Controlled Hierarchical Self-Assembly of Catenated Cages.

Constructing hierarchical superstructures to achieve comparable complexity and functions to proteins with four-level hierarchy is challenging, which relies on the elaboration of novel building blocks with complex structures. We present a series of catenated cages with unique structural complexity and tailorability. The rational design was realized as such: A catenane of two symmetric cages (CSC), CSC-1, with all rigid imine panels was converted to a catenane of two dissymmetric cages (CDC), CDC-1, with two exterior flexible amine panels, and CDC-5 was tailored from CDC-1 by introducing an additional methyl group on each blade to increase lateral hindrance. CDC-1s with the most irregular and flexible configuration formed supramolecular dimers, which self-organized into 3D continuous wavelike plank with a three-level hierarchy, previously undiscovered by conventional building blocks. A drastically different 3D triclinic crystalline phase with a four-level hierarchy and trigonal phase with a three-level hierarchy were constructed of distorted CSC-1s and the most symmetric CDC-5s, respectively. The wavelike plank exhibited the lowest order, and the triclinic phase had a lower order than the trigonal phase which had the highest order. It correlates with the configuration of the primary structures, namely, the most disordered shape of CDC-1, the low-order configuration of CSC-1, and the most ordered geometry of CDC-5. The catenated cages with subtle structural differences therefore provide a promising platform for the search of emerging hierarchical superstructures that might be applied to proton conductivity, ferroelectricity, and catalysis.

Risk factors for postoperative pneumonia according to examination findings before surgery under general anesthesia.

OBJECTIVE: This study was performed to determine the risk factors associated with postoperative complications after surgery under general anesthesia according to respiratory function test results and oral conditions. MATERIALS AND METHODS: Preoperative examination data were collected for 471 patients who underwent surgery under general anesthesia at the Medical Hospital of Kyusyu University. Respiratory function tests, oral examinations, and perioperative oral management were performed in all patients. The incidence of and risk factors for postoperative complications were investigated. Classification and regression tree analyses were performed to investigate the risk factors for postoperative complications. RESULTS: Among the 471 patients, 11 developed postoperative pneumonia, 10 developed postoperative respiratory symptoms, and 10 developed postoperative fever. The most important risk factor for pneumonia was edentulism. Age, the Brinkman index, and head and neck surgery were also revealed as important risk factors for pneumonia. The O'Leary plaque control record (initial visit) was an important risk factor for postoperative respiratory symptoms. With respect to postoperative fever, a Hugh-Jones classification of grade > 1 was the most important risk factor; edentulism and a Brinkman index of > 642.5 were also found to be risk factors. CONCLUSION: In addition to respiratory function tests, oral examinations may be important for the prediction of postoperative complications. Additionally, improved oral hygiene may be effective in preventing postoperative respiratory complications. CLINICAL RELEVANCE: Risk factors for postoperative complications should be comprehensively evaluated using both respiratory function tests and oral findings.

Low-intensity pulsed ultrasound enhances the rate of lateral tooth movement and compensatory bone formation in rats.

INTRODUCTION: Because mechanical stimulation of the periodontal ligament by low-intensity pulsed ultrasound (LIPUS) has been shown to increase the speed of bone remodeling, this study aimed to examine the effects of LIPUS stimulation on the rate of tooth movement and bone remodeling during lateral tooth movement. METHODS: Twelve-week-old Wistar rats were divided into 2 groups. The LIPUS group received experimental tooth movement with LIPUS stimulation, and the tooth movement (TM) group were provided experimental tooth movement without LIPUS. For each group, the upper right first molars were moved buccally with fixed appliances. LIPUS exposure was placed in the region corresponding to the right maxillary first molar. Three days after tooth movement, tartrate-resistant acid phosphatase was examined. Fourteen days after tooth movement, the intermolar width, bone mineral content, and bone volume fraction were analyzed by micro-computed tomography, and newly formed bone was measured histomorphometrically. RESULTS: The number of TRAP-positive cells in the compressed region was higher in the LIPUS group. The intermolar width was significantly higher in the LIPUS group than in the TM group. The alveolar bone around the maxillary first molar showed no differences in bone mineral content and bone volume fraction between the LIPUS and TM groups. The LIPUS group exhibited a more significant amount of newly formed alveolar bone than the TM group. CONCLUSIONS: The present study provides evidence of the beneficial effects of LIPUS on the lateral tooth movement.

Effects of self-assessed chewing ability, tooth loss and serum albumin on mortality in 80-year-old individuals: a 20-year follow-up study.

