Asymmetry index for the photogrammetric assessment of facial asymmetry

The accuracy of three-dimensional facial scan obtained from three different 3d scanners

This study aimed to compare the accuracy (trueness and precision) and reproducibility of three 3D facial scanning systems: a laser scanner (Planmeca Proface), a dual-structured light scanner (EinScan H2), and a smartphone application (EM3D Scanner). Thirty subjects with skeletal deformities scheduled for orthognathic surgery were scanned using these systems, and the resulting 90 3D facial scans were compared with facial surfaces segmented from CBCT scans. Surface discrepancies were measured using root mean square (RMS) values across five facial aesthetic areas (cheeks, nasal, perioral, and mental units) through Geomagic Control X software. The EM3D Scanner showed significantly better trueness and precision compared to the EinScan H2, particularly for the overall face (p < 0.01). Planmeca Proface showed no significant difference from the other scanners in terms of error. The nasal and perioral regions, scanned with Planmeca Proface, achieved the highest accuracy compared to other areas, while the left cheek demonstrated the lowest accuracy. Up to 80% of the scanned areas were classified as reproducible, falling within acceptable tolerance limits. Overall, trueness values ranged from 0.70 to 0.85 mm, and precision ranged from 0.68 to 0.81 mm, with deviations of less than 1.0 mm deemed highly acceptable for clinical applications. Surface regions closer to the midline were found to have higher accuracy than those on the sides of the face. These findings highlight the potential of EM3D Scanner and Planmeca Proface for accurate and reliable facial scanning, particularly in clinical settings where minimal deviation is crucial.

Digitally Designed Decompression Device for Treatment of Odontogenic Cysts: Technical Note

The aim of the work is to describe the technical procedures adopted to realize a custom-made clinical device, designed through a digital workflow, to improve the decompression of odontogenic cysts. After an incisional biopsy to confirm the histologic nature of the osteolytic jaw lesion, a digital impression of the dental arches, obtained by intraoral scanner, and a CBCT of the jaws, were acquired. The STL (Standard tessellation language) and DICOM files were matched and the decompression device was designed by the use of CAD software (Exocad, 3.1). The 3D-printed resin replica was obtained and cast with a surgical alloy. The delivered device proved to be safe and effective in decompressing the osteolytic lesions.

The Role of Hyaluronic Acid in Alveolar Ridge Preservation: A Systematic Review of Its Biological and Regenerative Potential According to PRISMA Guidelines and the Cochrane Handbook

Objectives: This systematic review evaluates the biological activity and regenerative potential of hyaluronic acid (HA) in alveolar ridge preservation (ARP) following tooth extraction, assessing its efficacy in reducing bone resorption and promoting bone regeneration when combined with xenografts. Methods: A comprehensive search was conducted across PubMed, Scopus, Web of Science, and Lilacs databases, adhering to PRISMA guidelines. Studies from 2012 to December 2024 involving human participants were included based on a PECO framework. Four studies met the inclusion criteria, with data extracted and analyzed for clinical and histological outcomes. The risk of bias was assessed using the ROBINS-E tool. Results: The included studies demonstrated that HA combined with xenografts significantly reduced post-extraction bone resorption compared to controls. HA-enhanced grafts showed superior radiographic and histological outcomes, including increased bone density and reduced graft shrinkage. While one randomized controlled trial found no significant differences in wound healing or patient-reported outcomes between HA and control groups, other studies reported improved bone formation and graft stability with HA. Variability in study design and sample size was noted, with a generally moderate to high risk of bias in some studies. Conclusions: The evidence supports the beneficial role of HA as an adjuvant in ARP procedures, enhancing bone regeneration and limiting resorption. However, further research with larger samples and standardized methodologies is required to confirm these findings and optimize clinical protocols.

Soft tissue changes during orthopedic therapy: An in vivo 3-dimensional facial scan study

INTRODUCTION

The aim was to compare the soft tissue changes in pretreatment and posttreatment facial scans of patients who had undergone various orthopedic treatments vs a control group of untreated growing patients.

METHODS

Facial scans were performed before (T0) and after (T1) orthopedic treatment in 15 patients prescribed rapid palatal expander (RPE), 15 cervical headgear (HG), and 15 facemasks (FM), as well as 6 months apart in 15 untreated growing patients. After best-fit scan alignment using Geometric Control X software (3D Systems Inc, Rock Hill, SC), a 3-dimensional (3D) analysis of soft tissue changes was performed, comparing 3D reference points (total 22) and 8 areas on T0 and T1 scans. Kruskal-Wallis nonparametric tests and pairwise comparison with Bonferroni's correction were applied to identify any statistically significant differences among groups (P <0.05). All analyses were conducted with SPSS software (version 28; IBM, Armonk, NY).

