Volumetric Evaluated Bone Resorption After Open Reduction and Internal Fixation of Condylar Head Fractures of the Mandible.

PURPOSE: Decision making in the management of condylar head fractures remains difficult due to its dependency on multiple factors like fracture type, degree of dislocation, patient`s age and dental condition. As open reduction and internal fixation (ORIF) of condylar head fractures (CHFs) becomes more popular, the question of osteosynthesis removal is controversial. So far, information on volumetric changes after ORIF are available for a short-term period (<6 months) only. This study, therefore, was performed to assess bone resorption after condylar head fractures and to follow-up intermediate-term (>1 year) remodelling after removal of metallic osteosynthesis material. Furthermore clinical outcome was measured using Helkimo Index and put in relation with bone resorption. MATERIALS AND METHODS: A retrospective analysis of 19 patients who underwent open reduction and internal fixation of condylar head fractures at the University Hospital of Zürich between January 2016 and April 2018 using intraoperative cone-beam computed tomography repositioning control was conducted. The bone resorption on the condylar head was measured in the course after removal of osteosynthesis material by segmenting and superimposing of the postoperative 3D radiologic follow-up exam (T2) over the initial intraoperative cone-beam computed tomography (T1) using iPlan-CMF software. Complementary Helkimo index was assessed to put resorption rate in relation to clinical outcome. RESULTS: A total of 19 patients fulfilled the inclusion criteria. The mean follow-up time was 15.6 months and the mean bone resorption on the condylar head was -0.348cm3 or -15.29% of segmented condylar head. There was no correlation of clinical outcome and bone resorption. CONCLUSIONS: Helkimo index showed satisfying results; therefore, ORIF of condylar head fracture proves as a feasible treatment option. The mean bone resorption rate of -15.29% in the intermediate-term follow-up time (mean 15.6 months) is comparable to findings of other studies with short-term follow-up time (< 6 months). Thus, postinterventional remodeling activity and resorption seems highest in the first 4 to 6 postoperative months with little further resorption. In prevention of negative sequelae of protruding implants, timing of osteosynthesis material removal after this period of high bone remodeling activity is recommended. The resorption rate showed no correlation to clinical outcome.

Cell seeding accelerates the vascularization of tissue engineering constructs in hypertensive mice.

Rapid blood vessel ingrowth into transplanted constructs represents the key requirement for successful tissue engineering. Seeding three-dimensional scaffolds with suitable cells is an approved technique for this challenge. Since a plethora of patients suffer from widespread diseases that limit the capacity of neoangiogenesis (e.g., hypertension), we investigated the incorporation of cell-seeded poly-L-lactide-co-glycolide scaffolds in hypertensive (BPH/2J, group A) and nonhypertensive (BPN/3J, group B) mice. Collagen-coated scaffolds (A1 and B1) were additionally seeded with osteoblast-like (A2 and B2) and mesenchymal stem cells (A3 and B3). After implantation into dorsal skinfold chambers, inflammation and newly formed microvessels were measured using repetitive intravital fluorescence microscopy for 2 weeks. Apart from a weak inflammatory response in all groups, significantly increased microvascular densities were found in cell-seeded scaffolds (day 14, A2: 192 ± 12 cm/cm2, A3: 194 ± 10 cm/cm2, B2: 249 ± 19 cm/cm2, B3: 264 ± 17 cm/cm2) when compared with controls (A1: 129 ± 10 cm/cm2, B1: 185 ± 8 cm/cm2). In this context, hypertensive mice showed reduced neoangiogenesis in comparison with nonhypertensive animals. Therefore, seeding approved scaffolds with organ-specific or pluripotent cells is a very promising technique for tissue engineering in hypertensive organisms.

Improved Results in Closed Reduction of Zygomatic Arch Fractures by the Use of Intraoperative Cone-Beam Computed Tomography Imaging.

