centricjawrelation1autosaved-220205182724.pptx

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1. CENTRIC JAW RELATION Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 1

2. INTRODUCTION Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 2 “a maxillomandibular relationship, independent of tooth contact, in which the condyles articulate in the anterior-superior position against the posterior slopes of the articular eminences in this position, the mandible is restricted to a purely rotary movement; from this unstrained, physiologic, maxillo -mandibular relationship, the patient can make vertical, lateral or protrusive movements; it is a clinically useful, repeatable reference position’’[9]

3. INTRODUCTION IT IS CLASSIFIED AS: 1 . Centric relation. 2. Eccentric relation. A. Protrusive relation. B. Lateral relation. I. Right lateral relation. II. Left lateral relation Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 3

4. Maximal intercuspal position (MIP): The complete intercuspation of the opposing teeth independent of condylar position, sometimes referred to as the best fit of the teeth regardless of the condylar position, is also called maximal intercuspation. Centric occlusion (CO): The occlusion of opposing teeth when the mandible is in CR. This may or may not coincide with the MIP. CR is a bone-to-bone relation, while MIP and CO are tooth-to-tooth relation. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 4

5. MUSCLES INVOLVED IN CENTRIC RELATION Centric relation is not resting or postural position of the mandible. Contraction of muscles is necessary to move and fix the mandible in this position. The anatomic attachments of the posterior and middle parts of the temporal and suprahyoid muscles together with EMG studies show that these muscles move and fix the mandible in its most retruded relation to maxilla. Temporal , masseter and medial pterygoid muscles elevate the mandible. The lateral pterygoid muscle shows little activity when mandible is in centric relation. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 5

6. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 6

7. THEORIES OF CENTRIC RELATION Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 7 Saizer P. Centric relation and condylar movement: anatomic mechanism. J Prosthet Dent 1971;26(6):581-91.

8. THE MUSCLE THEORY Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 8 DEFENCE REFLEX CONTRACTION OF LATERAL PTERYGOID MUSCLE HALTS THE JAW centric relation is always the same at any vertical level, nor does it explain the most posterior mandibular position. no anatomic explanation is provided for the posterior hinge movement, nor for the acuteness of the “needle-point” tracing.

9. THE LIGAMENT THEORY Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 9 LIGAMENTS WHEN BECOME TENSE THEY DETERMINE THE LIMITS OF RETRUSIVE MOVEMENTS Ligaments bind the elements of the articulations, limit their possibilities of movement, and are also capable of determining terminal border positions. When the condyle is seen in lateral radiographic views in centric relation, it appears to be “suspended” or “floating.” the anatomic arrangement of the temporomandibular ligaments is not well suited to halt the retrusive condylar movement. ligamentous retrusive terminal stop provides no satisfactory location for the hinge axis. does not explain satisfactorily the lateral border movements,

10. THE OSTEOFIBER THEORY Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 10 retrusive terminal stop formed by the soft tissues of the posterior part of the roof of the glenoid fossa. this fibrous stop acts as a buffer. these tissues to be loose, fibrous, and functionally differentiated. He named this structure the “retroarticular cushion.”

11. THE MENISCUS THEORY Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 11 When the disc is in its postural position, or close to it, the upper synovial cavity continues down and backward, within the retroarticular fibrous tissues Discs with their retromeniscal fibrous tissues--stop the retrusive condylar movements

12. RELATING CENTRIC RELATION TO CENTRIC OCCLUSION C entric relation must be accurately recorded so that centric occlusion can be made to coincide with it. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 12 In the natural dentition CO is usually located anterior to CR, the average distance being 0.5 to 1 mm. If natural tooth has interferences in CR it initiate impulses and responses that direct the mandible away from deflective occlusal contacts into CO. Impulses created by closure of the teeth into CO establish memory patterns that permit the mandible to return to this position, usually without tooth interferences

13. RELATING CENTRIC RELATION TO CENTRIC OCCLUSION Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 13 The edentulous patient cannot control mandibular movements or avoid deflective occlusal contacts in CR in the same manner as the dentulous patient. Deflective occlusal contacts in CR cause movement of denture bases and displacement of the supporting tissues or direct the mandible away from this relation

14. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 14

15. RELATING CENTRIC RELATION TO HINGE AXIS Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 15 The upper cast can be accurately oriented to the opening axis of the articulator by the location of the physiologic transverse hinge axis and a facebow transfer. Opening and closing the jaws with mandible in its most retruded position to maxilla ( terminal hinge axis ) is the method used to locate transverse hinge axis. They occur without translation. Centric relation is the most retruded relation of mandible to maxilla at a particular vertical relation along pathway of terminal hinge movement. So the lower cast automatically gets oriented to opening axis of articulator with accurate centric relation recorded.

16. SIGNIFICANCE OF CENTRIC RELATION More definite than VD Most comfortable position(home of the mandible) Optimum position for health comfort and functioning of TMJ Movements of mandible start from here and end up here. physiologically acceptable position for mastication of food. Most posterior border position Acts as a reference point. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 16

17. SIGNIFICANCE OF CENTRIC RELATION Pure rotations take place. Bone to bone relation Independent of position of tooth. Constant for an individual. Reproducible, repeatable and recordable. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 17

18. FACTORS INFLUENCING CENTRIC RELATION RECORDS Resiliency of supporting tissues Fit of denture bases – Stability - Retention The TMJ and its associated neuromuscular mechanism The character of the pressure applied in making the recording. The technique used in making the recording and the associated recording devices used. Maxillo-mandibula r relationship . Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 18 Yurkstas AA, Kapur KK. Factors influencing centric relation records in edentulous mouths. J Prosthet Dent 2005;93:305-10 .

19. FACTORS INFLUENCING CENTRIC RELATION RECORDS The skill of the dentist. The health and co-operation of the patient. Posture of the patient. Character or size of the residual alveolar arch. Amount and character of saliva. Size and position of the tongue. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 19 Yurkstas AA, Kapur KK. Factors influencing centric relation records in edentulous mouths. J Prosthet Dent 2005;93:305-10 .

20. FACTORS INFLUENCING CENTRIC RELATION RECORDS Psychic or emotional tension. Protective reflex action caused by faulty occlusal contacts. Materials and equipment used for record making. The use of articulators that do not accurately adjust to all inter occlusal check records. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 20 Yurkstas AA, Kapur KK. Factors influencing centric relation records in edentulous mouths. J Prosthet Dent 2005;93:305-10 .

21. RECORDING CENTRIC RELATION Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 21

22. COMPLICATIONS IN RECORDING CENTRIC RELATION The structure of TMJs are such that one joint can be displaced downward by uneven pressure when records are made and yet the condyles be in their most retruded position. This situation cannot occur on the articulator and thus a deflective occlusal contact may be the source of instability, soreness and resorption despite the correctness of the other relations. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 22

23. COMPLICATIONS IN RECORDING CENTRIC RELATION REALEFF EFFECT BY HANAU : according to it, there is uneven resiliency in the soft tissues. This resiliency is present in both the mucosa and the TMJs, thus undue pressure in securing the relation must be avoided lest excessive displacement of soft tissues occur . Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 23

24. COMPLICATIONS IN RECORDING CENTRIC RELATION Even though a balanced and equilized registration has been made it often is lost due to: Cast mounting procedures Processing of denture Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 24

25. RETRUDING THE MANDIBLE IN CENTRIC RELATION BIOLOGIC Lack of coordination between muscles. Habitual eccentric jaw positions Senility or neuro-muscular disorder PSYCHOLOGIC Inability to follow the dentist instructions MECHANICAL Poorly fitting base plate Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 25

26. METHODS PASSIVE METHODS : The mandible is retruded by the patients themselves, following the dentist’s instructions without any physical participation by the dentist. The patient is instructed to Relax, pull the jaw back and close on the back teeth. Get the feeling of pushing the upper jaw out and close on back teeth. Touch the posterior part of the upper denture with tongue and close till the rims contact. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 26

