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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

A Narrative Review of Bioactive Glass-Loaded Dental Resin Composites.

This review aims to provide a comprehensive analysis of the characterizations of bioactive glass (BAG)-loaded dental resin-based composite materials. Online databases (Web of Science, PubMed, and Science Direct) were used to collect data published from January 2011 to January 2022. Only BAG-containing resin adhesive and resin restorative composites are discussed in this narrative review. BAG-loaded resin composites exhibit excellent mineralization ability reflecting enhanced ion release, pH elevation, and apatite formation, especially regarding high BAG loading. This aids the anti-demineralization and remineralization of teeth. Furthermore, BAG-loaded resin composites demonstrated in vitro biocompatibility and antibacterial performance. It has been suggested that BAG fillers with small particle sizes and no more than 20 wt% in terms of loading amount should be used to guarantee the appropriate mechanical properties of resin composites. However, most of these studies focused on one or some aspects using different resin systems, BAG types, and BAG amounts. As such, this makes the comparison difficult, and it is essential to find an optimal balance between different properties. BAG-loaded resin composites can be regarded as bioactive materials, which present major benefits in dentistry, especially their capability in the bacterial inhibition, cell biocompatibility, anti-demineralization, and remineralization of teeth.

Evaluation of 12-hour in situ bacterial colonization on smooth restorative material surfaces.

OBJECTIVES: The aim of this study was to investigate 12 h in situ bacterial colonization on different restorative materials with smooth surfaces. METHODS: The restorative materials examined included resin composite (RC), a glass ionomer cement (GIC), casein phosphopeptide-amorphous calcium phosphate modified GIC (CPP-ACP GIC, 3% w/w), and control bovine teeth. Polished bovine tooth and material slabs (average roughness < 0.2 µm) were prepared. Specimens were mounted in a custom-made removable appliance, then placed for 12 h in the oral cavities of ten systemically and orally healthy volunteers (23-30 year-old). The colonized bacteria on the restorative materials were evaluated by real-time quantitative polymerase chain reaction (q-PCR) and 16S rRNA gene sequencing. RESULTS: The in situ bacterial colonization, in terms of both total bacterial biomass and bacterial community composition, was similar among the restorative materials tested. The microbiota of early plaque comprised similar "core microbiota", which were dominated by species within the genera of Streptococcus, Haemophilus, Neisseria, Gemella, and Prevotella, regardless of the type of underlying surface. Beta-diversity analyses revealed that most differences in the microbiota profile among samples were attributed to inter-individual variation, rather than the different materials. The microbial community composition of 12 h in situ plaque appeared different from that of whole saliva. CONCLUSIONS: Similar bacterial composition of 12-h in situ plaque was observed on smooth material and tooth surfaces tested, including species mainly from within the Streptococcus, Haemophilus, Neisseria, Gemella, or Prevotella genera. CLINICAL SIGNIFICANCE: The high inter-individual variation in plaque microbiota observed in this study, which outweighed the potential differences among various materials, demonstrated the importance of an in situ biofilm model as well as consideration of the host oral an microbial backgrounds when evaluating the bacterial colonization on restorative materials.

A systematic review of the proteomic profile of in vivo acquired enamel pellicle on permanent teeth.

OBJECTIVES: To provide a comprehensive review on the proteomic profile of in vivo acquired enamel pellicle (AEP) formed on permanent teeth. DATA/SOURCES: PubMed, EMBASE (Ovid) and Web of Science databases were searched for eligible studies (up to December 2020). Studies reporting mass spectrometry-based proteomic analysis of in vivo AEP were included. Risk of bias assessment was performed. Qualitative and quantitative proteomic data were extracted, integrated, then followed by bioinformatic analysis. STUDY SELECTION: Eleven studies were included, involving 122 systemically and dentally healthy adults from four different research groups. Pooled AEP samples from study participants were the normal practice for all included studies. A total of 257/93/108/870 non-redundant proteins were detectable from the in vivo ≤ 5 min/10-min/60-min/2-h AEP samples, respectively. Fifteen "core in vivo 2-h AEP proteins", generally associated with immune and/or inflammatory responses, were consistently identifiable from all four research groups. Eight included studies conducted relative quantitative proteomic analysis, while no statistical analysis could be undertaken due to the inherent limitation of the relative quantification in the proteomics analyses of these studies. CONCLUSIONS: A systematic review on adult in vivo AEP proteomic profile was undertaken. The results provide a comprehensive appreciation of the AEP proteome in healthy individuals from in vivo sampling. Further studies are warranted to clarify the biological role of AEP on oral health, particularly at an individual level. CLINICAL SIGNIFICANCE: A comprehensive appreciation of the proteomic profile of in vivo AEP in healthy individuals is essential to further understand its functions in oral health and disease. The information generated also provides insights for future studies.

The biocompatibility of glass-fibre reinforced composites (GFRCs) - a systematic review.

