Validity and reliability of a structured-light 3D scanner and an ultrasound imaging system for measurements of facial skin thickness

Singular entry point technique for forehead and temple filler augmentation: Anatomical and clinical perspectives

BACKGROUND

The depressed volume of the forehead and temple is resolved by filler injection. However, the current method has the potential to cause pain and side effects in patients, depending on the skill of the clinician. Therefore, this study proposes a new method for safer and simpler injection using only one injection entry point.

METHODS

Using the novel injection method, the filler was injected into the forehead and temple regions in three unembalmed cadavers and two healthy Korean volunteers. The cannula and filler locations were identified using dissection, ultrasonography, and three-dimensional (3D) scanning.

RESULTS

Ultrasonographic images and dissection results showed that the filler injected into the cadavers was in the target layer. The cannula and filler were located on the layer as the supraperiosteal layer on the forehead and the supra deep temporal fascia layer in the temple. Finally, 3D scanning images showed that the filler was injected precisely and effectively into the forehead and temples of the volunteer who underwent the procedure.

CONCLUSIONS

This method can reduce pain and minimize externally visible wounds caused by injections. The injected filler was naturally connected from the forehead to the temple and maintained for around 3 months. Additionally, it is possible to inject fillers into the forehead and temple at a constant and safe depth without requiring specific skills. It is expected that this method will become a universal method because it minimizes the burden on both patients and clinicians.

Frontiers in Three-Dimensional Surface Imaging Systems for 3D Face Acquisition in Craniofacial Research and Practice: An Updated Literature Review

Digitalizing all aspects of dental care is a contemporary approach to ensuring the best possible clinical outcomes. Ongoing advancements in 3D face acquisition have been driven by continuous research on craniofacial structures and treatment effects. An array of 3D surface-imaging systems are currently available for generating photorealistic 3D facial images. However, choosing a purpose-specific system is challenging for clinicians due to variations in accuracy, reliability, resolution, and portability. Therefore, this review aims to provide clinicians and researchers with an overview of currently used or potential 3D surface imaging technologies and systems for 3D face acquisition in craniofacial research and daily practice. Through a comprehensive literature search, 71 articles meeting the inclusion criteria were included in the qualitative analysis, investigating the hardware, software, and operational aspects of these systems. The review offers updated information on 3D surface imaging technologies and systems to guide clinicians in selecting an optimal 3D face acquisition system. While some of these systems have already been implemented in clinical settings, others hold promise. Furthermore, driven by technological advances, novel devices will become cost-effective and portable, and will also enable accurate quantitative assessments, rapid treatment simulations, and improved outcomes.

Application of three-dimensional reconstruction technology in dentistry: a narrative review

BACKGROUND

Three-dimensional(3D) reconstruction technology is a method of transforming real goals into mathematical models consistent with computer logic expressions and has been widely used in dentistry, but the lack of review and summary leads to confusion and misinterpretation of information. The purpose of this review is to provide the first comprehensive link and scientific analysis of 3D reconstruction technology and dentistry to bridge the information bias between these two disciplines.

METHODS

The IEEE Xplore and PubMed databases were used for rigorous searches based on specific inclusion and exclusion criteria, supplemented by Google Academic as a complementary tool to retrieve all literature up to February 2023. We conducted a narrative review focusing on the empirical findings of the application of 3D reconstruction technology to dentistry.

RESULTS

We classify the technologies applied to dentistry according to their principles and summarize the different characteristics of each category, as well as the different application scenarios determined by these characteristics of each technique. In addition, we indicate their development prospects and worthy research directions in the field of dentistry, from individual techniques to the overall discipline of 3D reconstruction technology, respectively.

CONCLUSIONS

Researchers and clinicians should make different decisions on the choice of 3D reconstruction technology based on different objectives. The main trend in the future development of 3D reconstruction technology is the joint application of technology.

Customized Augmentation Rhinoplasty With Morpheus 3-Dimensional Scanner

PURPOSE

Three-dimensional (3D) scanning-based morphologic analyses of facial structures are becoming more popular in several clinical settings. However, the application has not yet been reported in augmentation rhinoplasty. The purpose of the study is to show the efficacy of the Morpheus 3D scanner for preoperative planning in rhinoplasty.

METHODS

In this retrospective review, 241 patients who underwent primary and secondary rhinoplasty from September 2018 to August 2020 were reviewed. The authors determined the degree of augmentation preoperatively using the Morpheus 3D scanner based on patients' esthetic needs. According to the simulated 3D embodiment result, the Silicone implant was carved and implanted with closed or open rhinoplasty approach.