27. METHODS 4. Swallow and close. 5. Tap the occlusal rims together repeatedly and rapidly. 6. Tilt the head back while performing the above exercises. 7. Protrude and retrude the mandible repeatedly holding his/her fingers lightly against the chin. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 27

28. METHODS ACTIVE METHODS : The patient is guided to retrude the mandible with physical assistance from the dentist. The dentist places his thumb and forefinger on the patient’s chin to exert a mild but firm posterior force while patient closes on the rims. This will prevent the patient from moving the jaw anteriorly Dentist palpates the temporal and masseter muscles to relax them. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 28

29. METHODS Dawson’s bimanual palpation – the dentist stands behind the patient and places all four fingers of both hands on the lower border of the mandible on either side. The thumbs are placed over the symphysis such that they contact in the midline. The patient is instructed to open the mouth and then close slowly . As the patient closes, dentist applies an upwards lifting force with the fingers on the inferior border and simultaneously applies a downward force with the thumbs . This guides the patient to close in CR. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 29

30. METHODS OF RECORDING CENTRIC RELATION Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 30 Bansal, e t al, Critical evaluation of methods to record centric jaw relation, The Journol of lndion Prosthodontic Society ; July 2OO9 ,Vol 9: lssue 3

31. METHODS OF RECORDING CENTRIC RELATION BY BOUCHER Static methods — interocclusal record with/with out central bearing devices and tracing devices Functional methods — chew-in technique Needles technique House technique Patterson technique Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 31

32. STATIC METHOD Involves guiding the mandible in CR with the maxillae then making a record of the relationship of the two occlusion rims to each other. ADVANTAGE - minimal displacement of the recording bases Record made with wax or plaster DISADVANTAGES: • Inaccuracy can result from lack of equalized pressure. • Difficult to verify the accuracy of the record. • Not as accurate as graphic method. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 32

33. 1. WAX OCCLUSAL RIMS One of the most commonly used methods to record CR. The wax occlusal rims are contoured and the vertical dimension of occlusion is established ensuring even contact of the maxillary and mandibular rims anteriorly and posteriorly. The patient is trained to retrude the mandible. The various ‘guidelines’ are marked and the patient is asked to close in centric and hold the position. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 33

34. The rims are joined or sealed in this position and then removed from the mouth and articulated. The following methods can be used to seal the rims: HEAT: A hot wax knife can be used to melt and flow the wax at the junction of the rims. Care must be taken to avoid heating the lips and cheeks by adequately protecting and retracting them. The knife should not be hot enough to cause the wax to run Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 34

35. PINNING: The occlusal rims can also be sealed together using pins. Slightly warm metal staples can be used to join the sides of the rims Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 35

36. THE ABOVE METHODS OF SEALING ARE NOT RECOMMENDED DUE TO: Chances of burning and injuring lips and cheek. No equalization of pressure. Difficult to prevent movement of rims while sealing. NICK AND NOTCH METHOD: This is the recommended method for sealing the rims as there is less resistance to closure and the movement during sealing is tackled. After the rims are evened, V-shaped notches are then placed in the molar region of the maxillary occlusal rim to prevent anteroposterior movement. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 36

37. A nick is cut anterior to the notch in the premolar regions, not extending throughout the width of the occlusal rim, to prevent the lateral movement. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 37

38. A trough is created in the posterior regions of the mandibular occlusal rims The patient is trained to retrude and close at CR position. Soft wax, zinc oxide eugenol impression paste, quick setting plaster and elastomeric bite materials may be used . Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 38

39. The recording material is loaded in the trough created on the mandibular rim. Occlusal rims are inserted in the patient’s mouth and the patient is instructed to retrude and close. Contact should be observed in the maxillary and mandibular rims anteriorly. Once the intervening recording material sets, the rims get sealed and are removed together Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 39

40. 2. INTER-OCCLUAL CHECK RECORS As the name suggests, these records are used to verify the centric jaw relation at the time of try-in or denture insertion. They are also used to check the occlusion of teeth in existing dentures. These are also called ‘physiologic’ methods as the patient’s proprioception and tactile sense is essential in the making of an accurate record. The same recording mediums used for static registrations can also be used for this procedure Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 40