RESULTS

At T1, reduced soft tissue projection was found at the nose and upper lip in the HG group, the lower lip in the HG and RPE groups, and the chin in the FM and RPE groups. The RPE group displayed a statistically significant increase in facial divergence, confirmed by gnathion position (RPE vs FM [P = 0.018] and RPE vs control [P = 0.046]), as well as an increase in the soft tissue projection of both cheeks (left cheek in range of 1-2 mm [P = 0.030] and range of 0 to -1 mm [P = 0.022]; right cheek in range of 1-2 mm [P = 0.003] and range -1 to -2 mm [P = 0.001]). There were no clinically significant differences among groups in mandibular right and left body areas.

CONCLUSIONS

The 3D facial analysis revealed significant differences in soft tissues among orthopedic treatments, especially at the upper and lower lip and chin areas, as compared with untreated patients.

Comparison of Mirroring and Overlapping Analysis and Three-Dimensional Soft Tissue Spatial Angle Wireframe Template in Evaluating Facial Asymmetry

AIM

The purpose of this study was to evaluate the accuracy and efficacy of a new wireframe template methodology in analyzing three-dimensional facial soft tissue asymmetry.

MATERIALS AND METHODS

Three-dimensional facial soft tissue data were obtained for 24 patients. The wireframe template was established by identifying 34 facial landmarks and then forming a template on the face with the MeshLab 2020 software. The angle asymmetry index was automatically scored using the template. The mirroring and overlapping technique is accepted as the golden standard method to diagnose facial asymmetry by acquiring deviation values of one's face. Consistency rates between the two methodologies were determined through a statistical comparison of the angle asymmetry index and deviation values.

RESULTS

Overall consistency rates in the labial, mandibular angle, cheek, chin, and articular regions were 87.5%, 95.8%, 87.5%, 91.7%, and 100%, respectively. Regions with consistency rates in three dimensions of more than 85% are the x-axis and the z-axis of all regions and the y-axis of the mandibular angle, chin, and articular region.

CONCLUSIONS

Soft tissue facial asymmetry can be diagnosed accurately and effectively by using a three-dimensional soft tissue spatial angle wireframe template. Precise localization of asymmetry can be offered, and indiscernible tiny asymmetry can be identified.

Analyzing Discrepancies and Correlations in Soft and Hard Tissue Asymmetry: A Focused Study on Hemifacial Microsomia and Isolated Microtia

BACKGROUND

This study aims to thoroughly investigate the distinctions and relationships between facial hard and soft tissue asymmetry, as well as their variations within different conditions and age groups.

METHODS

This cross-sectional study analyzed pre-treatment computed tomography (CT) images from 120 male patients aged 5 to 12 years with unilateral HFM (Pruzansky-Kaban types I and IIA) or isolated microtia. The 120 patients were categorized into four groups by condition (HFM or isolated microtia) and age (5-7, 8-12 years). Segmentation and extraction of anatomical landmarks were performed using Mimics software, followed by generating root-mean-square (RMS) values for facial asymmetry. Statistical analysis, including the Wilcoxon signed-rank test and Spearman correlation coefficient, was conducted to assess differences and correlations in asymmetry.

RESULTS

The study found that soft tissue asymmetry was generally greater than hard tissue asymmetry across all facial regions. The complexity of regional asymmetry correlations increased with age in HFM patients but decreased in isolated microtia patients. Significant correlations between hard and soft tissues were observed within the same anatomical regions, particularly in HFM patients aged 8-12 years.

CONCLUSION

The intricate interplay between hard and soft tissues was observed in HFM and isolated microtia patients. Personalized analysis of the causes of asymmetry in different regions is crucial for the formulation of effective treatment plans.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Unraveling the Complexities of Sleep Disturbances: A Scientific Perspective

How to cite this article: Uzunçıbuk H, Fiorillo L, Ronsivalle V, et al. Unraveling the Complexities of Sleep Disturbances: A Scientific Perspective. J Contemp Dent Pract 2024;25(12):1081-1083. Keywords: Circadian rhythm disorders, İnsomnia, Obstructive sleep apnea, Sleep disturbances.

