Attachments in Removable Prosthodontics

Lecture Outline

• Why do we use attachments in removable prosthodontics?• Retention of removable partial dentures.• Definition of attachments.• Classification of attachments.• Indications for attachments.• Contraindications for attachments.• Advantages of attachments.• Disadvantages of attachments.• Other attachments and retention devices.• How to choose appropriate attachments for different cases?• References.

Attachments

• Retention, support and stability.

• Can be used with: Partial dentures. Overdentures. Implants.

Retention of Removable Partial Dentures

Retention

Neuromuscularcontrol

MechanicalInherent physical

forces

Clasps Undercuts attachments

Definition• An attachment is a mechanical

device made up of two components, one located in or on the abutments tooth and the other housed in the denture. When the two matched parts are linked together they produce very positive retention.

Classification

Fabrication:Precision

or Semiprecision

Functional characteristics:Rigid or Movable

Location:Intracoronal

or Extracoronal

Size:Macro or Micro

Attachments

Intracoronal Attachments -1

• Two components: Matrix and Patrix.

• Sliding joint configuration.• Retain, support and stabilise

the removable partial denture.

Intracoronal Attachments -2

• Crowns.• At least 4 mm vertical

space.• At least 3 mm buccolingual

space.• Parallelism.

Intracoronal attachment -3

• Location : Intracoronal.• Size : Micro

attachments.• Functional characteristics:

Rigid attachments.• Fabrication: Precision or

semi precision attachments.

Extracoronal attachments -1

• Two components: e.g. Dalbo (Patrix) and other component (Matrix) held in denture.

• Sliding joint configuration.• Retain and stabilise

removable partial dentures.

Extracoronal attachments -2

• Reside entirely outside the normal clinical contour of abutments.

• Need no space within the abutment crown.

• May be employed where buccolingual space is limited.

• often employed to retain bilateral distal extension prostheses.

Extracoronal attachments -3

• Location: Extracoronal.• Size: Micro attachments.• Functional characteristics:

Rigid or movable attachments.

• Fabrication: Precision or semi precision attachments.

Extracoronal attachments -4

• Rigid : only allow movement in one direction.

• Movable: movement allowed should be regarded as a safety valve and not as a means of anchoring an unstable prosthesis to natural teeth.

Macro attachments

• E.g. Telescopic crowns

Indications When neither fixed bridge nor

clasp retained denture would be satisfactory.

Small bounded saddles with considerable bone loss.

Retain bilateral distal extension prosthesis.

Join a series of crowns which don’t have common path of insertion.

Overdentures. Implants.

Contraindications

Short clinical crowns of abutment teeth (Intracoronal attachments).

Limited buccolingual space of abutment teeth (Intracoronal attachments).

Large size of pulp (Intracoronal attachments).

Poor periodontal health of abutment teeth (Rigid attachments).

Lack of experience and clinical skills (Extra and Intracoronal attachments).

Bad oral hygiene (Extra and Intracoronal attachments).

Advantages Better aesthetic results and more effective retention than

clasps. More apical functional load transfer to abutments than rests

(Intracoronal attachments). Diminish rotational movements of abutments (Intracoronal

attachments). Improved cross arch load transfer and stabilisation of

prosthesis. Limit the potentially damaging force imparted to abutments

(Extracoronal attachments and Intracoronal attachments).

Disadvantages Abutment teeth usually

have to be crowned. Occupy a lot of space. Encourage plaque

accumulation. Require ongoing

maintenance. Clinical and technical skills

are demanding. Relatively expensive.

Other attachments and retention devices -1

• Stud attachment• Used with overdentures.

Other attachments and retention devices -2

• Magnets No demands on the

periodontal tissues of abutment teeth.

Other attachments and retention devices -3

• Two parts denture• Needs good manual

dexterity.

How to choose appropriate attachments for different cases? -1

• Personal design philosophy• Rigid or movable?• How much resiliency?

How to choose appropriate attachments for different cases? -2

• Condition of the abutment teeth

• Intra or extracoronal attachments?

How to choose appropriate attachments for different cases? -3

• Condition of the non-abutment supportive structures (periodontal tissues and alveolar ridge)

• Rigid or movable ?

How to choose appropriate attachments for different cases? -4

• Manual dexterity• Intra or extracoronal

attachments ?

References

• Stewart’s Clinical Removable Partial Prosthodontics, Third Edition. Chapter 20, Attachments for removable partial dentures, pages 507-515.

• Preiskel, H. W. (1974). "Precision attachments for the partially dentate mouth." Annals of the Royal College of Surgeons of England 55(6): 294-298.