Katja Nelson

Publications of Katja Nelson

• Bone physiology in human grafted and non-grafted extraction sockets - an immunohistochemical study.

  Authors: Susanne Nahles, Claudia Nack, Kerrin Gratecap, Hermann Lage, John J Nelson, Katja Nelson

  Clinical oral implants research. 03/2012;

  PURPOSE: The aim of the present immunohistological investigation was to define and compare the osteogenic potential with the vascularization of the provisional matrix in grafted and ungraftedPURPOSE: The aim of the present immunohistological investigation was to define and compare the osteogenic potential with the vascularization of the provisional matrix in grafted and ungrafted extraction sockets after 4 and 12 weeks of healing. METHODS: A total of 33 Patients (15 women, 18 men) with 65 extraction sites with a mean age of 54.4 years (30-73 years) participated in this study. After tooth extraction, the sockets were augmented with Bio-Oss collagen or non-augmented. At implant placement after 4 or 12 weeks bone biopsies were obtained. Within the specimens the osteogenic and endothelial potential of mesenchymal cells was analyzed in the provisional matrix using immunohistochemical analysis with three monoclonal antibodies Cbfa1/Runx2, Osteocalcin (OC), and CD31. Statistical analysis was performed using Mann-Whitney U-test, Spearman's rank-order correlation coefficient, and the two-factorial analysis for repeated measurements. RESULTS: Of the 65 extraction sockets, 25 (13 non-augmented, 12 augmented) sites after 4 weeks healing time and 40 (19 non-augmented, 21 augmented) sites after 12 weeks healing time were involved in the study. No signs of acute or chronic inflammation were noted in any specimens. After 4 weeks, a median amount of 56% (10-85%) of Cbfa1 positive cells and a median amount of cells expressing OC of 21% (5-42%) were measured. A median CD31 score of 5 was observed. After 12 weeks, a median amount of 61% (19-90%) positive cells expressed by Cbfa1/Runx2 staining a median amount of OC positive cells of 9% (2-17%) was measured. The results at 12 weeks revealed a median score of CD31 positive cells of 3. DISCUSSION: Osteoblastic activity in the provisional matrix was highest after 4 weeks of healing period. The active zone of bone formation is found in the apical region of the extraction socket during the early healing phase, shifting to the coronal region after 12 weeks. A peak of osteoblast activity within the first weeks is followed by a reduction in mature osteoblasts with osteoblasts remaining in an inactive stage. The vascularity changed in likewise fashion to the maturation of osteoblasts within the observation period. The results have shown that with increasing age a decreasing endothelial potential was observed not after 4 weeks, but after 12 weeks, thus it suggests that angiogenesis is diminished in older patients in the later phase of healing in extraction sockets.

• Analysis of soft tissue display in Chinese subjects during an enjoyment smile.

  Authors: Xiulian Hu, Ye Lin, Susanne Heberer, Katja Nelson

  Quintessence international (Berlin, Germany : 1985). 02/2012; 43(2):105-10.

  Due to global migration, clinicians often see patients with different ethnic backgrounds. Planning esthetic prosthodontic treatment for patients with different ethnicities can be a challenge. The aimDue to global migration, clinicians often see patients with different ethnic backgrounds. Planning esthetic prosthodontic treatment for patients with different ethnicities can be a challenge. The aim of this study is to analyze the smile features of Chinese individuals. Sixty-two Han-Chinese subjects with a mean age of 28.5 years were enrolled and photographed. Standardized digital photographs were made to measure the height of displayed maxillary gingivae, papillae, and teeth during an enjoyment smile. The data were then compared with the data acquired from Caucasians in a previous study. Statistical analysis was performed using the Mann-Whitney test and two-factorial nonparametric analysis. The mean display of the central incisors was 10 mm, with no significant difference between sexes (P = .74). The mean amount of display of the molars and premolars was significantly lower in Chinese (P < .001) than in Caucasians. The mean displayed gingiva in all subjects (n = 62) was 1.3 mm (0 to 8 mm). There was no significant difference between sexes (P > .05), but there was a significantly lower display of gingiva at the molars in Chinese (P < .001). Of all the subjects, 16.1% (n = 10) displayed gingivae from the central incisor to the first molar with a mean gingival height of 2.8 mm. The subjects showed a mean papilla height of 3.4 mm (0 to 11.6 mm) with no significant difference between sexes (P > .05). Again, a significantly lower display of papilla at the molar (P < .001) was found in Chinese. Of all subjects, 43.5% (n = 27) of all subjects showed papilla from the central incisor to the first molar. The mean papilla height of these subjects was 3.9 mm. All subjects displayed at least one papilla. The results indicate that pink esthetics is a prime factor for both Chinese men and women in the esthetic restoration from the central incisors to the premolars.

