Research

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EDITORIAL
Issue: 01/2011
The Journal of Dental Implantology (JDI) goes online! (www.online-jdi.com)

The development of the internet has not only changed the market of continuing education and communication between practitioners but also enhanced the process and distribution of scientific publishing. Time consuming activities like visiting libraries and chasing references just to find an information on a particular treatment strategy or surgical technique have become an issue of the past. Large biomedical databases, like pubmed have become available over the internet and have dramatically increased the accessibility of the scientific and practical world literature. Because many of the people in the western countries have direct access to the internet, relevant rapid and complete literature searches as well as continuing education via the internet have fast become the norm. During the past few years, several of the larger journals on oral implantology have progressed electronically to become available “online”. We are proud to announce that the Journal of Dental Implantology (JDI) is joining this important development and is now available online via www.online-jdi.com. Consequently, an online version is offered to all of the subscribers in addition to the printed version.

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FROM PRACTITIONER TO PRACTITIONER
Issue: 02/2011 - C. Arndt - F.-A. Preusse - M. Suhr
Implant repositioning osteotomy for changing the position
of osseointegrated implants

The options in the treatment of fully osseointegrated implants in an incorrect or unusable position include not utilising the implant (“sleeping implant”), surgical removal of the implant and complete replanning, providing it with superstructure and accepting the situation, or performing an implant repositioning osteotomy (IRO). In the latter procedure, emphasis is placed on ensuring an adequate bone- and blood-supply and adequate fixation of the implant-bearing bony segment. This can be accomplished by wire or plate osseosynthesis, fixing abutments into a splint incorporating temporary crowns, or by bone-grafting and impaction. Adequate planning, obtaining an informed consent from the patient with presentation of all the options and frequent and repeated foto-documentation are essential components in ensuring an outcome acceptable to the patient.

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Issue: 03/2011 - S. Schulz - S. Dax - D. T. Weinhold - M. Dürholt
Comparison of lateral augmentation techniques

Question: A multitude of surgical techniques for the augmentation of vertical bones in connection with the insertion of dental implants is described in the relevant literature. The objective of the present article is to compare three techniques of vertical ridge augmentation on the basis of our medical records of patients who have undergone the described treatments in the past.

Method: The following methods were examined: spreading the alveolar ridge [12, 13, 14] by means of oscillating saws and spiral osteotomes, bone block grafts taken from the mandibular angle area [1, 4, 6, 11] and the use of absorbable membranes [3, 8]. All patients that complied with the guidelines of the DGZMK for the insertion of dental implants were registered. The patient population was not differentiated in more detail. Complete and partial loss of the augmentation material as well as a dehiscence of the suture were rated as complications [7].

Results: A complication rate of 3% was determined for the spreading of the alveolar ridge, the rate established for bone block grafts was 19% and that of the membrane techniques was 32%.

Conclusion: The spreading of the alveolar ridge showed significantly less complications than the other two augmentation techniques we examined. Due to the design of the study and the inhomogeneity of the patient group, this result was affected by a number of other factors which could not be included in the statistics. Prospective studies regarding this topic are desirable.

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ORIGINAL STUDY
Issue: 01/2011 - J. Zöller - Z. Mazor - T. Fienitz - A. Happe - R. Smeets - F. Schwarz - D. Rothamel
Sinus floor elevation using a sintered, natural bone mineral

Background: Implantological rehabilitation of the posterior maxilla often requires cranialization of the sinus floor to allow for long-term stability and permit the placement of sufficiently long implants. Well known as sinus floor elevation or sinus lift, this operation is one of the most common therapies for vertical deficits of the upper jaw.

Aim: The aim of the present study was the histological and clinical evaluation of the xenogeneic bone substitute material (BEGO OSS, Bego Implant Systems, Bremen) for the indications one-stage and two-stage sinus floor elevation.

Materials and method: Twelve patients were included in the study, undergoing 15 simultaneous or staged sinuslift operations. Data were evaluated clinically and, for two-stage approaches, histologically and histomorphometrically after trephine harvesting during implant bed preparation.

Results: Healing was uneventful in all cases. All patients showed good hard tissue regeneration of the lateral window of the sinus. Neither resorption nor dislocation of the granular bone substitute material was observed. Radiologically, good volume stability of the graft was observed. Histologically, bone substitute particles displayed complete osseous integration in newly formed bone matrix. The proportion of newly formed bone within the graft was 25.8–49.6 %, whereas the proportion of remaining bone substitute material varied from 28.6–38.5%.

