Recapitulating Antioxidant and Antibacterial Compounds into a Package for Tissue Regeneration: Dual Function Materials with Synergistic Effect.

Oxidative damage and infection can prevent or delay tissue repair. Moreover, infection reinforces reactive oxygen species (ROS) formation, which makes the wound's condition even worse. Therefore, the need for antioxidant and antibacterial agents is felt for tissue regeneration. There are emerging up-and-coming biomaterials that recapitulate both properties into a package, offering an effective solution to turn the wound back into a healing state. In this article, the principles of antioxidant and antibacterial activity are summarized. The review starts with biological aspects, getting the readers to familiarize themselves with tissue barriers against infection. This is followed by the chemistry and mechanism of action of antioxidant and antibacterial materials (dual function). Eventually, the outlook and challenges are underlined to provide where the dual-function biomaterials are and where they are going in the future. It is expected that the present article inspires the designing of dual-function biomaterials to more advanced levels by providing the fundamentals and comparative points of view and paving the clinical way for these materials.

Caries-preventive effectiveness of two different fluoride varnishes: A randomised clinical trial in patients with multi-bracketed fixed orthodontic appliances.

BACKGROUND: Patients with multi-bracketed fixed orthodontic appliances are at a higher risk of developing enamel demineralisation. AIM: To compare the efficacy of the quarterly application of two varnishes in preventing white spot lesions (WSLs) during multi-bracketed fixed orthodontic treatment. DESIGN: Ninety-nine patients were randomly allocated into three intervention groups: Group A-standard oral hygiene instructions (OHI); Group B-5% sodium fluoride (NaF) varnish with standard OHI; and Group C-NaF plus tricalcium phosphate varnish with standard OHI. The outcome was assessed at 6-monthly intervals using a quantitative laser fluorescence device, clinical evaluation and photographic evaluation on six maxillary anterior teeth. A logistic regression model using generalised estimating equations with the intervention group, time and their interaction was used to compare the occurrence of WSLs, whereas the independent-samples Kruskal-Wallis test was used to compare the means of fluorescent values among different groups at p = .05. RESULTS: Generalised estimating equations (with intervention and time as predictors) showed that only the effect of time was found to be significant (p < .001), whereas there was no significant difference among the three intervention groups (p = .305) using clinical assessment or photographic assessment (p = .599). At the 18-month follow-up, sodium fluoride (NaF) varnish with standard OHI was shown to reduce the odds of WSLs by 55% (p = .200), and NaF plus tricalcium phosphate varnish with standard OHI by 42% (p = .327). CONCLUSION: The study failed to demonstrate that the quarterly application of both the study varnishes with OHI provided additional benefits compared with standard OHI alone in preventing WSLs, taking the effect of time of follow-up into consideration. There were higher odds of developing WSLs with an increased duration of orthodontic treatment.

Prevention of demineralization during multi-bracketed fixed orthodontic treatment: An overview of systematic reviews.

BACKGROUND: Demineralization during multi-bracketed fixed orthodontic treatment is a well-known problem. AIM: To systematically evaluate the evidence for the prevention of enamel demineralization during multi-bracketed fixed orthodontic treatment. DESIGN: Systematic reviews (with or without meta-analysis) that have appraised the primary studies on the prevention of demineralization during multi-bracketed fixed orthodontic treatment were searched systematically and included as per pre-defined eligibility criteria. The risk of bias of the included reviews was assessed by two authors using the ROBIS tool and AMSTAR-2 tool. RESULTS: Twenty-nine reviews conducted on 128 exclusive primary studies were included for the present overview; 23 of these reviews were assessed to be of a high risk of overall bias, 5 were of low risk, and 1 review was of unclear risk of bias. CONCLUSIONS: Predominantly, the published reviews have focused on fluorides, whereas some reviews have also studied the role of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), reminder therapy, lasers, and sealants. Professional fluorides, sealants, reminder therapy, and lasers might be valuable interventions to prevent demineralization during orthodontic treatment based on the conclusions of reviews with high quality; however, further studies are required to elucidate the role of CPP-ACP, chlorhexidine varnish, and powered toothbrushes.

