An effective tooth isolation method for bitewing dental X-ray images

Tooth isolation is a very important pre-processing step for both computer-aided dental diagnosis and automatic dental identification systems. The accuracy of tooth isolation will directly affect the accuracy of feature extraction and thereby the final results of both types of systems. This paper presents a very effective and fully automatic tooth isolation method for bitewing dental X-ray images. Our upper-lower jaw separation mechanism is based on gray-scale integral projection to avoid possible information loss and incorporates with angle adjustment to handle skewed images. In single tooth isolation, we propose an adaptive windowing scheme for locating gap valleys to improve the accuracy. Furthermore, excessive isolation-curves can be removed and separating lines can be added to indicate the locations of missing teeth. Experimental results show that our method achieves higher tooth isolation accuracy rates for both upper- and lower-jaw images, when compared to Nomir and Abdel-Mottaleb´s method.