Oral hygiene behaviour automaticity: Are toothbrushing and interdental cleaning habitual behaviours?

OBJECTIVES: Toothbrushing and interdental cleaning are critical to maintaining good oral health. Literature is beginning to suggest that these behaviours may be conducted automatically, although the instigation ('deciding to do') and execution ('doing') of these behaviours has never been examined separately. The objective of this study was to test a theoretically informed supposition that oral hygiene behaviours in adults are automatic behaviours. METHODS: One hundred and fifty participants attending three types of dental providers covering emergency and routine dental services, completed a questionnaire. The self-reported behavioural automaticity index scale (SRBAI) was used to measure behavioural automaticity. RESULTS: Morning toothbrushing SRBAI scores were higher than evening scores (Z=-3.315, p = 0.001). Automaticity scores for instigating both toothbrushing and interdental cleaning were also higher compared to execution (toothbrushing: Z=-2.601, p = 0.009 and interdental cleaning: Z=-2.256. p = 0.024). Toothbrushing automaticity scores were associated with age, gender and self-efficacy, whereas interdental cleaning automaticity scores were associated with intention. Individuals in lower socio-economic status (SES) occupations had significantly higher automaticity scores for interdental cleaning compared to those with higher SES roles. CONCLUSIONS: A high proportion of people undertake toothbrushing and interdental cleaning automatically, especially in relation to embarking on these behaviours. This is most pronounced in morning toothbrushing. CLINICAL SIGNIFICANCE: Promoting improvements in oral hygiene behaviour toothbrushing and interdental cleaning are key strategies in preventing caries and periodontal disease. A greater understanding of what prompts and sustains these behaviours helps inform how behaviour change efforts should be approached.

Using a cost function based on kinematics and electromyographic data to quantify muscle forces.

A reliable evaluation of muscle forces in the human body is highly desirable for several applications in both clinical and research contexts. Several models of muscle force distribution based on non-invasive measurements have been proposed since 1836 (Weber and Weber, 1836), amongst which Crowninshield's model (Crowninshield and Brand, 1981), which maximizes a cost-function representing the muscle fiber endurance, is the most popular. It is worth noting that Crowninshield's model is the most widely adopted notwithstanding its major limitations of physiological coherence. Forster et al. (2004) pointed out that "these (conventional) criteria however do not predict co-contraction adequately". Besides, electromyographic (EMG)-driven models have been proposed to assess individual muscle forces, which have not been broadly adopted due to their complexity and the need for a calibration before each test. In this context, a cost function based on kinematic and electromyographic data could provide the advantage of being physiologically more coherent with muscle activations compared to conventional cost-functions based on kinematics solely, and easier to use than the EMG-driven models. The objective of this study is to propose the first cost-function based on kinematics and electromyographic data to quantify muscle forces. When applying this new cost-function on a database of upper limb motions data of 17 subjects, healthy or with cerebral palsy, the muscle force prediction of the proposed model was 17.74% more coherent with the EMG pattern than the prediction of Crowninshield's model. And on average, these results were more consistent whether the subjects were healthy or with cerebral palsy. In conclusion, we propose this cost-function for the quantification of muscle forces.

Decomposition of three-dimensional ground-reaction forces under both feet during gait.

Three-dimensional ground reaction forces (3D-GRF) are essential for functional evaluation for rehabilitation. A platform path is required to obtain the 3D-GRF. The main shortcoming of these platform paths is that during double stance phases of gait, both feet can be placed on the same force platform causing the need for decomposing the 3D-GRF under each foot. Despite the high number of studies on force decomposition, there is still no method on the decomposition of 3D-GRF based on data from platforms. OBJECTIVE: This study aims to present an automatic method using parametric curve fitting modeling to increase the accuracy of decomposition of 3D-GRF during double stances under each foot. METHODS: The decomposition method was applied to the global 3D-GRF using 3rd order polynomial, sine, and sine-sigmoid functions. The computed 3D-GRF was compared to the 3D-GRF independently recorded by force platforms for each subject. RESULTS: The relative average error between the computed 3D-GRF and the recorded 3D-GRF were equal to 3.3±1.6%. In details for the vertical, antero-posterior, and medio-lateral GRF, these errors were 2.9±1.6%, 6.3±4.3%, and, 9.5±3.6%, respectively, for 30 subjects. CONCLUSION: The global error on the GRF is the best one in the literature. This method can be validated on various populations with musculoskeletal disorders.

