Changes in Gloss Alteration, Surface Roughness, and Color of Direct Dental Restorative Materials after Professional Dental Prophylaxis

In the context of optimizing dental care for patients who are elderly, the purpose of this in vitro study was to evaluate the surface gloss (with a micro-area gloss meter) of, surface roughness (with a compact surface roughness measuring instrument) of, and color change (with a dental colorimeter) in two commercially available injectable resin-based composites (Estelite Universal Flow (EUF) and Beautifil Flow Plus F00 (BFP)) as well as two glass-ionomer cements (GC Fuji II LC CAPSULE (FLC) and GC Fuji IX GP EXTRA CAPSULE (FGP)), before and after dental prophylaxis. After 24 h, the surfaces of each specimen were polished at 2500 rpm with a prophy brush (Mersage Brush, Shofu) and one-step prophylaxis paste (Prophy Paste Pro, Directa): under 100 or 300 gf load, and for 10 or 30 s, 4× cycles of cleaning. After mechanical cleaning, conditions were found for a significant reduction in the gloss level (EUF, BFP, or FLC; p < 0.05) and a significant increase in surface roughness (BFP; 300 gf load, 10 s × four cycles of cleaning). Overall, the longer time or higher prophylaxis load tended to decrease the surface gloss. However, the observed change in surface roughness varied between the restorative materials. There was no color change post-prophylaxis.

Evaluation of the chemical, physical, and biological properties of a newly developed bioceramic cement derived from cockle shells: an in vitro study

BACKGROUND

Tricalcium silicate is the main component of commercial bioceramic cements that are widely used in endodontic treatment. Calcium carbonate, which is manufactured from limestone, is one of the substrates of tricalcium silicate. To avoid the environmental impact of mining, calcium carbonate can be obtained from biological sources, such as shelled mollusks, one of which is cockle shell. The aim of this study was to evaluate and compare the chemical, physical, and biological properties of a newly developed bioceramic cement derived from cockle shell (BioCement) with those of a commercial tricalcium silicate cement (Biodentine).

METHODS

BioCement was prepared from cockle shells and rice husk ash and its chemical composition was determined by X-ray diffraction and X-ray fluorescence spectroscopy. The physical properties were evaluated following the International Organization for Standardization (ISO) 9917-1;2007 and 6876;2012. The pH was tested after 3 h to 8 weeks. The biological properties were assessed using extraction medium from BioCement and Biodentine on human dental pulp cells (hDPCs) in vitro. The 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5[(phenylamino)carbonyl]-2 H-tetrazolium hydroxide assay was used to evaluate cell cytotoxicity following ISO 10993-5;2009. Cell migration was examined using a wound healing assay. Alizarin red staining was performed to detect osteogenic differentiation. The data were tested for a normal distribution. Once confirmed, the physical properties and pH data were analyzed using the independent t-test, and the biological property data were analyzed using one way ANOVA and Tukey's multiple comparisons test at a 5% significance level.

RESULTS

The main components of BioCement and Biodentine were calcium and silicon. BioCement's and Biodentine's setting time and compressive strength were not different. The radiopacity of BioCement and Biodentine was 5.00 and 3.92 mmAl, respectively (p < 0.05). BioCement's solubility was significantly higher than Biodentine. Both materials exhibited alkalinity (pH ranged from 9 to 12) and demonstrated > 90% cell viability with cell proliferation. The highest mineralization was found in the BioCement group at 7 days (p < 0.05).

CONCLUSIONS

BioCement exhibited acceptable chemical and physical properties and was biocompatible to human dental pulp cells. BioCement promotes pulp cell migration and osteogenic differentiation.

Relationship between age and occlusal force in adults with natural dentition

This study aimed to clarify the relationship between age and occlusal force in adults with natural dentition. A total of 385 adults (180 males and 205 females) with natural dentition participated in this study. Subjects were asked to perform maximum clenching for approximately 3 s, and the occlusal forces on both sides and habitual chewing side were calculated using a dental prescale. Regression analysis was performed by sex with occlusal forces on both sides and habitual chewing side as the dependent variable and age as the independent variable. In addition, all subjects were divided into three groups: young group (20-39 years), middle group (40-59 years), and old group (60 years and over), and the occlusal forces on both sides and habitual chewing side were compared among the three groups. The occlusal forces did not differ from 20 to 60 years old for both males and females, and the occlusal forces gradually decreased after 60 years old. The curve of the polynomial equation was the most suitable. The occlusal forces on both sides and the habitual chewing side were similar in the young and middle groups, and the values of the old group were significantly smaller than those of the other two groups. From these results, it was suggested that the occlusal force of adults with natural dentition does not differ from 20 to 60 years old and can be represented by a curve of a cubic polynomial, and it significantly decreases after 60 years old.

