COMPARATIVE EVALUATION OF MARGINAL SEALING ABILITY OF POSTERIOR PACKABLE COMPOSITE WITH OR WITHOUT LINERS USING DYE PENETRATION METHOD- AN INVITRO STUDY.

Condensable” or “packable” composites (Surefil) were introduced as an alternative to dental amalgam. However, concerns have been raised related to the ability of these stiffer materials to adequately adapt to internal surfaces. To offset this problem, low viscosity fiowable liners walls are recommended under packable composites. This study aimed at evaluating the effect of SDR and Ketac N100 liners on marginal sealing ability of High Density Surefil posterior packable composite. Methodology: Sixty permanent extracted molars were mounted in a modelling wax and box only Class II cavities were prepared on the mesial side with gingival seat 1mm above CEJ. Teeth were divided into 3 groups: Group (i) Surefil with SDR; Group (ii) Surefil with Ketac N 100; and Group (iii) Surefil without liner. After restoration, the teeth were immersed in Methylene blue dye, sectioned mesiodistally and then evaluated for leakage under Stereomicroscope. Results: None of the groups were free of microleakage. Surefil without liner (1.2±0.696) exhibited maximum microleakage followed by Ketac N100 group (0.9±0.718) and SDR group (0.8±0.523) showed least microleakage. Conclusion: Posterior packable composites should be lined by a resin based liner at the gingival margin to allow better seal

Diferencias en procesamiento cerebral visual temprano en niños con trastorno del déficit de atención / Differences in early visual cerebral processing in children with attention deficit / hyperactivity disorders with predominance of no attention

Para evaluar los procesos atencionales a estímulos visuales que no requieren repuesta motora, se llevó a cabo un estudio con potenciales evocados a 17 niños con trastornos del déficit de atención/ hiperactividad (TDAH-I) con predominio inatento y a 15 controles de edades entre 7 y 11 años. Se analizó la latencia y localización de fuentes de los potenciales evocados visuales tempranos P100 y N100 durante la realización de una tarea oddball visual (20% rayas horizontales y 80% verticales) en que las rayas verticales no exigían respuesta motora. Los resultados indican que los niños con TDAH-I procesan la información visual que no requiere respuesta motora con un mayor aumento de la actividad cerebral y mediante la vía temporal ventral mientras que el grupo control lo hace mediante la vía parietal dorsal. Este proceso neurobiológico de procesamiento de la información visual vía temporal ventral de los niños con TDAH-I podría deberse a alteraciones en los procesos emocionales que influyen directamente en el reconocimiento visual o a un déficit en el control de los procesos atencionales por parte de la vía parietal dorsal.

To evaluate attentional processes to visual stimuli that do not require motor response, a study with evoked potentials was carried out on 17 children with attention deficit disorder predominantly inattentive (ADDH-I) and 15 controls between the ages of 7 and 11 years. The latency and localization of sources of the early visual evoked potentials P100 and N100 were analyzed during the performance of a visual oddball task (20% horizontal and 80% vertical lines) where the vertical lines did not require motor response. The results indicate that ADDH-I group process visual information that does not require motor response with a greater increase in brain activity and through the ventral temporal pathway, while the control group does so by means of the dorsal parietal stream. This neurobiological process of visual information processing by ventral temporal pathway of ADDH-I group could be due to alterations in emotional processes that directly influence visual recognition or as consequence of deficit in the control of attentional processes by the dorsal parietal pathway.

Event-Related Potentials in Major Depressive Disorder / 신경정신의학

Many event-related potentials (ERPs) studies have been performed in major depressive disorder. ERPs include P50, N170, loudness dependence of auditory evoked potentials (LDAEP), P300, and mismatch negativity (MMN). These ERPs have good time-resolution as noninvasive methods, so they can be used easily in clinical practice and research. For example, ERPs can be used to differentiate patients from healthy people, as well as for assessing the subtype and severity, investigating the psychopathology, and predicting the treatment response in mental disorders. This review focuses on P50, N170, LDAEP, P300, and MMN in major depressive disorders.

Interferencia de la información léxica sobre la identificación de fonemas durante una tarea de decisión fonológica / Lexical information interference in phonemic recognition during a phonological decision task

A partir de estudios con potenciales relacionados a eventos en tareas de decisión fonológica (DF) o léxica (DL), se ha propuesto que el procesamiento auditivo del lenguaje es de tipo serial con interacciones tardías entre los módulos fonológico, sintáctico y semántico. Este trabajo intentó valorar si existía una interferencia entre el procesamiento fonológico y semántico durante la DL y DF de sintagmas nominales utilizando un artículo definido en concordancia con un sustantivo. A fin de examinar esto, se presentaron 180 estímulos auditivos a un grupo de participantes, y se les pidió que realizaran una tarea de DL y una de decisión DF; 60 estímulos utilizaron palabras de la lengua, 60 con una vocal alterada en el sustantivo que generaba una pseudopalabra (PSP1), y 60 con una sílaba traslocada en el sustantivo para generar otro tipo de pseudopalabra (PSP2). Se registraron 10 participantes hispanohablantes adultos sin padecimientos neurológicos ni psiquiátricos. Se encontró que los participantes se equivocaron más al identificar las PSP1 que las PSP2 en la tarea de DL. No se encontraron diferencias en el componente N400 durante DL. En la tarea de DF, se encontró que el N100 incrementó su amplitud ante la presentación de palabras. Estos hallazgos apuntan a que la información léxica interfiere con la fase de procesamiento fonológico y cuestiona el modelo de procesamiento serial del lenguaje.

