The role of oral sensorimotor function in masticatory ability

Evaluation of masticatory efficiency and OHRQoL in implant-retained overdenture with different numbers of implant in the edentulous mandible: a one-year follow-up prospective study

PURPOSE

The aim of this article is to evaluate to the masticatory function performance and Oral Health-related Quality of Life (OHRQoL) in implant-retained overdenture compared with different implant number placements in the edentulous mandible.

METHODS

From 2013 to 2015, each patients received 3 implants (iSy-Implant, Camlog, Wimsheim, Germany) in intraforaminal mandible (34, 41/31, 44). After operation, inserted implants were gradually loaded and incorporated into an overdenture with a self-aligning attachment system (Locator abutments) in 3 + 3 + 3 months. Five checked points were performed chewing cycle test with multicolored chewing gum and OHIP-G14 questionnaire and a sum score questionnaire as following: pre-operation, one implant load (41/31), two implants loaded (33,43), three implants loaded and 1-year follow up.

RESULT

A total of 10 patients with 30 implants were placed, the survival rate of the implants was 100% within 1-year follow-up. Regarding the masticatory function analysis, for the higher number of chewing cycles, the higher mixing rate was observed. After 1 year, the inter-mixing rate without significant changes was found compared to the time after three implants were loaded with attachment system. The mean value of OHIP-G14 was 30.4 preoperatively, 21.1 after loading the first locator, 10.7 after loading two locator abutments, and 3.2 after loading all three locator abutments. After 1 year, OHIP-G14 was 2.6 without significantly changed. The mean of the sum score was 15.5 preoperatively, 27.8 after activation of the first locator, 39.4 after activation of two locators, 46.2 after activation of all three locators, and 47.3 after 1 year. An increase of 0.7 sum score units per time point was observed. No significance was detectable, analogous to OHIP-G14, compared to the time of activation of all three locator setups (p-value = 0.22).

CONCLUSIONS

A significant improvement in masticatory function performance and OHRQoL was evaluated with the increasing number of implants with locator attachment in edentulous mandible. With the investigation of the OHIP-G14 and sum score, the results of patient report outcome might be associated with the increase in the number of implants.

Effects of tongue lesions and palatal coverage on oral sensory functions

STATEMENT OF PROBLEM

Oral stereognosis (OS) plays a significant role in the oral rehabilitation of patients with edentulism, as it influences their adaptation to new prostheses. Because of the essentially tactile characteristic of oral sensory perception, the tongue and palate appear to have a crucial function in OS. However, little is known about the influence of tongue lesions on OS and sensorial function. In addition, controversies remain regarding the role of the palate.

PURPOSE

The purpose of this clinical study was to evaluate whether tongue lesions and palatal coverage are disruptive to OS and gustatory function.

MATERIAL AND METHODS

Seventy participants (mean age=30.7 ±6.7 years) were divided into a tongue lesion group (experimental; n=35) and a control group (n=35). The tongue lesion group included participants with geographic, fissured, or hairy tongue. OS was evaluated with the oral stereognosis ability (OSA) test. Gustatory function was assessed with exposure to flavored solutions. After completing the above tests, the participants received a palate covering device, and then OS and gustatory function were immediately reevaluated. Data were analyzed with the Mann-Whitney and Wilcoxon tests (α=.05).

RESULTS

OSA and gustatory function scores did not differ among the tongue lesion and control groups with and without palatal coverage (all P>.05). After palatal coverage, the tongue lesion group took more time to perform the OSA test than the control group (P<.05).

CONCLUSIONS

Neither the presence of tongue lesions nor palatal coverage influenced OS or gustatory function. The OSA test response times were longer for the tongue lesion group after they had received palatal coverage.

Palatal coverage and oral stereognosis: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Complete denture wearers present with less sensory function than dentate individuals because of the loss of periodontal receptors. However, the role of the palatal receptors on such function is still unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to evaluate the influence of palatal coverage associated with complete dentures or palatal devices on oral stereognosis in edentulous or dentate adults.