Oral Health Promotion under the 8020 Campaign in Japan-A Systematic Review

(1) Background: The aim of this study is to review the benefits of the 8020 Campaign since its inception. (2) Methods: We followed the PRISMA guideline and collected information regarding the 8020 Campaign through online database searches. (3) Results: Twenty-five studies met the inclusion criteria and were eligible for analysis. The main outcomes of the 25 included studies were reviewed. The quality evaluation demonstrated a range of studies showing a credible relationship between masticatory function, number of teeth, salivary secretion, frequent dental check-ups, and general health concerns. Due to the risk of bias, publication bias, and indirectness, 22 studies were considered that only had "fair" quality. (4) Conclusions: The 8020 Foundation funded several of the studies, and other research papers noted the 8020 Campaign in their papers, however there were no clear explanations for any direct relationship between their findings and the 8020 Campaign. As a result, evidence for the direct effectiveness and benefits assessment of the 8020 Campaign positive outcomes were compromised by confounding social and economic variables over the 30-year period. To fully elucidate how improvement in Japan's oral health was directly related to the 8020 Campaign, a more informed and systematic explanation of the campaign's structure and activities is required.

Gender and age group modified association of dental health indicators with total occlusal force among Korean elders

BACKGROUND

This study aimed to investigate the distribution of objective total occlusal force (TOF) and its association with dental health indicators: dental status, number of natural teeth (NT), natural and rehabilitated teeth, natural posterior teeth (NT-Post), and natural and rehabilitated posterior teeth among Korean elders after controlling for various confounders encompassing socio-demographic factors, behavioral factors and health/oral health factors.

METHODS

This cross-sectional study recruited 551 elders from the Sungbook-Gu health education cohort. TOF was measured using Prescale II as an outcome variable. Dental health indicators assessed by dentists were the main explanatory variables. Analysis of covariance and multivariable linear regression models were applied to evaluate the adjusted association of dental health indicators with TOF. Gender and age group stratified analyses were also applied.

RESULT

TOF was higher in dentate elders than denture wearers in males and younger elders. The adjusted mean of TOF and standard error was 464.24 ± 17.15 N for dentate elders, 297.15 ± 28.85 N for partial denture wearers, 280.42 ± 47.71 N for complete denture wearers. Among all dental health indicators, NT-Post showed the highest association with TOF (partial r = 0.330, p < 0.001, R2 = 0.15), followed by NT (partial r = 0.329, p < 0.001, R2 = 0.16). Older elders highlighted the association of NT (partial r = 0.37, p < 0.001, R2 = 0.18). Males decreased the association of NT (partial r = 0.30, p < 0.001, R2 = 0.20) and NT-Post (partial r = 0.29, p < 0.001, R2 = 0.20).

CONCLUSION

TOF was significantly associated with dental health indicators, and its association was modified by sex and age group.

The Effects of Wearing a Removable-Partial-Denture on the Bite Forces: A Cross-Sectional Study

