Interocclusal records and mounting of casts on articulator/ online orthodontic courses


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Interocclusal records and mounting of casts on articulator/ online orthodontic courses

  1. 1. Interocclusal records andInterocclusal records and mounting of casts on articulatormounting of casts on articulator 1 INDIAN DENTAL ACADEMY Leader in continuing dental education
  2. 2. Contents  Introduction  Techniques  Types  Materials  Mounting of casts on articulators  Conclusion  References
  3. 3. Introduction  The tactile or inter occlusal check record is referred to as physiological method.The kinesthetic sense or muscle sense helps to direct movements of parts of body through space.  It is one of the methods of recording centric relation . It is particularly indicated in situations of abnormally related jaws , supporting tissues that are excessively displaceable , large tongues , & uncontrollable or abnormal mandibular movements. It is also used to check occlusion in existing dentures & in trial dentures .
  4. 4. Types of inter occlusal records Centric inter occlusal records Eccentric inter occlusal records lateral inter occlusal records protrusive inter occlusal records
  5. 5. Definitions  Inter occlusal record : registration of the positional relationship of the opposing teeth or arches  A record of the positional relationship of the teeth or jaws to each other.  Centric inter occlusal record-a record of centric jaw position  Eccentric inter occlusal record – a record of jaw position other than centric  Lateral –record of lateral eccentric jaw position  Protrusive – record of protruded eccentric jaw position .
  6. 6. Factors that influence inter occlusal records  Amount and equalization of pressure , which depends on uniform consistency of recording material .  Comfort of patient ,which depends on stability & compatibility of record bases. Artificial teeth are more compatible to mandibular movements than occlusion rims.  An inter occlusal record with multiple points of references made by styli or cusp tips is more satisfactory than with occluding surfaces of wax or non cusp form teeth.
  7. 7. Techniques  Active techniques  Passive techniques
  8. 8. Methods of assisting the patient to retrude the mandible 1)instructing the patient to:  let your jaw relax ,pull it back and close slowly and easily on your back teeth  get the feeling of pushing your upper jaw out and close your back teeth together
  9. 9.  Protrude and retrude the mandible repeatedly as the patient holds the fingers lightly against the chin  Turn the tongue backwards towards the posterior border of the upper denture  Tap the opcclusal rims or the back teeth repeatedly  Tilting the head back while all the exercise is carried out  Palpating the temporal and the masseter muscles to relax them
  10. 10. Clinically accepted methods  One hand chin point guidance technique  Dawson’s technique  Unguided technique  Tongue to palate technique
  11. 11.  Dawson’s technique
  12. 12.  One hand chin point guidance technique
  13. 13. Unguided technique  Lucia jig  leaf gauge  Central bearing point  Cotton roll
  14. 14.
  15. 15.
  16. 16.
  17. 17. Tongue to palate technique
  18. 18. Characteristics of ideal registration material  Limited resistance before setting to avoid displacing teeth or mandible during closure.  Rigid after setting  Minimum dimensional change  Accurate record of incisal & occlusal surfaces  Easy to manipulate  No adverse effect on tissue  Records should be verifiable
  19. 19. Materials  Impression plaster  zinc oxide eugenol  waxes  elastomers  acrylic resins  Impression compound
  20. 20. Impression plaster (soluble plaster)  Type 1 modified with addition of accelerators to decrease setting time & setting expansion  Records are accurate , rigid after setting , do not distort with extended storage ,  Difficult to handle , record is brittle .
  21. 21. Bite registration waxes  Ease of manipulation ,  Inaccurate ,unstable ,inconsistent , may interfere with active & passive movements
  22. 22.
  23. 23. Zinc oxide eugenol paste  Fluidity before setting – is a critical factor because it ensures minimal interferences with mandibular closure during recording .  Adhesion to carriers  Rigid and inelastic after setting  Accuracy in recording occlusal and incisal surfaces  High degree of reproducibility
  24. 24.  Brittle(vital portion may be lost by breakage)  Sticks to tissues  Unless trimmed ,flash around the teeth may prevent accurate seating of casts
  25. 25. Silicone elastomers Addition and condensation silicones  Good accuracy.stable after setting,minimum resistance to closure Resistance to compression of set material which contributes to difficulty of seating of plaster casts
  26. 26. Polyether material  Accurate,stable to store,good fluidity,and minimum resistance to closure . Self curing acrylic resins  Good fluidity , but brittle , generates heat while setting , distortion & very hard on dies.
  27. 27. Impression compound type I uneven softening of material,distortion and inability to reproduce details accurately.
  28. 28.  Three general classes of records are used to transfer maxillo mandibular relation ship from patient to articulator  Inter occlusal records  Graphic records  Hinge axis records
  29. 29. Inter occlusal record adjustment  The mechanical features that determine whether an articulator can be adjusted to accommodate inter occlusal records include  Individually adjustable horizontal condylar guidance's  Variable controls for bennet shift  Variable inter condylar distances  Split axis condylar guidance controls  Adjustable incisal guidance control
  30. 30. Requirements of centric relation record  At open vertical dimension a face bow is indicated to orient maxilla to upper member of articulator  The inter occlusal registration material must be passive so that it does not interfere with clinical positioning of mandible  Centric relation registration must be repeatable and recordable
  31. 31.  Patient must be able to make eccentric mandibular movements from centric relation registration  Patient can voluntarily and reflexly return to this position  The record should be verifiable
  32. 32. Technique for inter occlusal record is divided into 2 steps  Tentative record using occlusion rims attached to accurate stable record bases  Inter occlusal check record with teeth arranged for try in
  33. 33. Technique  Seat the patient comfortably with head upright  Contour the maxillary rim ,lip line,occlusal plane and place notch to aid in seating records (trial denture when used the record material is sealed to lower posterior teeth)  Establish the vertical dimension of jaw separation with mandible at rest .