41. After the occlusal rims have been articulated with a static record, the artificial teeth are arranged and a trial denture is fabricated. At the time of try-in (or denture insertion) if the dentist feels the need to verify the CR, then this procedure is adopted. Patient is asked to rehearse retruding the mandible. The maxillary trial denture is inserted in the patient’s mouth. The recording medium like aluwax is loaded onto the occlusal surface of the teeth in the mandibular occlusal rim Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 41

42. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 42

43. The patient is asked to slowly retrude the mandible and close on the wax till the tooth contact occurs . They should not bite through the material. The recording material is allowed to set and the trial dentures are removed with the recording material. The maxillary trial denture is removed from the record and placed on the mounted maxillary cast in the articulator. The mandibular trial denture with the record is now returned to the mandibular cast on the articulator. The horizontal condylar guide locks in the articulator are released. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 43

44. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 44

45. The maxillary teeth are now seated over the record. If the previous recording of CR is the same as the check record, then both the condylar elements of the articulator will contact the centric stops, i.e. the articulated casts need not move to fit into the check records. If anyone or both of the condylar elements of the articulator does not contact the centric stops, it indicates that one of the records is inaccurate. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 45

46. INDICATIONS: It may be advisable to make interocclusal check records to verify the CR in the following conditions: Abnormally related jaws Displaceable, flabby tissues Large tongue Uncontrolled mandibular movements Factors affecting the success of interocclusal records : Uniform consistency of the recording material Accurate vertical jaw relation records Stability and fit of the record base Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 46

47. FUNCTIONAL METHOD Involves functional activity or movement of the mandible at the time the record is made. Disadvantage - causes lateral and anteroposterior displacement of the recording bases Includes the various chew-in techniques : Needlehouse Patterson Meyers Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 47

48. Needle–House method: Occlusal rims are fabricated from impression compound . Four metal balls or styli are embedded in the canine and molar areas of the maxillary occlusal rim. The occlusal rims are inserted and the patient is asked to perform various functional and excursive movements of the mandible with the styli contacting the lower rim. The vertical height is reduced as the styli cuts through the lower rim and the patient is stopped at the appropriate vertical dimension. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 48

49. The styli makes three-dimensional diamond-shaped tracings , which can be transferred to a suitable articulator to duplicate the movements. The most anterior point of the marking denotes CR and can be used to mount on any articulator Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 49

50. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 50

51. PATTERSON method: Wax occlusal rims are fabricated. A trench or trough is made in the mandibular occlusal rim which is filled with equal mixture of carborundum paste and plaster . The occlusal rims are inserted and the functional mandibular movements will produce compensating curves in the plaster lower rim. As the vertical height reaches the appropriate level, the patient is asked to retrude his jaw and the occlusal rims are joined together with metal staples. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 51

52. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 52

53. MEYER’S method: Used soft wax occlusal rims. Tinfoil was placed over the wax and lubricated. Patient performed functional movements to produce a wax path Plaster index was made Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 53

54. GRAPHIC METHODS The earliest graphic recordings were based on studies of mandibular movements by Balkwill in 1866 . The intersection of the arcs produced by the right and left condyles formed the apex of what is known as GOTHIC ARCH TRACING. Hesse (1897)– First to make a Needle point tracing. Gysi (1910)– Improved needle point tracing . Phillips (1927)– He developed a plate for the maxillar occlusal rims and a tripoded ball bearing mounted on a jackscrew for the mandibular occlusal rim. He called this as the " Central Bearing Point ". Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 54

55. WHAT DOES THE TRACING REPRESENTS ? Border movements of the mandible in the horizontal plane and its apex is the most retruded position (relaxed position) of the mandible. Advantage of reproducibility – can verify the centric relation. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 55

56. CONCEPT: The concept consists of attaching a stylus (a writing device with a pointed end) to one occlusal rim and a plate to the other rim. The stylus traces or marks the path in the plate as the mandible performs excursive movements from the centric position. The tracing is typically in the shape of a ‘gothic arch’ or ‘arrow head’ if the patient is trained to move the mandible from centric to protrusive, right and left lateral positions. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 56