• [Measurement and analysis of smile line of 62 Han-Chinese].

  Authors: Xiu-lian Hu, Susanne Heberer, Katja Nelson, Ye Lin

  Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology. 11/2011; 46(11):660-4.

  To analyze smile features in maximum lip-dynamic in Chinese. Sixty-two Han-Chinese, travelling in Germany, with a mean age of 28.5 years were enrolled and photographed. Standardized digital photosTo analyze smile features in maximum lip-dynamic in Chinese. Sixty-two Han-Chinese, travelling in Germany, with a mean age of 28.5 years were enrolled and photographed. Standardized digital photos were made to measure the height of displayed maxillary gingiva, papilla and tooth during an enjoyment smile. Statistical analysis was performed using Mann-Whitney-U Test and non-parametric analysis. The mean height of tooth display for the central incisors was 10 mm, with no significant difference between the gender (P > 0.05). The mean height of gingival display was 1.3 mm and the mean papilla height was 3.4 mm. There was no significant difference between the genders (P > 0.05). 31% (19/62) of the subjects belonged to high smile line type, 50% (31/62) to medium smile line type and 19% (12/62) to low smile line type. The red esthetics is a paramount factor for Chinese men and women in the esthetic restoration. 81% of the Chinese studied showed various degree of gingival exposure from central incisor to the premolars, which defined the esthetic area for Chinese people. Papilla is a critical parameter for esthetic evaluation and treatment design. The ratio of high smile line in Chinese may be higher than that in Caucasian.

• Osteogenic potential of mesenchymal cells embedded in the provisional matrix after a 6-week healing period in augmented and non-augmented extraction sockets: an immunohistochemical prospective pilot study in humans.

  Authors: Susanne Heberer, Alexander Wustlich, Hermann Lage, John J Nelson, Katja Nelson

  Clinical oral implants research. 03/2011; 23(1):19-27.

  The aim of the present clinical study was the evaluation of the osteogenic potential of mesenchymal cells embedded in the provisional matrix of non-augmented and with Bio-Oss collagen-augmented humanThe aim of the present clinical study was the evaluation of the osteogenic potential of mesenchymal cells embedded in the provisional matrix of non-augmented and with Bio-Oss collagen-augmented human extraction sockets after 6 weeks of healing time. Twenty-five patients with 47 extraction sites participated in the present study. After tooth removal, the extraction sockets were augmented with Bio-Oss collagen or not augmented. At implant placement, bone biopsies of the extraction sockets were obtained. The immunohistochemical analysis of the osteogenic potential of the mesenchymal cells in the provisional matrix was performed using three monoclonal antibodies: core-binding factor α1 (Cbfa1)/runt-related protein (Runx)2, osteonectin (OSN/secreted protein acidic and rich in cyst [SPARC]) and osteocalcin (OC). The statistical analysis was performed using two-factorial analysis for repeated measures, Mann-Whitney U-test and Spearman's rank-order correlation coefficient. Of 47 extraction sockets examined, 17 sockets demonstrated an almost complete ossification. Hence, the provisional matrix of the 30 remaining extraction sockets (21 non-augmented, 9 augmented) was immunohistochemically investigated. No evidence of acute or chronic inflammation was noted in any of the specimens. In the provisional matrix of the non-grafted socket, the median amount of Cbfa1/Runx2-positive cells was 72.3%, of OSN (SPARC) 66.9% and of OC 23.4%, whereas in the grafted sockets the median rate of immunopositive cells staining with Cbfa1/Runx2 was 73.3%, of OSN (SPARC) 61.4% and of OC 20.1%. There was no significant difference in the proportion of positive cells expressed by Cbfa1/Runx2, OSN/SPARC and OC between the grafted and non-grafted socket. Furthermore, the cell density did not correlate to the quantity of stained cells independent of the used proteins. After a 6-week healing period, the provisional matrix was demonstrated to have a high proportion of cells displaying a maturation of mature osteoprogenitor cells to osteoblasts. The grafting procedure did not influence the quantity of osteogenic cells in the extraction socket.

