Unilateral Buccal Bifurcation Cyst: A Rare Cystic Lesion in Children and Adolescents.

A buccal bifurcation cyst (BBC) is a rarely occurring, distinct lesion that is limited exclusively to the buccal bifurcation area of mandibular first and second molars in children and adolescents. A definitive diagnosis is formulated based on specific clinical and radiographic features. Management of such cysts depends on the presence of symptoms and the size of the lesion. This case report details the common features of a BBC in a 13-year-old patient and outlines the surgical approach to managing the cystic entity. The importance of a comprehensive clinical examination and appropriate supplemental investigations is emphasized to facilitate accurate diagnosis.

Diagnosing Oral Granulomatous Lesions: A Case Report.

The diagnosis of oral granulomatous lesions raises many challenges for the clinician. This article, which includes a case report, describes a process to formulate differential diagnoses by identifying distinguishing characteristics of an entity and applying that information to attain understanding of the ongoing pathophysiological process. Relevant clinical, radiographic, and histologic findings of common disease entities that can mimic clinical and radiographic presentation of this case are discussed to aid dental clinicians in identifying and diagnosing similar lesions in their practice.

CircFISH: A Novel Method for the Simultaneous Imaging of Linear and Circular RNAs.

Circular RNAs (circRNAs) are regulatory RNAs which have recently been shown to have clinical significance in several diseases, including, but not limited to, various cancers, neurological diseases and cardiovascular diseases. The function of such regulatory RNAs is largely dependent on their subcellular localization. Several circRNAs have been shown to conduct antagonistic roles compared to the products of the linear isoforms, and thus need to be characterized distinctly from the linear RNAs. However, conventional fluorescent in situ hybridization (FISH) techniques cannot be employed directly to distinguish the signals from linear and circular isoforms because most circRNAs share the same sequence with the linear RNAs. In order to address this unmet need, we adapted the well-established method of single-molecule FISH by designing two sets of probes to differentiate the linear and circular RNA isoforms by virtue of signal colocalization. We call this method 'circular fluorescent in situ hybridization' (circFISH). Linear and circular RNAs were successfully visualized and quantified at a single-molecule resolution in fixed cells. RNase R treatment during the circFISH reduced the levels of linear RNAs while the circRNA levels remain unaltered. Furthermore, cells with shRNAs specific to circRNA showed the loss of circRNA levels, whereas the linear RNA levels were unaffected. The optimization of the in-situ RNase R treatment allowed the multiplexing of circFISH to combine it with organelle staining. CircFISH was found to be compatible with multiple sample types, including cultured cells and fresh-frozen and formalin-fixed tissue sections. Thus, we present circFISH as a versatile method for the simultaneous visualization and quantification of the distribution and localization of linear and circular RNA in fixed cells and tissue samples.

Structural basis of cyclic oligoadenylate binding to the transcription factor Csa3 outlines cross talk between type III and type I CRISPR systems.

RNA interference by type III CRISPR systems results in the synthesis of cyclic oligoadenylate (cOA) second messengers, which are known to bind and regulate various CARF domain-containing nuclease receptors. The CARF domain-containing Csa3 family of transcriptional factors associated with the DNA-targeting type I CRISPR systems regulate expression of various CRISPR and DNA repair genes in many prokaryotes. In this study, we extend the known receptor repertoire of cOA messengers to include transcriptional factors by demonstrating specific binding of cyclic tetra-adenylate (cA4) to Saccharolobus solfataricus Csa3 (Csa3Sso). Our 2.0-Å resolution X-ray crystal structure of cA4-bound full-length Csa3Sso reveals the binding of its CARF domain to an elongated conformation of cA4. Using cA4 binding affinity analyses of Csa3Sso mutants targeting the observed Csa3Sso•cA4 structural interface, we identified a Csa3-specific cA4 binding motif distinct from a more widely conserved cOA-binding CARF motif. Using a rational surface engineering approach, we increased the cA4 binding affinity of Csa3Sso up to ∼145-fold over the wildtype, which has potential applications for future second messenger-driven CRISPR gene expression and editing systems. Our in-solution Csa3Sso structural analysis identified cA4-induced allosteric and asymmetric conformational rearrangement of its C-terminal winged helix-turn-helix effector domains, which could potentially be incompatible to DNA binding. However, specific in vitro binding of the purified Csa3Sso to its putative promoter (PCas4a) was found to be cA4 independent, suggesting a complex mode of Csa3Sso regulation. Overall, our results support cA4-and Csa3-mediated cross talk between type III and type I CRISPR systems.

