Optical penetration models for practical prediction of femtosecond laser ablation of dental hard tissue

OBJECTIVES

To develop and practically test high-precision femtosecond laser ablation models for dental hard tissue that are useful for detailed planning of automated laser dental restorative treatment.

METHODS

Analytical models are proposed, derived, and demonstrated for practical calculation of ablation rates, ablation efficiency and ablated morphology of human dental enamel and dentin using femtosecond lasers. The models assume an effective optical attenuation coefficient for the irradiated material. To achieve ablation, it is necessary for the local energy density of the attenuated pulse in the hard tissue to surpass a predefined threshold that signifies the minimum energy density required for material ionization. A 1029 nm, 40 W carbide 275 fs laser was used to ablate sliced adult human teeth and generate the data necessary for testing the models. The volume of material removed, and the shape of the ablated channel were measured using optical profilometry.

RESULTS

The models fit with the measured ablation efficiency curve against laser fluence for both enamel and dentin, correctly capturing the fluence for optimum ablation and the volume of ablated material per pulse. The detailed shapes of a 400-micrometer wide channel and a single-pulse width channel are accurately predicted using the superposition of the analytical result for a single pulse.

CONCLUSIONS

The findings have value for planning automated dental restorative treatment using femtosecond lasers. The measurements and analysis give estimates of the optical properties of enamel and dentin irradiated with an infrared femtosecond laser at above-threshold fluence and the proposed models give insight into the physics of femtosecond laser processing of dental hard tissue.

Laser fluorescence assessment of dental caries arrest with two silver fluoride agents in patients with special needs- a preliminary report

PURPOSE

While silver diamine fluoride has been used extensively for caries arrest and desensitising, silver fluoride (AgF) at neutral pH may also have value as a minimally invasive dental caries treatment. This study explored the effectiveness of two AgF products (AgF/KI and AgF/SnF2) when used in adult patients with special needs (SN) who had high caries risk and salivary gland hypofunction.

METHODS

This split-mouth clinical study, over two appointments 3-months apart, compared the impact of a single application of AgF/KI (Riva Star Aqua, SDI) and AgF/SnF2 (Creighton Dental CSDS, Whiteley) on matched carious lesions in the same arch, by clinical visual-tactile (cVT) assessment of caries status and laser fluorescence (LF, DIAGNOdent) evaluation of bacterial load in the lesions, using repeated measures analysis.

RESULTS

Twelve participants were recruited in the study. A total of 56 teeth (28 pairs) were included. Both AgF products gave a significant decrease in caries activity as measured by cVT (P < 0.0001) and LF (P = 0.0027). There were no statistically significant differences between the two AgF treatments, with response rates for improvements in active lesions of 92% in the AgF/KI arm, and 96% in the AgF/SnF2 arm. There was no effect of tooth type, lesion type, arch type, plaque metabolism and plaque area at the site level on outcomes, nor was there a clustering effect of sites in a patient level analysis. Overall, LF was superior to cVT for detecting lesions that still progressed despite treatment (P = 0.0027).

CONCLUSION

A single application of AgF/KI or AgF/SnF2 has high predictability (over 90%) for achieving arrest in active caries lesions in adult patients with SN and high caries risk. Clinical assessment should use visual-tactile examination combined with LF readings to detect lesions that are still progressing and that require additional treatments. Future studies should compare these AgF modalities with SDF and explore factors such as time between applications and the need for repeated applications.

TRIAL REGISTRATION

The study was registered with the Australian Clinical Trials Registry (ACTRN12621001139864p) on 23/08/2021.

Awareness of dental complications with oral piercings

OBJECTIVES

To investigate knowledge and awareness of dental complications with oral piercings among adults with oral piercings, a control population with no piercings and body-piercing professionals in South-East Queensland, Australia.

METHODS

Participants recruited from public and private dental clinics and body-piercing professionals from piercing centres in the same region completed questionnaires to assess knowledge and attitudes.

RESULTS

Respondents comprised 54 pierced individuals, 54 controls and 35 body-piercing professionals. Only 13% of the pierced group were informed about oral piercing-related complications, and 14% of body-piercing professionals did not warn their clients about long-term complications. The latter included chipped teeth (26%) and gingival recession (15%). About 76% play with their piercing, developing teeth grinding (15%), jaw clenching (15%) and sleep disturbances (4%). Interestingly, 41% of those with oral piercings advised others against getting piercings.

CONCLUSIONS

There is a lack of awareness about dental-related complications among pierced individuals and body-piercing professionals. A significant proportion of pierced individuals advise others against getting piercings. Body piercers do not consistently advise clients about risks associated with oral piercings. Thus, it is recommended that programmes be developed to improve awareness of oral and dental complications associated with oral piercings.

Measuring ergonomic interventions and prevention programs for reducing musculoskeletal injury risk in the dental workforce: A systematic review

PURPOSE

Pain from musculoskeletal disorders (MSD) is experienced by all types of dental clinicians, leading to forced reduction of work capacity and premature retirement. Prolonged static posture is a major contributor to MSD in dentistry. Currently, there is no uniform ergonomic training in dentistry to prevent MSD. This systematic review explored and summarized methods and technologies for baseline and ongoing measurements of ergonomic intervention and prevention programs for reducing postural risk and for prevention of MSDs.

METHODS

The review was conducted in accordance with PRISMA guidelines. The literature search included PUBMED, Embase, CINAHL and the Cochrane Library, and identified relevant observational, experimental, quasi-experimental, research, and intervention studies. Quality was rated using a validated standardized instrument.

RESULTS

A total of 20 studies were included, of which 4 were rated as being of the high quality. Methods ranged from observers to motion sensors. Ten studies focused used established measuring tools (PAI, RULA, REBA), while nine studies focused on effectiveness of alternative methods of measurement. One study identified ISO standard 11226 for baseline comparisons. Evolving technologies were found to be suitable for baseline measurements of posture, and for feedback for developing sustainable postural behaviors. No studies measured ongoing postural performance improvement.

