Insights into Orbital Symmetry: A Comprehensive Retrospective Study of 372 Computed Tomography Scans.

Background: The operation planning and production of individualized implants with the help of AI-based software after orbital fractures have become increasingly important in recent years. This retrospective study aimed to investigate the healthy orbitae of 372 patients from CT images in the bone and soft tissue windows using the Disior™ Bonelogic™ CMF Orbital software. (version 2.1.28). Methods: We analyzed the variables orbital volume, length, and area as a function of age and gender and compared bone and soft tissue windows. Results: For all variables, the intraclass correlation showed excellent agreement between the bone and soft tissue windows (p < 0.001). All variables showed higher values when calculated based on bone fenestration with, on average, 1 mL more volume, 0.35 mm more length, and 0.71 cm2 more area (p < 0.001). Across all age groups, men displayed higher values than women with, on average, 8.1 mL larger volume, a 4.78 mm longer orbit, and an 8.5 cm2 larger orbital area (p < 0.001). There was also a non-significant trend in all variables and both sexes toward growth with increasing age. Conclusions: These results mean that, due to the symmetry of the orbits in both the bone and soft tissue windows, the healthy orbit can be mirrored for surgical planning in the event of a fracture.

Biomechanical Evaluation of Patient-Specific Polymethylmethacrylate Cranial Implants for Virtual Surgical Planning: An In-Vitro Study.

Cranioplasty with freehand-molded polymethylmethacrylate implants is based on decades of experience and is still frequently used in clinical practice. However, data confirming the fracture toughness and standard biomechanical tests are rare. This study aimed to determine the amount of force that could be applied to virtually planned, template-molded, patient-specific implants (n = 10) with an implant thickness of 3 mm, used in the treatment of a temporoparietal skull defect (91.87 cm2), until the implant cracks and finally breaks. Furthermore, the influence of the weight and porosity of the implant on its force resistance was investigated. The primary outcome showed that a high force was required to break the implant (mean and standard deviation 1484.6 ± 167.7 N), and this was very strongly correlated with implant weight (Pearson's correlation coefficient 0.97; p < 0.001). Secondary outcomes were force application at the implant's first, second, and third crack. Only a moderate correlation could be found between fracture force and the volume of porosities (Pearson's correlation coefficient 0.59; p = 0.073). The present study demonstrates that an implant thickness of 3 mm for a temporoparietal skull defect can withstand sufficient force to protect the brain. Greater implant weight and, thus, higher material content increases thickness, resulting in more resistance. Porosities that occur during the described workflow do not seem to reduce resistance. Therefore, precise knowledge of the fracture force of polymethylmethacrylate cranial implants provides insight into brain injury prevention and serves as a reference for the virtual design process.

Functional and Cosmetic Outcome after Reconstruction of Isolated, Unilateral Orbital Floor Fractures (Blow-Out Fractures) with and without the Support of 3D-Printed Orbital Anatomical Models.

The present study aimed to analyze if a preformed "hybrid" patient-specific orbital mesh provides a more accurate reconstruction of the orbital floor and a better functional outcome than a standardized, intraoperatively adapted titanium implant. Thirty patients who had undergone surgical reconstruction for isolated, unilateral orbital floor fractures between May 2016 and November 2018 were included in this study. Of these patients, 13 were treated conventionally by intraoperative adjustment of a standardized titanium mesh based on assessing the fracture's shape and extent. For the other 17 patients, an individual three-dimensional (3D) anatomical model of the orbit was fabricated with an in-house 3D-printer. This model was used as a template to create a so-called "hybrid" patient-specific titanium implant by preforming the titanium mesh before surgery. The functional and cosmetic outcome in terms of diplopia, enophthalmos, ocular motility, and sensory disturbance trended better when "hybrid" patient-specific titanium meshes were used but with statistically non-significant differences. The 3D-printed anatomical models mirroring the unaffected orbit did not delay the surgery's timepoint. Nonetheless, it significantly reduced the surgery duration compared to the traditional method (58.9 (SD: 20.1) min versus 94.8 (SD: 33.0) min, p-value = 0.003). This study shows that using 3D-printed anatomical models as a supporting tool allows precise and less time-consuming orbital reconstructions with clinical benefits.

Three-Dimensional Analysis of Isolated Orbital Floor Fractures Pre- and Post-Reconstruction with Standard Titanium Meshes and "Hybrid" Patient-Specific Implants.

