Search

One of the many applications for which lasers have been proposed in implant dentistry is for the decontamination process. The purposes of this study were to assess possible alterations in titanium implants in vitro and in vivo by use of the carbon dioxide (CO2) laser and to determine whether new bone formation can occur on previously contaminated implants. In vitro, temperature changes at the bone-titanium implant interface were recorded during use of a CO2 laser-scanning system (Swiftlase). Additionally, the effects of laser irradiation on titanium implants at various power settings were examined. In 6 beagle dogs, a total of 60 implants and bony defects resulting from plaque accumulation were treated by air-powder abrasive (the conventional treatment), laser irradiation, or both. Depending on the parameters chosen, melting and other surface alterations were seen in vitro, especially in the superpulse mode. Otherwise, no alterations were found, even at high power settings in the continuous mode. In vivo, corresponding histologic examination of 4-month sections showed evidence of new direct bone-to-implant contact after laser-assisted therapy, especially when the implants had been treated concomitantly with submerged membranes. These results support the hypothesis that peri-implant defects can be treated successfully by laser decontamination without damaging the surrounding tissues in the dog model. Nevertheless, further investigations will be required to determine the clinical efficacy of the treatment. [ABSTRACT FROM AUTHOR]

Purpose: The development of gap-free abutments is a challenging problem, because the gap between the implant and the abutment, which is a consequence of current manufacturing limitations, can serve as a reservoir for pathogens. This may lead to peri-implantitis, a major cause of implant failure. Therefore, the aim of this study was to design and fabricate a gap-free abutment using a shape memory alloy with improved ability to prevent microleakage at the implant-abutment gap., Materials and Methods: The abutment was designed using the shape memory alloy nitinol and based on mathematical calculations considering the temperature-related, reversible changes to its crystalline alloy structure. The abutment prototypes were tested for their susceptibility to microbes in vitro, under static and dynamic conditions, by contaminating the abutments before assembly using a bacterial solution. Microbacterial tests were performed after cultivation of the implants for 1 week. The results were tested for statistically significant differences using the chi-square test., Results: The mathematical calculations met the clinical requirements using a contact pressure of 2 3 108 Nm2 with a preload of 1.9 kN on cooled abutments. After recooling, the contact pressure was 1.3 Nm2, allowing for easy disassembly. Microbacterial analysis revealed no penetration of Escherichia coli under static conditions either in the control group or in the prototypes. Under dynamic conditions, however, the prototypes showed significantly reduced bacterial leakage compared to the controls., Conclusions: The data presented here demonstrate that dental implants fabricated with gap-free abutments using a shape memory alloy showed significantly reduced bacterial leakage versus conventional implants. This improvement could minimize clinical problems such as peri-implantitis and consequently enhance the long-term success of dental implants.

Objective: The cause of enophthalmos as a late complication after orbital reconstruction is poorly investigated. Multislice CT (MSCT) is usually employed for its assessment, in spite of limitations regarding soft tissue depiction/imaging, as well as the implication of radiation and production of artifacts. Magnetic resonance imaging (MRI) has been shown to be a valuable alternative. The aim of this study was to establish a bony and soft tissue orbital volume calculation method based on different high-resolution MRI sequences compared to MSCT., Materials and Methods: Thirty-seven patients were included in this prospective study investigating the origin of enophthalmos present 3-4 months after complex orbital reconstruction. Morphological and dimensional changes of the orbit, eye globes, extraocular muscles and fat content were investigated 3-4 months after surgery. To assess the site and size of bony and soft tissue changes in the traumatized orbits, we used MSCT and MR images as well as corresponding 3-D reconstructions., Results: All enophthalmic orbits revealed a significant bony volume increase compared to the contralateral side as well as a reduced sagittal eye projection. Mean orbital volume enlargements of 1.0 cm3 lead to 0.93 mm enophthalmos (P< .05). Hardly any fatty atrophy could be depicted by the different MRI techniques., Conclusions: For soft tissue depiction of the orbit, MRI was superior to MSCT. Particularly, proton density weighting proved to be the best sequence for soft tissue volume segmentation, allowing determination of the cause and degree of posttraumatic enophthalmos in reconstructed orbits.

Lasers have been used for many years in oral surgery and implant dentistry. In some indications, laser treatment has become state of the art as compared to conventional techniques. This article is a comprehensive review of new laser applications in oral surgery and implant dentistry. One of the most interesting developments over the last years was the introduction of the 9.6-microm CO(2) laser. It has been shown in the recent literature that the use of this new device can preserve tissue with almost no adverse effects at the light microscopic level. In contrast, modifications of approved CO(2) laser therapies of premalignant lesions resulted in higher recurrence rates than the conventional defocused laser technique. However, several studies indicate that other wavelengths such as Nd-YAG (lambda = 1,064 nm) or diode lasers (lambda = 810 nm) may be also of value in this field. In many other indications, the use of lasers is still experimental. Intraoperatively used photodynamic therapy or peri-implant care of ailing implants with the CO(2) laser seems to be more of value than conventional methods. However, further studies are required to assess standard protocols. Over the past years, research identified some new indications for laser treatment in oral surgery and implant dentistry. Moreover, well-known laser applications were defined as state of the art. Nevertheless, further studies are required for laser treatment in oral surgery and implant dentistry.

Dental implants are becoming increasingly important in prosthodontic rehabilitation. Bacterial infections, however, can induce bone loss and jeopardize clinical success. Recent literature has demonstrated that infrared CO(2) laser light is suitable for the decontamination of exposed implant surfaces. The aim of the present study was to investigate the influence of 308-nm excimer laser irradiation on peri-implantitis-associated bacteria in vitro. In this study, a XeCl excimer laser (308 nm) was used (Summit Technology, Boston, USA). Both aerobe (Streptococcus mutans, S. sanguis, Actinomyces naeslundii) and anaerobe microorganisms (A. odontolyticus, Prevotella melaninogenica) were tested. According to previous studies, a constant energy of 0.8 J/cm(2) and a constant frequency of 20 Hz were used for all irradiations. Colony-forming units after laser irradiation were counted. Excimer laser irradiation showed significant influence on the growth of all microorganisms. As compared to S. mutans and S. sanguis, A. naeslundii demonstrated higher sensitivity to laser irradiation. Anaerobe microorganisms, in contrast, demonstrated that a total of 200 pulses were sufficient to reduce the replication of these germs for more than 99.9%. Excimer laser irradiation (lambda = 308 nm) can significantly reduce both aerobe and anaerobe microorganisms. Depending on the parameters chosen, 200 pulses are sufficient for sterilization. New studies are necessary to evaluate if this wavelength is more of value in the treatment of peri-implantitis than other wavelengths or conventional therapies.

