Xray - Outcome 7

Question 1

Film Mounting

Answer 1

The mounting of processed dental radiographs is another important function of the dental auxiliary. It is much easier for the dentist to view and diagnose radiographs when the films are placed in mounts in their anatomic orientation. Properly mounted films make charting and examination a much more accurate procedure. The mounted films are kept with the patient’s chart and are placed on the view box for reference at each visit. Radiographs are identified and oriented as to position in the mouth by the tooth and bony structures visible on each film. A thorough understanding of radiographic anatomy will make mounting easier.

Question 2

Mounts

Answer 2

Various types of dental mounts are available. They are usually made of either cardboard, plastic, or celluloid-like material, with the desired number of windows for the placement of radiographs. They are available in standard, ready made, or can be customized to suit special needs. Black mounts make viewing of the radiographs easier due to the contrast with the grayscale of the radiographs.

Question 3

There are 2 distinct shade you will see on a radiograph

Answer 3

Radiolucent : refers to structures that are less dense, therefore the xray beam passes through them easily, causing the image to appear black or dark

Radiopaque: refers to structures that are dense and to not allow passage of the xray beam, this causes the image to appear light or white.

Question 4

Anatomical Landmarks

Answer 4

Anatomical landmarks are those normal structures and areas which appear in a routine series of radiographs. These structures will not appear with the same clarity for all patients. These images may vary depending on exposure techniques and patient anatomy.

Question 5

Anatomical Landmarks are identified through..

Answer 5

These structures are identified through the varying shades of gray (grayscale).

Question 6

Appearance of Enamel & Dentin on Xray

Answer 6

When a radiograph has been correctly exposed and processed, there is a difference in density between the enamel and underlying dentin. Just underneath the enamel is the dentin, which extends from the crown into the root. Dentin is not as hard or dense as enamel, but it is still radiopaque. In a correctly exposed and processed radiograph, dentin appears lighter than the underlying pulp but darker than the overlying enamel (Enamel is most radiopaque of all)

Question 7

Cementum & Pulp Tissue on a Xray

Answer 7

. The root of the tooth is covered with a thin layer of cementum, which is not visible radiographically. The pulp tissue is not visible on the radiograph but is represented by a dark space within the tooth. It appears dark because it is composed of soft tissue through which x-rays readily penetrate to the film. The canal extends from the crown of the tooth through to the root apex.

Question 8

Supporting Structures/Bone on a Radiograph

Answer 8

he supporting structures of the teeth are also evident on all radiographs. Bone is usually less dense than enamel and therefore, usually appears grey. The maxilla and the mandible are made up of two types of bone. Cortical bone known as the lamina dura appears white (radiopaque) because of its dense structure. This is the bone that immediately surrounds and supports the tooth and forms a continuous white (radiopaque) line around the alveolus. The remaining bone is much less dense because it has marrow spaces within its structural make-up. This is a cancellous bone and appears less radiopaque than the cortical bone. It appears as irregularly shaped lines in random patterns

Question 9

The PDL on an Radiograph

Answer 9

Between the root of the tooth and the lamina dura is a fine, continuous, dark line (radiolucent) that is an attachment of the tooth to the bone, called the periodontal ligament space. The periodontal ligament itself is not visible on the radiograph

Question 10

Common Landmarks of the Maxillary Arch: Central-Lateral Incisor Area

Answer 10

The oval-shaped radiolucent area located between the apices of the central incisors is the incisive foramen. It may be oval, round, heart-shaped, small or large.

Extending in the mid-line between the maxillary centrals is a radiolucent line that extends posteriorly through the midline of the palate. This is the median palatine suture that marks the junction of the right and left palatine bones.

The nasal fossae (air spaces) one on each side of the midline of the face, divided by the bony nasal septum are two radiolucent areas divided by a radiopaque band.

Nasal septum (radiopaque).

