A tutorial review of both linear and quadratic representations is given. The linear representations discussed are the short-time Fourier transform and the wavelet transform. The discussion of quadratic representations concentrates on the Wigner distribution, the ambiguity function, smoothed versions of the Wigner distribution, and various classes of quadratic time-frequency representations. Examples of the application of these representations to typical problems encountered in time-varying signal processing are provided. >

Linear and quadratic time-frequency signal representations

The current paper provides a brief overview of research on the effects of race and ethnicity on pain. More specifically, the article reviews the utility of the concepts of race and ethnicity for pain research, suggests operational definitions of race and ethnicity, reviews the literature on the effects of race and ethnicity on laboratory and clinical pain, and provides suggestions for future research.

Race, ethnicity and pain

Sleep bruxism; an overview of an oromandibular sleep movement disorder. REVIEW ARTICLE.

Objective Although numerous studies have independently examined ethnic differences in clinical and experimental pain, few have investigated differences in both sensitivity to controlled noxious stimuli and clinical pain reports in the same sample. The present experiment examined the effects of ethnicity (African American vs. white) on experimental pain tolerance and adjustment to chronic pain. Methods Three hundred thirty-seven (68 African American and 269 white) patients with chronic pain referred to a multidisciplinary treatment center participated in the study. In addition to completing a number of standardized questionnaires assessing adjustment to chronic pain, participants underwent a submaximal effort tourniquet procedure. This experimental pain procedure yields a measure of tolerance for a controlled noxious stimulus (ie, arm ischemia). Results African American subjects reported higher levels of clinical pain as well as greater pain-related disability than white participants. In addition, substantial group differences were observed for ischemic pain tolerance, with African Americans demonstrating less tolerance than whites. Correlational analyses revealed a small but significant inverse relationship between ischemic pain tolerance and the reported severity of chronic pain. Conclusions Collectively these findings support previous research revealing ethnic differences in responses to both clinical and experimental pain. Moreover, the present results suggest that enhanced sensitivity to noxious stimuli on the part of African Americans may be associated with ethnic differences in reported clinical pain, although the magnitude of ethnic differences was much greater for ischemic pain tolerance than for clinical pain measures.

http://www.pain-initiative-un.org/doc-center/articulos%20y%20documentos/dolor%20e%20implicaciones%20sociales/ethnic%20differences%20in%20pain.pdf

Ethnic differences in pain tolerance: clinical implications in a chronic pain population.

Summary During chewing, food is reduced in size, while saliva moistens the food and binds the masticated food into a bolus that can be easily swallowed. Characteristics of the oral system, like number of teeth, bite force and salivary flow, will influence the masticatory process. Masticatory function of healthy persons has been studied extensively the last decades. These results were used as a comparison for outcomes of various patient groups. In this review, findings from literature on masticatory function for both healthy persons and patient groups are presented. Masticatory function of patients with compromised dentition appeared to be significantly reduced when compared with the function of healthy controls. The influence of oral rehabilitation, e.g. dental restorations, implant treatment and temporomandibular disorder treatment, on masticatory function will be discussed. For instance, implant treatment was shown to have a significant positive effect on both bite force and masticatory performance. Also, patient satisfaction with an implant-retained prosthesis was high in comparison with the situation before implant treatment. The article also reviews the neuromuscular control of chewing. The jaw muscle activity needed to break solid food is largely reflexly induced. Immediate muscle response is necessary to maintain a constant chewing rhythm under varying food resistance conditions. Finally, the influence of food characteristics on the masticatory process is discussed. Dry and hard products require more chewing cycles before swallowing than moist and soft foods. More time is needed to break the food and to add enough saliva to form a cohesive bolus suitable for swallowing.

Assessment of mastication with implications for oral rehabilitation: a review

Children, 4-6 years old, 153 Caucasian and 50 African-American, from a pre-school and kindergarten programme in a low income industrial area, who participated in a voluntary oral health examination, were questioned and examined for signs and symptoms of craniomandibular disorders (CMD) and of oral parafunctions. Most of the CMD signs and symptoms were mild. Eight per cent had recurrent (at least 1-2 times per week) TMJ pain, and 5% had recurrent neck pain, African-American children more often than Caucasian children (P < 0.05). Seventeen per cent had recurrent headache. Three per cent had recurrent earache. Pain or tiredness in the jaws during chewing was reported by 25% of the children, more often by African-American than by Caucasian children (P < 0.001) and more often by girls than by boys (P < 0.05). Pain at jaw opening occurred in 10% of the children, more often in the African-American than in the Caucasian group (P < 0.001). Thirteen per cent of the children had problems in opening the mouth. Deviation during opening was observed in 17% and reduced opening in 2%. Reduced lateral movements, locking or luxation were not observed in any child. Palpation pain was found in the lateral TMJ area in 16%, in the posterior TMJ area in 25%, in the temporalis and masseter areas in 10%, and pain for all regions was found more often in the African-American than in the Caucasian children (P < 0.01). Thirty-four per cent of the African-American, and 15% of the Caucasian children admitted to having ear noises (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

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Prevalence of signs and symptoms of craniomandibular disorders and orofacial parafunction in 4-6-year-old African-American and Caucasian children.

