Attenuation of orthodontically induced inflammatory root resorption by using low-intensity pulsed ultrasound as a therapeutic modality- a systematic review.

Ultrasound is an effective tool for both diagnostic and therapeutic applications. As an imaging tool, ultrasound has mostly been used for real-time noninvasive diagnostic imaging. As ultrasound propagates through a material, a reflected radio-frequency (RF) signal is generated when encountering a mismatch in acoustic impedance. While traditionally recognized for its diagnostic imaging capabilities, the application of ultrasound has broadened to encompass therapeutic interventions, most notably in the form of Low-Intensity Pulsed Ultrasound (LIPUS). Low-Intensity Pulsed Ultrasound (LIPUS) is a form of mechanical energy transmitted transcutaneously by high-frequency acoustic pressure waves. The intensity of LIPUS (30 mW/cm2) is within the range of ultrasound intensities used for diagnostic purposes (1-50 mW/cm2) and is regarded as non-thermal, non-destructive, permeating living tissues and triggering a cascade of biochemical responses at the cellular level. The LIPUS device produces a 200 µs burst of 1.5 MHz acoustic sine waves, that repeats at a modulation frequency of 1 kHz and provides a peak pressure of 30 mW/cm2. Low-intensity pulsed ultrasound (LIPUS) forms one of the currently available non-invasive healing-enhancing devices besides electro-stimulation (pulsed electro-magnetic field, PEMF). This modality has been leveraged to enhance drug delivery, expedite injury recovery, improve muscle mobility, alleviate joint stiffness and muscle pain, and enhance bone fracture healing. Although LIPUS has been embraced within various medical disciplines, its integration into standard dental practices is still in its nascent stages, signifying an unexplored frontier with potentially transformative implications. Low-intensity pulsed ultrasound (LIPUS) has emerged as an attractive adjuvant therapy in various dental procedures, such as orthodontic treatment and maxillary sinus augmentation. Its appeal lies in its simplicity and non-invasive nature, positioning LIPUS as a promising avenue for clinical innovation. One particular area of interest is orthodontically induced inflammatory root resorption (OIIRR), an oftenunavoidable outcome of the orthodontic intervention, resulting in the permanent loss of root structure. Notably, OIIRR is the second most common form of root resorption (RR), surpassed only by root resorption related to pulpal infection. Given the high prevalence and potential long-term consequences of OIIRR, this literature review seeks to evaluate the efficacy of LIPUS as a therapeutic approach, with an emphasis on assessing its capacity to reduce the severity of OIIRR to a level of clinical significance. To conduct this systematic review, a comprehensive automated literature search was executed across multiple databases, including MEDLINE, Embase, PsycINFO, Web of Knowledge, Scopus, CINAHL, LILACS, SciELO, Cochrane, PubMed, trials registries, 3ie, and Google Scholar. Both forward and backward citation tracking was employed, encompassing studies published from database inception through January 2009 to April 2023. The review focused on randomized controlled trials (RCTs) that specifically evaluated the effects of low-intensity pulsed ultrasound therapy on orthodontically induced inflammatory root resorption (OIIRR), without restrictions of publication date. A stringent selection criterion was applied, and only studies demonstrating high levels of statistical significance were included. Ultimately, fourteen studies met the inclusion criteria and were subjected to further analysis. The overall quality of the included randomized controlled trials (RCTs) was rigorously assessed utilizing the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. This analysis revealed certain methodological limitations that posed challenges in drawing definitive conclusions from the available evidence. Despite these constraints, the review offers invaluable insights that can inform and guide future research. Specifically, it delineates recommendations for targeted populations, necessary interventions, appropriate outcome measures, suitable study designs, and essential infrastructure to facilitate further investigations. The synthesis of these insights aims to enhance the development and application of low-intensity pulsed ultrasound therapy within the field of dentistry, thereby contributing to improved patient outcomes.

Challenges of E-Learning: Behavioral Intention of Academicians to Use E-Learning during COVID-19 Crisis.

