MAXILLO MANDIBULAR RELATIONS IN COMPLETE DENTURE PROSTHODONTICS

CENTRIC RELATION

1. TO ACHIEVE SUCCESS…. HARDWORK IS THE KEY, HOPE IS THE LIGHT, PERSEVERENCE IS THE FUEL, BUT ABOVE ALL !!! ITS YOUR BLESSINGS ALLMIGHTY AND MY LOVING PARENTS!!!!! GOOD MORNING

2. STAFF INCHARGE: DR. HOMBESH M.N. SIR. PROFESSOR, DEPT. OF PROSTHODONTICS AND CROWN AND BRIDGE, COLLEGE OF DENTAL SCIENCES, DAVANGERE . PRESENTER: DR. KRUTIKA CHIKORDE. 2 nd YEAR POSTGRADUATE DEPT. OF PROSTHODONTICS, AND CROWN AND BRIDGE COLLEGE OF DENTAL SCIENCES, DAVANGERE . MAXILLO-MANDIBULAR RELATIONSHIP

3. CONTENTS INTRODUCTION DEFINATION AND TERMINOLOGIES CLINICAL SIGNIFICANCE OF JAW RELATION TYPES OF MAXILLO-MANDIBULAR RELATIONS Orientation jaw relation Terminal hinge axis Schools of thought regarding hinge axis theory Clinical significance of hinge axis. Facebow- History -Types and Parts -Steps for face bow record using Hanau spring bow. RECENT ADVANCES CONCLUSION REFRENCES Part 1 TO BE CONT… Vertical jaw relation Horizontal jaw relation

4. INTRODUCTION Complete dentures must be used in most functions once served by natural dentition. Mastication, speech and appearance all depend on specific vertical and horizontal relations of mandible to the maxilla. Many methods have been used to record these relationships, but there is no scientific proof that establishes the reliability of any one method. Common sense, judgment, knowledge, and clinical experience are most essential for critical evaluation of each patient in determining these relationships.

5. DEFINITIONS: Jaw relation is defined as -“Any spatial relationship of the maxilla to the mandible.” -(GPT-9) Jaw relation records- “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)

6. TERMINOLOGIES: Centric jaw relation-The most posterior relation of mandible to maxillae at the established vertical dimension. Eccentric jaw relation-Any jaw relation other than centric jaw relation. Orientation jaw relation-The mandible which is kept at its most posterior position,it can rotate in saggital plane around an imaginary transverse axis passing through or near the condyles. Vertical jaw realtion -The amount of separation between maxilla and mandible in the frontal plane. Horizontal jaw relation-Maxillomandibular relations in which condyles articulates with the thinnest avascular portion of their respective disc with the complex in the anteriosuperior direction against the slopes of the articular eminence.

7. CLINICAL SIGNIFICANCE OF JAW RELATION: To re-establish the functional position of the mandible. Comfort. Esthetics. Phonetics. Functional efficiency. Structural balance.

8. TO ACHIEVE THIS GOAL….. The recording must include an appropriate VD of occlusion. Stable occlusal contacts in harmony with the existing TMJ & masticatory muscle functions. The relationship between the prosthesis & oro -facial soft tissues and musculature.

9. CUSTOMISING THE OCCLUSAL RIMS: LABIAL FULLNESS: Facial esthetics as a guide. Phonetics as a guide. INCISAL VISIBILITY:  Generally the amount of tooth displayed at rest varies with age. FLAT OCCLUSAL PLANE:  Shunting effect must be prevented.

10. TYPES OF JAW RELATIONS: The three types are : Orientation jaw relation Vertical jaw relation Horizontal jaw relation -Centric relation -Eccentric relation-Protrusive records -Lateral records.

