Functionally generated path occlusion final

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1. 1 FUNCTIONALLY GENERATED PATH OF OCCLUSION Presented by – Dr Mujtaba Ashraf MDS -III

2. 2 1. INTRODUCTION 2. FUNCTIONALLY GENERATED PATH OCCLUSION IN FPD 3. FUNCTIONALLY GENERATED PATH OCCLUSION IN COMPLETE DENTUERE 4. FUNCTIONALLY GENERATED PATH OCCLUSION IN SINGLE COMPLETE DENTURE 5. FUNCTIONALLY GENERATED PATH OCCLUSION IN REMOVABLE PARTIAL DENTURE 6. ADVANTAGES. DISADVANTAGES. CONCLUSION. CONTENTS:

3. 3 OCCLUSION: It is defined as- 1. The act or process of closure or being closed or shut off, 2. The static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues. ( GPT-8) Dental articulation: Dental articulation is defined as the static and dynamic contact relationship between the occlusal surfaces of the teeth during function.

4. 4 Early concepts were based on those of: Bonwill (1858) Balkwill (1866) Von Spee(1890) Then came the age of occlusal theories and occlusal articulators which include: 1.Monsons spherical theory(1916) 2.Halls conical theory(1918). 3. Meyers functionally generated path technique(1940) CONCEPTS OF OCCLUSION:

5. 5 NATURAL DENTITION OCCLUSION . Mutually protected occlusion or canine protected occlusion . (D’AMICO) 2. Group function occlusion . (SCHULER)

6. INTRODUCTION: To properly evaluate a patients occlusion it is mandatory that diagnostic casts be placed /articulated in the same relation as in the patients mouth. The method of reproducing centric and eccentric relations between the maxilla and the mandible for the fixed or removable reconstruction can be divided into two groups. Methods using articulators. Methods using functionally generated Path technique (FGP) 6

7. Dentistry has recognized functional path articulations as a viable way of developing occlusion for more then 60 years . Meyers first described this method in 1933, as a means of obtaining the “Functional Occlusal path” for bridges fabricated by a direct/indirect technique and for dentures. 7

8. Functionally generated path relies on recording in a simple, yet precise manner the pathways traveled by the cusps in the border movements of the mandible. Wax is adapted over the occlusal surface of the prepared tooth. The patient occludes the teeth in the intercuspal position and moves the mandible through all excursions .By this process the tips of the opposing cusps acts a recording styli that carve , in three dimensions in wax, a record of the border movements in all mandibular positions. Stone is brushed and poured into the wax record in the mouth to produce functional core. The stone core is then used in the fabrication of posterior tooth restoration. 8

9. The technique was adapted for use in COMPLETE OCCLUSAL REHABHILITATION by PANKEY AND MANN. Here based on the Spherical theory of occlusion, calipers are used to locate a center of rotation. From this center , the mandibular cast is reduced to bring the occlusal surface of the mandibular teeth in to harmony with the surface of the theoretical sphere, with a uniform amount of reduction (1.6 mm). 9

10. After the mandibular teeth in the mouth have been reduced and subsequently restored to an ideal plane, an functionally generated recording of the mandibular cusp path is made. It is used to produce a stone functional core or index against which the maxillary restoration are fabricated. 10

11. Armamentarium for the FGP Petrolatum Cotton-tipped applicator Cavity varnish Tacky wax PKT waxing instruments Bunsen burner Die fabricant Mounting stone Spatula Plaster bowl Sable brush Functional index try Laboratory knife with no 25 blade Custom impression tray Impression material (base and accelerator) Mixing pad Syringe Bite registration frame Bite registration paste Die stone Di- lok tray Twin stage occluder 11

12. PROCEDURE FOR THE FABRICATION OF FUNCTIONAL CORE FOR FIXED PROSTHODONTICS : ( Functional index or Counter die) The working side tooth contacts is evaluated to determine whether they form a mutually protected occlusion (canine guide occlusion) or unilaterally balanced (group function) occlusion, which is essential in determining the type of occlusal scheme to be produced in the final restoration. The technique to be described here is primarily for use in fabricating restorations in maxillary teeth. 12

13. The preparation for the cast restoration is started by doing the occlusal reduction. Before preceding on to the axial reduction the functional tracings are made. The larger occlusal table that is present before axial reduction will afford greater stability to the wax tracing. 13

14. Petrolatum is applied with a cotton tipped applicator to the occlusal surface of the opposing quadrant and cavity varnish is applied to the occlusal surface of the prepared tooth to help the wax to adhere more securely. Piece of wax is cut in a square slightly larger than the occlusal surface of the teeth being restored. The square of wax is attached to a PKT No.2 waxing instrument and soften it over bunsen burner flame. While the varnish on the occlusal surface is still tacky and the wax is soft, tack the wax is to the tooth being restored. 14

15. The patient is guided into a retruded closure in centric relation. Then patient is guided through all excursions, moving first into the working side . From working excursion, the patient is guided back to centric relation and then into a nonworking movement. 15

16. Have the patient return again to centric relation and then to protrusive. The patient should be guided through combination movements as well : working protrusive and non working protrusive . Finally the patient should just “mill around” to ensure adequate clearance For the opposing cusps in function. 16

