International Poster Journal of Dentistry and Oral Medicine, 02/2007

Orthognathic surgery changes the morphology of faces in most cases. Usually these three-dimensional changes are visualized, measured and documented by cephalometric x-rays or photographs in only two dimensions.New techniques like the 3D-profilometry allow the capture of the facial surface three-dimensionally without any x-ray.Within this technique we captured the faces of 15 orthognathic patients pre- and postoperatively. Then we matched each pre- and postoperative 3D-model by reference points on a face bow and a "matching"- function of the 3D-software "gView". The differences between these models were calculated orthogonally to their surfaces and then coded into a colour. This colour-coded picture of differences was put together topographically with the postoperative 3D-model. So we got a colour-coded 3D-model with the possibility to visualize the 3D-morphology of the postoperative face, also the topography and quantification of the morphological changes by one view. It could be an improvement in visualization and documentation in orthognathic-surgery. Keywords: 3D-Profilometrie, Orthognathe Chirurgie, Gesichtsmorphologie, Visualisierung

Objectives: An important criterion for the success of a crown is marginal fit. However, in patient's mouth, fit can only be evaluated by subjective methods. This study describes the correlation between objective marginal fit and its subjective evaluation by dentists and dental technicians. Methods: 30 human premolars and molars were prepared and randomly divided into 6 groups. For each of the groups complete crowns were made of different alloys and technologies (casting: AuAgCu, AuPdPt, PdAgAu, CoCrMo, Ti, milling: Ti). The crowns were provisional cemented. 10 dentists and 10 technicians were asked to evaluate the fit of the crowns with a new dental explorer. The crowns were cemented with a zinc-oxide-phosphate-cement. The marginal gap (MG) and a possible overextended margin (OM) were examined under a special 4X-light-microscope. The means of MGs and OMs were calculated for each group. Significances were detected by ANOVA and post-hoc-test (Bonferroni, pResults: Crowns made from different alloys and technologies showed partly significantly (pConclusion: Crowns from different alloys and technologies showed differences in marginal fit. MGs and OMs of crowns significantly correlated with the subjective evaluation of their fit by dentists and dental technicians. For the decision of the clinicians, whether a crown is acceptable, overextension was more important than marginal gap. Keywords: crowns, marginal gap, overextension, correlation, marginal fit

Aim: The aim of the present study was to evaluate whether patients treated with an additional upper utility arch show higher amounts of root resorption than patients treated with a straight-wire technique. Materials and methods: 67 patients were included in this study. 29 of them (group 1) were treated with an additional maxillary utility arch within the straight-wire therapy (intrusion 15gm). 38 patients (group 2) were treated with a straight-wire fixed appliance. The amount of apical root resorption of the maxillary central incisors was determined for each patient by subtracting the post-treatment tooth length from the pre-treatment tooth length measured directly on cephalograms. Results: Root shortening of the maxillary central incisors was found to average 1,7mm after using an additional maxillary utility arch (group 1) for 5 months (average) and a treatment time of 23,8 months. Root shortening was found to average 0,7 mm after a treatment time of 19,8 months (average). The amount of root resorption between the two orthodontic techniques was compared by means of the student-t-test, showing to be significant. Conclusion: In the present study, it was found that intrusion with the utility arch type of technique increases the amount of root resorption for the central maxillary incisors. The average amount of root resorption in both groups show no clinical relevance. Keywords: apical root resorption, intrusion, maxillary central incisor, cephalogram

Objective: Primary stability has a major impact on the long term success of dental implants. The aim of this study was to investigate the correlation of resonance frequency analysis (RFA) and insertion torque of self-tapping and non self-tapping implants and their respective differences in primary stability. Design: A group of 263 patients were treated with a total of 602 conically formed dental implants: 408 non self-tapping Ankylos® and 194 self-tapping Camlog®. The maximum insertion torque during implant placement was recorded. Resonance frequency, measured as the implant stability quotient (ISQ), was assessed once immediately after insertion and twice three months later. Results: Torque values of the non self-tapping implants were significantly higher than those in the self-tapping group (p=0.023). RFA did not show differences between the two groups (p=0.956), but a correlation between ISQ values after implantation and three months after implant placement was measured (r=0.712). Within the implant systems, no correlation between insertion torque and resonance frequency values could be determined (r=0.305). Conclusion: Our study indicates that ISQ values obtained from different implant systems are not comparable. The RFA does not appear suitable for evaluation of implant stability when used as a single method. Higher insertion torque of the non self-tapping Ankylos® implants appeared to confirm higher clinical primary stability. Keywords: resonance frequency analysis, insertion torque, primary stability, self-tapping implants, non self-tapping implants

