CENTRIC RELATION jaw relation Horizontal jaw reationppt
Download as PPT, PDF0 likes25 views
this presentation is regarding centric relation
CENTRIC RELATION jaw relation Horizontal jaw reationppt
- 2. 2 CENTRIC RELATION CENTRIC RELATION The maxillomandibular relationship The maxillomandibular relationship in which the condyles articulate in which the condyles articulate with the thinnest avascular portion with the thinnest avascular portion of their respective disks with the of their respective disks with the complex in the anterior-superior complex in the anterior-superior position against the shapes of the position against the shapes of the articular eminencies. This position articular eminencies. This position is independent of tooth contact. This is independent of tooth contact. This position is clinically discernible position is clinically discernible when the mandible is directed when the mandible is directed superiorly and anteriorly. It is superiorly and anteriorly. It is restricted to a purely rotary restricted to a purely rotary movement about the transverse movement about the transverse horizontal axis. horizontal axis. (GPT-5-1987) (GPT-5-1987)
- 3. 3 CENTRIC RELATION CENTRIC RELATION The most posterior relation of the lower jaw The most posterior relation of the lower jaw to the upper jaw from which lateral to the upper jaw from which lateral movements can be made at a given vertical movements can be made at a given vertical dimension. dimension. (BOUCHER) (BOUCHER)
- 4. 4 CENTRIC OCCLUSION CENTRIC OCCLUSION The occlusion of opposing teeth when the The occlusion of opposing teeth when the mandible is in centric relation. This may or mandible is in centric relation. This may or may not coincide with maximal intercuspal may not coincide with maximal intercuspal position. position. (GPT-7) (GPT-7)
- 5. 5 Terminal hinge axis Terminal hinge axis Terminal hinge axis is the most retruded hinge Terminal hinge axis is the most retruded hinge position. Terminal hinge position is significant position. Terminal hinge position is significant because this position is learnable, repeatable because this position is learnable, repeatable and recordable which coincides with the and recordable which coincides with the position of centric relation. Since the rotation position of centric relation. Since the rotation of condyles occurs when the mandible is in its of condyles occurs when the mandible is in its terminal retruded centric relation position, it terminal retruded centric relation position, it was known as terminal hinge axis. was known as terminal hinge axis. (GPT-7) (GPT-7)
- 7. 7 TMJ TMJ
- 8. 8 Muscle involvement in centric Muscle involvement in centric relation relation Centric relation is not a resting or postural position of Centric relation is not a resting or postural position of the mandible. the mandible. Contraction of muscles is necessary to move & fix the Contraction of muscles is necessary to move & fix the mandible in centric relation position. mandible in centric relation position. The anatomic attachments of the posterior & middle The anatomic attachments of the posterior & middle parts of the temporal & supra hyoid (geniohyoid & parts of the temporal & supra hyoid (geniohyoid & digastric) together with electromyographic studies digastric) together with electromyographic studies indicate that these muscles move & fix the mandible in indicate that these muscles move & fix the mandible in the centric relation the centric relation The temporal, masseter, and medial pterygoid muscles The temporal, masseter, and medial pterygoid muscles elevate the mandible to the centric relation position. elevate the mandible to the centric relation position.
- 10. When to Use Centric When to Use Centric Relation Relation When entire occlusion being restored When entire occlusion being restored No remaining posterior centric stops No remaining posterior centric stops When complete, fixed, or removable When complete, fixed, or removable partial dentures involve the entire partial dentures involve the entire occlusion occlusion
- 11. When to When to Not Not to Use Centric to Use Centric Relation Relation Stable occlusion Stable occlusion No pathology No pathology Posterior centric stops present Posterior centric stops present No valid reason to change No valid reason to change Use maximum intercuspation Use maximum intercuspation
- 12. 12 Relating centric relation to centric Relating centric relation to centric occlusion occlusion Centric relation is a bone to bone relation. Centric relation is a bone to bone relation. Centric occlusion is a relationship of upper & lower Centric occlusion is a relationship of upper & lower teeth to each other. teeth to each other. In complete denture, once centric relation is In complete denture, once centric relation is established centric occlusion can be built to coincide established centric occlusion can be built to coincide with it. with it. In natural tooth interferences in centric relation In natural tooth interferences in centric relation initiate impulses and responses that would direct the initiate impulses and responses that would direct the mandible away from the deflective contacts into mandible away from the deflective contacts into centric occlusion establishing a memory pattern. centric occlusion establishing a memory pattern.
