Radiograph

Question 1

Which type of radiographs are necessary for RCT, why? (4)

Answer 1

Periapaical radographs – may want to shift cone if multiple canals (may overlap) • Determine working lengths. • Locate superimposed structures. • Locate canals. • Evaluate root canal preparation. • Assess adaptation and position of master cone. • Evaluate root canal obturation. • Assess procedural accidents e.g. perforation, separated instruments, ledges.

Question 2

a. List two plain (non-panoramic) views to visualize the paranasal sinuses

Answer 2

Water’s view Caldwell’s view Anson: See page 121 for images

Question 3

Radiographic errors –> cone-cut & how to avoid it? (3)

Answer 3

Check parallelism of cone beam to indicator ring Re-check the assembly of receptor holding device, make sure the entire receptor can be viewed through the indicator ring

Question 4

9 years old boy, unerupted maxillary central incisor 3 radiographic views to aid diagnosis (3)

Answer 4

Periapical, occlusal, lateral cephalogram

Question 5

9 years old boy, unerupted maxillary central incisor Briefly describe the parallax technique (2)

Answer 5

(parallax = shift cone) Take 2 radiographs at different horizontal angles, but same vertical angulation. The object that travels in the same direction as the x-ray tube is positioned lingually; the object that travels in the opposite direction as the xray tube is positioned buccally. (SLOB) • Canine - moved in the same direction as the radiograph did. So palatally displaced.

Question 6

What are the radiographic techniques commonly used in endodontics? What are their benefits? (6m) Big question split into small questions: What are the advantages of bisecting angle?

Answer 6

 Can be used when the patient’s anatomy preclude the use of the paralleling technique.  Positioning of the film is reasonably comfortable and relatively simple and quick.  Diagnostically adequate if angulations are correct.

Question 7

What are the radiographic techniques commonly used in endodontics? What are their benefits? (6m) Big question split into small questions: What are the disadvantages of bisecting angle?

Answer 7

 Periodontal bone levels are poorly represented.  The zygomatic bone often superimpose over the roots of the maxillary molars.  Crowns of teeth are often distorted, thus preventing the detection of proximal caries.  Buccal roots of the maxillary premolars and molars are often foreshortened.

Question 8

What are the radiographic techniques commonly used in endodontics? What are their benefits? (6m) Big question split into small questions: What are the advantages of parellel?

Answer 8

 Geometrically more accurate images produced with little magnification.  The shadow of zygomatic bone stays above the apices of maxillary molar teeth.  Periapical tissues and periodontal bone levels are well represented.  Crowns of teeth are well defined to enable detection of interproximal caries.

Question 9

What are the radiographic techniques commonly used in endodontics? What are their benefits? (6m) Big question split into small questions: What are the disadvantages of parellel?

Answer 9

 Positioning of the film in the oral cavity can be uncomfortable to the patient.  The anatomy of the mouth, such as a shallow flat palate, sometimes make this technique impossible.  The apices of the teeth may appear very near the edge of the film.

Question 10

Name x-ray machine used to take lateral cephalometric; state the expected magnification; name two additional ways to better visualize the soft tissues in the lat ceph

Answer 10

• Cephalostat - 8.8-9% magnification - Aluminum wedge is positioned to attenuate the beam / use digital film

Question 11

Name three x-rays (other than lat ceph) that are indicated for children, and state their usage

Answer 11

• Panoramic: general examination and screening of dentition, observe eruption and presence of teeth, detect any abnormalities - Bitewing: Detect caries - Anterior occlusal: detect and locate objects like supernumerary teeth, check position of impacted teeth

Question 12

List three methods of assessing skeletal maturity.

Answer 12

• Height measurements
• Cervical vertebral maturation status
• Secondary sex characteristics o Female: menstruation = 1 year after peak growth o Male: voice break = 1 year after peak growth • Tooth eruption – (but usually inaccurate) • Hand wrist radiographs (don’t use anymore) o Another type is “middle phalanx of the third finger”

Question 13

How to protect the patients from the radiation for taking radiographs for endo? (suggest at least five ways) (5 marks)

Answer 13

• Use of endoray and parallel technique (less error and distortion) • Use of apex locator to confirm working length prior taking radiograph • Ensure file inserted into canal is in correct position and able to have clear image by using at least # 15 file and place cotton pellet into canal to hold the file • Protection thyroid shield, lead apron • Choice of equipment like high speed F film, long cone, rectangular collimation to reduce radiation exposure • Correct interpretation and diagnosis reduce unnecessary taking

Question 14

How to position the x­ray beam and film when taking a periapical using parallel technique

Answer 14

X-ray beam should be perpendicular to the long axis of the teeth.

Question 15

What is the problem of the xray film for permanent canine and how to correct it?

Answer 15

Size 2 is often too large, leading to bending of the x-ray film. Can use a smaller size – size 1.

Question 16

Radiolucency around the crown of the impacted canine, give 2 differential diagnoses

Answer 16

Dentigerous cyst, odontogenic keratocysts, ameloblastic fibroma, eruption cyst, hyperplastic follicles

Question 17

Identify lamina dura, PDL space and ?? on an x­ray (Resorbing alveolar bone?)

Answer 17

No answers given

Question 18

Advantages of panoramic radiograph compared to full-mouth intraoral radiographic examination(2)

Answer 18

Advantages of panoramic • All the teeth and their supporting structures are shown on one image • The technique is relatively simple • The radiation dose is relatively low • Useful in patients unable to open their mouth

Question 19

DIsadvantages of panoramic radiograph compared to full-mouth intraoral radiographic examination(2)

Answer 19

Disadvantages of panoramic • Soft tissue and air shadows can overlie the required hard tissue structures • Ghost or artifactual shadows can overlie the structures • The overlapping structures can hide odontogenic lesions, particularly in the incisor regions • The image does not display the fine anatomic detail available on periapical radiographs • Unequal magnification and geometric distortion across the image

Question 20

Describe the head alignment when taking panoramic radiograph(4)

Answer 20

Question 21

Bitewing: 3 indications and 2 advantages compared with panoramic (5m)

Answer 21

Indications: • Detection of carious lesions – extent and depth towards bone/pulp, + interproximal • Assessment of existing restorations • Assessment of the periodontal status (bone height) • See shape of pulp chamber Advantages: Clearer image of teeth, especially at interproximal areas. Less distortion of tooth.

Question 22

(On panoramic) Identify i) right posterior wall of max sinus, ii) left mental foramen, iii) left inferior alveolar c,n7 t3d1anal, iv) right mandibular condyle (4)

Answer 22

Not answers given