Career outcomes and satisfaction among graduates of a 4-year oral health and welfare baccalaureate program at Niigata University, Japan: A cross-sectional study.

OBJECTIVE: Globally, baccalaureate programs in dental hygiene are increasingly established. In addition, in Japan, many dental hygienists (DHs) and social workers (SWs) are prematurely leaving the workforce. This study aimed to investigate the most recent employment, career outcomes, reasons for a job change, and satisfaction with the job and undergraduate curriculum among graduates of the baccalaureate program at the Department of Oral Health and Welfare (DOHW), Faculty of Dentistry, Niigata University. METHODS: All 262 graduates (graduating classes 1-10) of the DOHW were invited to participate in this survey; an original self-administered questionnaire was distributed to those who consented. Responses were received from 114 (43.5%) graduates. RESULTS: Almost all respondents (89.5%) had dual licensure as both DH and certified SW. They were employed immediately after graduation (99.1%) and at the time of the survey (96.5%). Over 60% of them worked as DHs, mainly in hospitals. SWs mainly worked in administration. Among the 113 respondents who were employed, 39.8% changed jobs at least once. The main reasons for job selection were 'interest in job content' and 'flexible working hours'. Nearly 90% of the respondents felt satisfied or fairly satisfied with their job and their undergraduate education. CONCLUSIONS: A quality 4-year baccalaureate degree program in dental hygiene and social welfare positively influenced graduates' work continuity. Most graduates felt satisfied or fairly satisfied with their job and the undergraduate curriculum. Employment rates within each profession and the prevalence of hospital and administrative roles were higher than national averages. Long-term studies of graduates' career outcomes are warranted.

Income from nutrition and oral health management among long-term care insurance facilities in Niigata Prefecture, Japan.

OBJECTIVE: To determine recent insurance claim rates for, facility income from, and the roles of professionals associated with management of nutrition, oral ingestion and oral health maintenance in long-term care insurance facilities (LTCIFs) in Niigata Prefecture. METHODS: A questionnaire on current staffing, oral health professional (OHP) utilisation, and claims for insured benefits for the investigated services was mailed to all LTCIFs in Niigata Prefecture, Japan (n = 304). Claim rates for and average facility income from these benefits were calculated. Facility income was compared between facilities with and without employed OHPs. Statistically significant factors associated with claims for investigated benefits were identified by logistic regression. RESULTS: Responses from 111 facilities indicated that they made insurance claims for nutrition management (95%), transition from tube feeding to oral ingestion (9%), basic maintenance of oral ingestion (39%), additional services for maintenance of oral ingestion (23%), oral health management system (68%), and oral health management (17%). Most facilities established collaborations with private dental clinics, but only 16% of facilities employed OHPs. Facility income was significantly higher (P = 0.005) for facilities that employed OHPs. OHP employment by facilities was associated with claims for four of the six benefits (P < 0.05). CONCLUSIONS: Most facilities consulted with private dental clinics, and 16% of the facilities employed dentists or dental hygienists to help residents manage oral ingestion problems and oral health maintenance. The facility income associated with management of these problems was significantly higher in facilities employing dental professionals.

The influence of temporomandibular joint movement parameters on dental morphology.