- 13. 13 SIGNIFICANCE OF MAKING SIGNIFICANCE OF MAKING CENTRIC RELATION CENTRIC RELATION The maxillo-mandibular musculature is so The maxillo-mandibular musculature is so arranged that it is simple to move the mandible arranged that it is simple to move the mandible into centric relation. into centric relation. It serves as a reference relation which can be It serves as a reference relation which can be reproduced repeatedly hence can be used for reproduced repeatedly hence can be used for establishing an occlusion. establishing an occlusion. Stability of denture bases is jeopardized. Stability of denture bases is jeopardized. Stability of natural teeth is jeopardized when Stability of natural teeth is jeopardized when mandible is deflected away. mandible is deflected away.
- 14. 14 Patients cannot close their teeth into centric Patients cannot close their teeth into centric occlusion if it is off centered. occlusion if it is off centered. Errors can go undetected when centric relation is Errors can go undetected when centric relation is not used as a horizontal reference relation. not used as a horizontal reference relation. It is a repeatable, recordable position and a It is a repeatable, recordable position and a physiologically acceptable position for physiologically acceptable position for mastication & deglutition. mastication & deglutition.
- 15. 15 Proper adjustments of the condylar guidance can Proper adjustments of the condylar guidance can be done on the articulator for eccentric be done on the articulator for eccentric movements. movements. If centric relation is not recorded the angulation If centric relation is not recorded the angulation of condylar pathway will be incorrect. of condylar pathway will be incorrect. An accurate centric relation properly orients the An accurate centric relation properly orients the lower cast to the opening axis of the articulator lower cast to the opening axis of the articulator and orients the centric relation to the Hinge axis and orients the centric relation to the Hinge axis of the articulator. of the articulator.
- 16. 16 Complications in recording centric Complications in recording centric relation relation Centric relation has been defined as the most retruded Centric relation has been defined as the most retruded unstrained position of the condyles in the glenoid fossae unstrained position of the condyles in the glenoid fossae at given degree of mouth opening. Unstrained is not at given degree of mouth opening. Unstrained is not only in the anteroposterior direction but also in the only in the anteroposterior direction but also in the supero-inferior direction. supero-inferior direction. The structure of the TMJ is such that it can be displaced The structure of the TMJ is such that it can be displaced downward by uneven pressure between the jaws when downward by uneven pressure between the jaws when the records are made and yet the condyles can be still be the records are made and yet the condyles can be still be located in their most retruded position which doesn’t located in their most retruded position which doesn’t occur on the articulator leading to deflective occlusal occur on the articulator leading to deflective occlusal contacts. contacts.
- 17. 17 Centric relation is further complicated by the Centric relation is further complicated by the different degree of tissue resiliency. different degree of tissue resiliency. Hanau has referred to tissue resiliency as Hanau has referred to tissue resiliency as REALEFF (resiliency and like effect). REALEFF (resiliency and like effect). This resiliency is present both on the oral This resiliency is present both on the oral mucosa and the capsular ligament of the TMJ. mucosa and the capsular ligament of the TMJ. Thus undue pressure in securing centric relation Thus undue pressure in securing centric relation must be avoided to eliminate the possibility of must be avoided to eliminate the possibility of excessive displacement of the soft tissues. excessive displacement of the soft tissues.
