Effects of Metformin Delivery via Biomaterials on Bone and Dental Tissue Engineering.

Bone tissue engineering is a promising approach that uses seed-cell-scaffold drug delivery systems to reconstruct bone defects caused by trauma, tumors, or other diseases (e.g., periodontitis). Metformin, a widely used medication for type II diabetes, has the ability to enhance osteogenesis and angiogenesis by promoting cell migration and differentiation. Metformin promotes osteogenic differentiation, mineralization, and bone defect regeneration via activation of the AMP-activated kinase (AMPK) signaling pathway. Bone tissue engineering depends highly on vascular networks for adequate oxygen and nutrition supply. Metformin also enhances vascular differentiation via the AMPK/mechanistic target of the rapamycin kinase (mTOR)/NLR family pyrin domain containing the 3 (NLRP3) inflammasome signaling axis. This is the first review article on the effects of metformin on stem cells and bone tissue engineering. In this paper, we review the cutting-edge research on the effects of metformin on bone tissue engineering. This includes metformin delivery via tissue engineering scaffolds, metformin-induced enhancement of various types of stem cells, and metformin-induced promotion of osteogenesis, angiogenesis, and its regulatory pathways. In addition, the dental, craniofacial, and orthopedic applications of metformin in bone repair and regeneration are also discussed.

Flavonoid Baicalein Suppresses Oral Biofilms and Protects Enamel Hardness to Combat Dental Caries.

The objectives of this study were to investigate the effects of a novel method using flavonoids to inhibit Streptococcus mutans (S. mutans), Candida albicans (C. albicans) and dual-species biofilms and to protect enamel hardness in a biofilm-based caries model for the first time. Several flavonoids, including baicalein, naringenin and catechin, were tested. Gold-standard chlorhexidine (CHX) and untreated (UC) groups served as controls. Optimal concentrations were determined by cytotoxicity assay. Biofilm MTT, colony-forming-units (CFUs), biofilm biomass, lactic acid and polysaccharide production were evaluated. Real-time-polymerase-chain reaction (qRT-PCR) was used to determine gene expressions in biofilms. Demineralization of human enamel was induced via S. mutans-C. albicans biofilms, and enamel hardness was measured. Compared to CHX and UC groups, the baicalein group achieved the greatest reduction in S. mutans, C. albicans and S. mutans-C. albicans biofilms, yielding the least metabolic activity, polysaccharide synthesis and lactic acid production (p < 0.05). The biofilm CFU was decreased in baicalein group by 5 logs, 4 logs, 5 logs, for S. mutans, C. albicans and S. mutans-C. albicans biofilms, respectively, compared to UC group. When tested in a S. mutans-C. albicans in vitro caries model, the baicalein group substantially reduced enamel demineralization under biofilms, yielding an enamel hardness that was 2.75 times greater than that of UC group. Hence, the novel baicalein method is promising to inhibit dental caries by reducing biofilm formation and protecting enamel hardness.

Senior dental students' perceptions of evidence-based dentistry.

INTRODUCTION: This study aimed to assess senior dental students' knowledge and attitudes regarding evidence-based dentistry (EBD), their use of the current literature and considerations for patient preferences. MATERIALS AND METHODS: A modified Knowledge, Attitudes, Access, and Confidence Evaluation (KACE) survey was administered to collect data from senior dental students at the University of Maryland School of Dentistry (UMSOD). The chi-squared test was used to compare the correct response rates of each question in the knowledge of scientific evidence domain. Spearman's rank correlation coefficient was conducted to examine correlations between students' knowledge of scientific evidence and their confidence in appraising the study qualities. RESULTS: 61 seniors (out of 130) answered all survey questions. Participants displayed an intermediate level of knowledge of EBD. Only 15% of participants correctly answered to the most appropriate design; the distribution of responses appeared significantly different amongst the questions in the basic knowledge section (chi-squared test, p < .0001). There was no or very weak correlation between students' knowledge of scientific evidence and their confidence in appraising study qualities (Spearman's ρ = 0-0.18). The participants highly valued the use of the current literature and patient preferences. However, their preferred sources of scientific evidence were the Internet excluding Cochrane reviews (60%) and colleagues (56%). Forty per cent of participants rarely or never used textbooks. CONCLUSION: Whilst seniors felt confident in evaluating study qualities and implementing EBD in routine practice, their understanding of the study design was poor. Seniors' preferred sources of scientific evidence were non-peer-reviewed Internet sources and colleagues.

