Research
Independent research on chewing and oral function.
Published studies, read at the source. What each one measured, what it found, including no link and mixed results, and the limits of each. None of these studies tested MYODYN.
Independent research on mastication.
How to read this
- Trial or observation
- A randomised trial assigns people to groups and compares them. An observational study measures people as they are. It can show an association, not a cause.
- Ratios
- Relative risk and hazard ratio compare two groups. 1.0 means no difference. 1.48 means the measured risk in the first group was 1.48 times that of the comparison group. A hazard ratio is read the same way, over time.
- The bracket
- The 95% confidence interval. If it crosses 1.0, the result is not statistically significant. Those rows are drawn with a hollow dot and a dashed line, and say so in words.
- Association is not causation
- A link in a population study does not show that one thing causes the other. People with early cognitive change may look after their teeth less, which produces the same link in reverse.
- Numbers
- Copied from each source, not rounded, and with no figures of our own added. Each figure says whether it shows medians, means or ratios.
Dental and oral function
Bite force, occlusal support, masticatory performance and chewing exercises, mostly in older adults.
Figures
Fig. 1 Cross-sectional population study, n = 1,962, Japan, 2018
In a Japanese population study, people aged 80 recorded lower average bite force and had fewer teeth than people aged 70.
Show the numbers as a table
| Age group | Mean occlusal force (N) | Mean number of teeth |
|---|---|---|
| 70 years, n = 994 | 529 | 20.4 |
| 80 years, n = 968 | 326 | 15.4 |
Limitation Different people at each age, measured once. Not the same people followed over time.
Source Ikebe et al. 2018, PLoS One, Table 2
Independent research on mastication.
Fig. 2 Randomised controlled trial, n = 211 completers (107 gum, 104 control), adults aged 65 to 85, Japan, 2023
In a 2-month trial in adults aged 65 to 85, the group that chewed a firm training gum daily recorded higher median bite force than a control group.
Between groups at 2 months: p = 0.013.
Show the numbers as a table
| Group | Baseline | 2 months |
|---|---|---|
| Firm training gum, n = 107 | 457.8 (IQR 442.1) | 663.8 (IQR 509.1) |
| Control, n = 104 | 512.1 (IQR 447.8) | 507.0 (IQR 411.3) |
| Between groups | p = 0.25 | p = 0.013 |
Limitation Funded by a chewing gum manufacturer. Medians with wide spread (interquartile ranges 442.1 and 509.1 N in the gum group, 447.8 and 411.3 N in the control group). One measuring device.
Source Kashiwazaki et al. 2023, J Clin Med, Table 2
Independent research on mastication.
Study library
-
Kashiwazaki K, Komagamine Y, Shanglin W, et al. J Clin Med. 2023;12(20):6534.
Improvements in Maximum Bite Force with Gum-Chewing Training in Older Adults: A Randomized Controlled Trial
- Design
- Double-blind randomised controlled trial, 2 months
- People
- 211 completers (218 randomised), aged 65 to 85, Japan
The group given one piece of firm training gum (hardness 7.1 N), chewed in three sets a day, had a median maximum bite force of 457.8 N at baseline and 663.8 N at 2 months. The control group, given a daily granular food, had 512.1 N and 507.0 N. The groups differed at 2 months (p = 0.013). Tongue pressure and the other oral measures did not differ between the groups. Shown in Fig. 2.
Limits Funded by a chewing gum manufacturer. Adherence recorded by diary. Medians with wide spread. Oral function was not below reference values at the start. Checked against: abstract and full text.
Read it on PubMed Central: Improvements in Maximum Bite Force with Gum-Chewing Training in Older Adults: A Randomized Controlled Trial -
Kashiwazaki K, Komagamine Y, Uehara Y, et al. J Dent Sci. 2024;19(2):1021-1027.
