Small Teeth Research Articles

Skeletal remains of a Pleistocene modern human (Homo sapiens) from Sulawesi.

Major gaps remain in our knowledge of the early history of Homo sapiens in Wallacea. By 70–60 thousand years ago (ka), modern humans appear to have entered this distinct biogeographical zone between continental Asia and Australia. Despite this, there are relatively few Late Pleistocene sites attributed to our species in Wallacea. H. sapiens fossil remains are also rare. Previously, only one island in Wallacea (Alor in the southeastern part of the archipelago) had yielded skeletal evidence for pre-Holocene modern humans. Here we report on the first Pleistocene human skeletal remains from the largest Wallacean island, Sulawesi. The recovered elements consist of a nearly complete palate and frontal process of a modern human right maxilla excavated from Leang Bulu Bettue in the southwestern peninsula of the island. Dated by several different methods to between 25 and 16 ka, the maxilla belongs to an elderly individual of unknown age and sex, with small teeth (only M1 to M3 are extant) that exhibit severe occlusal wear and related dental pathologies. The dental wear pattern is unusual. This fragmentary specimen, though largely undiagnostic with regards to morphological affinity, provides the only direct insight we currently have from the fossil record into the identity of the Late Pleistocene people of Sulawesi.

Closing the Diastema and Teeth Spacing Using Direct Composite Resin Build-Up

Teeth spacing is commonly seen in the upper anterior teeth, which affect patient’s confidence due to disagreeable appearance. Teeth spacing may be due to low frenal attachment, which causes median diastema, small teeth with large maxilla, and bi-maxillary procline anterior teeth. Some patients will seek for options to close the space in order to get better aesthetic appearance. We reported this case of a 25-year-old woman who requested to close her median diastema between the teeth 11 and 21 as she felt that her smile was not nice and attractive. She also presented with mild spacing between her upper anterior teeth apart from the diastema. The treatment given to her was direct composite resin build-up, a minimal invasive treatment to close the spacing of between 1 to 2mm. The treatment has provided satisfaction to the patient. Being a conservative treatment, it can be reversible and repairable.

Time-varying meshing stiffness calculation of an internal gear pair with small tooth number difference by considering the multi-tooth contact problem

Time-varying meshing stiffness calculation of an internal gear pair with small tooth number difference by considering the multi-tooth contact problem

Signaling Modulation by miRNA-221-3p During Tooth Morphogenesis in Mice.

miRNAs are conserved short non-coding RNAs that play a role in the modulation of various biological pathways during tissue and organ morphogenesis. In this study, the function of miRNA-221-3p in tooth development, through its loss or gain in function was evaluated. A variety of techniques were utilized to evaluate detailed functional roles of miRNA-221-3p during odontogenesis, including in vitro tooth cultivation, renal capsule transplantation, in situ hybridization, real-time PCR, and immunohistochemistry. Two-day in vitro tooth cultivation at E13 identified altered cellular events, including cellular proliferation, apoptosis, adhesion, and cytoskeletal arrangement, with the loss and gain of miRNA-221-3p. qPCR analysis revealed alterations in gene expression of tooth-related signaling molecules, including β-catenin, Bmp2, Bmp4, Fgf4, Ptch1, and Shh, when inhibited with miRNA-221-3p and mimic. Also, the inhibition of miRNA-221-3p demonstrated increased mesenchymal localizations of pSMAD1/5/8, alongside decreased expression patterns of Shh and Fgf4 within inner enamel epithelium (IEE) in E13 + 2 days in vitro cultivated teeth. Moreover, 1-week renal transplantation of in vitro cultivated teeth had smaller tooth size with reduced enamel and dentin matrices, along with increased cellular proliferation and Shh expression along the Hertwig epithelial root sheath (HERS), within the inhibitor group. Similarly, in 3-week renal calcified teeth, the overexpression of miRNA-221-3p did not affect tooth phenotype, while the loss of function resulted in long and slender teeth with short mesiodistal length. This study provides evidence that a suitable level of miRNA-221-3p is required for the modulation of major signaling pathways, including Wnt, Bmp, and Shh, during tooth morphogenesis.

