Association between tooth loss-related speech and psychosocial impairment with cognitive function: A pilot study in Hong Kong's older population.

BACKGROUND: Tooth loss has been associated with cognitive decline, but the underlying mechanisms involving speech and psychosocial impairment remain unclear. OBJECTIVES: To investigate the impact of tooth loss-related speech and psychosocial impairment on cognitive function in Hong Kong's older population. METHODS: Seventy-six Cantonese-speaking participants between the ages of 51-92 were classified into three groups: patients with complete dentures (CD), partially edentulous patients with less than 10 occluding tooth pairs (OU <10), and at least 10 occluding tooth pairs (OU ≥10). Cognitive function was assessed using the Montreal Cognitive Assessment Hong Kong Version, One-minute Verbal Fluency Task and Hayling Sentence Completion Test. Objective and subjective speech assessments were carried out using artificial intelligence speech recognition algorithm and a self-designed speech questionnaire. The impact of tooth loss on psychosocial condition was evaluated by the Reading the Mind in the Eyes Test and a self-designed questionnaire. Statistical analyses (one-way ANOVA, ANCOVA, Kruskal-Wallis test, Spearman correlation test) were performed. RESULTS: Tooth loss was significantly associated with lower cognitive function (p = .008), speech accuracy (p = .018) and verbal fluency (p = .001). Correlations were found between cognitive function and speech accuracy (p < .0001). No significant difference in tooth loss-related psychosocial impact was found between the three groups. CONCLUSION: While warranting larger sample sizes, this pilot study highlights the need for further research on the role of speech in the association between tooth loss and cognitive function. The potential cognitive impact of tooth retention, together with its known biological and proprioceptive benefits, supports the preservation of the natural dentition.

Association between removable prosthesis-wearing and pneumonia: a systematic review and meta-analysis.

BACKGROUND: A high burden of respiratory pathogens colonizing removable prosthesis surfaces suggests the potential of association between removable prosthesis-wearing and respiratory infections. Therefore, this systematic review and meta-analysis aimed to evaluate the evidence from clinical studies concerning the association between removable prosthesis-wearing and respiratory infections. METHODS: Clinical studies that reported respiratory infections associated with adult patients wearing removable prostheses in any centers (hospitals and nursing homes) or communities were included. Literature was searched across five electronic databases (MEDLINE, Cochrane Library, EMBASE, Web of Science, and Scopus) to 28 May 2024. An additional search was performed for unpublished trials and references cited in related studies. The Newcastle-Ottawa Scale was employed for the quality assessment. The certainty assessment was established using GRADE. The results were pooled using a frequentist random-effects meta-analysis and the odds ratios generated. RESULTS: A total of 1143 articles were identified. Thirteen articles had full-text articles screening and an additional two articles were added through reference linkage. Ultimately, six non-randomized clinical studies reporting various types of pneumonia contributed to this review. Overall odds of having pneumonia among prosthesis wearers were 1.43 (95% CI: 0.76 to 2.69) and 1.27 (95% CI: 1.11 to 1.46) using the random- and fixed-effects models, respectively. The heterogeneity in the meta-analysis was substantial. In subgroup analysis according to the study design, the heterogeneity within prospective studies was much reduced, I2 = 0% (p = 0.355). The certainty of the evidence evaluated using the GRADE approach was low to very low evidence for prosthesis wearers developing pneumonia based on studies. CONCLUSIONS: There was no conclusive evidence from the non-randomized clinical studies supporting whether prosthesis-wearing is a risk factor for pneumonia based on outcomes from this review.

Prevalence of respiratory pathogens colonizing on removable dental prostheses in healthy older adults: A systematic review and meta-analysis.

PURPOSE: This systematic review and meta-analysis aimed to investigate the prevalence of opportunistic respiratory pathogens colonizing removable dental prostheses in older adults without respiratory diseases. METHODS: This review was registered with PROSPERO and conducted in accordance with the principles formed by the working group of the Joanna Briggs Institute (JBI) to evaluate systematic reviews of prevalence data. Literature searches were conducted across five electronic databases. Quality assessments were determined according to a revised JBI critical appraisal checklist across nine criteria. Comparison between fixed- and random-effects meta-analyses were performed for sensitivity analysis. Prediction intervals were also presented when three or more studies were included in the meta-analysis. RESULTS: Across the databases, 1091 articles were identified, and 591 articles remained after the removal of duplicates. Twenty "potentially effective" studies were identified. Ultimately eight studies informed this review and meta-analyses were performed for 13 known respiratory pathogens. The meta-analyses identified the top three common respiratory pathogens residing on the removable prostheses were, in descending order: Staphylococcus aureus: 31.81% (95% CI: 13.34%-48.24%); Staphylococcus epidermidis: 14.07% (95% CI: 7.88%-21.48%); Klebsiella pneumoniae: 10.50% (95% CI: 2.55%-22.30%). The heterogeneity scores for nine respiratory pathogen analyses were classified as "unimportant inconsistency", I2  = 0% (p > 0.1). For sensitivity analysis, there was no difference between the random- and fixed-effects models. CONCLUSION: The existing evidence demonstrated a high burden of certain opportunistic respiratory pathogens, which may be considered a major potential cause of respiratory infections in older adults wearing removable prostheses.