BACKGROUND: The association between dental status and mortality in community-dwelling older adults has been documented by several studies. The aim of this study was to analyze the contribution of self-assessed chewing ability, number of remaining teeth and serum albumin levels to mortality and the interactions between the three factors. METHODS: A 20-year follow-up study was conducted with 666 subjects aged 80 years (from 1996 to 2017) who resided in the 8 areas served by one health center in Iwate Prefecture. Health check-ups including physical fitness measurements were conducted at a meeting place or gymnasium. Medical interview and blood sampling were conducted by physician. Oral examination was examined by dentist. The number of remaining teeth, serum albumin levels, and self-assessed chewing ability were used as predictors of mortality. RESULTS: Among the 608 subjects (233 men and 375 women) included in this study, only 12 subjects (1.97%) survived after 20 years of follow-up. For men, dental status and serum levels of albumin were significantly associated with mortality. The hazard ratios of self-assessed chewing ability calculated by item response theory analysis and the inability to chew at least one food adjusted for serum albumin and tooth conditions were statistically significant in men. When adjusted by health status evaluated by blood tests, self-assessed chewing ability was statistically significant in men. According to path analysis, self-assessed chewing ability and serum albumin independently affected mortality in men. CONCLUSION: Masticatory dysfunction may be an important risk factor for mortality in men, even though it was self-assessed. Retaining chewing ability might be a useful predictor of longevity in older male adults.

Effect of Mucosal Brushing on the Serum Levels of C-Reactive Protein for Patients Hospitalized with Acute Symptoms.

This study was based in a hospital setting. Patients with acute symptoms face a life-threatening crisis and often have systemic complications during the convalescence stage. During the acute stage, oral function does not work and oral hygiene status deteriorates. A gauze or sponge brush is generally used to wipe the oral cavity; however, this process does not clean the oral cavity enough. Effective oral care requires better methods. Patients participating in this study were all hospitalized by ambulance and with acute symptoms. During the convalescence stage, patients were assigned application of mucosal brushing or wiping by gauze or sponge brush by order of hospitalization. The effects were evaluated by the number of bacteria on the tongue surface, serum C-reactive protein (CRP) and body temperature. Changes in bacterial count, body temperature, and CRP were effectively reduced in the mucosal brushing group compared to the wiping by gauze or sponge brush group. Based on mixed effect modeling, the coefficient of mucosal brushing for CRP was -2.296 and for body temperature was -0.067 and statistically significant. This simple method can effectively prevent systemic complication of inpatients with deteriorated oral conditions. This method may also be effective for the elderly in nursing homes or perioperative oral-care management.

Consistency of supplied food and dentition status of the elderly in residential care homes.

BACKGROUND: The association between oral health and malnutrition has been investigated in detail. The nutrition of elderly subjects in residential care homes is determined by caregivers, dietitians or nutritionists and managed by changing the consistency of their supplied food. However, few reports have described the relationship between oral condition and supplied food consistency. The objective of this study was to determine dentition status and care levels that correlate with supplied food consistency among elderly residents of care facilities. In addition, we estimated the care level at which ordinary food consistency can be supplied by caregivers who cannot diagnose dental status. METHOD: Several factors, including dentition, wearing removable dentures, meals categorized as ordinary or processed (sliced, mashed, or liquefied), and care levels according to the Japanese standardized care-needs certification system were investigated in 276 elderly residents (male, n = 56; female, n = 220; mean age, 87.68 ± 5.94 years) of 12 fee-based care facilities. RESULTS: The results of this study showed that care levels were significantly correlated with the consistency of the food supplied to the residents. When supplied food consistency was categorized as ordinary or processed, the number of remaining teeth and the number of tooth contact pairs, either natural or artificial, were statistically significant. From logistic regression analysis, it was determined that the numbers of tooth contact pairs were statistically significant among residents requiring high levels of care. CONCLUSION: The number of tooth contact pairs, either natural or artificial, was one of the contributing factors for deciding supplied food consistency among elderly residents of care facilities. Elderly residents requiring less than care level 3 should have ordinary meals.

Complete genome sequence of Streptococcus troglodytae TKU31 isolated from the oral cavity of a chimpanzee (Pan troglodytes).

