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PubMed2001

Detection power, estimation efficiency, and predictability in event-related fMRI.

Experimental designs for event-related functional magnetic resonance imaging can be characterized by both their detection power, a measure of the ability to detect an activation, and their estimation efficiency, a measure of the ability to estimate the shape of the hemodynamic response. Randomized designs offer maximum estimation efficiency but poor detection power, while block designs offer good detection power at the cost of minimum estimation efficiency. Periodic single-trial designs are poor by both criteria. We present here a theoretical model of the relation between estimation efficiency and detection power and show that the observed trade-off between efficiency and power is fundamental. Using the model, we explore the properties of semirandom designs that offer intermediate trade-offs between efficiency and power. These designs can simultaneously achieve the estimation efficiency of randomized designs and the detection power of block designs at the cost of increasing the length of an experiment by less than a factor of 2. Experimental designs can also be characterized by their predictability, a measure of the ability to circumvent confounds such as habituation and anticipation. We examine the relation between detection power, estimation efficiency, and predictability and show that small increases in predictability can offer significant gains in detection power with only a minor decrease in estimation efficiency.

Artifacts↗

PubMed1990

Determination and interpretation of mechanical power in human movement: application to ergometer cycling.

Based on a model consisting of three rigid links, an instantaneous power equation has been deduced for ergometer cycling which shows a causal relationship between power liberated in joint rotation on the one hand and the rate of change of segmental energy plus the power transferred to the pedal on the other. The shape and magnitude of these two types of power have been calculated by measurements of pedal force and cinematographic analysis and the results show fair agreement between them. When cycling at a mean exercise intensity of 340 W at 90 rpm, less than 28 W appears to be lost in the (necessary) changes of segmental energies. It is suggested that power liberated in the joints should be judged as the source of power in the power equation. It is, therefore, proposed that this power should be defined as external power in this and other human movement.

Exercise↗

PubMed1992

Effects on efficiency in repetitive lifting of load and frequency combinations at a constant total power output.

Boxes were lifted and lowered repetitively at three different combinations of load and frequency. These combinations were chosen such that the total mechanical power generated was constant. Effects of the varying load or frequency conditions (but constant total mechanical power) on the rate of energy expenditure (M) and on the mechanical efficiency (ME) were measured. Mechanical power was determined from film analysis and separated into external power (generated to lift the load) and internal power (to raise the lifter's body mass). The M was determined from oxygen consumption measurements. The ME was calculated in two ways, depending on the definition of mechanical power, including either the external power only (MEext) or the total power output (MEtot). Despite a constant total mechanical power, M increased at higher loads and lower frequencies. This might be explained by the increasing isometric force required in postural and load control. The M increase resulted in a decrease of MEtot. However, at higher loads and lower frequencies MEext increased, indicating that more external work can be done at the same energy costs at higher loads or lower frequencies, which could be of interest from the point of view of occupational physiology. It would seem that at higher loads or lower frequencies the increased costs for isometric muscle action do not outweigh the benefit of raising the body less frequently. Furthermore, it was found that the MEext in lifting was much lower than the values reported for other kinds of activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Measurement of directional force and power during human submaximal and maximal isokinetic exercise.

An isokinetic cycle ergometer has been developed to measure power output generated over a wide range of constant velocities. The ergometer system has two operating modes and it can be instantly switched from one to another. In its conventional mode the cycle ergometer is connected to a conventional electrically braked cycle ergometer so that the subjects can perform submaximal steady-state exercise. For maximal power measurements the system can be instantly switched to an isokinetic control mechanism which allows a constant pedalling rate to be set in the range of 23-180 rev.min-1. In both operating modes the forces generated on the pedals are monitored by strain-gauges mounted inside the pedals. This enables information to be obtained regarding the direction of forces generated at the foot-pedal interface. The output from the strain-gauges was A-D converted and stored along with data giving pedal and crank position. Data was sampled 150 times in each revolution of the crank. Force data are usually analysed for maximal peak power (highest instantaneous power generated during each revolution), mean power (power generated over a complete revolution), extension and flexion power (power generated during leg extension and leg flexion respectively). This system allows characterisation of the relationship between maximal leg power and pedalling rate, both under control and exercise-induced potentiation and fatigue conditions. Thus it is possible for example to quantify instantly the magnitude of fatigue induced by preceding dynamic exercise of a given duration, intensity or contraction velocity.

