Facebow record, transfer and articulation

A face-bow is a dental instrument used in the field of prosthodontics. Its purpose is to transfer functional and aesthetic components from patient's mouth to the dental articulator. Specifically, it transfers the relationship of maxillary arch and temporomandibular joint to the casts. It records the upper model's (maxilla) relationship to the External Acoustic Meatus, in the hinge axis. It aids in mounting maxillary cast on the articulator.
U-shaped frame - forms the main part of the frame with remaining components attached to it by clamps. Frame extends from the region of TMJ or external acoustic meatus to a distance of 2-3 inches in front of the face.[1]

Condylar rods – are positioned 13 mm anterior to the auditory meatus on the Canto-Tragal line. This placement generally locates the rods within 5 mm of the true centre of the opening hinge axis of the jaw.[1]

Bite fork – consist of stem and prongs. Wax material is usually attached to the bite fork, and the bite fork is held in contact with maxillary jaw or mandibular jaw in kinematic face-bow.[1]

Locking device – helps to attach the bite fork to the U-shaped frame.[1]

Orbital pointer with clamp – used as a third reference point. The pointer tip is placed in the contact with infraorbital notch which is 43 mm above the incisal edge of the right incisors.
Kinematic Face-bow - It orients jaw to actual hinge axis
Arbitrary Face-bow - It orients maxilla on an arbitrary hinge axis
Facia Type (With orbital indicator)
Ear Piece Type (With nasal relator)
Hanau face-to-face (spring bow)
Slidematic (Denar) [clarification needed]
Twirl bow
Whipmix
George B. Snow is credited as the inventor of face-bow.[2] In his version of face-bow, he positioned the plaster cast in the articulator in respect to distance of median incisal point from the condyles and all the other points on the occlusal plane. Snow attempted to give the occlusal plane an individual position also in this third dimension : and in order to achieve this he set about as follows. He fixed his bite-fork in the upper occlusion rim in such away that the handle, when the rim was placed in the patient's mouth. was parallel with a plane extending from the bottom of the glenoid fossa and passing through the anterior nasal spine. This plane cannot be determined directly on a living person; but it approximately corresponds with a line drawn from the upper part of the tragus to the lower edge of the nostril. In American literature, this plane is known as the Bromell plane, in Europe as the Camper plane. Snow then placed the bite-fork horizontally when the casts were mounted in the articulator

1. FACEBOW TRANSFER AND ARTICULATION DR ABHIDHA TRIPATHI DEPT OF PROSTHODONTICS

2. Introduction 1 2 CONTENTS Definition 3 4 5 6 7 Value of Facebow Recent advances Facebow Registration and Transfer Types of Facebow Indications Conclusion References 8 9

3. INTRODUCTION In 1899, George Snow introduced the facebow to help locate the rotation axis of the lower jaw. The procedure of facebow transfer confirms that the maxillary arch is oriented in the same or comparable distances to the hinges on the articulator as it is in the TMJ.

4. JAW RELATION OR MAXILLO-MANDIBULAR RELATIONSHIP DEFINITION: A registration of any positional relationship of the mandible relative to the maxillae. These records may be made at any vertical, horizontal or lateral orientation. -GPT 9

5. ORIENTATION JAW RELATION DEFINITION: The relations that orient the maxilla to the cranium in such a way that, when the mandible is kept in its most posterior position, the mandible can rotate in a sagittal plane around an imaginary transverse axis passing through or near the condyles. - GPT 9

6. Plane of maxilla may be tilted in some patients - plane of mandible will not be altered since it articulates with base of the skull. Hence , a maxillary tilt will alter the relationship of maxilla to mandible during different movements, also affects the level of occlusal plane . ORIENTATION OF MAXILLA IN RELATION TO BASE OF SKULL

7. ACCORDING TO GPT 9: AN INSTRUMENT USED TO RECORD SPATIAL RELATIONSHIP OF THE MAXILLARY ARCH TO SOME ANATOMIC REFERENCE POINT OR POINTS AND THEN TRANSFER THIS RELATIONSHIP TO AN ARTICULATOR; IT ORIENTS THE DENTAL CAST IN THE SAME SPATIAL RELATIONSHIP TO THE OPENING AXIS OF THE ARTICULATOR DEFINITION

8. VALUE OF THE FACEBOW Failure to use facebow can lead to errors in occlusion of denture. Allows more accurate arc of closure on the articulator. An integral part in analyzing and studying the occlusion.

