Download Sessionn 15 Wax up #12

Waxing #12 on the Dentoform
Introduction to Posterior Occlusal
Anatomy
Dental Arch Relationships
• The maxillary arch is usually LONGER
than the mandibular arch. So what?
– Every maxillary tooth is more DISTAL than its
opposing counterpart; therefore,
• The only maxillary tooth with 1 opposing
counterpart is the MAXILLARY THIRD MOLAR.
• The only mandibular tooth with 1 opposing
counterpart is the MANDIBULAR CENTRAL
INCISOR.
Dental Arch Relationships
This is a useful diagram (“picket fence”)
that you can easily draw on the margin of a
test before you even look at the questions.
Ideal Class I Occlusion
Maxillary Posterior
Teeth are ½ tooth distal
to their mandibular
counterpart. For
example, the maxillary
1st premolar is ½ tooth
distal to the mandibular
1st premolar. The
Universal numbers of
these pairs will add up
to 33.
The tooth to tooth
relationship is
fixed and
standardized in
Class I Occlusion.
The occlusal
contact scheme
may vary slightly.
This drawing illustrates an occlusal scheme
where the contacts are: cusp tips to marginal
ridges & cusp tips to fossa. Cusp tip to fossa
contacts require a tripod.
With very slight changes to the anatomy of the
teeth you could have cusp-fossa contacts only.
This scheme requires that every contact is a
tripod.
Cusp tips that contact marginal ridge areas could
also contact both adjacent marginal ridges
simultaneously.
Another View
(Cusp to Marginal Ridge)
(Contemporary Fixed Prosthodontics, Rosenstiel, et al, 4th ed)
Another View
(Cusp to Fossa)
(Contemporary Fixed Prosthodontics, Rosenstiel, et al, 4th ed)
Critical Announcement!
If you expect to
pass dental anatomy
questions on Part I
of the boards, you
must know these
relationships!
– Which tooth
touches which
tooth/teeth?
– This cusp touches
where?
– Start NOW!
All of these variations in occlusal schemes are
fundamentally sound and result in stable
occlusal contacts. You should be aware of
these variations. Why? In order to:
1) Properly treat your patients. You have some
flexibility in where to place your contacts.
2) Answer National Board questions. The
questions may be based on any of the
occlusal schemes mentioned.
All of the discussed occlusal schemes have
a principle in common:
All of the contacts are either cusp tips
contacting relatively flat areas or cusp tips
contacting in a fossa with a tripod.
Your dentoform is not equilibrated at this point,
occlusion has not been established. Any
posterior wax-ups that we do on the dentoform
are for anatomic form only. Leave these wax ups
slightly out of occlusion.
Cusp Ridges – the ridges that connect the cusp
tip to the marginal ridge. Note the mesial cusp
ridge of #12 is longer than the distal cusp ridge.
The lingual cusp tips of the maxillary
premolars appear to be angled toward the
mesial.
The lingual cusps of the maxillary premolars, on
the dentoform, are angled mesially to occlude in
the distal fossa of the opposing premolars.
Cusp-Fossa
Two other equally acceptable locations for
occlusal contact in this situation would be:
Cusp tip on distal marginal ridge of #21
Cusp tip contacting both mesial MR of #20 and
distal MR of #21
Add the thin coat of wax –
beginning in the central fossa
and working your way up the
inclines.
Continue with the thin
coat on down to the
finish line. The occlusal
“V” should still be
visible.
Add band of
wax at the
margin.
Seal the wax
at the finish
line.
Project the
emergence
profile of the
crown
Contouring and carving this band of wax should
duplicate accurately the emergence profile of tooth
that you are waxing.
You only need to develop about 2mm of properly
carved emergence profile. This becomes your
gingival or cervical reference for the rest of your
waxing.
Using your unprepared tooth, mark the
location of the proximal contacts both
facially and from the occlusal view.
Connect the
lines. This is a
fairly accurate
way to locate
the proximal
contact areas.
Build the wax extensions to the marks created.
Check from both the facial
view and the incisal view.
Add a small
ridge of wax on
the proximal
contact locators
to create the
facial and
lingual
embrasure
forms.
Symmetrical form of embrasures
Distal – Wider
Mesial – More Narrow
Wax in the proximal
surfaces.
RULE: Proximal
surfaces are fairly
straight from contact
area to CEJ. Initially
wax down over the
finish line. Begin the
carving at the finish
line and move
occlusally. Avoid
removing the contact
area.
Repeat the process for the mesial proximal
surface.
Evaluate the gingival embrasures, they should be
open and the proximal surfaces should be flat to
slightly convex.
Next Step: Locate the buccal and lingual
cusp tips. Use wax cones to facilitate this.
