Geometric morphometric analysis of malocclusion on lateral cephalograms in Malaysian population

Hard and soft tissue shape variation and changes in Class II division 1 malocclusion during orthodontic treatment: a geometric morphometric analysis

BACKGROUND

This study aims to determine the hard and soft tissue shape variation and its changes in Class II division 1 malocclusion before and after orthodontic treatment using Geometric Morphometric Analysis.

METHODS

This retrospective study included 141 pre-treatment and near-end treatment lateral cephalometric radiographs of Class II division 1 malocclusion patients aged 16-40 years with a skeletal II pattern (ANB > 4o). 32 landmarks in Cartesian coordinates were created and identified using MorphoJ software to establish a shape analysis.

RESULTS

The vertical dimensions (hypodivergent to hyperdivergent facial profiles) showed the largest variation in the general shape of hard and soft tissue, followed by the anteroposterior dimensions (mild to severe skeletal II patterns). Variations of lip shape (long to short), lip protuberance (everted to inverted), and nasolabial angle (obtuse to acute) were present. Orthodontic treatment affected the shape of the hard and soft tissue significantly (p < 0.0001). T2 showed significant uprighting of upper incisors (17.5o) and lower incisors (3.7o), improved NLA (8o), an increase in upper lip thickness (1.5 mm), and a reduction in lower lip thickness (0.7 mm) (p < 0.05).

CONCLUSION

Vertical and anteroposterior shape variations were found. Orthodontic treatment had an impact on both hard and soft tissue shapes. Hence, understanding both the hard and soft tissue shape variations and the orthodontic treatment changes is crucial for an accurate diagnosis and treatment plan to achieve a successful outcome and excellent patient satisfaction.

Geometric morphometric analysis of mandibular symphysis in Class III skeletal base

This study aimed to investigate the general mandibular symphysis (MS) shape variation among Class III skeletal base, using geometric morphometric analysis. Pre-treatment lateral cephalometric radiographs of 254 patients aged 11-40 years old, with Class III skeletal base (ANB <1°) and lower incisor angle (<99°) were included. Nine-landmarks with x and y coordinates were identified on MS using TPSDig2 software, then exported into Morpho J for shape and statistical analysis. Principal component analysis showed that three main shape dimensions with a total variance of 74.6% represented the majority variation of samples. Procrustes Anova showed the shape of MS in Class III skeletal base to be mainly influenced by gonial angle, incisor inclination and sex (P<0.0001). Canonical variate analysis showed that high gonial angle groups had significantly narrower and elongated MS whereas low gonial angle groups had wider, bulbous and rounded MS (P<0.0001). The ratio of alveolar part to basal part was 1:5 in low gonial angle and 2:3 in high gonial angle. Males had significantly taller MS with narrower B point area compared to females (P<0.0001). Retroclined incisors exhibited taller and retroclined alveolar parts (P<0.0001). The shape of MS in Class III skeletal base varied at the alveolar part, basal part or both and it is influenced by gonial angle, incisor inclination and sex. Hence, understanding the shape variation of MS is important to aid orthodontic treatment planning.

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.

A geometric morphometric evaluation of facial hard tissue patterns

OBJECTIVE:

The purpose of this study was to investigate the size and shape variations of hard tissue patterns in different skeletal relations in Malaysian Malay subjects using the two-dimensional geometric morphometrics method.

MATERIALS AND METHODS:

A total of 188 lateral cephalograms of adult Malay subjects (aged between 18 and 40 years) with Class I, II, and III skeletal relations were collected. Ten two-dimensional hard tissue landmarks were applied on lateral cephalograms which underwent landmark application and shape analyses as Procrustes ANOVA analysis, principal component analysis, canonical variate analysis, and discriminant function analysis. Statistical analyses were performed to find the mean and variance of each landmark using one-way ANOVA. The raw data from shape analysis were used to calculate the link between landmarks.

RESULTS:

Skeletal relations showed 16 Principal Components which indicated that variances existed in 16 different dimensions. In Procrustes ANOVA, the Centroid size was significantly different in genders and skeletal relations (P < 0.01). Canonical variate analysis showed the highest Mahalanobis distances and Procrustes distances between Class II and III among skeletal relations and between gender groups (P < 0.0001). Discriminant function analysis showed the classification was mostly accurate, especially for Class II and Class III with success rates of 90.6% and 83.3%, respectively, after cross-validation. The statistical analysis showed significant differences (P < 0.05) in hard tissue landmarks.

CONCLUSION:

There were different ANB angles in different skeletal relations. The GMM could be used as an alternative tool for diagnosis and treatment planning for craniofacial shape evaluations for future orthodontists and maxillofacial surgeons.

Geometric analysis of the urethral-vaginal interface curvature in women with and without stress urinary incontinence: A pilot magnetic resonance imaging study

AIMS

To evaluate differences in the curvature of the urethral-vaginal interface in women with and without stress urinary incontinence (SUI) using geometric morphometric analysis techniques.

METHODS

We conducted a pilot case-control study using magnetic resonance imaging (MRI) scans of 18 women with and without SUI. The urethral-vaginal interface at the level of the mid-urethra was fitted with a second-order polynomial regression. The chord length and chord-to-vertex length of the resulting parabolic curve were used to calculate the arc length and radius of a circular arc fitted to the interface curvature. Demographic characteristics and Pelvic Organ Prolapse Quantification (POP-Q) parameters were collected. Subjects were stratified by those with and without SUI, as well as by those with and without anterior wall prolapse beyond 2 cm proximal to the hymen (Aa > -2 cm).

RESULTS

The radius of the urethral-vaginal interface curvature was not found to be different between subjects with and without SUI (8.8 vs. 9.2 mm, p = 0.53); however, this value was smaller in subjects with Aa > -2 (8.4 vs. 11.9 mm, p = 0.03). The chord length, chord-to-vertex length, and arc length comprising the urethral-vaginal interface curvature were similar between subjects with and without SUI, and between subjects with and without Aa > -2 cm (p > 0.05 for all).

CONCLUSIONS

In this pilot study population, the radius of the urethral-vaginal interface curvature at the mid-urethra was smaller among women with anterior vaginal wall prolapse beyond 2 cm proximal to the hymen. A difference in the urethral-vaginal interface curvature among women with and without SUI was not found.