Dental Radiography: Bitewing, Occlusal, Panoramic, Extraoral, and 3D Imaging

Bitewing Radiography Principles and Anatomy

• Fundamental Definition and Clinical Scope:

  • Records the coronal portions, crowns, and alveolar bone crests of both the maxillary and mandibular teeth simultaneously on a single image receptor.

  • Exclusively images coronal and crestal structures; it does not capture the apical regions of teeth and will not reveal periapical pathology.

  • Functions clinically as:

  • A stand-alone diagnostic radiographic series.

  • An adjunct taken in conjunction with a full mouth series (FMX) of periapical radiographs.

  • A supplemental exposure alongside extraoral panoramic radiographs.

• Primary Diagnostic Indications:

  • Detection of interproximal dental caries in early and incipient stages before clinical cavitation occurs.

  • Accurate evaluation of alveolar bone crest levels and pattern of crestal bone resorption associated with periodontal disease.

  • Visualizes proximal decay and the crestal height of alveolar bone with greater geometric accuracy and resolution than standard periapical radiographs.

Image Receptor Selection, Sizing, and Series Configurations

• Receptor Sizes and Patient Indications:

  • Size 0:

  • Recommended clinical population: Pediatric patients presenting with primary dentition.

  • Standard exposure quantity and orientation: $2$ horizontal posterior images ($1$ per side).

  • Size 1:

  • Recommended clinical population: Pediatric patients presenting with primary or mixed dentition; adult anterior examinations.

  • Standard exposure quantity and orientation:

    • Pediatric posterior: $2$ horizontal posterior images ($1$ per side).

    • Adult anterior: $3$ or $4$ vertical anterior images.

  • Size 2:

  • Recommended clinical population: Pediatric patients in mixed dentition prior to the eruption of permanent second molars; adolescents following eruption of permanent second molars; adult routine examinations; adult periodontal patients.

  • Standard exposure quantity and orientation:

    • Mixed dentition (prior to permanent second molar eruption): $2$ horizontal posterior images.

    • Adolescent (post-eruption of permanent second molars): $4$ horizontal posterior images ($2$ per side: premolar and molar).

    • Adult routine: $4$ horizontal posterior images ($2$ per side: premolar and molar).

    • Adult periodontal disease: $4$ vertical posterior images (provides greater superior-inferior recording area to monitor advanced bone loss).

  • Size 3:

  • Recommended clinical population: Adolescents after eruption of permanent second molars; adult patients.

  • Standard exposure quantity and orientation: $2$ horizontal posterior images ($1$ per side).

• Characteristics of Size 3 Receptors:

  • Specifically engineered for horizontal bitewing projections.

  • Advantage: Requires only a single exposure per side of the dental arch, decreasing patient radiation exposure and operator clinical time.

  • Disadvantages:

  • Narrower in vertical dimension compared to Size 2 receptors, often failing to capture adequate crestal alveolar bone levels.

  • Due to the curvature of the dental arch, it is virtually impossible to align the primary radiation beam perpendicular to all posterior contacts simultaneously, routinely resulting in overlapping interproximal contact points.

• Bitewing Series Configurations:

  • Complete bitewing examinations range from $2$ to $8$ exposures.

  • Posterior bitewing series consist of either $2$ exposures (pediatric/mixed dentition or Size 3) or $4$ exposures (standard adult premolar and molar projections per side).

  • Anterior bitewing examinations utilize $3$ or $4$ vertical images.

  • Vertical bitewing series comprise $7$ to $8$ vertical radiographs (combining anterior and posterior projections); indicated specifically for comprehensive evaluation of moderate-to-severe periodontal bone loss.

Bitewing Receptor Stabilization and Beam Alignment

• Non-Bite Block Devices:

  • Include self-adhesive stick-on paper or plastic bitetabs and paper or plastic film loops.

  • Characterized by ease of placement, low cost, disposable single-use design, and high patient comfort and tolerance.

• Bite Block Holders and Alignment Instruments:

  • Specialized bite blocks accommodate photostimulable phosphor (PSP) plates or direct digital sensors for vertical and horizontal orientations.

  • Receptor positioners paired with an external guide arm and aiming ring assist the operator in selecting precise horizontal and vertical angulation and central ray points of entry.

  • Clinical Caveat: The rigid block portion of certain receptor positioners is thicker than adhesive tabs; this thickness can prevent the patient from fully occluding into centric relation, truncating the recorded height of the alveolar crest.