The aim of this study was to compare the efficacy of the intraoperative bending of titanium mesh with the efficacy of pre-contoured "hybrid" patient-specific titanium mesh for the surgical repair of isolated orbital floor fractures. In-house 3D-printed anatomical models were used as bending guides. The main outcome measures were preoperative and postoperative orbital volume and surgery time. We performed a retrospective cohort study including 22 patients who had undergone surgery between May 2016 and November 2018. The first twelve patients underwent conventional reconstruction with intraoperative free-hand bending of an orbital floor mesh plate. The subsequent ten patients received pre-contoured plates based on 3D-printed orbital models that were produced by mirroring the non-fractured orbit of the patient using a medical imaging software. We compared the preoperative and postoperative absolute volume difference (unfractured orbit, fractured orbit), the fracture area, the fracture collapse, and the effective surgery time between the two groups. In comparison to the intraoperative bending of titanium mesh, the application of preformed plates based on a 3D-printed orbital model resulted in a non-significant absolute volume difference in the intervention group (p = 0.276) and statistically significant volume difference in the conventional group (p = 0.002). Further, there was a significant reduction of the surgery time (57.3 ± 23.4 min versus 99.8 ± 28.9 min, p = 0.001). The results of this study suggest that the use of 3D-printed orbital models leads to a more accurate reconstruction and a time reduction during surgery.

Fibula Graft Cutting Devices: Are 3D-Printed Cutting Guides More Precise than a Universal, Reusable Osteotomy Jig?

Individual cutting guides for the reconstruction of lower jaw defects with fibular grafts are often used. However, the application of these osteotomy tools is costly and time intensive. The aim of this study was to compare the precision of osteotomies using a 3D-printed guide with those using a universal, reusable, and more cost-efficient Multi-Use Cutting Jig (MUC-Jig). In this non-blinded experimental study, 10 cranio-maxillofacial surgeons performed four graft removals each in a randomized order using the same osteotomy angle, both proximally (sagittal cut) and distally (coronal cut), of a graft (45°, 30°, 15°, or 0°), first with the MUC-Jig then with the 3D-printed cutting guide. The 40 fibula transplants (Tx) of each method (n = 80) were then analyzed concerning their Tx length and osteotomy angles and compared to the original planning data. Furthermore, the surgeons' subjective perception and the duration of the two procedures were analyzed. The mean relative length and mean relative angle deviation between the MUC-Jig (-0.08 ± 1.12 mm; -0.69° ± 3.15°) and the template (0.22 ± 0.90 mm; 0.36° ± 2.56°) group differed significantly (p = 0.002; p = < 0.001), but the absolute deviations did not (p = 0.206; p = 0.980). Consequently, clinically comparable osteotomy results can be achieved with both methods, but from an economic point of view the MUC-Jig is a more cost-efficient solution.

The most common complications after wisdom-tooth removal: part 1: a retrospective study of 1,199 cases in the mandible.

The knowledge of potential complications after surgical removal of third molars and adequate risk assessment is indispensable in oral surgery. The present retrospective study analyzed the influence of different parameters, such as the patient’s age and gender, retention type, and radiological projection (using orthopantomography) of wisdom teeth on the mandibular canal on postoperative complications after the removal of 1,199 wisdom teeth. Overall, 101 (8.4%) complications occurred: 50 cases of alveolar osteitis (4.2%), 12 temporary (1%) and 6 persistent (0.5%) sensation disorders, 15 abscesses (1.25%), 7 dehiscences (0.6%), 5 cases of post-operative bleeding (0.4%), 4 sequestra (0.32%), 1 fistula (0.08%) and 1 hematoma (0.08%). The risk for developing alveolar osteitis was 6% for patients who suffered from a previous pericoronal infection and was higher for female than male patients. Smoking showed no influence on alveolar osteitis. A significant correlation (p<0.0001) could be shown between the radiological projection of wisdom teeth on the mandibular canal and post-operative sensation disorders. The experience of the surgeon and pre-operative 3-dimensional imaging (cone- beam computed tomography, computed tomography) did not reduce this risk. No correlation was found for patient’s age and gender. In conclusion, the surgical decision to remove wisdom teeth must be made with caution in cases of complete radiological projection of the wisdom tooth on the mandibular canal.

