Arthroscopic treatment for intra-articular adhesions of the temporomandibular joint.

PURPOSE: To introduce arthroscopic surgery of intra-articulator adhesion of the temporomandibular joint (TMJ) upper compartment and evaluate its effect. PATIENTS AND METHODS: One hundred forty-two patients (159 joints) with intra-articular adhesions confirmed by arthroscope were treated with lysis of the adhesions, intra-articular cleanup surgery, or capsule radiofrequency catheter ablation. One hundred ten patients (123 joints) with disc displacement were treated with the disc repositioning and suturing technique. The follow-up index includes jaw movement, visual analog scale pain value, and patients' self-evaluation. The therapeutic effect was divided into excellent, good, and poor. Excellent and good patients were defined as effective. Jaw movement and visual analog scale pain value before and after the operation were evaluated by a paired t test. RESULTS: The average follow-up period was 10.3 months (range: 2-27 months), and 33.80% (48/142) of all joints were excellent; 56.34% (80/142) were good, and 9.86% (14/142) were poor. The total effectiveness rate was 90.14% (128/142). Of all patients, 93.66% (133/142) felt more comfortable than they had before the operation. The interincisal opening increased from a preoperative 23.14 ± 5.93 mm (range: 10-40 mm) to postoperative 37.48 ± 3.51 mm (range: 30-40 mm; P < .01), and the pain scores were reduced from 28.94 ± 23.54 (0-80) to 4.44 ± 10.10 (0-40; P < .05). CONCLUSION: The effect of arthroscopic surgery on temporomandibular joint intra-articular adhesion was positive. It can increase the mouth's range of motion, improve jaw function, and reduce pain during jaw movement.

Application of rapid prototyping for temporomandibular joint reconstruction.

PURPOSE: To introduce the preliminary application of rapid prototyping (RP) for temporomandibular joint (TMJ) surgery. MATERIALS AND METHODS: This study included 11 consecutive patients (13 joints) seeking TMJ replacement. All patients had previously undergone 3-dimensional computed tomography (CT) scanning (0.625-mm slice thickness) of the craniofacial skeleton. The data from CT scanning in DICOM (Digital Imaging and Communications in Medicine) format were input into the interactive Simplant CMF software program (Materialise Medical, Leuven, Belgium). Preoperative planning included segmentation and osteotomies. The movements of the jaw bones were simulated by use of Simplant CMF. The affected mandible was reconstructed based on the contralateral side. Then, the titanium plate was shaped on the reconstructed model before surgery. The bone graft was transplanted by the shaped titanium plate during the operation to reconstruct the TMJ. Twenty-four patients who underwent traditional surgery were used as the control group. The operative time of the 2 groups was analyzed with the SPSS software package, version 13.0 (SPSS, Chicago, IL), with the Student t test. The data from CT scanning in the experimental group before and after surgery were compared by paired t test. RESULTS: All the incisions healed primarily without any complications. All patients were satisfied with the operation, because of their symmetric faces and good occlusion. Postoperative magnetic resonance imaging confirmed the position of the transplanted costochondral cartilage in the glenoid fossa. A group t test showed that the operative time was longer in the control group (mean, 7.09 hours) than that in the RP group (mean, 5.67 hours). Three parameters (condyle-incisor, condyle-mental foramen, and condyle-angle) from the postoperative CT scan were analyzed by paired t test, and there was no significant difference between the 2 sides. CONCLUSION: RP technology provides an advanced method for TMJ reconstruction that can make the TMJ reconstruction more accurate and symmetric, improve the mandible's function, and consequently, enhance the reconstructive effect.

The ESTMJS (European Society of Temporomandibular Joint Surgeons) Consensus and Evidence-Based Recommendations on Management of Condylar Dislocation.