• Horizontal Angulation and Interproximal Overlap Diagnosis:

  • The central ray must pass precisely parallel to the contact areas and perpendicular to the receptor.

  • Mesiodistal Beam Angulation Error: Directing the position-indicating device (PID) obliquely from the mesial toward the distal (a deviation of approximately $15^\circ$) produces severe overlap in the posterior (distal) region of the radiograph.

  • Distomesial Beam Angulation Error: Directing the PID obliquely from the distal toward the mesial (a deviation of approximately $15^\circ$) produces severe overlap in the anterior (mesial) region of the radiograph.

  • Correct Horizontal Beam Angulation: Directing the central ray perpendicular to the image receptor and parallel through the interproximal embrasures eliminates overlapping entirely.

• Vertical Angulation:

  • Standard vertical angulation for all bitewing projections is $+10^\circ$ (PID tilted downward toward the floor).

  • Pediatric vertical angulation of $+5^\circ$ is occasionally recommended.

  • Errors in Vertical Angulation:

  • Inadequate vertical angulation (negative or less than $+10^\circ$) results in excessive mandibular coverage with loss of maxillary crestal anatomy.

  • Excessive vertical angulation (significantly greater than $+10^\circ$) results in excessive maxillary coverage with loss of mandibular crestal anatomy.

• Point of Entry:

  • Positioned at the level of the occlusal/incisal plane (adjacent to the lip line), directed directly through the interproximal embrasures of interest and centered over the receptor.

  • Failure to center the PID over the image receptor results in partial beam interception, creating a conecut error.

Occlusal Radiography Principles and Classifications

• Fundamental Scope and Purpose:

  • Exposes large anatomic segments of the maxilla or mandible on a single intraoral projection.

  • Indicated for locating supernumerary, unerupted, or impacted teeth.

  • Identifying retained root tips post-extraction.

  • Mapping the boundaries and extent of pathologic lesions, cysts, or tumors.

  • Identifying radiopaque foreign bodies lodged within jaw structures.

  • Demonstrating sialoliths (salivary stones) within Wharton's duct (submandibular gland) or the ducts of the sublingual glands.

  • Diagnosing and evaluating maxillary and mandibular fractures.

  • Demonstrating the extent and morphology of mandibular tori.

  • Managing patients with severe trismus who cannot open the mouth beyond several millimeters.

  • Evaluating the bony margins and integrity of the maxillary sinus.

  • Assessing structural defects in cleft palate patients.

  • Providing a surrogate periapical assessment in pediatric patients intolerant of standard periapical intraoral positioners.

• Technical Modalities:

  • Topographical Technique:

  • Utilizes the geometric principles of the bisecting angle technique, yielding an image resembling an enlarged periapical radiograph.

  • Applicable to both anterior and posterior regions of the maxilla and mandible.

  • Delivers high diagnostic yield regarding apical regions and the crest of the alveolar ridge.

  • Cross-Sectional Technique:

  • The central ray is directed perpendicular ($90^\circ$) to the image receptor.

  • Results in teeth that appear circular, shortened, or elliptical in cross-section.

  • Maximizes visibility of the floor of the mouth and sublingual space.

  • Primarily indicated for diagnosing buccal-lingual expansion, foreign bodies, soft tissue calcifications, and impacted teeth.

  • Confined almost exclusively to the mandible; cross-sectional maxillary projections are rarely indicated due to superimposition of dense cranial structures.

Occlusal Projection Techniques and Angular Parameters

• Receptor Specifications and Handling:

  • Utilizes Size 4 image receptors (PSP plates or film) in adults.

  • Size 2 receptors serve as substitutes for pediatric occlusal examinations.

  • Stabilization relies on patient biting pressure directly on the receptor face; no bite-blocks or alignment frames are required.

  • The receptor is placed with the active (unprinted/white) exposure side against the arch of interest.

  • Must be positioned deep into the oral cavity with approximately $0.25\,\text{inch}$ ($0.5\,\text{cm}$) protruding past the incisal edges to prevent truncation of coronal structures.

• Patient Head Alignment by Arch:

  • Maxillary Topographical (Anterior & Posterior) and Mandibular Topographical: Seated upright with the midsagittal plane perpendicular to the floor and the occlusal plane parallel to the floor.

  • Mandibular Cross-Sectional: Patient reclined with the head tipped completely back, aligning the occlusal plane perpendicular to the plane of the floor.