• Effect of dehiscences to the bone response of implants with an Acid-etched surface: an experimental study in miniature pigs.

  Authors: Baerbel Ruehe, Susanne Heberer, Katja Bayreuther, Katja Nelson

  The Journal of oral implantology. 01/2011; 37(1):3-17.

  Spontaneous early exposure of submerged implants during the healing phase as a factor for early crestal bone loss around the implants is still being controversially discussed. The aim of this studySpontaneous early exposure of submerged implants during the healing phase as a factor for early crestal bone loss around the implants is still being controversially discussed. The aim of this study was to examine the potential impact of dehiscences on the osseointegration process of acid-etched dental implants with a shortened healing period in the maxilla. Five animals received a total of 15 titanium implants 8 weeks postextraction. Eight of these implants were placed in the maxilla to osseointegrate within a shortened healing period of 3 months, whereas the remaining implants were inserted in the lower jaw and served as controls with a regular healing time. Polyfluorochrome sequential labeling with xylenol orange, calcein green, and alizarin complexone was performed 2, 5, and 8 weeks after implant placement. After 12 weeks of unloaded and submerged healing, the animals were killed and the implants removed en bloc. After the processing of the undecalcified PMMA-embedded samples, thin ground sections (40-60 µm) were made. The histomorphometric determination of the bone-to-implant contact (BIC) was calculated using light microscopy. The peri-implant bone apposition rate and the direction of bone growth were determined with the fluorescence microscope. For statistical evaluation, the Mann-Whitney U test, Wilcoxon signed ranks test, and Friedman test were chosen. During the healing period, nonartificial dehiscences were observed at 9 implants. The average BIC was 54.19% (14.51%-68.97%). There were significantly lower BIC rates detected for the cervical part of the implants compared with the middle part. An influence of dehiscences on the osseointegration could not be proven. There were no significant differences between the BIC values of the upper and lower jaw. During the observation period from the third to the eighth week after implantation, the average new bone formation rate was 2.32 µm/d (1.76-2.82 µm/d). During this period, the amount of new bone growth decreased insignificantly. Based on the sequence of the polyfluorochrome labeling, an implantopetal (53.03%) as well as an implantofugal bone growth (46.97%) have been observed. It could be assumed that the acid-etched implants offered a prerequisite to osseointegrate under a shortened healing period. The observed dehiscences seemed not to have compromised the rate of osseointegration.

• Rehabilitation of irradiated patients with modified and conventional sandblasted acid-etched implants: preliminary results of a split-mouth study.

  Authors: Susanne Heberer, Sevtap Kilic, Jaber Hossamo, Jan-Dirk Raguse, Katja Nelson

  Clinical oral implants research. 12/2010; 22(5):546-51.

  The aim of this study was to evaluate the success rate of chemically modified and conventional sandblasted acid-etched surface (SLA) titanium implants in irradiated oral squamous cell carcinomaThe aim of this study was to evaluate the success rate of chemically modified and conventional sandblasted acid-etched surface (SLA) titanium implants in irradiated oral squamous cell carcinoma patients. Twenty patients with a mean age of 61.1 years were treated with dental implants after ablative surgery and radio-chemotherapy of oral cancer. All patients were non-smokers. The placement of SLA and modSLA implants was performed bilaterally according to a split-mouth design. All 102 implants (50 SLA, 52 modSLA) placed showed an unloaded healing time of 6 weeks in the mandible and 10 weeks in the maxilla. Mean crestal bone changes using standardized orthopantomographies and clinical parameters like pocket depths, mPII and mBI were evaluated. Of 102 implants, 55 implants (27 SLA implants, 28 modSLA) were located in the maxilla and 47 implants (23 SLA, 24 modSLA) in the mandible. The average observation period was 14.4 months. The amount of bone loss at the implant shoulder of SLA implants was 0.4 mm mesial and 0.4 mm distal. The modSLA implants displayed a bone loss of mesial 0.3 mm and distal 0.3 mm. Two SLA implants were lost resulting in a success rate of 96%. The success rate of modSLA implants was 100%. Regarding the data found in this investigation, we can conclude that implants with chemically modified and conventional SLA titanium surface show high success rates in irradiated patients. SLA implants with or without a chemically modified surface regardless of the location can be restored with a high predictability of success at least in the short time range observed.

