 Hello everyone, welcome back to another session in the industry and more. Today, we have intraoral radiographic techniques and its modification in oral radiology. So, this session is about periapical radiography, then bite wing and occlusion radiography. In periapical radiography, we have the most important paralleling ankle technique and bi-setting ankle technique and also we will be looking into bite wing radiography and occlusion radiography. To begin with, intraoral radiographic examinations are the foundation of dental radiography. It is through which we inspect the teeth and its supporting structures and how do we take it? We keep a film inside the mouth and direct x-ray beam at various angles from a position outside the mouth through the anatomical region of interest towards the film. So the general steps for taking radiographs are we need to seat the patient, adjust the x-ray unit setting, then position the tube head, then examine the oral cavity, position the film inside the cavity, then position the x-ray tube towards the film, then make the exposure. Now the films, the periapical films can be classified based on the size as 0, 1 and 2. So 0, 1 and 2, 0 is used for children that is around 3 to 5 years, it is smaller, comparatively smaller one because it is used for the deciduous teeth. It is 22 to 35 millimeter, then size 1, 24 to 40 millimeter, it is used for adults, anterior region and children's posterior region and size 2 that is 32 to 41. It is length by breadth, it is 32 by 41, not 32 to 41, it is 32 by 41. It is a standard film, can use it for adults anterior and posterior and also 9 to 12 years children anterior and posterior, so size 0, 1 and 2. Based on the film speed, we have A to E that is A, B, C, D and E, A is the slowest and is the fastest. D and E speed films are commonly used in intraoral periapical radiography. D speed films has half the exposure time than the D speed films, so there is large silver bromide crystals and increased silver bromide in emulsion. So what are the types of intraoral radiography? We have three types, this is the periapical radiography, this is the bite wing radiography and this is the occlusion radiography, this is the maxilla and this is mandible. So the first one, periapical radiography, it is to record the images of the outlines, position and mesiodisital extension of teeth and surrounding tissues. So periapical radiographs must contain the full length of tooth and at least 2 mm of periapical bone. So this is a lesion, it is located at the apex. So in order to understand the full details of this lesion, we need to have 2 mm of periapical bone, that is what is known as periapical radiography. So it is indicated when there is periapical infection or inflammation to understand the periodontal status and also to know the root morphology before extraction, especially the complicated extraction and in endodontics we need to understand the working length, we need to understand the apical foramen status and to understand the implants postoperatively and also to get a detailed picture of trauma to teeth and alveolar bone. So there are 2 techniques to take periapical radiographs, they are paralleling or right ankle or long con technique, bisecting or short con technique. So it can be asked as paralleling right ankle or long con and it could be a short con technique. So you need to know all the names because it is a very common question. So what is paralleling ankle technique, it is also known as right ankle long con technique. So the principles are the image receptor or the X-ray film or digital sensor placed in holder. So it is placed in holder. So we can see the film here behind the teeth. This is the X-ray tube and we have a film holder and an indicator road here. So this is positioned parallel to the long axis of tooth. The X-ray tube head is, this is the X-ray tube head which is right ankle to the film and so here the image receptor it is kept parallel to the long axis of tooth. So this is parallel to the long axis of tooth and the X-ray tube is right angle to the film and tooth. So from here the X-ray will be produced. So here will be the X-ray tube. So this is the X-ray tube. This is the film. So when long con beam technique there will be less magnification and increased definition. So we can see the object and its image here. When there is a longer con, so we can see the longer con, this is a longer con, the image is slightly magnified. When there is shorter con, this is a shorter con, the magnified image will be there. So this picture shows the long con. When there is a long con, the image magnification will be less and there will be more well defined the resulting image whereas a shorter con will result in a magnified image with less definition. So we need slight magnification with more definition. So that is the advantage of long con. When there is long con, it will result in more defined and less magnified image. So that is the idea of paralleling technique. So film position for maxillary incisors and canine, it is kept at volt of pallet and mandibular incisors and canine, floor of the mouth in line with lower canine or first primolars. For maxillary primolars and molars it should be at midline of pallet and mandibular primolars and molars at the lingual sulcus. So this is the long axis of tooth, film is placed at parallel to the long axis of tooth. This is the film holder and this is the x-ray produced from x-ray tube and the x-ray tube or x-ray produced will be at right angle to