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In this section you get a brief look at the research, with practical implications, currently undertaken in the area of dental implants and related areas.
Clicking the highlighted link in the end of each summary, will take you to an abstract of the article, as presented by the PubMed database.
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1. Is it possible to apply GBR procedures at transmucosal implants and succeed in single stage surgery?
The aim of this clinical study was to test whether peri-implant bone defects can successfully be filled with bone by applying bioresorbable materials for guided bone regeneration (GBR) procedures in conjunction with implants in the transmucosal healing position.
10 patients received an ITI implant at the extraction site 8-14 weeks following tooth extraction. The implants had 2 distincly different surfaces – a titanium plasma sprayed surface comprising the endosseus portion and a smooth surface for the transmucosal part. Only patients with a proper prosthetic location and primary stability of the implant were included in the study. All implants exposed part of the rough titanium plasma sprayed surfaces. The implants were covered with a bioresorbable collagen membrane (Bio-Gide) and deproteinized bovine bone mineral (Bio-Oss) was used as a membrane-supporting material. The implants were left extending transmucosally into the oral cavity and were not loaded during the observation period.
At reentry 6-7 months later 8 of the 10 patients showed 100% defect resolution with respect to the rough titanium sprayed surfaces. But if the baseline defect was 2 mm and less there was a slight loss of bone between baseline and re-entry, maybe because of contact of the crestal bone with the smooth surface of the implant. But this needs further investigation to be clarified. One patient exhibited 60% defect fill and the last patient was a complete failure. Both these latter 2 patients showed signs of disturbed wound healing.
It is thus demonstrated that it is possible to combine implantation and GBR in a single procedure without the need for further surgical interventions. ( edited by EB )
Hämmerle C.H.F & Lang N.P.: Single stage surgery combining transmucosal implant placement with guided bone regeneration and bioresorbable materials.
Clin Oral Impl Res 12, 2001:9-18
2. Can single tooth implants be functionally loaded immediately?
Ericsson et al have done an 18 months' clinical pilot follow-up study of 14 Brånemark implants installed in a 1-stage surgical procedure. Within 24 hours a provisional crown was cemented to the abutment. The occlusion of the crown was designed with no or minimal contacts in centric relation as well as in intercuspidal position and at lateral excursions. Six months after the installation of the implant pillar the temporary crown was removed and a permanent crown was cemented.
The experimental group were non-smokers and non-bruxers. All replaced teeth were canines or incisors and the amount of bone had to allow for installation of a fixture with a minimum length of 13 mm and a diameter of 3, 75 mm.
Two of the implants were lost, the remaining 12 implants were stable at all follow-up examinations. (edited by EB)
Ericsson I et al. Immediate functional loading of Brånemark single tooth implants. An 18 months' clinical pilot follow-up study.
Clin Oral Impl Res 2000:11:26-33
3. Horizontal osteotomy for reconstruction of the narrow edentulous mandible.
A narrow edentulous mandible does not allow for a direct insertion of an implant. Raghoebar et al used a horizontal osteotomy procedure to reconstruct a narrow inferior alceolar crest in 7 edentulous patients. Three months later 10 Brånemark and 8 ITI Bonefit implants were inserted. Implant supported overdentures were fabricated 3 months after implantation.
At the time of evaluation the implants had been loaded for at least 14 months ( range 14-68 months, mean 37 months ). All implants and overdentures functioned well and without sensitivity problems. They conclude that the horizontal osteotomy procedure to widen a narrow edentulous alveolar ridge with autogenous bone grafts is a reliable surgical procedure to enable the insertion of implants. The procedure is simple and can be performed under local anasthesia. (edited by EB)
Raghoebar GM et al: Horizontal osteotomy for reconstruction of the narrow edentulous mandible.
Clin Oral Impl Res 2000.11:76-82
4. Difference in complications for fixed partial dentures
on implants or on teeth?
The aim of the study was to compare the frequency of biological and technical complications with fixed partial dentures ( FPDs ) on implants, teeth and as mixed tooth-implant supported FPDs over 4 to 5 years of function. All implants belonged to the ITI Dental Implant System.
