Morphological differences between the first and second maxillary premolar crowns: A three-dimensional surface homologous modeling analysis.

OBJECTIVES: The current study used a three-dimensional (3D) surface homologous modeling to analyze the structure of maxillary first premolar (P1) and second premolar (P2) crowns, to identify any morphological differences between them, particularly in their cuspal structures. METHODS: The study sample comprised 27 male elementary and junior high school students from Chiba Prefecture, Japan. Plaster casts were collected and the 3D coordinates were used to measure the crown structures. Thereafter, principal component (PC) analysis was carried out using the 3D coordinates of the homologous models, containing 4498 anatomical data points, including 9 landmarks. RESULTS: The findings indicated that P1 was significantly larger than P2, despite both teeth exhibiting similar intercuspal distances. The homologous model analysis revealed that 61.5 % of the total variance could be explained up to the fourth PC. Overall size and shape in the mesiodistal and buccolingual directions were estimated using PC1 and PC2, respectively. Both components highlighted a shape factor, indicating that the buccal cusp was more well-developed than the lingual cusp in P1 compared to P2. CONCLUSIONS: The variations in the size of the mesial and distal premolar teeth and the relationships between the cusps in the completed tooth crowns can be explained using molecular biology developmental models.

Sexual dimorphism in the three-dimensional detailed crown structure of maxillary first premolars.

OBJECTIVES: Maxillary first premolars have a unique shape because of their curvature features, positional relationship of the cusps, and most prominent points, making them different from other teeth. This study aimed to quantitatively analyze the detailed three-dimensional morphometric structure of maxillary first premolars and sexual dimorphism. METHODS: The study participants were 60 elementary and junior high school students (30 boys and 30 girls) in Japan. The distance between landmarks was measured using the three-dimensional coordinates of plaster casts, and the data collected was statistically analyzed. RESULTS: Sexual dimorphism was greater in the lingual cusp, showing greater variation in size than the buccal cusp. Boys exhibited significantly larger relative distances in the mesiodistal and buccolingual directions than girls; particularly, regarding mesiodistal diameter of the central groove, mesial slope of the buccal cusp, and distal slope of the lingual cusp. These results may be due to a slight difference in the timing of secondary enamel knots between boys and girls during the developmental stage, which was reflected in the sexual dimorphism of the completed teeth. Curvature features, cusp positions, and most prominent points were considered individual traits because they were not interrelated. CONCLUSIONS: Subtle differences during the developmental stage may lead to sexual dimorphism of the completed crown. Furthermore, the morphological characteristics of the maxillary first premolars may be related to their location in the dental arch.

The biological significance of tooth identification based on developmental and evolutional viewpoints.

BACKGROUND: Tooth identification is important not only for anatomists and anthropologists but also for dental practitioners and dental students studying dental anatomy courses. This review paper provides an overview of the significance of tooth identification focusing on the morphological and developmental background. HIGHLIGHT: The process of tooth identification comprises five steps of distinction: (1) between deciduous and permanent teeth; (2) between tooth classes; (3) between maxillary and mandibular teeth; (4) within the same tooth class; and (5) between the left and right sides of a tooth. According to Mühlreiter's features, the mesial half is more developed than the distal half, and the curvature feature is associated with the configuration of the dental arch. Each step of tooth identification refers to effective traits and characteristics. The possibility that systemic conditions affect dental morphology should be considered. Tooth identification is occasionally difficult owing to individual variations (size and shape, supernumerary tubercles, root fusion) and sex-based differences. A tooth type error within the same class is the most frequent error in tooth identification, followed by a left or right side error. CONCLUSION: To understand tooth identification, it is necessary to have comprehensive knowledge of dental morphology. A broad education with regard to tooth evolution and comparative odontology, as well as a thorough understanding of the morphology and function of teeth, which play a crucial role in sustaining life as organs of mastication, is essential.

Mandibular premolar identification system based on a deep learning model.

