This document discusses different concepts of occlusion including bilaterally balanced occlusion, unilaterally balanced occlusion, and mutually protected occlusion. It describes the key features of each concept and compares their advantages and disadvantages. The document also discusses factors that influence occlusion like condylar guidance, anterior guidance, and patient adaptability. It defines pathogenic occlusion and lists potential signs and symptoms. Finally, it outlines objectives and techniques for occlusal treatment, including the use of occlusal splints or devices.
3. Organisation of occlusion
Collective arrangemaent of the teeth in function is
quite important & has been subjected to a great deal
of analysis discussion over the years.
There are 3 recognized concepts that describes the
manner in which teeth should & should not contact in
various functional & excursive positions of the
mandible.
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4. They are :
1. Bilateral balanced occlusion
2. Unilateral balanced occlusion / Group function
3. Mutually protected occlusion/Canine guidance
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5. Bilaterally balanced occlusion
It dictates that maximum number of teeth should
contact in all excursive movements of the mandible.
It is important for complete denture fabrication, in
which contact on non working side is important to
prevent tipping of the denture.
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6. This concept was applied to natural teeth in complete
occlusal rehabilitation.
Attempt was made to reduce the load on individual
teeth by sharing the stress among as many teeth as
possible.
But it was very difficult to achieve. As a result of
multiple teeth contact during various excursions, there
was excessive frictional wear of teeth.
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7. There was increased rate of periodontal break down.
There was neuromuscular disturbances. However it
was often relieved when posterior contacts on
mediotrusive sides were eliminated in attempt to
eliminate unfavorable loading.
So the concept of unilateral balance was evolved.
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8. Unilateral balance occlusion
Also known as Group function.
It is widely accepted & used method of teeth
arrangement in fixed restorative dentistry today.
It was originated by Schuyler, who observed the
destruction of tooth contact on non working side.
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9. He concluded that as much as cross arch balance is not
necessary in natural teeth, it is best to eliminate all
tooth contact in non working side.
So in unilateral balanced occlusion, all teeth in
working side should be in contact during lateral
excursions.
Teeth on non working side are contoured to be free of
contact.
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10. Group function of teeth on working side destributes
the occlusal load.
Absence of contact on non working side prevents
those teeth from being subjected to destructive,
obliquely directed forces found in non working
interferences.
It also saves the centric holding cusps, ie. Mandibular
buccal cusps & maxillary lingual cusps from excessive
wear.
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11. In this occlusal arrangement load is distributed among
periodontal support of all posterior teeth on working
side.
It can be advantageous if periodontal support of
canine is compermised.
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12. The functionally generated path technique, described
by Meyer, is used for producing restorations in
unilateral balanced occlusion.
It has been adapted by Mann & Pankey for use in
complete mouth occlusal rehabilitation.
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13. Allowing some freedom of movement in antero
posterior direction is advantageous.
This concept is known as long centric, by Schuyler.
It is important for posterior teeth to be in harmonious
gliding contact when the mandible translates from
centric relation forward to make anterior teeth
contact.
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14. Some authors advocates long centric because centric
relation rarely coincides with maximum intercuspation
in healthy natural dentition.
long centric ranges from 0.5 to 1.5 mm.
This theory says that condyle can translate
horizontally in fossae over a trajectory before
beginning to move downward.
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15. Mutually protected occlusion
Also known as Canine protected occlusion or Organic
occlusion.
Originated by D’ Amico, Stuart, Stallard,& Lucia,
members of gnathological society.
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16. They observed that in many mouths with healthy
periodontium & minimum wear, the teeth were
arranged so that overlap of anterior teeth prevented
the posterior teeth from making any contact on either
working or non working sides during mandibular
excursions.
This separation oclusion was termed as Disocclusion.
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17. According to this concept, anterior teeth bear all the
load & posterior teeth are disoccluded in any excursive
position of mandible.
Desired result is absence of frictional wear.
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18. Position of maximum intercuspation coincides with
optimal condylar position of mandible.
All posterior teeth are in contact with forces being
directed along long axis.
Anterior teeth either very lightly or out of contact
slightly.
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19. As a result of anterior teeth protecting the posterior
teeth in mandibular excursions & posterior teeth
protecting the anterior teeth at intercuspal position,
so it is called as mutually protected occlusion.
It is most widely accepted, easily fabricated & greater
tolerance by the patients.
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20. It is necessary to have anterior teeth periodontally
healthy.