  34. 34.  Reduce the mandibular occlusal rim to allow inter occlusal distance  Make face bow record  Using interocclusal record material make tentative centric relation record
  35. 35.  Adjust condylar elements and secure them against centric stops  Mount the maxillary casts using face bow record  Secure the centric relation record and position the mandibular cast  Attach the cast to articulator with plaster
  36. 36. Eccentric interocclusal record – The purpose is to adjust horizontal & lateral condylar inclinations so that articulator jaw members perform eccentric jaw movements equivalent to the relative movements of the mandible – These adjustments provide condylar elements to travel to & from centric & eccentric position & make it possible to arrange teeth in balanced articulation
  37. 37. Protrusive relation record Seat the patient in comfortable upright position & rehearse the patient to protrusive bite Instruct the patient to protrude the lower jaw for approx 5-6 mm from centric observe the midline. Reinsert the trail denture and instruct the patient to protrude the jaw and close until the upper teeth contact the record material Allow the interocclusal record material to set . . Set the condylar post of articulator on 0 degree on the lateral calibrations
  38. 38.  Release the horizontal condylar adjustments by freeing the lock nuts .raise the incisal guide pin one half from incisal guide table.  Place the maxillary and mandibular trial dentures in their respective mounting casts in their articulator, carefully relate the maxillary teeth to interocclusal protrusive records  examine condylar elements to see protrusion is 5- 6 mm.  Using horizontal condylar lock nuts as handles manipulate one side and then another until all the teeth are accurately seated in record.  Secure the horizontal condylar adjustment locknuts with finger pressure
  39. 39. Lateral interocclusal records  When an articulator accurately adjusts to lateral maxillo mandibular records the additional points of reference are valuable  The more accurate points of references supplied in adjusting the articulator the more harmony will exist between mandibular movements and cusp inclines  The record is made in the same manner as the protrusive record. Two records are required one of right lateral and one of left lateral.  The articulator is adjusted as each record is made
  40. 40.  Although the mechanics of making the lateral jaw relations records appears simple it is recognized that in complete denture construction the procedure is difficult and many inaccuracies occur  Hanau held the opinion that the setting of lateral inclinations by an an anatomic record offers no particular advantages and the requirements can be determined on the finished case in the mouth by the records , observations and interpretation of symptoms on ridges.
  41. 41. Hanau’s formula for lateral inclination L = H/8 +12  L = Lateral condyle inclination in degrees  H = horizontal condyle inclination in degrees as established by the protrusive relation record
  42. 42. Review of literature Fattore et al (1984 JPD) studied accuracy of waxes ,zinc oxide eugenol & polyether and found that  Polyether recording material was the most accurate, with out carrier.  Polyether and zinc oxide eugenol paste were second most accurate with carrier .  Recording waxes ware consistently unreliable.  Distortion occurs more frequently in a vertical direction , followed by an anterior posterior direction.
  43. 43. Millestien (1985 JPD)studied accuracy of laminated wax interocclusal record (aluminum foil laminated between layer of wax )combined with use of dental plaster to mount casts and concluded that  Plaster which is most commonly used to mount casts expands and then contracts to 0.30%.  Wax was inaccurate material even if mounting was precise .
  44. 44. Michael urstein et al (1991JPD)studied 3 recording materials wax , plaster , and resin in maximum intercuspation position (IC) and retruded contact position (RCP) and concluded  Where a complete or nearly complete dentition is present and occlusion is stable hand articulation is most accurate method.  Plaster is more accurate material in recording IC and RCP ,than either wax or resin.  Wax record is slightly more accurate than resin at IC position and RCP.
  45. 45. Vergos .v.k et al(Int.JP. 2003) studied 4 inter occlusal record materials  polyether, polyvinyl siloxane,acrylic,wax, to record and maintain vertical relation.  Their results showed least dimensional change with poly vinyl siloxane followed by poly ether and wax showed highest dimensional change.  which ever material used for recording, 0.5mm vertical discrepancies occurred when records were transferred on casts which were clinically significant.
  46. 46. Conclusion The accuracy of inter occlusal records is single most important factor in complete denture construction. Articulators are not used to their full capabilities,its functions should be within the understanding of the operator. It can perform no better than the accuracy of the inter occlusal record used.
  47. 47. BIBLIOGRAPHY  Prosthodontic treatment for edentulousProsthodontic treatment for edentulous patient-(8patient-(8th,th, 1111thth , 12, 12thth ,),) BoucherBoucher  Syllabus of Complete Denture-Syllabus of Complete Denture- HartwellHartwell  Essentials of complete denture-Essentials of complete denture- WinklerWinkler  Complete Denture Prosthodontics John J SharryJohn J Sharry
  48. 48.  Evaluation,diagnosis,and Treatment of Occlusal Problems - Peter E Dawson  Management of temperomandibular disorders and occlusion 4th edition - Jeffery P Okeson  The Glossary of Prosthodontic Terms 7th Edition - The Academy of Prosthodontics
  49. 49. 49 For more details please visit