Equipment Design↗

PubMed1984

The effects of motor unit synchronization on the power spectrum of the electromyogram.

A realistic model for two synchronized motor unit action potential trains (MUAPT) is presented in which the variability of the time difference between corresponding action potentials (hereafter denoted by delay) is taken into account. Specifically, this delay is modeled as a continuous random variable that may assume both positive and negative values. Expressions are derived for the auto- and cross-power spectra of two such trains using their relations with the auto- and cross-correlation functions, respectively, with which they form Fourier transform pairs. The results show that the auto- and the cross-power spectra of two such synchronized MUAPTs differ from the auto- and the cross-spectra of two independent MUAPTs. The contribution of the statistics of the interpulse intervals to one of the auto-power spectra is smaller and the cross-power spectra no longer reduce to a Dirac sigma-function at the origin but are now determined by the other auto-power spectrum and by the Fourier transform of the density function associated with the time difference between corresponding action potentials. As a consequence of this change in the cross-power spectra synchronization leads to an absolute increase of power at low frequencies and to a relative decrease of power at high frequencies. The results are then generalized to electromyograms (EMG) composed of more than just two MUAPTs and illustrated with simulated power spectra with which the theory shows excellent agreement.

Action Potentials↗

PubMed2006

Development of a strength test battery for evaluating leg muscle power after anterior cruciate ligament injury and reconstruction.

A more sports-specific and detailed strength assessment has been advocated for patients after anterior cruciate ligament (ACL) injury and reconstruction. The purpose of this study was to develop a test battery of lower extremity strength tests with high ability to discriminate between leg power development on the injured and uninjured sides in patients after ACL injury and in patients who have undergone ACL reconstruction. Twenty-three patients were tested 6 months after ACL injury and 44 patients were tested 6 months after ACL reconstruction. Twenty-four of the 44 patients were operated on using a hamstrings graft and 20 patients were operated on using a patellar tendon graft. All the patients performed a test battery of three strength tests for each leg in a randomised order. The three strength tests were chosen to reflect quadriceps and hamstring muscular power in a knee-extension and a knee-flexion test (open kinetic chain) and lower-extremity muscular power in a leg-press test (closed kinetic chain). There was a higher sensitivity for the test battery to discriminate abnormal leg power compared with any of the three strength tests individually. Nine out of ten patients after ACL reconstruction and six out of ten of the patients after ACL injury exhibited abnormal leg power symmetry using the test battery. Thus, this test battery had high ability in terms of discriminating between the leg power performance on the injured and uninjured side, both in patients with an ACL injury and in patients who have undergone ACL reconstruction. It is concluded that a test battery consisting of a knee-extension, knee-flexion and leg-press muscle power test had high ability to determine deficits in leg power 6 months after ACL injury and reconstruction. Only a minority of the patients had restored leg muscle power. The clinical relevance is that the test battery may contribute to the decision-making process when deciding whether and when patients can safely return to strenuous physical activities after an ACL injury or reconstruction.

Adult↗

PubMed1999

Power Doppler evaluation of joint effusions: investigation in a rabbit model.

OBJECTIVE: To study the power Doppler findings of septic arthritis and noninfectious synovitis in an animal model. MATERIALS AND METHODS: The right knees of 10 rabbits were inoculated with an aqueous suspension of Staphylococcus aureus. The right knees of 5 rabbits were injected with talc suspension. The right knees of 5 rabbits were injected with saline. All 20 left knees were injected with saline. Serial power Doppler images were obtained using constant-imaging parameters. Images were reviewed by blinded observers who assessed for increased power Doppler signal. RESULTS: All 10 knees inoculated with S. aureus developed septic arthritis. Each infected rabbit knee demonstrated increased signal on power Doppler on at least one examination, ranging from 1-6 days after inoculation. Only 23 of 45 examinations of infected knees were unequivocally positive by power Doppler on examinations performed 1 to 6 days after inoculation. No knee with talc synovitis demonstrated increased power Doppler signal. No control knee demonstrated increased power Doppler signal. CONCLUSION: Increased power Doppler signal may be seen with septic arthritis; however, its intensity and timing may vary from subject to subject. A normal power Doppler examination does not exclude septic arthritis.

