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Ng KKW, Lafee O, Bouchatta O, Makdani AD, Marshall AG, Olausson H, McIntyre S, Nagi SS. Human Foot Outperforms the Hand in Mechanical Pain Discrimination. eNeuro 2024; 11:ENEURO.0412-23.2024. [PMID: 38272674 PMCID: PMC10875634 DOI: 10.1523/eneuro.0412-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 01/04/2024] [Accepted: 01/08/2024] [Indexed: 01/27/2024] Open
Abstract
Tactile discrimination has been extensively studied, but mechanical pain discrimination remains poorly characterized. Here, we measured the capacity for mechanical pain discrimination using a two-alternative forced choice paradigm, with force-calibrated indentation stimuli (Semmes-Weinstein monofilaments) applied to the hand and foot dorsa of healthy human volunteers. In order to characterize the relationship between peripheral nociceptor activity and pain perception, we recorded single-unit activity from myelinated (A) and unmyelinated (C) mechanosensitive nociceptors in the skin using microneurography. At the perceptual level, we found that the foot was better at discriminating noxious forces than the hand, which stands in contrast to that for innocuous force discrimination, where the hand performed better than the foot. This observation of superior mechanical pain discrimination on the foot compared to the hand could not be explained by the responsiveness of individual nociceptors. We found no significant difference in the discrimination performance of either the myelinated or unmyelinated class of nociceptors between skin regions. This suggests the possibility that other factors such as skin biophysics, receptor density or central mechanisms may underlie these regional differences.
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Affiliation(s)
- Kevin K W Ng
- Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Odai Lafee
- Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Otmane Bouchatta
- Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Adarsh D Makdani
- Research Centre for Brain and Behaviour, School of Psychology, Liverpool John Moores University, Liverpool, United Kingdom
| | - Andrew G Marshall
- Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Håkan Olausson
- Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Sarah McIntyre
- Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Saad S Nagi
- Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
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Bouchatta O, Brodzki M, Manouze H, Carballo GB, Kindström E, de-Faria FM, Yu H, Kao AR, Thorell O, Liljencrantz J, Ng KKW, Frangos E, Ragnemalm B, Saade D, Bharucha-Goebel D, Szczot I, Moore W, Terejko K, Cole J, Bonnemann C, Luo W, Mahns DA, Larsson M, Gerling GJ, Marshall AG, Chesler AT, Olausson H, Nagi SS, Szczot M. PIEZO2-dependent rapid pain system in humans and mice. bioRxiv 2023:2023.12.01.569650. [PMID: 38168273 PMCID: PMC10760115 DOI: 10.1101/2023.12.01.569650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
The PIEZO2 ion channel is critical for transducing light touch into neural signals but is not considered necessary for transducing acute pain in humans. Here, we discovered an exception - a form of mechanical pain evoked by hair pulling. Based on observations in a rare group of individuals with PIEZO2 deficiency syndrome, we demonstrated that hair-pull pain is dependent on PIEZO2 transduction. Studies in control participants showed that hair-pull pain triggered a distinct nocifensive response, including a nociceptive reflex. Observations in rare Aβ deafferented individuals and nerve conduction block studies in control participants revealed that hair-pull pain perception is dependent on Aβ input. Single-unit axonal recordings revealed that a class of cooling-responsive myelinated nociceptors in human skin is selectively tuned to painful hair-pull stimuli. Further, we pharmacologically mapped these nociceptors to a specific transcriptomic class. Finally, using functional imaging in mice, we demonstrated that in a homologous nociceptor, Piezo2 is necessary for high-sensitivity, robust activation by hair-pull stimuli. Together, we have demonstrated that hair-pulling evokes a distinct type of pain with conserved behavioral, neural, and molecular features across humans and mice.
