Evaluation of Extrusion and Apical Seal of Thermafil™ Obturation with and without MTA as an Apical Barrier in Comparison with Lateral Condensation Technique: An In Vitro Study

AIM AND OBJECTIVE

This study aimed to compare the apical sealing ability and periapical extrusion in the Thermafil™ obturation technique, with and without an apical barrier of MTA, with lateral condensation technique.

MATERIALS AND METHODS

Sixty freshly extracted human central incisors were instrumented with the crown down technique and divided into three experimental groups. Group I: lateral condensation technique obturation, group II: Thermafil obturation (DENTSPLY Tulsa), and group III: this group was obturated into two parts; first MTA (ProRoot) was placed in apical 3 mm and later the remaining canal was obturated with Thermafil™ obturation technique (DENTSPLY Tulsa). AH Plus sealer was used in all the groups. Specimens of all the groups were layered with nail paint excluding the apical 3 mm. Twenty-four hours later, all the teeth were suspended in Black India ink for 48 hours. Finally, all the teeth were decalcified, rendered transparent and linear dye leakage and periapical extrusion was measured using ×60 magnification of stereomicroscope with an in-built ruler.

RESULTS

A Chi-square test done to evaluate periapical extrusion showed there was a significant difference found among all the groups (p < 0.05), whereas in case of linear apical dye leakage using a Student's "t" test showed there was no significant difference among all the groups (p > 0.05).

CONCLUSION

Despite showing apical leakage, the thermo-plasticized gutta-percha obturation technique can be advantageous when used with MTA as an apical barrier since there is no scope for apical extrusion along with the benefit of three-dimensional obturation of the root canal system when compared with the lateral condensation technique.

HOW TO CITE THIS ARTICLE

Rao AS, Mathur R, Shah NC, et al. Evaluation of Extrusion and Apical Seal of Thermafil™ Obturation with and without MTA as an Apical Barrier in Comparison with Lateral Condensation Technique: An In Vitro Study. Int J Clin Pediatr Dent 2020;13(S-1):S40-S44.

The effects of intranasal oxytocin on reward circuitry responses in children with autism spectrum disorder

BACKGROUND

Intranasal oxytocin (OT) has been shown to improve social communication functioning of individuals with autism spectrum disorder (ASD) and, thus, has received considerable interest as a potential ASD therapeutic agent. Although preclinical research indicates that OT modulates the functional output of the mesocorticolimbic dopamine system that processes rewards, no clinical brain imaging study to date has examined the effects of OT on this system using a reward processing paradigm. To address this, we used an incentive delay task to examine the effects of a single dose of intranasal OT, versus placebo (PLC), on neural responses to social and nonsocial rewards in children with ASD.

METHODS

In this placebo-controlled double-blind study, 28 children and adolescents with ASD (age: M = 13.43 years, SD = 2.36) completed two fMRI scans, one after intranasal OT administration and one after PLC administration. During both scanning sessions, participants completed social and nonsocial incentive delay tasks. Task-based neural activation and connectivity were examined to assess the impact of OT relative to PLC on mesocorticolimbic brain responses to social and nonsocial reward anticipation and outcomes.

RESULTS

Central analyses compared the OT and PLC conditions. During nonsocial reward anticipation, there was greater activation in the right nucleus accumbens (NAcc), left anterior cingulate cortex (ACC), bilateral orbital frontal cortex (OFC), left superior frontal cortex, and right frontal pole (FP) during the OT condition relative to PLC. Alternatively, during social reward anticipation and outcomes, there were no significant increases in brain activation during the OT condition relative to PLC. A Treatment Group × Reward Condition interaction revealed relatively greater activation in the right NAcc, right caudate nucleus, left ACC, and right OFC during nonsocial relative to social reward anticipation during the OT condition relative to PLC. Additionally, these analyses revealed greater activation during nonsocial reward outcomes during the OT condition relative to PLC in the right OFC and left FP. Finally, functional connectivity analyses generally revealed changes in frontostriatal connections during the OT condition relative to PLC in response to nonsocial, but not social, rewards.

CONCLUSIONS

The effects of intranasal OT administration on mesocorticolimbic brain systems that process rewards in ASD were observable primarily during the processing of nonsocial incentive salience stimuli. These findings have implications for understanding the effects of OT on neural systems that process rewards, as well as for experimental trials of novel ASD treatments developed to ameliorate social communication impairments in ASD.

Risk Factors for Cardiovascular Disease in Obese Children

OBJECTIVE

To study the prevalence of cardiovascular risk factors in pediatric obesity.