MATERIAL AND METHODS

Eight major literature databases and the nonpeer-reviewed literature were searched up to December of 2021. Randomized clinical trials and nonrandomized clinical trials comparing oral stereognosis in edentulous or dentate participants using conventional complete dentures or implant-supported prostheses or those using palatal devices were included. Bias was assessed with Cochrane tools (ROBINS-I and RoB 2.0). Meta-analyses were conducted to compare oral stereognosis before and after palatal coverage (α=.05). Certainty of the evidence was verified using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

RESULTS

Of 14 included studies, the risk of bias was considered low for 9 studies and moderate for 5 studies. Despite the very low certainty of evidence, meta-analyses showed no differences in oral stereognosis immediately after complete denture insertion (standardized mean difference [SMD]=0.302; 95% confidence interval [CI]: -0.124, 0.728; P=.165; I2=92.4%). Oral stereognosis scores improved after ≥1 month of complete denture use compared with initial evaluations without them. Qualitative analysis indicated that oral stereognosis was not influenced by palatal coverage shortly after complete denture installation and that oral stereognosis scores improved over time after prosthesis use.

CONCLUSIONS

Oral stereognosis improved with the use of palate-covering prostheses over time. However, because of the very low certainty of evidence, the statement must be interpreted with caution.

A review on children's oral texture perception and preferences in foods

Texture properties of foods are particular drivers for food acceptance and rejection in children. The texture preferences follow the developmental progression of the child and these changes modulate the present and future food habits. This paper reviews the development and factors influencing texture preferences in children and the methods in food texture research with children. The child's acceptance of more complex food textures is age-dependent. The progression is indorsed by the development of oral processing skills at an early age and bolstered by repeated exposures to foods with varying textures. Children generally reject foods containing pieces or bits (i.e., geometrical textural properties); however, the impact of mechanical textural properties on food acceptance is less clear. Child characteristics such as food neophobia, picky eating, and tactile over-responsivity, negatively affect the acceptance of more diverse food textures. Depending on the child's age, the prevailing methods of characterizing food texture preferences in children include observational techniques and self-reported questionnaires. Despite knowledge of children's development of masticatory skills, learning, and cognitive abilities, the relationships of these changes to food texture acceptance and the recommended test methodology for evaluating product texture acceptance in this period of life are still limited.

Mastication and oral sensory function in frail edentulous elderly: a case-control study

OBJECTIVE

To evaluate the maximum bite force (MBF), masticatory performance and oral sensory function (OSF) of frail edentulous elderly. The correlation of MBF with maximum grip strength (MGS) was also assessed.

METHODS

Twenty edentulous elderly [10 with and 10 without the frailty phenotype (FP)] were selected to participate in this case-control study. The FP was diagnosed using the criteria of Fried et al., which consider weight loss, exhaustion, physical activity level, weakness and slowness to the evaluation. All volunteers received new complete dentures (CDs) to standardise the occlusal status, and after 2 months of use with no complaint, all variables were assessed. MBF was measured by pressure sensors positioned bilaterally on the first artificial molars. Masticatory performance was assessed using the sieving method and was expressed as the median particle size (X₅₀ ) of Optocal after 40 masticatory cycles. OSF was evaluated using the oral stereognosis test, and MGS was measured using a dynamometer. Groups were compared using one-way analysis of variance. The Pearson coefficient of correlation between MBF and MGS was calculated.

RESULTS

Frail elderly people showed reduced MBF (P = 0.0431) and larger X₅₀ values (P = 0.0053) than did non-frail elders, while OSF did not differ between the groups. MBF had a moderate positive correlation with MGS (r = 0.690, P = 0.003).

CONCLUSIONS

Frail elderly had reduced MBF and impaired mastication. On the other hand, OSF does not seem to be affected by frailty. MBF was moderately correlated with MGS.

Sensorial Ability, Mastication and Nutrition of Single-Implant Overdentures Wearers

Abstract The use of two-implant overdentures improves mastication of edentulous elderly patients. However, little is known about the effects of single-implant overdentures (SIO) on oral perception and masticatory function in such elders. This study compared the effects of conventional complete dentures (CD) and SIO on the oral sensorimotor ability (OSA), masticatory function, and nutritional intake of elderly people with residual alveolar mandibular height classified as Class III or IV according to the American College of Prosthodontics. Twelve elders first received new conventional CD, which were later converted to SIO. All variables were evaluated after use of each prosthesis for 2 months. To evaluate OSA, elders closed their eyes and orally identified test pieces prepared from raw carrots. A kinesiographic device was used to measure chewing movements during mastication of a test material (Optocal). Masticatory performance (MP) was determined with the sieving method, and a 3-day food diary verified nutrient intake based on a standard Brazilian Food Composition Table. Data were analyzed using the Wilcoxon signed rank test and Student’s paired t test (P < 0.05). OSA results did not differ according to prosthesis type. However, opening and closing velocities during chewing and MP increased after SIO insertion (P < 0.05). Although no difference was observed in the intake of most nutrients, sodium ingestion decreased after SIO insertion (P < 0.05). SIO use had no effect on OSA, but significantly improved mastication and sodium intake of elders with decreased residual ridges height (Brazilian Registry of Clinical Trials #RBR-3kgttj).