RISK PREDICTORS OF EARLY CHILDHOOD CARIES INCREMENT-A SYSTEMATIC REVIEW AND META-ANALYSIS.

This systematic review aimed to investigate the risk predictors of caries in primary teeth and evaluate their association with the increment of Early Childhood Caries (ECC) among preschool children. This systematic review included only cohort or case-control studies of at least 2 years duration, over 300 participants and with English full-text. Potentially eligible studies were retrieved from 4 electronic databases (Ovid Embase, Ovid MEDLINE; PubMed, Web of Science) from inception to March 1, 2021. Independent screening and data extraction by 2 reviewers to identify factors associated with ECC increment, including family and socioeconomic factors, dietary and oral health-related habits, and clinical parameters. A total of 18 studies from 163 potential reports were included, involving 1,159,226 preschool children. Lower parental education attainment was found associated with ECC increment (WMD:0.87; 95% CI 0.52, 1.21); whereas immigration status (WMD:-0.38; 95% CI -1.09, 0.34), gender (WMD:-0.02; 95% CI -0.28, 0.24), and dental service utilization (WMD:0.35; 95% CI -0.10, 0.79) were not significant factors for ECC increment. All included studies consistently suggested positive correlations between ECC increment and baseline caries experience, plaque level, cariogenic microorganisms, and prenatal and passive smoking, while mixed findings were detected between ECC increment with dietary and oral hygiene practices. Preschool children whose parents have low education level are more likely to have greater increment of ECC over 2 years. Existing caries lesions, increased dental plaque level, cariogenic microorganisms, prenatal or passive smoking were also consistently identified as risk factors for ECC in all reviewed studies. This systematic review highlights specific risk factors to target for the prevention of ECC and supports implementing more oral health promotion for preschool children with parents of lower educational attainment.

Nonspherical Metal-Based Nanoarchitectures: Synthesis and Impact of Size, Shape, and Composition on Their Biological Activity.

Metal-based nanoentities, apart from being indispensable research tools, have found extensive use in the industrial and biomedical arena. Because their biological impacts are governed by factors such as size, shape, and composition, such issues must be taken into account when these materials are incorporated into multi-component ensembles for clinical applications. The size and shape (rods, wires, sheets, tubes, and cages) of metallic nanostructures influence cell viability by virtue of their varied geometry and physicochemical interactions with mammalian cell membranes. The anisotropic properties of nonspherical metal-based nanoarchitectures render them exciting candidates for biomedical applications. Here, the size-, shape-, and composition-dependent properties of nonspherical metal-based nanoarchitectures are reviewed in the context of their potential applications in cancer diagnostics and therapeutics, as well as, in regenerative medicine. Strategies for the synthesis of nonspherical metal-based nanoarchitectures and their cytotoxicity and immunological profiles are also comprehensively appraised.

Swept-source optical coherence tomographic observation on prevalence and variations of cemento-enamel junction morphology.

To investigate the prevalence of different patterns of cemento-enamel junction (CEJ) morphology under swept-source optical coherence tomography (SS-OCT). One hundred extracted human teeth were used consisting of incisors, premolars, and molars. Each sample was observed for every 500 µm circumferentially along CEJ and OCT images of the pattern were noted. Microscopic observations were done for the representative sample using confocal laser scanning microscope (CLSM) and transmission electron microscope (TEM). The OCT images exhibited four CEJ patterns: edge-to-edge (type I), exposed dentin (type II), cementum overlapping enamel (type III), and enamel overlapping cementum (type IV). The prevalence of CEJ patterns was further statistically considered for mesial, distal, buccal, and lingual surfaces. The real-time imaging by SS-OCT instantly determined CEJ morphology. CLSM and TEM observation revealed morphological features along CEJ, which corresponded to OCT images of CEJ anatomy. OCT results showed 56.8% of type I pattern predominantly found on proximal surfaces, followed by 36.5% of type II pattern on buccal and lingual surface, 6.4% of type III pattern, and 0.3% of type IV pattern. There was a significant difference in prevalence of CEJ patterns among different types of teeth, but there was no statistically significant difference among the four surfaces in each type of teeth. OCT is a non-invasive diagnostic tool to examine the CEJ patterns along the entire circumference. OCT observation revealed even minor dentin exposure that would need clinical and home procedures to prevent any symptoms.

