Dentin anti-demineralization potential of surface reaction-type pre-reacted glass-ionomer filler containing self-adhesive resin cement.

OBJECTIVE: To investigate the anti-demineralization potential of a newly developed surface reaction-type pre-reacted glass-ionomer (S-PRG) filler containing self-adhesive resin cement against acidic attacks on the dentin surface. MATERIALS AND METHODS: A total of 32 bovine teeth were used. Cavities were prepared on crown dentin slaps and filled with three self-adhesive resin cement: (1) S-PRG-based cement, (2) Si-based cement, and (3) RelyX cement. Specimens were then subjected to pH cycling for 28 days, and the depth of demineralization was assessed using swept-source optical coherence tomography (SS-OCT) after 7, 14, 21, and 28 days. Sixty-four root dentin blocks were divided into four groups and then subjected to a pH cycling procedure with the aforementioned three material blocks and one negative control. The mineral loss was observed using transverse microradiography (TMR), and the surface microhardness (SMH) test was conducted to investigate the mechanical properties of treated dentin surfaces. RESULTS: The depth of demineralization for the S-PRG-based cement was significantly lower than that of the Si-based cement after 7, 21, and 28 days. Conversely, the RelyX cement was not significantly different from the Si-based cement after 7, 14, and 21 days (p < 0.05). Regarding the TMR and SMH test, the S-PRG-based cement showed the least mineral loss with the highest resistance to acidic challenge. CONCLUSION: The S-PRG filler containing resin cement can reduce mineral loss and promote remineralization of dentin substrate and has the potential to preserve dentin integrity and resist acidic attack. Clinical significance Self-adhesive resin cement containing S-PRG fillers maintained the surface integrity of dentin after exposure to 28 days of acidic challenge with a significant anti-demineralization effect.

Swept-source optical coherence tomographic observation on prevalence and variations of cemento-enamel junction morphology.

To investigate the prevalence of different patterns of cemento-enamel junction (CEJ) morphology under swept-source optical coherence tomography (SS-OCT). One hundred extracted human teeth were used consisting of incisors, premolars, and molars. Each sample was observed for every 500 µm circumferentially along CEJ and OCT images of the pattern were noted. Microscopic observations were done for the representative sample using confocal laser scanning microscope (CLSM) and transmission electron microscope (TEM). The OCT images exhibited four CEJ patterns: edge-to-edge (type I), exposed dentin (type II), cementum overlapping enamel (type III), and enamel overlapping cementum (type IV). The prevalence of CEJ patterns was further statistically considered for mesial, distal, buccal, and lingual surfaces. The real-time imaging by SS-OCT instantly determined CEJ morphology. CLSM and TEM observation revealed morphological features along CEJ, which corresponded to OCT images of CEJ anatomy. OCT results showed 56.8% of type I pattern predominantly found on proximal surfaces, followed by 36.5% of type II pattern on buccal and lingual surface, 6.4% of type III pattern, and 0.3% of type IV pattern. There was a significant difference in prevalence of CEJ patterns among different types of teeth, but there was no statistically significant difference among the four surfaces in each type of teeth. OCT is a non-invasive diagnostic tool to examine the CEJ patterns along the entire circumference. OCT observation revealed even minor dentin exposure that would need clinical and home procedures to prevent any symptoms.

Diagnosis of Occlusal Tooth Wear Using 3D Imaging of Optical Coherence Tomography Ex Vivo.