11. ORIENTATION JAW RELATION:

12. Orientation relations are those that orient mandible to the cranium in such a way that when the mandible is kept in its most posterior position, it can rotate in sagittal plane around an imaginary tranverse axis passing through or near the condyles. This record gives the angulation of the maxilla in relation to the base of the skull. The plane of the maxilla may be tilted in some patients, in such cases, the plane of the mandible will not be altered because it articulates with the base of the skull. Hence, a maxillary tilt will alter the relationship of the maxilla to mandible during different movements. It will also affect the level of the plane of occlusion of the denture. Orientation jaw relation can be recorded with a face-bow.

13. Transverse horizontal axis- An imaginary line around which the mandible may rotate within the sagittal plane. -GPT 9 Sagittal plane- Any vertical plane or section parallel to the median plane of the body that divides a body into right and left portions. -GPT 9

14. Terminal Hinge Axis- The opening movement to bring the jaw from occlusal to rest position is almost a pure hinge movement. Here the mandible moves on an arc of a circle with a definite radius from the temporomandibular joint. This path of the condyle is determined by the curvature of the condylar head and the curvature of glenoid fossa. Since the radius is not constant for all the patients, it has to be determined for every individual patient, i.e., the relation of maxilla to the opening and closing axis has to be determined. The upper jaw in the human skull is positioned uniquely to the lower jaw. This position is different for every person. Also, the anatomy of maxilla and the temporomandibular joint varies from persons to persons. Thus, recording of the orientation jaw relationship is very important which is done with the help of facebow record.

15. Hinge movement is a purely rotational movement of the joint, which takes place around a horizontal axis till the patient opens his mouth to about 20-25 mm. The hinge movement occurs when there is a 10-13° rotation of the condyle in the temporomandibular joint, which provides a jaw separation of 20-25 mm in the incisal region.

16. Clinical use of Terminal Hinge Axis- The location of the transverse hinge axis serves only to orientate the maxilla and to record the static starting point for functional mandibular movements. It does not record centric relation or condylar movements. It allows the transfer of the opening axis of jaws to the articulator so that occlusion would be on the same arc of closure as in the patients mouth. The condylar axis has to be located and duplicated on the articulator as the basic requirement for successful occlusal therapy. There is a need to accurately locate the hinge axis to enable the accurate reproduction of occlusal relationships on an articulator.

17. Recording the transverse hinge axis- Mandibular hinging movement around the transverse hinge axis is repeatable. It is a starting point of lateral movements. Opening and closing movements of the mandible are reproduced in the articulator .

18. Controversies regarding hinge axis- Controversies have arisen over the presence of a single axis, The methods used to locate the axis, The method and validity of recording the positions on the skin for future reference, And the relation of the terminal hinge position to the position of centric relation.

19. 1. Absolute location of the hinge axis - McCollum(1939)- It is believed that the hinge axis is a component of all masticatory movements of the mandible and is to be considered for every mandibular movement. 2. Arbitrary location of the hinge axis - Craddock & Simmons(1952)- It is believed that the hinge axis is of considerable value, but it is not worth the effort to locate. It is not of significance if the hinge axis of the articulator does not coincide with the hinge axis of the patient. Four main schools of thoughts regarding hinge axis theory-

20. 3. Nonbelievers in the transverse axis location - Beck(1959)- It is believed that the hinge axis is only theoretical and not practical. It can’t be accurately located and can’t be reproduced by one axis of an articulator. Hence an arbitrary axis is acceptable. 4. Split axis theory – Slavens (1961)- It is believed that there are two separate hinge axes of rotation, one in each condyle and they exist parallel to each other.

21. Kurth and Feinstein said within 2 mm when restricting opening to ¾ inch at the incisal pin. Borgh and Posselt said within 1.5 mm when a 10 degree arc was used and within 1.0 mm when a 15 degree arc was used. Lauritzen and Wolford were able to achieve an accuracy of 0.2 mm when using a 10 degree arc of movement. J D.Preston , A reassessment of the mandibular transverse horizontal axis theory . J Prosthet Dent 1979 41:605-613. Accuracy in locating a true hinge axis-

22. A method to locate true hinge axis- Observing the motion of a stylus on a kinematic bow, as created by jaw movements, in relation to a flag fixed over the patients axis area. When the stylus no longer translates but rotates then the point is accepted .