Surgery of craniofacial deformities is a complex task that requires careful preoperative planning. In this field Nobel-Guide-System made a great impact of predictable implantology. Using these for computer-aided surgery (CAS) the patient outcome of extreme dental and facial makeovers can be anticipated. The following case report shows new indications for dental implants by using Nobel-Guide- System for fixation of a prefabricated "Implant Guided Palatinal Distractor" (IGPD) and for an implant bridge. Thus - embedding dental implantation in maxillofacial procedures like LeFort-Osteotomy,forced guided palatinal distraction, chin augmentation and septorhinoplasty can be performed in a single-step operation. Operation time and costs can be reduced. Keywords: Esthetic facial surgery, Nobel-Guide, facial implants, palatinal distraction, dental implants

The dynamics of mandibular movements is determined by neuromuscular physiology as well as pathophysiology of all parts of the masticatory system. The objective of this pilot study was to examine if dynamic features of mandibular movements in healthy subject can be described and extracted through mandible acceleration measurements. Keywords: mandibular biomechanic, temporomandibular joint, accelerometry

A prophylactic check for any dental problems should be conducted on patients who suffer from leukaemia before beginning chemotherapy. Bacteraemia caused by oral micro flora may be very dangerous for patients with haematological malignancies. However, it should be noted that the prophylactic process itself might bring about life-threatening complications if there is only a short interval between dental treatment and the beginning of chemotherapy or if the dental treatment is too aggressive.We present a case where this prophylactic procedure produced life-threatening complications for a patient with acute myeloid leukemia. Keywords: Life-threatening complications, AML, dental treatment

The aim of this retrospective longitudinal study was, to assess the clinical long term performance of telescopic crown retained dentures with abutment teeth, exclusively located in the canine region of the lower jaw. In addition, the factors - influencing the survival time of the abutment teeth - as well as the nature and the number of the follow-up treatment measures were determined.The evaluation based on records of 84 patients who had been treated in the Department of Prosthetic Dentistry, Justus-Liebig-University Giessen, Germany.The 90%- (50%-) survival probability of the dentures was not achieved after 4.0 years (9.1 years). Furthermore, the 90%- (50%-) survival probability of the abutment teeth, determined at 4.0 years (12.9 years), was comparable to other studies. It was revealed, that the vital abutment teeth had a significant higher survival rate and survival time in comparison to abutment teeth, treated endodontically and provided with root canal posts.The patients' assessment of the telescopic crown retained denture was down the line positive (70% were very satisfied, 28% were relatively satisfied, 2% were dissatisfied). Keywords: Longitudinaluntersuchung, Teleskop, Überlebensrate, Zahnersatz festsitzend/herausnehmbarer

Aim: Retrospective evaluation of the clinical effect of non-surgical periodontal therapy according the concept of full-mouth disinfection (FMD) in patients with drug-induced gingival overgrowth (GO). Material and Method: 10 patients (7 female, 32 to 73 years of age) medicated with cyclosporine and/or calcium channel blocker received oral hygiene instruction, professional tooth cleaning followed by scaling and root planning of all 4 quadrants within 24 hours. Patients rinsed with 0.12% CHX solution and brushed with 1% CHX gel for the next 2 weeks. The clinical situation was re-evaluated approximately 4 months after FMD. After completion of FMD 8 patients were assigned to supportive periodontal therapy (SPT) and monitored for a mean of 24 months. Plaque control record (PCR), gingival bleeding index (GBI), pocket depth (PD) were recorded at baseline, re-evaluation and the last SPT visit. PD sites were stratified as follows: = 4 mm, 5-6 mm and >= 7 mm. Results: The number of sites with PD = 4mm was increased significantly after FMD (56.5 to 97.4%). Concomitantly sites with 5-6 mm and >= 7mm decreased in the same interval (27.1 to 2.2%, 16.4 to 0.4% respectively). PCR and GBI also declined significantly compared to baseline. All clinical variables remained stable over SPT. Further surgical therapy was required only in one case. Conclusions: FMD and regular SPT were effective in resolving inflammation and reducing the need for surgical treatment in patients with drug-induced GO. Keywords: full-mouth disinfection, gingival overgrowth, non-surgical, periodontal therapy, cyclosporin, calcium channel blocker

