Double Teeth and Coexistent Anomalies: Examples From Continental Africa.

OBJECTIVES: Whether gemination or fusion, double teeth are rare worldwide, including Africa based on few published data. New cases from the continent are tallied, and anomalies potentially associated with double teeth are identified. These findings should interest a range of dental researchers. METHODS: The presence of double teeth was recorded in 97 modern and premodern North and sub-Saharan African samples (5631 inds.). They and coexistent anomalies are described relative to published examples. Prevalence was estimated as possible, using a Poisson model for 95% confidence intervals (CI). RESULTS: Three maxillary double teeth were identified: a primary left lateral incisor in a Nubian child (1938-1756 BC), permanent left central incisor in an adult Egyptian (3650-3500 BC), and permanent right central incisor in a modern (19th century) adult from Guinea. Each co-occurs, respectively, with a talon cusp, peg lateral incisor and, in the latter individual, second premolar crown variation with rotation, and third molar dens evaginatus. Double tooth prevalence is 0.048% (CI 0.001%-0.270%), with regional variation, in premodern, and 0.000% in modern North Africans. It is 0.000% for premodern and 0.048% for modern sub-Saharan Africans (0.008%-1.714%). CONCLUSIONS: The double incisors are comparable to other global examples, indicative of common developmental processes during odontogenesis. Prevalence is lower than published modern rates, to suggest some exceptionality in Africans as reported earlier for other dental variants. Finally, though circumstantial, double teeth and accompanying anomalies may share an etiology. Continuing research overall, and in Africa specifically, will promote an improved understanding of double teeth formation and expression.

Schizodontic Molarization of Mandibular Premolars: A Case Report of Gemination.

Background: Tooth gemination is a single enlarged or joined tooth with a normal tooth count when the anomalous tooth is counted as one. Mandibular second premolars show an elevated variability of crown morphology. Only nine cases of isolated second premolar macrodontia have been reported in the literature. Case Description: This case report presents the clinical and radiographic findings and conservative treatment of an atypical and rare case of localized bilateral molarization of mandibular second premolars. Conclusion: Dental professionals should acquire deeper knowledge about anomalies and plan treatment carefully to avoid unexpected complications during dental procedures caused by morphological ignorance.

Identification of AtALKBH1A and AtALKBH1D as DNA N6-adenine demethylases in Arabidopsis thaliana.

DNA N6-methyladenine (6 mA) has recently been discovered as a novel DNA modification in animals and plants. In mammals, AlkB homolog 1 (ALKBH1) has been identified as a DNA 6 mA demethylase. ALKBH1 tightly controls the DNA 6 mA methylation level of mammalian genomes and plays important role in regulating gene expression. DNA 6 mA methylation has also been reported to exist in plant genomes, however, the plant DNA 6 mA demethylases and their function remain largely unknown. Here we identify homologs of ALKBH1 as DNA 6 mA demethylases in Arabidopsis. We discover that there are four homologs of ALKBH1, AtALKBH1A, AtALKBH1B, AtALKBH1C and AtALKBH1D, in Arabidopsis. In vitro enzymatic activity studies reveal that AtALKBH1A and 1D can efficiently erase DNA 6 mA methylation. Loss of function of AtALKBH1A and AtALKBH1D causes elevated DNA 6 mA methylation levels in vivo. atalkbh1a/1d mutant displays delayed seed gemination. Based on our RNA-seq data, we find some regulators of seed gemination are dysregulated in atalkbh1a/1d, and the dysregulation is correlated with changes of DNA 6 mA methylation levels. This study identifies plant DNA 6 mA demethylases and reports the function of DNA 6 mA methylation in regulating seed germination.

Production of Arabic Geminates by English Speakers.