The COVID-19 crisis demanded that all educational activities should be performed virtually to follow social distancing guidelines. Therefore, there was a need to perform a research study to assess the effects of external factors on the perceived usefulness, ease of use of e-learning, and the further effect of these perceptions on attitude and intent to use e-learning by using the technology acceptance model (TAM) among academicians at higher education institutions in the Kingdom of Saudi Arabia. METHODS: A cross-sectional study was conducted, and data were collected from 263 academicians across Saudi Arabia through an online survey questionnaire using a non-probability purposive sampling technique and analyzed and tested using the SPSS and Smart PLS software. RESULTS: This study found that self-efficacy was positively associated with perceived usefulness at ß = 0.143 and p < 0.05, but it had no association with perceived ease of use at ß = 0.057 at p > 0.05. System accessibility had a significant and positive relationship with perceived usefulness and perceived ease of use at ß = 0.283, ß = 0.247, and p < 0.01, respectively. Self-efficacy had a positive effect on perceived usefulness, whereas the subjective norm had no relationship with perceived usefulness and perceived ease of use at ß = -0.065 and ß = -0.012 at p > 0.05, respectively. Perceived ease of use and perceived usefulness were positively related to attitude towards use, which has a significant influence on intention to use e-learning. CONCLUSION: Perceived ease of application is the most significant factor (ß = 0.556) in developing the attitude among academicians to practice e-learning, followed by perceived usefulness (ß = 0.262). Moreover, it can be concluded that system accessibility has a stronger influence on developing perception among academicians about the expediency and ease of application of e-learning than self-efficacy.

Loss of DNA repair mechanisms in cardiac myocytes induce dilated cardiomyopathy.

Cardiomyopathy is a progressive disease of the myocardium leading to impaired contractility. Genotoxic cancer therapies are known to be potent drivers of cardiomyopathy, whereas causes of spontaneous disease remain unclear. To test the hypothesis that endogenous genotoxic stress contributes to cardiomyopathy, we deleted the DNA repair gene Ercc1 specifically in striated muscle using a floxed allele of Ercc1 and mice expressing Cre under control of the muscle-specific creatinine kinase (Ckmm) promoter or depleted systemically (Ercc1-/D mice). Ckmm-Cre+/- ;Ercc1-/fl mice expired suddenly of heart disease by 7 months of age. As young adults, the hearts of Ckmm-Cre+/- ;Ercc1-/fl mice were structurally and functionally normal, but by 6-months-of-age, there was significant ventricular dilation, wall thinning, interstitial fibrosis, and systolic dysfunction indicative of dilated cardiomyopathy. Cardiac tissue from the tissue-specific or systemic model showed increased apoptosis and cardiac myocytes from Ckmm-Cre+/- ;Ercc1-/fl mice were hypersensitive to genotoxins, resulting in apoptosis. p53 levels and target gene expression, including several antioxidants, were increased in cardiac tissue from Ckmm-Cre+/- ;Ercc1-/fl and Ercc1-/D mice. Despite this, cardiac tissue from older mutant mice showed evidence of increased oxidative stress. Genetic or pharmacologic inhibition of p53 attenuated apoptosis and improved disease markers. Similarly, overexpression of mitochondrial-targeted catalase improved disease markers. Together, these data support the conclusion that DNA damage produced endogenously can drive cardiac disease and does so mechanistically via chronic activation of p53 and increased oxidative stress, driving cardiac myocyte apoptosis, dilated cardiomyopathy, and sudden death.

Retentive Forces and Deformation of Fitting Surface in RPD Clasp Made of Polyether-Ether-Ketone (PEEK).

