The Dental Articulator “The articulator: a tool, not the answer” Jeffrey P. Okeson, D.M.D.

Credits Management of Temporomandibular Disorders and Occlusion. Okeson Fundamentals of Fixed Prosthodontics. Shillingburg, et al. Contemporary Fixed Prosthodontics. Rosenstiel, et al. Whip Mix Corporation

The Dental Articulator What is it? Why use it? What are the different types? What are their advantages/disadvantages? How do we decide which one to use?

What is it? A mechanical device that simulates mandibular movements. Articulators can simulate the movement of condyles in their fossae.

Why use it? Handheld casts provide information concerning the alignment of arches & relationship of teeth, but do not permit analysis of functional relationships. Invaluable aid in: Diagnosis Treatment Planning Treatment

Classification Arcon vs. Nonarcon Arcon: condylar spheres attached to the lower component; mechanical fossae to the upper. Nonarcon: glenoid fossae on the lower component; condylar elements on the upper.

Arcon vs. Nonarcon Arcon Nonarcon Constant condylar inclinations Easily disassembled Nonarcon Variable condylar inclinations during opening Connected components

Classification, cont. How closely can it reproduce mandibular border movements? Nonadjustable Semi-adjustable Fully adjustable

Nonadjustable Articulators

Nonadjustable Articulators Simple Eccentric movements are often possible, but inaccurate.

Nonadjustable Articulators Only the maximal intercuspal position (ICP) is repeatable and accurate. Opening/closing pathways are inaccurate

Semi-adjustable Articulators

Whip Mix 4641

Semiadjustable Articulators Closely approximates the distance between the axis of rotation and the teeth Arcing errors will be minimal

Nonadjustable vs. Semiadjustable

Semiadjustable Articulators Limitations The TMJ is mechanically simplified It does not produce some condylar movements.

Fully Adjustable Articulators

Fully Adjustable Articulators Advantage (1) Highly accurate in: All border movements Condylar inclinations Intercondylar distance Disadvantages Expensive Time-consuming Requires a high degree of skill

What & When

Articulator Selection from Contemporary Fixed Prosthodontics, Rosenstiel, et al

Factors for Success Accurate Casts

Accurate Casts Accurate Facebow Transfer Factors for Success Accurate Casts Accurate Facebow Transfer

Indirect Mounting Technique

Direct Mounting Technique

Steps for Articulating Casts

Magnetic Mounting Plates Check the fit of the removable plates. Plastic Plate Metal Disk Magnets Use blue adjustment wrench only if necessary!

Condylar Settings Set progressive side shift: Typical setting are 10 or 15 degrees Zero degrees may be used to mount cases. Set condylar guidance to 30 degrees.

Acrylic Guide Table Incisal Guide Pin Locate incisal guide pin and acrylic guide table Place incisal guide table on the lower member

Acrylic Guide Table Incisal Guide Pin Place incisal guide pin in the incisal guide boss with the chisel end up & the round end down Set incisal guide pin to the zero mark At zero, the upper & lower members are parallel (important info)

Quick Mount Remount Jig PVA Mounting Jig

Quick Mount Remount Jig PVA Mounting Jig

Quick Mount Remount Jig PVA Mounting Jig

Quick Mount Remount Jig PVA Mounting Jig Mount jigs on lower member. No mounting plate on lower at this time. Fit maxillary cast onto PVA jig. Close upper member Trim lugs as needed

Mounting Casts Soak the base of the cast in water before mounting to the articulator.

Mounting Casts Armamentarium: Read directions! Rubber bowl Spatula Water syringe Envelope of mounting stone Read directions!

Mounting Casts Wet the bowl before proceeding Add water to bowl before adding powder

Mounting Casts Always shake the stone to one end of the packet before opening carefully! Add powder to the water quickly, but without splashing

Mounting Casts Mix thoroughly and quickly without flipping powder everywhere! Final consistency has form, but isn’t stiff

Mounting Casts Put some stone on the cast, then on the mounting plate.

Mounting Casts Close articulator and make sure nothing has moved. Hold cast steady on jig until stone sets.

Dressing Casts Dressing the casts Remove by grasping the mounting plate Do NOT remove a mounted cast from an articulator by grasping the cast

Dressing Casts Dressing the casts Mix new batch of mounting stone Grasp mounted cast securely, touching both the cast and the mounting plate

Dressing Casts

Dressing Casts

Dressing Casts

Mounting Lower Cast Hand articulate lower cast with upper Remove blebs Check stability Note intercuspal relationship

Mounting Lower Cast Invert articulator Put lower cast in MI Attach mounting plate to lower member & check for clearance Mount lower cast as you did for the upper cast

Mounting Lower Cast Keep pressure on articulator to offset expansion of mounting stone. Pin (at zero setting) must touch acrylic guide table after procedures are complete. Dress lower cast

When in doubt, follow the directions!