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GUPEA >
Sahlgrenska Academy / Sahlgrenska akademin >
Institute of Odontology / Institutionen för odontologi >
Doctoral Theses / Doktorsavhandlingar >
On cobalt-chrome frameworks in implant dentistry
Please use this identifier to cite or link to this item:
http://hdl.handle.net/2077/21179
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| Title: | On cobalt-chrome frameworks in implant dentistry |
| Authors: | Hjalmarsson, Lars |
| Email: | lars.hjalmarsson@dll.se |
| Issue Date: | 2009-11-22 |
| University: | University of Gothenburg. Sahlgrenska Academy |
| Department: | Institute of Odontology. Department of Prosthetic Dentistry/Dental Material Science |
| Parts: | I Hjalmarsson L, Örtorp A, Smedberg J-I, Jemt T. Precision of Fit to Implants: A
Comparison of Cresco™ and Procera® Implant Bridge Frameworks.
Clinical Implant Dentistry and Related Research, in press
VIEW ARTICLE
II Hjalmarsson L, Smedberg J-I, Wennerberg A. Material degradation in implantretained
cobalt-chrome and titanium frameworks. Submitted for publication.
III Hjalmarsson L, Smedberg J-I, Aronsson G, Wennerberg A. Cellular responses to
cobalt-chrome and CP titanium: an in vitro comparison of frameworks for implantretained
oral prostheses. Submitted for publication.
IV Hjalmarsson L, Smedberg J-I, Pettersson M, Jemt T. Implant level Cresco-prostheses
in the edentulous upper jaw. A comparison with conventional abutment level prostheses
after 5 years in function. Submitted for publication.
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| Date for public defence: | 2009-12-11 |
| Public defence: | Fredagen den 11 december 2009, kl. 9.00, Föreläsningssal 3, Odontologen, Medicinaregatan 10 |
| Examinationsnivå: | Doctor of Philosophy (Odontology) |
| Publication type: | Doctoral thesis |
| Keywords: | cobalt-chrome
titanium
implants
misfit
corrosion
viability
abutment-free |
| Abstract: | Background: Cobalt-chrome (CoCr) alloys have been used in dentistry in decades but very
little is known about their behavior and biological impact as framework materials in implant
dentistry. Furthe... morermore, few studies have evaluated and compared the clinical and radiological
results of abutment and abutment-free implant treatment concepts. Aims: To investigate in
vitro CoCr and commercially pure (CP) titanium frameworks regarding precision of fit,
estimated material degradation and possible adverse cellular responses. In addition, to
retrospectively evaluate the clinical and radiological five-year outcome of abutment-free
porcelain-veneered CoCr prostheses compared to acrylic-veneered CP titanium prostheses,
with or without abutments. Materials and methods: Paper I. Two groups of cast, sectioned
and laser-welded frameworks were fabricated, either in a CoCr alloy or in CP titanium. A
third group comprised computer numeric controlled (CNC) milled CP titanium frameworks.
Measurements of fit were performed with a coordinate measuring machine. Paper II. Ion
leakage from titanium implants, CoCr and CP titanium framework sections into artificial
saliva was observed with mass spectrometry. Surface structures were registered with optical
interferometry. Paper III. Viability of epithelial cells and fibroblasts cultured on CoCr and
titanium specimens were evaluated with the Alamar Blue™ method. Specimen surface
structures were registered with optical interferometry and cell morphology observed with
SEM. Paper IV. A test group (n=40) comprised of patients treated with prostheses made at
implant level in dental-porcelain veneered CoCr alloy (n=15) or acrylic-veneered CP titanium
(n=25). A control group (n=40) was provided with prostheses made at abutment level, in
acrylic-veneered CNC-milled CP titanium. Clinical and radiological five-year data were
evaluated. Results: Paper I. The transversal width decreased in CoCr frameworks, but
increased in both groups of titanium frameworks. Less vertical distortions were present in the
CNC-milled frameworks compared to the two other groups. Paper II. Significantly more
cobalt ion leaked than titanium and chrome ions. Both framework sections and implants
roughened after saliva exposure. Paper III. Both cell groups were more viable on titanium
than on CoCr surfaces. The CoCr surfaces had a lower height deviation but were denser than
the CP titanium surfaces. No major deviations from normal cell morphology were present.
Paper IV. No significant differences in implant cumulative survival rates were demonstrated
between the test and control groups after five years in function (98.6% and 97.6%,
respectively). No major differences in bone levels were demonstrated. Mucositis and veneer
fracture were the most common complications in all groups. Conclusions: None of the
frameworks presented a perfect, completely “passive fit”. There were indications of active
corrosive processes for both implants and framework materials. Epithelial cells and
fibroblasts preferred titanium to CoCr surfaces. The clinical outcomes of implant level
prostheses made of porcelain-veneered CoCr or acrylic-veneered titanium seem comparable
to acrylic-veneered titanium prostheses made at abutment level. |
| ISBN: | 978-91-628-7923-5 |
| ISSN: | 0348-6672 |
| URI: | http://hdl.handle.net/2077/21179 |
| Appears in Collections: | Doctoral Theses from Sahlgrenska Academy
Doctoral Theses from University of Gothenburg / Doktorsavhandlingar från Göteborgs universitet
Doctoral Theses / Doktorsavhandlingar
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