Class III Denture

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Arrangement of Teeth in Class 3 Jaw Relations

Problems associated with class 3 relations…

The condition is characterized by the lower anterior ridge being forward in relation to maxillary ridge that may vary from edge to edge relation OR marked prognathism of mandible.

Class 3 upper and lower jaw relation

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Management of Problems Associated with class 3 Relations

When ridges are edge to edge:

• Incisal edges of upper and lower incisors and cuspids also meet in edge to edge.

• Upper and lower teeth are placed as near as possible to the labial plates of bone in their respective ridges.
• Normal horizontal overlap can be given only if it is possible.

Normal horizontal overlap can be given only if it is possible

• Normal horizontal overlap should not be attempted when ridge relation does not permit-if done then stability of denture will be greatly hampered.
•  Edge to edge relation enhances stability.

Extreme protrusion of the mandible:

•  Negative or reverse horizontal overlap should be used (magnitude depends on degree of  protrusion).

Canine relationship in CLASS 3 cases:

• Relationship – usually does not pose much of a problem.
• Distal surface of lower canine coincides with the tip of the upper canine.
• If it finishes mesial to the canine tip, the discrepancy can be rectified using small spaces between the lower anterior teeth so that the canine will have normal relation.

Distal surface of lower canine coincides with the tip of the upper canine

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Setting  Posterior  Teeth in Class 3 Cases

Arrangement of posterior teeth

• Crest of the lower arch is located further buccally than that part of the upper residual ridge which leads to a problem of developing an adequate occlusal relationship between upper and lower teeth.
• To ensure there is normal occlusal contact with the lower teeth, the upper posterior teeth can be set slightly buccal to the crest of the ridge,  therefore results in a wider arch form.

When the Lower Arch is Too Wide…

• Interchange using upper teeth on the lower denture and lower teeth on the upper denture.
• Interchange is made across the arch as well (e.g. right upper teeth are placed on left lower ridge, left lower teeth are placed on right upper arch).

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