Overdentures

Question 1

Overdentures

Answer 1

• removable denture prosthesis
  
  • covers & rests on ≥1 natural teeth, roots, or implants
• Attachments
  
  • provides the fixation, retention, and stabilize the prosthesis
  • on teeth, roots or implants

Question 2

Tooth Supported Overdenture: Advantages vs disadvantages

Answer 2

• Advantages:
  
  • Preserve:
    
    • alveolar ridge height
    • Proprioception (PDL mechanoreceptors)
  • Improves:
    
    • retention & stability with attachments
    • Denture support (vertical stops)
  • Less psych trauma-not all teeth are lost
  • Convertibility→switch to complete denture if teeth are extracted
• Disadvantages:
  
  • Exposed Dentin→Increased risk for caries
  • RCT therapy
    
    • potential coronal leakage→ RCT failure
  • Canines→ Denture Flange irritates mucosa
  • Possible cementum failure

Question 3

Tooth Supported Overdenture: Indications vs contraindications

Answer 3

• Indications:
  
  • poor candidates for surgery
    
    • radiation therapy
    • bisphosphonates
  • Financial constraints
    
    • can’t afford implants
• Contraindications:
  
  • Tissue undercuts
  • Poor Manual Dexterity
  • No distribution of abutment teeth→poor prognosis

Question 4

Tooth Supported Overdenture: Abutment Teeth

Answer 4

• Adequate
  
  • Perio health
  • endo therapy
• 8-10 mm of restorative space
  
  • < 8mm →break denture
• ≥ 5mm of root in bone
• Location:
  
  • Anterior Mandible
    
    • Alveolar ridge most vulnerable to resorption
    • Canines or Premolars→ reduce adverse forces
  • At least one tooth per quadrant

Question 5

Tooth Supported Overdenture: Options

Answer 5

• Tooth Supported Overdenture with:
  
  • no attachment
    
    • amalgam plug
    • gold casting
  • attachment

Question 6

Tooth Supported Overdenture with no attachment

Answer 6

• Provide Support Only
• Dome shaped abutment
• Amalgam Plug
  
  • Direct Restoration→ Amalgam or Composite
    
    • requires 1mm supracrestal tooth
    • only provides coronal seal (access hole)
      
      • does not cover dentin
• Gold Coping
  
  • Indirect Restoration
    
    • Tooth at Crestal ridge
    • Coronal & dentin coverage

Question 7

Tooth Supported Overdenture with attachment

Answer 7

• Provide Retention & support
• Direct or Indirect Restoration
  
  • Direct:
    
    • root is straight or 10-20° divergent
  • Indirect:
    
    • Root > 20° divergent

Question 8

Implant Supported Overdenture: Advantages vs Disadvantages

Answer 8

• Advantages:
  
  • Preserve alveolar ridge height
  • Improves
    
    • retention & stability
    • support to denture (Vertical stop)
  • No dentin exposure, caries, decay, endo complications
  • Control implant locations
  • Less maintenance
• Disadvantages
  
  • requires sufficient bone volume for implant placement
  • Financial constraints
  • No proprioception (No PDL mechanoreceptors)
  • Can’t undergo implant surgery (medically compromised)
  • Maxilla requires at least 4 implants
    
    • can’t be done on 2→ compromise peripheral seal

Question 9

What are the different types of Attachment Systems used in over dentures?

Answer 9

• Both used in Implant or tooth supported overdenture
• Stud Attachment:
  
  • locator=most common
    
    • consists of 2 parts (male & female)
      
      • 1 attached to abutment
      • 1 attached to denture base
• Bar Attachment:
  
  • Physical barrier goes b/w implants or natural teeth

Question 10

Stud attachment Advantages vs disadvantages

Answer 10

• Advantages:
  
  • Less restorative space needed
  • easier to clean and replace
  • auto aligns when placed
• Disadvantages:
  
  • less stable
  • Limited implant angle correction

Question 11

Bar Attachment: Advantages vs disadvantages

Answer 11

• Advantages:
  
  • increased stability
  • Increased stress distribution
  • Fixes poorly placed implants
• Disadvantages:
  
  • Hard to clean
  • More expensive
  • requires 13mm of restorative space

Question 12

Locator Abutment/Attachment

Answer 12

• most common stud attachment
• adjust unparalleled implants
  
  • Regular vs extended range males:
    
    • regular:
      
      • if abutment is < 20° off
    • Extended range:
      
      • if abutment is > 20-40° off
• multiple cuff heights (1-5mm)
  
  • Use thickest tissue level
  • allows retention groove to be at surpragingival height

Question 13

What are the different parts of the Locator?

Answer 13

• metal housing
  
  • holds long insert
  • gives force
• Nylon insert
  
  • attaches denture base to abutment

Question 14

What are the two methods to attach the metal housing to the denture

Answer 14

• Direct Method
  
  • Place abutment
  • place metal housing
  • Try on denture & modify denture
• Indirect Method:
  
  • take abutment height
  • registration in the impression