Question 11

Common Landmarks of the Maxillary Arch: Cuspid Area

Answer 11

-The maxillary sinus makes its appearance. It is an air space and appears as a radiolucent area.

-An inverted – Y is an important anatomical landmark. It is especially useful in locating the maxillary cuspid area in edentulous surveys. It is formed by the anterior wall of the maxillary sinus and the floor of the nasal fossa.

Question 12

Common Landmarks of the Maxillary Arch: Bicuspid Area

Answer 12

-Maxillary sinus is one of the paranasal sinuses. The lower half of the maxillary sinus is revealed on a radiograph as a dark shadow. The margin of the cavity is a thin layer of dense bone that appears as an irregular white line. Although it may not always look like it on the radiograph, there is usually a lamina dura surrounding the apices adjacent to the floor of the sinus.

-The sinus sometimes extends down between the roots of the maxillary posterior teeth, especially the lingual and buccal roots of the first molars, which may give the appearance that one or more roots protrude into the sinus.

Question 13

Common Landmarks of the Maxillary Arch: Molar Area

Answer 13

-Maxillary sinus is one of the paranasal sinuses. The lower half of the maxillary sinus is revealed on a radiograph as a dark shadow. The margin of the cavity is a thin layer of dense bone that appears as an irregular white line. Although it may not always look like it on the radiograph, there is usually a lamina dura surrounding the apices adjacent to the floor of the sinus.

-The sinus sometimes extends down between the roots of the maxillary posterior teeth, especially the lingual and buccal roots of the first molars, which may give the appearance that one or more roots protrude into the sinus.

-The posterior border of the maxillary sinus. A prominent landmark is the zygomatic bone which appears as a U-shaped radiopacity in the apical region of the first and second molar, and is usually superimposed over the molar root tips. The limbs of the “U” represent the lateral walls of the sinus where the anterior and posterior portions meet.

-Other radiopaque structures seen are the maxillary tuberosity

-The hamular process (hook-like process) both of which are composed mostly of cancellous bone.

-The coronoid process of the mandible is sometimes visible as well (5). Metallic restorations (6) are also visible on 2.6 and 2.7.

Question 14

Landmarks of the Mandibular Arch: Central-Lateral Incisor Area

Answer 14

The genial tubercles are located on the inner surface of the body of the mandible in the midline.As you will recall, these tubercles are the points of insertion of the genioglossus and geniohyoid muscles. They appear as roundish, localized areas of increased density (radiopaque) with a small, dark (radiolucent) round spot in the middle representing the lingual foramen for the passage of small lingual nutrient vessels.

The ridge of bone located below the apices of the anterior teeth is the oblique ridge. This radiopaque band extends from the midline of the mandible posteriorly to the bicuspid region.

Sometimes, the border of the mandible is also visible.

Question 15

Landmarks of the Mandibular Arch: Cuspid Area

Answer 15

No new landmark of any significance is present in this region.

Sometimes, the posterior extension of the ramus.

The mental foramen lies just inferior to the apices of the bicuspids. The mental foramen conducts the mental vessels and nerves. It appears as a circular radiolucent area. The location varies from the distal of the cuspid to the second bicuspid area, midway between the upper and lower border of the body of the mandible.

Inferior border of the mandible may also be visible

Question 16

Landmarks of the Mandibular Arch: Bicuspid Area

Answer 16

The mental foramen. It may be superimposed over the root apex of either bicuspid and may resemble periapical pathology of pulpal origin or cementoma.

The mylohyoid ridge may appear in this exposure.

The inferior border of the mandible may also be visible.

Question 17

Landmarks of the Mandibular Arch: Molar Area

Answer 17

In this region, there are two opaque lines.

The upper line is a continuation of the ascending border of the mandible and usually ends in the region of the first molar. This is the external oblique ridge which serves as an area for muscle attachment. It is seen as a radiopaque line of varied width and density that passes across the molar region. Remember this ridge is located on the buccal side of the mandible.