Association between tooth morphology, occlusal relations and mandibular condyle/glenoid fossa morphology is still a controversial issue in dentistry. The aim of the present study was to examine the influence of three important articular parameters on the dental morphology and the crown volume, quantifying the variation for each tooth group: incisor, canine, premolar and molar. MATERIALS AND METHODS: All maxillary teeth from a set of basic study models were prepared for zirconia single crowns. The models were scanned and then, using a computer aided design software, they were mounted in a virtual articulator and specific mandibular movements were defined. The crown morphology was designed and statically adapted. Ten models were obtained by dynamical adjustment of the basic model for successively modified articular parameters: sagittal condylar inclination (SCI)=30°, Bennett angle (BA)=10°, Immediate side shift (ISS)=0.5mm - for control and SCI: 40°, 50° and 60° with BA and ISS as control, BA: 15°, 20° and 25° with SCI and ISS as control, ISS: 1.5mm, 1.0mm and 0.0mm with SCI and BA as control - for the nine test models. The following measurements were performed three times on the right side of each model: volume for each tooth group, slope (S) for the central incisor, S and mesio-distal angle (MDA) for canine, S, MDA and vestibulo-oral angle (VOA) for the first premolar and molar. RESULTS: When SCI was varied, statistically significant changes as compared to the controls were found for incisor's and premolar's S, premolar's VOA and, for 50° and 60°, MDA and molar's MDA (for 50°) and VOA (for 60°). When BA was varied, significant changes were found for S (canine) and, in certain models, MDA (premolar, molar). Variations of ISS significantly changed mainly MDA for molars and, in two models, premolars. CONCLUSIONS: Within the limits of this study, among the articular parameters, SCI mostly influenced the dynamic tooth morphology, but canine and molar morphology was stronger influenced by BA and/or ISS.

Relationship between alcohol consumption and periodontal tissue condition in community-dwelling elderly Japanese.

OBJECTIVES: To examine the associations among alcohol consumption level, dietary intake and other lifestyle factors, and periodontal condition, in community-dwelling elderly Japanese of a specific age. BACKGROUND: The relationship between alcohol consumption level and periodontitis is a controversial issue. METHODS: Participants were 438 dentate elders aged 73 years from a larger cohort survey of elders in Niigata City, Japan. Data collected from oral examination of each participant, including number of the existing teeth, mean probing pocket depth and mean clinical attachment level (CAL) were used for the analyses. A semiquantitative food frequency questionnaire and a lifestyle habit questionnaire were used to assess food and alcohol consumption, smoking experience, frequency of tooth brushing, interdental brush use, and visits to a dental clinic during the previous year. Blood glucose control was assessed by the glycated haemoglobin (HbA1c) level. Body mass index was calculated from height and weight measurements. The relationships between each variable and the individual mean CAL were analysed by univariate and multivariate analyses. RESULTS: According to logistic regression analysis, the mean CAL was significantly associated with the number of existing teeth (odds ratio [OR] = 0.90; P < .001), being a heavy drinker (OR = 2.44; P < .05), and smoking experience (OR = 2.37; P < .01). CONCLUSION: This study showed that increased mean CAL was significantly associated with heavy drinking in community-dwelling elderly Japanese (aged 73 years) compared with non-drinking. Our results provide new evidence that high alcohol consumption is associated with an increased risk of periodontal disease and its progression.

An oral health and function screening tool for nursing personnel of long-term care facilities to identify the need for dentist referral without preliminary training.

OBJECTIVE: To develop and evaluate, with a dentist as gold standard, an oral health screening tool, the Oral Health Screening Tool for Nursing Personnel (OHSTNP), that assists long-term care facility nursing staff without preliminary training in identifying resident need for dentist referral. METHODS: Using an OHSTNP adapted from previous screening tools (Chalmers, J Gerontol Nurs, 2004, 30, 5; Tsukada, J Jpn Soc Dent Hyg, 2012, 7, 43), one of four nurses, one of eight caregivers and a dentist with 15 years' experience screened the oral health/function of 57 long-term care facility residents. The OHSTNP included a question on the need and reasons for dentist referral. Tool reliability and validity were evaluated by determining inter-rater agreement (Cohen's kappa), sensitivity, specificity and accuracy. RESULTS: For dentist-nurse and dentist-caregiver pairs, kappa was statistically significant and sensitivity was high (≥0.67, nurses; ≥0.71, caregivers) for natural teeth, dentures and oral function-related categories. Specificity for all categories was ≥0.69. Screening by nurses and caregivers for need for referral had low sensitivity (0.05, 0.23), accuracy (0.25, 0.39) and kappa (-0.01, 0.08). However, if nursing staff had been instructed to request a dentist referral in case of alterations in natural teeth/dentures or severe alterations in any other category, the estimated values increased to a sensitivity of 0.86 and 0.91, an accuracy of 0.75 and 0.82 and a kappa of 0.26 and 0.47. CONCLUSIONS: OHSTNP was reliable and valid for screening natural teeth, denture conditions and oral functions. Supplementary guidelines improved estimates of OHSTNP sensitivity, accuracy and reliability for nurse/caregiver assessment of resident need for dentist referral.