Impact of Obstructive Sleep Apnea on Masticatory Muscle Function

How to cite this article: Russo D, Almeida LE, Ronsivalle V, et al. Impact of Obstructive Sleep Apnea on Masticatory Muscle Function. J Contemp Dent Pract 2024;25(11):997-1000. Keywords: Apnea-hypopnea index, Diabetes, Obstructive sleep apnea, Temporomandibular joint.

Assessing Artificial Intelligence in Oral Cancer Diagnosis: A Systematic Review

BACKGROUND

With the use of machine learning algorithms, artificial intelligence (AI) has become a viable diagnostic and treatment tool for oral cancer. AI can assess a variety of information, including histopathology slides and intraoral pictures.

AIM

The purpose of this systematic review is to evaluate the efficacy and accuracy of AI technology in the detection and diagnosis of oral cancer between 2020 and 2024.

METHODOLOGY

With an emphasis on AI applications in oral cancer diagnostics, a thorough search approach was used to find pertinent publications published between 2020 and 2024. Using particular keywords associated with AI, oral cancer, and diagnostic imaging, databases such as PubMed, Scopus, and Web of Science were searched. Among the selection criteria were actual English-language research papers that assessed the effectiveness of AI models in diagnosing oral cancer. Three impartial reviewers extracted data, evaluated quality, and compiled the findings using a narrative synthesis technique.

RESULTS

Twelve papers that demonstrated a range of AI applications in the diagnosis of oral cancer satisfied the inclusion criteria. This study showed encouraging results in lesion identification and prognostic prediction using machine learning and deep learning algorithms to evaluate oral pictures and histopathology slides. The results demonstrated how AI-driven technologies might enhance diagnostic precision and enable early intervention in cases of oral cancer.

CONCLUSION

Unprecedented prospects to transform oral cancer diagnosis and detection are provided by artificial intelligence. More resilient AI systems in oral oncology can be achieved by joint research and innovation efforts, even in the face of constraints like data set variability and regulatory concerns.

Stem Cells: Present Understanding and Prospects for Regenerative Dentistry

Regenerative medicine in dentistry focuses on repairing damaged oral tissues using advanced tools like stem cells, biomaterials, and tissue engineering (TE). Mesenchymal stem cells (MSCs) from dental sources, such as dental pulp and periodontal ligament, show significant potential for tissue regeneration due to their proliferative and differentiative abilities. This systematic review, following PRISMA guidelines, evaluated fifteen studies and identified effective strategies for improving dental, periodontal, and bone tissue regeneration through scaffolds, secretomes, and bioengineering methods. Key advancements include the use of dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs) to boost cell viability and manage inflammation. Additionally, pharmacological agents like matrine and surface modifications on biomaterials improve stem cell adhesion and promote osteogenic differentiation. By integrating these approaches, regenerative medicine and TE can optimize dental therapies and enhance patient outcomes. This review highlights the potential and challenges in this field, providing a critical assessment of current research and future directions.

Photogrammetry is a useful tool to assess the aesthetic outcome after excision and reconstruction of the nose skin tumors

BACKGROUNDOBJECTIVE

Post-oncological nasal reconstruction presents both aesthetic and functional challenges. While established methods exist for quantitatively evaluating functional results following surgery, equivalent systems for assessing aesthetic outcomes are lacking. Three-dimensional (3D) photogrammetry, already used in maxillofacial and orthodontic surgery for aesthetic evaluation, overcomes some limitations of traditional methods like direct anthropometry. However, its applicability in oncological facial reconstruction has not yet been explored. In our study, we applied the 3dMDtrio™ system for the quantitative analysis of line and surface modifications following nasal reconstruction.

METHODS

We conducted a prospective observational study enrolling patients with skin neoplasms located on the nose undergoing surgical excision and reconstruction. Using the 3dMDtrio™ system, we measured the dimensions and projections of nasal surfaces and the positions of specific landmarks before and after surgery. The surface measurements were then correlated with aesthetic evaluations performed by three plastic surgeons, not involved in the procedure, using a 5-point Likert scale.