Effectiveness of Pit and Fissure Sealants for Preventing and Arresting Occlusal Caries in Primary Molars: A Systematic Review and Meta-Analysis.

OBJECTIVE: The use of pit and fissure sealants have been well supported in permanent teeth, but no concrete evidence is available to support this procedure in primary molars. This review aims to systematically assess randomized controlled trials and summarize the evidence on the effectiveness of different sealants in prevention and arrest of the pit and fissure occlusal caries in primary molars of children. MATERIALS AND METHODS: Four electronic databases were searched from inception to March 2018. Seven studies were included in the qualitative and quantitative syntheses. Two reviewers independently selected studies, extracted data, assessed risk of bias using the revised Cochrane risk of bias tool, and evaluated the certainty in the evidence adopting the Grading of Recommendations Assessment Development and Evaluation approach. Odds ratio and retention rate of different sealants were recalculated and analyzed. RESULTS: This review identified no significant difference in the overall caries incidence and progression when evaluated over 24 months between (1) resin-based sealant (RBS) and glass ionomer sealants (GIS) or resin-modified GIS; (2) conventional and newly developed RBS; (3) autopolymerized and light-polymerized RBS; (4) RBS with topical fluoride application and topical fluoride alone; and (5) RBS with topical fluoride application and resin infiltration with topical fluoride application. The pooled estimates of the mean retention rates of RBS and GIS on primary molars over an 18-months period were 85.94% and 23.18%, respectively. The certainty in the evidence of each outcome was determined as low or very low mainly because of high risk of overall bias and imprecision. CONCLUSION: There are currently insufficient well-controlled randomized controlled clinical trials to determine whether sealants are beneficial in preventing or arresting noncavitated occlusal caries in the primary molars.

Effectiveness of self-applied topical fluorides against enamel white spot lesions from multi-bracketed fixed orthodontic treatment: a systematic review.

BACKGROUND: The regular use of fluoride dentifrices is quite practical, widespread and linked to global decline of dental caries. However, the role of self-applied topical fluorides in prevention and reversal of Enamel White Spot Lesions (EWSLs) during multi-bracketed fixed orthodontic treatment is not yet explored. OBJECTIVE: To systematically appraise the current literature on the effectiveness of self-applied topical fluorides in the prevention and reversal of EWSLs occurring during multi-bracketed fixed orthodontic treatment. SEARCH METHODS: Four electronic databases (Cochrane Library, Embase via Ovid, Medline via Ovid, and Scopus) and gray literature were searched using the broad MeSH terms and keywords. SELECTION CRITERIA: Only randomized/quasi-randomized controlled clinical trials evaluating the effectiveness of self-applied fluorides in the prevention of EWSLs during multi-bracketed fixed orthodontic treatment or reversal of post-orthodontic EWSLs were included. DATA COLLECTION AND ANALYSIS: Two reviewers independently screened for studies, extracted data and assessed the risk of bias using the Cochrane risk of bias tool 2.0. Due to substantial variations in the interventions, control groups, and the measurement of outcome among studies, quantitative synthesis could not be performed as planned. RESULTS: Only three studies could be included in the present review; two of them assessing prevention of EWSLs and one addressing reversal of post-orthodontic EWSLs. One of the studies was judged to be of low risk of overall bias, whereas 2 studies were adjudged to be of high risk of overall bias because of deviations from intended interventions. The certainty of evidence about the role of self-applied fluorides in prevention and reversal of EWSLs was found to be of low quality; hence, our confidence in the effect estimate is limited, and future well-conducted trials might alter the effect estimates. LIMITATIONS: The inclusion of only English literature and inability to perform quantitative synthesis due to a limited number of studies. CONCLUSIONS AND IMPLICATIONS: Although the review did not confirm the effectiveness of self-applied fluorides in the reversal of EWSLs, it did partially substantiate the positive role of self-applied fluorides in the prevention of EWSLs occurring during multi-bracketed fixed orthodontic treatment. The review recommends the need for well-designed randomized controlled trials evaluating the effectiveness of self-applied fluorides on the prevention and reversal of EWSLs during multi-bracketed fixed orthodontic treatment. REGISTRATION: PROSPERO database (Registration number: CRD42018108590) and is freely available at: http://www.crd.york.ac.uk/PROSPERO/display_record.php?ID=CRD42018108590. FUNDING: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Oral health of children with attention deficit hyperactivity disorder.

