Bisecting Angle Technique Radiology PPT
- 1. GUIDED BY : DR. ANUSUYA BIYANI MAâAM DR. VINAYA PAWAR MAâAM PRESENTED BY :SANKET CHOURE ROLL NO. : 18 BISECTING ANGLE TECHNIQUE /SHORT CONE TECHNIQUE
- 2. Intraoral Radiographic Techniques: ďľ Techniques used in routine dental practice. ďľ Technique provides high resolution imaging of teeth and potential associated dental and jawbone diseases. ďľ provide detail & allow dentist to find cavities, check health of tooth root and bone surrounding tooth, check status of developing teeth, and monitor general health of your teeth and jawbone. ďľ 1. Periapical projections ďľ shows all teeth and surrounding bone ďľ Divided into two types 1. Paralleling Technique 2. Bisecting Technique 2. Bitewing projections ďľ shows crowns of maxillary and mandibular teeth and adjacent alveolar crest. 3. Occlusal projections ďľ shows an area of teeth and bone larger than periapical
- 3. BISECTING ANGLE TECHNIQUE ďľ Technique where film is kept as near to teeth and X-ray beam ďľ Principle 1. Works on Cieszyskiâs rule/rule of isometry (two triangles are equal if they have two equal angles and share common side). 2. Two equal triangles are formed then side of film and tooth will also be equal and in that condition tooth size in the film will be same as that of real tooth without any magnification. 1. Angle CAB=CAD 2. ACB=ACD=900 3. Side AC is common 4. ď¸ ď¸ ď¸ ď¸ ď¸ ď¸ ď¸ ď¸ ď¸ ď¸ ď¸ ď¸ ď¸ ď¸ď¸ABC=ADC 5. Then AB=AD 6. the tooth image formed in the film will be equal to the real-tooth
- 4. 3. These two triangles are formed equal only when: 1. The X-ray beam is perpendicular to the imaginary bisector film 2. Imaginary line should be correctly imagined 3. Proper patient positioning 4. Correct vertical angulation ďľ AB = Formed by the fiml ďľ AD = Formed by long axis of tooth ďľ AC = Formed by imaginary bisecting line
- 5. Steps in Taking Periapical Radiography: 1.Proper positioning of patient: 1. Brief Radiographic procedure to patient. 2. Position the patient upright in chair. 3. level of the chair must be adjusted 4. Adjust the headrest to support patients head 5. Remove all objects from patient's mouth that may interfere with film exposure. 2. Proper evaluation of target area for exposure: 6. Evaluation of complete oral cavity is mast. 7. Target area for exposure should be properly evaluate for correct placement of film
- 6. 3.Placement of the film: 1. white side of the film always faces the tooth 2. Anterior projections, film is placed vertically 3. Posterior projections, film is placed horizontally 4. Identification dot should be on occlusal surface always 5. 1.5-2 mm of the gap should be left on incisal or occlusal surface of film. 6. .Film holder kept tight so there will not be movement of film.
- 7. 4. check proper head orientation. 1. Arch is parallel to the floor and midsagittal plane is perpendicular to the floor. 2. maxillary projection -Ala tragus line should be parallel to floor so patient had to turn head little parallerd downward 3. mandibular projection Line above 3 cm above lower border of mandible parallel to the floor so patient had to turn head little upward. 4. Position tube head
- 8. 5.Position the tube head different vertical angulation given for dilferent teeth
- 9. Finger holding method: 1. finger always placed behind the film and teeth. 2. thumb position maxillary anterior & posterior- index finger 3. index finger to stabilize mandibular films. 4. patient's left hand is used for right side of the mouth 5. right hand is used for exposures on left side of the mouth, Disadvantages 6. Patient's hand in path of primary beam â unnecessary exposure 7. Patient use excessive force to stabilize film - bending of film â image distortion. 8. slip from position -inadequate exposure of prescribed area. Films Film Selection for Adults: #2 size film is used long axis of the film is vertical- anterior horizontal â posterior Film Selection for Children: small mouths #0 size film used ,.child's mouth small for larger size films.
- 10. PID Angulation: ďľ used to describe alignment of central ray of X-ray beam in horizontal and vertical planes Vertical angulation: 1. given by tilting tube head indicating either moving up and down. 2. determined by the imaginary bisecting between tooths and film 3. For maxilla â directed downloads - positive angulation. 4. For mandible - directed upward â negative angulation. Horizontal angulation: 5. Horizontal angulation must be 00 not any tube head tilting on either right or left side 6. Tube head has to move based on the arch curvature so that X-rays should pass throngh the contact area in 900 7. Any tilting right or left will cause overlaping between teeth Teeth Maxillary angulation Mandibular angulation Incisor +40 -15 Canine +45 -20 Premolars +30 -10 Molars +20 -05
- 11. Guiding lines for bisecting angle technique ďľ line of concentration for maxillary teeth is indicated along a line approximately 1/4th inch above the ala tragusline. ďľ line of concentration for mandibular teeth is indicated along a line approximately 1/4th inch above the lower border of the mandible. Chair position: The maxillary & Mandibular teeth occlusal plane is kept parallel to the floor and sagittal plane perpendicular to the floor.
- 13. MAXILLARY REGION Central Incisor ďľ Area visualised: include both central incisors ďľ Placement of the film:behind central incisor in line with midline of arch. placed with superioborderer on palate and inferior border 2 mm beyond incisal edges of the teeth. with help of patientâs thumb pressing against palatal surface of teeth. ďľ Projection of central rays: directed through tip of nose, perpendicular to imaginary bisector. ďľ Vertical angulation: +40 to +50°. ďľ Horizontal angulation: pass through contact area of central incisors. ďľ Exposure of film:0.8â1 s.
