Problem Denture Design

Question 1

Why would survey lines be modified and how can this be done?

Answer 1

• unfavourable survey lines can be modified to make them more favourable for clasping
• addition of composite
  
  • straight forward
  • composite added buccally
  • minimally invasive
• crowns
  
  • more destructive to tooth tissue
  • consider if tooth needs crowned

Question 2

What are precision attachments?

Answer 2

• components to increase retention of partial dentures
• rarely used
  • path of insertion must be the same
    
    • if multiple used in same arch
  • technically difficult
    
    • challenging to repair and replace

Question 3

What are two part dentures and when might they be used?

Answer 3

• dentures with one part CoCr and one part acrylic which attach together following two different paths of insertion
  
  • split pins on CoCr
  • teeth and flange fit onto split pins
• useful when gross tissue loss has occurred
  
  • advanced localised periodontitis

Question 4

What are swing lock dentures and when might they be used?

Answer 4

• denture composed of lingual plate, hinge and lock and gingival flange
  
  • engages bone and tissue undercuts
  • increased retention
  • patient locks denture
  • acrylic engages undercuts to retain denture
• used for Kennedy Class I (rarely II)
  
  • not commonly used
  • good oral hygiene essential
    
    • quantity of acrylic
    • gingival coverage
    • poor for periodontal health and caries

Question 5

What adjustments can be made to dentures when teeth have a lingual tilt?

Answer 5

• traditional lower connectors are not suitable
  
  • buccal bar instead

Question 6

What adjustments can be made for dentures for bruxists?

Answer 6

• important to note that bruxism does not stop once teeth are lost and dentures are worn through very quickly
• metal backing to teeth/metal occlusal surface
  
  • must be certain of tooth position
  • poor aesthetics anteriorly
• CoCr reduces fracture rate
  
  • acrylic prone to fracture
    
    • especially midline
  • weak point between CoCr and acrylic
  • CoCr in acrylic
    
    • maintains peripheral seal and post dam
• cross-linked teeth
  
  • better wear resistance and longevity
  • more expensive