57. COMPONENTS: The tracing can be made intraorally or extraorally . The extraoral tracing device consists of a central bearing device and a tracing device . The central bearing device consists of a central bearing point and a central bearing plate. The tracing device consists of a stylus and a recording plate. The stylus or stud and central bearing plate attached to the maxillary occlusal rim, while the central bearing point and recording plates are attached to the mandibular rim. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 57

58. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 58

59. COMPONENTS: In the intraoral tracer , the central bearing device also performs the function of a tracing device. So there is only one set of device Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 59

60. Central bearing device is a very important aspect of the device. It should be placed in the geometric centre of the maxillary and mandibular arches to serve the following functions: ▪ Maintains vertical dimension. ▪ Equalizes the pressure by distributing the forces throughout the supporting tissues. ▪ Allows mandibular movement to be dictated by the condyles. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 60

61. ADVANTAGES Documented to be the most accurate method of recording CR. Allows equalization of pressure on the supporting tissues. Easily verifiable. Can also be used to record eccentric relations. DISADVANTAGES May be difficult to locate the centre of the arches which is very important for central bearing function and accuracy of tracing. More time consuming. Training patient in making mandibular movements is strenuous. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 61

62. INDICATIONS Broad edentulous sides. Adequate interarch space. In patients with habitual centric, the use of the graphic method eliminates all occlusal contacts on the rims, thus breaking the neuromuscular reflex and allows the patient to record his true centric. CONTRAINDICATIONS Severely resorbed ridges and excessively flabby ridges as they lead to instability of denture bases. Decreased interarch space – difficult to place central bearing device without raising the vertical dimension. TMJ arthropathy. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 62

63. PROCEDURE FOR EXTRAORAL TRACING: The maxillary cast is mounted on the articulator with a facebow transfer. The mandibular cast is oriented to the maxillary cast at the established vertical dimension with a static CR record. The condylar elements of the articulator are secured against the centric stops. The central bearing and tracing devices are mounted on the respective rims Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 63

64. The patient is seated with head upright, in a comfortable position on the dental chair. The record bases with the attached devices are inserted in the patient’s mouth. They are checked for stability, contact during mandibular movements and interference Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 64

65. The stylus is retracted and patient is trained to make various excursive movements passively and actively (if needed). Patient is instructed to move the jaw forwards, right and left from centric position. The Ney Excursion Guide has been used as an aid in training the patient but patient responds better to specific locations than numbers Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 65

66. When the patient is well trained in making the movements, the recording plate is coated with a thin coating of lacquer, precipitated chalk or dark coloured wax. The coating material should not provide any resistance to movement and produce a clearly visible tracing . The stylus is made to contact the recording plate and the patient is instructed to make the specific movements. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 66

67. When an acceptable tracing is made with a single sharp apex, a centric record is obtained. The rims and tracing are prepared to receive the centric record Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 67

68. The patient is instructed to retrude the mandible such that the stylus contacts the apex of the tracing. Quick setting plaster is injected between the rims and allowed to harden thus, the centric record is obtained. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 68

69. The rims are remounted on the articulator with the new record Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 69

70. DEVICES: a. Hight tracer Sears tracer Phillips tracer Chandra tracer Stansbery tracing device Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 70

71. PROCEDURE FOR INTRAORAL TRACING: The procedure with intraoral tracer is similar, but as the tracing is not visible while being made, a thin plastic disc with a central hole is fixed on the recording plate such that the hole is placed on the apex of the tracing. The patient closes with the tip of the stylus in the hole and this ensures that the patient closes in centric and maintains the position while the record is being made. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 71

72. DEVICES : a. Coble tracer Swissdent ball bearing bite tracer Micro tracer Functiograph Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 72

73. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 73

74. Evaluation of Gothic Arch Tracings : Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 74 Classical, pointed form The symmetry indicates an undisturbed movement sequence in the joints and uniform muscle guidance . Classical flat form Indicates distinct flat lateral movements of the condyles in the fossa .

