An open-source, three-dimensional growth model of the mandible.

The available reference data for the mandible and mandibular growth consists primarily of two-dimensional linear or angular measurements. The aim of this study was to create the first open-source, three-dimensional statistical shape model of the mandible that spans the complete growth period. Computed tomography scans of 678 mandibles from children and young adults between 0 and 22 years old were included in the model. The mandibles were segmented using a semi-automatic or automatic (artificial intelligence-based) segmentation method. Point correspondence among the samples was achieved by rigid registration, followed by non-rigid registration of a symmetrical template onto each sample. The registration process was validated with adequate results. Principal component analysis was used to gain insight in the variation within the dataset and to investigate age-related changes and sexual dimorphism. The presented growth model is accessible globally and free-of-charge for scientists, physicians and forensic investigators for any kind of purpose deemed suitable. The versatility of the model opens up new possibilities in the fields of oral and maxillofacial surgery, forensic sciences or biological anthropology. In clinical settings, the model may aid diagnostic decision-making, treatment planning and treatment evaluation.

Efficacy and Toxicity of Calcitonin Treatment in Children with Cherubism: A Single-Center Cohort Study.

Cherubism is a rare autosomal dominant disease characterized by expansile osteolytic jawbone lesions. The effect and safety of off-label calcitonin treatment during the progressive phase of the disease are not well described. In this retrospective study, we present data on the radiological response and adverse effects of subcutaneously administered calcitonin in a cohort of nine cherubism children (three female, six male). Two of the nine patients underwent two separate treatment courses with a significant off-treatment interval in between; therefore, a total of 11 treatment courses with a mean duration of 17.9 months (range <1 to 35, SD 10.8) were studied. To measure the response, the cumulative volume of cherubism lesions was calculated from available three-dimensional imaging. The primary outcome was the change in the volume of lesions during calcitonin treatment and only assessed for the eight treatment courses with a minimal duration of 6 months. A statistically significant reduction in the mean cumulative volume of lesions was seen regardless of treatment duration. Average volume reduction was highest in the first half year of treatment, with a gradual, ongoing reduction thereafter. For the secondary outcome, the change in the cumulative volume of lesions after treatment cessation was assessed for the seven treatment courses with follow-up imaging available. After six of these seven treatment courses, the cumulative volume increased again but remained undoubtedly smaller than the initial volume at the start of therapy. Adverse effects were assessed for all 11 treatment courses and occurred in 73% of them. Most adverse effects were mild and low grade, with the most severe being one grade 3 symptomatic hypocalcemia requiring hospitalization and early treatment termination. Calcitonin treatment seems effective and tolerable in treating actively progressing cherubism in children. However, further research is required to better understand the pharmacological treatment of cherubism, including also other drugs, dosing, and protocols. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Contact stress distribution after unilateral condylar fracture with angulation of the fractured part: A finite element model study.

After a fracture of the condyle, the head of the condyle is often pulled inwards, which causes the fractured part to angulate medially. This change can cause a disbalance in the masticatory system. The disbalance could lead to contact stress differences within the temporomandibular joints (TMJs) which might induce remodelling within the TMJ to restore the balance. The contact stress in the fractured condyle during open and closing movements is expected to decrease, while the contact stress in the non-fractured condyle will increase. In a clinical situation this is hard to investigate. Therefore, a finite element model (FEM) was used. In the FEM a fractured right condyle with an angulation was induced, which was placed at different degrees, varying from 5° to 50° in steps of 5°. This study shows only minor differences in amount of contact stress between the fractured and the non-fractured condyle. The amount of contact stress in the condyles does not increase with a higher degree of angulation. However, with larger angulations, the contact stress within the fractured condyle is more centralized. Clinically, this more centralized area could be associated with complaints, such as pain. In conclusion, due to the more centralized contact stress in the fractured condyle, one would expect some minor remodelling on the fractured side with more angulation.

Changes in load distribution after unilateral condylar fracture: A finite element model study.

OBJECTIVE: Premature dental contact on the fractured side and a contralateral open bite are signs of a unilaterally fractured condyle of the temporomandibular joint (TMJ). The lateral pterygoid muscle pulls the condyle inwards, causing angulation of the fractured part and shortening of the ramus. This imbalance after fracture might change the load in both TMJs and consequently induce remodeling. The present study aimed to calculate this change in load. It is hypothesized to decrease on the fractured side and increase on the non-fractured side. DESIGN: For these calculations, a finite element model (FEM) was used. In the FEM, shortening of the ramus varied from 2 mm to 16 mm; angulation, from 6.25° to 50°. RESULTS: After fracture, load on the non-fractured side increased, but only at maximal mouth opening (MMO). Simultaneously, load on the fractured side decreased, at both timepoints, i.e., MMO and closed mouth. When comparing all simulations at those time points, i.e., from 2 mm and 6.25° to 16 mm and 50°, the load in the fractured condyle declines steadily. However, for both timepoints, a threshold stands out around 6 mm shortening and 18.75° angulation: visualization of the fractured condyle showed, apart from load on the condylar head, a second point of load more medial in the TMJ which was most evident in the 6 mm - 18.75° simulation. CONCLUSIONS: These findings could implicate that the balance between both TMJs is more difficult to restore after a fracture with more than 6 mm shortening and more than 18.75° angulation.