Comprehension of Japanese oral care-related terms among caregivers and nurses, as assessed using a newly developed instrument.

OBJECTIVES: (i) To assess comprehension of oral care-related terms among caregivers and nurses working at long-term care facilities, using a newly developed test; (ii) to analyse the effect of participant characteristics on their comprehension. BACKGROUND: Effective mutual communication between dental professionals and caregivers/nurses is essential for providing information on daily oral care for institutionalised elders. METHODS: A 36-item word-knowledge test in Japanese was developed to assess comprehension of oral care-related terms. The test was administered to a convenience sample of 236 nursing staff (198 caregivers and 38 nurses) at six long-term care facilities in Niigata City, Japan, and its reliability and validity were verified. Associations of participant characteristics with their responses were investigated by multiple regression analysis. RESULTS: Mean percentage of correct responses (accuracy rate) for nursing staff was approximately 62% (highest for oral care products and lowest for prosthodontic terms). Test internal reliability was high (Cronbach's alpha >0.8). Concurrent validity (test ability to distinguish between characteristically different groups) was confirmed. Mean accuracy rate was significantly higher among nurses (78.5 ± 19.3%) than among caregivers (58.7 ± 22.8%), and among respondents with interest in oral care (64.2 ± 21.1%) than among those with no such interest (51.5 ± 28.9%). CONCLUSION: The word-knowledge test was valid and reliable for nursing staff of six long-term care facilities in Niigata City. Their comprehension was low for perioral and intraoral structures, related symptom and disease names, and prosthodontics terms related to oral care. Understanding of oral care-related terms among the nursing staff was related to their occupation and interest in oral care.

Changes in the Oral Moisture and the Amount of Microorganisms in Saliva and Tongue Coating after Oral Ingestion Resumption: A Pilot Study.

BACKGROUND AND OBJECTIVE: Tube feeding has been significantly associated with a higher rate of aspiration pneumonia that is mainly related to oral microorganisms and a reduced salivary flow. Thus, the difference in the mode of nutritional intake is expected to affect the oral environment, but this has not yet been fully clarified. The purpose of this study was to investigate, in tube-fed patients, changes in the oral moisture and the counts of microorganisms in saliva and tongue coating, which occur after oral ingestion resumption. METHODS: Study participants were 7 tube-fed inpatients of the Niigata University Medical and Dental Hospital (72.7±8.5 years old) who received dysphagia rehabilitation at the Unit of Dysphagia Rehabilitation until oral ingestion resumption. Their oral health, swallowing, and nutrition status, oral mucosal moisture, amount of unstimulated saliva and the counts of microorganisms (total microorganisms, streptococci, Candida) in saliva and tongue coating were investigated and compared before and after the recommencement of oral intake. RESULTS: Tongue coating, choking, oral mucosal moisture and amount of unstimulated saliva were improved significantly after resumption of oral ingestion. The other investigated parameters did not significantly change, except for the streptococci in tongue coating, which significantly increased 1 week after oral ingestion recommencement, but decreased thereafter. CONCLUSION: After oral intake resumption, oral mucosal moisture and amount of unstimulated saliva were improved. However, because of a transitory increase in the counts of streptococci with oral ingestion recommencement, it is important to appropriately manage oral hygiene in these patients, according to the changes in their intraoral microbiota.

Correlation Between Stress Distributions and Biological Reactions in Bone Surrounding Implants That Support Cantilevers in Supraocclusal Contact in Rats.