BACKGROUND: Polyetheretherketone (PEEK) has provided the option to fabricate RPDs with aesthetics unlike metal RPDs, but little attention has been paid to its suitability, especially towards the retentive forces and deformation of the clasp. This study aimed to examine the retentive forces and the fitting surface (inner surface) deformation of clasps made from PEEK and compare it with cobalt-chromium (Co-Cr) clasp. METHODS: Forty-two circumferential clasps (14 Co-Cr and 28 PEEK) were fabricated and divided into two groups with clasp undercuts (0.25 mm and 0.5 mm) with thicknesses of 1 mm and 1.5 mm. Each was examined for retentive forces after cycle test on its abutment for 360 cycles. Initial and final retentive forces were recorded. The fitting surface deformation was determined using 3-Matic research analysis software. RESULTS: The results revealed that highest mean initial retentive force was of Co-Cr clasps with 0.50 mm undercut 22.26 N (±10.15 N), and the lowest was the 1 mm PEEK clasps with 0.25 mm undercut 3.35 N (±0.72 N) and highest mean final retentive force was the Co-Cr clasps with 0.50 mm undercut 21.40 N (±9.66 N), and the lowest was the 1 mm PEEK clasps with 0.25 mm undercut 2.71 N (±0.47 N). PEEK clasps had a lower retentive force than Co-Cr clasps with 0.50 undercut. PEEK clasps (1.5 mm) at 0.25 mm undercut had the least deformation (35.3 µm). PEEK showed significantly less deformation (p ≤ 0.014) than Co-Cr. CONCLUSION: The deformation of PEEK clasps fitting surface was lower than Co-Cr clasps and retentive forces were close to the Co-Cr clasps, suggesting the use of PEEK as an aesthetic clasp option for RPD framework.

In vitro Evaluation of Laser vs. Handpiece for Tooth Preparation.

Background: The erbium-doped yttrium aluminium garnet (Er:YAG) laser has been revealed to effectively ablate dental hard tissues, and its utilisation to caries eradication and cavity preparation is envisaged. Nevertheless, only a limited research has been performed on the Er:YAG laser's capacity to treat caries. Aim and Objectives: The efficiency of caries elimination with an Er:YAG laser in vitro was equated to that of traditional mechanical therapy in this study. Methodology: The investigation made use of teeth that had suffered from root caries. The Er:YAG laser was used to treat half of each tooth, while the other half was either removed with a conventional bur or left untouched as a control. Each therapy was evaluated in terms of how long it took to remove cavities, histological examinations of decalcified serial sections, scanning electron microscopy (SEM) analyses and the density of the dentin. Result: A longer treatment time was required for the Er:YAG laser to completely eradicate carious dentin because of its precise irradiation strategy. However, the Er:YAG laser was effective in removing diseased and softening carious dentin with little heat injury to neighbouring intact dentin, much as the bur treatment. It was also shown that the Er:YAG laser treatment had a lower amount of vibration than other methods. The SEM study of the lased dentin surface revealed characteristic micro-irregularities. Conclusion: The Er:YAG laser system appears to be a potential novel technical option for caries therapy, based on our findings.

An In Vitro study to Compare Dental Laser with other Treatment Modalities on Biofilm Ablation from Implant and Tooth Surfaces.

Background: Periodontal and peri-implant disorders are etiologically linked to bacterial biofilms. The researchers wanted to see how well the erbium-doped yttrium aluminum garnet (Er:YAG) laser removed bacterial biofilms along with attached epithelial cells (EC), gingival fibroblasts (GF), in addition to osteoblast-like cells (OC) dentin along with titanium surfaces compared to previous therapy methods. Methodology: 3.5 days were spent growing bacterial biofilms on standardized dentin and also titanium samplings using a sand-blasted along with the acid-etched surface. Following that, the specimens were positioned into pockets that had been formed artificially. The following approaches were used to remove biofilm: (1) Er:YAG, (2) photodynamic therapy (PDT), and (3) curette (CUR) along with supplementary PDT (CUR/PDT). The remaining biofilms' colony forming units (CFUs) were determined, as well as the attachment of EC, GF, in addition to OC. Analysis of variance with a posthoc least significant difference was utilized in the statistical analysis. Results: When compared to untreated dentin and titanium surfaces, all therapy strategies reduced total CFUs in statistically significant biofilms (p = 0.001). On the dentin, Er:YAG was as effective as CUR and PDT, but not as effective as CUR/PDT (p = 0.005). The application of Er:YAG on titanium surfaces leads to statistically significantly improved biofilm eradication equated to the supplementary three therapies (all p = 0.001). On untouched infested dentin and titanium surfaces, the counts of attached EC, GF, and OC were the lowermost. Atop the dentin, increased EC counts were detected after CUR/PDT (p = 0.006). On titanium, all cleaning procedures increased the counts of attached EC by a statistically significant amount (p = 0.001), with no variations between groups. After Er:YAG decontamination, there were statistically substantially elevated amounts of GF (p = 0.024) and OC (p = 0.001) than on untreated surfaces. Conclusion: The usage of Er:YAG laser to ablate subgingival biofilms and, specifically, to decontaminate titanium implant surfaces appears to be a promising strategy that needs further research.

