9: Systemic Factors Influencing Periodontal Diseases

Systemic Factors Influencing Periodontal Diseases

Gary C. Armitage

Systemic factors can have a profound effect on the diagnosis, pathogenesis, and treatment of periodontal infections. Some systemic diseases have signs and symptoms that mimic those of plaque-induced gingivitis or periodontitis, thereby increasing the likelihood of a misdiagnosis. Systemic problems in some patients can result in the following:

In many cases, medical treatment of systemic diseases affects the clinical presentation and course of periodontal infections. People are now living longer than ever before. As a result, the patient population in a typical dental practice includes an increasing number of individuals with complex systemic problems, many of which are being treated with a wide variety of medications. The knowledgeable clinician must understand how the patient’s systemic problems influence the selection of periodontal treatment and the anticipated response to therapy. This chapter provides an introduction to this subject and reviews some common systemic conditions encountered in dental hygiene and dental practice.

Cardiovascular Diseases

In the United States, more than 40 million people have some form of cardiovascular disease. In this group of diseases, the most common conditions include hypertension (high blood pressure), coronary artery disease, heart valve disease, cardiac arrhythmias, and congestive heart failure. Because cardiovascular diseases are so prevalent in the population, many patients who seek dental care will have these conditions. In general, dental and periodontal treatment is not contraindicated in most patients with cardiovascular disease. In many cases, it is advisable to obtain a written medical consultation from the patient’s physician before treatment is initiated. It is important to include a summary of which type of dental or periodontal treatment is planned. This information is useful to the physician in deciding whether any special precautions are required for the anticipated dental treatment. When dentists or dental hygienists request medical consultations, it is their responsibility to have a reasonable idea of which pretreatment precautions might be necessary.

Hypertension (High Blood Pressure)

High blood pressure is a major risk factor for cardiovascular disease, stroke, and kidney failure. Tens of millions of people in the United States have high blood pressure or are taking antihypertensive medications.1 Hypertension has been called the “silent killer” because it is frequently asymptomatic and more than half of patients with hypertension are unaware that they have it. The prevalence of the disease increases dramatically with age,2 and variations also occur by gender and race.3 Blood pressure is the force of the blood pushing against the walls of arteries. It is highest when the heart beats (systolic pressure) and lowest when the heart is resting (diastolic pressure). Blood pressure is recorded as two numbers, the systolic over the diastolic pressure (e.g., 110/70 mm Hg).4 In general, patients with readings greater than 140/90 mm Hg are considered to be hypertensive.5,6 Patients with a systolic pressure from 120 to 139 mm Hg and a diastolic pressure from 80 to 89 mm Hg are considered to have prehypertension.4 Table 9-1 shows a classification of hypertension from the Joint National Committee on the Detection, Evaluation, and Treatment of High Blood Pressure.5


Classification of Adult Blood Pressure and Dental Treatment Modifications

Normal <120 <80 No modification of dental care
Prehypertension 120-139 80-89 No modification of dental care
Stage I 140-159 90-99 No modification of dental care, medical referral, inform patient
Stage II 160-179 100-109 Selective dental care,* medical referral
Stage III 180-209 110-119 Emergency nonstressful procedures, immediate medical referral/consultation
Stage IV ≥210 ≥120 Emergency nonstressful procedures, immediate medical referral


See: http://www.nhlbi.nih.gov/.

*Selective dental care may include, but is not limited to, dental prophylaxis, nonsurgical periodontal therapy, restorative procedures, and nonsurgical endodontic therapy.

Emergency nonstressful procedures may include, but are not limited to, dental procedures that may help alleviate pain, infection, or masticatory dysfunction. These procedures should have limited physiologic and psychological effects. An example of an emergency nonstressful procedure might be a simple incision and drainage of an intraoral fluctuant dental abscess. The medical benefits achieved by performing emergency nonstressful procedures in stages III and IV hypertensive patients should outweigh the risk of complications caused by the patient’s hypertensive state.

Used with permission. Modified from Muzyka BC, Glick M. The hypertensive dental patient. J Am Dent Assoc. 1997;128:1109–1120.6 Copyright 1997, American Dental Association.)