Begin with the lingual cone: Start to establish
the height and location that you think is correct.
Check to see if the cone is in line with the
linguoocclusal line.
With the dentoform closed, check the position of
the lingual cusp cone. It should be located in the
distal fossa of #21, but not touching it. If contact
is noted shave the height of the cone until it is just
out of occlusion.
Lightly melt the wax on the tip of the cone and
close the dentoform.
If you see a flat mark on the cusp tip it means the
wax is in contact with the opposing tooth. Carve
this mark away, the cusp tip should be just out of
occlusion.
Locate the buccal cusp tip with a wax cone.
Try to establish the mesial-distal position and
height using the facial view.
Contralateral side. A straight edge will nearly
touch the cusp tips of the premolars and the
mesiobuccal cusp of the 1st molar. This can be a
general guide line for the height of the cone.
Buccolingual position of cusp tips: The cones
should be in line with the buccoocclusal and the
linguoocclusal lines.
Add Cusp Ridges: Connect the cusp tips to the
marginal ridges.
Lingual cusp ridges / Occlusal view: Evaluate
lingual embrasures. ML embrasure-look at
contralateral embrasure.
Lateral view: compare the contour of the cusp
ridges to the second premolar.
Add Buccal Cusp Ridges: Occlusal View
Pay particular attention to the buccal embrasures
and the mesial and distal point angles that are
established.
Buccal Cusp Ridges: Facial View
Evaluate the occlusal embrasures and the contour
of the cusp ridges.
Add the mesial and distal facial line angles. Also
add wax along the central lobe (facial ridge) to
establish the contour there.
Check the contour
of the middle lobe
(facial ridge) with
the lateral view.
The wax at this
point does not line
up well with the
premolar behind it.
Adjust the
central ridge of
wax until it
will very
nearly
superimpose
on the profile
of the tooth
just distal to it.
Complete the facial surface using the marginal
trim, line angles, cusp ridges and central lobe
contour as guiding parameters.
Complete the lingual surface. The lingual
embrasures are much more open compared to the
facial embrasures and the line angles are less
distinct.
This distal view is a good way to evaluate lingual
contours. Look at the contralateral side and
compare. The wax is slightly over contoured at this
point.
The final contour of the lingual surface should be
very similar to the lingual contour of the second
premolar.
Occlusal Surfaces
?
First identify the anatomical components.
Mesial & Distal
Pits:
The deepest
points on the
occlusal
surface.
Junctions for all
of the major
grooves.
Central Groove
Connects the
mesial and
distal pits.
Triangular Ridge
Grooves
Every Triangular
Ridge will have
a groove on both
sides, mesial and
distal.
The central
groove of the
maxillary first
premolar may
extend across the
mesial marginal
ridge to form the
mesial marginal
groove.
Supplemental
grooves are
usually branches
off of the
triangular ridge
grooves.
Supplemental
grooves are
secondary
anatomy.
Every cusp tip will
have a triangular
ridge. These are
convex structures.
There are two
triangular ridges
on the maxillary
first premolar.
Marginal ridges
are also convex
structures. They
extend from the
proximal contact
areas to the
respective pits.
The marginal
ridges and the
triangular ridges
make up the bulk
of any occlusal
surface.
Begin the occlusal surface by adding the two
triangular ridges. Close the dentoform while the
wax is still soft – avoid contacts.
Add wax to the marginal ridges, and fill and blend
any voids.
Marginal ridge check: Evaluate occlusal
embrasures, open & rounded
Triangular ridge check: Adjacent inclines should
be very similar.
Use the pointed
end of the #7
wax spatula to
“lay out” the
anatomy. Hold
the carver
vertically while
doing this.
Locate the m&d
pits by spinning
the tip into the
wax.
Roughly carve in the pits, the central groove, the
triangular ridge grooves and the mesial marginal
groove.
This is the angle that you initially used to carve
in the grooves – vertical.
Keeping the tip of the carver in the groove, angle
the carver to scrape and blend the edge with the
existing contour.
Facial side of the central groove blended with the
facial triangular ridge. Treat each side of each
individual groove the same way.
Remove any wax
shavings as you
go. Perfect each
individual groove
and using the side
of the carver
smooth each
segment between
grooves one at a
time.
When both sides of a groove have been carved
the groove becomes distinct. Grooves are
actually the confluence of two inclines.
Continue around the
occlusal surface defining
grooves and smoothing the
areas between grooves.
Supplemental grooves may
be added as you go.
The mesial
marginal groove
Make final evaluations using a variety of
views.
Check emergence profiles: There should be a
smooth transition from tooth peg to wax margin.
Reseal and re-carve margins if any discrepancies
are noted.