This study assessed and compared oral health and oral-health behaviours among children with and without attention deficit hyperactivity disorder (ADHD). The study included 31 children, 12-18 yr of age, with ADHD and 31 age- and gender-matched children without ADHD. Clinical data were recorded by a trained and calibrated examiner for caries, traumatic dental injuries, periodontal health, tooth wear, and salivary function. A questionnaire was also given to parents or caregivers about the oral health habits and behaviours of these children. Data were compared using Mann-Whitney U-tests and chi-square tests. No significant differences were found between children, with or without ADHD, in caries extent or prevalence, dental trauma prevalence, prevalence of periodontal disease or plaque, tooth wear, or unstimulated salivary flow. Children with ADHD had a significantly higher percentage of sites with gingival bleeding, as well as a higher frequency of parent-reported dislike of dentists, bruxism, history of assisted toothbrushing, and toothbrushing duration <1 min. They also had higher attendance at government dental clinics. The findings indicate that children with ADHD have poorer oral hygiene and more adverse oral-health attitudes and behaviours than do children without ADHD.

Effect of different fluoride varnishes on remineralization of artificial enamel carious lesions.

OBJECTIVES: To compare remineralization potential of topical fluoride varnishes with added calcium phosphate-based delivery systems on artificial enamel caries. METHODS: Human enamel specimens (n = 60) were randomly divided into six groups: Group 0: Control (no varnish), Group 1: Duraphat® , Group 2: MI Varnish™ , Group 3: Embrace™ Varnish, Group 4: Enamel Pro® Varnish, and Group 5: Clinpro™ White Varnish. Specimens were immersed in demineralizing solution for 96 h to create artificial caries lesion. Each specimen was then immersed in artificial saliva for 6 h after fluoride varnish application and pH cycling was performed for 8 days. Specimens were evaluated using Knoop surface microhardness (KHN) and transverse microradiography (TMR). One-way anova test was performed to examine the effect of fluoride varnishes on change in percentage of surface hardness recovery (%SHR), change in lesion depth (ΔLD), and change in mineral loss (ΔΔZ) with the significance limit set at 5%. RESULTS: %SHR of enamel following treatment with Group 1 was significantly higher than Group 3 and Group 4. Conversely, ΔLD and ΔΔZ of Group 1 were significantly higher than Group 2, Group 3, and Group 4. No significant differences in %SHR, ΔLD, and ΔΔZ were found between Group 1 and Group 5. CONCLUSIONS: Duraphat® alone achieves significant remineralization of enamel carious lesions. Clinpro™ White Varnish had similar enamel remineralization effect as Duraphat® .

A Review of Enamel Remineralisation Potential of Calcium- and Phosphate-based Remineralisation Systems.