CONCLUSIONS

This systematic review adds to current evidence for the expanded and improved use of early training and testing of postural competence to reduce MSD risk among dental professionals. Further studies using technologies to assess the impacts of ergonomic training and testing among dental professionals are warranted.

Clinical Assessment of Plaque Removal Using a Novel Dentifrice Containing Cellulose Microfibrils

Dentifrice performance in the removal of dental plaque is influenced by the interactions of dentifrice components with tooth surfaces. This randomized controlled clinical study assessed the effectiveness and safety of a novel fluoride dentifrice formulation that included a micro-fibrillated cellulose network with entangled microcrystalline cellulose and silica particles (ProtegeraTM), and compared this to a positive control fluoride dentifrice (Crest Cavity Protection™). Whole mouth dental plaque levels in 82 healthy adults were measured after the first supervised use, and following a week of twice daily use at home. Overall, the test dentifrice was at least three times and up to four times more effective in whole-mouth plaque reductions, with a 38.6% reduction on first use, a 30.9% reduction at day 7, and a 41.6% reduction from day 1 to day 7, compared to reductions of 12.0%, 9.6% and 11.6%, respectively for the positive control, and up to seven times more effective in lingual plaque reductions, than the reference dentifrice (p < 0.001), with a 27.7% reduction on first use, a 22.3% reduction at day 7, and a 31.0% reduction from day 1 to day 7, compared to reductions of 4.4%, 2.2%, and 4.5%, respectively, for the positive control. No safety issues arose from the use of the test dentifrice. These results indicate that including micro-fibrillated cellulose enhances plaque removal effectiveness, without causing adverse changes to oral soft tissues.

Oral complications associated with metal ion release from oral piercings: a systematic review

PURPOSE

This systematic review explored dental complications associated with metal ion release from oral piercings using the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.

METHODS

Item retrieval from October 2022 to December 2022 from databases, such as Cochrane Central Register of Controlled Trials, Medline, PubMed, Embase, Scopus and Web of Science, using predefined search terms was undertaken by two independent reviewers. Data were extracted and risk of bias was assessed using the Joanna Briggs Institute (JBI) critical appraisal checklist. From 1509 identified studies, 25 were included for analysis.

RESULTS

Of the 25 studies, 20 included both clinical examination and questionnaire-based data. The remaining five studies were deemed low quality based on the Joanna Briggs Institute criteria. The average time piercings were worn ranged between 5 and 48 months. Most studies did not investigate complications from metal ion release. Only two studies examined the direct effects of metal ion release and showed that metal ions may cause hypersensitivity reactions and mucosal changes. Other soft tissue complications were reported, with gingival recession noted in 16 out of 25 studies, especially due to lip piercings. Studies reporting other complications were as follows: swelling (9), pain (8), infection (6), bleeding (6), inflammation (5), alterations to speech, eating and/or swallowing (5), changes to taste or metallic taste (5), and mucosal changes (4). Ten studies reported tooth chipping from tongue piercings.

CONCLUSION

Oral piercings leach metal ions into surrounding tissues which may cause local mucosal changes. Furthermore, oral piercings cause damage to both soft and hard oral tissues, particularly gingival recession for lip piercings and tooth chipping for tongue piercings. Thus, to prevent such adverse injuries, dental professionals should discourage patients against oral piercings.

The Prevalence of Middle Mesial Canals in the Second Mandibular Molars of an Iranian Subpopulation: A Cross-Sectional CBCT Study

Background Missed additional canals are a common reason for the failure of root canal treatments. The prevalence of additional canals in molar teeth can vary because of ethnic differences. Hence, this study aimed to determine the prevalence and distribution of middle mesial canals (MMCs) in the second mandibular molars using cone beam computed tomography (CBCT), for an adult population from Kerman in southeast Iran. Methodology De-identified retrospective provided CBCT scans from three private radiology centers in Kerman were reviewed (131 patients; 58 males (44.3%), 73 females (55.7%); age range: 13 to 54 years, mean age: 33). The presence of MMCs in mandibular second molars (222 teeth; 112 left and 110 right) was recorded, along with the morphology of the distal roots in the same teeth. Frequency data were analyzed using the Chi-square test and Fisher's exact test. Results The overall prevalence of MMC in the second mandibular molars was 2.3%. MMCs were found both unilaterally and bilaterally. More MMCs were found in females than males (2.7% vs. 1.7%), and on the left side (2.7% vs. 1.8%), but these differences were not statistically significant (p=1.0). There was no association between the existence of MMC in the mesial root and a second canal in the distal root of the same tooth. Conclusion Based on CBCT scans, the overall prevalence of MMC in mandibular second molars in this population was just below one in 44. Clinicians performing endodontic treatment on second molars should check for the presence of MMC so that this possible additional canal is not missed.

Investigation of laser wavelength effect on the ablation of enamel and dentin using femtosecond laser pulses

We investigated the effect of femtosecond (fs) laser ablation of enamel and dentin for different pulse wavelengths: infrared (1030 nm), green (515 nm), and ultra-violet (343 nm) and for different pulse separations to determine the optimal irradiation conditions for the precise removal of dental hard tissues with the absence of structural and compositional damage. The ablation rates and efficiencies were established for all three laser wavelengths for both enamel and dentin at room temperature without using any irrigation or cooling system, and the surfaces were assessed with optical and scanning electron microscopy, optical profilometry, and Raman spectroscopy. We demonstrated that 515 nm fs irradiation provides the highest rate and efficiency for ablation, followed by infrared. Finally, we explored the temperature variations inside the dental pulp during the laser procedures for all three wavelengths and showed that the maximum increase at the optimum conditions for both infrared and green irradiations was 5.5 °C, within the acceptable limit of temperature increase during conventional dental treatments. Ultra-violet irradiation significantly increased the internal temperature of the teeth, well above the acceptable limit, and caused severe damage to tooth structures. Thus, ultra-violet is not a compatible laser wavelength for femtosecond teeth ablation.