SURVIVAL AND COMPLICATION RATES OF RESIN COMPOSITE LAMINATE VENEERS: A SYSTEMATIC REVIEW AND META-ANALYSIS.

OBJECTIVES: The aim of this systematic review was to evaluate the survival and complication rates of resin composite laminate veneers. METHODS: Randomized controlled trials and cohort studies with a minimum 2-year follow-up assessing survival and complication rates of resin composite laminate veneers on permanent dentition from 1998 to May 2022. Literature searches were conducted in MEDLINE (PubMed), Scopus, and the Cochrane Central Register of Controlled Trials electronic databases. References cited in the related reviews and included full-text articles were also hand-searched to further identify potentially relevant studies. RESULTS: A total of 827 articles were identified. Twenty-two studies were considered for full-text review after the title and abstract screening stage. After exclusion, 7 studies (3 randomized controlled trials and 4 cohort studies) were included in the systematic review. Three published scales were adopted for the quality and risk of bias assessment. At the survival rate threshold, the overall heterogeneity (I2) for randomized controlled trials was 50.5% (P = .108). The overall pooled survival rate of the randomized controlled trials was 88% (95% CI: 81%-94%), with the mean follow-up time ranging from 24 to 97 months. Surface roughness, color mismatch, and marginal discoloration were the most reported complications. CONCLUSION: Resin composite laminate veneers demonstrated moderately high survival rates for the entire sample and the direct laminate veneer group demonstrated higher survival rates than the indirect approach. Most of the complications were regarded as clinically acceptable with or without reintervention.

In Vitro Salivary Protein Adsorption Profile on Titanium and Ceramic Surfaces and the Corresponding Putative Immunological Implications.

Immune responses triggered by implant abutment surfaces contributed by surface-adsorbed proteins are critical in clinical implant integration. How material surface-adsorbed proteins relate to host immune responses remain unclear. This study aimed to profile and address the immunological roles of surface-adsorbed salivary proteins on conventional implant abutment materials. Standardized polished bocks (5 × 5 × 1 mm3) were prepared from titanium and feldspathic ceramic. Salivary acquired pellicle formed in vitro was examined by liquid chromatography-tandem mass spectrometry and gene ontology (GO) analysis to identify and characterize the adsorbed proteins. Out of 759 proteins identified from pooled saliva samples, 396 were found to be attached to the two materials tested-369 on titanium and 298 on ceramic, with 281 common to both. GO annotation of immune processes was undertaken to form a protein-protein interaction network, and 14 hub proteins (≥6 interaction partners) (coding genes: B2M, C3, CLU, DEFA1, HSP90AA1, HSP90AB1, LTF, PIGR, PSMA2, RAC1, RAP1A, S100A8, S100A9, and SLP1) were identified as the key proteins connecting multiple (6-9) immune processes. The results offered putative immunological prospects of implant abutment material surface-adsorbed salivary proteins, which could potentially underpin the dynamic nature of implant-mucosal/implant-microbial interactions.

Shear Bond Strength and Remineralisation Effect of a Casein Phosphopeptide-Amorphous Calcium Phosphate-Modified Glass Ionomer Cement on Artificial "Caries-Affected" Dentine.

