Increasing Chemical Diversity of B2 N2 Anthracene Derivatives by Introducing Continuous Multiple Boron-Nitrogen Units.

Increasing the chemical diversity of organic semiconductors is essential to develop efficient electronic devices. In particular, the replacement of carbon-carbon (C-C) bonds with isoelectronic boron-nitrogen (B-N) bonds allows precise modulation of the electronic properties of semiconductors without significant structural changes. Although some researchers have reported the preparation of B2 N2 anthracene derivatives with two B-N bonds, no compounds with continuous multiple BN units have been prepared yet. Herein, we report the synthesis and characterization of a B2 N2 anthracene derivative with a BNBN unit formed by converting the BOBN unit at the zigzag edge. Compared to the all-carbon analogue 2-phenylanthracene, BNBN anthracene exhibits significant variations in the C-C bond length and a larger highest occupied molecular orbital-lowest unoccupied molecular orbital energy gap. The experimentally determined bond lengths and electronic properties of BNBN anthracene are confirmed through theoretical calculations. The BOBN anthracene organic light-emitting diode, used as a blue host, exhibits a low driving voltage. The findings of this study may facilitate the development of larger acenes with multiple BN units and potential applications in organic electronics.

Kinetic-Controlled Crystallization of α-FAPbI3 Inducing Preferred Crystallographic Orientation Enhances Photovoltaic Performance.

Crystallization kinetic controls the crystallographic orientation, inducing anisotropic properties of the materials. As a result, preferential orientation with advanced optoelectronic properties can enhance the photovoltaic devices' performance. Although incorporation of additives is one of the most studied methods to stabilize the photoactive α-phase of formamidinium lead tri-iodide (α-FAPbI3 ), no studies focus on how the additives affect the crystallization kinetics. Along with the role of methylammonium chloride (MACl) as a "stabilizer" in the formation of α-FAPbI3 , herein, the additional role as a "controller" in the crystallization kinetics is pointed out. With microscopic observations, for example, electron backscatter diffraction and selected area electron diffraction, it is examined that higher concentration of MACl induces slower crystallization kinetics, resulting in larger grain size and [100] preferred orientation. Optoelectronic properties of [100] preferentially oriented grains with less non-radiative recombination, a longer lifetime of charge carriers, and lower photocurrent deviations in between each grain induce higher short-circuit current density (Jsc ) and fill factor. Resulting MACl40 mol% attains the highest power conversion efficiency (PCE) of 24.1%. The results provide observations of a direct correlation between the crystallographic orientation and device performance as it highlights the importance of crystallization kinetics resulting in desirable microstructures for device engineering.

Hole-Transporting Vanadium-Containing Oxide (V2O5-x) Interlayers Enhance Stability of α-FAPbI3-Based Perovskite Solar Cells (∼23%).

Perovskite solar cells (PSCs) have attracted tremendous interest due to their outstanding intrinsic photovoltaic properties, such as absorption coefficients, exciton binding energies, and long carrier lifetimes. Although the power conversion efficiency (PCE) of PSCs is close to the Si solar cells' PCE, device stability remains a challenge. In particular, the device stability is more critical in n-i-p normal structured PSCs, which show a higher efficiency than p-i-n inverted ones, simply because of the much lower stability of 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spi). To prevent the devices from degrading performances arising both from perovskite's degradation and Spi instability, we prepare atomic layer deposition (ALD)-grown transition metal oxides for hole transport with efficient n-i-p PSCs. We demonstrate low-temperature (Tdep = 45 °C)-grown amorphous ALD-V2O5-x with oxygen-deficient traps on top of Spi as an interlayer, which prevents the devices' degradation in performance. By blocking moisture and oxygen, ALD-V2O5-x was able to greatly improve the devices' stability by preserving the photovoltaic α-FAPbI3 phase while suppressing both Li ion diffusion from the additive and Au ions from the electrode. As a result, we successfully fabricate PSCs with passivation/hole-transporting bifunctional Spi/ALD-V2O5-x interlayers without sacrificing photovoltaic performances, and the device stability is significantly improved.

Influence of Chewing Ability on Elderly Adults' Cognitive Functioning: The Mediating Effects of the Ability to Perform Daily Life Activities and Nutritional Status.

