Additive wax technique
Step 1: Locate and place cusp cones
Step 2: Place cusp ridges and marginal ridges
Steps 3,4: Develop buccal and lingual cusp ridges and surfaces
Step 5: Place triangular ridges
Steps 6,7: Refine occlusion, finish and polish
Kinematic Hinge Axis
True axis = kinematic hinge axis. Not easy to find without
This is arbitrary axis = close enough to kinematic without all of the time and money.
13 mm anterior to tragus on tragus-canthus line
6 mm radius from true axis. If you do this,
error is almost negligible.
Accuracy jumped up over time as this was modified
the bump at the condyle portion helped tremendously) - earbows with modifications.
moves anywhere in
Non-working condyle moves in
3 directions - this is the reason for
the medial articulator wall.
Angle between protrussive and W =
Bennett’s angle. On horizontal plane.
N = nonworking direction.
The Frankfort Horizontal Plane
Forion, orbital (lowest part of orbital rim). FH plane.
Occlusal plane is not parallel to
First melt wax on. In the front,
those prongs help with this.
Hanau’s Formula for the “lateral” angle (Bennett’s Angle)
L = H/8 + 12
Where, L= Lateral angle and H= Horizontal angle
Significance of Ear Bow Transfer
- Relates maxillary cast to the Terminal Hinge Axis (manibular condyles)
- Orients the maxillary cast correctly in space using a third point of reference (occlusal plane)
-Is aligned parallel to the interpupillary line
- Permits mounting of the maxillary cast on a semi-adjustable articulator
- The mandibular cast is mounted using a centric relation (CR) record
Centric Relation (CR)
The maxillomandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective disks with the complex in the anterior-superior position against the shapes of the articular eminencies. This position is independent of tooth contact.
CR Each point on curve is an
equal amount of
Any point is CR (any level
of opening, you are in CR), including last point/phalange (still on arc of rotation).
90% have .
Initial point of contact =
CO centric occlusion.
CR is still CO, but CO is a descriptor for a specific CR. MI is not CR.
COMI slide or CRMI slide describe this.
Methods of Recording CR
Chin point guidance
Using two hands to move the jaw.
A bit of acrylic When patient bites down, they bite on acrylic, and eventually deprogram themselves. This removes any abnormal biting so that a patient can move as they naturally do.
**Upward push, not backward.
Centric Relation (CR) Record
Along the arc of rotation of the mandible No teeth touching
Fast setting Dimensionally stable Easily verifiable
Casts mounting in CR 3Rs
Repeatable, reliable, reproduceable - 3Rs for this.
You will never see this with hand examination.
Influence of articular guidance
The more you go to the front, you have more incisal guidance.
Bow - mark 3rd point of reference
Marks 43 mm from occlusal plane. Same distance as orbit distance.