This study investigated the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-modified glass ionomer cement (GIC) on shear bond strength (SBS) and remineralisation of artificial "caries-affected" dentine. Human dentine slices were demineralised and allocated to three groups: group 1, conventional GIC; group 2, CPP-ACP-modified GIC; and group 3, resin-modified GIC. The SBS was measured using a universal testing machine (n = 16 per group). Remaining samples (n = 8 per group) were subjected to pH-cycling for 28 days. After pH-cycling, lesion depth and micro-mechanical properties at the sample-bonding interface were investigated using micro-computed tomography (micro-CT) and nano-indentation, respectively. The SBS for groups 1 to 3 were 4.6 ± 1.5 MPa, 4.2 ± 1.1 MPa, and 5.9 ± 1.9 MPa, respectively (p = 0.007; group 1, group 2 < group 3). Lesion depths determined by micro-CT for groups 1 to 3 were 186 ± 8 µm, 149 ± 14 µm, and 178 ± 8 µm, respectively (p < 0.001; group 2 < group 1, group 3). The mean (±SD, standard deviation) nano-hardness values for groups 1 to 3 were 0.85 ± 0.22 GPa, 1.14 ± 0.21 GPa, and 0.81 ± 0.09 GPa, respectively (p = 0.003; group 1, group 3 < group 2). The mean (±SD) elastic moduli for groups 1 to 3 were 1.70 ± 0.33 GPa, 2.35 ± 0.44 GPa, and 1.59 ± 0.13 GPa, respectively (p < 0.001; group 1, group 3 < group 2). The results suggest that the incorporation of CPP-ACP into GIC does not adversely affect the adhesion to artificial caries-affected dentine. Furthermore, CPP-ACP-modified GIC is superior to conventional GIC in promoting dentine remineralisation.

An investigation into the effect of a resin infiltrant on the micromechanical properties of hypomineralised enamel.

BACKGROUND: Resin infiltration may alter the mechanical properties of enamel hypomineralised lesions (HL); however, variable surface layer (SL) thickness may affect resin penetration. AIMS: To determine the thickness of the SL of HL and to investigate the effect of resin infiltration on the mechanical properties of HL. DESIGN: The thickness of the SL over HL was determined using polarised light microscopy. Etching time using 15% HCl gel to remove the SL of 52 samples was determined. Selected HL and control areas of 21 teeth were infiltrated with Icon® resin infiltrant, and cross-sectional Knoop microhardness (KHN) measurements were recorded before and after resin infiltration. RESULTS: Ninety-six point five per cent of HL had a detectable SL with mean thickness of 58 ± 29 µm. Application of HCl for 120 s produced a mean MIH erosion depth of 58 ± 12 µm. Eleven of 21 samples had evidence of infiltration using visual examination. The infiltrant penetrated some of the HL leading to an increase in KHN (111 ± 75 KHN) which, when compared to adjacent non-infiltrated HL (96 ± 52 KHN), was not statistically significantly different (P = 0.56). CONCLUSIONS: There was marked variation in the SL thickness of HL. Resin infiltration of HL did not increase microhardness significantly.

Evaluation of a commercial primer for bonding of zirconia to two different resin composite cements.

PURPOSE: To evaluate the effects of a commercial zirconia primer (Choice or RelyX Unicem) on shear bond strength (SBS) of two different resin composite cements - Choice (a conventional bis-GMA-based resin cement) and RelyX Unicem (self-adhesive resin cement) - to zirconia. MATERIALS AND METHODS: Zirconia blocks were manufactured and randomly divided into 5 main groups (n = 20) that received surface treatments and cements as follows: no surface treatment, Choice and RelyX Unicem (groups C and U, resp.); tribochemical silica coating followed by silanization, Choice (group SSC); application of a zirconia primer, Choice and RelyX Unicem (groups ZC and ZU, resp.). Light-curing composite resin cylinders were prepared and bonded on the prepared zirconia blocks using the two different resin cements. Half of the specimens in each group were stored in water for 24 h, and half were aged by 50 days of water storage followed by thermocycling (12,000 cycles between 5°C and 55°C). Thereafter, all of them were submitted to the SBS test. Fourier transmission infrared (FT-IR) spectrum analysis and gas mass spectrometry (MS) analysis were adopted for characterization of the zirconia primer. RESULTS: Statistical analysis of the SBS test showed that group C presented the lowest SBS values and group SSC the highest (p < 0.01). Artificial aging exerted no influence on the SBS of groups U, SSC, ZC, or ZU. FT-IR analysis suggested that benzene rings and carboxylic groups exist in the zirconia primer. MS analysis detected that 2-hydroxyethyl methacrylate, triethylamine, ethyl-4-dimethylaminobenzoate, ethanol, and water are contained in the primer. CONCLUSION: The zirconia primer and self-adhesive resin cement increased the SBS of zirconia.

Efficacy of ultrasonic home-care denture cleaning versus conventional denture cleaning: A randomised crossover clinical trial.