This study investigates the production of Arabic intervocalic geminate obstruents as produced by American L2 learners of Arabic. The participants of the study were 24 Arabic learners (12 advanced, 12 beginners) at North Georgia University and 12 native speakers of Jordanian Arabic (the control group). An examination of the results reveals that native speakers of Arabic and advanced Arabic learners pattern similarly while the beginner Arabic learners show a different pattern. Native speakers as well as advanced L2 learners of Arabic maintain a contrast between geminate and singleton consonants in terms of consonant duration while beginner L2 leaners do not. Unlike the case of the beginner L2 learners, the duration of the preceding vowel is found to be shorter before a geminate in native speakers and advanced L2 learners. However, the duration of vowels following a geminate is not affected across all proficiency levels. Further, the results suggest that the place and manner of articulation have no effect on the production of geminate consonants for both native and advanced L2 learners. Finally, voicing of geminates is found to have a significant effect on the duration of geminates, in favor of voiceless geminates, among native speakers and beginner L2 learners.

Geminated Supernumerary Premolar Impacted in the Palate: A Report of a Rare Case and Review of the Literature.

Supernumerary teeth are dental anomalies characterized by the presence of an excessive number of teeth in relation to normal dentition. Among these, the supernumerary premolars have a prevalence of 0.29% to 0.64%, making it a very rare finding. On the other hand, gemination is a developmental disturbance in the shape of the teeth where a partial cleavage of a single tooth germ results in the formation of a singular root and a singular pulp chamber but two partially or totally separated crowns. Although these anomalies as individual entities are fairly common in clinical practice, the occurrence of both anomalies in a single tooth is an extremely rare occurrence. We hereby report a rare case of impacted geminated supernumerary premolar in a 45-year-old female patient. A thorough search of the literature revealed that only four cases listing this anomaly have been reported in the literature thus deserving a mention. In addition to the case presentation, the authors have also reviewed the existing literature on this anomaly.

Root Canal Treatment of a Geminated Maxillary Second Molar with C-shaped Canal System: A Case Report.

Gemination is a rare phenomenon in the maxillary posterior teeth. Endodontic treatment of these teeth requires special care due to the bizarre anatomy particularly when it is accompanied by a C-shaped canal system. This report illustrates a patient with a rare geminated C-shaped maxillary second molar comprised of two sections in its crown, including a geminated section attached to a normal coronal of a second maxillary molar diagnosed with the pulpal status "necrosis" and "irreversible pulpitis" in geminated section and the molar respectively. Thus, endodontic treatment was performed on both parts of the tooth. Two months follow-up revealed well-functioning teeth with normal status of periapical tissue with no mobility or abnormality. Successful treatment of unusual anatomical teeth requires adherence to biomechanical principles of canal preparation and coronal restoration.

Prosody Trumps Orthography in Second Language Phonology: The Case of Consonant Gemination.

This paper examines the understudied phenomenon of consonant gemination in the pronunciation of English among Levantine Arabic learners of English (LA learners). The very few studies that touched on gemination among LA learners attributed gemination to spelling in the target language (English). This study challenges this analysis and demonstrates that gemination is primarily a phonological phenomenon that is triggered by first language under-represented structural rules as well as Universal Grammar (UG) markedness principles. Data were elicited through semi-structured interviews with three groups of LA learners. Contrary to previous studies (on other phonological aspects), which argue that interference errors decrease over time, findings show that gemination is attested across all groups of LA learners and persists even among advanced learners. Results show that interface phenomena involving more than one phonological level pose a great challenge to second language learners.

Exploring Variability in Compound Tensification in Seoul Korean.