Relationship between oral stereognostic ability and dietary intake in older Japanese adults with complete dentures

PURPOSE

Oral stereognostic ability (OSA) is a useful indicator of oral perception to recognize food characteristics during mastication. Previous studies have shown associations between dietary intake and oral health status, such as taste perception. However, the effect of oral sensory ability on dietary intake is unclear. The purpose of this study was to investigate the association between oral sensory ability and dietary intake in older Japanese complete denture wearers.

METHODS

This cross-sectional study included 164 participants aged 69-71 or 79-81years old, wearing both maxillary and mandibular complete dentures. OSA test was used to evaluate oral tactile perception. Diet during the preceding month was assessed using a self-administered diet history questionnaire. Multivariable linear regression analysis was conducted to assess the association between OSA score and food and nutrient intake after adjusting for age, sex, socioeconomic factors, and occlusal force.

RESULTS

The bivariate analysis showed that OSA score was significantly and positively correlated with intake of green and yellow vegetables and negatively correlated with intake of cereals among examined foods. OSA score was also positively correlated with intake of vitamins A, B₂, and C and α-tocopherol (as a substitute for vitamin E) among examined nutrients. After adjusting for age, sex, socioeconomic factors, and occlusal force, OSA score remained significantly associated with intake of green and yellow vegetables and α-tocopherol.

CONCLUSIONS

OSA was significantly associated with intake of green and yellow vegetables in older complete denture wearers.

Influence of lower complete denture use on masseter muscles and masticatory function: A longitudinal study

BACKGROUND

Edentulism can reduce mastication, leading to changes in food pattern, with possible consequences to masticatory muscle thickness.

OBJECTIVES

This study verified masticatory function and oral perception in subjects who did not use lower CDs, and whether the insertion of new upper and lower CDs would improve such variables.

METHODS

Fifteen edentulous elderly who wore only the upper CD were selected and received new upper and lower CD. Volunteers were evaluated at baseline and after 1, 3 and 6 months of new prosthesis use. Masticatory performance (MP) was assessed by the sieving method (X₅₀ values). Masseter thickness (MT) was evaluated by ultrasonography. Oral sensorial ability (OSA) was assessed by oral stereognosis test and maximum tongue pressure (MTP) was verified by pressure sensors. Data were submitted to repeated measures ANOVA and Tukey-Kramer posthoc tests (α = 0.05). Correlation between OSA and MTP was verified by Person's correlation.

RESULTS

X₅₀ and MTP decreased (P < 0.05) after 1 month and remained stable (P > 0.05) for next assessments. After 3 months, MT in rest position was increased (P < 0.05), while during maximum voluntary contraction 1 month was enough to increase MT (P < 0.05). There were no differences for OSA (P > 0.05) and no correlation between OSA and MTP.

CONCLUSION

Masticatory performance and masseter thickness of elderly who did not use the lower dentures were improved after 2 months using new upper and lower CDs. However, new CDs in both dental arch decreased MTP. Brazilian Registry of Clinical Trials (ReBEC #RBR-37gdst).

Impact of cognitive function on oral perception in independently living older people

OBJECTIVES

Oral tactile perception is important for better mastication, appetite, and enjoyment of food. However, previous investigations have not utilized comprehensible variables thought to have negative effect on oral perception, including aging, denture wearing, and cognitive function. The aim of this study was to elucidate the impact of cognitive function on oral perception in independently living older individuals.

MATERIALS AND METHODS

The study sample was comprised of 987 participants (466 males, 521 females; age 69-71 years). Oral examinations, assessments of cognitive function in preclinical level by Montreal Cognitive Assessment (MoCA)-J, and determination of oral stereognostic ability as an indicator of oral perception were performed. Related variables were selected by univariate analyses; then, multivariate logistic regression model analysis was conducted.

RESULTS

Univariate analyses revealed that number of teeth, removable dentures usage, and cognitive function respectively had a significant relationship with stereognostic score. Next, the subjects were classified into good and poor perception groups (lowest 17.4%) according to oral stereognostic ability. Logistic regression analysis revealed that lower cognitive function was significantly associated with poor oral perception (OR = 0.934, p = 0.017) after controlling for other variables.