Effect of gum-chewing exercise on maintaining and improving oral function in older adults: A pilot randomized controlled trial
Bite force: no difference between groups
- Design
- Single-blind pilot randomised controlled trial, 1 month, gum vs tablets
- People
- 130 older adults
At 1 month, tongue pressure was higher in the gum group than in the control group (P = 0.027). Maximum bite force rose within the gum group (P < 0.001) but did not differ between the groups. The authors note that additional increases in masticatory load may be necessary.
Limits Pilot study over 1 month, with a softer gum (2.7 N) than the 2023 trial. Checked against: abstract.
Read it on PubMed: Effect of gum-chewing exercise on maintaining and improving oral function in older adults: A pilot randomized controlled trial -
Li X, Zhang J, Liu Y, Yang C, Tan L, Yang Y. J Prosthet Dent. 2025;134(6):2193.e1-2193.e10.
Impact of masticatory training on masticatory function: A systematic review and meta-analysis
- Design
- Systematic review and meta-analysis
- People
- 9 studies: healthy adults, people with cognitive impairment, oral frailty, or after orthognathic surgery
In the pooled analysis, chewing exercises with gum improved tongue pressure (SMD = 2.04, 95% CI 0.63 to 3.45). The pooled result is for tongue pressure, not bite force. The authors found exercises with gum and hard foods unsuitable for edentulous people.
Limits Only 9 studies, of different kinds, and a wide interval. Checked against: abstract.
Read it on PubMed: Impact of masticatory training on masticatory function: A systematic review and meta-analysis -
Tanaka T, Takahashi K, Hirano H, et al. J Gerontol A Biol Sci Med Sci. 2018;73(12):1661-1667.
Oral Frailty as a Risk Factor for Physical Frailty and Mortality in Community-Dwelling Elderly
- Design
- Prospective cohort, 2012 to 2016
- People
- 2,011 people aged 65 and over, Japan
Oral frailty here meant poor status in 3 or more of six measures, including number of natural teeth, chewing ability and tongue pressure. 16% of participants had it at baseline. It was associated with 2.4-, 2.2-, 2.3- and 2.2-fold higher risk of physical frailty, sarcopenia, disability and mortality.
Limits Observational. Confidence intervals not checked, as the full text was not accessible. One cohort. Checked against: abstract.
Read it on PubMed: Oral Frailty as a Risk Factor for Physical Frailty and Mortality in Community-Dwelling Elderly -
Hatta K, Murotani Y, Takahashi T, et al. J Am Geriatr Soc. 2022;70(2):541-548.
Decline of oral functions in old-old adults and their relationship with age and sex: The SONIC study
No significant change over 3 years
- Design
- Longitudinal cohort, 3-year follow-up
- People
- 951 people in the 70 (466), 80 (391) and 90 (94) year age groups, Japan
Occlusal force was lower in the 80-year group (B = −81.7) and the 90-year group (B = −87.2) than in the 70-year group, lower in women (B = −66.9), and higher with more teeth (B = 13.8). It did not significantly decrease over the 3 years. The authors write: "Tongue-related muscles may be more susceptible to aging than masticatory muscles."
Limits Abstract only; the units of the coefficients are not stated there. Checked against: abstract.
Read it on PubMed: Decline of oral functions in old-old adults and their relationship with age and sex: The SONIC study -
Ikebe K, Gondo Y, Kamide K, et al. PLoS One. 2018;13(1):e0190741.
Occlusal force is correlated with cognitive function directly as well as indirectly via food intake in community-dwelling older Japanese: From the SONIC study
- Design
- Cross-sectional population study
- People
- 994 people aged 70 and 968 aged 80, Japan
Mean occlusal force was 529 N in the 70-year group, with 20.4 teeth on average, and 326 N in the 80-year group, with 15.4 teeth. The cognitive finding from the same paper is listed under Cognition. Shown in Fig. 1.
Limits Two different age groups, measured once. Means only. Checked against: abstract and full text.
Read it on PubMed Central: Occlusal force is correlated with cognitive function directly as well as indirectly via food intake in community-dwelling older Japanese: From the SONIC study -
Higashi K, Hatta K, Mameno T, et al. J Dent. 2023;139:104763.