• Maxillary sinus augmentation following removal of a maxillary sinus pseudocyst after a shortened healing period.

  Authors: Ye Lin, Xiulian Hu, Arnulf-Reimar Metzmacher, Haiyan Luo, Susanne Heberer, Katja Nelson

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 11/2010; 68(11):2856-60.

  Dome-shaped radiopacities on the floor of the maxillary sinus are commonly interpreted as a sinus cyst on radiographs during dental implant planning. They might present an obstacle in sinus grafting,Dome-shaped radiopacities on the floor of the maxillary sinus are commonly interpreted as a sinus cyst on radiographs during dental implant planning. They might present an obstacle in sinus grafting, leading to bone graft failure or implant loss later. The therapeutic approaches to the removal of such cystic lesions and the following sinus augmentation are still controversial. The purpose of this article is to present a modified technique that can be used for predictable removal of a maxillary sinus cyst and sinus augmentation after a shortened healing period in patients with maxillary sinus pseudocysts. A total of 11 patients with a mean age of 43.7 years with a radiographic dome-shaped opacity in the posterior maxilla sinus were included in this study. A lateral sinus window (with a diameter of about 5 mm) was prepared, and removal of the cyst was performed with grasping forceps. Three months after removal of the cyst, a conventional sinus augmentation with xenogeneic material was undertaken. Dental implants were placed 6 months later. Panoramic radiography and coronal/axial computed tomography were performed to diagnose the sinus lesion preoperatively and for follow-up. A total of 11 pseudocysts were removed from the sinuses of 11 patients under local anesthesia. Histologic evaluation showed antral pseudocysts in all specimens. A soft tissue scar was evident after 3 months of healing at the time of sinus augmentation. No sinus membrane perforation was seen or occurred during the sinus augmentation. A total of 17 implants were placed and restored prosthetically. No clinical complications were observed. The patients were followed up for a mean of 29.2 months (range, 17-43 months) after prosthetic loading, during which no implants were lost and no recurrence of the antral pseudocyst was observed. The described modified surgical technique allows the minimally invasive removal of the antral pseudocyst and histologic verification of the diagnosis without compromising the nasoantral entrance as well as the anatomy of the sinus for future sinus augmentations. It can be performed under local anesthesia without endoscopic equipment while shortening the treatment period.

• Clinical evaluation of a fixed (retrievable) implant-supported prosthesis in the edentulous jaw: a 5-year report.

  Authors: Xiang Lixin, Xiulian Hu, Juergen Mehrhof, Katja Nelson

  Quintessence international (Berlin, Germany : 1985). 04/2010; 41(4):277-83.

  This retrospective study evaluated the success rate of a fixed retrievable prosthesis based on an electroforming technique combining the advantages of screw- and cement-retained principles. FortyThis retrospective study evaluated the success rate of a fixed retrievable prosthesis based on an electroforming technique combining the advantages of screw- and cement-retained principles. Forty patients (17 men and 23 women) with a mean age of 62.2 years were treated. A total of 353 implants were placed in the edentulous maxilla, mandible, or both jaws to allow prosthetic rehabilitations with 55 fixed prostheses. Clinical success of the implants was based on the criteria of Buser. Technical complications monitored throughout the wearing period are described. Retrievability of the restoration with a conventional crown remover was checked at 6, 12, and 36 months. The cumulative survival rate of the implants was measured. After a mean observation period of 4.08 years (range 22 to 62 months), a cumulative survival rate of 99.15% was recorded for the 234 maxillary implants (234 Camlog RootLine, Camlog) and for the 119 mandibular implants (72 Camlog RootLine, 47 Camlog ScrewLine). Three implants failed before prosthetic loading. Monitored technical complications were seen in 10.91% of the restorations; they comprised ceramic chip-off and relining. This fixed implant-retained prosthesis based on electroforming indicates a comparable clinical efficacy to other techniques and allows scheduled retrieval.

• Miniature pigs as an animal model for implant research: bone regeneration in critical-size defects.