OBJECTIVES: For constructing an isolated tooth identification system using deep learning, Igarashi et al. (2021) began constructing a learning model as basic research to identify the left and right mandibular first and second premolars. These teeth were chosen for analysis because they are difficult to identify from one another. The learning method itself was proven appropriate but presented low accuracy. Therefore, further improvement in the learning data should increase the accuracy of the model. The study objectives were to modify the learning data and increase the learning model accuracy for enabling the identification of isolated lower premolars. METHODS: Static images of the occlusal surface of the premolars made from the dental plaster casts of dental students were used as the training, validation, and test data. A convolutional neural network with 32 hidden layers, AlexNet, convolutional architecture for fast feature embedding, and stochastic gradient descent was used to construct four learning models. RESULTS: The accuracy of the identification model increased using static images of the occlusal surface of the teeth with the adjacent teeth deleted as the training and validation data; however, a learning model that could perfectly identify the teeth could not be realized. CONCLUSIONS: Static images of the occlusal surface of the teeth with the adjacent teeth deleted should be used as both training and validation data. The ratio of the numbers of training, validation, and test data should be optimized.

Morphological Observations of the Bony Canal Structure of the Eustachian Tube in Elderly Human Cadavers With Cone-Beam Computed Tomography and Principal Component Analysis.

OBJECTIVE: Anatomical information regarding the eustachian tube (ET) is limited; therefore, more detailed analytical data on ET structure is needed when planning surgical treatments involving the temporal bone. METHODS: We examined the bony structure of the middle ear and ET in 30 Japanese donor cadavers (71-97 years old at the time of death) both macroscopically and with cone-beam computed tomography. Each ET was reconstructed in 3 dimensions, and the structure and correlations of ET element measurements, identified via principal component analysis, were analyzed. RESULTS: Delineation between bony and cartilaginous zones appeared unclear, and the space between ET cartilage and the carotid canal was narrow. We observed stenosis of the ET bony canal in 43.3% of the specimens (n = 30). In 50% of the specimens, the position of the ET bony canal was depressed at the pharyngeal orifice of the auditory side of the tube, and the middle region was a roundish structure. The lateral and central regions of the bony canal were related to the ET bony canal structure. CONCLUSION: The close proximity of the ET bony canal to the carotid canal is an important anatomical and morphological finding. Pre-surgical 3D modeling of the middle ear structure, or at a minimum, of the central region of the middle ear canal, may provide useful information for planning procedures that involve the ET.

Solubilization of Progesterone and its Derivatives into Gemini Surfactant Solutions.

The solubilization of poorly water-soluble progesterone derivatives into micelles of a gemini surfactant was investigated in an aqueous medium. The aqueous solubility at different temperatures was determined spectroscopically using an ultraviolet visible light spectrophotometer. Thermodynamic parameters for the solubilization were calculated under the basis of the solubility change against temperature. The solubility of progesterone was quite low and remained constant below the critical micelle concentration (cmc) of the surfactant. On the other hand, the solubility increased considerably with increasing surfactant concentration above the cmc. It was suggested that the solubilizates were located in the vicinity of polar regions of micelles.

Genetic contribution to palatal morphology variation using three-dimensional analysis in Australian twins.

OBJECTIVE: This study aimed to provide insight into the relative contributions of genetic and environmental factors to palatal morphology variation in a cohort of Australian twins. METHODS: Healthy Australian twins, aged 12-15 years (45 monozygotic, 46 same sex dizygotic, and 32 opposite-sex dizygotic) were included in the study groups. A scanner was used to obtain three-dimensional data of the maxillary arch. Palatal depth was defined by a line to the deepest point measured from the reference plane at the mid-point of the inter-pre-molar or inter-molar line. This line was then divided into 10 equal sections in order to created 10 different depths for each palatal width. Each palatal width was divided into anterior and posterior areas. Univariate genetic analysis, using the OpenMx structural equation modelling package in R, was carried out on the quantitative data using the normal assumptions of a twin model. RESULTS: Heritability estimates for anterior palatal width ranged from 0.75 to 0.80, and from 0.78 to 0.86 for posterior palatal width. Estimates for anterior and posterior palatal depth were 0.72 and 0.86, respectively. CONCLUSIONS: Palatal morphology tends to have a moderate to relatively high genetic contribution overall. Palate height has a higher genetic contribution posteriorly than anteriorly. The width of the deep palate is under marginally less stringent genetic regulation than the width of the shallow palate.

