International Poster Journal of Dentistry and Oral Medicine, 03/2007

A semiautomatic approach to segment a central incisor along with itsperiodontal ligament (PDL) and the alveolus (tooth socket) from ComputedTomography (CT) and Digital Volume Tomography (DVT) recordings is presented.Clinical CT and DVT image series were combined in this study to mutuallycompensate for their individual weaknesses concerning the identification ofboundaries between the different segments. Three-dimensional rigid imagewarping is used to align the relevant objects in both series, allowing toapply masks of segments of one image stack on the other. The segmentationprocess involves the use of thresholds and manual refinements. In apostprocessing step, the segments are getting polygonized for smoothing andfinal inspection. It is found that a combined segmentation of CT and DVTdata allows for generating a complete model of the tooth and its alveolus inthe context of a range of applications. Keywords: DVT, CT, multimodal 3D reconstruction

Inroduction: For the reconstruction of bone defects the gold standard is still the autologous bone harvested from the iliac crest, the mandible or the maxilla. Tissue-engineering procedures for hard tissue augmentations of the maxilla offer significant advantages compared with conventional grafts, as there is minimal or no donor site morbidity, limited availability of bone and the necessity of an additional surgical procedure. Periosteum has been demonstrated to have cell populations, which include chondroprogenitor and osteoprogenitor cells, that can be isolated in tissue culture and form both cartilage and bone. Methods: Eight weeks after harvesting and cultuvating the periosteal cells, the tissue-engineered autologous bone was transplanted into the maxillary sinus of the test group. The control group underwent the same procedure except that autologous cancellous bone from the iliac crest was used instead of tissue engineered bone substitute. Results: The loss of augmented material was significantly higher in the group in which the tissue engineered material was applied. Discussion: Our experiences from this pilot study with tissue engineered bone transplants reveal the necessity to limit the indications for tissue engineered bone. Its application is restricted to the sinus augmentation with simultaneous implant insertion at sites providing a sufficient bone bearing. Keywords: tissue engineering, bone, sinus lift, dental implants

The tsunami disaster victims were recovered during the clear-up operationsusing heavy construction- and earth-moving-machinery, all sorts of vehicles,working elephants, search and recovery divers and additional action forcesby water, by land and by air. Within the "Mobile Forensic Medicine Center",the international DVI teams worked in shifts and performed the post mortemexamination of each of the tsunami victims. The DVI teams comprised policeofficers, photographers, finger print experts, legal medicine physicians,forensic odontologists and DNA experts. Keywords: tsunami, mass disaster, identification, dental, DVI, odontostomatology

Introduction: The complexity of the work stages used in the removablepartial denture technology increases the difficulty grade of denturesachieving and also the error sources. Objectives: Theimprovement of the working style is imposed for reducing the working timeand economizing some materials used for intermediary stages. Material and Methods: 30 Casts with different edentation types madein the Departement of Removable Partial Dentures Technology - UniversityDental College from Timisoara, Romania , were took for the study between2004-2005. The wax patterns of the metallic frameworks of the removablepartial dentures were made directly on the cast using a profiled "Ti -Light" (Ti Research GbR, Mainbernheim, Germany) or "LiWa"(WP Dental GmbHBevern/Hamburg), light curing waxes. Results: Light curing waxesused in the removable partial dentures technology modify clearly the workingstages of the dental technician, through elimination of the intermediarystages of model duplication, reducing the working time and economizing ofsome materials. The wax pattern of metallic framework in removable partialdentures technology, was realised directly on the cast in 20 minutes andcured in 5 -8 minutes. Light-curing wax is sticky to the instruments andcast, difficult to use. Therefore it needs precision for the profilesapplying. Even the wax-pattern seems to have a great elasticity, theirremoving from the cast have to be made cautiously in order to avoid materialcracks or fractures. The fractures proportion is higher at Ti Light, thenLiWa. Conclusions: Using light curing waxes is a novelty in thefield of removable partial dentures technology. Reducing the working timeand economizing some materials used for intermediary stages are majorqualities that will impose this materials in practice. Keywords: Light curing waxes, removable partial denture, wax pattern

Several studies evaluated the removable partial dentures by the finiteelement analysis, but none of them evaluated thermal stresses. The purposeof the study was to explore the influence of thermal oral changes induced byhot/cold liquids and food on the circumferential cast clasps of removablepartial dentures. A 3-dimensional finite element method was used to explorethe temperature distribution, thermal stress and the influence of thermalchanges on stresses and displacements of circumferential clasps duringfunctions. Thermal variations induce stresses in dental clasps, hightemperatures having a more aggressive effect than lower one. The studysuggests the importance of considering thermal variations for stressanalyses of the cast clasps. Keywords: thermal changes, finite element method, stress, displacement, clasps

In this study we examined the proliferation, the morphology and the vitality of human osteoblasts on non-sintered hydroxyapatite and demineralised bone matrix in vitro to get knowledge whether these materials are suitable for bone reconstruction in oral surgery.Human osteoblasts were isolated from the jaw during routine dental surgery and seeded onto the two different biomaterials. These cells were characterized by alkaline phosphatase assay, collagen I detection and osteocalcin production. After 21 days of cultivation the cell/biomaterial constructs were examined by scanning electron microscopy, thin sections and PI/FDA staining.The results demonstrated that the osteoblasts were able to form a vital multiple cell layer on the demineralised bone matrix within three weeks of cultivation. On hydroxyapatite the cells showed no capacity of proliferation or migration onto the synthetic biomaterial in vitro. The cells had no tendency to form well spread and viable cell constructs. These findings suggest that surface morphology or the presence of osteoinductive factors may have an important role in osteoblast adhesion and proliferation.The data implies that human demineralised bone matrix can be colonized by human osteoblast-like cells in vitro, indicating the potential of allogenic carriers regarding future therapy procedures in the field of bone engineering.

