Removable Partial Denture: Extracoronal Attachment
Extracoronal Attachment is a type of precision attachment which involves two parts. The first half has a ball joint cantilevered from the abutment unit. The second part, is housed within the one piece casting framework. The attachment may involve a spring or an O ring or a similar component.
The attachment compensates for the differential compressibility of the denture bearing mucosa and abutment teeth, which support the denture base. The support provided by abutment teeth and the mucosa is not equal and may result in instability of the denture during function.
Extracoronal attachment usually requires at least one cm of the distal crown height of the abutment to house the component parts. It uses mechanical resistance to displacement through its component on the external surfaces of the abutment tooth or teeth.
EC attachment can be used in a free end saddle situation where stress breaking is a risk. It is also usually prescribed for patients with limited manual dexterity, or a prosthesis with difficult path of insertion and removal.
The disadvantages of Extracoronal Attachment are:
1. Its extracoronal nature alters the contour of the abutment which may be difficult to clean.
2. Loss of O-ring or spring housed within the matrix could result in the sinking of denture, causing possible damage to supporting tissues.
 Carr AB et al: McCracken’s Removable Partial Prosthodontics 11 th ed. Elsevier Mosby 2005
For more info about Extracoronal Attachment, please read:
 Removable Partial Denture Attachment – http://costdentures.com/fixed/removable-partial-denture-attachment/
Jesus Lecitona+, DMD, MScD-Prosthodontics
Email your questions about Extracoronal Attachment at: jes[at]lecitona.com
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