Frequency and types of incidental findings on limited field of view CBCT scans.

The objective of this retrospective study was to identify and categorize incidental findings (IFs) discovered on limited field of view (LFOV) cone beam computed tomographic (CBCT) scans of the maxillofacial region. The sequential LFOV CBCT radiology reports created by 2 board-certified radiologists from January 1, 2017, to December 31, 2017, were retrospectively reviewed. The CBCT scans were acquired for implant site evaluation. Incidental findings of pathologic or anatomical defects were categorized as endodontic, periodontal, sinus-related, nonodontogenic, or other concerns. Of 474 radiology reports that were evaluated, 244 (51.5%) recorded at least 1 detectable IF. Fifty-one of these 244 (10.8% of the total sample) recorded that multiple IFs were detected on a single CBCT scan. On 3 reports, 3 IFs were detected, while the remaining 48 reports showed 2 IFs. More than half of the 295 unique IFs were categorized as endodontic or sinus-related concerns. The majority (70.5%) of IFs were recommended for referral or additional treatment. The results indicate that the use of a CBCT system with an LFOV does not diminish the need to conduct a thorough evaluation of the images.

The Landscape of Regulatory Noncoding RNAs in Ewing's Sarcoma.

Ewing's sarcoma (ES) is a pediatric sarcoma caused by a chromosomal translocation. Unlike in most cancers, the genomes of ES patients are very stable. The translocation product of the EWS-FLI1 fusion is most often the predominant genetic driver of oncogenesis, and it is pertinent to explore the role of epigenetic alterations in the onset and progression of ES. Several types of noncoding RNAs, primarily microRNAs and long noncoding RNAs, are key epigenetic regulators that have been shown to play critical roles in various cancers. The functions of these epigenetic regulators are just beginning to be appreciated in ES. Here, we performed a comprehensive literature review to identify these noncoding RNAs. We identified clinically relevant tumor suppressor microRNAs, tumor promoter microRNAs and long noncoding RNAs. We then explored the known interplay between different classes of noncoding RNAs and described the currently unmet need for expanding the noncoding RNA repertoire of ES. We concluded the review with a discussion of epigenetic regulation of ES via regulatory noncoding RNAs. These noncoding RNAs provide new avenues of exploration to develop better therapeutics and identify novel biomarkers.

Identification of a New Transcriptional Co-Regulator of STEAP1 in Ewing's Sarcoma.

Ewing's sarcoma (ES) is caused by a chromosomal translocation leading to the formation of the fused EWSFLI1 gene, which codes for an aberrant transcription factor EWSFLI1. The transcriptional targets of EWSFLI1 have been viewed as promising and novel drug targets in the treatment of ES. One such target is six transmembrane epithelial antigen of the prostate 1 (STEAP1), a transmembrane protein that is upregulated by EWSFLI1 in ES. STEAP1 is a hallmark of tumor invasiveness and an indicator of tumor responsiveness to therapy. EWSFLI1 binds to the STEAP1 promoter region, but the mechanism of action by which it upregulates STEAP1 expression in ES is not entirely understood. Upon analysis of the STEAP1 promoter, we predicted two binding sites for NKX2.2, another crucial transcription factor involved in ES pathogenesis. We confirmed the interaction of NKX2.2 with the STEAP1 promoter using chromatin immunoprecipitation (ChIP) analysis. We used single-molecule RNA imaging, biochemical, and genetic studies to identify the novel role of NKX2.2 in regulating STEAP1 expression in ES. Our results show that NKX2.2 is a co-regulator of STEAP1 expression and functions by interacting with the STEAP1 promoter at sites proximal to the reported EWSFLI1 sites. The co-operative interaction of NKX2.2 with EWSFLI1 in regulating STEAP1 holds potential as a new target for therapeutic interventions for ES.

