Dental Radiography and Anatomical Landmarks

Radiopaque: Denser structures that absorb more X-rays, appearing lighter or whiter. Examples include Enamel, Bone, and Metal restorations.
Radiolucent: Less dense areas that allow X-rays to pass through easily, appearing darker or black. Examples include Soft tissue, Pulp, and cysts or lesions.
Tooth Structure Labeling:
- $1.$ Enamel
- $2.$ Dentin
- $3.$ Dentin
- $4.$ Pulp/pulp chamber
- $5. \& 6.$ PDL
- $7.$ Crest of the Alveolar bone

Embossed Dot: A dot on the film packet used to determine orientation. The dot should face the X-ray beam and be placed toward the incisal or occlusal surface. When mounting, keep dots facing the same direction.
Labial Mounting: Recommended by the CDA. The raised side of the dot ("pimple") faces the viewer. The radiograph is viewed as if looking at the client (client's left is viewer's right).
Lingual Mounting: Not recommended. The depressed side of the dot ("dimple") faces the viewer. Viewed as if the radiographer were inside the mouth looking out (client's right is viewer's right).
Curve of Spee: The anatomic curve of the occlusal alignment. On a mount, this appears as an upward smile line extending from the midline to the posterior.

Radiopaque Landmarks:
- Nasal Septum: Dense cartilage separating the right and left nasal fossa.
- Anterior Nasal Spine: V-shaped projection from the floor of the nasal fossa.
- Inverted Y: Important landmark in the canine/premolar area; the border where the nasal fossa and maxillary sinus meet.
- Zygomatic Process of the Maxilla: Broad U-shaped band above the roots of the first and second molars.
- Other: Maxillary tuberosity (rounded end of alveolar process), Hamulus (hook-shaped), and Coronoid process of the mandible (sometimes visible overlapping the maxilla).
Radiolucent Landmarks:
- Median Palatine Suture: Thin line at the midline of the palate between central incisors.
- Incisive Foramen: Round or pear-shaped opening near the apices of central incisors.
- Maxillary Sinus: Large air chamber visible from canines to molars.
- Lateral Fossa: Depression in the lateral incisor area.

Radiopaque Landmarks:
- Genial Tubercles: Four small bony crests appearing as a radiopaque donut at the midline below central incisor apices.
- Mental Ridge: Ridge of bone appearing as a broad band below the canine and incisor apices.
- External Oblique Ridge: Continuation of the ramus border appearing as a band of varied width on top.
- Internal Oblique Ridge (Mylohyoid Ridge): Radiopaque line parallel and below the external oblique ridge.
Radiolucent Landmarks:
- Lingual Foramen: Small circular area (the "donut hole") surrounded by genial tubercles.
- Mental Foramen: Small opening near the apices of the premolars.
- Nutrient Canals: Thin lines of uniform width often seen in the anterior or edentulous areas.
- Submandibular Fossa: Irregular shaped area below the mylohyoid ridge where bone is thin; may be mistaken for a lesion.

Darkroom/Safe Light: Must be $4\,ft$ away from the working surface. Bulb wattage is $15\,W$ ( $7-10\,W$ for extraoral).
Processing Issues: Overdeveloped films appear dark (solution too hot); underdeveloped films appear light (solution too cold).
Digital Imaging: Uses CCD (Charge coupled device) or PSP (Photo Stimulate Phosphors/Storage Phosphor Plate).
Exposure Efficiency: Digital radiography reduces radiation exposure by $50\%-90\%$ compared to film ( $0.05\,s$ for digital vs. $0.2\,s$ for film).
Bit-depth: The number of possible gray-scale combinations for each pixel. An $8$ -bit depth provides $2^8 = 256$ shades.
Quality Control: Ensure the Ala-Tragus line and occlusal plane are parallel with the floor for better image quality.