RESULTS

We included 33 patients with a mean age of 71 years, ranging from 40 to 94. We obtained complete documentation of all postoperative measurements for 21 patients. We observed significant changes in the positions of the landmarks post-surgery, limited to the right ala and nasion. The average nasal surface area was 4674.41 mm2 ± 477.24 mm2 before surgery and 4667.95 mm2 ± 474.12 mm2 after surgery, with no significant discrepancies. The evaluation using the Likert scale revealed an average score of 3.04 ± 0.48, with a significant negative correlation to the measured surface changes.

CONCLUSION

Our findings suggest that 3D photogrammetry can be considered a valid method for objectively assessing volumetric changes associated with post-oncological nasal reconstructive surgery.

Navigating the Interconnected World of Tooth Wear, Bruxism, and Temporomandibular Disorders

How to cite this article: Ronsivalle V, Russo D, Cicciù M, et al. Navigating the Interconnected World of Tooth Wear, Bruxism, and Temporomandibular Disorders. J Contemp Dent Pract 2024;25(10): 911-913. Keywords: Bruxism, Sleep disorders, Temporomandibular disorders, Tooth wear.

From Filters to Scalpels-Understanding Perceptions of Facial Asymmetry: An AAFPRS Survey

Facial asymmetries can significantly affect patient satisfaction post-surgery. Social media can impact a patient's perception of their asymmetries. To gather insights into the practices, perceptions, and approaches concerning facial asymmetry among facial plastic surgeons. The aim of this study was to understand the impact of social media on perceptions of facial asymmetry. This is an American Academy of Facial Plastic and Reconstructive Surgeons (AAFPRS) survey consisting of 46 questions that sought to understand facial plastic surgeons' perceptions of facial asymmetry, their consultation process, their patients' perspectives on their own facial asymmetries, and patient satisfaction. The survey was distributed to 1,269 members of AAFPRS across community hospitals, private practices, and academic hospitals. Sixty-seven members completed the survey. The survey revealed that 31% (21) of surgeons face challenges in managing patient expectations regarding facial asymmetry. In addition, 12% (8) of surgeons felt that patients did not initially recognize their own asymmetries. Eighty-seven percent (58) of surgeons emphasize the natural occurrence of asymmetry during consultations to set realistic expectations. This study emphasizes the need for thorough patient education during initial consultations to align expectations with achievable outcomes. Surgeons should explain the natural occurrence of asymmetry clearly and use digital imaging to show patients realistic previews of surgical results.

Evaluation of lavender and rose aromatherapies on the success of inferior alveolar nerve block in symptomatic irreversible pulpitis: A randomized clinical trial

Trial design

This is a prospective, block-randomized, blinded, multiple arm and parallel-group superiority clinical trial.

Methods

Seventy-eight patients satisfying the recruitment standards, were randomly allocated into three groups as follows: Group I (n = 26) - Inferior alveolar nerve block (IANB) devoid of aromatherapy (AT); Group II (n = 26) - IANB with lavender AT and Group III - IANB with rose AT (n = 26) with the help of the ultrasonic aroma diffuser (with respective oils)for 20 min/2 h in operatories 1,2 and 3 respectively. For AT, 3-4 drops of lavender and rose-conditioned oils were added from a 100 ml solution containing 100 mg of these medicinal plants. The pre-operative (PRO) and access opening (AO) pain as well as the anxiety of patients were recorded using the Visual Analog Scale (VAS) and Modified Dental Anxiety Scale (MDAS) respectively. Data thus obtained was entered into the Excel sheet and subjected to statistical tests (analysis of variance and paired t-test). The p-value less than 0.05 was considered statistically significant.

Results

Group I showed non-significant disparity between PRO and AO for both VAS as well as MDAS (p = 0.62, p = 0.71). However, group II (p = 0.04, p = 0.02) and group III (p = 0.03, p = 0.01) revealed significant differences between PO - AO VAS and MDAS. MDAS and VAS intergroup comparison revealed a significant difference among groups I and II (p = 0.03, p = 0.04), and groups I and III (p = 0.02, p = 0.03). However non-significant disparity was observed among groups II and III (p = 0.85, 0.34). Moreover, there was a statistically significant reduction in anxiety levels in females compared to males after rose AT (p = 0.02). Nevertheless, groups I and II did not show any gender predilection for anxiety as well as pain.

Conclusion

Alleviation of dental anxiety as well as reduction in pain during AO of teeth with SIP can be achieved using Lavender and rose AT. In female patients, rose AT can be preferred over lavender AT.