In absence of canine or anterior bone loss, mouth
should be restored to group function.
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21. It also depends on orthodontic relationship of
opposing arches.
In class 2 or 3 malocclusion, mandible can not be
guided by anterior teeth.
Also in cross bite cases, where maxillary &mandibular
cusps interfere during working side excursions.
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22. Features of Mutually protected occlusion are :
1. Uniform contact of all teeth around the arch when
mandibular condylar processes are in their most
superior position.
2. Stable posterior tooth contacts with vertically
directed resultant forces.
3. Centric relation coinciding with maximum
intercuspation.
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23. 4. No contact of posterior teeth in lateral or protrusive
movements.
5. Anterior tooth contacts harmonizing with functional
jaw movements.
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24. Criteria to achieve Mutually protected occlusion :
1. Full complement of teeth exists
2. Supporting tissues are healthy
3. No reverse articulation or cross bite
4. Occlusion is Angle’s class 1.
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25. It looks illogical to load single rooted anterior teeth to
multi rooted posterior teeth during chewing.
But canine & incisors have distinct mechanical
advantages over posterior teeth.
Effectiveness of forces exerted by muscles of
mastication is less when loading contact occurs farther
anteriorly.
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26. Mandible is a lever of class 3 type, which is the least
efficient of lever system.
Farther the initial tooth to tooth contact occurs, less
effective is the force exerted by musculature & smaller
the load to which teeth are subjected is.
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27. Effects of anatomic determinants
Condylar guidance & anterior guidance have strong
influence on occlusal morphology of teeth being
restored.
It is a relationship of numerous factors like immediate
lateral translation, condylar inclination, disc flexibility,
cusp height, cusp location, groove direction etc.
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28. Molar disocclusion
On repeated lateral movements, there wont be same
path due disc flexibilty.
This deviation is 0.2 mm in centric relation, 0.3 mm in
working, & 0.8 mm in protrusive and non working
movements.
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29. To avoid occlusal interferences & non axially directed
forces on molars during eccentric movements, molar
disocclusion must be equal to or more than these
deviations.
It is advised to have 0.5 mm in working, 1 mm in non
working & 1.1 mm separation from mesio buccal cusp
tips of first molar.
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30. Condylar guidance
Mainly protrusive condylar guidance & mandibular
lateral translation.
Protrusive condylar path can be steep or shallow.
It has average angle of 30.4 degree from horizontal
reference plane.
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31. If protrusive condylar path is steep, cusp height must
be longer & vice versa.
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32. If immediate lateral translation is great, then cusp
height must be shorter & vice versa.
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33. Grooves & ridges are affected by condylar path mainly
lateral translation.
Nearer the tooth is to working side condyle antero
posteriorly, smaller the angle between working & non
working paths and vice versa.
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34. Anterior guidance
The track of incisal edges of mandibular to maxillary
anterior teeth from maximum intercuspation to edge
to edge occlusion is called as protrusive incisal path.
Angle formed between protrusive incisal path &
horizontal reference plane is called as protrusive
incisal path inclination.
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35. It ranges from 50 to 70 degree.
In healthy occlusion, anterior guidance is 5 to 10
degree steeper than condylar path in sagittal plane.
Therefore when mandible moves protrusively, anterior
anterior teeth guide mandible downward to create
disocclusion in posterior teeth.
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36. Lingual surface of maxillary anterior teeth has both
concave & convex surface, cingulam.
Mandibular incisal edge should contact maxillary
lingual surfaces at transition from concavity to
convexity in centric relation position.
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37. Anterior guidance affects the occlusal morphology of
posterior teeth.
Greater the vertical overlap of anterior teeth, longer
is posterior cusp height.
Greater the horizontal overlap of anterior teeth,
shorter is posterior cusp height.
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38. By increasing anterior guidance to compensate for
inadequate condylar guidance, it possible to increase
cusp height.
If protrusive condylar inclination is shallow, requiring
short posterior cusps, cusps may be lengthened by
making the anterior guidance steeper.
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39. Increasing anterior guidance will permit the
lengthening of cusps that would otherwise have to be
shorter in presence of pronounced immediate lateral
translation.
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40. Patient adaptability
Most of the patients are able to adapt small occlusal
deficiencies without exhibiting acute symptoms.
lowered threshold :
Patients with low pain threshold do not present much
difficulty in diagnosis.
But it should not be confused with hypochondria
which is poor adaptability to occlusal discrepancies.