• Angular Parameters and Points of Entry:

  • Maxillary Topographical (Anterior):

  • Orientation: Long dimension placed transversely (buccal-to-buccal) across the arch.

  • Vertical Angulation: $+65^\circ$.

  • Horizontal Angulation: Central ray perpendicular to the receptor through the maxillary central incisor contact.

  • Point of Entry: Near the bridge of the nose, aimed toward the center of the receptor.

  • PID Specification: An $8\,\text{inch}$ ($20.5\,\text{cm}$) PID is utilized to mitigate geometric magnification.

  • Maxillary Topographical (Posterior):

  • Orientation: Long dimension placed anteroposteriorly along the midline, offset to the side of interest.

  • Vertical Angulation: $+45^\circ$.

  • Horizontal Angulation: Perpendicular to the midsagittal plane through posterior embrasures.

  • Point of Entry: Along the ala-tragus line, directly inferior to the outer canthus of the eye.

  • Mandibular Topographical (Anterior):

  • Orientation: Long dimension placed transversely (buccal-to-buccal).

  • Vertical Angulation: $-55^\circ$.

  • Horizontal Angulation: Perpendicular to the receptor through the mandibular central incisor contact.

  • Point of Entry: Midline of the chin, directed toward the center of the receptor.

  • Mandibular Topographical (Posterior):

  • Orientation: Long dimension placed anteroposteriorly, offset over the quadrant of interest.

  • Vertical Angulation: $-45^\circ$.

  • Horizontal Angulation: Perpendicular to the midsagittal plane through posterior embrasures.

  • Point of Entry: Along the inferior border of the mandible, directly below the second mandibular premolar.

  • Mandibular Cross-Sectional:

  • Orientation: Long dimension placed transversely (buccal-to-buccal).

  • Vertical Angulation: $0^\circ$ (central ray directed perpendicular to the receptor plane; PID face parallel to receptor).

  • Horizontal Angulation: Perpendicular to the plane of the image receptor.

  • Point of Entry: At the midline, approximately $2\,\text{inches}$ ($5\,\text{cm}$) posterior to the tip of the chin.

Radiographic Object Localization Techniques

• Tube Shift Method (Buccal-Object Rule / SLOB Rule):

  • Requires two individual radiographs of the same anatomic area exposed at different horizontal or vertical beam angles.

  • Acronym rule: SLOB = Same Lingual, Opposite Buccal.

  • Lingual Determination: If the object in question moves in the same direction as the horizontal or vertical angular shift of the tubehead, the object resides on the lingual aspect.

  • Buccal Determination: If the object in question moves in the opposite direction relative to the horizontal or vertical angular shift of the tubehead, the object resides on the buccal aspect.

Panoramic Imaging Fundamentals and Equipment

• Core Concepts of Panoramic Radiography:

  • Produces an extraoral survey displaying a broad view of the maxilla, mandible, and adjacent maxillofacial structures on a single projection.

  • Operates on the physical principle of tomography: a radiographic technique that records structures situated within a specific plane of tissue while intentionally blurring structures located in adjacent planes.

  • The radiation source (tubehead) and the image receptor rotate continuously around the patient's head in opposite directions while the patient remains stationary.

• Center of Rotation:

  • Represents the pivotal rotational axis around which the tubehead and cassette carrier revolve.

  • Modern panoramic systems employ a continuously moving rotational center to adjust to the elliptical morphology of the human dental arches.

• The Focal Trough:

  • A theoretical three-dimensional curved zone (or image layer) where anatomical structures register with optimal resolution and sharpness.

  • Structures positioned inside the trough are sharply recorded; structures positioned anterior, posterior, or lateral to the trough undergo severe geometric distortion and blurring.

• Image Classification on Panoramic Projections:

  • Real Image: Formed when an anatomical structure lies directly between the receptor and the moving rotational center; registers with normal anatomical characteristics.

  • Double Image: Formed when an anatomical structure located posterior to the moving center of rotation is penetrated twice by the beam (e.g., hard palate, hyoid bone, cervical spine); manifests as mirror images on both sides of the radiograph.

  • Ghost Image: Formed when a dense anatomical structure or metallic object is positioned outside the focal trough, close to the x-ray tubehead; registers on the opposite side of the image, appearing larger, more blurred, and projected higher than the real object.