- 18. 18 Factors that determine Centric Factors that determine Centric Relation Relation Horizontal movements of mandible have Horizontal movements of mandible have definite limits (Border movements) and a wide definite limits (Border movements) and a wide range of intra border movements. range of intra border movements. Health of the nerves. Health of the nerves. Muscles. Muscles. Ligaments. Ligaments. Temporomandibular joints. Temporomandibular joints. Capsular ligament Capsular ligament Border movements. Border movements.
- 19. 19 Methods available in aiding to Methods available in aiding to retrude the mandible retrude the mandible Central bearing point and plate supported by the recording bases. Central bearing point and plate supported by the recording bases. Instruct the patient by saying “ let your jaws relax, pull it back Instruct the patient by saying “ let your jaws relax, pull it back and close slowly and easily on your back teeth” and close slowly and easily on your back teeth” Instruct the patient by saying ‘ get the feeling of pushing your Instruct the patient by saying ‘ get the feeling of pushing your upper jaw out and close your back teeth together. upper jaw out and close your back teeth together. Instruct the patient by saying to protrude and retrude the Instruct the patient by saying to protrude and retrude the mandible repeatedly while the patient holds the fingers lightly mandible repeatedly while the patient holds the fingers lightly against the chin. (Boos - Stretch – relax exercise) against the chin. (Boos - Stretch – relax exercise) Tongue guidance Tongue guidance Tapping the occlusal rims or the back together repeatedly Tapping the occlusal rims or the back together repeatedly Tilting the patients head back while performing the above Tilting the patients head back while performing the above exercises. exercises. Palpate the temporal and masseter muscles to relax them Palpate the temporal and masseter muscles to relax them
- 20. 20 Methods of guiding the mandible to Methods of guiding the mandible to centric relation centric relation FINGER GUIDANCE FINGER GUIDANCE TONGUE GUIDANCE TONGUE GUIDANCE DEGLUTITION GUIDANCE DEGLUTITION GUIDANCE INHALATION METHOD INHALATION METHOD
- 23. 23 DEGLUTITION GUIDANCE DEGLUTITION GUIDANCE The patient is instructed to swallow a little The patient is instructed to swallow a little saliva before closure of the jaws is effected. saliva before closure of the jaws is effected. During the act of deglutition the mandible During the act of deglutition the mandible places itself in centric relation to the maxillae. places itself in centric relation to the maxillae. In this instance to, the patient is told to close In this instance to, the patient is told to close very gently because of the even greater danger very gently because of the even greater danger of obtaining a strained jaw relation resulting of obtaining a strained jaw relation resulting from a forceful closure. from a forceful closure.
- 24. 24 INHALATION METHOD INHALATION METHOD Instructing the patient to inhale as much air as Instructing the patient to inhale as much air as possible by mouth and exhale it through the possible by mouth and exhale it through the nasal apertures after the jaws have been nasal apertures after the jaws have been brought together gently. brought together gently. In this instance, if the patient is to exhale the In this instance, if the patient is to exhale the air through the nose exclusively while the jaws air through the nose exclusively while the jaws are closed and the lips are in contact, the are closed and the lips are in contact, the tendency is for the mandible to assume a tendency is for the mandible to assume a centric relation to the maxillae. centric relation to the maxillae.
- 25. 25 Materials used for securing the Materials used for securing the centric relation centric relation Plaster bite records. Plaster bite records. Softened wax. Softened wax. Zinc-oxide – Eugenol paste. Zinc-oxide – Eugenol paste. Silicone bite records. Silicone bite records. Acrylic resin. Acrylic resin.
