Occlusal conceptsOcclusal concepts

• Balanced occlusionBalanced occlusion

• Group function Group function occlusion occlusion

• Canine protected Canine protected occlusionocclusion

• Mutually protected Mutually protected occlusionocclusion

• Theoretically ideal occlusion

• Physiologic occlusion

• Nonphysiologic occlusion

• Malocclusion

• Therapeutic occlusion

Ballanced occlusionBallanced occlusion

Bonwill:”Geometric and mechanical laws of Bonwill:”Geometric and mechanical laws of articulation”articulation”

Geometric ideal: bringing into contact the largest amount of grinding surface

Centrally located static hinge

1850.

Spee’s concept:Spee’s concept:””grinding millstones”grinding millstones”

The horizontal axis of the cylinder’s curvature pass through the midline of the medial surface of the orbit, behind the lacrimal duct

1890.1890.

Alfred Gysi 1910.Alfred Gysi 1910.

• Belived that the mandibular movement depends on– The condylar inclination

– The incisal inclination

• Proposed the bilaterally ballanced occlusion in dentures

Monson’s spherical theoryMonson’s spherical theory

His conclusion produced the 10 cm radius sphere, a geometric embodiment of the function, form and beauty of the masticatory system

Bilaterally balanced occlusionBilaterally balanced occlusion• CO-ICP: coincides with CR-RCP

– Point centric or freedom in centric• Protrusion

– Anterior teeth contact– Posterior teeth: contact, -protrusive

ballance• Lateral excursion

– Working side: maxillary buccal and mandibular lower cusps contact, maxillary lingual nad mandibular lingual cusps contact (cross tooth ballance)

– Ballancing side: maxillary lingual and mandibular buccal cusp contact (cross arch ballance)

””Gnathological” Society Gnathological” Society of California (McCollum of California (McCollum

1939.)1939.)

• ”ideal nature of the relationship between the condyle and fossa” – anatomical and functional ideal

• Articulator could absolutely duplicate jaw relations

• Hinge axis locator- kinematic face-bow– Modified Snow face-bow

• ‘Ballanced’ was the ideal type

Functionalists (Schuyler Functionalists (Schuyler 1929.)1929.)

• ”Such arrangements of teeth as will provide the highest efficiency during all excursions of the mandible which are necessary to the function of mastication”

• Ballanced suitable only to mucosa born dentures

• Ballanced is traumatic and extremely undesirable (1961)

Canine guidance (D’Amico 1961.)Canine guidance (D’Amico 1961.)• CO-ICP: coincides with CR-RCP

– Point centric or freedom in centric

• Protrusion

– Anterior teeth contact

– Posterior teeth:gap (sagittal Chistensen’s phenomenon)

• Lateral excursion

– Working side: maxillary and Working side: maxillary and mandibular canines contactmandibular canines contact

– Ballancing side:gap (transversal Christensen’s phenomenon)

Group function (Schuyler 1961.)Group function (Schuyler 1961.)• ICP: may coincide with CR-RCP

– Point centric or freedom in centric

• Protrusion

– Anterior teeth contact

– Posterior teeth:gap (sagittal Chistensen’s phenomenon)

• Lateral excursion

– Working side: maxillary Working side: maxillary buccal and mandibular lower buccal and mandibular lower cusps contact cusps contact

– Ballancing side:gap (transversal Christensen’s phenomenon)

Mutually protected occlusion (organized Mutually protected occlusion (organized disclusion, Butler and Zander 1968)disclusion, Butler and Zander 1968)

• CO-ICP: may coincide with CR-RCP– Anterior teeth contact very lightly– Point centric or freedom in centric

• Protrusion– Anterior teeth contact, incisal

guidance is steep enough to produce– Posterior disclusion (sagittal

Chistensen’s phenomenon)

• Lateral excursion– Working side: maxillary buccal Working side: maxillary buccal

and mandibular lower cusps and mandibular lower cusps contact contact

– Ballancing side: disclusion (transversal Christensen’s phenomenon)

Theoretically ideal occlusionTheoretically ideal occlusion• 1. All components of the

masticatory system are present• 2. „Classical” anatomical

ralationships exist among all maxillary and mandibular teeth

• 3. In ICP the supporting cusps of all posterior teeth occlude with marginal ridges, except for the distobuccal cusps of mandibular and the mesiolingual cusps of the maxillary molars, which occlude withcentral fossae of opposing teeth

• 4.The dentition is in harmony with its basal bone and with other craniofacial structures

• 5.The long axes of teeth are aligned so that functional occlusal forces act through, or close to these axes.