Effectiveness of Mouthwashes in Managing Oral Diseases and Conditions: Do They Have a Role?

Antimicrobial mouthwashes are considered to reduce dental plaque biofilm and thus the potential to prevent plaque-induced oral diseases, particularly periodontal diseases. The effectiveness of mouthwashes relates to this antiplaque role, as well as, their tooth-whitening potential and ability to mask/mange malodour (halitosis). There is also a growing interest in the use of mouthwashes as an adjunctive measure in post surgical and post-dental care, while the COVID-19 pandemic has given a new lease of life to mouthwashes as an oral antispetic that may be useful in reducing the oral viral load. The mode of action of mouthwashes varies, depending on their active ingredients, concentrations, and mode and frequency of use, as does their potential effectiveness. This article aims to provide a narrative overview of the evidence of the effectiveness of the most widely used mouthwashes in managing oral diseases, oral conditions, and adjunctive care roles.

The application of lasers in vital pulp therapy: a review of histological effects

Vital pulp therapy (VPT) is primarily intended to preserve the vitality of pulp tissues, which have been exposed for any reason. Various materials and techniques have been proposed to improve treatment outcomes, including the use of lasers. This study aimed to review the histological results of different dental lasers including low-level lasers, carbon dioxide (CO2), erbium-doped yttrium aluminum garnet laser (Er:YAG), neodymium-doped yttrium aluminum garnet (Nd:YAG), erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers, and diode lasers for VPT. This focused review included a comprehensive electronic search of Scopus, MEDLINE, Web of Science, and Google Scholar databases from 2000 to 2022 by two independent investigators. Different combinations of keywords were used, and reference mining of related papers was done. The review included studies related to histologic evaluation of laser-assisted vital pulp therapy that stated the laser parameters that were used. Articles with radiographic or clinical assessments or articles lacking necessary data were excluded. Non-English articles were excluded unless their abstract was in English and encompassed the necessary data. Most studies indicated the efficacy of lasers for reduction of inflammation, acceleration of healing, and increasing the thickness of dentinal bridge. According to the evidence, lasers used in combination with pulp capping agents are beneficial to enhance the success rate of VPT.

Positive impacts of oral health services provision by a student-led primary care clinic to an Australian rural indigenous community

BACKGROUND

This study aimed to determine whether oral health services provision by a dental student clinical outplacement embedded within a Community Controlled Health Service positively impacted a rural Indigenous community and to explore the nature of these benefits.

METHODS

Aggregated and de-identified 2017, 2018 and 2019 student-led clinic services provision data were retrospectively analysed. The change in services mix over time was measured. Rural outplacement clinic operational costs to the university were estimated. Government-funded local public dental clinic waiting list and services provision data were used to identify any student clinic establishment effect.

RESULTS

The student-led clinic services mix shifted over time from mainly acute care for toothache towards prevention of disease and tooth restoration, indicating an improvement in patient oral health and correspondingly reduced system costs. Imputed value of 2017-2019 student-led clinic services provision totalled almost AUD$1 million. Government public clinic waiting list times decreased after full establishment of the student-led clinic, indicating decreased pressure on the public system.

CONCLUSION

The Community Controlled Health Service and university partnership improved community oral health care access, its timely delivery and simultaneously provided valuable human capital development from the student training experience. The student-led clinic's targeted Indigenous community showed oral health improvement over time. © 2023 Australian Dental Association.

Antimicrobial stewardship: Prescribing across the primary care health professions

We examined the patterns of antibiotic prescribing by medical and non-medical prescribers (dentists, nurse practitioners, and midwives) in Australia. We explored trends in the dispensed use of antibiotics (scripts and defined daily dose [DDD] per 1000 population/day) by Australian prescribers over the 12-year period, 2005-2016. We obtained data on dispensed prescriptions of antibiotics from registered health professionals subsidized on the Pharmaceutical Benefits Scheme (PBS). There were 216.2 million medical and 7.1 million non-medical dispensed prescriptions for antibiotics over 12 years. The top four antibiotics for medical prescribers were doxycycline; amoxicillin, amoxicillin plus clavulanic acid, and cefalexin, constituting 80% of top 10 use in 2005 and 2016; the top three for non-medical were amoxicillin, amoxicillin plus clavulanic acid and metronidazole (84% of top 10 use in 2016). The proportional increase in antibiotic use was higher for non-medical than medical prescribers. While medical prescribers preferentially prescribed broad-spectrum and non-medical prescribers moderate-spectrum antibiotics, there was a large increase in the use of broad-spectrum antibiotics over time by all prescribers. One in four medical prescriptions were repeats. Overprescribing of broad-spectrum antibiotics conflicts with national antimicrobial stewardship initiatives and guidelines. The proportional higher increase in antibiotic use by non-medical prescribers is a concern. To reduce inappropriate use of antibiotics and antimicrobial resistance, educational strategies targeted at all medical and non-medical prescribers are needed to align prescribing with current best practice within the scope of practice of respective prescribers.

Mesoporous Core-Cone Silica Nanoparticles Can Deliver miRNA-26a to Macrophages to Exert Immunomodulatory Effects on Osteogenesis In Vitro

Nanoparticles can play valuable roles in delivering nucleic acids, including microRNAs (miRNA), which are small, non-coding RNA segments. In this way, nanoparticles may exert post-transcriptional regulatory influences on various inflammatory conditions and bone disorders. This study used biocompatible, core-cone-structured, mesoporous silica nanoparticles (MSN-CC) to deliver miRNA-26a to macrophages in order to influence osteogenesis in vitro. The loaded nanoparticles (MSN-CC-miRNA-26) showed low-level toxicity towards macrophages (RAW 264.7 cells) and were internalized efficiently, causing the reduced expression of pro-inflammatory cytokines, as seen via real-time PCR and cytokine immunoassays. The conditioned macrophages created a favorable osteoimmune environment for MC3T3-E1 preosteoblasts, driving osteogenic differentiation with enhanced osteogenic marker expression, alkaline phosphatase (ALP) production, extracellular matrix formation, and calcium deposition. An indirect co-culture system revealed that direct osteogenic induction and immunomodulation by MSN-CC-miRNA-26a synergistically increased bone production due to the crosstalk between MSN-CC-miRNA-26a-conditioned macrophages and MSN-CC-miRNA-26a-treated preosteoblasts. These findings demonstrate the value of nanoparticle delivery of miR-NA-26a using MSN-CC for suppressing the production of pro-inflammatory cytokines with macrophages and for driving osteogenic differentiation in preosteoblasts via osteoimmune modulation.

