Tricalcium phosphate-based biocomposites for mandibular bone regeneration--A histological study in sheep.

The present study investigated the suitability of three different absorbable biocomposites for the repair of critical sized bone defects created at the mandibular angle of adult sheep. Each biocomposite was composed of a three-dimensional individualized polylactide scaffold, containing a tricalcium phosphate biomaterial (chronOS). Either autologous bone marrow (chOS/BoneMarrow) or coagulation factor XIII (chOS/FactorXIII) was added to the biomaterial for osteopromotion. Venous whole blood (chOS/Blood) added to the biomaterial served as a control. A total of 18 adult sheep were used for implantation studies, subdivided into three groups of six animals each. After 12 weeks of observation, the animals were sacrificed and the mandibles were retrieved for qualitative and quantitative histologic assessment within three regions of interest (transitional zone, center, and periphery) throughout the biocomposites. Successful bone regeneration was defined by the absence of scaffold deformation and the presence of new bone formation within the biocomposites. In histomorphometry, only chOS/BoneMarrow showed elevated area fractions of newly formed bone in all regions of interest (transitional zone 50.7 ± 7.5, center 31.9 ± 9.3, periphery 23.1 ± 13.5). This led to preservation of the macroscopic scaffold structure in all specimens. Zero hurdle regression confirmed this by validating the factor biocomposite as significant (p < 0.001) for regeneration success. In our experiment, chOS/BoneMarrow was the only biocomposite passing the hurdle of regeneration in all three regions of interest. In contrast, bone formation was less pronounced and uniform in chOS/FactorXIII and chOS/blood-containing specimens. In these groups, scaffolds showed obvious to significant deformation. Overall, autologous bone marrow showed the most promising results in our experimental setting. As opposed to reports in the literature, we could not confirm the suitability of coagulation factor XIII to promote bone formation, since bone formation rates were comparable only to those of the control venous blood.

HCRP1 expression status is a significant prognostic marker in oral and oropharyngeal cancer.

OBJECTIVE: The hepatocellular carcinoma-related protein 1 (HCRP1) is a key factor in the degradation of the epidermal growth factor receptor. In this study, we assessed the prognostic significance of HCRP1 expression in patients with oral and oropharyngeal squamous cell carcinoma (OOSCC). METHODS: HCRP1 expression was determined by immunohistochemistry on tissue biopsy sections of 111 patients with locally advanced OOSCC undergoing neoadjuvant chemoradiotherapy followed by surgery. The Kaplan-Meier method and Cox regression models were used for survival analyses. RESULTS: Low HCRP1 expression was associated with poor recurrence-free survival (P = 0.046) and overall survival (P = 0.03). Multivariate analysis revealed that low HCRP1 expression remained an independent risk factor for relapse (HR 2.98, 95% CI 1.19-7.49, P = 0.02) and death (HR 3.04, 95% CI 1.19-7.79, P = 0.02). CONCLUSION: Low HCRP1 expression was found to be of adverse prognostic significance in patients with OOSCC who received preoperative chemoradiotherapy.

Facial aesthetics and the assignment of personality traits before and after orthognathic surgery.

Processing and interpreting the face is generally very important because one is often required to make rapid decisions in life on the basis of meagre information. Ninety-two volunteers used a computer-assisted test battery to assess 40 profiles of patients (8 skeletal Class II and 8 skeletal Class III patients, each pre- and postoperatively, with 8 skeletal Class I photographs serving as controls). On a 7-point Likert scale the raters were asked to evaluate aesthetics and a few relevant personality traits (e.g. unintelligent, inhibited, aggressive, brutal). The photographs of the two patient groups were rated significantly less attractive and intelligent prior to surgery than the photographs of the control group. In respect of personality traits, the photographs of the skeletal Class III group differed more strongly from normal ones. In respect of aesthetics and intelligence, both patient groups benefited markedly from surgery. For some personality traits, significant interactions were found between the two groups on pre-post comparison. The method underlying the study is useful for evaluating the outcome of orthognathic surgery, but also indicates the strongly generalized and unconscious processes involved in the estimation of people's personality traits, especially when these concern deviations from the socially normal condition.

Is failure of condylar neck osteosynthesis predictable based on orthopantomography?