Does facial asymmetry vary between subjects of different age groups? A 3D stereophotogrammetry analysis

This study was aimed to assess whether facial asymmetry increases with age and to examine potential gender differences using 3D stereophotogrammetry. A prospective cross-sectional study was performed. 3D photographs were acquired from 600 control subjects, 300 male, 300 female, and were stratified into 15 different age groups ranging from 0 to 70+. The 3D photographs were postprocessed and mirrored. The original and mirrored faces were surface-based matched using an iterative closest point algorithm. The primary outcome variable, facial asymmetry, was evaluated by calculating the absolute mean distance between the original and mirrored images. The primary predictor was age. Pearson's correlation was used to assess the correlation between facial asymmetry and age. The average overall facial asymmetry was 0.72 mm (SD 0.72 mm; range 0.25 - 3.04 mm). Mean facial asymmetry increased significantly with age, from 0.45 mm in the age group of 0-4 years to 0.98 mm in the age group of 70+ (p<0.001). Facial asymmetry was positively correlated with age (Pearson's r = 0.55; p<0.001). Male subjects were significantly more asymmetric compared to females, 0.77 mm and 0.67 mm, respectively (p<0.001). This study indicates that facial asymmetry significantly increases with age and is significantly larger in males than in females.

Therapeutic Strategies and Genetic Implications for Periodontal Disease Management: A Systematic Review

The objective of this review is to identify the microbiological alterations caused by various therapy modalities by critically analyzing the current findings. We limited our search to English-language papers published between 1 January 2004 and 7 May 2024 in PubMed, Scopus, and Web of Science that were relevant to our topic. In the search approach, the Boolean keywords "microbio*" AND "periodontitis" were used. A total of 5152 papers were obtained from the databases Web of Science (2205), PubMed (1793), and Scopus (1154). This resulted in 3266 articles after eliminating duplicates (1886), and 1411 entries were eliminated after their titles and abstracts were examined. The qualitative analysis of the 22 final articles is included in this study. Research on periodontal disease shows that periodontitis alters the oral microbiome and increases antibiotic resistance. Treatments like scaling and root planing (SRP), especially when combined with minocycline, improve clinical outcomes by reducing harmful bacteria. Comprehensive mechanical debridement with antibiotics, probiotics, EMD with bone grafts, and other adjunctive therapies enhances periodontal health. Personalized treatment strategies and advanced microbial analyses are crucial for effective periodontal management and antibiotic resistance control.

Difference in the Intestinal Microbiota between Breastfeed Infants and Infants Fed with Artificial Milk: A Systematic Review

The gut microbiota (GM) plays a crucial role in human health, particularly during the first years of life. Differences in GM between breastfed and formula (F)-fed infants may influence long-term health outcomes. This systematic review aims to compare the gut microbiota of breastfed infants with that of F-fed infants and to evaluate the clinical implications of these differences. We searched databases on Scopus, Web of Science, and Pubmed with the following keywords: "gut microbiota", "gut microbiome", and "neonatal milk". The inclusion criteria were articles relating to the analysis of the intestinal microbiome of newborns in relation to the type of nutrition, clinical studies or case series, excluding reviews, meta-analyses, animal models, and in vitro studies. The screening phase ended with the selection of 13 publications for this work. Breastfed infants showed higher levels of beneficial bacteria such as Bifidobacterium and Lactobacillus, while F-fed infants had a higher prevalence of potentially pathogenic bacteria, including Clostridium difficile and Enterobacteriaceae. Infant feeding type influences the composition of oral GM significantly. Breastfeeding promotes a healthier and more diverse microbial ecosystem, which may offer protective health benefits. Future research should explore strategies to improve the GM of F-fed infants and understand the long-term health implications.

3D facial mask for facial asymmetry diagnosis

Objectives

Facial asymmetry is a common problem seen in orthodontic clinics that may affect patient esthetics. In some instances, severe asymmetry that affects patient esthetics may cause psychological issues. An objective method is therefore required to help orthodontists identify asymmetry issues.

Materials and methods

We used three-dimensional (3D) facial images and landmark-based anthropometric analysis to construct a 3D facial mask to evaluate asymmetry. The landmark coordinates were transformed using a symmetric 3D face model to evaluate the efficacy of this method. Patients with facial asymmetry were recruited to conduct mirror and overlap analysis to form color maps, which were used to verify the utility of the novel soft tissue landmark-based method.

Results

The preliminary results demonstrated that the asymmetry evaluation method had a similar response rate compared to diagnosis using mirror and overlap 3D images, and could therefore identify 3D asymmetry problems.

