Oral environmental factors affecting number of microbes in saliva of complete denture wearers

Time spent away from bed is associated with oral hygiene and oral function: A cross-sectional and multi-institutional study

BACKGROUND

Spending time away from bed is important in older adults. Not doing so can lead to functional decline rapidly.

OBJECTIVE

To investigate the association between oral function and time spent away from bed in older adults living in nursing homes.

METHODS

We enrolled 748 adults aged ≥65 years across eight nursing homes between April 2022 and March 2023. 'Problems with oral hygiene' and 'problems with oral function' were the dependent variables in the multiple regression analyses to determine their association with time spent away from bed.

RESULTS

We selected 304 participants (76 men; mean age, 86.3 ± 7.5 years) and divided them into three groups: group S (< 4 h), group M (4 to < 6 h) and group L (≥ 6 h), with 28, 23 and 253 participants, respectively. Comparison of the characteristics between the groups demonstrated significant differences in the Barthel index (p < .001), time spent away from bed (p < .001), history of aspiration pneumonia (p < .001), confirmation of meals and food forms (p = .010), problems with oral hygiene (p = .014), and problems with oral function (p = .002). Based on multiple regression analyses, 'problems with oral hygiene' (p < .001) and 'problems with oral function' (p < .001) were significantly associated with time spent away from bed.

CONCLUSIONS

The time spent away from bed was significantly associated with both oral hygiene and function in older adults, suggesting the importance of extending the time that older adults spend away from bed.

Developing tongue coating status assessment using image recognition with deep learning

PURPOSE

To build an image recognition network to evaluate tongue coating status.

METHODS

Two image recognition networks were built: one for tongue detection and another for tongue coating classification. Digital tongue photographs were used to develop both networks; images from 251 (178 women, 74.7±6.6 years) and 144 older adults (83 women, 73.8±7.3 years) who volunteered to participate were used for the tongue detection network and coating classification network, respectively. The learning objective of the tongue detection network is to extract a rectangular region that includes the tongue. You-Only-Look-Once (YOLO) v2 was used as the detection network, and transfer learning was performed using ResNet-50. The accuracy was evaluated by calculating the intersection over the union. For tongue coating classification, the rectangular area including the tongue was divided into a grid of 7×7. Five experienced panelists scored the tongue coating in each area using one of five grades, and the tongue coating index (TCI) was calculated. Transfer learning for tongue coating grades was performed using ResNet-18, and the TCI was calculated. Agreement between the panelists and network for the tongue coating grades in each area and TCI was evaluated using the kappa coefficient and intraclass correlation, respectively.

RESULTS

The tongue detection network recognized the tongue with a high intersection over union (0.885±0.081). The tongue coating classification network showed high agreement with tongue coating grades and TCI, with a kappa coefficient of 0.826 and an intraclass correlation coefficient of 0.807, respectively.

CONCLUSIONS

Image recognition enables simple and detailed assessment of tongue coating status.

Associations of oral health status and swallowing function with cognitive impairment in the aging population: a cross-sectional study

BACKGROUND

The purpose of this study was to investigate the relationships of oral health status and swallowing function with cognitive impairment in community-dwelling older adults from Changsha, Hunan Province, China.

METHODS

In this cross-sectional study, we analyzed the data of 215 participants aged ≥ 50 years which were retrieved from the Xiangya and Panasonic mild cognitive impairment (MCI) Study, a community-based study conducted among the residents of the urban areas of Hunan province in China. Demographic information of all participants was collected. We determined oral function by evaluating oral hygiene, oral dryness, occlusal force, tongue pressure, chewing function, swallowing function, remaining teeth number, and other indicators. The mini-mental state examination (MMSE) was used to screen for cognitive function. The relationship between each oral function evaluation item and cognitive function was investigated using correlation analysis. The associations between oral health status and swallowing function with cognitive impairment were inferred using multiple regression analysis.

RESULTS

The general characteristics of participants showed statistically significant correlation coefficients in number of teeth remaining (p = 0.003) and number of teeth lost (p < 0.0001). Almost half of the 25 participants (48%) were aged from 70-80 years. Only 25 older adults (11.6% of the participants) were determined to have cognitive impairment by MMSE sores less than 24. Tongue pressure in male participants was the only significant independent variable that was associated with cognitive impairment (p = 0.01971). The results indicate that male participants with lower MMSE scores had a relative deficiency in tongue pressure.

CONCLUSIONS

In this cross-sectional study, the oral health status and swallowing function of participants were in relatively good condition and showed low correlations with cognitive impairment. However, lower tongue pressures were associated with lower MMSE scores in males, indicating it could serve as a novel oral function index for evaluating cognitive impairment.

Study on syndrome rules of stagnated heat in liver and stomach of non-erosive reflux disease based on microecology of tongue coating

INTRODUCTION

At present, the pathogenesis of non-erosive reflux disease (NERD) is still unclear, and proton pump inhibitors are the main treatment drug. However, the effect is limited. Traditional Chinese medicine treatment of NERD has advantages. Stagnated heat in liver and stomach syndrome is the most important traditional Chinese medicine syndrome type of this disease. Tongue diagnosis is an important basis for the diagnosis of stagnated heat in liver and stomach syndrome. The microecology of tongue coating suggests the occurrence and development of disease. The purpose of this study aims to clarify the regular changes of tongue coating microecology in stagnated heat in liver and stomach syndrome of NERD.