23. Accuracy of an arbitrarily selected axis- Scallhorn found that 95% of the axis points located 13 mm anterior to the posterior margin of the tragus on the tragus-canthus line to be within a 5 mm radius of the kinematically located axis. Beyron found that approximately 87% of the located points were within a 5 mm radius of the arbitrary points. Lauritizen and Bodner found only 33% of the true axis points to be located with in a 5 mm radius of the arbitrary points. Teteruck and Lundeen found similar results. Nagy W, Smithy T, Wirth C. A ccuracy of a predetermined transverse horizontal mandibular axis point. J Prosthet Dent 2002;87:387-94.

24. Walker found that 20% of the true axis points were located within 5 mm from the arbitrarily selected point. Palik , Nelson, and White found that the earpiece face-bow related the maxillary cast to the hinge axis only 50% of the time. 92% of the time the arbitrary axis was located anterior to the terminal hinge axis. Preston, J. D - A single transverse horizontal axis can usually appear to be located, within the limits of accuracy of operators, equipment and patients. When a kinematic axis is located, this is a worthwhile clinical procedure to transfer the arc of rotation in the sagittal plane from patient to the articulator. J D.Preston , A reassessment of the mandibular transverse horizontal axis theory . J Prosthet Dent 1979 41:605-613.

25. Granger, E. R. - The hinge axis determines the arc of closure in every contacting position of the teeth. The path of closure is different from each open position of the mandible to tooth contact. This path results from the closing rotation combined with a gliding path of the axis. E. R.Granger . Clinical Significance of the Hinge Axis Mounting . Dent Clin North Am, Mar 1959:205-213.

26. WHAT IS A FACE BOW? An instrument used to record the 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 relationship to the opening axis of the articulator; customarily the anatomic references are the mandibular transverse horizontal axis and one other selected anterior reference point. -(GPT-9)

27. History of the face bow- In 1860- Bonwil l concluded that the distance from the center of the condyle to the median incisal point of the lower teeth is 10 cm, but, he did not mention at what level below the condylar mechanism the occlusal plane should be situated. In 1866- Balkwill demonstrated an apparatus to measure the angle formed by the occlusal plane of lower teeth & the plane passing through the condyles & incisal plane of lower teeth. In 1880- Hayes constructed an apparatus called ‘ Caliper’ with median incisal point localized in relation to the two condyles. In 1890 Walker invented ‘ Clinometer’ used to obtain the relative position of the lower cast in relation to the condylar mechanism.

28. Gysi - constructed an instrument for registering the condylar path & used as face bow also. Snow - 1899 , constructed simple instrument which has become prototype for all the face bows constructed in present days. Stansberry - (1928) was dubious about the value of facebow and adjustable articulators. He thought that since an opening movement about the hinge axis took the teeth out of contact the use of these instruments was ineffective except for the arrangement of the teeth in centric occlusion. Mclean- (1937) stated that the hinge portion of the joint is the great equalizer for disharmonies between the gnathodynamic factors of occlusion. When occlusion is synthesized on articulator without accurate hinge axis orientation, there may be minor cuspal conflicts, which must be removed by selective spot grinding.

29. Sicher - (1956) stated “the hinge position or terminal hinge position is that position of the mandible from which or in which pure hinge movement of a variable wide range is possible”. Weinberg- (1961) evaluated the facebow mounting and stated that “ a deviations from the hinge axis of 5mm will result in an anteroposterior displacement error of 0.2 mm at the second molar”. Neol D.Wilkie - (1979) analyzed and discussed five commonly used anterior points of reference for a face bow transfer. He said that “not utilizing a third point of reference may result in an unnatural appearance in the final prosthesis and even damage to the supporting tissue”. He suggests the use of the axis - oribitale plane because of the ease of making and locating orbitale and therefore the concept is easy to teach and understand.