Identification of SOFT syndrome caused by a pathogenic homozygous splicing variant of POC1A: a case report

BackgroundPathogenic variants in POC1A led to SOFT syndrome and variant POC1A-related (vPOC1A) syndrome. SOFT syndrome is a rare primordial dwarfism condition characterized by short stature, onychodysplasia, facial dysmorphism and hypotrichosis.The main clinical differences between SOFT and vPOC1A syndrome include dyslipidemia with insulin resistance and acanthosis nigricans. To our knowledge, this is the first report of a SOFT syndrome patient diagnosed with a homozygous splicing variant, which could help to extend our understanding of the genotypic and phenotypic information of the disease.Case presentationWe reported a seven-year-old boy with SOFT syndrome. The patient presented symmetrical short stature and facial features, including prominent forehead, inverted triangular face, epicanthal fold, small teeth and enlarged ears. Laboratory tests displayed mild insulin resistance. Whole-exome sequencing (WES) led to the identification of a homozygous splicing variant (c.981+1G>A) in POC1A gene of the patient, which was inherited from his heterozygous parents confirmed by Sanger sequencing. Further transcriptional experiments of the splicing variant revealed aberrant percentage of exon 9 skipping transcripts.ConclusionsThis is the firstly reported case of a SOFT syndrome patient with a novel homozygous splicing variant and detailed delineation of the aberrant transcript in proband and carrier of the variant in Chinese. Our study enriched mutational spectrum of POC1A which could help in further genetic diagnosis and counselling of SOFT syndrome patients.

Schindleria parva, a new species of Schindler's fish (Teleostei: Schindleriidae: Schindleria) from Jeddah, Saudi Arabia, Red Sea.

Schindleria parva, a new species of the family Schindleriidae, is described from two specimens collected from the central Red Sea of Saudi Arabia. The new species is characterized by lack of pigmentation on the body, possession of an inconspicuous gas bladder and the presence of small teeth on the premaxillae. The holotype is a female of 11 mm standard length (SL) (11.9 mm total length) and the paratype is a male of 9 mm SL. Dorsal fin rays 10 (9) anal fin rays 9 (7). The body depth at pectoral-fin origin 5% (4%) of SL, depth at anal-fin origin 8% (7%) SL, predorsal length 63% (65%) SL, preanal length 72% (72%) SL, the first anal-fin ray situated below the fourth dorsal-fin ray), a total of 23 + 16 myomeres. The female contained a series of 30 rectangular eggs in a single row, whereas the male is characterized by a short rod-like urogenital papilla. Species of the genus Schindleria are likely the smallest marine vertebrates on the planet and S. parva is likely the smallest Schindleria species in the Red Sea. The global diversity of Schindleria is likely underestimated due to the paedomorphic features of this genus. Its fast generation times make it a species-rich genus of high turnover rates, thus potentially highly important for the trophic food webs of coral reefs. Thus, this finding advances knowledge on the biodiversity of the Red Sea, highlights its conservation significance, and contributes towards the understanding of the complexity of the coral-reef fish community.

하모닉 감속기의 치형 오차 측정 및 평가

Due to the recent 4<SUP>th</SUP> industrial revolution and explosive interest in smart factories, the demand for industrial robots and related technologies is rapidly increasing. In order to develop a precision reducer for robots, a measurement technology of the small teeth of a gear is very important. This paper developed a method to measure the tooth shape of a precision harmonic reducer for robots and to evaluate the tooth shape measurement error quantitatively. The tooth shape of the flexspline of a harmonic drive was measured using three instrumental devices: a stylus, a projector, and a laser line scanner. A mathematical tool was also developed to evaluate the error by comparing the designed and measured teeth. The measured tooth profile was quantitatively assessed with maximum, average, and root mean square error. The measurement method using a stylus has disadvantages of careful measurement effort and a small measuring range. However, it has better precision. On the other hand, the projection method shows a moderate performance without much effort during measurement.