OBJECTIVE: To compare the efficacy of test (ultrasonic cleaner combined with immersion in denture cleanser solution) and control (immersion in denture cleanser solution followed by conventional brushing) denture cleaning interventions in enhancing denture cleanliness, reducing denture stomatitis, and improving patient satisfaction. METHODS: A prospective, single-blind, block-randomised, two-period crossover, superiority-controlled clinical trial was conducted of a 3-month intervention. The study design included a pre-intervention period (2 weeks), intervention period one (3 months), washout period (2 weeks), and intervention period two (3 months). A total of 56 community-dwelling elders were block-randomized into either sequence Test/Control or sequence Control/Test. The intervention, period, and carryover effects for the changes in the cleanliness of extensive partial and complete acrylic dentures, denture stomatitis, and changes in patient satisfaction were estimated using Generalized Estimating Equations models. RESULTS: Percentage plaque area coverage, patient satisfaction, and denture stomatitis were significantly improved for both intervention and control arms after 3 months (P < 0.05). The intervention arm was found to significantly improve denture cleanliness (P < 0.001) and patient satisfaction (P = 0.002) more than the control arm. Denture-wearing habits and denture age were also significantly associated with the changes in denture plaque coverage (P < 0.05). However, the effect of the test intervention on denture stomatitis was not significantly different compared to the control arm (P = 0.284). CONCLUSION: This study revealed that the test intervention group was significantly more effective than the control group in improving denture cleanliness and patient satisfaction among community-dwelling elders. This test intervention is recommended for maintaining optimum denture hygiene among older adults. CLINICAL SIGNIFICANCE: Removable dentures can harbor opportunistic pathogens, emphasizing the need for effective denture hygiene intervention using ultrasonic cleaner combined with immersion in denture cleanser solution to eliminate denture biofilm in community-dwelling elders.

A comparison of the prevalence of respiratory pathogens and opportunistic respiratory pathogenic profile of 'clean' and 'unclean' removable dental prostheses.

OBJECTIVES: To determine and compare the opportunistic respiratory pathogenic index (ORPI) and prevalence of respiratory pathogens between clean and unclean removable prostheses. METHODS: A cross-sectional study was conducted among 97 removable prosthesis wearers at a teaching dental hospital. Participants' prosthesis hygiene was grouped into clean and unclean. After prosthesis plaque samples were sequenced using the Type IIB Restriction-site Associated DNA Sequencing for Microbiome method, the prevalence was assessed for the presence of respiratory pathogens on each sample. The ORPIs for clean and unclean prostheses were quantified based on the sum of the relative abundance of respiratory pathogenic bacteria in a microbiome using a reference database that contains opportunistic respiratory pathogens and disease-associated information. RESULTS: A total of 30 opportunistic respiratory pathogens were identified on the removable prostheses. Eighty-one (83.5 %) removable prostheses harboured respiratory pathogenic bacteria. Stenotrophomonas maltophilia (34.0 %), Pseudomonas aeruginosa (27.8 %), and Streptococcus agalactiae (27.8 %) were the top three prevalent respiratory pathogens detected in plaque samples. There was a significantly higher prevalence of respiratory pathogens residing on unclean than clean prostheses (P = 0.046). However, the ORPIs in both groups showed no statistically significant difference (P = 0.516). CONCLUSIONS: The ORPIs for both clean and unclean prostheses demonstrated a similar abundance of respiratory pathogens. However, the high prevalence of respiratory pathogens residing on unclean prostheses should not be underestimated. Therefore, maintaining good prosthesis hygiene is still important for overall oral and systemic health, even though the direct link between prosthesis cleanliness and reduced abundance of respiratory pathogens has not been established. CLINICAL SIGNIFICANCE: The association between the prevalence of respiratory pathogens and unclean removable prostheses has been demonstrated and might increase the theoretical risk of respiratory disease development.

Characterization of pathogenic microbiome on removable prostheses with different levels of cleanliness using 2bRAD-M metagenomic sequencing.

Background: The microbiomes on the surface of unclean removable prostheses are complex and yet largely underexplored using metagenomic sequencing technology. Objectives: To characterize the microbiome of removable prostheses with different levels of cleanliness using Type IIB Restriction-site Associated DNA for Microbiome (2bRAD-M) sequencing and compare the Microbial Index of Pathogenic Bacteria (MIP) between clean and unclean prostheses. Materials and Methods: Ninety-seven removable prostheses were classified into 'clean' and 'unclean' groups. All prosthesis plaque samples underwent 2bRAD metagenomic sequencing to characterize the species-resolved microbial composition. MIPs for clean and unclean prostheses were calculated based on the sum of the relative abundance of pathogenic bacteria in a microbiome using a reference database that contains opportunistic pathogenic bacteria and disease-associated information. Results: Beta diversity analyses based on Jaccard qualitative and Bray-Curtis quantitative distance matrices identified significant differences between the two groups (p < 0.05). There was a significant enrichment of many pathogenic bacteria in the unclean prosthesis group. The MIP for unclean prostheses (0.47 ± 0.25) was significantly higher than for clean prostheses (0.37 ± 0.29), p = 0.029. Conclusions: The microbial community of plaque samples from 'unclean' prostheses demonstrated compositional differences compared with 'clean' prostheses. In addition, the pathogenic microbiome in the 'unclean' versus 'clean' group differed.

