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Issue: 04/2009 - A. Behneke - N. Behneke - M. Burwinkel - B. d’Hoedt
Clinical assessment of the reliability of a computer-aided implant planning concept using laboratory-fabricated templates based on cone beam computed tomography

The purpose of this prospective study was to assess the reliability of computer-aided implant planning based on cone beam computed tomography and mechanical transfer using laboratory-fabricated surgical templates. A total of 131 implants were placed with the aid of 3D-based transfer templates in forty consecutive partially or fully edentulous patients between September 2006 and November 2008. After individual adaptation of the scan templates and cone beam CT scanning, the acquired data for virtual implant planning and simulation was processed using the med3D and coDiagnostiX software programs. Following spatial alignment using the references and positioning table, the scan templates were converted for the transfer of the planning results to the actual surgical situation by inserting guide tubes for cavity preparation. The data recorded intraoperatively and the preoperative planning data were assessed using descriptive statistics, scattergrams and the Spearman correlation coefficient to compare the planned and actual situation. Agreement between the planned and actual implant sizes was 97.7% for length and 96.2% for diameter. The Spearman correlation coefficient indicated a high relationship between planned and achieved outcome with 0.99 for the length, 0.95 for the diameter, 0.90 for the width of buccal bone wall and 0.80 for the width of oral bone wall and dehiscence. On average, the differences in width between the planned and intraoperative situation were 0.15 ± 0.45 mm for the buccal bone wall, and 0.1 ± 0.39 mm for the oral bone wall. The maximal overestimation of the width of bone wall was –1.5 mm for the buccal aspect and –0.7 mm for the oral aspect. Underestimations of the actual bone availability were a maximum of 1.0 and 1.5 mm respectively. Differences between planned and achieved outcome were more frequent in completely edentulous patients with mucosa-supported templates and the maximum overestimation for the width of the buccal bone wall increased to –1.5 mm (mean 0.2 mm). If natural teeth were used to support the template in partially edentulous patients, the bone width was overestimated by a maximum of –0.5 mm (mean 0.1 mm) indicating very accurate transference of data.

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Issue: 04/2009 - W. Wagner - H. Götz - H. Duschner - M. O. Klein
Bony integration of an alloplastic bone substitute material (NanoBone) after maxillary sinus augmentation –

Modern bone substitute materials (BSM) have to meet numerous structural and biological requirements. Accordingly, morphological in vitro analysis and histomorphometric ex vivo investigations are of great significance to estimate BSM biocompatibility. Aim of the study was a respective evaluation of a modern alloplastic BSM (NanoNone).

Structural in vitro analysis of the native BSM was carried out by electron microscopy and microcomputed tomography (µ-CT) with special regard to porosity. 14 months after maxillary sinus augmentation with NanoBone and collected autologous bone particles in one individual patient case, a representative trephine biopsy out of the augmentation volume was histomorphometrically analysed employing conventional histology and µ-CT. Volume ratios of newly formed bone and remaining BSM particles were calculated via assessment of 2D-phase distribution of tissue density.

In vitro investigation of the BSM showed a chiselled macrostructure with a total porosity of 65 % as well as a high ratio of pores 250 µm, which were almost exclusively localized interparticulary. Histomorphometric analysis of the trephine biopsy revealed a good bony integration of the BSM with evidence of BSM resorption and replacement by vital bone tissue after 14 months. The volume ratio of newly formed bone was 37 %.

The presented methods for pre-clinical and clinical evaluation of modern BSM complement one another in a reasonable manner.

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Issue: 03/2009 - H.-L. Graf - J. Hofmann - U. Tröger - J. Schreckenbach - H. Hilbig
In vitro studies to screen for implant surface properties*

In a short-term (ten days in vitro) culture of cells derived from human maxillae the expression of the non-collagenous bone matrix proteins osteonectin, osteocalcin and bone sialoprotein at the surface of four clinically-employed and three experimentally-designed implants was estimated quantitatively. The surfaces “titanium-calcium-magnesium ANOF” and “titanium-calcium-magnesium-fluoride ANOF” induced high expression levels of bone-derived cell markers. Theses results suggest further investigation magnesium – and fluorid modifications including.

Both the chemical composition of the implant and the microstructure of the implant surface influence protein expression.

The experimental design is suitable for preliminary and quick screening to select experimentally designed implant surfaces for further testing.

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Issue: 03/2009 - G. Weibrich - Ph. Streckbein - W. Kleis - R.S.R. Buch - T. Hansen
Bone remodeling around dental implant surfaces

This study analyzed the effect of four different implant surfaces on bone regeneration in vivo. In twelve female beagle dogs, four different titanium screw implants (Branemark MK III, Osseotite, Xive and Compress) with four different surfaces (TiUnite, Osseotite, Friadent Plus and machined/sandblasted, respectively) were inserted in the mandible. Intravital fluoro-chrome staining was performed in the 1st (alizarin), 2–3rd (calcein green), and 4–5th (xylenol orange) weeks. Five animals were analyzed histologically and histomorphometrically after six weeks and six were analyzed after twelve weeks. At six weeks, the median peri-implant fluorochrome labeling (% of marked bone surface), a marker of bone regeneration, was slightly greater for Xive (73.38 ± 10.3 %) and Brane-mark (69.97 ± 25 %) than for Compress (54.47 ± 17.5 %) and Osseotite (49.53 ± 9.5 %). At twelve weeks, the Xive implants had the highest median bone-implant contact rate (BIC) (72.36 ± 8.21 % vs. Branemark 53.37 ± 9.74 %, Osseotite 47.47 ± 11.95 %, and Compress 42.7 ± 5.7 %). Peri-implant bone regeneration (fluorochrome staining) and the resulting BIC did not differ significantly among the four implant surfaces at six or twelve weeks (sign test, all p ? 0.063). This study demonstrated that these four implant surfaces did not differ significantly in their effect on peri-implant bone regeneration and the BIC.