Acoustical behavior of loss-optimized involute gears

The progressing electrification of vehicle drive systems focuses more and more on efficient high-speed concepts. Increasing the motor speed leads to a higher power density of the electrified power train and thereby to an increased range for battery electric vehicles. The high rotational speeds cause new challenges in designing gearboxes regarding the efficiency and the acoustical behavior. Most present gearings in conventional vehicles are designed with high tooth depths to ensure low noise excitation behavior combined with the best possible efficiency. By changing the gear geometry to smaller tooth depths with higher pressure angles, it is possible to further decrease gear losses. However, the loss-optimized gear geometry must not jeopardize the beneficial acoustical behavior. In theoretical studies, the acoustical behavior of loss-optimized gears are investigated and compared to gearings designed according to the state of the art. Design calculations of the excitations of all ideal gears without deviations are on similar levels. However, application of such gear geometries faces severe challenges because the sensitivity to manufacturing deviations may be high. In this paper, simulation results and test results between low-NVH gears and loss-optimized gears are documented and analyzed.

A new species of the deep-sea shrimp genus Spongicoloides (Decapoda: Spongicolidae) from the South China Sea.

Spongicoloides zhoui sp. nov. (Crustacea: Decapoda: Spongicolidae), a species of deep-sea hexactinellid sponge-associated shrimp, is described based on specimens collected from the Zhenbei Seamount in the South China Sea. The new species is morphologically most similar to the Western Pacific congeneric species Spongicoloides iheyaensis Saito, Tsuchida Yamamoto, 2006 in that the ischium of the third pereiopod is unarmed and the fixed finger of the third pereiopod is armed with small teeth on the distoventral margin. However, S. zhoui sp. nov. can be distinguished from S. iheyaensis in that its female antennal basicerite has three large spines on the distolateral margin. Molecular analyses based on nuclear histone H3, and mitochondrial cytochrome c oxidase subunit I (COI), 12S ribosomal RNA (rRNA), and 16S rRNA gene fragments confirmed the placement of S. zhoui sp. nov. within a clade of Spongicoloides/Spongiocaris species, and their sequence divergences were large enough to justify the recognition of this new species.

Microdontia treatment with orthodontics and indirect restoration: clinical case

Objective: This case report aims to present the microdontia treatment of tooth 35 through pre-prosthetic orthodontics, followed by re-anatomization with an indirect restoration. Case report: A 21-year-old female patient presented with microdontia in tooth 35, with a distalized and vestibularized crown. In addition, tooth 34 was gyroverted with mesial diastema. Orthodontic mechanics with segmented arch were used to centralize tooth 35 in the alveolar ridge, close the diastema in the mesial of tooth 34, and correct its gyroversion. For lingualization of tooth 35, a first-order fold (in set) was performed, and for mesialization, an open-coil spring was used between teeth 35 and 36. A closed-coil spring was used to delimit the movement of tooth 35 to mesial. The force applied by the open spring for mesialization of tooth 35 was transmitted to tooth 34, through the closed spring, resulting in its mesialization; this, closed the diastema between teeth 33 and 34 and corrected the gyroversion. Subsequently, the coronary preparation was performed with diamond tips 1014 and 3146, and confection of the temporary crown in acrylic resin. For the ceramic system, IPS™ e.max Press was used. The ceramic crown was luting using the adhesive technique, followed by light curing for 40 seconds on each face of the tooth. Conclusion: It can be concluded that the re-anatomization of a small tooth should be the first treatment option. However, pre-prosthetic orthodontic treatment may be necessary.

Third Molar Agenesis Is Associated with Facial Size.

Simple SummaryMissing third molars is a common occurrence in modern humans with a prevalence of approximately 20% in the general population. The absence of those teeth, however, is not found in other human predecessors. Therefore, there is speculation whether the congenital absence of third molars is part of an evolutionary mechanism that leads to smaller jaws, smaller and fewer teeth, or if their absence is associated with more local developmental factors. In this study, we assessed the size of the cranial base, the maxilla, the mandible and the entire craniofacial complex in individuals missing one or more third molars and compared them with a group with no missing teeth. We showed that in cases with one or more missing third molars, there is a significant decrease in the size of the maxilla, the mandible as well as the entire facial configuration. Additionally, the more missing third molars, the smaller the jaws and the face were. These findings suggest that isolated third molar agenesis is part of a developmental mechanism related to craniofacial size reduction. Whether this mechanism is part of an evolutionary process in humans remains to be seen.Individuals with congenitally missing permanent teeth, other than third molars, present smaller craniofacial configurations compared to normal controls. However, it is not known if agenesis of third molars is part of the same mechanism. Therefore, this study assessed individuals with and without isolated third molar agenesis and tested the relation of this condition to the size of their facial configurations, using geometric morphometric methods. We show that the absence of one or more third molars is associated with a smaller maxilla, smaller mandible and a smaller overall facial configuration. The effect was larger as the number of missing third molars increased. For example, the size of the mandibular centroids in five 16-year-old females with no, one, two, three or four missing third molars showed a size reduction of approximately 2.5 mm per missing third molar. In addition, in cases with third molar agenesis in one jaw only, the effect was also evident on the opposite jaw. Our findings suggest that isolated third molar agenesis is part of a developmental mechanism resulting also in craniofacial size reduction. This might be the effect of an evolutionary process observed in humans, leading to fewer and smaller teeth, as well as smaller facial structures.