Effect of Food Colorants on Color of Denture Base Acrylic Resins.

BACKGROUND: Acrylic resin has been successfully used for complete denture fabrication for many years. Color stability is very crucial clinical properties for dental materials, and color change may be an indicator of aging or damaging of materials. AIM AND OBJECTIVES: This study has been designed to determine the color stability of heat cure denture base acrylic resins in commonly consumed solutions causing stains. METHODOLOGY: Four hundred disc samples of four commercially used heat cure denture base resins (Trevalon®, DPI®, Veracril®, and Pyrax®) were fabricated (100 in each group). These were checked for any change in optical density by immersing them in four different staining solutions (tea, coffee, turmeric, and betel leaf, i.e., paan) and synthetic saliva for 1-month synthetic saliva was taken as control. The denture cleansers were also evaluated for their efficacy determined by their ability to remove the stains caused by the staining solutions. RESULTS: It was observed that Trevalon® showed least change in optical density and coffee illustrated the maximum potential for staining the denture base resins and is the most difficult to be removed using a denture cleanser. CONCLUSION: It can be concluded that Trevalon® demonstrated maximum color stability. Among the staining solutions, coffee caused maximum stains.

In vitro Results of Scanning Technique on Assessing Cement Thickness and Interfacial Nanoleakage of Luted CAD/CAM-Fabricated Fiber Posts.

BACKGROUND: Fiber posts are broadly used due to their good esthetics and elasticity close to that of dentin, which allows for uniform stress distribution within a root and lowers the possibility of nonrestorable root fractures. AIM AND OBJECTIVES: The study assessed the layer of cement thickness and interfacial nanoleakage of luted fiber posts which were fabricated with CAD/CAM technology following direct scanning of the post space (DS) method, scanning of a polyether impression of the post space (IS), and scanning of a plaster model of the post space (MS). METHODOLOGY: Ninety premolars were chosen randomly and were assigned to three groups according to the scanning technique. Posts were computer designed and milled from experimental fiber-reinforced composite blocks. RESULTS: The mean and standard deviation values of cement thickness, respectively, were: DS 172 ± 39 = m; IS 199 ± 55 = m, and MS MPa 272 ± 81 = m. The fiber posts fabricated following DS technique demonstrated superior performance compared to posts fabricated upon IS and MS, in terms of the post retention. The cement thickness did not differ between DS and IS, whereas in MS group, the cement layer was significantly thicker than in the remaining two groups. The scanning technique did not influence the sealing ability, as all groups showed comparable nanoleakage. CONCLUSION: Fiber posts fabricated following DS technique demonstrated superior performance. Furthermore, scanning technique did not influence the sealing ability, as all groups showed comparable nanoleakage.

Analysis of surface conditioning methods on core-veneer bond strength of CAD/CAM zirconia restorations.

