Consensus on the terminologies and methodologies for masticatory assessment.

A large number of methodological procedures and experimental conditions are reported to describe the masticatory process. However, similar terms are sometimes employed to describe different methodologies. Standardisation of terms is essential to allow comparisons among different studies. This article was aimed to provide a consensus concerning the terms, definitions and technical methods generally reported when evaluating masticatory function objectively and subjectively. The consensus is based on the results from discussions and consultations among world-leading researchers in the related research areas. Advantages, limitations and relevance of each method are also discussed. The present consensus provides a revised framework of standardised terms to improve the consistent use of masticatory terminology and facilitate further investigations on masticatory function analysis. In addition, this article also outlines various methods used to evaluate the masticatory process and their advantages and disadvantages in order to help researchers to design their experiments.

A training program for fibromyalgia management: A 5-year pilot study.

We studied the effects of a specific cardio training program lasting 5 years on pain and quality of life in fibromyalgia patients. METHOD: An observational longitudinal pilot study was conducted in 138 fibromyalgia women. Fibromyalgia women recruited were asked to carry out three sessions per week, each lasting 45 min, of moderate-intensity continuous training (64%-75% Maximal Heart rate [HRmax]). During the first year, the patients progressively increased their training intensity. During the last 2 years, the patients were asked to associate moderate-intensity continuous training and high-intensity interval training (85%-90% HRmax). Pain on a visual analog scale, anxiety and depression state on the Hospital Anxiety and Depression Scale, impact of fibromyalgia on daily life using the Fibromyalgia Impact Questionnaire, heart rate and sleep quality (visual analog scale) were assessed at baseline and each year for 5 years. RESULTS: Forty-nine patients dropped out in the first year. Depending on their training status, the remaining 89 patients were retrospectively assigned to one of the three groups: Active (moderate-intensity continuous training), Semi-Active (one or two sessions, low-intensity continuous training <60% HRmax) and Passive (non-completion of training), based on their ability to comply with the program. Alleviation of all symptoms (p < 0.0001) was observed in the Active group. Increasing exercise intensity enhanced the effects obtained with moderate-intensity continuous training. Significant change in the Fibromyalgia Impact Questionnaire (p < 0.0001) and depression (Hospital Anxiety and Depression Scale; p < 0.0001), and no significant decrease in pain were noted in the Semi-Active group. No effect of the training was observed in the Passive group. CONCLUSION: The study intervention associated with multidisciplinary care alleviated pain, anxiety and depression, and improved both quality of life and quality of sleep, in fibromyalgia patients.

Masticatory Adaptation to Occlusal Changes.

This review deals with the frequent wide variability of masticatory capacity/incapacity. Neither researchers nor clinicians have taken sufficient account of this variability despite its implications for nutrition. Mastication in normal healthy oral conditions is first described, followed by a short presentation of the mechanisms of masticatory adaptation in the nervous system. Capacity, incapacity, and successful compensatory adaptation of mastication are then defined, along with the different methods used for their evaluation. Examples of adaptation needs are given, such as those concomitant with dental wear or occlusal changes. Finally, given its vital importance for deeply impaired mastication/deglutition function, the impact of masticatory adaptation processes on nutrition is examined.

Impact of a specific training programme on the neuromodulation of pain in female patient with fibromyalgia (DouFiSport): a 24-month, controlled, randomised, double-blind protocol.

INTRODUCTION: The main symptom of fibromyalgia (FM) is diffuse pain. There is currently no aetiological treatment for FM. However, all pain associations and best practice guidelines strongly advocate the practice of aerobic physical activity to improve the symptoms of FM subjects. The mechanisms of dysfunctional pain are mostly central and related to stress axis dysfunction (autonomic nervous system and corticotropic axis). Our main objective is to assess the efficacy of a specific training programme on endogenous pain control mechanisms in female patients with FM. Further aims include rebalancing the autonomic neurovegetative system, improving quality of life and sleep quality, and reintegrating patients into society and work. METHODS AND ANALYSIS: 110 female patients with FM diagnosed on American College of Rheumatology 2010 criteria, aged 18-65 years and meeting inclusion conditions will be recruited and randomised into two groups (active and semiactive). The training programme will consist of three 45 min sessions per week of supervised, individualised physical activity over 2 years. Only the intensity of the exercises will differ between the two groups (moderate intensity vs low intensity).All outcome measures will be conducted at baseline (T0), after 6-9 months of training (T6-9) and after 24 months of training (T24). The primary endpoint will be an improvement of pain modulation (activation of diffuse noxious inhibitory control) evaluated by the stimulation test. The secondary endpoint will be relief of pain, anxiety, depression, stress, sleep disorders, pain impact on life quality, and improved heart rate, blood pressure and salivary cortisol. ETHICS AND DISSEMINATION: This study is approved by the Committee for the Protection of Persons West VI. The results will be published in specialised scientific journals and will be presented at scientific meetings on pain and/or physical activity. TRIAL REGISTRATION NUMBER: NCT02486965; Pre-results.