Morphological variation in the anterior cranial fossa.

The anterior cranial fossa is an important anatomical landmark in clinical orthodontics consisting of the frontal, ethmoid, and sphenoid bones. The relationships between these bones remain poorly understood. The purposes of the present study were to describe the morphological relationships among the three bones and to discuss the factors contributing to individual variations in adult skulls based on postnatal development. Skulls of 100 Indian adults and 18 Japanese juveniles were observed both macroscopically and using computed tomography images in the median sagittal plane. Three types of relationship were seen among the three bones in adult skulls: (a) a triangular border between ethmoid and sphenoid bones (ethmoid spine), (b) a straight or concave border between ethmoid and sphenoid bones, and (c) frontal bone lying between the ethmoid and sphenoid bones. In the juvenile skull, structures corresponding to those in adults were observed. These three bones comprise the anterior cranial base, each with differing developmental processes, and slight differences in these processes seem to be reflected in the morphological variations seen among adults.

Protuberance or fossa on the lateral surface of the mandible in primates.

In order to clarify the morphological characteristics and function of the protuberance and/or fossa on the lateral surface of the mandible, we examined 778 mandibles of 9 genera, 19 species of non-human primates. Both protuberance and fossa were found in Macaca, Chlorocebus, and Cercocebus at frequencies ranging from 0% to 60%. The protuberance was composed of compact bone and was similar to the mandibular torus in humans. A well-developed protuberance extended from the fourth premolar to third molar region, and was situated at the central part of the mandibular body, or continued on the oblique line. Sometimes the protuberance localized on the mandibular base. A deep and large fossa was found in all individuals of Papio, Theropithecus, and Mandrillus, and the bone width was thin in the center of the fossa. The fossa extended from the third premolar to the second molar region, and the deepest area was the first molar region. In Macaca, Chlorocebus, and Cercocebus, the curvature of the external table of the mandible created a fossa. In Colobus, and Hylobates, the external surface of the mandible looked concave because of the thickened mandibular base. These concavo-convex structures have some biological functions and represent an adaptive change for mastication.

Endoscopic submucosal dissection is an effective and safe therapy for early gastric neoplasms: a multicenter feasible study.

BACKGROUND AND AIM: The technique of endoscopic submucosal dissection (ESD) was introduced to obtain en bloc specimens of large early gastrointestinal neoplasms. The drawback of ESD is its technical difficulty and, consequently, its higher rate of complication. In this multicenter study, we investigated the therapeutic outcomes of ESD in consecutive patients. METHODS: From January 2002 to December 2008, 485 early gastric neoplasms in 418 patients were consecutively treated by using ESD procedure performed by 6 endoscopists in 4 institutions in Tokyo. Demorgraphics, tumor location, therapeutic outcomes, and complication rates were analyzed. RESULTS: The rates of en bloc resection, complete en bloc resection, submucosal invasion, and piecemeal resection were 93.6%, 85.4%, 10.9%, and 5.4%, respectively. In multivariate analysis, the en bloc resection rate was independently lower in lesions in upper portion than in lower portion (P<0.01), lower in larger lesions (>30 mm, P<0.05; 20 to 30 mm, P<0.05), and lower in lesions with a scar (P<0.01). Delayed bleeding occurrence was independently high in larger lesions (>30 mm, P<0.01; 20 to 29 mm, P<0.01) than in small lesions (<20 mm). Institution and endoscopists were not risk factors of en bloc resection and complications CONCLUSIONS: ESD is an effective and safe therapy in the management of early gastric neoplasms when performed by well-trained endoscopists. Endoscopists should recognize the difficulty to perform ESD for en bloc resection of upper lesion, and the risk of delayed bleeding in cases of lesions >2 cm in size.

