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Internal vs. external connections for abutments/reconstructions: a systematic review
Stefano Gracis1, Konstantinos Michalakis, Paolo Vigolo
1Division of Postgraduate Prosthodontics, Tufts University, School of Dental Medicine, Boston, MA, USA. sgracis@dentalbrera.com
Clinical Oral Implants Research
|October 16, 2012
Summary
This review found that implant connection type can influence impression accuracy, with implant divergence negatively affecting internal connections. Screw loosening is the most common complication, potentially reduced by proper preload.
Area of Science:
- Dental Implantology
- Prosthodontics
- Biomaterials
Background:
- Accurate implant-level impressions are crucial for successful prosthetic restorations.
- Understanding technical complications associated with different implant connection types (internal and external) and materials (metal and zirconia) is essential for long-term clinical success.
Purpose of the Study:
- To evaluate the accuracy of implant-level impressions for internal and external connection abutments/reconstructions.
- To assess the incidence of technical complications in metal- or zirconia-based abutments and single-implant reconstructions with internal and external connections.
Main Methods:
- A systematic literature search of MEDLINE and hand searches of key dental journals (2009-2012) were conducted.
- Inclusion criteria focused on studies evaluating implant-level impression accuracy and technical complications of abutments/reconstructions.
- Seven in vitro studies were included for accuracy assessment, and 19 clinical studies for complication analysis.
Main Results:
- No studies directly compared impression accuracy between internal and external connections using a standardized protocol.
- In vitro studies indicated that implant divergence negatively impacts impression accuracy with internal connections.
- Screw loosening was the most frequent mechanical complication for metal abutments/reconstructions, regardless of connection type. Fracture incidence was not influenced by connection type.
Conclusions:
- Implant-level impression accuracy is multifactorial, influenced by connection type, design, implant parallelism, and impression techniques.
- While abutment/screw fracture rates are similar, screw loosening is more prevalent in externally connected systems, suggesting proper preload is critical.
- Further research is needed to directly compare impression accuracy between internal and external connections and to better understand complication incidence.