the long axis of tooth and the film. So position of tube head, tube head is the x-ray tube head that is film should be placed so that it covers the particular teeth to be examined. And vertical inclination that is the central ray of x-ray beam should be perpendicular to film and long axis. So the central ray should be perpendicular to the long axis of tooth and the film and this film should be placed so that it covers the particular teeth to be examined. So we are taking x-ray of this tooth. So the film should be placed in such a way that it covers the entire tooth. Sometimes if this is mispositioned the entire tooth will not be obtained. And the horizontal inclination that is central ray of x-ray beam through the contact area between the teeth and central ray of x-ray must be directed to the center of the film to completely cover the fillet. The advantages of paralleling techniques are accuracy, simplicity, duplication, the periodontal bone level and there will not be any concutting. So we will define periodontal bone level is obtained. Disadvantages are the film placement is little difficult and there will be increased exposure time and the holders need to be autoclaved and only 20 degree margin of error. So these are the maxillary teeth projections for the central incisor. It should be like this primolars and the canines and the molar region. So the angulation of tube head is changing. This is almost 90 degree, this is around 40-45 degree, this is parallel to the root amin tooth. So similarly in mandibular teeth this is incisor, primolar, canine and molar region. So the modifications if there is shallow palate, cotton trolls on either side of the bite block, then increased vertical angulation and in case of bony growth, tore also we need to modify the placement mandibular, primolar region. So mild film curvature should be recommended to avoid the anatomic constraint area. So the next technique is bisecting ankle technique, which is also known as short con technique. The principle is Sisynchi's rule of isometry. It says two triangles are equal when they share one complete side and have two equal angles. So this is Sisynchi's rule. This is a triangle. This is a triangle. So it has one common side and two equal angles. So film is placed close to teeth. So the film is placed close to teeth. So the angle between long axis of teeth and long axis of film is bisected. So the angle between long axis of the tooth, this is a long axis of tooth and the long axis of film is bisected. This is an imaginary bisector. So imaginary bisector and the chendral ray is coming at perpendicular to this bisecting line. So the x-ray tube head is right angle to this bisecting line. So the actual length of the tooth in mouth will be equal to the length of tooth on image. So the actual length of tooth in mouth will be equal to the length of tooth on image. So this is the one side of the triangle and this is the other side of triangle. So this is Sisynchi's rule. So this will be equal to this. So since it is isometric triangle, the last sentence that is actual length of tooth in mouth will be equal to the length of tooth on image. So this is the actual length of tooth in mouth. This is the image that is the image produced here. So this two will be equal because angle are equal, these two angles are equal. So film placement, so hope you understood this concept of Sisynchi's rule of isometry because two triangles are equal when they share one complete set and have two equal angles. So we have two equal angles here and here. So the sides will be same. So the film placement is close to teeth and anterior, vertical and posterior horizontal. That is the position of film. So in anterior teeth we keep it at a vertical fashion and posterior should be at horizontal level and there is two methods either we can use a film holder or digital method. So the vertical angulation, so we can see this is a occlusion plane and this is a mid sagittal plane. So this is zero angulation and this is 90 degree angulation, 60 degree and 30 degree, 30, 60 and 90 degree. So angulation will be changed according to the tooth to be x-rayed. So we have maxilla and mandible. The molar should be 25 to 30 degree that is plus 30, primolars plus 40, canines plus 50 and incisors 55, bite wings 10 degree whereas the mandible it is minus 10, for molars it is 0, primolars minus 10, minus 15 and minus 20. So this is angulation, horizontal angulation, central tray perpendicular to the curvature of arch and through the contact area of teeth. So in molars 0 degree, transcontila plane as seen from vertical above the patient and in primolars it is 30 degree, canines it is 45 degree and incisors it is 90 degree. And this picture shows the point of entry of x-ray beam. So we can make out maxillary, this is incisors through the tip of nose, canine, alof nose, primolars, pupillary perpendicular to the at line and the molars outer canthus of eye perpendicular to this at line and mandibular teeth, the incisors through the tip of chin, canines angle of mouth, primolars pupillary line, molars outer canthus of eye, third molar the ICM behind outer canthus. So the advantage of this bisecting ankle technique is it is simple and quick. Hand positioning is reasonably comfortable for the patient, can hold the film using his finger, decreased exposure time as short distance is used. If all angulations are assessed correctly exact replica image can be obtained. In paralleling technique we get slightly magnified image because we