New method for analysing spatial relationships of facial muscles on MRI: a pilot study

Dysfunction of the facial musculature can have significant physical, social, and psychological consequences. In surgeries such as cleft surgery or craniofacial bimaxillary osteotomies, the perioral facial muscles may be detached or severed, potentially altering their functional vectors and mimicry capabilities. Ensuring correct reconstruction and maintenance of anatomical sites and muscle vectors is crucial in these procedures. However, a standardized method for perioperative assessment of the facial musculature and function is currently lacking. The aim of this study was to develop a workflow to analyse the three-dimensional vectors of the facial musculature using magnetic resonance imaging (MRI) scans. A protocol for localizing the origins and insertions of these muscles was established. The protocol was implemented using the 3DMedX computer program and tested on 7 Tesla MRI scans obtained from 10 healthy volunteers. Inter- and intra-observer variability were assessed to validate the protocol. The absolute intra-observer variability was 2.6 mm (standard deviation 2.0 mm), and absolute inter-observer variability was 2.6 mm (standard deviation 1.5 mm). This study presents a reliable and reproducible method for analysing the spatial relationships and functional significance of the facial muscles. The workflow developed facilitates perioperative assessment of the facial musculature, potentially aiding clinicians in surgical planning and potentially enhancing the outcomes of midface surgery.

[Is there more to hypodontia then missing teeth?]

Dental care professionals regularly see patients with hypodontia. Hypodontia can be acquired, for example through chemotherapy or radiation at a young age, but is hereditary in most patients. Due to an error (pathogenic variant) in one of the many genes that control odontogenesis, the formation of the tooth germ is disrupted at an early stage. The genes involved are not only crucial for tooth development, but they also play an important role in other physical processes. This article provides background information on hypodontia. Based on an inventory of gastrointestinal complaints in patients with hypodontia and a case description of the simultaneous occurrence of a coagulation disorder and hypodontia, the importance of a broad view of this patient group is illustrated. It is concluded that, in addition to a dental assessment, examination of these patients should include a limited physical examination and the medical history of the patient and his close relatives.

The average three-dimensional face for different sex and age groups in a Dutch population

The increasing use of three-dimensional imaging calls for reference models representing large parts of the population. The aim of this prospective study was to create templates depicting facial maturation in the younger age groups. Healthy Dutch volunteers were captured, without selection of inclusions. Three-dimensional average faces were created using MATLAB, for both genders in four age groups (4-8 years, 8-12 years, 12-16 years, and ≥16 years). Variation within the groups was calculated and depicted on an average face with a green to red colour scale, corresponding to standard deviations between 0 and ≥ 3 mm, respectively. Measurements of the distances of eight peri-oral landmarks were provided as ratios. The statistical analysis was performed using ANOVA and Tukey's test. Three-dimensional reconstructions of the average face and their first principal component were created for each gender and age group. The first principal component comprised the facial width for each group, and the variation of landmarks was low. All ratios showed an increasing trend with increasing age, except for the ratio of philtrum width to mouth width. This study is novel in comparing facial morphology by means of ratios and in creating average faces for the different young age groups. These data provide useful insights into facial maturation, which might be beneficial for facial surgeons.

Value of cone beam computed tomography for detecting bone invasion in squamous cell carcinoma of the maxilla

OBJECTIVE

To determine the diagnostic value of cone beam computed tomography (CBCT) in detecting bone invasion in maxillary squamous cell carcinoma (MSCC).

STUDY DESIGN

In this retrospective cohort study, preoperative CBCT scans were independently assessed by a single surgeon in imaging assessment 1 (IA 1) and by 1 surgeon with 2 dentists in consensus (IA 2) for the presence of bone invasion in MSCC. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, area under the receiver operating characteristic curve (AUC), and Cohen's κ were calculated. Histopathologic results of resection specimens served as the reference standard.

RESULTS

Of 27 patients, 19 (70%) had proven bone invasion. IA 1 yielded 68.4% sensitivity, 75.0% specificity, 86.7% PPV, 50.0% NPV, 70.4% accuracy, and 0.717 AUC. All results of IA 2 were true-positive and true-negative, resulting in 100% sensitivity, specificity, PPV, NPV, accuracy, and AUC. The assessments differed in 6 cases. Interobserver κ was fair (0.38, 95% CI 0.04-0.72, P = .038). There was a significant association between CBCT detection of bone invasion and extent of surgical treatment (P = .006) CONCLUSIONS: The diagnostic accuracy of CBCT was high but observer-dependent. CBCT examination may be useful in surgical treatment planning.