METHODS AND ANALYSIS

This is a cross-sectional clinical trial. This study is divided into NERD stagnated heat in liver and stomach syndrome group, qi stagnation, and phlegm obstruction syndrome control group and normal control group, with 20 cases in each group. Tongue coating samples will be collected from 3 groups, and 16SrRNA gene sequencing technology will be used to detect the genome of tongue coating flora in patients with NERD with stagnated heat in liver and stomach syndrome, control group with qi stagnation and phlegm obstruction syndrome and normal control group. The main outcome measures are the distribution, diversity, and richness of the tongue flora in patients and healthy controls.

DISCUSSION

The results of this study will clarify the internal relationship between NERD stagnated heat in liver and stomach syndrome and the microecological changes in tongue coating.

An innovative oral management procedure to reduce postoperative complications

Background

Numerous studies have shown that improving oral hygiene contributes to a reduction in the risk of postoperative complications in patients with head and neck cancer, cardiac disease, and esophageal cancer. However, the beneficial standard for oral management procedures during the perioperative period has not yet been established. Therefore, our aim was to determine whether or not their innovative oral management intervention contributed to a reduction in postoperative complications in lung cancer.

Methods

We performed a retrospective analysis of medical records of patients who underwent lung cancer surgery with lobectomy and pneumonectomy at Kyorin University Hospital. Patients were divided into 2 groups: a perioperative oral management intervention group that underwent lung cancer surgery from April 2016 to March 2018 (n = 164), and a control group without oral management that underwent surgery from April 2014 to March 2016 (n = 199). In particular, our oral management procedure emphasized oral mucosa stimulation to induce saliva discharge as in gum chewing, rather than simply using teeth brushing to reduce oral microbiome. Therefore, our oral management procedure is different from traditional oral care.

Results

This study demonstrated that our oral management practice was associated with a decline in the occurrence of postoperative pneumonia (odds ratio, 0.184; 95% CI, 0.042-0.571; P = .009), postoperative hospital stay duration (β coefficient, −4.272; 95% CI, −6.390 to −2.155; P < .001) and Clavian-Dindo classification grade II or above (odds ratio, 0.503; 95% CI, 0.298-0.835; P = .009).

Conclusions

We propose an innovative new strategy using their unique oral management procedure to reduce postoperative complications resulting from pulmonary resection.

An Interprofessional Approach to Oral Hygiene for Elderly Inpatients and the Perception of Caregivers Towards Oral Health Care

OBJECTIVE

The objective of this study was to investigate the effect of an interprofessional oral hygiene support program for elderly inpatients and the perception of caregivers of the elderly towards oral health care.

MATERIALS AND METHODS

Participants comprised 37 elderly inpatients requiring nursing care (17 males, 20 females; mean age, 83.3 ± 4.9 years) and 29 registered nurses who participated in the interprofessional oral health care support program as a caregiver (4 males, 25 females; mean age, 45.2 ± 10.3 years). In this program, inpatients received daily oral cleaning by registered nurses based on each patient's oral health care plan. The number of microbes on the tongue surface of the inpatients was measured once a week for 12 weeks. Additionally, as an investigation of the perception of the caregivers towards oral health care, a questionnaire about the required frequency and duration for oral cleaning was conducted with registered nurses before and after the program to investigate the perception of the caregivers towards oral health care.

RESULTS

Significant differences were observed in the number of microbes on the tongue surface between baseline and at every measurement after the beginning of this program, except for the first week. The mean required frequency and duration for oral cleaning by registered nurses at baseline were 1.5 ± 0.8 times and 3.8 ± 2.2 minutes, whereas those after the program were 2.7 ± 0.7 times and 5.8 ± 2.9 minutes, respectively.

CONCLUSION

Implementation of the program decreased the number of microbes on the tongue surface of the elderly inpatients and improved the perception of their caregivers towards oral health care.

Methicillin-Resistant Staphylococcus aureus in the Oral Cavity: Implications for Antibiotic Prophylaxis and Surveillance

The oral cavity harbors a multitude of commensal flora, which may constitute a repository of antibiotic resistance determinants. In the oral cavity, bacteria form biofilms, and this facilitates the acquisition of antibiotic resistance genes through horizontal gene transfer. Recent reports indicate high methicillin-resistant Staphylococcus aureus (MRSA) carriage rates in the oral cavity. Establishment of MRSA in the mouth could be enhanced by the wide usage of antibiotic prophylaxis among at-risk dental procedure candidates. These changes in MRSA epidemiology have important implications for MRSA preventive strategies, clinical practice, as well as the methodological approaches to carriage studies of the organism.