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41. raised threshold :
Individuals who have adapted to existing mal
occlusion may be comfortable with their dentition,
although numbers of signs are evident.
However occlusal treatments are advised to prevent
further problems.
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42. Pathogenic occlusion
It is defined as an occlusal relationship capable of
producing pathologic changing in stomatognathic
system.
There is disharmony between teeth &TMJ to present
the symptoms.
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43. Signs & symptoms :
Diagnosis is difficult because of combinations of
symptoms. Following symptoms can help to confirm
the diagnosis –
1. Teeth
2. Periodontium
3. Musculature
4. TMJ
5. MPDS
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44. Teeth
Hyper mobility - due to premature contact inCR
Open contacts – due to tooth migration, unstable
occlusion
Abnormal wear – due to parafunctional activities
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45. Periodontium
Widened periodontal ligament space – due to
premature occlusal contact
Advanced periodontal disease – bone loss, rapid tooth
migration due to occlusal descrepancies
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46. Musculature
Acute or chronic muscular pain – due to bruxism
Trismus - due to no relaxation of elevator muscle
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47. TMJ
Pain, clicking or popping – due to muscular origin, or
internal derangement of joint.
Unilateral clicking with midline deviation – due to
displaced disc.
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48. MPDS
Diffuse unilateral pain in preauricular area with muscle
tenderness, clicking, popping noise in contralateral
Tmj joint.
Due to bruxism or clenching with chronic muscle
fatigue leading to muscle spasm & altered mandibular
movement.
Tooth movement may occur & malocclusion becomes
apparent when muscle spasm is releived.
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49. Or malocclusion of teeth displaces the condyle, &
feeedback from dentition is altered that results in
muscle spasm.
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50. Occlusal treatment
Any signs & symptoms that correlates occlusal
interferences, then occlusal treatment should be
considered.
It can be done by tooth movement by orthodontics,
elimination of deflective contacts through selective
reshaping of occlusal surface of teeth, or restoration &
replacement of missing teeth that result in more
favorable distribution of occlusal force.
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51. Objectives of occlusal
treatmaent
1. To direct occlusal forces along long axis of teeth.
2. To attain simultaneous contact of all teeth in CR.
3. To eliminate any occlusal contact on inclined planes
to enhance positional stabilty of teeth.
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52. 4. To have centric relation coincides with maximum
intercuspation position.
5. To arrive at occlusal scheme selected for patient. i.e
unilateratl or mutually protected occlusion.
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53. These objectives can be accomplished with removable
occlusal device, fabricated from clear acrylic resin that
overlies the occlusal surfaces of one arch.
Definitive occlusal treatment involves accurate
manipulation of the mandible, particularly in centric
relation.
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54. Because patient may resist such manipulation as a
result of protective muscular reflexes, deprogramming
device can be used, also called as occlusal device.
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55. Occlusal device therapy
Also called as occlusal splint, oclusal appliance or
orthotics.
It is particularly helpful in determining whether a
proposed change occlusal scheme can be tolerated by
patient.
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56. It is made in acrylic overlay, that allows testing of the
scheme, with slight increase in vertical dimension.
If patient responds favorably to occlusal device, then
restorative treatment will be positive.
So it is important diagnostic procedure before
initiation of treatment.
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57. It can be made for either maxillary or mandibular
teeth.
It can be made by direct or indirect technique.
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58. Direct technique ( auto polymerised
) Can be done in 1 appointment.
Uses mouth as articulator, introducing errors.
Vaccum formed matrix is thin & flexible, require more
coverage for stablity.
Chipping & breaking, need for chair side repair.
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59. Stains, odors, & excess wear because of porosity of
acrylic.
Device can be duplicated in heat cure acrylic resin for
greater durability.
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60. Procedure :
Adapt a sheet ( 1 mm thickness ) of clear thermoplastc
resin to diagnostic cast. Excessive undercuts should
have been blocked out.
Trim the excess resin so all facial soft tissue is exposed.
On lingual surface of maxillary device, matrix should
cover anterior third of hard palate for rigidity.
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61. Try the matrix for fit & stability.
Add small amount of self cure acrylic in incisal region
& guide mandible in CR by bimaual manipulation
technique so that shallow indentation will come in
acrylic resin.
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62. Add more resin to incisors & canine region, ask patient
to do retrusive, protrusive and lateral closure in soft
resin.
Allow resin to polymerize.
