Record bases and oclusal rims.

2. BY ARBIYA ANJUM.S

3. RECORD BASES

5. Objectives:
-Helps in transfer of accurate jaw relation ships
to an articulator
- To enable the setting of artificial teeth for the
trial denture.

6. MATERIALS & METHODS
-It is generally agreed that
maxillomandibular relations are difficult -
to record accurately.
- Record bases are made of several different
materials.

7. TYPES
TEMPORARYRECORDBASES:
--They are discarded and replaced by denture base
material, once their role in establishing jaw relation,
teeth arrangement and try in is complete.

8. Types of temporary record
bases:
Shellac base plate
Reinforced shellac base plate
Cold cure acrylic resin
visible light cure acrylic resin
Vacuum formed vinyl and polystyrene
Base

9. PERMANENT RECORD
BASES
They are not discarded and become part of the actual
base of the finished complete denture.
TYPES OF PERMANENT RECORD BASES:
.Heat cure acrylic resin
.Gold
.Chromium-cobalt alloy
.Chromium-nickel alloy

10. Shellac base plate
advantages:
-They will adapt to intimate contact with the mastercast.
-Procedure is not time consuming
-cheap
-uniform thickness
-Can be corrected easily by reheating and readapting to the
mastercast.

11. Disadvantages :
Quickly adapted, BUT not considered
satisfactory.
They warp,
do not fit accurately,
distort easily, lack rigidity,
become brittle and break, and will not permit
polishing of the borders

12. SHELLAC
Any undercuts are relieved, and separating medium
is applied to the cast.
The shellac record base forms are manufactured in
the shapes of the maxillary and mandibulararches.

13. The forms are softened with an open flame and
molded to the cast with an instrument or the
fingers.
While the material is in a softened state, the
excess is removed with scissors.
Afterhardening, the borders are smoothed but as
a rule will not take a polish.

14. Reinforced shellac
Athinlayerofzincoxideeugenolimpressionpasteisspreadoverthetissueside
ofthebaseandseatedonthecastinthemannerofmakingimpression.
Theexcessflashisremovedandthebordersaresmoothed.
Anyundercutsarerelieved,andseparatingmediumisappliedtothecast.
Themanufacturedformofshellacissoftenedwithanopenflame.
Aflattenedwireiscontouredandadaptedacrosstheposteriorpalatalsealarea
ofthemaxillaryrecordbaseandadaptedtothelingualflangeofthemandibular
Recordbaseandincorporatedinthebase.

15. Disadvantages :
-Base is more rigid and stable than shellac but its still
subject to distortion and breakage.
- It is bulky, the odor and
taste of the paste are objectionable to some patients,
and it is unsuitable for arrangement of teeth
in cases of limited inter arch space.

16. Cold cure acrylic
resin
Advantages:
Good strength no need for reinforcement
Good dimensional stability
Does not wrap during manipulation
Closely fit to the master cast

17. DISADVANTAGES:
.Require more time in fabrication
.Difficult to control the thickness
.Residual monomer can cause
irritation to oral tissues

18. METHODS
.Sprinkle on method
.Finger adapted dough method
.Flasking method
.Stone mold method *
.Wax-confined method *

19. SPRINKLE ON METHOD
.Any undercutsare relieved, and separating medium is
applied to the cast.
.Using an eye dropperapply the monomerto the cast,
carefully add the polymer (salt and pepper technique) until
a sufficient thickness is gained over the entire surface of
the cast.
.The processed base is removed from the cast, smoothed,
and polished at the borders.

20. FINGER ADAPTED DOUGH
METHOD
.Any undercuts are relieved, and separating
medium is applied to the cast.
.The self curing resin is mixed according to
manufacturerinstructions
.When it reach the dough stage, it is molded to the
cast with instrument or fingers.
.It is allowed to polymerized completely.
.The processed base is removed from the cast,
smoothed, and polished at the borders.

21. FLASKING METHOD
.A wax pattern is constructed over the cast
with a thickness and contour desired for
complete denture.
.The cast and pattern are flasked, the wax is
eliminated, acrylic resin is packed and
allowed to set under the pressure of clamps or
press.
.The processed base is removed from the cast,
smoothed, and polished at the borders.

22. VISIBLE LIGHT CURED
ACRYLIC RESIN
Any undercuts are relieved, and
separating medium is applied to the cast.
Adapt a sheet of pink base plate material
to the cast by fingers and prevent
trapping of air.

23. .Extend the material to the depth of vestibule.
.Cure the record base for 4 minutes in the light
cure unit. Carefully removed from the cast,
invert and cure the tissue surface for 4 minutes.
.The processed base is removed from the cast,
smoothed, and polished at the borders

24. Vacuum formed vinyl and polystyrene
Any undercuts are relieved, and separating medium
is applied to the cast.
A sheet of base plate material placed over the cast
and inserted in the vaccum chamber.
Electric heater switched to heat the sheet.
Turn on the vacuum. The sheet will adapt closely
to the cast.
Switch of the heaterand allow the record base to
cool.
Remove the record base and cut the excess material

25. Advantages
.Easy to fabricate
.Uniform thickness
.Accurate adaptation to the .Master cast
.Good rigidity
Disadvantages
.Expensive
.Difficult to form smooth rounded .Borders .

26. BASE PLATE WAX
.Wet the cast
.Soften the base plate wax over the flame
and adapt it to master cast
.Remove the excess wax and make the
borders round and smooth.

