Subjective Evaluation of Denture Adhesives: A Multicenter Randomized Controlled Trial.

INTRODUCTION: Many reports show that denture adhesives improve the retention and stability of dentures. However, few randomized controlled trials have examined the effects of denture adhesives. OBJECTIVE: This 10-center randomized controlled trial with parallel groups involving 200 edentulous patients wearing complete dentures aimed to evaluate the effects of short-term use of cream and powder denture adhesives. METHODS: Patients were allocated into 2 cream- and powder-type adhesive groups and 1 control group. Intervention groups were treated with the 2 adhesives (1 each), and the control group received saline solution. Adhesive or control was applied to the denture-mucosal surface for 4 d, and data at baseline and after day 4 of intervention (i.e., 8 meals) were obtained. Patient satisfaction was evaluated with a 100-mm visual analog scale. Oral health-related quality of life was measured with the Japanese version of the Oral Health Impact Profile for Edentulous Patients. Perceived chewing ability was evaluated by a questionnaire regarding ease of chewing and swallowing food. Between-group comparisons were performed with Kruskal-Wallis tests with the Mann-Whitney U test adjusted by Bonferroni correction. Within-group comparisons of pre- and postintervention measurements were performed with the Wilcoxon signed-rank test. Intention-to-treat analysis was also performed. RESULTS: Between-group comparisons showed no significant differences for general satisfaction or Oral Health Impact Profile for Edentulous Patients. However, significant differences in satisfaction with various denture functions with cream- and powder-type adhesives were seen in pre- and postintervention comparisons (P < 0.05). Significant differences were also observed for perceived chewing ability of hard foods (P < 0.05). CONCLUSION: These results suggest that although denture adhesives do not invariably improve denture function, they do affect subjective evaluations and possibly chewing of hard foods. Therefore, the effects of denture adhesive use are insufficient to resolve any fundamental dissatisfaction with dentures ( ClinicalTrials.gov NCT01712802 ). KNOWLEDGE TRANSFER STATEMENT: The results of this study suggest that denture adhesives should be applied under certain conditions; however, an appropriate diagnosis is important before application. These practice-based data provide information to establish evidence-based guidelines for applying denture adhesives.

Factors associated with masseter muscle quality assessed from ultrasonography in community-dwelling elderly individuals: A cross-sectional study.

BACKGROUND: Associations between masseter muscle thickness(MMT) and limb muscle thickness, and between grip strength and MMT, as well as tooth-loss, have been reported previously. The previous study also showed that masseter muscle mass could be a better marker of sarcopenia than psoas muscle mass. Although the association between MMT and muscle strength is also known, the quality of the masseter muscle were not assessed in detail previously. We examined the relationship of masseter muscle echo intensity (MMEI) with skeletal muscle, physical function, and nutrition status, in order to determine whether MMEI could be a good indicator of these parameters. METHODS: We assessed 139 community-dwelling elderly individuals (men: 65, women: 74). Age, body mass index (BMI), skeletal muscle mass index, grip strength, walking speed, calf circumference, tooth-loss (Eichner classification), occlusal force, MMT, and MMEI were obtained. In multiple regression analysis, MMEI were set as dependent variables. RESULTS: Multiple regression analysis revealed BMI (p < 0.05), grip strength (p < 0.01), walking speed (p < 0.01), and MMT (p < 0.01) as factors with significant association with MMEI. CONCLUSIONS: MMT is related to occlusal force and MMEI. MMEI was related strongly to grip strength and walking speed, but not to tooth-loss. However, MMEI, which is easily determined ultrasonographically, could be a good indicator of grip strength and walking speed, and thus may be predictive of dynapenia.

Evaluation of swallowing ability using swallowing sounds in maxillectomy patients.