[Reconstruction of the mandible after loss of the middle segment due to an odontogenic myxoma]

In an 18-year-old boy, the middle segment of the mandible was removed because of a locally aggressive tumour. The reconstruction became infected and was lost, resulting in 2 separately-moving mandible parts and oral disability. For the second reconstruction, skeletal fixation with osteosynthesis plates, dental fixation with a stabilization frame and intermaxillary fixation were used. Preparation for returning the jaws to their original position was facilitated by three-dimensional simulation software. After a successful second reconstruction, an implant-supported removable bridge was eventually placed.

A Novel Method for Quantitative Three-Dimensional Analysis of Zygomatico-Maxillary Complex Symmetry

To develop a reliable and accurate method to quantify the symmetry of the zygomaticomaxillary complex (ZMC).

Zygomaticomaxillary complex fracture repair with intraoperative CBCT imaging. A prospective cohort study

The aim of this study was to evaluate the value of intraoperative conebeam computed tomography (CBCT) imaging in the treatment of zygomaticomaxillary complex (ZMC) fractures. A prospective single center cohort study was performed. Included were consecutive patients who underwent surgery for a unilateral ZMC fracture. An intraoperative CBCT scan was performed after reduction of the ZMC fracture. Revision reduction was performed of the ZMC and/or orbital floor (OF) on indication. The preoperative and postoperative asymmetry of the outer surface of the ZMC was measured on digital 3D-models of CBCT scans, using a mirroring and surface-based matching technique. The postoperative asymmetry of the ZMC in the study group was compared to the asymmetry of the ZMC in the control group with healthy individuals. A total of 38 patients with a unilateral ZMC fracture were included. The mean postoperative asymmetry in the study group (1.67 mm, SD 0.89) was less than the mean preoperative asymmetry (2.69 mm, SD 0.95) (paired samples T-test p < 0.01) but showed no statistically significant difference with the mean asymmetry in the healthy control group (1.40 mm, SD 0.54) (independent samples T-test p = 0.31). Revision reduction of the ZMC and/or OF fracture had been performed in 11 cases after malalignment was noted on the intraoperative CBCT. The indication for intraoperative revision reduction was associated with comminuted ZMC fractures and/or fractures with indication for OF reduction (Pearson Chi Square p < 0.01). Within the limitations of the study, intraoperative CBCT imaging seemed to have a positive influence on ZMC fracture treatment, especially in the case of comminuted ZMC fractures and/or fractures with indication for OF treatment.

Endochondral Bone Regeneration by Non-autologous Mesenchymal Stem Cells

Mimicking endochondral bone formation is a promising strategy for bone regeneration. To become a successful therapy, the cell source is a crucial translational aspect. Typically, autologous cells are used. The use of non-autologous mesenchymal stromal cells (MSCs) represents an interesting alternative. Nevertheless, non-autologous, differentiated MSCs may trigger an undesired immune response, hampering bone regeneration. The aim of this study was to unravel the influence of the immune response on endochondral bone regeneration, when using xenogeneic (human) or allogeneic (Dark Agouti) MSCs. To this end, chondrogenically differentiated MSCs embedded in a collagen carrier were implanted in critical size femoral defects of immunocompetent Brown Norway rats. Control groups were included with syngeneic/autologous (Brown Norway) MSCs or a cell-free carrier. The amount of neo-bone formation was proportional to the degree of host-donor relatedness, as no full bridging of the defect was observed in the xenogeneic group whereas 2/8 and 7/7 bridges occurred in the allogeneic and the syngeneic group, respectively. One week post-implantation, the xenogeneic grafts were invaded by pro-inflammatory macrophages, T lymphocytes, which persisted after 12 weeks, and anti-human antibodies were developed. The immune response toward the allogeneic graft was comparable to the one evoked by the syngeneic implants, aside from an increased production of alloantibodies, which might be responsible for the more heterogeneous bone formation. Our results demonstrate for the first time the feasibility of using non-autologous MSC-derived chondrocytes to elicit endochondral bone regeneration in vivo. Nevertheless, the pronounced immune response and the limited bone formation observed in the xenogeneic group undermine the clinical relevance of this group. On the contrary, although further research on how to achieve robust bone formation with allogeneic cells is needed, they may represent an alternative to autologous transplantation.