Streptococcus troglodytae TKU31 was isolated from the oral cavity of a chimpanzee (Pan troglodytes) and was found to be the most closely related species of the mutans group streptococci to Streptococcus mutans. The complete sequence of TKU31 genome consists of a single circular chromosome that is 2,097,874 base pairs long and has a G + C content of 37.18%. It possesses 2082 coding sequences (CDSs), 65 tRNAs and five rRNA operons (15 rRNAs). Two clustered regularly interspaced short palindromic repeats, six insertion sequences and two predicted prophage elements were identified. The genome of TKU31 harbors some putative virulence associated genes, including gtfB, gtfC and gtfD genes encoding glucosyltransferase and gbpA, gbpB, gbpC and gbpD genes encoding glucan-binding cell wall-anchored protein. The deduced amino acid identity of the rhamnose-glucose polysaccharide F gene (rgpF), which is one of the serotype determinants, is 91% identical with that of S. mutans LJ23 (serotype k) strain. However, two other virulence-associated genes cnm and cbm, which encode the collagen-binding proteins, were not found in the TKU31 genome. The complete genome sequence of S. troglodytae TKU31 has been deposited at DDBJ/European Nucleotide Archive/GenBank under the accession no. AP014612.

A new screening method for periodontitis: an alternative to the community periodontal index.

BACKGROUND: Periodontal screening plays an important role in the prevention of periodontal disease and promotes an improvement in oral health-related quality of life. The World Health Organization's Community Periodontal Index should be carried out by well-trained dentists. However, the Community Periodontal Index is an invasive technique, and if used for periodontal screening, increases the cost of evaluation. In order to overcome these issues, we developed saliva tests for periodontal screening. The purpose of this study was to calculate the sensitivity and specificity of our method for measuring hemoglobin and lactate dehydrogenase levels in saliva. METHODS: Inclusion criteria were adults aged over 20 years with at least 20 teeth remaining. The study population comprised 38 men and 54 women with a mean age of 50.03 years. Oral examinations were carried out by dentists, and the number of remaining teeth, presence or absence of calculus, bleeding on probing and pocket depth were recorded. In this study, periodontitis was defined according to the criteria of the Center for Disease Control and Prevention in partnership with the American Academy of Periodontology. In order to examine hemoglobin and lactate dehydrogenase levels in saliva, participants were instructed to chew on a standard-sized tasteless and odorless gum base for 5 min, during which time, stimulated whole saliva was continuously collected. RESULTS: The sensitivity and specificity for hemoglobin levels were 0.759 and 0.763, respectively, and 0.722 and 0.711, respectively, for lactate dehydrogenase levels. Combining these two tests, when samples tested positive for both hemoglobin and lactate dehydrogenase, the positive predictive value was 91.7 %. CONCLUSION: Measuring hemoglobin and lactate dehydrogenase levels in saliva is a less invasive method than the Community Periodontal Index. Therefore, our saliva tests may be a viable alternative to the Community Periodontal Index for periodontal screening.

Application of chimeric glucanase comprising mutanase and dextranase for prevention of dental biofilm formation.

Water-insoluble glucan (WIG) produced by mutans streptococci, an important cariogenic pathogen, plays an important role in the formation of dental biofilm and adhesion of biofilm to tooth surfaces. Glucanohydrolases, such as mutanase (α-1,3-glucanase) and dextranase (α-1,6-glucanase), are able to hydrolyze WIG. The purposes of this study were to construct bi-functional chimeric glucanase, composed of mutanase and dextranase, and to examine the effects of this chimeric glucanase on the formation and decomposition of biofilm. The mutanase gene from Paenibacillus humicus NA1123 and the dextranase gene from Streptococcus mutans ATCC 25175 were cloned and ligated into a pE-SUMOstar Amp plasmid vector. The resultant his-tagged fusion chimeric glucanase was expressed in Escherichia coli BL21 (DE3) and partially purified. The effects of chimeric glucanase on the formation and decomposition of biofilm formed on a glass surface by Streptococcus sobrinus 6715 glucosyltransferases were then examined. This biofilm was fractionated into firmly adherent, loosely adherent, and non-adherent WIG fractions. Amounts of WIG in each fraction were determined by a phenol-sulfuric acid method, and reducing sugars were quantified by the Somogyi-Nelson method. Chimeric glucanase reduced the formation of the total amount of WIG in a dose-dependent manner, and significant reductions of WIG in the adherent fraction were observed. Moreover, the chimeric glucanase was able to decompose biofilm, being 4.1 times more effective at glucan inhibition of biofilm formation than a mixture of dextranase and mutanase. These results suggest that the chimeric glucanase is useful for prevention of dental biofilm formation.

