 Astra Tech
BioManagement Complex
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 Surgical techniques
A wide range of different surgical techniques are applied when placing implants under different preconditions. The summaries below show that one- and two-stage surgery, immediate placement in extraction sockets, bone augmentation and sinus lift can be successfully and predictably performed using the Astra Tech Implant System'".
 Reconstruction of the severely resorbed maxilla with autogenous bone, platelet-rich plasma, and implants: 1 -year results of a controlled prospective 5-year study
Purpose: The primary outcome variable in this controlled clinical study was to evaluate the effect on osseointegration of implants placed after bone grafting with or without adjunctive platelet rich plasma (PRP). A second aim was to compare implant osseointegration of block grafts without PRP with PRP-treated particulated bone.
Materials and methods: A splitmouth design was applied in this study. In each patient, the anterior maxilla was divided into test and control sides. Both sides of the posterior maxilla were also divided in test and control. The 19 patients (2 men and 19 women, mean age 58 years), referred to the Maxcil-lofacial Unit (Stockholm, Soder Hospital) were consecutively included in the study. Inclusion criteria were: signed informed consent; no general medial contraindications for surgery/general anesthesia; no alcohol abuse; cigarette consumption <9 cigarettes per day; residual bone height of 2-5 mm and width < 2mm at planned implant sites, and an age between 20 to 75 years.
A corticocancellous bone graft was taken from the iliac crest under general anaesthesia. The bone was subdivided for placement of onlay block graft (anterior right side), onlay particulated bone graf with PRP (anterior left side), and for inlay grafting with particulated bone with (left sinus) or without (right sinus) PRP. The preparation of PRP was carried out from the patients venous blood (450 mL) by several steps of separation. The PRP was blended with mixture of autologous thrombin and anticoagulated PRP and left to form a gel that could be used together with the bone.
Eight implants were placed in each patient (TiOblast 3.5, n=152, lengths between 9-17 mm) and were left submerged to heal for 6 months when healing abutments were connected. All patients received fixed prosthetic restorations and the 1-year examination was performed after 1-year of loading.
Recording of the marginal bone levels were performed using a picture analysis system (NIH Image) on carefully taken radiographs at prosthetic delivery and after 1-year of loading. The top of the cervical section of the implant neck served as the reference point.
Stability measurements by means of Resonance Frequency Analysis (RFA, Ostell apparatus, giving the value in Implant Stability Quotient, ISQ) was performed at implant installation, abutment connection and after 1-year of loading.
Result: Following grafting procedure, two patients developed localized infections that resolved with drainage and antibiotics. A marked resorption of the grafts was generally seen at implant placement. At abutment connection 2 implants were found mobile, giving a total survival rate of 98.7%. Following abutment connection, 4 patients showed penetrations of the cover screws, which also were accompanied by some marginal bone resorption.
The mean marginal bone levels at all test sides changed from 1.3 mm (SD±1.9) to 1,8 mm (SD±1.1) between prosthetic insertion (baseline) and 1-year. The corresponding figures for bone levels on the control side were 1.5 mm (SD±1.7) at baseline to 2.0 mm (SD±0.9) at 1-year follow up. The difference between the test and control was not statistically significant.
The RFA measurements revealed similar stability at implant placement for all implants, but significantly better stability at test sites (PRP) at abutment connection and at the 1-year follow-up, compared to control sites.
Discussion and conclusion: The present study could not show any significant differences in clinical outcome when particulated or block grafts were enhanced with PRP or not. An advantage with particulated bone is that it is easier to mold to the contour of the recipient bone. It has further been hypothesised that particulated bone could be more quickly incorporated due to the immediate access of angiogenic and osteogenic cells in the space between the particles of the graft. However, the result could not prove any such advantages. The result did prove on the possibility to achieve predictable clinical result with particulted onlay grafts. Stability measurements revealed significantly better stability for grafted sites augmented with PRP at abutment connection and after 1 year of loading. The reason for this is attributed to the type of graft rather than to an effect of PRP. The level of stability, around 60 ISQ after 1-year, corresponds well to results, reported from other clinical studies.
In conclusion, the results here show on high implant survival and stable marginal bone conditions 1 year after loading in autogenous bone grafted maxillaes. The addition of PRP to the graft had no significant influence on the result, but the use of the rough TiOblast implant may have positively influenced the clinical outcome, compared to if a smooth or machined implant surface had been used. |
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