PURPOSE: The use of intraoperative imaging could help overcome the insufficiency of closed reduction that can result from the absence of visible feedback to evaluate the accuracy of the reduction in isolated zygomatic arch fractures. The aim of the present study was to evaluate the use of intraoperative 3-dimensional cone-beam computed tomography (CBCT) to improve the accuracy of reduction, by measuring the remaining cortical step and dislocation angle. We also evaluated the effect of CBCT on the need for repeat surgery. PATIENTS AND METHODS: We performed a retrospective cohort study of patients who had undergone zygomatic arch reduction surgery from January 2008 to May 2018. The patients were grouped according to the predictor variables into group A (postoperative radiologic follow-up studies) and group B (intraoperative CBCT imaging studies). The primary outcome variables were the remaining cortical step and dislocation angle compared with the ideal virtually mirrored position. These were assessed as measures of reduction accuracy. The secondary variables included age, gender, surgery duration, and fracture type. Statistical analysis was performed using a robust multiple regression analysis. RESULTS: The 45 patients were divided into 2 subgroups with 18 patients in the no intraoperative imaging (control) group and 27 patients in the intraoperative imaging group. Insufficient reduction occurred in 1 patient in the group without intraoperative imaging, leading to repeat surgery. No repeat surgery was necessary in the intraoperative imaging group. The remaining cortical step of the intraoperative imaging group was significantly lower than that of the control group (0.18 vs 2.03 mm; P < .001). For the remaining dislocation angle, similar findings were observed but without statistical significance (3.93° vs 7.75°; P = .58). CONCLUSIONS: The use of intraoperative CBCT significantly increased the accuracy of the reduction. Furthermore, the need for repeat surgery was not required for any patient in the intraoperative imaging group with CBCT-guided reduction.

Postgraduate training in Oral- and Maxillofacial Surgery: Results of a survey among 74 German interns.

The aim of this study was to asses a survey of residents to obtain relevant information about their current situation in training in Oral and Maxillofacial Surgery in Germany. Special focus was given to the personal and clinical preferences of the residents, their main subjects of interest and plans after residency. Furthermore, the different principles of education at German teaching hospitals were evaluated. Overall, 74 questionnaires were completed on a voluntary and anonymous basis by German residents for Oral and Maxillofacial Surgery. Participants' mean age was 32.74 years (68% male, 27% female). Most participants were in the fifth year of training (32%) and members of the German Association of Oral and Maxillofacial Surgery (70%). This rate increased with progress in residency (p = 0.006). Most residents (70%) were employed at university hospitals, followed by non-university hospitals (26%) and private practices (4%). Residents from university hospitals (3.06 ± 0.39 years) were less advanced in training compared to residents from non-university hospitals and private practices (4.10 ± 0.54 years; p = 0.005). Part-time employed residents were significantly younger (30.64 ± 2.37 years) than full-time employed residents (33.25 ± 0.64 years, p = 0.002). Structured concepts of training existed in 64% of the hospitals, while training depending on the current year of residency (42%) was most common. Most of the residents would prefer a systematic rotation system (59%). Main subjects of clinical interest were aesthetic (50%) and orthognathic surgery (46%). The interest in dento-alveolar surgery (34%) significantly increased with participants' age (p = 0.008). Clefts and malformations were favoured by few residents (16%). Most participants planned to specialize in facial plastic surgery after residency (76%). The data collected might give evidence for an increasing importance of structured training concepts in Oral and Maxillofacial Surgery. It might be relevant to enhance the interest and the excitement of residents for oncology, traumatology, cleft and malformation surgery.

Outcome of Surgically Treated Fractures of the Condylar Process by an Endoscopic Assisted Transoral Approach.

