Recently in Japan, due to the increased prices of palladium and gold, cast titanium restorations have been included in the Japanese national health insurance system. The purpose of this review was to survey the available literature on titanium bonding systems, focusing on the adhesive monomer in the luting agent in order to expand the application of resin-bonded fixed prostheses made of titanium or titanium alloys. It was found that adhesive monomers are effective for bonding to titanium, and provide results equal to the procedures of silanization and tribochemical silica coating. A primer or a luting agent, including 10-methacryloyloxydecyl dihydrogen phosphate (MDP), methacryloyloxyalkyl thiophosphate derivative (MEPS), 6-methacryloxyhexyl phosphonoacetate (6-MHPA), and 4-methacryloyloxyethl trimellitate anhydride (4-META) promotes bonding characteristics between titanium and the resin material.

Purpose: This study was conducted to evaluate the effects of the probiotic Lactobacillus paracasei in patients undergoing removal of impacted mandibular third molars, focusing on tumor necrosis factor alpha (TNF-α) levels in gingival crevicular fluid, pain, swelling, trismus, and interincisal distance.

Methods: Thirty patients were divided into two groups: (1) wound irrigation with the probiotic, and (2) irrigation with 0.9% normal saline. The data were collected at the baseline, and at 24 h and 7 days after the operation. The TNF-α level in gingival crevicular fluid was determined using the ELISA technique.

Results: In the experimental group, the probiotic L. paracasei MSMC39 reduced the TNF-α level in gingival crevicular fluid to a significantly greater degree than in the control group (P < 0.05). Pain, swelling and trismus evaluated in terms of a visual analog scale (VAS) score were lower in the experimental group than in the control group, but not to a statistically significant degree (P > 0.05). The mean interincisal distance in the experimental group was higher than that in the control group (P = 0.014).

Conclusion: The probiotic L. paracasei is able to reduce the level of TNF-α in gingival crevicular fluid and can ameliorate postoperative complications after mandibular molar removal.

Purpose: Few studies have examined the association of oral health behaviors with chewing ability.This study aimed to investigate the associations between the number of remaining natural teeth and oral health behaviors with subjective chewing ability among older Thai adults.

Methods: Analysis was carried out using data from the 8th Thailand National Oral Health Survey. Subjective chewing problems were assessed using self-reported questionnaires, and the number of remaining teeth by oral examination. Poisson regression with sampling weights was used to calculate the prevalence ratios (PRs) and 95% confidence intervals (CIs) for having chewing problems.

Results: Of the 2,310 participants (mean age, 67.2 ± 4.5 years), 53.3% had chewing problems. After adjusting for all covariates, significantly higher PRs for having chewing problems were observed among the participants without interdental cleaning (PR, 1.32; 95% CI, 1.06-1.65), without night-time brushing (PR, 1.12; 95% CI, 1.01-1.25), who were edentulous (PR, 1.16; 95% CI, 1.02-1.31), had urgent dental treatment within the past 12 months (PR, 1.15; 95% CI, 1.06-1.24), and who brushed for <2 min (PR, 1.10; 95% CI, 1.02-1.20).

Conclusion:The number of remaining natural teeth and oral health behaviors were significantly associated with subjective chewing problems.

Purpose: The aim of this study was to evaluate the effect of dyes used in photodynamic therapy (PDT) on color changes of resin-based composites (RBCs).

Methods: A total of 120 composite discs were made of microfilled, nanohybrid, and nanoceramic RBCs, and the CIE Lab system was used to assess initial colors with a spectrophotometer. Photosensitizers were used in accordance with the experimental design, as follows: MB (methylene blue), TB (toluidine blue), ICG (indocyanine green), and control (no dye). The samples were irradiated with a 940-nm diode laser. After irradiation, the photosensitizers were removed with distilled water (∆E₁) and sodium hypochlorite (∆E₂), and final colors were measured. Data were analyzed by the three-way ANOVA and Bonferroni tests (α = 0.05).

Results: There was no statistically significant difference between the ICG and control groups; however, the TB and MB groups exhibited the strongest staining. The nanohybrid RBC exhibited the greatest color change, and there were no significant differences between the microhybrid and nanoceramic RBCs. After NaOCl irrigation, ΔE₂ values decreased to clinically acceptable values (ΔE₂ < 3.3).

Conclusion: The intensity of staining of the RBCs differed according to the type of photosensitizer used and the content of the composite resin. The irrigant NaOCl was effective in removing discoloration.

Purpose: To clarify the effect of mouth-closed tooth brushing on the suppression of droplet generation in comparison with ordinary (mouth-open) tooth brushing and to investigate the difference in plaque removal efficacy between mouth-open and mouth-closed tooth brushing.