Pathological and physiological muscle co-activation during active elbow extension in children with unilateral cerebral palsy.

OBJECTIVE: To address the roles and mechanisms of co-activation in two flexor/extensor pairs during elbow extension in children with cerebral palsy (CP). METHODS: 13 Typically Developing (TD) and 13 children with unilateral spastic CP performed elbow extension/flexion at different speeds. Elbow angle and velocity were recorded using a 3D motion analysis system. The acceleration and deceleration phases of extension were analyzed. Co-activation of the brachioradialis/triceps and biceps/triceps pairs was computed for each phase from surface electromyographic signals. Statistical analysis involved linear mixed effects models and Spearman rank correlations. RESULTS: During the acceleration phase, there was strong co-activation in both muscle pairs in the children with CP, which increased with speed. Co-activation was weak in the TD children and it was not speed-dependent. During the deceleration phase, co-activation was strong and increased with speed in both groups; co-activation of brachioradialis/triceps was stronger in children with CP, and was negatively correlated with extension range and positively correlated with flexor spasticity. CONCLUSIONS: Abnormal patterns of co-activation in children with CP were found throughout the entire movement. Co-activation was specific to the movement phase and to each flexor muscle. SIGNIFICANCE: Co-activation in children with CP is both physiological and pathological.

Custom sizing of lower limb exoskeleton actuators using gait dynamic modelling of children with cerebral palsy.

The use of exoskeletons as an aid for people with musculoskeletal disorder is the subject to an increasing interest in the research community. These devices are expected to meet the specific needs of users, such as children with cerebral palsy (CP) who are considered a significant population in pediatric rehabilitation. Although these exoskeletons should be designed to ease the movement of people with physical shortcoming, their design is generally based on data obtained from healthy adults, which leads to oversized components that are inadequate to the targeted users. Consequently, the objective of this study is to custom-size the lower limb exoskeleton actuators based on dynamic modeling of the human body for children with CP on the basis of hip, knee, and ankle joint kinematics and dynamics of human body during gait. For this purpose, a multibody modeling of the human body of 3 typically developed children (TD) and 3 children with CP is used. The results show significant differences in gait patterns especially in knee and ankle with respectively 0.39 and -0.33 (Nm/kg) maximum torque differences between TD children and children with CP. This study provides the recommendations to support the design of actuators to normalize the movement of children with CP.

Impact of muscle activation on ranges of motion during active elbow movement in children with spastic hemiplegic cerebral palsy.

BACKGROUND: Children with spastic hemiplegic cerebral palsy are restricted in their daily activities due to limited active ranges of motion of their involved upper limb, specifically at the elbow. Their impaired muscles are frequently targeted by anti-spastic treatments that reduce muscle tone. But these treatments do not necessarily improve the limb function. There is a lack of comprehensive knowledge of the quantitative relations between muscle activation and joint active ranges of motion. Consequently, the objective of this study is to quantify the impact of muscle activation on the elbow active ranges of motion. METHODS: During voluntary elbow pronation/supination and extension/flexion movements, kinematic and electromyographic measurements were collected from the involved upper limb of 15 children with spastic hemiplegic cerebral palsy (mean age=8.7 years, standard deviation=2.2) and the dominant upper limb of 15 age-matched children who are typically developing. Representative indicators of the muscle activation, such as the muscle co-activation, were extracted from the electromyographic measurements. FINDINGS: Muscle co-activation in the involved upper limb accounted for 78% and 59% of the explained variance of the supination and extension limited active ranges of motion respectively. The agonist and antagonist muscle activations were both longer in the involved upper limb. INTERPRETATIONS: This study succeeded in quantifying the impact of longer antagonist muscle activation on decreased elbow active ranges of motion in children with spastic hemiplegic cerebral palsy. Longer agonist muscle activation suggests that strengthening agonist muscles could increase the extension and supination ranges of motion, which constitutes a perspective of future clinical studies.