Purpose: Multislice computed tomography (MSCT) was the modality of choice for orbital volume measurement. This first prospective study compares MSCT with high-resolution magnetic resonance imaging (MRI) combined with micro (MRImc) and headcoil (MRIhc) in volumetric evaluation of the postsurgical enophthalmic orbit., Patients and Methods: Morphologic and dimensional changes of the orbit, eyebulb, and fat content were investigated 3 to 4 months after reconstruction of complex orbital fractures in 36 patients. Image analysis and volumetric assessment from 2-dimensional and 3-dimensional-MRImc and MRIhc were compared with MSCT. The volume segmentation algorithm operated on multispectral, 3-dimensional MR data acquired at isotropic proton density weighted acquisitions., Results: CT and MRI volume data correlated significantly (P < .01). Enlargement of the posterior segment often resulted in orbital geometry change from conical to convex. Even cases of correct orbital reconstruction presented significant volume enlargement compared to the contralateral side (P < .01). The retro bulbar fat showed itself fragmented and was dislocated in the medial posterior region mostly. We found reduced sagittal eye projection, increased width of the orbital rim, and dislocation of the posteromedial orbital floor (P < .01). High correlation was detected between orbital volume increment and degree of enophthalmos (0.93 mm per 1 cm3 orbital volume enlargement diameter) (P < .01)., Conclusions: As MRI orbital volume measurement permitted prediction of postsurgical enophthalmos, which is related to possible failure in orbital volume correction and reduction of the posterior medial bulge and not to fat content changes, it is suited for planning secondary correction.

Purpose: Recently, histologic studies in the beagle dog model demonstrated that CO2 laser-assisted implant decontamination can result in reosseointegration. Consequently, the purpose of this study was to assess the efficacy of CO2 laser-assisted therapy as compared with conventional therapy, with the concomitant use of beta-tricalcium phosphate, in humans., Materials and Methods: The study included 32 patients with 73 ailing implants. In the laser group, 22 implants were treated with soft tissue resection following laser decontamination; whereas in 17 implants, bone augmentation was performed. In the control group, soft tissue resection after conventional decontamination was performed in 19 implants, augmentation in 15 implants. Results were evaluated 4 months after surgery and in May 2004., Results: Four months after therapy, there were no significant differences in distance from implant shoulder to the first bone contact (ie, DIB values) between implants undergoing laser decontamination and soft tissue resection and implants treated with conventional decontamination followed by soft tissue resection. At the end of the study, there was a statistically significant difference between these 2 groups. Four months after therapy, DIB values after laser decontamination and augmentation were significantly more favorable than after conventional decontamination and augmentation. This difference was no longer detectable at the end of the study., Conclusion: Based on the results of this study, it may be concluded that the treatment of peri-implantitis may be accelerated by using a CO2 laser concomitant with soft tissue resection. However, with respect to long-term results in augmented defects, there seems to be no difference between laser and conventional decontamination.

Fluorochrome sequential labelling of mineralizing tissues is commonly used in different fields of clinical and basic research. Recently we improved polychrome fluorescent sequential labelling of bone by applying spectral image analysis to discriminate seven different fluorochromes. Although basic mineralization processes of bone and teeth follow comparable principles, the respective tissues differ in terms of matrix composition and mineral assembly. The aim of this study therefore was to investigate the feasibility of this new technique for polychrome sequential labelling of teeth and to demonstrate the advantages in the field of dentistry. Furthermore, the exact labelled area of each fluorochrome could be measured, even in regions of overlapping fluorochromes. The technique presented may provide a basis for further investigations of mineralization processes of different anatomical dental structures.

In this technical approach, we demonstrate that preoperative tetracycline administration helps distinguish between viable and necrotic bone in osteoradionecrosis (ORN) during surgery by exciting tetracycline fluorescence by black light. The difficult aspect of the operative approach lies in the decision of the extent of the debridement in order to prevent an iatrogenic fracture or progression of ORN. With this technique, vital bone, in contrast to necrotic bone, showed detectable fluorescence. Therefore, tetracycline fluorescence labeling may be used in attempts to facilitate the intraoperative decision making in the surgical therapy of osteoradionecrosis.

The aim of this study was to investigate the long-term effect of the ceramic beta-tricalcium phosphate (beta-TCP) at different sites of alveolar reconstruction and to evaluate its properties. From 1997 to 2002, beta-TCP was implanted as bone substitute in 152 patients using a standardized study protocol. Main indications were the filling of large mandibular cysts (n=52), secondary and tertiary alveolar cleft grafting (n=38), periodontal defects (n=24) and maxillary sinus floor augmentation (n=16). For defects exceeding 2cm in diameter, beta-TCP was combined with autologous bone taken from the retromolar area, the maxillary tuberosity or the chin region. A radiological, clinical and ultrasonographical examination was carried out 4, 12 and 52 weeks postoperative. In 16 cases, biopsies were taken after 12 months indicating complete bony regeneration. While wound-healing disturbances occurred in 9.2% of cases, partial loss of the bone substitute material was found in 5.9%, while total loss occurred in only 2%. Complete radiological replacement of beta-TCP by autologous bone was found after approximately 12 months, indicating its osteoconductive properties. Because of its versatility, low complication rate and good long-term results, synthetic, pure-phase beta-TCP is a suitable material for the filling of bone defects in the alveolar region.

Autogenous bone transfer is still regarded as the "golden standard" for many indications in oral and cranio-maxillofacial surgery. In this overview, the status of the autogenous bone is re-evaluated under consideration of current research results, clinical long-term studies, risks and safety of the patient as well as the costs. Due to the further development of modern bone substitute materials, which reveal in parts superior long-term results for special indications, the routine use of autogenous bone has to be critically reviewed.

