Midterm Exam Roentgenology PDF

PRDM 134 | ROENTGENOLOGY | LECTURE MODULE LESSON 1st SEMESTER | S.Y. 2024-2025 Lecture notes typewritten by: Rhein Feniza PARALLELING TECHNIQUE...

PRDM 134 | ROENTGENOLOGY | LECTURE MODULE LESSON 1st SEMESTER | S.Y. 2024-2025 Lecture notes typewritten by: Rhein Feniza PARALLELING TECHNIQUE PARALLELING FILM PLACEMENT PATIENT PREPARATION As mentioned previously, the film is placed in the mouth so that the long axis of the film is parallel with the long axis of the teeth. Since all Prior to starting to take films, the patient must be positioned properly. teeth are inclined toward the middle of the head (not straight up and Seat the patient and ask them to remove their glasses and any down), the film will be slightly angle in the mouth (see below left). Of removable appliances. the film is maintained in an upright position (see below right), the Adjust the headrest to support the head while taking films. patient will not be able to close on the biteblock and the film will now be parallel. Raise or lower the chair to a comfortable height for the operator. Þ The image will be slightly larger than the actual teeth Place the lead apron and thyroid collar on the patient. Þ Analog films are more accurate; very important in RCT It is a good idea to inform the patient about the number of films you Þ Follow the long axis of the tooth will be taking so they know what to expect. In the paralleling technique, the film is placed in the mouth so that the long axis of the film is parallel with the long axis of the teeth being radiographed. A paralleling instrument with an aiming ring is normally used to orient the film, teeth and ring in a parallel relationship. When the x-ray beam is aligned with the ring, the x-ray beam will be perpendicular (right angle) to the teeth and the film. To facilitate film placement, the film may be tipped up to 20 degrees beyond parallel. Because the palate and floor of the mouth are shallower as you approach the lingual of the teeth, the film often cannot be positioned properly close to the teeth. ADVANTAGES OF USING THE PARALLELING TECHNIQUE There are two techniques for taking periapical films, the paralleling and the bisecting angle techniques. When comparing the two techniques, the advantages of the paralleling techniques are: As a result, the film must be positioned away from the teeth (farther 1. Better dimensional accuracy: The paralleling technique results back in the mouth) to achieve parallelism. To facilitate film placement, in less distortion of the image of the teeth. the film may be tipped up to 20 degrees beyond parallel 2. When using the paralleling instrument with the aiming ring, the alignment of the x-ray beam is simplified. 3. It is easier to standardize films. 4. Head position is not as critical. When the long axis of the film is parallel with the long axis of the tooth, the image of the tooth on the film looks the same as the tooth itself (no distortion). The image will be slightly larger than the actual tooth Because the film father from the teeth, there will be increased (magnification), but the shape is the same. magnification (larger size) and decreased sharpness (less detail). To compensate for this, the target-nim distance should be increased (the target is where the x-rays are produced) Longer target = similar size and shape (but longer exposure time) The target-film distance is increased by using a longer PID, using a machine with a recessed target (opposite side of the tube head from DISADVANTAGES OF USING THE PARALLELING TECHNIQUE the PID) or a combination. The medium PID with a recessed target is a good compromise. The disadvantage to increasing the PID length is that the exposure time When comparing the paralleling and bisecting angle techniques, the must be increased. If you change from a 8” target-film distance to a 16” paralleling technique is: target-film distance (double the distance) the exposure time will be 1. Less comfortable. Because the film is usually more upright when four times as much (see inverse square law). using the paralleling technique, it impinges more on the palate or floor of the mouth, thus making it more uncomfortable. 2. More limited by the anatomy of the patient’s mouth. A shallow palate or floor of the mouth makes it harder to position the film using the paralleling technique. pg. 13  PARALLELING TECHNIQUE ANTERIOR PERIAPICAL Head As mentioned previously, head position is not as For the anterior periapical, the #1 size film is placed vertically on the Position important when using the paralleling technique. biteblock. The film is rotated so the identifying black dot is down; this However, in general it is best to position the head in end of the film goes into the slot of the biteblock (dot-in-the-slot). an upright position so that the maxillary arch is Push the film back against the biteblock support and slide it down into parallel to the floor. the slot. Film The #1 size film is used for anterior periapical films Selection using the paralleling technique. The long axis of the POSTERIOR PERIAPICAL for Adults film is vertical. For posterior films, # 2 size film is used with the long axis horizontal. For the posterior periapical, the # 2 size film is placed horizontally in the biteblock. The film is rotated so the identifying dot (faint embossed circle) is down; this side of the film goes into the slot of the biteblock If horizontal, (dot-in-the-slot). you won’t see the root Push the film back against the biteblock support and slide it down the slot. Film For children with small mouths, the #0 size film is used Selection for both anterior and posterior periapical films. for Children However, if the child’s mouth is large enough to reasonably accommodate the larger size films (#1 Þ Reverse image – See the herring bone pattern anterior, #2 posterior) and the child is cooperative they should be used. Þ Beam can overcome the thickness of the lead Þ Exposed film - transparent GENERAL TECHNIQUE GUIDELINES For all periapical films, the teeth being radiographed must be in contact with the biteblock to avoid not having the apices of the teeth on the film. Make sure patient doesn’t just close lips tight around biteblock; have them part their lips so you can confirm the contact Þ Bite for the stability RINN PARALLELING INSTRUMENTS The Rinn paralleling instruments. They are color-coded, with yellow being the posterior instrument and blue being the anterior instrument. The metal bar connects to the side of the biteblock and the ring slides on the bar. As shown above, cotton rolls may be used in any area of the mouth to help support the biteblock, especially if an edentulous region or uneven teeth oppose the teeth being radiographed. Using a cotton roll also makes it more comfortable for the patient to bite in some situations. The cotton roll should be placed against the arch opposite the one being radiographed If a patient has partial denture or a complete denture in one of the arches, the appliance can be used to help support the biteblock