The relationship between changes in occlusal support and masticatory performance using 6-year longitudinal data from the SONIC study
- Design
- Longitudinal cohort, median follow-up 5.92 years
- People
- 488 of 864 participants aged 72 to 74
The decline in masticatory performance was strongest in people whose occlusal support changed from complete or reduced to collapsed. The authors conclude that loss of occlusal support is a major factor in declining masticatory performance.
Limits No headline effect size in the abstract. 488 of 864 completed follow-up. Checked against: abstract.
Read it on PubMed: The relationship between changes in occlusal support and masticatory performance using 6-year longitudinal data from the SONIC study -
Ikebe K, Matsuda K, Murai S, Maeda Y, Nokubi T. Int J Prosthodont. 2010;23(6):521-524.
Validation of the Eichner index in relation to occlusal force and masticatory performance
- Design
- Cross-sectional study
- People
- 1,288 independently living people over 60
Occlusal force fell as occlusal contacts were lost. Masticatory performance also fell, more gradually. Premolar contacts on both sides mattered most for occlusal force, and on one side for masticatory performance.
Limits No numeric effect sizes in the abstract. Checked against: abstract.
Read it on PubMed: Validation of the Eichner index in relation to occlusal force and masticatory performance -
Iinuma T, Arai Y, Fukumoto M, et al. J Am Geriatr Soc. 2012;60(1):68-76.
Maximum occlusal force and physical performance in the oldest old: the Tokyo oldest old survey on total health
- Design
- Cross-sectional study
- People
- 489 people aged 85 to 102, Japan
Lower maximum occlusal force was associated with poor performance on the timed up and go test, in men (OR = 2.34, 95% CI 1.02 to 5.38) and in women (OR = 2.44, 95% CI 1.12 to 5.33).
Limits Cross-sectional, wide intervals, oldest old only. Checked against: abstract.
Read it on PubMed: Maximum occlusal force and physical performance in the oldest old: the Tokyo oldest old survey on total health -
Alpoz E, Daylan A, Kayhan Koçak FO, et al. BMC Geriatr. 2025;26(1):15.
Associations between ultrasonographic masseter muscle thickness, sarcopenia and Eichner index in geriatric outpatients: a case control study
Mixed result
- Design
- Case-control study
- People
- 46 outpatients, median age 73
Masseter thickness was lower in people with high SARC-F scores (p = 0.041) but similar across the probable sarcopenia, sarcopenia and non-sarcopenic groups (p > 0.05).
Limits Very small sample. Checked against: abstract.
Read it on PubMed: Associations between ultrasonographic masseter muscle thickness, sarcopenia and Eichner index in geriatric outpatients: a case control study
Independent research on mastication.
Wider research
The studies below look at teeth, chewing and other areas of health in groups of people. They describe associations or short laboratory effects. They do not show that chewing gum changes any of these outcomes.
Cognition
Teeth and later cognition in large populations, laboratory studies of chewing gum and attention, then animal and mechanism studies of how jaw muscles and nerves connect to the brain.
Figures
Fig. 3 Meta-analysis of 14 longitudinal studies, n = 34,074, GRADE moderate, 2021
In pooled long-term studies, people with more tooth loss had a higher measured risk of cognitive impairment and dementia.
Right of 1.0: the outcome was recorded more often in the group with more tooth loss.
Show the numbers as a table
| Comparison | Outcome | Relative risk (95% CI) | Studies, n |
|---|---|---|---|
| More tooth loss vs less | Cognitive impairment | 1.48 (1.18 to 1.87) | 6 studies, n = 17,310 |
| More tooth loss vs less | Dementia | 1.28 (1.09 to 1.49) | 9 studies, n = 27,904 |
| Edentulous | Cognitive impairment | 1.54 (1.34 to 1.78) | not stated |
| Edentulous | Dementia | 1.40 (1.10 to 1.80) | not stated |
Limitation Observational association. It does not show causation.
Source Qi et al. 2021, J Am Med Dir Assoc
Independent research on mastication.
