Articulating Casts on the Hanau Articulator Dr. Pauline Hayes Garrett Department of Endodontics, Prosthodontics, and Operative Dentistry University of Maryland, Baltimore

Introduction An articulator is an instrument that duplicates certain important diagnostic features and border movements of the mandible.  In conjunction with accurate and properly mounted diagnostic casts, it may be used for diagnosis, treatment planning and treatment.  It is important to understand that the usefulness of the articulator diminishes if information gathered from the patient is inaccurate and/or the casts are mounted inaccurately.

Introduction (cont.) A facebow transfer was recorded from a simulated patient, and the casts of that patient are now ready for attachment to (mounting on) the articulator.  Casts derived from a patient should be properly trimmed with a base which is not too thick (approx. ½ inches)  A thick base might not allow enough room between the facebow and the maxillary mounting ring.  In this exercise, casts from the simulation patient will be mounted. 

Armamentarium a)      mounted facebow template from simulated patient, provided by the instructor b)      set of casts from the rubber molds c)      Hanau articulator d)      white model plaster e)      rubber mixing bowl f)        plaster spatula g)      metal (or disposable plastic) mounting plates h)      CaStix i)        CaStix adhesive system j)        bunsen burner k)      wet/dry sandpaper

Step 1: 1)      Soak the maxillary cast for 5 minutes.  This will provide better adhesion between the stone and plaster.

Step 2: 2)      Cut “key ways” into the base of the cast.  They will allow you to replace the cast in the proper position should it be separated from the mounting plaster (either on purpose or by mistake), and they will help keep the stone attached to the plaster.  These three “V” shaped groves may be made with a lab knife and should be located along the bottom of the base in the area of the posterior corners and the anterior incisor area. They should be 3-5 mm deep.

Step 3: 3)      Set the incisal pin to the mid-line (thick line in the middle).  This is considered “zero”.

Step 4: 4)      Lubricate around the threaded mounting studs on the upper and lower members of the articulator with a thin layer of Vaseline.

Step 5: 5)      Secure a mounting plate to the mounting stud on the upper member.

Step 6: 6)      Attach a mounted facebow template to the lower member.

Step 7: 7)      Carefully seat the maxillary cast into the imprints made in the baseplate wax on the bitefork. Note: Use the telescope to support the maxillary cast

Step 8: 8)      Raise the upper member of the articulator and place a mound of thick, creamy model plaster on the base of the cast.  (THE WATER/POWDER RATIO IS APPROXIMATELY 100 GRAMS OF MODEL PLASTER TO 45 ML OF WATER.)  This should be just enough to “tack” (attach) the cast to the articulator.

Step 9: 9)  Swing the upper member of the articulator down until the incisal pin is resting on the mounting platform or the anterior table.  Be sure the plaster is engaging the cutouts in the mounting plate.  Add more plaster if necessary.

Step 10: 10)  Remove excess plaster off the top of the mounting plate with a spatula.

Step 11: 11)  When the plaster has set completely (AT LEAST ONE HOUR), carefully open the articulator and remove the facebow assembly.  The maxillary cast should remain on the articulator in order to mount the mandibular cast.

Step 12: 12)  The DRY mandibular cast is positioned against the maxillary cast in a maximum intercuspal position and secured there by attaching the CaStix to the anterior and 2 posterior areas of the intercuspated casts with adhesive.  BE CAREFUL TO KEEP THE ADHESIVE AWAY FROM YOUR FINGERS.

Step 13: 13)  Fasten a new mounting plate to the lower member of the articulator.

Step 14: 14)  Carefully turn the articulator upside down.  Verify that the guide pin is still at a “zero” position, wet the base of the mandibular cast, and mount the mandibular cast to the articulator using plaster in the same manner as described for the maxillary cast.  AGAIN WAIT ONE HOUR BEFORE PROCEEDING. Note: Lower Cast is Mounted in Maximum Intercuspation

Step 15: Place a heavy duty rubber band around the upper an lower members of the articulator to allow pin to remain “zeroed out” during the expansion process of the plaster.

Step 16: 15)  At this point, the casts are mounted and can be removed from the articulator to add more plaster to complete the mounting.  Additional mixes of plaster are added to the mounted casts to fill in the void areas.  The finished plaster should extend to the edge of the mounting plate and to the outer edge of the base of the casts.  The plaster can then be finished smooth with wet/dry sandpaper.  

Step 17: 16)      Set the condylar inclination using the patient’s protrusive registration.

Mechanical Guide Table

Putting it together Table flush to front Incisal guide pin with flat blade end parallel to straight line on table All settings initially set at zero Guide pin set at zero

Setting the mechanical guide table *Loosen double nut on bottom to place guide table on articulator *Tighten inner nut to hold table in place *Loosen outer nut to shift guide table Outer nut loosened will allow table to shift in an anterior-posterior direction

Setting anterior-posterior tilt of table Place incisal edges of maxillary incisors edge-to-edge *Tilt table up until incisal guide pin touches table Tighten outer nut to lock table in this position *This protects the cast in protrusive movements

Setting lateral wings of guide table The lateral wings are moved by turning the screws attached to each side of the wings. Twist these screws to move the wings of the table. Screws have a lock screw on them.

If patient has canine guidance, place the canines in an edge-to edge relationship. If patient has group function, then place posterior buccal cusps edge to edge

Twist screw until table wing touches the incisal guide pin Teeth and incisal guide table should touch simultaneously

Move to the other side and repeat Canines edge-to-edge Twist screw and lift wing to touch pin

Verify all settings and articulation of casts in all excursive movements Teeth and incisal guide table should touch simultaneously

The patient’s casts are now ready for use