Gábor Braunitzer

In vitro fracture resistance of molar teeth restored with a short fibre-reinforced composite material

OBJECTIVES The purpose of this in vitro study was to evaluate the efficiency of a short fibre-reinforced composite (SFRC) material compared to conventional composites when restoring class II. MOD cavities in molar teeth with different layering techniques. METHODS One hundred and thirty mandibular third molars were divided into 5 groups (n=26). Except for the control group (intact teeth), in all other groups MOD cavities were prepared. The cavities were restored by either conventional composite with horizontal and oblique layering or by SFRC with horizontal and oblique layering. The specimens were submitted to static fracture toughness test. Fracture thresholds and fracture patterns were evaluated. RESULTS In general, no statistically significant difference was found in fracture toughness between the study groups, except for horizontally layered conventional composite restorations, which turned out to be significantly weaker than controls. However, SFRC yielded noticeably higher fracture thresholds and only obliquely applied SFRC restorations exhibited favourable fracture patterns above chance level. CONCLUSIONS The application of SFRC did not lead to a statistically significant improvement of the fracture toughness of molar teeth with MOD cavities. Still, SFRC applied in oblique increments measurably reduces the chance of unrestorable fractures of molar teeth with class II MOD cavities. CLINICAL SIGNIFICANCE The restoration of severely weakened molar teeth with the use of SFRC combined with composite might have advantages over conventional composites alone. It was observed from the statistical data, that the application of SFRC with an oblique layering technique yielded not significantly but better fracture thresholds and more favourable fracture patterns than any other studied material/technique combination. Thus further investigations need to be carried out, to investigate the possible positive mechanical effects of SFRC. The application of the horizontal layering technique with conventional composite materials is inferior to the oblique technique and SFRC materials.

Smoking as a permissive factor of periodontal disease in psoriasis

Background Population-based studies have identified smoking as a pathogenetic factor in chronic periodontitis. At the same time, chronic periodontal disease has also been found to occur more often in persons suffering from psoriasis than in controls with no psoriasis. It is known that smoking aggravates both periodontal disease and psoriasis, but so far it has not been investigated how smoking influences the occurrence and severity of periodontal disease in psoriasis. Methods A hospital-based study was conducted to investigate this question. The study population consisted of 82 psoriasis patients and 89 controls. All patients received a full-mouth periodontal examination, and a published classification based on bleeding on probing, clinical attachment level and probing depth was utilized for staging. Both patients and controls were divided into smoker and non-smoker groups, and the resulting groups were compared in terms of periodontal status. Beyond the descriptive statistics, odds ratios were computed. Results Psoriasis in itself increased the likelihood of severe periodontal disease to 4.373 (OR, as compared to non-smoker controls, p<0.05), while smoking increased it to 24.278 (OR, as compared to non-smoker controls, p<0.001) in the studied population. In other words, the risk of severe periodontal disease in psoriasis turned out to be six times higher in smokers than in non-smokers. Conclusions The results of this study corroborate those of other studies regarding the link between psoriasis and periodontal disease, but they also seem to reveal a powerful detrimental effect of smoking on the periodontal health of psoriasis patients, whereby the authors propose that smoking may have a permissive effect on the development of severe periodontal disease in psoriasis.

Visual Pathways Serving Motion Detection in the Mammalian Brain

Motion perception is the process through which one gathers information on the dynamic visual world, in terms of the speed and movement direction of its elements. Motion sensation takes place from the retinal light sensitive elements, through the visual thalamus, the primary and higher visual cortices. In the present review we aim to focus on the extrageniculo-extrastriate cortical and subcortical visual structures of the feline and macaque brain and discuss their functional role in visual motion perception. Special attention is paid to the ascending tectofugal system that may serve for detection of the visual environment during self-motion.

Parallel development of contour integration and visual contrast sensitivity at low spatial frequencies

It has been suggested that visual contrast sensitivity and contour integration functions exhibit a late maturation during adolescence. However, the relationship between these functions has not been investigated. The aim of this study was to assess the development of visual contrast sensitivity and contour integration in 152 healthy volunteers aged between 5 and 30 years. The results revealed a significant maturation of contrast sensitivity at low spatial frequencies (0.5, 1.2, and 1.9 cycles/degree) and contour integration. The largest developmental step was observed for both contrast sensitivity and contour integration tasks when the 5-8-year olds were compared with the 9-11-year olds. There was a significant correlation between the development of low spatial frequency contrast sensitivity and contour integration. These results raise the possibility that the development of low spatial frequency processing may affect attentional mechanisms, which may have an impact on early contour integration.

Delayed development of visual motion processing in childhood migraine

Introduction: Altered visual processing has been observed in adult migraineurs. But because visual processing has not been studied in paediatric cases, it is not known whether such visual system alterations are already present in early development. We therefore used a dynamic visual task to investigate motion detection threshold in paediatric migraine. Methods: Fourteen migraineurs and 21 controls participated in the study (age range: 8–17 years). The minimal percentage of coherently moving dot stimuli at which subjects were still able to detect coherent movement (absolute threshold) was determined using a random dot kinematogram paradigm. Results: Motion coherence detection threshold was higher in migraineurs (p < 0.05). This difference between groups was more pronounced at younger ages, but migraineurs seem to catch up with healthy controls over the years. Conclusions: Children with migraine exhibit a delayed development of visual motion processing. This might be a useful supplementary biomarker in paediatric migraine.