Chewing ability is also related to activities of daily living (ADLs) and nutritional status; however, these associations have not been firmly established. We examined chewing ability as a predictor variable and explored its relationship with cognitive functioning as mediated by ADLs and nutritional status data were collected by face-to-face interviews. Patients were receiving home healthcare service in Mun-gyeong city, Gyung-buk, Korea. Participants comprised 295 patients aged 81.35 ± 6.70 years. Structural equation modeling (SEM) was performed using AMOS 18.0 (SPSS Inc., Chicago, IL, USA). The model fit was based on absolute fit index and incremental fit index. Data were collected to assess cognitive functioning (using the Korean version of the Mini-Mental Status Examination for dementia screening (MMSE-DS)), ADL, a mini-nutritional assessment (MNA) questionnaire, and a chewing ability test. Participants with better chewing ability had significantly better cognitive functioning, ADLs, and nutritional status (p < 0.001). Chewing ability directly affected cognitive functioning and indirectly affected how ADLs and MNA affected MMSE-DS. Chewing ability is an important factor influencing the cognitive functioning of elderly adults in Korea, both directly and indirectly through mediating variables such as nutritional status and ADLs. Efforts to help older adults maintain their chewing ability are necessary for preventing cognitive impairment.

Unusual Hole Transfer Dynamics of the NiO Layer in Methylammonium Lead Tri-iodide Absorber Solar Cells.

Nickel oxides (NiO) as hole transport layers (HTLs) in inverted-type perovskite solar cells (PSCs) have been widely studied mainly because of their high stability under illumination. Increases in the power conversion efficiency (PCE) with NiO HTLs have been presented in numerous reports, although the photoluminescence (PL) quenching behavior does not coincide with the PCE increase. The dynamics of the charge carrier transport between the NiO HTLs and the organic-inorganic halide perovskite absorbers is not clearly understood yet and quite unusual, in contrast to organic/polymerics HTLs. We deposited NiO HTLs with precisely controlled thicknesses by atomic layer deposition (ALD) and studied their photovoltaic performances and hole transfer characteristics. Ground state bleaching (GSB) recovery was observed by ultrafast transient absorption spectroscopy (TAS), which suggested that backward hole injection occurred between the perovskites and NiO HTLs, so that the uncommon PL behaviors can be clearly explained. Backward hole injection from the NiO HTL to the perovskite absorber originated from their similar valence band (VB) energy positions. The thickness increase of the NiO HTLs induced VB sharing, which caused a red-shift of the photoinduced hole absorption spectrum in near-infrared (NIR) femtosecond TAS and a decrease in the PL intensity. Our studies on inorganic metal oxide transport layers, NiO in this work, with a thickness dependence and the comparison with organic layers provide a better understanding of the interfacial carrier dynamics in PSCs.

Atomic layer deposition for efficient and stable perovskite solar cells.

Organic-inorganic hybrid metal halides are now the most attractive photovoltaic absorber materials, typically, methylammonium lead triiodides (MAPbI3). These unique semiconducting materials as absorbers demonstrate a remarkably improved power conversion efficiency of over 20% and now with a certified efficiency of 23.3%. Considering the Shockley-Queisser limit and their bandgaps, there is still much room to increase the efficiency. Stable devices with reproducibility and long-term use are essential for their commercialization. Atomic layer deposition (ALD) is a powerful technique to deposit high-quality thin films with excellent thickness accuracy and conformality, as well as with no pin-holes in a large area at low temperatures. ALD could be an ideal tool for efficient and stable perovskite solar cells. In particular, ALD will emerge for the production of tandem as well as flexible solar cells. This review contains the following recent research topics; underlying charge transport layers onto transparent conducting oxides (TCO), interfacial layers, overlying electron transport layers (ETLs), and encapsulation techniques utilized by ALD. Several extended understandings by recent studies and challenges toward further enhancing the efficiency and stability will be addressed.

Atomic layer deposition of a SnO2 electron-transporting layer for planar perovskite solar cells with a power conversion efficiency of 18.3.

High-efficiency planar type perovskite solar cells were fabricated by atomic layer deposition (ALD) of SnO2 and subsequent annealing at 180 °C. As-dep. SnO2 layers prepared by post-annealing at 180 and 300 °C, respectively, were used as electron transporting layers (ETLs). ALD-TiO2 layers were also prepared by post annealing at 400 °C, and the thicknesses of all ETLs were around 12 nm. PL quenching, optical band gap measurement, UPS, and conductive AFM results show that SnO2 can more appropriately be used as an ETL compared to TiO2.

Perovskite Solar Cells with Inorganic Electron- and Hole-Transport Layers Exhibiting Long-Term (≈500 h) Stability at 85 °C under Continuous 1 Sun Illumination in Ambient Air.