The aim of this study was to assess the utility of 3D imaging of optical coherence tomography (OCT) for the diagnosis of occlusal tooth wear ex vivo. Sixty-three extracted human molars with or without visible tooth wear were collected to take digital intraoral radiography and 3D OCT images. The degree of tooth wear was evaluated by 12 examiners and scored using 4-rank scale: 1-slight enamel wear; 2-distinct enamel wear; 3-tooth wear with slight dentin exposure; 4-tooth wear with distinct involvement of dentin. The degree of tooth wear was validated by the histological view of confocal laser scanning microscopy (CLSM). The sensitivity, specificity, and area under the curve (AUC) of receiver operating characteristic analysis were calculated. Diagnostic accuracy was compared with the agreement with CLSM observation using weighted kappa. The results were statistically analyzed at a significance level of α = 0.05. Three-dimensional OCT showed significantly higher sensitivity (p < 0.05) for all the diagnostic thresholds of enamel wear and dentin exposure than digital radiography (0.82, 0.85, and 0.79 vs. 0.56, 0.52, and 0.57, respectively). Three-dimensional OCT showed higher AUC and kappa coefficients than digital radiography (p < 0.05), where mean AUC and Kappa values were 0.95 and 0.76 for OCT and 0.92 and 0.47 for radiography, respectively. No significant difference of specificity was observed (p > 0.05). Three-dimensional OCT could visualize and estimate the degree of tooth wear and detect the dentin exposure at the tooth wear surface accurately and reproducibly. Consequently, a new guideline for tooth wear assessment can be proposed using OCT.

Effect of lights with various wavelengths on bleaching by 30% hydrogen peroxide.

The objective of this study was to evaluate the bleaching effect of light sources with various wavelengths using 30% hydrogen peroxide (HP) in vitro. The hematoporphyrin-stained paper was bleached with HP and irradiated for 10 min using LED light sources with 265, 310, 365, 405, or 450 nm respectively. In control group, HP was applied for 10 min without light irradiation. The bleaching procedure was repeated two times. The L*a*b* values of the samples before bleaching and after each bleaching step were measured using a colorimeter. Color changes of specimens were then calculated and statistically analyzed. There was an interaction between light sources and time of irradiation in the color change (p < 0.05). Time and light sources significantly affected ΔE and ΔL (p < 0.05). The light source of 256 nm showed the highest bleaching effect over time followed by that of 310 nm, which were statistically different from other groups (p < 0.001). The 365 nm, 450 nm groups, and control group showed low bleaching effect visually with no significant differences in ΔE and ΔL (p > 0.05). It was concluded that the wavelengths of the light sources affected the bleaching by HP. The 310-nm light can be a potential source for bleaching.

Effects of UVB and UVC irradiation on cariogenic bacteria in vitro.

The aim of this study was to evaluate the bactericidal effect of ultraviolet (UV) light at 265-nm (UVC) and 310-nm (UVB) wavelengths from a newly developed UV light-emitting diode (LED) device against cariogenic bacteria in vitro. Suspensions of Streptococcus mutans (S. mutans) and Streptococcus sobrinus were directly irradiated by UVB or UVC for 2.5 min or 5 min. Numbers of colonies were counted and calculated as colony forming units (CFU) per milliliter. Fluorescence microscopy (FM) and optical density measurements at 490 nm (OD490) were also taken after irradiation. In addition, the bactericidal effects of irradiation against S. mutans under 0.5 mm-thick dentin were compared using culture tests and OD490 measurements. Direct UV-LED irradiation with both UVB and UVC showed strong bactericidal effects. UVB showed superior bactericidal effect through 0.5-mm-thick dentin than did UVC, especially after demineralization. These results suggest that UVB irradiation could be utilized for the prevention and management of dental caries.

Remineralization capacity of carious and non-carious white spot lesions: clinical evaluation using ICDAS and SS-OCT.

