TL;DR

Key Facts

What Is It?

Dental and maxillofacial radiography encompasses a wide range of imaging techniques used to visualise the teeth, jaws, skull, paranasal sinuses, temporomandibular joints, and associated structures. These techniques vary in their spatial resolution, field of view, radiation dose, technical complexity, and clinical indications — from the small intraoral periapical film that shows a single tooth in exquisite detail to the cone beam CT that generates a full 3D volume of the entire skull.

Understanding the types of radiography available — and, critically, which type is appropriate for each clinical question — is a fundamental competency for every dental clinician. Selecting the right imaging study delivers the diagnostic information needed at the lowest achievable patient dose, in accordance with the ALARA principle (As Low As Reasonably Achievable).

This article provides a systematic overview of all major dental radiographic types, their technical basis, indications, advantages, limitations, and comparative radiation doses.

Why It Matters

Radiographic diagnosis is integral to virtually every aspect of dental practice — from detecting early interproximal caries to planning complex implant surgery, from assessing root morphology before extraction to evaluating condylar fractures after trauma. No clinical examination alone can substitute for the information that radiographs provide.

Clinical Relevance

• Matching imaging to clinical question: a clinician who understands all available radiographic types can select the optimal imaging pathway — avoiding over-investigation (unnecessary dose) and under-investigation (missed diagnosis).
• Exam relevance: the INBDE tests recognition of radiograph types, their indications, and their limitations as a core component of radiology.
• Radiation justification: under radiation protection regulations, the choice of imaging type must be clinically justified. A CBCT cannot be prescribed “routinely” — it requires a specific clinical indication where 3D information will change diagnosis or treatment.
• Referral competency: general dentists must know when to perform, when to request, and when to refer for specialist radiographic imaging.

Intraoral Radiography

Intraoral radiographs place the receptor inside the patient’s mouth. They provide the highest spatial resolution of any dental imaging technique (up to 20+ line pairs per mm) and are the gold standard for detecting dental caries, periapical pathology, root morphology, and bone levels around individual teeth. Three subtypes are used in clinical practice: periapical, bitewing, and occlusal radiographs.

Periapical Radiograph

The periapical (PA) radiograph is designed to image an entire tooth from its crown to the root apex, along with at least 2–4 mm of surrounding periapical bone. It is the single most information-rich intraoral film for tooth-specific diagnosis.

• Receptor: Size 0, 1, or 2 intraoral film, PSP plate, or CCD/CMOS sensor
• Technique: Paralleling technique (preferred — receptor parallel to tooth long axis, beam perpendicular to both) or bisecting-angle technique (beam bisects the angle between tooth and receptor)
• What it shows: Entire tooth from crown to apex; periapical bone; periodontal ligament space; lamina dura; root morphology
• Indications: Periapical pathology (abscess, granuloma, cyst); endodontic diagnosis and treatment monitoring; root morphology assessment; pre-extraction evaluation; implant site assessment; periodontal bone loss around individual teeth
• Dose: ~1–8 μSv per film (digital: ~1–3 μSv)
• Limitation: Limited to 1–2 teeth per film; cannot survey the full arch in a single exposure

Bitewing Radiograph

The bitewing radiograph images the crowns of the upper and lower posterior teeth simultaneously on a single receptor, making it the gold standard for detecting interproximal caries and assessing crestal bone height in the posterior regions.

