Abnormality in the Morphogenesis of Tooth Development and Relationship with Orthodontic Deformities and Treatment Approaches

In the process of odontogenesis, a disturbance in the formation of the epithelium and mesenchyme can be observed and this can be manifested by atypical forms of dental development. Such biological phenomena with altered morphology are as follows: dens invaginatus (DI), dens evaginatus (DE), talon cusps, and double teeth (DT) or connate teeth (fusion and gemination). Patients with orthodontic anomalies who also exhibit teeth with morphogenetic disorders are presented in this article. Dens evaginatus and talon cusps pose orthodontic challenges in the treatment finishing phase. These reduce the possibility of achieving maximum intercuspidation between the lower and upper front teeth as well as poor incisor guidance. Other orthodontic challenges are as follows: the risk of occlusal trauma and periodontal loading of the antagonists and the possibility of accessory cusps to play the role of the inclined plane and lead to deviations in the closure of the lower jaw. The fused teeth can cause aesthetic and occlusal disturbances in the anterior segment. Furthermore, double teeth can lead to ectopic eruption or noneruption of adjacent teeth due to their increased crown size as is the case with one of the presented patients. This is because a double tooth occupies more space in the dental arch. If not diagnosed early, impaction of the adjacent tooth, violation of the occlusal ratios (Bolton/anterior), and exacerbation of the orthodontic deformity can be observed. The modern CBCT imaging is the best diagnostic method for identifying problems related to tooth positions or tooth germs.

A Rare Tooth Anomaly (Double Teeth) in Deciduous Teeth: A Case Report

Introduction: The Size and shape of the teeth are genetic characteristics. Anomaly in tooth size and shape is due to disturbances in a sequence of morph differentiation and his to differentiation in tooth bud formation periods and is more common in permanent dentition than deciduous teeth. The most common tooth size discrepancy is in the upper lateral incisor and upper and lowers 2nd premolar teeth. About 5% of malocclusions are due to tooth size discrepancy. For having the best occlusion, we must have the appropriate size and shape of teeth. As there is a relation between deciduous and permanent teeth, proper evaluation and timely intervention are essential for achieving a good occlusion in anterior and posterior segments of permanent teeth. Thus we need interceptive orthodontic in mixed dentition period with a good treatment plan for removing the malformed tooth at the proper time and appliance therapy for eruption guidance of other teeth. Case Report: A rare tooth anomaly (double teeth) in deciduous teeth: The case reported here is a 9- years old boy with a delayed eruption of the right lower permanent lateral incisor and gemination of lower right deciduous canine and crowded upper incisors that refer to the orthodontic department of dental school of Ahvaz Jundishapur University of Medical Sciences on7th October of 2020. Conclusion: After creating patient’s file, the further steps of molding from the patient and gathering all diagnostic records such as panoramic radiography, intraoral photography was carried out and ordered to remove the malformed baby tooth afterward. In the next stage, on the patient’s treatment, we installed a strap onto the patient’s first permanent molars, remolded them, then created a lingual arch to maintain the vegetative space in the lower permanent canine and prevent its collapse, and increased the patient’s overbite.

A Geminated Mandibular Second Molar—A Case Report

Fusion and gemination are not entirely uncommon dental anomalies that may also be named ‘double teeth’. This is due to their unusual presentation in a twin-like fashion. Teeth with these irregularities may appear clinically similar, presenting as large and bulbous in shape with unusual anatomy and fissure patterns. The exact aetiology of these anomalies is uncertain, but many potential local or systemic disturbances during the morphodifferentiation stage of odontogenesis have been considered. Gemination occurs rarely in the permanent dentition and even less frequently in the posterior region of the oral cavity. This report presents a case of a geminated mandibular second molar and discusses the importance of early recognition and diagnosis of such teeth so that adequate preventative care and treatment can be provided.