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63. With help of marking ribbons, adjust resin to give
smooth, even contacts during protrusive & lateral
excursions as well as definite occlusal stop for each
incisors in CR.
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64. Ask patient to wear the device overnight before the
acquired protective muscle patterns are overcome.
If posterior tooth eruption to be avoided, patient must
be seen again in 24 to 48 hours.
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65. Place pencil marks in depressions made by opposing
functional cusps.
Remove excess resin with bur or wheel & leave those
pencil marks. All other contacts must be eliminated.
Smoothen and polish the device.
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66. Indirect technique
More esthetic
Less chance of breakage, warping or wear
More precise occlusal contacts with articulator
Less chair time at delivery
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67. Better adaptation to teeth & soft tissues.
Less coverage needed for stability.
Use of ball clasps for retention.
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68. Indirect technique With self cure
acrylic resin
Mount diagnostic casts accurately.
Be sure that device is made at same vertical dimension
as centric relation recorded.
Fit articulator with incisal guide table flat.
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69. Lower the incisal guide pin until there is 1 mm of
clearance between posterior teeth.
Check the clearance of 1 mm during protrusive
movements.
Raise the platform wings of incisal guidance table in
all lateral excursions, for 1 mm of clearance.
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70. Block out the undercuts with wax.
Form wire clasps to engage facial undercuts, seal the
casts with separating medium.
Fabricate device with self cure acrylic.When resin is
still soft, close the articulator.There will be depression
formed by each functional cusps.
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71. Close articulator in protrusive & lateral excursions.
Add or remove acrylic until it is in constant contact
with anterior teeth when incisal guide pin contacts the
guide table.
After it polymerize, refine the occlusion on articulator.
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72. There should be even contact for each functional cusp
in CR.
A stop should exist for each anterior tooth in CR.
Protrusive contacts on incisors should be smooth &
even.
There should smooth & even lateral contact on
laterotrusive canines.
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73. Indirect tehnique with self cure resin
( alternative technique )
Obtain accurate casts & interocclusal record.
Articulate the casts in CR.
Adjust the articulator pin until 2 mm of interocclusal
clearance results.
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74. Wire clasps & 2 sheets of base plate wax are adapted
on maxillary casts.
Develop anterior ramp & establish evenly destributed
occlusal contact with mandibular teeth.
Wax sprues are added to posterior side of waxed
device.
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75. Laboratory silicone is adapted over wax up.
After wax is boiled off, reposition the clasps & lute
them with sticky wax.
Apply separating media. Self cure is filled in the mold
cavity between cast & repositioned silicone.
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76. After polymerization, reattach casts to articulator &
adjust occlusal contacts until mutually protected
articulation is achieved.
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77. Indirect technique ( heat cure )
Articulate the casts in CR. Notch the bases of cast for
remounting.
Create desired device in wax, obtaining centric stops &
anterior guidance.
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78. Separate the casts & flask it in conventional manner.
Process in heat cure clear acrylic.
Rearticulate & adjust the occclusion.
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79. Patient is asked to wear the device for 24 hours a day,
removing it only for oral hygiene. Check it weekly,
biweekly for modifications.
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80. Occlusal interferences
Interferences are undesirable occlusal contacts that
may produce mandibular deviation during closure to
maximum intercuspation or may hinder smooth
passage to & from the intercuspal position.
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81. Types :
1. Centric
2. Working
3. Non working
4. Protrusive
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82. Centric interference :
It is a premature contact that occurs when mandible
closes with the condyles in their optimum position in
the glenoid fossa.
It causes deflection of mandible in posterior, anterior
or lateral direction.
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83. Elimination of interference :
1. Find any interference that cause condylar process to
displace anteriorly,( protrusive interference). It is
mesial incline of maxillary & distal incline of
mandibular teeth.
2. Continue adjustment until all teeth contact evenly
( except incisors ). If excursive movements are guided
by canines, then stop when bilateral canine to canine
contact is restablished.
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84. In lateral displacing prematurity, adjust buccal facing
inclines of maxillary & lingual facing inclines of
mandibular teeth. Premature contact can be on
laterotrusive or mesiotrusive side of mandible.
In laterotrusive side, adjust buccal inclines of maxillary
lingual cusps & lingual inclines of mandibular buccal
cusps until there is contact on cusp tips.
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85. If it is in mesiotrusive side, adjust buccal inclines of
mandibular buccal cusps & lingual inclines of maxillary
lingual cusps until there is contact on cusp tips.