Structural basis of KdpD histidine kinase binding to the second messenger c-di-AMP.

The KdpDE two-component system regulates potassium homeostasis and virulence in various bacterial species. The KdpD histidine kinases (HK) of this system contain a universal stress protein (USP) domain which binds to the second messenger cyclic-di-adenosine monophosphate (c-di-AMP) for regulating transcriptional output from this two-component system in Firmicutes such as Staphylococcus aureus. However, the structural basis of c-di-AMP specificity within the KdpD-USP domain is not well understood. Here, we resolved a 2.3 Å crystal structure of the S. aureus KdpD-USP domain (USPSa) complexed with c-di-AMP. Binding affinity analyses of USPSa mutants targeting the observed USPSa:c-di-AMP structural interface enabled the identification of the sequence residues that are required for c-di-AMP specificity. Based on the conservation of these residues in other Firmicutes, we identified the binding motif, (A/G/C)XSXSX2N(Y/F), which allowed us to predict c-di-AMP binding in other KdpD HKs. Furthermore, we found that the USPSa domain contains structural features distinct from the canonical standalone USPs that bind ATP as a preferred ligand. These features include inward-facing conformations of its ß1-α1 and ß4-α4 loops, a short α2 helix, the absence of a triphosphate-binding Walker A motif, and a unique dual phospho-ligand binding mode. It is therefore likely that USPSa-like domains in KdpD HKs represent a novel subfamily of the USPs.

Mönckeberg Arteriosclerosis of the Facial Vasculature Presentation on CBCT: A Case Report.

Mönckeberg arteriosclerosis, also known as Mönckeberg sclerosis or Mönckeberg medial calcinosis, is a well-documented phenomenon in medicine due to its association with a number of serious systemic conditions and aging. This article presents a unique case of Mönckeberg arteriosclerosis in the oral facial region demonstrated clearly on cone-beam computed tomography (CBCT). The reporting of Mönckeberg arteriosclerosis in dental literature is uncommon even though the radiographic features of the head and neck on plain film and CBCT are unique to the condition. As dentistry and medicine strive to move toward an integrated one-health model, it will be important for dental practitioners to recognize this condition during dental radiographic evaluation. A practitioner's understanding of the potential medical implications and the need for appropriate referral to a medical colleague could be lifesaving for a dental patient.

Methods for spatial and temporal imaging of the different steps involved in RNA processing at single-molecule resolution.

RNA plays a quintessential role as a messenger of information from genotype (DNA) to phenotype (proteins), as well as acts as a regulatory molecule (noncoding RNAs). All steps in the journey of RNA from synthesis (transcription), splicing, transport, localization, translation, to its eventual degradation, comprise important steps in gene expression, thereby controlling the fate of the cell. This lifecycle refers to the majority of RNAs (primarily mRNAs), but not other RNAs such as tRNAs. Imaging these processes in fixed cells and in live cells has been an important tool in developing an understanding of the regulatory steps in RNAs journey. Single-cell and single-molecule imaging techniques enable a much deeper understanding of cellular biology, which is not possible with bulk studies involving RNA isolated from a large pool of cells. Classic techniques, such as fluorescence in situ hybridization (FISH), as well as more recent aptamer-based approaches, have provided detailed insights into RNA localization, and have helped to predict the functions carried out by many RNA species. However, there are still certain processing steps that await high-resolution imaging, which is an exciting and upcoming area of research. In this review, we will discuss the methods that have revolutionized single-molecule resolution imaging in general, the steps of RNA processing in which these methods have been used, and new emerging technologies. This article is categorized under: RNA Export and Localization > RNA Localization RNA Methods > RNA Analyses in Cells RNA Interactions with Proteins and Other Molecules > Small Molecule-RNA Interactions.

