Occlusion in restorative dentistry

© Ramaiah University of Applied Sciences
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Faculty of Dental Sciences
Occlusion as related to
Conservative Dentistry

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Contents
• Introduction
• Terminologies
• General description
– Tooth alignment and dental arches
– Anterior-posterior inter arch relationship
– Inter arch tooth relationship
– Posterior cusp characteristics
– Supporting and non supporting cusp
• Types and directions of mandibular movements
• Mechanism of mandibular motion
• Tooth contacts during mandibular movements
• Role of contact, contours and marginal ridges
•Signs of instability of occlusion
•Response to high restoration
•Requirements for equilibrium of the masticatory
system
•Requirements for occlusal stability
• Occlusal interferences
•Occlusal equilibration
•Occlusal considerations for restorative treatment
•Stamp Technique
•Conclusion
•References

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Occlusion – “Closing”
Introduction
In dentistry, occlusion - “The Contact of the opposing dental arches when they are in contacts
(static) and during various jaw movements (dynamic occlusion)”- Sturdevant’s, 7th edition
Carlsson et al, concluded that “in final analysis, optimal function & the absence of disease is
the principal characteristic of a good occlusion”- Sturdevant’s, 7th edition

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Significance of occlusion in conservative dentistry
A dental restoration after being placed in a tooth, becomes one
of the essential components of stomato-gnathic system
They can initiate/ predispose into myriad of pathologic processes

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Terminologies
• Centric relation - Centric relation is defined as a maxillomandibular relationship
independent of tooth contact, in which the condyles articulate in the anterior-
superior position against the posterior slopes of the articular eminences; in this
position the mandible is restricted to a purely rotary movement; from this
unstrained, physiologic, maxillomandibular relationship, the patient can make
vertical, lateral or protrusive movements; it is a clinically useful, repeatable
reference position GPT-9 (2017)
Jankelson
1972 DF
1956 Posterior
most
Lucia-1961
RUM

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• Centric Occlusion: The occlusion of opposing teeth when the mandible is in centric
relation. This may or may not coincide with the maximal intercuspal position
• Maximal Intercuspal Position: The complete intercuspation of the opposing teeth
independent of condylar position, sometimes referred to as the best fit of teeth
regardless of the condylar position- called also maximal intercuspation
• Balanced Occlusion: Simultaneous bilateral contacting of maxillary and mandibular
teeth in anterior and posterior occlusal areas in centric and eccentric positions

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General description:
1.Tooth alignment & dental arches
Sturdevant’s, 7th edition
• Cusp – Blunt,
rounded or pointed
projections of crown
• Cusp are seperated
by Developmental
Grooves
• Central Groove –
facial and lingual
cusp
• Fossa – Depressions
between cusp
• Fissures – Grooves
with non coalesced
enamel and its
deepest point is a Pit

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2.Inter arch tooth Relationship

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3.Posterior Cusp characteristics

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4.Functional Cusp

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5.Non-functional Cusp

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Features of Non Supporting Cusps / Noncentric / Nonholding
Cusp
Do not contact
opposing tooth in MI
Keep tongue or
cheek off the
occlusal table
Farther from
faciolingual centre
Outer inclines has no
potential for contact
Have sharper cusp
ridges than
supporting cusps
Features of Supporting Cusps / centric / holding / stamp cusp
Contacts opposing
teeth in MI
Supports Vertical
dimension
More rounder cusp
ridges than Non
supporting Cusps
Outer Inclines has
potential for contact
Near the faciolingual
centre of the tooth
as compared to non
supporting cusps

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Types and directions of mandibular movements
Centric relation (CR), is the location of the mandible when the
condyles are positioned superiorly and anteriorly in the
glenoid fossae
• The thinnest avascular portion of the TMJ discs are in an
anterosuperior position on the condylar head, and are
adjacent to the beginning of the slopes of the articular
eminences
Rotation is a simple motion of an object around an axis
• Rotation with the condyles positioned in CR is termed
terminal hinge (TH) movement.
• Maximum of 25mm.
• TH is used in dentistry as a reference movement for
construction of restorations
• Initial contact between teeth during a TH closure provides
a reference point, termed centric occlusion (CO)

