Evaluation of Bone Thickness and Density Values in Resistance Regions in Rapid Maxillary Expansion Using Computed Tomography.

OBJECTIVES: This study used computed tomography (CT) to compare the bone thickness and density values around the zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures that are resistant to rapid maxillary expansion (RME) treatment according to age, sex, and cervical vertebrae maturation (CVM) stage. METHODS: The study included 200 paranasal sinus records obtained for medical diagnosis and examination in a radiology clinic. The records provided data on 110 males and 90 females aged between 4 and 28 years. Bone thickness and density values around the zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures were measured using CT imaging. The correlations of bone thickness and density values with the variables of age, sex, and CVM stage were evaluated. RESULTS: No statistically significant difference was revealed between the bone thickness values around the zygomaticomaxillary and zygomaticotemporal sutures and age, sex, CVM stage, and the right and left regions of the same individual ( P >0.05). A strong correlation was identified between Hounsfield units (Hu) values on bone density in all 3 regions and age and sex ( P <0.001). No correlation was found between the CVM stage and density values around the zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures ( P >0.05). CONCLUSIONS: The Hu values of the records from females were higher than those of males in all age groups. It was observed that with increasing age, bone density values increased in all 3 regions, and thus circummaxillary region's Hu value increased.

Investigating the Contraction Pattern of the Zygomaticus Major Muscle and its Clinical Relevance: A Functional MRI Study.

BACKGROUND: Our understanding of facial anatomy has significantly evolved, yet the detailed contraction patterns of facial muscles and their presentation during clinical imaging remain largely unexplored. Understanding the contraction patterns and visual presentation of these muscles, particularly the zygomaticus major could enhance pre-surgical facial assessments and the development of new treatment strategies. METHODS: A total of 34 healthy young individuals (17 female, 17 male) with a mean age of 23.6 (2.4) years [range: 20-30] were investigated regarding the length, thickness, width, and angle of the zygomaticus major muscle in five different facial expressions (i.e., repose, anger, joy, surprise, and sadness) utilizing MR imaging. RESULTS: Joyful expressions caused a reduction in muscle length to 85.6% of its original length and an increase in width (103.4%), thickness (108.4%), and facial angle (2.72°) when compared to that in repose, suggesting isotonic contraction. Conversely, expressions of anger, surprise, and sadness generally led to muscle stretching, seen through changes in length (98.9%, 104.3%, and 102.7%, respectively), width (98.8%, 96.5%, and 99.4%, respectively), and thickness (91.2%, 91.0%, and 102.7%, respectively), with variable alterations in facial angle (0.55°, 1.85°, and 1.00°, respectively) depending on the specific expression. CONCLUSION: This MRI-based study indicates that the zygomaticus major muscle experiences isotonic contraction, characterized by decreased length and increased width and thickness. The findings underline the importance of muscle thickness as a reliable parameter in assessing facial muscle function and offer valuable guidance for practitioners in accurately evaluating muscle performance during different facial expressions. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. 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 .

Anatomical variations of the zygomaticofacial foramen and its related canal through the zygomatico-orbital and zygomaticotemporal foramina in dry human skulls.

PURPOSE: The aim of this study is to reveal the location of the zygomaticofacial foramina, the variations of their numbers, and their connections between the zygomatico-orbital and zygomaticotemporal foramina. METHODS: Ethics committee approval of our study was received by the Istanbul Medical Faculty Clinical Research Ethics Committee (date:30.07.2021, number:358356). 171 zygomatic bones of unknown gender from the Department of Anatomy, Istanbul University, were included in this study. The number of zygomaticofacial foramina and their connections with the zygomatico-orbital foramen and the zygomaticotemporal foramina were examined. Also, the morphometric distances between the zygomaticofacial foramen were calculated. Evaluation of the data was done with SPPS v.21. RESULTS: The number of zygomaticofacial foramina was found as 299. It was found single, double, three, four, five and six foramina, in 52 (30.4%), 52 (30.4%), 24 (14.03%), 10 (5.85%), 5 (2.93%), 1 (0.58%) zygomatic bone, respectively. Zygomaticofacial foramen was absent in 27 (15.8%) bones. Of these 299 foramina, 129 were found to be connected with zygomatico-orbital foramen and 23 with zygomaticotemporal foramen. It was noted that 147 zygomaticofacial foramina had no connection with any foramina. The distances between the zygomaticofacial foramen and the frontozygomatic suture, temporal process, maxillary process, the lowest point of the zygomatic bone, and orbital rim were found as 25.30 ± 2.81mm, 18.74 ± 3.56mm, 21.56 ± 4.16mm, 18.72 ± 2.57mm, 6.67 ± 3.27mm, respectively. CONCLUSION: Consequently, the location and variations of ZFF are of great importance for maxillofacial surgery and regional block anesthesia. Knowing its location and variations will help prevent complications during any surgical intervention in this region.