Animals↗

PubMed2001

Dynamic contrast-enhanced power Doppler sonography improves the differential diagnosis of liver lesions.

The aim of this paper was to investigate the diagnostic value of dynamic contrast-enhanced power Doppler sonography in the differential diagnosis of liver lesions. We prospectively examined 85 focal liver lesions in 71 patients by real-time gray-scale sonography, power Doppler sonography, and contrast-enhanced power Doppler using two ultrasound contrast agents (Levovist, Optison). Amount and architecture of lesion vascularity and the kinetics of contrast enhancement within the lesions were analyzed. Vascularity was detected in 61% of liver lesions (52/85) by conventional power Doppler, compared to 86% (73/85) by contrast-enhanced power Doppler sonography. Dynamic contrast-enhanced power Doppler identified arterial radial hypervascularity <16 s after contrast injection in 19/22 focal nodular hyperplasias (86%). Irregular hypervascularity was seen with contrast enhancement in the arterial phase in 14/15 hepatocellular carcinomas (93%). In 14/25 hemangiomas (56%), a circular vascularization pattern was noted. Specific lesion diagnosis based on B-scan and conventional and dynamic contrast-enhanced power Doppler sonography led to correct diagnosis in 86% (73/85, 95% confidence interval 78%-94%) compared to 57% (48/85, 95% confidence interval 47%-94%) by B-scan criteria and conventional power Doppler sonography. Contrast-enhanced power Doppler sonography improves diagnostic accuracy in the differential diagnosis of focal liver lesions.

Albumins↗

PubMed2003

Comparison between young and older women in explosive power output and its determinants during a single leg-press action after optimisation of load.

Lower limb explosive power, which is more predictive of functional difficulties than strength per se with women being more at risk than men for disability, has been previously compared between young and older women using systems with fixed inertia. Individuals may have been obliged to use a percentage of their maximum strength that is not ideal for performing the movement at the optimum speed for maximum power output. This study was designed to compare explosive power output and its two determinants, optimal force and optimal speed, during a leg-press action between young and older women after optimising the load for maximum power production. The experiments were carried out on 20 women in good physical condition: 10 older, aged between 65 and 74 years and 10 young, aged between 18 and 30. Explosive power output was measured by setting the initial load at different percentages of maximum isometric strength and measuring the corresponding speed of movement during a leg-press action of the dominant leg. Maximum peak power, which was obtained at 60% of maximum isometric strength in both young and older women, was 61% lower in the older women ( P<0.0001). This was due to a 52% lower optimal force ( P<0.0001) and 21% lower optimal speed ( P<0.01). The ratio of peak power to maximum isometric strength was 22.1% lower in the older women ( P<0.01). After optimising the load, both lower speed of movement and lower strength determine the lower levels of power in older women. Power is more affected by ageing than isometric strength.

Adolescent↗

PubMed2004

Power output of the lower limb during variable inertial loading: a comparison between methods using single and repeated contractions.

The power-inertial load relationship of the lower limb muscles was studied during a single leg thrust using the Modified Nottingham Power Rig (mNPR) and during cycling exercise in nine young male subjects. The relationship between peak power and inertial load showed a parabolic-like relationship for mNPR exertions, with a peak [937 (SD 246) W] at 0.158 kg m(2), this being significantly (P <0.05) different from the power generated at both the lowest [723 (162) W] and highest [756 (206) W] inertial loads. In contrast, for cycling exercise power output did not differ significantly between inertial loads, except at the lowest inertia where power output was significantly ( P<0.05) less compared with all other inertial loads. Maximum peak power output during cycling was 1,620 (336) W, which was significantly (P <0.05) greater than that recorded on the mNPR. However, a close association was observed between the mean power generated by each method (r=0.84, P<0.05). The results suggest that during a single contraction a range of inertial loads is required to allow peak power to be expressed. Above a certain critical value, this is unnecessary during cycling movements where the load can be repeatedly accelerated.

Adaptation, Physiological↗

PubMed2006

Optimal power-to-mass ratios when predicting flat and hill-climbing time-trial cycling.

