Effectiveness of Interocclusal Aligner (IOA) on Preventing Occlusal Changes in Patients Treated With a Mandibular Advancement Device (MAD): A Preliminary Study

Sleep-related breathing disorders (SRBD) are a group of disorders characterized by abnormal breathing during sleep, and common SRBD conditions encompass primary snoring and obstructive sleep apnea (OSA). Obstructive sleep apnea (OSA) is characterized by recurring episodes of partial or complete upper airway obstruction during sleep. This condition can result in daytime exhaustion, cognitive impairments, diminished quality of life, and elevated risks of cardiovascular and cerebrovascular illnesses, as well as increased mortality. OSA has also been linked to the development and progression of painful conditions such as temporomandibular disorders (TMD) and other orofacial pain conditions.

Currently, continuous positive airway pressure (CPAP) is recognized as the most effective treatment for OSA. However, patients' compliance with CPAP therapy is low, and it is oftentimes not tolerated. Therefore, almost two decades ago, the American Academy of Sleep Medicine approved the use of mandibular advancement devices (MADs) as an alternative treatment option. MADs work by mechanically advancing the mandible and maintaining it in a forward position, thereby decreasing airflow resistance and preventing collapse of the upper airway during sleep. MADs are also used for the cosmetic management of primary snoring.

Despite the promise of MADs in treating SRBD, one of the drawbacks to long-term use is the development of dental side effects. These include palatal tipping of the maxillary incisors, forward tilting of the mandibular incisors, minor mesial shifting of the mandibular molars, and posterior teeth losing contact or developing a posterior open occlusal relationship (POOR). The development of a POOR secondary to MAD use has been estimated to affect approximately 10-12% of individuals using these devices. However, beyond investigating the prevalence of POOR, the long-term consequences remain largely unexplored, with limited studies available. It has been hypothesized that POOR can cause sustained shortening of the lateral pterygoid muscles. As a result, when the patient attempts to achieve maximum intercuspation, the front teeth make contact while the back teeth fail to do so, which can significantly hinder a patient's ability to chew properly, resulting in impaired masticatory function. While this phenomenon is often temporary, resolving within hours or days, in rare instances, it may become irreversible.

Traditionally, simple jaw exercises aiming to stretch the lateral pterygoid muscle are recommended to alleviate or correct these side-effects of MADs. However, an emerging clinical trend is the use of an interocclusal aligner (IOA) following the removal of the MAD to minimize dental side effects, rather than relying solely on jaw exercises. However, the effectiveness of IOAs to prevent the development of POOR secondary to the MAD has not yet been empirically demonstrated.

The interocclusal appliances (interocclusal aligner (IOA)) include a variety of personalized appliances and pre-manufactured devices designed to restore the mandible to its usual pre-treatment position. These tools function by re-calibrating the patient's bite into maximum intercuspation, guiding each tooth back into its original position. Additionally, biting pressure is applied to reposition the condyles, with the goal of re-establishing or preserving proper occlusal alignment in the morning after each night of MAD therapy. The guide is customized to fit the patient's maxillary and mandibular teeth in their pre-treatment maximum intercuspation. Moreover, these devices assist in reversing tooth position changes by providing additional exercises that stretch and engage the jaw muscles.