9. INDICATIONS When interocclusal check records are used When balanced occlusion is desired When cusp form teeth are used In full mouth rehabilitation when accurate occlusal restorations are to be made For diagnostic mounting and treatment planning In gnathological studies and treatment

10. U SHAPED FRAME CONDYLAR RODS EAR PIECES BITE FORK LOCKING DEVICE ORBITAL POINTER PARTS OF FACEBOW

11. Represents the plane of the cranium It forms the main frame of the facebow All other components are attached to this frame. It extends from the region of TMJ on one side to the other side without contacting the face. U SHAPED FRAME

12. Two small metallic rods on either side of the free end of the U shaped frame that contact the skin over the TMJ. They are used to locate the hinge axis and transfer it to the articulator. Some facebows have ear piece that fit into the external auditory meatus instead of condylar rods CONDYLAR RODS

13. Represents the plane of the maxilla. U shaped plate which is attached to the occlusal rims while recording the orientation relation It is attached to the frame with the help of a rod called the stem. The bite fork should be inserted 3mm below occlusal surface within occlusal rim BITE FORK

14. Attaches the bite fork to the U shaped frame Supports the facebow, occlusal rims and cast during articulation. Consists of transfer rod U shaped frame is attached to the vertical transfer rod LOCKING DEVICE

15. Attaches the bite fork to the U shaped frame Supports the facebow, occlusal rims and cast during articulation. Consists of transfer rod U shaped frame is attached to the vertical transfer rod THIRD REFERENCE POINT

16. ARBITARY TYPE KINEMATIC TYPE TYPES OF FACEBOW EAR PIECE TYPE FACIA TYPE HANAU FACEBOW SLIDEMATIC TWIRL BOW WHIP MIX FACIA TYPE HANAU FACEBOW ATTACHED TO HANAU ARTICULATOR

17. ARBITARY TYPE TYPES OF FACEBOW KINEMATIC TYPE Earpiece Facia type HANAU Denar Slidematic Whipmix Quick Mount HANAU 132-25 M HANAU 132-2C Model TMJ Instrument Pantograph Axiograph

18. Most commonly used In this type the axis is located by using anatomical land marks. The condylar rods are positioned approximately 13 mm anterior to the auditory meatus on the cantho-tragal line ARBITARY TYPE This method generally locates the rods within 5mm of the true hinge axis of the jaws. As this is an arbitary hinge axis, errors in jaw relation may produce occlusal discrepancies which should be corrected by minor occlusal adjustments during insertion.

19. Facia type utilizes approximate points on the skin over the temporomandibular region as the posterior reference points. These points are located by measuring from certain anatomic landmarks on the face. The facebow has a pointer that can be positioned to the posterior reference point. FASCIA TYPE DISADVANTAGES: As the facebow is placed on the skin which is movable there is a tendency for the condylar rods to displace. Also requires an assistant to hold the facebow in place.

20. It uses external auditory meatus as an arbitary reference point Accurate relationship for most diagnostic and restorative procedures. Posterior reference point is External auditory meatus and anterior reference point is Orbitale EARPIECE TYPE ADVANTAGES; Simple to use Does not require measurements on face Provides an average anatomic dimension between EAM and horizontal axis of mandible DISADVANTAGES: An error of 0.2mm from the axis can be expected.

21. It is an earpiece facebow made of spring steel and simply springs open and close to various head widths. Most commonly used This instrument is designed to orient the occlusal plan to the Frankfort horizontal plane by means of a third reference point. indicated in cases when it is critical to precisely reproduce the exact opening and closing movement of the patient to articulator SPRING BOW (HANAU’S FACEBOW) ADVANTAGES: Easy and efficient to use one piece design of bow eliminates the moving parts and maintainence problems encountered with other models DISADVANTAGES: Inability to measure inter condylar distance Chairside assistance is required