Factors associated with the number of microorganisms on the tongue surface in patients following acute stroke

BACKGROUND

Oral hygiene management of patients with acute stroke is important for preventing aspiration pneumonia and ensuring oral intake. The tongue coating score can be useful for evaluating the oral hygiene level since it reflects the microorganism number on the tongue surface in elderly patients. However, the relationship between the number of oral microorganisms and the tongue coating score in patients with acute stroke remains unclear.

OBJECTIVES

We aimed to investigate the relationships between the microorganism number on the tongue surface and oral factors, including tongue coating score, tongue surface moisture level and tongue function.

METHODS

This cross-sectional study enrolled 73 patients with acute stroke who were hospitalised at an acute care hospital and underwent dental intervention. Potential explanatory factors, including sex, age, Glasgow Coma Scale score, tongue coating score, tongue surface moisture level, nutrition intake method, number of functional teeth and tongue function, were evaluated. Logistic regression analysis determined their association with the microorganism number on the tongue surface.

RESULTS

The tongue coating score (odds ratio: 1.31) and tongue surface moisture level (odds ratio: 1.10) were significantly associated with increased microorganism numbers on the tongue surface.

CONCLUSION

The tongue coating score, which reflects the actual number of microorganisms on the tongue surface, could be an effective tool for evaluating oral hygiene level in patients with stroke. Moreover, reducing oral microorganisms in saliva through oral hygiene management, including removing the tongue coating, could contribute towards the prevention of aspiration pneumonia.

Evaluation of Factors Associated with Tongue Coating Status in Elderly with Care Needs

The tongue surface in older people requiring nursing care is often coated with a layer believed to comprise, keratinized products of degeneration, food residue, bacteria, and leukocytes attached to the tongue papillae. Which factors affect the status of this tongue coating remain to be elucidated, however. The purpose of this study was to evaluate factors related to tongue coating status in older people requiring nursing care. The study participants comprised 41 individuals admitted to special nursing homes for the elderly. After undergoing tooth brushing and tongue cleaning by the facility staff, the participants were required to refrain from oral cleaning until evaluation of tongue coating status, which was performed just after lunch. The moisture level of the tongue surface was measured and total number of oral microbes determined. Food type, care level, and sex were determined by a questionnaire given by the attending nurses. Correlations between the tongue coating status and various factors were analyzed using Spearman's rank correlation coefficient. The participants were divided into 2 groups according to the median value of the tongue coating status. Factors related to tongue coating were analyzed using binomial logistic regression analysis (α=0.05). Tongue coating status showed a significant correlation with the total number of oral microbes on the tongue surface (r_S=0.449, p=0.003), type of food (r_S=0.388, p=0.012), and care level (r_S=-0.308, p=0.050). Logistic regression analysis revealed that the food type of the side dish significantly affected tongue coating status. These results showed a correlation between tongue coating status and type of food of the side dish in older people requiring nursing care.

Clinical observation of tongue coating of perioperative patients: factors related to the number of bacteria on the tongue before and after surgery

Background

Increased amount of tongue coating has been reported to be associated with increased bacteria count in the saliva and aspiration pneumonia in elderly people. However, the implications of tongue coating for prevention of postoperative complications in patients undergoing major oncologic or cardiac surgery has not been well documented. The purpose of this study is to investigate the number of bacteria on the tongue before and after surgery and factors affecting it.

Methods

Fifty-four patients who underwent oncologic or cardiac surgery under general anesthesia at Nagasaki University Hospital were enrolled in the study. Various demographic, tumor-related, treatment-related factors, and the number of bacteria on the tongue and in the saliva were examined, and the relationship among them was analyzed by Mann-Whitney U test, Spearman rank correlation coefficient, or multiple regression.

Results

Before surgery, no significant factors were correlated with the number of bacteria on the tongue, and there were no relationship between bacteria count on the tongue and that in the saliva. On the next day after surgery, bacteria on the tongue increased, and sex, periodontal pocket depth, feeding condition, dental plaque, blood loss, and bacteria in the saliva were correlated with bacteria on the tongue by a univariate analysis. A multivariate analysis showed that feeding condition, and amount of dental plaque were correlated with the number of bacteria.

Conclusions

Increased number of bacteria on the tongue was associated with feeding condition and amount of dental plaque. Further studies are necessary to clarify the clinical significance of dental coating in perioperative oral management of patients undergoing oncologic or cardiac surgery.

Oral hypofunction in the older population: Position paper of the Japanese Society of Gerodontology in 2016

BACKGROUND

There is growing international interest in identifying the effects of ageing on oral health and on appropriate strategies for managing oral disorders. The Japanese Society of Gerodontology (JSG), as the official representative of researchers and clinicians interested in geriatric dentistry in Japan, makes several recommendations on the concept of "oral hypofunction."

AIMS

This study proposes diagnostic criteria and management strategies to reduce the risk of oral hypofunction among older people.

CONCEPTUAL FRAMEWORK

We define oral hypofunction as a presentation of 7 oral signs or symptoms: oral uncleanness; oral dryness; decline in occlusal force; decline in motor function of tongue and lips; decline in tongue pressure; decline in chewing function; and decline in swallowing function. The criteria of each symptom were determined based on the data of previous studies, and oral hypofunction was diagnosed if the criteria for 3 or more signs or symptoms were met.

