Face Bow and Articulators PDF

Occlusion Face bow and articulators Refrence : Rahn p162-167 Zarb p195-202  Outline of the lecture ◼ Types of Face bows and articulators ◼ Objectives of face bow and articulators ◼ Definition: Face-bow The face bow is a caliper like device....

Occlusion Face bow and articulators Refrence : Rahn p162-167 Zarb p195-202  Outline of the lecture ◼ Types of Face bows and articulators ◼ Objectives of face bow and articulators ◼ Definition: Face-bow The face bow is a caliper like device. Used to: 1- Record the relationship between the maxilla & the rotational axis of the mandible,. 2- Transfer the relation from the patient to the articulator.  Types of face bow I-Kinematics face bow or mandibular face bow. II-Arbitrary face bow or maxillary face bow. ◼ Types: I- Mandibular face bow or kinematic face bow: It consists of : 1- U-shaped bow. 2-A clamp → attaches the bow to the mandible. (fits under the chin and fixes the lower occlusion block in place). 3-universal joint → attaches the clamp to the bow. 4-Two pointed condylar rods → attached to the bow. 5-Two Screws → adjust the position of the condylar rods. I- Mandibular face bow or kinematic face bow: ◼ Uses: Locate the exact terminal hinge axis before using of maxillary face bow: II-Arbitrary face-bow or maxillary face bow. ◼There are two types of arbitrary face-bow: 1- Facia face bow. 2- Ear piece face-bow. ◼ II- Maxillary face bow: It consists of a U-shaped bow & a bite fork which is attached to the bow by a universal joint and a clamp. A graduated condylar rod & a clamp at each end of the bow. ◼ Uses: Record the relationship between the maxilla & the rotational axis of the mandible, & this relation is transferred from the patient to the articulator: The bite fork is attached to the upper occlusion rim parallel to the occlusal plane and inserted in the patient's mouth. The lower occlusion block is inserted to support the upper block. The stem of the bite fork is slipped in the universal joint and the clamp is left loose..  An anterior reference pointer, the infra-orbital pointer,that contact the skin over the lowest part of the infra-orbital margin. It is used to relate the base plate and occlusion rim to the horizontal plane of the articulator as they are related to the patient’s frankfort plane. The condylar rods are positioned on a marked point 13 mm infront of the tragus on a line called canthus-tragus. Orienting the maxillary face-bow on the patient's face: The condylar rods are adjusted so that their ends lie on the points representing the condylar axis (either arbitrary through canthus-tragus line or exactly through the mandibular face bow). Both condylar rods should show equal calibrations with slight tension. The clamp is tightened. The condylar rods are released and the entire assembly is removed and ready for mounting the upper cast  Ear piece face bow The ear piece face-bow utilizes the external auditory canal as posterior reference points, the ear pieces are placed on the external auditory canal when adjusting the face-bow to the patient. Orienting the maxillary face- bow on the patient's face: Orienting the maxillary face- bow on the patient's face: Orienting the maxillary face- bow on the patient's face: Orienting the maxillary face- bow on the patient's face: Orienting the maxillary face-bow on the articulator Orienting the maxillary face-bow on the articulator Orienting the maxillary face-bow on the articulator TRANSFER JIG ASSEMBLY BITEFORK VERTICAL SHAFT CLAMP #2 CLAMP #1 FINGER ARTICULATOR SCREWS INDEX  Mounting the upper cast By Bonwill triangle Plasticine Studies have shown that there is no need for a facebow orientation for most complete denture cases, provided that the occlusal vertical dimension is not changed during the fabrication procedures. However, a facebow recording will place the dentures into a closer relationship with the anatomical closure axis of the patient and help minimize errors. Because using the facebow is a relatively easy procedure, it usually makes the articulating of the maxillary cast simpler and results in benefits making the denture fabrication process more accurate The type of occlusal scheme (balanced versus nonbalanced) will also determine the need for interocclusal records to program the condylar inclination on the instrument. Arbitrary facebows rely on facial and anatomical landmarks to record the position of the maxilla relative to the hinge axis and axis-orbital plane (or base of the skull). They are accurate enough to place the articulator hinge axis within 6 mm of the true hinge axis more than 80% of the time. This creates an acceptably accurate arc of closure, which will minimize occlusal discrepancies in the dentures. Articulators ◼ Definition: It is a mechanical device that represents the T.M.J. & jaw members. To which the maxillary & mandibular casts are attached → to simulate different mandibular movements. Articulators Class III articulator. A: Upper Member B: Lower Member C: Condylar Element or Post D: Condylar Housing E: Incisal Pin Various articulators are suited for complete denture fabrication. The most common type are Class III articulators, which accept a facebow and can use protrusive or lateral records to set the condyles ◼ Articulators are divisible into four classes. A class I articulator is a simple holding instrument capable of accepting a single static registration; vertical motion is possible. ◼ A class II articulator permits horizontal as well as vertical motion but does not orient the motion to the temporomandibular joints. ◼ A class III articulator simulates condylar pathways by using averages, or mechanical equivalents, for all or part of the motion; these instruments allow for orientation of the casts relative to the joints and may be arcon or nonarcon instruments. ◼ A class IV articulator will accept three dimensional dynamic registrations; these instruments allow for orientation of the casts to the temporomandibular joints and simulation of mandibular movements. ◼ 1- Simple hinge articulators or plain line articulators: It consists of an upper and lower members held at a certain distance by a screw which acts at the back. The screw can increase or decrease the distance between the two members. E.g. Gariot's articulator Records accepted: → Centric occluding relation. ◼ Gariot's articulator B- Simple hinge articulator: (Plane line): Diagram to show the essential features of the simple hinge articulator A, Hinge, B, Upper bow, C, Vertical stop mechanism D, Lower bow. ◼ II- Mean value articulator: e.g. Gysi simplex articulator Class II: Mean value articulators. Essential features of the mean value articulator A, condylar guidance mechanism, B, Upper bow, C, Incisal guide pin, D, Incisal guide plate , E, Lower bow.  