It isn’t unusual for clinicians to regularly see patients who have clinical failures or complications related to poor occlusion. Complications can cause pain, compromise masticatory function and affect patients’ phonetics and appearance.
Occlusal problems develop for a variety of reasons. Teeth can suffer a certain amount of wear and tear due to functional activity, such as normal attrition and erosion, and abrasion. Parafunctional habits like bruxism, gastric reflux, diet, methamphetamine abuse and eating disorders all contribute to excessive occlusal wear. Excessively worn anterior teeth have a detrimental effect on aesthetics and occlusal harmony. Diminished vertical occlusal dimensions often age facial appearance due to the decrease in the lower third of the face. Loss of vertical dimension can also affect the temporomandibular joint and masticatory muscles.
An essential part of occlusal rehabilitation is to re-establish the correct occlusal vertical dimension. This dimension is defined by the vertical distance between the mandible and the maxilla while the occlusal surfaces are in contact. Any restorative treatment aims to provide good posterior occlusal contacts, stabilizing the occlusion and providing anterior guidance. This ensures a predictable amount of disocclusion during lateral and protrusive excursions, and provides harmony between the stomatognathic system and the structures used for speech and for chewing and swallowing food. Fundamental knowledge about the structures of the stomatognathic system is crucial for fully restoring occlusion for optimal functioning. A harmonious occlusion significantly improves the longevity and function of natural teeth and dental prostheses.
One of the first things to assess is patient expectations for occlusion rehabilitation.
Most patients’ expectations fall into one or more of four categories: comfort, function, aesthetics, and quality of life. Your discussions with the patient should determine which factors are most important to them. Questions to ask include:
Understanding and managing these expectations is crucial for patient satisfaction. Carefully evaluate how the patient reacts and adapts their expectations once they are aware of what can and cannot be achieved.
Defining the ideal occlusion is tricky, because it can only be described relatively broadly in terms of function and form. Points to consider include:
The anterior teeth support the lips, which, in turn, frame the teeth. The shape of the lips, the dimension of the oral opening, the visibility of supporting teeth, and the health of the gingival tissue all influence the lip line. Evaluate the lip line while the patient is smiling, as this increases the width of the mouth by a quarter or a third compared to when the lips are at rest. Usually, younger patients will show more tooth structure than older patients. Patients with large smiles can also display an excess of gingival tissue, which can make planning anterior restorations challenging. Generally, patients with smaller smiles and longer upper lips are less challenging to restore, since fewer teeth are shown when smiling.
After completing a clinical examination, take impressions and manufacture models that reproduce the patient’s current occlusion in order to properly assess the patient’s vertical dimension of occlusion (VDO). One way to evaluate the patient’s VDO is by using a bite gauge to establish the discrepancy in the vertical dimension, which can then be recorded using bite registration material. You can also verify the discrepancy using facial muscle relaxation to establish the patient’s physiologic rest position. The rest position, also called freeway space, is defined as the vertical space between the occlusal surface of the mandibular and maxillary teeth. The average freeway space is 2 to 3 mm.
Phonetic and aesthetic assessments can help you select the correct VDO. When testing the patient’s phonetics, place emphasis on their ability to pronounce sibilant sounds “Ch,” “S,” and “J” repeatedly and accurately, because these are good indicators of the average speaking space. If the patient makes a clicking sound while contacting the anterior teeth, the VDO might be too big. When the distance between sounds is too big, the VDO is most likely too short. If the patient currently wears a denture, modifying it with treatment liners can be helpful in establishing an optimal VDO.
Use the bite registration and models to make temporary splints that attach to the occlusal surfaces of the teeth, re-establishing the correct VDO. Using provisional restorations allows the patient to adjust to the new vertical dimensions more easily, which also helps to stabilize the occlusion. Then, you can assess the patient for comfortable chewing, swallowing, and speaking and for any temporomandibular discomfort. Permanent dental restorations can be fabricated with the appropriate increase in VDO, which should be distributed evenly over the two arches to produce a more aesthetic appearance. The final outcome of treatment should restore occlusion dimensions and aesthetics and be comfortable and pain-free.
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References
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2994694/
https://medcraveonline.com/JDHODT/JDHODT-09-00336.pdf
