Setting Posterior Teeth Set for Function Philosophies of

Setting Posterior Teeth Set for Function

Philosophies of Denture Occlusion s Many philosophies of arranging denture occlusion s No definitive scientific studies prove one occlusal scheme clearly superior

Rationale for Dalhousie Approach s Principles to choose an occlusal scheme s Based on clinical experience s Dalhousie: two occlusal schemes : • Lingualized Occlusion • Monoplane Occlusion

Occlusal Schemes Attempts to Stabilize Dentures s Lingualized Occlusion: Contacts on centered on mandibular ridge minimizes movement s Monoplane Occlusion: Lack of cusps minimizes lateral forces on denture

Lingualized Occlusal Scheme s Centric contacts: s Maxillary lingual cusp to central fossa / marginal ridge Based on the UCLA/IVOCLAR/ACP Series

Appearance s Anatomic teeth used in maxilla s Better esthetics than Monoplane s Shallow cusped mandibular teeth s Forces centered over mandibular ridge

Lingualized Occlusion s No anterior vertical overlap (overbite) s May or may not have balancing contacts in excursions s Anterior teeth - must make at least grazing contacts in excursions

Lingualized Occlusion s Maxillary anatomic - 33° s Mandibular Teeth s If Steep Condylar Guidance s Shallow cusped, e. g. Anatoline - 10° s If Shallow Condylar Guidance s Non-anatomic, e. g. Portrait - 0°)

Denture Occlusion Options Semi-anatomic Non-anatomic (balancing ramp) Lingualized (lingual contact) Anatomic Nonanatomic

Occlusal plane Set mandibular premolars & 1 st molar : • Level with occl plane • Centered over ridge Line indicating the crest of the ridge

Balanced Lingualized Occlusion s In centric - simultaneous bilateral posterior contacts (maxillary lingual cusp) s In excursions - bilateral contacts of posterior (max. ling. cusp) & anterior teeth so denture does not displace/tip

Mandibular Tooth Form s If using a lingualized posterior tooth form (Dentsply Anatoline) • little or no Curve of Wilson • lingual and buccal cusps of level with plane of occlusion

15 degrees Second molar elevated by ~ 15° from the occlusal plane

Max. lingual cusps contact central fossae/marginal ridge ~ 1 mm space between buccal cusps

Maxillary lingual cusps firmly contact bilaterally simultaneously

Centric Position Verify centric No max. buccal cusp contacts in: • Centric • Lateral excursions

Working Excursions Verify excursive contacts Anterior teeth are in contact during excursions

Balancing Excursions Note the balancing contacts

Effect of Mandible Moving Downward During Excursions

Effect of Condylar Guidance As angle gets steeper, more separation of posterior teeth in excursions

Maintaining Balancing Contacts s Change occlusal plane angle s Increase compensating curves s Increase cusp angles

Achieving Balance • Condylar angulation s Recorded with protrusive record • Cusp angle s Selected by dentist

Achieving Balance • Occlusal Plane s Determined by dentist with wax rims • Curve of Spee & Curve of Wilson s Controlled by inclination of teeth

Checking for Balance Feels Smooooooth in excursions - Fingers on Maxillary Canines - On Articulator

Assessing Balance • Jumps or bumps are due to cusp tips moving over other cusp tips, inclines, marginal ridges

Occlusal Refinement Occlusal Adjustment, Selective Grinding s Set teeth as close to: s Maximum intercuspation s Balance s All setups will need some adjustment

‘IIF’ Rule IIF you have contacts on the Inner Inclines of Functional cusps they are balancing contacts

Rules for Balancing Contacts s Balancing contacts should be lines, not points s Balancing contacts should never be heavier than working

Find the Balancing Contact

Find the Balancing Contact

What type of Contact?

What type of Contact?

What type of Contacts?

What type of Contact?

Assess Contacts s Centric Stops s Excursions

Non-Balanced Lingualized Occlusion Maxillary anatomic opposing mandibular non-anatomic

Mortar & pestle occlusion without maxillary buccal cusp contact

Lack of mandibular cusp angles and no attempt to balance the occlusion

No compensating curves No overbite

No overbite

Magnitude of Horizontal Overlap (Overjet) Class I More for Class II patients Class II

Magnitude of Horizontal Overlap Class III patients Little or no overjet

A-P Length of Posterior Teeth • Teeth should end prior to ascending portion of ramus

• Maxillary lingual cusps contact central groove/marginal ridge of the opposing teeth

The horizontal overlap prevents biting of cheek & lips Horizontal overlap

• All maxillary teeth, with exception of lateral incisors and cuspids, should be on the plane of occlusion

Monoplane Occlusion

Monoplane Scheme s Cuspless teeth (0°) on flat plane s 1. 5 -2 mm overjet s No cusp to fossa relationship s No anterior contacts in centric position

Monoplane Philosophy s Eliminate cusps s lateral forces reduced s improves stability s Simplifies tooth arrangement

Monoplane Anterior Setup s No overbite (would cause tilting) s Overjet of 2 mm is used to create an illusion of overbite

Monoplane Excursive Contacts s Excursions - may or may not contact on balancing sides s Depends on condylar inclination & other aspects of tooth arrangement

Maintaining Stability s Anterior teeth make contact in excursions s Modifications have been proposed to minimize the tilting potential: s Balancing ramps s Compensating curves

Monoplane Excursive Contacts without condylar influence

Monoplane Occlusion

As mandible moves laterally (L) or protrusively (P) condyle(s) translate forward separating teeth on one (L) or both sides (P)

Monoplane Advantages • Technically easier to set • Minimizes lateral forces • Use when: – Difficulty obtaining repeatable centric records (muscle incoordination) – Skeletal malocclusion (Class II, III) – Severe residual ridge resorption

Monoplane Disadvantages • Poorer appearance • Can be unstable if condylar guidance is steep (posterior teeth separate, leaving only the anteriors in contact)

Monoplane Occlusion s Always take a protrusive record prior to setting teeth – need to know protrusive angle to select teeth s At delivery, clinical remount on an articulator s Practice doing a clinical remount

Adjusting Monoplane Occlusion s Main adjustment is flat s If heavy prematurity near fossa, slightly shallow fossa

Videos s Setting Mandibular Posterior Teeth s Setting Maxillary Posterior Teeth s View outside of Class: s Principles for Centric Contacts Lingualized Occlusion