occlusion

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

2020-2021
Department of Prosthodontics
Department of: HERE
COMPLETE DENTURE OCCLUSION
Balanced Occlusion and Articulation
By: Dr. Monia MN Kandil 4

1- Provide maximum denture stability during functional and parafunctional movements.

2- Help in distribution of the masticatory pressure over the supporting tissues and reduce trauma to the underlying tissues.
4- Psychologically it is more comfortable to the patients.
UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY
Bilateral simultaneous occlusal contact of teeth, anteriorly and posteriorly, in both centric and eccentric positions.
Gliding of the teeth across each other during their movement from one position to another, without any interferences.
3- Increased efficiency of mastication.

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

achieving  Stable and physiologic occlusion. During protrosive excursions
During lateral excursions
It should be at least three-point contact between the teeth on each arch one anterior and 2 posteriors.
There should be working and balancing side contacts, or at least There a minimum of three-point contact between the lower centrals and posterior teeth on each side.
Balanced Occlusion


UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY
Balance in eccentric Occlusion During Protrosive Excursions
If with anatomic teeth arrangements  follow compensating curves. If with non-anatomic teeth, should use, as example:
Tilting the second molar  Using balancing rump  Reverse curve of Wilson   

We talk about lateral extrusion movement of the mandible We should talk about Bennet Movement
UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY
When
It is a complex lateral movement or lateral shift of the mandible resulting from the movements of the condyles along the lateral inclines of the mandibular fossae during lateral jaw movement.
Bennett Movement
The immediate Bennett side-shift which occurs at the beginning of the translation. The progressive Bennett side shift.
The Bennett movement can be studied in detail by “pantographic registration”, which shows that it consists of:

In the immediate Bennett side shift: The condyle moves essentially straight medially as it leaves centric relation at the beginning of the lateral jaw movement. while The progressive Bennett side shift: Creates an angle (the Bennett angle) formed by the sagittal plane and the path of the advancing condyle during lateral mandibular movement as viewed in the horizontal plane
UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY
Bennett Movement & Angle

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

Factors affecting occlusal balance
The condylar guidance The incisal guidance The inclination of plane of occlusion The compensating curve and cusp angle of teeth
A: Inclination of the condylar guidance, B: Prominence of the compensating curve, C: Plane of orientation, D: Height of the cusp, E: Inclination of the incisal guidance.


UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY
Condylar inclination: is the angle formed by the steepness of the articular surface of the temporal bone as related to a horizontal line.
The condylar guidance: refers to the path of the condyle follows in the temporomandibular joint when the mandible moves into protrusive or lateral movements.

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

The shape of the glenoid fossa. The variation of the thickness of the articular disc in its different parts. The relation of the condyle to the disc during movement. The extent of the mandibular protrusion
The inclination of the condylar paths varies in different individuals and from side to side in the same person. It depends upon:
The condyler guidance is the only factor given by the patient.
Can’t be changed

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

It is the path taken by the lower anterior teeth as it move in a protrusive movements against the palatal surface of upper anteriors, till become edge to edge.
A) Anatomically: The angle formed by the intersection of the plane of occlusion and a line within the sagittal plane determined by the incisal edges of the maxillary and mandibular central incisors when the teeth are in maximum intercuspation.
B) On an articulator: That angle formed between the plane of reference and the slope of the anterior guide table, as viewed in the sagittal plane.
Anatomically incisal guidance determination
On articulator incisal guidance determination

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

The incisal guide angle can be controlled when developing a balanced occlusion. With a given amount of vertical or horizontal overlap, the incisal guide angle can be made flatter by increasing the horizontal overlap (over-jet)
A: Steep incisal guidance
B: Medium incisal guidance
C: Zero incisal guidance
B
Inc.G should be either equal to, or less than Condy.G. never be greater than it.
Steep Inc.G. calls for steep cusps, steep Occlu.Plane or Comp.Curve to effect an occlusal balance. This type of occlusion results in harmful inclined planes with their harmful risk to the supporting tissues.
Inc.G. can be set by the dentist according to esthetics and phonetics requirements.


UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY
It is an imaginary plane formed by lines connecting tips of incisor teeth and disto-buccal cusps of the most posterior teeth on each side of arch
Occlusal plane Parallel to interpupillary line.
Occlusal plane Parallel to the ala tragus line.

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

Occl.P. At (a) is the ala-tragus plane obtained from the patient. At (b) is a compromise plane midway between ridges. At (c) is a low plane necessary to favor weak lower ridges
The orientation of the occlusal plane becomes as a fixed factor of occlusion
Any necessary alteration for balancing the occlusion must be made in rarely.