Despite the high power conversion efficiency (PCE) of perovskite solar cells (PSCs), poor long-term stability is one of the main obstacles preventing their commercialization. Several approaches to enhance the stability of PSCs have been proposed. However, an accelerating stability test of PSCs at high temperature under the operating conditions in ambient air remains still to be demonstrated. Herein, interface-engineered stable PSCs with inorganic charge-transport layers are shown. The highly conductive Al-doped ZnO films act as efficient electron-transporting layers as well as dense passivation layers. This layer prevents underneath perovskite from moisture contact, evaporation of components, and reaction with a metal electrode. Finally, inverted-type PSCs with inorganic charge-transport layers exhibit a PCE of 18.45% and retain 86.7% of the initial efficiency for 500 h under continuous 1 Sun illumination at 85 °C in ambient air with electrical biases (at maximum power point tracking).

Factors affecting use of word-of-mouth by dental patients.

OBJECTIVES: Word-of-mouth (WOM) refers to communication among consumers, which greatly influences the marketing strategies of dental clinics. This study aimed to explore factors that affect use of WOM by dental patients and to analyse their pathways. METHODS: The participants were 520 outpatients from four private dental clinics. Data were obtained from a survey using self-reported questionnaires, which included questions regarding seven latent variables: five exogenous variables, including medical service quality (physical environment, customer service, patient relationship quality) and individual characteristic variables (opinion leader tendency, social hub tendency); and two endogenous variables (intention to recommend, WOM experience). Statistical analysis was performed using structural equation modelling. RESULTS: Significant associations were found in the pathways between relationship quality and intention to recommend, intention to recommend and WOM, and opinion leader tendency and WOM (P < 0.001). Higher patient relationship quality and higher intention to recommend were related to positive WOM, as was higher opinion leader tendency. CONCLUSIONS: Improving patient relationship quality can promote positive WOM for dental clinics. Strategies are needed to promote a positive perception of dental clinics by effectively responding to the views of patients with strong opinion leader tendencies.

p-Type CuCrO2 particulate films as the hole transporting layer for CH3NH3PbI3 perovskite solar cells.

CuCrO2 with a crystal structure of delafossite is a promising material as a transparent conducting oxide. It shows unique properties, for example, wide band gap, good chemical stability, and p-type carrier transporting character. The oxide layers with delafossite structure have been suggested as hole transporting materials for organic-inorganic CH3NH3PbI3 perovskite solar cells. In this study, we fabricated inverted (p-i-n) type planar perovskite solar cells with CuCrO2 nanoparticles synthesized by the hydrothermal method and their films were formed by spin-coating without any further heat treatment. The champion device gave a 13.1% of power conversion efficiency and CuCrO2 based devices show improved stability in ambient air compared with the standard PEDOT:PSS based perovskite solar cells.

Dental amalgam exposure can elevate urinary mercury concentrations in children.

OBJECTIVES: Owing to its cost-effectiveness and operative convenience, dental amalgam remains in use as a restorative material for tooth caries in children in many countries. The aim of this study was to evaluate the relationship between dental amalgam exposure and urinary mercury (U-Hg) concentrations in children. METHODS: In this longitudinal study, 463, 367 and 348 children, 8-11 years of age, were evaluated at baseline, and at the first and second follow-up visits, respectively. The interval between each survey was 6 months. For the oral examination and urine sample, the amalgam-filled tooth surface (TS), and U-Hg and creatinine concentrations of participants were determined, and the cumulative amalgam-filled TS and cumulative creatinine-adjusted U-Hg were calculated. To assess potential covariates, socio-demographic factors, oral health behaviour and dietary factors were surveyed by questionnaire. Data were analysed by the t-test, correlation analysis and mixed-model analysis. The statistical analyses were performed using SPSS 18.0. RESULTS: Children with more than one amalgam-filled TS exhibited significantly higher creatinine-adjusted U-Hg concentrations than those without, in all three survey periods (P < 0.001). The results for the current and cumulative amalgam-filled TS significantly correlated with those for the current and cumulative creatinine-adjusted U-Hg concentration, respectively, in all surveys (P < 0.001). In the repeated-measures mixed model analysis, current and cumulative amalgam-filled TS was significantly related to current and cumulative creatinine-adjusted U-Hg concentration, respectively (P < 0.001). CONCLUSIONS: Amalgam-filled TS was significantly correlated with U-Hg concentrations in children. Therefore, dental amalgam exposure can affect the systemic mercury concentration in children.

Efficacy of various cleaning solutions on saliva-contaminated zirconia for improved resin bonding.