Conclusion: It was concluded that BEGO OSS acts as an osteoconductive material to support hard tissue regeneration after sinus floor elevation. Showing excellent volume stability, it is integrated into newly formed bone matrix within a six-month healing period.

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Issue: 01/2011 - N. Gersdorff - M. Rödiger - F. vom Orde
Comparative microarray analyses of inflamed human periimplant and periodontal tissues in vivo

Purpose: The aim of the present in vivo study was a comparative gene expression analysis of inflamed periimplant and periodontal tissues to demonstrate potential differences between these two disease entities at the molecular level. The data presented here was combined from two published studies [7, 17].

Materials and methods: Using microarray technology, the gene expression profiles of inflamed periimplant tissue, inflamed and healthy periodontal tissue were analyzed and verified by real-time (RT) PCR. The main focus was on extracellular matrix components as well as on their degrading enzymes.

Results: In inflamed periimplant tissue, non-fibril-forming collagens types IV, VI, VII and XVII were up-regulated and the fibril-forming type III and XI collagens were down-regulated compared to inflamed periodontal tissue. In the group of matrix-degrading enzymes, the cathepsins B and C, the matrix metalloproteinases MMP-1 and MMP-9 were up-regulated and two tissue inhibitors of metalloproteinases, TIMP-1 and TIMP-3, were significantly up-regulated.

Conclusions: In summary, the results of the present study show that periimplantitis can be clearly differentiated from periodontitis at the molecular level. Comparison of these two oral diseases might be important for the objectification of disease-specific genes, and for the diagnosis, progress and prognosis as well as for the development of new periimplantitis therapies.

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Issue: 02/2011 - L.T. Kuhn - D.M. Shafer - M. Wei - B. Wen - M.A. Freilich - M. Karl
Guided vertical bone regeneration by means of roughened
and alkaline treated titanium implant surfaces

Introduction: To determine if an alkaline surface treatment would enhance vertical bone growth around sand-blasted, large grit, acid-etched (SLA) titanium implants in a rabbit mandible model.

Material and methods: A total of twelve New Zealand white rabbits received either SLA or alkaline-treated SLA implants placed in transverse orientation in the posterior mandible with the coronal 3mm of the implants left outside the bone. Three treatment groups (n=6 implants per group) were studied with or without demineralized bone matrix (DBM) scaffolds as follows: SLA/DBM, alkSLA/DBM or alkSLA alone. The DBM was stabilized by a scaffold retention screw. MicroCT imaging and histological analysis was performed on retrieved specimens after ten weeks of healing to assess new bone formation.

Results: For all parameters, except for bone volume fraction, the highest values were recorded for SLA implants plus DBM scaffolds. Bone-to-implant contact (BIC) in the newly-formed mass of bone above the original bone was not enhanced in the alkaline-treated group as compared to the SLA group (32.0% ± 13.5 vs. 55.7% ± 12.8; p=0.0152). Significantly less new bone formed around alkaline-treated implants when they were placed without DBM scaffolds (e.g. bone height with DBM: 1.9mm ±0.3, without DBM: 0.3mm±0.5; p = 0.0312).

Discussion: Alkaline treatment of commercially available SLA implants did not enhance vertical bone regeneration or bone-to-implant contact in combination with DBM in this animal model.

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Issue: 02/2011 - S. Schultze-Mosgau - C. K. Müller - J. Chen - S. Fröbisch
Evaluation of the influence of preoperative factors
on soft tissue consolidation around single tooth implants
in the esthetic zone – A pilot study

Aim: The study aimed at identifying patient-, defect- and treatment-related factors that influence the esthetic outcome following oral rehabilitation using single tooth implant crowns.

Materials and Methods: 34 patients, who received a total of 49 dental implants at the Department of Oral and Maxillofacial Surgery/Plastic Surgery, Jena University Hospital, were analyzed in a pilot study. Patient-, defect- and treatment-related factors were documented. Employing the "Pink Esthetic Score" (PES), the "red esthetics" were judged on standardized intraoral photos. The influence of patient-, defect- and treatment-related factors on the PES score was analyzed in a multivariate statistical approach.

Results: Defect size, SAC class and the condition of periimplant bone were found to be significant variables in the description of the PES.