• Panoramic Equipment Architecture:

  • X-Ray Tubehead and Collimation:

  • Differs from intraoral equipment by utilizing a lead collimator containing an opening configured as a narrow vertical slit.

  • Projects a narrow, fan-shaped vertical ribbon of radiation through the patient to an opposing vertical slit in the cassette carrier.

  • The vertical angulation of the tubehead is permanently fixed, directing the primary beam with a slight negative-to-positive upward trajectory (pointing slightly upward).

  • Head Positioner Hardware: Includes a chin rest, notched incisal bite-block, forehead clamp, and lateral head guides to immobilize the patient within the focal trough.

  • Image Receptors and Intensifying Screens:

  • Utilizes direct digital sensors, photostimulable phosphor plates, or screen film.

  • Screen film is loaded between two intensifying screens within a rigid or flexible light-tight cassette.

  • Calcium Tungstate Screens: Emit blue visible light.

  • Rare Earth Screens: Emit green visible light; exhibit superior x-ray-to-light conversion efficiency, requiring less radiation exposure, and represent the clinical standard for dose reduction.

Panoramic Technique, Positioning Protocol, and Error Analysis

• Patient Preparation Protocol:

  • Fully describe the machine's rotational trajectory to prevent startle reactions.

  • Apply a lead apron without a thyroid collar (double-sided apron recommended) to prevent beam obstruction.

  • Remove all metallic and radiodense items from the head and neck region (glasses, earrings, necklaces, piercings, hairpins, prostheses, intraoral appliances).

• Patient Positioning Steps:

  • Patient stands or sits completely erect ("as tall as possible") with shoulders pulled back.

  • Anterior teeth bite edge-to-edge into the designated notches on the plastic bite-block.

  • Align the midsagittal plane perpendicular to the floor.

  • Align the Frankfort plane (orbitale to porion) parallel to the floor.

  • Instruct the patient to swallow, seal the lips securely around the bite-block, and press the entire dorsum of the tongue firmly against the hard palate for the entire exposure.

• Comprehensive Error Analysis:

  • Ghost Images:

  • Cause: Failure to remove external radiodense or metallic hardware.

  • Presentation: Radiopaque, blurred, magnified artifact appearing higher up on the side opposite the physical object.

  • Lead Apron Artifact:

  • Cause: Use of a thyroid collar or placing a lead apron too high on the neck/shoulders.

  • Presentation: Dense, radio-opaque, cone-shaped wedge in the inferior-central field obscuring the mandible.

  • Failure to Seal Lips: Radiolucent dark shadow across the anterior crowns.

  • Failure to Maintain Tongue on Palate: Expansive radiolucent airway shadow obscuring the apices of all maxillary teeth.

  • Chin Tipped Up (Frankfort Plane Angled Superiorly):

  • Presentation: Flattened occlusal plane or "reverse smile line" (frowning occlusal plane); hard palate and floor of the nasal cavity superimposed directly over maxillary root apices; condylar processes projected off the lateral edges.

  • Chin Tipped Down (Frankfort Plane Angled Inferiorly):

  • Presentation: Pronounced curvature or "exaggerated smile line"; mandibular anterior roots foreshortened and blurred; severe loss of detail in the mandibular anterior apical region; condyles projected high near the upper image border.

  • Teeth Anterior to Focal Trough (Patient Positioned Too Far Forward): Anterior teeth positioned mesial to the bite-block groove appear abnormally skinny, narrowed, and out of focus.

  • Teeth Posterior to Focal Trough (Patient Positioned Too Far Back): Anterior teeth positioned distal to the bite-block groove appear abnormally widened ("fat"), magnified, and out of focus.

  • Head Turned (Midsagittal Plane Not Centered): Asymmetric magnification; the side rotated farther from the receptor appears excessively wide and magnified, while the side rotated closer to the receptor appears narrowed.

  • Slumped Spine Posture: Cervical spine superimposes over the midline as a dense, triangular radiopacity obscuring the anterior teeth.

• Systemic Advantages and Disadvantages:

  • Advantages: Broad field of view (captures maxilla, mandible, TMJ, sinuses); technical simplicity; high patient compliance; low relative radiation dose.

  • Disadvantages: Inferior image resolution compared to intraoral radiography; focal trough limitations (structures outside the trough blur); magnification and geometric distortion; high equipment capital cost.