A fossil record of the Eastern clade of Blanus (Amphisbaenia: Blanidae) from the late Miocene of Ukraine

The fossil history of worm lizards in Eastern Europe is very patchy because of the small number of localities and the fragmentary vertebral material available. A new record of the genus Blanus from the late Miocene of the Egorovka1 and 2 localities in Ukraine is reported here. Based on its dental morphology, Blanus from Egorovka differs from all extinct species of the genus and from the extant B. cinereus complex. It is most closely related to the Eastern clade of Blanus (B. strauchi complex) in having enlarged second and small third dentary teeth. Blanus from Egorovka is the second fossil record of the B. strauchi complex and the first record of the Eastern clade outside of its current geographical range. It indicates a wider past range of the Eastern European Blanus, including the northern Black Sea coastal area.

Pluridens serpentis, a new mosasaurid (Mosasauridae: Halisaurinae) from the Maastrichtian of Morocco and implications for mosasaur diversity

Mosasaurids (Mosasauridae) were specialized marine lizards that evolved and radiated in the Late Cretaceous. Their diversity peaked in the Maastrichtian, with the most diverse faunas known from Morocco. Here we describe a new species of mosasaurid from this fauna. Pluridens serpentis sp. nov. is described based on two complete skulls and referred jaws. It is referred to Pluridens based on the elongate and robust jaws, small teeth, and specialized tooth implantation. Pluridens is referred to Halisaurinae based on the posteriorly expanded premaxilla, long premaxilla-maxilla suture, broad premaxillary facet on the maxilla, closed otic notch, and small, striated, hooked teeth. The orbits are reduced relative to other halisaurines while the snout is robust and flat with a broad, rounded tip. The jaws bear numerous small, hooked, snake-like teeth. Skulls imply lengths of 5–6 m; referred material suggests lengths of ≥9 m. Pluridens’ specialized morphology – especially the contrasting large size and small teeth - suggests a distinct feeding strategy. Small orbits imply that P. serpentis relied on nonvisual cues including touch and chemoreception during foraging, as in modern marine snakes. Numerous neurovascular foramina on the premaxillae are consistent with this idea. The small teeth suggest proportionately small prey. The dentary becomes massive and robust in the largest individuals, suggesting sexual selection and perhaps sexual dimorphism, with the mandibles possibly functioning for combat as in modern beaked whales and lizards. The new mosasaur emphasizes how Maastrichtian mosasaurids were characterized by high species richness, high functional diversity, and high endemism, i.e. geographic specialization. It appears mosasaurids continued diversifying until the end of the Cretaceous, just prior to the K-Pg extinction.