Ion release from oral piercings from in vitro acidic challenges

OBJECTIVES

This laboratory-based study measured ion release from metallic piercings when exposed to organic acids (lactic, citric) and inorganic acids (phosphoric, hydrochloric) that could be encountered in the oral cavity.

METHODS

Barbell and ring oral piercings composed of stainless steel, titanium or gold-plated titanium were submerged in 2 mL volumes of 0.1% lactic acid, 10% citric acid, 0.2% phosphoric acid, and 0.1% hydrochloric acid for 7 and 34 days. Ion release into the liquid was measured using inductively coupled plasma optical emission spectroscopy (ICPOES) and expressed in relationship to surface area. Surface changes from baseline were assessed using light and backscatter scanning electron microscopy (SEM).

RESULTS

ICPOES results showed that hydrochloric and phosphoric acid caused the greatest release of material per surface area. Released elements included (ranked highest to lowest): Fe, P, Ti, Na, Cr, S, Ni, Ca, Mg, K, Si, Al, V, Mn, Ba, and Co. SEM imaging identified qualitative surface changes consistent with corrosion, for most piercing types examined.

CONCLUSIONS

Under the exposure conditions used, inorganic acids cause greater metal dissolution than organic acids. Inorganic acids could therefore pose a risk of corrosion and leaching of ions from metallic oral piercings.

Amelioration Strategies for Silver Diamine Fluoride: Moving from Black to White

Topical cariostatic agents have become a reasonable alternative for managing dental caries in young children. Silver diamine fluoride (SDF) is a practical topical approach to arrest caries and avoid extensive and risky dental treatment. However, the literature demonstrates a parental hesitation towards accepting SDF because of black unaesthetic tooth discolouration following application. The rapid oxidation of ionic silver darkens demineralised tooth structure permanently. In this regard, nano-metallic antimicrobials could augment or substitute for silver, and thereby enhance SDF aesthetic performance. Recently, biomedical research has drawn attention to selenium nanoparticles (SeNPs) due to their antimicrobial, antioxidant, and antiviral potencies. Various in vitro studies have examined the effect of SeNPs on the virulence of bacteria. This narrative review explores practical issues when using SDF and suggests future directions to develop it, focusing on antimicrobial metals. Several methods are described that could be followed to reduce the discolouration concern, including the use of nanoparticles of silver, of silver fluoride, or of selenium or other metals with antimicrobial actions. There could also be value in using remineralising agents other than fluoride, such as NPs of hydroxyapatite. There could be variations made to formulations in order to lower the levels of silver and fluoride in the SDF or even to replace one or both of the silver and fluoride components completely. Moreover, since oxidation processes appear central to the chemistry of the staining, adding SeNPs which have antioxidant actions could have an anti-staining benefit; SeNPs could be used for their antimicrobial actions as well. Future research should address the topic of selenium chemistry to optimise how SeNPs would be used with or in place of ionic silver. Incorporating other antimicrobial metals as nanoparticles should also be explored, taking into account the optimal physicochemical parameters for each of these.

Influence of eight debridement techniques on three different titanium surfaces: A laboratory study

OBJECTIVES

Debridement methods may damage implant surfaces. This in vitro study investigated eight debridement protocols across three implant surfaces to assess both biofilm removal and surface alterations.

MATERIAL AND METHODS

One hundred sixty commercially pure titanium discs were treated to simulate commercially available titanium implant surfaces-smooth, abraded and abraded and etched. Following inoculation with whole human saliva to create a mixed species biofilm, the surfaces were treated with eight debridement methods currently used for clinical peri-implantitis (n = 10). This included air abrasion using powders of glycine, sodium bicarbonate and calcium carbonate; conventional mechanical methods-piezoelectric scaler, carbon and stainless steel scalers; and a chemical protocol using 40% citric acid. Following treatment, remaining biofilm was analysed using scanning electron microscopy and crystal violet assays. For statistical analysis, ANOVA was applied (p < 0.05).

RESULTS

All debridement techniques resulted in greater than 80% reduction in biofilm compared with baseline, irrespective of the surface type. Glycine powder delivered through an air polishing system eliminated the most biofilm. Mechanical instruments were the least effective at eliminating biofilm across all surfaces and caused the greatest surface alterations. Citric acid was comparable with mechanical debridement instruments in terms of biofilm removal efficacy. Titanium surfaces were least affected by air abrasion protocols and most affected by mechanical methods.

CONCLUSIONS

Mechanical protocols for non-surgical debridement should be approached with caution. Glycine powder in an air polisher and 40% citric acid application both gave minimal alterations across all implant surfaces, with glycine the superior method in terms of biofilm removal.

Antibody response to BNT162b2 mRNA vaccine in gingival crevicular fluid

BACKGROUND

This prospective cohort study aimed to evaluate the antibody responses in non-invasive gingival crevicular fluid (GCF) and unstimulated whole saliva to the SARS-CoV-2 Spike unit 1 receptor-binding domain (S1-RBD) protein following administration of the mRNA BNT162b2 vaccine.

METHODS

This longitudinal study recruited 37 participants with no prior COVID-19 exposure (eight people recruited prior to the COVID-19 pandemic - labeled pre-COVID, 16 vaccinated and 13 non-vaccinated participants). An enzyme-linked immunosorbent assay (ELISA) was used to determine antibody levels against S1-RBD in saliva (n=90) and GCF (n=80) samples obtained at 1 and 3 weeks after dose 1, and 3 days, 7 days, and 3 weeks after dose 2. To determine previous SARS-CoV-2 infection status, anti-nucleocapsid (N) Ig levels were determined in samples from the pre-COVID (saliva as reference), non-vaccinated (saliva and GCF), and vaccinated (saliva and GCF) participants at 1-week post-dose 1 using ELISA.