PURPOSE: Along with calcium and phosphate ions, fluoride ions promote remineralisation of noncavitated carious lesions to form fluorapatite. However, the supply of calcium and phosphate ions from saliva may not be adequate for effective remineralisation in patients with high caries risk. Therefore, an additional supply of calcium and phosphate ions is mandatory to enhance effective remineralisation with fluoride ions. Several calcium- and phosphate-based remineralisation agents are available for clinical use. However, the nature of the incorporated calcium and phosphate ions and the method of their stabilisation are not similar. Therefore, this review summarises research findings on the enamel remineralisation potential of calcium- and phosphate-based remineralisation agents. MATERIALS AND METHODS: Appropriate key words were used and the Pubmed electronic database was searched to retrieve articles. Screening through titles and abstracts identified relevant articles. Full text review of the identified relevant articles was performed and the significant findings were summarised and presented in this review. RESULTS: Several studies including laboratory-based studies, in situ and randomised controlled clinical trials showed casein phosphopeptide amorphous calcium phosphate (CPP-ACP)-containing remineralisation agents to have superior remineralisation potential compared to other forms of calcium- and phosphate-based remineralisation agents, such as functionalised tri-calcium phosphate (fTCP) and amorphous calcium phosphate (ACP). CONCLUSIONS: More long-term clinical studies are necessary to compare the enamel remineralisation potential of calcium- and phosphate-based agents that contain fTCP and ACP with those containing CPP-ACP. Additional well-designed randomised controlled clinical trials are also necessary to justify long-term clinical supplemental use of products containing CPP-ACP.

Developing clinical practice guidelines for caries prevention and management for pre-school children through the ADAPTE process and Delphi consensus.

BACKGROUND: This study aims to develop consensus evidence-based clinical guidelines for caries prevention and management by caries risk assessment for pre-school children in Hong Kong. METHODS: Employing the ADAPTE process, guidelines for caries prevention and management by caries risk assessment for pre-school children with a preliminary list of 91 recommendations was complied. External review of the guidelines was conducted by a panel of 41 reviewers from the Hong Kong Society of Paediatric Dentistry using a two-round web-based Delphi process. The reviewers were invited to contribute any comments on the draft-adapted guidelines and rated their agreement with each recommendation using a 9-point Likert scale. During the second round, 36 participants received anonymous feedback from the first round and assessed a narrowed list of 28 recommendations. Recommendations were retained and classified according to the median score and rating percentages by the reviewers. RESULTS: A total of 70 out of 91 recommendations were retained (five reached high consensus, 65 reached consensus), and 21 recommendations were discarded. Recommendations and guidelines were outlined. CONCLUSIONS: Caries prevention and management guidelines for pre-school children were developed for use in Hong Kong using the ADAPTE process and Delphi consensus to develop evidence-based recommendations. This can facilitate the translation of guidelines into dental practice.

Evaluating the impact of caries prevention and management by caries risk assessment guidelines on clinical practice in a dental teaching hospital.

BACKGROUND: Clinical practice guidelines on 'Dental caries prevention and management by caries risk assessment for pre-school children in Hong Kong' were developed using ADAPTE process and Delphi consensus technique. This study aimed to evaluate the feasibility of disseminating and implementing the guidelines, and to evaluate their effectiveness in changing clinical practice. METHODS: The study was conducted in two phases, examining clinical records of pre-school aged patients being treated by non-academic clinical staff in the Paediatric Dentistry Clinic of a dental teaching hospital in Hong Kong. The clinical guidelines were introduced to the staff in a departmental seminar at the end of pre-intervention phase. Post-intervention phase began one month after the introduction of guidelines. Clinical records for three consecutive months were reviewed against standards and recommendations derived from the newly developed clinical guidelines in both phases. The results were assessed by Chi-square test, ANOVA and regression analyses. RESULTS: A total of 237 and 147 clinical records were reviewed in pre-intervention and post-intervention phases, respectively. Guideline adherence percentage increased significantly on almost all aspects of the guidelines in the post-intervention phase (P < 0.05). There were a significant difference in the mean overall guideline adherence score (pre-intervention phase: [Formula: see text] = 14.86 ± 6.11; post-intervention phase: [Formula: see text] = 28.88 ± 8.75) and sub-domain adherence scores between the two phases (P < 0.001). The training grade of the clinicians was the factor associated with changes in evidence-based practice (P < 0.001). CONCLUSIONS: The developed guidelines were effective in translating evidence into best practice. The findings have implication for widespread implementation.