CONCLUSIONS

Cognitive decline even in preclinical stage was associated with reduced oral perception after controlling for gender, tooth number and denture use in independent living older people.

CLINICAL RELEVANCE

This study suggested that preclinical level of change in cognitive function affected oral perception. Dental practitioners and caregivers may need to pay attention to reduced oral perception among older people even if they do not have trouble in daily life.

Individuality of masticatory performance and of masticatory muscle temporal parameters

OBJECTIVE

Mammalian mastication serves to improve intra-oral food reduction. Insufficient food reduction creates potential swallowing problems, whereas over-reduction may accelerate tooth wear and increase feeding time. Either extreme has consequences. The study's objectives were: (1) to study the relationship between food reduction, number of chews in a sequence, and chewing rate, (2) to study how controlling the number of chews and chewing rate variability affects food reduction, and (3) to assess how dentoskeletal morphological and electromyographical (EMG) characteristics impact food reduction.

DESIGN

Twenty-three healthy, fully-dentate adults chewed a standardized test food under three conditions: (1) no control, (2) number of chews controlled, and (3) number of chews and chewing rate controlled. EMG activity was sampled from masseter and temporalis muscles bilaterally. Demographic, occlusal contact area in maximum intercuspation, and cephalometric data were obtained.

RESULTS

In uncontrolled conditions, food reduction and bout duration varied more than expected across subjects. Subjects with poor reduction under controlled conditions were those with poor reduction under uncontrolled conditions. Only occlusal contact area correlated with chewing performance under uncontrolled conditions. Chewing cycle duration, EMG burst duration, and EMG peak onset latency increased when the number of chews was restricted. EMG amplitude, a surrogate for bite force, increased in tasks controlling the number of chews and chewing rate. Chewing rate variability was difficult to diminish below individual-specific levels.

CONCLUSIONS

Results: provided evidence that bite force, chewing rate, chewing performance and chewing bout duration reflected individual preferences. Future work will determine whether similar findings occur among other mammals.

Tactile recovery assessment with shortened Semmes-Weinstein monofilaments in patients with buccinator myomucosal flap oral cavity reconstructions

BACKGROUND

The sensitive restoration is a primary aim of oral reconstructive surgery. The Semmes-Weinstein monofilament test is the "Gold Standard" to assess the threshold of tactile sensitivity on the skin but its use in the oral cavity is limited due to the size of the tools. We adopted half-cut Semmes-Weinstein monofilaments to evaluate the threshold of tactile sensitivity in oral reconstructions with buccinator myomucosal flaps.

MATERIALS AND METHODS

Monofilaments were half-cut and recalibrated. Fifty-seven oral reconstructions were considered at 4-year minimum follow-up. Test was conducted both on the reconstructive flap and on the non-operated contralateral side.

RESULTS

All of the considered flaps (100%) showed a recovery of tactile sensitivity. The overall average tactile threshold value assessed on this sample was 0.76 ± 1.58 g/mm² overall.

CONCLUSIONS

Shortened monofilaments allow easily assessment of tactile sensitivity in all the oral cavity areas, even in operated patients which often present lockjaw or microstomia.

Relevance of Tongue Force on Mandibular Denture Stabilization during Mastication

PURPOSE

Tongue activity, involving stereognosis of denture position, food bolus distribution, and direct denture pressing, can affect the stability of removable mandibular dentures. Knowledge of details of tongue activity in patients with removable dentures could contribute to the development of training methods to improve bilateral mastication. The hypothesis of this study was that tongue force improves mandibular complete denture stabilization on the atrophied foundation during mastication load transfer with a typical balanced occlusion.

MATERIALS AND METHODS

Finite element analysis was used to assess the effect of tongue activity on denture stability, which was evaluated with objective biomechanical criteria. Denture movement (displacement), sliding distance on the mucosal surface, and pressure on the foundation during occlusal load transfer were considered with and without additional tongue forces.

RESULTS

Tongue force in the canine zone of the balancing flange contributed to a slight reduction in the sliding distance. An adverse effect of tongue force on the working side and in the posterior zone of the balancing side was found.