• Receptor: Size 2 (horizontal or vertical) intraoral film, PSP plate, or sensor with bitewing tab or holder
• Technique: Patient bites gently on the tab or holder; beam directed through the interproximal contacts at approximately +8–10° vertical angulation
• What it shows: Crowns and coronal thirds of roots of upper and lower posterior teeth simultaneously; interproximal contacts; crestal bone height; restoration margins
• Horizontal bitewing: Primary use is interproximal caries detection and restoration assessment
• Vertical bitewing: Greater coverage of root structure and crestal bone — preferred in periodontal disease monitoring
• Indications: Interproximal caries detection (most sensitive 2D technique); crestal bone assessment; secondary caries under existing restorations; restoration margin evaluation
• Dose: ~1–5 μSv per film (digital)
• Limitation: Shows crown level only — root apices are not visible; cannot diagnose periapical pathology

Occlusal Radiograph

The occlusal radiograph uses a large receptor (Size 4, 57 × 76 mm) placed flat in the occlusal plane — the patient bites gently on it — to provide a broad cross-sectional view of either the maxillary or mandibular arch. It is the only intraoral technique that surveys an entire arch in a single exposure.

• Receptor: Size 4 (57 × 76 mm) intraoral film or PSP plate
• Technique: Patient bites on the receptor; beam directed from above (maxillary occlusal) or from below the chin (mandibular occlusal)
• What it shows: Broad cross-sectional view of the arch; maxillary or mandibular teeth and supporting bone; palate; floor of mouth structures
• Indications: Supernumerary or unerupted teeth; dentigerous cysts; mandibular fractures (cross-sectional view); salivary gland calculi (sialoliths) in the floor of the mouth; cleft palate assessment; trauma
• Dose: ~4–8 μSv per film
• Limitation: Lower resolution per tooth than periapical films; largely supplemented by OPG and CBCT in modern practice but remains useful for specific indications

Extraoral Radiography

Extraoral radiographs place the receptor outside the patient’s mouth. They provide broader coverage of the jaws, skull, sinuses, and facial skeleton at the cost of lower resolution per tooth. They supplement — but do not replace — intraoral radiographs for tooth-specific diagnosis. Multiple subtypes are used in clinical dentistry, each optimised for a different anatomical region or clinical question.

Panoramic Radiograph (OPG / OPT)

The panoramic radiograph (orthopantomogram, OPG or OPT) is the most widely used extraoral view in general dental practice and provides a single broad survey image of both jaws, all teeth, and surrounding structures.

• Principle: Rotational tomography — the X-ray tube and receptor rotate simultaneously around the patient in opposite directions; only the curved focal trough is rendered in sharp focus, producing a flattened panoramic image of the dental arches
• What it shows: All teeth and both jaws; TMJs; maxillary sinuses; nasal fossa; inferior alveolar canal; hyoid bone; cervical spine (partial); styloid processes
• Indications: Third molar assessment (most common); new patient survey; jaw pathology (cysts, tumours); orthodontic and implant screening; trauma overview; assessment of developing dentition
• Limitations: Insufficient resolution for reliable caries detection; not a substitute for periapical films for periapical diagnosis; positioning errors produce ghost images and blurring; variable magnification across the image; curved focal trough means areas outside it are blurred
• Dose: ~14–24 μSv

Lateral Cephalometric Radiograph

The lateral cephalometric radiograph is a standardised lateral skull projection taken with a cephalostat, providing reproducible craniofacial geometry for cephalometric analysis.

• Principle: Standardised lateral skull radiograph taken with a cephalostat (ear rods fix the patient’s head); fixed source-to-patient-to-receptor geometry ensures reproducibility for serial measurements
• What it shows: Entire craniofacial skeleton in lateral projection; hard and soft tissue profile; airway outline; cervical vertebrae
• Indications: Orthodontic diagnosis and treatment planning; growth assessment (serial cephalometry); orthognathic surgery planning; airway analysis; sleep-disordered breathing assessment
• Key measurements: SNA (~82°), SNB (~80°), ANB (~2°), mandibular plane angle (FMA ~25°), incisor inclinations (upper incisor to NA, lower incisor to NB)
• Dose: ~5–6 μSv
• Limitation: 2D projection of a 3D structure; cephalostat required for measurements; soft tissue profile accuracy depends on image quality and tracing technique

Posteroanterior (PA) Cephalometric Radiograph

The PA cephalometric view provides the frontal complement to the lateral ceph, allowing assessment of transverse skeletal relationships and facial symmetry.