  Authors: Baerbel Ruehe, Stefan Niehues, Susanne Heberer, Katja Nelson

  Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics. 09/2009;

  OBJECTIVE: Standardized experimental investigations determining the critical-size defect (CSD) in the mandible of miniature pigs are still lacking. The aim of the present study was to obtainOBJECTIVE: Standardized experimental investigations determining the critical-size defect (CSD) in the mandible of miniature pigs are still lacking. The aim of the present study was to obtain information about the new bone formation in created defects of varying sizes. STUDY DESIGN.: Marginal resection of the alveolar crest of the lower jaw was performed in 3 female miniature pigs. The animals used in the study were 3 years of age and weighed approximately 55 kg. For histologic evaluation the dental implants were harvested with the surrounding bone tissue 10 weeks after implant placement. For this, bone segments including the implants were removed from each side of the mandible. The sizes of the resected bone blocks varied, showing the following volumes: 10.1 cm(3), 4.2 cm(3), and 1.9 cm(3). Periosteal coverage of the defects was performed. Computerized tomography (CT) of the skull of the miniature pig was performed immediately after the surgical procedure as well as 6 weeks later using a 64-channel mult-slice scanner. RESULTS.: The CT showed that 6 weeks after obtaining the biopsies, the filling of the defects with new bone varied. The percentage of newly formed bone in relation to the size of the original defect was 57.4% for the small- and 87.2% for the middle-sized defect. The large-sized defect showed 75.5% newly formed bone compared with baseline. CONCLUSION.: Considering the amount of new bone formation found within this study, it is questionable if the critical defect size of 5 cm(3) stated in the literature is valid. Further research concerning the mandibular model in minipigs is required and more refinement needed to assure a standardized CSD, allowing qualitative and quantitative evaluation of bone grafts and bone graft substitutes.

• Stable vertical distraction osteogenesis of highly atrophic mandibles after ablative tumour surgery of the oral cavity - a salvage pathway for mandibular reconstruction prior to oral rehabilitation with dental implants.

  Authors: Nicolai Adolphs, Christoph Sproll, Jan-Dirk Raguse, Katja Nelson, Susanne Heberer, Christian Scheifele, Martin Klein

  Journal of cranio-maxillo-facial surgery : official publication of the European Association for Cranio-Maxillo-Facial Surgery. 07/2009;

  Mandibular reconstruction is still a challenge for surgeons. Distraction osteogenesis (DO) might contribute in certain instances to solve this problem. A principal advantage of DO is the expansion ofMandibular reconstruction is still a challenge for surgeons. Distraction osteogenesis (DO) might contribute in certain instances to solve this problem. A principal advantage of DO is the expansion of the surrounding soft tissues that accompanies the bony regeneration. In addition there is no donor site morbidity when compared with reconstruction by autologous bone grafting. However its application may be limited by the thinness of the mandible and the attendant fracture risk. This article describes a technique that combines stable internal fixation with vertical distraction of the alveolar ridge in six patients with critical mandibular thickness after ablative surgery for cancer of the oral cavity. Prior to implant insertion for further prosthodontic restoration stable vertical mandibular distraction produced an additional 11-20mm. Improvement of the surrounding soft tissues, especially intraorally was achieved and dental implants were inserted after bony consolidation. This method can be a useful salvage technique for the augmentation of the atrophic mandible in patients who are not able or willing to undergo the risks and disadvantages of established methods such as free autologous bone transfer or microsurgical techniques.

• A prospective randomized split-mouth study comparing iliac onlay grafts in atrophied edentulous patients: covered with periosteum or a bioresorbable membrane.

  Authors: Susanne Heberer, Bärbel Rühe, Leif Krekeler, Tania Schink, John J Nelson, Katja Nelson

  Clinical oral implants research. 04/2009; 20(3):319-26.