Just inferior to this line is the radiopaque mylohyoid ridge which is located on the lingual side of the mandible and serves as the point of attachment for the mylohyoid muscle.

The mandibular canal that usually appears as a narrow dark ribbon between two white lines representing the canal walls. This is a canal carrying nerves and blood vessels; therefore, it appears as a radiolucent canal in the region of the root apices of the molars. The mandibular canal starts at the mandibular foramen on the inner aspect of the ramus and passes in a downward and forward direction through the mandible. As it passes forward, it moves from the lingual side of the mandible to the buccal side in the bicuspid area.

The inferior border of the mandible may also be visible.

Retromolar area, extension of the ramus distal of the third molar.

Question 18

Alveolar Bone on Radiograph

Answer 18

An even texture

Darker in hue than the teeth because it is more radiolucent

Net-like structure of bone trabecula enclosing minute marrow spaces (cancellous bone)

Question 19

Lamina Dura on Radiograph

Answer 19

Appears as a white homogenous line

A thin layer of cortical bone

Constitutes alveolus (tooth socket)

Question 20

Periodontal Membrane Space on Radiograph

Answer 20

Dark line around the root

Space between root and lamina dura

It May be very thin in mature cases

It May appear thin from certain angles

Question 21

Enamel on Radiograph

Answer 21

Tissue with the greatest density

Appears lightest in color

Question 22

Dentin on Radiograph

Answer 22

Less dense than enamel

Appears grey in color

Question 23

Cementum on Radiograph

Answer 23

same density as dentin and therefore not distinguishable

Question 24

Pulp Chamber and Root Canals on Radiograph

Answer 24

appear black

Question 25

Metallic Restoration on Radiograph

Answer 25

appear as white

Question 26

Besides recognizing anatomical landmarks, the auxiliary should be able to identify:

Answer 26

Normal tooth tissues

Restorative materials

Common lesions and pathological conditions

Fractures

Impactions

Tooth abnormalities

Tooth development and eruption

Calculus

Question 27

Caries on Radiograph

Answer 27

Dental caries or cavities are defects in the enamel due to decalcification . X-rays readily penetrate these areas of decalcified enamel; therefore, caries has a radiolucent appearance when seen on a radiograph. Once the lesion penetrates the enamel, it rapidly enlarges in size because of the decreased density of the dentin in comparison with the enamel (

Question 28

Acute and Chronic Periapical Abscesses on Radiograph

Answer 28

These lesions begin to form when the dental pulp of the affected tooth is infected with bacteria, usually from a carious lesion. A blow to a tooth can also cause the pulp to degenerate, leading to abscess formation. Before the effects of an abscess can be seen on a radiograph, the toxic material must pass through the pulp canal to the apical foramen. Once it reaches the apex of the tooth, decalcification takes place in the bony tissue surrounding the apex. Approximately one-third of the bone calcium must be lost before radiographic evidence of an abscess can be seen. The longer the abscess has to develop, the darker it will appear on the radiograph. Abscesses appear as radiolucent areas surrounding the apex of the root

Question 29

Periapical Cysts on Radiograph

Answer 29

An abscessed tooth, if not treated, may develop a root end cyst. The cyst is a sac containing fluid and causes a round cavity formation in the bone. Although the cyst cannot with certainty be distinguished from an abscess when viewing a radiograph, there is one feature that suggests that the lesion is a cyst – the well-defined outline of cortical bone

Question 30

Bone Sclerosis on Radiograph

Answer 30

Excessively light or radiopaque areas of bone represent an increase in the calcification of the bone involved. The greater the calcification, the lighter or more opaque the bone image will appear

There are two basic causes for this type of bone formation. One is the repair of a diseased area that has been resolved, such as a former abscess. The other reason sclerotic bone may be formed is in an attempt to wall off inflammation or spreading infection. The dense bone becomes a line of resistance

Question 31

Periodontal Disease on Radiograph

Answer 31

The first stage of periodontal disease is gingivitis, which is inflammation confined to the gingiva. Because it involves the gingiva, which is soft tissue, the radiograph will appear normal The alveolar bone crest will be at, or close to, the crown-root junction.