Background: Removable partial dentures are a frequently used prosthetic treatment in the elderly population, but different types or RPDs might guarantee different chewing capabilities. In many studies, the relationship between chewing and aging has been reported and it has been shown that efficient chewing can improve the overall quality of life. Objectives: In the present study, the relationship between maximum bite force (MBF) and RPDs was studied. A relationship between the body mass index (BMI) and the type of prosthesis was also analyzed. Methods: 240 elderly patients, 120 males and 120 females, with bilateral posterior edentulism (class 1 of Kennedy classification) who had been wearing an RPD for at least a year, were recruited. Patients were divided into two groups: Group 1: male (n = 60) and female (n = 60) patients with bilateral edentulous areas located posterior to the remaining natural teeth and natural teeth in the opposite dental arch. Group 2: male (n = 60) and female (n = 60) patients with maxillary and mandibular bilateral edentulous areas located posterior to the remaining natural teeth. Their Body Mass Index (BMI) and Maximum bite force (MBF) were measured and compared according to the material and design of their RPD. Results: In both Groups, patients wearing cobalt-chrome alloy RPDs (Co-Cr-RPD) (Group 1: 20.25 ± 6.7 MBF, p < 0.001; Group 2: 16.0 ± 5.7 MBF, p < 0.001) had an increased MBF when compared to polymethylmethacrylate RPD (PMMA-RPD) (Group 1: 12.9 ± 3.36 MBF; Group 2: 10.4 + 2.8 MBF), and Valplast RPD (V-RPD) (Group 1: 14.3 ± 4.7 MBF; Group 2: 11.3 ± 3.4 MBF) users. There were no significant differences in bite force between patients wearing PMMA-RPD and V- RPD in both Groups. Patients in Group 2 showed a lower MBF than those in Group 1 (Group 1: 16.05 ± 6.13 MBF; Group 2: 12.6 ± 4.84 MBF; p < 0.001). Conclusions: A reduction in chewing force can lead to choosing softer foods for nutrition, which can lead to an increase in BMI. Our results show that only CoCr-RPD wearers were able to chew consistent food, whereas PMMA- RPD and V-RPD, due to the properties of the materials, their instability, and the possibility of causing pain during mastication, determined a limitation in the choice of food for many of the participants.

Gender differences in masticatory function in elderly adults with natural dentition

The purpose of this study was to clarify the presence or absence of gender differences in masticatory function in elderly adults with completely natural dentition. Fifty-six elderly adults aged 65 years and older (elderly group) and 60 young adults in their 20-40 s (young group) with natural dentition participated in this study. The maximum occlusal force on the habitual chewing side was measured using dental prescale. Next, the amount of glucose extraction when subjects chewed a gummy jelly on their habitual chewing side for 20 s was measured. The maximum occlusal force and masticatory performance in the elderly and young groups were compared between males and females. The relationship between the maximum occlusal force and masticatory performance was also investigated. The maximum occlusal force in the elderly and young groups was larger in males than in females, and the difference was significant. The amount of glucose extraction in the elderly and young groups was higher in males than in females, and the difference was significant. Regarding the relationship between the maximum occlusal force and the amount of glucose extraction, there was a significant positive correlation. These results suggest that there are gender differences in the masticatory function of the elderly adults with completely natural dentition, and these differences need to be noted in the evaluation of masticatory function.

Masticatory Force in Relation with Age in Subjects with Full Permanent Dentition: A Cross-Sectional Study

Masticatory performance is directly correlated with masticatory muscle work to grind and cut the food. Chewing efficacy is decisive to eating a variety of foods needed maintain general health status at all ages. Older people have oral problems that get worse with age. Elders have more pathologies such as periodontal diseases, caries, tooth loss and inadequate dental prostheses than younger subjects. Objectives: to investigate the correlation between masticatory bite force (MBF) and body mass index (BMI) vs. aging and sex. Methods: This study was performed on 426 subjects (213 females plus 213 male) assigned into five different groups by age. Group “A” aged from 20 to 35 years; group “B” aged 45–59 years; group “C” aged 60–69 years; group “D” aged 70–79 years; and group “E” aged more than 79 years. Results: There were not statistically significant differences in right-side MBF versus left-side MBF. The differences between sex were statistically significant with a stronger bite in males than females (p < 0.05). At the same time, younger subjects had a stronger bite than elders (p < 0.05). In group “E”, more corpulent subjects (BMI > 25) had an MBF higher than less corpulent subjects (BMI < 25, p < 0.05). The analysis of mean MBF showed a statistically significant difference within all groups stratified by BMI with mean values inversely proportional with age (p < 0.001). Conclusion: The results in our study confirm data from many scientific papers. The importance of the present paper was to correlate data between and within a large sample with a wide range of ages. Our sample subjects had a 31%–33% decrease in MBF from group “A” to group “E” group, but they all had full permanent dentation and they preserved a valid MBF.

Evaluation of occlusal force and masticatory performance in elderly adults with natural dentition unaffected by occlusal support

PURPOSE

This study aimed to clarify whether occlusal force and masticatory performance reduced in elderly adults and whether these parameters were affected by age.

METHODS

Seventy-eight elderly adults (elderly group) and 76 young adults (control group) with natural dentition were asked to maximally clench for 3 s, and occlusal force was calculated. The amount of glucose extraction after chewing a gummy jelly was measured as the parameter for masticatory performance. Occlusal force and masticatory performance were compared between the elderly and control groups. The correlation between age and occlusal force and between age and masticatory performance was also investigated.