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Affiliation(s)
- Otmane Bouchatta
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
- These authors contributed equally
| | - Marek Brodzki
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
- These authors contributed equally
| | - Houria Manouze
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Gabriela B. Carballo
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Emma Kindström
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Felipe M. de-Faria
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Huasheng Yu
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Anika R. Kao
- School of Engineering and Applied Science, University of Virginia, Charlottesville, USA
| | - Oumie Thorell
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
- School of Medicine, Western Sydney University, Sydney, Australia
| | - Jaquette Liljencrantz
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, USA
- Department of Anesthesiology and Intensive Care, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Kevin K. W. Ng
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Eleni Frangos
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, USA
| | - Bengt Ragnemalm
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Dimah Saade
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, USA
| | - Diana Bharucha-Goebel
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, USA
| | - Ilona Szczot
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Warren Moore
- Institute of Life Course and Medical Sciences, University of Liverpool, UK
| | - Katarzyna Terejko
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
- Biology of Astrocytes Research Group, Łukasiewicz Research Network - PORT Polish Center for Technology Development, Wroclaw, Poland
| | - Jonathan Cole
- University Hospitals, Dorset, and University of Bournemouth, UK
| | - Carsten Bonnemann
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, USA
| | - Wenquin Luo
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - David A. Mahns
- School of Medicine, Western Sydney University, Sydney, Australia
| | - Max Larsson
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Gregory J. Gerling
- School of Engineering and Applied Science, University of Virginia, Charlottesville, USA
| | - Andrew G. Marshall
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
- Institute of Life Course and Medical Sciences, University of Liverpool, UK
| | - Alexander T. Chesler
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, USA
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, USA
| | - Håkan Olausson
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
| | - Saad S. Nagi
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
- School of Medicine, Western Sydney University, Sydney, Australia
- Senior author
| | - Marcin Szczot
- Center for Social and Affective Neuroscience, Linköping University, Linköping, Sweden
- Senior author
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Sharma D, Ng KKW, Birznieks I, Vickery RM. Perceived tactile intensity at a fixed primary afferent spike rate varies with the temporal pattern of spikes. J Neurophysiol 2022; 128:1074-1084. [DOI: 10.1152/jn.00284.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The perceived intensity of a vibrotactile stimulus is thought to depend on single neuron firing rates (rate coding) and the number of active afferents (population coding). Unaddressed until now is whether the temporal relation of individual spikes also conveys information about tactile intensity. We used cutaneous electro-tactile stimulation to investigate how the temporal structure of a fixed number of spikes in a 1 s train influenced the perception of intensity. Four mean spike rates spanning the flutter and vibratory hum range (36 Hz, 60 Hz; 120 Hz, 180 Hz) were tested, with spikes grouped into a regular pattern, or bursts of 2-6 spikes spaced 3 ms apart. To link a putative neural code to perception, perceived intensity was assessed in sixteen human participants (aged 20-45; 4 females) using the psychophysical paradigm of magnitude estimation. Compound sensory nerve action potentials were recorded to assess any stimulus variation in afferent recruitment. The temporal structuring of a fixed number of spikes into periodic bursts of multiple spikes altered perceived intensity as a function of burst spike count. The largest increase was seen at 36 Hz, where the bursts of 6 spikes were rated 2.1x stronger than the regularly spaced spikes (95% CI: 1.9-2.3). The true increase is likely larger as temporal structuring of spikes into bursts had some negative effect on afferent recruitment. We conclude that the perceived intensity can be modulated by changing temporal features of afferent discharge even when normalized for the number of recruited afferents.