Objective: Comparison of the results of microbiological RNA-probeanalysis after subgingival plaque sampling according to 2 differentstrategies. Methods: In 158 patients suffering from aggressiveor generalized severe chronic periodontitis clinical examinations wereobtained before (n=82) or after (n=76) combined mechanical and antibioticantiinfectious periodontal therapy. Subgingival plaque samples were obtainedfrom the 3 pockets with the deepest probing depths. Two sterile paper pointswere inserted simultanously in the periodontal pockets. One paper point fromeach pocket was put in a separate transport-vial, the second was pooled(MT3) with the two other paper points of a respective patient in atransport-vial. The content of each vial was analysed separately forActinobacillus actinomycetemcomitans, Tannerella forsythensis, Porphyromonasgingivalis, and Treponema denticola with a commercially available RNA-probetest. Results: The log-transformed number of bacteria was higherin pooled samples than the mean value of the results of the separate samplesfor all tested pathogens (P Conclusion: Pooling of subgingivalplaque samples increased the bacterial counts per analysis compared toseparate samples and thus may increase the probability to detect existingpathogens. However, this observation had no statistically significant effecton the detection frequency of the tested pathogens. Keywords: oral microbiology/diagnosis, sampling strategies, RNA-probes, generalised severe chronic periodontitis/aggressive periodontitis, subgingival plaque: Actinobacillus actinomycetemcomitans, Tannerella forsythensis, Porphyromonas gingivalis, Treponema dentico

The genetic pathology often determins a complex and extreme polimorphclinical aspects. Among the frequently found anomalies are those in thedentomaxillary field. The Genetic Department from "Louis Turcanu"Children's Emergency Hospital investigated and observed between 2000-2005,540 children with genetic diseases. 78% of them presented from minor tomajor dentomaxillofacial anomalies. Among the registated cases cromosomialsyndroms, monogenic diseases, different caused plurimalformative syndromswere found. For the dentomaxillar anomalies diagnosis the dentistry exam wasoften indispensable and highly important, revealing hardly detectablediseases. The early dental exam is necessary in all genetic syndroms, for acorrect topic and adequate therapeutical directions. The dentist completsthe multidisciplinary team which participates to diagnosis and observinggenetic diseases. Keywords: dental exam, genetic diseases, dentomaxillary anomalies

Objectives: Assessment of factors contributing to tooth loss 10 years after initiation of periodontal treatment. Methods: 93 adult patients were recruited for the study. Inclusion criteriawere full-mouth radiographs from initiation of therapy and completion ofantiinfective therapy. Clinical examinations including probing parameters,Plaque and Gingival Index, samples for interleukin-1 haplotype (IL-1) test,and a detailed questionnaire on e.g. smoking habits were obtained by thesame examiner. Periodontal conditions were surveyed according to thecriteria of the Swiss Dental Association. Medical files were searched forinitial diagnosis, frequent supportive periodontal therapy (SPT) andprognosis index. Results: The following means of tooth loss per patientwithin the 10 years of observation were observed: gender (male/female):1.5±3.5/ 1.7±3.9; smoking (no/yes): 1.1±1.8/ 3.1±6.5; prognosis (A/B,C):1.4±2.4/ 2.7±4.9; initial diagnosis (moderate/severe chronic, aggressiveperiodontitis): 0.6±1.4/ 2.0±4.2; regular maintenance (yes/no): 0.45±0,8/3.1±5.1; IL-1 (no/yes): 0.95±4.7/ 2.1±1.3. Stepwise linear regressionanalysis identified irregular SPT and IL-1 haplotype to be associated withan increased rate of tooth loss (pConclusions: some criteria seemto interact with tooth loss whereas only regular spt and absence of il-1haplotype could be proven to be statistically significant in prevention oftooth loss.

Objective: Retrospective evaluation of success after tunnel preparation of class III furcation molars. Methods: In 41 patients (29 female, mean age 54.8±10.8 years) tunnel preparations were rendered to a total of 56 molars from 1992-2000. Before and 1 to 13 years after therapy examinations took place. A multilevel regression analysis was used to identify factors influencing the survival time of tunnel preparations: sex, jaw (maxilla/mandible), molar type (1st/2nd molar), smoking, participation in supportive periodontal therapy (SPT). Results: Six tunnel preparations were performed in the maxilla, 50 in the mandible. Forty tunnel preparations were done at 1st, 15 at 2nd, and 1 at 3rd molars. Eight tunnel preparations were lost during the observation period: 7 in the mandible. For the lost tunnel preparations a mean survival time of 40.8±18.6 months was observed. For those tunnel preparations that were still in function a mean survival time of 53.1±22.9 months was calculated. Multilevel regression analysis identified frequent SPT as positive (p = 0.08) and smoking (p = 0.08) as negative prognostic factors for tunnel survival. Conclusion: After an observation period of 50.7±22.6 months 48 of 56 tunnel preparations were still in function (86%). Keywords: furcation involvement, resective therapie, long-term results