27. ADVANTAGES
.Easy and rapid method
.Inexpensive and available
DISADVANTAGES
.It lacks rigidity
.It lacks dimensional stability

28. HEAT PROCESSED ACRYLIC
RESIN
A wax pattern is constructed over the cast
with a thickness and contour desired for
complete denture.
The cast and pattern are flasked, the wax is
eliminated, acrylic resin is packed and heat
processed.
The processed base is removed from the cast,
smoothed, and polished at the borders.

29. ADVANTAGES
They are rigid, accurate, stable, not subject to
distortion, and suitable for arrangement of teeth.
DISADVANTAGES :
Require considerable time, more expensive.

32. DEFNITION
“Occluding surfaces built on temporary or
permanent denture bases for the
purposes of making maxillomandibular
relation records and arranging teeth”

33. REQUIREMENTS
the position should be in the anticipated
position of the artificial teeth.
it must be securely attached to the base.
the occlusal surface must be smooth and flat.
it should be contoured to support the lip and
cheeks accurately.
all the surfaces should be smooth.

34. USES
The occlusion rims are used :
To establish the level of the occlusal plane.
to establish the arch form.
to record the maxillary mandibular relations.
for arrangement of the teeth.

35. FACTORS CONTROLLING THE FORM OF
AN OCCLUSAL RIMS
BASICFACTORS
Relationship of the natural teeth to alveolar bone
Relationship of the occlusal rims to the
edentulous ridge
Standard dimensions used to fabricate an
occlusal rims.
Technique of fabrication
Clinical guidelines

36. RELATIONSHIP OF THE NATURAL
TEETH TO ALVEOLAR BONE
Occlusal rims should be fabricated such that it is
parallel to the long axis of the tooth to be replaced.
The maxillary anteriors are labially inclined,hence,
the occlusal rims in that area should also be
labially inclined .
All the posterior teeth are placed vertically ,hence,
the occlusal rim should also be fabricated vertical
in this region .

37. RELATIONSHIP OF THE OCCLUSAL RIMS
TO THE EDENTULOUS RIDGE
Residual ridge resorption changes the apex of
the edendulous ridge
The occlusal rim should be fabricated such
that the midline of the occlusal plane pases
through the apex of the EDENTULOUS
RIDGE

38. STANDARD DIMENSIONS USED TO
FABRICATE AN OCCLUSAL RIMS.
ARCH ANTERIOR REGION POSTERIOR REGION
HEIGHT WIDTH HEIGHT WIDTH
MAXILLARY 20-22mm
from the
deepest part
of the sulcus
3-5mm 16-18mm
from the
deepest part
of buccal
sulcus in the
molar region
6-8mm
MAND
IBULAR
16-18mm
from the
deepest part
of the sulcus
3-5mm At a level of
the junction
roof the
anterior 2/3rd
& posterior
1/3rd of the
retromolar
6-8mm

39. TECHNIQUE OF FABRICATION
Rolled Wax Technique.
Metal Occlusal Rim Former.
Pre-formed Occlusal Rim.

40. ROLLED WAX TECHNIQUE
Recquirements
Commonly used

41. A SHEET OF WAX IS TAKEN AND 1
END IT IS SOFTEN OVER FLAME &
ROLLED TO A WIDTH OF 4MM.

42. Waxisthenrolledcarefullytoavoiidair
bubbles
Rollisagainheatedandconsequetiverollsare
madetoformasinglethickcylinderofwax.
Rolledwaxisthenadaptedovertheinsuch
thatitfollowsthearchform

43. MAXILLARY OCCLUSAL RIMS ARE USUALLY
‘U’ SHAPED & MANDIBULAR ARE ‘V’
SHAPED OR LESS WIDER ‘U’

44. The adapted wax is sealed to the base on
the lingual/palatal surface using a hot wax
knife

45. Mild pressure is applied on the wax to
make it oval in cross section so that it
overhangs a little labially.

46. The Maxillary oclusal rims shows the
labial incination

47. THE OCCLUSAL PLANE IS SHAPED BY
MARKING HEIGHT &REMOVING EXCESS WAX
USING HOTPLATE

48. THE MEASUREMENTS ARE CHECKED &
POSTERIOR EXTENT IS CUT WITH WAX
KNIFE TO GIVE A SLOPE

49. POLISHING
Byswiftflamingfollowedbywipingitgentlywith
aloosemassofwetcottonunderrunningwater.

50. METAL OCCLUSAL RIM FORMER
Waxisrolledtoacylinderasdescribedinprevioustechnique
Thecylinderofwaxisthenshapedusingmetalocclusalrim
former&storedforlateruse
Thesearelateradapted,sealed&finishedasdescribedearlier

51. PRE-FORMED OCCLUSAL RIM
Readymadeocclusionrim
its supplied as a horse shoe shaped rim, adapt it in
the proper position on the record base.
Softened it slightly, sealed it with the record base
by the aid of a wax knife.

52. CLINICAL GUIDELINES
Maxillaryanterioredgeshouldbe0-2mmbelowthe
upperlipatrest.
Theleveloftheupperlipinrelationtotheocclusalrims
showsthelowerlipline.Butitvariesbasedonage

53. Maxillary posterior occlusal plane should be 1/4th inch
below the opening of the stensons duct or parotid duct
Mandibular incisal edge should be at the level of lower
lip & about 2mm behind the maxillary incisal edge
Canine eminence of the lower occlusal rim should be
located at the corner of the mouth

54. Posteriorpartofthemandibularrimshouldextent
till2/3rd ofretromolarpad

55. Anterior maxillary occlusal plane should be parallel to the inter pupillary
line . the antero-posterior occlusal plane should be parallel t o the ala-
tragus line or the campers line or bromel’s line.

56. THE MIDLINE ,SMILE LINE &
CANINE LINE ARE MARKED.

57. TRIAL IN PATIENT