Research

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Issue: 03/2010 - S. Vogel - L. Ricken
Survival rate of immediately loaded implants

The demands of our patients regarding an implantological treatment are continuously increasing. Not least the widespread idea of “theeth in an hour” sets the implantologist under pressure. Regardless of the individual prepositions it is suggested that this concept is always practicable. Such statements are wrong in the same way as a generaly denegation of an immediate loading. The aim of our investigation was to find out the survival rate of immediately loaded implants under clearly defined conditions. 256 immediately loaded implants in 56 patients were observed during an average period of 34.7 months. With a survival rate of 99.21 % it is shown that this protocol of loading is successful under restrict adherence to the indication.

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ORIGINAL STUDY
Issue: 01/2010 - S. Heberer - L. Hohl
Clinical results with acid-etched implants in edentulous patients: a prospective multicenter study

The aim of this prospective study was to evaluate the clinical parameters of acid-etched implants up to one year after loading. The study examined 135 wi.tal implants placed in the maxilla and mandible of 27 edentulous patients. The healing time in the maxilla was twelve weeks and in the mandible eight weeks. The implants were checked at defined intervals based on the success criteria of Buser and clinical parameters like mPII, mBI and pocket depths were evaluated. All patients had standardized orthopantomographs for evaluation of peri-implant bone loss after implant placement, at loading, after six months and after twelve months.

69 implants were placed in the maxilla and 66 in the mandible. During the observation period three implants failed, resulting in a success rate of 97.7 % for the maxilla and 100% for the mandible. The results indicate that success rate of the present study is comparable to that of other studies. The bone level changes over the different time points fulfill the success criteria. Further studies are necessary to assess the long-term outcome.

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Issue: 02/2010 - W. Wagner - M. Kunkel - R. Nölken
Early implant placement, immediate reconstruction and provisionalization after long-axis root fracture and total loss of the facial bony lamella

Purpose: The aim of these case reports is to present the performance and advantages of a flapless surgical approach for early implant placement, simultaneous alveolar ridge augmentation and immediate provisionalization in case of total loss of the facial bony lamella due to long-axis root fracture for three upper incisors.

Materials and Methods: Three NobelPerfect Groovy implants were placed flapless as early implants three to eight weeks post extractionem in three patients (follow-up 23 to 26 months) who had sustained complete loss of the facial bony lamellae. The implants were inserted simultaneously with subperiosteal bone augmentation using autogenous bone chips and underwent immediate provisionalization. Outcome variables were implant success, marginal bone level and Pink Esthetic Score according to Fürhauser (PES).

Results: All implants achieved excellent primary stability. There were no implant losses. On average, the interproximal marginal bone level stabilized at 1.7 mm coronal to the first thread. Post-operative cone beam tomographies (CB-CT) at least 23 months post-operatively confirmed restoration and stability of the facial lamella. Marginal esthetics, as assessed by PES, yielded the very high mean score of 13 after a mean follow-up period of 24 months.

Conclusion: Survival rate, marginal bone level and esthetic results suggest that the principle of flapless early implant placement with simultaneous reconstruction of an extended crestal bony defect and immediate provisionalization in case of total loss of the facial bony lamella is a further therapeutic option in the anterior maxilla.

Abbreviations

CB-CT cone beam computed tomography

PES Pink Esthetic Score after Fürhauser

PFM Porcelain-fused-to-metal

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Issue: 04/2010 - S. Schultze-Mosgau - M. Mtsariashvili - C. K. Müller
Influence of different soft tissue management concepts on the rate of peri-implant inflammation and implant success

Purpose: The aim of this study was to investigate the influence of different soft tissue management concepts on the rate of peri-implant inflammation and on implant success using a one- and two-stage procedure.

Material and methods: In an animal study using the Göttingen minipig model, flapless and flap surgery were compared with regard to the rate of peri-implant inflammation. One month after extraction of all upper premolars, twelve pigs had two Semados RI implants (4.1 mm x 10 mm, BEGO Implant Systems, Bremen, Germany) inserted per quadrant. The pigs were randomized to have minimally invasive exposure by trephine punch in one quadrant. The ridge was exposed conventionally on the contralateral side by raising a mucoperiosteal flap. Biopsies of the soft tissue were taken after a transmucosal healing period of one, two, four and twelve weeks and histological examination and pangenomic gene expression analysis were performed. In a retrospective clinical study involving 181 patients (521 implants), the influence of the main and releasing incisions as well as the exposure technique on implant success was evaluated by means of Kaplan-Meier survival analysis.