Streptococcus panodentis sp. nov. from the oral cavities of chimpanzees.

Three strains TKU9, TKU49 and TKU50(T) , were isolated from the oral cavities of chimpanzees (Pan troglodytes). The isolates were all gram-positive, facultative anaerobic cocci that lacked catalase activity. Analysis of partial 16S rRNA gene sequences showed that the most closely related species was Streptococcus infantis (96.7%). The next most closely related species to the isolates were S. rubneri, S. mitis, S. peroris and S. australis (96.6 to 96.4%). Based on the rpoB and gyrB gene sequences, TKU50(T) was clustered with other member of the mitis group. Enzyme activity and sugar fermentation patterns differentiated this novel bacterium from other members of the mitis group streptococci. The DNA G + C content of strain TKU50(T) was 46.7 mol%, which is the highest reported value for members of the mitis group (40-46 mol%). On the basis of the phenotypic characterization, partial 16S rRNA gene and sequences data for two housekeeping gene (gyrB and rpoB), we propose a novel taxa, S. panodentis for TKU 50(T) (type strain = CM 30579(T) = DSM 29921(T) ), for these newly described isolates.

Cranial-base morphology in adults with skeletal Class III malocclusion.

INTRODUCTION: The objectives of this study were to clarify the characteristics of cranial-base morphology in adults with skeletal Class III malocclusion and investigate factors relating to the establishment of a skeletal Class III malocclusion. METHODS: Initial lateral cephalograms of women were examined. Subjects with an ANB angle of 0° to 4°, normal overjet and overbite, and a Class I molar relationship were classified as Class I (n = 86). Those with an ANB angle less than -1°, a Wits appraisal less than 2 mm, a negative overjet, and a Class III molar relationship were the Class III group (n = 86) in this study. Angular, linear, and coordinate measurements were made. Multivariate analysis of variance and the Student t test were used to analyze significant differences between the 2 groups. Discriminant analysis, logistic regression analysis, and decision analysis were used to identify which cranial-base and maxillomandibular variables influenced the establishment of a skeletal Class III malocclusion. RESULTS: The Class III group had smaller values for NSBa, SeSBa, FH-SSe, and FH-SBa. Sphenoidale and basion were more inferior and anterior than those of the Class I group. There was no difference in the anterior and posterior cranial-base lengths between the groups. Greater mandibular length was the first major characteristic in the Class III group, followed by smaller values for SeSBa and NSBa. CONCLUSIONS: Cranial-base morphology in adults with a skeletal Class III malocclusion is different from that in a skeletal Class I malocclusion. Smaller cranial-base angles, steeper posterior cranial bases, more inferiorly positioned sphenoidale, and more anteriorly positioned basion are major characteristics of skeletal Class III malocclusions. These characteristics play important roles in the establishment of a skeletal Class III malocclusion.

Streptococcus troglodytae sp. nov., from the chimpanzee oral cavity.

Six strains, TKU 25, TKU 28, TKU 30, TKU 31(T), TKU 33 and TKU 34, were isolated from the oral cavity of a chimpanzee (Pan troglodytes). Colonies of strains grown on Mitis-Salivarius agar were similar in morphology to that of Streptococcus mutans. The novel strains were Gram-stain-positive, facultatively anaerobic cocci that lacked catalase activity. Analysis of the partial 16S rRNA gene sequences of these isolates showed that the most closely related strain was the type strain of S. mutans (96.4 %). The next closely related strains to the isolates were the type strains of Streptococcus devriesei (94.5 %) and Streptococcus downei (93.9 %). These isolates could be distinguished from S. mutans by inulin fermentation and alkaline phosphatase activity (API ZYM system). The peptidoglycan type of the novel isolates was Glu-Lys-Ala(3). Strains were not susceptible to bacitracin. On the basis of phenotypic characterization, partial 16S rRNA gene and two housekeeping gene (groEL and sodA) sequence data, we propose a novel taxon, Streptococcus troglodytae sp. nov.; the type strain is TKU 31(T) ( = JCM 18038(T) = DSM 25324(T)).

Distribution of Streptococcus troglodytae and Streptococcus dentirousetti in chimpanzee oral cavities.