when the patient closes. This is normally preferable to using cotton rolls Þ Gauge is more stable The film is placed in the biteblock so that the all-white side of the film Make sure that the denture is only used in the arch opposite to the packet faces the teeth and, by extension, the ring. (The colored one being radiographed. portion of the film is against the back support of the biteblock). When Partial dentures can not be left in the arch being radiographed because you look down through the ring, you should see the all-white side of the the metal framework will be superimposed over the image of the teeth film packet centered in the opening. pg. 14  After the patient is biting on the biteblock, and before aligning the PID, MAXILLARY CANINE the ring needs to be moved closer to the patient’s face. While supporting the bar with the fingers of the hand, slide the ring down Þ Maxillary canine most difficult to take since it is at the corner close to the face with other hand The film is centered on the canine. The film should be placed well back Always make sure the head is supported by the headrest before aligning in the mouth, away from the teeth, where the palatal vault is the the PID and exposing the films. highest. The PID should be aligned with the ring so that the end of the PID is equidistant from the ring and within ¼” of the ring. The PID doesn’t have to touch the ring and the placement doesn’t have to be perfect. Don’t spend excessive time making adjustments when aligning the PID. (remember: the paralleling technique is not very comfortable and the patient won’t appreciate any delays in exposing the film). Make sure the long axis of the film stays in line with the long axis of the tooth when the patient closes. If the film tips, place a cotton roll between the biteblock and the mandibular teeth to keep the film aligned with the canine. MAXILLARY CENTRAL-LATERAL This is a typical maxillary canine film (tooth 11). Note the overall* (red The film is centered on the contact between the central and lateral arrow) between canine and first premolar. This is usually not avoidable incisors. Make sure the mesial edge of the film crosses the midline in the maxillary canine region using the paralleling technique slightly (into the opposite central incisor), to insure getting all of the central incisor crown on the film. The film should be placed well back in the mouth, away from the teeth, where the palatal vault is the highest. Þ Overlap refers to the superimposition of part of one tooth over This is a typical maxillary central-lateral periapical film. Both the a part of the adjacent tooth. In this film, the mesial of the tooth crown’s and roots of the central and lateral incisors (#’s 9 and 10 in this #12 is “overlapping” the distal of #11 film) are completely visible. ALL POSTERIOR FILMS The film should be equidistant from the teeth in an anterior-posterior direction (the distance from the front edge of the film to the lingual surface of the teeth should be the same as the distance from the back edge of the film to the lingual surface of the teeth, indicated by red arrows below). The film should be positioned in this manner for both the premolar and molar radiographs. This helps to avoid overall (see errors). Although we routinely use the #1 size film in the anterior region because it is easier to place in the mouth due to its narrower width, it MAXILLARY PREMOLAR is also possible to use the #2 size film (for all anterior projections). However, when the #2 size film is used for the maxillary incisors, it is usually centered on the midline, allowing you to image all four incisors The film is positioned so that the anterior edge is at least in the middle on one film (the film at right is slightly cropped, cutting off the distal of of the canine, or more anterior if possible. The film is approximately the laterals) centered on the 2nd premolar. The top edge of film is approximately in the center of the palate (side-to-side). The premolar film below shows the first and second premolar and the first molar completely; a portion of the second molar is also seen. pg. 15  MAXILLARY MOLAR For all mandibular films, do not force the film down into the floor of the mouth trying to get the biteblock to contact the occlusal surface of The film is centered on the second molar. The top edge of the film is in the mandibular teeth. the center of the palate (side-to-side). The film should be centered on Position the film in a parallel relationship and let the patient guide the the second molar event if the third molars are not present. film into place as they close their mouth. Have the patient bite slowly and gently. The molar film below shows the first and second molars and the third molar region (the third molar has been extracted). The maxillary tuberosity (red arrow) is easy identifiable. The incisor film shows all four mandibular incisors. The distal aspects of the lateral incisors are often cut off but you can see these areas on the canine films. All four roots are clearly visible. Some patients have a maxillary torus, which is a bony growth in the center of the palate. If a palatal torus is present, place the film so that the top edge is on the opposite side of the torus away from the teeth being radiographed. The film should not rest on the torus. (See MANDIBULAR CANINE diagram below) The film is centered on the canine. The film should be placed back in the mouth, away from the teeth, as much as possible. The bottom edge of the film is placed under the tongue and as the film is uprighted into a parallel position, the tongue is pushed back slightly. This canine film shows the mandibular canine (#22) and most of the lateral incisor and first premolar. Some patients, especially larger individuals, will have longer than normal teeth. With the normal positioning of the film and alignment of the beam, the apices of the teeth will be above the edge of the film (not visible or "cut off") as seen in the film below. To compensate for this, increase the angle of the beam and raise the PID slightly (illustration below right). You are purposely foreshortening the image. You will not MANDIBULAR PREMOLAR know the teeth are longer from just looking at the patient, but if you have taken previous films, or you get films from another dentist, you The anterior edge of the film is positioned at least in the middle of the can identify the need to alter your technique. canine, or more anterior if possible. The film is approximately centered on the 2nd premolar. The film should be placed more toward the middle of the mouth, away from the teeth. This will be more comfortable for the patient. However, this is usually the most uncomfortable film taken on a patient using the paralleling technique. Þ Because the floor of the mouth is more shallow in the middle of the anteroposterior MANDIBULAR INCISOR The film is centered on the contact between the central incisors (midline). The film should be placed back in the mouth, away from the teeth, as much as possible. The bottom