In Korean noun-noun compounds, the lenis onset consonant in the second noun is often realized as a tense consonant. Although extensive work has been carried out to clarify its causes and relevant phonological processes, this tensification is deemed not entirely predictable. This paper presents a speech production experiment that confirms the existing findings that the variability in tensification is predictable to a certain extent. The experimental results also showed that the relationship between the predictors and the variability is not linear and that tensification mirrors the cognitively determined boundary strength. Native Korean speakers calibrate the boundary strength by incorporating complex information, such as the word's length, segment type, frequency, and plausibility of the compound. While a "tight" boundary led to high tensification probability, it was not affected by speaking-rate variation. Furthermore, the perceived compound's plausibility directly affected the duration of the tensified consonant. Importantly, the findings suggest that speakers' calibration of the boundary strength is fluid and changeable over time and it affects both phonological and phonetic outputs. Finally, variability in data was reduced for the experimental conditions leading to either extremely high or low tensification probability, and there seemed to be lexicalized exceptions to the general trends.

The Study of Prevalence and Distribution of Shape Anomalies of Teeth in Indian Population on the Basis of Age and Gender.

INTRODUCTION: Dental anomaly of shape leads to various clinical dental pathologies requiring the intervention of a dental specialist. Early diagnosis and intervention in earlier stages can restore a near-normal dentition and esthetics. So, the present study was undertaken to determine the prevailing dental anomalies of shape and its various subtypes in various age groups and gender variations. MATERIALS AND METHODS: Retrospective dental casts and radiographs were evaluated in 3,000 cases consisting of an equal proportion of males and females. Only cases with an age range from 10 to 40 years were included in the study. Dental anomalies of shape were evaluated for the presence of Gemination, fusion, talon cusp, dens evaginates, the cusp of carabelli, dens invaginatus, taurodontism, and dilacerations and recorded. RESULT: A total of 538 (17.9%) cases were found to have dental anomalies of shape which included 288 (19.2%) males and 250 (16.6%) females. Dilaceration was found to be the most common (9.2%) dental anomaly of shape followed successively by taurodontism (3.7%), talon cusp (2.23%), and the cusp of carabelli (1.4%). Most of the shape anomalies showed male predilection. A higher prevalence of most dental anomalies of shape was found in the younger age group of 10 to ≤25 years as it is not linked with age but still has got importance to know while the treatment is carried out in this age group. CONCLUSION: It is quite imperative to have complete knowledge of trends and patterns of shape anomalies in India. It will guide dental practitioners to formulate a treatment plan on the basis of existing prevailing anomalies.

The GEMMA speech database: VCV and VCCV words for the acoustic analysis of consonants and lexical gemination in Italian.

The GEMMA database consists of recordings of disyllabic words: vowel-consonant-vowel (VCV) for nongeminate cases and vowel-consonant-consonant-vowel (VCCV) for geminate cases. The consonants in the words are stops /b/, /d/, /g/, /p/, /t/, /k/, affricates /ts/, /dz/, /ʧ/, /ʤ/, fricatives /f/, /v/, /s/, /z/ (singleton only) and /ʃ/ (geminate only), nasals /m/, /n/ and /ɲ/ (geminate only), and liquids /l/, /r/ and / λ / (geminate only). The database also includes recordings for glides (/j/, /w/). The vowels in the words are /a, i, u/; words are symmetric with respect to vowel. Six native adult speakers of Standard Italian, raised and living in Rome, Italy, three female and three male, uttered the speech materials in three different recording sessions; three repetitions for each word per speaker were therefore collected. The dataset also includes the durations of vowel and consonant segments for all cases where the consonant can be singleton vs. geminate (see [1] and [2]).

The LaMIT database: A read speech corpus for acoustic studies of the Italian language toward lexical access based on the detection of landmarks and other acoustic cues to features.

The LaMIT database consists in recordings of 100 Italian sentences. The sentences in the database were designed so to include all phonemes of the Italian language, and also take into account the typical frequency of each phoneme in written Italian. Four native adult speakers of Standard Italian, raised and living in Rome, Italy, two female and two male, pronounced the sentences in two different recording sessions; two repetitions for each sentence per speaker were therefore collected, for a total of 800 recordings. The database was specifically created for application in the LaMIT project, that focuses on the application to the Italian language of the Lexical Access model proposed by Ken Stevens for American English. The model relies on the detection of specific acoustic discontinuities called landmarks and other acoustic cues to features that characterize each phoneme. Each recording was thus processed to generate a set of labeling files that identify both predicted landmarks and other cues, and actual landmarks/cues. The labeling files, compiled according to the labeling syntax used in the Praat speech processing software, are also made available as part of the LAMIT database.