- 26. 26 METHODS OF RECORDING METHODS OF RECORDING CENTRIC RELATION CENTRIC RELATION Centric relation functional graphical Inter occlusal check Intra oral Extra oral Needle house tech Patterson tech Heartwell
- 27. 27 Functional / Chew-in method Functional / Chew-in method
- 28. 28 Functional method / Needle house Functional method / Needle house method method Low fusing compound is used as the Low fusing compound is used as the mandibular occlusal rim. After the vertical mandibular occlusal rim. After the vertical dimension has been established the maxillary dimension has been established the maxillary occlusal rim is reduced and 4 needles are occlusal rim is reduced and 4 needles are embedded on the maxillary occlusal rim. embedded on the maxillary occlusal rim. Vertical relation is rechecked. The patient is Vertical relation is rechecked. The patient is asked to perform the mandibular movements. asked to perform the mandibular movements. Diamond shaped markings are inscribed on the Diamond shaped markings are inscribed on the mandibular occlusal rim. mandibular occlusal rim.
- 29. 29 NEEDLE HOUSE TRACING NEEDLE HOUSE TRACING
- 30. 30 Graphical method / Gothic arch Graphical method / Gothic arch tracing tracing INTRA-ORAL TRACING INTRA-ORAL TRACING EXTRA-ORAL TRACING EXTRA-ORAL TRACING This concept was first propounded by Hesse in This concept was first propounded by Hesse in 1897 and was popularized by Gysi (1910). 1897 and was popularized by Gysi (1910). All movements in the horizontal plane initiate All movements in the horizontal plane initiate from the apex of the tracing which is a from the apex of the tracing which is a reproducible reference point (CR). reproducible reference point (CR).
- 31. 31 To make a needle point tracing, one condyle To make a needle point tracing, one condyle moves forward and inward during a lateral moves forward and inward during a lateral movement, followed by a movement in the movement, followed by a movement in the opposite direction with rotation occurring opposite direction with rotation occurring around the opposite condyle. The movements around the opposite condyle. The movements are approximate rotation alternately around the are approximate rotation alternately around the two condyles. The movement cut lines two condyles. The movement cut lines extending to a point representing the centric extending to a point representing the centric relation (APEX OF TRACING). relation (APEX OF TRACING).
- 32. 32 Factors of importance Factors of importance Displacement of the record bases may result from Displacement of the record bases may result from pressure if the central points are off centre. pressure if the central points are off centre. If the central bearing device is not used, rims offer If the central bearing device is not used, rims offer resistance to horizontal movements. resistance to horizontal movements. Difficult to place in the presence of large tongue. Difficult to place in the presence of large tongue. Cannot be used in cases of TMJ disorder. Cannot be used in cases of TMJ disorder. Cannot be used in patients with poor inter ridge space. Cannot be used in patients with poor inter ridge space. Tracing not acceptable until a pointed apex is got. Tracing not acceptable until a pointed apex is got. Double tracing improper coordination of the Double tracing improper coordination of the movements. movements. Vertical dimension has to be maintained. Vertical dimension has to be maintained.
- 33. 33 Technique for graphic method Technique for graphic method Accurate, stable denture bases Accurate, stable denture bases Occlusal rims made of hard base plate wax Occlusal rims made of hard base plate wax Contouring of occlusal rims Contouring of occlusal rims Establish vertical dimension at rest Establish vertical dimension at rest Establish vertical dimension at occlusion Establish vertical dimension at occlusion Face bow transfer and articulation with tentative jaw Face bow transfer and articulation with tentative jaw relation relation Mount the central bearing device exactly on the centre Mount the central bearing device exactly on the centre of the ridge of the ridge Stylus attached to the maxillary rim Stylus attached to the maxillary rim Tracing plate attached to the mandibular rim Tracing plate attached to the mandibular rim
- 34. 34 Seat the patient with the head upright, in a comfortable Seat the patient with the head upright, in a comfortable position in the dental chair position in the dental chair Seat the record bases on the ridge Seat the record bases on the ridge No interference in the occlusal rims and the denture bases No interference in the occlusal rims and the denture bases Retract the stylus and conduct the training exercise for the Retract the stylus and conduct the training exercise for the mandibular movements mandibular movements Ney excursion guide can be used. Ney excursion guide can be used. The tracing plate is precipitated with chalk in denatured The tracing plate is precipitated with chalk in denatured alcohol alcohol Tracing is performed with the stylus touching the tracing plate Tracing is performed with the stylus touching the tracing plate Sharp apex should be formed indicative of the centric relation Sharp apex should be formed indicative of the centric relation Quick setting plaster is injected between the central bearing Quick setting plaster is injected between the central bearing devices to secure the centric relation record with the stylus at devices to secure the centric relation record with the stylus at the tip of the apex of the tracing the tip of the apex of the tracing
- 35. 35
- 36. 36 CENTRAL BEARING DEVICE CENTRAL BEARING DEVICE
- 37. 37 CENTRAL BEARING CENTRAL BEARING TRACING TRACING The pattern obtained on the The pattern obtained on the horizontal plate using with a horizontal plate using with a central bearing tracing device. central bearing tracing device. (GPT-7) (GPT-7) Synon: Synon: Arrow point Arrow point tracing. tracing. Needle point Needle point tracing. tracing. Stylus tracing. Stylus tracing.