METHODS

50 obese children (age 5-17y) and 50 apparently healthy non-obese children (body mass index of over 95th percentile and between 5th to 95th percentiles, respectively) using Centre for Disease Control growth charts were included. Fasting blood sugar, lipid profile, insulin, homeostasis model assessment of insulin resistance, uric acid, fibrinogen, lipoprotein (a), homocysteine, malondialdehyde, ferric reducing ability of plasma and nitric oxide were measured.

RESULTS

Insulin, insulin resistance, triglycerides, uric acid, fibrinogen, malondialdehyde, ferric reducing ability of plasma and nitric oxide were significantly higher (P <0.001) in obese children. Body mass index showed significant positive correlation with insulin r=0.519, P<0.001; insulin resistance r =0.479, P<0.001; uric acid r= 0.289, P=0.005; fibrinogen r=0.461, P<0.001; and nitric oxide r=0.235, P=0.012.

Conclusion

Pediatric obesity is associated with dyslipidemia, oxidative stress, insulin resistance and endothelial dysfunction, which are cardiovascular risk factors and components of metabolic syndrome. These children must be targeted for lifestyle and dietary modification.

Autofluorescence spectroscopy of betel quid chewers and oral submucous fibrosis: A pilot study

Context:

Oral lesions related to the use of commercially available tobacco (gutkha) is going to pose a major challenge for health care providers in India. Therefore, techniques that are useful for mass screening of the public for early identification of pre-cancerous lesions and conditions are necessary to overcome this challenge.

Aims:

To identify the differences in autofluorescence spectra of normal oral mucosa, mucosa of betel quid chewers, and mucosa of oral sub mucous fibrosis.

Materials and Methods:

Group I consist of 15 individuals with clinical diagnosis of oral submucous fibrosis, Group II consists of 18 individuals without oral submucous fibrosis, having the habit of betel quid (gutkha) chewing and Group III consists of 18 normal individuals without the habit of betel quid chewing. Both males and females were included in the study with their age ranging from 18 to 53 years. In vivo fluorescence spectra were obtained using an optical fibre probe attached to Fluoromax-2 spectrofluorometer in the Department of Medical Physics, Anna University, Chennai, India.

Statistical Analysis Used:

Fisher's Chi square test was used for statistical analysis. Probability value (P value) was also obtained to discriminate the statistical differences between the three groups.

Results:

The averaged emission and excitation spectra of oral submucous fibrosis was significantly less compared to normal mucosa and betel quid chewers. The statistical findings showed significant differences (P<0.001) between oral submucous fibrosis and the other two groups.

Conclusions:

Fluorescence spectroscopy can be used effectively for diagnosing the individuals affected by OSMF. However, this technique was unable to discriminate the betel chewers mucosa from normal individuals.

Heterotopic salivary gland tissue: A report of two cases

The heterotopic salivary gland or salivary choristoma is defined as a tumor - like growth of otherwise normal salivary gland found in an abnormal location. In general, salivary gland tissue is not observed in the gingiva, with only isolated case reports having been found. The occurrence of the case in the midline, especially in the anterior two - thirds of the hard palate, has not been documented so far (PubMed search engine). It is apparent that these reported cases constitute a unique clinico -pathologic entity. Clinically, they appear as soft tissue tumors and are composed of lobules of salivary gland tissue.

Environmental risk assessment of genetically engineered herbicide-tolerant Zoysia japonica

Herbicide-tolerant Zoysia grass (Zoysia japonica Steud.) has been generated previously through Agrobacterium tumefaciens-mediated transformation. The genetically modified (GM) Zoysia grass survived Basta spraying and grew to maturity normally while the wild-type (WT) grass stopped growing and died. GM Zoysia grass will permit more efficient weed control for various turf grass plantings such as home lawns, golf courses, and parks. We examined the environmental/biodiversity risks of herbicide-tolerant GM Zoysia before applying to regulatory agencies for approval for commercial release. The GM and WT Zoysia grass' substantial trait equivalence, ability to cross-pollinate, and gene flow in confined and unconfined test fields were selectively analyzed for environmental/biodiversity effects. No difference between GM and WT Zoysia grass in substantial traits was found. To assess the potential for cross-pollination and gene flow, a non-selective herbicide, Basta, was used. Results showed that unintended cross-pollination with and gene flow from GM Zoysia grass were not detected in neighboring weed species examined, but were observed in WT Zoysia grass (on average, 6% at proximity, 1.2% at a distance of 0.5 m and 0.12% at a radius of 3 m, and 0% at distances over 3 m). On the basis of these initial studies, we conclude that the GM Zoysia grass generated in our laboratory and tested in the Nam Jeju County field does not appear to pose a significant risk when cultivated outside of test fields.