RESULTS

Salivary levels of anti-N antibodies measured in samples from vaccinated and nonvaccinated participants were comparable to those in pre-COVID saliva samples collected between October 2018 and September 2019, thus confirming that all study participants had no prior SARS-CoV-2 infection. Overall, the levels of anti-S1-RBD antibodies peaked at 3 weeks after dose 2 in both saliva and GCF for all three immunoglobulin isotypes. Notably, the concentration of anti-S1-RBD antibodies in GCF was significantly higher than in saliva at all time points.

CONCLUSION

This study establishes GCF and saliva as viable alternative non-invasive sources to monitor levels of antibodies following vaccination, with GCF demonstrating feasibility as a biofluid source for the detection of antibodies against SARS-CoV-2 S1-RBD antigen.

Positive oral health outcomes: A partnership model improves care in a rural Indigenous community

OBJECTIVE

The purpose of this study was to explore the benefits of a partnership between a university dental school and a Community Controlled Health Service, specifically in relation to improving the oral health of an underserved rural Indigenous community. We sought community opinions on health and social outcomes arising from the service provided by the dental student clinical outplacement.

SETTING

In Dalby, Queensland.

PARTICIPANTS

In total, 38 participants in five focus groups were representative of local Indigenous community Elders, community health support group members and management and staff.

DESIGN

A descriptive qualitative study employing semi-structured audio-recorded focus group discussions conducted with purposefully selected Indigenous community groups to explore participant views and experience of the partnership model. Qualitative data were analysed using thematic content analysis.

RESULTS

The Indigenous community representatives expressed positive benefit in both their general and oral health awareness, in improved access to dental care provided in their own safe space, while they were pleased to assist with students' learning. They viewed the partnership as mutually beneficial. Suggestions for enhancement of the oral health service were also offered.

CONCLUSION

This partnership between a university and a Community Controlled Health Service provides sustainable positive social and health benefits for the targeted Indigenous community and for the wider local population, while simultaneously providing enhanced educational benefits for students on clinical outplacement. Translation and uptake of this successful model of care would benefit both underserved communities and dental and other health care professional educators worldwide.

Mechanical and Metallurgical Characterization of Nickel-Titanium Wire Types for Rotary Endodontic Instrument Manufacture

This study aimed to evaluate and compare the effects of ambient temperature and post-manufacture heat-treatment on the mechanical behavior of nickel-titanium (NiTi) wires. Four types of commercial NiTi variants (Stock NiTi, heat treated "Blue", "Gold", "Superflex", all Dentsply Maillefer, Ballaigues, Switzerland) were stressed in a tensile testing machine in a temperature-controlled water bath at three different temperatures. Stress and strain values were extrapolated from the raw data, and 2-way ANOVA and Tukey's test for multiple comparisons were performed to compare the differences of the mechanical constants. Differential scanning calorimetry (DSC) tests established the martensitic transformation starting (M_s), finishing (M_f) and austenitic (reverse-martensitic) starting (A_s) and finishing (A_f) points. Austenitic modulus of elasticity and transformation stress values increased with temperature for all NiTi groups. The martensitic modulus of elasticity, maximum transformation strain and ultimate tensile stress were not significantly affected by temperature changes. Stock NiTi and Gold wire samples presented with clearly delineated austenitic and martensitic transformations in the DSC experiments. Differences in manufacturing/heat treatment conditions and ambient temperature affect the mechanical behavior of nickel-titanium and may have clinical implications. Further improvements to the experimental setup could be considered to provide more accurate measurements of strain.

A Comparative Study of Mesoporous Silica and Mesoporous Bioactive Glass Nanoparticles as Non-Viral MicroRNA Vectors for Osteogenesis

Micro-ribonucleic acid (miRNA)-based therapies show advantages for bone regeneration but need efficient intracellular delivery methods. Inorganic nanoparticles such as mesoporous bioactive glass nanoparticles (MBGN) and mesoporous silica nanoparticles (MSN) have received growing interest in the intracellular delivery of nucleic acids. This study explores the capacity of MBGN and MSN for delivering miRNA to bone marrow mesenchymal stem cells (BMSC) for bone regenerative purposes, with a focus on comparing the two in terms of cell viability, transfection efficiency, and osteogenic actions. Spherical MBGN and MSN with a particle size of ~200 nm and small-sized mesopores were prepared using the sol-gel method, and then the surface was modified with polyethyleneimine for miRNA loading and delivery. The results showed miRNA can be loaded into both nanoparticles within 2 h and was released sustainedly for up to 3 days. Confocal laser scanning microscopy and flow cytometry analysis indicated a high transfection efficiency (>64%) of both nanoparticles without statistical difference. Compared with MSN, MBGN showed stronger activation of alkaline phosphatase and activation of osteocalcin genes. This translated to a greater osteogenic effect of MBGN on BMSC, with Alizarin red staining showing greater mineralization compared with the MSN group. These findings show the potential for MBGN to be used in bone tissue engineering.

Femtosecond laser dentistry for precise and efficient cavity preparation in teeth

High fluence focused femtosecond laser pulses were used to perform fast, high precision and minimally damaging cavity cutting of teeth at room temperature without using any irrigation or cooling system. The optimal ablation rates were established for both enamel and dentin, and the surfaces were assessed with optical and scanning electron microscopy, Raman spectroscopy and optical profilometry. No chemical change in the composition of enamel and dentin was observed. We explored temperature variations inside the dental pulp during the laser procedure and showed the maximum increase was 5.5°C, within the acceptable limit of temperature increase during conventional dental treatments.