Dental hygienists play an important role in detecting previously undiagnosed and asymptomatic cases of hypertension. Adult dental patients should have their blood pressure measured at each visit. When elevated blood pressure is detected, patients should be advised to see their physician. In individuals with uncontrolled hypertension, elective dental treatment should be deferred because stress associated with dental procedures can further elevate blood pressure and thereby increase the risk of stroke and assorted cardiovascular or renal problems. However, patients with medically well-controlled hypertension can safely receive nearly all forms of dental and periodontal therapy.

The use of epinephrine-containing local anesthetics is not contraindicated in patients with well-controlled hypertension. However, it is advisable to use minimal amounts of epinephrine, such as 0.04 mg per dental visit (approximately two cartridges containing 1 : 1000,000 parts epinephrine). If pain is anticipated in association with the planned dental or periodontal treatment, very good local anesthesia is desirable to minimize the release of endogenous epinephrine.7,8

Physicians prescribe many types of medications for hypertensive patients, including diuretics (e.g., thiazides), sympatholytics (e.g., beta-adrenergic blockers such as propranolol), vasodilators (e.g., hydralazine HCl), and angiotensin-converting enzyme inhibitors (e.g., enalapril). As with all patients who are taking medication, it is important for the dental hygienist to review the list of drugs taken by the patient and become familiar with their mode of action and potential side effects. Some of the side effects of these medications are drowsiness, mental depression, confusion, and xerostomia (dry mouth).

Coronary Artery (Ischemic Heart) Disease

Atherosclerosis is the deposition of cholesterol-containing material in the walls of arteries that results in a narrowing of the affected blood vessels. This can eventually lead to the complete blocking of blood flow. Ischemia is the insufficient supply of blood to an organ or tissue. Atherosclerotic changes in the coronary arteries that feed the heart can lead to ischemic heart disease, the leading cause of sudden death in the United States. The two most common clinical manifestations of ischemic heart disease are angina pectoris and myocardial infarction, commonly referred to as a heart attack.

Angina pectoris is a severe recurring chest pain that frequently radiates into the left shoulder and arm. It is an intense crushing pain that can also move across the chest and down each arm. Sometimes the pain involves the neck, lower jaw, and face. It is caused by the deprivation of oxygen to the cardiac muscle as a result of reduced blood flow, frequently as a consequence of atherosclerotic narrowing of the coronary arteries. However, it also can be caused by specific situations in which the oxygen demands of the heart muscle are not met, such as strenuous physical exertion or extreme psychological stress.

A condition in which anginal pain is predictable and controlled by medication is called stable angina.9 Patients with stable angina frequently control their anginal pain by taking one or more of the following types of drugs: nitrates (e.g., nitroglycerin), beta-adrenergic blockers, and calcium channel blockers (e.g., nifedipine). Gingival enlargement is one of the common side effects of nifedipine (Procardia) and some other calcium channel blockers.1014 The gingival enlargement can make oral hygiene difficult and thereby increase the risk of plaque-induced diseases, such as dental caries and periodontal disease, (Figure 9-1).

Patients with stable angina can safely receive routine dental care, but it is advisable to minimize stress by scheduling relatively short morning appointments so that the patient is well rested. As with hypertensive patients, local anesthesia should be used for potentially painful procedures to minimize the release of endogenous epinephrine.7,8 If an anginal attack occurs during the delivery of dental care, treatment should be discontinued, the patient should be placed in a semisupine position, and standard emergency procedures should be performed.

Myocardial infarction, or heart attack, is caused by sudden occlusion or blocking of the blood supply to a portion of the heart. Heart attacks are frequently caused by occlusion of a coronary artery by atherosclerotic deposits or a blood clot (thrombus). Patients who are recovering from a recent heart attack should not receive elective dental treatment until their condition is medically stabilized, usually for 6 months or until treatment is approved by their physician.

Diseases of Heart Valves

Any dental or periodontal procedure that introduces bacteria into the bloodstream of patients with heart valve disease can increase their risk of a potentially fatal heart infection called infective endocarditis. In general, damaged heart valves are more susceptible to colonization by bacteria. In addition, the stasis of blood, frequently associated with defective heart valves, increases the likelihood that bacteria will be able to attach successfully to fibrin deposits that can form on the heart at sites at which blood flow is impaired. In the past, some patients with heart valve problems were prescribed antibiotics before undergoing any procedures in which gingival bleeding might be induced, including periodontal examination and scaling of the teeth. It was believed that the antibiotics lowered the risk of developing infective endocarditis. However, this is no longer routinely recommended because the risks of taking antibiotics often outweigh the risk of developing infective endocarditis.15

It is important for dental hygienists to have a basic understanding of the general types of diseases that affect heart valves so they can more effectively consult physicians about any pretreatment precautions that should be taken for high-risk patients.