Average Value The dimensions of these articulator reflect the average measurement recorded by Bonwill 10 cm between the central points of the condyle and mid incisal point of lower teeth. They also have condylar path representing the average sagittal condylar path 33. ◼ The articulators have upper and lower members, joined posteriorly by two condylar pillars. ◼ Terminated with joints representing the temporo- mandibular joints. ◼ The condylar path is fixed at an average angle range 33° to the horizontal plane. ◼ Records accepted: 1- Bonwill triangle → mounting the upper cast. 2- Centric occluding relation → mounting the lower cast. In Gysi articulator, the upper cast is mounted according to Bonwill triangle which is four inch (10cm) equilateral triangle extending posteriorly from one condyle to the other and joining the lower incisors contact point anteriorly.  Articulators BONWILL 1854 4” 4” Articulators ◼ III- Adjustable articulators: a- Semi-adjustable articulator: ◼ E.g. Hanau (Model H) articulator ◼ The horizontal condylar path angulation is adjusted by → a protrusive record obtained from the patient. ◼ The lateral condylar path angulation is adjusted → according to Hanau's formula. Semi-adjustable articulator Articulators Semi-adjustable Can alter; Condylor Guidance Angle Incisal guidance plate  Hanau (Model H) articulator Denar 5a Denar II - Arcon ◼ Records accepted: Bonwill triangle → mounting the upper cast. Centric occluding relation → mounting the lower cast. Protrusive record → adjust the horizontal condylar path. Hanau’s formula: ◼ used to → adjust lateral condylar guidance L = H/8 + 12 Where: L = Lateral condylar path. H = Horizontal condylar path. ◼ B- Fully-adjustable articulator: Both horizontal and lateral inclinations are adjusted → according to the records obtained from the patient. E.g. Hanau kinoscope. Dentatus articulator. ◼ Records accepted: 1-Bonwill triangle or face bow record → mounting the upper cast. 2-Centric occluding relation → mounting the lower cast. 3-Protrusive record → adjust the horizontal condylar path inclination. 4-Right lateral record → adjust the left lateral condylar path inclination. 5-Left lateral record → adjust the right lateral condylar path inclination.  Denar II Adjustable Condylar Angle, ISS & ◼ PSS ◼ No matter the number of adjustable parts or programmability, it is unlikely that any articulator will precisely duplicate the condylar movements in the temporomandibular joints. However, for complete denture patients and many dentate patients, exact accuracy is not necessary. ◼ However, for edentulous patients, the device must be attached to the record bases/occlusion rims, which are some what mobile because they are resting on movable tissues. Therefore, extreme accuracy in programming these articulators is difficult in complete denture patients. Fortunately this same accuracy is not required for edentulous patients, and complex articulators are not indicated for their treatment. ◼ Even though an articulator may not reproduce movements in an identical pattern as that of the patient, it is still accurate enough to establish proper occlusal and esthetic placement of the artificial teeth. Because the completed dentures rest on movable tissues, the use of an articulator for the final occlusal adjustments is preferable to perfecting denture occlusions intra orally. Indexing the cast: Indexing casts prior to mounting them on an articulator permits removal of the cast and accurate replacement to the articulator. It is also important for remounting procedures made for correcting occlusal errors after curing. It is accomplished by placing grooves or notches, or by using remounting plates.  Indexing the cast: Occlusal error in the finished denture,upper and lower dentures remounted to the original plaster for correction of occlusal errors.  Mounting the Master Cast on the Articulator: ◼ In the process of mounting master casts on a fixed condylar path articulator the following steps should be performed: Relation the cast to the articulator ◼ The cast should be positioned so that the midline of the occlusion rim is aligned with the tip of the incisal indicator pin anteriorly and the line drawn on the base. Is aligned with mark indicating the midline in the articulator posteriorly. Relation the cast to the articulator The basal surface of the cast should be painted with a separating medium. The cast and occlusion rim should be replaced on the occlusion plane table and the wax Rim should then be temporarily fixed to the table with wax.  Relation the cast to the articulator The cast can be the articulator should be closed and additional stone should be mounted with plaster. placed through the hole in the upper frame.  Relation the cast to the articulator After the stone has set, The lower cast is The lower cast should be mounted on its base related to the upper cast using a similar using an interocclusal technique to that used record and then they for the upper cast. should be firmly joined together with steel rods and sticky wax. Relation the cast to the articulator Thank You