Levels of mercury in alligators (Alligator mississippiensis) collected along a transect through the Florida Everglades

As part of a multi-agency study of alligator health, 28 American alligators (Alligator mississippiensis) were captured along a transect through the Florida Everglades in 1999. Liver and tail muscle tissues were sampled and analyzed on a wet weight basis for total mercury (THg) using cold-vapor atomic absorption spectrophotometry. All tissues had detectable concentrations of THg that ranged from 0.6 to 17 mg/kg in liver and from 0.1 to 1.8 mg/kg in tail muscle. THg was more concentrated in liver tissue than tail muscle, but levels were highly correlated between tissues. THg concentrations in tissue differed significantly among locations, with animals from Everglades National Park (ENP) having mean concentrations of THg in liver (10.4 mg/kg) and tail muscle (1.2 mg/kg) that were two-fold higher than basin-wide averages (4.9 and 0.64 mg/kg, respectively). The reasons for higher contamination of ENP alligators were unclear and could not be explained by differences in sex, length, weight or animal age. While delta15N values were positively correlated with THg concentrations in tail muscle, spatial patterns in isotopic composition did not explain the elevated THg levels in ENP alligators. Therefore, it appears that ENP alligators were more highly exposed to mercury in their environment than individuals in other areas. Comparisons to a previous survey by Yanochko et al. [Arch Environ Contam Toxicol 32 (1997) 323] suggest that mercury levels have declined in some Everglades alligators since 1994.

RecX protein abrogates ATP hydrolysis and strand exchange promoted by RecA: insights into negative regulation of homologous recombination

In many eubacteria, coexpression of recX with recA is essential for attenuation of the deleterious effects of recA overexpression; however, the molecular mechanism has remained enigmatic. Here, we show that Mycobacterium tuberculosis RecX binds directly to M. tuberculosis RecA as well as M. smegmatis and E. coli RecA proteins in vivo and in vitro, but not single-stranded DNA binding protein. The direct association of RecX with RecA failed to regulate the specificity or extent of binding of RecA either to DNA or ATP, ligands that are central to activation of its functions. Significantly, RecX severely impeded ATP hydrolysis and the generation of heteroduplex DNA promoted by homologous, as well as heterologous, RecA proteins. These findings reveal a mode of negative regulation of RecA, and imply that RecX might act as an anti-recombinase to quell inappropriate recombinational repair during normal DNA metabolism.

Mercury in eggs and feathers of great egrets (Ardea albus) from the Florida Everglades

Great egret (Ardea albus) eggs and nestling feathers were collected for total mercury (THg) and methylmercury (MeHg) analysis from two colonies in the Florida Everglades in 1999 and 2000. THg was present in all eggs at a mean concentration of 0.39 +/- 0.19 microg/g fresh weight (n = 33, range = 0.08-0.86 microg/g). Egg-THg levels did not differ significantly between colonies or years. MeHg concentration in eggs was 0.35 +/- 0.18 microg/g fresh weight (n = 20, range = 0.05-0.82 microg/g,), and on average represented 85% of the THg found in the egg. Concentration of THg in feathers from egret nestlings, age 11-31 days, ranged from 1.4 to 8.6 microg/g dry weight. Feather-THg levels also did not differ significantly between colonies or years. THg concentrations in feathers, normalized based on bill length, were positively correlated to THg concentrations in eggs from the same clutch. Levels of THg in both eggs and feathers were lower in 1999 and 2000 than values reported for similar samples collected in 1993-95, indicating that MeHg exposure has decreased in the southern Everglades since the mid-1990s. THg levels in eggs and nestling feathers for the period of this study were below levels associated with toxic reproductive effects. Clutch size, fledging success, and brood size observed in this study were consistent for this species in the Everglades. Collectively, these results suggest that MeHg was not adversely affecting the reproductive performance of this population during the study.

Effect of naloxone on GnRH-induced LH and FSH release in buffalo, Bubalus bubalis

The effect of naloxone on GnRH-induced LH and FSH release was measured in buffaloes in luteal phase of estrous cycle. Animals were administered intravenously, naloxone/saline (50 mg/injection) every 15 min for 3 hr followed by GnRH (100 micrograms). Peripheral plasma LH and FSH concentrations were measured in blood samples collected at 15 min intervals from 1 hr prior to beginning of naloxone/saline treatment up to 3 hr post GnRH administration and every 30 min for the subsequent 3.5 hr. Between the animals of Group I administered naloxone and those of Group II given saline, GnRH-induced peak LH and FSH concentrations, the total LH and FSH released in response to GnRH, and the time to peak LH and FSH concentrations were not significantly different. The results of the present study suggest the absence of a direct effect of naloxone on pituitary responsiveness to GnRH.