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Centric occlusion
• It is the position of maximum intercuspation of teeth which is in harmony with the
neuromuscular mechanism
• This is not the most retruded position of the mandible
• Centric occlusal contacts should be checked in both functional & non-functional occlusion

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Determining centric relation: Dawson’s technique of bimanual
manipulation

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The Kois Deprogrammer
• A removable, plastic appliance that covers the hard palate and creates a single point of
contact between the lower central incisor and the anterior bite plane
• It is an invaluable tool in diagnosing the three most common types of abnormal occlusal
attrition: occlusal dysfunction, parafunction (e.g. bruxism), and constricted path of closure
• It can be used during bite registration. This procedure, with the Kois Deprogrammer in
place, allows control of the vertical dimension of occlusion (VDO) during bite registration
• It facilitates finding premature contacts – i.e. any contact encountered during mandibular
closure with the condyles in CR before reaching MIP. If occlusal adjustment needs to be
obtained, it ensures control because the deprogramming will be maintained

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Recording centric relation criteria for accuracy in making an
interocclusal bite record
The bite record must not cause any movement of teeth or displacement of soft tissue
It must be possible to verify the accuracy of the interocclusal record in the mouth & on
the casts
The bite record must fit the casts as accurately as it fits the mouth
The bite record must not distort during storage or transportation to the laboratory

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Lateral movement(Left) is forward translation of right
condyle &rotation of left condyle
Translation(> 25mm) is the bodily movement of an
object from one place to another. Simultaneous,
direct anterior movement of both condyles, or
mandibular forward thrusting, is termed protrusion
Complex motion combines rotation and translation in
a single movement. Most mandibular movement
during speech, chewing, and swallowing consists of
both rotation and translation

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Role of contact areas,contours and marginal ridges
Creating a contact that is too broad
& changing the tooth anatomy will
disturb the inter dental anatomy
The broadened contact produces an
inter-dental area that is less
cleansable
Creating a contact that is too narrow
leads to greater susceptibility for
plaque accumulation
All of these predisposes to caries &
periodontal problems
A break in continuity of
the line of contact areas
throws additional
responsibility on the PDL
& alveolar bone

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Role of Contour
The concavities occlusal to the height of contour, whether anterior or posterior teeth are involved
in the occlusal static & dynamic relations as they determine the pathways for mandibular teeth in
& out of centric occlusion

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Role of marginal ridges
• A marginal ridge should always be formed in two planes bucco- lingually, meeting at a very
obtuse angle
• This feature is essential when an opposing functional cusp occludes with the marginal ridge
• A marginal ridge with these specifications is essential for:
The balance of the teeth in the arch
Prevention of food impaction proximally
Protection of the periodontium
Prevention of recurrent and contact decay
For helping in efficient mastication

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Requirements for Occlusal Stability
Stable stops on all teeth when condyles are in CR
Anterior guidance in harmony with the border movement of
the envelope of motion
Disocclusion of all posterior teeth in protrusive movements & in
non working side
In lateral movements, supporting cusps should have slight freedom in
centric and occlude in groove or embrasure on opposing teeth, to
facilitate non interfering passage of cusps

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Symptoms/Response to High Restoration
• Tooth ache
• Tooth tender on biting
• Tooth wear
• Spastic masticatory muscles
• Muscle tension headache
• Condyle/ disk displacement
• Degenerative arthritic changes in TMJ

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Occlusal Interferences
• When the teeth are not in harmony with the joints & the mandibular movements,
interference is said to exist
• Interferences are undesirable occlusal contacts that may produce mandibular deviation
during closure to maximum intercuspation or may hinder smooth passage to and from
the intercuspal position

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Types of
interferences
Centric
interferences
Working
interferences
Non working
interferences
Protrusive
interferences

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Eliminating interferences in CR
Centric relation interferences can be differentiated into two types:
Interferences in the arc of closure
Interferences in the line of closure

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Interferences to the arc of closure:
• As the condyles rotate on their terminal hinge axis, each lower tooth follow an arc of
closure
• Most deviations from the arc of closure require the condyle to move forward

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Interferences to the arc of closure:
• Primary interferences that deviate the condyle forward produce the “anterior slide”
• Basic grinding rule to correct anterior slide: MUDL
• May trigger bruxism