1- Aesthetic base. 2- Functional base (chewing and speech). 3- Physical and mechanical (leverage action and parallelism).
Determination of the occlusal plane:
The Height Of Occlusal Plane Should Be 1-2 Mm. Below The Upper Lip. Anteriorly Is Influenced By: The Length Of The Lip. Ridge Fullness. Ridge Height, The Amount of The Maxillomandibular Space. The Incisal Guide Angle.
UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY
Determination of the occlusal plane


Chewing The height of occlusal plane should be convenient and at a level familiar to the tongue to perform its action easily and stop food escaping to the floor of the mouth.
The occlusal surface of the teeth should be below the greatest convexity of the tongue. This also improves the stability of lower denture.
UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY
Speech: During speech, the tongue pushes against the sides of the teeth to produce a seal for a better pronunciation of words.



1) Leverage action: The nearer the occlusal plane to the basal bone of the jaws, the less the leverage action and the better stability.
UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY
2) Parallellism: The occlusal plane should be parallel to both supporting ridges. In this way the biting forces are vertical on the ridges and there is no tendency for horizontal displacement of the dentures.
Effect of occlusal plane orientation on denture stability
3) Arch form:
Both the width of the occluding surfaces and the contour of the arch form of the occlusion rims should be individually established to simulate the desired arch form of artificial teeth

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

1- Spee’s curve The anatomic curvature of the occlusal alignment of the lower teeth beginning at the tip of the lower cuspid and following the buccal cusps of the natural bicuspids and molars continuing to the anterior border of the ramus
The buccal cusps of the lower posterior teeth are slightly higher than the lingual cusps, and a line drawn through the buccal and lingual cusps of the teeth on the other side forms a lateral curve called the curve of Wilson
2- Wilson’s curve

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

The curve of occlusion in which each cusp and incisal edge of upper and lower teeth of right and left sides touches or conforms to a segment of the surface of a sphere eight inches in diameter, its center in the region of the Glabella
3- Monson’s curve The compensating curve of the artificial occlusion corresponds to a combination of these curves in natural teeth. It is considered one of the more important factors in establishing balanced occlusion

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

It is measured by the angle formed by the mesiobuccal cuspal incline to the horizontal plan when the long axis of the tooth is vertical to the plane
Cusp Angle
Types of posterior teeth:
1- Anatomic teeth
2- Modified or semianatomic tooth
3- Non-anatomic tooth


UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY
Anatomic teeth

Problems with anatomic teeth

1- The presence of cusp inclines can cause trauma, discomfort and instability to the bases because of the horizontal component of force that produced during function.
2- The use of adjustable articulator is mandatory, so various eccentric records must be made for articulator adjustments.
3- Harmonious balanced occlusion is lost when settling occurs, then horizontal force will developed, that acting on thin delicate mucosa and the underlying bone.
4- The bases need frequent relining to keep the occlusion stable and balanced.

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

Non-anatomic tooth
The arrows indicate the direction and the magnitude of the force generated by the two types of teeth as they penetrate the bolus of food during masticatory cycle
Sharp cusped teeth need less vertical force for penetration but produce more lateral force owing to the inclined plane effect. Flat teeth more vertical force but produce less lateral force components.

Problems with non-anatomic tooth: 1- Functionally not efficiently, unless the occlusal surface provides cutting ridges and spillways. 2- They can not be corrected by occlusal grinding without impairing their efficiency. 3- Appear dull and unnatural.
UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

1- The capacity of the ridges 2- Inter-ridge distance 3- The ridge relationship
1- The capacity of the ridges:
Strong well-forme resist horizontal forced
A large interridge distance creates a long lever arm through which horizontal forces created by the inclines of cusps can act. Therefore, this force can be controlled by using flat teeth.
2- Interridge distance
Selection of tooth forms is based on:
Non-anatomic posterior teeth used effectively to control the forces of occlusion and to stabilize the denture base supported by compromised weak ridge in either class II or class III ridge relationship
3- The ridge relationship



All five factors of balance interact with each other, and changes in any one effect changes in the others. for the final analysis, the dentist can only control four of five factors. * The condylar guidance: can be completely fixed and is not be change. * The incisal guidance and inclination of the plane of occlusion: can be altered within a small range according to esthetic and physiologic (phonetic) factors. * Cusps, on the teeth and tooth inclination of cuspless teeth and compensating curve: are the real working tools of balanced occlusion.
UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY
Condylar guidance
Incisal guidance
Occlusal Plane
Cusp Height
More controllable
Compensating curve

020-2021

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY
1- Lever balance
Dependent on tooth position as related to its base
Placing the teeth over the ridge or slightly lingual to it. Denture base area covers as wide area on the ridge as possible. Placing the teeth as close to the ridge as other factors will permit. Using narrow buccolingual teeth width occlusal food table, as much as possible.

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY

Is dependent on tooth contact
"stable simultaneous contact" of the opposing upper and lower teeth in centric relation position with a continuous "smooth bilateral gliding" from this position to any eccentric position within the normal range of mandibular function.
2- Bilateral occlusal balance
Bilateral balance in artificial teeth, is necessary to stabilize the bases.

THE END

UNIVERSITY OF MOSUL COLLEGE OF DENTISTRY
2020-2021