edge of the film is placed under the tongue and as the film is uprighted into a parallel position, the tongue is pushed back slightly. This premolar film shows the mandibular and second premolars, the first molar and part of the second molar. pg. 16  MANDIBULAR MOLAR PARALLELING TECHNIQUE ERRORS The film is centered on the 2nd molar. The film can be placed closer to The following slides identify some of the most common errors seen the teeth than in the premolar region. This film is more comfortable when using the paralleling technique. than the premolar film because the floor of the mouth is deeper in this Þ ALARA: as low as reasonably achievable region. Film Poor film placement is the most common error seen Placement when using the paralleling technique. This usually involves incorrect anterior-posterior positioning. The premolar film is often not far enough forward and the molar film is frequently not far enough back. The premolar film below is placed properly. The molar film, however, is too far forward, failing to image the third This mandibular molar film shows the first and second molars and the molar region. third molar region (the third molar was extracted). Þ RCT both crown and root In the anterior region, failure to properly center the film is a common error. In the film below, the mesial of Some patients may have bilateral mandibular tori, which are bony the central incisor is not visible because the film was growths on the lingual of the mandible in the premolar region. If tori positioned too far back. For the central-lateral film, are present, place the film so that it is between the torus and the the film must cross the midline slightly in order to tongue. Make sure the film doesn't rest on top of the torus. (See insure that all of the central incisor will be seen. diagram below). If the patient is not completely closed and biting on the biteblock (photo below), the top of the film will not be Patients with longer teeth will also require an alteration in technique in positioned to slow the ends of the roots (below right). the mandibular arch. Increase the angle of the beam (increase the Usually the patient will tighten their lips around the negative vertical angulation, e.g., change from -20 degrees to -35 biteblock when this occurs; ask the patient to part degrees) and lower the PID slightly (illustration below right). You are his/her lips so that you can make sure they are biting purposely foreshortening the image. properly. Cone Cone cutting occurs when part of the film is not Cutting covered by the x-ray beam. It results in a white (clear) area on the film because no silver halide crystals were exposed and were not converted to black metallic ADULT FULL-MOUTH SERIES, PARALLELING TECHNIQUE silver during processing. Using the paralleling instrument, it is very easy to align the beam with the An adult full-mouth series of films consists of 15 periapical film, 7 film. However, if the instrument is not assembled anterior (from canine to canine, 4 maxillary and 3 mandibular) and 8 properly (ring upside down; see diagram below), cone- posterior (premolar and molar films in each quadrant. cutting will result. Reverse If the film is placed in the biteblock so that the colored Film portion of the film packet faces the ring/teeth, the lead foil in the packet will be between the teeth and ANTERIOR FIRST the film. The pattern (herring bone) imprinted on the When taking films on a patient, you should always start with the anterior lead foil will be visible on the film (right side of film films. below) and the film will be lighter because the lead If you are doing a full series, start with the maxillary canine film and then keeps some of the x-rays from reaching the film. finish all the anterior films, both maxillary and mandibular. Then complete the posterior films, starting with the premolar, then molar, in each quadrant. When doing only a few films on a patient, start with the most anterior film and work your way back in the mouth. This sequence of taking films allows the patient to get use to the procedure with a minimum of discomfort and helps to avoid stimulation of gag reflex. pg. 17 Double When taking films, you should always place each film Glasses It is recommended that glasses be removed before Exposure in a container or paper bag immediately after it is taking radiographs, even if they are not expected to be exposed. Exposed films should never be placed in the a problem (mandibular films or bitewing radiographs). same area where unexposed films are located. If you If the glasses are left on, they may be in the path of inadvertently pick up an exposed film and use it for the x-ray beam when taking maxillary films and another exposure, the result is a double exposure. Two produce an image on the film (see below). different areas of the mouth are superimposed, making the images worthless. This is the worst error because two films have to be retaken. The film at left shows images of mandibular incisors and mandibular molars. The film was vertical for the incisors and horizontal for the molars. Failure to Removable partial dentures, as the name suggests, Remove should be removed prior to taking films. If the RPD is Appliances left in place in in the arch being radiographed, the image of the RPD will obscure the necessary diagnostic information. However, an RPD may be left in the mouth in the arch opposite the one being radiographed in order to support the biteblock. This is more effective than using cotton rolls in the edentulous regions. Patient If the patient moves slightly during the exposure of the Movement radiograph, the image will be blurred as in the film below. Always advise the patient to remain still for the very short time it takes to complete the exposure. Overlap As mentioned previously, the film must be kept equidistant from the teeth when taking posterior Film If you “soften” the film excessively by bending the radiographs. If the film is not placed properly, as in the Bending edges before placing the film in the biteblock, black diagram below left, overlapping will result due to the lines may be produced due to disruption of the improper horizontal angulation. Overlap is the emulsion in the areas where the film was bent. These superimposition of part of one tooth with part of the black lines can also be caused by bending the film when adjacent tooth (dotted circles below right). The red inserting it into the slot of the biteblock. If you just arrow represents the direction of the x-ray beam. push down on the film without pushing back on the biteblock support, this bending may occur. The radiograph below shows the overlap in the region of the crowns of the teeth “DIGIT” AL Make sure the patient is biting firmly on the biteblock IMAGE before aligning the tubehead. Do not allow the patient to hold the instrument in position. If this happens, the patient's finger may appear on the film (red arrows on film below). Incorrect The standard exposure settings on your x-ray machine Exposure will be acceptable for