Surveillance of small intestinal abnormalities in patients with hepatocellular carcinoma: a prospective capsule endoscopy study.

BACKGROUND: Patients with hepatocellular carcinoma (HCC) sometimes suffer from obscure gastrointestinal bleeding. Portal hypertension (PH), common in cirrhosis, induces esophagogastric varices. Because of the location, PH also may influence mucosal abnormalities in the small intestine. The objective of this study is to estimate the prevalence of small intestinal mucosal abnormalities in HCC patients using capsule endoscopy (CE). PATIENTS AND METHODS: We prospectively conducted CE in HCC patients, and analyzed the findings in relation to hepatic function, the number and size of HCC tumor and findings obtained by conventional endoscopy. RESULTS: Thirty-six patients (aged 66.7 ± 7.5 years, 29 men) underwent CE. Abnormal findings in the small bowel were found in 16 patients (44%), angioectasias in eight patients (22%), erosions in five (14%), varices in four (11%), polyps in four (11%), and submucosal tumor in one (3%). The patients with angioectasia had a larger spleen index than the no abnormal lesions group (85.4 ± 15.8 vs 59.0 ± 24.4, P = 0.02). The former group had been more frequently treated for esophageal varices endoscopically (62% vs 15%, P = 0.02). Large HCC nodules seemed more common in the patients with angioectasia than subjects without abnormal lesions (38% vs 5%, P = 0.06). Small intestinal varices also seemed to have a positive association with large HCC. During the follow up after CE, one patient with small intestinal polyps suffered from obscure gastrointestinal bleeding. CONCLUSIONS: CE revealed that HCC patients frequently have small intestinal mucosal lesions. In particular, small intestinal angioectasia, which may cause obscure gastrointestinal bleeding, seems to be associated with portal hypertension.

The evolutionary aspects of aquaporin family.

Aquaporins (AQPs) were originally identified as channels facilitating water transport across the plasma membrane. They have a pair of highly conserved signature sequences, asparagine-proline-alanine (NPA) boxes, to form a pore. However, some have little conserved amino acid sequences around the NPA boxes unclassifiable to two previous AQP subfamilies, classical AQPs and aquaglyceroporins. These will be called unorthodox AQPs in this review. Interestingly, these unorthodox AQPs have a highly conserved cysteine residue downstream of the second NPA box. AQPs also have a diversity of functions: some related to water transport such as fluid secretion, fluid absorption, and cell volume regulation, and the others not directly related to water transport such as cell adhesion, cell migration, cell proliferation, and cell differentiation. Some AQPs even permeate nonionic small molecules, ions, metals, and possibly gasses. AQP gene disruption studies have revealed their physiological roles: water transport in the kidney and exocrine glands, glycerol transport in fat metabolism and in skin moisture, and nutrient uptakes in plants. Furthermore, AQPs are also present at intracellular organelles, including tonoplasts, mitochondria, and the endoplasmic reticulum. This review focuses on the evolutionary aspects of AQPs from bacteria to humans in view of the structural and functional diversities of AQPs.

Observation of maxillary sinus septa and bony bridges using dry skulls between Hellman's dental age of IA and IIIC.

Maxillary sinus septa and bony bridges were observed using dry skulls in childhood, classified based on Hellman's dental age, to clarify maxillary sinus septum formation. Eighty-eight maxillary sinuses of 44 dry skulls and a cone-beam computed tomography (CBCT) unit were used. The locations of the septum, defined as a pointed bony structure originating from the inferior wall, and bony bridge, defined as a bony structure between the maxillary sinus wall and dental germ, were antero-posteriorly recorded, and the superoinferior distance, distance from the bony palate, and angle to the median palatine suture were measured. The rate of septum presence in the maxillary sinus was high (41.7%) in IIIC, and the septa were located in the deciduous molars, premolars, and molars. Also, all bony bridges were related to the median maxillary sinus wall, and the rate of the maxillary sinus showing a bony bridge was high in IIA and IIIA. Septum presence in the maxillary sinus was observed in IIA, IIC, IIIA, IIIB, and IIIC of Hellman's dental age. Also, bony bridges were observed in IC, IIA, IIC, IIIA, IIIB, and IIIC of Hellman's dental age.