The primary function of heart valves is to allow the unidirectional forward flow of blood through the heart. Diseases of the heart valves can be either acquired or congenital. Acquired diseases are far more common. Approximately half of all acquired heart valve lesions occur as isolated stenosis, or narrowing, of the orifice of the aortic or mitral valve. Stenosis leads to the failure of a valve to open completely, thereby retarding the forward flow of blood through the heart. Heart valve insufficiency is the failure of a valve to close completely, thereby leading to regurgitation, or flow of blood in a reverse direction. Stenosis and insufficiency often affect the same valve.

Many methods are used by physicians to detect heart disease. One of them is to listen to heart sounds with a stethoscope to detect, among other things, the presence or absence of a heart murmur. Murmurs are simply the sounds that are produced by the turbulent flow of blood through the heart. Heart valve disease is only one of many possible causes of a heart murmur. Some murmurs are caused by abnormalities of the heart (organic murmurs); others are termed innocent or functional murmurs. When patients report that they have a heart murmur, it is usually advisable to consult their physician to determine whether any precautions are necessary before dental procedures are performed. Patients with heart murmurs rarely require preoperative coverage with antibiotics, although this was common in the past.

Acquired heart valve disease is often found in patients with a history of rheumatic fever16 and several other systemic diseases.1719 Rheumatic fever is an acute systemic inflammatory disease that sometimes follows throat infections with group A streptococci. Antistreptococcal antibodies that form in response to these infections can react with heart valve tissues and cause inflammation and damage to the valves. This damage may lead to rheumatic heart disease in which there is scarring of the heart valves. In the past, a history of rheumatic heart disease was one of the conditions for which antibiotics were routinely prescribed in an attempt to reduce the risk of infective endocarditis. Other conditions for which preoperative antibiotics are no longer recommended include mitral valve prolapse, bicuspid valve disease, calcified aortic stenosis, and some congenital heart conditions such as ventricular or atrial septal defects.15 The American Heart Association (AHA) has published guidelines on when antibiotic prophylaxis for dental procedures are recommended (Table 9-2).15 However, before performing dental procedures (including oral examinations with periodontal probing or exploring) in a patient with a history of heart valve problems, the clinician should consult the patient’s physician to determine whether preoperative coverage with antibiotics is necessary.

TABLE 9-2 AHA Recommendations of Prophylactic Antibiotic Coverage for Dental Procedures in Patients at High and Moderate Risk for Infective EndocarditisRights were not granted to include this table in electronic media. Please refer to the printed book. Used with permission from Dajani AS, Taubert KA, Wilson W, et al. Prevention of bacterial endocarditis: recommendations by the American Heart Association. J Am Dent Assoc. 1997;128(28):1142–1151.20; and Hancock EW. Coronary artery disease: epidemiology and prevention. In: Rubenstein E, Federman DD, eds. Scientific American Medicine. New York, NY: Scientific American; 1991:1(section VIII):1–10. Copyright American Dental Association. Excerpted by JADA with permission of The Journal of the American Medical Association. JAMA. 1997;277(22):1794–1801; Copyright 1997 American Medical Association. Adapted 2006 with permission of the American Dental Association.) American Heart Association

Cardiac Arrhythmias

Irregular heartbeat can be associated with a variety of systemic conditions, such as high fevers from certain infectious diseases, ischemic heart disease, congestive heart failure, mitral valve prolapse, rheumatic heart disease, myocardial infarction, hypertension, certain allergic reactions (anaphylaxis), and hyperthyroidism. There are many forms of cardiac arrhythmia, some of which can be controlled by medications. Others require the insertion of electronic devices (e.g., pacemakers and defibrillators).