Assessing the frequency and variability of accessory zygomatic sutures in dry skulls: clinical insights and potential implications.

PURPOSE: This study aimed to determine the presence and incidence of accessory sutures and bipartite zygomatic bone types, and their effects on population affinity and clinical significance. METHODS: We examined 120 dry skulls and 50 zygomatic bones to evaluate the presence, frequency, and location of accessory zygomatic sutures as well as subtypes of bipartite zygomatic bones. Morphometric analysis included measuring the total width and length of the zygomatic bone with accessory sutures (ASs), the total length of the AS, and the shortest distance between the AS and various anatomical landmarks. RESULTS: Bipartite zygomatic bone was observed in 14 of 120 dry skulls (11.6%) and 1 of 50 zygomatic bones (2%), indicating an overall incidence of 16 occurrences (8.82%). The ASs were predominantly located posterolaterally in 11 cases (six males, five females), anteromedially in two cases (one male, one female), superiorly in one case (male), and superolaterally in one case (male). Significant differences were noted in the distribution of the ASs (p < 0.001). Notably, a vertical inferior bipartite zygomatic type, which has not been reported in the literature, was identified. Correlations were observed between the various anatomical landmarks. Among females, the length of AS was significantly different (p = 0.038). Significant differences were also noted in the shortest distance between the AS and the zygomaticofacial foramen (ZFF) based on the body side (p = 0.034). CONCLUSIONS: Our study suggests that the bipartite zygomatic bone is not a common occurrence, indicating its significance as a morphological variation present in certain individuals. The type VII bipartite zygomatic bone exhibited the highest incidence rate, suggesting potential ethnic-specific differences in the prevalence of certain subtypes. The consistent pattern of suture distribution, along with the asymmetry and variability in suture patterns, emphasizes its potential clinical relevance.

Effects of exposure length, cortical and trabecular bone contact areas on primary stability of infrazygomatic crest mini-screws at different insertion angles.

BACKGROUND: The infrazygomatic crest mini-screw has been widely used, but the biomechanical performance of mini-screws at different insertion angles is still uncertain. The aim of this study was to analyse the primary stability of infrazygomatic crest mini-screws at different angles and to explore the effects of the exposure length (EL), screw-cortical bone contact area (SCA), and screw-trabecular bone contact area (STA) on this primary stability. METHODS: Ninety synthetic bones were assigned to nine groups to insert mini-screws at the cross-combined angles in the occlusogingival and mesiodistal directions. SCA, STA, EL, and lateral pull-out strength (LPS) were measured, and their relationships were analysed. Twelve mini-screws were then inserted at the optimal and poor angulations into the maxillae from six fresh cadaver heads, and the same biomechanical metrics were measured for validation. RESULTS: In the synthetic-bone test, the LPS, SCA, STA, and EL had significant correlations with the angle in the occlusogingival direction (rLPS = 0.886, rSCA = -0.946, rSTA = 0.911, and rEL= -0.731; all P < 0.001). In the cadaver-validation test, significant differences were noted in the LPS (P = 0.011), SCA (P = 0.020), STA (P = 0.004), and EL (P = 0.001) between the poor and optimal angulations in the occlusogingival direction. The STA had positive correlations with LPS (rs = 0.245 [synthetic-bone test] and r = 0.720 [cadaver-validation test]; both P < 0.05). CONCLUSIONS: The primary stability of the infrazygomatic crest mini-screw was correlated with occlusogingival angulations. The STA significantly affected the primary stability of the infrazygomatic crest mini-screw, but the SCA and EL did not.