Methods: Fourteen adults participated in the study. The labial/buccal, lingual, and occlusal surfaces of each sextant were brushed with the mouth open and closed, and a high-sensitivity camera and a high-power light source were used to measure the number of generated droplets. The plaque removal efficacy of each type of tooth brushing was evaluated according to the O’Leary Plaque Control Record.

Results: Significantly more droplets were generated by mouth-open brushing than by mouth-closed brushing. The number of droplets was highest when the lingual surfaces of the upper anterior sextants were brushed with the mouth open. In mouth-closed brushing, almost no droplets were observed from any region. The plaque removal rate with each type of brushing did not differ significantly among any regions except the lingual surfaces of the upper left sextant.

Conclusion: Mouth-closed tooth brushing almost completely suppressed droplet generation and did not reduce the plaque removal efficacy. Therefore, mouth-closed tooth brushing is beneficial as an oral hygiene method during coronavirus disease 2019 outbreaks.

Purpose: This study investigated the surface roughness (SR), surface microhardness (SH), and chemical composition of recently developed fluoride-releasing restorative materials aged in common liquids.

Methods: A total of 276 disc-shaped samples with a diameter of 8 mm and a height of 2 mm were prepared by using four restorative materials: alkasite, Activa, Equia Forte, and Zirconomer. Atomic force microscopy (AFM) and the Vickers microhardness test were used to measure SR and SH, respectively. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM/EDS) was used for elemental analysis of the materials. The prepared samples were divided into 3 subgroups and immersed in coffee, cola, and saliva for 1 week at 37°C and 100% humidity.

Results: Cola and coffee significantly increased the SR of all materials except Zirconomer immersed in coffee (P < 0.05). The microhardness of alkasite and Activa significantly decreased in all liquids (P < 0.05) The percentage of fluorine (F) in the materials significantly changed after immersion for some liquids (P < 0.05).

Conclusion: Aging differentially affected the surface characteristics and elemental mass ratios of the studied materials.

Purpose: The purpose of this repeated cross-sectional study was to investigate the prevalence and severity of oral hygiene conditions in Cambodian primary school children.

Methods: Oral examinations were conducted on 2,020 school children (1st-6th grade) at a public primary school in Siem Reap, Cambodia from 2013 to 2015, focusing on plaque adhesion, gingiva, and dental calculus deposition. Data analysis was performed on 1,998 children without any missing data, and the chi-square test was used to compare the variables.

Results: The prevalence of dental plaque adhesion in 2013, 2014, and 2015 was 93.6%, 93.7%, and 85.1%, respectively. The prevalence of gingivitis in 2013, 2014, and 2015 was 93.1%, 92.1%, and 88.8%, respectively. The prevalence of dental calculus deposition in 2013, 2014, and 2015 was 55.1%, 19.3%, and 34.7%, respectively. Significant differences were observed in all variables each year (P < 0.001).

Conclusion: The findings of this study suggest that oral hygiene conditions were poor in this population.

Purpose: This study investigated and tested a novel cone-beam computed tomography (CBCT) scanning technique capable of obtaining clear contours of soft tissues in the esthetic area.

Methods: Twenty-three periodontally healthy participants underwent this novel CBCT scanning technique. Soft tissue morphological parameters were measured on the CBCT images obtained. Intraoral clinical data were also collected at the same locations, and the accuracy of the CBCT method was tested.

Results: The median (interquartile range [IQR]) of the supracrestal gingival tissue thickness as 0.91 (0.73-1.13) mm, and the thickness of the central incisors was significantly greater than that of the canines (P < 0.05). The median (IQR) of keratinized tissue thickness was 0.73 (0.55-0.91) mm, which also showed a significantly greater thickness in the central incisors than in the canines (P < 0.05). Bland-Altman analysis suggested that CBCT could be accurate for measuring soft tissues in the esthetic area.

Conclusion: The novel CBCT technique described yields clear contours of soft tissues in the esthetic area without the need for auxiliary tools. Moreover, measurements of soft tissue morphological parameters on CBCT appear to be accurate.

Purpose: This study investigated the root and canal morphology of the permanent anterior dentition in a Black South African population.

Methods: In total 2,343 permanent anterior teeth were evaluated using cone-beam computed tomography images and described according to the Vertucci and Ahmed et al. classifications. Demographic information, root number and internal canal morphology were recorded. Age and sex associations were made using Fisher’s exact test (P < 0.05).