30. Parts of facebow- U-shaped frame Condylar rods/ear piece Bite fork Locking device Third reference point.

31. U- shaped frame- U-shaped frame forms the main frame of the facebow. All the other components are attached to this frame with the help of clamps. It extends from the region of one TMJ to other without contacting the face.

32. Condylar rods/Ear piece- Two small metallic rods on either side of the free end of the U shaped frame that contact the skin over the TMJ. They help to locate the hinge axis or the opening axis of the temporomandibular joint. They transfer the hinge axis of the TMJ by attaching to the condylar shaft in the articulator.

33. Bite fork- Bite fork “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 about 3 mm below the occlusal surface within the occlusal rim. Sometimes the bite fork is attached to the occlusal surface of the occlusal rim using impression compound in order to preserve the occlusal rim. This part of the face bow helps to fix the bite fork to the U-shaped frame firmly after recording the orientation jaw relation. Locking device-

34. A NTERIOR PATIENT REFRENCE- Third reference point is used to orient the face bow assembly to a anatomical reference point on the face along with the two condylar reference points.

35. Anterior reference points- Nasion Orbitale Orbitale minus 7 mm Alae of the nose

36. Nasion - The Nasion , can be approximately located in the head as the deepest part of the midline depression just below the level of the eyebrows. This reference point is widely used by Whip Mix articulator. Nasion guide is designed to fit into this depression which can move in and out but not up and down. Wilkie ND. The anterior point of reference. J Prosthet Dent 1979;41:488-96. 

37. Orbitale - Orbitale is the lowest point of the infraorbital rim of skull which can be palpated on the patient through the overlying tissues and the skin. One orbitale and the two posterior points that determine the horizontal axis of rotation will define the axis - orbital plane. Located by hanau facebow with the help of orbital pointer. Wilkie ND. The anterior point of reference. J Prosthet Dent 1979;41:488-96.

38. Orbitale minus 7mm- The Frankfort horizontal plane passes through both the poria and one orbital point. Because porion is a skeletal landmark, Sicher recommended to use the midpoint of the upper border of the external auditory meatus as the posterior cranial landmark on a patient. Most articulators do not have a reference point for this landmark. Gonzalez pointed out that this posterior tissue landmark on the average lies 7 mm superior to the horizontal axis. Wilkie ND. The anterior point of reference. J Prosthet Dent 1979;41:488-96. Sicher , H.: Oral Anatomy, ed 2. St. Louis, 195’. I‘hc C 1. .Mosby Cu.. p 91.

39. Alae of the nose- In most of the conventional complete denture techniques. It is imperative to make tentative or the actual occlusal plane parallel with the horizontal plane. Wilkie ND. The anterior point of reference. J Prosthet Dent 1979;41:488-96.

40. Posterior reference points- Prior to the aligning of facebow on face, posterior reference points must be located and marked. They are located by: Arbitrary method Kinematic method Arbitrary methods: Most commonly used measurements and landmarks- Bergstrom point Beyrons point Gysi’s point Snow point Denar point Brandrup- Wognsen point Lauritzen and Bodner’s point

41. Bergstrom point- 11 mm anterior to the center of the spherical insert for the external auditory meatus and 7mm below the Frankfort plane. Beyrons point- 13 mm anterior to the posterior margin of the tragus of the ear on a line from the center of tragus extending to the corner of the eye. Singh S, Rehan S, Palaskar J, Mittal S. Hinge axis - location, clinical use and controversies. Journal of Research in Dentistry 2017,4(6):158-161.

42. Gysi’s point- Gysi placed it 11–13 mm anterior to the upper third of the tragus of the ear on a line extending from the upper margin of the external auditory meatus to the outer canthus of the eye. 12 mm ant to post border of tragus and 5 mm inferior to line from EOM and outer canthus. Snow point- 11-13 mm anterior to tragus. Denar’s point-

43. Brandrup- Wognsen point- On line extending from the tragus to the lateral angle of eye, a point is marked at about 12mm in front of posterior margin of most prominent tragus. Lauritzen and Bodner’s point- A point 13mm anterior to the tragus on tragus-canthus line.