The purpose of this article was to establish whether previously reported oxygen-to-mass ratios, used to predict flat and hill-climbing cycling performance, extend to similar power-to-mass ratios incorporating other, often quick and convenient measures of power output recorded in the laboratory [maximum aerobic power (W(MAP)), power output at ventilatory threshold (W(VT)) and average power output (W(AVG)) maintained during a 1 h performance test]. A proportional allometric model was used to predict the optimal power-to-mass ratios associated with cycling speeds during flat and hill-climbing cycling. The optimal models predicting flat time-trial cycling speeds were found to be (W(MAP)m(-0.48))(0.54), (W(VT)m(-0.48))(0.46) and (W(AVG)m(-0.34))(0.58) that explained 69.3, 59.1 and 96.3% of the variance in cycling speeds, respectively. Cross-validation results suggest that, in conjunction with body mass, W(MAP) can provide an accurate and independent prediction of time-trial cycling, explaining 94.6% of the variance in cycling speeds with the standard deviation about the regression line, s=0.686 km h(-1). Based on these models, there is evidence to support that previously reported VO2-to-mass ratios associated with flat cycling speed extend to other laboratory-recorded measures of power output (i.e. Wm(-0.32)). However, the power-function exponents (0.54, 0.46 and 0.58) would appear to conflict with the assumption that the cyclists' speeds should be proportional to the cube root (0.33) of power demand/expended, a finding that could be explained by other confounding variables such as bicycle geometry, tractional resistance and/or the presence of a tailwind. The models predicting 6 and 12% hill-climbing cycling speeds were found to be proportional to (W(MAP)m(-0.91))(0.66), revealing a mass exponent, 0.91, that also supports previous research.

Adult↗

PubMed2006

Strength, power output and symmetry of leg muscles: effect of age and history of falling.

Risk factors for medically unexplained falls may include reduced muscle power, strength and asymmetry in the lower limbs. Conflicting reports exist about strength and there is little information about power and symmetry. Forty-four healthy young people (29.3 +/- 0.6 years), 44 older non-fallers (75.9 +/- 0.6 years), and 34 older fallers (76.4 +/- 0.8 years) were studied. Isometric, concentric and eccentric strength of the knee and ankle muscles and leg extension power were measured bilaterally. The younger group was stronger in all muscles and types of contraction than both older groups (P < 0.02-0.0001). Strength differences between the older groups occasionally reached significance in individual muscles and types of contraction but overall the fallers had 85% of the strength and 79% of the power of the non-fallers (P < 0.001). Young subjects generated more power than both older groups (P < 0.0001) and the fallers generated less than the non-fallers (P = 0.03). Strength symmetry showed an inconsistent age effect in some muscles and some contraction types. This was similar overall in the two older groups. Both older groups had greater asymmetry in power than the young (P < 0.02-0.004). Power asymmetry tended to be greater in the fallers than the non-fallers but this did not reach significance. These data do not support the suggestion that asymmetry of strength and power are associated with either increasing age or fall history. Power output showed clear differences between age groups and fall status and appears to be the most relevant measurement of fall risk and highlights the cumulative effects on function of small changes in strength in individual muscle groups.

Accidental Falls↗

PubMed2001

Imaging of power spectral heart rate variability regarding subject position.

Heart rate variability (HRV) and its assessment using power spectral analysis revealed a possibility to quantify the characteristics of autonomic nervous system, related cardiovascular status and sympathovagal interaction. This study was designed to assess vagal tone in supine and right recumbent position in normal healthy subjects as many maneuvers that potentially increase vagal tone have been sought both in normal subjects and in patients with heart disease. Seven subjects, four male and three female, aged 20-27 years were enrolled in the study. To evaluate the time-dependent stability of short term ECG recordings, every subject participated in six ECG recording sessions (three successive morning and three successive afternoon measurements). Heart rate power spectra were obtained by off-line Fast Fourier Transform analysis. The frequency domain measures, namely very low frequency power (VLF), low frequency power (LF), high frequency power (HF) and total power were determined, and their normalized correlates used in the comparison between supine and right recumbent position. Normalized high frequency (nHF) indicated cardiac vagal activity, normalized low frequency power indexed sympathetic modulated activity, low frequency power/high frequency power ratio (LF/HF) represented sympathovagal balance. The results showed remarkable variation among successive day measurements as well as among study subjects. However, several types of response to adopting right recumbent position could be identified. In the first, in right recumbent position the values of nHF, indicator of vagal activity did not differ appreciably from the values measured in supine position. Secondly, there was a tendency towards higher nHF values and lower LF/HF power ratio in supine position. We were not able to notice any appreciable difference among morning and afternoon short-term measurements. Finally, our results do not suggest higher vagal modulation when lying in right recumbent position.