Fig. 4 Prospective cohort, n = 4,425, Japan, 4 years, 2012
In a 4-year Japanese cohort, few teeth without dentures and having no regular dentist were linked with later dementia onset; self-reported chewing ability was not.
Hollow dot and dashed line: not statistically significant (the interval crosses 1.0).
Show the numbers as a table
| Self-reported dental status | Hazard ratio (95% CI) | Significant |
|---|---|---|
| Few teeth and no dentures | 1.85 (1.04 to 3.31) | Yes |
| Could not chew very well | 1.25 (0.81 to 1.93) | No |
| No regular dentist | 1.44 (1.04 to 2.01) | Yes |
| Did not take care of dental health | 1.76 (0.96 to 3.20) | No |
Limitation Self-reported dental status. Short follow-up.
Source Yamamoto et al. 2012, Psychosom Med
Independent research on mastication.
Study library: teeth, chewing and later cognition
-
Qi X, Zhu Z, Plassman BL, Wu B. J Am Med Dir Assoc. 2021;22(10):2039-2045.
Dose-Response Meta-Analysis on Tooth Loss With the Risk of Cognitive Impairment and Dementia
- Design
- Systematic review and dose-response meta-analysis of longitudinal studies, GRADE moderate
- People
- 14 studies, 34,074 participants, 4,689 cases
More tooth loss: relative risk 1.48 (95% CI 1.18 to 1.87) for cognitive impairment and 1.28 (1.09 to 1.49) for dementia. Edentulous: 1.54 (1.34 to 1.78) and 1.40 (1.10 to 1.80). Each additional tooth lost was associated with a 0.014 higher relative risk of cognitive impairment and 0.011 of dementia. Shown in Fig. 3.
Limits Observational. Tooth loss was measured differently across studies. The paper's denture estimate is printed inconsistently, so it is not shown. Checked against: abstract and full text.
Read it on PubMed Central: Dose-Response Meta-Analysis on Tooth Loss With the Risk of Cognitive Impairment and Dementia -
Chen H, Ji L, Wang Y, Klineberg I, Chen H. J Oral Rehabil. 2026;53(4):924-938.
Dentition-Cognition Relationship in Aging Populations: A Meta-Analysis of Longitudinal Data
- Design
- Meta-analysis of 21 longitudinal studies
- People
- 35 744 989 participants as printed, mostly registry data
Tooth loss was associated with dementia (OR = 1.26, 1.07 to 1.49) and mild cognitive impairment (OR = 1.40, 1.14 to 1.71). Edentulism: dementia OR = 1.16 (1.09 to 1.23), mild cognitive impairment OR = 1.90 (1.07 to 3.35). In people with tooth loss who used dentures, the dementia estimate was OR = 1.03 (0.82 to 1.28).
Limits Observational. The dementia estimate for edentulism is lower than for any tooth loss, which the abstract does not explain. The authors' causal wording is not supported by the design. Checked against: abstract.
Read it on PubMed: Dentition-Cognition Relationship in Aging Populations: A Meta-Analysis of Longitudinal Data -
Yamamoto T, Kondo K, Hirai H, Nakade M, Aida J, Hirata Y. Psychosom Med. 2012;74(3):241-248.
Association between self-reported dental health status and onset of dementia: a 4-year prospective cohort study of older Japanese adults from the AGES Project
Chewing ability: no significant link
- Design
- Prospective cohort, 2003 to 2007
- People
- 4,425 people aged 65 and over, 220 dementia onsets, Japan
Adjusted hazard ratios for dementia onset: few teeth and no dentures 1.85 (1.04 to 3.31); could not chew very well 1.25 (0.81 to 1.93), not significant; no regular dentist 1.44 (1.04 to 2.01); did not take care of dental health 1.76 (0.96 to 3.20), not significant. Self-reported chewing ability was not significantly associated. Shown in Fig. 4.
Limits Self-reported. A 4-year follow-up allows reverse causation. Checked against: abstract.
Read it on PubMed: Association between self-reported dental health status and onset of dementia: a 4-year prospective cohort study of older Japanese adults from the AGES Project -
Dintica CS, Marseglia A, Wårdh I, et al. Aging (Albany NY). 2020;12(9):8536-8548.