BACKGROUND: The increased strength of zirconia has resulted in its widespread application in clinical dentistry. Nevertheless, the fracture of veneering porcelains remains one of the key reasons of failure. OBJECTIVE: The objective of this study was to compare and analyze the influence of surface conditioning methods on the core-veneer bond strength of zirconia restorations. METHODS: Thirty specimens of zirconia core with sizes 10 × 5 × 5 mm were layered with porcelain of sizes 5 × 3 × 3 mm. On the basis of different surface conditioning methods, four groups were made: Group I: abrasion with airborne alumina particles of 110 µm size, Group II: sandblasting with silica coated alumina particles of 50 µm in size, Group III (modified group): alteration with a coating of zirconia powder prior to sintering, and Group IV (control group): metal core specimens. The shear force of all specimens was tested using a universal testing machine with a 0.5 mm/min crosshead speed. One-way analysis of variance (ANOVA) and Tukey's post hoc pair wise comparison (p= 0.05) were performed to analyze the shear bond strength. A scanning electron microscope was used to assess the fractured specimens. RESULTS: A statistically significant difference was noted between the groups. The mean value of shear bond strength was 40.25 MPa for Group I, 41.93 MPa for Group II, 48.08 MPa for Group III and 47.01 MPa for Group IV. CONCLUSIONS: The modified zirconia group and control group demonstrated a significantly higher mean bond strength than that of Group I, where airborne particle abrasion was used. The scanning electron microscope showed that cohesive fracture in the porcelain veneers was the main problem of failure in altered zirconia. The modified zirconia specimens in Group III demonstrated significantly improved values of shear bond strength.

DNA damage-how and why we age?

Aging is a complex process that results in loss of the ability to reattain homeostasis following stress, leading, thereby, to increased risk of morbidity and mortality. Many factors contribute to aging, such as the time-dependent accumulation of macromolecular damage, including DNA damage. The integrity of the nuclear genome is essential for cellular, tissue, and organismal health. DNA damage is a constant threat because nucleic acids are chemically unstable under physiological conditions and vulnerable to attack by endogenous and environmental factors. To combat this, all organisms possess highly conserved mechanisms to detect and repair DNA damage. Persistent DNA damage (genotoxic stress) triggers signaling cascades that drive cells into apoptosis or senescence to avoid replicating a damaged genome. The drawback is that these cancer avoidance mechanisms promote aging. Here, we review evidence that DNA damage plays a causal role in aging. We also provide evidence that genotoxic stress is linked to other cellular processes implicated as drivers of aging, including mitochondrial and metabolic dysfunction, altered proteostasis and inflammation. These links between damage to the genetic code and other pillars of aging support the notion that DNA damage could be the root of aging.

Does the quality of residual alveolar bone apical to a periodontal lesion beneath the maxillary sinus play a vital role in preventing the extension of periodontal disease to maxillary sinus? A CBCT-assisted retrospective study.

BACKGROUND: The mucous membrane of the maxillary sinus is sensitivis susceptible to infection or inflammation adjacent to it, which may contribute to mucous membrane thickening (MMT). Residual alveolar bone quality (RABQ) is considered a quality of the remaining bone apical to periodontal defect adjoining to the floor of the maxillary sinus. OBJECTIVE: The current study aimed to analyze the minimum RABQ to prevent the extension of periodontal pathology from reaching maxillary sinus using cone-beam computed tomography (CBCT). METHODS: In this retrospective observational study, 240 sinus exposure CBCT records of 146 patients were evaluated. Patients with at least one sinus exposure were included. RABQ and MMT were calculated using CBCT inbuilt tools. RABQ was divided into four groups based on gray scale values (GSV). Statistical analysis was performed using one way ANOVA and independent sample t-tests. Correlation was completed applying Pearson's correlation coefficient. RESULTS: A significant difference (p< 0.05) was observed between the MMT values of the four RABQ groups. Inverse correlation was observed between mean MMT and GSV values. Mean MMT was higher than pathological MMT range (> 2 mm), with significant differences in groups A and B, where mean GSV values are less than 500. Mean GSV greater than 500 in groups C and D show non-pathological MMT. Prevalence of MMT is 91.4% if GSV is < 500 and 7.5% if GSV is > 500. CONCLUSIONS: Our study suggests that MMT is present if RABQ has GSV values < 500. Maxillary sinusitis and its etiology from periodontal pathology can be excluded based on RABQ adjoining periodontal lesion. Early detection and prompt treatment along with appropriate regenerative protocols can be performed to increase the RABQ. Further microbiological investigation is required to support the present results.

Loss of prdm1a accelerates melanoma onset and progression.