RESULTS

Occlusal force was significantly smaller in the elderly group (P < 0.05). Masticatory performance was lower in the elderly group, but this difference was not statistically significant. No significant correlation was observed between age and occlusal force in the control group, but a negative correlation was found in the elderly group (P < 0.05). No significant correlation was found between age and masticatory performance in either group.

CONCLUSION

Occlusal force was affected by age and reduced significantly, whereas masticatory performance was not affected by age and was maintained in elderly adults.

Bite Force in Elderly with Full Natural Dentition and Different Rehabilitation Prosthesis

(1) Background: This study aimed to investigate maximum bite force (MBF) in elderly patients with natural full dentition (FD), patients rehabilitated with Traditional Complete Dentures (CD), with overdentures (IRO) and edentulous patients (ED). We also tested whether MBF changes are associated with gender, age of the patients and body mass index (BMI) as result of altered food; (2) Methods: Three hundred and sixty-eight geriatric patients were included. We studied two types of prostheses: (a) IRO with telescopic attachments. (b) CD (heat polymerized polymethyl methacrylate resin). The MBF was measured using a digital dynamometer with a bite fork; (3) Results: We found that MBF is higher in males than females, regardless of teeth presence or absence (p < 0.01). In patients with CD or IRO, there are no differences between males and females; prostheses improve MBF compared to edentulous patients (p < 0.0001) and this effect is greater with IRO prostheses (p < 0.0001); the chewing force of FD subjects remains greater (p < 0.0001); there are no differences among chewing strength based on different BMI categories, although FD subjects have a reduced incidence of obesity; there is a significant negative correlation between MBF and age (p = 0.038; R = 0.145), and no correlation between MBF and BMI; (4) Conclusions: This study showed that MBF improves more in patients using IRO prostheses, although not reaching the MBF of FD subjects. MBF does not correlate with BMI, although we found increased percentages of obesity in edentulous subjects or those with prostheses. Thus, old people wearing prostheses require special attention by a nutritionist to avoid risk of malnutrition.

A Cross-Sectional Study of Age-Related Changes in Oral Function in Healthy Japanese Individuals

BACKGROUND

Oral function deterioration is related to a variety of factors, including aging, decline in activities of daily living, malnutrition, and cognitive decline. This cross-sectional study examined the effects of aging on oral function in healthy individuals.

METHODS

A retrospective study was conducted on 175 healthy, independent patients aged 40-89 years, without dementia and with ≥20 teeth, who visited a local dental clinic in Japan. Patients were compared with 92 university students aged 20-29 years. The seven criteria proposed by the Japanese Society of Gerodontology to diagnose "oral hypofunction" were observed and statistically analyzed.

RESULTS

Compared with those in the control group, the degree of tongue coating was increased in the group aged over 80 years, occlusal force was decreased in the group aged 70-79 years, tongue motor function was decreased in the groups aged 60-69 years and older, and tongue pressure was decreased in the groups aged 70-79 years and older.

CONCLUSIONS

Healthy, independent individuals maintained several oral function criteria across aging, including oral mucosal wetness, occlusal force, lip motor function, masticatory function, and swallowing function. Tongue motor function and tongue pressure decreased with aging, indicating that these may be rehabilitation targets.

Multiple External Root Resorption of Teeth as a New Manifestation of Systemic Sclerosis-A Cross-Sectional Study in Japan

BACKGROUND

Multiple external root resorption (MERR) has been reported in systemic sclerosis (SSc) patients in Japan and Spain. To establish whether MERR is a new manifestation, we investigated the prevalence of MERR and systemic and oral manifestations to be associated with MERR in patients with SSc.

METHODS

Root resorption was detected by dental X-rays, panoramagraphy or cone beam computed tomography (CBCT). The prevalence of systemic and oral manifestations was examined by rheumatologists and dentists, respectively. Autoantibodies were investigated using laboratory tests.

RESULTS

MERR was detected in four out of the 41 patients (9.8%) who participated in the present study. The prevalence of digital ulcers was significantly higher in patients with MERR (MERR vs non-MERR, 75% vs 16.2%, p < 0.05), whereas that of other systemic manifestations was not. The prevalence of face skin sclerosis (100% vs 10.8%, p < 0.01), calcinosis at the facial region (75% vs 0%, p < 0.01), limited mouth opening (75% vs 18.9% p < 0.05), temporomandibular disorder symptoms (50% vs 2.7%, p < 0.05), and tongue rigidity (75% vs 2.7%, p < 0.05) was significantly higher in patients with MERR.