CONCLUSIONS

Despite the lack of substantial improvement in stability with the addition of tongue forces, tongue action that contributes to a slight reduction in sliding may help reduce common frictional trauma resulting from cyclic movement during chewing. The beneficial impact of tongue force shown in earlier work under conditions of complete adherence of dentures to the foundation indicates a benefit of using adhesives.

Sensory recovery of myomucosal flap oral cavity reconstructions

BACKGROUND

Sensory restoration of the oral cavity is a primary aim of reconstructive surgery in posttraumatic or postablative defects. Sensitivity plays a key role in oral function, whose impairment strongly affects the patient's quality of life. Cheek myomucosal flaps provide a reliable and tissue-like reconstruction of these regions but their sensitive recovery, which we still know little about, deserves thorough assessment.

METHODS

In this retrospective study, the myomucosal cheek flaps were tested for different aspects of sensory recovery: touch; 2-point discrimination; pain; sharp/smooth discrimination; ability to feel hot/cold stimulus; stereognosis; and taste.

RESULTS

Fifty-two myomucosal flap reconstructions were investigated. All sensitivity tests showed positive results. When comparison was possible, sensitivity seemed significantly close to the contralateral healthy side. Sensory recovery proved to be even better than that reported on reinnervated microvascular free flap reconstructions of the oral cavity.

CONCLUSION

Myomucosal flap reconstruction demonstrated a high degree of sensory recovery.

Oro-facial impairment in stroke patients

Stroke is considered one of the leading causes of death and acquired disability with a peak prevalence over the age of 80 years. Stroke may cause debilitating neurological deficiencies that frequently result in sensory deficits, motor impairment, muscular atrophy, cognitive deficits and psychosocial impairment. Oro-facial impairment may occur due to the frequent involvement of the cranial nerves' cortical representation areas, central nervous system pathways or motoneuron pools. The aim of this narrative, non-systematic review was to discuss the implications of stroke on oro-facial functions and oral health-related quality of life (OHRQoL). Stroke patients demonstrate an impaired masticatory performance, possibly due to reduced tongue forces and disturbed oral sensitivity. Furthermore, facial asymmetry is common, but mostly discrete and lip restraining forces are reduced. Bite force is not different between the ipsi- and contra-lesional side. In contrast, the contra-lesional handgrip strength and tongue-palate contact during swallowing are significantly impaired. OHRQoL is significantly reduced mainly because of the functional impairment. It can be concluded that impaired chewing efficiency, dysphagia, facial asymmetry, reduced lip force and OHRQoL are quantifiable symptoms of oro-facial impairment following a stroke. In the absence of functional rehabilitation, these symptoms seem not to improve. Furthermore, stroke affects the upper limb and the masseter muscle differently, both, at a functional and a morphological level. The rehabilitation of stroke survivors should, therefore, also seek to improve the strength and co-ordination of the oro-facial musculature. This would in turn help improve OHRQoL and the masticatory function, subsequently preventing weight loss and malnutrition.

Predictors of chewing ability among community-residing older adults in Korea

AIMS

Decreased chewing ability in older adults can lead to poor nutritional and physical conditions, and eventually death. The present study examined the relationships between chewing ability and related characteristics (e.g. health promotion habits, health status and functional status), and identified predictors of chewing ability in community-residing older adults.

METHODS

Among the total of 11 542 participants in the 2011 National Survey on Older Adults in Korea, data from 10 543 participants were used for analysis. Chewing ability was evaluated using a self-report of chewing ability. Exercise ability was assessed by objective exercise ability and perceived exercise ability in both the upper and lower extremities. Depression and cognitive functions were measured using the Geriatric Depression Scale-Short Form and the Mini-Mental State Examination, respectively.

RESULTS

A total of 56.9% of participants had poor chewing abilities. After adjusting for age and sex, logistic regression analysis showed that depression (OR 1.76, 95% CI 1.60-1.92), cognitive impairment (OR 1.28, 95% CI 1.17-1.40), objective exercise ability (OR 1.24, 95% CI 1.11-1.41), regular exercise habits (OR 1.23, 95% CI 1.13-1.34), medical check-up history (OR 1.17, 95% CI 1.05-1.32), number of chronic diseases (OR 1.12, 95% CI 1.09-1.15) and perceived exercise ability in the lower extremities (OR 1.08, 95% CI 1.05-1.10) were significant predictors of chewing ability.

CONCLUSION

Chewing ability in older adults should be improved in consideration of mental and general health condition. Geriatr Gerontol Int 2017; 17: 78-84.