RESULTS

The operation was performed based on the simulated 3D shape, and the patients were satisfied with the esthetic outcomes.

CONCLUSIONS

Morpheus 3D scanner can be a valuable tool for esthetic rhinoplasty planning. This tool also provides preoperative customized patient counseling based on their current anatomic characteristics and esthetic needs.

Positional deformation of the parotid gland: application to minimally invasive procedures

Anatomical studies of the parotid gland are important for mid- and lower face filler, botulinum toxin, and thread lifting procedures. The purpose of this study was to observe the topographic anatomy of the parotid gland using cadaveric dissections. The superficial lobe of the parotid gland was studied in 30 hemisected heads. Reference lines were made on the lateral aspect of the face. A reference line (the line connecting the mandibular angle to the upper margin of the zygomatic arch, along the posterior border of the ramus) was divided into four sections (P1, P2, P3, and P4). The superior, inferior, anterior, and posterior borders of the parotid gland were measured using the reference lines and sections. Using these measurements, we categorized the superficial lobe of the parotid gland into two types: type Ia, pistol-shaped; Ib, pistol-shaped with an accessory lobe; and type II, oval-shaped. The superior border of the parotid gland started just below the inferior margin of the zygomatic arch. The parotid gland covered the posterior part of the masseter muscle near P1 and P2, but at P3 and below P3, the tail of the parotid gland was located posterior to the ramus and covered the anterior part of the sternocleidomastoid muscle. The topographic anatomy of the parotid gland serves as a reliable reference for esthetic procedures in the lower face and neck region. This article is protected by copyright. All rights reserved.

The facial soft tissue thickness related facial reconstruction by ultrasonographic imaging: A review

The facial soft tissue thickness is crucial for facial reconstruction. Ultrasound is one method to evaluate facial thickness. There are two main modes of ultrasound that can be used for measurement: A-mode and B-mode. Because of its advantage, B-mode is frequently used in many recent studies. The factors that contribute to the varying results of facial soft tissue thickness are classified as method error and biological factors. The following factors should be considered when designing a study: subject type, subject posture and facial expression, ultrasound machine, ultrasound mode, transducer type, frequency, gel type and application, transducer orientation, landmark selection, and thickness measurement. According to the results of previous research, the main biological factors that likely affected facial thickness are sex, age, body mass index, and ancestry. However, there is still insufficient evidence to conclude how the thickness differs among various methods of measurement and which method produces the best results for facial reconstruction. Future ultrasonographic imaging research associated with facial thickness should determine the accuracy of the facial reconstruction to compare with other techniques and evaluate the gold standard of the facial reconstruction. Furthermore, the standardized landmarks and ultrasonographic imaging of each landmark should be clarified for consistency across the populations.

Reliability of cone beam CT for morphometry of nasolabial soft tissue in patients with skeletal class III malocclusion: A qualitative and quantitative analysis

OBJECTIVE

To assess reliability of cone-beam CT (CBCT) for nasolabial soft tissue measurements in patients with skeletal class III malocclusion based on 3-dimensional (3D) facial scanner results.

METHODS

CBCT and 3D facial scan images of 20 orthognathic patients are used in this study. Eleven soft tissue landmarks and 15 linear and angular measurements are identified and performed. For qualitative evaluation, Shapiro-Wilk test and Bland-Altman plots are applied to analyze the equivalence of the measurements derived from these two kinds of images. To quantify specific deviation of CBCT measurements from facial scanner, the latter is set as a benchmark, and mean absolute difference (MAD) and relative error magnitude (REM) for each variable are also calculated.

RESULTS

Statistically significant differences are observed in regions of nasal base and lower lip vermilion between two methods. MAD value for all length measurements are less than 2 mm and for angular variables < 8°. The average MAD and REM for length measurements are 0.94 mm and 5.64%, and for angular measurements are 2.27° and 3.78%, respectively.

CONCLUSIONS

The soft tissue results measured by CBCT show relatively good reliability and can be used for 3D measurement of soft tissue in the nasolabial region clinically.

Three-Dimensional Computed Tomography of the Detoured Facial Artery: Variations and Implications for Nasojugal Groove Correction

BACKGROUND

When performing filler injection procedures to the nasojugal groove, there is the risk of iatrogenic damage to the detoured facial artery.

OBJECTIVE

To determine the 3-dimensional location of the detoured facial artery.

MATERIALS AND METHODS

The branches of the facial arteries from 118 cadaveric hemifaces were scanned using computed tomography and reconstructed using the Mimics software program.