Dental procedures can be safely performed in most patients who are under medical treatment for cardiac arrhythmias. However, patients who are taking antiarrhythmic drugs can experience a variety of side effects that may complicate or worsen their dental and periodontal problems. For example, some antiarrhythmic drugs, such as disopyramide (Norpace), mexiletine (Mexitil), verapamil (Calan), and diltiazem (Cardizem), may lead to xerostomia, which can facilitate plaque retention and increase the patient’s susceptibility to dental caries and periodontal disease. Drugs such as phenytoin (Dilantin), verapamil, and diltiazem may lead to severe gingival enlargement, which makes plaque control difficult (see Figure 9-1). In some patients, mexiletine and quinidine (Cardioquin) may cause neutropenia (a decrease in circulating neutrophils), which can increase their susceptibility to periodontal and other infections.

Some cases of cardiac arrhythmia are best treated by surgical insertion of a battery-operated electronic device (pacemaker) under the skin of the upper chest wall. Wire leads connect the pacemaker to an electrode that is placed in contact with heart tissue. The pacemaker sends periodic electrical impulses to the heart, thereby regulating its rate of contraction. The AHA guidelines do not recommend that patients with pacemakers be given antibiotics before dental procedures.15 However, for certain patients, the physician or cardiologist might recommend antibiotic coverage.

In one type of arrhythmia, portions of the heart undergo rapid irregular twitching, referred to as fibrillation. Defibrillators are designed to send electrical impulses to the heart to shock it into a normal pattern of contraction. Defibrillators can be implanted subcutaneously in the abdomen with electrodes connected to the heart. The devices detect the onset of fibrillation and automatically send small electrical shocks to the heart to correct the situation. As with pacemakers, prophylactic antibiotic coverage is not usually required before dental procedures.15

Congestive Heart Failure

Elective dental procedures should not be performed in patients with congestive heart failure unless their condition has been stabilized by medical treatment. In cases of congestive heart failure, the heart is unable to supply the body with sufficient oxygenated blood. As a result, the patient has difficulty breathing after minimal exertion.

Patients whose condition is under good medical control can safely receive routine dental treatment. However, appointments should be kept short to minimize stress. When these patients are treated, the dental chair should be kept in an erect or partially reclining position. If these patients are placed in a fully reclining position, gravity promotes the return of peripheral blood to the central circulation, thereby placing an extra burden on the heart. For these patients, it is a good idea to have supplemental oxygen on hand in case they encounter any difficulty in breathing.

Patients Who Are Taking Anticoagulants

Many patients with a history of cardiovascular disease often take anticoagulants (blood thinners). These reduce the risk of the development of blood clots that can block the circulation to vital organs such as the brain, heart, and lungs. Patients who have prosthetic heart valves or have had a recent heart attack or stroke (blockage of blood flow to the brain) frequently receive anticoagulant therapy. The medications that are usually administered for these conditions are heparin or warfarin (Coumadin) derivatives. Warfarin is the agent that is most often used on an outpatient basis. Subgingival instrumentation associated with routine dental hygiene procedures in anticoagulated patients can result in more gingival bleeding than is ordinarily encountered. However, the bleeding is usually easily controlled by applying pressure with a gauze sponge. When treating these patients, it is important to minimize the soft tissue trauma associated with subgingival instrumentation.

Many patients with a history of cardiovascular disease take small daily doses (80 to 325 mg) of aspirin, which retards the formation of blood clots by inhibiting platelet aggregation. At these doses, aspirin does not significantly alter the bleeding time,20 and postoperative bleeding from dental hygiene procedures is usually not a problem.

Joint Diseases and Disorders

Joint diseases and disorders that are frequently seen in dental patients and can complicate or modify the approach to dental or periodontal treatment include arthritis and artificial or prosthetic joints.


Arthritis is a general term that means inflammation of a joint. It is a common condition that affects, in one form or another, as many as 85% of adults older than 45 years. It is associated with many systemic diseases, including rheumatoid arthritis (rheumatism), osteoarthritis, systemic lupus erythematosus, scleroderma, and gout. The primary dental problem that arthritis causes in some patients is difficulty in performing oral hygiene procedures. This problem is particularly common in patients with rheumatoid arthritis and osteoarthritis involving the hands. Arthritic involvement of the hands can result in the inability to grasp such items as a toothbrush and to manipulate dental floss or other interproximal cleaning devices. This inability may stem from actual loss of joint flexibility or from intense pain associated with inflamed joints of the hands and fingers. Dental hygienists must recognize this potential problem and determine whether special plaque control devices, such as a powered toothbrush, are needed. In addition, as with all patients who have difficulty cleaning their teeth, it is advisable to schedule more frequent professional care.