Conclusion: Within the limitation of a pilot study employing a small sample size, it was confirmed that insufficient hard and soft tissue represents the greatest challenge for the implantologist. Current developments in minimally invasive implantology might have the potential to enhance the esthetic outcome in the future.

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Issue: 03/2011 - P. Gehrke - H. Schliephake - D. Siebers
Immediate Function in a Dental Practice

Objectives: The aim of this study was to clarify whether immediate function or immediate loading in a private practice may be regarded as a safe treatment protocol for selected cases. This question is addressed using a longitudinal case control study of patients in a private practice.

Material and Methods: All 111 implants that had been treated according to an immediate function protocol between 2001 and 2004 were followed up. 111 implants with parameters as similar as possible served as controls. 96 parameters in 76 patients were recorded and analyzed. These included numerous risk factors mentioned in the literature, implant and denture parameters, and clinical and radiographic parameters. The implant success rate was evaluated and an aesthetic assessment of a reasonable proportion was performed.

Results: Five of the 222 implants were lost during the healing period (survival rate 97.7% after 3.25years on average). The Kaplan-Meier analysis showed statistically significantly better results for the control group (survival rate 100%) compared with the test group (survival rate 95.5%, p=0.024) as well as for implantation in healed sites (99.4%, p=0.0055) compared with immediate implantation (93.1%). Evaluation of implant success resulted in a success rate of 97.75% (Gettleman/Schnitman) and 95.5% (Buser/Naert). The success rate was statistically significantly higher with delayed compared with immediate implantation (p=0.017). The test group had significant advantages aesthetically compared with the control group (p=0.0074).

There were also advantages for immediate compared with delayed implantation (p=0.0076) and for the test group compared with the control group (p=0.0092). The probing depth was less in the test group than in the control group (p=0.011) and with immediate loading compared with the immediate restoration group (p=0.025).

Conclusions: Immediate function of dental implants is a therapy with a high success rate of 95.5% and high aesthetic potential. However, there is evidence that immediate function and immediate implantation are associated with a higher risk of failure. Therefore, an accurate risk analysis is required for each patient to avoid risk accumulation.

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Issue: 04/2011 - M. Wolkewitz - B. Koller - S. Cepa - R. Kohal
Implant-retained prostheses: ball vs. conus attachments – A randomized controlled clinical trial

Purpose: The aim of the present study was to evaluate implant survival, peri-implant soft and hard tissue conditions, prosthodontic maintenance and patient satisfaction for implant-supported mandibular overdentures retained with ball attachments or prefabricated conical crown attachments during a 2-year period.

Materials and methods: 25 patients with edentulous mandibles received two oral implants in the mandibular interforaminal region. The denture attachment system was chosen randomly. Twelve patients received ball attachments and 13 patients received prefabricated conical crown attachments. Implant survival, peri-implant soft and hard tissue conditions such as probing depth (PD), modified plaque index (mPlI), bleeding on probing (BOP), modified gingival index (mGI), horizontal bone loss (HBL) and patient satisfaction were assessed for each patient. In addition, detailed prosthodontic maintenance interventions were monitored during the follow-up period.

Results: The implant survival rate was 100%. There were no significant differences in PD, mPlI, BOP, mGI and HBL between the two groups. Within the two-year evaluation period prosthodontic intervention was required for 80% of the patients in the ball attachment group and 75% of the patients in the conical crown group. After two years, patient satisfaction in the ball group (82%) was higher than in the conical crown group (60%).

Conclusion: The results indicate that both attachments (ball attachment, conical crown attachment) used on two implants in the edentulous mandible show similar clinical results. However, the maintenance of both attachment groups is high. Due to the need for extensive maintenance, regular recall is fundamental for both attachment systems.

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STATEMENT
Issue: 01/2011 - H. Wehrbein - F. P. Strietzel
The use of implants for skeletal anchorage in orthodontics

F. P. Strietzel1, H. Wehrbein2

Introduction

Endosseous implants for orthodontic anchorage are used more and more frequently in orthodontic treatment for movement of larger groups of teeth or single teeth without loading other teeth. Also, in situations with no or only very limited existing conventional anchorage options in the case of hypodontia, after tooth loss or in patients with periodontally compromised teeth, implants for orthodontic anchorage provide an alternative to extraoral anchorage.

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