PURPOSE: This study aimed to investigate the efficacy of cleaning solutions on saliva-contaminated zirconia in comparison to air-abrasion in terms of resin bonding. MATERIALS AND METHODS: For saliva-contaminated airabraded zirconia, seven cleaning methods)-no contamination (NC), water-spray rinsing (WS), additional airabrasion (AA), and cleaning with four solutions (Ivoclean [IC]; 1.0 wt% sodium dodecyl sulfate [SDS], 1.0 wt% hydrogen peroxide [HP], and 1.0 wt% sodium hypochlorite [SHC])-were tested. The zirconia surfaces for each group were characterized using various analytical techniques. Three bonded resin (Panavia F 2.0) cylinders (bonding area: 4.5 mm(2)) were made on one zirconia disk specimen using the Ultradent jig method [four disks (12 cylinders)/group; a total of 28 disks]. After 5,000 thermocycling, all specimens were subjected to a shear bond strength test with a crosshead speed of 1.0 mm/minute. The fractured surfaces were observed using an optical and scanning electron microscope (SEM). RESULTS: Contact angle measurements showed that groups NC, AA, IC, and SHC had hydrophilic surfaces. The X-ray photoelectron spectroscopy (XPS) analysis showed similar elemental distributions between group AA and groups IC and SHC. Groups IC and SHC showed statistically similar bond strengths to groups NC and AA (P>.05), but not groups SDS and HP (P<.05). For groups WS, SDS, and HP, blister-like bubble formations were observed on the surfaces under SEM. CONCLUSION: Within the limitations of this in vitro study, some of the cleaning solutions (IC or SHC) were effective in removing saliva contamination and enhancing the resin bond strength.

Burnout and its related factors in Korean dentists.

OBJECTIVES: Dentistry has been identified as one of the most stressful work environments. Knowledge of modifiable work-environment factors related to job stress could lead to a strategy and policy to provide a better work environment for dentists. The aims of this study were to examine the degree and distribution of burnout and to determine the factors associated with burnout subscale of Korean dentists. METHODS: A cross-sectional survey of Korean dentists was conducted using a custom-designed and validated questionnaire that incorporated the Maslach Burnout Inventory Human Services Survey (MBI-HSS) as well as questions regarding sociodemographic and job-related characteristics. A random sample of 1,000 dentists was selected from 13,207 registered dentists in the Korean Dental Association. The MBI-HSS scores were summarised in the three dimensions of emotional exhaustion, depersonalisation, and personal sense of accomplishment. Bivariate and multivariate analyses were conducted to assess the prevalence of burnout and its related factors. RESULTS: The adjusted response rate was 45.9% (444/967). In the subscales of burnout, 41.2%, 55.9%, and 41.4% of respondents scored highly in emotional exhaustion and depersonalisation and poorly for personal sense of accomplishment, respectively. High burnout seems to be more likely to occur in association with some of the sociodemographic and job-related characteristics, especially younger age, male gender, without occupational calling, and unwilling to reselect a dentistry as a job. CONCLUSIONS: This study suggests that burnout is a common problem in Korean dentists and that occupational calling and willing to reselect a dentistry as a job are important factors for managing burnout.

Bone healing with oxytocin-loaded microporous ß-TCP bone substitute in ectopic bone formation model and critical-sized osseous defect of rat.

AIM: This study investigated the efficacy of the hypothalamic nonapeptide oxytocin (OT) by direct delivery to local defects using a microporous ß-tricalcium phosphate (TCP) as the carrier for the future applications as a method to achieve predictable bone regeneration of large osseous defects requiring sinus bone graft and guided bone regeneration procedures for implant placement. MATERIAL AND METHODS: Both the ectopic and new bone formation induced by the OT-loaded microporous ß-TCP powder was histomorphometrically compared with unloaded ß-TCP in a subcutaneous ectopic bone formation model and calvarial critical-sized defects (CSDs) in 45 rats. RESULTS: The OT-loaded ß-TCP clearly enhanced ectopic bone formation compared with the unloaded control group. A High initial OT dose (250 µg) significantly increased ectopic bone formation at an early healing time-point compared with a lower OT dose (50 µg). The OT-loaded samples displayed greater new bone formation in the rat calvarial CSDs. Extensive new bone formation was achieved in the calvarial CSDs with the higher OT dose. CONCLUSION: These results suggest that local OT delivery to bone substitute promotes new bone formation via an osteoinductive mode of action.