The aim of this study was to analyze the distribution and phenotypic properties of the indigenous streptococci in chimpanzee (Pan troglodytes) oral cavities. Eleven chimpanzees (aged from 9 to 44 years, mean ± SD, 26.9 ± 12.6 years) in the Primate Research Institute of Kyoto University were enrolled in this research and brushing bacterial samples collected from them. Streptococci were isolated from the oral cavities of all chimpanzees. The isolates (n = 46) were identified as thirteen species by 16S rRNA genes analysis. The predominant species was Streptococcus sanguinis of mitis streptococci from five chimpanzees (45%). Mutans streptococci were isolated from six chimpanzees (55%). The predominant species in the mutans streptococci were Streptococcus troglodytae from four chimpanzees (36%), this species having been proposed as a novel species by us, and Streptococcus dentirousetti from three chimpanzees (27%). Streptococcus mutans was isolated from one chimpanzee (9%). However, Streptococcus sobrinus, Streptococcus macacae and Streptococcus downei, which are indigenous to human and monkey (Macaca fasciclaris) oral habitats, were not isolated. Of the mutans streptococci, S. troglodytae, S. dentirousetti, and S. mutans possessed strong adherence activity to glass surface.

Correlation between health-care costs and salivary tests.

The burden of health-care costs relative to gross domestic product in Japan is increasing. A large percentage (7.6% in 2009) of the Japanese gross domestic product has been spent on health care, and this percentage has been increasing annually. Soaring health-care costs have been recognised as a serious social problem. In this study, we attempted to estimate the relationship between periodontal disease and health-care costs. Subjects consisted of teachers and staff members (35 men, 26 women; mean age, 45 ± 9 years) from two high schools. The salivary levels of lactate dehydrogenase and haemoglobin were adopted as biomarkers to assess periodontal disease. After salivary tests, data for the health-care costs over the subsequent 6 months were provided by the mutual association of the public schools on an individual basis. Curve-fit estimations were then performed where health-care costs were used as a dependent variable and age or salivary levels of haemoglobin or lactate dehydrogenase were used as independent variables. However, no good fitness was obtained. Subsequently, multilayer perceptron neural networks were applied. With the neural networks, good fitness was obtained by using lactate dehydrogenase as an independent variable. The results of this study show that oral health, particularly periodontal disease, is correlated with total health-care costs. The data presented in this study suggests that, from the perspective of both oral and systemic health, oral health can be a signpost in well-being and health promotion.

Human periodontal ligament fibroblasts are the optimal cell source for induced pluripotent stem cells.

Among the various kinds of fibroblasts existing in the human body, the periodontal ligament (PDL) fibroblasts have been suggested as multipotent cells. Periodontal ligament fibroblasts are characterized by rapid turnover, a high remodeling capacity and remarkable capacity for renewal and repair. They also differentiate into osteoblasts and cementoblasts. We established iPS cells from human PDL fibroblasts by introducing the ES cell markers Oct3/4, Sox2, Nanog, Klf4 and Lin28 by retrovirus transduction, even without the oncogene c-Myc. The iPS cells established in this study expressed the ES cell markers and formed teratomas in SCID mice. The c-Myc expression level in the PDL fibroblasts was higher than that in the iPS cells by quantitative RT-PCR. Therefore, we have concluded that PDL fibroblasts could be an optimal cell source for iPS cells.

Effects of the Dental Caries Preventive Procedure on the White Spot Lesions during Orthodontic Treatment-An Open Label Randomized Controlled Trial.

(1) Background: The aim of this study was to assess the preventive effect of tooth surface disinfection treatment, in addition to fluoride application, during fixed orthodontic treatment. (2) Methods: An open label randomized control trial for the evaluation of the dental caries preventive procedure was performed for the patients with high caries risk who had been visited at Department of Orthodontics, Tsurumi University Dental Hospital for orthodontics treatment. The follow-up period was six months. White spot lesions (WSLs) were evaluated by quantitative light-induced fluorescence (QLF). Cariogenic bacteria were monitored and evaluated by bacterial culture. In addition, the oral microbiome was evaluated by a next-generation sequence (NGS). (3) Results: By the mixed effect modeling, tooth surface disinfection treatment significantly reduced cariogenic bacteria and all parameters obtained by QLF. (4) Conclusions: Tooth surface disinfection treatment, in addition to PMTC and fluoride application, were effective for dental caries prevention and keeping a healthy microbiome during orthodontic treatment.

Mechanism of active eruption of molars in adolescent rats.