Effect of Intracanal Medicaments (Modified Triple Antibiotic Paste, Calcium Hydroxide, and Aloe Vera) on Microhardness of Root Dentine: An In Vitro Study.

AIM: To compare the effect of three different intracanal medicaments, namely, modified triple antibiotic paste (MTAP), calcium hydroxide (Ca(OH)2), and aloe vera, on the root dentine microhardness. MATERIALS AND METHODS: A total of 50 extracted mandibular bicuspids were prepared using ProTaper Next rotary files. The roots of the bicuspids were alienated to three groups (n = 10 each) and one control group (untreated; n = 20). In three groups, the root canals were filled with MTAP, Ca(OH)2, and aloe vera medicaments. After 21 days, medicaments were removed by Endo activator. Mean Knoop hardness numbers were calculated after treatment and compared with the untreated control group. Data were evaluated using the Student's t test (paired), ANOVA (one-way) followed, and the post hoc test. RESULTS: All treated groups except the aloe vera group had shown significant reduction (p < 0.05) in microhardness of the root dentin as compared with the untreated control group. The aloe vera group showed least reduction of microhardness and was statistically insignificant (p > 0.05). CONCLUSION: Aloe vera shows promising results in terms of fewer effects on microhardness of the root dentin compared to MTAP and Ca(OH)2. CLINICAL SIGNIFICANCE: Elimination of most of the bacterial infection from the root canal and very minimum to no effect on the microhardness of the dentin in the root part are the basics of success in any endodontic treatment. Further in vivo studies are required to compare the efficacy of these intracanal medicaments.

Preparedness of dental under-graduate students towards practicing endodontics in rural and remote areas of India.

BACKGROUND: Undergraduate students can provide valuable opinions and suggestions for modifying the educational program for the enhancement of learning. Therefore, the aim of this study was to explore the preparedness of undergraduate dental students with regard to practice endodontics in the rural and remote areas of India. MATERIALS AND METHODS: The present cross-sectional questionnaire-based study was conducted among dental undergraduates (interns). The survey was conducted among the students of 3 private dental colleges. For the data collection, a close-ended questionnaire was designed to test the knowledge for performing endodontic therapy, root canal therapy (RCT), attitude, and behavior of performing these procedures in the rural set-ups. Unpaired t test and one way analysis of variance (ANOVA) was used to compare the significant difference based on demographics and Pearson's correlation was applied to find the associations among knowledge, attitude, and behavior of study participants. The level of significance was set at below 0.05. RESULTS: A total of 79 students participated, out of which 22 respondents were males (27.8%), and 57 were females (72.15%). Overall mean knowledge scores for endodontics was 9.72 ± 2.19, and the scores of female students were slightly higher than males, whereas the attitude and behavior were better in males but there was no statistical significant difference between both the genders (P > 0.05). A statistically significant positive correlation was observed between attitude and behavior on practicing endodontics in rural settings among study subjects (P < 0.05). CONCLUSION: These findings highlights the necessity for taking initiatives to enhance the community-based dental education programs by various dental colleges for improving oral health care access for rural and isolated populations.

Investigations of Dimethylglycine, Glycine Betaine, and Ectoine Uptake by a Betaine-Carnitine-Choline Transporter Family Transporter with Diverse Substrate Specificity in Vibrio Species.

