Quantitative analysis of bone density in direct digital radiographs evaluated by means of computerized analysis of digital images.
OBJECTIVE
minimal density variations of mineralized tissues can be reliably detected with quantitative image subtraction analysis. The aim of this study was to evaluate quantitative variations of in vitro mineral density by varying the exposure time of direct digital radiographs using a computer assisted densitometric image analysis (CADIA) program.


METHODS
in a human mandibular segment a three-wall periodontal defect was created mesial to a molar. Bone chips were created from the marrowbone of the same mandible with masses of 1 to 5 mg. A triplicate radiograph of the defect was taken as a baseline for seven different exposure times. The bone chips were inserted into the defect and another triplicate series of radiographs for the seven exposure times were taken as follow-up images. The images were analysed using CADIA software to detect variations in bone density.


RESULTS
the results of CADIA revealed increased density when the size of the inserted bone chip increased. The 2 mg chip was underestimated owing to mass reduction during insertion. The regression line of the CADIA values was consistent with the weight of the bone chips of 1, 3, 4 and 5 mg. The exposure time f6 (0.178 s) showed the best correlation with the bone chip weight. Loss of information in the images occurred when the exposure time exceeded the sensor's latitude.


CONCLUSIONS
CADIA analysis is a reliable and sensitive tool for detecting subtle bone density variations. More reliable results are obtained with increased exposure time; however, excessive exposure should be avoided.
Morea
C
C
Department of Orthodontics, Dentistry Faculty, University of São Paulo, São Paulo, Brazil. cmorea@uol.com.br
Dominguez
G C
GC
Coutinho
A
A
Chilvarquer
I
I
D015502:Absorptiometry, Photon / Q000379:methods*; D015519:Bone Density; D016025:Bone Transplantation; D002102:Cadaver; D044962:Data Compression; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008334:Mandible / Q000000981:diagnostic imaging*; D010486:Periapical Tissue / Q000000981:diagnostic imaging; D019252:Radiography, Dental, Digital / Q000379:methods*; D011873:Radiology Information Systems; D012044:Regression Analysis; D012984:Software; D013382:Subtraction Technique; D013997:Time Factors