Frequency Morphologic and Morphometric Properties and Osseous Relationships of Whitnall's Tubercle.

Whitnall tubercle (WT) of the zygomatic bone is used as an anatomical landmark in some surgical approaches to the orbit. The authors aimed to determine the localization of WT by using some palpable bony landmarks and to reveal its morphological and morphometric features. Three hundred twenty-two zygomatic bones (167 right and 155 left) belonging to adults of unknown sex, were examined. An acetate prepared by drawing a clock with a dial on it was used to determine the localization of WT according to marginal tubercle and zygomatic arch. Distances between WT and frontozygomatic suture and lateral margin of the orbital rim were measured with digital calipers. One zygomatic bone had double tubercles, thus 321 bones were taken into consideration. Whitnall tubercle was determined in 284 of 321 zygomatic bones. 181 were classified as small, 10 as medium, and 93 as large. The position of the WT according to the marginal tubercle was at the 8, 9, and 10 o'clock positions on the left, and at 2, 3, and 4 o'clock on the right. The position of the WT according to the zygomatic arch was at the 9,10 and 11 o'clock positions on the left, and at the 1 and 2 o'clock positions on the right. Distances between the WT and lateral margin of the orbital rim and the frontozygomatic suture were measured meanly as 1.94±0.31 mm and 8.17±5.82 mm, respectively. The authors believe that the data obtained regarding WT will contribute to anatomy and surgical procedures of the related region.

A marginal process of the zygomatic bone predicts a lateral exit of the zygomaticotemporal nerve: An anatomical study with application to surgery around the midface.

Previous studies have not verified the contents of accessory foramina of the zygomatic bone on dry skulls and thus could not conclude whether they carried accessory zygomaticofacial nerve branches or branches or the entire trunk of the zygomaticotemporal nerve (ZTN). Therefore, the aim of the current study is to present findings from cadaveric dissections to clarify this relationship. Fifty, fresh frozen, adult cadaveric sides underwent dissection of the ZTN. When identified, these nerves were quantified and their relationship to the zygomatic bone further documented by dissecting through the bone following the course of the nerve from a superficial to deep perspective. Additionally, 100 dry, adult, human skulls were analyzed looking for lateral foramina on the zygomatic bone. On three cadaveric sides (6%), the ZTN was found to pierce the zygomatic bone deeply and exit its superficial lateral surface. For dry skull specimens, a lateral zygomaticotemporal foramen (ZTF) was identified on nine sides (4.5%). For both groups, the presence of a strong marginal process of the zygomatic bone was strongly correlated to a ZTF exiting the lateral surface of the zygomatic bone. Although relatively uncommon, the ZTN can pierce the lateral aspect of the zygomatic bone and thus can be located superficial to the cheek. Such findings should be borne in mind during surgical or other invasive procedures in this area in order to minimize iatrogenic injury to the ZTN.

Topographic Anatomy of the Zygomatico-Orbital Artery.

ABSTRACT: The zygomatico-orbital artery (ZOA) originating from the superficial temporal artery and supplying the lower temporal region superficially has been reported. Previous studies of this artery have used definitions that are too ambiguous for the results to be directly adapted to clinical practice, including since they have resulted in marked variations in the reported incidence ofthe artery. This study dissected 193 hemifaces of 123 fixed human cadavers aged 36 to 102 years (119 males and 74 females). The authors investigated the ZOA based on the following definition: (1) it originates from the superficial temporal artery, (2) it runs mostly above the zygomatic arch, and (3) it terminates below the superior border of the orbicularis oculi muscle. The incidence of the ZOA was 22.8% (44 cases of 193 sides), and its mean diameter was 1.1 mm. The meanvertical distances from the superior borderofthe zygomatic arch to the artery were 29.6, 17.8, and 2.9 mm at the jugale, zygion, and the origin of the ZOA, respectively. An accurate definition of the ZOA and accurate knowledge of its incidence and course could be important for clinicians to avoid unintentional complications in clinical practice.