the majority of your patients. Factors However, if you are taking radiographs on a child you would need to decrease the settings. If your patient is very large, you would need to increase the settings. Underexposure results when the exposure factors are set too low for the patient size. Overexposure results when the exposure factors are set too high. pg. 18  INFECTION CONTROL PROCESSING IMMUNIZATION Put on new gloves Under safelight with gloved hands, remove the film from the film All dental personnel should have the appropriate immunization packet and allow them to drop on clean surface including Hepatitis B virus. Do not touch the film with gloved hands since it is considered contaminated PATIENT HISTORY Dispose of the film packet wrapper and carrying cup and remove and dispose the gloves Since film is not contaminated gloves are not necessary or needed in Every patient should have a current medical history. processing Should obtain history using a questionnaire. Þ Film has a lead inside for protection SOURCES OF INFECTION POSITION-DISTANCE RULE Saliva Blood Nasal Instruments o PID o Tube head o Control panel o Exposure switch o Dental chair o Lead apron o Walls and doorknobs BARRIER Gloves Mask Second, the operator should never hold films or sensors in place. Protective eyegear Film or sensor-holding instruments should be used. Household plastic wrapper If correct film placement and retention are still not possible, a parent Plastic bag or other individual responsible for the patient should be asked to hold Aluminum foil the sensor in place and, of course, be afforded adequate protection o Autoclavable with a leaded apron. Under no circumstances should this person be one of the office staff. “The less you touch, the less you worry about.” Third, neither the operator nor patient should hold the radiographic tube housing during the exposure. STERILIZATION AND DISINFECTION Suspension arms should be adequately maintained to prevent housing movement and drift. Sterilization – Produces the absence of all microorganism including spores. o Dry heat o Autoclave Disinfections – Process that results in the absence of pathogenic organisms but not spores. o Cold/chemical (glutaraldehyde) Antiseptics – Agents used on human tissue that are either bacteriostatic or bactericidal. o Bacteriostatic – Is a biological or chemical agent that stops bacteria from reproducing. o Bactericidal – Is a substance that kills bacteria. FILM PACKET Can use to avoid transmission of microorganism. CHAIRSIDE EXPOSURE PROCEDURE Cover all appropriate surfaces with plastic wrap, aluminum foil. Seat the patient and drape with lead apron. Wash hands with antiseptic soap and put on gloves. Make the required exposures, taking care to touch only the covered surface. If the procedure is interrupted and you have to leave the room remove the gloves, dispose them and put new one before resuming the work. If no other dental procedures are to be done, dismiss the patient and dispose of all contaminated barriers and supplies in the operatory and then disinfect the lead apron and other appropriate surfaces. Remove contaminated gloves and carry the film container to the darkroom. pg. 19  PRDM 134 | ROENTGENOLOGY | LECTURE MODULE: 2nd Topic for Midterms LESSON: Bisecting Angle Technique, Occlusal Technique, and Bitewing Technique 1st SEMESTER | S.Y. 2024-2025 Lecture notes typewritten by: Rhein Feniza BISECTING ANGLE TECHNIQUE DISADVANTAGES OF THE BISECTING ANGLE TECHNIQUE PATIENT PREPARATION When comparing the two periapical techniques, the disadvantages of the bisecting angle technique are: Prior to starting to take films, the patient must be positioned properly. 1. More distortion: because the film and teeth are at an angle to Seat the patient and ask them to remove their glasses and any each other (not parallel) the images will be distorted removable appliances. 2. Harder to position x-ray beam: as mentioned previously, Adjust the headrest to support the head while taking films. because a film holder is often not used it is difficult to visualize where the x-ray beam should be directed. Raise or lower the chair to a comfortable height for the operator. 3. Film less stable: using finger retention, the film have more Place the lead apron and thyroid collar on the patient. chance of moving during placement You are now ready to begin taking films. It is a good idea to inform the patient about the number of films you will be taking so they know what to expect DISTORTION BISECTING ANGLE TECHNIQUE In the bisecting technique, the long axis of the tooth is not parallel with the long axis of the film. Produced using this technique. In the left radiograph below, the buccal roots appear much shorter than the The bisecting angle technique is an alternative to the paralleling palatal root, even though in the actual tooth the lengths are not that technique for taking periapical films. The paralleling technique is much different. In the other radiograph taken with the paralleling recommended for routine periapical radiography, but there are some technique, the lengths are projected in their proper relationship instances when it is very difficult due to patient anatomy or lack of (minimal distortion). cooperation. In these situation, the bisecting angle technique may be used. The film can be held in the mouth with the thumb or index finger or a bisecting instrument may be used. During this discussion, finger retention will be stressed: patient acceptance of the bisecting instrument is not much better than for the paralleling instrument. 2 TYPES OF DISTORTION Elongation Foreshortening In the bisecting angle technique, the x-ray beam is directed perpendicular to an imaginary line which bisects (divides in half) the angle formed by the long axis of the tooth and the long axis of the film (see diagram below). HEAD POSITION When using a bisecting instrument, head position is not critical. However, when using finger retention, head position is important. When radiographing the maxillary arch. The head should be positioned so that the maxillary arch is parallel to the floor. For mandibular films, ADVANTAGES OF THE BISECTING ANGLE TECHNIQUE the head is tipped back slightly so that the mandible is parallel to the floor when the mouth is open (the mouth is always open when using When comparing the two periapical techniques, the advantages of the finger retention). Make sure head is supported by headrest. bisecting angle technique are: 1. More comfortable: because the film is placed on the mouth at an angle to the long axis of the teeth, the film doesn’t impinge on the tissues as much. 2. A film holder, although available, is not needed. Patients can hold the film in position using a finger. 