Dissolution, dislocation and dimensional changes of endodontic sealers after a solubility challenge: a micro-CT approach

AIM

To evaluate, using a novel micro-CT approach, the solubility and dimensional changes of an MTA-based sealer inside the root canal system after a solubility challenge. The MTA-based material (MTA Fillapex) was compared to a gold standard epoxy-based endodontic sealer (AH Plus).

METHODOLOGY

Ten human mandibular premolars with a single canal were divided randomly into two groups (n = 5) according to the sealer used. The canals were instrumented using the Reciproc System (VDW) with a R40 file and filled with R40 gutta-percha cones and one of the sealers. The filled canals were immediately scanned in a micro-CT, and after that, the teeth were immersed in 20 mL phosphate-buffered saline (PBS) at 37 °C for 7 days, when they were removed and rescanned. Final image stacks were registered against the initial stacks and the numerical difference between the initial and final volume of the filling material was obtained. Calculations were performed to identify dimensional changes of the filling material. All image stacks were 3D rendered to disclose areas of dislocation of the filling material inside or outside the root canal. The Shapiro-Wilk's test revealed that data were normally distributed; thus, the Student's t-test was used to detect statistically significant changes, assuming a 5% α-error.

RESULTS

No significant changes were seen for the percentage volume of material lost after the solubility challenge for both AH Plus and MTA Fillapex groups (1.44% and 1.16%, respectively). A significant difference was, however, found for the volume of filling material which revealed dimensional changes after the solubility test (6.68% for MTA Fillapex and 1.09% for AH Plus). In fact, observation of 3D models disclosed that MTA Fillapex was associated with material extrusion through the foramen in all but one sample. In AH Plus filled samples, no material extrusion was detected.

CONCLUSIONS

Although the solubility of both sealers was similar using this novel micro-CT approach, MTA Fillapex was associated with significant dimensional changes related to material extrusion through the apex after PBS storage compared to AH Plus.

Influence of electronic apex locators and a gutta-percha heating device on implanted cardiac devices: an in vivo study

AIM

To evaluate the potential for electromagnetic interference (EMI) of electronic apex locators (EALs) and a gutta-percha heating device (HD) in patients with implantable cardiac pacemakers (ICPs) or cardioverter-defibrillators (ICDs).

METHODOLOGY

Two types of EALs (Romiapex A-15 and Novapex) and a HD (Touch'n Heat) were tested in patients followed in an outpatient clinic for cardiac arrhythmias. The heart rhythm was monitored on a computer screen during all experimental phases. After baseline data collection, the patient held each appliance (turned on) for 30 s, simulating their clinical use. If background noise was detected on the cardiac monitor, the sensitivity of the ICP/ICD was lowered by the cardiologist to evaluate the intensity of the detected EMI.

RESULTS

Twelve patients were evaluated (5 female and 7 male), and in nine instances, background noise in their cardiac devices related to the use of the endodontic devices was detected (6 patients). After lowering the sensitivity of the cardiac implants, three patients had more severe EMI in six instances, including pauses in ICP function. The presence of a symptomatic or asymptomatic pause was related to the patient's underlying heart rhythm. The HD device produced background noise more often compared to EALs. These were associated with more severe types of EMI.

CONCLUSION

The EALs and gutta-percha HD were capable of causing background noise detection or pauses in cardiac implants in vivo. The use of electronic dental devices nearby patients with cardiac implants should be carefully considered in clinical practice.

Exploiting the potential of free software to evaluate root canal biomechanical preparation outcomes through micro-CT images

AIM

To propose an automated image processing routine based on free software to quantify root canal preparation outcomes in pairs of sound and instrumented roots after micro-CT scanning procedures.

METHODOLOGY

Seven mesial roots of human mandibular molars with different canal configuration systems were studied: (i) Vertucci's type 1, (ii) Vertucci's type 2, (iii) two individual canals, (iv) Vertucci's type 6, canals (v) with and (vi) without debris, and (vii) canal with visible pulp calcification. All teeth were instrumented with the BioRaCe system and scanned in a Skyscan 1173 micro-CT before and after canal preparation. After reconstruction, the instrumented stack of images (IS) was registered against the preoperative sound stack of images (SS). Image processing included contrast equalization and noise filtering. Sound canal volumes were obtained by a minimum threshold. For the IS, a fixed conservative threshold was chosen as the best compromise between instrumented canal and dentine whilst avoiding debris, resulting in instrumented canal plus empty spaces. Arithmetic and logical operations between sound and instrumented stacks were used to identify debris. Noninstrumented dentine was calculated using a minimum threshold in the IS and subtracting from the SS and total debris. Removed dentine volume was obtained by subtracting SS from IS.