Decomposition of the vertical ground reaction forces during gait on a single force plate.

UNLABELLED: Davis and Cavanagh (1993) have proposed a solution to avoid the footstep targeting by using a large force plate but several points of Davis and Cavanagh's method remain unclear and hardly computable. OBJECTIVE: to develop a method that decomposes left and right GRF profiles from the GRF profile recorded on a single platform. This method aims to include a systematic detection of the single to double stand-phase-instants in order to lead to accurate measurement of the vertical GRF component in typically developing children. METHODS: Six children were asked to walk without targeting their footsteps on a set-up composed of independent force platforms. The vertical GRF component, independently measured on the different platforms, was numerically summed to obtain the corresponding global vertical GRF, to which the decomposition method was applied. Then, the validation consisted in comparing the vertical GRF computed from this decomposition to the independently measured vertical GRF. RESULTS: the mean relative error between the computed vertical GRF and the corresponding measured vertical GRF of 36 double stances (6 double stances x 6 children) is equal to 3.8±2.6%. CONCLUSION: implemented a new method to assess with known accuracy the vertical GRF component under each foot using a unique large force platform.

Quantification of intervertebral efforts during walking: comparison between a healthy and a scoliotic subject.

The accurate quantification of internal efforts in the human body is still a challenge in biomechanics. The aim of this study is to quantify the intervertebral efforts along the spine during walking, in order to compare the dynamical behaviours between a healthy and a scoliotic subject. Practically, one healthy subject, one scoliotic patient before an instrumentation surgery (Cobb 41 degrees ) and after this instrumentation (Cobb 7.5 degrees ) walked on a treadmill at 4 km/h. The acquisition system included optokinetic sensors, recording the 3D-joint coordinates, a treadmill equipped with strain gauges, measuring the external forces independently applied to both feet, and bi-planar radiographs, enabling the 3D reconstruction of the spine from C7 to L5, using a free form interpolation technique. The intervertebral efforts were computed using an inverse dynamical model of the human body in 3D. As results, significant differences of the spine kinematics were recorded which lead to different internal effort behaviour in magnitude, shift, coordination and pattern when normalized to the subject mass. Particularly, the normalized antero-posterior intervertebral torques are less uniform for the scoliotic patient (from min -2.5 to max 1.9 Nm/kg) than the healthy subject (from -1.5 to 1.5 Nm/kg). This disequilibrium in the left-right balance of the scoliotic patient is a bit rectified after surgery (from -1.3 to 1.1 Nm/kg).

Determination of joint efforts in the human body during maximum ramp pushing efforts.

Determining with accuracy, the internal efforts in the human body is a great challenge in Biomechanics, particularly in Physical Therapy and Ergonomics. In this context, the present study develops a human body model that permits a non-invasive determination of the joint efforts produced by a seated subject performing maximum ramp pushing efforts. The joint interactions during these experiments are provided by a dynamic inverse model of the human body, using a symbolically generated recursive Newton-Euler formalism. The theoretical investigation is presented in two steps, with increasing complexity and relevance:The dynamic model confirms some previous studies of the effects of biomechanical factors on the performance of the task and is proposed as an accurate method for determining the joint efforts in dynamic contexts. Finally, this application is a preliminary benchmark case that will be extended to: *physical therapy, in order to analyse the joint and muscle efforts in various motion contexts, particularly for patients with fibromyalgia and patients with lumbar diseases; *accidentology, in order to analyse and simulate car occupant dynamics before a crash.