Patients with severe arthritis often take antiinflammatory medications to reduce local inflammation and decrease the amount of joint pain. In some cases, relatively high doses of aspirin are prescribed by the patient’s physician. Aspirin can retard the formation of blood clots, so some increased bleeding may occur during routine scaling and root planing procedures. In most patients, this problem is not significant, and any localized gingival bleeding resulting from subgingival instrumentation can be controlled by pressure with a gauze sponge.

It is important to remember that arthritis can be the result of many systemic diseases and that it is only one of several medical problems that may have dental implications. For example, patients with progressive systemic sclerosis (PSS), or scleroderma, experience multiple dental and periodontal problems that are directly attributable to their systemic disease.21 PSS is a chronic connective tissue disease of unknown cause in which abnormal amounts of collagen are continuously deposited in a variety of organ systems, including the skin, lungs, and kidneys. PSS can cause death due to kidney or respiratory failure. As the disease progresses, the skin loses much of its elasticity and becomes almost leather-like. Severe arthritis and stiffening of the hands are common (Figure 9-2). It is difficult for these patients to hold or manipulate plaque control devices, and their firm inflexible skin often prevents them from opening their mouths wide enough to allow the dentist or dental hygienist access to perform routine procedures. As a result, patients with PSS tend to experience high rates of dental caries and periodontal disease. Significant gingival recession is a common feature (Figure 9-3). An unusual oral finding in some patients with PSS is the uniform widening of the periodontal ligament space seen in radiographs (Figure 9-4).22 Although PSS is not a common disease, it is a dramatic example of a systemic disease that can present challenges to the dentist and dental hygienist in providing adequate oral health care.

Artificial Joints

In some patients with arthritis, the destruction of joint tissues can result in severe pain and loss of function. In such cases, it is often necessary to replace the affected joint with an artificial or prosthetic device. Through modern orthopedic surgery, it is possible to replace joints of the hip, knee, elbow, wrist, and shoulder. Complete replacement of the hip joint is the most common procedure. Insertion of an artificial knee joint is often performed. Because more than 450,000 joint prostheses are placed annually in the United States, most dental practices will encounter patients with these devices.23

Infection, in one form or another, occurs in approximately 1% of joint prostheses and is a major cause of their failure.24 The sources of infections of joint prostheses (infections that occur more than 3 months after joint placement) are not known, but bacteremias originating from acute dental, respiratory tract, dermatologic, or urinary tract infections are prime suspects.2428 It appears that the highest risk of late infections of joint prostheses is up to 2 years after joint replacement.29

All patients with total joint replacements, orthopedic pins, and plates do not routinely require antibiotic prophylaxis before dental treatment.23 However, some patients may be at increased risk of hematogenous joint infection and should be considered as candidates for antibiotic coverage before extensive bacteremia-producing dental procedures. Guidelines for antibiotic regimens for these patients are currently being revised. Because there are no universally approved antibiotic prophylaxis guidelines, it is recommended that the patient’s physician be consulted prior to performing dental hygiene procedures in an individual with artificial joints.

Endocrine Disturbances and Abnormalities

Diabetes Mellitus

It is estimated that more than 16 million people in the United States have diabetes mellitus (DM), but only half of them have been diagnosed.30 Due to the obesity epidemic, the number of people with the disease is increasing. DM is a group of disorders that share the common feature of an elevated glucose level in the blood. The underlying problem in DM is an insufficient supply or impaired availability of insulin, a pancreatic hormone that is necessary for the regulation of carbohydrate metabolism. Based on the newest method of classification there are two main types of DM, type 1 and type 2.31 Although different groups of genes have been linked to the risk of developing of each of these two forms of diabetes, both forms have a genetic component.

Approximately 10% to 20% of all cases of diabetes mellitus are of the type 1 variety. In this form of the disease, there is a severe deficiency of insulin as a result of the destruction of pancreatic beta cells. Destruction occurs because of autoimmune reactions to beta cells that develop in response to environmental injury from some viruses.32 In other cases, destruction of beta cells may be caused by tumors, surgery, and toxic reactions to drugs or chemicals.32 Onset of the disease is usually rapid and occurs around the time of puberty. Medical control of type 1 DM requires periodic self-injection with one or more prescribed insulin preparations.