BACKGROUND: Osteosynthesis failure rates of 11.3% with 1 miniplate, 6.7% with 2 miniplates, and 4.4% with a single Medartis condyle plate were reported in previous studies of our clinic. Current science is still focused on the osteosynthesis material. Besides clinical parameters, conventional radiographs are still the first choice to detect osteosynthesis failures. This study scrutinized several factors assessable in postoperative orthopantomographs which might elevate the risk of osteosynthesis failure. STUDY DESIGN: A total of 136 patients (22 with osteosynthesis failure, 114 without) with 151 mandibular condyle fractures were included in this study. Eight parameters were assessed in postoperative orthopantomographs. RESULTS: The best predictor of osteosynthesis failure was a simplified concept of ramus height. In cases of reduced or normal ramus height, the odds of osteosynthesis failure was significantly (P = .000001) reduced to a 10th. Isolated fractures were significantly more error prone (P = .0009). CONCLUSIONS: Postoperative orthopantomographs depict factors which increase the risk of osteosynthesis failure.

Examination of dental casts in newborns with bilateral complete cleft lip and palate.

This study reports measurements of dental casts in patients up to 6 months of age with bilateral complete cleft lip and palate (BCLP). 25 mouth casts of newborns with BCLP were selected from the hospital archive. They were measured independently by two examiners who assigned numbers to each measurement, referring to the expected reproducibility. The investigators also classified each dental cast according to an established score. The absolute values of all measured distances (P-P', L-C1-C2-T, L'-C1'-C2'-T', P-L, P'-L', L-L', C1-C1', C2-C2', Q1-Q1', Q2-Q2', T-T', I-Q1Q1', I-Q2Q2', I-TT') are reported. Inter-observer reproducibility was acceptable with total measurement errors ranging from 0.5 to 1.4mm. Most reliability scores, ranging from 1 (very high) to 5 (very low), showed a mean between 2 and 3 (min 2.17; max 3.16). The two examiners rated only one patient differently, according to the applied classification scheme. The absolute measurement values of the two classification systems accorded with the literature. This is the first study to measure the distances according to an established protocol in BCLP patients. The measurements between certain landmarks are more precise than others; it may be possible to use the more precise points for a longitudinal study from birth to 18 years.

Uptake of (18)F-FLT and (18)F-FDG in primary head and neck cancer correlates with survival.

UNLABELLED: The aim of the study was to determine the practicability of (18)F-FLT in tumours of the head and neck area in terms of visualization, a possible correlation between FLT uptake and proliferation fraction as determined by Ki-67 immunostaining, and if tumoural FLT-uptake has a prognostic meaning, as determined by a correlation to patient survival time. Results were compared to (18)F-FDG. PATIENTS, METHODS: 20 patients with previously untreated lesions of the head and neck area, which were clinically highly suspicious to be malignant, underwent PET scans with (18)F-FLT and (18)F-FDG, a CT of the head and neck area, and a biopsy. Tumour tracer uptake was determined by standardized uptake value (SUV) normalized to body weight and /non-tumor ratios (T/N). (18)F-FDG and (18)F-FLT uptake were compared with histopathologic and immunohistochemical results. RESULTS: 19 patients had malignant tumours; one patient had a benign cystadenoma (so called Warthin's tumour) of the parotid gland. One negative lesion turned out to be a malignant T1 stage squamous cell carcinoma in both PET scans, the Warthin's tumour was false positive with (18)F-FDG but showed only faint uptake with (18)F-FLT, resulting in a sensitivity of 95 % for both tracers. Of all lesions, maximum SUVs of (18)F-FLT ranged from 1.53 to 11.70 (mean +/- SD 5.81 +/- 2.28) those of FDG from 2.63 to 16.50 (mean +/- SD 8.91 +/- 3.58), p < 0.001. (18)F-FLT-T/N ranged from 0.94 to 5.85 (mean +/- SD, 3.18 +/- 1.21), (18)F-FDG-T/N was from 0.92 to 7.50 (mean +/- SD, 3.6 +/- 1.74), n.s. The mean survival time was 18 months in a maximum follow up time of 36 months. A significant correlation between both PET tracers and survival was detected, but no correlation between the amount of Ki-67 positive cells and FLT. CONCLUSION: In head and neck cancer in the primary setting (18)F-FLT does not provide additional visual information in comparison to (18)F-FDG.(18)F-FLT uptake is inversely correlated with patient survival, as well as (18)F-FDG.