Results: The minipig study showed significantly greater inflammatory infiltration of the peri-implant soft tissue one week (p = 0.016), two (p = 0.010) and twelve (p = 0.039) weeks after insertion after flap surgery compared with flapless surgery. Immunofluorescence analysis confirmed macrophage predominance after one and two weeks and the absence of macrophages after twelve weeks. Pangenomic gene expression analysis showed reduced inflammation and improved wound detoxification in the early healing phases and faster re-epithelialization and reduced fibrosis in later phases following flapless surgery. The retrospective clinical study showed a significant (p = 0.022) influence of the releasing incisions on the implant survival rate.

Conclusions: The results of the minipig study suggest that the rate of peri-implant inflammation can be reduced by flapless surgery due to improved soft tissue architecture. An effect on the implant success rate was not found. When a two-stage implantation procedure is employed, only a very short distal releasing incision should be made during implant insertion.

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Issue: 04/2010 - C. Pertl - M. Stopper - G. Dohr - R. Kirmeier - N. Jakse - M. Lorenzoni - M. Payer
Cell growth on different zirconia and titanium surface textures:
a morphologic in vitro study

Purpose: Aim of this study was to evaluate cell growth of human osteoblasts and fibroblasts on different zirconia and titanium surface textures with similar roughness values.

Materials and Methods: Five surface textures were tested: titanium machined (Ti m), titanium grit-blasted and acid-etched (Ti g+e), zirconia machined (ZrO2 m), zirconia grit-blasted (ZrO2 g) and glass slides (Gl contr). Both osteoblasts and fibroblasts were cultured under static, osteoblasts also under dynamic conditions. Morphology was evaluated with scanning electron microscopy (SEM); laser scanning microscopy (LSM) was used to obtain cell counts over five days. Collagen type I and alkaline phosphatase (ALP) secretion after 48 and 96 hours were used as markers of cell differentiation.

Results: Cells attached to all surfaces. Cell counts of both cell lines revealed no significant differences under static conditions, whereas under dynamic conditions significantly higher numbers of osteoblasts were present at day one and two on ZrO2 g and Ti g+e surfaces than on machined and glass surfaces. Collagen and ALP secretion after 48 h could be observed only on surfaces Ti g+e and ZrO2 g. Average roughness values (Ra) of Ti g+e, ZrO2 g were significantly higher than those of ZrO2 m, Ti m and Gl contr surfaces.

Conclusions: Within the limitations of in vitro results, surface roughness for zirconia as implant material seems to be beneficial for initial cell growth and metabolism as it has been established for titanium.

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Issue: 04/2010 - M. Trautwein - S. Wentaschek - H. Scheller - G. Weibrich
Comparative clinical examination of treatment with alumina
and zirconia crowns placed on single tooth implants

Aim: The aim of this clinical examination was to analyse the short-term results of all-ceramic zirconia abutments, which have been available clinically for some time (Procera AllZirkon), and frameworks retained on Brånemark implants in the posterior region and compare them with proven alumina crown systems (Procera AllCeram crowns) in a prospectively documented, controlled human study.

Materials and methods: A total of 20 patients each with one Procera crown (n = 10 zirconia, n = 10 alumina) were consecutively included in the study. Every patient participated in the follow-up two weeks and six months after the fitting of the restoration, which is an established routine in the Department of Prosthetic Dentistry, and the results of the examinations were prospectively documented. Any possible changes to the peri-implant soft and hard tissue architecture as well as the subjective overall aesthetic effect on patients and dentists (visual analogue scale – VAS) were analysed.

Results and conclusion: Based on the examined parameters similarly good tissue compatibility was established for the two routinely used framework materials. Analysis of the findings for the soft tissue situation (papilla index according to Jemt) indicated a slightly more favourable development in the group with zirconia superstructures. The subjective assessment of the aesthetics by the patient and dentist showed very good results for the two materials.

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Issue: 03/2010 - G. Dhom - A. Strohecker - P. Gehrke
Influence of interdental papilla length and interproximal contact point on the perception of esthetics in symmetric and asymmetric situations

Introduction: Reliable peri-implant soft tissue regeneration represents a complex surgical and prosthetic challenge. Due to clinical limitations, group-specific perceptions of gradual soft tissue alterations versus ideal situations seem to be of special interest especially if the viewer’s profession is taken into account.

Aim: The aim of the study was to assess the influence of papilla length and position of the interproximal contact space in symmetric and asymmetric situations by comparing the esthetic perception of dental professionals and laymen. Furthermore, it was determined which factors have affected the evaluation in case of deviations from the optimal standard in the anterior region.