3 groups of patients were examined, one group with FPDs from implant to implant ( 40 FPDs ), a second group with FPDs from tooth to tooth ( 58 FPDs ) and a third group with FPDs from implant to natural tooth ( 18 FPDs ).
No statistical significance was found concerning biological complications. 9.6% of the implants had periimplantitis, defined as pathological pocket depth > 5 mm and bleeding on probing, whereas 11.8% of the abutment teeth presented biological complications ( 2.8% had secondary caries, 4.9% had endodontic problems and 4.1% had periodontitis ).
There were statistically significantly more technical complications at implant compared to tooth abutments. Of all implants 2.9% had loss of retention, 10.7% had a minor porcelain fracture and 6.8% occlusal screw loosening. Technical complications occured in 6.3% of the abutment teeth: 0.7% showed loss of retention and 5.6% a porcelain fracture.
The authors found no statistical difference in technical complications between cemented ( 16.5% ) and screw retained ( 11.5% ) FPDs on implants. But bruxism as well as extensions were associated with more technical failures. ( edited by EB )
Urs Brägger et al: (2001) Biological and technical complications and failures with fixed partial dentures ( FPD ) on implants and teeth after four to five years of function.
Clin Oral Impl Res 12: 26-34
5. otal transformation of bioactive glass particles into mature lamellar trabecular bone in humans 16 month after sinus floor elevation.
Tadjoedin, E.S. et al. use a ’split-mouth’ study design to evaluate the bone formation in a 1:1 mixture of bioactive glass particles (size range 300 – 355 um) and autogenous bone particles (iliac crest) compared to bone particles alone (control side) after bilateral sinus floor augmentation.
Bone biopsies were harvested 4,5 and 6 months later in the study groups and in a single patient 16 month later.
The authers suggest that the relative small size particles function as a bone growth center, but the formation of lamellar bone is delayed several months compared to the control side. The formation of lamellar bone (experimental side) was first noticed 5-6 month after the sinus augmentation took place. However, total transformation of bioactive glass material into mature lamellar trabecular bone was observed after 16 months. The implication of this observation for the implant treatment when compared to the use of other bone substitutes remain to be established.
The significance of persisting particles of biomaterials present at the bone-implant interface, when fixtures are installed after bone augmentation procedures is not known (ed. NGP).
Tadjoedin, E.S. et al. (2000) Histological observations on biopsies harvested following sinus floor elevation using a bioactive glass material of narrow size range.
Clin Oral Impl Res 11: 334-344.
6. Reuse of coverscrews?
Many clinicians have probably been tempted to the reuse of coverscrews. Beside the ethical considerations of re-using medical devices, it has been uncertain to what extent the surface changes due to previous use will alter the tissue response compared to a brand new coverscrew.
Zvi Schwartz et al. shows that the reuse of coverscrews - after proper cleaning and sterilisation - do not affect the overlying epithelial and connective tissues compared to the new coverscrews at the time of removal (abutment connection 3-6 month later). However, the study does not support the reuse of titanium in bone. The study suggests it is clinical safe to reuse a coverscrew, but only in the same patient (ed. NGP)
Schwartz, Z. et al. (2000). Re-use of implant coverscrews changes their surface properties but not clinical outcome.
Clin Oral Impl Res 11: 183-194
7. Is it only patients with severely resorbed mandible who benefit by the implant-retained overdenture?
Raghoebar, G.M. et al. evaluate the patient satisfaction and chewing ability of patients with an edentulous mandible treated with either conventional full denture or implant-retained overdenture.
the patients has a residual mandibular height in the symphysis region between 15 mm and 25 mm before treatment). Patient satisfaction was assessed after 1 and 5 years. Patients with the implant-retained denture were in general more pleased with their denture compared to patients treated with a conventional mandibular denture! (ed. NGP)
Raghoebar, G.M. et al. (2000). Effectiveness of three treatment modalities for the edentulous mandible. a five-year randomized clinical trial.
Clin Oral Impl Res 11: 195-201
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