PURPOSE: To investigate the relationship between stress distributions and peri-implant bone reactions around maxillary implants that support cantilevers in supraocclusal contact. MATERIALS AND METHODS: After molar extraction, 16 Wistar rats received a titanium implant unilaterally. After healing, 8 rats (control group) were killed and the others received implant-supported cantilever superstructures in supraocclusion (loaded group). After 5 days, they were killed. The maxillae of all rats were scanned by microcomputed tomography (µ-CT). Based on the µ-CT images, bone volumes were measured. For the loaded group, 3D finite element models were created and analyzed under 20-N vertical and 5-N lateral forces, successively. After µ-CT scanning, sections were prepared and observed histologically. RESULTS: When compared with the controls, the bone volume tended to decrease in the loaded group, but the difference was not statistically significant. On average, marginal bone resorption and stresses tended to be higher in 2 rats that occluded on the cantilever arm than in the others, which occluded right on the implant, nevertheless, calculated stress did not surpass the maximum elastic stress (yielding strength) of rat bone. However, at the implant-bone interface of these samples, partial bone resorption surrounded by signs of active resorption was histologically found. CONCLUSION: These findings suggest that in this occlusally loaded rat model, the stress distributions correlated to some extent with bone volume and morphological changes observed on µ-CT images and histological sections.

A proposed core curriculum for dental English education in Japan.

BACKGROUND: Globalization of the professions has become a necessity among schools and universities across the world. It has affected the medical and dental professions in terms of curriculum design and student and patient needs. In Japan, where medicine and dentistry are taught mainly in the Japanese language, profession-based courses in English, known as Medical English and Dental English, have been integrated into the existing curriculum among its 83 medical and 29 dental schools. Unfortunately, there is neither a core curriculum nor a model syllabus for these courses. METHODS: This report is based on a survey, two discussion forums, a workshop, and finally, the drafting of a proposed core curriculum for dental English approved by consensus of the participants from each university. RESULTS: The core curriculum covers the theoretical aspects, including dental English terms and oral pathologies; and practical aspects, including blended learning and dentist-patient communication. It is divided into modules and is recommended to be offered for at least two semesters. CONCLUSIONS: The core curriculum is expected to guide curriculum developers in schools where dental English courses are yet to be offered or are still in their early development. It may also serve as a model curriculum to medical and dental schools in countries in Asia, Europe, Africa, and Central and South America, where English is not the medium of instruction.

Finite element analysis of implant-embedded maxilla model from CT data: comparison with the conventional model.

PURPOSE: There are no entire maxillary finite element analysis models available, as a base of reference for the dimensions of conventional segment finite element analysis models. The objectives of this study were: (1) to construct a maxillary model derived from a human skull and to investigate the strain distribution around a posterior implant embedded in it; (2) to investigate the usability of conventional segment maxillary models. METHODS: CT DICOM data of a human dried skull maxilla was imported into the Mesh Generation Tools (ANSYS AI environment) and a computer-generated implant-abutment unit was bicortically embedded into it. In this Large model, Von Mises strains under axial and buccolingual loads were then calculated by a finite element program. Moreover, two simplified maxillary segments (Simplified models) were computer-generated and their Von Mises strains were similarly calculated. RESULTS: Although absolute values differed markedly, strain distribution patterns in the cortical bone were similar to those in the Simplified models: high Von Mises strains in the cortical bone concentrated in the sinus floor around the implant apex under axial load, and in the alveolar crest around the implant neck under buccolingual load. CONCLUSIONS: The simplified and segmented three-dimensional finite element models of the human maxilla showed the same locations of the highest equivalent strains as the full maxilla model created from CT DICOM data. If absolute strain values are not of interest, the Simplified models could be used in strain analyses of simulated posterior maxilla for diagnostic suggestions in implant placement.

Influence of maxillary cortical bone thickness, implant design and implant diameter on stress around implants: a three-dimensional finite element analysis.