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Affiliation(s)
- Deepak Sharma
- School of Biomedical Sciences, UNSW Sydney,Sydney, Australia
- Neuroscience Research Australia, Sydney, Australia
| | - Kevin K. W. Ng
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Ingvars Birznieks
- School of Biomedical Sciences, UNSW Sydney,Sydney, Australia
- Neuroscience Research Australia, Sydney, Australia
- Bionics and Bio‐robotics, Tyree Foundation Institute of Health Engineering, UNSW Sydney, Sydney, Australia
| | - Richard Martin Vickery
- School of Biomedical Sciences, UNSW Sydney,Sydney, Australia
- Neuroscience Research Australia, Sydney, Australia
- Bionics and Bio‐robotics, Tyree Foundation Institute of Health Engineering, UNSW Sydney, Sydney, Australia
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Sharma D, Ng KKW, Birznieks I, Vickery RM. Auditory clicks elicit equivalent temporal frequency perception to tactile pulses: A cross-modal psychophysical study. Front Neurosci 2022; 16:1006185. [PMID: 36161171 PMCID: PMC9500524 DOI: 10.3389/fnins.2022.1006185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 08/24/2022] [Indexed: 12/02/2022] Open
Abstract
Both hearing and touch are sensitive to the frequency of mechanical oscillations—sound waves and tactile vibrations, respectively. The mounting evidence of parallels in temporal frequency processing between the two sensory systems led us to directly address the question of perceptual frequency equivalence between touch and hearing using stimuli of simple and more complex temporal features. In a cross-modal psychophysical paradigm, subjects compared the perceived frequency of pulsatile mechanical vibrations to that elicited by pulsatile acoustic (click) trains, and vice versa. Non-invasive pulsatile stimulation designed to excite a fixed population of afferents was used to induce desired temporal spike trains at frequencies spanning flutter up to vibratory hum (>50 Hz). The cross-modal perceived frequency for regular test pulse trains of either modality was a close match to the presented stimulus physical frequency up to 100 Hz. We then tested whether the recently discovered “burst gap” temporal code for frequency, that is shared by the two senses, renders an equivalent cross-modal frequency perception. When subjects compared trains comprising pairs of pulses (bursts) in one modality against regular trains in the other, the cross-sensory equivalent perceptual frequency best corresponded to the silent interval between the successive bursts in both auditory and tactile test stimuli. These findings suggest that identical acoustic and vibrotactile pulse trains, regardless of pattern, elicit equivalent frequencies, and imply analogous temporal frequency computation strategies in both modalities. This perceptual correspondence raises the possibility of employing a cross-modal comparison as a robust standard to overcome the prevailing methodological limitations in psychophysical investigations and strongly encourages cross-modal approaches for transmitting sensory information such as translating pitch into a similar pattern of vibration on the skin.
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Affiliation(s)
- Deepak Sharma
- School of Biomedical Sciences, The University of New South Wales (UNSW Sydney), Sydney, NSW, Australia
- Neuroscience Research Australia, Sydney, NSW, Australia
- *Correspondence: Deepak Sharma,
| | - Kevin K. W. Ng
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Ingvars Birznieks
- School of Biomedical Sciences, The University of New South Wales (UNSW Sydney), Sydney, NSW, Australia
- Neuroscience Research Australia, Sydney, NSW, Australia
- Bionics and Bio-Robotics, Tyree Foundation Institute of Health Engineering, The University of New South Wales (UNSW Sydney), Sydney, NSW, Australia
| | - Richard M. Vickery
- School of Biomedical Sciences, The University of New South Wales (UNSW Sydney), Sydney, NSW, Australia
- Neuroscience Research Australia, Sydney, NSW, Australia
- Bionics and Bio-Robotics, Tyree Foundation Institute of Health Engineering, The University of New South Wales (UNSW Sydney), Sydney, NSW, Australia
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Ng KKW, Tee X, Vickery RM, Birznieks I. The Relationship Between Tactile Intensity Perception and Afferent Spike Count is Moderated by a Function of Frequency. IEEE Trans Haptics 2022; 15:14-19. [PMID: 34990370 DOI: 10.1109/toh.2022.3140877] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
It has been suggested that tactile intensity perception can be explained by a linear function of spike rate weighted by afferent type. Other than relying on mathematical models, verifying this experimentally is difficult due to the frequency tuning of different afferent types and changes in population recruitment patterns with vibrotactile frequency. To overcome these complexities, we used pulsatile mechanical stimuli which activate the same afferent population regardless of the repetition rate (frequency), generating one action potential per pulse. We used trains of different frequencies (20-200 Hz) to investigate perceived intensity. Subjects' magnitude ratings increased with pulse rate up to ∼100 Hz and plateaued beyond this frequency. This was true regardless of pulse amplitude, from small pulses that exclusively activated Pacinian (PC) afferents, to pulses large enough to activate other afferents including slowly adapting. Electrical stimulation, which activates afferents indiscriminately, plateaued at a similar frequency, although not in all subjects. As the plateauing did not depend on indentation magnitude and hence on afferent weights, we propose that the contribution of spike count to intensity perception is weighted by a function of frequency. This may explain why fine textures evoking high frequency vibrations of a small magnitude do not feel disproportionally intense.