  Purpose: In this prospective study, solid monocortical iliac onlay grafts of the maxilla were randomly covered with a bioresorbable membrane and periosteum within the maxilla. Histologic specimensPurpose: In this prospective study, solid monocortical iliac onlay grafts of the maxilla were randomly covered with a bioresorbable membrane and periosteum within the maxilla. Histologic specimens were analyzed by light microscopy after a healing period of three months and the rate of resorption of the grafts were measured. Materials and methods: Fourteen patients (9 females and 5 males), with a mean age of 56 years (range 25-72) underwent augmentation with avascular iliac onlay bone grafts. The grafts were randomly covered either with a bioresorbable membrane (MC) or periosteum (PC). Resorption was measured with a digital caliper at the microscrews (slashed circle1.5 mm) used to fixate the graft. Histologic evaluation of the specimens derived from the graft with a trephine bur (slashed circle2 mm) from the implant site at implant placement after a 3-month healing period. Statistical evaluation of the data was performed using Analysis of variance and the Wilcoxon signed rank test. Results: Clinical appearance of the augmented bone after 3 months showed a dense cortical layer with good vascular perfusion. Thirty-three sites in 13 patients (one dropped put) were analyzed histomorphometrically and showed an average of 46% newly formed bone with no significant difference between the groups (P=0.46). The mean resorption rate at 56 measured sites was 1.2 mm (range 0.3-3.4 mm) after 3 months, with no significant difference between the MC sites and the PC sites (P=0.38). Discussion: Histomorphometry of new bone formation after 3 months demonstrates no significant difference between the PC and MC groups. Initialization of graft resorption can be seen after 3 months with no significant difference as to whether the graft was covered with a membrane or the periosteum. Conclusion: This study provides evidence that after avascular iliac bone grafting, the revascularization of the graft was sufficient after 3 months regardless of the graft coverage with no effect on the amount of initial resorption of the graft. To cite this article: Heberer S, Rühe B, Krekeler L, Schink T, Nelson JJ, Nelson K. A prospective randomized split-mouth study comparing iliac onlay grafts in atrophied edentulous patients: covered with periosteum or a bioresorbable membrane. Clin. Oral Impl. Res. 20, 2009; 319-326. doi: 10.1111/j.1600-0501.2008.01638.x.

• Clinical evaluation of a modified method of vestibuloplasty using an implant-retained splint.

  Authors: Susanne Heberer, Katja Nelson

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 04/2009; 67(3):624-9.

  PURPOSE: Oral rehabilitation of resected tumor patients often requires, besides the use of dental implants, the improvement of the soft tissue condition. In this clinical report, we describe a simplePURPOSE: Oral rehabilitation of resected tumor patients often requires, besides the use of dental implants, the improvement of the soft tissue condition. In this clinical report, we describe a simple and effective surgical and prosthetic treatment procedure to achieve adequate long-term soft tissue conditions. MATERIALS AND METHODS: Seventeen tumor patients were selected for this evaluation. A total of 68 implants were placed in the mandible. At implant placement, a closed impression was taken from the implants for the fabrication of an implant-retained surgical splint. At second-stage surgery, vestibuloplasty by use of a split-thickness skin graft from the upper thigh was performed and an implant-retained splint was positioned. Pocket depths at the implants and the size of the graft were monitored over a period of 2 years. Statistical analysis by use of nonparametric 2-factorial analyses for repeated measures was performed. RESULTS: The mean mesial and distal pocket depths remained stable and measured 2.56 mm and 2.64 mm, respectively, at 24 months postoperatively. The graft showed an overall shrinkage of 18.5% in the vertical direction and 10.4% in the horizontal direction after 24 months. The shrinkage of the vertical direction compared with the horizontal direction showed a significant difference (P= .035). The shrinkage tendency was less than that described in the literature. CONCLUSIONS: The applied method described an easy, sufficient surgical procedure that minimizes shrinkage and creates a denture-bearing area that is stable over the long term, thus representing an improvement over previous methods.

• Histomorphometric analysis of extraction sockets augmented with Bio-Oss Collagen after a 6-week healing period: A prospective study.

  Authors: Susanne Heberer, Bassem Al-Chawaf, Detlef Hildebrand, John J Nelson, Katja Nelson

  Clinical oral implants research. 01/2009; 19(12):1219-25.

• Fabrication of a Fixed Retrievable Implant-supported Prosthesis Based on Electroforming: A Technical Report.

  Authors: Katja Nelson, Detlef Hildebrand, Juergen Mehrhof

  Journal of prosthodontics : official journal of the American College of Prosthodontists. 09/2008;

  This article describes a method of fabricating a fixed retrievable implant-retained prosthesis based on electroforming. This method combines the advantages of both the cement- and screw-retainedThis article describes a method of fabricating a fixed retrievable implant-retained prosthesis based on electroforming. This method combines the advantages of both the cement- and screw-retained prostheses, including passive fit, ease of fabrication, and retrievability. The absence of visible occlusal screw-canals adds to its increased esthetic appeal.

• Sudden death in miniature pigs.

  Authors: Baerbel Ruehe, Olivia Kershaw, Stefan Niehues, Katja Nelson

  Lab animal. 03/2008; 37(2):65-6, 68-9.

• Estradiol, tamoxifen and ICI 182,780 alter alpha3 and beta1 integrin expression and laminin-1 adhesion in oral squamous cell carcinoma cell cultures.