Advances in implant therapy in North America: Improved outcomes and application in the compromised dentition.

Advances in dental implant therapy have strengthened our understanding of the management of the implant-soft tissue interface, with site-specific implications ranging from marginal tissue management and esthetics to immediate placement and restoration, and extend to patient-level implications of systemic conditions. The advancements in implant therapy have placed an increased emphasis on patient-centered outcomes. In this paper, the following conclusions can be drawn: improvements in both esthetics and long-term maintenance have been guided by the study of the marginal peri-implant tissues leading to innovations in implant design along the implant-abutment interface. Patient expectations for simple and realistic time intervals for treatment have promoted the use of immediate implant placement and restoration. The expansion of implant therapy offers implant options for patients with medical conditions, with one in particular, diabetes mellitus a focus of this paper. Studies on patients with diabetes are supporting the development of evidence-based treatment considerations with broader application and greater benefits for the use of implant therapy across a larger patient population. This paper is not intended to offer a comprehensive review, but offers a representative review of some of the many contributions of USA and North American clinicians to the global scientific dialogue that has guided the development of dental implant therapy.

Novel Nanocomposite Inhibiting Caries at the Enamel Restoration Margins in an In Vitro Saliva-Derived Biofilm Secondary Caries Model.

Secondary caries often occurs at the tooth-composite margins. This study developed a novel bioactive composite containing DMAHDM (dimethylaminohexadecyl methacrylate) and NACP (nanoparticles of amorphous calcium phosphate), inhibiting caries at the enamel restoration margins in an in vitro saliva-derived biofilm secondary caries model for the first time. Four composites were tested: (1) Heliomolar nanocomposite, (2) 0% DMAHDM + 0% NACP, (3) 3% DMAHDM + 0% NACP, (D) 3% DMAHDM + 30% NACP. Saliva-derived biofilms were tested for antibacterial effects of the composites. Bovine enamel restorations were cultured with biofilms, Ca and P ion release of nanocomposite and enamel hardness at the enamel restoration margins was measured. Incorporation of DMAHDM and NACP into composite did not affect the mechanical properties (p > 0.05). The biofilms' CFU (colony-forming units) were reduced by 2 logs via DMAHDM (p < 0.05). Ca and P ion release of the nanocomposite was increased at cariogenic low pH. Enamel hardness at the margins for DMAHDM group was 25% higher than control (p < 0.05). With DMAHDM + NACP, the enamel hardness was the greatest and about 50% higher than control (p < 0.05). Therefore, the novel composite containing DMAHDM and NACP was strongly antibacterial and inhibited enamel demineralization, resulting in enamel hardness at the margins under biofilms that approached the hardness of healthy enamel.

The McGill Denture Satisfaction Questionnaire revisited: Exploratory factor analysis of a binational sample.

