J Can Dent Assoc 2014;80:e22
jcda
ca
ESSENTIAL DENTAL KNOWLEDGE
Published by
The Canadian Dental Association
5. Once the access hole is located, carefully bore out the edges of the crown to expose the filling material
(cotton pellets, polytetrafluoroethylene [PTFE] tape, gutta-percha). Remove the filling material and
confirm that there is a clear view to the abutment screw (Fig. 2).
6. Confirm the type of abutment screw and matching driver tip.
– There must NOT be any margin impingement from the sides of the crown as the abutment screw
driver is placed (Fig. 3).
– Anything that does not allow full engagement of the screw driver could lead to damage or stripping
of the abutment screw.
7. Carefully inspect and clean the inside of the implant, abutment screw, and crown.
– Confirm that the screw is not damaged or worn.
8. If the screw is not good for reinsertion, replace it with a new screw if necessary.
– Applying the proper torque to the abutment screw is important.
– The alternative is to fabricate a new restoration.
9. Verify the fit of the crown/abutment with a radiograph prior to sealing the access hole.
10. Confirm that light occlusal contacts are centrally located on the crown, and eliminate any significant
excursive interference.
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If No Master Cast is Available
1. Confirm the orientation of the implant with a radiograph.
– The buccal–lingual orientation may be estimated from palpation of the surrounding soft tissues. For
instance, a significant buccal depression may indicate that the implant fixture is positioned to the lingual.
– Continue with steps 4–10 listed previously.
2. The objective of treatment should be to stabilize/replace the loose crown; locating the abutment screw
with minimal trauma to the restoration and implant components is imperative.
– If the access hole to the abutment screw is direct and clean, the same crown may be used as a functional restoration.
– After tightening the abutment screw, the access hole must be filled with a soft material (cotton pellets, PTFE tape, gutta-percha) and then composite resin.
– The continued use of the crown is occasionally possible for bicuspids and molars. Usually, an
anterior crown will need to be remade if the screw access is through the labial surface.
Advice
• A loose abutment screw should be treated urgently, otherwise further damage or fracture of the
implant components could occur.
• A cemented crown onto an implant abutment takes on the path of insertion of the implant and not the
abutment. As such, it may not always be possible to remove the implant crown/abutment assembly due
to binding of the contact areas during attempted removal. In this case, straight tightening is best and
is often the only course of action if a new crown is not contemplated.
The Author
Dr. Hum is a prosthodontist who maintains a private practice in Ottawa.
Correspondence to: Dr. Stewart Hum, Prosthodontics on Chamberlain, 30 Chamberlain Avenue, Ottawa ON K1S
1V9. Email: [email protected]
The author has no declared financial interests.
This article has been peer reviewed.
Suggested Resources
The complete list of suggested resources is available online.
jcda
ca | 2014 | Vol. 80, No. 1 |
ESSENTIAL DENTAL KNOWLEDGE
Published by
The Canadian Dental Association
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