CONCLUSIONS

We recommend that more evidence should be gathered from clinical studies and trials to clarify our diagnostic criteria and management strategies.

Reliability, Accuracy, and Use Frequency of Evaluation Methods for Amount of Tongue Coating

OBJECTIVE

To classify the evaluation methods for amount of tongue coating (TC) and investigate their reliability, accuracy, and frequency of use.

METHODS

Articles published from 1985 to 2015 were searched for evaluation methods for the amount of TC in PubMed and the Cochrane Library. Only clinical researches were included except protocol articles. The methods were classified according to their characteristics.

RESULTS

Finally, 113 articles were selected. The evaluation method for the amount of TC from the articles was classified into 4 types: intuitive, specificative, computerized, and weighing TC. The reliability in the intuitive and specificative methods (κ =0.33-0.92) showed varying levels among the studies. In general, the amount of TC calculated by the specificative method (Spearman's r=0.68-0.80) was more strongly related to the directly measured value than to the value estimated by the computerized method (Pearson's r=0.442). The number of articles published on this topic has increased consistently, and the specificative method was the most frequently used. Despite the higher reliability of the computerized method, it has not been widely used.

CONCLUSIONS

The high prevalence of the specificative method would continue in clinical practice because of its convenience and accuracy. However, to establish higher reliability, the limitation of the subjectivity of the assessors should be overcome through calibration training. In the computerized method, novel algorithms are needed to obtain a higher accuracy so that it can help the practitioners confidently estimate the amount of TC.

A controlled study comparing salivary osmolality, caries experience and caries risk in patients with cerebral palsy

BACKGROUND

Cerebral palsy (CP) is a permanent neurological disorder accompanied by secondary musculoskeletal masticatory disorder, with repercussion on chewing and deglutition functions. In these conditions, the liquids ingestion is compromised resulting in salivary osmolality alteration. The objective of this study was to compare salivary osmolality, caries experience and caries risk between normoreactive individuals and patients with CP.

MATERIAL AND METHODS

The participants were 4-20 years old: 52 patients with CP treated at a reference rehabilitation centre (study group, SG), and 52 normoreactive individuals (control group, CG). Saliva was collected for five minutes using cotton rolls. Following centrifugation, salivary osmolality was determined by freezing point depression osmometry. Evaluations included caries experience (DMFT index), and caries risk based on a caries-risk assessment tool (CAT). Descriptive and inferential statistics (Chi square and Student t tests) were used to compare the groups. Receiver operating characteristic (ROC) analyses were performed and the area under the ROC curve (Az) was calculated. The level of significance was set at 5%.

RESULTS

The groups were homogeneous for sex (p=0.843) and age (p=0.128). In the SG, spastic type CP was the most prevalent (80.8%), and patients showed significantly higher salivary osmolality values compared with the CG (p<0.001). No significant differences in caries experience (p=0.159) or caries risk (p=0.297) were observed. ROC curve analysis determined a salivary osmolality cutoff point of >74 for the SG and >54 for the CG in the presence of dental caries. A significant correlation was verified between salivary osmolality and the DMFT index for the SG (p≤0.05).

CONCLUSIONS

Although patients with CP showed higher salivary osmolality values, higher caries experience and caries risk were not observed compared with normoreactive individuals.

Effect of water containing organic acids on aspiration pneumonia-causative bacteria in the biofilm on the tooth surface

Background/purpose

The tooth surface is a source of oral microbes in dentulous individuals, it is difficult for elderly people requiring nursing care to perform mechanical tooth cleaning by themselves. The objective of this study was to investigate the antimicrobial effect of water containing organic acids (WOA) made by some organic acids as food additives on chemical cleaning for elderly people on aspiration pneumonia-causative bacteria in the biofilm on the tooth surface.

Materials and methods

Ninety-six specimens made from bovine incisors were divided into four groups and incubated with one of four aspiration pneumonia-causative bacteria. Each group was further divided into six subgroups according to treatment as follows: control group (DW), chlorhexidine gluconate solution group (CHX), WOA group (WOA), ultrasonic treatment in distilled water group (DW-U), ultrasonic treatment in chlorhexidine gluconate solution group (CHX-U) or ultrasonic treatment in WOA group (WOA-U). After treatment, the levels of viable microbes in the biofilm were evaluated by quantitative adenosine triphosphate analysis and compared among the six groups.

Results

For every evaluated microbe, there were significant differences between DW and WOA, and DW and WOA-U. However, there was no significant difference among the WOA, DW-U, CHX-U and WOA-U groups. These results suggested that the antimicrobial effect of WOA on microbes attached to the tooth surface was similar to that of ultrasonic cleaning.

Conclusion

WOA has an antimicrobial effect on microbes in the biofilm on the tooth surface.

Inflammatory markers in saliva as indicators of gingival inflammation in cerebral palsy children with and without cervical motor control

AIM

To evaluate the relation among gingival inflammation, salivary osmolality, levels of IL-1β, IL-6, IL-8, TNF-α, and s-IgA concentrations in children with spastic CP with or without cervical motor control in a cross-sectional study.