OBJECTIVES: To examine the McGill Denture Satisfaction Questionnaire (MDSQ) in terms of dimensionality, item reduction and construct validity in a binational sample of complete denture wearers. MATERIALS AND METHODS: We conducted secondary analyses of baseline data from two studies on implant-retained overdentures: a quasi-experimental study in the United States (n = 145) and a randomised trial in Brazil (n = 120). All participants wore upper/lower dentures and responded at baseline to the MDSQ items concerning their original mandibular dentures. A putative model of the MDSQ items resulted in two question subsets: (a) overall satisfaction, retention/stability, aesthetics, cleaning, speech and comfort, plus general chewing ability; (b) mastication of specific foods. Analyses focused on the internal consistency of each subset and possible item reduction, using Cronbach's alpha (Cα), inter-item correlation and exploratory factor analysis (EFA). RESULTS: The 1st subset showed high inter-item correlation for most question combinations and no redundancy (r ≤ .8). An item on cleaning had low correlation, but its removal does not increase internal consistency (Cα ≥ .83). Results were similar for both studies, with EFA showing a single significant factor (namely "overall satisfaction, lower denture") able to explain nearly 54% of the variance. The 2nd subset also shows strong internal consistency (Cα ≥ .95) and inter-item correlation, with a single factor representing 65% of the variation. CONCLUSIONS: This study discloses the reliability and construct validity of the MDSQ for patient-centred evaluation of complete dental prostheses in the edentulous mandible. Findings also support the use of both "overall satisfaction" and "masticatory ability" as summary scores, for improved outcome assessment.

Gradient metal nanoislands as a unified surface enhanced Raman scattering and surface enhanced infrared absorption platform for analytics.

In the last few decades, the use of plasmonics in vibrational spectroscopy has expanded the scope of (bio)analytical investigations. Nevertheless, there is a demand for a combined platform that can be simultaneously efficient for Surface Enhanced Raman Scattering (SERS) and Surface Enhanced Infrared Absorption (SEIRA). Here, we present a solution on the basis of a plasmonic Ag nanoparticle layer with a thickness gradient. The optical resonance along the layer varies from the visible to the infrared range offering optimal and intermediate sites for SERS and SEIRA of the analyte molecule (mercaptobenzonitrile). Enhancement factors for the same mode were determined to be ca. 104 and 170 for SERS and SEIRA, respectively. We present a full optical and vibrational characterization and demonstrate further tunability. The platform resolves reproducibility and comparability issues by a combination of the two methods. It also offers individualized solutions for different investigation conditions, i.e. a choice between excitation wavelengths and resonant Raman molecules. The multiple applicabilities of the presented unifying substrate can contribute to the expansion of the vibrational spectroscopic field and to analytics.

A Novel Dental Sealant Containing Dimethylaminohexadecyl Methacrylate Suppresses the Cariogenic Pathogenicity of Streptococcus mutans Biofilms.

Cariogenic oral biofilms are strongly linked to dental caries around dental sealants. Quaternary ammonium monomers copolymerized with dental resin systems have been increasingly explored for modulation of biofilm growth. Here, we investigated the effect of dimethylaminohexadecyl methacrylate (DMAHDM) on the cariogenic pathogenicity of Streptococcus mutans (S. mutans) biofilms. DMAHDM at 5 mass% was incorporated into a parental formulation containing 20 mass% nanoparticles of amorphous calcium phosphate (NACP). S. mutans biofilms were grown on the formulations, and biofilm inhibition and virulence properties were assessed. The tolerances to acid stress and hydrogen peroxide stress were also evaluated. Our findings suggest that incorporating 5% DMAHDM into 20% NACP-containing sealants (1) imparts a detrimental biological effect on S. mutans by reducing colony-forming unit counts, metabolic activity and exopolysaccharide synthesis; and (2) reduces overall acid production and tolerance to oxygen stress, two major virulence factors of this microorganism. These results provide a perspective on the value of integrating bioactive restorative materials with traditional caries management approaches in clinical practice. Contact-killing strategies via dental materials aiming to prevent or at least reduce high numbers of cariogenic bacteria may be a promising approach to decrease caries in patients at high risk.

The effect of embryonic origin on the osteoinductive potential of bone allografts.

