Cone Beam CT

As Albert Einstein said, “If I can’t picture it, I can’t understand it.”

Sleep and Brain aims to identify a disease process, establish a differential diagnosis, determine an etiology, and render treatment options to support optimal health. We gather as much information as possible through a comprehensive exam, data collection, and photography. Radiographic imaging using cone beam computed tomography (CBCT) offers insight into causes and treatment solutions by visualizing anatomy. CBCT provides detailed images of the jaw, teeth, upper airway, nasal cavity, and sinuses. Clinical decisions are better informed when we can see what is happening. CBCT shows anatomy, not function: it is a static image taken while awake, so it does not diagnose sleep apnea or show how the airway behaves during sleep, and we interpret it together with the clinical evaluation and, when indicated, sleep testing.

Horizontal (Front-to-Back) Dimension

Children and adults can display horizontal dimension deficiencies, commonly seen in sleep-related disordered breathing due to improper growth of the maxilla and mandible. Maxillary deficiency can allow the soft palate to restrict the airway. Similarly, a retrognathic mandible can push the tongue back into the throat and pharyngeal region, constricting the airway. Early interventions can correct and may help prevent these outcomes and their effects on health.

Vertical Dimension

Vertical dimension is the distance between any point on the maxilla and the mandible when the teeth are in maximum intercuspation. Aberrancies in the vertical dimension are associated with sleep-disordered breathing and temporomandibular joint (TMJ) dysfunction.

Imaging helps identify problems in the temporomandibular joint region, which matters for airway management and TMD treatment. Active or passive joint degeneration and disk injury can result in vertical dimension loss, causing pain and function loss in the joint and head and neck muscles.

This vertical dimension loss can also impact occlusion and tooth wear. The CBCT images can indicate the need for additional imaging, like an MRI, to better understand the damage to the temporomandibular disk. A loss of vertical dimension can also negatively impact the airway. When considering a mandibular advancement appliance to treat obstructive sleep apnea, it is crucial to understand disk position and the presence of active or passive condylar degeneration since compressive forces can exacerbate these conditions.

The ramus length influences the lower facial one-third and the vertical dimension. With normal ramus development, the facial thirds are similar in length. With short ramus development, a long lower facial one-third with an increased display of teeth and gum on the maxillary arch develops. A long ramus has the opposite appearance. Instead of a long, narrow face, a more square face grows. Treatment for short ramus may entail double jaw surgery to decrease the lower facial one-third and the amount of maxillary tooth display. The opposite applies to a long ramus.

The gonial angle also influences the vertical dimension. An acute gonial angle (flat mandibular plane angle) will mimic the facial appearance of a long ramus. In contrast, an obtuse gonial angle (steep mandibular plane angle) will mimic the facial appearance of a short ramus length. The strength of the masseter muscles influences the gonial angle. The stronger and more developed the masseter muscle is, the more acute the gonial angle tends to be.

Transverse Dimension

Transverse deficiencies are associated with sleep disorders, malocclusion, tooth wear, and improper growth. We can measure the maxilla and mandible to understand their growth relationship. Recognizing transverse dimension issues early can produce predictable corrections through expansion. TAD expanders, TPD, MARPE, MSE, and EASE can correct transverse deficiency in children and adults, improving their occlusion and, in some individuals, airway function and sleep, which may support broader wellness.

The treatment target used by several analyses, including Andrews’ Element III, Hayes’ center of alveolar crest (CAC) technique, and the University of Pennsylvania CBCT analysis, is a maxilla about 5 mm wider than the mandible at the first molars (Hayes 2010; Tamburrino et al. 2010).

This is a target, not an average: in adults with normal occlusion measured on CBCT, the actual difference is smaller and varies widely from person to person (Lee et al. 2022). Hayes regards a maxilla that is merely equal in width to the mandible as the lower limit of an acceptable relationship, and as the maxilla falls further below the mandible, Class II relationships, crossbites, and compensatory tipping of the molars become more common (Hayes 2010; Tamburrino et al. 2010).

Absolute measurements help as well. In adults, an interlingual (transpalatal) width between the upper first molars of approximately 36 to 39 mm has been described as accommodating an average-sized dentition without crowding or spacing, while a maxillary arch narrower than about 31 mm may be crowded and is a candidate for orthopedic or surgically assisted expansion (McNamara 2000). Average values are somewhat narrower in females and vary among populations (Mustafa and Abuaffan 2021).

Nasal cavity width at the level of the first molars can also be measured on CBCT. In two small CT-based studies of people with transverse deficiency, one in adults with nasal obstruction undergoing surgically assisted expansion (Aras et al. 2010) and one in children with crossbite undergoing rapid palatal expansion (Georgiadis et al. 2023), the average width before treatment was about 29 to 31 mm, and expansion increased it by roughly 1 to 3 mm. In the adult study, acoustic rhinometry showed increased nasal cross-sectional area and volume after expansion, largely maintained at least a year later (Aras et al. 2010). A normal reference value for this measurement has not been well established, so these figures describe patients with transverse deficiency rather than the general population.