DESIGN

Unstimulated whole saliva and the gingival index were collected in 37 and 34 CP children with and without cervical motor control, respectively. The data were dichotomized as follows: (=0) absence of gingival inflammation and (≥0.1) presence of gingival inflammation.

RESULTS

The group without cervical control presented statistically higher mean values of salivary osmolality, s-IgA, and cytokines. In addition, statistically positive correlation between the gingival index and salivary cytokines was observed in the group with cervical control. Salivary osmolality, salivary cytokines, and s-IgA from both groups presented a significant positive correlation. Significant differences (P = 0.00336) in the values of salivary osmolality were observed between the CP individuals with (93.9 ± 32.7) and without gingival inflammation (74.4 ± 16.6). ROC analysis was performed, and values of salivary osmolality >80 indicated a sensitivity of 0.54 and a specificity of 0.79.

CONCLUSIONS

Children without cervical motor control presented a more pronounced oral inflammatory status that was characterized by higher levels of cytokines.

Inhibition of denture plaque by TiO2 coating on denture base resins in the mouth

STATEMENT OF PROBLEM

Information is lacking about antiadhesion effect of titanium dioxide (TiO₂) coating on denture base resins in the mouth.

PURPOSE

The purpose of this clinical study was to investigate the antiadhesion effect of TiO₂ coating on denture base resins.

MATERIAL AND METHODS

Ten healthy dentate participants (mean 27 ±2 years of age) participated in this study. Disks and palatal appliances were made with denture base resin. They were divided into 2 groups: a TiO₂-coated group and an uncoated group. A primer and a top coat containing TiO₂ were applied to the surfaces of the resin by means of an air spray. In the denture plaque staining test, resin disks were fixed to the retainer, placed in each participant's mouth for 3 days, and stained with a dental plaque-disclosing solution. The staining rate was calculated. The resin disks and palatal appliances were used to measure the total number of microbes. The resin specimens were placed in each participant's mouth for either 3 or 7 days and swabbed to count the total number of microbes. The chewing gum adherence test was performed both subjectively and objectively. Subjectively, each participant wearing a palatal appliance rated adherence using a visual analog scale. The objective test was performed with a chewing gum adhesion test. The staining rate, the total number of microbes, and the visual analog scale values were statistically analyzed using the Wilcoxon signed rank test, and the adhesive force was statistically analyzed using a Student t test.

RESULTS

In the denture plaque staining test, the measurement of microbes, and the resin chewing gum adherence test results, significant differences were observed between the TiO₂-coated groups and the uncoated groups.

CONCLUSIONS

TiO₂ coating of the denture base acrylic resin inhibited the adhesion of microbes, denture plaque, and highly adhesive food.

Gingivitis and salivary osmolality in children with cerebral palsy

AIM

To investigate the influence of salivary osmolality on the occurrence of gingivitis in children with cerebral palsy (CP).

DESIGN

A total of 82 children with spastic CP were included in this cross-sectional study. Oral motor performance and gingival conditions were evaluated. Unstimulated saliva was collected using cotton swabs, and salivary osmolality was measured using a freezing point depression osmometer. Spearman's coefficient, receiver operating characteristic (ROC), and multiple logistic regression analyses were performed.

RESULTS

Strong correlation (r > 0.7) was determined among salivary osmolality, salivary flow rate, visible plaque, dental calculus, and the occurrence of gingivitis. The area under the ROC to predict the influence of salivary osmolality on the occurrence of gingivitis was 0.88 (95% CI 0.81-0.96; P < 0.001). The cutoff value of 84.5 for salivary osmolality presented good sensitivity and specificity, both higher than 77%. The proportion of children presenting salivary osmolality ≤84.5 mOsm/kgH₂ O and gingivitis was 22.5%, whereas for the group presenting osmolality >84.5 mOsm/kgH₂ O, the proportion of children with gingivitis was 77.5%. Salivary osmolality above 84.5 increased the likelihood of gingivitis fivefold, whereas each additional 0.1 mL of salivary flow reduced the likelihood of gingivitis by 97%.

CONCLUSION

Gingivitis occurs more frequently in children with CP showing increased values of salivary osmolality.

Effects of Salivary Oxidative Markers on Edentulous Patients' Satisfaction with Prosthetic Denture Treatments: A Pilot Study

Objectives

The purpose of this study was to assess relationships among periodontal conditions, salivary antioxidant levels, and patients’ satisfaction with their prostheses.

Methods

This study was conducted at the Division of Prosthodontics, Department of Dentistry, Taipei Medical University Hospital. The periodontal condition of patients was based on an assessment of the plaque index (PI) and gingival index (GI). The pH value, flow rate, and buffer capacity of the saliva were estimated. The salivary total antioxidant status (TAS) and superoxide dismutase (SOD) level were also determined. Patients’ satisfaction with prosthetic treatments was evaluated using the Chinese version of the short-form Oral Health Impact Profile (OHIP-14C). A multivariate regression model was used to determine whether patients’ satisfaction with prosthetic treatment was affected by their oral health status.