Oral parafunctions are generally considered to be important factors in the etiology of temporomandibular disorders (TMDs) and many reports have been published about their prevalence in adults and schoolchildren However, few have included significant numbers of children below the age of 7 The aim of this study was to examine the association between parafunctions and oral/facial TMD-related pain in preschool children Bruxism, nail biting, and thumb sucking were found to be significantly associated with important oral/facial pain symptoms of clinical interest in the diagnoses of TMD indicating that those parafunctions are risk factors The study included 525 4- to 6-year-old African-American and Caucasian children, mean age 51 +/- 065 (SD) An alpha level of 5% was chosen for comparison with a Pearson Chi-Square test Bonferroni correction was made and a p-value of < 0005 was accepted as significance level Only 28% of the children had no history of any parafunction More girls (82%) than boys (63%) in the Caucasian subgroup had at least one parafunction (p approximately 000017) No such difference was found in the African-American subgroup where the corresponding figures were 71% for girls and 73% for boys Thumb sucking was reported by 57% of the children, more often by Caucasian girls (69%) than by Caucasian boys (43%) (p < 000001) Thirty percent still had the habit Forty-one percent had a history of nail biting Bruxism was noted in 20% of the children, but occurred mostly in combination with other parafunctions and was seldom (in 34%) the only parafunction Of the 10 pain variables, bruxism was significantly associated with eight, thumb sucking with three, and nail biting with two Analysis with logistic regression confirmed the results Association does not, however, tell if a parafunction is the cause or the consequence of pain, or if a third factor is causing both pain and increased prevalence of oral parafunctions Further prospective longitudinal studies including higher age groups are needed to clarify those relations and to determine if there are long-term effects of childhood parafunctions

Oral Parafunctions as Temporomandibular Disorder Risk Factors in Children

The associations between oral parafunctions, signs and symptoms of craniomandibular disorders (CMD), race, and sex were analysed in recordings from 203 4-6-year-old African-American and Caucasian children. Significant correlations were found between bruxism, nail biting, thumb sucking and most of the CMD signs and symptoms. There were also significant associations between most of the signs and symptoms and race, while significant association with sex was found only regarding headache, TMJ sounds and chewing pain. Significant associations were found between most CMD signs and TMJ sounds supporting the view that joint sound recordings have diagnostic value. There were also significant associations between the pain variables recorded by questionnaire and those recorded by palpation, which indicates that reliable data can be obtained by interviewing children as young as five. The results of this study support the concept that oral parafunctions have a significant role in the aetiology of CMD. The results also show that race and sex need to be considered when analysing the possible aetiological role of oral parafunctions in CMD. Longitudinal studies, beginning with low age groups are needed to better determine the role of childhood oral parafunctions in CMD aetiology.

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Association between CMD signs and symptoms, oral parafunctions, race and sex, in 4-6-year-old African-American and Caucasian children.

summary For analysis of time-varying signals such as the TMJ sounds, it is often desirable to know how the frequency components change with time, using methods of timefrequency analysis. The aim of this study was to compare two of the most familiar methods for energy density representation with a newly developed technique. The sounds were recorded with a microphone fastened to the subject’s forehead, transformed to the time-frequency domain and displayed as 3D- and contour plots using spectrogram, Wigner distribution (WD), and the reduced interference distribution (RID) to display their time-frequency energy distributions. The spectrogram resolved only the lowfrequency components. The WD provided higher resolution but also exhibited strong interference between components. The RID gave a detailed representation of the TMJ signals’ relative energy distribution in the time and frequency domains, with a great reduction in the interference or cross terms. The RID therefore appears to be most useful in the application of time-frequency distributions in classification of TMJ sounds.

/pdf/time-frequency-distributions-of-tmj-sounds-1xm7m3zt4l.pdf

Time frequency distributions of TMJ sounds

The aim was to test the hypothesis that developmental mandibular asymmetry is associated with increased asymmetry in muscle activity. Patients with mandibular condylar and/or ramus hyperplasia having unilateral cross-bite were compared with healthy subjects with normal occlusion. Muscle activity was recorded with surface electrodes in the masseter, suprahyoid, sternocleidomastoid muscle (SCM) and upper trapezius areas during jaw opening-closing-clenching, head-neck flexion-extension, and elevation-lowering of shoulders. Root mean square (RMS) and mean power frequency (MPF) values were calculated and analysed using anova and t-tests with P < 0.05 chosen as significance level. The SCM and masseter muscles showed co-activation during jaw and head movements, significantly more asymmetric in the patients than in the healthy subjects. The RMS and MPF values were higher in the patients than in the controls in the SCM and suprahyoid areas on both sides during jaw opening-closing movement. The results indicate that the ability to perform symmetric jaw and neck muscle activities is disturbed in patients with developmental mandibular asymmetry. This is of clinical interest because asymmetric activity may be an etiologic factor in temporomandibular joint and cervical pain. The results support that co-activation occurs between jaw and neck muscles during voluntary jaw opening and indicate that postural antigravity reflex activity occurs in the masseter area during head extension. Further studies, where EMG recordings are made from the DMA patients at early stages are motivated to verify activity sources and test if the asymmetric activity is associated with muscle and joint pain in the jaw and cervical areas.

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Sven E. Widmalm

Papers

Prevalence of signs and symptoms of craniomandibular disorders and orofacial parafunction in 4-6-year-old African-American and Caucasian children.

Oral Parafunctions as Temporomandibular Disorder Risk Factors in Children

Association between CMD signs and symptoms, oral parafunctions, race and sex, in 4-6-year-old African-American and Caucasian children.

Time frequency distributions of TMJ sounds

Asymmetric muscle function in patients with developmental mandibular asymmetry