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Ng KKW, Snow IN, Birznieks I, Vickery RM. Burst gap code predictions for tactile frequency are valid across the range of perceived frequencies attributed to two distinct tactile channels. J Neurophysiol 2021; 125:687-692. [PMID: 33439792 DOI: 10.1152/jn.00662.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Perceived frequency of vibrotactile stimuli can be divided into two distinctive cutaneous sensations-flutter (<60 Hz) and vibratory hum (>60 Hz), mediated by two different tactile afferent types [fast adapting type I (FA1) and fast adapting type II (FA2), respectively]. We recently demonstrated a novel form of neural coding in the human tactile system, where frequency perception of stimulus pulses grouped into periodic bursts in the flutter range depended on the duration of the silent gap between bursts, rather than the periodicity or mean impulse rate. Here, we investigated whether this interburst interval could also explain the perceived frequency of electrocutaneous pulse patterns delivered at frequencies above the flutter range. At stimulus rates of 50 to 190 pulses/s, the burst gap model correctly predicted the perceived frequency. This shows that the burst gap code represents a general coding strategy that spans the range of frequencies traditionally attributed to two different tactile channels.NEW & NOTEWORTHY We present evidence for a generalized frequency processing strategy on tactile afferent inputs that is shared across a broad range of frequencies extending beyond the flutter range, supporting the notion that spike timing has an important role in shaping tactile perception.
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Affiliation(s)
- Kevin K W Ng
- School of Medical Sciences, UNSW Sydney, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia
| | - Ian N Snow
- School of Medical Sciences, UNSW Sydney, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia
| | - Ingvars Birznieks
- School of Medical Sciences, UNSW Sydney, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia
| | - Richard M Vickery
- School of Medical Sciences, UNSW Sydney, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia
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Ng KKW, Olausson C, Vickery RM, Birznieks I. Temporal patterns in electrical nerve stimulation: Burst gap code shapes tactile frequency perception. PLoS One 2020; 15:e0237440. [PMID: 32790784 PMCID: PMC7425972 DOI: 10.1371/journal.pone.0237440] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Accepted: 07/27/2020] [Indexed: 12/25/2022] Open
Abstract
We have previously described a novel temporal encoding mechanism in the somatosensory system, where mechanical pulses grouped into periodic bursts create a perceived tactile frequency based on the duration of the silent gap between bursts, rather than the mean rate or the periodicity. This coding strategy may offer new opportunities for transmitting information to the brain using various sensory neural prostheses and haptic interfaces. However, it was not known whether the same coding mechanisms apply when using electrical stimulation, which recruits a different spectrum of afferents. Here, we demonstrate that the predictions of the burst gap coding model for frequency perception apply to burst stimuli delivered with electrical pulses, re-emphasising the importance of the temporal structure of spike patterns in neural processing and perception of tactile stimuli. Reciprocally, the electrical stimulation data confirm that the results observed with mechanical stimulation do indeed depend on neural processing mechanisms in the central nervous system, and are not due to skin mechanical factors and resulting patterns of afferent activation.