The pathogenic microbiome in the unclean removable prosthesis group tends to be more abundant than that of the clean counterpart among participants with the majority being elders attending a teaching hospital. This finding is worrying because a general decline in systemic health among community-dwelling elders may predispose them to life-threatening diseases.By understanding the characteristics of the microbiome of removable prostheses with different levels of cleanliness and the related microbial-infection risks after a comprehensive whole metagenomic sequencing, appropriate prosthesis hygiene care should be emphasized.This study introduced a comprehensive and novel method of microbiological investigation of plaque using 2bRAD-M. The taxonomic profile of the microbiome of whole genomes was demonstrated and resolved at the species-level taxonomy for prosthesis biofilms. The biggest advantage of this method included overcoming the DNA sample problems particularly the low-biomass nature of 'clean' prosthesis plaque samples. The findings will add to our understanding of the microbiological aspect of removable prosthesis plaque.

A comparative study on the mechanical and antibacterial properties of BPA-free dental resin composites.

OBJECTIVE: The commonly used base monomer utilized in resinous commercial dental restorative products is bis-GMA which is derived from bisphenol-A (BPA) - a well-known compound which may disrupt endocrine functions. To address concerns about its leaching into the oral environment and to optimize the quality of dental composites, a BPA-free alternative base monomer, fluorinated urethane dimethacrylate (FUDMA), was designed by modifying a UDMA monomer system. METHODS: Nine groups of composites were prepared by mixing the base monomers and TEGDMA in a ratio of 70/30 wt% to which were added silanized glass particles (mean diameter: 0.7 µm) in 3 different volume fractions (40, 45, and 50 vol%). Bis-GMA and UDMA base monomers were used as control groups in the same ratios. Various properties including degree of conversion (DC), flexural strength (FS) and flexural modulus (FM), water sorption (WS), solubility (SL), surface hardness and roughness, and initial adhesion property against S.mutans were investigated. One-way analysis of variance followed by Bonferroni test at α = 0.05 was used to analyze the results. RESULTS: A significant difference in FS between FUDMA-based composite with 40 vol% filler (120.3 ± 10.4 MPa) and Bis-GMA-based composite with the same filler fraction (105.8 ± 10.0 MPa) was observed but there was no significant difference among other groups. The UDMA based group exhibited the highest WS (1.3 ± 0.3 %). Bis-GMA showed greater initial bacterial adhesion but was not statistically different from the other groups (p = 0.082). SIGNIFICANCE: FUDMA-based resin composites exhibit comparable mechanical and bacterial adhesion properties compared with Bis-GMA and UDMA-based composites. The FUDMA composites show positive outcomes indicating they could be used as substitute composites to Bis-GMA-based composites.

Clinical performance of zirconia-based tooth-supported fixed dental prostheses: a systematic review and meta-analysis.

OBJECTIVES: This study aimed to investigate the clinical performance of zirconia-based fixed dental prostheses (FDPs) in comparison to metal-ceramic (MC) FDPs. METHODS: A comprehensive search on MEDLINE (PubMed), Web of Science (Core Collection), Scopus up to June 2024 was conducted. Studies that compared the success, survival and complication rates between zirconia based FDPs and MC FDPs were eligible for inclusion. RESULTS: Thirty-one articles were identified, of which 22 were included for systematic review and 7 RCTs were included for meta-analysis. 10, 9 and 3 studies were classified to mean follow-up ≤ 5 years, 5 years < mean Follow-up ≤ 10 years, mean Follow-up >10 years, respectively. In the pooled analysis, 180 bilaminar zirconia (ZC) FDPs and 206 MC FDPs were included. ZC FDPs were significantly associated with more failures (RR=3.64, p=0.009) and more Ceramic Chipping (RR=2.92, p<0.0001) when compared to MC FDPs. Higher risks of Framework Fracture (RR=4.57, p=0.18), Loss of Retention (RR=4.79, p=0.17), Secondary Caries (RR=1.25, p=0.68), Endodontic complications (RR=1.30, p=0.74) and Marginal Integrity (RR=1.07, p=0.88) were also found in ZC FDPs when compared to those of MC FDPs, but with no statistical difference. CONCLUSION: The current evidence continues to support the preference for traditional MC FDPs over ZC FDPs. Studies indicate that ZC FDPs have higher failure rates and more complications compared to MC FDPs, with ceramic chipping being a significant concern. There is lack of long term (>10 years follow-up) evidence of the clinical performance of ZC FDPs and monolithic zirconia FDPs. CLINICAL SIGNIFICANCE: The study suggests that despite the growing popularity of zirconia, evidence shows MC FDPs may still be considered preferable to ZC FDPs.