A multifactorial model of masticatory performance: the Suita study

Previous studies have identified various factors related to masticatory performance. This study was aimed to investigate variations and impacts of factors related to masticatory performance among different occlusal support areas in general urban population in Japan. A total of 1875 Japanese subjects (mean age: 66·7 years) were included in the Suita study. Periodontal status was evaluated using the Community Periodontal Index (CPI). The number of functional teeth and occlusal support areas (OSA) were recorded, and the latter divided into three categories of perfect, decreased and lost OSA based on the Eichner Index. Masticatory performance was determined by means of test gummy jelly. For denture wearers, masticatory performance was measured with the dentures in place. The multiple linear regression analysis showed that, when controlling for other variables, masticatory performance was significantly associated with sex, number of functional teeth, maximum bite force and periodontal status in perfect OSA. Masticatory performance was significantly associated with number of functional teeth, maximum bite force and periodontal status in decreased OSA. In lost OSA, masticatory performance was significantly associated with maximum bite force. Maximum bite force was a factor significantly influencing masticatory performance that was common to all OSA groups. After controlling for possible confounding factors, the number of functional teeth and periodontal status were common factors in the perfect and decreased OSA groups, and only sex was significant in the perfect OSA group. These findings may help in providing dietary guidance to elderly people with tooth loss or periodontal disease.

Does shape discrimination by the mouth activate the parietal and occipital lobes? - near-infrared spectroscopy study

A cross-modal association between somatosensory tactile sensation and parietal and occipital activities during Braille reading was initially discovered in tests with blind subjects, with sighted and blindfolded healthy subjects used as controls. However, the neural background of oral stereognosis remains unclear. In the present study, we investigated whether the parietal and occipital cortices are activated during shape discrimination by the mouth using functional near-infrared spectroscopy (fNIRS). Following presentation of the test piece shape, a sham discrimination trial without the test pieces induced posterior parietal lobe (BA7), extrastriate cortex (BA18, BA19), and striate cortex (BA17) activation as compared with the rest session, while shape discrimination of the test pieces markedly activated those areas as compared with the rest session. Furthermore, shape discrimination of the test pieces specifically activated the posterior parietal cortex (precuneus/BA7), extrastriate cortex (BA18, 19), and striate cortex (BA17), as compared with sham sessions without a test piece. We concluded that oral tactile sensation is recognized through tactile/visual cross-modal substrates in the parietal and occipital cortices during shape discrimination by the mouth.

Analysis of temporal variation in human masticatory cycles during gum chewing

OBJECTIVE

The study investigated modulation of fast and slow opening (FO, SO) and closing (FC, SC) chewing cycle phases using gum-chewing sequences in humans.

DESIGN

Twenty-two healthy adult subjects participated by chewing gum for at least 20s on the right side and at least 20s on the left side while jaw movements were tracked with a 3D motion analysis system. Jaw movement data were digitized, and chewing cycle phases were identified and analysed for all chewing cycles in a complete sequence.

RESULTS

All four chewing cycle phase durations were more variant than total cycle durations, a result found in other non-human primates. Significant negative correlations existed between the opening phases, SO and FO, and between the closing phases, SC and FC; however, there was less consistency in terms of which phases were negatively correlated both between subjects, and between chewing sides within subjects, compared with results reported in other species.

CONCLUSIONS

The coordination of intra-cycle phases appears to be flexible and to follow complex rules during gum-chewing in humans. Alternatively, the observed intra-cycle phase relationships could simply reflect: (1) variation in jaw kinematics due to variation in how gum was handled by the tongue on a chew-by-chew basis in our experimental design or (2) by variation due to data sampling noise and/or how phases were defined and identified.

The effect of osteoporosis on residual ridge resorption and masticatory performance in denture wearers

AIM

To compare masticatory performance, masticatory efficiency and residual ridge resorption (RRR) in osteoporotic and non-osteoporotic edentulous subjects after rehabilitation with complete dentures.

METHOD

Thirty subjects fulfilling the inclusion criteria were enrolled from the patients visiting the Department of Prosthodontics for complete denture fabrication. Two groups consisting of control subjects (group I; N = 15) and osteoporotic subjects (group II; N = 15) were formed. Complete dentures satisfying certain criteria were fabricated for both groups. Masticatory performance and efficiency were measured 6 months after denture insertion. Areal measurements were taken on lateral cephalograms before and 6 months after denture fabrication. The data were then computed to analyse differences between groups I and II using SPSS statistical software version 15.0.