Results

In total, 35 edentulous patients were recruited. In the Spearman correlation analysis, salivary pH (r = -0.36, p = 0.03) and the buffer ability (r = -0.48, p<0.01) were associated with OHIP-14C scores. In the multivariate analysis, patients who had a higher GI also had a higher score of physical disabilities (β = 1.38, p = 0.04). Levels of SOD increased with the scores of psychological discomfort (β = 0.33 U/g protein, p = 0.04).

Conclusions

This study suggested that both the GI and SOD levels were associated with patients’ satisfaction with prosthetic treatments. To the best of our knowledge, this is the first study to elucidate the relationship between OHIP scores and salivary oxidative markers in edentulous patients.

Linear reciprocal interaction between dental caries and salivary characteristics

Carious tooth surfaces can alter saliva in various ways. We investigated whether salivary parameters were affected by elimination of existing active dental caries in 99 children (age 6-12 years) with more than five carious tooth surfaces. Unstimulated saliva samples were obtained from each child, and salivary characteristics were evaluated. One month after caries treatment that eliminated all existing dental caries, saliva sampling and analysis were repeated. Saliva viscosity significantly decreased (P = 0.04), while pH and saliva buffering capacity significantly increased (P < 0.001). There was no significant difference in unstimulated salivary production at the start of the study and 1 month after caries elimination (P > 0.05). The relationship between dental caries and salivary condition is reciprocal. Treatment of existing dental caries can prevent future caries by improving saliva quality.

Biocompatibility of a titanium dioxide-coating method for denture base acrylic resin

OBJECTIVES

Ease of denture cleaning is of paramount importance in geriatric patients and those with limited dexterity. We have previously investigated methods of coating dentures with titanium dioxide (TiO₂ ) and reported the effects (self-cleaning and antibacterial) of such treatments in in vitro studies. This study was to verify the biocompatibility of a TiO₂ -coated acrylic resin produced by the new coating method with spray-coating technique.

METHODS

Specimens were prepared from denture base acrylic resin and polished up to grit #1000. The TiO₂ -coating agent was sprayed onto the specimens using an airbrush gun. Specimens were then divided into 'polymethyl methacrylate (PMMA)', 'primer-coated PMMA' and 'TiO₂ -coated PMMA' groups to be evaluated for biological safety using a hamster oral mucosa irritation test, a guinea pig skin sensitisation test and a rabbit intracutaneous test. The biological reaction was scored.

RESULTS

Reaction scores were considerably <1.0, the acceptable limit set by the ISO, in all three tests. Indeed, in most samples, there was no deleterious effect at all.

CONCLUSION

These results tested on animals demonstrate that denture base resin coated with TiO₂ by this method does not cause irritation or sensitisation of the oral mucosa, skin or intracutaneous tissue and is therefore good biocompatibility for use in close proximity to oral mucosa and skin.

Evaluation of application possibility of water containing organic acids for chemical denture cleaning for older adults

AIM

The purpose of the present study was to evaluate the application possibility of water containing organic acids (WOA), made by some organic acids used as food additives, for chemical denture cleaning for older adults by microbial investigation.

METHODS

Using an in vitro biofilm study, we determined the effects of WOA on Streptococcus sanguinis, S. pneumoniae and Candida albicans attached to heat-cured acrylic resins. Specimens were divided into three groups as follows: control group (TW), commercial denture cleaner group (DC) and WOA group (WOA). Specimens were treated with each for 5 min, 30 min or 8 h, and the numbers of attached microbes were determined by counting colony-forming units or adenosine triphosphate analysis. Using an in vivo biofilm study, we studied the effects of these same solutions on 60 complete dentures. The dentures were divided randomly and blindness into three groups as described above, and treated for 10 min. The numbers of microbes attached to dentures before and after treatment were determined by counting colony-forming units.

RESULTS

For the in vitro biofilm study, there were significant differences in the numbers of microbes between WOA and TW, although there were no significant differences between WOA and DC except for C. albicans. For the in vivo biofilm study, there were significant differences between WOA, DC and TW, although there was no significant difference between WOA and DC.

CONCLUSION

We conclude that water containing organic acids exerts antimicrobial effects as strong as commercial denture cleaner, and it has an application possibility of use for safe chemical denture cleaning for older adults.

Shaping the oral microbiota through intimate kissing

BACKGROUND

The variation of microbial communities associated with the human body can be the cause of many factors, including the human genetic makeup, diet, age, surroundings, and sexual behavior. In this study, we investigated the effects of intimate kissing on the oral microbiota of 21 couples by self-administered questionnaires about their past kissing behavior and by the evaluation of tongue and salivary microbiota samples in a controlled kissing experiment. In addition, we quantified the number of bacteria exchanged during intimate kissing by the use of marker bacteria introduced through the intake of a probiotic yoghurt drink by one of the partners prior to a second intimate kiss.