Patients with type 2 DM account for 80% to 90% of all cases of diabetes mellitus. In the early stages, the pancreatic beta cells are intact and capable of producing insulin. There are, however, two general metabolic defects associated with the development of type 2 DM, impaired secretion of insulin and insulin resistance.33 Although the precise reasons for these abnormalities are unknown, defective cell receptors for insulin are believed to play a role in insulin resistance.31 The onset of the disease is slow and it usually affects overweight individuals older than 30 years.32 The incidence of the disease increases with age. Medical control of early forms of type 2 DM can frequently be achieved by dietary modifications. If problems persist, oral hypoglycemic agents are used that stimulate insulin release from the pancreas and enhance insulin uptake by the tissues. In many patients with long-standing type 2 DM, loss of pancreatic beta cells eventually occurs, and periodic insulin injections are required to achieve medical control of the disease.

Patients with either form of diabetes suffer a wide variety of cardiovascular, kidney, eye, and neurologic problems.32 In addition, patients with uncontrolled or poorly controlled DM appear to be more susceptible to infections, including periodontal disease.33,34 The precise reasons for this increased susceptibility are unknown, but certain antibacterial functions of neutrophils appear to be abnormal.3538 Other common oral problems associated with diabetes include asymptomatic parotid gland enlargement39 and dry mouth resulting from decreased salivary flow.40

There is a long-standing clinical impression that control of gingival inflammation through periodontal therapy and good daily oral hygiene reduces insulin requirements in patients with diabetes.41 In other words, satisfactory metabolic control of diabetes is made easier if periodontal infections are arrested. There is a growing body of scientific evidence supporting this clinical impression.4245

Treatment Considerations

Patients with diabetes mellitus tolerate most routine dental procedures well, and no special precautions are usually necessary. However, because they are at greater risk for periodontal disease, it is advisable to schedule preventive dental care at more frequent intervals. Before dental visits, patients with diabetes should be instructed to continue their medication schedule as prescribed by their physician. For morning appointments, they should eat a normal breakfast to reduce the chances of becoming hypoglycemic during the visit.

Occasionally, before a dental visit, diabetic patients do not eat their normal diet and self-administer too much insulin. This practice can precipitate a dangerous emergency called insulin shock, in which the patient becomes severely hypoglycemic. The condition frequently develops rapidly and with little warning. The initial signs and symptoms of insulin shock include mental confusion, slurred speech, rapid heartbeat, nausea, and cold clammy skin. If the condition is not promptly treated, the patient’s blood pressure may drop precipitously. As a result, the patient may lose consciousness and have seizures. Death can occur if emergency measures are not taken. Fortunately, insulin shock is relatively easy to recognize, and the initial management of the emergency is simple. Because the underlying problem in cases of insulin shock is dangerously low levels of blood sugar (glucose), initial emergency care involves the prompt administration of a sugar-containing beverage, such as orange juice. Any easily administered sugar source will suffice (e.g., candy, honey, soft drinks). In addition, many patients will know what is happening and why they are being asked to consume a sugar-containing substance. Once the patient has consumed the sugar, recovery usually begins within a few minutes. If the patient does not respond, a medical emergency response team should be called.


Increased gingival inflammation (gingivitis) is frequently associated with pregnancy.4650 The gingivitis can be severe, with the tissues becoming swollen and red (Figure 9-5). Patients often report bleeding gums because the tissues bleed on the slightest provocation. The gingivitis is most severe during the first and second trimesters. It decreases somewhat around the eighth month and after parturition.47,48 If left untreated, the severe gingivitis associated with pregnancy may lead to the development of periodontitis, with the loss of alveolar bone and even teeth.46,50

It is not known precisely why gingival inflammation intensifies during pregnancy, but it has been clearly established that the inflammation is caused by plaque.47,48 However, vascular alterations associated with the hormonal changes of pregnancy (i.e., elevated serum levels of estrogen and progesterone) make the gingiva more susceptible to plaque-induced inflammation.50 Increased estrogen and progesterone can promote the growth of certain suspected periodontal pathogens such as Prevotella intermedia.51,52 In addition, changes in the immune system associated with pregnancy alter the host defenses against some infections.49

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Jan 14, 2015 | Posted by in Periodontics | Comments Off on 9: Systemic Factors Influencing Periodontal Diseases

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