Load distribution after unilateral condylar fracture with shortening of the ramus: a finite element model study.

OBJECTIVES: After a fracture of the condyle, the fractured ramus is often shortened, which causes premature dental contact on the fractured side and a contralateral open bite. The imbalance could change the load in the temporomandibular joints (TMJs). This change could lead to remodelling of the TMJs to compensate for the imbalance in the masticatory system. The load in the non-fractured condyle is expected to increase, and the load in the fractured condyle to decrease. MATERIALS AND METHODS: These changes cannot be measured in a clinical situation. Therefore a finite element model (FEM) of the masticatory system was used. In the FEM a fractured right condyle with shortening of the ramus was induced, which varied from 2 to 16 mm. RESULTS: Results show that, with a larger shortening of the ramus, the load in the fractured condyle decreases and the load in the non-fractured condyle increases. In the fractured condyle during closed mouth a major descent in load, hence a cut-off point, was visible between a shortening of 6 mm and 8 mm. CONCLUSIONS: In conclusion, the change of load could be associated with remodelling on both condyles due to shortening of the ramus. CLINICAL RELEVANCE: The cut-off point implies that shortening over 6 mm could present more difficulty for the body to compensate.

Normal variation of mandibular asymmetry in children.

OBJECTIVE: To explore the normal variation of asymmetry in mandibles of children in the age group of 1 to 12 years. MATERIALS AND METHODS: The study group consisted of 92 cadaveric mandibles of children with a dental age of 1 to 12 years old in possession of ACTA (Academic Centre for Dentistry Amsterdam), Faculty of Dentistry, the Netherlands. 3D models of the mandibles were obtained from CT-scans and hemimandibular volumes of all mandibles were calculated. The condylar height, ramus height, mandibular body length and the gonial angle were bilaterally determined using a novel landmark-based method, and the degree of asymmetry was calculated. RESULTS: No relationship was found between dental age and asymmetry of the studied parameters (P < .05). The highest degree of asymmetry was found in the ramus height, whereas the gonial angle presented the lowest degree of asymmetry. A positive correlation was found between the asymmetry of the hemimandibular volume vs the height of the ramus (P < .05) and the length of the mandibular body (P < .05). An inverse correlation was found between the asymmetry of the ramus height vs the condylar height (P < .05), mandibular body length (P < .05) and gonial angle (P < .05). CONCLUSIONS: Mandibular asymmetries in children did occur (9.8% of the included mandibles presented with a relevant overall asymmetry of ≥3%) and were unrelated to age. The different segments of the mandible seem to compensate for each other, in order to maintain a functional equilibrium.

Management of Asymmetry.

Orthognathic surgery in asymmetric cases is challenging because of diversity and individuality. Clinical observations are of paramount importance and need to be systemically thorough. Three-dimensional diagnosis and virtual planning have been proven extremely helpful in facilitating treatment toward symmetry in difficult cases with increasing precision. Compared with orthognathic surgery in symmetric situations, asymmetries produce numerous pitfalls and provide opportunities for out-of-the-box procedures.

RANKL inhibition for giant cell lesions of the jaw: A retrospective cohort analysis.

BACKGROUND: In all giant-cell-rich lesions (GCRL) occurring in bone, a common underlying excessive RANKL expression is held responsible for the osteolytic activity. Apart from giant cell tumour of bone (GCTB), systematic outcome analysis of RANKL inhibition in other GCRL is unavailable. The aim of this study is to assess the efficacy and safety of a 1-year denosumab protocol in giant cell lesions of the jaw (GCLJ). METHODS: A retrospective cohort study was conducted compromising patients treated with a 1-year protocol of monthly subcutaneously administered 120 mg denosumab. Objective tumour response based on histology and imaging was used to calculate objective tumour response rate, progression-free survival (PFS) and time to progression. Type, severity and frequency of adverse events were recorded in a standardised way to assess safety. RESULTS: Twenty patients, predominantly female (90%), were included. Fifty-five per cent of lesions were located in the mandible; most classified as aggressive lesions (90%). Thirty-five per cent (7/20) of cases were either recurrent after prior treatment or progressive, while on other drug treatment. Objective tumour response rate was 100% after 12 months of treatment. Median PFS was 50.4 months (95% CI 38.0-62.8) with a cumulative PFS rate of 22.6% (95% CI 1.8-43.4) at 5 years follow-up. Median time to progression was 38.4 months (95% CI 26.0-50.8). Treatment was well tolerated, and none of the patients had to interrupt therapy for toxicity. CONCLUSION: High-dose denosumab is effective and safe in achieving a complete response in GCLJ within 12 months. The high long-term relapse rate after treatment cessation is the main obstacle for denosumab to become standard treatment for GCLJ.