STATEMENT OF PROBLEM: Allografts with osteoinduction potential are widely used to augment bone in surgical and prosthetic rehabilitations. However, osteoinduction potential varies among commercially available allografts. Donor bones are derived from different embryonic origins, either the neural crest or mesoderm. Whether the origin of the bones affects the osteoinductivity of allograftsis is unclear. PURPOSE: The purpose of this ex vivo study was to investigate the osteoinduction potential of allografts derived from bones with distinct embryonic origins. MATERIAL AND METHODS: Allografts were obtained from human frontal and parietal bones at 2 different ages (fetal and adult). The specimens were divided into 4 groups: adult frontal (n=5), adult parietal (n=5), fetal frontal (n=10), and fetal parietal (n=10). Two investigations were conducted to assess the osteoinductive potential of these allografts. First, the osteogenesis of human osteoblasts exposed to these allografts were evaluated by analyzing the expression of runt-related transcription factor 2 (RUNX2), collagen type 1 alpha 2 chain (COL1A2), and bone gamma-carboxyglutamate protein (BGLAP) genes using quantitative real-time polymerase chain reaction (qRT-PCR). Second, the protein content of the adult frontal and parietal bone matrices was analyzed using liquid chromatography tandem mass spectrometry (LC-MS/MS). One-way ANOVA and the t test were used for statistical analyses of the gene and protein expression of the groups (α=.05). RESULTS: No difference was found in the gene expression of the cells exposed to frontal or parietal bones. However, all 3 genes were significantly overexpressed in cells treated with fetal bones compared with adult bones. No difference was found in protein expression between adult frontal and adult parietal bones. CONCLUSIONS: No difference was found in the osteoinductive capacity of frontal and parietal bones used as allografts. However, the osteoinductivity of fetal bones can be higher than that of adult bones. Further microanalyses are needed to determine the protein content of fetal bones.

Tooth Fairy Study- The South Texas Oral Health Network Collaboration.

PURPOSE: This study's purpose was to examine the processes and the potential for dental practitioners to address environmental health exposure risks to their patients through dental practice-based research participation. To explore this, the South Texas Oral Health Network (STOHN) initiated a collaboration with The Tooth Fairy National Study investigating toxicants stored in deciduous teeth as a potential neurodevelopmental risk factor. BACKGROUND: Neurodevelopmental disorders (ND), like Autism Spectrum Disorder (ASD), affect 1 in 68 live births. Evidence suggests that environmental chemicals may play a role in ASD risk and/or etiology by acting independently or through interactions with genetic vulnerabilities. Provider awareness of environmental exposure risk during pregnancy and early childhood in South Texas is low. Therefore, it is important to increase provider knowledge and awareness to enable greater communication with patients. STOHN serves as a conduit reaching large numbers of patients. This study also engaged practitioners in an ongoing national study with minimal impact on their practice. METHODS: The goal was to enroll twenty parents with children via ten dental practitioners. STOHN pediatric and general practitioners were recruited for the study. Practitioners were contacted by phone and in person. Upon completion of Human Subject Protection training, each practitioner participated in a study training taught by a public health educator in the department of Family and Community Medicine at University of Texas Health Science Center in San Antonio (UTHSCSA). Training topics included NDs, environmental health exposures, patient engagement, survey administration, and how to collect donated teeth. This collaboration allowed STOHN to gather control teeth as well as demographic and health information for the Tooth Fairy Study repository for future analyses. Participants received a thank you card from the Tooth Fairy and participating providers were highlighted in the monthly STOHN newsletter. EVALUATION RESULTS: Evaluation was threefold: Practitioner enrollment and retention; practitioner confidence in educating their patients about potential environmental risk exposures and completed surveys with donated teeth. CONCLUSION: The interdisciplinary collaboration between dental practitioners and medical researchers through STOHN provided an opportunity to increase practitioner knowledge and awareness of a novel health concern, while also raising their confidence and willingness to educate their patients about potential environmental exposure risks. UTHSCSA IRB Protocol # HSC20170132E.

Immediate loading vs. early/conventional loading of immediately placed implants in partially edentulous patients from the patients' perspective: A systematic review.

