Mouthguard Bleaching : Complications and Adverse Effects
Systemic Effects. Controlled mouthguard bleaching procedures are considered relatively safe. However, some concern has been raised over bleaching gels inadvertently swallowed by the patient. Accidental ingestion of large amounts of these gels may be toxic and cause irritation to the gastric and respiratory mucosa. Bleaching gels containing carbopol, which retards the rate of oxygen release from peroxide, are usually more toxic. Therefore, it is advisable to pay specific attention to any adverse systemic effects and to discontinue treatment immediately if they occur.
Dental Hard Tissue Damage. In vitro studies indicate morphologic and chemical changes in enamel, dentin, and cementum associated with some agents used for mouthguard bleaching. Long-term in vivo studies are still required to determine the clinical significance of these changes.
Tooth Sensitivity. Transient tooth sensitivity to cold may occur during or after mouthguard bleaching. In most cases, it is mild and ceases on termination of treatment. Treatment for sensitivity consists of removal of the mouthguard for 2 to 3 days, reduction of wearing time, and re-adjustment of the guard.
Pulpal Damage. Long-term effects of mouthguard bleaching on the pulp are still unknown. To date, no correlation has been found between carbamide peroxide bleaching and permanent pulpal damage.The pulpalgia associated with tooth hypersensitivity is usually transient and uneventful.
Mucosal Damage. Minor irritations or ulcerations of the oral mucosa have been reported to occur during the initial course of treatment. This infrequent occurrence is usually mild and transient. Possible causes are mechanical interference by the mouthguard, chemical irritation by the bleaching active agent, and allergic reaction to gel components. In most cases, readjustment and smoothing the borders of the guard will suffice.
However, if tissue irritation persists, treatment should be discontinued.
Damage to Restorations. Some in vitro studies suggest that damage of bleaching gels to composite resins might be caused by softening and cracking of the resin matrix. It has been suggested that patients are informed that previously placed composites may require replacement following bleaching. Others have reported no significant adverse effects on either surface texture or color of restorations. Generally, however, if composite restorations are present in esthetically critical areas, they may need replacement to improve color matching following successful bleaching. It has also been reported that both 10% carbamide peroxide and 10% hydrogen peroxide may enhance the liberation of mercury and silver from amalgam restorations and may increase exposure of patients to toxic by-products.Although bleaching gels are mainly applied to the anterior dentition, excessive gel may inadvertently make contact with posterior teeth. Coverage of posterior amalgam restorations with a protective layer of dental varnish prior to gel application may prevent such hazards.
Occlusal Disturbances. Typically, occlusal problems related to the mouthguard may be mechanical or physiologic. From a mechanical point of view, the patient may occlude only on the posterior teeth rather than on all teeth simultaneously. Removing posterior teeth from the guard until all of the teeth are in contact rectifies this problem. From a physiologic point of view, if the patient experiences temporomandibular joint pain, the posterior teeth can be removed from the guard until only the anterior guidance remains. In such cases, wearing time should be reduced.