The development of new methods and materials for osteosynthesis requires in vitro testing prior to clinical use to exclude major problems or difficulties. In the field of oral and maxillofacial surgery no standardized testing procedures have so far been established. From a biomechanical point of view the lower jaw can be described as a lever that during the chewing cycle various forces at various points of the bone act upon. Standardized solid foam polyurethane mandibles (Sawbones, Malmö, Sweden) were used for the testing of various types of screws and different types of fractures. Via linkages that were connected to hydraulic cylinders defined forces were exerted on the polyurethane mandibles and the deformation was registered depending on the force. Monitoring was carried out contactless and therefore without back coupling by the use of a video system that recorded well-defined points on both sides of the fracture line. The photographs were then evaluated by special software (SIMI MOTION CAPTURE). The control of the cylinders was performed through a processor that besides static forces also allowed dynamic testing (e.g. sinusoid oscillation with defined amplitude and number of cycles). For the standardized and realistic three-dimensional static or dynamic testing of new methods and materials for osteosynthesis of the lower jaw this test stand has proved to be optimally suitable. Independent on the type of fracture and the material used the field of application for our test stand is the complete lower jaw. Therefore an ethically correct and economically reasonable testing of industrial products and clinical methods of osteosynthesis can be performed with this simulator.

The central role of the serine protease urokinase-type plasminogen activator (uPA) and its inhibitor, the plasminogen activator-inhibitor-1 (PAI-1), in tumour invasion and metastasis becomes more and more evident. In several studies, uPA and PAI-1 proved to be of prognostic relevance as shown for different types of cancer (e.g. breast, stomach, lung). Elevated antigen levels of uPA and/or PAI-1 predict poor outcome (relapse-free survival) for patients afflicted with cancer. For oral squamous cell carcinomas, however, the prognostic relevance of the tumour-associated proteolytic factors uPA and PAI-1 has still to be evaluated. In the present study, using tissue extracts of 79 oral cancer cases, 58 specimens of normal oral cavity mucosa and of 16 tumour positive lymph nodes taken from the same patients, uPA and PAI-1 antigen were determined by highly sensitive enzyme-linked immunosorbent assays (ELISA). A correlation was found between uPA and PAI-1 in tumour tissue, when compared with the normal mucosa of the same oral cavity. Median levels showed significant elevations in cancer tissue and in tumour positive lymph nodes versus normal oral mucosa. In patients with high levels of uPA or PAI-1, there were significantly more tumour relapses. There was no significant correlation between pathological TNM categories, grading, residual tumour category, tumour site and patient age. In summary, tumour uPA/PAI-1 content (as determined by ELISA) appears to be a strong independent prognostic factor for relapse-free survival in squamous cell cancer of the oral cavity. These observations might help to select patients with poor prognosis for additional adjuvant therapy in conjunction with complete surgical resection.

Aims: This prospective study evaluates the outcome after osteosynthesis of condylar head fractures using 1.7 mm small fragment screws (2/2000 ff), which were selected according to a previous biomechanical trial to optimize condylar head traumatology. Clinical and functional results were compared to a group of fractures fixed mainly by mini- and microplates (1993-2000) and to a control group after conservative therapy with early functional training., Patients and Methods: Functional values (axiography and MRI) regarding loss of vertical height, disk mobility, protrusive and translatory movements were assessed (a) in 34 of 83 condylar head fractures (groups V and VI according to Spiessl and Schroll, 22/69 subjects) managed by osteosynthesis with 1.7-mm small fragment screws (KFS), (b) a reference group (43/84 subjects) fixed mainly by mini- or microplates (PLO), comprising 56 of 101 fractures (1993-2000), and (c) 16 condylar head fractures after conservative therapy with early functional training (KT) as a control., Results: In cases of small fragment screws, loss of vertical height (0.3 mm) was significantly reduced (p<0.01) in comparison to PLO (1.6 mm) and KT (6.9 mm). Disk mobility in KFS reached 90% of the non-fractured sides (NFS), thus clearly superior (p<0.01) to PLO (63% of NFS) and KT (40% of NFS). Translatory movements after KFS showed better results, too (p<0.05), with mediotrusion 84% and protrusion 80% of NFS. After PLO, mediotrusion was 62%, protrusion 71% of NFS, whereas KT showed only 53% (mediotrusion) and 56% (protrusion) of NFS. High-grade limitations of translatory movements presented in about 30% after PLO and <10% in KFS (p<0.01). Fragment displacements were found in <5% after small fragment screws, and in the plate osteosynthesis group in 15% (p<0.01)., Conclusions: Due to better stability and reduced articular scarification osteosynthesis with 1.7-mm small fragment screws in condylar head fractures showed clearly superior functional results compared to mini- and microplates, and to conservative therapy.

Purpose: The present in vitro investigation was carried out to assess the efficacy of treatment with 308 nm excimer laser radiation applied to the structures of the temporomandibular joint of a pig. Laser parameters suitable to ensure adequate clinical efficiency with only minor thermal damage to the surrounding tissues were to be determined., Material and Methods: Tissue structures of the temporomandibular joint (cortical and cancellous bone, cartilage, disc and muscle) were extracted from freshly killed pigs and served as specimens. The specimens were embedded in polymethylmethacrylate. The laser light was applied after horizontal sectioning and measurement of thickness. The number of impulses that were necessary to perforate the specimen was counted and the rate of ablation determined. In addition, the irradiated surface was investigated histologically and the degree of tissue alteration was evaluated., Results: The lowest energy threshold for ablation was found at an energy density of 0.8 J/cm2. Depending on the type of tissue, the maximum rate of ablation was evaluated as 1.7-6.3 microm/pulse. The depth of the thermal alteration to the surrounding tissue was about 30-70 microm., Conclusion: The guidable 308 nm excimer laser light offers a combination of precise tissue ablation with only minimal thermal damage to the surrounding tissue.

Background: In cleft patients, implant dentistry has become an integral part of oral rehabilitation. However, a lack of keratinized mucosa is found in many cases which may have adverse effects on the long-term success of dental implants with microstructured surfaces. Therefore, the aim of this study was to evaluate whether mucogingival surgery is of value in the treatment of these patients., Patients: Between 1991 and 2002, a total of 35 microstructured dental implants were inserted in 32 cleft patients. In 18 patients, vestibular scars extended to the rim of the marginal mucosa of the implants and the gingiva of the adjacent teeth. To enhance the soft tissue condition, mucogingival surgery was performed using palatal mucosal grafts., Methods: In May 2002, 29 implants and 16 mucosal grafts were evaluated. Assessment included radiological and clinical parameters., Results: Three implants were lost. Most mucosal grafts showed shrinkage of up to 30%. Clinical and radiological parameters, however, showed results that were very similar to those from non-cleft patients., Conclusion: These results support the hypothesis that keratinized mucosal grafts show long-term success in the cleft region as well. Moreover, it may be concluded that a combination of dental implants with a rough surface and palatal mucosal grafts can be recommended for oral rehabilitation of cleft patients.

