[Effect of a 10-Methacryloyloxydecyl Dihydrogen Phosphate- treated Bioceramic Sealer on the Bond Strength of an Endodontic Fiber Post: Multilayer Composite Disk Models and Ultra-highspeed Imaging Analysis].

PURPOSE: Multiple materials are found in the root canal after fiber-post cementation. The layer of a bioceramic-based (BC) sealer may affect the bond strength (σBS) of the fiber post in the root canal. The purpose of this study was to employ multilayer compos-ite-disk models in diametral compression to investigate whether the bond strength between a fiber post and root dentin can be in-creased by the application of a primer on the BC sealer. MATERIALS AND METHODS: The multilayers of materials in the root canal required 3D finite-element (FE) stress analyses (FEA) to pro-vide precise σBS values. First, BC sealer was characterized using x-ray powder diffraction (XRD) to determine when the sealer com-pletely set and the types of crystals formed to select which primer to apply to the sealer. We selected a 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP)-based primer to treat the BC sealer before post cementation. Ultra-highspeed (UHS) imaging was utilized to analyze the crack initiation interface. The obtained failure force was used in FE analysis to calculate σBS. RESULTS: UHS imaging validated the fracture interface at the post-dentin junction as FEA simulations predicted. σBS values of the fiber posts placed with various material combinations in the root canal were 21.1 ± 3.4 (only cement/ post), 22.2 ± 3.4 (BC sealer/cement/post) and 28.6 ± 4.3 MPa (10-MDP primer treated BC sealer/cement/post). The 10-MDP-treated BC sealer exhibited the highest σBS (p < 0.05). CONCLUSION: The multilayer composite disk model proved reliable with diametral compression testing. The presence of BC sealer in the root canal does not reduce σBS of the fiber post. Conditioning the BC sealer layer with 10-MDP primer before fiber-post cemen-tation increases σBS.

Submicron Memtransistors Made from Monocrystalline Molybdenum Disulfide.

Multiterminal memtransistors made from two-dimensional (2D) materials have garnered increasing attention in the pursuit of low-power heterosynaptic neuromorphic circuits. However, existing 2D memtransistors tend to necessitate high set voltages (>1 V) or feature defective channels, posing concerns regarding material integrity and intrinsic properties. Herein, we present a monocrystalline monolayer MoS2 memtransistor designed for operation within submicron regimes. Under reverse drain bias sweeps, our experiments reveal memristive behavior within the device, further controllable through modulation of the gate terminal. This controllability facilitates the consistent manifestation of multistate memory effects. Notably, the memtransistor behavior becomes more significant as the channel length diminishes, particularly with channel lengths below 1.6 µm, showcasing an increase in the switching ratio alongside a decrease in the set voltage with the decreasing channel length. Our optimized memtransistor demonstrates the ability to exhibit individual resistance states spanning 5 orders of magnitude, with switching drain voltages of approximately 0.05 V. To elucidate these findings, we investigate hot carrier effects and their interplay with oxide traps within the HfO2 dielectric. This work highlights the importance of memtransisor behavior in highly scaled 2D transistors, particularly those featuring low contact resistances. This understanding holds the potential to tailor memory characteristics essential for the development of energy-efficient neuromorphic devices.

Effects of ceramic thickness, ceramic translucency, and light transmission on light-cured bulk-fill resin composites as luting cement of lithium disilicate based-ceramics.