• Principle: Frontal (PA) projection with cephalostat; standardised geometry ensures reproducible measurements in the transverse and vertical planes
• What it shows: Facial width; midline symmetry; transverse skeletal relationships; nasal cavity; orbits; frontal and ethmoid sinuses
• Indications: Facial asymmetry assessment; transverse skeletal discrepancy; midline deviation; complement to lateral cephalometric analysis in complex orthodontic and orthognathic cases
• Dose: ~3–5 μSv
• Limitation: Frontal plane only; limited detail for tooth-specific diagnosis; cephalostat required

Waters View (Occipitomental, OM)

The Waters view is the standard plain film projection for assessing the maxillary sinuses and orbital floors, and is a key view in facial trauma assessment.

• Principle: PA projection with the chin elevated approximately 45° to the orbitomeatal line (OML); this angulation projects the petrous ridges of the temporal bones below the maxillary sinuses, allowing unobstructed sinus visualisation
• What it shows: Maxillary sinuses; orbital floors and infraorbital rims; nasal cavity; zygomatic bodies; frontal sinuses (partially); hard palate
• Indications: Maxillary sinusitis (air-fluid level, opacification, mucosal thickening); orbital floor blowout fractures (teardrop sign — herniation of orbital contents into the maxillary sinus); Le Fort fractures (I, II, III); zygomatic body fractures
• Dose: ~10–15 μSv
• Limitation: Not suitable for tooth-specific diagnosis; cannot fully assess the zygomatic arch (SMV required); increasingly replaced by CT in major trauma centres

Reverse Towne’s View

The Reverse Towne’s view is the dedicated plain film projection for the condylar heads and necks, and is the key view for assessing condylar and subcondylar fractures.

• Principle: PA projection with the beam angled approximately 30–35° caudally, directed from behind the patient through the occiput; this angulation projects the condyles free of the petrous portions of the temporal bones
• What it shows: Condylar heads and necks bilaterally; glenoid fossae; subcondylar region; bilateral condylar comparison
• Indications: Condylar and subcondylar fractures (primary indication); bilateral condylar comparison; condylar height assessment; displaced versus non-displaced condylar fractures
• Dose: ~15–25 μSv
• Limitation: Condylar region only — not suitable for tooth or sinus assessment; typically used in combination with OPG for condylar fracture assessment; largely replaced by CBCT in specialist centres

Submentovertex (SMV) View

The submentovertex view provides an axial (from below) projection of the skull base and zygomatic arches, and is the dedicated view for zygomatic arch fractures.

• Principle: The beam is directed vertically upward from beneath the chin toward the vertex of the skull; the patient must be positioned with the neck in full hyperextension so the infraorbitomeatal line is parallel to the receptor
• What it shows: Zygomatic arches bilaterally (primary use); skull base anatomy; sphenoid sinuses; condyles in axial plane; mandibular rami; foramen ovale; foramen spinosum
• Indications: Zygomatic arch fractures (primary indication — the “bucket handle” or “W” deformity on SMV); base of skull anatomy; sphenoid sinus; axial condylar position
• Contraindications: Uncleared cervical spine injury — the required hyperextension is contraindicated until the cervical spine has been cleared
• Dose: ~15–20 μSv
• Limitation: Requires full neck hyperextension; contraindicated with cervical injury; provides axial plane only; largely replaced by CT in major trauma centres

Cone Beam Computed Tomography (CBCT)

CBCT is the 3D imaging modality of choice in dentistry, generating volumetric data sets that can be reformatted in any plane. It represents a fundamentally different class of radiography — offering true 3D anatomical information at doses that, while higher than 2D techniques, are far lower than conventional medical CT.