Extraoral Projections and Specialized Skull Radiography

• Core Extraoral Concepts and Hardware:

  • Uses image receptors placed outside the mouth to evaluate large craniofacial sections, growth, skeletal trauma, impacted teeth, TMJ pathology, and expansive lesions.

  • Equipment includes standard dental x-ray tubeheads fitted with beam-indicating devices or dedicated extraoral units utilizing a cephalostat (craniostat) equipped with ear-positioning rods (which must undergo intermediate-level surface disinfection between patients).

  • Utilizes light-tight cassettes with screen film and intensifying screens, digital sensors, or grids.

• Anti-Scatter Grids:

  • An apparatus positioned between the patient's head and the image receptor.

  • Fabricated from alternating thin lead strips embedded in an x-ray-permeable matrix.

  • Absorbs scattered x-rays while permitting primary parallel rays to reach the film, improving contrast resolution at the expense of requiring increased patient exposure time.

• Lateral Jaw Projections:

  • Body of the Mandible:

  • Purpose: Evaluates fractures, cysts, tumors, and impacted teeth within the mandibular body.

  • Receptor Placement: Flat against the cheek, centered over the mandibular body.

  • Patient Head Position: Head tilted $15^\circ$ toward the side being radiographed; chin elevated and extended forward.

  • Beam Alignment: Directed from below the inferior border of the opposite mandible at a vertical angulation of $-15^\circ$ to $-20^\circ$, perpendicular to the horizontal plane of the receptor.

  • Ramus of the Mandible:

  • Purpose: Evaluates large lesions, fractures, and impacted third molars extending into the ramus.

  • Receptor Placement: Flat against the cheek, centered over the mandibular ramus.

  • Patient Head Position: Head tilted $15^\circ$ toward the side being imaged; chin elevated and extended.

  • Beam Alignment: Directed posterior to the third molar area at a vertical angulation of $-15^\circ$ to $-20^\circ$.

• Cephalometric and Skull Projections:

  • Lateral Cephalometric Projection:

  • Purpose: Analyzes skeletal growth and development, craniofacial relationships, orthodontic dentofacial relationships, and trauma.

  • Receptor Placement: Vertical, perpendicular to the floor, long axis horizontal.

  • Patient Position: Left side of the head adjacent to the receptor; midsagittal plane perpendicular to the floor; Frankfort plane parallel to the floor.

  • Beam Alignment: Central ray directed perpendicular to the receptor.

  • Posteroanterior (PA) Projection:

  • Purpose: Evaluates facial asymmetry, disease, trauma, and transverse craniofacial growth.

  • Patient Position: Forehead and nose directly contact the receptor face; midsagittal plane perpendicular to the floor; Frankfort plane parallel to the floor.

  • Beam Alignment: Central ray directed perpendicular to the receptor.

  • Waters Projection:

  • Purpose: Dedicated visual assessment of the maxillary sinuses.

  • Patient Position: Chin rests against the receptor; tip of the nose positioned $0.5$ to $1.0\,\text{inch}$ away from the receptor face; midsagittal plane perpendicular to the floor; canthomeatal line forms an angle of $37^\circ$ with the receptor.

  • Beam Alignment: Central ray passes perpendicular to the receptor through the center of the head.

  • Submentovertex (SMV) Projection:

  • Purpose: Identifies the position and orientation of the mandibular condyles, demonstrates the base of the skull, and detects fractures of the zygomatic arches.

  • Patient Position: Head tilted back into hyperextension; vertex (top of the head) contacts the receptor; midsagittal plane and Frankfort plane perpendicular to the floor; canthomeatal line parallel to the receptor.

  • Beam Alignment: Central ray directed through the base of the skull perpendicular to the receptor.

  • Reverse Towne Projection:

  • Purpose: Identifies fractures of the condylar neck and subcondylar region.

  • Patient Position: Head flexed downward; top of the forehead touches the receptor; mouth opened as wide as possible; midsagittal plane perpendicular to the floor; canthomeatal line angled at $-30^\circ$ relative to the receptor.

  • Beam Alignment: Central ray perpendicular through the center of the head.

• Extraoral Bitewing Imaging:

  • Generated using specialized panoramic units programmed to image limited posterior dentoalveolar segments.

  • Eliminates intraoral sensor placement; provides expanded visualization of crowns, interproximal alveolar crests, and marginal periapical structures.

Temporomandibular Joint (TMJ) Radiography

• Anatomical Components:

  • Composed of the glenoid fossa and articular eminence of the temporal bone, the condyle of the mandible, and the fibrous articular disc.