Burning mouth syndrome.

Objective To review the clinical entity of primary burning mouth syndrome (BMS), its pathophysiological mechanisms, accurate new diagnostic methods and evidence-based treatment options, and to describe novel lines for future research regarding aetiology, pathophysiology, and new therapeutic strategies. Description Primary BMS is a chronic neuropathic intraoral pain condition that despite typical symptoms lacks clear clinical signs of neuropathic involvement. With advanced diagnostic methods, such as quantitative sensory testing of small somatosensory and taste afferents, neurophysiological recordings of the trigeminal system, and peripheral nerve blocks, most BMS patients can be classified into the peripheral or central type of neuropathic pain. These two types differ regarding pathophysiological mechanisms, efficacy of available treatments, and psychiatric comorbidity. The two types may overlap in individual patients. BMS is most frequent in postmenopausal women, with general population prevalence of around 1%. Treatment of BMS is difficult; best evidence exists for efficacy of topical and systemic clonazepam. Hormonal substitution, dopaminergic medications, and therapeutic non-invasive neuromodulation may provide efficient mechanism-based treatments for BMS in the future. Conclusion We present a novel comprehensive hypothesis of primary BMS, gathering the hormonal, neuropathic, and genetic factors presumably required in the genesis of the condition. This will aid in future research on pathophysiology and risk factors of BMS, and boost treatment trials taking into account individual mechanism profiles and subgroup-clusters.

Only severe malocclusion correlates with mastication deficiency.

OBJECTIVES: The relation between level of dentofacial deformity and extent of masticatory deficiency was studied. DESIGN: Three groups of human young adults were formed: (i) subjects needing orthodontics plus orthognathic surgery (SevDFD, n=18), (ii) subjects needing orthodontic treatment only (ModDFD, n=12), and (iii) subjects needing no treatment (NoDFD, n=12). For mastication tests, carrot boluses were collected at the deglutition time. Bolus particle size range was expressed as d50 value, which was compared with the Masticatory Normative Indicator (MNI). Index of treatment need (IOTN), global oral health assessment index (GOHAI) and chewing kinematic characteristics were also recorded. We used a general linear model univariate procedure followed by a Student-Newman-Keuls test. RESULTS: All the SevDFD subjects showed impaired mastication with MNI above the normal limit (d50 mean=7.23mm). All the ModDFD subjects but one were below this limit (d50 mean=2.54mm), and so could adapt to a low level of masticatory impairment as also indicated by kinematics. IOTN indicated a treatment need for ModDFD (3.7±0.5) and SevDFD (4.3±0.6) groups, while GOHAI values were unsatisfactory only for SevDFD (42.6±9.2 vs. 55.3±1.9). CONCLUSIONS: Our findings emphasize the need for an objective evaluation of masticatory function to discern truly deficient mastication from mild impairment allowing satisfactory adaptation of the function. However, malocclusions are known to worsen with time justifying thus their corrections as early as possible.

Dysfunctional stress responses in chronic pain.

Many dysfunctional and chronic pain conditions overlap. This review describes the different modes of chronic deregulation of the adaptive response to stress which may be a common factor for these conditions. Several types of dysfunction can be identified within the hypothalamo-pituitary-adrenal axis: basal hypercortisolism, hyper-reactivity, basal hypocortisolism and hypo-reactivity. Neuroactive steroid synthesis is another component of the adaptive response to stress. Dehydroepiandrosterone (DHEA) and its sulfated form DHEA-S, and progesterone and its derivatives are synthetized in cutaneous, nervous, and adipose cells. They are neuroactive factors that act locally. They may have a role in the localization of the symptoms and their levels can vary both in the central nervous system and in the periphery. Persistent changes in neuroactive steroid levels or precursors can induce localized neurodegeneration. The autonomic nervous system is another component of the stress response. Its dysfunction in chronic stress responses can be expressed by decreased basal parasympathethic activity, increased basal sympathetic activity or sympathetic hyporeactivity to a stressful stimulus. The immune and genetic systems also participate. The helper-T cells Th1 secrete pro-inflammatory cytokines such as IL-1-ß, IL-2, IL-6, IL-8, IL-12, IFN-γ, and TNF-α, whereas Th2 secrete anti-inflammatory cytokines: IL-4, IL-10, IGF-10, IL-13. Chronic deregulation of the Th1/Th2 balance can occur in favor of anti- or pro-inflammatory direction, locally or systemically. Individual vulnerability to stress can be due to environmental factors but can also be genetically influenced. Genetic polymorphisms and epigenetics are the main keys to understanding the influence of genetics on the response of individuals to constraints.

