Occlusal Radiography: used to examine large areas of maxilla or mandible on one film size 4( intraoral film) ,the film is named because the patient occlude or bites on the entire film . Uses of Occlusal Radiography: 1-To locate retained roots of extracted teeth. 2- To locate supernumerary,unerupted or impacted teeth. 3-To locate foreign bodies in the maxilla or mandible. 4- To locate salivary stone in duct of submandibular gland. 5-To locate and evaluate the extent of lesion e.g,cyst ,tumors in maxilla or mandible. 6-To evaluate the boundaries of maxillary sinus. 7-To evaluate fracture of maxilla or mandible. 8-To aid in examination of patients who can not open their mouth more than few millimeters. 9- To examine the area of cleft palate. 10.To measure changes in size and shape of maxilla or mandible. .
Principles: The basic principle of the occlusal technique can be described as follows: The film is positioned with white side facing the arch that is being exposed. The film is placed in mouth between the occlusal surfaces of maxillary and mandibular teeth. The film is stabilized when the patient gently bites on the surface of the film. .
Anterior Maxillary Occlusal Projection
Image field. The primary field of this projection includes the anterior maxilla and its dentition, as well as the anterior floor of the nasal fossa and teeth from canine to canine. Film placement. Adjust the patient's head so that the sagittal plane is perpendicular and the occlusal plane is horizontal to the floor. Projection of central ray. Orient the central ray through the tip of the nose toward the middle of the film with approximately +45 degrees vertical angulation and 0 degrees horizontal angulation.Cross-Sectional Maxillary Occlusal Projection Or Upper standard occlusal I mage field. This projection shows the palate, zygomatic processes of the maxilla, anteroinferior aspects of each antrum, nasolacrimal canals, teeth from second molar to second molar, and nasal septum. Film placement. Seat the patient upright with the sagittal plane perpendicular to the floor and the occlusal plane horizontal. Projection of central ray. Direct the central ray at a vertical angulation of +65 degrees and a horizontal angulation of 0 degrees, to the bridge of the nose just below the nasion, toward the middle of the film.
Main clinical indications:The main clinical indications include:• Periapical assessment of the upper anterior teeth, especially in children but also in adults unable to tolerate periapical films• Detecting the presence of unerupted canines, supernumeraries and odontomes.• As the midline view, when using the parallax method for determining the bucco/palatal position of unerupted canines.• Evaluation of the size and extent of lesions such as cysts or tumours in the anterior maxilla.• Assessment of fractures of the anterior teeth and alveolar bone. It is especially useful in children following trauma because film placement is straightforward.
Lateral Maxillary Occlusal Projection or upper oblique occlusal
Image field. This projection shows a quadrant of the alveolar ridge of the maxilla, inferolateral aspect of the antrum, tuberosity, and teeth from the lateral incisor to the contralateral third molar. In addition, the zygomatic process of the maxilla superimposes over the roots of the molar teeth. Projection of central ray. Orient the central ray with a vertical angulation of +60 degrees, to a point 2 cm below the lateral canthus of the eye, directed toward the center of the film. Point of entry. The central ray enters at a point approximately 2 cm below the lateral canthus of the eye.Main clinical indications:• Periapical assessment of the upper posterior teeth, especially in adults unable to tolerate periapical films.• Evaluation of the size and extent of lesions such as cysts, tumours affecting the posterior maxilla.• Assessment of the condition of the antral floor. • As an aid to determining the position of roots displaced inadvertently into the antrum during attempted extraction of upper posterior teeth.• Assessment of fractures of the posterior teeth and associated alveolar bone including the tuberosity.
Anterior Mandibular Occlusal Projection
I mage field. This projection includes the anterior portion of the mandible, dentition from canine to canine, and inferior cortical border of the mandible.Film placement. Seat the patient tilted back so that the occlusal plane is 45 degrees above horizontal. Place the film in the mouth with the long axis perpendicular to the sagittal plane and push it posteriorly until it touches the rami, center the film with the tube side down and ask the patient to bite lightly to hold the film in position. Projection of central ray. Orient the central ray with -10 degrees angulation through the point of the chin toward the middle of the film; this gives the ray -55 degrees of angulation to the plane of the film. Point of entry. The point of entry of the central ray is in the midline and through the tip of the chin.
Main clinical indications• Periapical assessment of the lower incisor teeth, especially useful in adults and children unable to tolerate periapical films.• Evaluation of the size and extent of lesions such as cysts or tumours affecting the anterior part of the mandible.• Assessment of displacement fractures of theanterior mandible in the vertical plane.
Cross-Sectional Mandibular Occlusal Projection
Image field. This projection includes the soft tissue of the floor of the mouth and reveals the lingual and buccal plates of the mandible from second molar to second molar. When this view is made to examine the floor of the mouth (e.g., for sialoliths), the exposure time should be reduced to one half the time used to create an image of the mandible. Film placement. Seat the patient with the head tilted back so that the ala-tragus line is almost perpendicular to the floor. Place the film in the mouth with its long axis perpendicular to the sagittal plane and with the tube side toward the mandible. The anterior border of the film should be approximately 1 cm beyond the mandibular central incisors. Ask the patient to bite gently on the film to hold it in position. Projection of central ray. Direct the central ray at the midline through the floor of the mouth approximately 3 cm below the chin, at right angles to the center of the film. Point of entry. The point of entry of the central ray is in the midline through the floor of the mouth.Cross-Sectional Mandibular Occlusal Projection
Main clinical indications:• Detection of the presence and position of radiopaque calculi in the submandibular salivary ducts .• Assessment of the bucco-lingual position of unerupted mandibular teeth.• Evaluation of the bucco-lingual expansion of the body of the mandible by cysts, tumours.• Assessment of displacement fractures of the anterior body of the mandible in the horizontal plane.Anterior True Lower Occlusal View
Lateral Mandibular Occlusal ProjectionImage field. This projection covers the soft tissue of half the floor of the mouth, the buccal and lingual cortical plates of half of the mandible, and the teeth from the lateral incisor to the contralateral third molar. When this view is used to provide an image of the floor of the mouth, the exposure time should be reduced to one half that used to provide an image of the mandible. Film placement. Seat the patient so that the alatragus line is almost perpendicular to the floor. Place the film in the mouth with its long axis initially parallel with the sagittal plane and with the tube side down toward the mandible. Place the film as far posterior as possible, then shift the long axis buccally (right or left) so that the lateral border of the film is parallel with the buccal surfaces of the posterior teeth and extends laterally approximately 1 cm. Projection of central ray. Direct the central ray perpendicular to the center of the film through a point beneath the chin, approximately 3 cm posterior to the point of the chin and 3 cm lateral to the midline. Point of entry. The point of entry of the central ray is beneath the chin, approximately 3 cm.