It is verified with Mylar shim stocks in forceps.
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86. Working interference :
It occur when there is contact between maxillary &
mandibular posterior teeth on the same side of the
arches as the direction in which mandible is moved.
If that contact is heavy enough to disocclude anterior
teeth, it is interference.
Between maxillary lingual facing cusp inclines &
mandibular buccal facing cusp inclines.
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87. Non working interferences :
It is occlusal contact between maxillary & mandibular
teeth on the side of arches opposite the direction in
which mandible has moved in lateral excursion.
It is of destructive nature, can damage the masticatoty
apparatus.
Between maxillary buccal facing cusp inclines &
mandibular lingual facing cusp inclines.
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88. Protrusive interferences :
It is a premature contact occurring between mesial
aspect of mandibular posterior & distal aspect of
maxillary posteriors.
Proximity of teeth to muscles & oblique vectors of
forces make contacts between opposing destructive
as well as interfere to incise properly.
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89. Elimination of lateral & protrusive interferences :
1. Use red & blue marking to distinguish centric and
eccentric contacts.
2. Goal is to eliminate contacts between all posterior
teeth during protrusive movements & to eliminate
any interference on non working side as well as on
working side.
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90. 3 No centric contacts to be removed.
4. Lateral & protrusive contacts are eliminated by
creating a groove that permits escape of the
functional cusps during eccentric movements.
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91. Diagnostic occlusal adjustments
2 stets of articulators are required.
1 act as reference & other is used to remove the tooth
structure.
Occlusal surfaces are painted with poster paint.
Pin setting is recorded before removing enamel.
Each step is recorded carefully.
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92. Objectives of selective occlusal reshaping :
Redistribute forces parallel to long axis of teeth by
eliminating contacts on inclined plane & creating cusp
fossa occlusion.
To eliminate deflective occlusal contacts, centric
relation coincides with maximum intercuspation.
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93. To improve worn occlusal harmony, enhance cuspal
shape, narrow occlusal table, proper developmental &
supplemental grooves.
To correct marginal ridge discrepancies & extrusions
so that oral hygiene will be easier.
To correct tooth malalignment through selective
reshaping.
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95. Open anterior occlusal relationships.
Excessive wear.
Before orthodontic or orthognathic treatment.
Before occlusal appliance therapy.
Patients withTMJ pain.
Patients with jaw movements cant be manipulated
easily.
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96. Optimum occlusion
In placement of restorations, dentists must produce
an occlusion that is nearly optimum as oral conditions
of the patient.
It requires minimum adaptation by the patient.
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97. Okeson’s criteria for optimum occlusion :
1. In closure, condyles are in most superoanterior
position against the discs on posterior slopes
eminence of glenoid fossae. Posterior teeth are in
solid & even contacts, anterior teeth are in slightly
lighter contact.
2. Occlusal forces are in long axes of the teeth.
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98. 1. In lateral excursions, working side contacts
disocclude or separate the non working side
instantly.
2. In protrusive excursions, anterior tooth contacts will
disocclude the posterior teeth.
3. In upright posture, posterior teeth contact more
heavily than do anterior teeth.
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99. Restoring lower anteriors
While restorative correction of any occlusal problem,
always lower anterior should be completed first.
First consideration is to determine the correct
location of incisal edges, based on most stable centric
contact with upper anterior & mounted models.
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100. It is ideal if lower anterior contact in centric relation at
correct vertical dimension on cingulum of upper
anterior teeth.
Whenever possible, incisal edges should follow a
horizontal alignment with the centre bowed up
slightly.
Flat or reverse curve alignment gives a harsh
appearance, not attractive.
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101. When alveolar ridge slants off a normal horizontal
line, incisal edges should should still be aligned evenly
along the horizontal plane.
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102. Wear on incisal edges produce sharp line angles.
Restoring the edges with rounded contour reduce the
wear, but looks artificial.
Slight rounding the line angle & giving slight concavity
in centre of edge looks natural without creating wear
problem.
Sometimes too steep anterior guidance can be
flattened by shortening the lower anterior & restoring
lingual surfaces of upper teeth.
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103. Restoring upper anteriors
Correct lip support : teeth not in harmony with lip are
not only unstable but also uncomfortable &
unesthetic.
Precise incisal edge position : it establishes correct
length of each tooth & plays dominant role in
esthetics and determinant of optimum function.
