Marginal bone level around implants assessed in digital and film radiographs: in vivo study in the dog.
BACKGROUND
One of the objectives of postoperative radiographic examinations of implants is to evaluate the marginal bone height and its changes over time.


OBJECTIVE
The purpose of this study was to assess the influence of digital image processing on measurements of the marginal bone level around implants.


METHODS
Implants in beagle dogs, used to study the development of peri-implantitis and subsequent healing following treatment, were monitored with conventional radiography and a digital image plate system. Five observers measured the distance between a reference point and the bone level. Measurements in conventional radiographs were made with the use of an x-ray viewer (2x) and a magnifying lens (7x). For the digital images, the system's built-in measuring function was used together with five image processing techniques: edge enhancement (matrixes set on 5 and 25), inverted grey scale, single color highlight, and color intensity mapping together with the brightness and contrast control. From the time of maximum breakdown and the end of the experiment, histologic values were available.


RESULTS
Differences between techniques and observers increased toward the end of the healing period. Measurements made at maximum breakdown did not differ significantly from the histologic value. Measurements made after healing all methods, except that using edge enhancement and a 25 x 25 kernel, differed significantly from the histologic value by underestimating the bone level.


CONCLUSIONS
Measurements of bone level around implants from digital radiographs are as accurate and precise as those from film images. In particular cases, the use of specific image processing algorithms may improve both accuracy and precision. After healing, the histologic specimens showed an incomplete bone fill in the crater with a remaining thin layer of connective tissue in contact with the fixture, and in such situations, the morphology of the bone will give a more complicated diagnostic task.
Borg
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Department of Oral Diagnostic Radiology, Faculty of Odontology, University of Göteborg, Box 450, SE 405 30, Göteborg, Sweden.
Gröndahl
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Persson
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D000465:Algorithms; D000539:Alveolar Process / Q000000981:diagnostic imaging* / Q000473:pathology; D000818:Animals; D001862:Bone Resorption / Q000000981:diagnostic imaging / Q000473:pathology; D003116:Color; D003238:Connective Tissue / Q000000981:diagnostic imaging / Q000473:pathology; D015921:Dental Implants; D004285:Dogs; D005456:Fluorescent Dyes; D005500:Follow-Up Studies; D007091:Image Processing, Computer-Assisted; D015588:Observer Variation; D016348:Osseointegration; D010518:Periodontitis / Q000000981:diagnostic imaging / Q000628:therapy; D010636:Phenols; D011856:Radiographic Image Enhancement; D013223:Statistics as Topic; D013454:Sulfoxides; D014945:Wound Healing; D014962:X-Ray Film; D014992:Xylenes
D015921:Dental Implants; D005456:Fluorescent Dyes; D010636:Phenols; D013454:Sulfoxides; D014992:Xylenes; C016833:xylenol orange