PURPOSE: Fractures of the condylar process are frequent. Ideal management of these fractures, as discussed in the literature, is controversial. Some recent meta-analyses have favored open reduction and internal fixation using various approaches. A strictly transoral approach has been described to minimize scarring and risk of facial nerve injury but has restricted visibility. This retrospective study analyzed outcomes of patients with unilateral mandibular condyle fractures who were treated by open reduction and internal fixation through an endoscopic-assisted transoral approach. MATERIALS AND METHODS: This study included 40 patients who were operated on from January 2015 through December 2016. All patients underwent surgery for a condylar process fracture using an endoscopic-assisted transoral approach. Fracture classification, demographic, and outcome data were collected. RESULTS: Most condylar process fractures were caused by falls from a height less than 3 m. Most were condylar base fractures and classified according to Spiessl and Schroll as Classes I and II. Sixteen patients showed a preoperative malocclusion, whereas 2 patients showed a slight postoperative malocclusion. In cases in which only 1 plate could be placed, the proximal fragment was shorter. A higher Spiessl and Schroll class showed a tendency toward longer operation times. For postoperative outcomes, 1 case of temporary facial palsy was the worst complication (2.5%), 2 cases exhibited minimal occlusal interference (5%), and 1 case exhibited a deviated mouth opening (2.5%). Ramus height was restored in all cases. No chronic pain was found in any cases. CONCLUSIONS: It is feasible to treat condylar process fractures in a safe manner using a transoral approach with endoscopic assistance and angled instruments without facial scarring and at a low complication rate. The endoscope improves the restricted visibility of the transoral approach, although a learning curve is necessary. This applies especially to dislocated fractures or to fractures with a short proximal fragment.

Is there more to the clinical outcome in posttraumatic reconstruction of the inferior and medial orbital walls than accuracy of implant placement and implant surface contouring? A prospective multicenter study to identify predictors of clinical outcome.

PURPOSE: Reconstruction of orbital wall fractures is demanding and has improved dramatically with the implementation of new technologies. True-to-original accuracy of reconstruction has been deemed essential for good clinical outcome, and reasons for unfavorable clinical outcome have been researched extensively. However, no detailed analysis on the influence of plate position and surface contour on clinical outcome has yet been published. MATERIALS AND METHODS: Data from a previous study were used for an ad-hoc analysis to identify predictors for unfavorable outcome, defined as diplopia or differences in globe height and/or globe projection of >2 mm. Presumed predictors were implant surface contour, aberrant implant dimension or position, accuracy of reconstructed orbital volume, and anatomical fracture topography according to the current AO classification. RESULTS: Neither in univariable nor in multivariable regression models were unfavorable clinical outcomes associated with any of the presumed radiological predictors, and no association of the type of implant, i.e., standard preformed, CAD-based individualized and non-CAD-based individualized with its surface contour could be shown. CONCLUSION: These data suggest that the influence of accurate mechanical reconstruction on clinical outcomes may be less predictable than previously believed, while the role of soft-tissue-related factors may have been underestimated.

A prospective multicenter study to compare the precision of posttraumatic internal orbital reconstruction with standard preformed and individualized orbital implants.

PURPOSE: A variety of implants are available for orbital reconstruction. Titanium orbital mesh plates are available either as standard preformed implants or able to be individualized for the patient. The aim of this study was to analyze whether individualized orbital implants allow a more precise reconstruction of the orbit than standard preformed implants. MATERIALS AND METHODS: A total of 195 patients treated between 2010 and 2014 were followed up to 12 weeks after surgery. Of the patients, 100 had received standardized preformed and 95 individualized implants. The precision of orbital reconstruction with the different implants was determined by comparing the variances in the volume difference between the reconstructed and the contralateral orbit on the postoperative computed tomographic scans. Clinical volume-related parameters including globe position, vision, motility, and diplopia and surgical details including approach, timing and technique of implant modification, use of navigation, duration of surgery, as well as adverse events were documented. RESULTS: Orbital reconstruction was significantly more precise when individualized implants were used. The same was seen with intraoperative navigation. An overlap in the use of individualized implants and navigation makes it difficult to attribute the improved precision to a single factor. CONCLUSION: This study demonstrated that individualization and navigation provide clinical benefit.

Model-based segmentation in orbital volume measurement with cone beam computed tomography and evaluation against current concepts.

