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Single-dose irradiation followed by implant insertion in rat bone: An investigative study to find a critical level for osseointegration
Örebro University, School of Health and Medical Sciences. Örebro University Hospital, Örebro, Sweden. (MedTek)
Sahlgrenska University Hospital, Göteborg, Sweden.
Örebro University, School of Health and Medical Sciences. Örebro University Hospital, Örebro, Sweden. (MedTek)
Sahlgrenska Academy, Institute of Clinical Sciences, University of Gothenburg, Göteborg, Sweden.
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2010 (English)In: Journal of Osseointegration, ISSN 2036-4121, Vol. 2, no 2, p. 52-60Article in journal (Refereed) Published
Abstract [en]

Aim: No general consensus exists regarding the ideal time to insert implants in bone after irradiation or how the various irradiation doses influence implant success. This study aims at investigating integration of implants in pre-irradiated rat bone and find a critical level doses that cause disturbed osseointegration.

Materials and methods: Single irradiation doses of 2, 5, 10, 20 and 30 Gy were given to one leg of adult rats 3 days prior to insertion of screw-shaped implants whereas the other leg served as a non-irradiated control. The follow up was 5 weeks. Bone implant contact (BIC) and bone area (BA) were measured on undecalcified cut and ground sections in the light microscope. The tissue quality was also examined in the light microscope.

Results: Doses of 5 and 10 Gy resulted in 25% higher contact values for the irradiated samples compared to non-irradiated controls. The most impaired integration occurred when doses of 20 Gy were given, revealing a 50% difference between the irradiated (25%) and the non irradiated samples (50%). The bone area demonstrated no major quantitative differences albeit the qualitative observations differed substantially being most pronounced in the 20 and 30 Gy irradiated samples.

Conclusions: The osseointegration was substantially impaired after radiation doses of 20 and 30 Gy. Quantitative data alone are insufficient to describe implant integration in situation like this. Qualitative observations are of utmost importance and require great attention. The importance of judging and describing various grades of tissue damage is complicated but necessary. Based on the results obtained in this study, full scale experiments are now ongoing.

Place, publisher, year, edition, pages
Carimate, Italy: Ariesdue , 2010. Vol. 2, no 2, p. 52-60
National Category
Dentistry
Research subject
Medicine
Identifiers
URN: urn:nbn:se:oru:diva-11359OAI: oai:DiVA.org:oru-11359DiVA, id: diva2:328750
Available from: 2010-07-06 Created: 2010-07-06 Last updated: 2017-10-18Bibliographically approved
In thesis
1. On implant integration in irradiated bone: clinical and experimental studies
Open this publication in new window or tab >>On implant integration in irradiated bone: clinical and experimental studies
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Radiation has an impact on the processes involved in bone- healing, regeneration and remodeling. The mechanisms that cause impaired bone healing of dental implants are not fully understood. Adjunctive treatments to revers radiation effects are limited. Dental implant surgery can be a risk in irradiated jaws and the risk for osteoradionecrosis is of concern. There is no consensus when to install implant after completed radiation therapy or what radiation dosage might cause impaired bone healing. The overall aim of the studies was to investigate bone tissue reactions adjacent to implants after irradiation.

I. A clinically long-term follow-up study was performed to assess the outcome of 18 dental implants inserted in five patients with and without irradiated fibula-reconstructed mandibles. Bone tissue reactions adjacent to 14 micro-implants were histologically evaluated. In the clinical follow-up, 15 implants were in function, with an overall success rate of 83%. The histomorphometric analyses demonstrated an impaired osseointegration with reduced bone-to-implant contact (BIC) and bone area (BA), in irradiated sides.

II. In an experimental animal study the aim was to find a critical level for a given single external radiation dosages causing impaired implant osseointegration. 9 rats received a single radiation dose of 2, 5, 10, 20 and 30 Gy, respectively to one hind-leg while the other served as a control. Three days post radiation two implants were inserted in each hind-leg and after a period of 5 weeks the implants (n=36) were harvested for histological examination. BIC and BA were lower for irradiated samples for dosages of 20 Gy and higher.

III. The aim was to investigate the effects of HBO on osseointegration of titanium implants in irradiated bone. 15 rats received an external single radiation dose of 20 Gy to one hind-leg. 3-days post-irradiation 2 implants were inserted in each hind-leg (n=60). The rats were divided in to 2 groups and one group received hyperbaric oxygen treatment (HBOT) 3 days post-implant insertion (n=8). After 5 weeks the distal implants were harvested for histological examination (n=30) and the proximal implants were used for removal torque tests (n=30). BIC obtained significant higher values for non-irradiated side, independent of HBO or not. BA obtained significant higher values for irradiated sides in the non-HBO group.

IV. The aim was to investigate gene expression in irradiate bone after implant insertion for bone formation, resorption and remodelling. 8 rats, received a single radiation dose of 20 Gy to one hind-leg and two implants inserted in each hind-leg 8 weeks after completed radiation therapy. After 5 weeks bone samples with implants were collected for gene expression analysis. ALP, OC (formation) and RANKL/OPG (remodelling) were down regulated in irradiated samples.

Conclusion: Bone-anchored dental bridges can be used in selected oro-mandibular reconstructed patients. Bone quality disturbances with impaired osseointegration for dosages of 20 Gy and more were demonstrated in an animal study model. HBO did not enhance osseointegration of implants placed in rat bone during a five-week follow-up period. Irradiation significant reduces bone formation and remodeling under influence of pro-inflammatory and growth factor cytokines

Place, publisher, year, edition, pages
Örebro: Örebro university, 2015. p. 75
Series
Örebro Studies in Medicine, ISSN 1652-4063 ; 128
Keywords
dental implant, osseointegration, radiation therapy, bone remodeling, histomorphometry, hyperbaric oxygen therapy, gene expression and in vivo
National Category
Surgery Dentistry
Research subject
Surgery
Identifiers
urn:nbn:se:oru:diva-45834 (URN)978-91-7529-096-6 (ISBN)
Public defence
2015-11-20, Universitetssjukhuset, Bomanssonsalen, Södra Grev Rosengatan, Örebro, 09:00 (Swedish)
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Supervisors
Available from: 2015-09-18 Created: 2015-09-18 Last updated: 2017-10-17Bibliographically approved

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Nyberg, JanJohansson, Carina B.

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