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Affiliation(s)
- Kevin K. W. Ng
- School of Medical Sciences, UNSW Sydney, Sydney, Australia
- Neuroscience Research Australia, Sydney, Australia
- * E-mail:
| | - Christoffer Olausson
- Neuroscience Research Australia, Sydney, Australia
- Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Richard M. Vickery
- School of Medical Sciences, UNSW Sydney, Sydney, Australia
- Neuroscience Research Australia, Sydney, Australia
| | - Ingvars Birznieks
- School of Medical Sciences, UNSW Sydney, Sydney, Australia
- Neuroscience Research Australia, Sydney, Australia
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Vickery RM, Ng KKW, Potas JR, Shivdasani MN, McIntyre S, Nagi SS, Birznieks I. Tapping Into the Language of Touch: Using Non-invasive Stimulation to Specify Tactile Afferent Firing Patterns. Front Neurosci 2020; 14:500. [PMID: 32508581 PMCID: PMC7248323 DOI: 10.3389/fnins.2020.00500] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Accepted: 04/21/2020] [Indexed: 12/12/2022] Open
Abstract
The temporal pattern of action potentials can convey rich information in a variety of sensory systems. We describe a new non-invasive technique that enables precise, reliable generation of action potential patterns in tactile peripheral afferent neurons by brief taps on the skin. Using this technique, we demonstrate sophisticated coding of temporal information in the somatosensory system, that shows that perceived vibration frequency is not encoded in peripheral afferents as was expected by either their firing rate or the underlying periodicity of the stimulus. Instead, a burst gap or silent gap between trains of action potentials conveys frequency information. This opens the possibility of new encoding strategies that could be deployed to convey sensory information using mechanical or electrical stimulation in neural prostheses and brain-machine interfaces, and may extend to senses beyond artificial encoding of aspects of touch. We argue that a focus on appropriate use of effective temporal coding offers more prospects for rapid improvement in the function of these interfaces than attempts to scale-up existing devices.
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Affiliation(s)
- Richard M. Vickery
- School of Medical Sciences, UNSW Sydney, Sydney, NSW, Australia
- Neuroscience Research Australia, Sydney, NSW, Australia
| | - Kevin K. W. Ng
- School of Medical Sciences, UNSW Sydney, Sydney, NSW, Australia
- Neuroscience Research Australia, Sydney, NSW, Australia
| | - Jason R. Potas
- School of Medical Sciences, UNSW Sydney, Sydney, NSW, Australia
| | - Mohit N. Shivdasani
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, NSW, Australia
| | - Sarah McIntyre
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Saad S. Nagi
- Center for Social and Affective Neuroscience, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Ingvars Birznieks
- School of Medical Sciences, UNSW Sydney, Sydney, NSW, Australia
- Neuroscience Research Australia, Sydney, NSW, Australia
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Ng KKW, Birznieks I, Tse ITH, Andersen J, Nilsson S, Vickery RM. Perceived Frequency of Aperiodic Vibrotactile Stimuli Depends on Temporal Encoding. Haptics: Science, Technology, and Applications 2018. [DOI: 10.1007/978-3-319-93445-7_18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Smales RJ, Ng KKW. Longevity of a resin-modified glass ionomer cement and a polyacid-modified resin composite restoring non-carious cervical lesions in a general dental practice. Aust Dent J 2004; 49:196-200. [PMID: 15762341 DOI: 10.1111/j.1834-7819.2004.tb00073.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Long-term prospective survival studies of resin-modified glass ionomer cements (RMGICs) and polyacid-modified resin composites (compomers) placed in non-carious cervical lesions (NCCLs) are lacking from general dental practice. Short-term studies have shown an unsatisfactory clinical performance for several materials. METHODS One practitioner placed 87 compomer (Compoglass, Vivadent-Ivoclar) and 73 encapsulated RMGIC (Fuji II LC, GC Int.) restorations in NCCLs for 61 adults. Compoglass was placed using SCA primer, and Fuji II LC using GC Dentin Conditioner. No cavity preparation was undertaken. The Kaplan-Meier method was used for estimating the cumulative survivals for those restorations that were replaced, with the probability level set at alpha = 0.05 for statistical significance. RESULTS Restorations were judged unsatisfactory (by the practitioner and the subjects) because of surface and marginal loss of material (68.8 per cent), dislodgement (18.8 per cent) and discoloration (12.4 per cent), these modes being similar for both materials (P = 0.35). Unsatisfactory restorations were replaced in 121 (75.6 per cent) instances. After periods of up to five years, cumulative survival estimates were 14.9 (5.8 Standard Error) per cent for Compoglass and zero per cent for Fuji II LC (P = 0.74). Median survivals were 30 months for Compoglass and 42 months for Fuji II LC. CONCLUSION Both materials had high long-term unsatisfactory performances when placed in non-prepared NCCLs in a general dental practice.
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Affiliation(s)
- R J Smales
- Dental School, Faculty of Health Sciences, The University of Adelaide, Adelaide, South Australia.
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