If the patient does not seek treatment the disease process will expand to involve the supporting bone and the periodontal membrane. The first radiographic signs are the destruction of the cortical crest and the widening of the periodontal membrane space at the coronal third of the root. As the disease progresses, the supporting bone will be continually destroyed by the infection and the teeth will become loose and may exfoliate

Question 32

Root Tips Retained in Alveolar Bone on Radiograph

Answer 32

During the extraction of a tooth, there is always a possibility that some part of the root may remain in the alveolar bone. The radiographic appearance of a retained root tip may resemble an area of scleritic bone; however, a root tip will usually exhibit a nerve canal and a periodontal membrane space surrounding the radiopacity

Question 33

Root Fracture on a Radiograph

Answer 33

This is not an uncommon injury. A fall or a blow to the mouth is a frequent cause of root fractures. A radiograph is necessary to discern a root fracture. Since the fracture is a separation of two radiopaque segments, you will see a dark line through the root at the area of the fracture

Question 34

Supernumerary Teeth on Radiograph

Answer 34

Some patients have one or more teeth in excess of the normal number. These extra teeth are known as supernumerary teeth. They are most frequently found in the maxillary incisor region and the mandibular bicuspid region. A supernumerary tooth is usually impacted in bone and may prevent the eruption of a permanent tooth

Question 35

Metallic Restorations on Radiograph

Answer 35

Metallic restorations (e.g., amalgam, gold) absorb x-rays, and as a result, very little (if any) radiation comes in contact with the receptor. Consequently, that area of the receptor remains unexposed, and the metallic restorations appear completely radiopaque (light or white) on a dental image.

Question 36

Nonmetallic restorations on Radiograph

Answer 36

Nonmetallic restorations (e.g., porcelain, composite, acrylic) may vary in appearance, from radiolucent (dark or black) to slightly radiopaque, depending on the density of the material. Of the nonmetallic restorations, porcelain is the densest and least radiolucent, and acrylic is the least dense and most radiolucent.

Question 37

Amalgam Restorations on an Xray

Answer 37

Amalgam is one of the most common restorative materials used in dentistry. This mixture of mercury, silver, tin, and copper is a durable and inexpensive filling material. Amalgam absorbs the x-ray beam and prevents x-rays from reaching the receptor; consequently, amalgam appears completely radiopaque on a dental image. Amalgam may be seen in a variety of shapes, sizes, and locations on a dental image.

Question 38

Gold Restorations on an Xray

Answer 38

It is not always possible to differentiate one metallic restoration from another on a dental image; however, an educated guess is often possible if the shape and size of the restoration are considered. Both gold and amalgam appear equally radiopaque on a dental image. A large radiopaque restoration with smooth borders is most likely gold. Gold restorations appear completely radiopaque and, unlike amalgam restorations, exhibit a smooth marginal outline

Question 39

Post and Core Restorations on an Xray

Answer 39

Post and core restorations can be seen in teeth treated with endodontic therapy. The post and core restoration is cast metal and appears as radiopaque as amalgam or gold. Post and core restorations appear radiopaque on a dental image. The core portion of the restoration resembles the prepared portion of a tooth crown, and the post portion extends into the pulp canal

Question 40

Porcelain Restorations on an Xray

Answer 40

A porcelain restoration appears radiopaque on a dental image. Unlike metallic restorations, which appear completely radiopaque, porcelain restorations are slightly radiopaque and resemble the radiodensity of dentin.