RESULTS

Quantitative data on total debris present in the root canal space after instrumentation, noninstrumented areas and removed dentine volume were obtained for each test case, as well as three-dimensional volume renderings.

CONCLUSION

After standardization of acquisition, reconstruction and image processing micro-CT images, a quantitative approach for calculation of root canal biomechanical outcomes was achieved using free software.

[Copper intoxication decreases lifespan and induces neurologic alterations in Drosophila melanogaster]

Wilson disease is a hereditary disorder caused by mutations of the ATP7B gene, which leads to intoxication with copper as a result of an unbalance of copper homeostasis. The clinical manifestations resulting from this intoxication are related to the affectation of liver and the encephalon in most cases. Several animal models are currently available for the study of the malady. However, in such models no neurological symptoms are observed, which limits their use for the study of pathogenic effects of this disease on the central nervous system. The aim of the present study was to evaluate if copper feeding could induce a disease state in Drosophila melanogaster to model Wilson disease. The effect of the feeding of copper at the doses of 31 microM and 47 microM on the survival was initially evaluated. Next, behavioral experiments were conducted to determine whether the motor performance was altered by the 47 microM concentration. The results suggest that copper treatment decreases the viability of the flies. In addition, the decrease of viability was associated to an increase and decrease of spontaneous motor activity at early and late stages of the intoxication, respectively. Finally, the role of the dopaminergic neurotransmission system on the observed motor alterations was evaluated. The dopamine precursor L-dopa increased motor activity. In contrast, D2 receptor antagonist, Fluphenazine, was able to block both the increase and decrease of motor activity scores induced by copper. These results suggest that Drosophila melanogaster could be used as a model organism for the study of possible interventions with potential neuroprotective effects in Wilson disease.

Effects on subjective and objective alertness and sleep in response to evening light exposure in older subjects

Evening bright light exposure is reported to ameliorate daytime sleepiness and age-related sleep complaints, and also delays the timing of circadian rhythms. We tested whether evening light exposure given to older adults with sleep-wake complaints would delay the timing of their circadian rhythms with respect to their sleep timing, thereby reducing evening sleepiness and improving subsequent sleep quality. We examined the impact of evening light exposure from two different light sources on subjective alertness, EEG activity during wakefulness, and sleep stages. Ten healthy older adults with sleep complaints (mean age=63.3 years; 6F) participated in a 13-day study. After three baseline days, circadian phase was assessed. On the evening of days 5-8 the subjects were exposed for 2h to either polychromatic blue-enriched white light or standard white fluorescent light, and on the following day circadian phase was re-assessed. Subjects were allowed to leave the laboratory during all but the two days when the circadian phase assessment took place. Evening assessments of subjective alertness, and wake and sleep EEG data were analyzed. Subjective alertness and wake EEG activity in the alpha range (9.75-11.25 Hz) were significantly higher during light exposures when compared to the pre-light exposure evening (p<0.05). The light exposures produced circadian phase shifts and significantly prolonged latency to rapid eye-movement (REM) sleep for both light groups (p<0.05). The increase in wake EEG alpha activity during the light exposures was negatively correlated with REM sleep duration (p<0.05). Evening light exposure could benefit older adults with early evening sleepiness, without negatively impacting the subsequent sleep episode.

Acute hepatitis due to dengue virus in a chronic hepatitis patient

We present a case of acute hepatitis caused by dengue virus, with a significant increase in aspartate transferase and alanine transferase levels in a chronic hepatitis patient attended at the Cane Sugar Planters Hospital of Campos dos Goytacazes, RJ.

