Complete Dentures – Occlusal Schemes – Monoplane: Neutrocentric

Several clinicians have employed monoplane posterior teeth with all the anterior and posterior teeth on the same flat plane.  There is no vertical overlap of the anterior teeth with this occlusal scheme although the lateral incisors may be elevated to enhance the esthetic display.  This program describes and illustrates this philosophy of complete denture occlusion.



Complete Dentures – Occlusal Schemes Monoplane-Neutrocentric Concept — Course Transcript

  • 1. Occlusal Schemes – Monoplane Neutrocentric Concept John Beumer III, DDS, MS and Michael Hamada DDS Division of Advanced Prosthodontics UCLA School of DentistryThis program of instruction is protected by copyright ©. No portion of thisprogram of instruction may be reproduced, recorded or transferred by anymeans electronic, digital, photographic, mechanical etc., or by anyinformation storage or retrieval system, without prior permission.
  • 2. Monoplane Occlusion – Neutrocentric Concept BackgroundThis concept of occlusion assumes that the anterior-posterior plane ofocclusion should be parallel to the denture foundation area and not dictatedby condylar inclination.The plane of occlusion is completely flat and level. There is no curve ofWilson 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 incisethe bolus. With this tooth arrangement DeVan noted that “the patient willbecome a chopper, not a chewer or a grinder.”When setting these teeth the horizontal and lateral condylar guidancesshould be set at zero.
  • 3. Monoplane Occlusion – Neutrocentric Concept Zero setting Protrusive inserts Protrusive insertBegin by positioning a zero degree protrusive insert, and checkto ensure that the incisal guide pin is set at zero and in contactwith the incisal guide table.
  • 4. Cast LandmarksMark the casts indicating midline, crest of the ridge, and theretromolar pad. These landmarks will be used to check yourdenture setup. Maxilla Mandible Midline Ridge Anterior land Retromolar pad
  • 5. Cast Landmarks – Maxilla Anterior landIncisivepapilla Midline
  • 6. Cast Landmarks -Mandible Midpoint of retromolar pad Mark on landLand indicating the midpoint of the Lines indicating the retromolar pad crest of the ridge
  • 7. Setting the Maxillary Anterior Teeth As previously mentioned (13c, 1a), the wax rim is ideally contoured on the patient and used to mount the upper cast with a facebow transferMidpoint of Midpoint ofretromolar retromolar pad pad 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
  • 8. Setting the Maxillary Anterior Teeth Mark indicating midpoint of the retromolar pad 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.
  • 9. Setting the Maxillary Anterior TeethSoften some baseplate wax and attach some to the ridge lapportion of the other maxillary central incisor and attach it tothe record base as shown. Set the lateral incisors andcuspids as shown previously (Section 13c, 1a Lingualizedocclusion).
  • 10. Setting the Maxillary Anterior Teeth Occlusal planeNote the angulations of the anterior teeth in relation to theocclusal plane when viewed in profile.
  • 11. Setting the Maxillary Anterior Teeth “Toed-in” PositionNote how the cervical and incisal edges of the cuspid are alignedvertically (yellow line). The facial surface of the cuspid however, iscanted inward and appears “toed in” (red line) due to the prominence ofthe cervical area of the tooth (yellow arrow). The centrals and lateralsare inclined slightly towards the distal.
  • 12. Setting Mandibular Anterior TeethAmount of vertical overlapWhen using a neutrocentric concept of occlusion is novertical overlap should be incorporated into the set up.
  • 13. Setting Mandibular Anterior TeethMagnitude of horizontal overlap? In Class II patients the mandible tends to travel farther anteriorly in function than the typical Class I patient and Class I Class II consequently more horizontal 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 III
  • 14. Setting the Mandibular Anterior TeethThe horizontal overlap should be consistent throughout theanterior region. In this setup it is about 1.5 mm.
  • 15. Setting the Mandibular Anterior TeethPositions of the anterior teeth. The lateral incisors shouldbe placed similar in angulation and position to the centralincisors. Note that the cuspids are towed out at thecervical.
  • 16. Monoplane Occlusion – Neutrocentric Concept Background – Setting the posterior teeth
  • 17. Monoplane Occlusion – Neutrocentric Conceptl 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.l Make corrections as necessary Occlusal Plane Since there is no vertical overlap of the anterior teeth all of the mandibular teeth are on the plane of occlusion.
  • 18. Monoplane Occlusion – Neutrocentric Conceptl 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.
  • 19. Monoplane Concept – Neutrocentric Concept l Position the maxillary posterior teeth.
  • 20. Monoplane Occlusion – Neutrocentric Conceptl 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
  • 21. Monoplane Occlusion – Neutrocentric Concept l Note that the premolar in the of the Ivoclar Orthoplane tooth form is of sufficient length to harmonize with the cuspid. In addition the
  • 22. Monoplane Occlusion – Neutrocentric Concept 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.
  • 23. Monoplane Occlusion –Neutrocentric Conceptl With this occlusal scheme the plane of occlusion should be parallel to the denture foundation area.
  • 24. Monoplane Occlusion –Neutrocentric Conceptl 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.
  • 25. Monoplane Occlusion – Neutrocentric Concept l Reestablish centric contacts as necessary by manipulating the mandibular posterior teeth. Make sure that the incisal guide pin maintains contact with the incisal guide table when you have completed this step. While performing this step make sure you do not alter the horizontal overlap of the posterior teeth.
  • 26. Monoplane Occlusion- Neutrocentric Concept l Note Christiansen’s phenomenon, or the separation between the posterior teeth in the 20 degrees protrusive position. If the patient presents with steep condylar inclination the posterior discrepancy in excursion may become significant. 30 degrees
  • 27. Monoplane Occlusion- Neutrocentric Concept l The steeper the condylar inclination the greater the posterior discrepancy in excursion and the greater the need for balancing ramps, and so in this patient, balancing ramps were added to improve the stability of the lower denture.
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