3D Analysis of Facial Morphology of a Colombian Population Compared to Adult Caucasians

A Preliminary Study of a Novel Reference Plane of the Head: Comparing With the True Horizontal Plane

A new reference plane of the head, based on soft tissue landmarks and suitable for clinical analysis and soft tissue measurements, is needed. We recently discovered a novel reference plane, that is, the COs plane, which was formed by bilateral Lateral Canthus and bilateral Otobasion Superius and might be horizontal at the natural head position (NHP). In this study, we investigated the angles between the COs plane and the true horizontal (TrH) plane while sitting and standing, aiming to explore whether the new plane could be used as a substitution for the reference plane in clinical practice. Briefly, 26 volunteers were enrolled. Their sitting and standing NHP were recorded using the 3dMDface system. In the pitch axis, the mean angle of COs/TrH was 0.29 degrees and 0.41 degrees for sitting and standing positions, respectively, showing no statistical difference ( P >0.05). However, in the roll axis, the mean angle of COs/TrH for sitting position and standing positions was 1.08 and 1.33 degrees ( P <0.05), which was considered to be the result of habitual canting of the head. Moreover, there were no significant differences between the sitting and standing NHP, considering the COs/TrH angles ( P >0.05). To sum up, we concluded that the COs plane could be used as a reliable reference plane in certain soft tissue analysis and clinical applications.

Cranial reconstruction evaluation - comparison of European statistical shape model performance on Chinese dataset

Purpose

Morphological variability of the skull is an important consideration for cranioplasty and implant design. Differences in morphology of the skull based on the ethnicity are known. In a previous study we could show the accuracy and benefits of virtual reconstructions based on a statistical shape model (SSM) for neurocranial defects. As the SSM is trained on European data, the question arises how well this model fares when dealing with patients with a different ethnic background. In this study we aim to evaluate the accuracy and applicability of our proposed method when deploying a cranial SSM generated from European data to estimate missing parts of the neurocranium in a Chinese population.

Methods

We used the same data and methods as in our previous study and compared the outcomes when applied to Chinese individuals. A large unilateral defect on the right side and a bilateral defect were created. The outer surface of the cranial table was reconstructed from CT scans, meshed with triangular elements, and registered to a template. Principal component analysis together with Thin Plate Spines (TPS) deformation was applied to quantify modes of variation. The mesh to mesh distances between the original defects´ surfaces and the reconstructed surface were computed.

Results

Comparing the Chinese test group with the European control group, regarding the entire defect the analysis shows no significant difference for unilateral defects (test vs. control group/0.46 mm ± vs. 0.44 mm). Reconstruction of bilateral defects exhibited only in slightly higher prediction errors than those of unilateral defects (0.49 mm ± vs. 0.45 mm).

Conclusion

The proposed method shows a high accuracy that seems to be ethnical independent - with low error margins for virtual skull reconstruction and implant design.

Clinical relevance: Metallic objects may severely impact image quality in several CBCT devices.

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Statistical shape modelling enables automatic skull reconstruction for computer assisted surgery

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Despite a Caucasian database, the statistical shape model can provide accurate results for other ethnic groups.

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The results facilitate the development of reconstruction algorithms, as the data basis can be kept smaller

Dental Arch Changes with Two Different Trans-Palatal Arch

Background:

Rapid maxillary expansion (RME) is a dentofacial orthopedic treatment often used to treat patients with narrow palate and transverse maxillary growth deficiency.

Introduction:

This treatment leads to correction of posterior dental crossbites, coordination of the upper and lower arches and gaining arch perimeter in patients with tooth size/arch size discrepancies. To stabilize the results obtained with RME and to limit or avoid the relapse, the use of Transpalatal Arch (TPA) would be recommended.

Objectives:

The aim of this study is to evaluate short-term maxillary changes in patients treated with RME followed by TPA with and without palatal arms.

Materials and Methods:

30 patients, 16 females and 14 males (mean age of 9.7 yrs ranging between 9 and 12), were treated by expansion with palatal Hyrax-type expander. After this period, it was removed and one of the two different types of TPA was used.