RESULTS

Similarity indices of microbial communities show that average partners have a more similar oral microbiota composition compared to unrelated individuals, with by far most pronounced similarity for communities associated with the tongue surface. An intimate kiss did not lead to a significant additional increase of the average similarity of the oral microbiota between partners. However, clear correlations were observed between the similarity indices of the salivary microbiota of couples and self-reported kiss frequencies, and the reported time passed after the latest kiss. In control experiments for bacterial transfer, we identified the probiotic Lactobacillus and Bifidobacterium marker bacteria in most kiss receivers, corresponding to an average total bacterial transfer of 80 million bacteria per intimate kiss of 10 s.

CONCLUSIONS

This study indicates that a shared salivary microbiota requires a frequent and recent bacterial exchange and is therefore most pronounced in couples with relatively high intimate kiss frequencies. The microbiota on the dorsal surface of the tongue is more similar among partners than unrelated individuals, but its similarity does not clearly correlate to kissing behavior, suggesting an important role for specific selection mechanisms resulting from a shared lifestyle, environment, or genetic factors from the host. Furthermore, our findings imply that some of the collective bacteria among partners are only transiently present, while others have found a true niche on the tongue's surface allowing long-term colonization.

Experiência de cárie e osmolaridade salivar em crianças com paralisia cerebral

INTRODUÇÃO: Estudos têm demonstrado que quanto maior a severidade do dano neurológico em crianças com paralisia cerebral (PC), maior é o risco de doenças orais. OBJETIVO: Correlacionar a experiência de cárie com a osmolaridade salivar em crianças com PC. MATERIAL E MÉTODO: Participaram do estudo 99 crianças (9,2±2,3 anos) com PC, em tratamento reabilitacional. A saliva de repouso foi coletada no período matutino, utilizando rolos absorventes (Salivette®) por cinco minutos. A osmolaridade salivar foi medida por depressão do ponto de congelamento em osmômetro. As avaliações incluíram a experiência de cárie pelo índice de dentes cariados, perdidos e obturados (CPOD), e o motor oral durante o processo de alimentação da criança. Foram utilizados os testes Qui-quadrado, t de Student, Correlação de Spearman e razão de chances (OR), com nível de significância de 5%. RESULTADO: O grupo 1 (G1) foi composto por 41 crianças livres de cárie e o grupo 2 (G2), por 58 crianças com cárie (CPOD=3,5±2,7). Os grupos foram homogêneos para gênero (p=0,884) e idade (p=0,174). Entretanto, diferiram significantemente com relação à motricidade oral, apresentando G2 maiores porcentagens de crianças com motor oral subfuncional (p<0,001) e tetraparéticos (p=0,001). O G2 apresentou valores significantemente maiores (p<0,001) para osmolaridade (99,6±36,7mOsml) quando comparado ao G1 (76,7±15,9mOsml). Observou-se uma correlação significante entre osmolaridade e experiência de cárie (p<0,001). Apresentar osmolaridade superior a 76,7 (OR=5,18; 1,85 a 14,83) foi determinante individual de maior probabilidade de apresentar risco de cárie (CPOD>0). CONCLUSÃO: Maiores valores de osmolaridade salivar aumentam o risco de cárie em crianças com PC.

Dry mouth and denture plaque microflora in complete denture and palatal obturator prosthesis wearers

OBJECTIVE AND BACKGROUND

The purpose of this study was to investigate the association of dry mouth with denture plaque microflora in patients with palatal obturator prostheses from the viewpoint of infection control.

METHODS

Thirty palatal obturator prosthesis wearers were compared with 30 healthy maxillary complete denture wearers. Dry mouth was examined using a moisture-checking device and was diagnosed by the measured moisture levels. Denture plaque was collected by rubbing the mucosal surface of the denture with a swab; collected microorganisms were cultured and identified using culture-dependent methods. The number of colonising microorganisms and prevalence of microorganisms were examined according to the type of prostheses and presence of dry mouth using nonparametric tests and frequency analysis (α = 0.05).

RESULTS

The prevalence of Candida spp. and Staphylococcus spp. in palatal obturator prostheses was significantly higher than that in complete dentures. In palatal obturator prostheses, the total number of colonising microorganisms showed no significant differences between the groups with and without dry mouth on each side of the prostheses. However, the prevalence of Candida spp. and Staphylococcus spp. in the group with dry mouth was significantly higher than that in the group without dry mouth. The number of microorganisms and moisture levels of palatal obturator prosthesis wearers showed a significantly negative correlation with Candida spp. and Staphylococcus spp., but a positive correlation with Neisseria spp.

CONCLUSION

It was concluded that palatal obturator prosthesis wearers with a dry mouth have greater colonisation by Candida spp. and Staphylococcus spp. than do complete denture wearers.