The mechanism of active eruption of molars was examined in 36 male adolescent Wistar rats. Histological, histochemical [tetracycline (TC) labelling and alkaline phosphatase (ALP) activity], and immunohistochemical [transforming growth factor (TGF)-ß1, -ß2, and -ß3] investigations were conducted of the rat molar areas. Real-time reverse transcription-polymerase chain reaction (RT-PCR) for mRNA of TGF-ß was performed on the periodontal ligament (PDL) dissected out by laser capture microdissection. TC labelling lines showed that a considerable amount of bone formation occurred in the alveolar crest region, apical region, and intraradicular septum, indicating that the maxillary molars had moved downward. However, the periodontal fibres revealed a regular arrangement (alveolar crest, horizontal and oblique fibres) during the experimental period. This suggests that new formation of alveolar crest fibres and rearrangement of the periodontal fibres occurred in the PDL. ALP activity was intense on the bone surface and in the PDL. TGF-ß1 was also detected in osteoblasts and fibroblasts but less so in cementoblasts. Real-time RT-PCR also demonstrated significant expression of mRNA of TGF-ß1 in the PDL, indicating that TGF-ß1 was involved in active eruption. These results suggest that active eruption occurs in adolescent rats and can be managed by TGF-ß1.

Impact of Working Environment on Job Satisfaction: Findings from a Survey of Japanese Dental Hygienists.

In Japan, there is currently a shortage of dental hygienists. The number of dental hygienists as a workforce at dental clinical practice is not sufficient. Several factors affect career retention and job satisfaction of hygienists and these factors are considered to correlate with each other to construct networks. The aim of this study was to present a structural model of job satisfaction of Japanese dental hygienists and to determine the characteristics of unmotivated hygienists. The Japan Dental Hygienists' Association has conducted a survey on their working environments every five years since 1981. Questionnaires were sent to all members of the association (16,113) and 8932 answers were returned. The data of 3807 active dental hygienists who worked at clinics were analyzed. Items associated with job satisfaction were derived from two latent variables, namely, the intrinsic psychosocial factors for the value of the work and extrinsic employment advantage. Based on the structural equation modeling, the association of value was higher than that of advantage. Most of the hygienists wished to continue working as dental hygienists. More than 60% felt their work required a high level of expertise. The value of the profession is deeply rooted in job satisfaction, motivation, and job retention of Japanese dental hygienists. Working environments where dental hygienists make great use of their specialized skills can lead to high career retention which prevent them from taking career breaks.

Factors Affecting the Reinstatement of the Japanese Dental Hygienist: A Japanese Dental Hygienist Survey Conducted in 2019.

There is a shortage of dental hygienists for dental clinics in Japan. An ideal solution would be for dormant dental hygienists to re-enter the workforce. In this study, we identified the obstacles preventing these dental hygienists from re-entering the workforce. The Japan Dental Hygienists' Association surveyed all 16,113 members about their working conditions. Among the 101 items in the questionnaire, 11 items specifically targeted the reasons why dental hygienists leave their jobs. Among 8780 responses (54.5%), 1063 were from members who had resigned from jobs as dental hygienists. Three hundred and fifty-five (34.4%) answered "Yes" to the question "I would like to return to work if conditions are satisfactory." The most frequent cause for leaving a job was" Childbirth and child-rearing" (16.9%). "Working status/working hours" (15.7%) was the main obstacle to re-entry. Furthermore, dental hygienists with intentions to re-enter decided to leave their jobs most frequently because of "Childbirth and child-rearing" and "Working status/working hours." Improvement of the social support system for dental hygienists is required to ensure a sufficient supply of dental health services.

Improvement of the Working Environment and Daily Work-Related Tasks of Dental Hygienists Working in Private Dental Offices from the Japan Dental Hygienists' Association Survey 2019.

A dental hygienist performs various daily work-related tasks. The aim of this study was to elucidate the daily work-related tasks of Japanese dental hygienists and construct groups to understand the relationships between daily work-related tasks, the attractiveness of dental hygienist work, and the improvement of the working environment. The Japan Dental Hygienists' Association has conducted a postal survey on the employment status of dental hygienists in Japan every five years since 1981. The data on the implementation of 74 daily work-related tasks in dental offices were analyzed from the survey carried out in 2019. The questionnaires were distributed to 16,722 dental hygienists and 8932 were returned (collection rate: 53.4%). The 3796 dental hygienists working at dental clinics were clearly classified into nine groups. Full-time workers requested a reduced workload. Part-time workers requested better treatment rather than reducing the workload. Salary and human relationships were common problems with the working environment. Full-time workers felt that job security was an attractive feature of the dental hygienist role. The data presented in this study may help with the improvement of working conditions for dental hygienists.