Although condylar dislocation is not uncommon, terminology, diagnostics, and treatment concepts vary considerably worldwide. This study aims to present a consensus recommendation based on systematically reviewed literature and approved by the European Society of TMJ Surgeons (ESTMJS). Based on the template of the evidence-based German guideline (register # 007-063) the ESTMJS members voted on 30 draft recommendations regarding terminology, diagnostics, and treatment initially via a blinded modified Delphi procedure. After unblinding, a discussion and voting followed, using a structured consensus process in 2019. An independent moderator documented and evaluated voting results and alterations from the original draft. Although the results of the preliminary voting were very heterogenous and differed significantly from the German S3 guideline (p < 0.0005), a strong consensus was achieved in the final voting on terminology, diagnostics, and treatment. In this voting, multiple alterations, including adding and discarding recommendations, led to 24 final recommendations on assessment and management of TMJ dislocation. To our knowledge, the ESTMJS condylar dislocation recommendations are the first both evidence and consensus-based international recommendations in the field of TMJ surgery. We recommend they form the basis for clinical practice guidelines for the management of dislocations of the mandibular condyle.

Clinical evaluation of tele-endoscopy using UMTS cellphones.

BACKGROUND: In the past years, various applications of telemedicine have been found. Especially teleconsulting or telementoring has been accepted as a possible answer to upcoming higher quality demands utilizing expert knowledge in everyday clinical routine. In this work we investigate whether video transmission based on universal mobile telecommunication system (UMTS) by means of arthroscopic videos is clinically reasonable. Secondly, we examine the quality of the enabling technology especially for consolidated diagnostics and telementoring. METHODS: Twenty arthroscopic video streams with a length of 60 s of each sequence, showing endoscopic craniomaxillofacial interventions such as arthroscopies of the temoporomandibular joint or endoscopic assisted open reductions of mandibular head fractures, were hosted on a server and analyzed on a UMTS cellphone. Each of the arthroscopic video sequences was independently evaluated by two consultants and a medical expert in TMJ surgery. Quality aspects such as identifiability of anatomical details, instruments, and tasks, and pathology were assessed in a questionnaire. Stability of transmission and breakdowns were also registered. RESULTS: The median percentage of completely transmitted videos without interruption was 85 ± 12.5% (interquartile range, IQR). In 6.7% of all video transmissions, complete interruption resulted, requiring restart. Of anatomical structures, 60.7% were correctly identified, while in 39.3% an identification error was detected. Tasks and instruments were recognized in 92.4%. In 94.8%, pathologies could be correctly diagnosed. CONCLUSIONS: The need for teleconsultation is given, since orientation in arthroscopy is difficult. UMTS-streamed endoscopic videos still have certain limitations regarding teleconsulting due to instability and delay. Nevertheless, the technology may currently be beneficial for teleteaching and could be used in the future in teleconsultation. Without affecting ongoing surgeries and with no special need for a lecture theater, this technology provides tele-education using standard hospital infrastructure.

Adhesive Hydrogels for Maxillofacial Tissue Regeneration Using Minimally Invasive Procedures.

Minimally invasive surgical procedures aiming to repair damaged maxillofacial tissues are hampered by its small, complex structures and difficult surgical access. Indeed, while arthroscopic procedures that deliver regenerative materials and/or cells are common in articulating joints such as the knee, there are currently no treatments that surgically place cells, regenerative factors or materials into maxillofacial tissues to foster bone, cartilage or muscle repair. Here, hyaluronic acid (HA)-based hydrogels are developed, which are suitable for use in minimally invasive procedures, that can adhere to the surrounding tissue, and deliver cells and potentially drugs. By modifying HA with both methacrylate (MA) and 3,4-dihydroxyphenylalanine (Dopa) groups using a completely aqueous synthesis route, it is shown that MA-HA-Dopa hydrogels can be applied under aqueous conditions, gel quickly using a standard surgical light, and adhere to tissue. Moreover, upon oxidation of the Dopa, human marrow stromal cells attach to hydrogels and survive when encapsulated within them. These observations show that when incorporated into HA-based hydrogels, Dopa moieties can foster cell and tissue interactions, ensuring surgical placement and potentially enabling delivery/recruitment of regenerative cells. The findings suggest that MA-HA-Dopa hydrogels may find use in minimally invasive procedures to foster maxillofacial tissue repair.

Matrix-associated chondrocyte transplantation for reconstruction of articulating surfaces in the temporomandibular joint: a pilot study covering medium- and long-term outcomes of 6 patients.