Design of double teeth metallic card clothing for the high-efficiency carding process by computational fluid dynamics

The design of metallic card clothing, which is one of the most important devices in the textile industry, has always been based on operational experience. With the development of types of fibers and the requirements for the quality of yarns, those principles concluded by engineers seem to be losing their efficiency. Recent research found that airflow played an important role in the card process, which means airflow should be carefully studied. Computational fluid dynamics (CFD) simulation greatly helps in the analysis of airflow because the gauge between carding elements is too narrow to put in any measuring device. In the present study, with the help of CFD simulation, the air around different carding clothing with varied tooth depth was analyzed. It was concluded that the carding efficiency improvement in card clothing with lower tooth depth may be related to more concentrated air velocity at the tooth tips. This resulted in more probabilities that fibers would get through the cylinder surface at the teeth tips, so that the fibers could be caught by flat-top needles more efficiently. With this assumption, a new generation of card clothing called “double teeth” containing two teeth in a single section has been invented. The new configuration design of card clothing was then applied in several spinning mills on an industrial scale for experiments. The results showed about a 30% improvement in production at the same quality level as conventional card clothing, which implied the usefulness of the newly applied principles related to airflow. Despite the difficulty in the study of the complex carding process, the new airflow analysis method has shown an optional and worthwhile way of thinking that could make a difference in future research in the textile industry.

First Scientific Record for Sivas Aquatic Systems Related to Alien Fish Species:Small-scaled Pacu; Piaractus mesopotamicus (Teleostei:Characidae)

In July 2017, three specimens of an alien fish species were caught by the amateur fishermen in Kızılırmak River at Sivas city center. One of the fish specimens was taken from the fishermen for ichthyologic examination. The morphological, metric (23 features) and meristic characters (13 features) of this specimen were determined. The alien fish is with ovoid shape and flattened laterally. Mouth is in a sub-ventral position. The tooth row is double. Teeth formula are 3,2 / 2,3 (at first row on maxil) and 2 / 2 (at second row on maxil), 3,3 / 3,4 (at first row on mandibul), 1,1 (at second row on mandibul). The number of rakers on the first gill arch is 33. The scale numbers in line lateral are 107 (on right side) and 103 (on left side). The number of branched rays of dorsal, anal, pectoral, and ventral fins are 14, 24, 14, and 7; respectively. As a result of the evaluation of morphological, metric and meristic characters, it was decided that the alien fish caught from Kızılırmak was Piaractus mesopotamicus (Holmberg, 1887) belonging to the Characidae family. This species is also called as the small-scaled pacu. P. mesopotamicus is not among to native fish fauna of Kızılırmak. It is a fish species which originated from South America and is a tropical freshwater fish. These alien fish specimens which were caught by the amateur fishermen, probably translocated from a hobbyist aquarium to this aquatic system. Both directly and indirectly, invasive fishes affect a wide range of native organisms from zooplankton to mammals across multiple levels of biological organizations ranging from the genome to the ecosystem. This study is the first scientific record for Sivas aquatic systems related to alien fish species.

A Clinical guide for the management of double teeth

Introduction : A double tooth can be a consequence of fusion or gemination and is characterized by a size increasing of the tooth and a morphological modification. This anomaly concerns the anterior teeth and occurs in temporary and permanent dentition. Double teeth causes various problems (easthetic, occlusal, endodontic, orthodontic, periodontal…). The management of clinical situations involving such abnormalities is often complex. Our aim is to present reasoned analysis based on a systematic review of therapeutic attitudes used in different clinical situations when the abnormal tooth is located at the anterior maxillary region. Material and methods : we carried out an electronic research via Pubmed and Sciencedirect to collect case reports published during the 20 recent years (1999-2020). We included 46 articles corresponding to 57 relevant case report that we classified based on Aguilo and coll. Classification (1999). Results : Partial crown and root section is indicated for type I. Stipping is indicated for type II. The management of type III is compromised by the canal morphology .Extraoral and entraoral hemisection are only incated for type IV. Coronoplasty is usually unavoidable. Endodontic, orthodontic or periodontal treatment can be indicated depending on the situation. The extraction is considered as a last resort, the space is restored by autotransplantation of a supernumarary tooth, a prosthetic restauration or an implant by the end of the craniofacial growth. Conclusion : The managment of double teeth is a therapeutic challenge, every case is different, a multidisciplinary approach is recommended.