Maxillectomy for oral tumours often results in debilitating oral hypofunction, which markedly decreases quality of life. Dysphagia, in particular, is one of the most serious problems following maxillectomy. This study used swallowing sounds as a simple evaluation method to evaluate swallowing ability in maxillectomy patients with and without their obturator prosthesis placed. Twenty-seven maxillectomy patients (15 men, 12 women; mean age 66.0 ± 12.1 years) and 30 healthy controls (14 men, 16 women; mean age 44.9 ± 21.3 years) were recruited for this study. Participants were asked to swallow 4 mL of water, and swallowing sounds were recorded using a throat microphone. Duration of the acoustic signal and duration of peak intensity (DPI) were measured. Duration of peak intensity was significantly longer in maxillectomy patients without their obturator than with it (P < .05) and was significantly longer in maxillectomy patients without their obturator than in healthy controls (P < .025 after Bonferroni correction). With the obturator placed, DPI was significantly longer in maxillectomy patients who had undergone soft palate resection than in those who had not (P < .05). These results suggest swallowing ability in maxillectomy patients could be improved by wearing an obturator prosthesis, particularly during the oral stage. However, it is difficult to improve the oral stage of swallowing in patients who have undergone soft palate resection even with obturator placement.

The relationship between jaw-opening force and the cross-sectional area of the suprahyoid muscles in healthy elderly.

We conducted a clinical cross-sectional study to examine the relationship between jaw-opening force and the cross-sectional area of the suprahyoid muscles and whole skeletal muscle mass. Subjects were healthy 39 males and 51 females without dysphagia and sarcopenia, aged 65 years and older. Jaw-opening force was measured three times using a jaw-opening sthenometer; the maximum of these three was taken as the measurement value. The cross-sectional area of the geniohyoid and anterior belly of the digastric muscles were evaluated using ultrasonography. The skeletal muscle mass index, gait speed and grip strength were evaluated according to the diagnostic criteria of the Asian Working Group for Sarcopenia. For each sex, a multiple regression analysis determined the factors that affect jaw-opening force. Jaw-opening force was associated with the cross-sectional area of the geniohyoid muscle in males (regression coefficient [ß] = 0.441, 95% confidence interval [CI] = 14.28-56.09) and females (ß = 0.28, 95% CI = 3.10-54.57). Furthermore, in females only, jaw-opening force was associated with the skeletal muscle mass index (ß = 0.40, 95% CI = 3.67-17.81). In contrast, jaw-opening force was not associated with the cross-sectional area of the anterior belly of the digastric muscle in either sex. In healthy elderly males and females, jaw-opening force was positively associated with the cross-sectional area of the geniohyoid muscle. However, the jaw-opening force was positively associated with the skeletal muscle mass index only in females.

A new evaluation of masticatory ability in patients with dysphagia: The Saku-Saku Test.

OBJECTIVE: In the elderly and patients with dysphagia, masticatory problems often cause aspiration or choking. Although simple methods to predict aspiration and silent aspiration exist, methods for evaluating the masticatory function of patients with dysphagia are lacking. Accordingly, we developed a simple test to assess the chewing and swallowing ability of patients with dysphagia. METHODS: One hundred and five patients with dysphagia were included. We used the Saku-Saku Test (SST), in which patients were asked to eat a rice cracker, and evaluated the quality of mandibular rotation during mastication. We studied the participants' ability to grind, aggregate, and swallow using videoendoscopic evaluation (VE) and investigated its association with mandibular rotation. RESULTS: The SST showed good reliability between two examiners, with a kappa coefficient of 0.80. 92.4% of the patients ate the rice cracker without aspiration. The SST showed a high sensitivity of 73.3% and specificity of 93.3% for the degree of grinding. The degree of food bolus aggregation had a sensitivity of 45.0% and specificity of 90.6%, and aspiration had a sensitivity of 25.0% and specificity of 84.5%, both of which showed high specificity. CONCLUSIONS: The results of this study suggested that the SST might be simple and useful for identifying patients with dysphagia who are able to masticate, even if they do not eat foods that need chewing and could be used before starting these patients on foods that need chewing.

Masticatory performance-related factors in preschool children: establishing a method to assess masticatory performance in preschool children using colour-changeable chewing gum.