OBJECTIVE: Matrix-associated chondrocyte transplantation is routinely used in joints of the extremities but not in the temporomandibular joint (TMJ). STUDY DESIGN: We report the first case series in 7 patients of a tissue engineering approach to regenerate severely degraded articulating surfaces in the TMJ by simultaneously completely resurfacing both the mandibular condyle and the articular eminence/glenoid fossa with a commercially available collagen sponge seeded with autologous cells stabilized within a fibrin matrix. To facilitate healing, we temporarily employed a silicone membrane to protect the engineered tissues. The indications for surgery were posttraumatic fibro-osseous ankylosis, ankylosing osteoarthritis, or late-stage osteoarthritis. RESULTS: Six of the patients were recalled for follow-up after 3 years 6 months to 12 years 1 month. The maximum incisal opening was 18.2 ± 9.2 mm (range, 9-33 mm) before and 31.2 ± 13.6 mm (range, 12-47 mm) at the latest follow-up. Histologic specimens taken at 4 months showed beginning differentiation of fibrocytes into chondrocytes, whereas at 3 and 11 years, mature hyaline cartilage-not typical for the TMJ-was present. CONCLUSIONS: We conclude that the reconstruction of TMJ surfaces by matrix-associated chondrocyte transplantation may become a routine method for cartilage regeneration in the TMJ in the future.

Open versus arthroscopic surgery for internal derangement of the temporomandibular joint: a retrospective study comparing two centres' results using the Jaw Pain and Function Questionnaire.

OBJECTIVES: Surgical procedures currently used for treating of internal derangement of the temporomandibular joint vary widely. Although different studies present favourable results following open or arthroscopic TMJ surgery, the criteria for a successful treatment outcome are not always defined identically. In a retrospective study, two groups of patients who underwent either open or arthroscopic surgery for internal derangement (stages III-V according to Wilkes' classification) were investigated using the so-called JPF-Questionnaire. PATIENTS AND METHODS: The Kyoto collective (group 1) consisted of 28 patients, 2 men and 26 women, who underwent arthroscopic surgery. At the time of surgery, age ranged from 13 to 77 years (mean 32.8 y). The postoperative follow-up period ranged from 4 years and 4 months to 5 years and 9 months. Twelve of the 28 patients were classified as stage III, 10 as stage IV and 6 were classified as stage V (according to Wilkes) at the time of surgery. The Vienna collective (group 2) also consisted of 28 patients, 2 men and 26 women, who underwent open meniscoplasty or discectomy. At the time of surgery age ranged from 17 to 55 years (mean 31.6 years). The postoperative follow-up ranged from 5 to 6 years and 9 months. Fourteen of the 28 patients were classified as stage III, 11 as stage IV and 3 were classified as stage V (according to Wilkes) at the time of surgery. The results of the JPF-Questionnaire of the two groups were compared by Wilcoxon 2-sample tests. The Japanese version was applied, while in Austria the German version of this questionnaire was applied. RESULTS: At a level of significance alpha=0.05 no significant difference was found when comparing the subgroups (Wilkes stages III, IV and V) or both groups of patients 5 years after temporomandibular joint surgery. CONCLUSION: There cannot be any clear indication for only one of the treatment modalities as similar results were noted following open or arthroscopic temporomandibular joint surgery. Nevertheless, arthroscopic surgery is a minimally invasive procedure resulting in a shorter or no time of hospitalization when compared with open surgery and therefore is preferred by many surgeons nowadays.

Cross-cultural adaptation of the JPF-Questionnaire for German-speaking patients with functional temporomandibular joint disorders.

OBJECTIVES: Clinical research related to the management of the syndrome of temporomandibular joint pain and dysfunction would be facilitated enormously between researchers in different locations around the world if a small number of patient-oriented questionnaires were to achieve wide acceptance. It would make comparison of therapeutic results possible. For this reason, a cross-cultural version of the Jaw Pain and Function (JPF)-Questionnaire was developed and validated for use in German-speaking patients with functional temporomandibular disorders. MATERIAL AND METHODS: The scale was translated from the English into the German language and translated back into English again, pretested and reviewed by a committee. The German version of the JPF-Questionnaire was tested on 137 patients with temporomandibular disorders. Reliability and concurrent construct validity were assessed using Pearson's correlation coefficients. RESULTS: The concurrent validity was assessed by evaluating the relation of the questionnaire's summary score (the internal criterion) to data on maximum interincisal distance (the external criterion). Spearman's and correlation coefficients were statistically significant for the comparison of the summary score with maximal mouth opening (r=-0.213; p=0.036). Test-retest reliability for the JPF-Questionnaire was also assessed by Spearman's correlation coefficients: at first admission at the clinic (time a, mean=20.23+/-16.42, median=16), then at the time of administration 1 day later at home (time b, mean=17.98+/-16.29, median=13), and 7 days later at home (time c, mean=17.90+/-15.77, median=13). They were r=0.91 (p=0.0001) for the initial administration with the repetition 1 day later, r=0.90 (p=0.0001) for the initial administration with the repetition 1 week later, and r=0.93 (p=0.0001) for the correlation between the two repetitions. Test - retest reliability measured by mean-against-difference graphs was not satisfactory for time (a) versus time (b) and time (a) versus time (c) but there was a good test-retest reliability for time (b) versus time (c). CONCLUSION: The use of this instrument can be recommended in future clinical trials, as the German version of the JPF-Questionnaire seems to be valid and--under the same test-retest conditions--reliable for the assessment of temporomandibular joint disorders.