3. No anatomical restrictions: the film can be angled to accommodate different anatomical situations using this When viewed from the front of the patient, the midsagittal plane technique (which divides the head into right and left halves) is perpendicular to the floor. ANATOMICAL VARIATIONS Anatomical situations which might require using the bisecting angle technique are: o A shallow palate o A large palatal torus o A shallow or tender floor of the mouth o A short lingual frenum (tongue-tie) pg. 8  FILM SELECTION FOR ADULTS SNAP-A-RAY The #2 size film is routinely used for all periapical films using the Another instrument that may be used for posterior periapical films is bisecting angle technique. The long axis of the film is vertical for the snap-a-ray shown below. The alligator haws hold the film tightly anterior films and horizontal for posterior films. and, since there is no support behind the film, the film can flex as the patient closes. This makes it more comfortable for the patient. FILM SELECTION FOR CHILDREN FINGER RETENTION For children with small mouths, the #0 size film is used for both anterior When using finger placement, always use the hand opposite to the and posterior periapical films. However, if the child’s mouth is large size side of the mouth being radiographed. (e.g., use the left index finger films, and the child is cooperative, they should be used. when taking the right maxillary premolar film). Use either thumb for the max incisor film, the thumb or index finger (opposite hand) for the maxillary canines, and the index finger for all mandibular films, and for the maxillary posterior films (opposite hand). Help the patient by positioning their thumb or finger where you want them to apply pressure. BISECTING ANGLE FILM PLACEMENT ANTERIOR PERIAPICAL The film placement below are appropriate for both maxillary and The # 2 (or # 0) size film is positioned vertically with the all-white side mandibular arches of the film facing the teeth. The identifying dot is placed at the incisal edge of the teeth. The thumb or finger is applied to the back (colored) side of the film at approximately the junction of the tooth with the gingiva: this provides good support for the film and avoid film bending. The film should extend ¼ beyond the incisal edges of the teeth. VERTICAL ANGULATION POSTERIOR PERIAPICAL Using finger retention of the film, there is no external guide to help you align the x-ray beam ,as there is when using the paralleling instrument. The # 2 (or # 0) size film is positioned horizontally with the all-white You have to “imagine” where the bisecting line is and align the beam side of the film facing the teeth. The identifying dot is placed at the perpendicular to this line. This makes the technique much more occlusal surface of the teeth. The finger is applied to the back (colored) difficult, but with practice it can be a beneficial adjunct to your side of the film at approximately the junction of the tooth with the radiographic technique gingiva; this provides good support for the film and avoids film bending. When suing this technique, keep in mind that all teeth incline slightly The film should extend ¼ beyond the occlusal surface of the teeth. toward the middle of the head; they are not straight up-and-down. This will influence your visualization of the long axis of the tooth and the angle it forms with the film. The x-ray beam is directed perpendicular to the bisecting line shown below. You can see the film’s long axis, but you have to “visualize” the inclination of the long axis of the tooth. Once you determine the angle, imagine the bisecting line and direct the x-ray beam at a 90-degree angle (perpendicular) to this line. This is the vertical angulation. BISECTING INSTRUMENT The bisecting angle instrument is shown below. Notice that the biteblock support, against which the film will be aligned, is not parallel with the ring; it is slightly angled to accommodate the In the diagram below, the tooth is imagined to be more upright than it bisecting technique. This slight tilt of the film does little to make really is. As the tooth is rotated into its correct inclination (click to film placement more comfortable for the patient over the rotate), the angle changes and the bisecting ling (green dotted line) is paralleling technique; that is why finger placement is recommended less steep, requiring an increased vertical angulation (green arrow). if the bisecting technique is indicated. Because most people imagine the tooth to be more upright than it really is, it is recommended that 5 degrees be added to the vertical angulation you have chosen. pg. 9  HORIZONTAL ANGULATION MAXILLARY PREMOLAR The horizontal angulation is adjusted so that a line connecting the Using the index finger of the opposite hand, position the film properly front and back edge of the PID (yellow line below) is parallel with a and align the beam vertically and horizontally. Center the x-ray beam line connecting the buccal surfaces of the premolars and molar (green on the film. line below). The x-rays will then be perpendicular to the film. MAXILLARY MOLAR Using the index finger of the opposite hand, position the film properly and align the beam vertically and horizontally. Center the x-ray beam on the film CENTERING THE BEAM Sometimes it is difficult to get the film far enough back to cover the For the anterior periapical it is easy to see the sides of the film and third molar region due to gagging or anatomy, and all of the third molar makes it easy to center the beam on the film side-to-side. You then will not be seen on the film. need to make sure the PID extends ¼ below the visible (incisal) edge of the film (maxillary arch) or above the visible edge (mandible). In the posterior region, the front edge of the PID should be ¼ anterior to the front edge of the film and the PID should extend ¼ beyond the visible (occlusal) edge of the film (above or below depending on which arch is being radiographed). These steps will help to ensure that the film is completely covered by the x-ray beam, avoiding cone-cuts. By rotating the tubehead so that the beam is directed more anteriorly, the third molar is projected on to the film, giving us the needed information. Note, however, the increase in overlap that results. MAXILLARY INCISORS The firm is held in place using the thumb of either hand. The x-ray beam is directed perpendicular to the bisecting line vertically and the horizontally angulation aligns the x-ray beam perpendicular to the film. The x-ray beam is centered on the film. The film shows both central incisors and most of the lateral incisors. MANDIBULAR INCISORS Using the index finger of either hand, position the film properly and align the PID as discussed earlier. All four incisors appear on the film. But for root canal treatments it best to show the incisal edge MANDIBULAR CANINE MAXILLARY CANINE Using the index finger of the opposite hand, position the film properly The firm is held in place using the thumb or index finger of the opposite and align the beam vertically and horizontally. Center the x-ray beam hand. (right hand for maxillary left canine pictured below). The x-ray on the film. # 22 is shown on the firm below. beam is directed perpendicular to the bisecting line vertically and the horizontal angulation should open the contact between the