Feasibility of CT quantification of intratumoural 166Ho-microspheres

Background

Microspheres loaded with radioactive ¹⁶⁶Ho (¹⁶⁶Ho-MS) are novel particles for radioembolisation and intratumoural treatment. Because of the limited penetration of β radiation, quantitative imaging of microsphere distribution is crucial for optimal intratumoural treatment. Computed tomography (CT) may provide high-resolution and fast imaging of the distribution of these microspheres, with lower costs and widespread availability in comparison with current standard single-photon emission tomography (SPECT) and magnetic resonance imaging. This phantom study investigated the feasibility of CT quantification of ¹⁶⁶Ho-MS.

Methods

CT quantification was performed on a phantom with various concentrations of HoCl and Ho-MS to investigate the CT sensitivity and calibrate the CT recovery. ¹⁶⁶Ho-MS were injected into ex vivo tissues, in VX-2 cancer-bearing rabbits, and in patients with head-neck cancer, to demonstrate sensitivity and clinical visibility. The amount of Ho-MS was determined by CT scanning, using a density-based threshold method and compared with a validated ¹⁶⁶Ho SPECT quantification method.

Results

In the phantom, a near perfect linearity (least squares R² > 0.99) between HU values and concentration of ¹⁶⁶Ho was found. Ex vivo tissue experiments showed an excellent correlation (r = 0.99, p < 0.01) between the dose calibrator, SPECT, and CT imaging. CT recovery was on average 86.4% ex vivo, 76.0% in rabbits, and 99.1% in humans.

Conclusion

This study showed that CT-based quantification of Ho microspheres is feasible and is a high-resolution alternative to SPECT-based determination of their local distribution.

Low skeletal muscle mass is a strong predictive factor for surgical complications and a prognostic factor in oral cancer patients undergoing mandibular reconstruction with a free fibula flap

BACKGROUND

Fibula free flaps (FFF) are effective in accomplishing successful reconstruction for segmental defects of the mandible. Potential risk factors for FFF complications have been described in previous research, e.g. age, comorbidity and smoking. Low skeletal muscle mass (SMM) has shown to be an emerging predictive factor for complications and prognostic factor for survival in head and neck cancer. This study aims to identify the predictive and prognostic value of low SMM for surgical FFF related complications, postoperative complications and survival in patients who underwent mandibular reconstruction with FFF after oral cavity cancer resection.

MATERIALS AND METHODS

A retrospective study was performed between 2002 and 2018. Pre-treatment SMM was measured at the level of the third cervical vertebra and converted to SMM at the level of the third lumbar vertebra (L3). SMM at the level of L3 was corrected for squared height. Low SMM was defined as a lumbar skeletal muscle index (LSMI) below 43.2 cm²/m².

RESULTS

78 patients were included, of which 48 (61.5%) had low SMM. Low SMM was associated with an increased risk of FFF related complications (HR 4.3; p = 0.02) and severe postoperative complications (Clavien-Dindo grade III-IV) (HR 4.0; p = 0.02). In addition low SMM was a prognosticator for overall survival (HR 2.4; p = 0.02) independent of age at time of operation, ACE-27 score and TNM stage.

CONCLUSION

Low SMM is a strong predictive factor for FFF reconstruction complications and other postoperative complications in patients undergoing FFF reconstruction of the mandible. Low SMM is also prognostic for decreased overall survival.

Inflammatory pseudotumour of the alveolar process of the maxilla as clinical manifestation of IgG4-related disease: a case report and literature review

IgG4-related disease (IgG4-RD) is an uncommon immune-mediated condition considered to be a systemic disease, described in multiple organ systems. IgG4-RD that involves the maxillary and sinonasal region is rare. This report presents a very rare presentation of IgG4-RD in the maxillary alveolar process. The patient presented with left-sided facial pain, headache, and mobility and loss of teeth. The first biopsy and resection specimen reports were inconclusive and showed a non-specific chronic inflammatory process. After the third resection, the diagnosis was finally established through findings that satisfied the 2012 consensus criteria for IgG4-RD. Consequently high doses of oral corticosteroids and azathioprine were given, tapered over a total period of 36 months. Weaning is still in progress, but no recurrence was observed after 34 months. A review of the English-language literature was performed, which identified seven cases of IgG4-RD with maxillary and sinonasal involvement. Cases were excluded from the review if there was any doubt that they met the consensus statement on the pathology.

