The correction of asymmetry using computer planned distraction osteogenesis versus conventional planned extra-oral distraction osteogenesis: A randomized control clinical trial

Changes in mandibular position during midface distraction in patients with syndromic craniosynostosis

The purpose of this study was to evaluate changes in mandibular position during midface distraction. Midface distraction was performed in patients with syndromic craniosynostosis to increase upper airway volume. Although this treatment resulted in changes in occlusion, the concomitant changes in mandibular position were poorly understood. In this retrospective study, three-dimensional (3D) cephalograms were obtained before and after midface distraction in 15 patients with syndromic craniosynostosis. Perioperative polysomnography scores and changes in maxillary and mandibular position, mandibular volume, and upper airway volume were analyzed. Results showed a significant improvement in apnea-hypopnea index (AHI) (from 20.6 ± 21.3 to 6.9 ± 5.1, p < 0.05) and upper airway volume (from 2951.65 ± 2286.38 to 5218.04 ± 3150.05 mm3, p < 0.001). When the lowest point of the sella turcica was set as the reference point, the mandible moved significantly in an anterior direction (from 47.9 ± 11.5 to 51.9 ± 9.8 mm, p < 0.05). Mandibular volume did not change significantly perioperatively (from 32530.19 ± 10726.01 to 35590.50 ± 14879.21 mm3, p = 0.10). There were positive correlations between the rates of improvement in AHI and the amount of mandibular movement in the anterior and inferior directions (both p < 0.05). Within the limitations of the study, it seems that the mandible moved in the anterior-inferior direction after midface distraction, and the amount of movement correlated with improvement in respiratory function. Therefore, it is important to consider the position of the mandible when determining the direction of midface distraction, as it may influence the therapeutic effect.

Anatomical Analysis of Inferior Alveolar Nerve Relation to Mandibular Posterior Teeth Using Cone Beam Computed Tomography: A Retrospective Radiographic Analysis Study

Introduction

Cone beam computed tomography (CBCT) is reliable in the assessment of structures related to teeth. The assessment of the inferior alveolar neurovascular (IAN) bundle location using CBCT is considered one of its prime uses in different mandibular surgeries.

Methodology

Retrospective CBCT data of patients presented to the institute were assessed to measure relations of IAN. Measurements were taken to assess the bone thickness adjacent to IAN, the superior-inferior dimension between the canal and the teeth, and the dimension between the canal and the inferior border of the mandible.

Results

Out of the 170 patients the root apices nearest to the IAN were that of the second molars (1.76 ± 1.86 mm). The IAN was closest to the inferior border of the mandible at the roots of the second molars (8 ± 3.4 mm). The buccal bone thickness had its greater dimension buccal to the IAN at the area of the second molar (5.16 ± 1.26 mm).

Conclusion

Two mini-plates in trauma do not increase the risk of injury. It is advisable in apicectomy not to extend 1.5 mm apically. The thickness of the nerve-lateralization window should not exceed 2 mm. In body osteotomy procedure, perform surgery anterior to premolars as much as possible.

Condylar resorption post mandibular distraction osteogenesis in craniofacial microsomia: A retrospective study

The aim of this study was to investigate the characteristics of condylar resorption in craniofacial microsomia (CFM) patients following mandibular distraction osteogenesis (MDO). Patients with unilateral type-IIa and type-IIb CFM, who had completed MDO and mandibular distractor extraction (MDE), were recruited. The height and volume of the condyle were measured on three-dimension models created by the analysis of computed tomography (CT) data. Normality analysis was performed using the Shapiro-Wilk test. Data for the affected and unaffected sides were compared using the paired t-test or Wilcoxon signed-rank test. Data for both type-IIa and type-IIb CFM were compared using the independent-samples t-test or Mann-Whitney U test. The Pearson or Spearman correlation was used to determine the correlations of condylar resorption rate with related measurements. In total, 48 type-IIa and 48 type-IIb CFM patients were included. The condylar resorption rate in type-IIa CFM (0.35 ± 0.32) was significantly associated with the height of the condyle (r = 0.776, p < 0.001) and distraction distance (r = 0.447, p = 0.001), while the condylar resorption rate in type-IIb CFM (0.49 ± 0.46) was significantly associated with the height of the condyle (r = 0.924, p < 0.001). However, there was no significant difference in condylar resorption rate between type-IIa and type-IIb CFM (p = 0.075). In addition to occlusal changes, no other negative symptoms of the TMJ were observed with condylar resorption. Condylar resorption was evident in CFM patients following mandibular distraction osteogenesis, and the condylar resorption rate showed a relationship with distraction distance and condylar height.