- 38. 38 Types of tracing Types of tracing
- 39. 39 Intra oral tracing - Advantages Intra oral tracing - Advantages Tracing near to the condyle. Tracing near to the condyle. Mid point shift not marked because of stability Mid point shift not marked because of stability of the denture bases. of the denture bases.
- 40. 40 Disadvantages Disadvantages Cannot be observed during tracing. Cannot be observed during tracing. Occlusal rim preparation is tiresome. Occlusal rim preparation is tiresome. Dynamic method hence accuracy is doubtful. Dynamic method hence accuracy is doubtful. Displacement of the mucousa. Displacement of the mucousa. Lack of equalized pressure on the occlusal rim. Lack of equalized pressure on the occlusal rim. Because of the rigidity of the occlusal blocks Because of the rigidity of the occlusal blocks difficult to perform the mandibular movements. difficult to perform the mandibular movements.
- 42. 42 FRAHM’S METHOD OF FRAHM’S METHOD OF TRACING TRACING Messerman tracing device at the centre Stylii mounted on the maxillary occlusal rim
- 44. 44 EXTRA-ORAL TRACING EXTRA-ORAL TRACING Larger tracing when compared to the intra oral Larger tracing when compared to the intra oral tracing. tracing. Patient coordination is good because the styli Patient coordination is good because the styli can be observed both by the patient and the can be observed both by the patient and the operator. operator.
- 46. 46 HIGHT TRACER {1931} HIGHT TRACER {1931}
- 47. 47
- 48. 48 Disadvantages of graphical method Disadvantages of graphical method Cautious use in Class II & III cases. Cautious use in Class II & III cases. Presence of flat ridge. Presence of flat ridge. Presence of flabby ridge. Presence of flabby ridge.
- 49. 49 Tactile or inter occlusal check Tactile or inter occlusal check record method record method Tentative records using occlusion rims Tentative records using occlusion rims attached to record bases. attached to record bases. Inter occlusal check records with the teeth Inter occlusal check records with the teeth arranged for try in. arranged for try in. Determined by the proprioception of the Determined by the proprioception of the patient. patient.
- 50. 50 The technique described in the section on The technique described in the section on complete dentures uses softened wax over the complete dentures uses softened wax over the occlusal and incisal surfaces of the mandibular occlusal and incisal surfaces of the mandibular teeth. In this manner the maxillary teeth teeth. In this manner the maxillary teeth strike .into. wax instead of wax striking wax, as strike .into. wax instead of wax striking wax, as in the other methods. in the other methods. The advantage of this method lies in the fact that The advantage of this method lies in the fact that comparatively small surfaces are striking instead comparatively small surfaces are striking instead of fiat wax surfaces. Compound, instead of wax of fiat wax surfaces. Compound, instead of wax has also been used aver the teeth far the has also been used aver the teeth far the interocclusal check bite. interocclusal check bite.
- 51. 51
- 52. 52