Results: All anterior teeth were single-rooted (100%). The most frequent configuration in maxillary anteriors was a single canal (Vertucci Type I/¹MXA¹). In mandibular anteriors, single canal configurations (Type I/¹MDA¹) predominated, however 36.6% of mandibular central and 33.9% of lateral incisors displayed two canals. Older subjects (>40 years) demonstrated single canals more than younger subjects (P = 0.0004). Females displayed variations more compared to males (P = 0.002). The two classifications were found to be comparable for evaluation of permanent anterior teeth. Complex configurations were better described using the newer system.

Conclusion: The permanent anterior teeth of this population exhibited exclusively single roots and diverse internal characteristics. Clinicians should be aware of anatomical variations, particularly in mandibular incisors, as these may result in adverse endodontic outcomes if not taken into consideration by the treating practitioner.

Purpose: The aim of this study was to categorize the effects of heat on coronal obturation with gutta-percha and sealer using X-ray micro-computed tomography (micro-CT).

Methods: Ten single-rooted, extracted human teeth were shaped using ProTaper NEXT files to size X5 (#50/Taper 6%) with 2.5% NaOCl irrigation. A single ProTaper NEXT X5 gutta-percha point was then inserted with epoxy resin (AH Plus) or tricalcium silicate (EndoSequence BC) sealer (n = 5/group), and cut at the cemento-enamel junction. The teeth were scanned using micro-CT (SkyScan1272) to obtain 11 sagittal 2-D images. Three calibrated raters categorized the coronal 0.5 mm of the images into four categories: “swirled sealer and/or gutta-percha without voids” (I), “uniform voids and sealer/gutta-percha” (II), “non-uniform voids and sealer/gutta-percha” (III), and “swirled sealer and/or gutta-percha with voids” (IV). Intra-rater and inter-rater reliability were then calculated. Chi-square tests were conducted to determine the significance of differences in each category between sealers.

Results: The intra-class correlation coefficient was 0.55 (same rater/two different times) and Fleiss’ kappa (different raters/same image) was 0.34. Categories I, II, III, and IV accounted for 16.4%, 4.2%, 30.3%, and 49.1% for AH Plus, and 6.7%, 4.2%, 27.3%, and 61.8% for EndoSequence BC, respectively.

Conclusion: Category IV was most common and Category II the least common. Significant differences were evident between sealers for Category I (P < 0.01).

Purpose: This study evaluated the cytotoxic effects of polymethyl methacrylate resin extracts on rat macrophage viability in in vitro conditions.

Methods: Prepared test specimens were immersed in 5 mL of artificial saliva and incubated for 24, 48, and 72 h at 37°C. The cytotoxicity of the obtained solutions of extracted resins, used as a stock solution (100%) and diluted with Roswell Park Memorial Institute (RPMI) medium to obtain the working solutions (50, 40, 30, 20, 10, and 5%), was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.

Results: No dose-dependent toxic activity in macrophage culture was detected for the three types of extracts obtained after 24, 48, and 72 h of material extraction. The shortest extraction of material was found to be completely non-toxic, and the 20% concentration of this extract obtained caused a significant increase in cell ability to metabolize MTT. Extracts obtained after 72 h of extraction showed the highest cytotoxic potential of 50%, 40% and 30%, and extracts obtained after 48 and 72 h of extraction at concentrations of 5% and 10% had a proliferative effect on the macrophage cell line.

Conclusion: This study demonstrated that the highest cytotoxic effect was observed in cells exposed to the highest concentrations (50, 40, and 30%) of the extracts that were extracted for 72 h.

Purpose: This study aimed to evaluate the causal relationship between root contact and root contact length of orthodontic miniscrew implants (miniscrews), and assessed factors for implant failure through cone-beam computed tomography (CBCT) images.

Methods: First, a logistic regression analysis was performed to investigate the most relevant factors for implant failure based on sex, age, vertical skeletal pattern, horizontal skeletal pattern, and presence of root contact in 59 patients (mean age: 21.2, age range: 13-54 years) who had miniscrew implants. Next, 38 miniscrews (1.6 mm in diameter and 8.0 mm in length) with root contact were investigated in the patients. Root contact length was measured using CBCT taken after miniscrew implant placement.

Results: The results showed that root contact was the most critical risk factor for failure of miniscrew implants in patients. Logistic regression analysis showed that the risk approximately doubled as the root contact length increased by 1.0 mm.

Conclusion: Avoiding proximity to the root during miniscrew implant placement is essential to prevent implant failure.

Purpose: To compare blood pressure (BP), hypertension (HT) history, oral diseases, and potentially associated factors among dental patients in Thailand and explore the associations among them.