Fluctuations in osmolarity are one of the most prevalent stresses to which bacteria must adapt, both hypo- and hyperosmotic conditions. Most bacteria cope with high osmolarity by accumulating compatible solutes (osmolytes) in the cytoplasm to maintain the turgor pressure of the cell. Vibrio parahaemolyticus, a halophile, utilizes at least six compatible solute transporters for the uptake of osmolytes: two ABC family ProU transporters and four betaine-carnitine-choline transporter (BCCT) family transporters. The full range of compatible solutes transported by this species has yet to be determined. Using an osmolyte phenotypic microarray plate for growth analyses, we expanded the known osmolytes used by V. parahaemolyticus to include N,N-dimethylglycine (DMG), among others. Growth pattern analysis of four triple-bccT mutants, possessing only one functional BCCT, indicated that BccT1 (VP1456), BccT2 (VP1723), and BccT3 (VP1905) transported DMG. BccT1 was unusual in that it could take up both compounds with methylated head groups (glycine betaine [GB], choline, and DMG) and cyclic compounds (ectoine and proline). Bioinformatics analysis identified the four coordinating amino acid residues for GB in the BccT1 protein. In silico modeling analysis demonstrated that GB, DMG, and ectoine docked in the same binding pocket in BccT1. Using site-directed mutagenesis, we showed that a strain with all four residues mutated resulted in the loss of uptake of GB, DMG, and ectoine. We showed that three of the four residues were essential for ectoine uptake, whereas only one of the residues was important for GB uptake. Overall, we have demonstrated that DMG is a highly effective compatible solute for Vibrio species and have elucidated the amino acid residues in BccT1 that are important for the coordination of GB, DMG, and ectoine transport.IMPORTANCEVibrio parahaemolyticus possesses at least six osmolyte transporters, which allow the bacterium to adapt to high-salinity conditions. In this study, we identified several additional osmolytes that were utilized by V. parahaemolyticus We demonstrated that the compound DMG, which is present in the marine environment, was a highly effective osmolyte for Vibrio species. We determined that DMG is transported via BCCT family carriers, which have not been shown previously to take up this compound. BccT1 was a carrier for GB, DMG, and ectoine, and we identified the amino acid residues essential for the coordination of these compounds. The data suggest that for BccT1, GB is more easily accommodated than ectoine in the transporter binding pocket.

CBCT in Advanced Dental Education: A Survey of U.S. Postdoctoral Periodontics Programs.

Historically, predoctoral and advanced dental education programs used two-dimensional panoramic and periapical radiographs for implant planning. Three-dimensional (3D) Cone Beam Computed Tomography (CBCT) imaging has improved visualization of anatomic structures that can positively influence implant planning and surgical implant placement. The aim of this study was to assess how U.S. postdoctoral periodontics programs have incorporated CBCT technology into their curricula. A ten-question survey was sent to all 57 U.S. postdoctoral periodontics programs in November-December 2018. Thirty-seven responses were received, for a 65% response rate. All participating programs reported providing residents access to CBCT machines, and most of their residents received some training in the acquisition and interpretation of CBCT images. Nearly all (95%) participating programs provided training to apply implant planning software. Among the participating programs, 14% reported using a surgical guide fabricated with a CBCT scan 76-100% of the time, and 60% reported obtaining a CBCT scan for implant cases 76-100% of the time. These results suggest that, while residents are receiving training in CBCT and implant planning, it is not used often. There may be merit in adopting the American Academy of Oral and Maxillofacial Radiology's recommendation to use 3D imaging for all implant planning, with CBCT as the imaging modality of choice.

Endodontic Management of Maxillary Second Molar Tooth with a Single Root and Single Canal.

Comprehensive understanding of variations in the root canal morphology of a maxillary molar is useful for performing successful endodontic treatment in such cases. This case report describes endodontic management of a case with such aberrant root canal morphology of a maxillary second molar having a single root and single canal.

Regenerative Evaluation of Immature Roots using PRF and Artificial Scaffolds in Necrotic Permanent Teeth: A Clinical Study.