The relation of poor mastication with cognition and dementia risk: a population-based longitudinal study
Dementia: no significant link
- Design
- Population-based cohort, up to 22 years
- People
- 544 cognitively intact people aged 50 and over, 52 dementia cases, Sweden
Fewer occlusal contacts (Eichner categories B and C) were linked with faster decline in spatial and fluid abilities (β = −0.16, 95% CI −0.30 to −0.03; β = −0.15, −0.28 to −0.02) but not with dementia risk (HR 0.83, 0.39 to 1.76; HR 0.63, 0.30 to 1.29).
Limits Few dementia cases. Checked against: abstract.
Read it on PubMed: The relation of poor mastication with cognition and dementia risk: a population-based longitudinal study -
Ikebe K, Gondo Y, Kamide K, et al. PLoS One. 2018;13(1):e0190741.
Occlusal force is correlated with cognitive function directly as well as indirectly via food intake in community-dwelling older Japanese: From the SONIC study
- Design
- Cross-sectional population study
- People
- 994 people aged 70 and 968 aged 80, Japan
After adjusting for other factors, occlusal force remained associated with the MoCA-J cognitive test score (Beta = 0.125, p < 0.001).
Limits Cross-sectional. The authors write that it is difficult to identify any causal relationships. Checked against: abstract and full text.
Read it on PubMed Central: Occlusal force is correlated with cognitive function directly as well as indirectly via food intake in community-dwelling older Japanese: From the SONIC study
Study library: chewing gum and attention
Results are mixed. Some studies found a small or short-lived benefit, some found none, and some found performance was worse with gum.
-
Sta Maria MT, Hasegawa Y, Khaing AMM, Salazar S, Ono T. Jpn Dent Sci Rev. 2023;59:375-388.
The relationships between mastication and cognitive function: A systematic review and meta-analysis
Slower with gum
- Design
- Systematic review with small meta-analyses
- People
- 20 studies
In young adults, gum chewing reduced the processing speed of cognitive tasks compared with no gum. The authors note that most of the evidence had a low level of evidence and a high risk of bias.
Limits Some printed intervals in the paper are internally inconsistent, so its pooled numbers are not reproduced here. Checked against: abstract and full text.
Read it on PubMed Central: The relationships between mastication and cognitive function: A systematic review and meta-analysis -
Miquel S, Haddou MB, Day JEL. Physiol Behav. 2019;202:101-115.
A systematic review and meta-analysis of the effects of mastication on sustained attention in healthy adults
Weak effect
- Design
- Systematic review and meta-analysis
- People
- 21 papers, healthy adults
A weak but statistically significant improvement in sustained attention when chewing (Cohen's d = −0.1479, 95% CI −0.2913 to −0.0045, p = 0.043). The result for alertness was not significant (p = 0.052).
Limits Lead author affiliated with a chewing gum manufacturer. Healthy adults only. Checked against: abstract.
Read it on PubMed: A systematic review and meta-analysis of the effects of mastication on sustained attention in healthy adults -
Onyper SV, Carr TL, Farrar JS, Floyd BR. Appetite. 2011;57(2):321-328.
Cognitive advantages of chewing gum. Now you see them, now you don't.
Mixed result
- Design
- Series of experiments
- People
- Healthy participants; n not given in the abstract
Gum chewed for 5 minutes before testing, but not during it, was associated with better performance on several measures. The benefit lasted only the first 15 to 20 minutes and did not extend to every area tested.
Limits Short laboratory tasks. Checked against: abstract.
Read it on PubMed: Cognitive advantages of chewing gum. Now you see them, now you don't. -
Tucha O, Mecklinger L, Maier K, Hammerl M, Lange KW. Appetite. 2004;42(3):327-329.
Chewing gum differentially affects aspects of attention in healthy subjects
Mixed result
- Design
- Within-subject experiment, randomised order
- People
- Healthy adults; n not given in the abstract
Chewing gum did not improve memory. Sustained attention improved, while alertness and flexibility were worse with gum. The authors advise caution about claims that gum improves cognition.