PURPOSE: To assess the effects of ceramic thickness, ceramic translucency, and light transmission on restorative composites used as luting cement for lithium disilicate-based ceramics. METHODS: Four luting types of cement were tested (n=8); a dual-cured resin cement (Multilink N), a light-cured conventional flowable composite (Tetric N-Flow), and two light-cured bulk-fill flowable composites (Tetric N-Flow Bulk Fill and X-tra base). The 20 s- or 40 s-light (1000 mW/cm2) was transmitted through 1- or 2-mm-thick high- or low-translucency (HT- or LT-) ceramic discs (IPS e.Max press) to reach the 1-mm-thick luting cement. Light transmitted to cement without ceramic served as a control. Vickers hardness number (VHN), flexural strength (FS), fractography, and degree of conversion (DC) were evaluated. One-way and multi-way analysis of variance was conducted to determine the effects of factors on VHN and FS. RESULTS: Ceramic thickness, light transmission time, and cement type significantly affected the VHN of the luting cement (P < .000). Only Multilink N (LT- and HT-1mm) and Tetric N-Flow (HT-1mm) reached 90% VHN of corresponding control by 20 s-light transmissions, but Tetric N-Flow exhibited lowest VHN and approximately 1/3-1/2 VHN of Multilink N (P < 0.05). X-tra base expressed superior physicochemical properties to Tetric N-Flow Bulk Fill (P < 0.05) and reached >90% VHN of control in all conditions with 40 s-light transmissions except for LT-2 mm. DC, FS, and fractography supported these findings. CONCLUSIONS: The light-cured bulk-fill composite served as a luting cement for lithium-disilicate-based ceramics in a product-dependent manner. Light transmission time is crucial to ensure sufficient luting cement polymerization.

Bioinspired and self-restorable alginate-tyramine hydrogels with plasma reinforcement for arthritis treatment.

Long-standing administration of disease-modifying antirheumatic drugs confirms their clinical value for managing rheumatoid arthritis (RA). Nevertheless, there are emergent worries over unwanted adverse risks of systemic drug administration. Hence, a novel strategy that can be used in a drug-free manner while diminishing side effects is immediately needed, but challenges persist in the therapy for RA. To this end, herein we conjugated tyramine (TYR) with alginate (ALG) to form ALG-TYR and then treated it for 5 min with oxygen plasma (ALG-TYR + P/5 min). It was shown that the ALG-TYR + P/5 min hydrogel exhibited favorable viscoelastic, morphological, mechanical, biocompatible, and cellular heat-shock protein amplification behaviors. A thorough physical and structural analysis was conducted on the ALG-TYR + P/5 min hydrogel, revealing favorable physical characteristics and uniform porous structural features within the hydrogel. Moreover, ALG-TYR + P/5 min not only effectively inhibited inflammation of RA but also potentially regulated lesion immunity. Once ALG-TYR + P/5 min was intra-articularly administered to joints of rats with zymosan-induced arthritis, we observed that ALG-TYR + P/5 min could ameliorate syndromes of RA joint. This bioinspired and self-restorable ALG-TYR + P/5 min hydrogel can thus serve as a promising system to provide prospective outcomes to potentiate RA therapy.

Real-world effectiveness of national pit and fissure sealants program in Taiwan.

OBJECTIVES: This study investigated the effectiveness of a national population-based pit and fissure sealants (PFS) program in Taiwan. METHODS: Part 1 (effectiveness of national PFS program) involved children who had participated in the PFS program from 2015 to 2019. After propensity score matching, 670,840 children were selected for analysis until the end of 2019. During follow-up, the permanent first molars of the participants were assessed for caries-related treatments by employing multilevel Cox proportional hazards models. In Part 2 (effectiveness of retained sealants), which involved 1,561 children, sealant retention was evaluated 3 years after placement. A structured questionnaire was employed to collect information on family and individual factors. The endpoints were the same as in Part 1. RESULTS: In Part 1, the adjusted hazard ratios (HRs) for caries-related treatments among participants in the PFS program were 0.90 (95% confidence interval [CI] = 0.89, 0.91) for dental restoration, 0.42 (95% CI = 0.38, 0.46) for initiation of endodontic treatment, 0.46 (95% CI = 0.41, 0.52) for completion of endodontic treatment, and 0.25 (95% CI = 0.18, 0.34, all Ps < 0.0001) for extraction. In Part 2, the adjusted HR for dental restoration of teeth with retained sealants was 0.70 (95% CI = 0.58, 0.85), significantly lower than that for teeth without retained sealants (P = 0.0002). CONCLUSIONS: Participation in the national PFS program was associated with a significant reduction of at least 10% in the risk of caries-related treatments, and an additional 30% risk reduction may have been attributed to sealant retention. CLINICAL SIGNIFICANCE: In a real-world setting, schoolchildren in the national PFS program were associated with a significant reduction of at least 10% in the likelihood of caries-related treatments. The program provided moderate protection against caries for the study population and could be improved by increasing the sealant retention rate.

Quality of dental treatments under intravenous sedation among patients with disability: A self-matching study.