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104. Labial contour : some are flat, some convex, square or
fan shaped, depending on patient’ smile.
Lingual contour : it is last step to prepare, based on
centric relation to incisal edge position.
Phonetics : incisal edge of upper teeth should lightly
touch vermillion border of lower lip during F,V sounds.
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105. Anterior guidance angles : in sufficient overjet,
lengthen the upper anterior & compensate with
concave lingual contour so flat guidance angle can be
maintained.
In minimum overjet, don’t lengthen upper anterior
without steepening anterior guidance angle.
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106. Determining the type of posterior
occlusal morphology
There are 3 basic steps :
1. Selection of type of centric holding contacts
2. Determining type & distribution of contact in lateral
excursions
3. Selection of most practical method of providing
stability of occlusal form.
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107. Types of centric holding contacts :
There are 3 basic ways by which centric contact is
established :
1. Surface to surface contact
2. Tripod contact
3. Cusp tip to fossa contact
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108. Variations of posterior contact in lateral excusions :
Whenever lower teeth move towards tongue, it should
not contact.
While teeth on working side are disoccluding the teeth
on non functioning side, they must also act as cuter,
grinder, holders.
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109. It is decided by selecting one of the following working
side occlusion :
1. Group function
2. Partial group function
3. Posterior disocclusion
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110. Selecting occlusal form for stability :
There are 4 basic types to choose form in normal arch
relationship :
Type 1 : lower buccal cusps contact upper fossa.There
are no other centric contacts.Working side excursive
function is limited to lingual inclines of upper buccal
cusps.
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111. Type 2 : centric contacts on tips of lower buccal cusps &
upper lingual cusps.
Working side excursive function is limited to lingual
inclines of upper buccal cusps.
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112. Type 3 : centric contact on tips of lower buccal cusps &
upper lingual cusps.
Working excursion contact is limited to the lingual
incline of upper buccal cusps & buccal incline of lower
lingual cusps.
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113. Type 4 : tripod contact
There are 2 types :
1. Contacts on sides of cusps & walls of fossa
2. Centric contact on brims of fossa& top of wide cusp
tips with no contact in eccentric excursions.
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114. Restoring lower posteriors
It is advised to restore lower posterior first than upper.
Posterior teeth in lower arch is accurately restored
with cusp tip to fossa contact with following basics :
1. Correct height & placement of buccal cusps
2. Correct height & placement of lingual cusps
3. Correct placement of fossa
4. Correct incline of fossa wall
5. Accurate ridge & groove direction
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115. placement of lower buccal cusps :
Buccal cusp placement for bucco lingual stability : the
lower buccal cusp must be positioned such that its
contacts directs the stress through the long axis of
both upper & lower teeth.
The main force vector should be as parallel as possible
to long axis of both upper & lower tooth.
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116. Mesiodistal placement of lower buccal cusps :
for attaining mesi distal stability
Cusp tip should be centered in correctly designed
upper fossa , than on incline or flat surface contact.
It will direct the force through long axis & eliminate
possibility of plunger cusp for food impaction.
There will not be tendency for cusp tips to migrate out
of fossae.
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117. Locating lower buccal cusps for non interfering
excursions :
While locating cusp tip placement, path of egress
from centric relation should be considered.
Egress towards buccal is equally non interfering on
each of contacts.
However if centric stop is placed on distal, egress
towards lingual is interfered by upper lingual cusp.
If lower buccal cusp tip is placed in upper mesial fossa,
it moves out on excursion towards lingual.
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118. Path of any lower cusp can be determined in mouth or
articulator by visualizing the path as being at right
angles to imaginary line from rotating condyle to the
cusp in question.
Path depicted on opposing side from rotating condyle
shows balancing excursions, while on same side shows
working excursions.
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119. Contouring cusp tips :
In correctly contoured cusp tip to fossae contact, the
cusp tip contacts in centric relation & through any
purely horizontal movements.
If lateral excursion contacts is desired, side of the cusp
takes over & cusp tip is disoccluded.This minimizes
wear on centric holding contacts.
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120. Wide cusp tips produce neither better function nor
better stabilty.
Properly contoured small cusp tip fits into base of
saucer shaped fossa that helps to stabilize it.
Small cusp tip permit good anatomy, require less force
& produce less stress.
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121. Contouring the lower fossa :
Inner incline of upper canine dictates the incline
limitations of lower posterior inclines facing it.