OBJECTIVES: This systematic review aimed at answering the following PICO question: In patients receiving immediate (Type 1) implant placement, how does immediate compare to early or conventional loading in terms of Patient-Reported Outcome Measures (PROMs)? MATERIAL AND METHODS: Following search strategy development, the OVID, PubMed, EMBASE, and Cochrane Database of Systematic Reviews databases were search for the relevant literature. All levels of evidence including randomized controlled trials, prospective and retrospective cohort studies, and case series of at least five patients were considered for possible inclusion. An additional manual search was performed by screening the reference lists of relevant studies and systematic reviews published up to May 2017. The intervention considered was the placement of immediate implant. Study selection and data extraction were performed independently by two reviewers. RESULTS: The search yielded a list of 1,102 references, of which nine were included in this systematic review. The limited number of studies included and the heterogeneity of the data identified prevented the performance of a meta-analysis. Three studies, one of which was a randomized controlled trial, allowed the extraction of comparative data specific to the aim of the present systematic review. The remaining studies allowed only data extraction for one single treatment modality and were viewed as single cohort studies. Overall, irrespective of the PROMs chosen, patients' satisfaction was overall high with little difference between the two loading protocols. Moreover, studies indicated a positive impact on oral health-related quality of life following immediate implant placement and loading. CONCLUSIONS: Within the limitations of the present systematic review, immediate implant placement and loading in single tooth edentulous space seems to be a well-accepted treatment modality from the patients' perspective and is worthy of consideration in clinical practice. However, the paucity of comparative data limits any definitive conclusions as to which loading protocol; immediate or early/conventional, should be given preference based on PROMs.

Group 3 ITI Consensus Report: Patient-reported outcome measures associated with implant dentistry.

OBJECTIVES: The aim of Working Group 3 was to focus on three topics that were assessed using patient-reported outcome measures (PROMs). These topics included the following: (a) the aesthetics of tooth and implant-supported fixed dental prostheses focusing on partially edentulous patients, (b) a comparison of fixed and removable implant-retained prostheses for edentulous populations, and (c) immediate versus early/conventional loading of immediately placed implants in partially edentate patients. PROMs include ratings of satisfaction and oral health-related quality of life (QHRQoL), as well as other indicators, that is, pain, general health-related quality of life (e.g., SF-36). MATERIALS AND METHODS: The Consensus Conference Group 3 participants discussed the findings of the three systematic review manuscripts. Following comprehensive discussions, participants developed consensus statements and recommendations that were then discussed in larger plenary sessions. Following this, any necessary modifications were made and approved. RESULTS: Patients were very satisfied with the aesthetics of implant-supported fixed dental prostheses and the surrounding mucosa. Implant neck design, restorative material, or use of a provisional restoration did not influence patients' ratings. Edentulous patients highly rate both removable and fixed implant-supported prostheses. However, they rate their ability to maintain their oral hygiene significantly higher with the removable prosthesis. Both immediate provisionalization and conventional loading receive positive patient-reported outcomes. CONCLUSIONS: Patient-reported outcome measures should be gathered in every clinical study in which the outcomes of oral rehabilitation with dental implants are investigated. PROMs, such as patients' satisfaction and QHRQoL, should supplement other clinical parameters in our clinical definition of success.

Formation of persisters in Streptococcus mutans biofilms induced by antibacterial dental monomer.

Antibacterial monomers can combat oral biofilm acids and caries; however, little is known on whether quaternary ammonium monomers (QAMs) would induce drug persistence in oral bacteria. The objectives of this study were to investigate the interactions of Streptococcus mutans (S. mutans) with dimethylaminohexadecyl methacrylate (DMAHDM), and determine for the first time whether DMAHDM could induce persisters in S. mutans. DMAHDM was synthesized using a modified Menschutkin reaction. Dose-dependent killing curves and time-dependent killing curves of planktonic S. mutans and biofilms were determined to evaluate drug persistence, using chlorhexidine (CHX) as control. The inheritability assay, minimum inhibitory concentration (MIC) and live/dead biofilm assay were determined to investigate persister characteristics. DMAHDM matched the killing potency of the gold standard CHX against S. mutans biofilms. DMAHDM and CHX induced drug persistence in S. mutans biofilms but not in planktonic bacteria. S. mutans biofilm persistence was not inheritable in that the tolerance to DMAHDM or CHX of the surviving persisters in the initial population was not transferred to subsequent generations, as displayed by the inheritability assay. The MIC of S. mutans parental strain and induced persisters remained the same. The induced persisters in S. mutans biofilms could be eliminated via higher doses of 300 µg/mL of DMAHDM and CHX. In conclusion, this study showed for the first time that (1) DMAHDM induced persisters only in biofilms, but not in planktonic bacteria; and (2) both DMAHDM-induced and CHX-induced S. mutans persister biofilms could be completely eradicated by even higher concentrations of DMAHDM and CHX. More studies are needed on the induction of persisters in oral biofilms for the development and use of a new generation of antibacterial dental monomers and resins.