Background/purpose: Patients with disabilities usually have difficulties in communication and mobility, and the quality of the dental treatments are often inferior. This study uses the Taiwan National Health Insurance Database to analyze the quality of dental treatment for patients with disabilities who receive intravenous sedation (IVS). Materials and methods: This study selected patients with disabilities who received dental treatment under IVS. Their oral cavity was divided into three major sections: anterior teeth, upper posterior teeth, and lower posterior teeth. Self-matching of the same section was conducted to observe whether operative dental treatment (OD) with or without IVS affected the occurrence of dental retreatment. This study observed the occurrence of refilling and the duration from the end of treatment until retreatment to compare treatment differences with or without IVS. Results: After self-matching, this study found 158 patients who received dental treatment within the same section with and without IVS. During a follow-up period of 17 years, 75.18% of the patients who received OD treatment required refilling, 10.87% required endodontic treatment, and 5.67% required tooth extraction. After OD treatment with IVS, the risks of refilling, endodontic treatment, and tooth extraction were 0.71 (95% CI: 0.58-0.87, P < 0.001), 0.77 (95% CI: 0.48-1.23, P = 0.28), and 0.64 (95% CI: 0.32-1.27, P = 0.20), respectively. Conclusion: For patients with disabilities, OD treatment with IVS significantly reduces the risk of refilling compared with OD treatment without IVS. IVS can be ideal for people with disabilities who receive dental treatment.

Decline in dental caries experience among schoolchildren in Taiwan, 2012-2020.

OBJECTIVES: This study investigated the association between the decline of the decayed, missing, and filled teeth (DMFT) index and several family-level and individual-level factors among 6- to 18-year-old Taiwanese children from 2012 to 2020. METHODS: This study used data from the 2012 and 2020 Taiwan National Oral Health Survey of Children and Adolescents. Both surveys used similar methods and were performed in the same study age group. A structured questionnaire was used to collect data on parents' sociodemographic background; the number of children in the family; oral health-related knowledge, attitudes, and behaviours; and children's dietary habits. Dental caries was recorded through standardized oral examinations. Multivariable multilevel zero-inflated negative binomial regression models were used to determine the association between family-level and individual-level factors and the DMFT index from 2012 to 2020. RESULTS: A total of 10 217 and 10 436 schoolchildren completed the oral examinations and questionnaires in the 2012 and 2020 surveys, respectively. The adjusted mean DMFT index of 12-year-old Taiwanese schoolchildren in 2020 was 2.01, denoting a significant decline from 2.50 in 2012 (adjusted mean ratio = 0.20, 95% confidence interval [CI] = 0.17, 0.23, p < .0001). Furthermore, children who often consumed sugar-rich drinks had a significantly higher risk (mean ratio = 1.05, 95% CI = 1.01, 1.10) of having DMFT than those who seldom consumed such drinks (p = .017). CONCLUSIONS: In the period of 2012-2020, the DMFT index among Taiwanese children significantly declined. Children who often consumed sugar-rich drinks had a higher DMFT index than those who seldom consumed such drinks. Our findings are valuable to paediatricians, dentists, nutritionists, and public health policymakers.

Calcium peroxide aids tyramine-alginate gel to crosslink with tyrosinase for efficient cartilage repair.

The innate cartilage extracellular matrix is avascular and plays a vital role in innate chondrocytes. Recapping the crucial components of the extracellular matrix in engineered organs via polymeric gels and bioinspired approaches is promising for improving the regenerative aptitude of encapsulated cartilage/chondrocytes. Conventional gel formation techniques for polymeric materials rely on employing oxidative crosslinking, which is constrained in this avascular environment. Further, poor mechanical properties limit the practical applications of polymeric gels and reduce their therapeutic efficacy. Herein, the purpose of this study was to develop a bioadhesive gel possessing dual crosslinking for engineering cartilage. Tyramine (TYR) was first chemically conjugated to the alginate (ALG) backbone to form an ALG-TYR precursor, followed by the addition of calcium peroxide (CaO2); calcium ions of CaO2 physically crosslink with ALG, and oxygen atoms of CaO2 chemically crosslink TYR with tyrosinase, thus enabling dual/enhanced crosslinking and possessing injectability. The ALG-TYR/tyrosinase/CaO2 gel system was chemically, mechanically, cellularly, and microscopically characterized. The gel system developed herein was biocompatible and showed augmented mechanical strength. The results showed, for the first time, that CaO2 supplementation preserved cell viability and enhanced the crosslinking ability, bioadhesion, mechanical strength, chondrogenesis, and stability for cartilage regeneration.