Limits Short report, small sample. Checked against: abstract.
Read it on PubMed: Chewing gum differentially affects aspects of attention in healthy subjects -
Kozlov MD, Hughes RW, Jones DM. Q J Exp Psychol (Hove). 2012;65(3):501-513.
Gummed-up memory: chewing gum impairs short-term recall
Worse with gum
- Design
- Three laboratory experiments
- People
- Healthy adults; n not given in the abstract
Chewing gum impaired short-term memory for both the order and the identity of items. Manual tapping produced a similar pattern.
Limits Laboratory recall tasks only. Checked against: abstract.
Read it on PubMed: Gummed-up memory: chewing gum impairs short-term recall -
Morgan K, Johnson AJ, Miles C. Br J Psychol. 2014;105(2):214-225.
Chewing gum moderates the vigilance decrement
- Design
- Between-groups experiment, 30-minute listening task
- People
- 40 adults
Correct responses were faster with gum in the later stages of the task. The authors report that their data contradict the 2012 Kozlov finding.
Limits 40 people, one task. Checked against: abstract.
Read it on PubMed: Chewing gum moderates the vigilance decrement -
Tucha L, Simpson W. Appetite. 2011;56(2):299-301.
The role of time on task performance in modifying the effects of gum chewing on attention
Mixed result
- Design
- Crossover experiment, 30 minutes
- People
- Healthy adults; n not given in the abstract
Gum chewing worsened sustained attention early in the task and improved it later. This study tested healthy adults, not people with ADHD.
Limits Short report. Checked against: abstract.
Read it on PubMed: The role of time on task performance in modifying the effects of gum chewing on attention
Study library: jaw muscles, nerves and the brain
Early mechanism work in animals and a small human experiment. These explore how jaw input might reach the brain. Neither tested chewing gum.
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Kobayashi T, Nagai M, Da Silva JD, et al. Neurosci Lett. 2019;698:180-185.
Retrograde transport of masseter muscle-derived neprilysin to hippocampus
Mice and cells: no people, no chewing
- Design
- Laboratory study of mouse tissue and cultured muscle cells
- People
- None. Mice and a mouse muscle cell line (C2C12)
The masseter muscle made substantial neprilysin, an enzyme that breaks down amyloid-beta, a protein linked to Alzheimer's disease. The trigeminal nerve and the hippocampus held neprilysin protein without making it themselves. When the masseter was contracted by electrical stimulation in freshly euthanised mice, muscle neprilysin fell while nerve and then hippocampal neprilysin rose. Labelled exosomes (small vesicles) followed the same route. The authors conclude that masseter-derived neprilysin travels along the trigeminal nerve to the hippocampus.
Limits Animal and cell work. The muscle was stimulated electrically, not by chewing or gum. No behaviour or cognitive outcome was measured, and no amyloid-beta change was shown in a living animal. It does not show that chewing affects memory or dementia in people. Checked against: abstract.
Read it on PubMed: Retrograde transport of masseter muscle-derived neprilysin to hippocampus -
Tramonti Fantozzi MP, Lazzarini G, De Cicco V, et al. Sci Rep. 2021;11(1):4744.
The path from trigeminal asymmetry to cognitive impairment: a behavioral and molecular study
Jaw bite splint and rat nerve lesion: no gum
- Design
- A human experiment with a custom bite splint, and a rat study of two ways of making the bite uneven
- People
- 20 adults (aged 20 to 54) with uneven masseter activity when clenching, picked from 30 screened. Twenty male rats, aged 15 to 20 months, in groups of five
In the 20 adults, wearing a splint that evened out the bite reduced the left-right difference in masseter activity (from 54.1 to 6.3 microvolts) and changed pupil size, which the authors use as a proxy for locus coeruleus activity. The authors report improved performance on a number-search task, and that a smaller resting pupil on the more active side predicted a larger improvement. In rats, cutting the lower-jaw branch of the trigeminal nerve on one side lowered c-Fos in the brainstem and BDNF in the brainstem, hippocampus and frontal cortex on the other side. Grinding the molars unevenly did not change gene expression.