Methods: This study included 709 patients. Demographic data, BP levels, oral diseases, xerostomia, anxiety, depression, and associated factors were evaluated.

Results: One-third of the patients were male; patients with a history of HT were older than those without (P < 0.001). In total, 53 (7.5%) had such a history, and HT was controlled in 29 (54.7%) of them. Patients with possible HT (BP ≥140/90 mmHg; 94 in total, 13.3%) were five times more likely to have a definitive diagnosis of HT than those without possible HT (odd ratio [OR] = 4.95; 95% confidence interval [CI]: 2.76-8.87; P < 0.001). They also had an increased tendency to be taking antidyslipidemic (OR = 5.54; 95% CI: 2.90-10.60; P = 0.001) or antidiabetic (OR = 4.80; 95% CI: 1.91-12.08; P = 0.001) drugs. Male sex (ß = 0.156, P < 0.001), higher age (ß = 0.299, P < 0.001), higher body mass index (ß = 0.410, P < 0.001), and periapical tissue diseases (ß = 0.073, P = 0.019) were significantly associated with elevated systolic BP. Severe periodontitis (ß = 0.081, P = 0.023) and a comparable association pattern with systolic BP were related to diastolic BP. Multivariate analysis revealed no significant association between BP and tooth loss, xerostomia, smoking, education level, anxiety, or depression.

Conclusion: Dentists play an essential role in screening for undiagnosed and uncontrolled HT. Significant associations were noted between oral inflammatory diseases and high BP.

Purpose: Moisture exclusion while treating dental caries can be challenging, and the glass ionomer cements (GICs) used for these procedures are susceptible to water. Few studies have examined the effects of the powder/liquid ratio (PLR) on the physical properties of GICs exposed to water. In this study, the hardness and thickness of the water-susceptible surface layer of three GICs were evaluated.

Methods: Three conventional GICs were mixed in increasing PLRs, and hardness over time was measured under conditions of no water exposure, distilled water exposure, and saliva exposure. Furthermore, the thickness of the water-susceptible layer for each GIC was determined.

Results: A water-susceptible layer of approximately 250 μm was evident for all GICs, and the thickness decreased with increasing PLR. GIC hardness increased with increasing PLR in conditions without water for all GIC types. Furthermore, the removal of the water-susceptible layer restored the physical properties of each GIC.

Conclusion: Overall, the results indicate that conventional GIC restoration with the removal of the water-susceptible surface layer is a feasible strategy for treating dental caries in individuals for whom exclusion of moisture can be difficult.

Purpose: The influence of three dental abrasives on the surface roughness, glossiness, and color of titanium (Ti) after mechanical polishing was investigated.

Methods: The specimens were divided into groups, referred to as SM, SR, and TP, to distinguish the different polishing processes. SM: rubber polishing using a rubber point containing SiC abrasive particles at 20,000 rpm, followed by gloss polishing; SR: rubber polishing using a rubber point containing Al₂O₃ abrasive particles at 20,000 rpm, followed by gloss polishing; TP: rubber polishing using a rubber point containing TiO₂ abrasive particles at 6,000 rpm, followed by gloss polishing. Gloss polishing was carried out at 10,000 rpm using a leather buffing wheel. Measurements to evaluate the surface conditions of Ti were performed after each polishing process.

Results: There were no significant differences in the Ra and glossiness values between the SM and TP groups; these specimens were not as smooth and glossy as the SR group. The SM group showed relatively high values of lightness and chroma after gloss polishing.

Conclusion: Rubber polishing with abrasives containing SiC or TiO₂ particles before gloss polishing did not achieve appropriate surface conditions on Ti.

A 72-year-old Japanese female patient presented with an asymptomatic, white-colored, smooth-surfaced, firm papule 3 mm in diameter involving the mucosa on the posterior part of the right maxilla. An excisional biopsy specimen was diagnosed as an oral focal submucous elastofibromatous lesion. A review of the literature revealed very few documented cases of oral mucosal lesions characterized by accumulation of degenerated elastic fibers. Various oral lesions have histopathological features similar to those observed in cutaneous diseases, and the present case was a focal submucous elastofibromatous lesion in the alveolar mucosa.

This study investigated the relationship between the direction of maxillary repositioning after Le Fort I osteotomy and changes in external nasal morphology using lateral cephalograms and frontal facial photographs. The results indicated greater changes in external nasal morphology, such as a more forward position of the nasal tip and an increased alar base width, with anterosuperior repositioning than with posterosuperior repositioning. In conclusion, this study demonstrated that the external nasal morphology changes after Le Fort I osteotomy, and that the changes vary depending on the direction of maxilla repositioning.