OBJECTIVES: To assess the remineralization capacity of carious, non-carious, and combined white spot lesions (WSLs) using the ICDAS and SS-OCT. MATERIALS AND METHODS: This clinical trial was based on a quasi-experimental design. Forty-two healthy subjects (median age 26.6 years), who visited university hospital and had at least one WSL with an ICDAS score of 2 or 1, were recruited. The subjects chewed a non-blind sugar-free gum containing bioavailable calcium and fluoride for 3 months. The remineralization capacities of carious and non-carious 121 WSLs were assessed using ICDAS by two calibrated non-blind examiners and optical boundary depth (BD) by SS-OCT at a monthly recall. The outcome variables, transitions of ICDAS score, mean BD, and mean BD recovery rate (RR%), were statistically analyzed using the chi-square test, two way-repeated measures ANOVA, and Wilcoxon rank sum test, respectively (alpha = 0.05). RESULTS: Based on the visual inspection, OCT images at the baseline, 72 WSLs were purely carious, 20 were non-carious (developmental) lesions, while 29 were combined (carious-developmental). The responses of WSLs over time showed to be highly variable. There was a significant difference in transitions of ICDAS scores after 3 months between carious and non-carious WSLs (p < 0.05) and non-carious and combined WSLs (p < 0.05). Carious and combined WSLs underwent significant changes in the mean BD between baseline (161.8 ± 56.8 µm) and 2 months (130.7 ± 57.4 µm) or 3 months (119.1 ± 57.5 µm) (p < 0.05), while there was no significant difference between baseline (132.2 ± 26.2 µm) and 2 months (122.8 ± 24.1 µm) or 3 months (119.8 ± 22.6 µm) in non-carious WSLs (p > 0.05). There was a significant difference in mean RR% after 2 and 3 months between carious and non-carious WSLs (p < 0.05). CONCLUSIONS: The remineralization capacity of WSL was variable among the cases and subjects, and depended on the WSLs history, etiology (carious, non-carious, or combined lesion) and structure (histological pattern). CLINICAL RELEVANCE: Carious WSLs showed the highest remineralization potential.

[Survey on healthcare provider awareness of cosmetic therapy for older adults of in-and-out geriatric hospital departments].

AIM: This study aimed to determine the perceptions among healthcare providers of the clinical need for cosmetic therapy among older adults. METHODS: A questionnaire was distributed to 190 medical staff regarding their perceptions of cosmetic therapy for older adults. The survey included questions on occupation, sex, age, cosmetic therapy in older adults, and acceptable cosmetic treatments. Nurses answered questions regarding the type of ward in which they worked. RESULTS: Completed questionnaires were collected from 121 people (mean age 33.3±9.4; men n=42). The participants included nurses (n=55), physical therapists (n=25), occupational therapists (n=15), and other occupations (n=26). Most participants believed that makeup improves the quality of life of older adults; however, many participants first became aware of the existence of cosmetic therapy through this survey. Half of the participants were interested in participating in cosmetic therapy, and a high number of women and nurses were interested. Most cosmetic treatments were acceptable to those caring for outpatients, while those caring for hospitalized patients showed low acceptance rates for treatments other than skin care. The acceptance rates tended to be particularly high for participants who worked in rehabilitation wards. CONCLUSION: Many participants believed cosmetic therapy to be effective in improving the quality of life; however, only about half of all subjects were interested in participating in cosmetic therapy. The acceptance rate of cosmetic treatments differed by work environment. This study provided valuable data contributing to the spread of cosmetic therapy.

Age-dependent changes of the mandible bone throughout the lifespan in female F344/N rat.

Age-dependent changes of the mandible bone in female F344/N rats, aged 22-1196 days, were analyzed using physiological bone properties and morphology. Bone weight, bone area, bone mineral components, and bone mineral density were assessed using dual-energy X-ray absorptiometry. The bone weight, bone area, bone mineral components, and bone mineral density increased rapidly until approximately 150 days of age, increased gradually thereafter, and then stabilized or decreased after 910 days of age. The ratio of bone mineral components to bone weight (bone mineral ratio) increased rapidly until approximately 43 days of age and stabilized thereafter. Size of the mandible, which was measured at 13 points on mandible surface, increased with age, and the rate of change showed a similar pattern to the other parameters. From a principal component analysis on morphometric measurements, principal component 1 (size factor) increased proportionally with age, whereas principal component 2 (shape factor) decreased until approximately 88 days of age and then increased after 365 days of age. As a result, the scatter plots for principal component 1 and principal component 2 were V-shaped, which indicates that the mandible developed in size, with deformation at younger ages, and recovered its original shape later in life. Our results revealed the occurrence of inflection points at approximately 43, 88, 150, 365, and 910 days of age. Some of these ages corresponded to transition points revealed by the age-dependent changes of the occlusal mandibular condyle and tooth wear in the same rat.

Comparison of Oral Assessment Results Between Non-Oral and Oral Feeding Patients: A Preliminary Study.