Biodegradable polymer membrane used as septal splint.

The treatment of a crooked nose is one of the most challenging rhinoplastic procedures. Correction of the abnormally curved or fractured septum has been reported using mostly scoring techniques, septoplasty and submucous resection techniques; cartilaginous spreader grafts can also be sutured to the distorted septum. Extracorporal septal straightening and repositioning/refixation is another useful but difficult technique. A common problem of septal cartilaginous grafting techniques is to harvest enough straight cartilage to correct the deformity. (Other donor sites such as rib cartilage are used, but harvesting additional cartilage is a time-consuming procedure and carries the risk of donor site morbidity.) Recent studies have been published using alloplastic internal splinting of the deformed septum. The use of poly p-dioxanone foils and porous polyethylene has been suggested before. In this study, a novel grafting material, a PolyMax membrane that has potential advantages over both materials, is presented. This is a porous biodegradable polymer made out of 70:30 poly(L-lactide-co-D,L-lactide) that remains stable for at least 7 months. Poly p-dioxanone loses its stability after only 2 months, whereas porous polyethylene is a permeable material that is controversial due to possible complications in cases of membrane exposure and infection. In this preliminary report the PolyMax membrane was used successfully in 3 patients.

Invitro study of adherent mandibular osteoblast-like cells on carrier materials.

Augmentation of the craniofacial region is necessary for many aesthetic and reconstructive procedures. Tissue engineering offers a new option to supplement existing treatment regimens. In this procedure, materials composed of hydroxyapatite (HA), of synthetic or natural origin, are used as scaffolds. The aim of this study was to evaluate the effects of three HA materials on cultured human osteoblasts in vitro. Explant cultures of cells from human alveolar bone were established. Human osteoblasts were cultured on the surface of HA calcified from red algae (C GRAFT/Algipore), deproteinized bovine HA (Bio-Oss) and bovine HA carrying the cell binding peptide P-15 (Pep Gen P-15). Cultured cells were evaluated with respect to cell attachment, proliferation and differentiation. Cells were cultured for 6 and 21 days under osteogenic differentiation conditions, and tissue-culture polystyrene dishes were used as control. The ability of cells to proliferate and form extracellular matrix on these scaffolds was assessed by a DNA quantification assay, protein synthesis analysis and by scanning electron microscopical examination. Osteogenic differentiation was screened by the expression of alkaline phosphatase. The osteoblastic phenotype of the cells was monitored using mRNA levels of the bone-related proteins including osteocalcin, osteopontin and collagen Type I. We found that cells cultured on C GRAFT/Algipore) and Pep Gen P-15 showed a continuous increase in DNA content and protein synthesis. Cells cultured on Bio-Oss showed a decrease in DNA content from Day 6 (P < 0.05) to Day 21 (P < 0.0001) and protein synthesis on Day 21 (P < 0.005). Alkaline phosphatase activity increased in cells grown on C GRAFT/Algipore and Pep Gen P-15 in contrast to cells grown on Bio-Oss, in which the lowest levels of activity could be observed on Day 21 (P < 0.05). Reverse transcriptase polymerase chain reaction analysis confirmed the osteoblastic phenotype of the cells grown on all three materials throughout the whole culture period. The results of our in vitro study show that the differences in metabolic activity of cells grown on HA materials are directly related to the substrate on which they are grown. They confirm the excellent properties of HA carrying the cell binding peptide P-15 and HA calcified from red algae as used in maxillofacial surgery procedures.

Distraction osteogenesis with subperiosteal devices in edentulous mandibles.

Nine patients with severely atrophic edentulous mandibles were treated by distraction osteogenesis with subperiosteal distractors for vertical augmentation of the anterior alveolar bone before insertion of implants. All the patients had severe complications and we conclude that the use of subperiosteal devices for vertical augmentation of edentulous mandibles is hazardous and offers no advantage over other surgical methods.

Preoperative radiochemotherapy and radical resection for stages II to IV oral and oropharyngeal cancer: grade of regression as crucial prognostic factor.