Anesthetic-, irrigation- and pain-free dentistry? The case for a femtosecond laser enabled intraoral robotic device

By leveraging ultrashort pulse laser and micro-electromechanical systems (MEMS) technologies, we are developing a miniaturized intraoral dental robotic device that clamps onto teeth, is remotely controlled, and equipped with a focusing and scanning system to perform efficient, fast, and ultra-precise laser treatments of teeth and dental restorative materials. The device will be supported by a real-time monitoring system for visualization and diagnostic analysis with appropriate digital controls. It will liberate dentists from repetitive manual operations, physical strain and proximity to the patient's oro-pharyngal area that potentially contains infectious agents. The technology will provide patients with high-accuracy, minimally invasive and pain-free treatment. Unlike conventional lasers, femtosecond lasers can ablate all materials without generating heat, thus negating the need for water irrigation, allowing for a clear field of view, and lowering cross-infection hazards. Additionally, dentists can check, analyze, and perform precise cutting of tooth structure with automatic correction, reducing human error. Performing early-stage diagnosis and intervention remotely will be possible through units installed at schools, rural health centers and aged care facilities. Not only can the combination of femtosecond lasers, robotics and MEMS provide practical solutions to dentistry's enduring issues by allowing more precise, efficient, and predictable treatment, but it will also lead to improving the overall access to oral healthcare for communities at large.

Root canal cleaning in roots with complex canals using agitated irrigation fluids

The internal topography of the root canal is complex, especially for the mesial root of the permanent first molar. In response to such challenges, enhanced irrigation protocols have been developed, using laser pulses to agitate fluids and enhance the removal of microbial deposits. The aim of this laboratory study was to assess the effectiveness of laser agitation of sodium hypochlorite in removing multispecies biofilms grown in the mesial root of the permanent first molars. The five agitation groups (N = 12 roots for each) were: 940 nm diode laser (superpulsed mode, 50 μs/pulses at 20 Hz using 20 mJ/pulse); 1064 nm Nd: YAG laser (200 μs/pulse at 20 Hz using 20 mJ/pulse); 2940 nm Er: YAG laser (50 μs/pulse at 15 Hz using a 400/14 conical tip in the SWEEPS protocol, with 20 mJ/pulse); passive ultrasonic agitation at 28 kHz (positive control); and irrigation with a 27-gauge side vented needle for 2 min per canal (negative control). Biofilm removal was assessed by confocal microscopic imaging of root slices at 1, 4 and 7 mm from the root apex. None of the tested methods were effective in completely eradicating biofilm from the most confined regions of the root canal system. The greatest challenge was cleaning the isthmus regions. There was a positive correlation between canal cleaning and isthmus cleaning, suggesting that increased effectiveness in cleaning root canal walls is associated with more effective isthmus cleaning. Wider and narrow isthmuses were cleaned better than long and narrow isthmuses.

Nanotechnology for the management of COVID-19 during the pandemic and in the post-pandemic era

Following the global COVID-19 pandemic, nanotechnology has been at the forefront of research efforts and enables the fast development of diagnostic tools, vaccines and antiviral treatment for this novel virus (SARS-CoV-2). In this review, we first summarize nanotechnology with regard to the detection of SARS-CoV-2, including nanoparticle-based techniques such as rapid antigen testing, and nanopore-based sequencing and sensing techniques. Then we investigate nanotechnology as it applies to the development of COVID-19 vaccines and anti-SARS-CoV-2 nanomaterials. We also highlight nanotechnology for the post-pandemic era, by providing tools for the battle with SARS-CoV-2 variants and for enhancing the global distribution of vaccines. Nanotechnology not only contributes to the management of the ongoing COVID-19 pandemic but also provides platforms for the prevention, rapid diagnosis, vaccines and antiviral drugs of possible future virus outbreaks.

Decontamination practices of paediatric crowns: a systematic review

Purpose

A systematic review was conducted into paediatric crown decontamination practices using the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.

Method

After database retrieval using predefined search terms, two reviewers independently applied the selection criteria, extracted the data, and assessed for risk of bias. From 92 potentially eligible studies, 10 were included for analysis.

Results

Steam sterilisation (autoclaving) was used as the gold standard for reducing biological contaminants on paediatric crowns across in vivo studies. However, autoclaving was associated with microstructural changes such as crazing and contour alterations. Furthermore, several tooth coloured crowns were liable to undergo colour changes from steam sterilisation.

Conclusion

Ambiguous manufacturer guidelines on protocols for reprocessing and reuse after biological exposure raises concerns regarding cross contamination and leaves practitioners open to potential litigation. A better understanding of the compatibility of paediatric crowns and decontamination practices is needed. More research into alternative chairside technologies that use low temperature, such as hydrogen peroxide gas plasma sterilisation, is warranted.

Simulated and clinical aerosol spread in common periodontal aerosol-generating procedures

Objectives

This study evaluated particle spread associated with various common periodontal aerosol-generating procedures (AGPs) in simulated and clinical settings.

Materials and methods

A simulation study visualized the aerosols, droplets, and splatter spread with and without high-volume suction (HVS, 325 L/min) during common dental AGPs, namely ultrasonic scaling, air flow prophylaxis, and implant drilling after fluorescein dye was added to the water irrigant as a tracer. Each procedure was repeated 10 times. A complementary clinical study measured the spread of contaminated particles within the dental operatory and quantified airborne protein dispersion following 10 min of ultrasonic supragingival scaling of 19 participants during routine periodontal treatment.

Results

The simulation study data showed that air flow produced the highest amount of splatters and the ultrasonic scaler generated the most aerosol and droplet particles at 1.2 m away from the source. The use of HVS effectively reduced 37.5–96% of splatter generation for all three dental AGPs, as well as 82–93% of aerosol and droplet particles at 1.2 m for the ultrasonic scaler and air polisher. In the clinical study, higher protein levels above background levels following ultrasonic supragingival scaling were detected in fewer than 20% of patients, indicating minimal particle spread.

Conclusions

While three common periodontal AGPs produce aerosols and droplet particles up to at least 1.2 m from the source, the use of HVS is of significant benefit. Routine ultrasonic supragingival scaling produced few detectable traces of salivary protein at various sites throughout the 10-min dental operatory.