Question 41

All-Porcelain Crowns and Bridges

Answer 41

All-porcelain crowns and bridges appear slightly radiopaque on a dental image

Question 42

Raised Dot on Film

Answer 42

Every radiograph has a raised dot to help indicate the film’s orientation. The film packet is placed in the patient’s mouth so that the side with the dot (convex side) is always nearest the occlusal surface of the teeth (Iannucci & Howerton, 2022). The film is positioned in the packet by the manufacturer so that the raised portion of the dot faces the radiography machine when the exposure is made. The position of this ID dot allows the operator to distinguish the patient’s right side from the left side when mounting the processed radiographs

Question 43

Labial Mounting

Answer 43

If you mount the radiograph so that the convex portion of the dot is towards you, you are looking at the films as if you were facing the patient and the patient’s left side is on your right. This is known as labial mounting. All national organizations recommend this method

Question 44

Mounting Arrangement

Answer 44

The radiographs must be arranged just as the teeth in the mouth are. The anterior teeth must be mounted in the middle frames and the posterior teeth in the frames on either side of the mount. The maxillary teeth must be positioned so that the occlusal or incisal edges point downward and the root upward. The mandibular teeth are mounted the opposite way, with the incisal or occlusal surfaces pointing up and the roots pointing toward the bottom of the moun

Question 45

Procedure for Mounting

Answer 45

1. Fully label mount. (criteria to follow)
2. Wash hands to prevent smudging the films. Dry thoroughly.
3. Always handle films by their edges to prevent smudging.
4. Lay out all of the films from the patient’s full-mouth series on the view box.
5. Always arrange the films so that the ID dots are all convex; either in or out.
6. Divide the films into three groups:
   -Anterior periapicals
   -Posterior periapicals
   -Bite-wing
7. The maxillary anterior films are then differentiated from the mandibular anterior on the basis of root and crown shape and anatomic landmarks. The films are placed in their proper position on the mount.
8. The posterior periapicals are placed horizontally and are identified through landmarks.
9. The bite-wing films are easily identified as the crowns of both the upper and lower teeth are seen. The anterior and posterior films are differentiated by the vertical orientation of the film for anterior teeth and the horizontal orientation for posterior teeth.
10. After mounting, check the entire film mount carefully to make sure that no films were accidentally reversed or mounted upside down.

Question 46

Hints To Make Mounting Easier

Answer 46

1. The roots and crowns of the maxillary anterior teeth are larger than those of the mandibular teeth.
2. Maxillary bicuspids usually have two roots while mandibular bicuspids have one root.
3. The maxillary molars generally have three roots; the mandibular molars have two.
4. Most roots curve towards the distal.
5. The large radiolucent areas denoting the nasal fossa or the maxillary sinus indicate that the radiograph is of a maxillary area.
6. The radiolucent mental foramen indicates that the film belongs in the mandibular cuspid- premolar area.
7. The body of the mandible has a distinct upward curve towards the ramus in the molar area.

Question 47

Labeling

Answer 47

At SAIT, each mount should contain the following information:

Name of patient
Date
Number of films actually in the mount including size – i.e. 2 #4 BW
Number of retakes or corrective exposures – i.e. 2 correctives
Name of student–operator
Name of the SAIT Dental Clinic

Question 48

Storage

Answer 48

Diagnostically acceptable films are placed in the appropriate mount, labeled, and then placed in the patient’s chart (file folder type).Unacceptable original exposures are placed in a fully labeled small brown envelope and retained in the patient’s file. Never throw anything out!

There are legal considerations when dealing with radiographs in dentistry. The main considerations are provincial legislation, registration for dental assistants, and risk management. A key component of risk management is patient records. Dental radiographs are considered to be legal documents. It is important that they are accurately mounted, labeled, and maintained.

Radiographs can be used as legal evidence because they provide visible evidence of prior conditions and the nature of the work performed. Duplicate any radiographs being sent to another dentist, a specialist, or an insurance company so the dental office can retain a copy. On the patient’s chart, make a note of when and where the film was sent.

Example: 12/11/95 P.A. 1.6 sent to Mutual Life Ins. for pre-authorization