44. Selection of the right anterior point of reference is highly subjective which necessitate special attention during its selection. The objective is usually to achieve a natural appearance in the form and the position of the anterior teeth. Articulating the maxillary cast relative to the Frankfort horizontal plane will attain this goal. When this reference plane is used, the teeth will be viewed as though the patient was standing in a normal postural position with the eyes looking straight ahead. Wilkie ND. The anterior point of reference. J Prosthet Dent 1979;41:488-96.

45. Plane Of Orientation- The spatial plane formed by joining the anterior and posterior reference points. The horizontal plane is established on the face of the patient by 1 anterior & 2 posterior points, from which measurements of the posterior anatomic determinants of occlusion and mandibular motion are made.

46. Arbitrary face-bow- - Facia type. - Earpiece type - Hanau face-bow (Spring bow) - Slidematic (Denar) - Gysi face-bow - Twirl bow - Whipmix Kinematic or hinge bow- - Panadent face-bow -TMJ face-bow - Axiograph Face- bows can be classified as follows:

47. Arbitrary facebow- It is the most commonly used face-bow in complete denture construction. The hinge axis is approximately located. The condylar rods are positioned approximately 13 mm anterior to the auditory meatus on a line running from the outer canthus of the eye to the top of the tragus also called the cantho -tragal line. This is done using a Richey condylar marker. This is not done for earpiece type face-bows where the earpiece is inserted into the external auditory meatus. This method generally locates the rods within 5 mm of the true hinge axis of the jaws. As this is an arbitrary hinge axis, errors in jaw relation may produce occlusal discrepancies which should be corrected by minor occlusal adjustments during insertion.

48. Facia type- Here, the hinge axis or the posterior reference point is 13 mm anterior to the external auditory meatus and the anterior reference point is the orbitale (midpoint of the lower border of the orbit). The face-bow has a pointer that can be positioned to the posterior reference point. Earpiece type- The posterior reference point is the external auditory meatus and the anterior reference point is the orbitale . The earpieces engage into the posterior reference points (the external auditory meatus). It has been found that on an average external auditory meatus is 6-6.5 mm posterior and 2.5mm superior to the actual hinge axis point . Since the ear piece facebow has not been oriented to the arbitary hinge axis points as in case of facia face bow, during the transfer of ear piece facebow to the articulator, the ear plug is seated not on the condylar pins of the articulator but on the auditory pins of the articulator, which have the same dimensional relation to the axis of the articulator as existing between the hinge axis and the external auditory meatus.

49. Slidematic type (Denar)- This face-bow 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 intercondylar distance. These face-bows 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. In an edentulous patient the anterior reference point is 43 mm superior to the lower border of the upper lip in a relaxed state. This anterior reference point is also used for Whip mix articulators. The anterior reference point can be marked using a Denar reference plane locator. The plane locator is an instrument which resembles a face-bow.

50. Twirl bow- It is an arbitrary type of face-bow that does not require any physical attachment to the articulator. It is not commonly used for CD construction. It relates the maxillary arch to the Frankfort's horizontal plane. A mounting guide is used to mount the transfer rod to the articulator. It is easy to manipulate because the face-bow is not needed to mount the maxillary cast in the articulator. Whip mix facebow- These face-bows have a built-in hinge axis locator. It automatically locates the hinge axis when the earpieces are placed in the external auditory meatus. It has a nasion relator assembly with a plastic nose peice . The nasion relator determines the anterior reference point.

51. Steps for Face-bow Record using Hanau Spring Bow- The patient is seated in a comfortable position with his head upright and supported by the headrest. Posterior reference point : External Auditory Meatus. Anterior reference point : Orbitable . Guidelines for anterior teeth placement are marked on the maxillary occlusal rim. A notch index about 2 mm deep is made in the first molar region. This helps to position the bite fork.