Intra-individual variation of upper airway measurements based on computed tomography.

The aims of this study were (1) to quantify the intra-individual variation in the upper airway measurements on supine computed tomography (CT) scans at two different time points; and (2) to identify the most stable parameters of the upper airway measurements over time. Ten subjects with paired CT datasets (3-6 months interval) were studied, using computer software to segment and measure the upper airway. The minimum cross-sectional area of the total airway and all its segments (velopharynx, oropharynx, tongue base, and epiglottis) generally had the largest variation, while the length of the total airway had the lowest variation. Sphericity was the only parameter that was stable over time (relative difference <15%), both in the total airway and each subregion. There was considerable intra-individual variation in CT measurements of the upper airway, with the same patient instruction protocol for image acquisitions. The length of the total airway, and the sphericity of the total upper airway and each segment were stable over time. Hence, such intra-individual variation should be taken into account when interpreting and comparing upper airway evaluation parameters on CT in order to quantify treatment results or disease progress.

Minimally Invasive Treatment With a Patient Specific Implant in Reconstruction of Isolated Anterior Wall Fracture of the Frontal Sinus.

ABSTRACT: Isolated fractures of the anterior wall of the frontal sinus are most often treated through a coronal approach. Although the coronal approach is a relatively easy procedure, the size of the incision is causing more problems related to patient morbidity and recovery time than smaller approaches. A novel, minimal invasive procedure for reconstruction of the anterior wall fracture of the frontal sinus is presented in this article. An endoscopic assisted approach to camouflage the defect of the anterior wall and restore the contour of the frontal bone with a titanium patient specific implant is described in 2 patients. The aim of this procedure is to evaluate the effect on the operating time, recovery time, length of hospital stay and facial scarring compared to the conventional coronal approach. Postoperative evaluation was performed by superimposing pre and postoperative 3D stereophotographs and computed tomography scans. A distance map demonstrated an accurate reconstruction of the preoperatively planned contour. Postoperative recovery of both patients was quick and uneventful with no complications. The use of endoscopically inserted patient specific implant for contour reconstruction in anterior wall fractures of the frontal sinus seems to offer a predictable and minimal invasive alternative to the conventional approach.

Diagnosing Internal Herniation After Roux-en-Y Gastric Bypass Surgery: Literature Overview, Cadaver Study and the Added Value of 3D CT Angiography.

PURPOSE: The purposes of the study are to outline the complexity of diagnosing internal herniation after Roux-en-Y gastric bypass (RYGB) surgery and to investigate the added value of computed tomography angiography (CTA) for diagnosing internal herniation. MATERIALS AND METHODS: A cadaver study was performed to investigate the manifestations of internal hernias and mesenteric vascularization. Furthermore, a prospective, ethics approved study with retrospective interpretation was conducted. Ten patients, clinically suspected for internal herniation, were prospectively included. After informed consent was obtained, these subjects underwent abdominal CT examination, including additional arterial phase CTA. All subjects underwent diagnostic laparoscopy for suspected internal herniation. The CTA was used to create a 3D reconstruction of the mesenteric arteries and surgical staples (3D CTA). The 3D CTA was interpreted, taking into account the presence and type of internal hernia that was found upon laparoscopy. RESULTS: Cadaveric analysis demonstrated the complexity of internal herniation. It also confirmed the expected changes in vascular structure and surgical staple arrangement in the presence of internal herniation. 3D CTA studies of the subjects with active internal hernias demonstrated remarkable differences when compared to control 3D CTA studies. The blood supply of herniated intestinal limbs in particular showed abnormal trajectories. Additionally, enteroenterostomy staple lines had migrated or altered orientation. CONCLUSION: 3D CTA is a promising technique for diagnosing active internal hernias. Our findings suggest that for diagnosing internal hernias, focus should probably shift from routine abdominal CT examination towards the 3D assessment of the mesenteric vasculature and surgical staples.