Osseointegration of commercial microstructured titanium implants incorporating magnesium: a histomorphometric study in rabbit cancellous bone.

OBJECTIVE: Recent studies have suggested that magnesium (Mg) ions exert a beneficial effect on implant osseointegration. This study assessed the osseointegration of nanoporous titanium (Ti) surface incorporating the Mg produced by hydrothermal treatment in rabbit cancellous bone to determine whether this surface would further enhance bone healing of moderately rough-surfaced implants in cancellous bone, and compared the result with commercially available micro-arc oxidized Mg-incorporated implants. MATERIAL AND METHODS: The Mg-incorporated Ti surfaces (RBM/Mg) were obtained by hydrothermal treatment using an alkaline Mg-containing solution on grit-blasted moderately rough (RBM) implants. Untreated RBM and recently introduced Mg-incorporated microporous Ti implants produced by micro-arc oxidation (M) were used controls in this study. The surface characteristics were evaluated by scanning electron microscopy, X-ray photoelectron spectroscopy and optical profilometry. Twenty-four threaded implants with a length of 10 mm (eight RBM implants, eight RBM/Mg implants and eight M implants) were placed in the femoral condyles of 12 New Zealand White rabbits. Histomorphometric analysis was performed 4 weeks after implantation. RESULTS: Hydrothermally treated and untreated grit-blasted implants displayed almost identical surface morphologies and R(a) values at the micron-scale. The RBM/Mg implants exhibited morphological differences compared with the RBM implants at the nano-scale, which displayed nanoporous surface structures. The Mg-incorporated implants (RBM/Mg and M) exhibited more continuous bone apposition and a higher degree of bone-to-implant contact (BIC) than the untreated RBM implants in rabbit cancellous bone. The RBM/Mg implants displayed significantly greater BIC% than untreated RBM implants, both in terms of the all threads region and the total lateral length of implants (P<0.05), but no statistical differences were found between the RBM/Mg and M implants except BIC% values in total lateral length. CONCLUSION: These results indicate that a nanoporous Mg-incorporated surface may be effective in enhancing the osseointegration of moderately rough grit-blasted implants by increasing the degree of bone-implant contact in areas of cancellous bone.

The effect of intensive oral hygiene care on gingivitis and periodontal destruction in type 2 diabetic patients.

PURPOSE: This study aimed to investigate the effects of oral hygiene care by oral professionals on periodontal health in type 2 diabetes mellitus patients. MATERIALS AND METHODS: Diabetic participants were recruited at a university hospital and matched at a 1:1 ratio by age and gender, and randomly allocated into intervention (40 people) and control groups (35 people). Tooth brushing instruction, oral health education, and supra-gingival scaling were implemented in all patients at baseline. This program was repeatedly conducted in intervention patients every month for 6 months, and twice at baseline and the sixth month in the control. Oral health was measured by decayed, missing, and filled teeth (DMFT), plaque index, calculus index, bleeding index, patient hygiene performance (PHP) index, tooth mobility, Russel's periodontal index, and community periodontal index (CPI). Diabetes-related factors, oral and general health behaviors, and sociodemographic factors were interviewed as other confounding factors. An analysis of covariance (ANCOVA) was used with SPSS for Windows 14.0. RESULTS: At baseline, there were no significant differences between the two groups in average of periodontal health (calculus index, bleeding index, Russel's periodontal index, CPI, and tooth mobility), diabetes-related factors (fasting blood glucose, postprandial blood glucose, and HbA1c), and in distribution of sociodemographic factors and health behaviors. In intervention group, plaque index, dental calculus index, bleeding index, and PHP index were reduced fairly and steadily from the baseline. There were significant differences in plaque index, dental calculus index, bleeding index, PHP index, and Russel's periodontal index between the two groups at sixth month after adjusted for baseline status. CONCLUSION: Intensive oral hygiene care can persistently improve oral inflammation status and could slow periodontal deterioration.

Morphological changes in Streptococcus mutans after chewing gum containing xylitol for twelve months.

Few studies have been conducted to evaluate the effect of xylitol on the virulence and morphology of Streptococcus mutans (S. mutans). This study was conducted to evaluate changes in the morphology and virulence of S. mutans in response to long-term consumption of gum containing xylitol. Participants were voluntarily recruited for a women's oral health prevention program, classified into two groups (a control and a xylitol group), and then followed for 1 year. Ten salivary samples were randomly selected from each group. Colony count, field emission scanning electron microscopy, and real-time reverse transcription polymerase chain reaction were used to analyze the characteristics of S. mutans. In the xylitol group, the colony counts of S. mutans decreased steadily over time. In addition, the adherence of the colonies in the xylitol group became weak, and the size of the colonies decreased compared to the control. The secretion of sticky substances from the surface of S. mutans colonies and gtfB gene expression also decreased in the xylitol group. These findings indicate that regular chewing of xylitol gum over a long period may lead to decreased gtfB expression, which can negatively affect the synthesis of extracellular polysaccharides by S. mutans, which could reduce the size and growth of S. mutans colonies and change their morphology as a result.

