ ++ 0 ? ? ++ +++ + ++ +++

The number of + relates to the degree of gravity of the complications associated with implant and graft surgery. One + is the least complicated (least predictable), and four ++++ is the most complicated (most predictable). Zero corresponds to total unpredictability.

The following list presents common systemic relative contraindications to implant and preprosthetic procedures.

Modern chemotherapy uses a wide range of drugs, which belong to 10 to 12 pharmacologic families. Treatment for each patient may include a complex combination of these drugs. Table 3-3 shows the principal cancer treatments that may present absolute contraindications to an implant procedure during the time they are administered or for up to 6 months thereafter. Table 3-2 also shows a proportionately limited number of drugs that are incompatible with the simultaneous insertion of implant devices. The interpolating agents on the whole, seem to be devoid of adverse effects on implantology. The interferons and interleukins prescribed in advanced stages of pathology, however, are particularly contraindicated.

Table 3-3 Effects of Chemotherapeutic Drugs on Critical Metabolic Functions

Type of Anticancer Drug or Agent Drug Family Commercial Brand Principal Complications, Disorders, or Affected Organs
Antifolic Methotrexate Thrombopenia, osteogenesis
Nitrogen-mustards (III)
Nitrogen-urea (IV)
Mitomycin
Ifosfamide
Streptozocin
Ametycin
Blood, bone (osteogenesis)
Renal, hepatic, blood
Renal, hepatic, blood
Vinca alkaloids (III) Vincristine Renal, hepatic, blood
N/A N/A N/A
Bleomycin Bleomycin Pulmonary fibrosis
Plicamycin Mithramycin Renal, hepatic, blood
(Ca)++
  Progestates Medroxyprogesterone
Ethynodiol
Renal, hep/>

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Jan 5, 2015 | Posted by in Implantology | Comments Off on 3: Evaluation and Selection of the Implant Patient
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