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.

Safe Zone for Dissection in Frontotemporal Region to Avoid Injury to the Temporal Branch of Facial Nerve.

ABSTRACT: The objective of this study is to provide a reliable roadmap for temporal branch of the facial nerve, in order to minimize, the risk of injury to the nerve during surgical dissections. A literature search was conducted on temporal branch of facial nerve. The date search range was 1950 to 2017. Databases searched included Medline, Web of science, Biosis, SciELO, Data Citation, and Zoologic Records. Data were collected on, author specialty, date of publication, and the relationship of the temporal branch of facial nerve to various landmarks in the frontotemporal region reported in human anatomic studies. Among the 48 studies reviewed, a total of 3477 anatomic dissections were performed in the craniofacial region. Temporal branch of facial nerve was located between 2.5 and 3 cm from lateral orbital rim. In relation to the zygomatic arch, it was found anywhere from the midpoint of the arch to 1 finger breath posterior to the arch. For the plane, it was most commonly described as being under the superficial temporal fascia (STF) or within the loose areolar tissue. Most anatomic dissections found 2 to 4 twigs of the temporal branch of facial nerve. In relation to the lateral canthus, it was found to be 2.85 +/- 0.69 cm superior and 2.54 +/- 0.43 cm lateral to the lateral canthus. Our study suggests consolidated data on surgical landmarks in order to ensure safe dissection in temporal region and prevent injury to the temporal branch of facial nerve.

Anatomy and external landmarks of the superficial temporal artery using 3-dimensional computed tomography.

PURPOSE: The purpose of this study was to analyze the anatomical variability of the superficial temporal artery (STA) and to provide an easy visual landmark to find the STA and its branches to facilitate its surgical access. METHODS: A retrospective study was conducted on 57 patients who underwent a head and neck computed tomography with contrast injection. A visual landmark running from the tragus to the corner of the eye was used: the "eye-tragus-line" (ETL). On the ETL, the distance between the tragus and the STA was measured. The length of the STA main branch, its parietal and frontal branch and the angle of the STA and its branches with the ETL were measured. The division of the STA was studied as above/at the same level/below the zygomatic arch (ZA) and the ETL. RESULTS: The STA division was located above the ZA in 61.54% of cases, at the same level in 26.92% of cases and below in 11.54% of cases. Regarding the ETL, 93.27% of the STA divisions were located above the ETL, 5.77% at the same level and 0.96% below. On the ETL, the STA was located 15.55 ± 4.5 mm in front of the tragus. CONCLUSION: This study allowed to define an easy visual landmark: the ETL running from the tragus to the corner of the eye. The STA main branch was located 15.55 ± 4.5 mm of front of the tragus on the ETL. The STA division was nearly always located above the ETL (99.04%). Furthermore, this study provides a statistical representation of the anatomy of the STA and its branches.

Defining a Preauricular Safe Zone: A Cadaveric Study of the Frontotemporal Branch of the Facial Nerve.

BACKGROUND: In the preauricular region, the frontotemporal branch of the facial nerve is vulnerable to injury, which can result in facial palsy and poor cosmesis after surgical interventions. OBJECTIVES: The purpose of this study was to describe variations in the branching patterns of the frontotemporal branch of the facial nerve and the relation between this branch and the surrounding anatomic landmarks. Based on our findings, we propose a Danger Zone and Safe Zones for preauricular interventions to avoid frontal branch injury. METHODS: Twenty cadaveric half-heads, 10 freshly frozen and 10 embalmed, were dissected. The anatomy of the auriculotemporal nerve, facial nerve, and variations of its branching pattern in the preauricular region were investigated. RESULTS: The mean [standard deviation] number of frontotemporal branches crossing the zygomatic arch was 2.05 [0.6]. Beginning from the X point at the apex of the intertragal notch, frontal branches ran over the zygomatic arch at a distance extending from 10 to 31 mm anterior to the tragus, which can be defined as the Danger Zone for frontal branches. Safe Zones A and B are triangular regions located behind and in front of the Danger Zone, respectively. CONCLUSIONS: Mapping of these Safety and Danger Zones is a reliable and simple approach in preauricular interventions to avoid frontal branch injury because the facial nerve typically has multiple frontal branches. This approach provides practical information for surgeons rather than estimating the trajectory of a single frontal branch from Pitanuy's line.