The frequency of dental abscesses increases in periods of low barometric pressure.

Bioclimatic conditions are thought to have an impact on the frequency of dental abscesses but previous studies have suffered from small patient cohorts, methodological obstacles, and restriction to a single site resulting in limited geographic and meteorological variability. The aim of the present study was to investigate the influence of environmental temperature and barometric pressure on the frequency of dental abscesses. Three maxillofacial and two dental clinics in Vienna retrospectively provided a total of 19,218 patients with dentoalveolar abscesses who were treated by intraoral incision between 1998 and 2011. Daily records from six local meteorological stations were consulted to assess daily meteorological parameters. Univariate and multivariate hurdle count regression models were fitted to estimate the effect of daily average barometric pressure and temperature on registered abscess frequencies. Temporal confounders causing variance of the observed abscess frequencies - such as weekday, business day, and month - were taken into consideration. On days of low barometric pressure a significant rise in dental abscess frequency was observed, even when adjusting for confounders. Environmental temperature, in contrast, did not show any effect. In conclusion, bioclimatic conditions affect health as low barometric pressure increases the number of patients with dental abscesses.

Interactive stereotaxic teleassistance of remote experts during arthroscopic procedures.

This article describes the technical setup for stereotaxic telesurgical assistance for arthroscopic procedures. It also outlines the current state, limitations, and feasibility of this technical development. Teleassistance or teleconsultation implemented in endoscopic or arthroscopic procedures have not yet been reported. In this study, 7 computer-assisted arthroscopies of the temporomandibular joint were supported by extramural experts via interactive stereotaxic teleconsultation from distant locations. The external experts were supplied with close to real-time video, audio, and stereotaxic navigation data directly from the operation site. This setup allows the surgeons and external experts to interactively determine portals, target structures, and instrument positions relative to the patient's anatomy and to discuss any step of the procedures. Optoelectronic tracking interfaced to computer- based navigation technology allowed precise positioning of instruments for single or multiple temporomandibular joint punctures. The average error of digitizing probe measurements was 1.3 mm (range, 0.0 to 2.5 mm) and the average standard deviation was 0.7 mm (range, 0.4 to 0.9 mm). Evaluation of the reliability and accuracy of this technique suggests that it is sufficient for controlled navigation, even inside the small temporomandibular joint, a fact that encourages further applications for arthroscopy in general. The minimum requirement for high-quality video transmission for teleassisted procedures are integrated services digital network (ISDN) connections. Conventional ISDN-based videoconferencing can be combined with computer-aided intraoperative navigation. Transmission control protocol/internet protocol (TCP/IP)-based stereotaxic teleassistance data transmission via ATM or satellite seem to be promising techniques to considerably improve the field of arthroscopy.

A 3-dimensional finite-element analysis investigating the biomechanical behavior of the mandible and plate osteosynthesis in cases of fractures of the condylar process.