Conclusions

By using 3D facial scans and 3D anthropometric analysis, we developed a preliminary evaluation method that provides objective parameters to clinically evaluate patient facial asymmetry and aid in the diagnosis of asymmetric areas.

Clinical relevance

This study presents a novel facial asymmetry diagnostic method that has the potential to aid clinical decisions during problem identification, treatment planning, and efficacy evaluation.

Customized Facial Orthopedics: Proof of Concept for Generating 3D-Printed Extra-Oral Appliance for Early Intervention in Class III Malocclusion

Background: The present case report serves as a proof of concept for the fabrication and effective clinical administration of a 3D-printed chin cup tailored to the patient’s anatomical characteristics. Methods: An 11-year-old male with a Class III malocclusion was treated using a chin cup appliance to intercept and control a Class III mandibular skeletal growing pattern early. Two tailored chin cup devices were designed using 3D face scanning and CBCT scanning and were produced with additive manufacturing techniques. The chin pads were digitally designed based on a 3D scan of the patient’s face. The 3D modeling of chin cup components was performed using 3Shape Appliance Designer and 3D printed with biocompatible resin. An analogic chin pad was also produced for the same patient. The treatment plan involved the patient wearing the chin cup for 13 h per day. The patient was instructed to use all three chin pads produced at intervals of 4 months. The patient’s experience was assessed by reporting the comfort experience via a VAS scale. The treatment strategy was effective in improving the skeletal Class III malocclusion. Additionally, the integration of 3D face scanning (or CBCT scanning), modeling, and printing enables the production of customized chin cups with superior fit and comfort, contributing to enhanced patient compliance and treatment efficacy.

Accuracy of 3D facial scans: a comparison of three different scanning system in an in vivo study

BACKGROUND

The aim of the study was to compare the accuracy and reproducibility of three different 3D facial scanning systems, relying, respectively, on stereophotogrammetry, structured light and a smartphone app and camera.

METHODS

Thirty subjects have been scanned with three different facial scanning systems, stereophotogrammetry, structured light and a smartphone app and camera. Linear measurements were compared with direct anthropometries measured on the patient's face, while the study of areas (forehead, tip of the nose, chin, right and left cheek) was evaluated by overlapping scans using the Geomagic Control X program. Statistical analyses were conducted using IBM SPSS v28 software.

RESULTS

The ANOVA test was used to compare linear distances and direct anthropometry measurements, revealing statically significant values for all distances investigated, especially for the Face Hunter scanner, except for the Prn-Pog' distance (p = 0.092). The three facial scans were superimposed pairwise almost the 100 per cent of the overlapping areas fell within the tolerance limits for all three comparisons analysed. The chin was the most accurately reproduced, with no differences among scanners, while the forehead proved to be the least accurately reproduced by all scanners.

CONCLUSIONS

All three acquisition systems proved to be effective in capturing 3D images of the face, with the exception of the Face Hunter scanner, that produced statistically significant differences in linear measurements for the distances Tr-Na' and Zyg-Zyg with respect to direct anthropometric measurements.

Subjective evaluation of facial asymmetry with three-dimensional simulated images among the orthodontists and laypersons: a cross-sectional study

OBJECTIVES

We used three-dimensional (3D) virtual images to undertake a subjective evaluation of how different factors affect the perception of facial asymmetry among orthodontists and laypersons with the aim of providing a quantitative reference for clinics.

MATERIALS AND METHODS

A 3D virtual symmetrical facial image was acquired using FaceGen Modeller software. The left chin, mandible, lip and cheek of the virtual face were simulated in the horizontal (interior/exterior), vertical (up/down), or sagittal (forward or backward) direction in 3, 5, and 7 mm respectively with Maya software to increase asymmetry for the further subjective evaluation. A pilot study was performed among ten volunteers and 30 subjects of each group were expected to be included based on 80% sensitivity in this study. The sample size was increased by 60% to exclude incomplete and unqualified questionnaires. Eventually, a total of 48 orthodontists and 40 laypersons evaluated these images with a 10-point visual analog scale (VAS). The images were presented in random order. Each image would stop for 30 s for observers with a two-second interval between images. Asymmetry ratings and recognition accuracy for asymmetric virtual faces were analyzed to explore how different factors affect the subjective evaluation of facial asymmetry. Multivariate linear regression and multivariate logistic regression models were used for statistical data analysis.

