The evolution of imaging technology has enabled dentists to expand the diagnostic services they can offer to patients. Many practices are taking advantage of these capabilities to help patients suffering from airway and joint conditions such as sleep-disordered breathing (SDB) and temporomandibular joint disorder (TMD).
This condition occurs when there is obstruction of the airway, decreasing the airflow by upwards of 25% for longer than 10 seconds at a time. The past two decades have seen a growing number of people with these conditions. Roughly 23 million adults in the U.S. have undiagnosed or untreated moderate-to-severe obstructive sleep apnea, according to a study in the Journal of Dental Sleep Medicine.
Most people associate this condition with troublesome symptoms such as snoring, but it can cause more severe issues. The resulting lower levels of oxygen in the blood can have a profound impact on quality of life. Researchers at Harvard Medical School found that milder forms of sleep apnea can result in issues such as impaired concentration and higher risk of traffic accidents and occupational injuries, while more intense cases may lead to cardiac disease, hypertension and death.
Patients with sleep apnea tend to present with common symptoms, such as difficulty staying asleep, excessive sleepiness in the daytime, dry mouth, difficulty concentrating, gasping for air during sleep and headaches in the morning. “There are many mechanical factors, such as facial elongation, hypertrophy of hard and soft tissues, a high-arched palate, as well as retroglossal obstructions and nasal obstructions, that are associated with SDB,” says Dr. Heidi Kohltfarber, renowned oral and maxillofacial radiologist and founder of Dental Radiology Diagnostics.
Evaluating patients for SDB
When there is suspected SDB, a systematic examination is warranted, beginning with a review of the patient’s health history, completion of the Epworth Sleepiness Scale questionnaire (a form used as a subjective measure of a patient’s sleepiness), a clinical examination and potentially a home sleep study. There are also a range of dental and medical imaging capabilities available for helping to diagnose patients with SDB. Each has its own pros and cons.
Panoramic images are the most common dental radiograph. This is very easy for patients and gives dentists a broad picture of what’s occurring. These 2D images cost little to produce and have a low radiation dose. The disadvantage is that due to superimposition of structures, it can be difficult to visualize soft tissue detail, making these images not particularly useful for evaluating the airway space.
Lateral cephalometric radiographs are also low dose and easy for patients. Similarly, these images offer a broad field of view for evaluating all skeletal types. This can be useful for evaluating oral appliances, as well as orthognathic surgery. However, like panoramic images, there is also a good amount of superimposition of structures, which limits their use for soft tissue assessment.
Cone beam computed tomography (CBCT) is becoming increasingly common in dental offices and offers a very high spatial resolution compared to virtually any other scan, including magnetic resonance imaging (MRI). One of the advantages of these 3D images is the ability to view patients in all three planes at the same time, as opposed to medical computed tomography (CT), where images are reconstructed one section at a time. CBCT offers low cost, lower radiation than medical CTs and are easy on patients. These tend to be very useful for looking at oral appliances and orthognathic surgery. In many dental offices, the patients will be standing or seated, and this can be a bit of a disadvantage when evaluating airway space. A supine unit would be ideal for this type of evaluation, but many practices don’t have that amount of space for this type of system.
Medical CTs also show the patient in all three planes, offering a high degree of temporal and spatial resolution. Scans can be performed very quickly, making them easy on the patient. These scans offer excellent soft tissue detail, making them ideal for evaluating airways, as well as boney structure for airways.
MRIs offer superior soft tissue contrast and high resolution of the upper airways. This includes dynamic imaging modality, enabling practitioners to watch the patient swallow and function. The downfall of MRIs is the small, confined space, which is challenging for patients who are claustrophobic or who are on the larger size. Some patients also find the noise within the systems difficult to tolerate.
Caution is needed when determining which patients go into an MRI machine, due to the powerful magnets the systems use. “You need to be very careful about keeping any metal out of the MRI because it will become a projectile,” cautions Dr. Kohltfarber. Patients with metallic implants, pacemakers or aneurysm clips aren’t candidates for MRIs. There is also a safety issue for patients with magnetic false eyelashes.
It’s important to note that scans, such as those captured by CBCT units, cannot diagnose obstructive sleep apnea. This requires a sleep study. However, dentists can perform CBCT scans to identify anatomical variants and pathologies that are limiting the mechanical airway function. “Once we can show a patient what their airway space looks like, this can start a dialogue, and can help a patient perhaps be more open to participating in a sleep study,” says Dr. Kohltfarber.
Obstructive sleep apnea treatment
There are a whole host of treatment options for sleep apnea, the most common being the continuous positive airway pressure (CPAP) machine, which uses a mask to deliver steady air pressure to help someone breathe while they sleep. Many people find it difficult to adjust to sleeping with a bulky mask on. Other treatment options include orthognathic surgery, as well as oral appliances. If a patient is considering an oral appliance, it’s important that this be properly sized by a dental professional; otherwise, it can cause damage to the temporomandibular joint (TMJ) region.
Sleep apnea is just one of many health issues practices are now helping patients address. In addition to assessing airway issues, many dentists are helping patients struggling with pain from TMD.
A Clinical Oral Investigations report noted that nearly one third of adults and adolescents have some sort of TMD. They may experience jaw discomfort, particularly in the morning or late afternoon, headaches, clicking or popping of the jaw, as well as pain spreading behind the eyes or in the face, shoulders, neck or back. According to the Cleveland Clinic, if left unresolved, TMD can result in health issues such as chronic pain and inflammation.
Evaluating patients with TMD
There is currently no singular standardized method for diagnosing TMD. Research reported in the Journal of Oral and Facial Pain and Headache highlighted numerous working groups involved with standardizing its diagnosis.
Dentists have found that this condition may or may not be associated with clinical symptoms. “The really strange thing about TMD is that we might see obvious changes and yet the patient has no symptoms at all, or a patient might come in with excruciating symptoms, yet we’re not seeing anything as far as the osseous structures are concerned,” says Dr. Kohltfarber. “It’s very multifactorial, which makes it very difficult to treat these patients. If a patient has persistent symptoms and occlusal therapy, different appliances or exercises we’ve prescribed are not doing a good job to curb that for that patient, then it’s advisable to perform additional imaging and refer the patient to an orofacial pain specialist.”
Ultimately, dental practitioners have many more tools at their disposal than they did just a few short years ago. This expands the ability to provide more holistic care for patients beyond general dentistry. The key is to understand the pros and cons of each type of imaging system, and to develop relationships with clinicians who can help patients manage conditions such as TMD and SDB.
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