15-10-2016, 12:03 PM
An Edge Detection Scheme for Endodontic Working Length
Measurement in Root Canal Treatment for Succedaneous Teeth
1459179665-root.pdf (Size: 1.1 MB / Downloads: 6)
Abstract— The process of edge detection is useful in processing the dental x-ray images, specifically in determining
the root morphology and the length to which the root has extended, for the purpose of providing root canal treatment.
Generally, a manual analysis of an expert is made to determine these two features. However, the human analysis has
two disadvantages: intra subject variability and inter subject variability in analyzing the features. Therefore, we
propose an algorithm: Multi-scale and Multi Directional Analysis based Edge Detection with Statistical Thresholding
(MMST), to determine these two features and were quite successful in their extraction. The results of the proposed
algorithm are compared in terms of both qualitative and quantitative analysis with Canny method and are found to be
doing appreciably well. The dental images used in this paper are taken from the database of the patients of Vishnu
Dental College, Bhimavaram.
. INTRODUCTION
A root canal is nothing but the space within the root of a
tooth and consists of pulp chamber, the main canals and
more complex anatomical branches that connect root
canals to each other or to the surface of the root.
Accessory canals are small branches found near the apex
of the root. There may be one or more canals within each
root. The root canal is filled with a highly vascular, loose
connective tissue called the dental pulp. However, root
canal is also common name for “Endodontic Therapy”,
which is a treatment given for the pulp to remove
infection and to give protection for the disinfected tooth
from further microbial attacks. In the situations in which
a decayed or cracked tooth is found or if there is a scope
for further infection to that damaged tooth where, the
doctors’ advice for a “Pulpectamy” which is the removal
of pulp tissue. As a first step to cure the infection and
save the tooth, the dentist drills into the pulp chamber
and removes the infected pulp and then drills the nerve
out of the root canal with long needle shaped drills.
Then, the dentist fills each of the root canals and the
chamber with an inert material and seals up the opening.
This entire procedure is called the root canal or
endodontic therapy. The standard filling material is
“gutta- percha”, natural non elastic latex taken out of the
percha or the Palaquium Gutta tree. The standard
endodontic technique involves inserting a gutta – percha
cone into the cleaned out root canal along with cement
and sealer. The proposed method is useful at this stage
of root canal treatment where the filling of the root canal
with gutta –percha requires the shape of the passage and
also the length to which the filling should be made.
Generally, in endo-dontics, conventional film-based
radiography is an important resource for diagnosis,
trans-operative procedures, and treatment control. The
digital radiography obtained through intra-buccal
sensors rather than radiographic films represents
technological progress that allows qualitative and
quantitative analyses of all stages of endodontic therapy
[11, 12]. Regarding radiographic estimation of
endodontic working length, direct digital imaging
provides measurement tools that facilitate the definition
of the apical limit of root canal instrumentation.
Moreover, there is substantial reduction in image
processing time with the acquisition of digital
radiographs. Hence, the clinical procedures are
performed more quickly, with reduced radiation.
However, when using conventional or digital techniques
for working length determination, problems can occur
when the endodontic treatment is performed in atresic
and/or curved root canals. In these situations, frequently,
the use of small instruments is required and they are
barely perceptible in the radiographic image.
Furthermore, a manual analysis of the dental X-rays is
made to know how to fill the root canal which may lead
to errors because of the intra subject variability in the
interpretation of results.
So, the proposed Multi-scale Multi Directional Edge
Detection Scheme with a Statistical Thresholding is used
in this paper to determine the root morphology and also
the length of the root especially for atresic and curved
root canals. In the proposed method Laplacian Pyramidal
decomposition is used to decompose the X-ray image of
the tooth into number of levels, a Directional Filter Bank
is used for the directional decomposition of the image.
Moreover, the variability in the absolute magnitudes of
the neighborhood pixels is considered to determine a
threshold which is used to find the boundaries of the root
canal. Thus, the skeleton of the root canal is determined
using the proposed method and finally the distance
between the CVG and the apex of the root is found out
to determine the endodontic working length. The rest of
the paper is organized as follows: In section 2, the
details of the proposed methodology are presented, in
section 3 the results obtained and the comparisons
against the Canny algorithm are presented. Finally, the
conclusions drawn from the experiments and results
obtained in section 3 will be provided in section4.