When Changing Vertical Dimension of Occlusion (VDO) is Clinically Acceptable

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Occlusion Connections - Center for Orthopedic Advancement

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The Decision Every Restorative Dentist Eventually Faces

Every dentist who does restorative work eventually faces this decision: the patient needs more vertical dimension, but the question of how much — and whether changing it is even appropriate — has no clear answer in standard training.

Most CE programs address VDO in the context of esthetics and crown-to-root ratios. What they don’t address is the neuromuscular and joint-based indications that make VDO changes not just acceptable, but necessary — and the objective measurement discipline that separates a physiologically valid VDO change from an educated guess.

This page addresses when changing vertical dimension of occlusion is clinically appropriate, and what the measurement protocol should look like before any irreversible decision is made.

When vertical dimension between the mandible to maxillary arches is lost.  Shimming up this deficiency would seem to be a reasonable approach using a conservative, removable intra oral appliance, especially if you experience TMD symptoms involving masticatory dysfunctions, pain and joint derangement problems.  Treatment using a Lower Anatomical GNM Orthotic has been found to be an effective alternative diagnostic as well as initial treatment method when clicking, popping, restricted jaw opening problems exist.  Muscle pains may exist in combination with some of these clinical signs and symptoms.

When Is Changing VDO Clinically Acceptable?

Changing vertical dimension of occlusion (VDO) is clinically acceptable when:

  • Condyle/disc entrapment – joint derangement exists (graiting, crepitus likes sounds)
  • Mandible is positioned posteriorly
  • Mal aligned dental arches
  • Poor arch development
  • Lack of tongue space
  • Posterior occlusal collapse
  • Collapsed facial esthetics
  • Cervical dysfunction

Why VDO Is Not Always the Forgiving Dimension It Was Taught to Be

There has in the past been a great deal of emphasis placed on vertical dimension of occlusion (VDO). Vertical dimension of occlusion has been often noted and taught to be a forgiving dimension when considering all 6 dimensions of mandibular freedom, but it is not always so, especially for those of us who understand GNM principles of occlusion.
It is very important to recognize that altering VDO should consider normalized healthy rest vertical dimensions, temporomandibular joint (condyle disc ) entrapment and derangement problems, bite force muscle recruitment abilities, effects of crown to root ratio tooth loading, intra oral tongue space parameters of the oral pharyngeal swallowing mechanism and neuromuscular adaptation ability (wide accommodative vs. narrow accommodative) of each individual.
These factors should all take precedence above and beyond any restorative cosmetic procedures, especially of the patient presents with various musculoskeletal occlusal signs and symptoms.
Although VDO is commonly observed amongst many TMD patients it is often deficient in the occlusally pathologic patient, e.g., the lower one third of the face, upper to lower anterior teeth relationships, orthodontic cephalometric vertical norms and masticatory muscle jaw posturing parameters can help further define those deficiencies with objective evidence based on known normative values.
The principles of altering vertical dimensions (bite opening) should adhere to known parameters of healthy anatomical form for normalized physiologic healthy function. Abnormal VDO’s naturally result in abnormal pathologic function.

Why Standard References Fall Short in Complex TMD Cases

Following standard tooth to width and gingival to gingival references in determining idealized vertical dimensions are not always reliable guides in complex TMD cases since it is recognized amongst experienced TMD clinicians that these kind of vertical dimension values do not always fit those type of cases that fall within the categories of anterior open bite type cases, or cases with vertical maxillary deficiencies, or cases with severely displaced disc/severe restricted mouth opening (joint derangement) problems.

The Measurement Approach That Changes Everything

An astute and trained clinician can determine the physiologic VDO of each and every person even when the above mentioned vertical dimensional challenges exists. Resting EMGs (electromyography) are not a reliable means to determine a physiologic healthy vertical dimension of occlusion for any TMD patient presenting with spastic hypermuscle activity especially in the cervical neck regions. Neither is educated guess work by the treating dentists or the lab sufficient to open up someones VDO to begin any occlusal treatment.

The Most Challenging Dimension — And Why It Matters Most

The antero-posterior relationship as well as the frontal/lateral relationships is the least forgiving and often the most challenging for most clinicians who perform occlusal treatments of complexTMD case involving cervical dysfunction, TMD primary problems, Class II division 2 type problems as well as paining anterior open bite TMD problems.

Continue Learning

🔹 When VDO Treatment Is Indicated

🔹 Treatment Protocols and Appliance Considerations

🔹 The Measurement That Guides the Decision

🔹 The Intellectual Foundation

🔹 Ready to Train

Written by Clayton A. Chan, D.D.S. — Founder and Director, Occlusion Connections | Las Vegas, Nevada

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