• Principle: A cone-shaped X-ray beam rotates around the patient (typically 180–360° rotation); a flat-panel detector captures projection data; volumetric 3D data is reconstructed via algorithms into axial, coronal, and sagittal planes — any cross-section or 3D rendering is possible
• What it shows: 3D volumetric data of the dentofacial complex, the extent of which depends on the field of view (FOV) selected
• Field of view:
  • Small FOV (single tooth to one quadrant): highest resolution; used for endo, implants, impacted teeth
  • Medium FOV (one jaw): used for implant planning across an arch, jaw pathology
  • Large FOV (full skull + airway): orthognathic surgery, craniofacial anomalies, airway analysis
• Indications: Implant planning (bone volume, nerve proximity); complex impacted teeth (inferior alveolar nerve proximity assessment); complex endodontics (extra canals, root resorption); orthognathic surgery planning; jaw cysts and tumours; TMJ bony pathology; airway analysis; craniofacial anomalies; sinus assessment for implant planning
• Dose: Small FOV ~20–100 μSv; medium FOV ~40–200 μSv; large FOV ~100–600 μSv
• Limitations: Higher dose than all 2D techniques; must be clinically justified — not a routine screening tool; soft tissue contrast is poor (MRI preferred for soft tissue); scatter and beam hardening artefacts; higher cost and equipment requirements

Transcranial TMJ View

The transcranial view is a lateral oblique projection of the temporomandibular joint taken with the mouth open and closed, showing the condylar head position and range of movement. It is a plain film technique that has been largely superseded by CBCT (for bony pathology) and MRI (for disc and soft tissue assessment).

• What it shows: Condylar head morphology in lateral oblique projection; open vs closed condylar position; gross bony changes (osteophytes, flattening, erosion)
• Indications: Historical assessment of TMJ bony changes; now largely replaced in specialist practice by CBCT and MRI
• Dose: ~5–10 μSv per side
• Limitation: Oblique projection introduces distortion; cannot assess disc or soft tissue structures; requires specialist equipment and technique; largely replaced by CBCT and MRI

Comparative Overview — All Radiograph Types

The following master table summarises all major radiographic types for rapid INBDE review. The “Best For” column is the highest-yield column for examination purposes.

Clinical Considerations

Choosing the right radiographic investigation is as important as any other clinical decision. The following principles guide appropriate radiographic selection in clinical practice.

• Sequencing radiographic investigations: for most clinical scenarios, start with the lowest-dose, highest-resolution option appropriate to the question. For tooth-specific questions: intraoral films first. For jaw-wide screening: OPG. For 3D questions: CBCT only when 2D is insufficient and the 3D information will change management.
• Selection criteria: the ADA/FDA guidelines provide evidence-based patient selection criteria based on age, caries risk, and clinical findings. Not every patient at every visit needs radiographs — and not every clinical question requires CBCT.
• Combination views in trauma: facial trauma typically requires a combination of views. Standard approach: OPG + PA mandible for mandibular fractures; OPG + Reverse Towne’s for condylar fractures; Waters + OM 30° for midface/orbital fractures; SMV for zygomatic arch. CBCT is increasingly replacing plain film series in major trauma centres where CT is immediately available.
• Consent and communication: patients should understand what each radiographic type shows, why it is indicated, and what the radiation dose is. Evidence-based dose comparisons (e.g., “equivalent to one to two days of background radiation”) aid informed consent and patient understanding.
• Digital radiography: almost all modern dental radiography is performed digitally — PSP (photostimulable phosphor) plates or CCD/CMOS intraoral sensors for intraoral; flat-panel detectors for extraoral and CBCT. Digital systems offer dose reductions of 50–80% compared to conventional film, immediate image review, electronic storage, and software enhancement tools — all relevant to optimising the imaging approach and minimising patient dose.

Common Mistakes & Misconceptions

Several persistent misconceptions about radiographic types lead to suboptimal imaging choices in clinical practice. Understanding these errors is essential for INBDE preparation and for safe clinical practice.

