General guidelines for vertical angulations for common dental radiographs in children:

Anterior Teeth

1. Maxillary Central Incisors:
   • Vertical Angulation: +40 to +50 degrees
2. Maxillary Lateral Incisors:
   • Vertical Angulation: +40 to +50 degrees
3. Maxillary Canines:
   • Vertical Angulation: +45 to +55 degrees
4. Mandibular Central Incisors:
   • Vertical Angulation: -10 to -20 degrees
5. Mandibular Lateral Incisors:
   • Vertical Angulation: -10 to -20 degrees
6. Mandibular Canines:
   • Vertical Angulation: -15 to -25 degrees

Posterior Teeth

1. Maxillary Premolars:
   • Vertical Angulation: +30 to +40 degrees
2. Maxillary Molars:
   • Vertical Angulation: +20 to +30 degrees
3. Mandibular Premolars:
   • Vertical Angulation: -5 to -10 degrees
4. Mandibular Molars:
   • Vertical Angulation: -5 to -10 degrees

Digital Radiology

Advances in computer and X-ray technology now permit the use of systems that employ sensors in place of X-ray ?lms (with emulsion). The image is either directly or indirectly converted into a digital representation that is displayed on a computer screen. 

DIGITAL IMAGE RECEPTORS

- charged coupled device (CCD) used
- Pure silicon divided into pixels.
- Electromagnetic energy from visible light or X-rays interacts with pixels to create an electric charge that can be stored.
- Stored charges are transmitted electronically and create an analog output signal and displayed via digital converter (analog to digital converter). 

ADVANTAGES OF DIGITAL TECHNIQUE

Immediate display of images.

Enhancement of image (e.g., contrast, gray scale, brightness).

Radiation dose reduction up to 60%.

Major disadvantage: High initial cost of sensors. Decreased image resolution and contrast as compared to D speed ?lms.

DIRECT IMAGING

- CCD or complementary metal oxide semiconductor (CMOS) detector used that is sensitive to electromagnetic radiation.

- Performance is comparable to ?lm radiography for detection of periodontal lesions and proximal caries in noncavitated teeth.

INDIRECT IMAGING

- Radiographic ?lm is used as the image receiver (detector). 

- Image is digitized from signals created by a video device or scanner that views the radiograph.

Sensors

STORAGE PHOSPHOR IMAGING SYSTEMS

Phosphor screens are exposed to ionizing radiation which excites BaFBR:EU+2 crystals in the screen storing the image.

A computer-assisted laser then promotes the release of energy from the crystals in the form of blue light.

The blue light is scanned and the image is reconstructed digitally.

ELECTRONIC SENSOR SYSTEMS

X-rays are converted into light which is then read by an electronic sensor such as a CCD or CMOS.

Other systems convert the electromagnetic radiation directly into electrical impulses.

Digital image is created out of the electrical impulses. 

RELATIVE RADIO SENSITIVITY OF THE TISSUES

Radiosensitive (2500 r or less kills or seriously injures many cells)

Lymphocytes and lymphoblasts
Bone marrow (myeloblastic and erythroblastic cells)
Epithelium
Germ cells (testes and ovary)

Radioresponsive (2500-5000 r kills or seriously injures many cells)

Epithelium of skin and many appendages.
Endothelium of blood vessels
Salivary glands
Growing bone and cartilage.
Conjunctiva, cornea and lens of eye
Collagen and elastic tissue(fibroblasts themselves are resistant)

Radioresistant (over 5000 r are required to kill or injure many cells)

Kidney
Liver
Thyroid
Pancreas
Pituitary
Adrenal and parathyroids
Mature bone and cartilage
Muscle
Brain and other nervous tissue.

The numbers represent the minimum damaging doses; a gray and a sievert represent roughly the same amount of radiation:
• Fetus--2 grays (Gy).
• Bone marrow--2 Gy.
• Ovary--2-3 Gy.
• Testes--5-15 Gy.
• Lens of the eye--5 Gy.
• Child cartilage--10 Gy.
• Adult cartilage--60 Gy.
• Child bone--20 Gy.
• Adult bone--60 Gy.
• Kidney--23 Gy.
• Child muscle--20-30 Gy.
• Adult muscle--100+ Gy.
• Intestines--45-55 Gy.
• Brain--50 Gy.
 

1. Postero-Anterior (PA) View of Skull

• Head Position: Centered in front of the cassette; canthomeatal line parallel to the floor. For cephalometric applications, the canthomeatal line is 10° above the horizontal, and the Frankfort plane is perpendicular to the film.
• Projection of Central Ray: Passes posterior to anterior, perpendicular to the film.
• Important Features:
  • Used to examine the skull for disease, trauma, and sinuses.
  • Best for viewing the coronoid process; a PA view with a 10° tilt is called the Caldwell projection.