75. Evaluation of Gothic Arch Tracings : Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 75 Weak Gothic arch tracing Indicates a lax and negligent performance of the movements . The registration must be repeated: Stronger movements must be demanded from the patient. Asymmetrical form The tracing indicates a distinct inhibition of the forward component of the lateral movement in the right joint.

76. Evaluation of Gothic Arch Tracings : Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 76 Miniature Gothic arch tracing This tracing points restricted mandibular movements. Due to badly fitting and pain-causing record bases or Long standing edentulous state with inhibited movement in the joints. Vertical line protrudes beyond the arrow point forcible retraction or pushing of the mandible or tracing obtained with protruded mandible

77. PANTOGRAPHIC TRACING: Pantograph: An instrument used to graphically record in, one or more planes, paths of mandibular movement and to provide information for the programming of an articulator (GPT8). Pantographic tracing ( pantogram ): A graphic record of mandibular movement usually recorded in the horizontal, sagittal and frontal planes as registered by styli on the recording tables of a pantograph or by means of electronic sensors (GPT8). Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 77

78. PANTOGRAPHIC TRACING: The pantograph is a device that records the movement in all three planes. The tracing is called a pantographic tracing or pantogram . To put it simply, it will consist of styli and recording plates placed in all three planes and the various jaw movements from centric position traced in all the planes . The recordings are transferred to a fully adjustable articulator, which is capable of accepting and reproducing these movements. This can also be used to record eccentric relations. Records are very accurate but procedure is complex Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 78

79. ECCENTRIC RECORDS DEFINITION: Any relationship of the mandible to the maxilla other than CR (GPT8). The relation recorded by moving the mandible forward is called protrusive relation record. The relation recorded by moving the mandible mesio - laterally is called lateral relation record . Eccentric relation depends on the shape of the mandibular fossae . Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 79

80. ECCENTRIC RECORDS Functional method- Needles-House and patterson technique. Graphic method. Tactile or Direct check methods. Pantography Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 80

81. SUMMARY Centric relation is a most Reproducible Reliable Repeatable Recordable Reference position. Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 81

82. REFERENCES Charles M . Heartwell JR. and rahn a. o:syllabus of complete dentures.fourth edition. John sharry , complete denture prosthodontics. Winklers , essentials of complete denture prosthodontics Carl . O. boucher :prosthodontic treatment for edentulous patients,10 edition. Ernest.r . granger:centric relation,j.p.d 1952:2 160-169 Kingery.r.h:problems associated with centric relation;j.p.d1952;2;307.. Shanahan T E. Physiologic jaw relations and occlusion of complete dentures. J Prosthet Dent 1955; 5: 319-322 Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 82 Bansal, e t al, Critical evaluation of methods to record centric jaw relation, The Journol of lndion Prosthodontic Society ; July 2OO9 ,Vol 9: lssue 3

83. REFERENCES Prosthodontic treatment foe edentulous patients- zarb-bolender 12 th edn . The Academy of Prosthodontics. Glossary of prosthodontic terms. J Prosthet Dent 1999; 81: 48-106. The Academy of Prosthodontics. Glossary of prosthodontic terms. J Prosthet Dent 1994; 71: 40-116. The Academy of Prosthodontics. Glossary of prosthodontic terms. J Prosthet Dent 2005; 94: 10-85. Saizer P. Centric relation and condylar movement: anatomic mechanism. J Prosthet Dent 1971;26(6):581-91. Palaskar , J.N., Murali, R. & Bansal, S. Centric Relation Definition: A Historical and Contemporary Prosthodontic Perspective. J Indian Prosthodont Soc Yurkstas AA, Kapur KK. Factors influencing centric relation records in edentulous mouths. J Prosthet Dent 2005;93:305-10. Centric relation records-Historical review Department of Prosthodontics, Crown & Bridge and Oral Implantology, DDCH, Udaipur 83 Bansal, e t al, Critical evaluation of methods to record centric jaw relation, The Journol of lndion Prosthodontic Society ; July 2OO9 ,Vol 9: lssue 3