Unique damage‐related, gap‐filling tooth replacement in pycnodont fishes

AbstractMost jawed vertebrates (gnathostomes) replace their teeth throughout life (polyphyodonty) and there is currently great interest in its molecular and cellular basis, particularly in fish. While much has still to be elucidated, it appears that whichever tooth replacement mechanism is used, only one tooth replaces one predecessor, at any one time. Here we present fossil crushing dentitions of two extinct pycnodont fishes, Pycnodus zeaformis and Pycnodus maliensis. Their surface features and x‐ray micro‐CT virtual sections show no evidence of one‐for‐one replacement. Instead, individual large teeth were replaced by multiple small teeth, for which, as far as we could ascertain, there is no known mechanism. This occurred where underlying dentigerous bone was damaged. Small teeth also developed where parts of large teeth had broken off, and in gaps between large teeth created by the geometry of their close alignment in rows. We compared the virtual sections to those of functionally analogous crushing dentitions of three modern fishes. Contrasting greatly to the pycnodonts, each showed an orderly, one‐for‐one replacement, typical of osteichthyans. We propose that the pycnodont specimens exhibit a gap‐filling tooth addition hitherto unseen in gnathostomes, and that the oral epithelium retained an initiatory competence throughout life, with a programming of ‘if a gap exists, fill it’. This would also have facilitated the addition of large teeth in rows, in space provided by ontogenetic growth. We hypothesize that gaps were registered as an absence of pressure at the crushing surface, initiating tooth development, as in the modern cichlid Astatoreochromis alluaudi.

Compliance and side effects of tongue stabilizing device in patients with obstructive sleep apnea

ABSTRACT Objective To evaluate the long-term effectiveness, compliance, and side effects of tongue stabilizing devices (TSDs). Methods Thirty-nine patients were followed up after 12 and 30 months. The subjective effectiveness was assessed using the Epworth Sleepiness Scale (ESS), the Functional Outcomes Sleep Questionnaire (FOSQ-10), the Chalder Fatigue Scale (CFQ), and a sleep-related quality of life questionnaire (QoL). Compliance and side effects were assessed. Results At 12-months, 35.9% of patients confirmed continuing the therapy, compared to only 15.4% of patients at 30 months. At 30 months, a significant average improvement of ESS (2.0 ± 2.8) was observed compared to baseline levels in six patients. Six patients demonstrated an average increase in blood pressure. The most frequently reported side effects were mouth dryness and excessive salivation. The 3D analysis revealed small tooth movements. Conclusion The TSD therapy demonstrated a good long-term subjective effectiveness against OSA but had a relatively low treatment acceptance rate.

3D Imaging of PDL Collagen Fibers during Orthodontic Tooth Movement in Mandibular Murine Model.

Orthodontic tooth movement is a complex biological process of altered soft and hard tissue remodeling as a result of external forces. In order to understand these complex remodeling processes, it is critical to study the tooth and periodontal tissues within their 3D context and therefore minimize any sectioning and tissue artefacts. Mouse models are often utilized in developmental and structural biology, as well as in biomechanics due to their small size, high metabolic rate, genetics and ease of handling. In principle this also makes them excellent models for dental related studies. However, a major impediment is their small tooth size, the molars in particular. This paper is aimed at providing a step by step protocol for generating orthodontic tooth movement and two methods for 3D imaging of the periodontal ligament fibrous component of a mouse mandibular molar. The first method presented is based on a micro-CT setup enabling phase enhancementimaging of fresh collagen tissues. The second method is a bone clearing method using ethyl cinnamate that enables imaging through the bone without sectioning and preserves endogenous fluorescence. Combining this clearing method with reporter mice like Flk1-Cre;TdTomato provided a first of its kind opportunity to image the 3D vasculature in the PDL and alveolar bone.

Symmetry of crown widths in subjects with unilateral maxillary lateral incisor agenesis

The aim of this study was to compare mesiodistal width and symmetry of maxillary and mandibular teeth in subjects with and without unilateral maxillary lateral incisor agenesis. The study group consisted of 31patients with unilateral maxillary lateral incisor agenesis (19females, 12males, mean age: 16.55 ± 5.24years), and acontrol group of 31patients (19females, 12males, mean age: 16.58 ± 4.41years) without agenesis. Mesiodistal dimensions of all teeth except second molars were measured. Paired samples t‑test and Wilcoxon signed-rank test were used for intragroup comparisons. Independent samples t‑test was used for intergroup comparisons. In the study group, mesiodistal dimensions of maxillary canine, second premolar, first molar, mandibular second premolar and first molar teeth on the agenesis side were significantly smaller than on the contralateral side (p < 0.05). In the control group, no significant difference was seen in mesiodistal dimensions between right and left sides. In the study group, mesiodistal dimensions of all teeth on the lateral agenesis side were significantly smaller than on the control side (p < 0.05). On the side without lateral agenesis, all teeth except the maxillary and mandibular first molars and mandibular second premolar teeth were significantly smaller than on the control side (p < 0.05). Total mesiodistal dimensions of the maxillary teeth were significantly smaller on the lateral agenesis side than on the contralateral side (p = 0.001). Total tooth size of the study group was significantly smaller than for the control group (p < 0.05). Patients with unilateral maxillary lateral incisor agenesis might have asymmetries in tooth width and have smaller teeth than individuals without agenesis.