PURPOSE: Objective determination of the orbital volume is important in the diagnostic process and in evaluating the efficacy of medical and/or surgical treatment of orbital diseases. Tools designed to measure orbital volume with computed tomography (CT) often cannot be used with cone beam CT (CBCT) because of inferior tissue representation, although CBCT has the benefit of greater availability and lower patient radiation exposure. Therefore, a model-based segmentation technique is presented as a new method for measuring orbital volume and compared to alternative techniques. METHODS: Both eyes from thirty subjects with no known orbital pathology who had undergone CBCT as a part of routine care were evaluated (n = 60 eyes). Orbital volume was measured with manual, atlas-based, and model-based segmentation methods. Volume measurements, volume determination time, and usability were compared between the three methods. Differences in means were tested for statistical significance using two-tailed Student's t tests. RESULTS: Neither atlas-based (26.63 ± 3.15 mm(3)) nor model-based (26.87 ± 2.99 mm(3)) measurements were significantly different from manual volume measurements (26.65 ± 4.0 mm(3)). However, the time required to determine orbital volume was significantly longer for manual measurements (10.24 ± 1.21 min) than for atlas-based (6.96 ± 2.62 min, p < 0.001) or model-based (5.73 ± 1.12 min, p < 0.001) measurements. CONCLUSION: All three orbital volume measurement methods examined can accurately measure orbital volume, although atlas-based and model-based methods seem to be more user-friendly and less time-consuming. The new model-based technique achieves fully automated segmentation results, whereas all atlas-based segmentations at least required manipulations to the anterior closing. Additionally, model-based segmentation can provide reliable orbital volume measurements when CT image quality is poor.

Non-radiological method for three-dimensional implant position evaluation using an intraoral scan method.

INTRODUCTION: This technical innovation presents a method that reproduces the position of a dental implant after insertion without the reuse of X-ray radiation. MATERIAL AND METHODS: An implant was inserted into the natural gap between the canines and premolars of three domestic pigs. A Straumann Scanbody was then screwed to the implant, and a digital impression of the jaw segment was made. The scanbody was scanned using a hand-held scanner. This was followed by the radiological detection of implant position on a CBCT. On the computer, the position of the implant was calculated and compared with the radiologically detected position. RESULTS: The calculated and determined position of the dental implant by the scanner is in good agreement with the radiologically controlled position. DISCUSSION: Evaluating the position of implants using intraoral scans is an easy and radiation-free method of three-dimensional site assessment after superimposition over a three-dimensional data set.

Perspectives on resorbable osteosynthesis materials in craniomaxillofacial surgery.

Since introduction to the clinics in the 1990s, resorbable osteosynthesis systems have undergone extensive improvements in order to establish their use as a standard treatment, especially in craniomaxillofacial surgery. However, the development of osteosynthesis systems made of poly(α-hydroxy acid) polymers has been hindered by the lack of information on the mechanical properties and biocompatibility of these materials. Moreover, magnesium-based degredable osteosynthesis materials have not yet been integrated into clinical practice owing to biocompatibility problems. Osteosynthesis systems made from nonresorbable titanium alloys have shown excellent biocompatibility, stability and individual fitting to the implant bed, so these materials are currently considered the 'gold standard'. The procedure of plate removal has been subjected to intense scrutiny and controversy. Bioresorbable materials are indicated for special conditions, such as osteosynthesis of the growing skull or orbital floor reconstructions. This paper presents an overview of the currently available and investigated resorbable osteosynthesis materials in comparison with the nonresorbable 'gold standard' titanium. The main problem areas such as sterilization, biocompatibility and stability are highlighted and perspectives for further improvements are provided.

Piezoelectric-assisted removal of a benign fibrous histiocytoma of the mandible: an innovative technique for prevention of dentoalveolar nerve injury.

In this article, we present our experience with a piezoelectric-assisted surgical device by resection of a benign fibrous histiocytoma of the mandible.A 41 year-old male was admitted to our hospital because of slowly progressive right buccal swelling. After further radiographic diagnosis surgical removal of the yellowish-white mass was performed. Histologic analysis showed proliferating histiocytic cells with foamy, granular cytoplasm and no signs of malignancy. The tumor was positive for CD68 and vimentin in immunohistochemical staining. Therefore the tumor was diagnosed as primary benign fibrous histiocytoma. This work provides a new treatment device for benign mandibular tumour disease. By using a novel piezoelectric-assisted cutting device, protection of the dentoalveolar nerve could be achieved.