In the current study, evaluation and comparison of oral status was performed to confirm the necessity of oral care for non-oral feeding patients. The study involved patients consulting an attending physician in one hospital's Department of Dentistry for oral care. Based on the feeding method, participants were divided into two groups: (a) non-oral (n = 66) and (b) oral (n = 66) feeding. Characteristics and Oral Assessment Guide scores were compared between groups. The non-oral feeding group had significantly worse scores than the oral feeding group. The non-oral feeding group also showed significantly lower voice-, swallowing-, saliva-, and tongue-related scores. The poor oral status of non-oral feeding patients was clarified. The results suggest the importance of oral care for non-oral feeding patients. [Journal of Gerontological Nursing, 43(4), 23-28.].

Bactericidal effects of 310 nm ultraviolet light-emitting diode irradiation on oral bacteria.

BACKGROUND: Ultraviolet (UV) light is used for phototherapy in dermatology, and UVB light (around 310 nm) is effective for treatment of psoriasis and atopic dermatitis. In addition, it is known that UVC light (around 265 nm) has a bactericidal effect, but little is known about the bactericidal effect of UVB light. In this study, we examined the bactericidal effects of UVB-light emitting diode (LED) irradiation on oral bacteria to explore the possibility of using a 310 nm UVB-LED irradiation device for treatment of oral infectious diseases. METHODS: We prepared a UVB (310 nm) LED device for intraoral use to examine bactericidal effects on Streptococcus mutans, Streptococcus sauguinis, Porphyromonas gingivalis, and Fusobacterium nucleatum and also to examine the cytotoxicity to a human oral epithelial cell line (Ca9-22). We also examined the production of nitric oxide and hydrogen peroxide from Ca9-22 cells after irradiation with UVB-LED light. RESULTS: Irradiation with the 310 nm UVB-LED at 105 mJ/cm2 showed 30-50% bactericidal activity to oral bacteria, though 17.1 mJ/cm2 irradiation with the 265 nm UVC-LED completely killed the bacteria. Ca9-22 cells were strongly injured by irradiation with the 265 nm UVC-LED but were not harmed by irradiation with the 310 nm UVB-LED. Nitric oxide and hydrogen peroxide were produced by Ca9-22 cells with irradiation using the 310 nm UVB-LED. P. gingivalis was killed by applying small amounts of those reactive oxygen species (ROS) in culture, but other bacteria showed low sensitivity to the ROS. CONCLUSIONS: Narrowband UVB-LED irradiation exhibited a weak bactericidal effect on oral bacteria but showed low toxicity to gingival epithelial cells. Its irradiation also induces the production of ROS from oral epithelial cells and may enhance bactericidal activity to specific periodontopathic bacteria. It may be useful as a new adjunctive therapy for periodontitis.

A new oral care gel to prevent aspiration during oral care.

AIM: Although oral care is important in the prevention of aspiration pneumonia, the different institutions and practitioners employ various oral care methods, some of which are associated with the risk of aspiration. We have developed a new gel with the physical properties needed for waterless oral care. In the present study, we evaluated and investigated the properties and effectiveness of this gel. METHODS: The physical properties of the trial gel and commercial moisturizing gels were compared using a VAS scale. The effects of plaque elimination were evaluated in healthy volunteers. Brushing was carried out by a dental hygienist using the gel and water. The number of throat suctions performed during brushing was also counted, and the difference was evaluated. RESULTS: In the evaluation of physical characteristics, trial Gel B showed a significantly higher rating than the other gels. In plaque elimination, the rate of decrease in a modified PCR was significantly greater with the gel trial. Suctioning was also performed significantly fewer times with the trial gel. CONCLUSIONS: Good results were obtained with the newly developed trial Gel B with regard to the physical properties and the sensory evaluations. Its effectiveness was also confirmed in plaque elimination and in the evaluated risk of aspiration. The use of Gel B may have the potential to decrease the risk of aspiration during oral care and reduce the occurrence of aspiration pneumonia.

Assessment of Self-Adhesive Resin Composites: Nondestructive Imaging of Resin-Dentin Interfacial Adaptation and Shear Bond Strength.