Density of the alveolar and basal bones of the maxilla and the mandible.

INTRODUCTION: The purpose of this investigation was to quantitatively evaluate density of the alveolar and basal bones of the maxilla and the mandible. METHODS: Sixty-three sets of computed tomographic (CT) images were selected, and bone density was measured with V-Works imaging software (Cybermed, Seoul, Korea). The sample consisted of 23 men (ages, 29 +/- 10.9 years) and 40 women (ages, 25.6 +/- 7.6 years). Cortical and cancellous bone densities at the alveolar and basal bones at the incisor, canine, premolar, molar, and maxillary tuberosity/retromolar areas were measured. RESULTS: The cortical bone density of the maxilla ranged approximately between 810 and 940 Hounsfield units (HU) at the alveolar bone except for the maxillary tuberosity (443 HU at the buccal and 615 HU at the palatal alveolar bone), and between 835 and 1113 HU at the basal cortical bone except for tuberosity (542 HU). The cortical bone density of the mandible ranged between 800 and 1580 HU at the alveolar bone and 1320 and 1560 HU at the basal bone. The highest bone density in the maxilla was observed in the canine and premolar areas, and maxillary tuberosity showed the lowest bone density. Density of the cortical bone was greater in the mandible than in the maxilla and showed a progressive increase from the incisor to the retromolar area. CONCLUSIONS: These data might provide valuable information when selecting sites and placement methods for miniscrew or microscrew implants in the dental arch.

Xenon light has effectiveness on the detection of incipient carious lesions on bovine enamel in vitro.

OBJECTIVE: Filtered 325-nm xenon light was used to test its effectiveness in the detection of incipient carious lesions on bovine enamel by measuring the fluorescence spectrum. BACKGROUND DATA: The combination of early detection with new interventional methodology and caries management will be the preferred dental practice in the future. METHODS: Specimens of bovine tooth enamel were embedded in resin, polished, exposed to a lactate carbopol buffer system for 71 hours, and randomly divided into one control and three test groups of 10 specimens each, with Vickers hardness number (VHN) stratification. The surface changes were characterized by atomic force microscopy. All specimens were irradiated with xenon light, and a fluorescence spectrum was produced. Characteristics of fluorescence among the demineralized tooth groups were measured using an optical multichannel analyzer and a confocal laser scanning microscope. RESULTS: The VHNs were significantly different among the four groups (p < 0.05). The fluorescence had a peak intensity of approximately 425 nm, and the slope value between 450 and 550 nm was significantly decreased in all test groups (groups II-IV) compared to the control group (group I), as the VHN decreased (p < 0.05). Demineralized lesion depth gradually increased to 30-40 microm in groups II-IV. CONCLUSIONS: The 325-nm xenon light resulted in high efficacy for detecting incipient carious lesions. By evaluating the highest peak and slope value, the incipient carious lesion may be detected.

Factors related to job satisfaction among South Korean dentists.

OBJECTIVES: The purposes of this study were to investigate the level and distribution of job satisfaction and to explore work environment factors associated with job satisfaction of South Korean dentists. METHODS: A stratified systematic random sample of 1029 dentists was selected from the 10 357 registered dentists in the Korean Dental Association. They were surveyed via a self-administered mail questionnaire. Job satisfaction was measured by a modified version of the Dentist Satisfaction Survey. RESULTS: The response rate was 62.2%. The mean score of overall job satisfaction among South Korean dentists was 3.2 out of 5. In terms of work environment factors, the most satisfying aspect was patient relations (3.7) and the least satisfying aspect was personal time (2.8). Multiple regression analysis identified a model including patient relations, perception of income, personal time, staff, and specialty training that accounted for 35% of variation in overall job satisfaction. The majority of the variance was explained by patient relations. CONCLUSIONS: This study suggests that patient relations, perception of income, personal time, staff, and specialty training are important work environment factors for job satisfaction among South Korean dentists. The findings of this study will be helpful to policy makers to design plans to increase the level of job satisfaction among South Korean dentists.