The purpose of this study was to assess the prognostic value of histological response to preoperative radiochemotherapy in an established multimodal therapy concept for advanced oral and oropharyngeal cancer. Two hundred and twenty-two patients who underwent preoperative radiochemotherapy (RCT: 50 Gy, mitomycin C and fluorouracil) and radical surgery were retrospectively evaluated. Resected tumours of all patients were histologically analysed and response to RCT was classified in histopathological grades of regression (RG). In a multivariate statistical analysis, RG was compared with established factors regarding their predictive value for overall and disease-specific survival. The 5-year overall survival probability in the different groups of histopathological regression grades were: RG1 (no vital tumour): 73.4%, RG2 (minimal tumour remnants encompassing less than 5%): 72.1%, RG3 (5-50% vital tumour cells): 41.9%, RG4 (more than 50% vital tumour): 37.9%. For disease-specific survival probability no significant differences were found between both groups of "responders" (RG1 and RG2) nor between "non-responders" (RG3 and RG4), whereas responders and non-responders differed significantly from each other (log-rank test; p < 0.001). T-classification, N-classification and disease stage, histological grading, tumour site, age, and sex had less prognostic value than RG in a Cox regression model. In the neoadjuvant multimodal therapy concept, histological response to preoperative RCT is a crucial prognostic factor even when surgical R0-resection is accomplished. Thus, non-responders have to be regarded as high-risk patients for recurrence and may benefit from further therapy.

Preoperative radiochemotherapy and radical resection for stages II-IV oral and oropharyngeal cancer: outcome of 222 patients.

To analyse survival and locoregional control in patients with advanced oral and oropharyngeal squamous cell carcinoma (SCC) after multimodal therapy with preoperative radiochemotherapy (RCT) and radical surgery. We included in this analysis 222 patients who underwent multimodal therapy between 1990 and 2000. Eligible were patients with UICC disease stages II-IV (T2: 33.3%; T3: 12.6%; T4: 54.1%; N0: 45.9%; N1: 17.6%; N2: 33.3%; N3: 3.2%; stage II: 21.1%; stage III: 14.9%; stage IV: 64%). Patients received preoperative radiochemotherapy consisting of Mitomycin C (15-20 mg/m2, day 1) plus 5-Fluorouracil (750 mg/m2/24 h-infusion, days 1-5) and concomitant radiotherapy for a total dose of 50 Gy. Radical locoregional en bloc-resection according to the pretherapeutic tumour extension was carried out in all patients. After a median surveillance period of 72.3 months (24-152 months), 131 patients (59%) were alive, and 91 (41%) patients died; 12 (5%) of them died postoperatively, 46 (21%) due to tumour recurrence, and 33 (15%) deaths were not directly related to the primary tumour. Overall survival probability was 76% after 2 years, and 62% after 5 years. Two- and 5-year local control probability were 88 and 81%, respectively. Regarding the high percentage of stage IV disease in the reported patients, the multimodal concept is an effective therapy offering excellent survival and local control probability.

Basic research and 12 years of clinical experience in computer-assisted navigation technology: a review.

Computer-aided surgical navigation technology is commonly used in craniomaxillofacial surgery. It offers substantial improvement regarding esthetic and functional aspects in a range of surgical procedures. Based on augmented reality principles, where the real operative site is merged with computer generated graphic information, computer-aided navigation systems were employed, among other procedures, in dental implantology, arthroscopy of the temporomandibular joint, osteotomies, distraction osteogenesis, image guided biopsies and removals of foreign bodies. The decision to perform a procedure with or without computer-aided intraoperative navigation depends on the expected benefit to the procedure as well as on the technical expenditure necessary to achieve that goal. This paper comprises the experience gained in 12 years of research, development and routine clinical application. One hundred and fifty-eight operations with successful application of surgical navigation technology--divided into five groups--are evaluated regarding the criteria "medical benefit" and "technical expenditure" necessary to perform these procedures. Our results indicate that the medical benefit is likely to outweight the expenditure of technology with few exceptions (calvaria transplant, resection of the temporal bone, reconstruction of the orbital floor). Especially in dental implantology, specialized software reduces time and additional costs necessary to plan and perform procedures with computer-aided surgical navigation.

Fixation of zygomatic fractures with a biodegradable copolymer osteosynthesis system: short- and long-term results.