Impacted Molariform Distomolar Double Tooth: A Case Report.

Double teeth, also called connated or cojoined teeth, are clinically present as two separate teeth united by dentin. It occurs due to the fusion of two individual tooth buds or the partial splitting of one into two. An accessory supernumerary fourth molar is called a distomolar or distodens. Usually, the distomolar has a small crown that can be conical, peg-shaped, or like a small premolar called molariform distomolar that occurs distal to the last molar. This case presents an impacted molariform distomolar with the fusion of crown and root in a 27-year-old female.

Acoustic and Kinematic Correlates of Heterosyllabicity in Different Phonological Contexts.

We investigate the temporal and kinematic properties of consonant gemination and heterosyllabic clusters as opposed to singletons and tautosyllabic clusters in Italian. The data show that the singleton versus geminate contrast is conveyed by specific kinematic properties in addition to systematic durational differences in both the consonantal and vocalic intervals; by contrast, tautosyllabic and heterosyllabic clusters differ significantly for the duration of the consonantal interval but do not vary systematically with respect to the vocalic interval and cannot be consistently differentiated at the kinematic level. We conclude that systematic variations in acoustic vowel duration and the kinematics of tongue tip gestures represent the phonetic correlates of the segmental phonological contrast between short and long consonants, rather than of syllable structure. Data are only partly consistent with the predictions of both moraic and gesture-based models of the syllable about the effects of syllable structure on speech production dynamics and call for a more gradient view of syllabification.

Ancient anomalies: Twinned and supernumerary incisors in a medieval Nubian.

During the analysis of a skeletal assemblage from a medieval cemetery in Nubia (c. AD 500-1550), a young adult female with abnormally developed maxillary incisors was discovered. The possible causes of the two dental anomalies found in this individual and their archaeological context are discussed. The remains are from a medieval assemblage from the Fourth Cataract region of Nubia, which forms part of the Nubian collection curated at the British Museum. The left central incisor has a twinned crown with two root canals, and a supernumerary tooth is present on the right side between the central incisor and lateral incisors. Although two different dental anomalies are present, the bilateral expression suggests that the same biological mechanism could be responsible.

Endodontic management of a rare case of the geminated maxillary second molar tooth using CBCT.

This report illustrates a rare case of a geminated maxillary right second molar tooth using CBCT in a 23-year-old man with severe pain. Nonsurgical endodontic treatment was performed, which gave rise to an asymptomatic tooth at the 12-month follow-up.

Double Gemination or Fusion of a Permanent Mandibular Second Molar: A Case Report.

Gemination and fusion are developmental conditions affecting the shape of teeth in both primary and permanent dentition. A 12-year-old girl presented for clinical assessment and the examination revealed an unusually shaped mandibular right second molar with irreversible pulpitis. Correlation of the intraoral and radiological appearance of this tooth suggested a diagnosis of either double gemination or fusion. The favourable position of the developing third molar supported early extraction of the abnormal second molar. The present report documents the clinical and radiological presentation of a mandibular second molar with an unusual developmental alteration in shape. Well-timed extraction therapy and good communication may reduce the need for unnecessary, complex treatment.

Bilateral gemination of permanent maxillary canine with labial and palatal talon's cusps: A rare entity.