The most common complications after wisdom-tooth removal: part 2: a retrospective study of 1,562 cases in the maxilla.

The possible complications of wisdom-tooth removal must be considered, because it is the most common surgical intervention in dental practices. This retrospective study assessed the complications occurring during the removal of 1,562 maxillary wisdom teeth in 1,212 patients. A total of 543 cases of surgical removal and 1,019 cases of non-surgical removal were analyzed. In all cases, a pre-operative panoramic radiograph was taken. Anatomical and clinical parameters were included in the evaluation. 106 complications occurred in 92 patients (5.9%) of the total 1,562 operations. Of these complications, 5.1% were intra-operative and 0.8% postoperative. An oroantral fistula (OAF) was found in 38 cases (2.4%), and alveolar osteitis occurred post-operatively in 6 cases (0.4%). The risk of OAF correlated with increasing patient age (p=0.0368). Root fractures also increased the risk of OAF. On the basis of the analysis of pre-operative panoramic radiographs, it was shown that radiological projection of the root tips to the sinus floor is a reliable criterion to assess the risk of OAF.

Functional outcome after non-surgical management of orbital fractures--the bias of decision-making according to size of defect: critical review of 48 patients.

The treatment of mild and moderate fractures of the orbital wall is controversial. Apart from clinical signs, the size of the defect is often used to aid the decision about treatment. We hypothesised that variables would be present that had an impact on the position and motility of the globe but were independent of the size of the defect, and prevented a balanced judgement of the outcome of conservative treatment. Between January 2000 and December 2007, 48 of 127 patients were included in this retrospective study to analyse the functional outcome of orbital fractures managed without operation. Selection was dependent on the availability of complete clinical records, post-traumatic computed tomographic (CT) scans (axial and coronal sections) and ophthalmic examination. All 48 defects were analysed and allocated to categories of a semiquantitative classification. The area of fracture of each defect was calculated with an integral calculus or geometrical formula and correlated with the associated category. Category A included all orbital walls as a single unit (A1) and combined fracture patterns (A2 and higher). Category B described isolated fractures of the medial wall. There was a significant correlation between classes A1 and A2 (p<0.01) and absolute area of the fracture (0.98 (0.4)cm(2) and 2.42 (0.8)cm(2)). Diplopia was most often seen in fractures in category B1 (the anterior third of the medial wall) and the post-traumatic position of the globe significantly correlated with the area of the fracture (p=0.04). The degree of diplopia was less severe in fractures of the posterior portion of the orbit (zones 2 and 3) compared with fractures of the anterior orbit, even if the defect was larger. The conservative management of category A1-3 and B1-3 fractures up to 2.42 (3.15)cm(2) showed no functional impairment, provided that enophthalmos was less than 2mm and there was no entrapment of periorbital tissue or extraocular muscles. We found good correlation between enopthalmos and the size of the fracture, but not for diplopia or motility of the eye. We conclude that conservative management of an orbital fracture in which the defect is less than 3cm(2) has a low risk of permanent functional damage if enophthalmos is less than 2mm and entrapment of soft tissue or muscles is excluded.

A gossypiboma (foreign body granuloma) mimicking a residual odontogenic cyst in the mandible: a case report.

INTRODUCTION: Gossypiboma (foreign body granuloma) in the tooth socket as a complication of tooth removal is rare. Several cases of gossypiboma have been reported after orthopedic, abdominal, otorhinolaryngology, or plastic surgery, but there has been only one reported case after oral surgery. CASE PRESENTATION: A 42-year-old Caucasian German-speaking Swiss woman applied to our clinic for removal of her right mandibular first molar. Her right mandibular third molar had been removed seven years ago. Post-operatively, she complained of pain and foreign body sensation for six months in the area of the removed tooth. A panoramic radiograph of our patient showed a defined and oval radiolucent area in the socket of the right mandibular third molar evoking a residual cyst. An operation was planned to remove the cyst-like lesion. During surgery, a foreign body composed of gauze was found in the right mandibular third molar region. The histological findings were compatible with a foreign body reaction around gauze. CONCLUSION: Retained gauze must be considered if patients complain of pain and foreign body sensation after tooth removal. The use of gauze with radio-opaque markers and extensive irrigation of the socket with saline to remove gauze fragments can avoid this mishap.