are using a long con technique. This is short con technique we are keeping the image as close to the teeth as possible and there is no sterilization of folders are required. But the disadvantages are image distortion there will be angulation problems and con cut, digital film holding method, then shadow of zygomatic bone frequently lies over the roots of upper molars, then buckle roots of primolars and molars are foreshortened, the crowns of teeth are often distorted in films preventing the detection of those proximal caries and not possible to obtain reproducible views. So the modifications when there is shallow pallet we need to use cotton rolls and to also increase the vertical angulation. So this is how we use cotton rolls and also modifications required when there is mandibular tori and maxillary tori mandibular tori and maxillary tori. So people with gag reflex or obese or children people we need to make them relax and reassure the patient, we need to distract the patient and we need to apply little bit of topical agent such as mouthwash or spray and reducing psychic and tactile stimuli. So third molars we may need to use this holder because keeping a position at third molar position is too difficult. So in endolontics the difficulties are film placement and stabilization, we need to understand exactly at the root apex and the working length, sometimes the observation. So identification and separation of root canals and assessing root canal length, so we need to keep special image receptor holder and taking two radiographs with two horizontal angulation to understand the root canals. For also edengulus ridge we need to go for panoramic radiograph and in children small size mouth or very small size children we need to go for modified bisecting angle technique. Next we have bitwing radiography, it is include crowns of both maxilla and mandible and alveolar crest of the same receptor. So it is mainly to use, so it is like this alveolar crest and crowns of maxilla and mandible, it is to detect the interproximal caries and to monitor progression of tunnel caries, detection of secondary caries below any restoration and also to evaluate the periodontal conditions and alveolar bone crest levels and also for detecting calculus in interproximal area. So the advantages are it is very simple, film pack at held firmly in position and cannot be despised by tongue, position of the x-ray tube head is determined by the holder thus it is less operator dependent ensuring that the x-ray beam is always at right angle to the film packet and it avoids conning off of anterior part of film and holders are autoclayable or disposable. But the problem is position of holder in mouth is operator dependent, it is not accurately reproducible, not suitable for monitoring of progression of caries, positioning of holders can be uncomfortable for the patient and some holders are relatively very expensive and holders are not usually suitable for children. Next the last one is occlusion radiography, indicated to locate the retained roots of extracted teeth, to locate the supernumeric teeth or un erupted or impacted teeth or to locate the salivary stones index of submandible earthland or to evaluate the extent of lesion in maxilla or mantel or also to examine the areas of cleft palate or to measure the changes in size and shape of maxilla. So classification maxilla and mantel occlusion radiograph maxilla it is both are cross sectional this is topographical anterior posterior lateral and also pediatrics. So maxillary occlusion topographical. So it is to view the maxilla for anterior alveolar fracture or to understand the cyst supernumeric teeth or impacted canines on pathology. So the patient position and direction of central ray, so this is a central ray direction and mantibular topographical occlusion radiograph uses to view the anterior portion of mandible to understand the fractures, cysts, root tips and periapical pathology and also it provides a very good view of symphysis region of the mandible and this is pointed the central ray of x-ray is going like this at 55 degree. So the cross sectional is taken at 90 degree to view the entire mandible for fracture foreign bodies, root tips, salivary calculate and tori. So the direction of central ray is like this 90 degree and posterior oblique axillary occlusion to view the maxillary posterior region or to view the maxillary sinus. The projection may be used in place who have a tendency to gag or to examine the periapical pathology of fruit. So central rays directed at 60 degree. So similar mandibular occlusion oblique it is directed at minus 50 degree it is to view the posterior teeth or to locate cysts and fractures and also to supernumeric teeth periapical pathology. So maxillary vertex occlusion, so the direction of central ray it is at 90 degree to view the buck co-parallel relationship or unrupted teeth in the dendrel arch. So that's all about the radiographic techniques. The most important techniques are paralleling and bite wing techniques in periapical radiographs and also we learned about bite wing radiographs and occlusion radiographs. So this is most commonly asked question that is paralleling technique or bisecting angle technique you need to draw pictures to get the maximum marks and the advantages and disadvantages of paralleling technique and bisecting angle is very important and also the bite wing radiographs and occlusion radiography. So I will come up with a new topic in the industry and more. Thank you.