canine and first premolar (see next slide). The x-ray beam is centered on the film. The films shows tooth #11. In many patients, especially ones with narrow maxillary arch widths, it is difficult to align the film ideally because the top edge of the film contact the palate on the opposite side and doesn’t allow enough film MANDIBULAR PREMOLAR to register the apex of the canine. By rotating the film into a diagonal placement, this won’t be a problem. Using the index finger of the opposite had, position the film properly and align the beam vertically and horizontally. Center the x-ray beam CANINE HORIZONTAL ANGULATION on the film. If you direct the beam perpendicular to the canine, there will normally be overlap between the canine and first premolar. In order to open this contact, the horizontal angulation must be rotated posteriorly. Try to imagine the mesial surface of the first premolar and align the beam parallel with this surface. pg. 10  MANDIBULAR MOLAR Improper Film o As with the paralleling technique, improper film placement Placement is one of the most common errors seen in the bisecting angle technique. In the molar film below, the film was Using the index finger of the opposite hand, position the film properly placed too far forward, cutting off the distal root of the and align the beam vertically and horizontally. Center the x-ray beam second molar and failing to image the third molar region. on the film. This film clearly shows all of the third molar roots (#17). ADULT FULL-MOUTH SERIES o With finger retention, it may be hard to keep the film from rotating around the end of the finger as it presses the film against the teeth. This may result in a tipped film as seen Using the all #2 size film, an adult full-mouth series of films consists of below. Notice the tip of the second molar is not visible, 14 periapical films; 6 anterior (from canine to canine, 3 maxillary and 3 resulting in the need for a retake. (the teeth are also mandibular) and 8 posterior (premolar and molar films in each elongated; is this too little or too much vertical angulation?) quadrant). o It is important to place the film so that ¼ of film extends beyond the incisal edge (anterior) or occlusal surface (posterior). However, if too much film extends beyond, the roots of the teeth will usually not appear on the film. ANTERIOR FIRST When taking films on a patient, you should always start with the anterior films. If you are doing a full series, start with the maxillary o When placing the film using finger retention, it is important canine film and then finish all the anterior films, both maxillary and to make sure that finger pressure is applied where the film mandibular. Then complete the posterior films, starting with the is supported by tooth structure, ideally at the junction of the crown of the tooth with the gingiva. If the film is not premolar, then molar, in each quadrant. When doing only a few films supported film bending will result. In the canine film below, and work your way back in the mouth. This sequence of taking films the canine root “bends” off of the film. What other error is allows the patient to get used to the procedure with a minimum of seen on this film? discomfort and helps to avoid stimulation of the gag reflex. BISECTING ANGLE TECHNIQUES ERRORS Elongation o If you have too little vertical angulation, as in the diagram below, the image will be elongated or stretched out on the film. The angle the x-ray beam forms with the bisecting lines is less than 90 degrees. The red lines on the film Reversed Film o If the colored portion of the film faces the teeth being represents the actual length of tooth # 9; the black arrow radiographed, the lead foil in the film packet will be points to the end of the “image” of the tooth. between the teeth and the film. This results in the pattern stamped on the lead foil appearing on the film. The firm will also be lighter than the other films taken at the same time. What other situations could results in a film that is too light? Foreshortening o If you have too much vertical angulation, as in the diagram below, the image will be foreshortened or reduced in length. The angle the x-ray beam forms with the bisecting line is greater than 90 degrees. The red lines on the film represent the actual length of tooth # 9; the black arrow Cone Cutting o If the x-ray tubehead is not positioned properly. The x-ray points to the end of the “image” of the tooth. beam may not cover the entire film. This is known as conecutting, which results in a clear (white) area on the film where the silver halide crystals were not exposed to x-rays. In the diagram below left, the dotted circle represents where the x-ray beam should have been positioned; the solid circle shows the actual position of the x-ray beam (posterior). o When the bisecting angle technique with finger retention, the incisal edge/occlusal surface will always be in contact with the film. This part of the tooth will always appear at the same spot on the film no matter what the angulation is. However, the apex of the teeth, being farther away from the film, will be imaged at different positions depending on the vertical angulation. The arrows in the Film o If you try to make the film more comfortable for the patient diagram below identify where the apex of the tooth will be “Softening” by “softening” the corners or edges, the emulsion of the fil at different angulation; e.g., at 90 degrees the apex will be will be affected, resulting in black lines. With finger imaged lower on the film, shortening the overall image. retention, film placement is usually not very Remember, a 90 degrees angle between the x-ray beam, uncomfortable; therefore, film softening is not needed. and the bisecting line is the ideal alignment. pg. 11  Double o When taking films, you should always place each film in a NORMAL MAXILLARY OCCLUSAL Exposure container or paper bag immediately after it is exposed. o When films should never be placed in the same area where unexposed films are located. If you inadvertently pick up an The normal maxillary occlusal film is the most common occlusal film exposed film and used it for another exposure, the result is taken in the maxillary arch. The vertical angulation is set at 65 degrees. a double exposure. Two different areas of the mouth are Because of this angle, structures located toward the back of the mouth superimposed, making the images worthless. This is the may be projected off the back edge of the film and not be imaged. worst error because two films have to be retaken. Thyroid Collar o With finger retention of films in the mandibular arch, the TRUE MAXILLARY OCCLUSAL tubehead may be positioned so that the x-ray beam passes through part of the thyroid collar. This lead in the thyroid collar prevents x-rays from passing through, resulting in an The true maxillary occlusal film is not often used because of the much unexposed, clear area on the film. higher exposure time needed to properly expose the film. (because the vertical angulation is 