52. The mandibular occlusal rim is placed in the patient’s mouth and reduced such that sufficient space is available between the two rims to accommodate the bite fork. The thickness of the bite fork and the wax together should not be more than 6 mm . The bite fork with the wax is inserted into the patient’s mouth. The midline of the bite fork should coincide with the midline of the maxillary occlusal rim. The stem of the bite fork should be parallel to the sagittal plane .

53. A thin layer of petroleum jelly is applied on both the occlusal rims to facilitate easy separation. The maxillary and mandibular occlusal rims are inserted into the patient's mouth. The U-shaped frame of the face-bow along with the condylar rods is positioned on the patient.

54. The patient is asked to close his mouth till both the occlusal rims get embedded into the bite fork. The stem of the bite fork is locked to the transverse rod of the face-bow. Any alterations in the position of the condylar rods should be checked. The entire face-bow assembly along with the occlusal rim is removed from the mouth and positioned (transferred) in the articulator.

55. Preparing the Facebow for Dentate patient using Hanau spring bow-

56. Kinematic facebow- This face-bow is generally used for the fabrication of fixed partial denture and full-mouth rehabilitation. The face-bow helps to orient the cast in the patient’s terminal hinge axis. The true hinge axis should be located and marked before using the face-bow. The location of the hinge axis is then transferred to the articulator with the face-bow. This face-bow requires a fully adjustable articulator to accept the true hinge axis (THA). Since the patient's hinge axis is transferred to the articulator, the movement of the articulator will simulate the movements of the joint made at the terminal hinge position.

57. Recording the Orientation Jaw Relation Using a Kinematic Face-bow- The kinematic face-bow is attached to the mandibular occlusal rim and the hinge axis is located based upon the opening movements of the mandible. Fabrication of the clutch- The first step involves the fabrication of a clutch. The clutch is a device, which relates the face-bow to the mandibular residual alveolar ridge. It is nothing but an occlusal rim made of impression compound with a bite fork attached to it. For dentulous patients, the clutch resembles a cap splint with a bite fork attached to it. It is usually fabricated and cast in aluminium . • A record base is fabricated over the mandibular cast. • An occlusal rim made of impression compound is built upon the record base. • The bite fork is attached to this occlusal rim. • Extending outside from the bite fork is its horizontal stem, which lies parallel to the sagittal (midline) plane.

58. Clinical procedure- The clutch along with the stem is placed in the patient’s mouth. The hinge bow (kinematic face-bow) is attached to the stem of the bite fork and the condylar rods are located at a point 13 mm in front of the auditory meatus on the Cantho tragus line. The patient should be placed in a semi-supine position and his mandible should be guided to produce opening and closing movements, which are purely rotational. The patient should also be asked to make eccentric movements. The condylar rods will move (either rotate or translate depending on the movement of the condyle) during the mandibular movements. The point at which the condylar rods show pure rotation indicates the terminal hinge axis (THA). If the patient opens his mouth widely (more than 12-15°) then the condylar rods will move anteriorly (translation). The condylar rods are locked in this position and the face-bow is removed. A tattoo representing the THA should be marked on the patient's face for further reference.

59. Indications to use Facebow- A definite cusp fossa or cusp tip to tip incline relation is desired. When interocclusal check records are used for verification of jaw positions. When the occlusal vertical dimension is subjected to change, and alterations of tooth occlusal surfaces are necessary to accommodate the change. To diagnose existing occlusion in patients mouth.

60. Advantages of using face bow- It aids in securing the antero-posterior cast position with relation to condyles of the mandible. It acts as an aid in the vertical positioning of the cast on the articulator. It assists in correctly transferring the inclination of the occlusal plane to the articulator .

61. Situations where face bow is not required- Monoplane teeth are arranged in balance occlusion and mandible in most retruded position at acceptable VD. No intended change in VDO. Articulator doesn't accept the transfer.