This article examines the prognostic importance of urinase type plasminogen activators (uPA) and of plasminogen activator inhibitors (PAI-1) in cases of primary oral squamous cell carcinoma. Tissue samples were taken from the core of the tumour in 58 such primary surgical patients. The levels of uPA and PAI-1 were determined using ELISA. Statistical significance was calculated using the chi2- and log-rank tests. The mean follow-up (n=58) was 23 months. In order to determine prognostic value, the time before relapse was used. The mean time before relapse was 19 months. A total of 28 (40%) patients relapsed (local n=13, lymph node n=3, local and lymph node n=1, lymph node and skin n=1, other locations n=5). Such patients had significantly raised uPA (P<0.012) and PAI-1 (P<0.014) levels in the primary tumour. A optimal cutoff value for uPA (4.58 ng/mg) and PAI-1 (106.3 ng/mg) was determined using the multiple log-rank test. There was no significant correlation for patients with low or high levels (i.e. lower or higher than the cutoff value, respectively) with the usual clinical parameters such as localisation, N-stage, T-stage, differentiation and residual tumor status. Older patients (>58 years) had significantly higher levels of uPA and PAI-1 (P<0.017 and P<0.02, respectively). The likelihood of relapse was significantly higher in patients with high levels (uPA P<0.009, PAI-1 P<0.008). If the patients were divided into three groups depending on uPA and PAI-1 levels (group 1: uPA and PAI-1 low, n=35; group 2: uPA or PAI-1 high, n=12; group 3: uPA and PAI-1 high, n=11), relapses were more common in group 3 than in groups 1 or 2 (P<0.023). Patients with only surgical therapy (n=29) and those with postoperative radiotherapy (n=29) were used to evaluate postoperative follow-up. Cutoff levels were calculated for both groups. In the surgical therapy group this was uPA=5.63 ng/mg and PAI-1=106.3 ng/ml and in the surgical therapy plus radiotherapy group uPA=4.13 ng/mg and PAI-1=97.02 ng/mg. Kaplan-Meier curves showed a marked tendency for patients with higher levels to relapse more often. This is significant for surgical patients for PAI-1 (P<0.01) and for radiotherapy patients for uPA (P<0.04)

This article examines the distribution and prognostic importance of urinase type plasminogen activators (uPA) and of plasminogen activator inhibitors (PAI-1) in cases of primary oral squamous cell carcinoma. Tissue from the primary tumor was taken from 79 patients. In order to make an intra-individual comparison, tissue from the healthy mucous membrane of the mouth was taken from 50 patients and metastatic tissue from lymph glands in the neck from 16 patients. The content of uPA and PAI-1 was determined using ELISA. After follow-up, 58 patients with primary surgical therapy were included. Statistical evaluation was carried out using the Kruskal-Wallis test, the Mann-Whitney U-test and the Wilcoxon test. Pearson's product moment correlation was used to determine the relationship between uPA and PAI-1 levels. The median uPA value was 3.43 ng/mg in primary tumor, and for PAI-1 47.1 ng/mg ( n=79). There was a significant correlation between uPA and PAI-1 both in the cancerous as well as the healthy tissue ( P<0.01). The intra-individual comparisons showed uPA and PAI-1 differed significantly between cancerous and healthy tissue ( P<0.0001) with the mean uPA and PAI-1 values being nine times higher in the cancerous tissue ( n=58). The correlation for between uPA and PAI-1 in tumors, healthy tissue and metastatic lymph node tissue ( n=16) showed highly significant values in the tumors ( P<0.001). The comparison between cancerous tissue in the primary tumor and the lymph nodes was not significant for PAI-1. For uPA, the values in the lymph nodes were significantly lower ( P<0.049). There were also significantly higher levels in metastatic lymph node tissue compared with healthy mucous membrane ( P=0.005 for uPA and P=0.003 for PAI-1). There was no significant correlation of PAI-1 and uPA ( n=79) with the patient's sex, size of the tumor (T stage), nodal status (N stage), differentiation (grade), or residual tumor status. If the patients were divided into two groups (< or =58 years and >58 years), the older patients had higher uPA ( P<0.017) and PAI-1 ( P<0.02) levels. The was no significant association between tumor localisation and uPA content in the tumor; for PAI-1 the association was significant ( P<0.02) in the individual areas of the mouth. A total of 23 (40%) patients relapsed (local n=13, lymph node n=3, local and lymph node n=1, lymph node and skin n=1, other locations n=5). Such patients had raised uPA ( P=0.012) and PAI-1 ( P=0.014) levels in the primary tumor. The high variability of the normal clinical parameters in tumors only has a limited prognostic value because it is not taken into account in individual cases. Thus determination of the PAI-1 level directly after surgery could provide an indication of the likelihood of a relapse and thus aid in determining the adjuvant therapy. This confirms a trend in that tumor associated proteases can also play a key role in oral squamous cell carcinoma as new, independent, prognostic factors. Whether or not uPA and PAI-1 will play such a role will be determined in additional multicentre clinical studies.

Background: Fractures of the condylar head are traditionally managed by closed techniques, despite a considerable rate of dysfunctional problems. PDS pin osteosynthesis (presented by Rasse 1992) via a preauricular approach failed to become established as a standard procedure due to a lack of stability. Alternatively, mini- or microplating, as performed in our patients (101 condylar head fractures between 1993 and 2000), showed high-grade limitations of translatory movements in about 30% due to scarification after loosening of osteosynthesis materials. The aim of this study was to establish an efficient procedure for achieving a functionally stable and atraumatic osteosynthesis., Methods: For the definition of a suitable procedure, models of the mandible (standardized fractures, types A, B, and C) were osteosynthesized (six samples for each type of fracture and type of screw), each with three PDS pins, 2.0 mm resorbable, 2.0 cortical, 1.7 and 1.2 mm small fragment screws, and exposed to increasing loads in centric (0-20-35 mm opening) and eccentric (35 mm opening) condylar positions. A computerized biomechanical test stand allowed a dynamic simulation of chewing forces (16 hydraulic drives). The resulting fracture gaps were measured without contact by a motion capture system., Results: Within physiological limits, only 1.7 small fragment and 2.0 mm cortical screws were able to bear occlusal loadings up to 200 N (1.2 mm small fragment screws up to 150 N, resorbable 2.0 mm screws up to 100 N, and PDS-pins up to 50 N). In a pullout experiment (condylar spongious bone of young pigs, aged 4-6 months), 1.7 mm small fragment screws showed superior retention. A consecutively developed small fragment screw-system has been applied clinically in 74 condylar head fractures (58 patients). After removal of osteosynthesis material, 41 of 49 TM joints have so far shown complete restitution., Conclusions: The newly developed osteosynthesis system using a retroauricular approach based on 1.7 mm small fragment screws makes maxillomandibular immobilization unnecessary. The extra-articular position of the screw heads prevents scar-induced articular limitations. Preexisting degenerative alterations of the TMJ soft tissues, however, will affect functional results adversely.