Clinical relevance

The likelihood of aerosol spread to distant sites during common periodontal AGPs is greatly reduced by high-volume suction. Clinically, limited evidence of protein contaminants was found following routine ultrasonic scaling, suggesting that the the majority of the contamination consisits of the irrigant rather than organic matter from the oral cavity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-022-04532-8.

Effects of decontamination protocols on the aesthetic, morphological, and material composition of preformed paediatric crowns

BACKGROUND

Preformed crowns (PCs) are exposed to potentially infectious bodily fluids during the trial fit; however, whether they can be safely re-used remains uncertain. This study determined the effects of decontamination methods on various PCs. The key criteria examined were aesthetic, morphological, and elemental characteristics.

DESIGN

This is a laboratory-based experimental study. Stainless steel, pre-veneered stainless steel, and zirconia PCs underwent either: (a) ultrasonic cleaning with EmPower^® followed by steam sterilisation, (b) thermal disinfection in an instrument washer with Asepti^® Neutraliser/Asepti^® followed by steam sterilisation, or (c) immersion in an ortho-phthalaldehyde (OPA) instrument-level disinfectant. The methods were performed for 1, 5, or 10 cycles, and scanning electron microscopy (SEM); red, green, and blue (RGB) value; and luminosity value were tracked (using a histogram of individual colour reference chips in Adobe Photoshop^® ) to assess colour changes, and energy-dispersive X-ray (EDX) spectroscopy to characterise the material composition.

RESULTS

Pre-veneered stainless steel crowns showed isolated zones of darkening with loss of luminosity and variations in green and blue values after ultrasonic or thermal washer disinfection combined with steam autoclaving at 5 and 10 cycles. No changes occurred with OPA. Both SEM imaging and EDX analysis identified no changes to crown materials from any of the three reprocessing methods.

CONCLUSIONS

Reprocessing protocols need to reflect the differing responses of various types of PCs. Repeated steam sterilisation causes slight aesthetic alterations by way of colour instability and loss of luminosity to pre-veneered stainless steel crowns, but no issues with stainless steel or zirconia PCs.

Laser-fluorescence assessment of sodium hypochlorite quenching reversal agents on human dentine

BACKGROUND

Laser-fluorescence diagnostic technology for real-time clinical assessment of residual bacteria could help assist in determining the endpoints for root canal debridement. Sodium hypochlorite (NaOCl) can however quench fluorescence and lead to false low reading. This study aims to evaluate various antioxidant for their ability to recover quenched fluorescence in dentine treated with NaOCl.

METHODS

Human dentine fluorescence was measured using 655 nm laser at baseline and again after a 2 min application of 4% NaOCl. The putative recovery agents were then applied, and the fluorescence measured after 5, 10, 20, 30 and 60 min. Recovery from quenching was also assessed using laser confocal scanning microscopy (CLSM) with a bound tetracycline fluorophore using 488 nm excitation.

RESULTS

A 5 min application of vitamin E oil or buffered 2% lignocaine solution (1:80,000 adrenaline) was effective in regaining quenched fluorescence within the following 5 mins. Distilled water, sodium thiosulfate, unbuffered 2% lignocaine with 1:80000 adrenaline and phosphate buffered saline were less effective, and of equal performance. Ascorbic acid and butylated hydroxyanisole were not effective and had deleterious effects on the levels of dentine fluorescence. CLSM provided confirmation of recovery from quenched fluorescence using vitamin E oil.

CONCLUSION

Based on these findings, reversal agents should be employed when assessing the fluorescence of dentine that has been exposed to NaOCl or other quenching agents.

Pulmonary arterial hypertension in hereditary hemorrhagic telangiectasia associated with ACVRL1 mutation: a case report

INTRODUCTION

Hereditary hemorrhagic telangiectasia is an autosomal dominant condition with an estimated prevalence of 1 in 5000. It is characterized by the presence of abnormalities of vascular structures, and may affect many organ systems, including the lungs, brain, spinal cord, gastrointestinal tract, and liver. A causative mutation is identified in approximately 97% of patients with definite hereditary hemorrhagic telangiectasia in one of three genes including a mutation in endoglin, a mutation in a locus mapped to chromosome 5, and an activin receptor-like kinase-1 (ACVRL1) mutation that is associated with an increased incidence of primary pulmonary hypertension. Pulmonary arterial hypertension is a rare (15-25 cases per million people) but severe vascular disorder. Heritable pulmonary arterial hypertension is associated with several gene mutations, with 75% having a mutation in the bone morphogenetic protein receptor 2 (BMPR2). However, the remaining 25% of patients have other associated genetic mutations including ACVLR1, which is also associated with hereditary hemorrhagic telangiectasia. Pulmonary arterial hypertension is a rare complication in patients with hereditary hemorrhagic telangiectasia (< 1% of the hereditary hemorrhagic telangiectasia population). We describe a case report with this rare occurrence.

CASE PRESENTATION

A 70-year-old white/caucasian Irish male presented for screening for hereditary hemorrhagic telangiectasia due to a history of recurrent epistaxis (once/week) and a family history suggestive of pulmonary hypertension. Genetic testing confirmed an ACVRL1 mutation, while an echocardiogram and right heart catheterization confirmed pulmonary arterial hypertension. On examination, he had several mucocutaneous telangiectasia across his face. He was commenced on tadalafil and macitentan. However, this led to increased iron deficiency anemia and pedal edema. Selexipag was also added to his drug regime. He continues to require intermittent admissions for diuresis and blood transfusions.

CONCLUSION

The association of hereditary hemorrhagic telangiectasia and pulmonary arterial hypertension is rare (< 1%). Here we describe a case of hereditary hemorrhagic telangiectasia complicated with pulmonary arterial hypertension as a result of an ACVRL1 mutation. We also describe the clinical challenges of treating these two conditions together, as treatment options for pulmonary arterial hypertension tend to worsen hereditary hemorrhagic telangiectasia symptoms.