RESULTS

Six months after denture fabrication, the masticatory performance and efficiency were significantly higher (p < 0.001) for group I, with a significant decrease in maxillary and mandibular sagittal area seen in both groups. The rate of bone loss was more in group II compared with group I.

CONCLUSION

Greater masticatory function was demonstrated by the non-osteoporotic group, and the rate of RRR was more in the osteoporotic group compared with the normal group. In this pilot study, osteoporosis leads to greater RRR, decreased masticatory performance and efficiency in edentulous subjects 6 months after denture insertion. Screening for osteoporosis is suggested as a routine procedure for all edentulous subjects undergoing rehabilitation. Recall check-ups for osteoporotic patients should be more frequent, and these patients may require more frequent denture remakes.

Masticatory Function and Bite Force in Stroke Patients

Orofacial functions are frequently affected by stroke, but little is known on the nature and extent of the impairment of mastication, which is investigated in this observational study. Thirty-one stroke patients, aged 69.0 ± 12.7 yrs, presenting with a hemi-syndrome with facial palsy, were recruited. Chewing efficiency, maximum bite and restraining lip forces were tested. Stroke severity (National Institutes of Health Stroke Scale) and dental state were recorded. The control group was similar in age, gender, and dental state (n = 24). The chewing efficiency was significantly lower in the stroke group (p ≤ 0.0001) and was related to both the dental state and the lip forces measured with small and medium-sized labial plates. The maximum bite force proved to be not significantly different between sides or groups (n.s.), whereas lip force was significantly lower in the stroke group (p ≤ 0.05). Chewing efficiency is severely affected by stroke; thus, rehabilitation protocols should aim to restore the strength and co-ordination of the orofacial muscles.

Oral sensation and function: a comparison of patients with innervated radial forearm free flap reconstruction to healthy matched controls

BACKGROUND

Limited evidence exists for the use of innervated radial forearm free flap (RFFF) reconstruction of hemiglossectomy defects. This study reports on sensation, mastication, and speech outcomes for patients with innervated RFFF reconstruction of the anterior two-thirds of the tongue.

METHODS

Sensation, mastication, and speech intelligibility were assessed in 8 patients and age- and sex-matched controls.

RESULTS

Sensation of intact tongue tissue after reconstruction of the hemitongue did not differ from controls. Although some sensory ability was restored to patients' reconstructed tongue, differences existed between the patient group and controls. However, whole mouth sensations resulted in similar sensory ability as controls. Whereas patients demonstrated adequate masticatory and speech ability, differences existed between patients and controls.

CONCLUSION

Although some sensory ability is preserved in patients who have had tongue reconstruction with an innervated RFFF, functional outcomes such as masticatory ability and speech intelligibility may be affected in some patients.

Decrease in stereognostic ability of the tongue with age

Rehabilitation of eating and swallowing functions from the viewpoint of quality of life should attempt to restore not only the physical, but also sensory function. As the size and shape of the intra-oral bolus of food provides oral sensory information important for eating and swallowing, we investigated the stereognostic ability of the tongue in 269 young adults (mean age: 24.5 years) and 60 seniors (mean age: 80.5 years); all of whom had no eating or swallowing complaints. Assessment of the stereognostic ability involved identifying 20 differently shaped test pieces placed in the oral cavity. The young adults identified a significantly higher number of differently shaped test pieces than the seniors (mean correct number of responses: 16.5 and 10.1 respectively; P < 0.001). Gender and the presence of palatal covers did not have any significant effect on stereognostic ability. The test pieces were categorized into six groups based on the shape. When the young adults misidentified a piece, they often selected another piece within the same group, almost never selecting a piece from another group. The seniors, however, chose test pieces from different groups. Moreover, to determine whether stereognosis could be improved through training, we conducted training involving four senior subjects in their 80s, who correctly identified 10 or fewer pieces. After the training, the number of correct answers increased significantly (P < 0.05). These findings indicate that seniors show decreased stereognostic ability of the tongue compared with young adults and suggest the possibility of recovering the ability using our training method.