Anthropometric Research of Metric Characters in Zygomatic Complex Region.

OBJECTIVES: To get and analyze the metric data of zygomatic region for the plasty of zygoma. MATERIALS AND METHODS: A total of 108 dry skulls in Chinese Han population were randomly collected and measured. The metrical data were divided into 4 parts, including the relative position of contour height of zygomatic bone, the relative prominence of zygomatic bone, the relative prominence of zygomatic arch, and the angle of the zygomatic bone and arch. RESULTS: The measurements in the 4 parts showed significantly difference between male and female (P < 0.05). For relative position of contour height of zygomatic bone group, the data of male is significantly bigger than female (P < 0.05). For relative prominence of zygomatic bone/zygomatic arch group, zygoma/zygomatic arch of male significantly protruded more than female (P < 0.05). CONCLUSION: The location of male zygoma is more protruding than female. The female zygoma is squarer than male and marginal process is helpful in zygomatic plasty. CLINICAL RELEVANCE: These studies show and analyze the metric data of zygomatic region in Chinese Han population for the plasty of zygoma. These different characters between males and females could be helpful in zygomatic plasty of Chinese Han population based on this research.

A Simple Clinical Application for Locating the Frontotemporal Branch of the Facial Nerve Using the Zygomatic Arch and the Tragus.

BACKGROUND: The seventh cranial nerve (CN VII), also known as the facial nerve, is an anatomically intricate structure the branches of which serve several physiologic functions. CN VII innervates the muscles of facial expression which are crucial for eye protection, oral competence, and social interaction. The temporal branch, clinically referred to as the frontotemporal branch (FTB), is the most superior of the 5 branches and is at risk during cutaneous surgery of the parotid gland and in the temporal region. Several methods for delineating the FTB trajectory exist, the most widely known being Pitanguy's Line, which is defined as running from 0.5 cm below the tragus to 1.5 cm above the lateral eyebrow. However, variations in eyebrow location, often affected by modern-day cosmetic trends, complicate the accuracy of this approach. OBJECTIVES: The aim of this study was to develop a surgical landmark to identify FTB location without relying on soft tissue structures. METHODS: To minimize variation, we chose landmarks that were both consistent and easy to locate based on simple surface anatomy. Twenty-one cadaver hemifaces were dissected in order to locate the FTB in relation to the inferior border of the zygomatic arch and the apex of the tragus. RESULTS: We found that the mean ± SEM distance from the apex of the tragus to the point where the FTB crossed the inferior border of the zygomatic arch was 3.21 ± 0.05 cm. CONCLUSIONS: Through the use of this measurement, we aim to avoid the pitfalls of previous techniques by providing a widely applicable clinical tool based on landmarks easily found on any patient.

Divided zygoma in Holocene human populations from Northern China.

OBJECTIVES: Divided zygoma (DZ) occurs in contemporaneous human populations, with the highest incidences in people from East Asia and Southern Africa. The present study examines the prevalence and variation of this condition in the Holocene populations of Northern China for the first time. METHODS: In this study, 1145 skulls from various human populations living in Northern China from the Neolithic Age to recent dynasties (5000-300 years BP) were examined. Specifically, cranial measurements and a CT scan were conducted to quantify craniofacial morphology. RESULTS: Fifteen skulls were identified with DZ, revealing an overall prevalence of 1.3% in the collection, while it was determined to be higher in North Asian and Northeast Asian regional groups. In skulls with unilateral DZ, the superior division of the zygoma was generally slender, while the inferior division of the zygoma was more robust. In skulls with bilateral DZ, the maxillae were generally more laterally extended. Moreover, unilateral DZ skulls displayed differences in cortical bone thickness between two sides of the facial skeleton. DISCUSSION: In context, the distribution pattern within these data points toward a greater prevalence of the DZ phenotype in North and Northeast Asian regional groups, suggesting a hypothesis that the DZ trait is more frequent in populations characterized by flat and broad faces. Accordingly, further studies into the DZ condition will deepen our understanding of developments in plasticity, variation, and recent evolution of the human cranium.