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Interference to the line of closure:
• It refers to those interferences that cause the mandible to deviate to the left or right from
the first point of contact to the most closed position

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If the interference incline causes deviation towards the cheek, grind the buccal
incline of the upper or lingual incline of the lower or both. (BULL)
If the interfering incline causes deviation towards tongue, grind the lingual incline of
the upper or buccal incline of the lower, or both the inclines. (LUBL)
Selective Grinding

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Why to adjust interferences in CR first??
By adjusting the centric
interferences first, you
have the option of
improving cusp-tip
position
Occlusal grinding is more
evenly distributed to both
arches
Eccentric interferences
can be eliminated with
speed and simplicity

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Lateral excursion interferences:
• When lateral excursions are being equilibrated, the mandible must be guided with
firm upward pressure
• Guiding the mandible with firm pressure during excursions will routinely pick up
posterior interferences that are missed with unguided movements

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Protrusive
interferences:
The rule for eliminating protrusive interferences is DUML grind the distal
inclines of the upper or the mesial inclines of the lower.
In grinding protrusive interferences, centric stops must be marked with a
different colored ribbon.

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Occlusal Equilibration
The modification of the occlusal form of the teeth with the intent of equalizing occlusal
stress, producing simultaneous occlusal contacts or harmonizing cuspal relations.
GPT 8

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Equilibration Procedures:
Divided into 4 parts:
1. Reduction of all contacting tooth interferences in centric relation
2. Selective reduction of tooth interferences with lateral excursions
3. Elimination of all posterior tooth structure that interferes with protrusive excursions
4. Harmonization of the anterior guidance

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Verification of Completion
• Clench Test
Clenching the tooth together and squeezing firmly.
Reasons for discomfort :- Incomplete elimination of occlusal interferences on the posterior teeth

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• Occlusal examination
Occlusal contacts can be located by marking them with articulating paper
Mylar strips are also helpful in identifying the presence of occlusal contacts

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Computer Assisted Dynamic Occlusal Analysis
• T- Scan
Developed by Maness
Sensor unit that records occlusal contacts on a thin mylar strip and relays the
information to a computer

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Treatment planning- Confirmative Approach
• Before initiating treatment the clinician must decide whether to provide restorations
within the existing occlusal scheme or to change it
• Confirmative approach is defined as the provision of restorations in harmony with the
existing jaw relationships
• It is the principle of providing a new restoration that does not alter the patients occlusion
• Majority of restorations follow this principle
S J Davies et al, Occlusion: Good occlusal practice in simple restorative dentistry. British Dental Journal (2001) 191, 365-3810

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Technique
– The sequence followed is The ‘EDEC’ Principle
E= Examine and record the pre-existing occlusion
D= Design the restoration
E= Execute the restoration
C= Check the occlusion
The EDEC Principle is useful in relation to :
- Direct Restorations
- Indirect Restorations
S J Davies et al, Occlusion: Good occlusal practice in simple restorative dentistry. British Dental Journal (2001) 191, 365-381

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The EDEC Principle for Direct & Indirect Restorations
1. Examine :
– Examine static and dynamic occlusion
– Mark them preoperatively
– Malpositioned opposing supporting cusps, ridges or fossae may be recountoured in order to achieve
optimal occlusal contacts
– Plunger cusps and over erupted teeth are to be reduced
– In anterior restorations, the scheme of incisal guidance must be examined properly
– Assessment of periodontal condition must be made

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2. Design :
– Visualize the design of cavity
– Existing occlusal marks will either be preserved by being avoided in the preparation, or they will be
involved in the design, but never end preparation margins at these points.
3. Execution :
– Controlled interproximal cutting and care in restoring axial tooth contour to avoid overcontouring is
essential
– Carving of restoration must be harmonious to occlusion and should not produce premature contacts
4. Check :
– Check the occlusion by either reversing the color of paper or foils used pre-operatively and using the
preoperative marks as a refrence

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Occlusal Considerations For Restorative Treatment
• Restorations are influenced by the need to withstand forceful contact with the opposing
teeth
• The restorations should provide contacts on smoothly concave fossae such that the
masticatory forces are directed parallel to the long axis of the tooth
• Occlusal features should be compatible with the patients existing occlusion, especially in
cases of bruxism
• Both in anterior and posterior teeth