Melanoma is an aggressive, deadly skin cancer derived from melanocytes, a neural crest cell derivative. Melanoma cells mirror the developmental program of neural crest cells in that they exhibit the same gene expression patterns and utilize similar cellular mechanisms, including increased cell proliferation, epithelial-mesenchymal transition, and migration. Here we studied the role of neural crest regulator PRDM1 in melanoma onset and progression. In development, Prdm1a functions to promote neural crest progenitor fate, and in melanoma, we found that PRDM1 has reduced copy number and is recurrently deleted in both zebrafish and humans. When examining expression of neural crest and melanocyte development genes, we show that sox10 progenitor expression is high in prdm1a-/- mutants, while more differentiated melanocyte markers are reduced, suggesting that normally Prdm1a is required for differentiation. Data mining of human melanoma datasets indicates that high PRDM1 expression in human melanoma is correlated with better patient survival and decreased PRDM1 expression is common in metastatic tumors. When one copy of prdm1a is lost in the zebrafish melanoma model Tg(mitfa:BRAFV600E );p53-/- ;prdm1a+/- , melanoma onset occurs more quickly, and the tumors that form have a larger area with increased expression of sox10. These data demonstrate a novel role for PRDM1 as a tumor suppressor in melanoma.

Community acquired Clostridium difficile in an infant without antibiotic exposure.

Clostridium Difficile is the most common cause of hospital acquired and antibiotic associated diarrhoea, but it is important to note that this can be a colonizer. The rates of community carriage is not very well described in children. We hereby report a case of Community acquired Clostridium Difficile in an infant without antibiotic exposure.

Variations in the Compressive Strength of a Die Stone with Three Different Sulfates at Eight Different Concentrations: An In Vitro Study.

AIM: The present study aimed to evaluate the alteration in the compressive strength (CS) of the die stone with three different sulfate salt additives, each at eight various concentrations. MATERIALS AND METHODS: The specimens were prepared at specific dimensions (length: 2.5 cm and diameter: 2.5 cm) divided into three test groups based on the type of sulfate additives used [potassium sulfate (K2SO4), zinc sulfate (ZnSO4·H2O), and manganese sulfate (MnSO4·H2O)] and one control group, without any additives. Again, each group was divided into eight subgroups based on concentration of sulfates (ranging from 0.2% to 4%). A total of 375 specimens were tested. CS (in MPa) was evaluated after 72 hours of drying time, using an universal testing machine. STATISTICAL ANALYSIS: A one-way analysis of variance (ANOVA) was used for intergroup comparisons. Individual comparisons were done using the post hoc Tukey HSD analysis. RESULTS: All the three additives at all the concentrations have shown an inferior resistance to compressive forces when compared to the standard specimen. However, the least mean CS was observed at 0.8% of MnSO4 (10.95 MPa) and the highest was at 1% K2SO4 (25.28%). A highly significant difference (p < 0.001) was observed among the concentrations in all the three groups (K2SO4, MnSO4, and ZnSO4 groups) and F values were derived as 69.84, 24.29, and 130.52, respectively. At each concentration, comparisons between the groups have shown a significant difference (p < 0.05) at almost all concentrations. CONCLUSION: The CS of die stone is shown to be decreased with an increase in all three types of sulfate additives when compared to the control specimen. CLINICAL SIGNIFICANCE: Die stone is an often used gypsum material in the field of dentistry. Compressive strength of the die stone is crucial in prosthetic dentistry; chemical additives such as sulfate salts may increase the CS such that the die stone can withstand clinical and laboratory handling forces. How to cite this article: Vyas R, Vaddamanu SK, Gurumurthy V, et al. Variations in the Compressive Strength of a Die Stone with Three Different Sulfates at Eight Different Concentrations: An In Vitro Study. J Contemp Dent Pract 2019;20(11):1297-1306.

Assessment of Fracture Resistance Capacity of Different Core Materials with Porcelain Fused to Metal Crown: An in vitro Study.