The two different TPA were a 0.036-inch stainless steel wire with a loop directed mesially in the middle, one maintained the original design (TPA), the second one presented arms extended to canines (TPAa). Dental casts were collected for each patient for each treatment step; before (T0), after expansion (T1) and after TPA or TPAa (T2). To assess differences in dental arches after the two treatment phases, three-dimensional (3D) dental casts were used to make more predictable measurements compared with caliper measurements that presented intra-examiner and inter-examiner measurements errors.

Results:

In TPAa group, differences between the value at the end of the retention period and at the end of expansion showed no statistical significance. Instead in TPA group, the same measurements suggested a reduction of value in almost all dental transverse diameters. Statistically significant differences in dental measurements were found between TPAa and TPA.

Conclusion:

Results confirm the hypothesis that TPAa can allow to better maintain dental transverse dimensions.

Soft-Tissue Analysis of Different Sagittal Skeletal Patterns Using the Geometric Morphometric Method

OBJECTIVES

 This study aimed to investigate the size and shape variations of soft-tissue patterns in different sagittal skeletal patterns using the geometric morphometrics method (GMM) obtained from lateral cephalograms.

MATERIALS AND METHODS

 This is a retrospective study, where the sample comprised of 188 Malaysian Malay subjects aged between 18 and 40 years and with different sagittal skeletal patterns. Overall, 71 males and 117 females were gathered for all size and shape analyses. This study incorporated 11 soft-tissue landmarks, which underwent landmark application using tpsDig2 software version 2.31, while the shape analysis was done using MorphoJ software version 1.07a.

STATISTICAL ANALYSIS

 Statistical analyses were performed using IBM SPSS Statistics 26. The result of the analysis of variance (ANOVA) test showed significant differences in some of the parameters between the landmarks. Length D, Length E, Length F, Length H, and Length I showed significant differences (p < 0.05), while other parameters showed no difference (p > 0.05).

RESULTS

 The shape variation of soft-tissue landmarks in different skeletal patterns existed in 18 different dimensions which showed by 18 principal components (PCs). Procrustes ANOVA and canonical variate analysis showed the size and shape differences of soft-tissue patterns between Class II and III and gender groups (p < 0.0001). In discriminant function analysis for Class II subjects, the classification accuracy was 98.4%, whereas subsequent to cross-validation, the classification accuracy was 90.6%. For Class III subjects, the classification accuracy was 96.6%, while after cross-validation, the classification accuracy was 90%.

CONCLUSION

 Different sagittal skeletal patterns demonstrated different soft-tissue shape variations. Class III showed the most protrusive upper and lower lips, while Class II demonstrated the most retrusive lower lip.

Mandibular Coronoid Process Hypertrophy: Diagnosis and 20-Year Follow-Up with CBCT, MRI and EMG Evaluations

Coronoid process hypertrophy (CPH) consists of an abnormal volumetric increment of the mandibular coronoid process; as this process grows gradually, the infratemporal space needed for the rotation and translation of the mandible is reduced, which results in a reduction of the range of mouth opening and lateral excursion, limiting mouth opening. The purpose of this case report was to describe a rare case of hypertrophy of coronoid processes with associated temporomandibular ankylosis, monitored for over 20 years. The patient was first visited when he had a facial trauma at the age of 4. Then he was followed through clinical, functional, instrumental, bi-dimensional and three-dimensional radiological evaluations up to the age of 24. Physical therapy was initiated at the age of 10 to improve the condition of the masticatory muscles, while at the age of 14, Transcutaneous Electrical Nerve Stimulations were performed to reduce muscle tension and, a bite plane was delivered to control the parafunctional activity of the jaw in the night and self-control instruction was provided for daytime habits. The adult patient has not accepted surgical intervention; thus, the future objective is to continue monitoring over the years to avoid a detrimental progression of the medical condition through physical and functional therapies while waiting for patient consent to surgery if needed.