Material and Methods: Based on an ideal, digitally optimized reference picture of an anterior region, sequential alterations of papillary length and position of crown-contact point were performed by digital imagery. The digitally altered pictures were rated and assessed based on a questionnaire by 105 dentists and 106 laymen. Statistical analysis included description and assessment of scaling parameters according to the Mann-Whitney U test, the Kruskal-Wallis test and the Chi quadrant test. A possible influence of age and gender in both groups as well as the professional and educational background of laymen and the professional degree of dental specialists were considered.

Results: The phenomenon of papillary loss with a resulting “black triangle” in the midline was detected at an early stage both by laymen and dental specialists. However, they were evaluated differently with respect to esthetic consequences. Laymen tolerated the gradual loss of papilla as long as the remaining interproximal space was filled completely with mucosa due to prolongation of the contact point and if a “black triangle” could be avoided. Asymmetric alterations of the contact point or papillary length in the lateral arch were assessed significantly more critically by clinicians.

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REVIEW
Issue: 02/2010 - B. L. J. Schmidt - K. A. Grötz
In which bisphosphonate patients am I allowed to place implants? A systematic review

Bisphosphonates (BP) result in a positive tissue balance in bone, largely due to the antiresorptive effects at the osteoclast level, but are associated with osteonecrosis of the jaws (ONJ), which is hard to treat. There have been several attempts to improve medical care for patients receiving bis-phosphonates through enhanced communication between physicians prescribing bisphosphonates and dentists. The aim is to minimize the risk of developing BP-ONJ. In this contentious field, implantation is of special importance; in the last 20 years, many (alleged) contraindications for implants have been put into perspective, but BP-ONJ may be a new one. The literature-based evidence reflects the limited current knowledge of the real risk of implant-related ONJ or implant loss due to BP-ONJ. Against the background of existing experiences, an algorithm for indications can be developed. Three criteria are of high clinical importance: (1) the individual’s BP-ONJ risk (which can be evaluated with the ASO control slip), (2) the increase or decrease in risk due to an implantation and (3) the necessity of augmentative procedures. This allows a methodical, understandable decision for each patient, regarding the suitability of implant-borne prosthetic rehabilitation.

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Issue: 03/2010 - N. Reichenbach - K.–L. Ackermann
Microbiological and genetical diagnostics for advanced risk profiles

Oral biofilms are deposits in the mouth in which various organisms are embedded in a matrix of extracellular polymer substances where they live together synergistically. Disturbances of the “oral” ecosystem are accompanied by proliferation primarily of bacteria that are intolerant or not readily tolerant of oxygen, which can lead to periodontitis or – in the case of implants – periimplantitis. In addition to conventional diagnostic methods, microbiological diagnostics are an important element in the assessment of the disease and in therapeutic decision-making when adjuvant systemic antibiotics are indicated alongside standard therapy. For identification of the causative microorganisms, we now have at our disposal molecular biological techniques as reliable diagnostic methods for the detection of periodontal pathogens. In the majority of cases, bacteria are detected at the DNA level. A key role is played by the genetic component of the clinical picture, which suggests that evaluation of interleukin polymorphism would be a good approach. Findings from recent studies on the detection of active matrix metalloproteinase-8 (aMMP-8) suggest that it is possible to identify – in the sense of expanded PA diagnostics – whether a tissue is biologically healthy or if collagenolytic tissue breakdown is actively occurring.

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Issue: 01/2010 - K. Stein - B. Al-Nawas
Indication of a preoperative antibiotic prophylaxis
for insertion of dental implants – A systematic review

The aim of this study was to review the available literature on the question of whether preoperative antibiotic prophylaxis during implant placement reduces the risk of implant failure in patients without general medical risk factors.

The literature search was done using the medical databases Pubmed, Medpilot and the Cochrane Library. A hand-search was performed in dental journals. The studies were selected using a systematic quality evaluation and a meta-analysis.

Eight studies fulfilled the inclusion criteria: neither of the two studies of evidence level I showed a significant difference in the early implant failure rate between the test and the control groups. The studies of evidence level II also showed only a minor positive effect of antibiotic prophylaxis. We performed an aggregation of the data of the prospective clinical studies with control groups, which naturally must be interpreted with appropriate caution as there was marked heterogeneity between the four studies. There, a statistically significant difference between the intervention and control groups was apparent, with antibiotic prophylaxis having a clearly positive effect on the early implant failure rate with a number needed to treat of 56.

Based on the present available evidence of “moderate quality”, a “weak recommendation” can be given for antibiotic prophylaxis with a penicillin during implant placement.

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