Aim: The aim of the study was to evaluate the capacity to resist fracture in different core buildup materials with porcelain fused to metal (PFM) crown. Materials and methods: Totally, 45 mandibular single rooted first premolars were collected, which were sound along with similar shape and size. The teeth were sectioned at 15 mm above the root apex sparing the sound tooth structure. The teeth were endodontically treated with the crown-down technique using nickel-titanium (NiTi) instrumentation. The specimens were randomized into three groups as per the core materials used and were labeled accordingly. Group I consisted of dual-cured composite resin, group II consisted of glass ionomer reinforced with resin, and group III consisted of Miracle mix. Universal loading machine is used for measuring the compres-sive load applied to fracture the tooth. Results: The mean value of compressive strength was maximum in the dual cured composite resin (598.42 ± 22.64) followed by glass ionomer reinforced with resin (478.88 ± 26.74) and Miracle mix (442.16 ± 30.10). The results showed a significant difference statistically within the core materials used with p < 0.05. The results from the Tukey's post hoc test of multiple comparisons between dual-cured composite resin vs glass ionomer reinforced with resin, dual-cured composite resin vs Miracle mix, and glass ionomer reinforced with resin vs Miracle mix showed a highly statistical difference with p < 0.05, which is significant. Conclusion: This in vitro study showed that the dual-cured composite resin had maximum resistance to fracture compared with other core buildup materials on teeth which were endodonti-cally treated. Clinical significance: Restoration of a tooth which is structurally compromised is a tricky job for all the dentists. Restoring it with a proper core buildup material with adequate fracture resistance makes the tooth structure stable. The core material should be able to resist all types of occlusal forces and to distribute it equally within the tooth structure. Keywords: Core buildup, Crowns, Endodontically treated teeth, Fracture resistance.

Ligand-activated BMP signaling inhibits cell differentiation and death to promote melanoma.

Oncogenomic studies indicate that copy number variation (CNV) alters genes involved in tumor progression; however, identification of specific driver genes affected by CNV has been difficult, as these rearrangements are often contained in large chromosomal intervals among several bystander genes. Here, we addressed this problem and identified a CNV-targeted oncogene by performing comparative oncogenomics of human and zebrafish melanomas. We determined that the gene encoding growth differentiation factor 6 (GDF6), which is the ligand for the BMP family, is recurrently amplified and transcriptionally upregulated in melanoma. GDF6-induced BMP signaling maintained a trunk neural crest gene signature in melanomas. Additionally, GDF6 repressed the melanocyte differentiation gene MITF and the proapoptotic factor SOX9, thereby preventing differentiation, inhibiting cell death, and promoting tumor growth. GDF6 was specifically expressed in melanomas but not melanocytes. Moreover, GDF6 expression levels in melanomas were inversely correlated with patient survival. Our study has identified a fundamental role for GDF6 and BMP signaling in governing an embryonic cell gene signature to promote melanoma progression, thus providing potential opportunities for targeted therapy to treat GDF6-positive cancers.

In-vitro Evaluation of Transverse Strength of Repaired Heat Cured Denture Base Resins without Surface Treatment and with Chemical and Mechanical Surface Treatment.

BACKGROUND: Denture repair involves joining two parts of a fractured denture with a denture repair material. Hence, a substantial repairing system for denture base fracture should be there to elude frequent fracture. MATERIALS AND METHODS: Surface treatment of conventional heat cure denture base resin with different surface treatments (chemical ethyl acetate, and mechanical roughening with bur), with control group formed without surface treatment. Specimens were repaired with auto polymerizing acrylic resin using sprinkle on technique. The testing of the transverse strength of the repaired specimens was evaluated with three-point bending test on universal testing machine. RESULTS: The study revealed that surface chemical treatment with ethyl acetate improved the transverse strength of repaired heat cure denture base when compared with mechanical and control group. A two-way analysis of variance revealed that there was statistically significant difference in mean strengths of the three groups. CONCLUSION: Surface chemical treatment with ethyl acetate improved the transverse strength of the repaired heat cure denture base when compared with mechanical roughening with bur and group without surface treatment.

p53 attenuates AKT signaling by modulating membrane phospholipid composition.