Effects of oral exercise on tongue pressure in Taiwanese older adults in community day care centers.

BACKGROUND/PURPOSE: Oral exercise is a training method for swallowing dysfunction in older adults. The study investigated the effect of oral exercise on tongue pressure in older adults in Taiwanese community day care centers over a 3-month period. MATERIALS AND METHODS: Participants over age 50 who were able to communicate and participating for the duration of the 12-week period were recruited from five community day care centers. A 15-min weekly group oral exercise activity was conducted. The tongue pressures were measured and multivariable linear regression models were used to assess the effect of oral exercise intervention on the participants' tongue pressures. RESULTS: A total of 66 older adult participants, among whom the mean age was 78.06 ± 10.74 years. Tongue pressure continued improving during the intervention period, and the mean tongue pressure at the end of the study was 20.63 ± 10.45 kPa, which was significantly higher than the baseline measurement (16.92 ± 10.62 kPa, p < 0.001). Participants exhibited significant improvement in tongue pressure regardless of their age groups. Moreover, participants with one to seven pairs of functional tooth units (FTUs) exhibited significantly more improvement in tongue pressure (16.00 kPa, 95% CI = 2.58-29.43) than those without FTUs (p = 0.021). CONCLUSION: Oral exercise over a 3-month period significantly improved tongue pressure among the study participants regardless of their gender or age group. Oral exercise should be integrated into comprehensive health promotion programs to assist in the improvement and maintenance of oral function among older adults.

Association between sugary drinks consumption and dental caries incidence among Taiwanese schoolchildren with mixed dentition.

OBJECTIVES: Dental caries is a multifactorial disease, and a sugary diet can generate an acidic plaque environment that advances its development. However, the specific effect of sugary drinks on the subsequent oral health of schoolchildren with mixed dentition is unclear. In this study, we investigated the association between the consumption of sugary drinks and 1 year incidence rate of caries in permanent teeth among Taiwanese schoolchildren with mixed dentition. METHODS: A longitudinal 1 year follow-up study was conducted among Taiwanese schoolchildren aged 8-9 years. A questionnaire collected information regarding the parents' oral health status and their children's demographic background, oral health-related behaviours and consumption habits of sugary drinks, including handmade drinks (specifically bubble tea and pearl milk tea) and carbonated drinks. Dental caries was recorded through standardized oral examinations. The number of dental services received was retrieved from the Taiwan National Health Insurance Research Database. Multivariate Cox proportional hazards models and zero-inflated negative binomial models were used to estimate the association between the consumption of sugary drinks and the incidence rate of caries in permanent teeth after 1 year. RESULTS: The study involved 494 children. During the 1 year follow-up period, 117 children developed new dental caries in their permanent teeth, yielding a caries incidence rate of 0.183 per person-year. After adjustments for confounding factors, children who preferred having sugar-rich beverages were associated with having a 4.3 times higher (95% confidence interval [CI] = 1.2-15.7) risk of developing caries than did those who preferred nonsugary drinks (P < .05). Additionally, children who often consumed handmade drinks were associated with having a 1.7 times higher (95% CI = 1.1-2.9) risk of developing caries than those who seldom consumed (P < .05). CONCLUSIONS: The findings suggest that the consumption of sugary drinks during the mixed dentition stage might be a major etiological factor for caries in permanent teeth. These findings could be valuable to paediatricians, dentists, nutritionists and policymakers.

Association between population-based fluoride varnish application services and dental caries experience among schoolchildren in Taiwan.