Biological properties of a novel solution based on silver nanoclusters for arresting dentin caries.

Objectives: To test the biological properties of a novel non-restorative treatment method for arresting dentin caries based on silver nanoclusters (AgNCls) synthesized in polymethacrylic acid (PMAA). Methods: Synthesis of AgNCls was performed by photoreduction of AgNO3 in PMAA with 355 nm/wavelength light. AgNCls/PMAA was characterized by absorption/fluorescence spectroscopy and optical and atomic force microscopy. The stability of the clusters in an aerated PMAA solution was evaluated by means of fluorescence spectroscopy. Cytotoxicity was assessed using the MTT assay and antibacterial effect was determined for minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and colony forming (CFU) of Streptococcus mutans (S. mutans) and Lactobacillus acidophilus (L. acidophilus). 38% Silver Diammine Fluoride (SDF) was used for the control groups. Results: Chemical and structural identity of the clusters did not change within 9 months; Cell viability of 92%-89% was found after 24-48 h respectively. MIC and MBC were determined from 1:16 and 1:8 dilutions, respectively. Log CFU counts of S. mutans, and L. acidophilus treated with AgNCls/PMAA (3.4 ppm of silver) were significantly lower than in the control groups and even lower than when the same bacterial strains were treated with SDF (15,525 ppm of silver). Conclusions: AgNCls/PMAA presented chemical stability, acceptable cytotoxicity, and a potential antibacterial effect for strains associated with caries lesions at very low concentrations of silver.

Association of dietary inflammation with tooth loss and cognitive decline in older adults from cross-sectional data: The moderated role of albumin.

OBJECTIVE: Growing evidence suggests a potential connection between tooth loss and cognitive function in recent years. Increasing studies have focused on their inter-relationship, however, the underlying mechanism has yet to be fully elucidated. Few studies have considered the role of dietary inflammation and serum albumin in the association between tooth loss and cognitive function. Therefore, the aim of this study was to explore the role of dietary inflammation and serum albumin in the association between tooth loss and cognitive impairment. METHODS: A sample of 1,009 US adults from the National Health and Nutrition Examination Survey (NHANES) provided data on oral condition, cognitive function, dietary intake, and serum tests. The association between tooth loss (exposure variable) and cognitive function (outcome variable) was assessed by linear regression. Furthermore, a moderated mediation model was established to examine the influence of dietary inflammation on the association between tooth loss and cognitive tests, and the visualization of the moderating effect of serum albumin concentration was displayed through the Johnson-Neyman curve. RESULTS: Participants with impaired dentition had worse cognitive function and a higher Dietary Inflammation Index (DII). DII was highly correlated with Immediate Recall Test (IR), Animal Fluency Test (AFT), and Digit Symbol Substitution Test (DSST), which mediated 16.46 %, 14.41 % and 11.28 % of the effect between tooth loss and cognitive functions. Additionally, the relationship between DII and DSST was moderated by serum albumin concentration. CONCLUSION: Tooth loss was associated with cognitive function which was affected by pro-inflammatory dietary patterns and serum albumin level. CLINICAL SIGNIFICANCE: This study presents evidence for dentists that dietary pattern change due to tooth loss plays a role in cognitive deterioration, which can also be moderated by serum albumin level. Therefore, the preservation of natural teeth is important for cognitive function, especially in an immunocompromised population with decreased serum albumin concentrations.

Proteomic profile of in situ acquired pellicle on tooth and restorative material surfaces.