A knowledge gap regarding masticatory performance in preschool children exists, which in turn delays intervention for preventive care; therefore, a method to easily assess performance is needed. The purpose of this study is to investigate the feasibility of assessing masticatory performance using colour-changeable chewing gum and to investigate masticatory performance-related factors in preschool children. This cross-sectional survey was conducted in two childcare facilities and our laboratory. First, a one-third quantity of colour-changeable chewing gum was masticated by six adults to assess the nature and progression of colour changes in this quantity. Then, masticatory performance in 370 children 4-6 years of age was assessed using the same quantity of colour-changeable chewing gum (60 chew strokes). The maximum bite force, body height, weight, age and number of healthy teeth were recorded. A t-test was performed to determine whether gum-chewing experience or lack thereof produced a significant difference in masticatory performance. The Spearman's rank correlation coefficient was then determined for masticatory performance assessment values and other factors solely for children with gum-chewing experience. Measurements from 259 children were obtained. Children with gum-chewing experience demons trated significantly higher assessment values and were deemed to have been correctly assessed. A very weak but significant positive correlation was observed only between masticatory performance and the number of healthy teeth. The masticatory performance of preschool children was easily assessed using colour-changeable chewing gum. The assessment values demonstrated significant correlation with the number of healthy teeth, but not with maximum bite force, body height, weight or age.

Effect of an impaired oral stage on swallowing in patients with Parkinson's disease.

We investigated the swallowing function in patients with Parkinson's disease (PD) using deteriorated tongue control because patients with PD frequently exhibit an impaired oral stage of swallowing and the tongue movement affects oral and pharyngeal stage. In total, 201 patients with PD (106 men, 95 women; mean age 70·6 ± 8·0 years; median Hoehn-Yahr Stage III) were studied. The patients swallowed 10 mL of liquid barium under videofluorography, and their oral transit time (OTT) was measured. Based on 20 healthy controls (mean age 70·3 ± 7·8 years) with an OTT + 2 standard deviation (0·89 + 2 × 0·46) of 1·81 s, the patients with PD were divided into 167 patients with an OTT < 1·81 s and 34 patients with an OTT ≥ 1·81 s. Swallowing function was compared between the groups and assessed using logistic regression analysis. The following factors were significantly associated with oral stage impairment in both groups: tongue-to-palate contact, tongue root-to-posterior pharyngeal wall contact, premature spillage into the pharynx, aspiration and onset of swallowing reflex. Logistic regression analysis showed that tongue root-to-posterior pharyngeal wall contact, onset of swallowing reflex and aspiration were independent factors. PD patients with prolonged OTT displayed poor lingual control and decreased range of motion of the tongue due to bradykinesia and rigidity. Such problems in the oral stage affected the subsequent pharyngeal stage of swallowing with aspiration. Lingual movement in the oral stage thus appears to play an important role in the sequential movement of swallowing in PD.

Structural and Chemical Analysis of the Zirconia-Veneering Ceramic Interface.

The interfacial interaction of veneering ceramic with zirconia is still not fully understood. This study aimed to characterize morphologically and chemically the zirconia-veneering ceramic interface. Three zirconia-veneering conditions were investigated: 1) zirconia-veneering ceramic fired on sandblasted zirconia, 2) zirconia-veneering ceramic on as-sintered zirconia, and 3) alumina-veneering ceramic (lower coefficient of thermal expansion [CTE]) on as-sintered zirconia. Polished cross-sectioned ceramic-veneered zirconia specimens were examined using field emission gun scanning electron microscopy (Feg-SEM). In addition, argon-ion thinned zirconia-veneering ceramic interface cross sections were examined using scanning transmission electron microscopy (STEM)-energy dispersive X-ray spectrometry (EDS) at high resolution. Finally, the zirconia-veneering ceramic interface was quantitatively analyzed for tetragonal-to-monoclinic phase transformation and residual stress using micro-Raman spectroscopy (µRaman). Feg-SEM revealed tight interfaces for all 3 veneering conditions. High-resolution transmission electron microscopy (HRTEM) disclosed an approximately 1.0-µm transformed zone at sandblasted zirconia, in which distinct zirconia grains were no longer observable. Straight grain boundaries and angular grain corners were detected up to the interface of zirconia- and alumina-veneering ceramic with as-sintered zirconia. EDS mapping disclosed within the zirconia-veneering ceramic a few nanometers thick calcium/aluminum-rich layer, touching the as-sintered zirconia base, with an equally thick silicon-rich/aluminum-poor layer on top. µRaman revealed t-ZrO2-to-m-ZrO2 phase transformation and residual compressive stress at the sandblasted zirconia surface. The difference in CTE between zirconia- and the alumina-veneering ceramic resulted in residual tensile stress within the zirconia immediately adjacent to its interface with the veneering ceramic. The rather minor chemical elemental shifts recorded in the veneering ceramic did not suffice to draw definitive conclusions regarding potential chemical interaction of the veneering ceramic with zirconia. Sandblasting damaged the zirconia surface and induced phase transformation that also resulted in residual compressive stress. Difference in CTE of zirconia versus that of the veneering ceramic resulted in an unfavorable residual tensile stress at the zirconia-veneering ceramic interface.