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20. TO OBTAIN THE FUNCTIONAL CORE. A tray of some sort should be used to hold the stone in place in the mouth to make the functional core. Tongue blades and denture tooth cards can be employed for this purpose, but a functional index tray offers definite advantages. It is curved to fit the arch. Has undercuts to hold the stone in position. The tray extends to the anterior teeth for added stability. The unneeded portion can be broken and discarded. 20

21. The wax is painted with a die lubricant to reduce surface tension and ensured a smooth, complete functional core. A creamy mix of mounting stone is painted on the surface of the functional wax tracing with a sable brush The functional index tray is loaded with a layer of mounting stone 6.0 mm(0.25 inch) thick. Position it on the occlusal surface of the quadrant so that it covers at least one tooth on each side of the prepared tooth. 21

22. When the stone has set, it is removed carefully and examined carefully for free of bubbles or voids . This stone replica of the movement of the cusp tips is called the functional core. It is also referred to as the functional index or counter die. The surface of the core is trimmed with a sharp laboratory knife. The rest of the tooth preparation is completed and an impression of the quadrant containing the prepared tooth is made using a custom acrylic tray made previously. 22

23. It is possible to fabricate a restoration using only the functional core for an opposing model. However it is very helpful to have an anatomic cast against which you can occlude the wax pattern. For this an occlusal registration is made at the intercuspal position using bite registration paste in a bite registration frame. 23

24. Attach the quadrant tray with the mounting stone to the lower member of an articulator with two upper members. Trim the base of the cast containing the prepared tooth also the cast will fit into the die tray. The finish line of the the tooth preparation should be about 0.25 inch above the edge of the die tray 24

25. TO ATTACH THE FUNCTIONAL CORE IN TWIN STAGE OCCLUDER. Dental stone is poured into the imprints of the mandibular teeth in the disinfected Zinc oxide eugenol bite registration and base is created approximately 0.5 inch thick on the occlusal registration. Undercuts are left on the base for the later attachment to the articulator. 25

26. Now the functional core is placed on the cast in the die tray and confirmed that it still fits accurately. It is attached to the cast with the sticky wax. The incisal pin of the twin stage occluder is adjusted. The functional core is now mounted on the upper right member of the articulator 26

27. Stone core mounting 27

28. TO ATTACH THE ANATOMIC CORE IN TWIN STAGE OCCLUDER. On the maxillary side of the zinc oxide eugenol bite registration small fins are trimmed that fit into the occlusal embrasure between the teeth. Carefully the bite registration is fitted on the cast of the di-lok tray. It is ensured to seat properly without any rocking or wobbling and after adjusting the incisal guide pin the anatomic cast is mounted to the left upper member with mounting stone. 28

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30. Sawing of the die is done. Ditching Gingival finish line marked in red pencil The die and the sections of the quadrant cast is reassembled The mounting is ready for wax pattern fabrication. 30

31. The verticulator is another instrument that is made for use with the functionally generated path technique. It is extremely rigid and provides a precise alignment of cast and functional core. It also utilizes a second upper member (removable not hinged) that can be employed with the anatomic cast. A plane line hinge articulator can also be used for this purpose, but it does not permit the use of an anatomic cast. 31

32. Wax pattern fabrication The die is removed from the di-lok tray and the preparation is lubricated thoroughly with die lubricant. Wax is flowed over the surface of the preparation on the die using quick, overlapping strokes of a hot no. 7 wax spatula. Initially the occlusal portion of the wax pattern should be waxed against the anatomic cast to aid in visualizing cusp location more effectively. The wax added technique is used to position the cones of the cusp tips. Marginal ridges and cusp ridges complete the outline of the occlusal table, and then they are blended into the axial contours. Triangular ridges are placed next. 32

33. Axial contours and proximal contacts are checked before preceding to the occlusal surface. The wax added technique is used to form the occlusal morphology. 33

34. Now the occlusal portion of the wax pattern can be completed by waxing against the functional core. 34

35. White liquid shoe polish is painted on the functional core. The articulator is closed so that the functional core is brought in contact with the occlusal surface of the wax pattern. The shoe polish will leave white marks on the occlusal surface of the wax pattern corresponding to the contacts in function. Any areas in white that are not part of the of the desired centric or excursive contact pattern are carved off according to the restoration which would go to mutually protected or group function occlusion. 35

36. If the restoration should be in mutually protected relationship there should be no contact on the lingual incline of the buccal cusp other than the centric contacts. If on the other hand the restoration to be fabricated in group function, the lingual incline of the buccal cusp should maintain continuous contact with the functional core. In no case should the non working inclines have any contact with the functional core. 36

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38. FUNCTIONALLY GENERATED PATHWAY FOR THE COMPLETE DENTURES. The functionally generated path technique has been successfully adopted in the construction of complete denture prosthodontics. The object is to obtain the individual curves of a patient. Briefly this is attained by inserting record blocs with abrasive rims and allowing the patient to grind them together untill they are in balanced articulation. This type of record is very suitable for patients with marked translatory movements of the mandible. 38