Experiments using event-related potentials during phonological decision (PD) and lexical decision (LD) tasks have suggested that auditory language processing occurs in a serial fashion, with late interactions amongst the phonological, syntactic and semantic modules. This paper sought to assess the existence of interference between phonological and semantic processing during LD and PD in nominal phrases, by using a definite article to match a noun. In order to examine this, 180 auditory stimuli were presented to a group of participants, and they were asked to perform a LD and a PD task. Sixty auditory stimuli included a noun that generated a pseudo-word (PSP1), and 60 others included a misplaced syllable within the noun so as to generate another type of pseudo-word (PSP2). Ten adult Spanish speakers without any neurological or psychiatric disorders volunteered to take part in the experiment. Participants were found to make more mistakes when identifying PSP1 than PSP2 during the LD task. There were no significant differences in the N400 component during LD. As for the PD task, it was found that N100 increased in amplitude when words were presented. These findings go to show that lexical information interferes with the phonological processing phase, and questions the serial model of language processing.

Application of N100, P300 and QEEG as a Biological Marker in Patients with Schizophrenia / 대한정신약물학회지

OBJECTIVE: This study was carried out to investigate the clinical availability of event related potential (ERP) P300, N100 and QEEG as biological markers in schizophrenia (SPR) patients. METHODS: The 23 SPR patients who met Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) criteria of SPR and age and sex matched 23 normal controls (NC) were recruited. Positive and Negative Syndrome Scale (PANSS) was used to evaluate the clinical symptoms. The three electrodes (Cz, CPz, Pz) were used to measure the amplitude and latency of each ERP components. The qEEG was analyzed by the ranges of Hz: delta (1-3 Hz), theta (4-7 Hz), alpha (8-12 Hz), beta (13-30 Hz) and gamma (30-50 Hz). RESULTS:P300 amplitudes of SPR patients were reduced across Cz, CPz and Pz (F=5.81, p<0.05). There was no difference in P300 latency, N100 amplitude and N100 latency between SPR and NC. P300 amplitudes were not influenced by demographic characteristics and PANSS scores in SPR patients. The PANSS positive, negative, general subscale scores were positively correlated with N100 latency at Cz, CPz. SPR patients showed significantly decreased alpha activity (SPR vs. NC=24.44+/-6.98% vs. 29.55+/-6.74%, p<0.05) and increased gamma activity (SPR vs. NC=19.48+/-5.47% vs. 16.42+/-4.69%, p<0.05) compared with those of NC. CONCLUSION: The results suggest that the amplitude of P300 and alpha activity can be considered as a biological marker of SPR. And there is a possibility that the latency of N100 may reflect symptom severity of schizophrenia patients.

N100 Amplitude Slopes in Major Depressive Disorder, Bipolar Disorder, Schizophrenia and Normal Controls

OBJECTIVES: N100 amplitude slope(the intensity dependence of the cortical auditory evoked potentials) is widely considered as an indirect indicator of central serotonergic neurotransmission. However, there are only a few studies about N100 amplitude slopes of major psychiatric disorders. In this study, we examined N100 amplitude slope differences among major depressive disorder(MDD), bipolar disorder(BD), schizophrenia (SCZ) and normal controls(NC). METHODS: We measured the N100 amplitude slopes of 35 patients with MDD, 33 patients with BD, 27 patients with SCZ and 35 NC subjects. Amplitude differences from N1 to P2 at the five different sound intensities(55, 65, 75, 85 and 95dB) were examined at Cz electrode. The N100 amplitude slope was calculated as the linear regression of five N1/P2 peak-to-peak amplitudes across stimulus intensities. RESULTS: BD patients showed significantly reduced N100 amplitude slope compared with NC(0.54+/-0.70 vs. 0.96+/-0.72, p=0.035). N100 amplitude slope of SCZ patients was significantly reduced compared with NC(0.50 +/-0.47 vs. 0.96+/-0.72, p=0.027). N100 amplitude slope of BD patients was significantly lower than that of MDD patients(0.54+/-0.70 vs. 0.94+/-0.60, p=0.046). SCZ patients also showed significant reduction of N100 amplitude slope compared with MDD patients(0.50+/-0.47 vs. 0.94+/-0.60, p=0.036). There was no significant difference of N100 amplitude slope between MDD patients and NC(0.94+/-0.60 vs. 0.96+/-0.72, p=1.000). CONCLUSION: Interestingly, the N100 amplitude slopes of BD and SCZ were reduced compared to NC and MDD patients. Our results suggest the predictive use of N100 amplitude slope in making differential diagnoses of major psychiatric disorders. Clinical implications of N100 amplitude slope in major psychiatric disorders were discussed.