Association between tongue and lip functions and masticatory performance in young dentate adults.

Motor functions of masticatory organs such as the tongue, lips, cheeks and mandible are known to deteriorate with age, thereby influencing masticatory performance. However, there are few reports on the relationships between tongue and lip functions and masticatory performance. To investigate the relationship between tongue and lip functions and comprehensive masticatory performance, by evaluating crushing, mixing and shearing abilities in young dentate adults. Participants comprised 51 dentate adults with a mean age of 25 years. Maximum tongue pressure and oral diadochokinesis were measured to evaluate tongue and lip functions. A multiple sieving method using peanuts was performed to evaluate crushing ability. A colour-changeable chewing gum was performed to evaluate mixing ability. A test gummy jelly was performed to evaluate shearing ability. The relationship between tongue and lip functions and each masticatory performance was assessed using Pearson's correlation coefficients. In addition, stepwise multiple regression analysis was performed to identify predictors of crushing ability. Crushing ability was significantly correlated with maximum tongue pressure and the number of repetitions of the syllables /pa/, /ta/ and /ka/. Maximum tongue pressure and number of repetitions of the syllable /pa/ were identified as significant predictors for crushing ability. Mixing ability was significantly correlated with the number of repetitions of the syllable /pa/. Shearing ability was not significantly correlated with tongue and lip functions. Masticatory performance during the chewing of brittle foods such as peanuts and solid foods such as chewing gum appears to be correlated with tongue and lip functions.

Association between near occlusal contact areas and mixing ability.

This study investigated the relationship between occlusal contact and near contact areas defined by clenching intensity using electromyograms (EMGs) and mixing ability assessed with colour-changeable chewing gum. Participants comprised 44 dentate adults (24 men, 20 women) with a mean age of 28·2 ± 6·8 years. Silicone material was used to measure the occlusal contact and near contact areas (the area of each type of tooth, the total area of the first molar and second molar, the second premolar to the second molar and the first premolar to the second molar) defined by clenching intensity at 10% maximum voluntary contraction (MVC). Colour-changeable chewing gum was used to assess mixing ability. A colorimeter was used to measure colour changes, and the calculated colour difference (ΔE) was used as a measure of mixing ability. Correlation analysis of ΔE and occlusal contact and near contact areas revealed a significant positive correlation of 0·47 at 0-160 µm thicknesses of the silicone registration material of the second molar (P < 0·01). The near contact area with a thickness up to 200 µm was correlated with mixing ability, with the correlation strengthening as the interocclusal distance increased up to 160 µm. Notably, occlusal contact and near contact areas of the second molar were strongly correlated with mixing ability in dentate adults.

Meta-analysis of bonding effectiveness to zirconia ceramics.

Dental zirconia can no longer be considered un-bondable to tooth tissue. In literature, an increasing number of papers indeed report on the bonding effectiveness of different luting techniques to zirconia. We aimed to disclose general trends in bonding to zirconia by systematically collecting zirconia bond-strength data. A search in PubMed and EMBASE revealed 1,371 bond-strength tests reported on in 144 papers. A macro-shear bond-strength protocol was most frequently used; it revealed significantly lower bond strengths and was less discriminative than the other test methods. Regarding luting technique, the combination of mechanical and chemical pre-treatment appeared particularly crucial to obtain durable bonding to zirconia ceramics. The cement choice was not revealed as a determining factor after aging conditions, as long as composite cement was used. Regarding test protocol, a tensile test appeared more discriminative, particularly when combined with 'water storage' aging.

Association between self-assessment of complete dentures and oral health-related quality of life.