Gemination is a morphologic anomaly of the tooth characterized by the formation of a macrodont. Bilateral presentation is rarely reported in permanent canines. Talon's cusp is an accessory cusp projecting lingually from the cingulum to the incisal edge and may be seen facially sometimes. Simultaneous occurrence of facial and lingual talons on the same tooth is rare. Concurrent occurrence of all the three entities has not been reported. These anomalies can cause unpleasant esthetic appearance due to irregular morphology. The presence of deep grooves on these teeth increases the susceptible to caries and periodontal disease requiring an endodontic intervention. Proper clinical and radiographic examination provides an accurate diagnosis and helps the clinician in the proper treatment planning and avoiding further complications. This article presents a unique case of simultaneous occurrence of bilateral gemination in the permanent maxillary canines with labial and palatal talon's cusps, which has not been reported in the literature till date.

Germination potential of baldcypress (Taxodium distichum) swamp soil seed bank along geographical gradients.

Changing environments of temperature, precipitation and moisture availability can affect vegetation in ecosystems, by affecting regeneration from the seed bank. Our objective was to explore the responses of soil seed bank germination to climate-related environments along geographic gradients. We collected seed banks in baldcypress (Taxodium distichum) swamps along the Mississippi River and the Gulf of Mexico Coast in the United States, which have distinct temperature and/or precipitation gradients, and germinated them in a greenhouse. The frequency, richness and seed density of species germinated from the seed bank were compared between various geographic locations, experimental water regimes (saturated, flooded) and wetland types (tidal, non-tidal and inland swamps). We also analyzed the relationship of seed density to the environment by using a Non-metric Multi-dimensional Scaling (NMDS) model. Sixty-one species germinated from the seed bank, differing in pattern by geographic location, experimental water regime and wetland type. The foundation species (i.e., T. distichum and Cephalanthus occidentalis) germinated with a niche affinity for the northern part of the latitudinal gradient (Tennessee and Illinois) and these species may shift northward with climate change. Some species had higher seed density in the locations that were subject to more persistent drought conditions (e.g., Texas) including Cyperus rotundus and Gratiola virginiana, indicating that these species may be better adapted to sites with high temperature and low precipitation. In contrast, certain species including Saururus cernuus and Ludwigia palustris were present throughout the range of these gradients, and so may be more resilient to any future climate shifts. We found that the regeneration potential of baldcypress swamps might be altered by changes in local and climate environment because of nuances of responses of seed banks to climates along latitudinal and longitudinal gradients. Our study can help predict vegetation regeneration potential to climate change environments depending on the ability of these species to disperse and maintain seed banks.

Rare case of gemination of mandibular third molar-A case report.

Fusion and germination are the anomalies that occur due to some developmental eccentricity during the time of morpho-differentiation of the tooth bud and have a close resemblance to each other. The gemination is an attempt of the division of a single tooth into two and, hence, appears as an enlarged single tooth while the tooth count is normal when the affected tooth is counted as one. Its exact pathogenesis is ambiguous. This anomaly has been observed mostly in deciduous dentition as compared to that in permanent dentition. Gemination is rarely associated with the third molar and, hence, the terminology is arguable when this condition is seen in relation to the third molar. In the present article, a case of germination of mandibular third molar has been reported.

Gemination in Northern versus Central and Southern Varieties of Italian: A Corpus-based Investigation.

It is often claimed that patterns of gemination are different across varieties of Italian. In particular, northern speakers are sometimes said to degeminate, or to produce shorter geminates than central and southern speakers. However, experimental data proving such claims is largely missing. In this article, we perform an analysis of the CLIPS corpus with the aim of comparing gemination for northern versus central and southern speakers of Italian. The analysis of different data types (target words in isolated position, read sentences, dialogues, local radio and TV broadcasts) revealed that: (a) geminate consonants are produced by all speakers, incl. northern speakers; (b) differences in the magnitude of consonant lengthening are small (< 19 ms) and reach significance only for some data types; (c) the shortening of vowels preceding geminate consonants is mainly restricted to isolated target words in nuclear position, with no significant differences between northern and central/southern speakers. We argue that regional differences in Italian gemination have been overestimated and overemphasized in the literature. In fact, the evidence suggests that they are not as sizeable as previously thought, probably because of the progressive standardization of the language.