Correlation Between Soft and Hard Tissue Changes in the Zygomaticomaxillary Region After Bone Contouring Surgery for Fibrous Dysplasia-A Preliminary Study.

PURPOSE: The purpose of the present study was to determine the correlation between the soft and hard tissue changes in the zygomaticomaxillary region after facial bone contouring surgery for patients with craniofacial fibrous dysplasia (FD). MATERIALS AND METHODS: The present study was a retrospective case series that reviewed the cases of 13 patients with craniofacial FD in the zygomaticomaxillary region who had undergone navigation-guided facial bone contouring surgery from January 2013 to October 2017. Pre- and postoperative computed tomography (>3 months) were collected. The pre- and postoperative soft and hard tissues were placed in the same spatial coordinate system using multipoint registration to measure the distances between the corresponding pre- and postoperative points of the soft and hard tissues. The outcome variable was the corresponding soft tissue change. The correlation between the hard and soft tissue changes was obtained using correlation analysis with SPSS software (IBM Corp, Armonk, NY). The linear regression equation of the soft and hard tissue changes was used to predict the corresponding soft tissue changes. RESULTS: The Pearson correlation coefficient of the zygomatic region was 0.954 (P < .001) and the coefficient for the maxillary region was 0.758 (P < .001). The linear regression index (R2) for the zygomatic and maxillary regions was 0.910 (P < .001) and 0.575 (P < .001), respectively. The ß value of the linear regression equation for the zygomatic and maxillary regions was 0.815 (P < .001) and 0.52 (P < .001), respectively. CONCLUSIONS: The soft and hard tissue changes were highly correlated in both the zygomatic area and the maxillary area, and the variance of the maxillary area was slightly greater than that in the zygomatic area. This implied that the change of 1 mm of bone tissue along the tangent direction of the bone contour will cause a change of 0.815 mm in the soft tissue in the zygomatic region and 0.52 mm in soft tissue in the maxillary region.

The Subtemporal Approach to the Lateral Midbrain with and without Zygomatic Osteotomy: An Anatomical Study.

The subtemporal approach provides a narrow operative corridor to the crus cerebrum and adjacent structures of the crural, interpeduncular, and ambient cistern. Addition of a zygomatic osteotomy widens this narrow corridor and spares retraction of the temporal lobe. We investigate and compare the morphometric parameters of the subtemporal approach with versus without zygomatic osteotomy. On each side of four cadaveric heads, a temporal craniotomy was performed to gain access to the crus cerebrum and adjacent subarachnoid cisterns using a subtemporal approach. Operative corridor width and corridor working angle were measured with and without brain retraction on each specimen side. Next, a zygomatic osteotomy was performed followed by full downward reflection of the temporalis muscle and further drilling of the squamous part of the temporal bone. Lastly, operative corridor width and corridor working angle were measured again for comparison. The subtemporal operating corridor was (mean/SD): 5.8/2.6 mm without retraction, 11.4/4.3 mm with retraction, and 13.5/6.5° working angle. After addition of a zygomatic osteotomy, the operative corridor was 8/9.2/4.3 mm without retraction, 14.7/4.5 mm with retraction, 31.8/3.1° working angle. Zygomatic osteotomy significantly increased the operative corridor working angle of the subtemporal approach. Furthermore, we demonstrate a direct approach into the interpeduncular fossa. Clin. Anat. 32:710-714, 2019. © 2019 Wiley Periodicals, Inc.

Using the zygomatic arch as a reference line for clinical applications and anthropological studies.