The relation between oral Candida load and bacterial microbiome profiles in Dutch older adults

Currently there are no evidence-based ecological measures for prevention of overgrowth and subsequent infection by fungi in the oral cavity. The aim of this study was to increase our knowledge on fungal-bacterial ecological interactions. Salivary Candida abundance of 82 Dutch adults aged 58-80 years was established relative to the bacterial load by quantitative PCR analysis of the Internal Transcribed (ITS) region (Candida) and 16S rDNA gene (bacteria). The salivary microbiome was assessed using barcoded pyrosequencing of the bacterial hypervariable regions V5-V7 of 16S rDNA. Sequencing data was preprocessed by denoising and chimera removal, clustered in Operational Taxonomic Units (OTUs) and assigned to taxonomy. Both OTU-based (PCA, diversity statistics) and phylogeny-based analyses (UniFrac, PCoA) were performed. Saliva of Dutch older adults contained 0-4 × 10(8) CFU/mL Candida with a median Candida load of 0.06%. With increased Candida load the diversity of the salivary microbiome decreased significantly (p<0.001). Increase in the Candida load correlated positively with class Bacilli, and negatively with class Fusobacteria, Flavobacteria, and Bacteroidia. Microbiomes with high Candida load were less diverse and had a distinct microbial composition towards dominance by saccharolytic and acidogenic bacteria--streptococci. The control of the acidification of the oral environment may be a potential preventive measure for Candida outgrowth that should be evaluated in longitudinal clinical intervention trials.

Effect of saliva viscosity on the co-aggregation between oral streptococci and Actinomyces naeslundii

BACKGROUND

The co-aggregation of oral bacteria leads to their clearance from the oral cavity. Poor oral hygiene and high saliva viscosity are common amongst the elderly; thus, they frequently suffer from pneumonia caused by the aspiration of oral microorganisms.

OBJECTIVES

To examine the direct effect of saliva viscosity on the co-aggregation of oral streptococci with actinomyces.

MATERIALS AND METHODS

Fifteen oral streptococcal and a single actinomyces strain were used. Co-aggregation was assessed by a visual assay in phosphate buffer and a spectrophotometric assay in the same buffer containing 0-60% glycerol or whole saliva.

RESULTS

Nine oral streptococci co-aggregated with Actinomyces naeslundii ATCC12104 in the visual assay and were subsequently used for the spectrophotometric analysis. All tested strains displayed a decrease in co-aggregation with increasing amounts of glycerol in the buffer. The co-aggregation of Streptococcus oralis with A. naeslundii recovered to baseline level following the removal of glycerol. The per cent co-aggregation of S. oralis with A. naeslundii was significantly correlated with the viscosity in unstimulated and stimulated whole saliva samples (correlation coefficients: -0.52 and -0.48, respectively).

CONCLUSION

This study suggests that saliva viscosity affects the co-aggregation of oral streptococci with actinomyces and that bacterial co-aggregation decreases with increasing saliva viscosity.

Denture stomatitis treated with photodynamic therapy: five cases

OBJECTIVE

Photodynamic therapy (PDT) is an effective method for Candida spp. inactivation in vitro and in vivo, but as yet, no clinical trial has been conducted. This report describes 5 cases of denture stomatitis (DS) treated with PDT.

STUDY DESIGN

Five subjects with clinical and microbiologic diagnosis of DS were submitted to 6 sessions of PDT 3 times a week for 15 days. In each session, patients' dentures and palates were sprayed with 500 mg/L Photogem, and, after 30 minutes of incubation, irradiated by light-emitting diode light source at 455 nm (37.5 and 122 J/cm(2), respectively). Cultures of Candida spp. from dentures and palates and standard photographs of the palates were taken at baseline (day 0), at the end of the treatment (day 15), and at follow-up time intervals (days 30 and 60).

RESULTS

Four patients showed clinical resolution of DS (no inflammation) after PDT sessions, and only 1 subject demonstrated reduction in palatal inflammation. Recurrence of DS was observed in 2 patients during the follow-up period.

CONCLUSIONS

PDT appears to be an alternative treatment for DS.

Evaluation of the efficacy of chemical disinfectants for disinfection of heat-polymerised acrylic resin

OBJECTIVE

This study evaluated the efficacy of disinfectants on the internal aspect of heat-polymerised acrylic resin contaminated with microbial strains.

BACKGROUND

Dentures absorb oral fluids and become contaminated by different microorganisms.

METHODS

Two hundred and fifty rectangular specimens were made of heat-polymerised acrylic resin, and then divided into five groups corresponding to the microbial strains (Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, S. mutans and Enterococcus faecalis). After contamination, the specimens were immersed in 1 and 2% sodium hypochlorite and 2% glutaraldehyde for periods of 5, 10 and 15 min. The specimens were placed into tubes containing different broths and incubated at 35°C and then visually analysed. Turbidity in the medium indicated microbial growth. The Fisher's exact test was used in the analysis of the results.

RESULTS

The strain E. faecalis was the most resistant to the disinfectant solutions, and among them, glutaraldehyde was more effective than 2 and 1% hypochlorite for disinfection for 5 min; in the 10-min period there were no differences between the disinfectants. In 15 min of immersion, 1% hypochlorite and glutaraldehyde were more effective than 2% hypochlorite.

CONCLUSIONS

Disinfection for 10 min with 1% hypochlorite and glutaraldehyde is effective in disinfecting the internal aspect of heat-polymerised acrylic resin.