62. RECENT ADVANCES- Over the past few decades, the mechanical articulators used to simulate mandibular movements have been replaced or supplemented with dental computer-aided design/computer-aided manufacturing (CAD/CAM) systems . Currently, several CAD/CAM systems provide a virtual articulator simulation. Articulator was designed to record the exact movement paths of the mandible by using an electronic jaw movement registration system called Jaw Motion Analyser ( Zebris ) and then to move digitized dental arches along those paths in the computer. However, the main problem with those virtual articulators was transferring data from the patient to the simulation. Virtual facebow was developed to locate the maxillary digital cast of the patient in a cranial coordinate system.

63. The facebow and centric relation record have been used to orient dental casts on an articulator in the same relationship as that in the patient’s mouth. However, the shift to the virtual environment has only just begun in terms of the facebow, and standard methodologies need to be developed and tested before the virtual facebow is part of routine practice. The present protocol also allows the dentist to locate the mandibular digital cast exactly on the maxillary digital cast by using the virtual interocclusal record.

64. Overall, this technique constitutes a step forward because once the patient has left the dental clinic, the virtual patient remains in the computer. This virtual patient facilitates the work of the dentist and of the dental technician. Additional studies need to be conducted to validate the accuracy and the reproducibility of these promising new digital systems. The virtual patient technology currently available can only make use of a limited amount of actual patient data. In the future, a system, still to be fully developed, will need to integrate data on movement registration, occlusal records, digitalization, cast location, and 3D face geometry into the 3D virtual patient application.

65. CONCLUSION- Failure to use the face bow leads to error in occlusion. Hinge axis is a component of every masticatory movement of the mandible and therefore cannot be disregarded and this hinge axis should be accurately captured and transferred to the articulator, so it becomes a fine representative of the patient and biologically acceptable restoration is possible. It is recorded for verification of maxillomandibular relationship as it is required to design any restoration for oral rehabilitation. Knowledge of biologic and mechanical factors exercised by neuromuscular system for mandibular movements and jaw closure helps to utilize the mandibular hinge axis for planning oral rehabilitation.

66. REFRENCES: TEXTBOOKS:- Bouchers Prosthodontic treatment for edentulous patients-9 th edition. Essentals of complete denture prosthodontics - Sheldon winkler-2 nd edition. Prosthodontic treatment for edentulous patients - Zarb Bolender-12 th edition. Textbook of complete dentures – Rahn and Heartwell-5 th ediion . Oral Anatomy- Sicher , H. 5 th editionSt . Louis, 195’. I‘hc C 1. .Mosby Cu.. p 91.

67. SCIENTIFIC JOURNALS:- Rathee M, Singla S, Tamrakar A. Philosophy and Physics of Mandibular Hinge Axis: A Review;IJSR,3(4):373-74. J D.Preston . A reassessment of the mandibular transverse horizontal axis theory . J Prosthet Dent.1979 41:605-13. Wilkie ND. The anterior point of reference. J Prosthet Dent.1979;41:488-96. Nagy W, Smithy T, Wirth C. A ccuracy of a predetermined transverse horizontal mandibular axis point. J Prosthet Dent.2002;87:387-94. Singh S, Rehan S, Palaskar J, Mittal S. Hinge axis - location, clinical use and controversies. Journal of Research in Dentistry 2017,4(6):158-161.

68. YOU TUBE:- https://youtu.be/bq-OHtV_cuI. Brenes C, Jurgutis L, Babb CS. Digital face-bow transfer technique using the dentofacial analyzer for dental esthetics and 2-D, 3-D smile design: A clinical report. J Oral Science Rehabilitation,2018 Jun;4(2):22–30. Petre A, Drafta S, Stefanescu C, Oancea L. Virtual facebow technique using standardized background images. JPD,2019 May;121(5):724-28. Solaberrieta E, Garmendia A, Minguez R, Brizuela A, Pradies G. Virtual facebow technique. JPD,2015 Dec;114(6):751-55.

69. THANK YOU! HAPPY GANESH CHATURTHI.