Deviation Analyses of Computer-Assisted, Template-Guided Mandibular Reconstruction With Combined Osteotomy and Reconstruction Pre-Shaped Plate Position Technology: A Comparative Study

BackgroundComputer-assisted and template-guided mandibular reconstruction provides higher accuracy and less variation than conventional freehand surgeries. The combined osteotomy and reconstruction pre-shaped plate position (CORPPP) technique is a reliable choice for mandibular reconstruction. This study aimed to evaluate the accuracy of CORPPP-guided fibular flap mandibular reconstruction and analyze the possible causes of the deviations.Patients and MethodsFrom June 2015 to December 2016, 28 patients underwent fibular flap mandibular reconstruction. Virtual planning and personalized CORPPP-guided templates were applied in 15 patients while 13 patients received conventional freehand surgeries. Deviations during mandibulectomy and fibular osteotomy, and overall and triaxial deviation of the corresponding mandibular anatomical landmarks were measured by superimposing the pre- and postoperative virtual models.ResultsThe deviation of the resection line and resection angle was 1.23 ± 0.98 mm and 4.11° ± 2.60°. The actual length of fibula segments was longer than the designed length in 7 cases (mean: 0.35 ± 0.32 mm) and shorter in 22 cases (mean: 1.53 ± 1.19 mm). In patients without ramus reconstruction, deviations of the ipsilateral condylar head point (Co.), gonion point (Go.), and coracoid process point (Cor.) were 6.71 ± 3.42 mm, 5.38 ± 1.71 mm, and 11.05 ± 3.24 mm in the freehand group and 1.73 ± 1.13 mm, 1.86 ± 0.96 mm, and 2.54 ± 0.50 mm in the CORPPP group, respectively, with significant statistical differences (p < 0.05). In patients with ramus reconstruction, deviations of ipsilateral Co. and Go. were 9.79 ± 4.74 mm vs. 3.57 ± 1.62 mm (p < 0.05), and 15.17 ± 6.53 mm vs. 4.36 ± 1.68 mm (p < 0.05) in the freehand group and CORPPP group, respectively.ConclusionMandibular reconstructions employing virtual planning and personalized CORPPP-guided templates show significantly higher predictability, convenience, and accuracy of mandibular reconstruction compared with conventional freehand surgeries. However, more clinical cases were required for further dimensional deviation analysis. The application and exploration of clinical practice would also continuously improve the design of templates.

MRI-based observation of the size and morphology of temporomandibular joint articular disc and condyle in young asymptomatic adults

Objective: To investigate the size and morphology of the temporomandibular joint (TMJ) articular disc and condyle in young asymptomatic adults by using magnetic resonance imaging (MRI) and to provide a reference for clinical diagnosis and scientific study of temporomandibular disorders (TMD). Methods: Overall, 93 undergraduate volunteers without TMD were enrolled from the freshmen pool at the Qingdao University. All participants underwent MRI of the oblique sagittal and oblique coronal TMJ planes. The articular disc and condyle were subsequently measured, and their morphology was evaluated. The obtained data were then grouped and analyzed statistically. Finally, intragroup correlation coefficient (ICC) was used to evaluate the interobserver measurement reliability. Results: We totally received 186 TMJ imaging samples. Based on our analysis, disc’s anterior band in young asymptomatic adult females were thicker than males of the same age (p = 0.024). Moreover, the media-lateral dimensions of the condylar head of adult females were shorter than males of equal age (P＜0.001). The bilateral articular disc morphology was the same in 72.4% of subjects while the condylar morphology was the same in 63.4% of participants. Finally, using measurement reliability assessment, we demonstrated that our conclusions are reliable (ICC ≥0.7). Conclusion: The thickness of the anterior band of the disc and the media-lateral dimensions of the condylar head were gender-related. Additionally, the morphology of the bilateral articular disc and condyle was different among the subset of young asymptomatic adults.

Minimal bone resorption after open treatment of mandibular condylar head fractures

Open treatment of condylar base and neck fractures is widely recommended, whereas treatment of condylar head fractures is still controversial and just is removal of osteosynthesis material. In this study, bone resorption and remodelling after open treatment of condylar head fractures were three-dimensionally (3D) assessed and correlated with clinical parameters in a medium follow-up. Of 18 patients with 25 condylar head fractures who underwent open reduction and internal fixation, clinical data and cone beam computed tomography (CBCT) datasets were analysed. Condylar processes were segmented in the postoperative and follow-up CBCT scans. Volumetric and linear changes were measured using a sophisticated 3D-algorithm. In the course after surgery, patients function and pain improved significantly. Low rates of postoperative complications were observed. All 3D measurements showed no significant bone resorption during the follow-up period. Open reduction of condylar head fractures leads to good patients outcomes and low rates of long-term complications. This study underlines the feasibility and importance of open treatment of condylar head fractures and may help to spread its acceptance as the preferred treatment option.

Unilateral Condylar Hyperplasia: Two Case Reports and a Literature Review

Condylar hyperplasia (CH) is a rare idiopathic condition affecting the mandibular condyle where the growth of the condylar head and/or neck continues beyond the normal growth period. This disorder presents clinically as facial asymmetry and occlusal discrepancy. Here, we present two cases of CH managed at our centers during the period between 2012 and 2017 with a successful outcome. We highlight the clinical presentation, investigation, and surgical management and give a brief literature review.

Selective β2-Adrenoceptor Blockade Rescues Mandibular Growth Retardation in Adolescent Rats Exposed to Chronic Intermittent Hypoxia

Activation of the sympathoadrenal system is associated with sleep apnea-related symptoms and metabolic dysfunction induced by chronic intermittent hypoxia (IH). IH can induce hormonal imbalances and growth retardation of the craniofacial bones. However, the relationship between IH and β2-adrenergic receptor signaling in the context of skeletal growth regulation is unclear. This study aimed to investigate the role of β2-adrenergic receptors in IH-induced mandibular growth retardation and bone metabolic alterations. Male 7-week-old Sprague–Dawley rats were subjected to IH for 3 weeks. IH conditions were established using original customized hypoxic chambers; IH was induced at a rate of 20 cycles per hour (oxygen levels changed from 4 to 21% in one cycle) for 8 h per day during the 12 h “lights on” period. The rats received intraperitoneal administration of a β2-adrenergic antagonist (butoxamine) or saline. To exclude dietary effects on general growth, the normoxic rats with saline, normoxic rats with butoxamine, and IH rats with butoxamine were subjected to food restriction to match the body weight gains between IH and other three groups. Body weight, heart rate, blood pressure, and plasma concentrations of leptin, serotonin, and growth hormone were measured. Bone growth and metabolism were evaluated using radiography, microcomputed tomography, and immunohistochemical staining. Plasma leptin levels were significantly increased, whereas that of serotonin and growth hormone were significantly decreased following IH exposure. Leptin levels recovered following butoxamine administration. Butoxamine rescued IH-induced mandibular growth retardation, with alterations in bone mineral density at the condylar head of the mandible. Immunohistochemical analysis revealed significantly lower expression levels of receptor activator of nuclear factor-kappa B ligand (RANKL) in the condylar head of IH-exposed rats. Conversely, recovery of RANKL expression was observed in IH-exposed rats administered with butoxamine. Collectively, our findings suggest that the activation of β2-adrenergic receptors and leptin signaling during growth may be involved in IH-induced skeletal growth retardation of the mandible, which may be mediated by concomitant changes in RANKL expression at the growing condyle.