PURPOSE: There is no clear evidence of the factors that could improve implant biomechanics in the posterior maxilla. Thus, a finite element analysis was performed to investigate the effect of maxillary cortical bone thickness, implant design and diameter on stress around implants. METHODS: A total of 12 models of the posterior maxilla with implant were computer-simulated by varying the thickness of the alveolar cortical bone (1.5, 1.0, 0.5 or 0 mm) and implant characteristics (cylindrical implant of 4.1-mm diameter, screw-type implants of 4.1-mm or 4.8-mm outer diameters). On top of each implant, forces were separately applied axially (100 N) and buccolingually (50 N), and the von Mises stresses were calculated. RESULTS: Regardless of load direction, implant design and diameter, cortical and cancellous bone stresses increased with the decrease of crestal cortical bone thickness. In the absence of crestal cortical bone, cancellous bone stresses were highest and, under axial load, were transferred to the sinus floor. Implant design and diameter influenced stress to a less extent, especially under buccolingual load and in the presence of crestal cortical bone. CONCLUSIONS: From a biomechanical viewpoint, to improve implant success odds in the posterior maxilla, rather than implant selection, careful preoperative evaluation of the cortical bone at the planned implant site is recommended. If this cortical bone is very thin or even lacking, implant treatment should be carried on with caution by progressive loading in the range of functional loads.

Peri-implant stress analysis in simulation models with or without trabecular bone structure.

Most 3-dimensional (3D) finite element analyses (FEAs) simplify the cancellous bone to a block and completely ignore its trabecular structure. Thus, a 3D FEA was performed to compare the peri-implant stress distribution of a model in which the trabecular structure was accurately simulated (precise model) with that of a model with a homogenous cancellous bone component (simplified model). In contrast to the simplified model, the distribution patterns and higher stresses in the precise model may explain the overall bone resorption at the implant-bone interface in load-related implant failures. Further studies using data from the jawbone and a more detailed implant simulation are planned.

Influence of superstructure materials on strain around an implant under 2 loading conditions: a technical investigation.

PURPOSE: This investigation was concerned with the effect of 3 superstructure materials on the strain around an implant under static and nonimpact dynamic loading. MATERIALS AND METHODS: Five highly filled composite resin-veneered crown analogs, 5 autopolymerized acrylic resin-veneered crown analogs, and 5 gold-alloy full cast crown analogs were prepared. The resin veneers were applied to gold-alloy frameworks. These crown analogs were prepared to fit an ITI implant-abutment assembly, which was screwed into a block of acrylic resin to simulate implantation in bone. The crown analogs were successively placed on the abutment, and a lateral load of 100 N was applied to the superstructure by a lever-type testing machine. Strains were recorded under static and dynamic loading by a 2mm-long strain gauge bonded to the surface of the bone simulant tangential to the implant. The dynamic load simulated masticatory cycles (75 strokes/min). RESULTS: Although the strain values differed significantly between the static and dynamic loading (P < .05), there was no significant difference among the superstructure materials under either loading condition (P > .05). DISCUSSION: These findings are in agreement with in vivo measurements, thus suggesting that cyclic rather than impact loading should be used in the investigation of occlusal material behavior under functional loading. CONCLUSION: Under static and nonimpact dynamic loading, the 3 superstructure materials tested (highly filled composite resin, acrylic resin, and gold alloy) had the same influence on the strain transmitted to a bone simulant that surrounded a single implant.

Biomechanical aspects of marginal bone resorption around osseointegrated implants: considerations based on a three-dimensional finite element analysis.