Prolactin induces adrenal hypertrophy

Although adrenocorticotropic hormone is generally considered to play a major role in the regulation of adrenal glucocorticoid secretion, several reports have suggested that other pituitary hormones (e.g., prolactin) also play a significant role in the regulation of adrenal function. The aim of the present study was to measure the adrenocortical cell area and to determine the effects of the transition from the prepubertal to the postpubertal period on the hyperprolactinemic state induced by domperidone (4.0 mg kg-1 day-1, sc). In hyperprolactinemic adult and young rats, the adrenals were heavier, as determined at necropsy, than in the respective controls: adults (30 days: 0.16 +/- 0.008 and 0.11 +/- 0.007; 46 days: 0.17 +/- 0.006 and 0.12 +/- 0.008, and 61 days: 0.17 +/- 0.008 and 0.10 +/- 0.004 mg for treated and control animals, respectively; P < 0.05), and young rats (30 days: 0.19 +/- 0.003 and 0.16 +/- 0.007, and 60 days: 0.16 +/- 0.006 and 0.13 +/- 0.009 mg; P < 0.05). We selected randomly a circular area in which we counted the nuclei of adrenocortical cells. The area of zona fasciculata cells was increased in hyperprolactinemic adult and young rats compared to controls: adults: (61 days: 524.90 +/- 47.85 and 244.84 +/- 9.03 microm2 for treated and control animals, respectively; P < 0.05), and young rats: (15 days: 462.30 +/- 16.24 and 414.28 +/- 18.19; 60 days: 640.51 +/- 12.91 and 480.24 +/- 22.79 microm2 ; P < 0.05). Based on these data we conclude that the increase in adrenal weight observed in the hyperprolactinemic animals may be due to prolactin-induced adrenocortical cell hypertrophy.

Clinical and diagnostic aspects of intestinal microsporidiosis in HIV-infected patients with chronic diarrhea in Rio de Janeiro, Brazil

The objectives of this study were to determine both the prevalence of microsporidial intestinal infection and the clinical outcome of the disease in a cohort of 40 HIV-infected patients presenting with chronic diarrhea in Rio de Janeiro, Brazil. Each patient, after clinical evaluation, had stools and intestinal fragments examined for viral, bacterial and parasitic pathogens. Microsporidia were found in 11 patients (27.5%) either in stools or in duodenal or ileal biopsies. Microsporidial spores were found more frequently in stools than in biopsy fragments. Samples examined using transmission electron microscopy (n=3) or polymerase chain reaction (n=6) confirmed Enterocytozoon bieneusi as the causative agent. Microsporidia were the only potential enteric pathogens found in 5 of the 11 patients. Other pathogens were also detected in the intestinal tract of 21 patients, but diarrhea remained unexplained in 8. We concluded that microsporidial infection is frequently found in HIV infected persons in Rio de Janeiro, and it seems to be a marker of advanced stage of AIDS.

Stability, precision, and near-24-hour period of the human circadian pacemaker

Regulation of circadian period in humans was thought to differ from that of other species, with the period of the activity rhythm reported to range from 13 to 65 hours (median 25.2 hours) and the period of the body temperature rhythm reported to average 25 hours in adulthood, and to shorten with age. However, those observations were based on studies of humans exposed to light levels sufficient to confound circadian period estimation. Precise estimation of the periods of the endogenous circadian rhythms of melatonin, core body temperature, and cortisol in healthy young and older individuals living in carefully controlled lighting conditions has now revealed that the intrinsic period of the human circadian pacemaker averages 24.18 hours in both age groups, with a tight distribution consistent with other species. These findings have important implications for understanding the pathophysiology of disrupted sleep in older people.

Ganciclovir prophylaxis for cochlear pathophysiology during experimental guinea pig cytomegalovirus labyrinthitis

The effectiveness of the antiviral agent ganciclovir (9-[1,3-dihydroxy-2-propoxymethyl]guanine) against guinea pig cytomegalovirus was tested in vitro in guinea pig embryonic fibroblasts and in vivo in an experimental guinea pig cytomegalovirus labyrinthitis model. In vitro, ganciclovir completely prevented guinea pig cytomegalovirus infection of guinea pig embryonic fibroblasts at concentrations above 32.6 micrograms/ml. In vivo, antibody-negative animals had an average 17-dB elevation in their auditory nerve compound action potential thresholds (P less than 0.01, t test) and showed signs bilaterally of guinea pig cytomegalovirus labyrinthitis 8 days after intrathecal inoculation of virus. Ganciclovir administration starting 1 day before inoculation prevented the development of both cochlear histopathologic change and hearing loss. Guinea pig cytomegalovirus meningitis was observed in both the drug-treated and untreated groups. High-pressure liquid chromatography confirmed the presence of ganciclovir in the serum, perilymph, and cerebrospinal fluid of the drug recipients. Prophylactic ganciclovir thus can protect the cochlea from the histopathologic changes and hearing loss normally associated with experimental guinea pig cytomegalovirus labyrinthitis.