Aberrant Response of Selective Serotonin Reuptake Inhibitor in Two Patients with High N100 Amplitude Slope / 대한정신약물학회지

Serotonin is one of the most important neurotransmitters involved in the pathophysiology of depressive illness. The assessment of alteration of cerebral serotonin has been still controversial but interesting topic to study. Recently, increasing evidence has accumulated that the N100 amplitude slope reflects cerebral serotonin activity and treatment response of selective serotonin reuptake inhibitors (SSRIs). We report on two patients who showed abrupt mood changes and side effects after taking SSRI antidepressants. In both patients, aberrantly high N100 amplitude slopes were observed. Our cases suggest that the N100 amplitude slope may be a reliable indicator for predicting manic conversion and side effects in the SSRI treatment of depressive patients. Controlled studies are necessary to confirm whether a high N100 amplitude slope is a useful indicator of SSRI supersensitivity.

Clinical Availability of Topographic Auditory Event Related Potential P300 as a Biological Marker in Patients with Schizophrenia / 신경정신의학

This study was designed to investigate the clinical availability of topographic auditory event related potential P300 as a biological marker in patients with schizophrenia. The subjects were composed of normal controls(N=30) and patients(N=30) with schizophrenia by DSM-IV. Topographic auditory event related potential P300 and N100 were measured by "oddball paradigm", which was known as a standard method. Schizophrenics were evaluated twice, initial and follow-up, by 4 week interval. P300 latency and N100 latency were deter-mined by Global Field Power. At this time point the maximum amplitude and its location, according to X-Y coordinates, were determined in brain topography. Clinical symptoms were evaluated by Positive and Negative Syndrome Scale(PANSS). P300 latencies of normal controls, initial group of schizophrenics, and follow-up group of schizophrenics were 315.8+/-24.2msec, 403.8+/-42.3msec, and 364.7+/-43.2msec, respectively. P300 amplitudes of normal controls, initial group of schizophrenics, and follow-up group of schizophrenics were 8.8+/-2.7microV, 4.4+/-1.9microV, and 4.4+/-2.5microV, respectively. They had significantly different P300 latencies one another by measuring ANCOVA, of which covariables were N100 latency, age, and CCP(correct counted percent)(p<0.01). X-Y coordinates was not significant. In P300, there were some different characters between normal controls and schizophrenics even though excluding N100, which was supposed to be exogeneous component by external stimuli. When clinical symptoms were improved, P300 latency was decreased. However, P300 amplitude was not changed. These results suggest that P300 woald be available clinically as a biological marker, P300 latency be a state marker, and P300 amplitude be a trait marker in schizophrenia.

Altered Auditory Event Related Potentials Following Administration of Methylphenidate in Children with Attention Deficit Hyperactivity Disorder / 신경정신의학

OBJECTS: Event related potential(ERF) has been recently applied to examine the neurophysiological disturbance in attention deficit hyperactivity disorder(ADHD), particularly with regard to N100 and P300 which are known as one of ERP components closely linked with cognitive function. On the basis of these aspects, this study was designed to evaluate electrophysiologic characteristics and its availability for diagnosis and treatment of ADHD children by comparison of ERP between normal controls and ADHD children before and after methylphenidate (MFD) administration. METHODS: We examined the topographic auditory ERF and T.O.V.A.(Test of variables of attention), a standardized computerized visual continuous performance test following administration of stimulant drug, MPD 10mg in 13 ADHD children and compared these results with those of 11 normal controls. RESULTS: The results were as follows: 1) Thought the difference was not spastically significant(P=0.0548), N100 latencies seemed to be longer in ADHD children than in normal controls. N100 amplitudes also seemed to be larger in ADHD children than in normal controls(P=0.0629). 2) The F300 latencies significantly shortened after MFD administration when compared with those before MPD administration in ADHD group(P<0.01). 3) ADHD group performed significantly less well than normal controls in T.O.V.A.(P<0.05). And T.O.V.A. scores significantly improved after MFD administration in ADHD group(P<0.01). 4) The N100 and P300 latencies and the T.O.V.A. scores were significantly correlated before MPD administration in ADHD group(P<0.05). 5) The F300 latencies before MFD administration were significantly correlated with the amplitudes of changes of T.O.V.A. scores after MFD administration(P<0.05). CONCLUSION: It seems that prolonged N100 latency of ADHD children can be regarded as a relatively enduring trait marker and that F300 latency may reflect attentional response ability along with therapeutic effect by stimulant.