A review of communication models and frameworks in a healthcare context.

This paper reviews six key communication models and frameworks in healthcare contexts. Comparison suggests key inter-relationships between the different stages of the clinical consultations. Implications are identified for future study in healthcare provider-patient communication. Clinical Relevance: To understand the healthcare provider-patient interaction through communication models.

A new method of evaluation of fracture patterns following microtensile bond strength testing using polarized light microscopy.

PURPOSE: This work describes a new method using polarized light microscopy to determine the failure modes of fractured beams following microtensile bond strength testing. The outcomes were validated using SEM and EDX elemental analysis. MATERIALS AND METHODS: Resin adhesives and resin composites bonded to caries-free dentin samples as well as disks of adhesive and composite were observed with reflected polarized light microscopy (PLM) to obtain standard images. A set of beams fractured in the microtensile bond test were observed with PLM and compared with the standard images to determine failure mode through PLM color matching with the standard dentin, adhesive, or composite images. Samples were analyzed by EDX under SEM and compared with the PLM outcomes. RESULTS: Reflected PLM images showed that the fractured surfaces covered with resin-based materials (adhesives or composite) appeared pink in color, in contrast to dentin surfaces, which appeared yellow. EDX mapping together with SEM observation confirmed the results obtained by PLM. CONCLUSION: The results of EDX mapping and SEM observation showed that the use of polarized light microscopy is a simple, viable method for differentiation between the resin-covered dentin surfaces for determining fracture pattern analysis after bond testing.

Efficacy of instruments measuring oral health literacy: a systematic review.

PURPOSE: To identify and review the psychometric properties of instruments available for measuring oral health literacy. MATERIALS AND METHODS: A comprehensive computerised search was carried out using six databases. The final papers were rated for level of evidence and scientific quality. RESULTS: A total of 621 potentially relevant articles were retrieved in the primary search. Twenty-nine studies using 13 oral health literacy instruments were included in the final analysis. After applying an international standards framework, all included studies were categorised as evidence level '2c'. Qualities of evidence were rated with STROBE guidelines. Psychometric analysis indicated various levels of validity and reliability across the instruments. CONCLUSIONS: As an emerging field, the number and reliability of oral health literacy instruments is rapidly growing, although many are in preliminary stages of testing. The majority of these focus on functional literacy and were developed in English for North American contexts. Further work is indicated to measure oral health literacy as a wider construct across diverse populations.

The Prevalence of Candida albicans and Malassezia globosa in Preschool Children with Severe Early Childhood Caries: A Case-Control Study.