BACKGROUND/PURPOSE: Taiwan government has provided population-based fluoride varnish application services for all preschool children since July 2004. This study investigated the association providing such services on dental caries experiences among schoolchildren. METHODS: A cross-sectional study was conducted on schoolchildren aged 8-9 years. A questionnaire collected information on sociodemographic background, parents' oral health status, children's oral health-related behavior, and dietary habits. Dental caries was recorded through standardized oral examinations. The number of services was retrieved from the Taiwan National Health Insurance Research Database. Univariate, multivariable linear, and logistic regression analyses were performed. RESULTS: The study involved 1246 children. The mean dental caries indices were 3.97 for decayed, extracted, and filled teeth (deft) and 0.94 for decayed, missing and filled teeth (DMFT). After adjustments for confounding factors, it was revealed that children receiving services were not associated with significantly lower deft and DMFT indices (P > 0.05). The adjusted odds ratio (OR) for untreated primary teeth of children receiving 3 or more services was 0.64 (95% CI = 0.44-0.95) compared with those who received no services (P = 0.025). However, subgroup analyses demonstrated that children in the low-risk group were mainly affected (adjusted OR = 0.36-0.89, P = 0.013). CONCLUSION: This study revealed that children receiving 3 or more services were associated with a 36% decreased risk of having untreated caries in primary dentition, but these children were mainly in the low-risk group. These results illustrate real data that provides dentists and policymakers with valuable information.

Two-photon scanned light sheet fluorescence microscopy with axicon imaging for fast volumetric imaging.

SIGNIFICANCE: Two-photon microscopy has become the standard platform for deep-tissue fluorescence imaging. However, the use of point scanning in conventional two-photon microscopy limits the speed of volumetric image acquisition. AIM: To obtain fast and deep volumetric images, we combine two-photon light sheet fluorescence microscopy (2p-LSFM) and axicon imaging that yields an extended depth of field (DOF) in 2p-LSFM. APPROACH: Axicon imaging is achieved by imposing an axicon lens in the detection part of LSFM. RESULTS: The DOF with axicon imaging is extended more than 20-fold over that of a conventional imaging lens, liberating the synchronized scanning in LSFM. We captured images of dynamic beating hearts and red blood cells in zebrafish larvae at volume acquisition rates up to 30 Hz. CONCLUSIONS: We demonstrate the fast three-dimensional imaging capability of 2p-LSFM with axicon imaging by recording the rapid dynamics of physiological processes.

Local chromatin fiber folding represses transcription and loop extrusion in quiescent cells.

A longstanding hypothesis is that chromatin fiber folding mediated by interactions between nearby nucleosomes represses transcription. However, it has been difficult to determine the relationship between local chromatin fiber compaction and transcription in cells. Further, global changes in fiber diameters have not been observed, even between interphase and mitotic chromosomes. We show that an increase in the range of local inter-nucleosomal contacts in quiescent yeast drives the compaction of chromatin fibers genome-wide. Unlike actively dividing cells, inter-nucleosomal interactions in quiescent cells require a basic patch in the histone H4 tail. This quiescence-specific fiber folding globally represses transcription and inhibits chromatin loop extrusion by condensin. These results reveal that global changes in chromatin fiber compaction can occur during cell state transitions, and establish physiological roles for local chromatin fiber folding in regulating transcription and chromatin domain formation.

Anti-Demineralization Effects of Dental Adhesive-Composites on Enamel-Root Dentin Junction.

Oral biofilm reactor (OBR) and pH cycling (pHC) artificial caries model were employed to evaluate the anti-demineralization effects of four composite filling systems on enamel-root dentin junction. Sixty-four enamel-root dentin blocks (6 mm × 6 mm × 2 mm) each with a cylindrical cavity were randomly assigned to the pHC and OBR group, then four subgroups (n = 8) and filled with either the Beautifil II (BEF, SPRG-filler-containing) or Estelite (EST) composite after the adhesive (either Single Bond Universal (SBU) or FL Bond II (FL, SPRG-filler-containing)). The demineralization lesions of filling interface were examined by micro-computerized tomography (µCT) and swept-source-optical coherence tomography (SS-OCT). According to the degree of interface damage, the caries lesions were sorted into four types: Type A and B (no attachment loss); Type C and D (attachment loss). EST/SBU showed the worst demineralization lesion and attachment loss (100% Type D), while BEF/FL exhibited the shallowest lesion depth (p < 0.05, 145 ± 45 µm on enamel, 275 ± 35 µm on root dentin) and no attachment loss (75% Type A and 25% Type B). Using FL adhesive alone does not effectively reduce enamel demineralization. BEF plays a leading role in acid resistance. The combination of BEF and FL showed a cumulative synergistic effect on anti-demineralization.