Esthetic, clinical and patient-centered outcomes of immediately placed implants (Type 1) and early placed implants (Type 2): preliminary 3-month results of an ongoing randomized controlled clinical trial.

AIM: The objective of the study was to compare (i) esthetic, (ii) clinical and (iii) patient-centered outcomes following immediate (Type 1) and early implant placement (Type 2). MATERIAL AND METHODS: Thirty-eight subjects needing a single extraction (premolar to premolar) were randomly allocated to Type 1 or Type 2 implant placement. Three months following permanent crown insertion, evaluation of (i) esthetic outcomes using soft tissue positions, and the pink and white esthetic scores (PES/WES), (ii) clinical performance using probing pocket depth (PPD), modified plaque index (mPI) and modified sulcus bleeding index (mSBI) around each implant and (iii) patient satisfaction by means of a questionnaire using a visual analogue scale (VAS) was performed. RESULTS: Thirty-two patients completed the 3-month follow-up examination (Type 1, n = 17; Type 2, n = 15) with a 100% implant survival rate. Type 1 implants lost 0.54 ± 0.18 mm of mid-facial soft tissue height, while Type 2 implants lost 0.47 ± 0.31 mm (P > 0.05). The papillae height on the mesial and distal was reduced about 1 mm following both procedures. The PES/WES following Type 1 implant placement amounted to 13.7 ± 0.6 and 12.5 ± 0.7 in the Type 2 group (P > 0.05). PPD, mPI and mSBI were low in both groups (P > 0.05). Patient-centered outcomes failed to demonstrate any statistical difference between the two cohorts. CONCLUSION: Three months following final crown delivery, there were no significant differences in esthetic, clinical and patient-centered outcomes following Type 1 and Type 2 implant placement. On the short term, one may achieve good optimal esthetic and clinical results irrespective of these two placement protocols. These results need to be confirmed on the long term.

Provision of Specific Dental Procedures By General Dentists in the National Dental Practice-Based Research Network: Questionnaire Findings.

BACKGROUND: Objectives were to: (1) determine whether and how often general dentists (GDs) provide specific dental procedures; and (2) test the hypothesis that provision is associated with key dentist, practice, and patient characteristics. METHODS: GDs (n = 2,367) in the United States National Dental Practice-Based Research Network completed an Enrollment Questionnaire that included: (1) dentist; (2) practice; and (3) patient characteristics, and how commonly they provide each of 10 dental procedures. We determined how commonly procedures were provided and tested the hypothesis that provision was substantively related to the 3 sets of characteristics. RESULTS: Two procedure categories were classified as "uncommon" (orthodontics, periodontal surgery), 3 were "common" (molar endodontics; implants; non-surgical periodontics), and 5 were "very common" (restorative; esthetic procedures; extractions; removable prosthetics; non-molar endodontics). Dentist, practice, and patient characteristics were substantively related to procedure provision; several characteristics seemed to have pervasive effects, such as dentist gender, training after dental school, full-time/part- time status, private practice vs. institutional practice, presence of a specialist in the same practice, and insurance status of patients. CONCLUSIONS: As a group, GDs provide a comprehensive range of procedures. However, provision by individual dentists is substantively related to certain dentist, practice, and patient characteristics. A large number and broad range of factors seem to influence which procedures GDs provide. This may have implications for how GDs respond to the ever-changing landscape of dental care utilization, patient population demography, scope of practice, delivery models and GDs' evolving role in primary care.