RESULTS

Detoured facial arteries were found in 47 of the 118 hemifaces (39.8%). Two main arterial patterns were identified: in Type I (29 of 47 cases), there were both detoured and nasolabial trunks where the facial artery originated, whereas in Type II (18 of 47 cases), there was only a detoured trunk. The detoured trunk originated 32.0 ± 5.3 mm from the midsagittal line, 5.0 ± 2.8 mm from the occlusion plane, and 5.9 ± 3.5 mm below the skin layer; the inflection of the detoured trunk was located 30.0 ± 5.6 mm laterally, 26.2 ± 4.4 mm superiorly, and 5.7 ± 2.6 mm deep. The meeting point with the inferior orbital rim plane was located 17.1 ± 3.4 mm laterally, 43.4 ± 3.1 mm superiorly, and 2.8 ± 1.7 mm deep.

CONCLUSION

The 3-dimensional location of the detoured facial artery as reported here will help clinicians to avoid iatrogenic damage when they are performing filler injection procedures.

Three-Dimensional Evaluation of the Depressor Anguli Oris and Depressor Labii Inferioris for Botulinum Toxin Injections

BACKGROUND

Botulinum toxin type A (BoNT-A) injection administered at an inappropriate site or depth can produce an unwanted change in facial animation because the depressor anguli oris (DAO) and depressor labii inferioris (DLI) muscles are partially overlapped. Therefore, simple BoNT-A injection guidelines, based on 3-dimensional (3D) facial anatomic references and landmarks, would be very useful.

OBJECTIVES

The aim of this study was to establish novel BoNT-A injection guidelines that include the soft tissue thickness at the lower perioral region. Data were acquired with a 3D scanning system combined with dissections in order to obtain accurate injection sites and depths for the DAO and DLI.

METHODS

3D scans of the facial skin, superficial fat, and facial muscle surface were performed in 45 embalmed cadavers. The thicknesses of the skin and subcutaneous layer were calculated automatically from superimposed images at each of 5 reference points (P) in the perioral region.

RESULTS

In every case (100%), P3 and P5 were located in the DLI and DAO areas, respectively (45/45). Therefore, we defined P3 as the "DLI point" and P5 as the "DAO point." The soft tissue thicknesses at the DLI and DAO points were 6.4 [1.7] mm and 6.7 [1.8] mm, respectively.

CONCLUSIONS

The P3 and P5 described in this study are effective guidelines that only target the DLI and DAO. Clinicians, specifically, can easily use facial landmarks, such as the cheilion and pupil, to assign the DLI and DAO points without any measurement or palpation of the modiolus.

Clinical Application of a Patient-Specific, Three-Dimensional Printing Guide Based on Computer Simulation for Rhinoplasty

BACKGROUND

A practical application of three-dimensional printing technology has been considered a difficult area in rhinoplasty. However, the patient-specific three-dimensionally printed rhinoplasty guide based on the simulation program the authors developed could be a solution for minimizing the gap between simulation and actual surgical results. The aims of this study were to determine how a three-dimensional rhinoplasty guide based on three-dimensional simulation would link the patient to the surgeon to investigate its effectiveness.

METHODS

Fifty patients who underwent rhinoplasty between January of 2017 and February of 2018 were included in this study. The patients were consulted about the desired shape of their nose based on preoperative three-dimensional photography. The confirmed three-dimensional simulation was sent to a manufacturing company for three-dimensionally printed rhinoplasty guides. In the guide group, rhinoplasty was performed based on the three-dimensionally printed rhinoplasty guide, and in the control group, procedures were performed based on the surgeon's intuition.

RESULTS

The intraclass correlation coefficient test for comparing the simulated and postoperative measurements showed higher correlation in the three-dimensional printing guide group: higher correlation 11.3 percent in nasal tip projection, 21.6 percent in dorsum height, and 9.8 percent in nasolabial angle. The postoperative result of the nasal dorsum had a statistically significant difference between the two groups (p < 0.05).

CONCLUSIONS

This study demonstrated the usefulness of the three-dimensionally-printed rhinoplasty guide, which delivers the preoperative simulated image in the actual clinical practice of rhinoplasty. This approach could cause a paradigm shift in simulation-based rhinoplasty.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Implication of Location of the Ascending Mental Artery at the Chin Injection Point

BACKGROUND

Facial proportions can be improved by means of chin augmentation in patients with a receding chin. The ascending mental artery is the main arterial supply to the top of the chin, and arterial occlusion of this artery can result in soft-tissue infarction. This study aims to measure the topographic anatomy of the ascending mental artery at the chin injection area, using a three-dimensional camera.

METHODS

Thirty-one embalmed cadaveric faces were dissected at the chin. The midline of the inferior margin of the mandibular protuberance was marked with a pin. A variation in size between the two opposite ascending mental arteries was noticed. The depth of the artery from the skin surface and distance from the midline were measured using a three-dimensional camera.

