20.occlusal schemes monoplane-neutrocentric concept

20. Occlusal Schemes - Monoplane 20. Occlusal Schemes - Monoplane Neutrocentric ConceptNeutrocentric Concept

John Beumer III, DDS, MSJohn Beumer III, DDS, MSandand

Michael Hamada DDSMichael Hamada DDSDivision of Advanced Prosthodontics, Division of Advanced Prosthodontics, Biomaterials and Hospital DentistryBiomaterials and Hospital Dentistry

UCLA School of DentistryUCLA School of Dentistry

This program of instruction is protected by copyright ©. No portion of This program of instruction is protected by copyright ©. No portion of this program of instruction may be reproduced, recorded or transferred this program of instruction may be reproduced, recorded or transferred by any means electronic, digital, photographic, mechanical etc., or by by any means electronic, digital, photographic, mechanical etc., or by any information storage or retrieval system, without prior permission.any information storage or retrieval system, without prior permission.

Monoplane Occlusion – Neutrocentric ConceptMonoplane Occlusion – Neutrocentric Concept

This concept of occlusion assumes that the anterior-posterior plane of occlusion should be parallel to the denture foundation area and not dictated by condylar inclination.

The plane of occlusion is completely flat and level. There is no curve of Wilson or Curve of Spee (compensating curve) incorporated into the set up.

There is no vertical overlap of the anterior teeth.

When using this concept of occlusion the patient is instructed not to incise the bolus. With this tooth arrangement DeVan noted that “the patient will become a chopper, not a chewer or a grinder.”

When setting these teeth the horizontal and lateral condylar guidances should be set at zero.

Background


Begin by positioning a zero degree protrusive insert, and check Begin by positioning a zero degree protrusive insert, and check to ensure that the incisal guide pin is set at zero and in contact to ensure that the incisal guide pin is set at zero and in contact with the incisal guide table.with the incisal guide table.

Protrusive insertsProtrusive inserts

Protrusive Protrusive insertinsert

Zero setting

Mark the casts indicating midline, crest of the ridge, and the retromolar pad. These landmarks will be used to check your denture setup.

MaxillaMidlineAnterior land

MandibleRidgeRetromolar pad

Cast LandmarksCast Landmarks

Anterior land

Cast Landmarks - MaxillaCast Landmarks - Maxilla

Midline

Incisive papilla

Lines indicating the crest of the ridge

Cast Landmarks -MandibleCast Landmarks -MandibleMidpoint of

retromolar pad

Land Mark on land indicating the midpoint of the retromolar pad

As previously mentioned (13c, 1a), the wax rim is ideally contoured on the patient and used to As previously mentioned (13c, 1a), the wax rim is ideally contoured on the patient and used to mount the upper cast with a facebow transfer record. When the lower cast is mounted on the mount the upper cast with a facebow transfer record. When the lower cast is mounted on the articulator with a centric relation record, the plane of occlusion is readily seen.articulator with a centric relation record, the plane of occlusion is readily seen.

The three landmarks used to identify the plane of occlusion are:The midpoint of the retromolar pads bilaterally as previously marked on the mandibular cast.The incisal edge of the maxillary central incisors

Setting the Maxillary Anterior TeethSetting the Maxillary Anterior Teeth

Midpoint of Midpoint of retromolar retromolar

padpad

Midpoint of Midpoint of retromolar retromolar

padpad

To set the remaining maxillary anterior teeth a clear glass or plastic slab is positioned on the mandibular record base to represent the plane of occlusion.

Setting the Maxillary Anterior TeethSetting the Maxillary Anterior TeethMark indicating midpoint of the retromolar pad


Soften some baseplate wax and attach some to the ridge lap portion of the other maxillary central incisor and attach it to the record base as shown. Set the lateral incisors and cuspids as shown previously (Section 13c, 1a Lingualized occlusion).


Note the angulations of the anterior teeth in relation to the occlusal plane when viewed in profile.

Occlusal Occlusal planeplane

Setting the Maxillary Anterior TeethSetting the Maxillary Anterior Teeth““Toed-in” PositionToed-in” Position

Note how the cervical and incisal edges of the cuspid are aligned vertically (yellow line). The facial surface of the cuspid however, is canted inward and appears “toed in” (red line) due to the prominence of the cervical area of the tooth (yellow arrow). The centrals and laterals are inclined slightly towards the distal.

Setting Mandibular Anterior TeethSetting Mandibular Anterior Teeth

Amount of vertical overlap

When using a neutrocentric concept of occlusion is no vertical overlap should be incorporated into the set up.

Magnitude of horizontal overlap?