Different types of antagonists modify the outcome of complete denture renewal.

PURPOSE: The effect of renewing removable dentures on masticatory function was evaluated according to the occlusion offered by different types of mandibular arches. MATERIALS AND METHODS: Twenty-eight patients with complete maxillary dentures were subdivided into three groups in terms of mandibular dentition type: dentate, partial denture, and complete denture. The participants were observed before and 8 weeks after maxillary denture renewal. The mandibular denture was also renewed in the partial and complete denture groups. The participants masticated carrots, peanuts, and three model foods of different hardnesses. The particle size distribution of the boluses obtained from natural foods was characterized by the median particle size (d50) in relation to the masticatory normative indicator (MNI). Chewing time (CT), number of chewing cycles (CC), and chewing frequency (CF) were video recorded. A self-assessment questionnaire for oral health-related quality of life (Geriatric Oral Health Assessment Index [GOHAI]) was used. Statistical analyses were carried out with a mixed model. RESULTS: Renewal of the dentures decreased d50 (P < .001). The number of participants with d50 values above the MNI cutoff decreased from 12 to 2 after renewal. Renewal induced an increase in mean CF while chewing model foods (P < .001). With all foods, renewal tended to affect CT, CC, and CF differently among the three groups (statistically significant renewal Å~ group interactions). The GOHAI score increased significantly for all groups. CONCLUSIONS: Denture renewal improves masticatory function. The complete denture group benefited least from renewal; the dentate group benefited most. This study confirmed the usefulness of denture renewal for improving functions and oral health- related quality of life.

Effect of experimental stress in 2 different pain conditions affecting the facial muscles.

UNLABELLED: Chronic facial muscle pain is a common feature in both fibromyalgia (FM) and myofascial (MF) pain conditions. In this controlled study, a possible difference in the mode of deregulation of the physiological response to a stressing stimulus was explored by applying an acute mental stress to FM and MF patients and to controls. The effects of the stress test were observed on pain, sympathetic variables, and both tonic and reflex electromyographic activities of masseteric and temporal muscles. The statistical analyses were performed through a generalized linear model including mixed effects. Painful reaction to the stressor was stronger (P < .001) and longer (P = .011) in FM than in MF independently of a higher pain level at baseline. The stress-induced autonomic changes only seen in FM patients did not reach significance. The electromyographic responses to the stress test were strongest for controls and weakest for FM. The stress test had no effect on reflex activity (area under the curve [AUC]) or latency, although AUC was high in FM and latencies were low in both pain groups. It is suggested that FM is characterized by a lower ability to adapt to acute stress than MF. PERSPECTIVE: This study showed that an acute psychosocial stress triggered several changes in 2 pain conditions including an increase in pain of larger amplitude in FM than in MF pain. Similar stress-induced changes should be explored as possible mechanisms for differentiation between dysfunctional pain conditions.

Clinical interpretation of a masticatory normative indicator analysis of masticatory function in subjects with different occlusal and prosthodontic status.

OBJECTIVES: To analyse the masticatory function of subjects characterised by different occlusal and prosthodontic status. Using Optosil(®) as a test food, the masticatory normative indicator (MNIOPT) was used to differentiate between sufficient ('normal') and impaired masticatory function. METHODS: Outcomes of occlusal force and masticatory tests were aggregated from three earlier studies dealing with four denture groups and three natural dentition groups. The four denture groups had a complete removable dental prosthesis in the upper jaw, and displayed one of the four following lower jaw prosthodontic rehabilitations: (i) complete removable dental prosthesis on a low mandible; (ii) complete removable dental prosthesis on a higher mandible; (iii) overdenture on natural roots; and (iv) overdenture on dental implants. The three natural dentition groups were: (i) shortened dental arch; (ii) complete dentition in older participants, and (iii) complete dentition in younger participants. All participants were women. They performed the same tests twice, and outcomes were averaged. RESULTS: A MNIOPT value of 3.68 mm was determined from the participants with complete natural dentitions. Applying the MNIOPT to the participants in the denture groups pointed at a considerable chance for impaired masticatory function, except for participants in the overdenture -implants group. The four denture groups compensated for reduced masticatory efficiency by increased number of masticatory cycles and prolonged mastication time until 'swallowing'. Nevertheless, they also 'swallowed' larger particles compared to the complete dentition group. CLINICAL SIGNIFICANCE: For a given patient or for a group of subjects with specific dental conditions, MNI enables to discriminate between a sufficient ('normal') and an impaired masticatory function.