PURPOSE: Fiber-reinforced composites (FRCs) have received considerable attention, owing to their potential use in dental prostheses or bone fracture fixation applications. The aim of this systematic review was to analyze and report the biological properties of FRCs reported in the existing literature. STUDY SELECTIONS: A systematic search of four databases (PubMed/MEDLINE, Scopus, Web of Science, and Cochrane library) was performed to identify all relevant studies published between 1962 and 2019. The search was limited to laboratory-based studies published in English. Citation mining was also performed through cross-referencing of included studies and hand searching of relevant journals. RESULTS: A total of 1283 potentially relevant articles were initially identified, and thirty-three articles were full-text screened. In the final ten studies included for review, four investigated bacterial adhesion and growth abilities on FRCs, four investigated the fibroblastic cytotoxicity of different surface-treated FRCs, and two investigated the osseointegration between bone and FRCs. Owing to the heterogeneity of fiber types, FRC-coating, and lack of standardized testing protocols, a meta-analysis was not feasible. The included studies indicated that glass fibers, and in particular E-glass fibers, are superior to ceramics and other FRCs in terms of bacterial adherence, fibroblast cytotoxicity, and cell viability. CONCLUSIONS: Glass-fiber-reinforced composites are cytocompatible materials that possess satisfactory biological properties and can be used in dental prosthesis and craniofacial implants. Further research is necessary to regulate the matrix ion release/degradation of FRCs to prolong the initially demonstrated properties.

Analysing Complex Oral Protein Samples: Complete Workflow and Case Analysis of Salivary Pellicles.

Studies on small quantity, highly complex protein samples, such as salivary pellicle, have been enabled by recent major technological and analytical breakthroughs. Advances in mass spectrometry-based computational proteomics such as Multidimensional Protein Identification Technology have allowed precise identification and quantification of complex protein samples on a proteome-wide scale, which has enabled the determination of corresponding genes and cellular functions at the protein level. The latter was achieved via protein-protein interaction mapping with Gene Ontology annotation. In recent years, the application of these technologies has broken various barriers in small-quantity-complex-protein research such as salivary pellicle. This review provides a concise summary of contemporary proteomic techniques contributing to (1) increased complex protein (up to hundreds) identification using minute sample sizes (µg level), (2) precise protein quantification by advanced stable isotope labelling or label-free approaches and (3) the emerging concepts and techniques regarding computational integration, such as the Gene Ontology Consortium and protein-protein interaction mapping. The latter integrates the structural, genomic, and biological context of proteins and genes to predict protein interactions and functional connections in a given biological context. The same technological breakthroughs and computational integration concepts can also be applied to other low-volume oral protein complexes such as gingival crevicular or peri-implant sulcular fluids.

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.

Mechanisms of silver diamine fluoride on arresting caries: a literature review.

OBJECTIVE: To review the evidence regarding the mechanisms of silver diamine fluoride (SDF) for arresting caries. METHODS: A literature search was conducted using the keywords silver diamine fluoride, and its alternative names, in seven databases: PubMed, Embase and Scopus (English); China National Knowledge Infrastructure (Chinese); Bilioteca Virtual em Saude (Portuguese); Biblioteca Virtual en Salud Espana (Spanish); and Ichushi-Web (Japanese). The titles and abstracts were screened. Full texts were retrieved for publications that studied mechanisms of actions of SDF, including its effects on remineralisation of carious lesions and on cariogenic bacteria. RESULTS: A total of 1,123 publications were identified. Twenty-nine articles were included and they investigated the effect of SDF on cariogenic bacteria and dental hard tissues. Eleven studies investigated the antibacterial properties of SDF. They found that SDF was bactericidal to cariogenic bacteria, mainly Streptococcus mutans. It inhibited the growth of cariogenic biofilms on teeth. Twenty studies reported the remineralisation of demineralised enamel or dentine by SDF. They found that mineral loss of demineralised enamel and dentine was reduced after SDF treatment. A highly mineralised surface rich in calcium and phosphate was formed on arrested carious lesions. Four studies examined the effect of SDF on dentine collagen. They found that SDF inhibited collagenases (matrix metalloproteinases and cysteine cathepsins) and protected dentine collagen from destruction. CONCLUSION: SDF is a bactericidal agent and reduces the growth of cariogenic bacteria. It inhibits demineralisation and promotes the remineralisation of demineralised enamel and dentine. It also hampers degradation of the dentine collagen.

Mechanical properties, water sorption characteristics, and compound release of grape seed extract-incorporated resins.

OBJECTIVE: This study evaluated the effect of grape seed extract (GSE) incorporation on the mechanical properties, water sorption, solubility, and GSE release from the experimental adhesive resins. MATERIAL AND METHODS: An experimental comonomer mixture, consisting of 40% Bis-GMA, 30% Bis MP, 28% HEMA, 0.26% camphorquinone and 1% EDMAB, was used to prepare four GSE-incorporated adhesive resins at concentrations of 0.5, 1, 1.5, and 2 wt%. The neat resin without GSE was used as the control. Six resin beams (25 mm x 2 mm x 2 mm) per group were prepared for flexural strength and modulus of elasticity evaluations using a universal testing machine at a crosshead speed of 1 mm/min. Five disks (6 mm in diameter and 2 mm in thickness) per group were used for microhardness measurements using a Leitz micro-hardness tester with Leica Qgo software. Five disks (7 mm in diameter and 2 mm in thickness) per group were prepared and stored in deionized water for 28 days. Water sorption, solubility, and GSE release in deionized water were calculated for each GSE-incorporated adhesive at the end of 28th day. Data was evaluated using one-way ANOVA and Tukey multiple comparisons. RESULTS: Flexural strength, modulus of elasticity and microhardness of GSE-incorporated adhesive decreased significantly with incorporation of 1.5% of GSE (p<0.05). Addition of GSE had no effect on the water sorption of the adhesive resins (p=0.33). The solubility of the resin also increased significantly with incorporation of 1.5% of GSE (p<0.05). Quantities of GSE release increased with increased concentration of GSE in the adhesive resin. CONCLUSION: Up to 1% of GSE can be incorporated into a dental adhesive resin without interfering with the mechanical properties or solubility of the resins.

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.