Background: This cross-sectional study aimed to identify the prevalence of Candida albicans and Malassezia globosa in children with severe early childhood caries and caries-free children in Hong Kong. Methods: This study first recruited a total of 80 children aged between 48 and 72 months old, 40 children with severe early childhood caries, and 40 caries-free children. The children were then further divided into four groups, with 20 children in each group: Group 1: Severe early childhood caries-C. albicans, Group 2: Severe early childhood caries-M. globosa, Group 3: Caries-free-C. albicans and Group 4: Caries-free-M. globosa. Saliva, plaque, and caries lesion samples were collected from participants with severe early childhood caries, while only saliva and plaque samples were collected from caries-free participants. Caries status of the primary molars was assessed using WHO's decayed, missing, and filled tooth index, and the severity of cavitated lesions was determined based on International Caries Diagnosis and Assessment System criteria as caries code 5 or 6. The samples were analyzed using an Internal Transcribed Space and Quantitative Real-Time Polymerase Chain Reaction. Results:C. albicans was more prevalent in saliva and plaque samples of severe early childhood caries than in the caries-free group. Proportion of C. albicans in both saliva and plaque samples differed significantly between severe early childhood caries and caries-free groups (p < 0.05). Within the severe early childhood caries group, the proportion of children with C. albicans varied between 6 and 46%. No significant difference in M. globosa load was found between plaque samples of the severe early childhood caries and caries-free groups (p = 0.159). Conversely, no significant difference in M. globosa load was observed between saliva samples of severe early childhood caries and caries-free groups (p = 0.051). Conclusions: This study demonstrated a strong association between C. albicans and severe early childhood caries. M. globosa was detected in both the caries-free and severe early childhood caries groups, albeit at low levels.

Effectiveness of Nonpharmacological Behavioural Interventions in Managing Dental Fear and Anxiety among Children: A Systematic Review and Meta-Analysis.

BACKGROUND: Non-pharmacological behavioural interventions (NPBIs) have been employed by dentists to alleviate dental fear and anxiety (DFA) among preschool and school children. The aim of this systematic review and meta-analysis was to investigate the effectiveness of different NPBIs in reducing DFA among children aged below 12. METHOD: A comprehensive search was conducted using four electronic databases to identify randomised controlled trials that assess the effectiveness of NPBIs among preschool and school children. Two reviewers independently screened and selected the relevant studies, evaluated the risk of bias, and extracted relevant data for qualitative and quantitative syntheses. RESULT: A total of 66 articles were included in the study. Except during more invasive dental procedures, the use of distraction techniques was found to result in significantly lower self-rated anxiety, better cooperation, and lower pulse rate compared to the tell-show-do method. However, inconsistent results were reported regarding the efficacy of virtual reality, modelling, visual pedagogies, tell-show-do and other NPBIs in reducing DFA among children. CONCLUSIONS: The studies exhibited substantial heterogeneity due to varying age groups, methods of implementing NPBIs, dental treatments performed, and measurement scales employed in the evaluation of DFA.

Intrafibrillar silicification of collagen scaffolds for sustained release of stem cell homing chemokine in hard tissue regeneration.

Traditional bone regeneration strategies relied on supplementation of biomaterials constructs with stem or progenitor cells or growth factors. By contrast, cell homing strategies employ chemokines to mobilize stem or progenitor cells from host bone marrow and tissue niches to injured sites. Although silica-based biomaterials exhibit osteogenic and angiogenic potentials, they lack cell homing capability. Stromal cell-derived factor-1 (SDF-1) plays a pivotal role in mobilization and homing of stem cells to injured tissues. In this work, we demonstrated that 3-dimensional collagen scaffolds infiltrated with intrafibrillar silica are biodegradable and highly biocompatible. They exhibit improved compressive stress-strain responses and toughness over nonsilicified collagen scaffolds. They are osteoconductive and up-regulate expressions of osteogenesis- and angiogenesis-related genes more significantly than nonsilicified collagen scaffolds. In addition, these scaffolds reversibly bind SDF-1α for sustained release of this chemokine, which exhibits in vitro cell homing characteristics. When implanted subcutaneously in an in vivo mouse model, SDF-1α-loaded silicified collagen scaffolds stimulate the formation of ectopic bone and blood capillaries within the scaffold and abrogate the need for cell seeding or supplementation of osteogenic and angiogenic growth factors. Intrafibrillar-silicified collagen scaffolds with sustained SDF-1α release represent a less costly and complex alternative to contemporary cell seeding approaches and provide new therapeutic options for in situ hard tissue regeneration.