RESULTS

There were 19 dominant ascending mental arteries on the right and 12 on the left. The dominant ascending mental arteries enter the chin paracentrally, approximately 6 mm (mean ± SD, 5.64 ± 4.34 mm) from the midline, within the muscular plane, and at a depth of 4.15 ± 1.95 mm from the skin. Furthermore, the artery formed an anastomosis with the sublingual artery, within the floor of the mouth.

CONCLUSION

Every aesthetic physician should recognize the course of the ascending mental artery and use the appropriate techniques to avoid vascular injury during chin augmentation using filler injections.

Three-Dimensional Territory and Depth of the Corrugator Supercilii: Application to Botulinum Neurotoxin Injection

This study aimed to determine the three-dimensional (3D) territory and depth of the corrugator supercilii muscle (CSM) using a 3D structured-light scanner. Thirty-two hemifaces from Korean and Thai embalmed cadavers were used in this study, and 35 healthy young Korean subjects also participated. A 3D analysis of the CSM territory and depth was performed using a structured-light 3D scanner. The most frequently observed locations of the CSM identified in the cadaver were confirmed in healthy young subjects using a real-time two-dimensional B-mode ultrasonography system. The CSM was present in all of the cadavers and healthy young subjects at the intersection point between the vertical line passing through the medial canthus and the horizontal line passing through the glabella (Point #6). The CSM was located on the medial side of the lateral limbus in most cases. The most-medial and most-lateral origin points were at depths of 5.7 ± 1.4 mm (mean ± SD) and 6.6 ± 1.4 mm, respectively; the corresponding depths of the insertion points were 5.4 ± 1.4 mm and 5.6 ± 2.1 mm, respectively. The origin and insertion points of the CSM were at similar depths. The injection depth should be around 4 mm for botulinum neurotoxin (BoNT) injections into the CSM. Point #6 could be regarded as an effective target point for managing the glabellar frown line and preventing palpebral ptosis when injecting BoNT into the CSM. Clin. Anat., 33:795-803, 2020. © 2019 Wiley Periodicals, Inc.

A novel anatomical consideration on the exposed segment of the facial artery

An understanding of the location and depth of the facial artery (FA) is essential in aesthetic surgery and various cosmetic procedures. The purpose of this study was to clarify the three-dimensional (3D) topography of the exposed segment (ES) of the FA and to provide information to help minimize complications during clinical procedures. From 50 embalmed adult cadavers, the undissected and dissected hemifaces were scanned and reconstructed using the 3D scanner. Then the topographic location of the ES was identified and measured from the superimposed the 3D images. The ES was observed in 82% of the whole specimens. The exposure patterns of the ES were examined, and classified into three types: Type I, one site exposed pattern (74%); Type II, two sites exposed pattern (8%); and Type III, nonexposed pattern (18%). The extent of the ES was located at 2.2 mm above and 4.2 mm below the cheilion (Ch)-otobasion inferius line, and 20.0 to 25.2 mm from the Ch on the lateral aspect. In the frontal view, the average distance from the mid-pupillary line to the ES was 7.1 mm, and from the lateral canthal line to the ES was 6.1 mm. The ES was 7.6 mm below the skin surface. The results of this study will help to provide safe guidelines for filler injections as well as selecting the safe regions in various clinical procedures. Clin. Anat. 33:257-264, 2020. © 2019 Wiley Periodicals, Inc.

Ultrasonographic and Three-Dimensional Analyses at the Glabella and Radix of the Nose for Botulinum Neurotoxin Injection Procedures into the Procerus Muscle

Botulinum neurotoxin (BoNT) injections are widely used for facial rejuvenation procedures, and the procerus muscle is a major target in cases of glabellar transverse lines or rhytids. Although there have been many cadaveric studies of the procerus, its depth and thickness have not been investigated thoroughly. The aim of this study was to measure the depth and thickness of the procerus and identify the location of the intercanthal vein using ultrasonographic (US) imaging and the three-dimensional scanning method, which is needed to know to avoid side effects during BoNT injections. The morphology of the procerus was classified into two types based on the US images obtained at the glabella. The procerus was located deeper below the skin surface at the glabella than the sellion (3.8 ± 0.7 mm versus 2.7 ± 0.6 mm). The width of the procerus in US images increased from the sellion (10.9 ± 0.2 mm) to the glabella (14.5 ± 4.6 mm), whereas its thickness decreased (from 1.6 ± 0.6 mm to 1.1 ± 0.5 mm). The intercanthal vein was located 5.1 ± 4.0 mm superior to the sellion and 3.0 ± 0.6 mm below the skin’s surface. The present findings provide anatomical knowledge as well as the reference location information for use when injecting BoNT into the procerus.