Background: The mandible is a very uncommon place for a metastasis of a gastric carcinoma. Normally the area of the temporomandibular joint (TMJ) remains unaffected. The separate vascularization is discussed as one reason among others. Primary reconstruction after resection of the condyle is often problematic because an early onset of adjuvant systemic therapy is required. In this case, the insertion of a Quinn joint prosthesis is presented after resection of a TMJ metastasis., Case: We report a hematogenic metastatic gastric adenocarcinoma in a 51-year old male who initially presented with increasing disclusion in the left molar region. Suspecting a metastatic adenocarcinoma of the TMJ, a condylectomy with immediate replacement by a total joint prosthesis was performed via a preauricular approach. Corresponding to the clinically and radiologically suspected diagnosis, the decalcified histological specimen presented as a metastatic gastric adenocarcinoma within the intracapsular region., Results: The healing period of the implanted modified Quinn prosthesis was fast and uncomplicated after resection of this, to our knowledge, first documented metastatic gastric adenocarcinoma of the intracapsular region. After early restoration of joint function and patient satisfaction, the required radiochemotherapy of further unresectable bony metastases could be started in time., Discussion: This example of an extremely rare case of a metastasis shows that such a total joint prosthesis appears to be a very good alternative to extended autogenous reconstruction or an unsatisfactory primary resection. Due to the mating of the spherical condylar head and glenoid fossa, the modified Quinn prosthesis is very suitable for total joint replacement after extended resection or in multiply preoperated cases.

Background: Craniomandibular disorders (CMD) and atypical facial pain (AFP) represent a clinical challenge. Whereas CMD patients respond to somatic approaches, somatization should be strictly avoided in AFP. The aim of this study was to establish prognostic criteria to identify an aggravated risk of a chronic course in CMD and AFP., Method: A total of 124 consecutive patients with CMD ( n=108) or AFP ( n=16) were examined by two interdisciplinary academic pain centers. Psychometric evaluation was conducted with standardized questionnaires (SCL-90R, STAXI, modified SBAS-IV). All patients were clinically assessed by a maxillofacial surgeon or specialized dentist., Results: The following variables proved to be significant: age (risk for AFP vs CMD increased by 6% p.a.), decreased dysfunction index (13% higher risk for AFP vs CMD), and low scores concerning outwardly directed anger (12% higher risk for AFP vs CMD). There was no correlation between initial pain intensity and somatic parameters of disease as assessed by the standardized clinical examination. Low educational status proved to be the best predictor ( p<0.001) for patients presenting high initial pain with a marked discrepancy between somatic findings and subjective status., Conclusions: CMD patients differ from AFP patients regarding age, psychosocial isolation, outwardly directed anger, and a decreased dysfunction index. Additionally, initial pain intensity in patients presenting indistinct CMD/AFP can be considered as a valid predictor for a chronic course in pain.

In this study, four methods of postoperative speech evaluation are compared for 19 persons with oral cancers who have undergone oral surgery and/or radiotherapy. The Munich Intelligibility Profile was used for intelligibility testing and semiquantitative scoring by novice listeners. Expert ratings were done on the Therapy Outcome Measure (TOM) Phonological Disability form. For self-evaluation, the EORTC QLQ-C30 and the Head and Neck module was used. Swallowing function was scored on the TOM Dysphagia form. There was a high intercorrelation between the results of subjective speech evaluation by experts and non-experts and the intelligibility test, but no correlation with any of these methods could be shown for the self-evaluation by the participants. Voice quality seemed to have an influence on non-expert scores. Swallowing was a more severe problem for our group than speech impairment.

This study aimed to discover whether the surgical treatment of oral cavity tumours only affects on articulation or whether it also leads to a change in voice quality and fundamental frequency. Twelve participants were examined pre- and postoperatively for mean speaking fundamental frequency, standard deviation of the mean fundamental frequency, harmonic-to-noise-ratio and intrinsic pitch. All the parameters showed a substantial postoperative change in some patients.

INDICATION FOR FETAL SURGERY: The widespread use of high-resolution ultrasound in prenatal diagnosis allows nowadays an accurate and early diagnosis of congenital malformations. Some of these can be corrected surgically. In certain cases intrauterine surgery could present functional and aesthetic advantages or be even lifesaving. Due to the extreme sensitiveness of the fetal patient and the fetal membranes, only some defined anomalies currently meet the criteria for intrauterine surgery. However, the list can change in the future since prenatal diagnosis, technical advances, and knowledge of pathophysiology improve constantly., Endoscopic Intrauterine Surgery: Additionally, the recent development of endoscopic intrauterine surgery represents a new and more careful possibility for intrauterine surgery. Endoscopic procedures could avoid the disadvantages of open intrauterine surgery and thus make fetal operations safer, in life-threatening as well as in non-life-threatening malformations such as cleft lip and palate (CLP). The main advantages of these procedures are (1) scarless wound healing and bone healing without callus formation that leave to expect normal growth of the midface and (2) lower fetal and maternal morbidity., Discussion: Based on the results achieved until now, it can be stated that at present the intrauterine operation of CLP on humans cannot be recommended. The high morbidity and mortality risk for mother and fetus cannot be counterbalanced by the unsatisfactory results of a prenatal operation., Conclusion: In this study first results of an experimental investigation with the new endoscopic techniques are presented, whereby the possibilities for optimization and quality improvement of the intrauterine surgical procedures are analyzed in detail.