  Authors: Katja Nelson, Victor Helmstaedter, Cynthia Moreau, Hermann Lage

  Oral oncology. 02/2008; 44(1):94-9.

  Adhesion molecules such as integrins and extracellular matrix proteins like laminins have been identified to play an important role in cell proliferation, migration and invasion by regulatingAdhesion molecules such as integrins and extracellular matrix proteins like laminins have been identified to play an important role in cell proliferation, migration and invasion by regulating cell-extracellular matrix interaction in various cancers including oral squamous cell carcinoma (OSCC). In this study, the effect of estradiol (E2), and the E2 antagonists tamoxifen (TAM) and ICI 182,780 (ICI) on the expression of integrins and adhesion to laminin-1 in different OSCC in vitro models was analyzed. TAM and ICI inhibited growth in all OSCC cell lines. Dependent on estrogen receptor (ER) status E2 displayed a significant influence on growth after long-term administration. ICI reduced laminin-1 adhesion in all cell lines. beta1 Integrin transcription is reduced with TAM and E2 and alpha3 cell surface expression with TAM. This study shows that OSCC is estrogen and SERM sensitive and that these compounds can modulate cell-matrix interaction in part by modulating integrin expression and translation. The investigation also confirms that growth is significantly influenced by these adjuvant therapeutics. These data suggest that a greater understanding of basic biology and mechanisms of the ER and its ligands in oral squamous cells is needed to elucidate the use of specific pharmacological agents as therapeutics of anti-tumorigenic pathways.

• Survival analysis and clinical evaluation of implant-retained prostheses in oral cancer resection patients over a mean follow-up period of 10 years.

  Authors: Katja Nelson, Susanne Heberer, Corvin Glatzer

  The Journal of prosthetic dentistry. 12/2007; 98(5):405-10.

  STATEMENT OF PROBLEM: Dental implants have been increasingly used for prosthodontic rehabilitation of patients following oral tumor resection and postsurgical radiotherapy. However, only a fewSTATEMENT OF PROBLEM: Dental implants have been increasingly used for prosthodontic rehabilitation of patients following oral tumor resection and postsurgical radiotherapy. However, only a few long-term studies have examined the implant survival rate and other factors related to prosthodontic treatment in oral tumor resection patients. PURPOSE: The purpose of this study was to evaluate the long-term survival of dental implants and implant-retained prostheses in oral cancer resection patients. MATERIAL AND METHODS: Ninety-three patients (63 men, 30 women) with a mean age of 59 years (range of 26-89 years) received 435 implants after the resection of a head and neck tumor. Twenty-nine patients received postsurgical radiotherapy prior to implant placement. The factors related to implant survival or failure were monitored over a mean observation period of 10.3 years (range of 5 to 161 months). Prosthodontic rehabilitation was evaluated with respect to the rates of technical failures and complications. Data were analyzed using a Kaplan-Meier curve and comparisons were made with the log-rank test or the Wilcoxon test (a=.05). RESULTS: Of the 435 implants, 43 implants were lost; the cumulative survival rate was 92%, 84%, and 69% after 3.5, 8.5, and 13 years, respectively. Twenty-eight implants in 6 patients were counted as lost since the patients had died. Twenty-nine irradiated patients received 124 implants, of which 6 implants were lost prior to prosthodontic rehabilitation. In 68 patients with 78 rigid bar-retained dentures, only minor technical complications were identified. However, all 25 fixed implant-supported restorations had no technical component failures and did not require technical maintenance. CONCLUSIONS: This study demonstrates that implant-retained and -supported prostheses in oral cancer resection patients, irrespective of the cancer treatment procedure, show lower long-term survival rates than those in patients without prior cancer surgery. Rigid fixation of the implant-supported prosthesis appears to minimize the complication rates. The poor implant survival rate was due to the higher mortality rate among these patients, and not to a lack of osseointegration.

• The influence of tamoxifen on growth behavior and cell-cell adhesion in OSCC in vitro.

  Authors: Katja Nelson, Victor Helmstaedter, Herrmann Lage

  Oral oncology. 09/2007; 43(7):720-7.