Shear bond strength (SBS) and the interfacial adaptation (IA) of self-adhesive resin (SAR) composites to dentin were evaluated. Two SARs [Vertise Flow (VTF) and Fusio Liquid Dentin (FLD)] were evaluated and compared with a conventional restorative system [adhesive: OptiBond FL and composite: Herculite Précis (OBF/HP)]. Human third molars were used for SBS testing and IA imaging (n=7) using optical coherence tomography (OCT). Flattened dentin disks were prepared and the composites were applied into molds (2.4 mm diameter) that were positioned on dentin. Samples were subjected to SBS testing and OCT analysis, which considered an increase in signal intensity at the bonded interface as evidence of internal gaps. SBS data were analyzed by one-way analysis of variance and Tukey's test and IA data (% distribution of high brightness values) by Kruskal-Wallis and Dunn's test (p≤0.05). No statistically significant difference in SBS was observed between VTF (13.9±3.6 MPa) and FLD (11.3±3.2 MPa), whereas OBF/HP showed higher average strength (27.3±6.1 MPa). However, there was a statistically significant difference in IA when VTF (33.3%) was compared with FLD (1.2%) and OBF/HP (1.5%). The conventional restorative system exhibited superior SBS performance compared with SARs. However, the IA of FLD to dentin had values that were not significantly different from OBF/HP.

Characterization of transparent dentin in attrited teeth using optical coherence tomography.

Attrition and wear of tooth surface occur with aging and result in loss of enamel, with exposure and histological changes in dentin. Dealing with attrited teeth and restoration of the lost tissue are clinically challenging. The main objective of this study is to characterize the exposed transparent dentin in the occlusal surface of attrited teeth by optical coherence tomography (OCT). Naturally attrited, extracted human teeth with occlusal-transparent dentin were investigated in comparison to sound and carious teeth. The teeth were subjected to OCT imaging and then cross-sectioned and polished. OCT B-scans were compared to light microscopy images of the same cross section. In OCT images, some changes were evident at the transparent dentin in attrited teeth. An OCT attenuation coefficient parameter (µ t) was derived based on the Beer-Lambert law as a function of backscatter signal slope. The mean values of µ t were 1.05 ± 0.3, 2.23 ± 0.4, and 0.61 ± 0.27 mm(-1) for sound, carious, and transparent dentins, respectively. One-way ANOVA with Tukey's post-hoc showed a significant difference between groups (p < 0.05). Physiological changes in transparent dentin that involve deposition of mineral casts in the dentinal tubules lead to lower attenuation of OCT signal. OCT has a potential role to detect transparent dentin on the surface of attrited teeth and can be used in the future as a clinical adjunct tool.

[The association between health-related quality of life and voice as evaluated by an acoustic analysis in elderly Japanese nursing home residents].

PURPOSE: We carried out a cross-sectional study investigating the association between health-related quality of life (HRQOL) and voice, as evaluated by an acoustic analysis, in elderly residents of a nursing home. METHODS: The HRQOL of 61 elderly nursing home residents (mean age: 82.1±8.3 years) was assessed via the SF-8 Health Survey questionnaire, Japanese version (SF-8). The subjects' voices were recorded and analyzed by a voice assessment software program, which calculated the pitch period perturbation quotient (PPQ), amplitude perturbation quotient (APQ), and noise-to-harmonic ratio (NHR). RESULTS: Subjects who scored under the 25th percentile on general health (GH), vitality (VT), or physical summary (PCS) in the SF-8 showed significantly higher PPQ, APQ, and NHR scores in comparison to their counterparts (p<0.05). After adjustment for age, lower GH scores were found to be associated with higher PPQ, APQ, and NHR scores; lower VT scores were associated with higher APQ and NHR scores; and lower PCS scores were associated with higher APQ and NHR scores (p<0.05). CONCLUSION: The results of the acoustic analysis indicated that voice was associated with HRQOL in the elderly nursing home residents of the present study. Among the acoustic parameters that were analyzed, PPQ, APQ, and NHR may be an influential factor that can be used to assess HRQOL, independently of the effects of age, in elderly individuals.

Analysis of cariogenic biofilms by using a swept-source optical coherence tomography in vitro.