Adult↗

PubMed1998

Electrogastrographic power ratio in humans is not related to changes in antrum-skin distance but to antral motility.

It is not clear whether the power increase in electrogastrography (EGG) after meal or water ingestion reflects increases in gastric motility or gastric distension bringing the stomach closer to the electrodes on the abdominal skin surface. We recorded EGG and real-time ultrasonography simultaneously before and after 150-ml water ingestion in 17 healthy volunteers. We calculated gastric power, by spectral analysis of EGG by the maximum entropy method, for 400 s before and after water ingestion, and calculated their ratio (power ratio). We calculated, using sonography, the number of antral contractions before and after water ingestion, the motility index after water ingestion, the distance between the antrum and the abdominal skin surface before and after water ingestion, and the ratio of these distances (distance ratio). The number of contractions was positively correlated with gastric power before water ingestion, and the antrum-skin distance was negatively correlated with gastric power both before and after water ingestion. The motility index after water ingestion was positively correlated with both gastric power after water ingestion (Spearman's rank correlation r = 0.492; P = 0.0498) and the power ratio (r = 0.615; P = 0.0141). There was no correlation between the distance ratio and the power ratio. These results suggest that the power increase in EGG induced by water ingestion does not reflect the approach of the antrum to the abdominal surface, but rather, reflects antral motility after water ingestion.

Adult↗

PubMed2006

Dynamics of in vivo power output and efficiency of Nasonia asynchronous flight muscle.

By simultaneously measuring aerodynamic performance, wing kinematics, and metabolic activity, we have estimated the in vivo limits of mechanical power production and efficiency of the asynchronous flight muscle (IFM) in three species of ectoparasitoid wasps genus Nasonia (N. giraulti, N. longicornis, and N. vitripennis). The 0.6 mg animals were flown under tethered flight conditions in a flight simulator that allowed modulation of power production by employing an open-loop visual stimulation technique. At maximum locomotor capacity, flight muscles of Nasonia are capable to sustain 72.2 +/- 18.3 W kg(-1) muscle mechanical power at a chemo-mechanical conversion efficiency of approximately 9.8 +/- 0.9%. Within the working range of the locomotor system, profile power requirement for flight dominates induced power requirement suggesting that the cost to overcome wing drag places the primary limit on overall flight performance. Since inertial power is only approximately 25% of the sum of induced and profile power requirements, Nasonia spp. may not benefit from elastic energy storage during wing deceleration phases. A comparison between wing size-polymorphic males revealed that wing size reduction is accompanied by a decrease in total flight muscle volume, muscle mass-specific mechanical power production, and total flight efficiency. In animals with small wings maximum total flight efficiency is below 0.5%. The aerodynamic and power estimates reported here for Nasonia are comparable to values reported previously for the fruit fly Drosophila flying under similar experimental conditions, while muscle efficiency of the tiny wasp is more at the lower end of values published for various other insects.

Animals↗

PubMed2005

An investigation of clinical studies suggests those with multiple objectives should have at least 90% power for each endpoint.

BACKGROUND AND OBJECTIVES: Many clinical studies have more than one objective, either formally or informally, but this is not usually taken into account in the determination of the sample size. We investigated the overall power of a study, that is, the probability that all the objectives will be met. METHODS: We calculated the overall power in the case that the study has two primary outcome variables and in the case that one outcome variable is evaluated on two subsets, in particular, the Per Protocol group and the Intention to Treat group. RESULTS: A power of 80% for each of the two end points leads to poor power for the end points combined. However, a power of 90% preserves better the overall power. The power of the Per Protocol analysis can be higher or lower than the power of the Intention to Treat analysis. CONCLUSION: Power should be calculated for all end points combined, and it should be at least 90% for each primary end point. If the sample size for the intention-to-treat analysis is determined by adding a percentage of "nonevaluable subjects" to the sample size required for the per protocol analysis, then this may lead to an underpowered study.

Analysis of Variance↗

PubMed2006

Simple regression formula for intraocular lens power adjustment in eyes requiring cataract surgery after excimer laser photoablation.