Biodegradable osteosynthesis devices can be viewed as addition to, not yet replacement for conventional metal osteosynthesis materials. In a series of 65 patients with zygomatic fractures, a short-term complication/sequelae rate of 22.8% and a long-term complication rate of 9.4% were recorded. Lactosorb plates, panels and screws were the only devices used for osteosynthesis. All complications associated with the biodegradable material could be considered minor and were resolved by the use of minor surgical procedures or conservative measures. The results of this study indicate that treatment of zygomatic fractures with biodegradable osteosynthesis material has no major long-term adverse effects beyond the total material resorption time.

Conservative treatment of large cystic lesions of the mandible: a prospective study of the effect of decompression.

Our aim was to evaluate prospectively the effects of decompression as the primary treatment of large mandibular cysts, irrespective of their histological type. Twenty patients with large mandibular cysts completed treatment successfully. After a mean duration of decompression of 446 days, cysts had shrunk by a mean of 81%. Mean follow-up was 527 days after removal of the decompression stent and removal of the cyst. There were no recurrences. The advantages of this approach are simplicity, immediate gathering of information on the type of cyst with simultaneous start of treatment, low morbidity and low incidence of complications during treatment. Despite the length of the treatment, we recommend the use of decompression stents in the treatment of large mandibular cysts.

Pedicled sandwich plasty: a variation on alveolar distraction for vertical augmentation of the atrophic mandible.

We describe a method of vertical augmentation of an edentulous mandible that causes minimal weakening of bone and disturbance of sensation.

Orbital floor reconstruction with an alloplastic resorbable polydioxanone sheet.

The orbital floor is frequently reconstructed after blow-out fractures or midface fractures to avoid a relapse of the repositioned orbital tissue and to prevent enophthalmos. A total of 31 patients underwent reconstruction of internal orbital wall fractures with a resorbable 0.25 mm or 0.5 mm-thick polydioxanone implant (PDS). Skeletal and functional outcome was evaluated retrospectively with regard to fracture size. Fracture size was graded as small, moderate or large by CT scans and operating records. Two of the 25 patients with small or moderate defects showed an enophthalmos of 2-3 mm. Five of the six patients with large defects or two orbital wall fractures had enophthalmos. The scar that formed after implant resorption was to weak to provide adequate support of the globe or to compensate the enlarged orbital volume. Endoscopic follow-up examination of 12 patients showed yielding of the scar in the orbital floor already in moderate defects. Eight patients had diplopia in extreme gaze and two had significant diplopia. Blow-out and midfacial fractures with small to moderate defects in the orbital floor (up to a size of 2.5 cm2) can be reconstructed by polydioxanone sheet to avoid enophthalmos. Polydioxanone implants should only be used in cases without massive orbital fat herniation. The scar formed after implant resorption may influence functional outcome.

Quantitative analysis of factors affecting intraoperative precision and stability of optoelectronic and electromagnetic tracking systems.

This study aims to provide a quantitative analysis of the factors affecting the actual precision and stability of optoelectronic and electromagnetic tracking systems in computer-aided surgery under real clinical/intraoperative conditions. A "phantom-skull" with five precisely determined reference distances between marker spheres is used for all measurements. Three optoelectronic and one electromagnetic tracking systems are included in this study. The experimental design is divided into three parts: (1) evaluation of serial- and multislice-CT (computed tomography) images of the phantom-skull for the precision of distance measurements by means of navigation software without a digitizer, (2) digitizer measurements under realistic intraoperative conditions with the factors OR-lamp (radiating into the field of view of the digitizer) or/and "handling with ferromagnetic surgical instruments" (in the field of view of the digitizer) and (3) "point-measurements" to analyze the influence of changes in the angle of inclination of the stylus axis. Deviations between reference distances and measured values are statistically investigated by means of analysis of variance. Computerized measurements of distances based on serial-CT data were more precise than based on multislice-CT data. All tracking systems included in this study proved to be considerably less precise under realistic OR conditions when compared to the technical specifications in the manuals of the systems. Changes in the angle of inclination of the stylus axis resulted in deviations of up to 3.40 mm (mean deviations for all systems ranging from 0.49 to 1.42 mm, variances ranging from 0.09 to 1.44 mm), indicating a strong need for improvements of stylus design. The electromagnetic tracking system investigated in this study was not significantly affected by small ferromagnetic surgical instruments.

Preprosthetic vertical distraction osteogenesis of the mandible using an L-shaped osteotomy and titanium membranes for guided bone regeneration.