Development of visual contour integration in children with migraine without aura

Introduction: As migraine attacks pose insult to cerebral circulation and ion homeostasis, migraine has the potential to interfere with the development of different brain structures, producing functional deficits. It is known that visual contour integration (CI) is a function with a protracted development. Therefore, we sought to establish whether migraine interferes with its development. Methods: Forty-eight migraineurs (without aura) and 48 age- and sex-matched controls participated in the study, divided into three cohorts by age. Stimuli were presented on cards with a contour consisting of Gabor patches embedded in random noise. Difficulty was varied by the manipulation of relative noise density. The task was to identify and show the contour. Results: A significant difference was found between the performance of migraineurs and controls in the 10–14-year-old and 15–18-year-old cohorts (p < 0.05). Development between all three cohorts was significant in the control group (p < 0.017), while it was not significant in migraineurs between 6 and 14 years. Correlation between age and CI threshold was stronger in controls than in migraineurs. Conclusion: Children with paediatric migraine exhibited a less marked development in the Gabor patch-based CI task.

Prasugrel Versus Clopidogrel: A Comparative Examination of Local Bleeding After Dental Extraction in Patients Receiving Dual Antiplatelet Therapy

PURPOSE To study the effects of various parameters on local hemostasis after dental extraction in patients receiving different combinations of medications who had previously confirmed effective dual inhibition of platelet aggregation. MATERIALS AND METHODS A total of 129 patients were enrolled. They underwent acute or planned percutaneous coronary intervention and their stomatological examination disclosed teeth that could have acted as foci and thus had to be removed. All patients took acetylsalicylic acid 100 mg and clopidogrel or prasugrel. Lidocaine with or without epinephrine was used for local anesthesia, and a gauze swab or suture was applied to help hemostasis. RESULTS Bleeding time was significantly longer by an average of 10 minutes (+21%) in patients taking prasugrel (P < .05) compared with those taking clopidogrel. Use of a suture resulted in a significantly shorter bleeding time after anesthesia with or without epinephrine (P < .05). A considerably longer bleeding time was observed when anesthesia with no epinephrine was combined with gauze. In smokers, the bleeding time was shorter by 15% on average. CONCLUSION This study is the first to analyze differences in bleeding times between clopidogrel and prasugrel treatments during dental extraction. In general, prasugrel is associated with a considerably longer bleeding time; nevertheless, dental extraction can be performed safely with either combination.

Neuronal code of spatial visual information in the caudate nucleus

Earlier reports described huge overlapping visual receptive fields and the absence of retinotopic organization in the dorsolateral, caudal part of the caudate nucleus. In the present study we suggest a possible alternative mechanism for the coding of spatial visual information. Extracellular microelectrode recordings were carried out in halothane-anesthetized, immobilized, artificially ventilated cats. In order to investigate the responsiveness of the single neurons to visual information arriving from different sites of the receptive field, we divided the visual fields to 20 parts of equal size and stimulated the individual parts one-by-one. We found that each single visual caudate nucleus (CN) neuron can carry information about stimulus locations throughout the whole physically approachable visual field of the investigated eye. A large majority (85%) of these neurons exhibited significantly different responses to stimuli appearing in different regions of their huge receptive field. Thus these neurons appear to have the ability to provide information on the site of the stimulus via their discharge rate. The huge receptive fields in combination with the spatial selectivity suggest that these caudate nucleus neurons may serve as panoramic localizers. On the population level, the sites of maximal responsiveness of the visual neurons are distributed over the whole extent of the receptive fields. We argue that groups of these panoramic localizer neurons with different locations of maximal stimulus preference should have the ability to accurately code the locations of visual stimuli. We propose this distributed population code of visual information as an alternative information processing mechanism.

Visual stimulation synchronizes or desynchronizes the activity of neuron pairs between the caudate nucleus and the posterior thalamus

Recent morphological and physiological studies have suggested a strong relationship between the suprageniculate nucleus (Sg) of the posterior thalamus and the input structure of the basal ganglia, the caudate nucleus (CN) of the feline brain. Accordingly, to clarify if there is a real functional relationship between Sg and CN during visual information processing, we investigated the temporal relations of simultaneously recorded neuronal spike trains of these two structures, looking for any significant cross-correlation between the spiking of the simultaneously recorded neurons. For the purposes of statistical analysis, we used the shuffle and jittering resampling methods. Of the recorded 288 Sg-CN neuron pairs, 26 (9.2%) showed significantly correlated spontaneous activity. Nineteen pairs (6.7%) showed correlated activity during stationary visual stimulation, while 21 (7.4%) pairs during stimulus movement. There was no overlap between the neuron pairs that showed cross-correlated spontaneous activity and the pairs that synchronized their activity during visual stimulation. Thus visual stimulation seems to have been able to synchronize, and also, by other neuron pairs, desynchronize the activity of CN and Sg. In about half of the cases, the activation of Sg preceded the activation of CN by a few milliseconds, while in the other half, CN was activated earlier. Our results provide the first piece of evidence for the existence of a functional cooperation between Sg and CN. We argue that either a monosynaptic bidirectional direct connection should exist between these structures, or a common input comprising of parallel pathways synchronizing them.

Is the development of visual contrast sensitivity impaired in children with migraine? An exploratory study

Introduction: Impairment of visual contrast sensitivity is a well-known phenomenon in adult migraineurs. Little is known, however, about whether contrast sensitivity deficits are already present in children with migraine. Methods: We conducted an exploratory study with 18 children with migraine without aura, in which we tested our subjects’ visual contrast sensitivity. Eighteen age- and sex-matched healthy children served as controls. Results: Among the youngest subjects (6–10 years) we found no significant differences at any of the spatial frequencies tested, as compared to the controls, whereas from the age of 10 on, migraineurs exhibited significantly poorer contrast sensitivity, especially at the lower spatial frequencies. Conclusion: To our knowledge, we are the first to report on such a deficit in children, and we conclude that our findings might be interpreted as reflecting an increased vulnerability of the visual system to migraine attacks as part of the migrainous endophenotype.