PURPOSE: To develop a simple and accurate method for determining appropriate intraocular lens (IOL) power in cataract patients who had prior excimer laser photoablation for myopia or hyperopia, because laser vision corrective surgery interferes with traditional keratometry and corneal topography, rendering IOL power calculations inaccurate. SETTING: Private Practice in Century City (Los Angeles), California, and free-standing outpatient surgery centers with institutional review boards. METHODS: Based on the empiric experience of the senior author, an IOL power correction factor that was proportional to the prior laser photoablation was determined and applied to the IOL power calculated by the IOLMaster (Zeiss). It was necessary to add to the predicted IOL power in eyes with prior myopic laser ablation, whereas eyes having prior hyperopic laser vision correction required a reduction in the IOL power. The correction factor was applied to 30 eyes that required cataract surgery at some time after laser refractive surgery; 23 eyes had prior treatment for myopia, and the remaining 7 eyes had prior hyperopic laser ablation. A regression formula was generated from the IOL power correction factor that was used in the 30 eyes. RESULTS: Using the correction factor for 30 eyes, the mean deviation from the desired postcataract refractive outcome was -0.15 diopter (D) +/- 0.29 (SD); 28 of 30 eyes were within +/-0.5 D of the intended goal; the remaining 2 eyes were both -0.75 D from the desired optical result of cataract surgery. Fourteen of the 30 eyes were emmetropic. CONCLUSIONS: A simple IOL power corrective adjustment regression formula allowed accurate determination of IOL power after laser refractive photoablation surgery. The weakness of the current method is that knowledge of the amount of prior laser vision correction is necessary.

Algorithms↗

PubMed2004

The effectiveness of manual versus powered toothbrushes for dental health: a systematic review.

OBJECTIVES: To compare manual and powered toothbrushes in everyday use, principally in relation to plaque removal and gingival health. Stain, calculus removal, dependability, adverse effects and cost were also considered. METHOD: A systematic review was undertaken in collaboration with the Cochrane Oral Health Group. Five electronic databases were searched to identify randomised controlled trials comparing powered and manual toothbrushes. Trials of less than 28 days duration, or where toothbrushing was supervised, were excluded. Assessment of relevance, data extraction and validity assessment were all undertaken independently and in duplicate by two reviewers. Included studies were grouped according to the mode of action of the powered toothbrush. The primary outcomes were plaque and gingival health with data defined as either short-term (1-3 months) or long-term (greater than 3 months) duration were analysed. Powered brushes were categorised into six groups depending on mode of action. Numerical data extracted were checked by a third reviewer for accuracy and entered into RevMan (version 4.1). RESULTS: The initial search identified 354 studies. Two hundred and fifteen full articles were obtained of which 29 trials fulfilled the inclusion criteria with results, which could be entered in the meta-analysis. Twenty-six trials (1786 participants) reported short-term and 10 trials (798 participants) long-term plaque scores. Twenty-nine trials (2236 participants) reported short-term and 10 trials (798 participants) long-term gingivitis scores. Powered brushes reduced plaque and gingivitis at least as effectively as manual brushing. Rotation oscillation powered brushes statistically significantly reduced plaque and gingivitis in both the short and long-term. For plaque at one to 3 months the standardised mean difference was -0.44 (95% CI: -0.66 to -0.21), for gingivitis SMD -0.45 (95% CI: -0.76, -0.15). These represented an 11% reduction on the Quigley Hein Plaque index and a 6% reduction on the Löe and Silness gingival index. At over 3 months the effects were SMD for plaque -1.15 (95% CI: -2.02, -0.29) and SMD for gingivitis -0.51 (95% CI: -0.76, -0.25). These represented a 7% reduction on the Quigley Hein Plaque Index and a 17% reduction on the Ainamo Bay Bleeding on Probing Gingival Index. Sensitivity analyses revealed the results to be robust when selecting trials of high quality. There was no evidence of any publication bias. No other powered brush designs were consistently superior to manual toothbrushes. In these trials, data on cost, reliability and side effects were inconsistently reported. CONCLUSION: In general there was no evidence of a statistically significant difference between powered and manual brushes. However, rotation oscillation powered brushes significantly reduce plaque and gingivitis in both the short and long-term. The clinical significance of this reduction is not known. Observation of methodological guidelines and greater standardisation of design would benefit both future trials and meta-analyses.

Dental Devices, Home Care↗