What Do We Find Attractive about the Face?: Survey Study with Application to Aesthetic Surgery

The appearance of the face is one of the most important factors influencing our perception of beauty. However, few studies have attempted to quantitate what one perceives as beauty. Therefore, this study was conducted with the goal of providing physicians with anatomical data that demonstrate which facial traits most influence our perception of one's attractiveness. In the first phase of the study, faces of 60 participants (30 males and 30 females) were photographed. Next, the photographs were shown to another group of 120 study members (60 males and 60 females), who evaluated the facial features using a Visual Analogue Scale. The highest rated facial parts were then measured using the ImageJ program. In men, the most attractive parts of the face were Type 1:2 lips, a Type IV nose of medium width, blue eyes, brown hair, and a very narrow face. Among females, the most attractive parts of the face were Type 2:1 lips, Type III and V noses of medium width, dark brown eyes, blonde hair, and a narrow face. This is the first study in which the most aesthetically important facial parts have been comprehensively examined. The results obtained in our study show a higher degree of representativeness compared to other studies due to a different methodological approach and can be used as an aesthetic guide and can help in the planning of aesthetic surgery such as lip augmentation and rhinoplasty. Clin. Anat. 33:214-222, 2020. © 2019 Wiley Periodicals, Inc.

Regional thickness of facial skin and superficial fat: Application to the minimally invasive procedures

Various recently introduced minimally invasive treatment modalities are now widely used for enhancing the aging face. In a special, filler is used to increase the volume of tissue, and so understanding the regional thickness and distribution of the facial superficial fat is essential for optimizing minimally invasive procedures. The aim of this study was to establish the overall facial skin and superficial fat thicknesses using a three-dimensional (3D) scanning system. From 53 adult Korean and Thai embalmed adult cadavers, the undissected and serially-dissected facial specimens were scanned and reconstructed. The facial skin and superficial fat thicknesses on seven facial regions were calculated from the superimposed images. The facial skin tended to become thicker in the order of the radix and dorsum, and the temple, supraorbital, forehead, perioral, cheek, and infraorbital areas. The skin was thinnest at radix and dorsum (1.51 ± 0.55 mm), and thickest in infraorbital region (1.97 ± 0.84 mm). The facial superficial fat thickness tended to increase in the order of the radix and dorsum, supraorbital, forehead, temple, cheek, infraorbital, and perioral regions. The superficial fat was thinnest at the radix and dorsum (1.61 ± 1.07 mm), and thickest in the perioral region (5.14 ± 3.31 mm). The facial superficial fat thickness tended to increase in the order of the radix and dorsum, supraorbital, forehead, temple, cheek, infraorbital, and perioral regions. The present findings indicate that 3D scanning system can yield crucial anatomical information about depths of the facial skin and superficial fat layers for utilization in various clinical procedures. Clin. Anat. 32:1008-1018, 2019. © 2019 Wiley Periodicals, Inc.

Three-Dimensional Topography of the Emerging Point of the Ophthalmic Artery

BACKGROUND

During periorbital noninvasive and surgical procedures, there is the risk of iatrogenic injury to the emerging point of the ophthalmic artery. This study aimed to determine the three-dimensional location of the emerging point of the ophthalmic artery and to provide clinicians with anatomical information that would help them to avoid associated complications.

METHODS

Seventeen hemifaces of the emerging point of the ophthalmic artery from 10 Korean and seven Thai cadavers were dissected and scanned by a three-dimensional scanner. The emerging points of the ophthalmic artery of 30 healthy Korean volunteers were also detected using an ultrasound imaging system.

RESULTS

The transverse distance from the medial canthus to the emerging of the ophthalmic artery was 3.8 ± 1.0 mm medially, and the vertical distance was 14.0 ± 2.9 mm superiorly. The transverse distance from the midline was 16.5 ± 1.7 mm to the emerging point of the ophthalmic artery and 20.0 ± 2.0 mm to the medial canthus. The measured depth from the skin surface to the emerging point of the ophthalmic artery was 4.8 ± 1.7 mm by means of three-dimensional scanning and 4.5 ± 1.1 mm using ultrasound detection. The vertical distance from the inferior margin of the superior orbital rim to the emerging point of the ophthalmic artery was 5.3 ± 1.4 mm.

CONCLUSION

These data inform clinicians about the anatomical three-dimensional location of the emerging point of the ophthalmic artery, which will help them to avoid iatrogenic injury when they are performing periorbital clinical procedures.