Contributory role of the tongue and mandible in modulating the in-mouth air cavity at rest.

OBJECTIVES: The tongue-to-palate distance influences the volume of the in-mouth air cavity (IMAC), thus conditioning the entry of aromatic compounds to the olfactory mucosa site. This study was set out to record the IMAC volume by measuring tongue-to-palate distance at rest. MATERIALS AND METHODS: Twelve young adults in good general health were tested--lips contacting, with at-rest posture of the tongue and jaw during a silent reading task. Observations in this study were limited to pre- and post-swallowing sequences. The tongue-to-palate distance was measured using three electromagnetic sensors placed on the tongue upper surface. IMAC volume was evaluated from a geometrical model, taking into account the tongue-to-palate distance, the IMAC transversal distance measured from dental casts and historic data giving the anterior-posterior distance of the oral cavity. RESULTS: (1) In the at-rest posture, the tongue-to-palate distance was significantly greater at the posterior sensor level. (2) A vertical shift in tongue posture at rest frequently appeared following deglutition. The upward shifts were of larger amplitude and more frequent than the downward shifts. (3) Evaluation of the IMAC volume gave an approximate value of 12 ml at rest. (4) The chin sensor at rest was 2.8 ± 0.8 mm below its position when in occlusion. CONCLUSION: The tongue and mandible contribute to shaping the IMAC volume. CLINICAL RELEVANCE: These and other results suggest that deglutition changes tongue-to-palate distance and influences aroma release during mastication/deglutition acts through modulation of the IMAC volume.

Retro-nasal aroma release is correlated with variations in the in-mouth air cavity volume after empty deglutition.

We hypothesized that interindividual differences in motor activities during chewing and/or swallowing were determining factors for the transfer of volatile aroma from the in-mouth air cavity (IMAC) toward the olfactory mucosa. In our first experiment, we looked for changes in IMAC volume after saliva deglutition in 12 healthy subjects. The mean IMAC volume was measured after empty deglutition using an acoustic pharyngometer device. Based on the time course of the IMAC volume after swallowing, we discerned two groups of subjects. The first group displayed a small, constant IMAC volume (2.26 mL ±0.62) that corresponded to a high tongue position. The second group displayed a progressive increase in IMAC (from 6.82 mL ±2.37 to 22.82 mL ±3.04) that corresponded to a progressive lowering of the tongue to its resting position. In our second experiment, we investigated the relationship between IMAC volume changes after deglutition and the level of aroma release at the nostril. For this purpose, the release of menthone was measured at the nostril level in 25 subjects who consumed similar amounts of a mint tablet. The subjects were separated into two groups corresponding to two levels of menthone release: high (H) and low (L). The mean volume of IMAC was measured during and after empty deglutition. Group H displayed a small, constant amplitude of IMAC volume change after deglutition, while Group L displayed a progressive increase in IMAC. It is likely that Group H continuously released the aroma through the veloglossal isthmus as the mint was consumed, while Group L trapped the aroma in the oral cavity and then released it into the nasal cavity upon swallowing. These results show that the in vivo aroma release profile in humans depends closely on the different motor patterns at work during empty deglutition.

Role of physical bolus properties as sensory inputs in the trigger of swallowing.

BACKGROUND: Swallowing is triggered when a food bolus being prepared by mastication has reached a defined state. However, although this view is consensual and well supported, the physical properties of the swallowable bolus have been under-researched. We tested the hypothesis that measuring bolus physical changes during the masticatory sequence to deglutition would reveal the bolus properties potentially involved in swallowing initiation. METHODS: Twenty normo-dentate young adults were instructed to chew portions of cereal and spit out the boluses at different times in the masticatory sequence. The mechanical properties of the collected boluses were measured by a texture profile analysis test currently used in food science. The median particle size of the boluses was evaluated by sieving. In a simultaneous sensory study, twenty-five other subjects expressed their perception of bolus texture dominating at any mastication time. FINDINGS: Several physical changes appeared in the food bolus as it was formed during mastication: (1) in rheological terms, bolus hardness rapidly decreased as the masticatory sequence progressed, (2) by contrast, adhesiveness, springiness and cohesiveness regularly increased until the time of swallowing, (3) median particle size, indicating the bolus particle size distribution, decreased mostly during the first third of the masticatory sequence, (4) except for hardness, the rheological changes still appeared in the boluses collected just before swallowing, and (5) physical changes occurred, with sensory stickiness being described by the subjects as a dominant perception of the bolus at the end of mastication. CONCLUSIONS: Although these physical and sensory changes progressed in the course of mastication, those observed just before swallowing seem to be involved in swallowing initiation. They can be considered as strong candidates for sensory inputs from the bolus that are probably crucially involved in the triggering of swallowing, since they appeared in boluses prepared in various mastication strategies by different subjects.