22. It is an earpiece type of facebow Allows the maxillary arch to be transferred to the articulator without physically attaching the facebow to the articulator Relates the maxillary arch to FH plane A mounting guide is used to mount the transfer rod to the articulator Easy to manipulate because the facebow is not needed to mount the maxillary cast in the articulator TWIRL BOW

23. This facebow has an electronic device, which gives the reading that can be seen in the anterior region. This reading denotes one half of the patient’s inter condylar distance These facebows require specific articulators, which accept the reading. The posterior reference point for this instrument is the external auditory meatus and the anterior reference point is 43 mm superior to the incisal edge of the upper central incisor for dentulous patients. SLIDEMATIC TYPE (DENAR)

24. In an edentulous patient the anterior reference point is 43mm superior to the lower border of the upper lip in a relaxed state. This anterior reference point is also used for Whipmix articulators. The anterior reference point can be marked using a Denar reference plane locator. Tthe plane locator is an instrument which resembles a facebow. SLIDEMATIC TYPE (DENAR)

25. SLIDEMATIC TYPE (DENAR)

26. SLIDEMATIC TYPE (DENAR)

27. These facebow have a built in hinge axis locator. It automatically locates the hinge axis when the earpieces are located in the External Auditory Meatus. It has a nasion relator assembly with a plastic nose piece. The nasion relator determines the anterior reference point WHIPMIX FACEBOW

28. WHIPMIX FACEBOW

29. It is used to determine and locate the exact hinge axis points. Hinge axis of the mandible can be determined can be determined by a clutch i.e. a segmented impression tray like device attached onto the mandibular teeth with a suitable rigid material such as impression plaster. KINEMATIC FACEBOW

30. KINEMATIC FACEBOW

31. The facebow helps to orient the cast in the patients’s terminal hinge axis. A 12-15degree pure rotational movement of the joint is possible with maximal incisal separation of 20-25 mm This facebow requires a fully adjustable articulator to accept the true hinge axis. Since the patients hinge axis is transferred to the articulator, the movement of the articulator will simulate the movements of the joint made at terminal hinge position. KINEMATIC FACEBOW

32. Quick Mount facebow (with bitefork , nasion relator and Quick Lock toggle assembly) Whip Mix Articulator Plaster bowl Spatula Laboratory Knife with no 25 blade Trimmed Maxillary cast Mounting Stone FACEBOW ARMAMENTARIUM

33. Two horseshoe wax wafers (Surgident Coprwax Bite Wafer) are heated in warm tap water until they become soft and flexible. A wafer is adapted to each side of the bite fork so that it is uniformly covered. The wax-covered bite fork is placed between the teeth, with the bite fork shaft to the patient’s right. The fork is centered by aligning the index ring on the fork with the patient’s midline. FACEBOW RECORD TECHNIQUE

34. The patient is instructed to bite lightly into the wax to produce shallow indentations of the cusp tips in the wax. The wax is cooled, and the bite fork is removed from the mouth. Any excess wax is trimmed off the bite fork. The maxillary cast is tried in the wax record to ensure that it will seat without rocking. If the cast fails to seat, the occlusal surfaces of the cast are checked for nodules of stone. If none are evident, there is a distortion in the registration or the cast FACEBOW RECORD TECHNIQUE

35. The reference pin is fastened to the underside of the face-bow by tightening the thumbscrew. The bite fork is placed in the mouth, and the patient is instructed to hold it securely between the maxillary and mandibular teeth. The patient should grip both arms of the facebow to guide the plastic earpieces into the external auditory meati, in the same manner as one would place a stethoscope into the ears FACEBOW RECORD TECHNIQUE

36. The anterior reference pointer is extended while the facebow is moved up or down. When the pointer is properly aligned with the anterior reference point, the thumbscrew is tightened. The facebow should not be allowed to torque or tilt during the tightening procedure. FACEBOW RECORD TECHNIQUE

37. FACEBOW RECORD TECHNIQUE The bite fork is placed against the maxillary teeth and supported by the dentist as the patient closes lightly for a shallow impression of the cusp The patient guides the earpieces as the dentist places them into the external auditory meati

38. FACEBOW RECORD TECHNIQUE The dentist places the clamp over the bitefork shaft while the patient inserts the earpiece The thumbscrew on the front of the facebow is tightened

39. FACEBOW RECORD TECHNIQUE The shaft of the nasion relator is extended, and the thumbscrew is tightened The thumbscrew on the top of the facebow is tightened

40. FACEBOW RECORD TECHNIQUE The Quick Lock Toggle is slipped into the slot on the bite fork and the thumbscrew is tightened Complete facebow record

41. FACEBOW RECORD TECHNIQUE The thumbscrew on the top of the facebow is loosened The space between the facebow and the bite fork is checked for uniformity.

