Articulators in Prosthodontics

Brief description on Articulators for UG students.

1. ARTICULATION CREATED BY: Dr. Joel Koshy Joseph MDS

2. Articulator: A mechanical device which represents the temporomandibular joints and the jaw members to which maxillary and mandibular casts may be attached to simulate jaw movements . (GPT 8)

3. Articulation The static and dynamic contact relationship between the occlusal surfaces of the teeth during function.

4. Occlusion: The static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogs. (GPT 8)

5. Functions of Articulators: Hold maxillary and mandibular cast in a planned position. Simulate TMJ and maxilla and mandibular movements (Similar to patient). To arrange artificial teeth. Mounted models can be used for Diagnostic, treatment planning and patient presentation.

6. Advantages of Articulators: Provide a better view of the patient’s occlusion, especially the lingual side. Refinement of complete denture occlusion is extremely difficult intraorally, because of movement of denture base and resiliency of the supporting tissues. Patient cooperation is not a factor, chairside and appointment time for the patient is reduced.

7. Limitation of articulators: Like all instruments, articulators are also subjected to errors in tooling and errors resulting from metal fatigue and wear. No articulator can exactly duplicate the condylar movements of an individuals It can not compensate for any errors in jaw relation records.

8. Classification of Articulations Based on adjustability Non Adjustable Semi Adjustable Full Adjustable

9. Non Adjustable articulator: An articulator that does not allow adjustment to replicate mandibular movements. Eg. Class I and II articulators, Slab Articulators Hinge articulators. Mean Value articulator

10. Semi Adjustable: An articulator that allows adjustment to replicate average mandibular movements – also called Class III articulator.

11. Fully Adjustable Articulators: An articulator that allows replication of three dimensional movement of recorded mandibular motions. – Also called Class IV articulators

12. Based on position of condylar element: Arcon : 2. Non - Arcon Ar ticulator Con dyle

13. Based on instrument function: Given by University of Michigan in 1972: Aka: Michigan’s classification Class I Simple holding instrument capable of accepting a single static registration vertical motion is possible. ( Open and Close movement) Eg. Slab Articulators Hinge Articulators By J. B Gariot in 1805

14. Class II: An instrument that permits horizontal as well as vertical motion but does not orient the motion to temporomandibular joints. Horizontal and vertical movements can be done but can not be adjusted. Average Values and theories are used. Class IIA Eccentric motions permitted are based on average values . Eg Grittman articulator, Gysi articulator, Mean Value articulator

15. Class IIB Eccentric motions permitted are based on arbitrary theories of motion . Spherical Theory Each cusp and incisal edge touches or conforms to a segment of the surface of a sphere 8 inch in diameter with its centre in the region of glabella. Eg. Maxillomandibular instrument

16. Class IIB Eccentric motions permitted are based on arbitrary theories of motion . Bonwill theory It states that distance between the condyles and each condyle and incisal point is 4 inch forming a equilateral triangle. Eg. Bonwill articulator

17. Class IIB Eccentric motions permitted are based on arbitrary theories of motion . Conical theory It states that the lower teeth move over the surfaces of the upper teeth as over the surface of a cone, generating an angle of 45 degrees with the central axis of the cone tipped 45 degrees to the occlusal plane. The teeth of the maxillary denture would conform to a segment of the inner surface of an 8-inch cone. Eg. Hall articulator

18. Class IIC Eccentric motions permitted are based on engraved records obtained from the patient. Eg. House articulator by M. M House 1927. Used records obtained form Centric record by the Needle House method.

19. Class III An instrument that stimulates condylar pathways by using averages or mechanical equivalents for all or part of the motion; these instruments allow for orientation of the casts relative to the joints and may be acron or non- acron instruments. Allow eccentric (protrusive and lateral). They accept facebow transfer. Eg. Semi adjustable articulators.

20. Class IIIA Instruments accept only protrusive record to adjust the protrusive condylar inclinations. Lateral condylar inclinations is determined using Hanau Formulae: L = H/8 + 12 Eg. : Hanau Model H and H2 Bregstrom .

21. Class IIIB Instruments accept both protrusive record and lateral records to record condylar inclinations. Eg .:Hanau Kinoscope , Ney articulator, Panadent

22. Class IV An instrument that will accept three-dimensional dynamic registrations; these instruments allow for orientation of the casts to the temporomandibular joints and simulation of mandibular movements. Fully adjustable articulators They accept facebow transfer All articulators are of Arcon type with adjustable interco - ndylar distance.

23. Class IVA The condylar pathways are engraved by the patient (Stereographic recordings) and the instrument will accept these three-dimensional dynamic engravings. Eg .:TMJ articulator by Kenneth Swanson 1965. Registration is obtained by records generated by studs in a cold cure resin (Similar to the Needle House technique). Also known as Stereographic recordings This recording is placed on the articulator and the condylar fossa is moulded to produce an accurate replica of the patient’s TMJ

24. Class IVB The condylar pathways are obtained using three-dimensional tracings (Pantographic recordings) and the instruments will accept these three-dimensional dynamic tracings. Eg. : Denar D5A There tracings are also available in electronic forms as well.

25. Mean Value Articulator Class II A (Michigan Classification) Non-Adjustable Articulator (Based on Adjustability) Non- Arcon Articulator (Based on Condylar position) Three Point Articulator Fixed horizontal axis Fixed incisal table angulation Fixed condylar path

26. Components: Upper Member Condylar shaft and slot with spring Lower Member Support rod and Orientation rod Vertical support arms Incisal adjustment screw Incisal Rod Incisal pin Incisal Table

27. Functions: Upper member: Holds the Maxillary cast Condylar shaft and slot with spring: this represents the condyle and glenoid fossa, angulated to 30 degree and spring to push the condylar rod into position. Lower member: holds the Mandibular cast

28. 4. Support rod: for stability for the articulator Orientation Rod: for orientation of the occlusal plane

29. Specifications: Distance between the incisal and condylar guidance: Average values Inter-condylar distance: 110mm Condylar Inclinations: 30 degree Incisal table angulation: 5 degree

30. Incisal Rod: Maintains vertical height and separation between the upper and lower members and act as a vertical anterior stop. Incisal pin: orientation of maxillary anterior teeth Incisal Table: for anterior guidance Incisal Pin adjustment screw: to change the position of incisal rod.

31. Procedure for articulations

32. Video on Mounting Cast on a mean valued articulator

33. Video on transfer of Facebow to Hanau wide Vue II