Maxillomandibular Relations

In ideal maxillomandibular relations, the ridges are equivalent in size and anteroposterior position; and the ridge crests are parallel to one another. Commonly however, the anterior crest of the mandibular arch lies to the lingual or facial of the maxillary arch; and the posterior mandibular ridge is to the buccal of the maxillary arch. With residual ridge resorption, the maxillary arch narrows and its most anterior extent moves posteriorly; and the mandibular arch widens as its most anterior extent moves further anteriorly.

Residual Ridge Form

Ideal residual ridge characteristics include:

• Healthy attached keratinized mucosa of even thickness
  
• No bony spicules, sharp ridges or undercuts
  
• No muscle attachments or frena in critical areas; frena attach to the ridge closer to the base than to the crest
  
• No scars or mucosal hypertrophies
  
• Prominent residual bone
  
• Rounded ridge crest
  
• Slightly tapered labial, buccal and lingual sides
  
• Distinct vestibules buccal and facial of both ridges; distinct retromylohyoid vestibule for lower ridge

Examining the Old Prostheses

An examination of the old prostheses, both in and out of the patient’s mouth, yields insights into a patient’s biting, chewing, and hygiene habits as well as information necessary for identifying and incorporating improvements and changes into the new dentures. Assessment of the following factors is important for optimal treatment planning:

• Age and condition of prosthesis
  
• Denture position relative to facial landmarks
  
• Extensions
  
• Interocclusal distance
  
• Occlusal relationships
  
• Occlusal vertical dimension
  
• Retention
  
• Soft tissue support
  
• Stability