CONCLUSION

SSc patients with MERR had highly homogenous maxillofacial manifestations. Further clinical and basic studies are needed to elucidate the mechanisms underlying MERR in SSc patients.

Fatigue and microgap behaviour of a three-unit implant-fixed dental prosthesis combining conventional and dynamic abutments

This is an in vitro study composed by a fatigue test followed by an optical microscopy analysis. Dynamic abutments concept, recently introduced on screw-retained implant dental prosthesis, consists on the screw channel customisation according to the individual needs of each rehabilitation. Geometry and tightening torque differences advise the assessment of their mechanical performance. Clarify whether the combination of dynamic and conventional abutments in a three-unit implant-fixed prosthesis has detrimental effects either on the mechanical performance under cyclic loading or on the implant-abutment microgap dimensions. The fatigue test was performed in agreement with the ISO standard 14801. Then on the samples that resisted 5 million cycles, the implant-abutment microgap was measured on dynamic and conventional abutments using optical microscopy. Two unloaded samples were used as control group. The samples supported a load of 1050 N. The implant-abutment microgap measurement did not show statistically significant differences (p = .086) between loaded and unloaded groups, but the loaded conventional abutments showed a significant lower implant-abutment microgap (p = .05) than the loaded dynamic abutments. The combination of conventional and dynamic abutments do not seem to produce a decrease in fatigue resistance to a level below the mastication forces or an increase in the joint dimensions.

Reparative bone-like tissue formation in the tooth of a systemic sclerosis patient

AIM

To report a case of reparative bone-like tissue formation in the tooth of a patient with systemic sclerosis.

SUMMARY

A 58-year-old Japanese female patient with systemic sclerosis was referred because of tooth fracture. Cone beam computerized tomography (CBCT) revealed multiple root resorption and the unclear transition from alveolar bone to root profile. A sample from a fractured tooth was analysed histologically. Haematoxylin and eosin-stained sections revealed the irregular replacement of pulp and dentine by bone-like tissue. Calcinosis was noted in various parts of the body and a histological analysis identified it as dystrophic calcification on sclerosed fibrous connective tissue. Bite force and the occlusal area were markedly weaker than the means for female of the same age.

KEY LEARNING POINTS

CBCT may be more useful than dental radiography for diagnosing multiple root resorption in systemic sclerosis patients. When systemic sclerosis patients have calcinosis, their root status must be examined carefully. When root resorption is present in systemic sclerosis patients, reparative bone-like tissue formation in teeth needs to be taken into account prior to the initiation of dental treatment.

Relationship Between Frailty and Oral Function in Community-Dwelling Elderly Adults

OBJECTIVES

To determine the standard values of and age-related changes in objective oral function of healthy older people; compare oral function of robust, prefrail, and frail older people; and determine the association between oral function and frailty.

DESIGN

Cross-sectional analysis.

SETTING

General community.

PARTICIPANTS

Elderly adults (≥65) from the Obu Study of Health Promotion for the Elderly were included and assigned to the robust, prefrail, and frail groups (N = 4,720).

MEASUREMENTS

Each participant underwent detailed physical testing to assess frailty. The frailty phenotype was defined according to the presence of limitations in three or more of the following five domains: mobility, strength, endurance, physical activity, and nutrition. The numbers of present teeth and functional teeth were counted, and occlusal force, masseter muscle thickness, and oral diadochokinesis (ODK) rate were measured, along with sociodemographic and functional status, comorbidities, and blood chemistry.

RESULTS

The number of present teeth, occlusal force, masseter muscle thickness, and ODK rate decreased with age. The frail group had significantly fewer present teeth (women aged ≥70), lower occlusal force (women aged ≥70; men aged ≥80), lower masseter muscle thickness, and lower ODK rate than the robust group. Multivariate analysis indicated that age, Geriatric Depression Scale score, skeletal muscle mass index, Mini-Mental State Examination score, hypertension, diabetes mellitus, albumin and triglyceride levels, and oral function were significantly associated with frailty.

