The term describes a disruption in the electrical signals that coordinate the heartbeat. The heart’s rhythm depends on a specialized conduction system—the SA node, AV node, and conducting pathways—that pace and synchronize atrial and ventricular contractions. When these impulses don’t flow or timing is off, the rhythm can become too fast, too slow, or irregular. That disturbance is called a cardiac arrhythmia. Arrhythmias can range from harmless to life-threatening and may cause palpitations, dizziness, or fainting, though sometimes there are no symptoms. This is different from a myocardial infarction, which is a blockage causing heart muscle damage; an aneurysm, which is a bulge in a vessel or heart wall; and atherosclerosis, which is plaque buildup in arteries.

During pregnancy, hormonal changes, especially higher levels of estrogen and progesterone, influence how gingival connective tissue behaves. These hormones alter the activity of gingival fibroblasts and immune cells, shifting the balance of how the extracellular matrix is produced and broken down. A key part of this shift is a decrease in collagenase activity, which means less breakdown of collagen in the gingiva. This change in connective tissue turnover interacts with the heightened inflammatory response to dental plaque, contributing to common oral health changes like gingival swelling, increased bleeding, and gingivitis seen in pregnancy. Enamel mineralization is a developmental process set before birth, so pregnancy hormones don’t dynamically change enamel mineralization. Salivary flow can be affected by various factors, but it isn’t the central mechanism behind the pregnancy-associated gingival changes. Dentin sclerotization is an aging-related process and isn’t a feature driven by pregnancy hormones.

Prophylaxis for infective endocarditis is kept for those with conditions that put them at the highest risk for serious infection if bacteremia occurs. A prosthetic heart valve creates a surface where bacteria can more easily adhere and form endocarditis, and infections on prosthetic valves are particularly difficult to treat and can be life-threatening. Because of that elevated risk, antibiotic prophylaxis is recommended for procedures that may cause bacteremia in these patients. Asthma, diabetes, and hypertension do not by themselves place a patient in the high-risk category defined by current guidelines, so prophylaxis is not routinely indicated for these conditions.

When saliva’s buffering system is reduced, it loses its ability to neutralize acids produced by bacteria. Saliva normally contains buffers like bicarbonate and phosphate that keep the pH around neutral to slightly basic. With fewer buffers available, those acids aren’t neutralized as effectively, so the pH drops and the saliva becomes more acidic. This aligns with the idea that decreased buffering leads to a lower salivary pH. Increased pH or no change would require more buffering or no change in acid production, which doesn’t fit the mechanism here; the result is a decreased pH.