OBJECTIVE: The objective was to measure the thickness of Streptococcus mutans (S. mutans) biofilms forming in an oral biofilm reactor (OBR) by using a noninvasive swept-source optical coherence tomography (SS-OCT) system at every 4 h time interval until 20 h and analyze the correlations with the amounts of biofilms. METHODS: S. mutans biofilms were formed on square-shaped bovine enamel blocks inside an OBR. Biofilms were analyzed at every 4 h stage (4 h, 8 h, 12 h, 16 h and 20 h) using a SS-OCT system and a laser scanning confocal microscope (LSCM). The amounts of biofilms were measured at each stage by separating the water insoluble glucan (WIG) and bacterial cells. Co-relationships between the SS-OCT measured biofilm thickness and the amounts of adhered biofilms were analyzed. RESULTS: The thickness of biofilms detected on SS-OCT images at 4 h stage was 0.059 ± 0.029 (Av ± SD) mm which increased time-dependently in a linear fashion after 8 h stage and reached to 0.435 ± 0.159 mm at 20 h stage and the correlation coefficient was about 0.89. The amounts of biofilms; bacterial optical density (OD) and WIG concentration increased time-dependently were 0.035 ± 0.008 / mm2 and 10.328 ± 2.492 µg/ mm2 respectively at 20 h stage. Correlation coefficients of 0.66 between 'the amounts of bacteria' and 'biofilm thickness on OCT' and 0.67 between 'the amounts of WIG' and 'biofilm thickness on OCT' were obtained, suggesting that there was a relatively positive correlation between them. CONCLUSION: The SS-OCT can be a useful tool to measure time-dependent growth of biofilms. Further studies are needed in order to assess biofilms using SS-OCT more accurately.

Stability of voxel values from cone-beam computed tomography for dental use in evaluating bone mineral content.

OBJECTIVES: The objective of this study was to investigate the stability of voxel values from cone-beam CT (CBCT) using a flat panel detector in changing surrounding circumstances mimicking clinical situations. MATERIALS AND METHODS: Seven hydroxyapatite (HA) rods (0, 40, 80, 120, 160, 199, and 239 mg Ca/cm(3) ) were set in a 16 cm diameter water phantom and scanned with CBCT (FineCube) and also with multislice CT (MSCT) used as reference. The voxel values from CBCT were measured by the obtained images with OsiriX software (http://www.osirix-viewer.com), and compared with the CT numbers from MSCT. We examined the correlation between the voxel values and the HA contents, the variance of voxel values, and the influence of changing surrounding circumstances on the voxel values. RESULTS: The voxel values from CBCT were different from the CT numbers from MSCT, but there was a linear Pearson correlation between the voxel values and the HA contents. The voxel values were greatly influenced when the samples were scanned surrounded in air. However, the voxel values were not affected significantly in the existence of materials simulating oral hard tissues and/or a metal core post. CONCLUSIONS: There was a linear correlation between the voxel values of CBCT and the contents of HA rod samples. Our study indicated that it might be possible to evaluate bone mineral content(BMC) from the voxel values of CBCT for dental implant treatment.

3D assessment of void and gap formation in flowable resin composites using optical coherence tomography.

PURPOSE: To investigate the effect of composite type and cavity size on gap and void formation using optical coherence tomography (OCT). MATERIALS AND METHODS: Class I cavities of two depths (2 mm or 4 mm; 4 mm diameter) were prepared, treated with Tri-S Bond (Kuraray Medical), and bulk filled with either Surefil SDR Flow (SF; Dentsply) or Clearfil Majesty LV (MJ; Kuraray Medical) to form four groups. After 24 h, the specimens were 3D scanned using swept-source OCT (Santec) with 1310 nm laser at a 20 kHz sweep rate. In OCT tomograms, the bonding interface and the bulk of the restorations were evaluated. The percentage values of sealed interfaces (SP) and void volume (VP) for all groups were calculated and statistically analyzed using two- and one-way ANOVA and Tukey's post-hoc test. Selected specimens were cross sectioned and observed using a scanning electron microscope (SEM) and a confocal laser scanning microscope to confirm OCT findings. RESULTS: The following values were obtained for SP and VP, respectively: SF-2mm: 92% and 0.08%; SF-4mm: 66% and 0.13%; MJ-2mm: 86% and 1.79%; MJ-4mm: 33% and 1.96%. Both composites showed a significant increase in gap formation at 4-mm cavity depth (p < 0.001). While SF showed a rather homogeneous bulk compared to MJ, cavity depth did not significantly affect the void volume fraction (p = 0.08). CONCLUSION: The flowable composite with SDR (stress-decreasing resin) technology performed better than the conventional composite; however, bulk filling a 4-mm-deep cavity will compromise the sealing of the bonding interface regardless of the type of composite. OCT is a unique method of characterizing materials and their behaviors nondestructively and precisely.