CONCLUSION

Age-related differences in oral function were found in older adults. Moreover, frail older individuals had significantly poorer oral function than prefrail and robust individuals. The risk of frailty was associated with lower occlusal force, masseter muscle thickness, and ODK rate.

Factors associated with self-rated oral health among community-dwelling older Japanese: A cross-sectional study

OBJECTIVES

A cross-sectional study was carried out to investigate the determinants of self-rated oral health among community-dwelling older people in Japan.

METHODS

The participants were 897 (357 men and 540 women) aged 65 years and over who participated in a comprehensive geriatric health examination, which included an oral examination, a face-to-face interview assessing cognitive function, questionnaires regarding depressive symptoms and functional capacity, and a medical examination. The oral examination measured indices of oral health status: number of present teeth, number of functional teeth, occlusal force and amount of resting saliva. Multiple logistic regression analyses were carried out to determine the factors associated with poor self-rated oral health.

RESULTS

The mean age of the participants was 73.5 ± 5.0 years. The prevalence of poor and rather poor self-rated oral health was 11.5% and 29.5%, respectively. Multiple logistic regression analyses showed that the number of present teeth (odds ratio [OR] 0.97, 95% confidence intervals [CI] 0.95-0.99), difficulty in mastication (OR 3.20, CI 2.18-4.70), presence of xerostomia (OR 1.43, CI 1.02-2.01), total score on the MoCA-J (OR 1.06, CI 1.01-1.11), and reduction in frequency of leaving the house (OR 1.64, CI 1.12-2.41) were significantly associated with poor self-rated oral health.

CONCLUSIONS

The present results suggested that self-rated oral health was a significant factor in oral health status as well as overall well-being among community-dwelling older Japanese people.

Effectiveness of an oral health educational program on community-dwelling older people with xerostomia

AIM

The purpose of the present study was to evaluate the changes in oral health and function through an oral health educational program for the independent older people with xerostomia.

METHODS

Community-dwelling older people with xerostomia aged over 65 years who participated in a preliminary comprehensive health survey in 2011 were recruited for the educational program. A total of 47 participants were randomly assigned into two groups, the intervention group (n = 26) and the control group (n = 21). The intervention group attended a 90-min oral health education program every 2 weeks for 3 months. The program consisted of oral hygiene instruction, facial and tongue muscle exercise, and salivary gland massage. The control group was provided only general information about oral health. The assessments of oral function, such as oral diadochokinesis of articulation, swallowing, taste threshold and salivary flow rate, were carried out before and after 3 months with or without intervention.

RESULTS

A total of 38 participants (21 of intervention group and 17 of control group) completed the study protocol. In the intervention group, resting salivation significantly improved after the program. The second and third cumulated Repetitive Saliva Swallowing Test times significantly improved in the intervention group. The threshold for bitterness significantly lowered in the intervention group, whereas the sour threshold significantly heightened in the control group after 3 months (P < 0.05).

CONCLUSIONS

The present study suggests that the educational program targeting oral function improvement is effective among the independent older population.

In vivo evaluation of occlusalcontact area and maximum bite force in patients with various types of implant-supported prostheses

OBJECTIVE

To determine the effects of various implant retained and/or supported prostheses on number of occlusal contacts (NOC), occlusal contact area (OCA)and maximum bite force (BF).

PATIENTS AND METHODS

In total, 56 patients were included in the study; five test groups and two control groups. The patients in the treatment groups received implant-supported/retained prosthesis; over-dentures retained with two individual attachments in occlusion with complete denture, with four individual attachments in occlusion with complete denture, with four individual attachments in occlusion with fixed partial dentures or natural dentition, 6-implant retained fixed bridges in occlusion with natural dentition and 8-implant retained fixed bridges in occlusion with natural dentition. The patients in control group 1 were wearing conventional complete maxillary and mandibular dentures, whereas in control group 2 they had fixed full-arch porcelain-fused to metal restorations prostheses for both arches. Dental Pre-scale was used measure the NOC, BF and OCA.

RESULTS

There was no statistically significant difference between the treatment and control groups, among the groups with regards to NOC. OCA demonstrated different results among the removable and fixed reconstruction groups. With regards to BF, removable dentures supported with four implants showed higher bite force values than controls and two implant over-dentures. Also, a fixed reconstruction using eight implants showed higher BF values than a fixed reconstruction using six implants.

CONCLUSION

Use of implants for removable dentures and fixed reconstructions improve occlusal contact area and bite force.