[Successful treatment of a gastrointestinal stromal tumor with liver metastases in a case that tolerated imatinib administration, by radiofrequency ablation using contrast-enhanced ultrasonography].

We report a case of gastrointestinal stromal tumor (GIST) with liver metastases which was undetectable by B-mode ultrasonography, effectively treated by radiofrequency ablation using contrast-enhanced ultrasonography US. A 43-year-old woman was admitted for the treatment of 6 lesions up to 4cm in diameter, which had emerged from necrotic sites within the liver after imatinib treatment. The recurrent lesions were not detected on B-mode US, and it was difficult to perform radiofrequency ablation (RFA) treatment. Using a contrast-enhanced agent (sonazoid), the recurrent lesions were detected and treated by RFA. RFA is considered to be an effective treatment for GIST with liver metastases that tolerate imatinib administration.

Comparison between cone-beam and multislice computed tomography depicting mandibular neurovascular canal structures.

OBJECTIVE: The most common diagnostic imaging modalities for cross-sectional imaging in dental implant planning are currently cone-beam computed tomography (CBCT) and multislice CT (MSCT). However, clinical differences between CBCT and MSCT in this task have not been fully clarified. In this investigation, the detection of fine anatomical structures in the mandible was assessed and compared between CBCT and MSCT images. STUDY DESIGN: The sample consisted of 28 patients who had undergone CBCT and MSCT. The bifid mandibular canal in the mandibular ramus, accessory mental and buccal foramina, and median and lateral lingual bony canals were observed in 2-D images, and the findings were compared between CBCT and MSCT. RESULTS: Four of 19 canals observed in CBCT were not observed in MSCT images. Three accessory mental foramina in 2 patients and 28 lateral lingual bony canals in 18 patients were observed consistently using the two methods. CONCLUSION: Depiction of fine anatomic features in the mandible associated with neurovascular structures is consistent between CBCT and MSCT images.

Observation of lateral mandibular protuberance in Taiwan macaque (Macaca cyclopis) using computed tomography imaging.

Morphological characteristics of the protuberance on the external surface of the mandible in Taiwan macaque (Macaca cyclopis) was investigated using cone-beam computed tomography. We observed 49 skulls of M. cyclopis. Of 7 skulls with deciduous and mixed dentitions in which M2s did not erupt, the protuberance was not found. Of the 13 skulls with mixed and permanent dentitions in which M2s had erupted, a palpable protuberance was found in one specimen. Of the 29 samples in which M3s had erupted completely, a perceptible protuberance was found in 2 samples, and palpable protuberance was found in 8 samples. Thus, the protuberance was found in 10 samples of the 29 samples with complete dentitions (34.5%), and the emergence of the protuberance may have been related to mandibular growth. In the case of the well-developed protuberance, it extended from the P4 to M3 region but did not extend to the mental foramina. By using cone-beam computed tomography, it was determined that the protuberance was composed of cortical bone and was the thickest in M2 region. Since the protuberance consisted of homogeneous cortical bone, it was considered to be the result of normal bone growth similar to the mandibular torus in humans.

Assessment of maxillary sinus septa using cone-beam computed tomography: etiological consideration.

BACKGROUND: Septum presence in the maxillary sinus complicates sinus floor elevation surgery, and so it is important that septa are accurately diagnosed on preoperative imaging. PURPOSE: Septa were observed regarding their relationship with the bony palate using cone-beam computed tomography (CT). MATERIALS AND METHODS: Thirty maxillary sinuses with dentate jaws of 15 dry skulls and a cone-beam CT unit were used. A septum was defined as a pointed bone structure, and an exostosis was defined as a rounded bone structure. The occurrence and locations of maxillary sinus septa and exostoses of more than 2 mm in height were evaluated. Also, angles between the direction of septum and median palatine suture were measured on axial images. RESULTS: Twelve septa of 11 maxillary sinuses (37%) and nine exostoses of nine maxillary sinuses (30%) were observed. Also, 42% of septa and 67% of exostoses were antero-posteriorly aligned according to the transverse palatine suture. Moreover, the mean septum angle was 57.9 degrees in the anterior maxillary sinus region, and 101.8 degrees in the transverse palatine suture region, and significant differences were noted between them. CONCLUSION: Maxillary sinus septa and exostoses could be clarified regarding their relationship with the bony palate using cone-beam CT.