• 6.The periodontium is intact and there is no clinically detectable fremitusor tooth mobility

• 7. The occlusion is stable – teeth do not migrate- just slow physiological compensatory movements

• 8. The teeth do not exhibit attritional wear beyond what would be expected for the age of the individual

• 9. The muscular contact position is coincidentt with ICP

• 10. ICP is in harmony with CR (coincident, or a maximum of 1mm difference in the midsagittal plane

• 11. During protrusion the posterior teeth disclude

• 12. During lateral movements the teeth on the nonworking side disclude

• 13. During lateral movements there is occlusal contact between the opposing canines on the working side, either alone or together with one or more adjacent posterior teeth

• 14. Postural rest position provides an adequate interocclusal distance

• 15. All masticatory, deglution speech, articulation, esthetic and respiratory requirements are met and are satisfactory to the patient

• 16. Tonic activity of the masticatory muscles can be reduced to low levels at times of repose

• 17. Minimal parafunctional activity • 18. Self-perpetuating structural and

functional adaptation to aging and to altered conditions

• 19. Multidirectional masticatory function can be accomplished satisfactorily with a wide variety of food

• 20. No signs or symptoms of pain or dysfunction from any component of the masticatory system can be detected

• 21. The patient has an aura of unawareness of the occlussion and masticatory system

Theoretically ideal occlusionTheoretically ideal occlusion

Physiologic occlusionPhysiologic occlusion• Usually found in adults, deviates in one or

more ways from the theoretically ideal yet is well adapted to its particular environment, is esthetically satisfactory to the patient, and has no pathological manifestations or dysfunctional problems.

• It represents a state of harmony, and does not require therapeutic intervention.

Nonphysiologic occlusionNonphysiologic occlusion

• Is one in which there are signs or symptoms of pathology, dysfunction, or inadequate adaptation of one or more components of the masticatory system that can be contributed to faulty structural relationships or to mandibular functional or parafunctional activity.

• Also includes patient nonacceptance of occlusally related esthetics, speech articulation, or masticatory function parameters.

Nonphysiologic occlusionNonphysiologic occlusion Periodontal conditions attributable Periodontal conditions attributable

to functional loadingto functional loading• Primary occlusal trauma

– In the presence of an intact periodontium, fremitus or mobility may be ordinarily caused by occlusal trauma

• Secondary occlusal trauma– Teeth may be loose because of previous periodontitis

that has destroyed a significant amount of the supporting apparatus. Under these conditions, even normal functional forces may keep these teeth mobile.

Nonphysiologic occlusionNonphysiologic occlusion Pathological conditions of the teeth due to Pathological conditions of the teeth due to mandibular functional or parafunctional mandibular functional or parafunctional

activityactivity• Conditions attributed to excessive occlusal

loading are:– Root resorption

– Cemental tears

– Tooth fracture

– Pericementitis

– Pulpal hyperemia

– Pulpitis

– Excessive or retrograde attrition of teeth

Nonphysiologic occlusionNonphysiologic occlusion Temporomandibular disordersTemporomandibular disorders

• Pain, tenderness, in one or more muscles of mastivcation, restricted mandibular movement, and/or joint sounds.

• Occlusal relationship may not necessarily be an etiologic factor

Therapeutic occlusionTherapeutic occlusion• Is one that has been modified by appropriate

therapeutic modalities in order to change a nonphysiologic occlusion to one that, at the least, falls within the parameters of a physiologic occlusion, if not theoretically ideal.

• Optimizing health and adaptation potential of the masticatory system. Non-natural structural modifications allowed:– Freedom in centric

– Cusp-to-fossae occlusal relationship