RESULTS

Orthodontists were found to be more critical of asymmetry than laypersons. Our results showed that observers progressively decreased ratings by 1.219 on the VAS scale and increased recognition rates by 2.301-fold as the degree of asymmetry increased by 2 mm; asymmetry in the sagittal direction was the least noticeable compared with the horizontal and vertical directions; and chin asymmetry turned out to be the most sensitive part among the four parts we simulated. Mandible asymmetry was easily confused with cheek asymmetry in the horizontal direction.

CONCLUSIONS

The degree, types and parts of asymmetry can affect ratings for facial deformity as well as the accuracy rate of identifying the asymmetrical part. Although orthodontists have higher accuracy in diagnosing asymmetrical faces than laypersons, they fail to correctly distinguish some specific asymmetrical areas.

ANALYSIS OF PHOTOMETRIC FULL-FACE PARAMETERS WITH A DISTAL BITE TAKING INTO ACCOUNT THE TYPES OF MANDIBULAR GROWTH

OBJECTIVE

The aim: Determination of the peculiarities of full-face aesthetics in patients aged 10-13 years with a distal bite with different types of mandibular growth.

PATIENTS AND METHODS

Materials and methods: 74 patients aged 10-13 years with a distal bite and various types of mandibular growth took part in the study. The methods of photostatic image study described by I.I. Uzhumetskene (1970), V.P. Pereverzev (1979) were used in this research.

RESULTS

Results: To determine the type of face, a gl-me: zy-zy index was calculated. Index values ranging from 0.84 to 0.879 are indicative of a mesoprosopic (medium) type of face, an index less than 0.839 defines a europrosopic (broad) type, an index exceeding 0.88 is characteristic of a leptoprosopic (narrow) type. The facial shape in all patients was determined by the Izar facial-morphological index. Similarly, the facial shape can be determined by the facial tapered angle (< FTA). In all groups of teenagers, a decrease in the angle is noted, which is indicative of an elongated, narrow face. To assess the ratio of the middle and lower parts of the face, the gl-sn:sn-me index was used, which is normally equal to 1. In our case, this index was higher than normal in all groups of children as compared to the control group (1.01±0.03). The p-p:zy-zy and p-p:go-go indices are indicative of the harmonious facial development transversally.

CONCLUSION

Conclusions: Vertical and neutral-vertical type of mandibular growth results in a narrow (leptoprosopic) type of face; medium (mesoprosopic) and wide (europrosopic) types of face result from neutral, horizontal and neutral-horizontal types of growth. Irrespective of the type of mandibular growth, all patients with a distal bite have a short lower third of the face. The strongest aesthetic changes are reported in the group of patients with a predominance of the hori¬zontal type of mandibular growth.

The accuracy of a three-dimensional face model reconstructing method based on conventional clinical two-dimensional photos

Background

This study aims to investigate the accuracy of a three-dimensional (3D) face reconstruction method based on conventional clinical two-dimensional (2D) photos.

Methods

Twenty-three patients were included, and Character Creator v3.2 software with the Headshot v1.0 plugin was used for 3D face model reconstruction. Various facial landmarks were finely adjusted manually to refine the models. After preprocessing and repositioning, 3D deviation analysis was performed. The accuracy of the landmarks in different dimensions was determined, and twelve facial soft tissue measurements were compared to validate the clinical potential of the method.

Result

The reconstructed 3D face models showed good facial morphology with fine texture. The average root mean square errors between face scan models and reconstructed models at perioral area (1.26 ± 0.24 mm, 95%CI: 1.15–1.37 mm) were significantly smaller than the entire facial area (1.77 ± 0.23 mm, 95%CI:1.67–1.88 mm), P < 0.01. The deviation of menton of soft tissue was significantly larger than pronasale (P < 0.01). The deviations of all landmarks in the Y-direction were significantly larger than those in the other 2 dimensions (Y > Z > X, P < 0.01). A significant difference (P < 0.05) of approximately 1.5 mm was found for facial height. Significant differences (P < 0.05) were also identified in the remaining 6 soft tissue measurements, with average deviations no greater than 0.5 mm (linear measurement) or 1.2° (angular measurements).

Conclusion

A 3D face modeling method based on 2D face photos was revealed and validated. The reconstruction accuracy of this method is clinically acceptable for orthodontic measurement purposes, but narrow clinical indications and labor-intensive operations remain problems.