• Misconception: “The OPG can replace bitewings and periapical films for routine dental assessment.”
  Correction: The OPG is a screening tool. It cannot reliably detect early interproximal caries (bitewings required) or fine periapical changes (periapical films required). The resolution of the OPG is fundamentally limited by its rotational tomographic principle. Intraoral and panoramic radiographs are complementary, not interchangeable.
• Misconception: “CBCT should be used whenever detailed jaw information is needed.”
  Correction: CBCT delivers significantly more radiation than 2D techniques (up to 600 μSv for large FOV) and must only be used when the 3D information will meaningfully change diagnosis or treatment planning. For routine caries detection, bone level assessment, or periapical diagnosis, 2D radiography is appropriate and sufficient.
• Misconception: “Extraoral radiographs always provide less dose than intraoral films.”
  Correction: While individual intraoral films are low-dose (1–8 μSv), extraoral views such as large FOV CBCT (100–600 μSv) and skull projections (15–25 μSv each) can deliver substantially more dose. The appropriate comparison is dose per clinical indication answered, not simply dose per exposure.
• Misconception: “Digital radiography eliminates the need to minimise exposure time and use rectangular collimation.”
  Correction: Digital sensors are more sensitive than film, but ALARA still applies. Unnecessary dose should still be minimised through rectangular collimation (reduces dose by up to 60% compared to round collimation), appropriate exposure settings, patient selection criteria, and avoiding unnecessary retakes — even in fully digital practices.
• Misconception: “Any lateral skull radiograph can be used for cephalometric analysis.”
  Correction: Cephalometric analysis requires a standardised lateral skull radiograph taken with a cephalostat — ensuring fixed, reproducible source-to-patient-to-receptor geometry. An unstandardised plain lateral skull view cannot be used for cephalometric measurements because the geometry cannot be controlled or reproduced.

Related Topics

Types of radiography connects closely with the following subjects in dental radiology and clinical practice.

References & Sources

The following foundational texts and peer-reviewed sources inform this article.

1. White SC & Pharoah MJ, 2014. Oral Radiology: Principles and Interpretation. 7th ed. Elsevier Mosby.
2. Whaites E & Drage N, 2013. Essentials of Dental Radiography and Radiology. 5th ed. Churchill Livingstone.
3. ADA Council on Scientific Affairs, 2012. Dental Radiographic Examinations: Recommendations for Patient Selection and Limiting Radiation Exposure. American Dental Association.
4. NCRP Report No. 145, 2003. Radiation Protection in Dentistry. National Council on Radiation Protection and Measurements.
5. Ludlow JB & Ivanovic M, 2008. Comparative dosimetry of dental CBCT devices and 64-slice CT. Oral Surgery, Oral Medicine, Oral Pathology, 106(1):106–114.
6. Bushong SC, 2017. Radiologic Science for Technologists. 11th ed. Elsevier.

Summary

Dental radiography is not a single technique but a comprehensive toolkit of imaging methods, each designed to answer specific clinical questions at specific radiation doses. Intraoral techniques — periapical, bitewing, and occlusal — deliver the highest spatial resolution and are the foundation of tooth-specific diagnosis. Extraoral techniques — panoramic, cephalometric, skull projections, and CBCT — extend coverage to the full jaws, skull, sinuses, and 3D anatomy, at progressively higher doses.

Mastery of the types, their indications, and their limitations allows the clinician to always select the right tool for the right question at the right dose. The ALARA principle is not a bureaucratic requirement — it is a clinical ethic that demands every radiographic decision be made with the patient’s best interest and radiation safety in mind.

About the Author

Dr. Andries Smith

Founder, Dental Panda

Dr. Andries Smith founded Dental Panda in 2020. As an immigrant to the United States, he had to take the INBDE exam, even though he was practicing dentistry for over 10 years. This revealed an opportunity. Andries noticed that INBDE prep course companies were putting profit over students. With his expertise and experience in dentistry, he created free dental wiki resources for students and the general public to have access to.