Gingival hyperplasia (GH), or gingival overgrowth, is an abnormal enlargement of the gum tissue that surrounds the teeth. This condition causes the gingiva to swell and thicken, sometimes partially covering the crowns of the teeth. While poor dental hygiene and inflammation are common causes, drug-induced gingival hyperplasia (DIGH) is a direct side effect of certain systemic medications that interfere with the normal biology of the gum tissue.
Medications Most Often Implicated
Three classes of medications are primarily responsible for causing gingival overgrowth. Although prescribed for different conditions, they share a biochemical pathway that leads to this oral side effect. The severity of the overgrowth is highly variable among patients and depends on factors like drug dosage, duration of use, and the individual’s oral hygiene status.
Anticonvulsant medications, used to treat epilepsy and seizures, are one of the oldest and most potent causes of DIGH. Phenytoin (Dilantin) is the classic example and is known to affect 15% to 50% of long-term users. Other anticonvulsants, such as phenobarbitone and valproic acid, have also been implicated in causing this type of gum enlargement.
Calcium Channel Blockers (CCBs) constitute a second major class of drugs associated with gingival overgrowth. These agents are widely prescribed for managing hypertension, angina pectoris, and certain heart arrhythmias. Nifedipine (Procardia) is the CCB most frequently linked to DIGH, though other drugs in this class, including Amlodipine (Norvasc) and Verapamil, can also trigger the condition. The incidence of DIGH with CCBs is generally lower than with phenytoin, affecting an estimated 10% to 20% of patients.
The third main group is Immunosuppressants, administered to prevent organ rejection in transplant recipients and to treat certain autoimmune diseases. Cyclosporine is the primary drug in this category that causes DIGH, with a reported prevalence as high as 25% to 80% in patients, particularly those with kidney transplants. This drug’s effect can be compounded when a patient is concurrently taking a CCB like Nifedipine.
How These Drugs Affect Gum Tissue
Drug-induced gingival overgrowth is a fibrotic process caused by the disruption of normal connective tissue maintenance within the gingiva, characterized by an excessive accumulation of the extracellular matrix, primarily collagen. The key players in this process are specialized cells in the gums called fibroblasts, which are responsible for both producing and breaking down collagen.
These medications interfere with the normal function of gingival fibroblasts, tipping the balance toward excessive production and reduced degradation of collagen. The drugs increase collagen synthesis while simultaneously inhibiting enzymes, such as collagenase, necessary to break down old collagen. This imbalance causes the tissue to enlarge and harden.
The drugs also impair the fibroblast’s ability to internalize and digest collagen (collagen phagocytosis). This is thought to relate to the drugs’ shared ability to interfere with the flow of calcium ions, which regulates cellular activities. This disruption in cellular maintenance leads to a net increase in the bulk of the gum tissue, resulting in the clinically visible overgrowth.
Clinical Management and Reversal
The primary step in managing drug-induced gingival overgrowth is rigorous control over dental plaque. Poor oral hygiene significantly exacerbates DIGH, as plaque intensifies the tissue’s reaction to the medication. Patients must commit to meticulous brushing and flossing, often requiring professional cleanings every three months to minimize the inflammatory component.
The most effective treatment involves modifying the medication regimen under the direction of the prescribing physician. If medically appropriate, discontinuing the causative drug often leads to rapid and significant regression of the overgrowth. When stopping the medication is not possible, the physician may substitute the offending drug with a chemically different alternative that is less likely to induce DIGH.
If substitution is not feasible or fails to resolve the condition, surgical intervention may be necessary. This procedure, known as a gingivectomy or gingivoplasty, involves physically removing the excess, fibrotic gum tissue. For instance, a patient experiencing overgrowth from a Calcium Channel Blocker might be switched to another class of antihypertensive medication.
Surgical removal is reserved for severe cases where the overgrowth interferes with speech, chewing, or aesthetics. If the causative drug is continued, the overgrown tissue is highly likely to recur, making long-term maintenance necessary. In some cases of Cyclosporine-induced overgrowth, the antibiotic Azithromycin has been used successfully as an adjunctive treatment to reduce the size of the enlarged tissue.