The p53 tumor suppressor is the central component of a complex network of signaling pathways that protect organisms against the propagation of cells carrying oncogenic mutations. Here we report a previously unrecognized role of p53 in membrane phospholipids composition. By repressing the expression of stearoyl-CoA desaturase 1, SCD, the enzyme that converts saturated to mono-unsaturated fatty acids, p53 causes a shift in the content of phospholipids with mono-unsaturated acyl chains towards more saturated phospholipid species, particularly of the phosphatidylinositol headgroup class. This shift affects levels of phosphatidylinositol phosphates, attenuates the oncogenic AKT pathway, and contributes to the p53-mediated control of cell survival. These findings expand the p53 network to phospholipid metabolism and uncover a new molecular pathway connecting p53 to AKT signaling.

Morphological and Dimensional Characteristics of Dental Arch among Tribal and Non-tribal Population of Central India: A Comparative Study.

BACKGROUND: Differences in the dental arch among Bhil Aboriginals were investigated and compared with non-tribal individuals residing in a tribal zone of Central India. Plaster models (120) were made with the help of alginate impression of tribal adults as well as non-tribal adults residing in the same area. The supposition as aboriginals being primitive due to dietary practices maxillary arch size and mandibular arch size is distended in comparison to the non-tribal population as adaptation of soft refined diet has disrupted the growth of the jaws. Hence, an attempt was made to evaluate the arch widths of tribal population and to associate it with non-tribe population in the same area of Central India. MATERIALS AND METHODS: Difference in morphology and dimension of the maxillary and mandibular arches was aimed at Bhil tribes as well as non-tribal residents of tribe rich zone of Central India. The study was steered amid 120 individuals both tribal and non-tribe equally around 60 each through a well-organized out-reach program intermittently. Study models were made of dental arches of all participants. All measurements of the arch dimension were patent on the study casts using an electronic digital sliding caliper. Pair t-test was applied by using SPSS software version-19.0. RESULTS: In the maxillary arch, on appraisal the non-tribal and Bhil tribe's subjects, it showed a statistically significant difference in inter-incisor width (2.95 mm), inter-canine width (2.60 mm), arch depth (3.25 mm). While inter premolar width (0.20 mm) and inter molar width (0.80 mm) anterior arch length (0.60 mm), and posterior arch length (0.10 mm) showed statistically not significant difference between non-tribal population and Bhil tribe subjects. In the mandibular arch, it showed a statistically significant difference in inter-canine width (1.00 mm). Although, inter-incisor width (0.72 mm), inter-molar width (0.80 mm), arch depth (0.90 mm), anterior arch length (0.30 mm), posterior arch length (0.35 mm), and curve of Spee (0.13 mm) showed statistically not significant difference between general population and Bhil tribe subjects. CONCLUSION: When associated non-tribal population to Bhil tribes subjects, for the morphological and dimensional characteristics of dental arches Bhil tribe subjects exhibited: A narrower and shorter maxilla; reduced mandible size; smaller incisor widths for the maxillary and mandibular arches.

Quantitative evaluation and comparison of stress transmission characteristics of bar-clip and short coping overdenture attachments under dynamic loading: a photoelastic stress analysis.

STATEMENT OF PROBLEM: When two canine abutment teeth are used to support an overdenture prosthesis, optimal stress distribution to minimize forces to abutments is desired. PURPOSE: This study used photoelastic stress analysis to compare the stress patterns generated around canine abutments using two different overdenture retainer designs. MATERIALS AND METHODS: Two canine abutments were anchored in the photoelastic mandible and overdentures were fabricated using two different overdenture attachments. The fitting surface of dentures were lined with resilient layer of light bodied silicon rubberbase impression material to simulate oral mucosa. The attachments used were Bar-Clip and Short coping type. Verticalload of 5 to 50 lb was applied by jaw simulator. Resultant stress fringes were photographed and evaluated quantitatively. RESULTS: Bar-Clip type of attachment transmitted more amount of stress than short coping type transmitted. There was gross difference in magnitude of stresses between two types of retainers. CONCLUSION: As the retentivity of the attachment increased there was more stress concentration around the abutments.