The piriform aperture, the bony opening at the front of the nasal cavity formed by the maxillae and nasal bones, can also be measured on CBCT. In a CT study of 170 adults, the maximal width averaged about 24.0 mm in women and 25.3 mm in men (Moreddu et al. 2013), in line with earlier studies. Whether a narrower aperture leads to measurably reduced nasal airflow has not been established, so we use these values as a reference for typical anatomy rather than a diagnostic cutoff.

Nasal Anatomical Abnormalities

Nasal anatomical abnormalities can increase nasal resistance and reduce nasal flow, leading to mouth breathing.

A CBCT can show a deviated septum, bone spur, concha bullosa, and enlarged turbinates, such as those caused by allergies. Proper nasal breathing is important to sleep quality and may support brain health, and correcting nasal obstruction can reduce mouth breathing. The images help show whether the problem is structural and whether noninvasive options such as nasal saline rinse, nasal dilators, allergy regimens, or Buteyko breathing are reasonable to try first. The images also help a head and neck or maxillofacial surgeon visualize a surgical plan to correct the anatomy.

Airway Volume

Imaging the airway space is beneficial to understanding the impact of the soft tissue and its effect on airflow. CBCT can identify potential chokepoints, which are the areas where the tissue can close off, impairing breathing.

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Airway volume and the narrowest cross-sectional area can be measured on CBCT. Smaller values are more common in people with obstructive sleep apnea, and the narrowest cross-sectional area has been the more consistent finding, but no accepted diagnostic cutoff has been established for either, and results depend on head position and measurement software.

Tonsils and Adenoids

A CBCT can show enlarged tonsils and adenoids.

Enlarged tonsillar tissue can affect sleep and brain health by narrowing, restricting, or blocking the airway. Identifying airway impingement is especially important with children, as early intervention can support growth and development.

Frequently asked questions

  • Planmeca Viso® G7 utilizes Planmeca Ultra Low Dose™ – a proprietary low-dose 3D imaging protocol that enables CBCT imaging with an even lower radiation dose than standard panoramic imaging. This protocol allows us to acquire 3D images at significantly lower effective doses without statistically reducing image quality. The pioneering and scientifically proven protocol is based on intelligent low-dose 3D imaging algorithms that produces an optimal balance of dose and quality – helping us adhere to the ALADA principle (As Low As Diagnostically Acceptable). SCARA (Selectively Compliant Articulated Robot Arm) technology guarantees anatomically accurate imaging geometry. The SCARA arm can produce any required movement pattern. This technology enables accurate and reliable volume positioning and diameter adjustment, resulting in clear and error-free CBCT images and reducing the dosage exposure. Finally, the Planmeca AINO™ algorithm achieves noise-free CBCT images without losing valuable details. The algorithm improves image quality when using small voxel sizes and allows lowering exposure values by reducing noise. 

  • Movement artifacts are among the most significant challenges to CBCT image quality. When a subject moves during imaging, it produces artifacts that affect the quality of the image. Planmeca Viso® G7 utilizes the intelligent Planmeca CALM® movement correction algorithm to cancel the effects caused by this movement. The Planmeca CALM® algorithm is excellent for imaging restless children, individuals with special needs, or the elderly. The Planmeca CALM® algorithm saves time and guards patients against unnecessary exposures by eliminating the need for retakes by canceling the effects of movement. Additionally, Planmeca Viso® G7’s head support provides stability and comfort. The clever support design of Planmeca Viso® G7 does not cover the ears in a 3D face photograph. We can also use it without the chin cup thanks to the Planmeca CALM®  movement artifact correction algorithm.

  • Metal restorations and root fillings can cause shadows and streaks in dental CBCT images. Based on extensive scientific research, the Planmeca Viso® G7  utilizes the intelligent Planmeca ARA™ algorithm to remove these artifacts efficiently and reliably. 

  • Rhinomanometry detects the Aerodynamic Failure (the traffic jam). The CBCT reveals the Architectural Cause (the car crash). When resistance is high, we use the 3D Scan to identify which of the four specific barriers is restricting flow inside the nose:

    1. Septal Deviation: Is the center cartilage bent or spurred, physically blocking one lane of the airway?

    2. Turbinate Obstruction: We check the structures that heat your air for two distinct issues: Hypertrophy (permanent soft-tissue swelling) or Concha Bullosa (a hidden air pocket inside the bone itself that steals valuable airspace).

    3. Transverse Deficiency Is your upper jaw (maxilla) too narrow? If the "floor" of the nose is constricted, the entire nasal tunnel is structurally cramped. This often requires orthopedic expansion rather than just surgery.

    4. Adenoids & Polyps: We check for growths that standard exams often miss. Nasal Polyps can grow out of the sinuses to fill the airway tunnel, while enlarged Adenoid Tissue can physically plug the "back exit" of the nose (the choanae).