OBJECTIVES: To evaluate and compare the proteomic profile of acquired pellicle on smooth bovine tooth and tooth-coloured restorative materials, including resin composite (RC), glass ionomer cement (GIC), and casein phosphopeptide-amorphous calcium phosphate modified GIC (CPP-ACP GIC). METHODS: Two-hour in situ pellicles on tooth/materials specimens mounted in oral appliances worn by ten healthy adults were investigated. Pellicle proteins and corresponding unstimulated whole saliva were quantitatively analysed through liquid chromatography-tandem mass spectrometry. RESULTS: Significantly higher amounts of protein were adsorbed onto tooth surface than restorative materials tested (4.11 ± 0.69 vs. 2.54 ± 0.38/2.98 ± 0.80/3.01 ± 0.37 µg, RC/GIC/CPP-ACP GIC). From the ten participants, 1,444 (487-1,086/person), 1,454 (645-1,051/person), 1,731 (454-1,475/person), or 1,597 (423-1,261/person) pellicle proteins were detected at least once on bovine tooth, RC, GIC, or CPP-ACP GIC, respectively, and with 1,072 (304-793/person) salivary proteins identified. Comparative quantification revealed minor differences between tooth and restorative materials pellicle profiles. High inter-individual variations in pellicle protein composition were demonstrated. Compared to the salivary protein profile, 214/57 proteins showed significantly increased/decreased abundance in pellicle formed on at least one substrate (fold change > 3.325/fold change < 0.301). Gene Ontology enrichment analysis showed some pellicle proteins detected with increased affinity to tooth/material surface were identified as being related to "calcium-dependent protein binding" or "cell-cell adhesion mediator activity". CONCLUSION: Similar protein quantity and composition was observed in 2 h in situ pellicles formed on different smooth restorative material surfaces. The proteomic profile of pellicles appeared distinct from that of the corresponding unstimulated whole saliva. CLINICAL SIGNIFICANCE: Host backgrounds appeared more influential on the proteomic profile of the in situ acquired pellicle than the underlying substrate characteristics among systemically and orally healthy adults. Pellicle proteins preferentially adsorbed on tooth/materials were putatively associated with calcium ion homeostasis or host-microbiota interaction.

Agreement in quantification of removable prosthesis plaque area coverage using a semi-automated planimetric assessment method.

OBJECTIVES: To determine the agreement of removable dental prosthesis cleanliness as assessed by a semi-automated planimetric method between images captured by a digital single-lens reflex camera (DSLR) and smartphone. METHODS: A total of 97 participants with removable prostheses were recruited for the quantification of the prosthesis plaque area coverage. The colour images of stained prosthesis plaque were obtained using both a DSLR camera and a smartphone. The prosthesis plaque area coverage was analysed in two ways: (i) prosthesis cleanliness index (PCI) and (ii) percentage plaque area coverage (PPC). The PPC (continuous data) was converted to the PCI (categorical data) to provide prevalence ordinal scales and the agreements in PCI ratings were determined using weighted Kappa statistics. Agreement of PPC scores was determined through assessing directional, standardised directional, and absolute differences and correlation analyses. RESULTS: Weighted Kappa values of agreement between PCI categories were excellent (> 0.80) for all comparisons. The mean PPC was 24.79 % as determined by DSLR and 25.37 % as determined by smartphone. There was no statistically significant difference in the means of PPC between the DSLR and smartphone (P = 0.149). The standardised directional difference was 0.15 ('small'). The mean absolute difference was 2.77. The interclass correlation coefficient was 0.98 ('excellent'). CONCLUSIONS: This method showed almost perfect agreements and allowed for threshold-based plaque segmentation on the removable prostheses. There was substantial agreement between DSLR and smartphone assessment of prosthesis plaque area coverage as determined by a semi-automated planimetric assessment. CLINICAL SIGNIFICANCE: This semi-automated planimetric assessment method has implications for monitoring removable prosthesis hygiene initiatives by offering a valid, reliable, and quantitative method of assessment with potential use in managed care and community settings.

A qualitative analysis of dentists' understanding and management of non-carious cervical lesions (NCCL).

INTRODUCTION: Non-carious cervical lesions (NCCLs) are considered to have a multi-factorial aetiology and their management is affected by a range of variables perhaps most importantly clinical judgement. The aim of this study was to elicit information from practicing dentists, using interviews, to explore their understanding of NCCL aetiology, the decision-making criteria of when to restore, and the restorative techniques used to restore NCCLs. This may help identify gaps or anomalies in our understanding to inform future research and clinical practice for the management of NCCLs. METHODS: An interview guide was developed from a literature search which formed 2 domains framed around understanding and management of NCCLs based on: understanding of diagnosis and aetiology, and factors affecting decision making for management. Practicing dentists with more than 10 years of experience were purposively recruited to conduct in-depth, semi-structured interviews. Fifteen interviews were audio recorded and transcribed verbatim. A thematic content analysis was conducted and the results analysed. RESULTS: From the thematic analysis, 2 domains were identified. In the domain of "diagnosis and aetiology", while participants have similar understanding and methods of diagnosing NCCL, most stated NCCLs in a patient were caused by a "main aetiology" such as "abrasion", "abfraction" while few described the inter-relationship of these aetiological factors. In the domain of "factors affecting decision making". "Patient reported symptoms" and "lesion dimension" were the main factors that affected participants' decision to provide restorative or non-restorative management. However, a "restorative threshold" was not able to be identified. CONCLUSION: There was notable variety in participants' understanding of the aetiology, management, and treatment of NCCLs, particularly the restorative threshold of when to treat. CLINICAL SIGNIFICANCE: The variability demonstrates the need to have a clearer understanding of the key elements that affect the management of NCCLs and better information to support the decision of when to treat.