PURPOSE: The Frankfurt line is the most frequently and widely used reference line in cephalometric analysis, but has shortcomings including the difficulty of landmark identification. This study investigated using the superior border of the zygomatic arch as a new external bony landmark, including measuring the angle between the new reference line and the Frankfurt line. METHODS: Facial computed tomography scans were obtained from 170 patients (100 males and 70 females) hospitalized at Konkuk University Chungju Hospital. After three-dimensional reconstruction, the locations of the porion and the inferior orbital rim and the superior border of the zygomatic arch were identified twice by two observers using software. A horizontal line parallel to the superior border of the zygomatic arch was established. The angle between the Frankfurt line and new reference line was then measured on each side. RESULTS: There was no significant intraobserver or interobserver bias. The angle between the Frankfurt line and the superior border of the zygomatic arch was 4.5° ± 2.5° (mean ± SD), and it was somewhat larger in females than males, but the difference was not statistically significant. CONCLUSIONS: This study demonstrated the good reproducibility of the location of the superior border of the zygomatic arch and found that the angle between the new reference line and the Frankfurt line is relatively constant. The superior border of the zygomatic arch therefore has potential as an alternative reference line to the Frankfurt line in specific clinical applications and anthropological studies, since it is a more accessible bony landmark on the external skull.

Correlation of anterior overbite with root position and buccal bone thickness of maxillary anterior teeth: a CBCT study.

PURPOSE: To investigate the correlation of anterior overbite with the sagittal root position (SRP) and buccal bone thickness (BBT) of the maxillary anterior teeth. METHODS: Cone-beam computed tomography (CBCT) data of southern Chinese patients who underwent CBCT examinations between November 2016 and December 2016 were collected. The anterior overbite was the predictor variable while the SRP and the BBT at 4 mm apical to the cementoenamel junction (CEJ-4) and midpoint of the root of the maxillary anterior teeth were set as the primary and secondary outcome variables, respectively. All measurements were done by two calibrated examiners. Correlations between variables were analyzed by the Spearman's correlation coefficient. The significance level was set at P < 0.05. RESULTS: CBCT data of 146 patients (65 men and 81 women) with a mean age of 44.2 ± 13.4 years were analyzed, and of the 876 maxillary anterior teeth evaluated, 9.8% were presented with deep overbites. Most of roots of the anterior teeth (94.9%) were positioned against the buccal cortical plate, of which, in 63.8% of them the apex was not covered by bone along the long axis of the tooth. The mean BBT at CEJ-4 was 0.89 mm at the central incisor, 0.85 mm at the lateral incisor and 0.84 mm at the canine. The overbite was positively correlated with SRP Class I subtypes and the BBT at CEJ-4 (P < 0.05). CONCLUSION: Deep overbite was more frequently accompanied by bone fenestration in the anterior maxillary areas.

Correlation between buccal and alveolar bone widths at the central incisors according to cone-beam-computed tomography.

OBJECTIVE: The aim of this study is to assess whether there is a correlation between buccal bone thickness and mean alveolar bone thickness around the central teeth using CBCT images. MATERIALS AND METHODS: Three points were selected at 3, 6 and 9 mm from the cemento-enamel junction, respectively, perpendicular to the long axis of the measuring points made to determine the width of the alveolar bone ridge. The arithmetic mean of the length measurements was taken as the average alveolar bone thickness. To determine the average buccal alveolar bone thickness, the buccal bone length was measured perpendicular to the long axis of the tooth from these 3 points, and the average of the measurements was taken from these 3 points. RESULTS: The mean coronal, mid-root, and apical third root widths of the maxillary, left central incisors were 7.72±0.60, 8.64 ± 0.93, and 9.23±1.45 mm, respectively and the mean widths of the buccal alveolar bone at the coronal, mid-root, and apical third root positions of the left central incisor were 1.18±0.39, 1.15±0.44, and 1.06±0.50 mm, respectively. The Spearman correlation coefficients were 0.194 and 0.191 for the left and right central incisors, respectively. CONCLUSIONS: There was no statistically significant difference between the alveolar bone thickness averages of the left and right central incisors, but the alveolar bone thickness was found to be thicker in males than females. Although the mean of alveolar and buccal bone thicknesses was positively correlated the statistical analysis demonstrated the correlation between the mean of alveolar and buccal bone thicknesses is not significant.