Dynamic Characteristics of a Gear System with Double-Teeth Spalling Fault and Its Fault Feature Analysis

Tooth spalling is one of the most destructive surface failure models of the gear faults. Previous studies have mainly concentrated on the spalling damage of a single gear tooth, but the spalling distributed over double teeth, which usually occurs in practical engineering problems, is rarely reported. To remedy this deficiency, this paper constructs a new dynamical model of a gear system with double-teeth spalling fault and validates this model with various experimental tests. The dynamic characteristics of gear systems are obtained by considering the excitations induced by the number of spalling teeth, and the relative position of two faulty teeth. Moreover, to ensure the accuracy of dynamic model verification results and reduce the difficulty of fault feature analysis, a novel parameter-adaptive variational mode decomposition (VMD) method based on the ant lion optimization (ALO) is proposed to eliminate the background noise from the experimental signal. First, the ALO is used for the self-selection of the decomposition number K and the penalty factor â of the VMD. Then, the raw signal is decomposed into a set of Intrinsic Mode Functions (IMFs) by applying the ALO-VMD, and the IMFs whose effective weight kurtosis (EWK) is greater than zero are selected as the reconstructed signal. Combined with envelope spectrum analysis, the de-nosing ability of the proposed method is compared with that of the method known as particle swarm optimization-based variational mode decomposition (PSO-VMD), the fixed-parameter VMD, the empirical mode decomposition (EMD), and the local mean decomposition (LMD), respectively. The results indicate that the proposed dynamic model and background elimination method can provide a theoretical basis for spalling defect diagnosis of gear systems.

Clinical Orodental Anomalies in Taiwanese Children under Age Six: a Study Based on the 1995-1997 National Dental Survey

There are few published studies that report the prevalence of intraoral anomalies for young children. The purpose of this study was to investigate the prevalence and distribution of several congenital oral and paraoral anomalies in Taiwanese children under age six. Twenty-five cities and townships were randomly sampled in different areas of Taiwan using the stratified method. These cities and townships represent cross-sectional samples of geographic locations and socioeconomic levels. A total of 981 Taiwanese children under age six were examined with dental mirrors and explorers as part of the national dental survey. The results of this survey indicated an 11.31% prevalence of geographic tongue. This number is higher than that reported in studies previously performed in different countries. The occurrence of double teeth in primary dentition was found to be 2.14%. Ankyloglossia had a frequency of 1.22%, and primary talon cusp a frequency of 0.61%. Seven (0.71%) children exhibited fissured tongues. Thirteen (1.33%) cases of hypodontia were found. These values were different from those reported in several other countries, which may be attributed to differences in the ethnic and racial composition of the population studied.

Dynamic characteristics of a gear system with double-teeth spalling fault and its fault feature analysis

Gear fault diagnosis has been a vital technology to enhance the reliability and reduce the maintenance cost of gear systems. Tooth spalling is one of the most destructive surface failure models of the gear faults. Revealing the dynamic characteristics of a gear system with spalling fault and extracting the fault feature are the premise and basis for effective fault diagnosis. Previous studies have mainly concentrated on the spalling damage on a single gear tooth, but the spalling distributed over double teeth which usually occurs in practical engineering problems is rarely reported. To remedy this deficiency, this paper constructs a new dynamical model of a gear system with double-teeth spalling fault and validates this model with various experimental tests. The dynamic characteristics of gear systems are obtained by considering the excitations induced by the number of spalling teeth, the relative position of two faulty teeth, and the rotational speed. The method based on the Variational Mode Decomposition (VMD) and the Fast Kurtogram (FK) is proposed to extract the features of the double-teeth spalling fault. First, the raw signal is decomposed into a set of Intrinsic Mode Functions (IMFs) by applying the VMD, and the IMFs with strong correlation are summed as a reconstructed signal. The reconstructed signal is then filtered by an optimal band-pass filter based on the FK. Combined with envelope spectrum analysis, the feature extraction ability of the proposed method is compared with that of the original FK method and the method based on the Empirical Mode Decomposition and the FK, respectively. The results indicate that the proposed dynamic model and fault feature extraction method can provide a theoretical basis for spalling defect diagnosis of gear systems.