OBJECTIVE: The condylar region is one of the most frequent sites for mandibular fractures, with direct application of miniplates being the most commonly used open-fixation technique today. Yet, anatomic and biomechanical limitations continue to make this application technically challenging with a considerable complication rate. We sought to analyze such incongruencies with respect to the complex biomechanical behavior of the mandible. STUDY DESIGN: Individual human mandible geometry, the specific bone density distribution, and the position and orientation of the masticatory muscles were evaluated by performing computed tomography scans and a sequential dissection of the cadaver mandible. Three-dimensional finite-element analysis was performed for different fracture sites, osteosynthesis plates, and loading conditions. RESULTS: Osteosynthesis of fractures of the condylar neck with 1 or 2 miniplates of a diameter of 2.35 x 1.00 mm was found to be an insufficient fixation method. This also applies for plates (3.60 x 1.54 mm), according to Pape et al,(8) when used in singular fashion (high condylar neck fractures excepted). In cases of singular occlusal contacts in the molar region (particularly at the contralateral side of the fracture), the highest stress values inside the mandible and osteosynthetic devices could be observed. With even the static yield limit of titanium being exceeded in such cases, consecutive rapid failure of the miniplates becomes most likely when loading of the condylar region caused by bite forces cannot be prevented. CONCLUSION: We strongly recommend the use, whenever possible, of 2 plates in the manner described by Pape et al(8) for osteosynthesis of fractures of the condylar neck in combination with bicortically placed screws. The stiffness of a singular osteosynthesis plate made of titanium in a diametrical dimension of approximately 5.0 x 1.75 mm was found to be equivalent to the physiological bone stiffness in the investigated fracture sites. The actual stiffness of such a fixation plate is approximately 3 times higher than the stiffness of devices commonly in use.

Expression of VEGF-receptors in TMJ synovium of rabbits with experimentally induced internal derangement.

Our aim was to evaluate the expression of vascular endothelial growth factor receptors (VEGFRs) in the synovium of the temporomandibular joints (TMJ) of rabbits with experimentally induced internal derangement. Internal derangement was experimentally induced in 52 rabbit TMJ, and established on the right side of TMJ while the left side was used as the control. Each joint and its control was evaluated by magnetic resonance imaging (MRI) and endoscopy. The synovial tissues on both sides were harvested after one, two, three, and four weeks. The expression of VEGFRs mRNA was investigated in the experimental joint and its control using real-time polymerase chain reaction (PCR). Internal derangement was successfully confirmed in 45 of the 52 of the experimental joints (87%) on the right side by MRI and endoscopy. In the first and fourth week, the VEGFR-2 mRNA expression was higher in the experimental joints than in the controls (P=0.008 and P=0.02). Meanwhile, the VEGFR-1 mRNA expression was up-regulated in the experimental group compared with the controls during the fourth week (P=0.02). However, we found no significant differences in VEGFR-3 mRNA expression in the two groups during the first and fourth weeks. During the second and third weeks, the mRNA expression of the three receptors did not differ significantly among the groups. Our data have shown increased expression of VEGFR-1 and VEGFR-2 mRNA in the synovium of rabbit TMJ with internal derangement, which indicates that VEGFR-1 and VEGFR-2 may have important roles in the processes of internal derangement and formation of adhesions.

Management and outcome of condylar fractures in children and adolescents: a review of the literature.

OBJECTIVE: The aim of this study was to provide a comprehensive review of all kinds of case reports and clinical studies focusing on management and outcome of mandibular condylar fractures (CFs) in children and adolescents. STUDY DESIGN: A PubMed search of the international literature was done, completed by an additional hand search based on the available references of the publications found. RESULTS: In total, 73 articles were included in this review: 7 case reports and 2 retrospective clinical studies regarding surgical management, 1 publication with case reports, 1 prospective and 3 retrospective clinical studies comparing operative and conservative treatment, 20 publications with case reports, and 35 retrospective and 4 prospective clinical studies dealing with conservative management of CFs in children and adolescents. CONCLUSIONS: Despite frequently encountered radiologic abnormalities, conservative management of CFs in children usually yields satisfactory to excellent clinical results. However, in adolescents the outcome is often reported to be less favorable. Good prospective randomized multicenter studies would clarify from which age on patients could probably benefit from operative treatment.

Pseudodynamic MRI differs from natural opening of the temporomandibular joint.

