AUTOMATIC REGISTRATION OF DENTAL RADIOGRAMS 
F. Samadzadegan *, H. Bashizadeh Fakhar^, M. Hahn, P. Ramzi^* 
*Dept. of Surveying and Geomatics, Faculty of Engineering, University of Tehran, Tehran, Iran - (samadz- pramzi)(Qut.ac.ir 
"Dept. of Dentomaxillofacial Radiology, Faculty of dentistry, Tehran university of medical sciences, Tehran, Iran - 
bashizad@tums.ac.ir 
‘Dept. of Geomatics, Computer Science and Mathematics, Stuttgart University of Applied Sciences, Stuttgart, Germany - 
m.hahn.fbv@fht-stuttgart.de 
Commission WG V/3 
KEY WORDS: Registration, Dental Radiograms, Fuzzy reasoning, Radiometric, Geometric, Matching 
ABSTRACT: 
In this paper we propose a feature based method, which employs a fuzzy reasoning strategy for registration of two different dental 
radiograms. The fuzzy decision process for conjugate feature determination simultaneously takes advantage of all the influential 
parameters that contribute during the conjugate feature identification stage, namely: geometrical constraints, radiometric similarities 
evaluated by correlation coefficient as well as texture differences. Simultaneous combination of these constraints blended into a 
fuzzy decision making process may offer the potential for reducing the mismatching possibilities. At the end, the registration outputs 
the set of transformations that can be used to correctly map the input image to the reference image. The tests carried out on 
registration of real periapical and panoramic dental radiograms demonstrate the high potentials of the proposed strategy. 
1. INTRODUCTION 
Within the current clinical setting, dental radiography is a 
vital component of a large number of applications. Such 
applications occur throughout the clinical track of events; not 
only within clinical diagnostics settings, but prominently so 
in the area of planning, consummation, and evaluation of 
surgical and adiotherapeutical procedures. 
Depending on the relative position of the film and the patient 
and the resolution of the films and the case of exposing the 
radiograms, dental radiograms are separated into two major 
groups, /ntraoral and Extraoral radiograms (Woods and 
Pharoah, 1994; Whaites, 2003). 
1.1 Intraoral Radiograms 
In this case, the radiogram is made as a double emulsion film 
(emulsion is on both sides of the base of the film). With this 
kind of films, less radiation can be used to produce an image, 
either, the resolution of these kind of radiograms are more in 
comparison to extraoral radiograms. In this case, the film is 
placed inside the mouth of patients. Intraoral radiograms can 
be divided into three categories (Figure. 1). 
Periapical: Periapical views are used to show the crowns, 
roots, and surrounding bone. Each film usually shows two to 
four teeth. Bitewing: Bitewing (Interproximal) views are 
used to record the coronal portions of the maxillary and 
mandibular teeth in one image. Occlusal: Occlusal views are 
used to show larger areas of the maxilla or mandible than 
may be seen on a periapical film. Here, the film is usually 
held in position by having the patient bite on it to support it 
  
Corresponding author. 
between the occlusal surfaces of the teeth (Woods and 
Pharoah, 1994; Whaites, 2003). 
  
Intraoral Radiograms 
Periapical 
  
Bitewing _ 
     
  
Figure 1. Intraoral radiograms types 
1.2 Extraoral Radiograms 
These kinds of radiograms include all views made of the 
orofacial regions with films positioned extraorally. These 
radiograms are used to examine areas not fully covered by 
intraoral films or to visualize the skull and facial structures. 
Extraoral radiograms can be divided into three categories 
(Figure. 1). 
Skull and maxillofacial: Skull and maxillofacial radiograms 
show different views of the head bones depending on the 
different projections have had to be devised. Cephalometric: 
Cephalometric radiography is a standardized and 
reproducible form of skull radiography used extensively to 
assess the relationships of the teeth to the jaws and the jaws 
to the rest of the facial skeleton. Panoramic: Panoramic 
(Pantomography) technique is used for producing a single 
image of the facial structures that includes both the maxillary 
and mandibular dental arches and their supporting structures. 
  
  
   
  
  
  
  
  
  
   
  
  
  
  
  
   
  
   
  
   
   
   
  
  
  
  
  
   
   
  
   
   
   
   
   
  
  
   
   
  
   
  
    
  
   
  
    
   
  
  
   
  
   
   
   
  
   
   
   
  
     
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