New approaches to dental occlusion: a literature update

Because the study of occlusion is a basic area in dentistry, its components, physiology and integration with the stomatognathic system (SS) have been the subject of interest in the scientific literature. However, the focus given to this issue has changed substantially. Currently, new approaches have been proposed in order to update concepts and to demonstrate the full integration and functionality of this system within the human body. With this approach, the authors proposed the following literature review aimed at gathering recent papers (published from 2000 to 2010) with innovative study design, methodology and/or results. The authors' intention is to show the main trends in the study of occlusion and the SS. The literature review was conducted in the PubMed database, using initially the term "dental occlusion" as a key-word. As items of interest were found, papers were grouped by categories according to their main subject matter. Forty-seven articles were selected and the main categories obtained were: 1. functional magnetic resonance imaging (fMRI); 2. brain activation; 3. masticatory/occlusal function; 4. body function and physical performance; 5. osseoperception; 6. finite element models; and 7. occlusion and pain. Observing the current literature, the authors found that recent studies present different methodologies for the study of occlusion. These studies have allowed scientists to obtain detailed information about the physiology of occlusion and the SS, as well as about its integration in the body. Research in this area should be continued in order to clarify, in detail, the role of each component of the SS and its interaction with human physiology.

Masseter muscle tension and chewing ability in older persons

AIM

Mastication is an important function to maintain, not only for oral health, but also for quality of life. An easy-to-use method to evaluate the chewing ability of elderly people in any environment is necessary. Few studies have discussed the effectiveness of the masseter muscle by palpation. The purpose of this study was to clarify the availability of masseter muscle tension assessment methods by investigating its relationship with oral health status, and comparing it with other methods of assessing chewing ability.

METHODS

This cross-sectional study was carried out with 547 community-dwelling elderly subjects (246 men and 301 women; mean age 73.8 ± 6.2 years) who participated in a comprehensive annual geriatric health examination in 2010 at Kusatsu, Gunma, Japan. Chewing ability was evaluated by masseter muscle tension palpation, differences of masseter muscle thickness, occlusal force, self-reported chewing ability, and the number of remaining and functional teeth. Masseter muscle thickness was measured by ultrasonography.

RESULTS

Masseter muscle thickness and occlusal force showed significant differences between males and females. The strength of masseter muscle tension palpation was significantly associated with men's occlusal force, masseter muscle thickness, the number of remaining and functional teeth, and self-reported chewing ability (P < 0.05). Female participants showed a significant association with occlusal force, masseter muscle thickness, the number of remaining teeth, and self-reported chewing ability and results of palpation (P < 0.05).

CONCLUSION

These results showed that the palpation of masseter muscle tension is a reliable and easy-to-use method to evaluate the chewing ability of elderly people.

Propofol dose-dependently increases bite force during sedation

PURPOSE

The purpose of this study was to investigate the dose-dependent effects of propofol on cognitive function and muscle power as well as vital functions.

MATERIALS AND METHODS

Twenty volunteers participated in this study. Each subject underwent 2 experiments in a randomized crossover manner (propofol group and control group). After control data were obtained, propofol at predicted effect site concentrations of 0.4, 0.8, 1.2, 1.6, and 2.0 μg/mL was infused in the propofol group using a target controlled infusion system. Heart rate, noninvasive blood pressure, arterial oxygen saturation, respiratory rate, and bispectral index value were monitored. Observer's assessment of alertness/sedation and the correct answer rate of the Stroop color word test were assessed. Muscle power, grip strength and bite force were measured.

RESULTS

In the propofol group, the bispectral index value and observer's assessment of alertness/sedation scale dose-dependently reduced. At the predicted effect site propofol concentration of 2.0 μg/mL, 6 subjects became unconscious. The correct answer rate of Stroop color word test reduced at the predicted effect site propofol concentration of 1.6 and 2.0 μg/mL. Grip strength slightly increased at the predicted effect site propofol concentration of 1.2 μg/mL or less, and bite force dose-dependently increased. At the predicted effect site propofol concentration of 2.0 μg/mL, both muscle powers began to decrease. Bite force dose-dependently increased and reached the maximum at the predicted effect site propofol concentration of 1.6 μg/mL.

CONCLUSION

Although the detailed mechanisms are unknown, propofol dose-dependently increases bite force during minimal and moderate sedation.