Localizing the mandibular canal on dental CT reformatted images: usefulness of panoramic views.

PURPOSE: The aim of this study was to compare panoramic and paraxial views of dental CT reformatted images to detect the mandibular canal, and to evaluate the usefulness of the dental CT software function of "Outlining the Mandibular Canal in the Panoramic View". METHODS: One hundred and fifty-five patients (310 sides), who underwent multi-slice computed tomography examination for pretreatment planning of dental implant were analyzed. After scanning, two types of dental CT reformatted image, panoramic and paraxial views were obtained. Two oral radiologists evaluated both views for the visibility of the mandibular canal using a 5-point rating scale: score 5, 100-80% visible, to score 1, 20-0% visible. The visibility scores of the two views were evaluated and compared by Wilcoxon's signed rank test. RESULTS: The mean ± standard deviations of panoramic and paraxial views were 4.2 ± 1.1 and 3.5 ± 1.2, respectively, and the former was significantly higher than the latter (p < 0.001). On the basis of these results, we attempted to apply the function of "Outlining the Mandibular Canal in the Panoramic View" to cases with poor visibility of the canal (score 1, 2 or 3) on paraxial views. Consequently, we could reduce the number of such cases from 128 (41%) to 56 (18%). CONCLUSIONS: The detectability of the mandibular canal was significantly higher in panoramic views than in paraxial views. Using the function of "Outlining the Mandibular Canal in the Panoramic View", the precision for identifying the canal on paraxial views was considered to be improved.

[The significance of oral care in dysphagia patients].

As society ages the number of dysphagia patients and elderly people who cannot independently manage oral care will also increase. Maintaining or improving proper swallowing and oral functions is an important issue from the perspective of retaining quality of life (QOL) and motivation in living. Dysphagia patients are susceptible to aspiration pneumonia, and are also more likely to be malnourished. Oral care for dysphagia patients does not involve simply cleaning the oral cavity, but also preventing aspiration pneumonia, which can be fatal. At the same time, it is related to improving eating and swallowing function and preventing dehydration and malnutrition. It is therefore very important from the perspective of improving QOL. Mechanical stimulation in oral care also plays a role as indirect training in eating and swallowing rehabilitation. The significance of oral care therefore lies in three points: (1) preventing aspiration pneumonia, (2) preventing malnutrition, and (3) indirect training in eating and swallowing rehabilitation. An oral care system of standardized oral care that can be completed in 5 minutes is promising as an effective means of oral rehabilitation.

Noninvasive diagnostic method using optical coherence tomography detected a vulnerable dentin enamel junction created by phosphoric acid etching.

To investigate the influence of phosphoric acid etching on the dentin enamel junction (DEJ) using optical coherence tomography (OCT). Human teeth were assigned to four groups: 1. control, no additional treatment (CT); 2. The primer of "SE Bond2" was applied (SE), 3. "Enamel Conditioner" was applied (EC), 4. "K-etchant syringe" was applied (KE). After treatment, the DEJ was observed using a laser microscope (CLSM), OCT, and scanning electron microscopy (SEM). Additionally, an ultimate tensile strength (UTS) test at the DEJ was performed. No cracks were observed by CLSM. In contrast, cracks were observed all samples by SEM. Additionally, OCT revealed a white line along the DEJ in all KE specimens and some EC specimens. The UTS test showed a significant difference between CT and KE. This study found that phosphoric acid etching may cause excessive demineralization and weaken the DEJ. This fragility was observed using a non-invasive diagnostic method using OCT.