Articular soft tissue injuries associated with mandibular condyle fractures and the effects on oral function

The majority of studies debating the optimization of treatment for condylar mandibular fractures focus on the bony aspect first. However, fractures of the mandibular condyle may go together with soft tissue injury of the temporomandibular joint. An electronic literature search for this topic was undertaken. Assessment of quality was carried out using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Sixteen articles were included in this review. The reviewed literature showed that intracapsular fractures and dislocated condylar fractures result in more severe injuries. Serious injury to the disc and capsule of the temporomandibular joint is a contributing factor towards development of complications after closed treatment. The results of this review give an overview of the published studies focusing on articular soft tissue injuries caused by condylar mandibular fractures. Additionally, an overview of the magnetic resonance imaging (MRI) settings used to detect these injuries is provided. Until now, the relation between soft tissue injuries and type of condylar trauma and their influence on clinical outcome has been insufficiently investigated. Before considering reduction of soft tissues next to reduction of the fracture, more research is needed into the impact of soft tissue injuries on oral functioning, in which a uniform classification is used.

The impact of immune response on endochondral bone regeneration

Tissue engineered cartilage substitutes, which induce the process of endochondral ossification, represent a regenerative strategy for bone defect healing. Such constructs typically consist of multipotent mesenchymal stromal cells (MSCs) forming a cartilage template in vitro, which can be implanted to stimulate bone formation in vivo. The use of MSCs of allogeneic origin could potentially improve the clinical utility of the tissue engineered cartilage constructs in three ways. First, ready-to-use construct availability can speed up the treatment process. Second, MSCs derived and expanded from a single donor could be applied to treat several patients and thus the costs of the medical interventions would decrease. Finally, it would allow more control over the quality of the MSC chondrogenic differentiation. However, even though the envisaged clinical use of allogeneic cell sources for bone regeneration is advantageous, their immunogenicity poses a significant obstacle to their clinical application. The aim of this review is to increase the awareness of the role played by immune cells during endochondral ossification, and in particular during regenerative strategies when the immune response is altered by the presence of implanted biomaterials and/or cells. More specifically, we focus on how this balance between immune response and bone regeneration is affected by the implantation of a cartilaginous tissue engineered construct of allogeneic origin.

Preventing hypoesthesia after a buccal plate fracture in a sagittal split procedure: A technical note

If during a sagittal split osteotomy a buccal plate fracture occurs, it inevitably results in a time-consuming procedure with, in many cases, hypoesthesia of the mental region as a consequence of manipulation of the inferior alveolar nerve. We would like to present a novel technique to solve a (threatening) buccal plate fracture that is quick and easy to perform, and has thus far not resulted in hypoesthesia.

A novel digital workflow to manufacture personalized three-dimensional-printed hollow surgical obturators after maxillectomy

Partial or complete resection of the maxilla during tumour surgery causes oronasal defects, leading to oral-maxillofacial dysfunction, for which the surgical obturator (SO) is an important treatment option. Traditional manufacturing of SOs is complex, time-consuming, and often results in inadequate fit and function. This technical note describes a novel digital workflow to design and manufacture a three-dimensional (3D)-printed hollow SO. Registered computed tomography and magnetic resonance imaging images are used for gross tumour delineation. The produced RTStruct set is exported as a stereolitography (STL) file and merged with a 3D model of the dental status. Based on these merged files, a personalized and hollow digital SO design is created, and 3D printed. Due to the proper fit of the prefabricated SO, a soft silicone lining material can be used during surgery to adapt the prosthesis to the oronasal defect, instead of putty materials that are not suitable for this purpose. An STL file of this final SO is created during surgery, based on a scan of the relined SO. The digital workflow results in a SO weight reduction, an increased fit, an up-to-date digital SO copy, and overall easier clinical handling.