39. OCCLUSAL RIMS: Generally the occlusal rims for complete denture are made up of Wax Impression Compound Mixture of plaster with an abrasive such as pumice and sand. 39

40. RECORD BASES AND OCCLUSAL RIMS Stability of the record bases is essential for accuracy since there will be a considerable lateral and protrusive drag to friction, during the process of grinding Ideally the denture bases is made up of heat cure acrylic resin. The occlusal rims are made up of plaster and an abrasive, such as coarse corborandum, pumice or sand The buccolingual width should be about 1 cm, which is necessary to define the lateral and antero-posterior curves and for strength. 40

41. RECORDING THE FUNCTIONAL PATH ` Tentative jaw relations are first recorded with wax blocks and mounted in semi adjustable articulator. The blocks with abrasive rims are then constructed with the vertical height opened a few millimeters to allow for the closure which will result from the grinding. One method of constructing the rims is to make them of composition within 5 mm of the estimated correct height, to groove the composition for retention and then build up the plaster pumice for a further 4-5 mm. 41

42. The record bases are placed in the oral cavity. The patient is instructed to grind the blocks together with both lateral and protrusive movements but only to use the minimum pressure necessary to keep the blocks in contact. The grinding is continued until the correct vertical dimension is obtained. 42

43. The occlusal surfaces of the rims now show correct balancing curves for the patient. The curves are reproduced in the denture by mounting the casts on a plane line articulator and setting the lower zero cusp teeth to occlude with the upper block and then the upper teeth to occlude with the lower ones. The form of cusp will vary with the height of the occlusal surfaces and also with the original shape of the plaster pumice blocks whether flat or curved. 43

44. FGP OCCLUSION FOR SINGLE COMPLETE DENTURE: Whenever the irregularity of the occlusal table of the natural teeth is only mild it is best treated by a functionally generated path technique. In such a case acrylic posterior teeth is used and the occlusion is built on the articulator as for as possible. Now mesio-distal channels are cut out and the upper denture teeth are reduced out of contact with the teeth on the lower cast. The channels are filled with impression compound and centric stops are made. The remainder of the denture teeth are built with the hard wax on the articulator. 44

45. The denture is placed in the patients mouth and the patient is instructed to make movements towards working, nonworking and protrusive excursions to shape the wax to these eccentric contacts. In the laboratory occlusal registers are poured.The hard wax and compound is removed and is replaced with the casting wax The casting wax is sprued and casted in gold alloy. The castings are polished and then attached to the denture with EBA (Orthoethoxybenzoic acid) cement to obtain gold occlusal denture teeth 45

46. FUNCTIONALLY GENERATED PATH TECHNIQUE FOR RPD: The theory on which the FGPT is based is that “the pathways each tooth opposed to the edentulous space makes throughout all functional movements of the mandible are recorded, the artificial tooth may be positioned and formed so that it will remain in harmonious contact with its antagonist at all times. 46

47. The pathways are created by the patient in a wax occlusal rim. The patient performs all functional excursions while the opposing teeth contact the surface of the occlusal rim. The recording produced is actually a negative record of the movement of each opposing tooth as the mandible executes the functional movements. 47

48. ADVANTAGES: FGPT eliminates the need for adjusting articulator with interocclusal records or a tracing device The excursive movements produced in the mouth are more accurate than those in an articulator. It eliminates the need of face bow transfer. Is simple and can produce precise excellent results. 48

49. DISADVANTAGES: The occlusion in one of the arches must be complete before functional generated path can be developed. This cannot be effectively utilized for CD opposing RPD. The movement of distal extension base carrying hard inlay wax occlusal rim is usual. Verification of record in mouth is difficult. 49

50. CONCLUSION: The method of interocclusal registration using the articulators is time consuming, expensive and technique sensitive. Whereas in the FGP technique dynamic and static relations are reproduced directly in the mouth to capture the pathways traveled by the opposing cusps in mandibular function. In this situation the articulator is reduced to a role of a simple hinge. It is a relatively easy technique to learn. The technique does have the advantage of permitting simple, inexpensive instrumentation for restoration of teeth. I demands a minimum of chair time, especially during the try in and cementation phase. 50

51. REFERENCES : Okeson:Management of temperomandibular disorders and occlusion Ed 3 St Louis 1993, Mosby Bernard G.N. Smith: Planning and making crown and bridges. Davis Hinderson: Mc crackens removable partial prosthodontics. Dawson P.E: Evaluation, diagnosis and treatment of occlusal problems. Dykema P.E. Johnston’s modern practice in fixed prosthodontics. Earnst L. Miller: Removable partial prosthodontics. Glossary of Prosthodontic terms. JPD Dec 1984. Hamish Thomson: occlusion. Herbert T. Shillingburg: Fundamentals of fixed prosthodontics Hobo Sumiya: Osseeointegration and occlusal rehabilitation. Ramford S and Ash M: occlusion. Robert P Renner: Removable partial dentures Stephen.R. Rosensteil: Contemporary fixed prosthodontics William F.P. Malone: Tylman’s Theory and practice of fixed prosthodintics. BDJ Series of articles on occlusion, 2000 51