In this work the biocompatibility of osteosynsthesis plates treated with plasma immersion ion implantation (PIII) was tested using a rat model. Small rods (Ø 0.9 mm, and length 10 mm) prepared from different materials-pure Ti, anodised Ti, and two NiTi alloys (SE 508, and SM 495)-were implanted with oxygen by PIII to form a rutile surface layer and subsequently inserted into rat femurs, together with a control group of untreated samples. The results of the biomechanical tests correlate with the histological results, and show that plasma immersion ion implantation leads to an increase of biocompatibility and osseointegration of titanium and NiTi, albeit no improvement of the (bad) biocompatibility of the anodised Ti. Despite the layer thickness of up to 0.5 microm a strong influence of the base material is still present.

Objectives: If the primary palatal closure in a patient with cleft lip and palate is unsuccessful, defects such as palatal fistulas and a short velum have to be corrected by secondary operations. It is an informal belief among surgeons that these reoperations can have detrimental effects on the patients' nasal resonance and articulation. It was our aim to critically evaluate the validity of this belief., Material and Methods: One hundred and twenty-four patients with cleft lip and palate were divided into three groups. The 70 patients in group 1 had only undergone a primary palatal closure operation. The 33 patients in group 2 had undergone one or more palatal reoperations. The 21 patients in group 3 had undergone an additional pharyngeal flap operation. Resonance and articulation were evaluated perceptually. Nasalance was assessed with the NasalView system, and the mean speech rate was analyzed with the MODIAS software., Results: There were no significant differences for any of the speech measures between groups 1 and 2. Patients in group 3 had significantly worse results for all speech measures., Conclusions: The speech outcomes for patients with multiple palatal reoperations were no different from those of patients with single palatal closure operations. The pharyngeal flap operation did not lead to sufficient improvements in the speech of the patients in group 3.

Aims: At present the discussion about the correct management of high condylar and diacapitular fractures has been reopened. The aim of the present prospective study was to evaluate the role of condylar mobility, disk mobility, and vertical dimension regarding the postoperative functional outcome after open reduction and osteosynthesis compared to nonsurgical treatment., Methods: Since 1993 a total of 130 high condylar and diacapitular fractures have been treated by open reduction and osteosynthesis. Thirty-nine subjects with 51 fractures classes V and VI according to Spiessl and Schroll (surgical treatment, ST) were assessed postoperatively (mean 24 months) including magnetic resonance imaging (MRI) and axiography. Sixteen conservatively treated fractures served as a reference (conservative treatment, CT)., Results: Surgically treated temporomandibular joints presented a better condylar mobility (11.4 mm after ST, 5.9 mm after CT) and a less remarked loss of vertical ramus height (1.6 mm after ST, 5.4 mm after CT). Conservatively treated high condylar fractures formed a nearthrosis with the articular eminence in an anteromedial malposition (x axis 6.9 mm, y axis 10.3 mm). Disk mobility was reduced in both groups (3.8 mm after CT, 5.8 mm after ST), with major interindividual variations after ST. Significant correlations were found in the surgically treated group between axiographic limitations and limitations of disk mobility (p < 0.01) or periarticular scar formations (p < 0.01). Helkimo indices after ST (31% symptom free, 67% light symptoms < 5 points) were clearly superior (p < 0.01) to conservative treatment, with 63% of the subjects presenting craniomandibular symptoms > 5 points., Conclusions: According to the functional results observed, high condylar and diacapitular fractures will profit by open reduction and osteosynthesis. Only effective surgical procedures can preserve both disk mobility and vertical ramus height.

Background: Velopharyngoplasty is the most commonly used operative technique for the treatment of velopharyngeal insufficiency. By attaching a posterior pharyngeal flap to the velum, a nonphysiological situation is created in the upper airway. Purpose: The aim of this investigation was to find a new surgical approach to physiological reconstruction of the velopharyngeal sphincter. Material: Anatomical investigations were performed in four cadavers. From this study a new surgical technique was developed and called 'levatorplasty': the musculus longus capitis was taken to create a new muscular loop leading to (a) an augmentation of the posterior wall, (b) a medial shift of the lateral pharyngeal wall; and (c) stretching of the velum posteriorly. Thus, the velopharyngeal space was reduced and a physiological closure of the nasal airway space could be obtained. Study design: The levatorplasty was employed in nine cleft palate patients with velopharyngeal insufficiency. Pre- and postoperatively the velopharyngeal closure was evaluated by phonetic and radiological examination. Results: The operation was easily performed without major complications. A concentric constriction with decrease of the velopharyngeal space was achieved and a definitive decrease of nasalance and hypernasality resulted. Conclusion: Long-term follow-ups have to verify whether these results will be stable. They also have to be compared with functional improvements following velopharyngoplasty or pharyngoplasty. Of special interest will be evaluation of the altered mobility of the lateral pharyngeal walls. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.

For the stress analysis of the human mandible a flexible simulation concept basing on finite element-method has been developed. One of the main issues is the prediction of fractures as a consequence of known forces as well as the forensic reconstruction of the traumatologic situation. At first, the individual geometry was reconstructed by 3D-CT-Scans. To reduce the simulation efforts, for the time being the anisotropic structural mechanics of the jaw bone was neglected in favour of an homogeneous and isotropic material law. Assuming the Von-Mises-Stress as a failure indicator the results of the simulations were in good agreement with typical traumatologic situations. For further validation of the model, a real failure case, shown on a radiograph of a injured human mandible with three fractures, was simulated and, by this, the real incident was reconstructed. Reasonable planned extensions of the actual simulation concept have the regard on the nerve channel, the temporomandibular joint's function, the paradontal apparatus and the individual mechanical properties of the bone.

The article describes part of a research project aiming to develop a new modular software tool for the individual dynamic numerical simulation of the human mandible using the finite element method (FEM). Its planned use in the clinical setting makes it very important to validate the results of the simulations. Here, the function of the masticatory muscles is to be tested. On the basis of biomechanical data from the literature, standard movements, such as closing the mouth, forward movement, lateral movement or backward movement, were dynamically simulated. Apart from muscle activity, the movements of the mandible are defined by the temporomandibular joint. At present, translating the condylar dynamics to the simulation still poses problems. For this reason, therefore, simulations of the two extreme cases "fixed" and "force-free" condyles are compared. While in the case of fixed condyles, some of the movements could be reproduced either not at all or only weakly, in the case of force-free condyles, all standard movements were reproduced qualitatively, albeit without the guiding effect of the joint capsule or the articular disc.