42. As the patient opens the mouth, the assembly is removed from the head. The clamps are rechecked and tightened. The bite fork assembly is removed from the underside of the facebow by loosening the set screw on the clamp by a quarter turn. Only the bite fork assembly needs to be used for mounting the maxillary cast and should be disinfected at this time. FACEBOW RECORD TECHNIQUE

43. In recent years, the incorporation of CAD/CAM technology has provided for more efficient protocols by automating processes and reducing manual labor . Intra-oral scanners can digitise dental arches and register maxillomandibular relationships. Currently, many CAD/CAM systems include a virtual articulator simulatory module as a tool to simulate mandibular movements, which can be adjusted by using numerical values to represent condylar inclination, Bennett angle, vertical dimension, etc. DIGITAL FACEBOW Solaberrieta E, Garmendia A, Minguez R, Brizuela A, Pradies G. Virtual facebow technique. J Prosthet Dent. 2015 Dec

44. Scan the maxillary and mandibular dental arches of the patient with an intraoral dental scanner to obtain digital casts Place 3 adhesive targets onto the patient’s head. Locate the first 2 points next to the temporomandibular joints and the third point onto the infraorbital point. Locate scannable elastomeric impression material on a plastic, colored facebow fork and introduce the facebow fork into the patient’s mouth DIGITAL FACEBOW Solaberrieta E, Garmendia A, Minguez R, Brizuela A, Pradies G. Virtual facebow technique. J Prosthet Dent. 2015 Dec

45. DIGITAL FACEBOW Solaberrieta E, Garmendia A, Minguez R, Brizuela A, Pradies G. Virtual facebow technique. J Prosthet Dent. 2015 Dec

46. DIGITAL FACEBOW Solaberrieta E, Garmendia A, Minguez R, Brizuela A, Pradies G. Virtual facebow technique. J Prosthet Dent. 2015 Dec

47. Make 8 to 10 photographs by using a digital camera to obtain the 3D spatial relationship of the shape of the head with target points related to the facebow. Scan the impression and the front side of the facebow fork with an intraoral dental scanner, load the facebow fork 3D geometry and align it to the maxillary digital cast by using the best-fit command DIGITAL FACEBOW

48. CONCLUSION Despite lot of controversies in facebow usage, hinge axis location and establishing plane of orientation is an important componenet for recording mandibular movement. 1 Facebow record helps in securing anteroposterior positioning of the cast in relation to condyles. It helps in achieving the exact anteroposterior or vertical positioning of cast irt condyles 2 The virtual facebow is a recent advancement and can align digital casts directly onto virtual articulator. this was developed to overcome the problem of transferring data from patient simulation to virtual articulators. 3

49. REFERENCES George A Zarb, Hobkirk J, Eckert S, Jacob R. Prosthodontic Treatment for Edentulous Patients: Complete Denture and Implant Supported Prostheses. South Asia Edition: Elsevier; 2015. Shillingburg HT, Hobo S, Whitsett LD, Jacobi R. Fundamentals of fixed prosthodontics. Quintessence Publishing Company: 1997 Schuyler CH. The function and importance of incisal guidance in oral rehabilitation. J Prosthet Dent 1963 Winkler S, editor. Essentials of complete denture prosthodontics. year book medical Pub 1988 Vivell C, Slavicek G, Slavicek R. Arbitrary versus exact mounting procedure during fabrication of intraoral splints: An exploratory randomized controlled clinical trial. Int J Stomatol Occl Med. 2009 Solaberrieta E, Garmendia A, Minguez R, Brizuela A, Pradies G. Virtual facebow technique. J Prosthet Dent. 2015 Dec;114(6):751-5. doi: 10.1016/j.prosdent.2015.06.012. Epub 2015 Sep 12. PMID: 26372628.