Provision of specific dental procedures by general dentists in the National Dental Practice-Based Research Network: questionnaire findings.

BACKGROUND: Objectives were to: (1) determine whether and how often general dentists (GDs) provide specific dental procedures; and (2) test the hypothesis that provision is associated with key dentist, practice, and patient characteristics. METHODS: GDs (n = 2,367) in the United States National Dental Practice-Based Research Network completed an Enrollment Questionnaire that included: (1) dentist; (2) practice; and (3) patient characteristics, and how commonly they provide each of 10 dental procedures. We determined how commonly procedures were provided and tested the hypothesis that provision was substantively related to the three sets of characteristics. RESULTS: Two procedure categories were classified as "uncommon" (orthodontics, periodontal surgery), three were "common" (molar endodontics; implants; non-surgical periodontics), and five were "very common" (restorative; esthetic procedures; extractions; removable prosthetics; non-molar endodontics). Dentist, practice, and patient characteristics were substantively related to procedure provision; several characteristics seemed to have pervasive effects, such as dentist gender, training after dental school, full-time/part-time status, private practice vs. institutional practice, presence of a specialist in the same practice, and insurance status of patients. CONCLUSIONS: As a group, GDs provide a comprehensive range of procedures. However, provision by individual dentists is substantively related to certain dentist, practice, and patient characteristics. A large number and broad range of factors seem to influence which procedures GDs provide. This may have implications for how GDs respond to the ever-changing landscape of dental care utilization, patient population demography, scope of practice, delivery models and GDs' evolving role in primary care.

How concerns for bisphosphonate-induced osteonecrosis of the jaw affect clinical practice among dentists: a study from the South Texas Oral Health Network.

Bisphosphonate-induced osteonecrosis of the jaw (BONJ) represents a growing concern for dentists and patients in that it may alter clinical care. This study assessed the knowledge and perceptions of practicing dentists in relation to the risk of BONJ and how their knowledge and perceptions influence their decisions when developing treatment plans. For this study, a sample of dentists (n = 93) in South Texas completed a 38-item survey about BONJ knowledge and perception and their current clinical practices for patients undergoing bisphosphonate therapy. Knowledge score groupings reflected differences between low knowledge and high knowledge dentists in terms of their behavior concerning medical history, alternative treatments offered, and routine blood testing for patients on bisphosphonate therapy.

Novel antibacterial titanium implant healing abutment with dimethylaminohexadecyl methacrylate to combat implant-related infections.

OBJECTIVE: Implant-related infections from the adhesion and proliferation of dental plaque are a major challenge for dental implants. The objectives of this study were to: (1) develop novel antibacterial titanium (Ti) healing abutment; (2) investigate the inhibition of implant infection-related pathogenic bacteria and saliva-derived biofilm, and evaluate the biocompatibility of the new material for the first time. METHODS: Dimethylaminohexadecyl methacrylate (DMAHDM) and hydroxyapatite (HAP) were polymerized via polydopamine (PDA) on Ti. Staphylococcus aureus (S. aureus), Streptococcus sanguinis (S. sanguinis) and human saliva-derived biofilms were tested. After 4 weeks of DMAHDM release, the antibacterial efficacy of the DMAHDM remaining on Ti surface and the DMADHM in medium was tested. Biocompatibility was determined using human gingival fibroblasts (HGFs) and periodontal ligament stem cells (PDLSCs). RESULTS: The DMAHDM-loaded coating filled into the nano-voids in Ti surfaces. The modified Ti showed potent antibacterial activity, reducing the CFU of S. aureus, S. sanguinis and saliva-derived biofilms by 8, 7 and 4 log, respectively (P < 0.05). After 4 weeks of release, the modified Ti was still able to reduce S. aureus and S. sanguinis biofilm CFU by 1-3 log (P < 0.05). This provided strong antibacterial function for more than 4 weeks, which were the high-risk period for implant infections. The new material showed excellent biocompatibility when compared to control (P > 0.05). CONCLUSION: Novel DMAHDM-loaded Ti healing abutment had strong antibacterial effects, reducing biofilm CFUs by orders of magnitude, and lasting for over four weeks to cover the high-risk period for implant infections. The novel antibacterial Ti is promising to combat implant-related infections in dental, craniofacial and orthopedic applications.