Lower working side incline can not be steeper than
lateral anterior guidance incline of cuspid. It should be
made flatter because it is not necessary for lower
incline to contact in function.
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122. Balancing incline should never be allowed to contact in
function.
So it should also be flatter than lateral guidance of
cuspid.
If angle is steeper than lateral anterior guidance, upper
lingual cusp will be locked into lower fossa & back
teeth will clash stressfully in lateral excursions.
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123. Contouring ridges & grooves :
Its action is to crush, tear & shred food against upper
inclines.
Extreme preciseness is not required because in cusp
tip to fossa relationship only the base of lower fossa
contact the upper lingual cusp.
Walls of fossa never contacts & grooves are opened up
to avoid contact.
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124. Placement of lower lingual cusps :
Lower lingual cusp is non functional as far as contact ic
concerned. However still it should act as gripper &
grinder of food.
Cusp tips should be rounded & smooth to hold the
tongue out of the way, but should be located over root
within long axis.
Distance between lower buccal & lingual cusp tip is
same as upper cusp tips.
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125. Distance between buccal & lingual cusp tip should not
be greater than half of total buccolingual width of
tooth at its widest part.
Lower lingual cusp height is about 1 mm shorter than
buccal cusp tip. It is further lower in first premolar.
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126. Procedure for locating buccal & lingual cusp tips :
1. Draw line on central grooves of upper posterior.
2. Try to select fossae for cusp tip placement & mark it.
3. Buccal cusp tip is placed where each line intersect.
4. Drill a hole at each cusp tip location by bur.
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127. 5. Insert 3 mm long 14 gauge wax sprue into hole &
close the articulator.
6. Flow red inlay wax around occlusal part of die to
engage sprue wax.
7. Articulator is opened & wax is added around die and
crown is build up.
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128. 8. Broadrick occlusal plane analyzer is used to
determine height of buccal & lingual cusp based on
curve of wilson and curve of spee.
9. Then dark cusp tips are never touched.
10. Buccal anatomy is carved. Crest of contour is at
gingival & middle third junction.
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129. 1. Lingual cusp tips are located by measuring the upper
cusp teeth with double pointed caliper.
2. Then lingual contour is carved. Crest of contour is at
middle third.
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130. Procedure to make fossa contour guide :
1. Anterior guide table is flattened to zero degree.
2. Special fossa contour pin is inserted in place of
incisal pin.
3. Softented wax is placed on flat guide table & upper
model is moved in left and right excursions, but not
go in protrusion.Take guidance with upper cuspid.
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131. 4.When lateral guidance pathways are cut sharp into
the wax, pin is raised, & applied separating media.
5. Same guidance is duplicated in self cure acrylic.
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132. There are 3 basic rules for using fossa contour guide :
1. Always hold the handle perpendicular.
2. Never destroy the predetermined cusp tip.
3. Locate fossa in proper relation to cusp tips.
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133. Restoring upper posteriors
There should be sufficient thickness of metal &
porcelain in all excursions.
Generally it is checked in CR only.
If anterior guidance is not finalized & lower posteriors
are not in final form, it is not possible to determine
clearance for upper posteriors.
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134. Dentist has to decide whether upper inclines has to be
in group function, partial group function or total
disocclusion in excursive movements.
Accordingly inclines are contoured& angulated.
Supplemental grooves are cut into inclines to increase
gripping ability of tooth surface.
Grooves are carved smaller than cusp tips.
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135. If we select to provide Group function on working side,
length of the contact stroke should be progressively
shorter from anterior teeth back.
Molar contact is only maintained for a fraction of its
inclined surface, while cuspid contact is maintained all
the way to incisal edge.
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136. If molar contact is maintained for entire incline,
protection from guidance is lost.
Stress exerted against the molar is severe because of
its torque effect near condylar fulcrum.
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137. Upper occlusal inclines should be contoured to
disclude in a manner that allows the anterior teeth to
maintain contact the longest.
Second molar should contact in a working side
excursion for no more than half its incline length.
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138. Occlusion on restoration is often ruined by errors of
cementation.
Unless some space is given for cement, the most
meticulously made crowns will be high after
cementation.
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139. Conclusion
The perfection of skills required to provide
sophisticated treatment of complex occlusal problems
may take years to acquire.
However, the minimum expectation of the
competent practitioner is the ability to diagnose &
treat simple occlusal disharmonies, should be able to
produce restorations that will avoid creation of
iatrogenic occlusal disease.
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140. Thank you
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