The purpose of this study was to determine which factors related to patient self-assessment of dentures are associated with changes in oral health-related quality of life (OHRQoL) among edentulous patients after replacement of complete dentures, and to determine whether masticatory performance as determined using an objective method affects the changes in OHRQoL among edentulous patients. As a preliminary study, the existing questionnaire regarding self-assessment of dentures consisting of 39 question items, measured with a 100-mm visual analogue scale, was analysed by factor analysis. Then a questionnaire, composed of 22 question items, was developed containing six subscales of 'function', 'lower denture', 'upper denture', 'expectation', 'aesthetic and speech' and 'importance'. Final participants in the present study comprised 93 edentulous patients requiring new conventional complete dentures (44 men, 49 women; mean age, 75·0 years). These patients were asked to complete the Japanese version of the Oral Health Impact Profile (OHIP)-EDENT, comprising 19 question items for assessment of OHRQoL in edentulous patients, along with the developed questionnaire regarding self-assessment of dentures. Moreover, masticatory performance was measured using a colour-changeable chewing gum. The questionnaire and measurement were completed twice; before and after replacement of complete dentures. Stepwise multiple regression analysis identified 'lower denture' and 'aesthetic and speech' as significant independent variables besides OHIP-EDENT scores before replacement. These results suggest that sufficient retention of lower dentures and appropriate appearance may lead to improved OHRQoL in edentulous patients.

Association between masticatory performance using a colour-changeable chewing gum and jaw movement.

The purpose of this study was to investigate the relationship between masticatory performance as determined using a colour-changeable chewing gum and mandibular movements. Subjects comprised 45 fully dentate adults (23 men, 22 women; mean age, 28·1 years). The gum was chewed for a specified number of chewing strokes (20, 40, 60, 80, 120 or 160 strokes) without any instructions as to chewing side. A colourimeter was used to measure L*, a* and b* values (CIE-L*a*b* colour system) for the chewed gum, then the difference between two colours in the CIE-L*a*b* colour space (ΔE) for each number of chewing strokes was calculated according to a formula. Index of masticatory performance (ΔE60) for each subject was obtained using ΔE for 20, 40, 60, 80, 120 and 160 strokes. Mandibular movements were recorded using an opto-electric system with six degrees of freedom. Twelve parameters of mandibular movements relating to amplitude, duration, velocity and angle were computed for each cycle, and mean values for 10 cycles (from cycle 11 to 20) were calculated separately. Stepwise multiple regression analysis identified maximum closing velocity and closing angle as predictors accounting for 18% of the variation in ΔE60. These results suggest that lower angles of approach to intercuspation and faster speed during closing duration are associated with colour changes in the colour-changeable chewing gum.

Measuring system for lip movements using two video trackers.

Movements of soft tissues surrounding the oral cavity, especially lips and cheeks, have a strong influence on mastication and phonetics. They also influence the relationship between a denture and its oral environment. The purpose of this study was to develop a three-dimensional measuring system for soft tissue movement. This system consisted of two video trackers placed stereographically and a computer. In addition, one video tracker was connected for measuring mandibular movements. The accuracy of this system was evaluated using computerized XYZ pulse stage. The resolution of this system was 0.10 x 0.10 x 0.10 mm, when the measurement was carried out in the area of the 24.0 (X) x 20.0 (Y) x 20.0 (Z) mm with a working distance of 500 mm and a frequency of 120 Hz. In the present study, the lip movements of a dentulous subject with mandibular movements during chewing peanuts were analysed using this system. The new system demonstrated its value for analysing soft tissue movement.

Denture mobility with six degrees of freedom during function.

The purpose of this study was (1) to assemble and verify a system to measure the three-dimensional (3-D) movement of the upper and lower complete dentures and the movement of the mandible simultaneously, and (2) to analyse the relation between denture movements and the path of closure of the mandible during function. A 3-D motion capture system with four infrared TV cameras was used for this purpose. The relation between the dentures and the mandibular movements was analysed through the change of the inner product of normal vectors of the denture occlusal planes and mandibular planes. The mandibular movements were classified into two types; the normal stroke (the path of closure was on the ipsilateral side of mastication) and the reverse stroke (on the contralateral side). The results showed that the system could measure the denture mobility within a 0.3 mm error. The mobility of the upper dentures had a correlation to the path of closure of the mandible regardless of the working side or nonworking side, and the lower dentures had a tendency to move toward the working side.

Effect of mastication on regional cerebral blood flow in humans examined by positron-emission tomography with ¹5O-labelled water and magnetic resonance imaging.