The role of a group III AQP, AQP11 in intracellular organelle homeostasis.

AQP11 is a member of a new aquaporin subfamily which includes many aquaporin homologs with low amino acid identities, around 20% of previously identified AQPs. Although these AQPs have unusual NPA sequences, these AQPs have a completely conserved and functionally indispensable cysteine residue downstream of the second NPA box, suggesting that they belong to a specific AQP subfamily, which we propose to name the group III AQPs. On the other hand, the NPA boxes are highly conserved in previous AQP subfamilies: the group I AQPs, original water-selective aquaporin family and the group II AQPs, aquaglyceroporin family. Currently the roles of the group III AQPs are only known with AQP11 as the disruption of intracellularly located AQP11 in mice produced huge vacuoles in the proximal tubule leading to fatal polycystic kidneys at one month old. This review focused on the classification of AQPs based on primary structures to obtain insights into the function and the role of AQPs. With the accumulation of new AQP-like sequences through genome projects, this classification will be useful to predict their functions as each group may have specific characteristics in its function, distribution and regulation.

Aquaporin water channels in mammals.

Water channels, aquaporins (AQPs), are a family of small integral plasma membrane proteins that primarily transport water across the plasma membrane. There are 13 members (AQP0-12) in humans. This number is final as the human genome project has been completed. They are divided into three subgroups based on the primary sequences: water selective AQPs (AQP0, 1, 2, 4, 5, 6, 8), aquaglyceroporins (AQP3, 7, 9, 10), and superaquaporins (AQP11, 12). Since no specific inhibitors are yet available, functional roles of AQPs are suggested by AQP null mice and humans. Abnormal water metabolism was shown with AQP1, 2, 3, 4, 5 null mice, especially with AQP2 null mice: fatal at neonate due to diabetes insipidus. Abnormal glycerol transport was shown with AQP3, 7, 9 null mice, although they appeared normal. AQP0 null mice suffer from cataracts, although the pathogenesis is not clear. Unexpectedly, AQP11 null mice die from uremia as a result of polycystic kidneys. Interestingly, AQP6, 8, 10, 12 null mice are almost normal. AQP null humans have been reported with AQP0, 1, 2, 3, 7: only AQP2 null humans show an outstanding phenotype, diabetes insipidus. This review summarizes the current knowledge on all mammalian AQPs and hopefully will stimulate future research in both clinical and basic fields.

Preservation of papillary relaxation after endoscopic papillary balloon dilation.

BACKGROUND/AIMS: Endoscopic papillary balloon dilation has been accepted as a less hazardous alternative to endoscopic sphincterotomy for removal of bile duct stones in patients with impaired hemostasis. Several manometric studies have suggested that endoscopic papillary balloon dilation can be expected to preserve papillary function. However, the aspect of the preservation of postprandial relaxation has not been addressed. METHODOLOGY: Seven, 7 and 6 patients underwent fatty-meal magnetic resonance cholangiography before endoscopic papillary balloon dilation for the treatment of common bile duct stones, and then 12 and 24 months after the procedure. Seven patients were employed as controls. Magnetic resonance cholangiography images were obtained on a 1.5-Tesla scanner (Signa Horizon, GE Medical Systems, Milwaukee, WI) with a phased-array torso coil. After an overnight fast, magnetic resonance cholangiography was performed before and after fatty-meal ingestion. RESULTS: No patients showed significant postprandial increase of the bile duct diameter except one patient with stone impaction during the examination. CONCLUSIONS: Endoscopic papillary balloon dilation may preserve the papillary function of postprandial relaxation.