- 14. Lateral Incisor ďľ Area visualised : lateral incisor centred on radiograph with central incisor on one side and canine on other side ďľ Placement of film :behind lateral incisors with superior border on palate and inferior border beyond incisal edges of teeth. ďľ Projection of central rays: rays directed from ala of the nose 1 cm from midline, through middle of lateral incisor. ďľ Vertical angulation: +40 to +50°. ďľ Horizontal angulation:rays pass through middle of lateral incisor. ďľ Exposure of the film: 0.8â1 s
- 15. Canine ďľ Area visualised:include canine in midline with its periapical areas ďľ Placement of film :behind canine with superior border on palate and inferior border below cusps of canine ďľ Projection of central rays : rays through canine eminence, and perpendicular to the plane bisecting the angle of long axis of film ďľ Vertical angulation: +45 to +55° ďľ Horizontal angulation: rays pass through mesial contact area of canine. ďľ Exposure of the film:0.8â1 s.
- 16. Premolar ďľ Area visualised : distal half of canine, premolars, some molars part ďľ Placement of film: superior border on palate and inferior border just beyond cusps of premolars, molar. ďľ Projection of central rays:projected below pupil of eye, close to level of alaâtragus line. ďľ Vertical angulation: +30 to +40°. ďľ Horizontal angulation:rays pass through contact area of first and second premolars ďľ Exposure of the film: 0.8â1 s.
- 17. Molars ďľ Area visualised: include distal half of second premolar, three molars and some part of tuberosity. ďľ Placement of film :film placed behind molar, cover 1st 2nd & 3rd molars distal aspect of second premolar. ďľ Projection of central rays: rays directed through outer canthus of eye, below zygoma and in anteroposterior level with second molar.central rays perpendicular to the imaginary bisector ďľ Vertical angulation: +20 to +30°. ďľ Horizontal angulation: rays pass through contact area of first and second molars. ďľ Exposure of the film:0.8â1 s.
- 19. MANDIBULAR REGION: Central and Lateral Incisor: ďľ Area visualised: mandibular central and lateral incisors ďľ Placement of film :film placed behind central and lateral incisors contact area centered. Superior border on incisal edge and inferior border displaced distally extending onto lingual mucosa. ďľ Projection of central rays: rays directed below vermillion border of lip 3 cm from midline. central rays perpendicular to imaginary bisector ďľ Vertical angulation: angulation â15°. ďľ Horizontal angulation: rays pass through contact area of central incisors ďľ Exposure of the film:exposure time 0.6 s.
- 20. Canine ďľ Area visualised: include whole canine in midline ďľ Placement of film :film placed behind canine with superior border above cusp of tooth and inferior border extending on to lingual mucosa ďľ Projection of central rays : rays directed on canine exactly 3 cm from midline ďľ Vertical angulation: â20°. ďľ Horizontal angulation:rays pass through contact area of canine and lateral incisor. ďľ Exposure of the film: 0.6 s.
- 21. Premolar ďľ Area visualised : include images of distal half of canine, premolars and first molar. ďľ Placement of film: film behind the premolar with superior border extending just beyond the cusps of the premolar and inferior border beneath lateral border of tongue. ďľ Projection of central rays: rays directed through interproximal space between first and second premolars below pupil of eye.3 cm above inferior border of mandible ďľ Vertical angulation: â10°. ďľ Horizontal angulation: rays pass through contact area of first and second premolars.
- 22. Molars ďľ Area visualised : distal surface of second premolar and three molars. ďľ Placement of film: behind molars with superior border extending above cusps of molar& inferior border beneath tongue. anterior border cover distal half of premolar. ďľ Projection of central rays :rays pass through interproximal space between molars.point of entry is directed below outer canthus of eye and 3 cm above the inferior border of mandible ďľ Vertical angulation: â5°. ďľ Horizontal angulation: rays pass through contact area of first and second molars. ďľ Exposure of the film: 0.6â0.8 s
- 24. Advantages: 1. simple and quick procedure. 2. Comfortable for patient. 3. film adapted to shape of most dental arches 4. More teeth may be demonstrated on one film without overlap 5. easily adaptable for endodontic treatment 6. Less exposure time required Disadvantages: 7. Chances of film fault are more like magnification distortion, cone cut, overlapping, 8. crowns of teeth are often distorted thus preventing detection of a proximal caries. 9. periodontal bone levels are poorly shown 10. horizontal & vertical angles have to be assessed for every patient & considering skill required 11. shadow of zygomatic bone is generally super imposed over roots of maxillary molar 12. Incorrect angulations result in overlapping of crowns and roots
- 25. Difference Between Paralleling and Bisecting Angle Technique: Paralleling technique Bisecting angle technique Also called Long cone technique Short cone technique First described by Donald MC Cormack in 1937 Weston Price in 1904 Mechanism film is parallel to long axis of teeth central ray of X-ray beam is directed at right angle to teeth Cieszyski's rule of isometry Holder used XCP - extended cone paralleling instrument Snap a ray holder Placement As far as possible to teeth As near as possible to teeth Magnification Less More Time consuming More Less Patient confert Less More
- 26. Reference: 1. White & Pharoahâs Oral Medicine Principles & Interpretation 2nd Edition By Sanjay M. Mallya, Ernet W. N. Lam 2. Essentials of Oral & Maxillofacial Radiology By Freny R. Karjodkar 3. TEXTBOOK OF ORAL RADIOLOGY SECOND EDITION By Anil Ghom , Savita Ghom 4. Textbook of oral medicine & Oral Radiology By PEEYUSH SHIVHARE