Influence of maxillary antrolith on the clinical outcome of implants placed simultaneously with osteotome sinus floor elevation: A retrospective radiographic study.

BACKGROUND: Large antroliths and those located adjacent to the sinus floor can affect clinical interventions and increase the difficulty of implant placement performed simultaneously with osteotome sinus floor elevation surgery. PURPOSE: This retrospective study investigated the clinical outcomes of implants placed simultaneously with osteotome sinus floor elevation subjacent to maxillary antroliths. MATERIAL AND METHODS: Twenty implants inserted subjacent to or intruding into the antrolith after sinus floor elevation were evaluated in 18 patients. Cone-beam computed tomography (CBCT) was used to measure antrolith size and membrane thickness at sites of osteotome sinus floor elevation. Periapical radiographs were used to assess the height of grafted bone. Generalized estimating equation (GEE) analysis was performed to correlate the occurrence of antroliths with patient background characteristics and dental outcomes, based on a sample population of 239, among whom 33 presented antroliths. RESULTS: The 20 implants remained clinically stable over a mean follow-up period of 42.4 months. The mean thickness of the sinus membrane at osteotome sites was 5.4 ± 3.3 mm. None of the cases presented sinus membrane perforation or sinus symptoms following osteotome intervention. The mean gain in the height of grafted sinus bone was 4.0 ± 1.4 mm at the last follow-up. The occurrence of antroliths was higher among females and the elderly (>49 years old). The multivariable GEE analysis showed that the adjusted odds ratio for the occurrence of antroliths with root canal fillings was significantly lower than those without root canal fillings (odds ratio = 0.33; 95% confidence interval = 0.11-0.96). CONCLUSION: Our findings indicate that osteotome sinus floor elevation is a surgical procedure with a risk <17%. Thorough planning based on CBCT and careful management during surgery can eliminate the negative effects of antroliths on implant performance.

Craniofacial, dental arch morphology, and characteristics in preschool children with mild obstructive sleep apnea.

BACKGROUND/PURPOSE: Pediatric obstructive sleep apnea (OSA) might be a serious cause of neurocognitive deficits, behavioral changes, and craniofacial disharmony in children at very young age with mild type of OSA. This study aims to examine the effect of mild OSA on craniofacial morphology as well as dental arch morphology and characteristics in preschool children. MATERIALS AND METHODS: The test group comprised 16 preschool children (11 boys, 5 girls; mean age: 5.14 years old; mean AHI: 2.02) with confirmed polysomnographic diagnosis of mild OSA. Ten control subjects also underwent polysomnography (5 boys, 5 girls; mean age: 5.18 years old; median AHI: 0.43). Lateral cephalometric radiographs and dental arch impressions were obtained and measured. A survey on characteristics and quality of life (OSA-18) was filled out by study participants' caregivers. RESULTS: For craniofacial morphology, a significant increase in ANB angle, a decrease in SNB angle, and larger overjet size were seen in the group with mild OSA, compared with the control group. More frequent sleep disturbances and mood swing were also found in children with mild OSA, based on the OSA-18 assessment. CONCLUSION: Preschool children with mild OSA present the following: skeletal Class II pattern with a more retrognathic mandible, increased overjet size, and more pronounced symptoms in the domains of sleep and emotion. Dental arch constriction is not a typical feature in our sample of Asian preschool children with mild OSA.

Dentists' performance in dentin-composite resin bonding before and after hands-on course learning.