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Issue: 02/2009 - H. Schliephake - E. Nkenke
Immediate loading and immediate restoration of oral implants: indications and survival rates

Based on an analysis of the current literature, the aim of the study was to compare the survival rate of immediately loaded implants with implants loaded after an unloaded healing period.

The literature search was performed electronically. Medline and Embase were searched from 1966 to 2006. The keywords were dental implant, delayed loading, immediate loading, immediate restoration, mandible, maxilla, edentulous, oral implant, partially dentate and single-tooth in different combinations.

The results of the literature analysis show that there is evidence based on prospective randomised controlled clinical trials that immediate loading of dental implants yields survival rates that are comparable to those of implants which are loaded after an unloaded healing period. These results are found in the mandible as well as in the maxilla and in edentulous, partially dentate and single-tooth situations. The lowest survival rate for immediate loading was 81.2 %, found after twelve months for single-tooth situations in the maxilla. For the remaining situations the survival rate exceeded 95 % after twelve months.

The analysis of the literature shows that immediate loading is well established in implant dentistry for all indications. In the future it will be important to define valid criteria that allow safe patient selection for immediate loading.

Keywords: Immediate loading, immediate restoration, dental implant, unloaded healing

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Issue: 02/2009 - H. Terheyden - H. Ruoff
Retrospective radiographic investigation of the long-term stability of xenografts (Geistlich Bio-Oss) in the sinus

The Bio-Oss graft proved to be very stable over a 10-year investigation period. The height reduction over the apex of the implant averaged 0.1 mm per year. Six of the 364 implants in Bio-Oss grafts were lost (two before and four after loading) during the observation period of 0 to 12 years. Therefore, the cumulative survival rate was 98.4 %. Marginal bone loss was monitored for almost six years. Crestal bone resorption in the mesial aspect averaged 0.235 mm per year with a standard error of 0.021 mm per year. In the distal aspect, the resorption rate was 0.211+/-0.018 mm per year. Since the implants were still completely osseointegrated within the follow-up period, even in the case of low preoperative bone levels, it can be concluded that the Bio-Oss graft contributed to the stabilization of the implants.

Keywords: Sinus elevation, long-term stability, marginal bone loss, implant survival rate,

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Issue: 01/2009 - H. Spiekermann - K. Papoulia - B. Wessing - K. Tokmakidis
Load distribution and loading concepts on teeth and implants

Tactile sensitivity and the function regulation of jaw movements with partially or completely implant-based restorations are very different and imprecise compared with the natural dentition. This systematic review shows certain correlations between the bite force and how the dentures are anchored. Twenty-two English and German publications were analyzed. The loads are three times higher on removable implant-borne prostheses and nine times higher on fixed single-tooth implant-borne restorations than on the natural dentition. This can lead to premature fatigue of the materials used, as well as to overloading of the implant abutments. This phenomenon can be reduced with the use of rigid materials (metal framework and porcelain veneering); splinting implants with natural teeth can also provide afferent feedback and thus prevent functional overloading. In regard to a satisfactory long-term prognosis, the type of splinting requires special attention.

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Issue: 01/2009 - J. Wiltfang - S.T. Becker - E. Behrens - I.N.G. Springer - R. Podschun - P.H. Warnke
Essential oils: antimicrobial effects and potential treatment options in dental implantology

Due to the steadily increasing numbers of dental implants placed, the number of peri-implant infections is also growing. To date, there is no standard and generally accepted regimen for treating peri-implant infections. The search for alternative treatment options is ongoing. This pilot study focuses on the antimicrobial effects of essential oils as their antimicrobial and anti-inflammatory effects have recently been highlighted in literature. The results may offer potential treatment options for peri-implant infections based on natural essential oils. Eucalyptus, tea tree, white thyme, lemon, lemongrass, clove bud oil and oil combinations were tested in the agar diffusion test against clinically relevant strains and multi-resistant nosocomial isolates. Ethanol, povidone iodine, chlorhexidine as well as olive and paraffin oil served as controls. The essential oils tested showed clear antimicrobial effects against staphylococci, streptococci and candida. In particular, the absolute impact on multi-resistant strains such as MRSA and Candida krusei should be stressed. The anti-inflammatory properties of essential oils may be advantageous in dental implantology compared to classic antiseptics. Essential oils can be produced naturally and cost-effectively. If the suspected antimicrobial effects can be confirmed against the dominant strains in peri-implant infections, essential oils may offer an alternative in the local treatment of these infections.

Keywords: Essential oils, antimicrobial, peri-implant infection, multi-resistant strains, MRSA, antiseptics

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