Precision attachments-principles. Milling technique. Conical crowns. Channel shoulder attachments, Swing- lock attachments. One piece cast Flashcards
What are precision attachments?
Special retainers in partial dentures
What are the functions of precision attachments?
- Fixation, retention and stability of prosthesis
- Replace occlusal rest, reciprocal arm and retentive arm of conventional clasp retained PD
Materials used to make precision attachments
milled alloys
Components of precision attachments
Matrix(Attached to abutment tooth)
Patrix(Attached to metal framework)
Advantages of precision attachments
Improved aesthetics
Easier to clean
Mechanical(forces directed along long access of teeth)
Disadvantages of precision attachments
- Complexity of design and procedures
- Excellent Oral hygiene required
- Aggressive tooth prep required
- Manual dexterity of patient required
Indications for precision attachments
- Retention and stabilisation
- Stress breakers
- Divergent abutment teeth with high survey line
- Implant prosthodontics
Contraindications for precision attachments
- Poor periodontal support
- Poor crown to root ratio
- Poor oral hygiene
- Inadequate space
Types of fit of precision attachments
Wider fit R1R2
Translational fit
Wider fit R1 < R2
Less friction
Secured by locking element
Tighter fit R1>R2
Strong forces required for removal
Frictional forces damage teeth
Translational fit
Ideal when layer of saliva compliments fit
Describe the milling technique
- Precision machining of wax and cast surfaces at controlled angles
- Produces custom made pieces
Types of milling techniques
Conventional milling(finer-right to left) Climb milling(rough-left to right)
