P. 110

An Urban Experience
J. Gawor1
1Klinika Weterynaryjna Arka, Klinika, Kraków, Poland
Jerzy Gawor DVM PhD, Dipl AVDC, Dipl EVDC, FAVD
Klinika Weterynaryjna Arka, ul. Chlopska 2a Krakow, Poland
Learning objective: Obtaining diagnostic radiograph is necessary to interpret it. The correct way of reading dental radiographs will be presented with presentation of most commonly radiopaque and radiolucent lesions.
Evaluation of dental radiographs starts with appropriate orientation of the image according to established standards.
The key to properly identifying the imaged teeth on standard (analog  lms) radiographs is the embossed dot, which is near one corner of the  lm. When exposing a radiograph on standard radiographic  lms, the convex surface points towards the radiographic tube head when the  lm is properly positioned. It is not possible to obtain a diagnostic radiograph with the  lm in backwards, because of the lead sheet on the back side of the  lm. Therefore, when exposing the  lm, the embossed dot must be facing out of the mouth.
Interpreting dental radiographs starts with the appropriate orientation. First, place the convex side
of the dot towards you. This means you are looking
at the teeth as if your eyes are the x-ray beam. This
step is done for you on most digital systems. The dot should always be located in such a way that it is not superimposed on structures being imaged. When chemical development is performed, place the clip to hold the  lm adjacent to the dot. This will provide an area of interest free of interfering artifacts. Next, rotate the  lm so that the roots are in their natural position (pointing up on maxillary views and down on mandibular). When this is done, it is necessary to determine if it is the left or right side of the patient. For lateral oblique projections (canine, premolar, and maxillary molar teeth) or parallel projections (mandibular molar teeth), the side of the  lm where the more mesial teeth are located indicates the side that was imaged. In other words, if the mesial teeth are on the right side of the  lm, it is an image of the right side of the patient. With other projections, such as dorsoventral (DV) or ventrodorsal (VD) images (i.e incisors or canines), the right side of the mouth is on the left side of the  lm and
vice versa for the left side of the mouth. This is similar to a VD image of the abdomen.
To distinguish between mandibular and maxillary images, certain landmarks should be evaluated.
For mandible the presence of the mandibular canal, mental foramina, mandibular symphysis and ventral mandibular margin (cortex).The most rostral mental foramen is located in the second incisor area, the middle at the level of apex of the second premolar, and the caudal is at the level of the third premolar. In dogs, the mandibular second, third, and fourth premolars and the  rst and second molars should have two roots. In cats there are normally only three teeth caudal to the canine. There are obviously exceptions to these rules (e.g.
third root in a molar, fused roots or the presence of the second premolar in cats, and supernumerary teeth)
In maxilla the presence of palatine  ssures, incisive canal; the conchal crest rostrally and pterygopalatine fossa caudally. The radiopaque line running across the canine root and just dorsally to the roots of the premolars and molars is the nasal surface of the alveolar process of the maxilla. Nasal structures are visible above the conceal crest with symmetric turbinate details. Typical structures for the nasal cavity are the palatine  ssures and incisive foramen. In dogs, the fourth premolar as well as two maxillary molars normally have three roots; however,
the second molar often has fused roots. In cats, the zygomatic arch is typically superimposed on the maxillary cheek teeth.
Normal radiographic anatomy. There are numerous structures within the oral cavity that mimic pathologic states depending on the projection. Knowledge of normal radiographic anatomy will help avoid over interpretation.
Normal alveolar bone will appear gray and relatively uniform throughout the arcade. It is slightly more radiopaque “darker” than tooth roots. In addition, it appears slightly but regularly mottled. Alveolar bone should completely  ll the area between the roots (furcation) and end at the cementoenamel junction (CEJ). The root canals should all be the same width; allowing for differences in the diameters of the root. There should be no radiolucent areas in teeth or bone. A regular thin dark line (periodontal ligament) should be visualized around the roots.
Periodontal disease. Periodontal bone loss results from the combination of bacterial induced in ammation and host response creating osteoclastic resorption of bone. This resorption will result in crestal bone loss to a level below the cementoenamel junction. This decrease
in bone height may also create furcational exposure. Horizontal bone loss is the most common pattern

   108   109   110   111   112