Additional data on morphology and distribution of Melitoides valida (Shoemaker, 1955) (Amphipoda, Melitidae)

The genus Melitoides Gurjanova, 1934 (Amphipoda, Melitidae) includes three species from the Arctic and northwestern Pacific: Melitoides makarovi Gurjanova, 1934, M. valida (Shoemaker, 1955), and M. kawaii Labay, 2014. M. makarovi and M. kawaii only were recorded until recently in the seas of the Russian Far East. Only two specimens of M. valida were found once near the Arctic coast of Alaska; therefore, the morphological description of the species was incomplete, which led to difficulties with its generic identification. For the first time, M. valida was found in the seas of the Russian Far East in September 2018 on the shelf of the Sea of Okhotsk, near the North-Eastern Sakhalin Island at the depth of 29 m on the sand bottom. Detailed re-description of the species was carried out using optical and electronic scanning microscopes by the Coleman protocol. The material collected is stored at the Crustacea collection of the Zoological Museum of Far Eastern Federal University (Vladivostok). The specimen from the Sea of Okhotsk is identical to the specimens of the type series from the Arctic coast of Alaska in the form of dorsal carination (with several teeth on posterior margin of pleon segments 2, 3 and urosomites 1, 2), in the structure of pereopods 1–7, especially in the form of propodus of pereopods 2 (palm with distinct posterior-distal tooth, as well as with three large and one small obtuse palmar teeth). M. valida description has been substantially supplemented, and information on its range has been expanded.

Description of two new species of Bassozetus (Ophidiiformes: Ophidiidae) and a redescription of Bassozetus robustus Smith and Radcliffe 1913

Two new deepwater assfish species, Bassozetus trachibranchus and Bassozetus squamosus, are described from the 29 western Atlantic and four western Indian and western South Pacific specimens, respectively. In addition, a redescription of Bassozetus robustus Smith and Radcliffe in Radcliffe 1913, with which both of the above two new species have been previously confused, is provided on the basis of 14 specimens and its distributional range is revised to the western Pacific Ocean. The three species are separable from the 13 known congeners by the following combination of characters: dorsal-fin rays (116–126), anal-fin rays (95–103), oblique scale rows (30–47), pelvic-fin length (14.3–21.7% SL), a single well-developed median bashibranchial tooth patch, and one or two deep indentations on the sagitta dorsal margin, plus long gill rakers (10–14 in B. robustus) and head, predorsal and prepelvic lengths (20.5–22.8% SL, 19.4–21.1% SL and 15.3–18.1% SL, respectively, in B. robustus). Additionally, B. trachibranchus, B. squamosus and B. robustus are distinguishable from each other as follows: oblique scale rows (39–45 in B. trachibranchus, 44–47 in B. squamosus, and 30–36 in B. robustus), eye diameter to head length ratio (greater in B. squamosus than in similarly sized specimens of the other species), pelvic fin length/distance between pelvic and anal fins ratio (smaller in B. robustus than in similarly sized specimens of the other species), and 2nd to 4th lower limb morphology (many small tooth patches arranged along the outer ridges in B. trachibranchus, absent or a few only in the other species).

Complex Odontoma: A Case Report

Odontoma, a mixed odontogenic tumor, is considered to be a hamartoma rather than a true neoplasm. Fully developed odontomas chiefly consist of enamel, dentin, pulp and occasionally cementum. They are subdivided into compound and complex types. The compound odontoma is composed of multiple, small tooth like structures, whereas the complex type consists of a conglomerated mass of enamel and dentin, having no anatomical resemblance to a tooth. They are usually asymptomatic, slow growing but cause bony expansion, which is often discovered during routine radiography. Here, we report a case of a complex odontoma in the posterior left mandibular region in an eight year old female child.