OBJECTIVES: Although bone loss around implants is reported as a complication when it progresses uncontrolled, resorption does not always lead to implant loss, but may be the result of biomechanical adaptation to stress. To verify this hypothesis, a three-dimensional finite element analysis was performed and the influence of marginal bone resorption amount and shape on stress in the bone and implant was investigated. MATERIAL AND METHODS: A total of nine bone models with an implant were created: a non-resorption (Base) model and eight variations, in which three different resorption depths were combined with pure vertical or conical (vertical-horizontal) resorption. Axial and buccolingual forces were applied independently to the occlusal node at the center of the superstructure. RESULTS: Regardless of load direction, bone stresses were higher in the pure vertical resorption (A) models than in the Base model, and increased with resorption depth. However, cortical bone stress was much lower in the conical resorption models than in both the Base and A models of the same resorption depth. An opposite tendency was observed in the cancellous bone under buccolingual load. Under buccolingual load, highest stress in the implant increased linearly with the resorption depth for all the models and its location approached the void existing below the abutment screw. CONCLUSIONS: The results of this analysis suggest that a certain amount of conical resorption may be the result of biomechanical adaptation of bone to stress. However, as bone resorption progresses, the increasing stresses in the cancellous bone and implant under lateral load may result in implant failure.

Influence of implant design and bone quality on stress/strain distribution in bone around implants: a 3-dimensional finite element analysis.

PURPOSE: A 3-dimensional finite element analysis was performed to evaluate the influence of implant type and length, as well as that of bone quality, on the stress/strain in bone and implant. MATERIALS AND METHODS: Two types (screw and cylinder) and 4 lengths (9.2, 10.8, 12.4, and 14.0 mm) of titanium implants were buried in 4 types of bone modeled by varying the elastic modulus for cancellous bone. Axial and buccolingual forces were applied to the occlusal node at the center of the abutment. RESULTS: Regardless of load direction, maximum equivalent stress/strain in bone increased with a decrease in cancellous bone density. Under axial load, especially in the low-density bone models, maximum equivalent strain in cancellous bone was lower with the screw-type implant than with the cylinder-type implant. It was also lower with the longer implants than with the shorter implants. Under buccolingual load, equivalent stress/strain was influenced mainly by bone density. DISCUSSION: This study confirms the importance of bone quality and its presurgical diagnosis for implant long-term prognosis. Implant length and type can also influence bone strain, especially in low-density bone. CONCLUSIONS: The results of this study suggest that cancellous bone of higher rather than lower density might ensure a better biomechanical environment for implants. Moreover, longer screw-type implants could be a better choice in a jaw with cancellous bone of low density.

Fatigue resistance of two implant/abutment joint designs.

STATEMENT OF PROBLEM: Because of reported mechanical failures, alternative implant system components with suggested optimized strength have been manufactured. However, the endurance of these products has not been well investigated. PURPOSE: This study was designed to assess the effect of joint design on the fatigue strength and failure mode of 2 single-tooth implant systems: Brånemark and ITI, in which a hex mediated-butt joint and 8-degree internal conical implant/abutment interface are used, respectively. MATERIALS AND METHODS: Seven 10-mm implants from each implant system were embedded to a depth of 7 mm in cylindrical acrylic resin blocks. CeraOne and Solid abutments with cement-retained castings were assembled to the Brånemark and ITI implants, respectively. The assembled units were mounted in a lever-type-testing machine that was equipped with an automatic counting device and shutoff sensors, enabling the recording of the number of cycles till failure. A cyclic load of 100 N was applied perpendicular to the long axis of the assemblies at a rate of 75 cycles/min. To investigate specimen resistance to fatigue during 6 years of simulated function, a target of 1,800,000 cycles was defined. Specimen preparation and testing was performed by the same operator. The association of the joint design with the occurrence of failure was verified by Fisher's exact probability test (P<.05). RESULTS: For the Brånemark group, the gold alloy abutment screw in all specimens fractured between 1,178,023 and 1,733,526 cycles with a standard deviation of 224,477 cycles. For the ITI group, all specimens had no failure until 1,800,000 cycles. Statistical analysis showed a highly significant difference between the 2 groups (P=.000582). CONCLUSIONS: Within the limitations of this in vitro study, the effect of joint design on the fatigue strength and failure mode of the ITI single tooth implant system was significantly better (P>.001) than the Brånemark single-tooth implant system tested.