Application of 20% silver nanoclusters in polymethacrylic acid on simulated dentin caries; its penetration depth and effect on surface hardness.

The aims of this study were: To evaluate the surface hardness of simulated dentin caries lesions treated with either silver nanoclusters (AgNCls) synthesized in polymethacrylic acid (PMAA) or 38% silver diammine fluoride (SDF), as well as observe the penetration of the treatment solutions into the simulated caries lesions. Dentin blocks 4 mm thick obtained from caries-free third molars were sectioned and then simulated caries lesions on the occlusal dentin surfaces were created. Each specimen (n = 8) was divided into four sections: (A) treated with 20% AgNCls/PMAA; (B) treated with SDF 38% (FAgamin, Tedequim, Cordoba, Argentina); (C) sound tooth protected by nail-varnish during artificial caries generation (positive control); and (D) artificial caries lesion without surface treatment (negative control). AgNCls/PMAA or SDF were applied on the simulated lesions with a microbrush for 10 s, then excess removed. The surface hardness was measured by means of Vickers indentation test. To trace the depth of penetration, up to 400 µm, of silver ions, elemental composition of the samples was observed using EDX, coupled with SEM, and measured every 50 µm from the surface towards the pulp chamber. Laser Induced Breakdown Spectroscopy (LIBS) was also employed to trace silver ion penetration; the atomic silver line 328.06 nm was used with a 60 µm laser spot size to a depth of 240 µm. Student's-t test identified significant differences between treatment groups for each depth and the Bonferroni test was used for statistical analysis of all groups (p < 0.05). Mean surface hardness values obtained were 111.2 MPa, 72.3 MPa, 103.3 MPa and 50.5 MPa for groups A, B, C and D respectively. There was a significant difference between groups A and C compared with groups B and D, the group treated with AgNCls/PMAA achieved the highest surface hardness, similar or higher than the sound dentin control. A constant presence of silver was observed throughout the depth of the sample for group A, while group B showed a peak concentration of silver at the surface with a significant drop beyond 50 µm. The 20% AgNCls/PMAA solution applied to simulated dentin caries lesions achieved the recovery of surface hardness equivalent to sound dentin with the penetration of silver ions throughout the depth of the lesion.

Morphology and mechanical performance of dental crown designed by 3D-DCGAN.

OBJECTIVES: This study utilised an Artificial Intelligence (AI) method, namely 3D-Deep Convolutional Generative Adversarial Network (3D-DCGAN), which is one of the true 3D machine learning methods, as an automatic algorithm to design a dental crown. METHODS: Six hundred sets of digital casts containing mandibular second premolars and their adjacent and antagonist teeth obtained from healthy personnel were machine-learned using 3D-DCGAN. Additional 12 sets of data were used as the test dataset, whereas the natural second premolars in the test dataset were compared with the designs in (1) 3D-DCGAN, (2) CEREC Biogeneric, and (3) CAD for morphological parameters of 3D similarity, cusp angle, occlusal contact point number and area, and in silico fatigue simulations with finite element (FE) using lithium disilicate material. RESULTS: The 3D-DCGAN design and natural teeth had the lowest discrepancy in morphology compared with the other groups (root mean square value = 0.3611). The Biogeneric design showed a significantly (p < 0.05) higher cusp angle (67.11°) than that of the 3D-DCGAN design (49.43°) and natural tooth (54.05°). No significant difference was observed in the number and area of occlusal contact points among the four groups. FE analysis showed that the 3D-DCGAN design had the best match to the natural tooth regarding the stress distribution in the crown. The 3D-DCGAN design was subjected to 26.73 MPa and the natural tooth was subjected to 23.97 MPa stress at the central fossa area under physiological occlusal force (300 N); the two groups showed similar fatigue lifetimes (F-N curve) under simulated cyclic loading of 100-400 N. Designs with Biogeneric or technician would yield respectively higher or lower fatigue lifetime than natural teeth. SIGNIFICANCE: This study demonstrated that 3D-DCGAN could be utilised to design personalised dental crowns with high accuracy that can mimic both the morphology and biomechanics of natural teeth.