• Transcranial Projection (Lindblom Technique):

  • Purpose: Evaluates the superior joint space, superior surface of the condylar head, and articular eminence.

  • Receptor: Placed flat against the ear, centered directly over the TMJ of interest.

  • Patient Position: Midsagittal plane perpendicular to the floor and parallel to the receptor.

  • Beam Alignment: Directed at an entry point $2\,\text{inches}$ superior and $0.5\,\text{inch}$ posterior to the external auditory meatus; angulated with a vertical angulation of $+25^\circ$ and a horizontal anterior angulation of $20^\circ$.

• TMJ Tomography:

  • Isolates slices through the condyle, eminence, and glenoid fossa at predetermined depths without superimposition.

  • Evaluates condylar translation between open and closed mandibular positions.

• Magnetic Resonance Imaging (MRI):

  • Diagnostic gold standard for comprehensive TMJ evaluation.

  • Employs radiofrequency pulses within a powerful magnetic field to temporarily alter the alignment of hydrogen protons; as protons relax to baseline equilibrium, emitted signals generate high-resolution images.

  • Emits zero ionizing radiation; visualizes hard tissues and soft tissues (articular disc morphology and positional displacement) during active mandibular movement.

Three-Dimensional Digital Imaging (Cone-Beam Computed Tomography - CBCT)

• Physical Fundamentals:

  • Employs a divergent cone-shaped x-ray beam coupled with a flat-panel digital detector that completes a single partial or full $360^\circ$ rotation around the patient's head.

  • Captures a complete volumetric dataset within one scan, eliminating the need for multiple slice acquisitions.

• Reconstruction Planes and DICOM Data:

  • The computer reconstructs raw volumetric projection data into a sequence of axial images, which are further formatted into three orthogonal imaging planes:

  • Axial Plane: Transverse plane dividing superior and inferior portions.

  • Coronal Plane: Frontal plane dividing anterior and posterior portions.

  • Sagittal Plane: Longitudinal plane dividing right and left lateral portions.

  • Combining these views produces Multiplanar Reconstructed (MPR) volumes.

  • Data files are stored and transmitted via the standardized DICOM (Digital Imaging and Communications in Medicine) protocol.

• Comparative Radiation Dosimetry:

• Professional Standards and Accreditation:

  • American Academy of Oral and Maxillofacial Radiology (AAOMR): Explicitly recommends that CBCT datasets be interpreted by a board-certified oral and maxillofacial radiologist.

  • Intersocietal Accreditation Commission (IAC): Non-profit organization that establishes clinical guidelines and operational standards for quality assurance and patient safety in dental computed tomography.

• Clinical Applications:

  • Pre-surgical dental implant assessment and dynamic computer-guided surgery.

  • Precise spatial localization of impacted teeth, supernumeraries, and their proximity to vital neurological structures (e.g., inferior alveolar nerve canal).

  • Endodontic root canal morphology analysis, internal/external resorption, and periapical lesion evaluation.

  • Airway analysis, sleep apnea evaluation, and paranasal sinus assessments.

  • TMJ osseous pathology and condylar morphology assessment.

  • Orthodontic treatment planning and skeletal asymmetry mapping.

  • Identification and volumetric boundary mapping of maxillofacial cysts, fibro-osseous lesions, and benign or malignant tumors.

  • Evaluation of maxillofacial fractures and traumatic dental injuries.

• Patient Acquisition Protocol:

  • Patient is seated, standing, or placed supine depending on the unit architecture.

  • Removal of all head and neck metallic objects, glasses, earrings, removable dental prostheses, and hair accessories.

  • Bite guides or separation wafers stabilize the arches and maintain incisal edge separation.

  • Head immobilized via chin cups, forehead rests, and lateral temple supports aligned with laser positioning lights.

  • Scan durations range between $7$ and $30\,\text{seconds}$, during which the patient must remain completely still.

• Advantages and Limitations:

  • Advantages: Lower effective radiation dose than medical fan-beam CT; rapid scanning times ($7\text{--}30\,\text{seconds}$); eliminates magnification artifacts; true $1:1$ anatomical scaling; simple DICOM transportability.

  • Disadvantages: Susceptible to patient motion artifacts; beam-hardening artifacts caused by metallic restorations; restricted field of view options; high initial purchase cost; operator liability requiring comprehensive interpretation of all visualized structures outside the dental arches.