PURPOSE: Vertical osteodistraction is a new alternative method for alveolar ridge augmentation of the mandible. The purpose of this article is describe a technique using an L-shaped osteotomy and titanium membranes for guided bone regeneration (GBR) in the distraction gap. PATIENTS AND METHODS: Ten patients with severe atrophy of the edentulous molar region of the mandible underwent vertical callus distraction in 13 sites using intraoral microplate distractors. An L-shaped osteotomy with a short vertical part mesially and a longer horizontal part ending in the retromolar region was made, and the osteotomized segment was fixed to the mandibular ramus at its distal edge by a microplate, which became the center of rotation when distraction began. In this way, more callus generation could be achieved mesially than in the distal molar region. Follow-up computed tomography (CT) scans reconstructed axially to the axis of the mandible revealed semilunar excavations of the generated bone buccally in the distraction gap in the first cases. Clinical inspection on removal of the distractors showed fibrous connective tissue in the gap. Therefore, to prevent this from happening, titanium membranes covering the distraction gap were applied in subsequent cases. RESULTS: Ten patients (13 sites) were treated by vertical callus distraction. In 4 cases, GBR was achieved using titanium membranes. In all cases, the increase in alveolar height was sufficient to make dental implantation possible. In 1 patient, a fracture of the distractor occurred, and dehiscence was observed in 2 cases. These complications did not change the plan of therapy nor did they influence the results. The CT scans showed a homogenous surface on the regenerated mandible in the cases of GBR application. CONCLUSION: Both an L-shaped osteotomy and the application of titanium membranes for GBR in the distraction gap are of great value for mandibular augmentation, producing a physiologically shaped alveolar ridge.

Midfacial degloving: an alternative approach for traumatic corrections in the midface.

Midfacial degloving was used as an approach in 14 patients to correct post-traumatic deformities in the midface. In eight patients, deformities in the naso-orbito-ethmoid region were corrected by orbitonasal osteotomy, telecanthus correction, orbital grafting and nasal augmentation procedures. Zygomatic osteotomies were performed in five patients with orbitozygomatic deformity. In one patient, a midface fracture (Le Fort II/III) was reconstructed after midfacial degloving. By combination of transoral vestibular, intranasal and preseptal transconjunctival incisions a complete degloving of the midface up to the nasofrontal angle and the zygoma prominence was possible. All osteotomies could be completed after midfacial degloving. Additional coronal incisions were not required. Orbitonasal osteotomies for nasal lengthening as well as fixation of the medial canthal ligament by a miniplate could be performed under direct vision. There were no postoperative complications such as stenosis of the nasal aperture or disturbances of the mimic musculature. Midfacial degloving offers good exposure, specially of the central part of the midface, without leaving an external scar. It is useful for reconstructive procedures in patients after midface trauma.

Principles of computer-assisted arthroscopy of the temporomandibular joint with optoelectronic tracking technology.

PURPOSE: This preliminary clinical study evaluated the applicability, accuracy, and benefits of computer-assisted arthroscopy of the temporomandibular joint (TMJ) with optoelectronic tracking technology. MATERIALS AND METHODS: A hybrid of reality and virtual reality is built as a composite-reality environment by extracting 3-dimensional anatomical structures through use of computed tomography, magnetic resonance imaging, radiography, and other types of imaging procedures commonly used in clinical praxis. These various independent sources of imaging data of a particular patient can be combined with and complemented by complex graphic simulations. Intraoperatively they are merged with online position data of surgical instruments inside the patient's TMJ. This hybrid model of detailed anatomical structures, guidelines, and real-time instrument positions allows the surgeon to accurately plan the arthroscopic intervention as well as to navigate effectively intraoperatively. RESULTS: In the first 10 cases of computer-assisted TMJ arthroscopy, composite reality environment technology permitted the online visualization of TMJ structures, puncture sites, instrument positions, and virtual pathways in relation to anatomical landmarks with high spatial accuracy (minimum, 0.0 mm; maximum, 2.5 mm; mean, 1.4 mm; SD, 0.6 mm) and high temporal resolution (100 ms). Past, present, and possible future instrument positions can be displayed. The application of computer-assisted arthroscopy caused little immobility for either surgeon or patient. CONCLUSION: Even experienced surgeons profit from improved precision in the handling of the arthroscope; thus this technology was found to be particularly useful in degenerative temporomandibular disorders and for triangulation procedures.