A new modular software concept for individual numerical simulation of the human mandible using the finite element method (FEM) is presented. The main task is an individual analysis of regional stress and stress-compatibility on the basis of computed tomographic data in individual patients. Simulation should, however, also be possible in parallel with biomechanical experiments, or for further research projects. For this purpose, rapid and uncomplicated generation of the FEM model, easy modification of input data, and short computation times are required. Practical use in the clinical setting makes appreciable additional demands on the individual software components.

Objectives: Mean nasalance in speakers with perceptually normal nasal resonance can differ in magnitude considerably. In addition, categorizations of speech based on nasalance scores may not agree with perceptual judgments. To overcome this limitation, we evaluated two new simple measures derived from mean nasalance data: the nasalance distance (range between maximum and minimum nasalance) and the nasalance ratio (minimum nasalance divided by maximum nasalance)., Setting: Department of Oral and Maxillofacial Surgery, University of Technology, Munich, Germany., Subjects: The sample consisted of 133 cleft lip and palate patients with normal nasal resonance or varying degrees of hypernasality., Procedures: Oral and nasal acoustic measurements were made using the NasalView system. Nasalance distance and nasalance ratio were calculated for five non-nasal and three nasal sentences from the modified Heidelberg Rhinophonia Assessment Form., Results: Optimum cutoffs were derived from receiver-operating characteristics. Results for the sentence stimuli ranged from 64.4% to 89.6% sensitivity and from 91.2% to 94.1% specificity. When the analysis was limited to only one nonnasal and one nasal sentence, results ranged from 79.7% to 87.5% sensitivity and from 88.2% to 97.1% specificity., Conclusions: We conclude that the two new measurements are valuable in routine clinical examinations. Nasalance distance and ratio derived from sentence stimuli are two useful and easily applicable measures that can be used to supplement the nasalance mean value.

Magnetic resonance imaging (MRI) assessment of traumatized temporomandibular joints (TMJ) usually focuses on disc position, defining regular joint function by normal, excentric or displaced disc position. So far, there are only few reports regarding disc position after open reduction of diacapitular or high condylar fractures of the TMJ with dislocation. The aim of the present study was to evaluate the role of the disc as regards postoperative functional outcome by electronic axiographic recordings of condylar movements and MRI, displacement of the disc and lesions of TMJ soft tissues being frequent in this type of mandibular fractures. A total of 30 subjects with 37 condylar fractures in whom osteosynthesis was performed using a preauricular approach were imaged postoperatively (mean 24 months) with a 1.5-Tesla MRI system to determine, (a) the position of the disc, (b) the range of mobility of the disc and (c) condylar mobility in closed and open mouth position, comparing fractured sides (FS) vs nonfractured sides (NFS). Linear movements between the two jaw positions in the sagittal plane were measured by superimposing transparencies. The results indicate: (1) more than 70% of the discs (FS) were found to be in normal position; there was no disc displacement without reduction. However, these data stood in contrast to severe limitations of the axiographic tracings as presented by almost 30% of the subjects. (2) Significant correlations were found between fixed (alpha = 0.05) or highly immobilized (alpha = 0.01) discs and axiographic limitations, suggesting disc mobility to be a valuable parameter for assessment of the postoperative functional outcome.

In patients with cleft lip and palate (CLP), the assessment of velopharyngeal morphology and function and the quantitative analysis of perceptual consequences of velopharyngeal insufficiency are of major importance regarding the effective planning of velopharyngoplasties for speech improvement. The NasalView, a new instrument for the objective assessment of rhinophonia, is presented. The NasalView measures nasalance, the relative sound pressure level of the nasal signal in speech, expressed as a percentage. In order to evaluate the effectiveness of the computerised measurement of nasalance, 156 patients with surgically treated CLP were examined. The NasalView differentiated with high sensitivity and specificity between patients with normal nasal resonance and patients with varying degrees of hypernasality. To illustrate the importance of the NasalView for making the decision for a velopharyngoplasty, a single case is presented.

While esthetic and functional outcomes of treatment have improved for patients with cleft lip and palate (CLP), a CLP remains a severe problem for patients and relatives. To date, psychological research has dealt with issues such as intelligence, self-consciousness or treatment satisfaction but the long-term impact of a CLP on a psychological construct such as quality of life has yet to be explored. From a pool of 156 patients with CLP, subgroups of varying sizes were examined with a set of standardized questionnaires (KINDL, SF-36, Social Support Survey). In all patients, primary operative treatment had been accomplished. Long-term impact of the CLP on family life was assessed by 112 of the patients' parents by filling in the Impact on Family Scale. A set of questionnaires, especially developed for patients with CLP, was administered as well. For all patients who have been being treated in an interdisciplinary cleft center for their entire life, the results presented indicate that quality of life is good and within a normal range. Social support appears to be within a normal range. Parents report only minor long-term impact of the CLP on family life and family planning. Treatment satisfaction is high in the CLP patients. The questionnaires especially aimed at CLP patients indicate more specific problems mainly concerning social acceptance, where patients think the CLP had a negative impact. The standardized questionnaires employed so far failed to capture these problems. The combination of the two types of questionnaires is a sufficiently sensitive assessment procedure.

Conservative treatment of TMJ condylar fractures (groups V and VI according to Spiessl and Schroll 1972) often shows poor clinical results. This follow-up study was designed to objectify the benefits of an operative procedure by electronic computer-assisted recording of condylar movements. Sixty-three individuals with a total of 77 condylar fractures (42 diacapitular fractures, 35 high condylar process fractures) underwent surgery over a preauricular approach. Osteosynthesis was performed according to the intraoperative site either by PDS pins, titanium lag screws, microplates, miniplates or a combination of these materials. Radiological controls showed a considerable loss of height of the condylar process in the diacapitular group of fractures affecting the lateral condylar pole (n = 20). Condylar deformations in these cases were similar to the high condylar process group, whereas diacapitular fractures not affecting the lateral condylar pole (n = 22) had better radiological results. Axiographic tracings of TMJ movements in all groups as well as clinical functional analysis demonstrated highly satisfactory functional results within physiological limits. Compared to data referring to individuals treated conservatively, far fewer irregularities of axiographic tracings were observed in this group. Limitations of condylar movements nevertheless were found frequently in the high condylar process group (35%). As a severe complication, permanent facial nerve palsies occurred in six individuls due to the preauricular approach employed. After a modification using a temporal extension, only one minor partial lesion occurred in 97 operations.