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• When restoring Mandibular 1st molar following precautions are to be taken :
 Provide adequate stops on mandibular 2nd molar to prevent distal migration
 The disto-lingual cusp of max 1st molar should contact the mesial marginal ridge of mand 2nd
molar
 The cusp tip should not occlude with the embrasure area of mand 1st and 2nd molar – food
impaction and distal movement

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OCCLUSAL ADJUSTMENTS
Directly Inserted Restorative Materials:
• Eg : Amalgam, Composite
• Should be carved to contact, contour & correct margins
• Check with marking ribbon for deflections in maximum intercuspation, protrusive
and lateral excursions
• Proceed with occlusal adjustments

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OVERCONTOURED RESTORATION – Premature contact in
centric occlusion leading to dis-occlusion of adjacent
teeth.
UNDERCONTOURED RESTORATION – Tipping of adjacent
teeth and supra eruption of opposing teeth.

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CAST RESTORATIONS:
• Occlusal equilibration prior to preparation
• After Fabrication, occlusal adjustments similar to directly inserted restorative materials.
COMPLEX RESTORATIONS:
• Pre operative study models
• Recording centric relation
• Facebow transfer
• Use of semi or fully adjustable articulators
• Boyarsky et al – occlusal refinement of mounted casts before crown fabrication decreases
clinical time

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Stamp Technique (MOOS technique by Maroun-Motawie et al)
• A new method for placing large composite restorations with accurate occlusal topography
• It consists of fabricating an occlusal matrix to impress the occlusal anatomy of posterior
teeth before cavity preparation takes place
• This matrix is then pressed against the final composite increment before curing takes place
• It is suitable in cases where the caries is evident during the clinical examination or routine
radiographic examination of teeth with intact marginal ridges and idea
• It is recommended to clean the occlusal surfaces with manual or ultrasonic devices prior to
the placement of the stamp material in order to eliminate interference and to obtain an
exact copy (Chiodera et al., 2016)

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Case Report 1

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Case Report 2

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Alani, A., & Patel, M. (2014). Clinical issues in occlusion – Part I. Singapore Dental Journal, 35, 31–38.
doi:10.1016/j.sdj.2014.09.00

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Check the MIP before commencement of cavity or tooth preparation
Adjust occlusal interference before restorative work is commenced
Avoid placement of the junction between the restorative materials and tooth surface where the MIP occlusal
contact will be
In the case of PFM crowns, it is important to keep the porcelain-metal junction 2mm from the MIP occlusal
contact It is preferable to place the occlusal contact on the metal and not on porcelain (abrasive)
To avoid chipping of the porcelain, maximum thickness of porcelain should not exceed 2mm
When all-porcelain restorations such as zirconia are considered, the zirconia substructure may be extended
incisally or occlusally to support the ceramic veneer at the incisal edge and the cusp, respectively
When the plan is to use a cantilever bridge, only one tooth is replaced and the pontic should be out of contact in all
excursive mandibular movements

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Conclusion
• Occlusion is fundamental to the practice of dentistry in providing a biologically
functional restoration and for comprehensive patient care
• A dental restoration after being placed in the tooth becomes one of the essential
components of the stomatognathic system. Hence, any restoration (from
intracoronal direct restoration to complex crown and bridge work) must be planned
to conform to the existing occlusal pattern and not to disturb it

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References
• Sturdevant’s Art & Science of Operative Dentistry – 7th Ed – Roberson, Heymann & Swift
• Operative Dentistry- Modern theory and practice – 1st Ed – Marzouk
• Principles and Practice of operative dentistry – 3rd Ed – Charbeneau
• Functional Occlusion – From TMJ to smile Design – Peter. E. Dawson
• Wheeler’s Dental anatomy, Physiology & Occlusion- 8th Ed- Ash and Nelson
• S J Davies et al, Occlusion: Good occlusal practice in simple restorative dentistry. British Dental Journal (2001)
191, 365-381
• CASE REPORT:Year : 2016 | Volume : 19 | Issue : 5 | Page : 490-493,The stamp technique for direct Class II
composite restorations: A case series,Saaid et al
• Glossary of Prosthodontic Terms 5 and 8

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