The interaction between mastication and cerebral blood flow was studied in 12 healthy volunteers (five males and seven females) aged 18-40 years. Positron-emission tomography (PET) autoradiography was carried out after bolus injection of 1.5 GBq H2¹5O (¹5O-labelled water) with a half life of 2 min. The PET images were superimposed on magnetic resonance images of each participant. The regional cerebral blood flow images were normalized by the global cerebral blood flow value, and subtraction images (those during gum-chewing minus those during resting) were created and recut at the magnetic resonance image slice positions. Gum specially designed for chewing training was used. Mastication increased regional cerebral blood flow in the primary sensorimotor areas by 25-28%, in the supplementary motor areas and insulae by 9-17%, and in the cerebellum and striatum by 8-11%. These increases demonstrate that chewing activates widespread regions of the brain.

[Clinical evaluation of measuring system of occlusal force].

An occlusal diagnostic system was evaluated for clinical applications. This system consists of pressure sensitive sheets (DENTAL PRESCALE, Fuji Photo Film Co.) and analyzing computer (OCCLUZER FPD703, Fuji Photo Film Co.). The clinical efficiency of this system was evaluated in aged dentates, aged complete denture wearers and an aged patient suffered from periodontitis. The results were as follows: 1. There was a positive correlation between the masticatory efficiency and maximum occlusal force. 2. In the complete denture wearers, the distances from the medial line to the center of the occlusal load were statistically greater in the adjustment needed cases than in the control group. 3. In a case of periodontitis, the full arch fixed splint was adjusted using this system. After adjustment, the maximum occlusal force and contact area increased, and the maximum and medial pressure of the occlusal contact force decreased. 4. It was suggested that this system would be available for the examination of masticatory efficiency and diagnosis of various types of occlusions.

[Epidemiological study on distribution of plaque, calculus and gingivitis among Nigerian people].

In 1991, dental health examination was carried out in Nigeria: ILE-IFE (urban) and Ashipa (rural) located in the southwest of Nigeria. The number of the subjects was 205 (aged 8, 10, 12) in ILE-IFE and 511 (aged 8, 10, 12, 15 to 75) in Ashipa. The purpose of this study is to clarify the distribution of plaque, calculus and gingivitis and to reveal the correlation between the plaque score (DI-S, OHI-S), calculus score (CI-S, OHI-S) and gingivitis score (GI) among the Nigerian by age. Results were as follows: 1. In the comparison between urban and rural schoolchildren, CI-S was higher in the rural children statistically but DI-S was not. This evidence is to be expected as a consequence of using PACO (traditional twig) for tooth brushing, because 73.1% of rural children were using the PACO whilst 92.1% of urban children were using the tooth-brush. 2. Because of the poor oral cleanliness using PACO, the changing pattern of DI-S, CI-S and GI by age could be natural and physiological. 3. DI-S and CI-S among the rural people were of a high level in the children 8 and 10 years of age and decreased to the bottom level in the 20's. After the lowest scores in the 20's, these increased with age. 4. The correlations between DI-S and GI were higher in the young people than in the elder people.

Joint epidemiological longitudinal dental survey in Nigeria, especially in comparison with that of Japanese.

Since 1980 we carried out a longitudinal dental survey in Ile-Ife, as a joint study with the dental school of Ife University, Nigeria, being supported by A Grant under The Monbusho International Scientific Research Program for ten years. One thousand one hundred seventy-one children and adults were examined in the 1991 survey. The data were compared with the data in the previous survey and Japanese survey. Results were as follows: 1) Caries prevalence rate and the average number of DMFT were still very low, especially showing that both the caries prevalence and the average number of DMFT decreased in the rural areas because the attrition proceeded faster than the caries, 2) Nigerian deciduous and permanent dentition were larger than in the Japanese in all items measured, 3) the condylar head was transformed from the round shape to the ultra-flat shape with age, 4) there was a fewer incidence of severe periodontal diseases despite of the marked deposition of calculus, 5) with respect to Nigerian foods, there was no difference between the rainy and dry seasons in both the urban and rural communities, 6) the weaning period of the baby is decided by their mother, taking care of the health of the baby, almost all babies at one year to two years and a few at three years and 7) the menu for the breakfast, lunch and supper of the baby was made considering the nutritional aspect of the baby.