AIM: The aim of this study is to evaluate and compare the regenerative potential of natural scaffold [platelet-rich fibrin (PRF)] and artificial scaffolds (commercially available collagen, placentrex, and chitosan) in necrotic immature permanent teeth. MATERIALS AND METHODS: Necrotic immature permanent maxillary incisors with or without radiographic evidence of periapical lesion were included. Access opening was done under rubber dam isolation. Canal disinfection was done using minimal instrumentation, copious irrigation, and double antibiotic paste as interappointment medicament for 4 weeks. After 4 weeks, asymptomatic teeth were divided into four groups on the basis of scaffolds used for the revascularization procedure: group I (PRF); group II (collagen); group III (placentrex); group IV (chitosan). The clinical and radiographic evaluations of teeth were done at 3, 6, and 12 months after the procedure and compared with baseline records. RESULTS: Clinically, patients were completely asymptomatic throughout the study period. Radiographically, all cases showed an improvement in terms of periapical healing, apical closure, root lengthening, and dentinal wall thickening. PRF and collagen gave better results than placentrex and chitosan in terms of periapical healing, apical closure, and dentinal wall thickening. CONCLUSION: Revascularization procedure is more effective and conservative over apexification in the management of necrotic immature permanent teeth. This study has shown that PRF and collagen are better scaffolds than placentrex and chitosan for inducing apexogenesis in immature necrotic permanent teeth.

Role of mir-15a/16-1 in early B cell development in a mouse model of chronic lymphocytic leukemia.

In both human chronic lymphocytic leukemia (CLL) and the New Zealand Black (NZB) murine model of CLL, decreased levels of microRNAs miR-15a/16 play an important role in the disease. Here we investigate the effects of this microRNA on early steps of B cell development and the capacity of miR-15a-deficient hematopoietic stem cells (HSC) and B1 progenitor cells (B1P) to reproduce CLL-like phenotype both in vitro and in vivo. Our results demonstrate that both miR-15a deficient HSC and B1P cells are capable of repopulating irradiated recipients and produce higher numbers of B1 cells than sources with normal miR-15a/16 levels. Furthermore, induced pluripotent stem (iPS) cells derived for the first time from NZB mice, provided insights into the B cell differentiation roadblock inherent in this strain. In addition, exogenously delivered miR-15a into the NZB derived B cell line provided valuable clues into novel targets such as Mmp10 and Mt2. Our data supports the hypothesis that miR-15a/16 deficient stem cells and B1Ps experience a maturation blockage, which contributes to B1 cells bias in development. This work will help understand the role of miR-15a in early events of CLL and points to B1P cells as potential cells of origin for this incurable disease.

Variation in Location of the Mandibular Foramen/Inferior Alveolar Nerve Complex Given Anatomic Landmarks Using Cone-beam Computed Tomographic Scans.

INTRODUCTION: The inferior alveolar nerve (IAN) injection is 1 of the most commonly administered and useful injections in the field of dentistry. Practitioners use intraoral anatomic landmarks, which vary greatly among patients. The objective of this study was to assist practitioners by identifying a range of normal variability within certain landmarks used in delivering IAN anesthesia. METHODS: A total of 203 randomly selected retrospective cone-beam computed tomographic scans were obtained from the Midwestern University Dental Institute cone-beam computed tomographic database. InVivoDental5.0 volumetric imaging software (Anatomage, San Jose, CA) was used to measure 2 important parameters used in locating the mandibular foramen (MF)/IAN complex: (1) the angle from the contralateral premolar contact area to the MF and (2) the distance above the mandibular occlusal plane to the center of the MF. The variation of these measurements was compared with established reference values and statistically analyzed using a 1-sample t test. RESULTS: The angle from the contralateral premolar contact area to the MF for the right and left sides was 42.99° and 42.57°, respectively. The angulations varied significantly from the reference value of 45° (P < .001). The minimum height above the mandibular occlusal plane for the right and left sides was 9.85 mm and 9.81 mm, respectively. The heights varied significantly from the minimum reference value of 6 mm but not the maximum reference value of 10 mm (P < .001). CONCLUSIONS: Orienting the syringe barrel at an angulation slightly less than 45° and significantly higher than 6 mm above the mandibular occlusal plane can aid in successfully administering anesthesia to the MF/IAN complex.