A 12-year old female orphan from Romania was transferred into our hospital. The lower jaw showed an enormous tumor in the symphysis mandibulae; diagnosed as an intraosseous venous malformation of the mandible. After resection of the tumor the defect was primarily reconstructed using a microvascularized fibula-graft. For total makeover of the mouth a computerized tomography was used for positioning the implants. The prosthesis was designed by using a Procera®-Implant Bridge. Because of vertical and horizontal loss of the anterior arch, a customized chin implant was prefabricated to improve the esthetical facial symmetry.Using dental and facial implants together in one operation is an option for full-face makeover. It reduces operating time and cost, avoids a second bone grafting procedure, improves the esthetic outcome and thus is beneficial for the patient and the dentist. Keywords: facial implants, computer assisted implantology, Simplant, facial reconstruction, immedate function, implant-bridge

Objectives: It has been widely accepted that rigidity is one of the desirable characteristics of removable partial dentures major connectors. The aim of the research was to investigate the effect of lingual bar major connector design on flexing and torque resistance by means of three-dimensional finite element analysis. Methods: Eighteen designs of lingual bars of different cross-sectional shapes and dimensions (4-5mm height, 1.5-3mm thickness, 0.3-0.75 thickness/height ratio) were developed using finite element analysis modeling. Half-pear and half-oval shapes with different cross-sections (5.88-10.59 mm²) were constructed for comparison. Vertical and horizontal forces of 30N were applied to one end of the bars, while the opposite side was fixed in all directions. The rigidity of the experimental Co-Cr major connectors was evaluated by measuring relative displacements and von Mises stresses generated under simulated torsional and compressive loads. Results: Stresses and displacements for compression loading simulating vertical forces were lower than those obtained for torsional loading simulating horizontal forces (61-63% for stresses and 41-74% for displacements). The displacements for compressive loading became closer to them for torsional loads with the decrease of the thickness/height ratio. Resulted displacements and stresses were smaller for bars with an increased thickness/height ratio. Values measured for half-oval designs were not significantly higher than those for the half-pear shapes. Conclusion: The results of this in vitro study suggest that the thickness of the lingual bar major connector should be increased to improve the rigidity of the framework to torsional and compressive loads. Cross-section shapes of the lingual bars have a lesser effect on rigidity as biomechanical point of view. (Grant: CEEX 2978/11.10.2005) Keywords: removable partial denture, three-dimensional finite element analysis, lingual bar design

Introduction: The quality of laser weldings in dental laboratory depends on the control of many parameters. The aim of the study was to find the optimal parameters related to the framework defect. Materials and methods: To evaluate the welding parameters several Co-Cr framework defects were simulated. Depending on the defect size, a pulsed Nd:YAG laser was used for joining and for build-up welding. Results: The physical parameters were determined for each step. The peak power was determined as 900W for fixing, 700W for filling and 600W for planing of the joints. The pulse duration was established as 10ms for fixing and planing and 20ms for build-up. The pulse energy was 8J for fixing, 14J for filling and 6J for planing. The diameter of the laser spot was maintained constant at 0.6mm. Conclusion: Selecting adequate combination of pulse energy, pulse duration and peak power for each step is necessary for the succes of the welding procedure. Keywords: laser welding, Co-Cr alloys, welding parameters

Aims: To enhance the prognosis of teeth with advanced furcation involvement, resective treatment options like root resection or hemisection can be indicated. The goal of this study was to describe the clinical outcome of furcation invovled teeth that underwent resective therapy. Methods: In 11 patients, 15 teeth (1 upper premolar, 12 upper molars and 2 lower molars)with advanced furcation involvement (grade II and III) were treated with resective techniques (1 trisection, 2 hemisections and 12 root resections) and consequently restored with fillings (2), single crowns (7) or double crowns (6). All patients agreed to participate in a regular recall system. Results: During the follow-up period (minimum: 20 months, maximum: 132 months), 2 out of 15 resected teeth (13.3 %) had to be extracted because of fractures of the remaining roots. The remaining 13 teeth showed a stable clinical outcome without signs of gingival or periodontal inflammation. Conclusion: If furcation involvement has advanced to grade II or III, resective treatment options should be considered as possible therapeutic strategies. Regular periodontal maintenance and a sufficient coronal restoration of the root resected teeth are important preconditions for long-term survival. Keywords: resective treatment, long-term survival