90 degrees, the x-ray beam passes through the very dense frontal bone; this is the reason for the increased exposure). Structures located father back in the mouth are more likely to be imaged on this film. Incorrect o The standard exposure settings on your x-ray machine will Exposure be acceptable for the majority of your patients. Factors o However, if you are taking radiographs on a child you would need to decrease the settings. If your patient is very large, you would need to increase the settings. o Underexposure results when the exposure factors are set too low for the patient size. Overexposure results when the exposure factors are set too high. MANDIBULAR OCCLUSAL OCCLUSAL TECHNIQUE With the head tipped back as much as possible, the x-ray beam is directed at a 90 degree angle to the film. Bony expansion of the OCCLUSAL FILM mandible as well as abnormalities or pathology in the floor of the mouth can be imaged with this film. THE OCCLUSAL FILM IS USED TO: o Identify the extent of lesions in a buccolingual direction o Identify the buccolingual location of impacted teeth or other abnormalities o Show the location of developing teeth in children using # 2 size film o Image patients with trismus that have limited mouth opening OCCLUSAL TECHNIQUE OCCLUSAL TECHNIQUE Head Maxillary film: the maxillary arch is parallel to the floor; the EXPOSURE SETTINGS Position midsagittal plane is perpendicular to the floor. o The exposure times for the “normal” maxillary and mandibular Mandibular film: the head is tipped back so that the mandibular occlusal films are the same as for a periapical or bitewing film arch is as close to perpendicular to the floor as possible. of comparable film speed. For the “true” maxillary occlusal film, the exposure time is four times as long, allowing enough x-rays to pass through the frontal bone and properly expose the film. MODIFIED BISECTING OCCLUSAL If a patient has difficult opening the mouth due to trismus, an occlusal Film The film is placed so that the all-white side of the film (# 4 for Position adults, # 2 for children) faces the arch being radiographed. The film can be used to provide a reasonable image of the teeth. The film is film is usually placed with the long axis side-to-side, but this is centered on the side of interest with the long axis front to back. The not critical. The film is large enough to normally cover the entire beam is aligned using the bisecting angle technique. The images will be arch, but make sure it covers the area of interest. Position the greatly distorted, but ay provide the necessary information. film as far back in the mouth as possible and the patient gently bites on it to keep it in place. X-Ray Beam Position There are three types of occlusal films: o “Normal” Maxillary o “True” Maxillary o Mandibular For all three of these, the x-ray beam is centered on the area of interest. Because of the curved beam, the corners of the film that sticks out of the mouth are often not exposed, resulting in slight concuts. This is not an error, since these areas contain no needed information. pg. 12  BITEWING TECHNIQUE PATIENT PREPARATION BITEWING FILM 1. Explain procedure o Patient bites a “wing” or a tab that had been placed on the film 2. Position the patient upright in the chair 3. Adjust the headrest 4. Place and secure the lead apron 5. Remove all objects from the mouth TABS ANATOMICAL STRUCTURES FOUND IN A BITEWING FILM BITEWING FILM USES o Interproximal caries o Crestal bone levels o Restorations contours pg. 13  HORIZONTAL ANGULATION FILM POSITION PREMOLAR BITEWING : o Covers the distal of upper and lower canine, both premolars, first molar and at least a portion of second molar MOLAR BITEWING o Covers molars o If third molars are not erupted into the mouth, the film should be positioned more anteriorly. o Make sure ¼ of film posterior to the second molar pg. 14  VERTICAL ANGULATION BITEWING ERRORS Patient is not biting on the bite block Film placement Film bending If lingual tori are present, the film must be placed lingual to the torus. Horizontal angulation Make sure the film clears the palatal gingiva as the patient closes to keep film from being pushed down into mandible. Single overlap technique Long axis of film vertical show advanced periodontitis Cone cut 3 anterior, 4 posterior +10 vertical angulation (tabs) Film reverse pg. 15  Processing of X Ray Films - Dental Radiology - Lecture Slides Dental Radiology Kalinga Institute of Industrial Technology 39 pag. Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Film Processing After the films are exposed to radiation, they need to be processed in order to see the information on the film. This processing is done using special chemicals and takes place in a darkroom. The darkroom should have the following attributes: It must be light-tight. Since the silver halide crystals are sensitive to both x-rays and light, the area where films are processed must be completely dark, except for a safelight (see next slide). It must have hot and cold water available; a mixing valve, which regulates temperature, is recommended. It should have an adequate size and must be kept very clean (no spilled chemicals). Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Safelight Safelights are used in the darkroom to provide adequate light so that you can see what you are doing when you unwrap films for processing. The safelights have special filters that produce light that does not expose the film. Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Safelight Filters There are two filters currently available: an orange one (Morlite) and a red one (GBX-2). The orange one can only be used for D- speed film. The red one can be used for all film types (D-speed, F-speed, extraoral, and duplicating). Since most offices use both intraoral and extraoral film, it makes sense to always have a red filter. The new Kodak LED red filter (below right) provides more light than the older safelights. Morlite GBX-2 D-speed Intraoral, extraoral Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Safelighting (continued) 15 W 15 watt bulb The safelight should have a 15-watt bulb (older style safelight) and be mounted to the wall or ceiling at red filter least 4 feet from the area where the films are 4 feet unwrapped and loaded into the film processor. Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Film Fogging If you have a light leak or improper safelighting in the darkroom, the film may be fogged before it is processed. Film fogging is the exposure of more of the silver halide crystals than would normally be affected during the taking of a radiograph. The exposure of these extra crystals results in the film being darker than normal and will usually decrease the diagnostic value of the film. If a film is processed without being exposed to light or x-rays, it should come out completely clear (white on the viewbox). A fogged film will have an overall slight grayness (see below). clear, unfogged film film fogging Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Light Test In order to check for improper safelighting or light leaks, you can perform the following test. Unwrap a film in the darkroom and lay it on the top of the processor. Place metallic (opaque) objects on the film (coins below left) and wait for 3-4 minutes. Remove the objects and process the film. If the film comes out completely clear, everything is OK (below right). If you see the clear images of the metallic objects surrounded by gray, there is a light problem (below middle). Correct as needed. Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Latent Image When you take a radiograph, x-rays penetrate through the tissues and interact with the silver halide crystals on the film, creating exposure centers in the crystals. There are thousands of these crystals and the number that are affected is dependent on the number of x-rays reaching a particular area of the film. Many x-rays will penetrate through objects that have little density, such as air and soft tissue. Few, if any, x- rays will penetrate objects with high density, such as amalgam and gold restorations. This difference in x-ray penetration results in the formation of a pattern on the film known as the latent image. Latent means “hidden”; the image formed by the pattern can not be seen until the film is processed (see next slide). Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Latent Image Air/soft tissue Bone Amalgam/gold Many x-rays penetrate Fewer x-rays penetrate Few, if any, x-rays and expose many silver and not as many silver penetrate; silver halide crystals halide crystals are halide crystals not exposed exposed = Exposure centers Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Basic Steps of Processing After taking the films on the patient, they are taken to the darkroom for processing. The steps involved in processing are: 1. Development: exposed silver halide crystals converted to black metallic silver. 2. Rinsing: Used with manual processing only; developer solution removed from film before fixing 3. Fixing: unexposed silver halide crystals removed from film 4. Washing: all chemicals removed from film 5. Drying: after removing moisture, films can be handled for mounting Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Developing Development centers in crystals struck by x-rays are converted into black metallic silver Air/soft tissue Bone Amalgam/gold Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Developing (continued) Entire crystal converted to black metallic silver Air/soft tissue Bone Amalgam/gold Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Developing (continued) The crystals that do not have exposure centers are not affected by the developer if films are in the developer for the correct amount of time and the temperature of the developer is correct. However, if the films are left in the developer too long, or the temperature is too high, the developer will start to act on the crystals that were not exposed by x-rays (no exposure centers) and these crystals will also be converted to black metallic silver. This results in the film being darker than ideal. After the films are properly developed, they go into the fixing solution. (The films are rinsed first if using manual processing). Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Fixing In the fixing solution, the unexposed silver halide crystals are removed from the film by the fixing solution. Air/soft tissue Bone Amalgam/gold Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected]) After the films have been in the fixing solution for the specified time, the films are washed and then dried so that they can be mounted for viewing. The next two slides review the components of the developing and fixing solutions. Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Developing Solution Developer: Coverts exposed silver halide crystals into black metallic silver Preservative: Helps protect the developer from being oxidized by the air Activator: Provides alkaline solution needed by developer; also softens gelatin, allowing developer to reach crystals Restrainer: Reduces effects of developer on unexposed crystals Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Fixing Solution Clearing Agent: dissolves and removes unexposed silver halide crystals from emulsion Preservative: Inhibits decomposition (oxidation) of clearing agent Acidifier: Neutralizes any contaminating alkali from the developer Hardener: Hardens emulsion so film can be handled Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Automatic vs. Manual Processing Most offices use an automatic processor for film development. While it will produce a very good film if done properly, manual processing is very time and labor intensive, requiring a much longer processing time than automatic processing and requiring someone to be available to transfer films into the various solutions. Drying films also takes much longer. The following slides discuss both types of processing. Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Manual Processing With manual processing, two tanks, one containing developer and one fixer, are placed in a larger tank filled with water. The water is maintained at a certain temperature using a mixing valve. The film is first placed in the developer for a specified time, rinsed in the water, and then placed in the fixer. After fixing for the appropriate time, the film is washed in the water. The overflow tube prevents water from rising high enough to enter the developer or fixer tanks. Cold water inlet Hot Mixing valve Developer Fixer insert tank insert tank overflow tube waterbath (large tank) drain Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Manual Processing For manual processing, films are clipped to some type of film hanger (see below). The film should be handled only by the edges to avoid damage. The film hanger, with films attached, is then placed in the processing solutions, developer first. If the film is inadvertently placed in the fixer first, the film will come out completely clear (no image); the fixer removes all crystals that have not been converted to black metallic silver by the developer, even if they have exposure centers. Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Manual Processing Times Develop 5 minutes at 68 degrees Rinse 30 seconds (agitate continuously) Fix 4 minutes (Agitate intermittently; 5 seconds every 30 seconds) Wash 10 minutes in clean running water Hang films to dry Docsity.com Document shared on https://www.docsity.com/en/processing-of-x-ray-films-dental-radiology-lecture-slides/220852/ Downloaded by: kleinsu ([email protected])  Manual Processing lid After removing Placesilver The Remove hanger the film halide thecrystals films from with lid, theplace from films onthe wash the attachedfilms fixer the water film and inare into and the place the rinse hang convertedwater developer infilms the to and 5continuously forblack to water dry. (Click minutes. bath metallic tofor 10agitate complete The silver for minutes. lid isin 30 action). placed