Setting Mandibular Anterior TeethSetting Mandibular Anterior Teeth

In Class II patients the mandible tends to travel farther anteriorly in function than the typical Class I patient and consequently more horizontal overlap is necessary to allow for this functional movement.

In contrast Class III patients often demonstrate little or no anterior movement of the mandible during function. Consequently, little or no horizontal overlap is developed in the set up.

Class IClass I Class IIClass II

Class IIIClass III

Setting the Mandibular Anterior TeethSetting the Mandibular Anterior Teeth

The horizontal overlap should be consistent throughout the anterior region. In this setup it is about 1.5 mm.

Setting the Mandibular Anterior TeethSetting the Mandibular Anterior Teeth

Positions of the anterior teeth. The lateral incisors should be placed similar in angulation and position to the central incisors. Note that the cuspids are towed out at the cervical.

Monoplane Occlusion – Neutrocentric ConceptMonoplane Occlusion – Neutrocentric ConceptBackground - Setting the posterior teeth

When setting these teeth the horizontal and lateral condylar guidances should be set at zero. The number and combination of the denture teeth utilized varies depending on the arch length of the patient.

The mandibular occlusal table should end prior to the ascending ramus.

The distal surface of most posterior maxillary denture tooth should extend one half 1-2mm distal to the most posterior mandibular denture teeth.


Position the posterior mandibular posterior teeth over the crest of the ridge. Check to ensure they are set to a flat plane and on the plane of occlusion.

Make corrections as necessary

Occlusal Occlusal PlanePlane Since there is no vertical

overlap of the anterior teeth all of the mandibular teeth are on the plane of occlusion.


Since there is no vertical overlap of the anterior teeth both the anterior teeth and the posterior teeth are on the plane of occlusion.

Make corrections as necessary.

Monoplane Concept – Neutrocentric ConceptMonoplane Concept – Neutrocentric Concept

Position the maxillary posterior teeth.


Check the horizontal overlap of the posterior teeth. The overlap should be at least one third of the width of the occlusal surface and be sufficient to prevent biting of the cheek and corner of the mouth.

Horizontal overlap


Note that the premolar in the of the Ivoclar Orthoplane tooth form is of sufficient Note that the premolar in the of the Ivoclar Orthoplane tooth form is of sufficient length to harmonize with the cuspid. In addition the the marginal ridges of the length to harmonize with the cuspid. In addition the the marginal ridges of the premolars have been lowered. This change provides the esthetics usually premolars have been lowered. This change provides the esthetics usually associated with anatomic teeth.associated with anatomic teeth.


The flatness of the maxillary premolars is provided by the flat buccal and lingual cusps. Note that in this set up both lingual and buccal cusps contact the plane of occlusion.

Monoplane Occlusion –Neutrocentric ConceptMonoplane Occlusion –Neutrocentric Concept

With this occlusal scheme the plane of occlusion should be parallel to the denture foundation area.

Monoplane Occlusion –Neutrocentric ConceptMonoplane Occlusion –Neutrocentric Concept

Verify again that all the maxillary teeth, with the exception of the lateral incisors and perhaps the cuspids, are on the plane of occlusion. Make corrections by manipulating the maxillary teeth. When you have completed this step, thoroughly cool the wax before proceeding to the next step.


Reestablish centric contactsReestablish centric contacts as necessary by manipulating as necessary by manipulating the mandibular posterior the mandibular posterior teeth. Make sure that the teeth. Make sure that the incisal guide pin maintains incisal guide pin maintains contact with the incisal guide contact with the incisal guide table when you have table when you have completed this step.completed this step. While While performing this step make performing this step make sure you do not alter the sure you do not alter the horizontal overlap of the horizontal overlap of the posterior teeth.posterior teeth.

Monoplane Occlusion- Neutrocentric ConceptMonoplane Occlusion- Neutrocentric Concept

Note Christiansen’s Note Christiansen’s phenomenon, or the phenomenon, or the separation between the separation between the posterior teeth in the posterior teeth in the protrusive position. If the protrusive position. If the patient presents with patient presents with steep condylar steep condylar inclination the posterior inclination the posterior discrepancy in excursion discrepancy in excursion may become significant.may become significant.

20 degrees20 degrees

30 degrees30 degrees

Monoplane Occlusion- Neutrocentric ConceptMonoplane Occlusion- Neutrocentric Concept

The steeper the The steeper the condylar inclination condylar inclination the greater the the greater the posterior discrepancy posterior discrepancy in excursion and the in excursion and the greater the need for greater the need for balancing ramps, and balancing ramps, and so in this patient, so in this patient, balancing ramps were balancing ramps were added to improve the added to improve the stability of the lower stability of the lower denture.denture.

20.occlusal schemes monoplane-neutrocentric concept

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