Infolge eines primären Defizits der velopharyngealen Funktion liegen bei vielen Patienten mit Lippen-Kiefer-Gaumenspalten sekundäre kompensatorische Lautbildungen vor. Mit zwei neuen Computerprogrammen werden die Auswirkungen der kompensatorischen Artikulation auf die durchschnittliche Sprechgeschwindigkeit von 146 Patienten mit Lippen-Kiefer-Gaumen-spalten untersucht. Die Patienten wurden dabei nach dem Schweregrad der artikulatorischen Auffälligkeit gruppiert. Bei der schnellen Silbenwiederholung zeigte sich, dass die durchschnittliche Silbenrate pro Sekunde bei Patienten mit deutlich auffälliger Artikulation signifikant reduziert war. Beim Nachsprechen von Sätzen war die zum Nachsprechen benötigte Gesamtzeit bei dieser Patientengruppe signifikant erhöht, und das Zielwort des Satzes wurde signifikant später begonnen. Die Ergebnisse zeigen, dass die mittlere Sprechgeschwindigkeit von Patienten mit Lippen-Kiefer-Gaumenspalten mit kompensatorischer palatolalischer Artikulation niedriger ist.

Background: In Anglo-American literature, prevalences as high as 41% are reported for voice disorders in cleft lip and palate (CLP) patients. Because of considerable variability in the reported findings and because no prevalence data are available for the German-speaking area, a screening study was conducted., Method: 154 patients with CLP were examined. Voice quality was assessed perceptively according to the rbh-system (roughness, breathiness, hoarseness). Suprasegmentals and nasal resonance were also assessed. Using a new computer programme for the apparative analysis of voice quality, data for pitch, intensity and pertubation (jitter and shimmer) were obtained for 4 sustained vowels., Results: Based on perceptual analysis, we found that the prevalence of severe voice disorders in CLP patients was 6.5% which is lower than reported in most other studies. The incidence of voice disorders in CLP patients is numerically only slightly higher than in the normal population. The acoustic measurements confirm the results of perceptual analysis. Since the prevalence of severe voice disorders was low, none of the pertubation quotients differentiated between modal and disordered voices. A weak correlation was found between jitter and the ratings for hoarseness., Conclusions: 1. While it is appropriate to assume a higher potential risk for vocal dysfunction in CLP patients the actual prevalence in the patients examined is numerically only slightly higher than in normals. 2. For patients with voice disorders, apparative diagnostics of voice quality is a useful and practical adjunct to perceptual analysis which helps profiling individual patients and helps the professional to make decisions for therapy.

The aim of the present study was to investigate the influence of 308 nm excimer-laser radiation on bacterial growth. Six different bacterial strains (Staphylococcus aureus, Escherichia coli, Streptococcus faecalis, Lactococcis lactis, Salmonella typhimurium, and Deinococcus radiodurans) were exposed in vitro to various doses and energy densities of laser radiation. To exclude bacterial killing by supraphysiological heating, the temperature change in the samples during irradiation was measured. Extended antimicrobial effects of XeCl excimer-laser radiation depending on the time of radiation, the energy density of the laser beam, and the irradiated bacterial strain were observed. Reduction of bacterial growth is independent of temperature and not linked to any ablative tissue removal. In almost all cases, a 99.9% reduction of bacteria was reached by total radiation times < 100 ms. The proven antimicrobial effects of 308 nm excimer-laser radiation may be of significant clinical importance in endodontics and periodontology in the future.

This study analysis 16 cases of dental injuries occurring during endotracheal intubation. The overall rate was 1 out of 6000 cases of intubation. As expected, the upper jaw teeth are most often involved. Partial dislocations were the most common lesion, together with dental fractures. A well-documented dental evaluation before delivery of anesthetics and appropriate precautions and protective devices during intubation will prevent most dental trauma related to endotracheal intubation. Also, early use of dental and risk management services often will ensure timely resolution of such problems.

This follow-up study was designed to identify the differences between the TMJ movements of individuals undergoing orthognathic surgery, with and without positioning of the mandibular proximal segment. A further aim was to assess the location of the terminal hinge axis before and after surgery regarding variations due to mandibular advancement or set back, respectively combined two jaw osteotomy. Mechanical axiographic tracings were documented in 14 patients undergoing orthognatic surgery without positioning of the mandibular proximal segment. The terminal hinge axis position was marked by a tattoo. After surgery two more axiographic tracings were recorded over a follow-up period of 24 months. Changes to the terminal hinge axis position were also documented. Condylar guidance angles showed no differences, whereas Bennett angles decreased by an average of 25%. Subjective or objective TMJ symptoms after surgery could be observed in 64% of the patients, compared to 50% before surgery. Considerable variations in the position of the terminal hinge axis were observed nine months after surgery, especially in the two jaw group. In Class II individuals the terminal hinge axis was found in a cranial position both after 9 and 24 months. Class III individuals with two jaw surgery also gained a long term cranial localisation, whereas Class III patients with mandibular setback only demonstrated a hinge axis position inferior and anterior compared to the preoperative reference. No statistically significant differences were apparent between the axiographic condylar movement parameters in the present group as compared to data published employing condylar positioning.

Our clinical results show that 3D model building is an excellent method for 3D preoperative planning. Dependent on the number of steps, however, there are many possibilities of failures. Standardization and quality control of data acquisition and industrial manufacturing must be recommended. This is especially important for stereolithography, as it is definitely more complex than the milling technique. One possibility seems to be the use of phantom models. Another factor is that the surgeon has to be involved in the essential steps of data analysis and segmentation. Based on our experience, the building of 3D CT skull models is a clinically efficient method that is mature enough for clinical use, but cannot yet be accepted as the clinical routine. Quality assurance is urgently necessary.

Planning and simulation of individual interventions are not yet the common standard treatment in general surgery. Improvements in planning and simulation of individual orthognatic and craniofacial interventions have led to the need to transfer the results of preoperative planning to the location. Videomatching offers a new approach to the surgeon so that simulation output can be used in a highly intuitive way. Congruent video superimposition of the real site and a view of the simulation give the surgeon a unified view of both domains. Visual merging is immediately accepted by the surgeon who prefers the intuitive, non-tactile nature of this highly informative navigational aid. Application and positioning of anatomical markers and time-consuming calibration procedures can be reduced to a minimum. Alternative plans can be discussed among several surgeons preoperatively, and different therapeutic concepts solidified in various simulation models can be selected intraoperatively. We concentrate on the application of this new method in craniomaxillofacial surgery, but it is applicable in other disciplines as well.