OBJECTIVE: One step toward motion analysis of the temporomandibular joint is pseudodynamic magnetic resonance imaging (i.e., with stepwise mouth opening controlled by a Burnett device). This study intends to clarify whether and how pseudodynamic motion differs from natural motion. Furthermore, the fixing efficiency (i.e., the reliability of the mechanical connection to the jaw) of the Burnett device was tested. STUDY DESIGN: In 10 patients we recorded pseudodynamic opening motions by means of MRI and optical tracking technology (as known from image-guided surgery) synchronously; natural opening motions by spatiotemporal tracking only. The MRI was used to allow for interpretation of the pseudodynamic motion as recorded by means of optoelectronic tracking. RESULTS: In 3 subjects the pseudodynamic differed from the natural opening in occurrence of a loop (i.e., a short backward motion of the condyle during the opening process that results from the application of the Burnett device and does not correspond to a natural jaw movement). Fifty percent of the opening steps showed unintended motion and thus did not keep the mandible still during the MRI scan. CONCLUSION: A method was provided to detect motion during MRI scan using optoelectronic tracking. Pseudodynamic motion may differ from natural motion.

High condylectomy and disc repositioning compared to arthroscopic lysis, lavage, and capsular stretch for the treatment of chronic closed lock of the temporomandibular joint.

OBJECTIVE: The article shows the 1-yr results comparing the efficacy of open-surgery high condylectomy and disc repositioning and the arthroscopic procedure of lysis, lavage and capsular stretch in patients with chronic closed lock of the temporomandibular joint (TMJ). STUDY DESIGN: Twenty patients with a clinical and radiologic diagnosis of chronic closed lock were randomly chosen to be treated with either open surgery or arthroscopy. Each patient was evaluated with a visual analog scale (VAS) for pain and a mandibular functional impairment questionnaire (MFIQ). The evaluation also included a clinical examination. Each patient was recorded at baseline before surgery and at 1-yr follow-up. Statistical analysis was made to evaluate whether differences in MFIQ, VAS, maximum opening and protrusion, lateral joint tenderness, muscle tenderness, crepitation, and clicking at 1-yr follow-up from baseline were significant. Results were considered statistically significant when P < .05. RESULTS: Both open surgery and arthroscopic surgery reduced pain and improved mandibular function. The severity of pain was significantly reduced in both groups (P = .005). In both the open and arthroscopy groups mandibular function improved significantly (P = .005). The clinical examination showed similar good results for the 2 surgical procedures. At 1-yr follow-up a majority of patients from both the open (80% of the patients) and the arthroscopy (70% of the patients) groups fulfilled the criterion of a cutoff point for maximum interincisal opening of equal or more than 35 mm (P = 0.005); all the patients in both groups fulfilled the criterion of the cutoff point for maximum protrusion of more than 5 mm (P = .007). At 1-yr follow-up, clicking was the same as before surgical procedures; no patient in the open group showed crepitation, but crepitation was found in patients in the arthroscopy group. Joint tenderness and pain on lateral palpation as well as muscle tenderness and pain were reduced in all the cases, disappearing in some of them, but the difference was significant only regarding joint tenderness (open surgery, P = .016; arthroscopy, P = .031). CONCLUSIONS: Open-surgery high condylectomy and disc repositioning and the arthroscopic procedure of lysis, lavage and capsular stretch are both effective surgical methods to treat symptomatic patients with a diagnosis of chronic closed lock of the TMJ. Because of the minimally invasive character of the arthroscopic procedure, it should be considered as the first choice in the surgical treatment of the TMJ.

Surface area analysis of dental implants using micro-computed tomography.

OBJECTIVES: In this study, we present and evaluate a micro-computed tomography (micro-CT)-based method for the calculation of the potential bone/implant contact area (p-BICA) on the surface of dental implants. MATERIAL AND METHODS: For seven commercially available implants (Ankylos implant, Brånemark System, Frialit CELLplus, Replace((R)) Select Tapered, Straumann Solid screw, XiVE S CELLplus, 3i Osseotite XP Threaded Miniplant, the p-BICA surface is determined by means of three-dimensional X-ray computed-tomography and computer-based data processing. Measurements were repeated two times, and the stability and repeatability of the measurement method were evaluated. RESULTS: Our analysis revealed a p-BICA of 118 mm(2) for the XiVE S CELLplus implant, 134 mm(2) for the Ankylos, 136 mm(2) for the Frialit CELLplus, 138 mm(2) for the Brånemark System, 139 mm(2) for the Replace((R)), 159 mm(2) for the 3i Osseotite XP and 199 mm(2) for the Straumann Solid screw implant. The measurement method proved to be stable and led to reproducible results. CONCLUSIONS: The micro- and macrostructure of dental implants define the surface and the p-BICA. Precise determination of this parameter can be achieved by means of the micro-CT-based method as presented in this study. The value of p-BICA lies in the predictability of industrial design before preclinical and clinical testing. Based on this method, dental implant properties become comparable even if geometrical details are not disclosed by the manufacturer.