Watchful waiting of the neck in early stage oral cancer is unfavourable for patients with occult nodal disease

For cT1/2N0 oral squamous cell carcinoma (OSCC), treatment of the neck is a matter of debate. Two treatment strategies were evaluated in this study: selective neck dissection (SND) and watchful waiting (WW). One hundred and twenty-three SND patients and 70 WW patients with cT1/T2N0M0 OSCC of the tongue, floor of mouth, or buccal mucosa were analysed retrospectively. Extracapsular spread (ECS), 3-year overall survival (OS), and disease-specific survival (DSS) were determined. Twenty-nine percent of SND patients and 13% of WW patients had occult nodal disease. WW-N+ patients showed thicker tumours as compared to WW-N0 patients (5mm vs. 2mm, P=0.02). WW-N+ patients showed significantly more ECS as compared to SND-N+ patients (56% vs. 14%, P=0.016) and had a significantly worse 3-year DSS than SND-N+ patients (56% vs. 82%, P=0.02). For T1 OSCCs, a watchful waiting policy is acceptable if tumour thickness proves to be <4mm. Otherwise, an additional treatment of the neck is advised, since WW-N+ patients show more ECS, with a worse DSS than SND-N+ patients.

Predictive factors for premature loss of Martin 2.7 mandibular reconstruction plates

Mandibular reconstruction with a plate, with or without a vascularised free (bone) flap, is commonly used to treat patients with a segmental mandibular defect. Common complications are loosening of the osteosynthesis screws, malposition, intraoral or extraoral exposure, or infection. To define prognostic factors for premature loss of such plates and improve future planning, we designed a retrospective study of all patients operated on between 2005 and 2011 for reconstruction of a mandibular segmental defect with a reconstruction plate with or without a free vascularised (bone) flap. Prognostic factors collected from medical records were the patient's age, sex, and American Society of Anesthesiologists (ASA) grade; treatment with radiotherapy; whether they had diabetes or smoked; the site of the mandibular defect; whether there was a dental occlusion; the number of screws used on each side, and the use of a free vascularised (bone) flap; and whether the diagnosis was of oral cancer, benign tumour, or trauma. One hundred patients were included, 79 with oral cancer, 19 with benign tumours, and 2 with trauma. In 20 patients the Martin 2.7 reconstruction plate failed. Diabetes and smoking were significant prognostic factors for premature loss of the reconstruction plate with a hazard ratio of 2.95 (95% CI 1.068-8.172), p value=0.04, for diabetes, and 2.42 (95% CI 1.006-5.824), p value=0.05, for smoking. Smokers and diabetic patients have a higher risk of failure after mandibular reconstruction with a 2.7 reconstruction plate.

The influence of a Le Fort I impaction and advancement osteotomy on smile using a modified alar cinch suture and V-Y closure: a prospective study

A previous report from the authors' department showed that a modified alar cinch suture combined with a muco-musculo-periosteal V-Y closure (mACVY) improves nasolabial mobility. To test if the improvements were equal to the range of nasolabial mobility in non-dysgnathic persons, a prospective study was carried out in 56 patients: 31 with mACVY, 25 with simple closing sutures (SCS) and 18 non-operated, angle class I volunteers. Standardized full facial frontal photographs, taken immediately preoperatively and 18 months postoperatively were used. The landmarks, alare, crista philtri and cheilion were analysed. The test has a standard deviation of 0.9 mm. Intra-group changes, paired t-test, and inter-group differences, unpaired t-test (p<0.05) were statistically analysed. The results show significant preoperative differences in nasolabial mobility compared with the control group, for both groups. Postoperative mobility improved in both groups, but significantly with mACVY with horizontal movement of cheilion and alare, and the vertical movement of crista philtri and less so for the vertical movement of crista philtri with SCS. Postoperative inter-group differences in mobility were small and significant for SCS vs the control group. It can be concluded that using mACVY improves orofacial movement to the level of normal class I volunteers.

[Obstructive sleep-apnoea syndrome: good results with maxillo-mandibular osteotomy after failure of conservative therapy]

A 36-year-old woman and a 49-year-old man with symptoms of an obstructive sleep-apnoea syndrome benefited insufficiently from the therapy of choice, i.e. treatment with continuous positive airway pressure. Minor surgical procedures to improve the upper airways did not have the desired effect. Subsequently, maxillo-mandibular osteotomy was performed. Thereafter, both the daytime somnolence and the snoring during sleep disappeared. Indications for osteotomy of the maxilla and mandible are: failure of conservative therapy or other forms of treatment with a lower morbidity, severe mandibular hypoplasia, extreme respiratory distress and morbid obesity. Ventral displacement of the maxilla or mandible eliminates the obstruction at the level of the base of the tongue. The operation is successful for the first year in 95% of the patients. A disadvantage is the temporary post-operative morbidity.