Silica nanoparticles containing nano-silver and chlorhexidine respond to pH to suppress biofilm acids and modulate biofilms toward a non-cariogenic composition.

OBJECTIVES: Dental caries is caused by acids from biofilms. pH-sensitive nanoparticle carriers could achieve improved targeted effectiveness. The objectives of this study were to develop novel mesoporous silica nanoparticles carrying nanosilver and chlorhexidine (nMS-nAg-Chx), and investigate the inhibition of biofilms as well as the modulation of biofilm to suppress acidogenic and promote benign species for the first time. METHODS: nMS-nAg was synthesized via a modified sol-gel method. Carboxylate group functionalized nMS-nAg (COOH-nMS-nAg) was prepared and Chx was added via electrostatic interaction. Minimal inhibitory concentration (MIC), inhibition zone, and growth curves were evaluated. Streptococcus mutans (S. mutans), Streptococcus gordonii (S. gordonii), and Streptococcus sanguinis (S. sanguinis) formed multispecies biofilms. Metabolic activity, biofilm lactic acid, exopolysaccharides (EPS), and TaqMan real-time polymerase chain reaction (RT-PCR) were tested. Biofilm structures and biomass were observed by scanning electron microscopy (SEM) and live/dead bacteria staining. RESULTS: nMS-nAg-Chx possessed pH-responsive properties, where Chx release increased at lower pH. nMS-nAg-Chx showed good biocompatibility. nMS-nAg-Chx exhibited a strong antibacterial function, reducing biofilm metabolic activity and lactic acid as compared to control (p < 0.05, n = 6). Moreso, biofilm biomass was dramatically suppressed in nMS-nAg-Chx groups. In control group, there was an increasing trend of S. mutans proportion in the multispecies biofilm, with S. mutans reaching 89.1% at 72 h. In sharp contrast, in nMS-nAg-Chx group of 25 µg/mL, the ratio of S. mutans dropped to 43.7% and the proportion of S. gordonii and S. sanguinis increased from 19.8% and 10.9 to 69.8% and 56.3%, correspondingly. CONCLUSION: pH-sensitive nMS-nAg-Chx had potent antibacterial effects and modulated biofilm toward a non-cariogenic tendency, decreasing the cariogenic species nearly halved and increasing the benign species approximately twofold. nMS-nAg-Chx is promising for applications in mouth rinse and endodontic irrigants, and as fillers in resins to prevent caries.

Novel pit and fissure sealant with nano-CaF2 and antibacterial monomer: Fluoride recharge, microleakage, sealing ability and cytotoxicity.

Conventional resin-based sealants release minimal fluoride ions (F) and lack antibacterial activity. The objectives of this study were to: (1) develop a novel bioactive sealant containing calcium fluoride nanoparticles (nCaF2) and antibacterial dimethylaminohexadecyl methacrylate (DMAHDM), and (2) investigate mechanical performance, F recharge and re-release, microleakage, sealing ability and cytotoxicity. Helioseal F served as commercial control. The initial F release from sealant containing 20% nCaF2 was 25-fold that of Helioseal F. After ion exhaustion and recharge, the F re-release from bioactive sealant did not decrease with increasing number of recharge and re-release cycles. Elastic modulus of new bioactive sealant was 44% higher than Helioseal F. The new sealant had excellent sealing, minimal microleakage, and good cytocompatibility. Hence, the nanostructured sealant had substantial and sustained F release and antibacterial activity, good sealing ability and biocompatibility. The novel bioactive nCaF2 sealant is promising to provide long-term F ions for caries prevention.