Effect of lingual nerve block on burning mouth syndrome (stomatodynia): a randomized crossover trial.

Burning mouth syndrome (stomatodynia) is associated with changes of a neuropathic nature the main location of which, peripheral or central, remains unknown. A randomised, double-blind crossover design was used to investigate the effects of lingual nerve block on spontaneous burning pain and a possible correlation with the effects of topical clonazepam, the patient's response to a psychological questionnaire, and the taste and heat thresholds. The spontaneous burning was measured with a visual analogue scale (VAS) just before and 15 min after injection. The decreases in VAS score after lidocaine or saline injection were not significantly different (2.7+/-3.9 and 2.0+/-2.6, respectively; n=20). However, two groups of patients could be identified: in a "peripheral group" (n=10) the VAS decrease due to lingual nerve injection was 4.3+/-3.1cm after lidocaine and 0.9+/-0.3 cm after saline (p=0.02). In a "central group" (n=7), there were an increase in pain intensity score (-0.8+/-2.6 cm) after lidocaine and a decrease (1.5+/-3.0 cm) after saline (p=0.15). An increase in the hospital anxiety and depression (HAD) score and a decreased taste sensitivity and heat pain threshold of painful oral area were seen in patients compared with age-and-sex-matched controls (p<0.05). Topical clonazepam treatment tended to be more effective (p=0.07) and HAD score lower (p<0.03) in the peripheral than in the central group. These results suggest that the neuropathic disorder associated with stomatodynia may be predominantly peripheral, central or mixed depending on the individual. Topical application of clonazepam and HAD may serve as indicators of which mechanism is dominating.

Steroid dysregulation and stomatodynia (burning mouth syndrome).

Stomatodynia ( burning mouth syndrome) is characterized by a spontaneous, continuous burning pain felt in the oral mucosa typically of anxiodepressive menopausal women. Because there is no obvious organic cause, it is considered a nonspecific pain. This Focus Article proposes a hypothesis based on the following pathophysiological cascade: chronic anxiety or post traumatic stress leads to a dysregulation of the adrenal production of steroids. One consequence is a decreased or modified production of some major precursors for the neuroactive steroid synthesis occurring in the skin, mucosa, and nervous system. At menopause, the drastic fall of the other main precursor supply , the gonadal steroids, leads to a brisk alteration of the production of neuroactive steroids. This results in neurodegenerative alterations of small nerves fibers of the oral mucosa and /or some brain areas involved in oral somatic sensations. These neuropathic changes become irreversible and precipitate the burning pain, dysgeusia, and xerostomia associated with stomatodynia, which all involve thin nerve fibers.

From movement to pain: a tribute to professor James P. Lund.

This tribute article to Professor James P. Lund stems from 6 of the presentations delivered at the July 1, 2008, symposium that honored 3 "giants" in orofacial neuroscience: B. J. Sessle, A. G. Hannam, and J. P. Lund. It was noted that soon after his training as a dentist in Australia, Jim Lund became interested in research. At the time he decided to do a PhD, there was a lot of discussion about how rhythmic movements were programmed. The early belief, based on Sherrington's studies of motor systems, was that these movements were simply an alternating series of reflexes. In the late 1960s and early 1970s, some still shared this belief, whereas others favored Graham Brown's hypothesis that repetitive movements were centrally programmed and did not depend on reflexes triggered by sensory inputs. There was no strong evidence then for either scenario except for the rhythmic movements of respiration. Lund's pioneering work during his PhD proved the existence of a central pattern generator (CPG) for mastication in the brainstem. Since then he has been interested in understanding how CPGs function and how sensory feedback works to adjust the motor patterns that they produce. Sections in this tribute article to Lund are written by some of his close collaborators and reflect the evolution of his work throughout the years. The first 4 presentations in this article (by K.-G. Westberg, D. McFarland, A. Kolta, and C. Stohler) highlight various aspects of these interests, and the final 2 presentations (by J. Feine and A. Woda) focus especially on clinical aspects of Lund's interests. The last section of this article is a final commentary from Professor Lund.