The wonderful world of dental radiology

Transcription

1 The wonderful world of dental radiology Dr Christine Hawke BSc(Vet)(Hons) BVSc(Hons) PhD MACVSc (Veterinary Dentistry) PO Box 3001 Willoughby North 2068 Phone: Web: Make the most of the opportunity! Many owners are concerned about the anaesthetic, and the cost associated with dental treatment We need to be thorough when we have the opportunity to assess and treat the mouth, so we can do everything that is needed to remove infection and relieve pain So why is dental radiology so important? Over 2/3 of tooth is below the gumline and not visible without radiographs! Dental radiology is a crucial tool in diagnosis, treatment planning and monitoring response to treatment otherwise we are guessing what is happening, and operating blind 1

2 Okay, tell me more.. In animals with abnormal findings on clinical oral examination, full mouth radiographs showed other undetected pathology in about half of the cases In those with no clinical findings, radiographs showed clinically-important pathology in 27.8% of dogs and 41.7% of cats Verstraete et al. Am J Vet Res : It s not just for advanced cases. Periodontal disease is the most common condition we see in small animal practice, and the real action is happening below the gumline Assessing periodontal disease Looks can be deceiving. 2

3 Dental extractions can be difficult Lack of planning makes them even harder Dental extraction planning Tooth resorption Very common in cats, and very painful Radiographs are critical for assessment and treatment planning Retained roots Resorbing roots 3

4 Missing teeth Missing teeth Fractured teeth 4

5 Discoloured teeth Worn teeth Oral tumours and swellings Courtesy Dr A Caiafa 5

6 So what do we need to take dental rads? 1. Source of xray radiation 2. Something to capture the image 3. Image processing equipment Xray source Dental xray machine Smaller focal spot so more detailed images than standard machines More versatile as can adjust the angle of the head in many directions (horizontal and vertical) Usually have fixed kv and ma so use the timer to adjust exposure (may have preset times) Courtesy Dr A Caiafa Xray source Portable dental xray machines 6

7 Xray source Standard xray machine Settings for a cm focal-film distance (FFD) are around 100 ma, time of 0.1or > sec. Range of KVp from 50 (cat or small dog) up to about 85 (large dog) Can use 100cm FFD and adjust using the inverse square law (double distance = fourfold increase in time) Image capture and processing - film Intraoral (dental) film No intensifying screen so better detail Most commonly used sizes are: Size 2 (31mm x 41mm) eg DF58 Size 4 (57mm x 77 mm) eg DF50 Lead foil Film Black paper Image capture and processing - film Film processing facilities Wet chemicals in darkroom or chairside darkroom Rapid developer and fixer solutions - shortening the developing time to 20 seconds (normally 4 minutes) and fixing time down to 2 minutes (normally 10 minutes) Automatic processors 7

8 Image capture and processing - digital DR and CR systems are available More expensive but eliminates need to process films in chemicals Can adjust images onscreen to optimise viewing Much easier to jump onto the steep part of the learning curve Taking intraoral radiographs Parallel Technique Standard method used in veterinary radiography where the film is placed parallel to the object being radiographed This can only been used in the caudal and mid mandible in dogs and cats (due to the shape of the oral cavity) Lateral recumbency, side of interest towards the xray machine Taking intraoral radiographs Bisecting Angle Technique Used in areas where the film cannot be placed parallel to the long axis of the tooth Dorsal or ventral recumbency (relevant jaw towards the xray machine) Shoot perpendicular to the bisecting angle (halfway between the film plane and the long axis of the tooth) to give an image that is of a similar dimension to the object 8

9 Taking intraoral radiographs Bisecting Angle Technique Taking intraoral radiographs Bisecting Angle Technique If the beam is angled too vertically, perpendicular to film (ie too acute or vertical), the image is foreshortened. Taking intraoral radiographs Bisecting Angle Technique If angle beam perpendicular to tooth (ie too flat or horizontal), the image will be elongated. 9

10 Dental radiology is wonderful Best for the patient Oral disease can be diagnosed and treated efficiently and effectively Best for the client Peace of mind that sources of oral pain will be detected and the best treatment performed Best for us! We can provide excellent care with less frustration and fewer nasty surprises QUESTIONS? 10