Assessment scale of the oral motor performance of children and adolescents with neurological damages

Among the conditions that classify individuals as special needs patients are those resulting from neurological sequelae, particularly cerebral palsy (CP), which is a disorder of high prevalence. Innumerable alterations can be found in individuals with CP but the inability to control striated muscles, due to damages suffered by the central nervous system, should be emphasized. Changes in tonus, speed and strength of oral muscles, reduction of mandibular mobility amplitude and difficulty to passively seal the lips are characteristics observed in such individuals. Categorization of the individual's mastication pattern is important in order to establish diagnosis and treatment protocols and prognosis. The aim of this study was to develop an Oral Motor Assessment Scale (OMAS) and evaluate its performance in terms of construct validity and reliability in a cohort of 53 children and individuals with CP. Two dentists examined the same patients on two different occasions. Good interexaminer (kappa > 0.85) and intra-examiner (kappa > 0.90) agreement was obtained for the majority of the OMAS items. This study shows that the OMAS is an accurate and valid method of assessment of oral motor skills in children and adolescents with neurological damages.

[Influence of setting position of palatal bar on thickness discrimination]

PURPOSE

The aim of this study was to evaluate the variation of thickness discrimination by wearing an upper removable partial denture. We investigated the thickness discrimination by changing the covered area and the food-recognizing area of the palate. We also evaluated the variation of thickness discrimination after two weeks of wearing the plate which covered the anterior area of the palate.

METHODS

Four kinds of experimental palatal plate, which covered the anterior, middle, posterior and whole area of the palate, were used. Five kinds of test pieces were used for the thickness discrimination test. The same test pieces coated with a fit checking material for removable dentures were used to detect the food-recognizing area. The thickness discrimination test was done after two weeks by the same method mentioned above.

RESULTS

The food-recognizing area was the anterior part of the plate regardless of with or without the experimental palatal plate. Although the thickness discriminative ability was the worst when wearing the plate that covered the anterior part of the palate, the ability improved by wearing the plate for two weeks.

CONCLUSION

These results suggest that the removable partial denture covering the anterior part of the palate decreased the food discrimination, but it improved by wearing for two weeks.

A two-colour chewing gum test for masticatory efficiency: development of different assessment methods

OBJECTIVE

The aim of this study was to investigate different assessment methods of a two-colour chewing gum test for masticatory efficiency to determine its validity for research and clinical purposes.

MATERIALS AND METHODS

Twenty adult volunteers, eleven women and nine men (mean age of 27.5 years), participated in this study. All participants perceived their masticatory efficiency as normal. The task was to chew five samples of a two-colour chewing gum for 5, 10, 20, 30 and 50 cycles respectively. Maximum bite force was measured. All samples were assessed twice by two independent operators both, as 'bolus' and after flattening to 1 mm thick 'wafers'. The latter were scanned and the unmixed pixels counted using Adobe Photoshop Elements to calculate the ratio of unmixed colour to the total surface.

RESULTS

Digital image processing confirmed a significant correlation between colour mixing and chewing duration (P < 0.001). Subjective assessment proved less accurate with fair to substantial intra-examiner agreement for 'bolus' (0.20 < kappa < 0.63) and substantial to almost perfect agreement for 'wafer' (0.60 < kappa < 0.88). Inter-examiner agreement was consistently moderate or substantial only for specimen chewed 20 cycles or longer. No significant correlation was found between the colour mixture and the maximum bite force.

CONCLUSION

Digital image processing of the two-colour chewing gum test specimen provides reliable quantitative data for chewing efficiency. Visual assessments were less reliable but might still be useful in screening for chewing deficiencies in a clinical setting. In this context, the test should be performed with a flattened specimen chewed, probably for 20 cycles.

Comparison of oral stereognosis in relation to age and the use of complete dentures

The purpose of this study was to examine the age-related difference in oral sensory function by testing oral stereognostic ability (OSA) and to determine the effect of wearing complete dentures on OSA. Subjects were 20 dentate and 30 edentulous elderly patients free from oral symptoms and pathologies, and 30 younger dentate students as controls. The OSA tests were conducted with test pieces of 12 shaped forms. The duration time for recognition was noted and the answers were recorded using a three-point scale. anova and paired t-tests were used to examine significant differences. P-values <0.05 were considered to be statistically significant. The OSA score in older dentate participants and complete denture wearers was significantly higher than in younger dentate subjects. However, no significant difference was found in the OSA score between older dentate participants and complete denture wearers. When older edentulous subjects removed the maxillary and mandible complete dentures, the OSA score was significantly lower and the response time significantly longer than with dentures. Within the limitations of this study, an age-related difference in oral sensory function, as measured by OSA tests, was found. However, oral sensory function was not significantly different between fully dentate persons and complete denture wearers in the elderly.