  The aim of this study was to evaluate the influence of tamoxifen on the growth and aggregation behavior, focusing on the expression pattern of E-cadherin and beta-catenin, in oral squamous cellThe aim of this study was to evaluate the influence of tamoxifen on the growth and aggregation behavior, focusing on the expression pattern of E-cadherin and beta-catenin, in oral squamous cell carcinoma (OSCC) in vitro. Oral squamous cancer cell lines (UM-SCC-14A, UM-SCC-14B and UM-SCC-14C) were treated with various concentrations of tamoxifen. Growth and aggregation behavior as well as the protein expression and its changes were analysed. All cell lines are estrogen receptor (ER) positive. Tamoxifen induced a significant growth inhibition and induced the ability to form cell aggregates. This phenomena was not accompanied by a change in E-cadherin or beta-catenin expression or due to transcriptional changes. beta-catenin showed isolated membrane staining and nuclear distribution in all cell lines. A defective Ecadherin/beta-catenin complex was seen in UM-SCC-14C with no restoration through tamoxifen treatment. The cell-cell formation is increased in all cell lines without any alterations in the functional and quantitative status of E-cadherin or beta-catenin, indicating that novel cell-cell adhesion complexes not involving the classical E-cadherin/beta-catenin influence cell growth and intercellular adhesion in OSCC.

• Clinical evaluation of endosseous implants in nonvascularized fibula bone grafts for reconstruction of the severely atrophied mandibular bone.

  Authors: Katja Nelson, Corvin Glatzer, Detlef Hildebrand, Berthold Hell, M Klein

  Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. 10/2006; 64(9):1427-32.

  PURPOSE: The purpose of the present study was to assess changes in graft height after augmentation of the severely atrophied mandibula with the use of avascular fibula bone grafts, as well asPURPOSE: The purpose of the present study was to assess changes in graft height after augmentation of the severely atrophied mandibula with the use of avascular fibula bone grafts, as well as evaluation of the clinical success of endosseous implants placed in the grafted mandibula. PATIENTS AND METHODS: This retrospective study included 10 patients with a mean observation period of 31 months (range, 3 to 76 months). A total of 40 implants were placed. Clinical criteria included implant success, graft success, and crestal bone resorption. RESULTS: The grafting procedure was successfully performed in all patients. All implants were integrated, 2 implants could not be used for prosthetic rehabilitation. One implant was lost 2 years after abutment connection. The maximum bone resorption of 7.21% (+/- 2.7%) was seen within the first year; no significant resorption was seen thereafter. CONCLUSION: In this clinical and radiographic evaluation, it was found that nonvascular fibula graft is a reliable material for augmentation procedures. The resorption takes place within the first year after augmentation. The possibility of improving the clinical results in bone grafting situations with avascular fibula grafts will be further evaluated in a prospective follow-up study providing long-term assessment of this procedure.

• Miniature pigs as an animal model for implant research: bone regeneration in critical-size defects

  Authors: Baerbel Ruehe, Stefan Niehues, Susanne Heberer, Katja Nelson

  Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology.

  ObjectiveStandardized experimental investigations determining the critical-size defect (CSD) in the mandible of miniature pigs are still lacking. The aim of the present study was to obtainObjectiveStandardized experimental investigations determining the critical-size defect (CSD) in the mandible of miniature pigs are still lacking. The aim of the present study was to obtain information about the new bone formation in created defects of varying sizes.Study designMarginal resection of the alveolar crest of the lower jaw was performed in 3 female miniature pigs. The animals used in the study were 3 years of age and weighed ∼55 kg. For histologic evaluation the dental implants were harvested with the surrounding bone tissue 10 weeks after implant placement. For this, bone segments including the implants were removed from each side of the mandible. The sizes of the resected bone blocks varied, showing the following volumes: 10.1 cm3, 4.2 cm3, and 1.9 cm3. Periosteal coverage of the defects was performed. Computerized tomography (CT) of the skull of the miniature pig was performed immediately after the surgical procedure as well as 6 weeks later using a 64-channel mult-slice scanner.ResultsThe CT showed that 6 weeks after obtaining the biopsies, the filling of the defects with new bone varied. The percentage of newly formed bone in relation to the size of the original defect was 57.4% for the small- and 87.2% for the middle-sized defect. The large-sized defect showed 75.5% newly formed bone compared with baseline.ConclusionConsidering the amount of new bone formation found within this study, it is questionable if the critical defect size of 5 cm3 stated in the literature is valid. Further research concerning the mandibular model in minipigs is required and more refinement needed to assure a standardized CSD, allowing qualitative and quantitative evaluation of bone grafts and bone graft substitutes.