Particle size of hydroxyapatite granules calcified from red algae affects the osteogenic potential of human mesenchymal stem cells in vitro.

Hydroxyapatite (HA) microparticles as a carrier in an injectable tissue-engineered bone filler are considered promising candidates for the treatment of small bone defects in the craniomaxillofacial region. HA granules calcified from red algae, varying in size, were evaluated in vitro for their suitability to be used as a carrier for human mesenchymal stem cells (hMSCs). Three groups of granules were produced in grain sizes of 10-100, 200-500 and 600-1,000 mum. After seeding and culturing hMSCs under osteogenic differentiation conditions onto HA particles for 3, 6 and 9 days, cellular proliferation (tetrazolium salt, XTT), alkaline phosphatase (ALP)-specific activity and total protein synthesis were investigated. The osteoblastic phenotype of the cells was evaluated by assaying the bone-specific genes osteocalcin, osteopontin and collagen type I. XTT assay revealed significantly higher (p < 0.01) proliferation of cells grown on the smallest grain size after 9 days of culture. Regarding ALP-specific activity, significantly higher levels of activity were detected in cells grown on the smallest grain size. Different grain sizes had no significant effects on the secretion of osteocalcin and osteopontin. Collagen type I production was significantly higher (p < 0.05) in cells grown on the biggest grain size in comparison with the two other grain sizes. These results show that the particle size of HA microparticles affects the osteogenic potential of cultured hMSCs and lead to the conclusion that particle size has differential effects on ALP-specific activity and collagen type I production.

Seven years of clinical experience with teleconsultation in craniomaxillofacial surgery.

PURPOSE: In this work the experiences from 50 telemedically supported treatments in craniomaxillofacial surgery are summarized and different setups for their technical realization are described. Furthermore, for the first time the innovative UMTS (universal mobile telecommunication system) is applied for the transmission of arthroscopic videos of the temporomandibular joint and other craniomaxillofacial structures. MATERIALS AND METHODS: The combination of computer-assisted navigation technology in augmented reality environments with telecommunication is used for execution of interactive stereotaxic teleconsultation. Furthermore, treatments without navigation are telemedically supported. This study is composed of 4 technical system configurations: 1) integrated services digital network (ISDN)-based videoconferencing without remote control of the navigation computer; 2) transmission control protocol/internet protocol (TCP/IP)-based interactive teleconsultation via bundled ISDN lines (including remote control of the navigation computer); 3) TCP/IP-based interactive teleconsultation via network; 4) combination of TCP/IP-connection and ISDN-based videoconferencing. The telemedically supported treatments are: orbitozygomatic osteotomies, positioning of the mandibular condyle in orthognathic surgery, insertion of implants, positioning of the maxilla in orthognathic surgery, distraction osteogenesis, arthroscopies of the temporomandibular joint, and operation simulations on stereolithographic models. The surgical interventions are evaluated on a 5-level system performance scale from the technical point of view. In a separate trial 20 videosequences of arthroscopies of the temporomandibular joint are transmitted via UMTS cellular phones and independently evaluated by 3 experts (ie, a total of 60 streamings) to investigate feasibility of this technology in the field of craniomaxillofacial surgery. RESULTS: In the years from 1996 to 2002 a total of 50 treatments were telemedically supported. All intraoperative applications were successfully finished; 48 of 60 UMTS transmissions were finished without any interruptions in constant quality, slight interruptions were observed in 8 tests, and a complete breakdown was observed during 4 streamings that required a restart of the transmission. Resolution was sufficient to diagnose even tiny anatomic structures inside the temporomandibular joint, but orientation was hardly recognizable. CONCLUSION: In many applications telecommunication technology can contribute to a quality improvement in cranio- and maxillofacial surgery because of the global availability of specialized knowledge. The required technical expenditure for teleconsultation crucially depends on the infrastructure that is already available at the clinic and the remote site. UMTS is a promising technology with the potential to be valuable in numerous craniomaxillofacial applications.