Morphologic Variability of Bone and Soft Tissue in Microtia With Hemifacial Microsomia

Objective: Microtia patients with hemifacial microsomia (HFM) have a host of distinct anatomical disorder of skeletal and soft tissue asymmetries. The purpose of this study was to assess soft tissue discrepancies in microtia patients with HFM and their correlation with skeletal discrepancies. Methods: A total of 42 patients were enrolled and studied prospectively using a 3-dimensional superimposition and color mapping of the soft and hard tissues. Mirroring techniques created perfectly symmetric models for comparison. Differences between affected and normal sides were evaluated in 5 areas: retroauricular mastoid, malar, maxillary frontal, mandibular frontal, and gonion areas. Pearson correlations were used to assess the relationship between skeletal and soft tissue asymmetry. Results: Hard tissue asymmetry ranged from 0.79 mm (mandibular frontal) to 1.29 mm (malar), while soft tissue asymmetry ranged from 1.34 mm (maxillary frontal) to 5.26 mm (retroauricular mastoid). Correlations between skeletal and soft tissue asymmetry varied, with the strongest correlation observed at the retroauricular mastoid area and the weakest at the maxillary frontal area. Conclusion: There was a high correlation between bone and soft tissue hypoplasia at the retroauricular mastoid area, while the other evaluated areas showed poor correlation between skeletal and soft tissue asymmetries. Clinicians should assess each component separately for optimal treatment planning in microtia patients with HFM.

Augmented reality hologram combined with pre-bent distractor enhanced the accuracy of distraction vector transfer in maxillary distraction osteogenesis, a study based on 3D printed phantoms

BACKGROUND

Vector control is a significant concern in maxillary distraction osteogenesis (DO). Distraction vector planning on the patient's 3D-printed skull phantom is more intuitive for surgeons and cost-efficient than virtual surgical planning. However, the accuracy of transferring the planned vector to intraoperative (vector transfer) according to the shape of the pre-bent footplate alone is relatively limited. The application of augmented reality (AR) in surgical navigation has been studied for years. However, few studies have focused on its role in maxillary DO vector transfer. This study aimed to evaluate the accuracy of AR surgical navigation combined with the pre-bent distractor in vector transfer by comparing it with the pre-bent distractor alone.

METHODS

Ten patients with maxillary hypoplasia were enrolled with consent, and three identical 3D-printed skull phantoms were manufactured based on per patient's corresponding pre-operative CT data. Among these, one phantom was for pre-operative planning (n = 10), while and the other two were for the AR+Pre-bending group (n = 10) and the Pre-bending group (n = 10) for the experimental surgery, respectively. In the Pre-bending group, the distraction vector was solely determined by matching the shape of footplates and maxillary surface. In the AR+Pre-bending group, the distractors were first confirmed to have no deformation. Then AR surgical navigation was applied to check and adjust the vector in addition to the steps as in the Pre-bending Group.

RESULTS

For the angular deviation of the distraction vector, the AR+Pre-bending group was significantly smaller than the Pre-bending group in spatial (p < 0.001), x-y plane (p = 0.002), and y-z plane (p < 0.001), and there were no significant differences in the x-z plane (p = 0.221). The AR+Pre-bending group was more accurate in deviations of the Euclidean distance (p = 0.004) and the y-axis (p = 0.011). In addition, the AR+Pre-bending group was more accurate for the distraction result.

CONCLUSIONS

In this study based on 3D printed skull phantoms, the AR surgical navigation combined with the pre-bent distractor enhanced the accuracy of vector transfer in maxillary DO, compared with the pre-bending technique alone.

Preliminary study of the accuracy and safety of robot-assisted mandibular distraction osteogenesis with electromagnetic navigation in hemifacial microsomia using rabbit models

This study aimed to investigate the accuracy and safety of mandibular osteotomy and distraction device positioning in distraction osteogenesis assisted by an electromagnetic navigation surgical robot. Twelve New Zealand white rabbits were randomly divided into two groups after computed tomography. The control group underwent a procedure based on the preoperative three-dimensional design and clinical experience. Animals in experimental group underwent a procedure with robotic assistance after registration. The accuracies of osteotomy and distraction device positioning were analysed based on distance and angular errors. The change in ramus length after a 1 cm-extension of the distraction device was for assessing distraction effect. The preparation, operative and osteotomy times, intraoperative bleeding, and teeth injury were used for safety assessment. In the experimental group, the distance (t = 2.591, p = 0.011) and angular (t = 4.276, p = 0.002) errors of osteotomy plane, and the errors in distraction device position (t = 3.222, p = 0.009) and direction (t = 4.697, p = 0.001) were lower; the distraction effect was better (t = 4.096, p = 0.002). There was no significant difference in the osteotomy time and bleeding; however, the overall operative and preparation times were increased in the experimental group, with a reduced rate of teeth damage. Robot-assisted mandibular distraction osteogenesis with electromagnetic navigation in craniofacial microsomia is feasible, safe, significantly improves surgical precision.