2. Lateral Skull or Cephalometric View

• Head Position: Left side of the face near the cassette; midsagittal plane parallel to the film.
• Projection of Central Ray: Directed towards the external auditory meatus, perpendicular to the film and midsagittal plane.
• Important Features:
  • Assesses facial growth.
  • Reveals soft tissue profile.
  • Surveys skull and facial bones for disease and trauma.

3. Water's Projection

• Head Position: Sagittal plane perpendicular to the film; chin raised so the canthomeatal line is 37° above horizontal.
• Projection of Central Ray: Passes through the maxillary sinus.
• Important Features:
  • Also known as Occipito-mental projection (variation of PA view).
  • Best for demonstrating zygoma fractures, paranasal sinuses, and nasal cavity.
  • Shows the position of the coronoid process between the maxilla and zygomatic arch.

4. Submentovertex (SMV) View

• Head Position: Head and neck extended backward; vertex of the skull at the center of the cassette.
• Projection of Central Ray: Directed towards the vertex of the skull.
• Important Features:
  • Also called BASE, FULL AXIAL, or JUG HANDLE VIEW.
  • Best for viewing the base of the skull and zygomatic arch fractures.
  • Contraindicated in patients with cervical spondylitis.
  • For viewing zygomatic arches, exposure time is reduced to one-third of that used for the skull.

5. Reverse Towne's View

• Head Position: Canthomeatal line oriented 25-30° downward.
• Projection of Central Ray: Directed towards the occipital bone.
• Important Features:
  • Frankfort plane vertically oriented and parallel to the film.
  • Best for viewing condylar neck fractures.
  • Condyles are better visualized if the patient opens their mouth widely.

6. Lateral Oblique Mandibular Body Projection

• Head Position: Tilted towards the side being examined; mandible protruded.
• Projection of Central Ray: Directed towards the first molar region.
• Important Features:
  • Demonstrates the premolar and molar region.
  • Best for viewing the inferior border of the mandible.

7. Lateral Oblique Mandibular Ramus Projection

• Head Position: Tilted towards the side being examined; mandible protruded.
• Projection of Central Ray: Directed posteriorly towards the center of the ramus.
• Important Features:
  • Often used for examining third molar regions of the maxilla and mandible.
  • Provides a view of the ramus from the angle to the condyle.

Age Groups and Radiographs

• Age 2:

  • Anterior IOPA's: 2
  • Posterior IOPA's: 4
  • Bitewings: 2
  • Total Films: 12

• Age 8:

  • Anterior IOPA's: 8
  • Posterior IOPA's: 4
  • Bitewings: 2
  • Total Films: 14

• Age 8 (another entry):

  • Anterior IOPA's: 8
  • Posterior IOPA's: 8
  • Bitewings: 2
  • Total Films: 20

Summary of Total Films by Type

• Anterior IOPA's:

  • Age 2: 2
  • Age 8: 8
  • Age 8 (another entry): 8
  • Total Anterior IOPA's: 18

• Posterior IOPA's:

  • Age 2: 4
  • Age 8: 4
  • Age 8 (another entry): 8
  • Total Posterior IOPA's: 16

• Bitewings:

  • Age 2: 2
  • Age 8: 2
  • Age 8 (another entry): 2
  • Total Bitewings: 6

Overall Total Films

• Total Films for Age 2: 12
• Total Films for Age 8 (first entry): 14
• Total Films for Age 8 (second entry): 20
• Grand Total Films: 12 + 14 + 20 = 46

Bisecting angle technique 

Bisecting angle technique is a method used in dental radiography to obtain radiographs of teeth and surrounding structures. This technique involves positioning the X-ray beam perpendicular to an imaginary line that bisects the angle formed by the long axis of the tooth and the film or sensor. Here are the general guidelines for angulations when using the bisecting angle technique:

Anterior Teeth

1. Maxillary Central Incisors:
   • Vertical Angulation: +40 to +50 degrees
2. Maxillary Lateral Incisors:
   • Vertical Angulation: +40 to +50 degrees
3. Maxillary Canines:
   • Vertical Angulation: +45 to +55 degrees
4. Mandibular Central Incisors:
   • Vertical Angulation: -15 to -25 degrees
5. Mandibular Lateral Incisors:
   • Vertical Angulation: -15 to -25 degrees
6. Mandibular Canines:
   • Vertical Angulation: -20 to -30 degrees

Posterior Teeth

1. Maxillary Premolars:
   • Vertical Angulation: +30 to +40 degrees
2. Maxillary Molars:
   • Vertical Angulation: +20 to +30 degrees
3. Mandibular Premolars:
   • Vertical Angulation: -10 to -15 degrees
4. Mandibular Molars:
   • Vertical Angulation: -5 to -10 degrees

Key Points

• Positioning: The film or sensor should be placed as close to the tooth as possible, and the X-ray beam should be directed perpendicular to the bisecting line.
• Patient Comfort: Ensure that the patient is comfortable and that the film or sensor is properly stabilized to avoid movement during exposure.
• Technique Variability: The exact angulation may vary based on the individual patient's anatomy, so adjustments may be necessary.