Limits Small. Each person was compared with themselves, splint on versus off, after two weeks of wearing it; no separate control group is described. Pupil size is an indirect proxy, and the authors note their brainstem sample was too coarse to pin the changes to the locus coeruleus. Five rats per group. The task measures number search, not memory or dementia. Nobody chewed gum. Checked against: abstract and full text.
Read it in Scientific Reports: The path from trigeminal asymmetry to cognitive impairment: a behavioral and molecular study
Independent research on mastication.
Parkinson's
Small case-control studies describing chewing and oral function in Parkinson's, for clinicians.
Study library
-
Bakke M, Larsen SL, Lautrup C, Karlsborg M. Eur J Oral Sci. 2011;119(1):27-32.
Orofacial function and oral health in patients with Parkinson's disease
- Design
- Case-control study
- People
- 15 people with Parkinson's (Hoehn and Yahr stage 2 to 4) and 15 matched controls
Orofacial dysfunction was more common, chewing and mouth opening were poorer, and oral health had a more negative effect on daily life in the Parkinson's group than in controls.
Limits 15 per group. No numbers in the abstract. Checked against: abstract.
Read it on PubMed: Orofacial function and oral health in patients with Parkinson's disease -
Baram S, Thomsen CE, Øzhayat EB, Karlsborg M, Bakke M. BMC Oral Health. 2023;23(1):381.
Orofacial function and temporomandibular disorders in Parkinson's Disease: a case-controlled study
- Design
- Case-control study
- People
- 20 people with Parkinson's and 20 matched controls
60% of the Parkinson's group found it difficult to eat foods of certain consistencies, against 0% of controls. A dry mouth feeling was reported by 58% and 20%.
Limits 20 per group; partly self-reported. Checked against: abstract.
Read it on PubMed: Orofacial function and temporomandibular disorders in Parkinson's Disease: a case-controlled study -
Baram S, Thomsen CE, Øzhayat EB, Karlsborg M, Bakke M. J Oral Rehabil. 2025;52(10):1829-1838.
Maximum Muscle Output and Electromyographic Activity of Masticatory Muscles in Persons With Parkinson's Disease. A Case-Control Study
Bite force: no significant difference
- Design
- Case-control study
- People
- n = 40: 20 with Parkinson's (median age 68.5) and 20 controls (median age 67), Denmark
While chewing, the Parkinson's group used 82% of their maximal masseter contraction, against 49% in controls (p = 0.02). Bite force did not differ significantly: median 316 N against 353 N (p = 0.17).
Limits Small sample and cross-sectional. The investigator was not blinded. Checked against: abstract and full text.
Read it on PubMed Central: Maximum Muscle Output and Electromyographic Activity of Masticatory Muscles in Persons With Parkinson's Disease. A Case-Control Study
Independent research on mastication.
ADHD and autism
A note for special-care dentistry.
Research in special-care dentistry has described oral sensory sensitivities in some autistic children, and studies of chewing and attention, including in ADHD, have produced mixed results.
- Tucha L, Simpson W, Evans L, et al. Appetite. 2010;55(3):679-684.Detrimental effects of gum chewing on vigilance in children with attention deficit hyperactivity disorderRead it on PubMed: Detrimental effects of gum chewing on vigilance in children with attention deficit hyperactivity disorder
- Stein LI, Polido JC, Mailloux Z, Coleman GG, Cermak SA. Spec Care Dentist. 2011;31(3):102-110.Oral care and sensory sensitivities in children with autism spectrum disordersRead it on PubMed: Oral care and sensory sensitivities in children with autism spectrum disorders
- Stein LI, Polido JC, Cermak SA. Pediatr Dent. 2013;35(3):230-235.Oral care and sensory over-responsivity in children with autism spectrum disordersRead it on PubMed: Oral care and sensory over-responsivity in children with autism spectrum disorders
Independent research on mastication.