BACKGROUND/PURPOSE: The restoration longevity depends on a high dentin-composite bond quality. This study investigated learning outcomes when using etch-and-rinse and self-etch adhesives among general practitioners in a hands-on bonding test course. METHODS: We recruited 30 general practitioners to perform shear bond strength (SBS) tests using five adhesives: one Peak® Universal Bond (PUB) etch-and-rinse and four Futurabond DC, Single Bond universal (SBU), Versa Optibond (VOB), and Tetric-N Bond Self-Etch (TNS) self-etch adhesives. SBS tests were conducted at pre-demonstration (pre-demo), post-demonstration (post-demo), and 24-h storage (delayed bonding) stages. SBS data were analyzed with paired Student's t-tests. We defined 17 MPa as "qualified bond strength (QBS)". The percentages of samples with SBS achieving QBS were analyzed using Mantel-Haenszel chi-square tests. The fracture surfaces of the samples were examined by scanning electron microscopy (SEM). RESULTS: Using PUB caused no significant differences in SBS between pre- and post-demo samples, whereas the SBS of the two self-etch adhesives (SBU and VOB) improved in post-demo samples (p < 0.05). SBU showed the highest percentage of samples with SBS achieving QBS in all three groups (pre-demo = 70%, post-demo = 83%, and delayed bonding = 76.5%). The QBS percentages of VOB and TNS notably improved from 0% (pre-demo) to 71.4% and 23.5% (post-demo), respectively. SEM indicated bubble-like defects at the dentin-resin interfaces in cases of low SBS. CONCLUSION: Bonding performance is both operator- and product-dependent. The continuing education hands-on course does help dentists to improve the bond strength especially when the self-etch system is used.

Can government-supported preventive fluoride varnish application service reduce pulp-involved primary molars?

OBJECTIVES: Fluoride varnishes are reported to reduce 37-43% of dental caries; however, it remains unclear whether they can prevent severe decay. The study investigated the association between the government-supported preventive fluoride varnish application service (FVAS) and the risk of undergoing treatments of pulp-involved primary molars. METHODS: Children who were younger than 6 years and did not receive any dental treatment between the first and last services within 2 years were defined as the "preventive-FVAS group." After the matching process, 45,296 children were selected for further analysis until the end of 2013. The log-rank test and Cox proportional hazard models were employed to estimate the effects of preventive-FVAS on the treatments of pulp-involved primary molars, including pulpectomy and early extraction before the age of 8 years. RESULTS: After adjusting for confounding factors, adjusted hazard ratios for the treatments of pulp-involved primary molars for children who received preventive-FVAS were 0.96 (95% CI = 0.92-1.00) for initiation of pulpectomy, 0.93 (95% CI = 0.86-1.00) for completion of pulpectomy, and 0.87 (95% CI = 0.82-0.92, P < 0.0001) for early extraction, especially for those who received three or more FVAS. CONCLUSIONS: Although preventive-FVASs were associated with a 4-13% decreased risk of undergoing treatments of pulp-involved primary molars within a lower risk subset, we suggest the implementation the current Taiwan government-supported FVAS program needs to be modified. Further studies are warranted to evaluate whether it would be a better strategy if the program focused only on the high-risk group.

Biomechanical behavior of cavity design on teeth restored using ceramic inlays: An approach based on three-dimensional finite element analysis and ultrahigh-speed camera.

Ceramic fracture and debonding are the primary failures that follow ceramic inlay and can lead to stress and tooth fracture. In this study, we examined two designs-concave and flat-of the gingival cavity bottom for tooth cavities restored using ceramic inlays. We investigated the biomechanical behavior of ceramic inlay-restored teeth (concave and flat) through three-dimensional finite element analysis (FEA) and experimentally validated the results using an ultrahigh-speed camera. We conducted in vitro real-time recording of the deformation of a restored tooth during loading using an ultrahigh-speed camera. This technique enables further image registration to observe deformation variation and vector fields. The deformation vector fields revealed that the concave design moved the deformation toward the buccal side of the cavity bottom, whereas the flat design moved it toward the palatal side. These findings correlated with the FEA results, which indicated that the concave design constrained stress in the dentin cavity and relieved palatal stress. Our results suggest that incorporating a concave design in cavity preparation can improve the fracture resistance of ceramic inlay-restored teeth, preventing unrestorable fractures. The current study is the first to utilize an ultrahigh-speed camera in dental biomechanics, and such cameras are useful for nondestructive and dynamic analysis. STATEMENT OF SIGNIFICANCE: First utilize ultrahigh-speed cameras in dental biomechanics analysis. Tooth fracture videos captured by ultrahigh-speed camera helps us learn fracture mechanics in between tooth cavity design and ceramic inlay. Concave design leads to stress in safer areas that causes a less damaging fracture. Minimal invasive preparation by concave design strengthens tooth fracture resistance. Non-destructive data from ultrahigh-speed cameras combined with FEA can get more insight into how the stress and strain derived in biomaterials.