A critical analysis of research methods and experimental models to study tooth discolouration from endodontic materials

As a range of materials used in endodontics may cause tooth discolouration, exploration of factors responsible for the darkening of the tooth crown or root is warranted. This narrative review paper discusses the range of technical factors that apply in laboratory studies that assess endodontic discolouration. As an example of how these factors operate, particular examples relating to discolouration caused by endodontic medicaments containing tetracycline antibiotics are used. Following the PRILE 2021 guidelines approach, a summary of key variables to be addressed in the methodology for laboratory studies is presented, to inform future work.

Australian dentists' knowledge, preparedness, and experiences during the COVID-19 pandemic

BACKGROUND

COVID-19 is a global health crisis. Close contact with the mucous membranes and respiratory secretions of patients and aerosol-generating procedures renders dentists and other oral health professionals at high risk of exposure to SARS-CoV-2. We examined dentists' knowledge, preparedness, and experiences of managing COVID-19 in Australia.

METHODS

A cross-sectional online survey of dentists with a current membership with The Australian Dental Association (ADA) was conducted between March and April 2021.

RESULTS

Of the 368 survey responses, most dentists (72.3%) reported having a good level of knowledge about COVID-19, with most visiting the ADA Federal COVID-19 (74.7%) and state/territory department of health websites (62.8%), respectively to source up-to-date information. Most dentists (87.6%) felt prepared to manage COVID-19 into the future, although 66% reported not receiving training or certification in the use of PPE. Over half (58.7%) reported not being concerned about contracting SARS-CoV-2 at work, with some (28.9%, n = 98/339) feeling more stressed than usual and having heavier workloads.

CONCLUSION

COVID-19 had significant impact in oral healthcare in Australia. Dentistry has adapted to the varied challenges raised by the pandemic. Comprehensive training and detailed guidelines were fundamental for successful patient management during the COVID-19 outbreak.

Evaluation of the effect of various endodontic irrigants and medicaments on dentine fluorescence

This study examined the effect of various root canal irrigants and medicaments on dentin fluorescence elicited by 655 nm visible red laser light. To replicate clinical use, irrigants were applied onto dentin samples for 2 min, while medicaments were applied for 2 weeks. Fluorescence values tracked from baseline across the following to 24 h, starting 5 min after exposure. Sodium hypochlorite, hydrogen peroxide, and articaine local anaesthetic (4% articaine with 1:1000,000 adrenaline) all significantly quenched fluorescence (p < 0.0001), which then returned to baseline levels after 20 min. Conversely, elevated fluorescence readings were recorded after 3% mepivacaine (p < 0.05), 0.2% chlorhexidine (p < 0.01) and chloroform (p <0.05). A 2 week application of Ledermix™ paste containing 3% demeclocycline caused an irreversible increase in fluorescence (p < 0.0001). Other tested endodontic materials (15% EDTA, eucalyptus oil, calcium hydroxide, Odontopaste™ clindamycin paste, and distilled water) had no impact on dentine fluorescence. The influences of endodontic materials on dentin fluorescence need to considered when using fluorescence endpoints to guide the progress of root canal treatment.

Modulating Osteoimmune Responses by Mesoporous Silica Nanoparticles

The immune response plays an important role in biomaterial-mediated osteogenesis. Nanomaterials may influence immune responses and thereby alter bone regeneration. Mesoporous silica nanoparticles (MSNs) have received much attention for drug delivery and bone regeneration. Recently, immunomodulatory effects of MSNs on osteogenesis have been reported. In this Review, we summarize the osteoimmunomodulation of MSNs, including the effects of MSN characteristics on immune cells and osteogenesis. Impacts of MSNs on immune cells vary according to nanoparticle properties, including surface topography and charge, particle size, and ion release. MSNs with suitable doses can inhibit inflammation and create an immune microenvironment beneficial for bone regeneration by activating immune cells and stimulating cytokine release. Further work is needed to explore and clarify the underlying mechanisms, including crosstalk between various types of immune cells and how to design MSNs to create a suitable immune environment for osteogenesis.

A Retrospective Analysis of Non-Sharps-Related Injuries in a Dental School

OBJECTIVES

Workplace non-sharps injuries are a common occurrence in a dental school setting. In dentistry, the importance of preventing non-sharps injuries is often overlooked due to emphasis on sharps-related injuries. The aim of this research was to analyse the incidences of non-sharps injuries over an 11-year period in a dental school to identify trends and the possible causative factors for these injuries.

METHODS

Injury reports lodged with the University of Queensland Workplace Health and Safety databases between 2009 and 2019 were categorised and analysed.

RESULTS

Of 1156 incidents reported, 35.7% (n = 413) were non-sharps injuries, and the most common type of non-sharps injury was general incidents (48.4%, n = 200). The most common body site for injury was the hands (19.4%, n = 80), and the most common location where an injury occurred was in clinical patient care (53.8%, n = 222). The personnel type most at risk of a non-sharps injury fluctuated between students and staff throughout the study period.

CONCLUSIONS

All personnel, including students and staff, are at similar risk of experiencing a non-sharps injury within a dental school setting. The equipment and facilities of a dental clinic as well as the level of adherence to safe working procedures are contributing factors. Continuous quality improvement is essential for minimising these injuries.

Microbial Decontamination and Antibacterial Activity of Nanostructured Titanium Dental Implants: A Narrative Review

Peri-implantitis is the major cause of the failure of dental implants. Since dental implants have become one of the main therapies for teeth loss, the number of patients with peri-implant diseases has been rising. Like the periodontal diseases that affect the supporting tissues of the teeth, peri-implant diseases are also associated with the formation of dental plaque biofilm, and resulting inflammation and destruction of the gingival tissues and bone. Treatments for peri-implantitis are focused on reducing the bacterial load in the pocket around the implant, and in decontaminating surfaces once bacteria have been detached. Recently, nanoengineered titanium dental implants have been introduced to improve osteointegration and provide an osteoconductive surface; however, the increased surface roughness raises issues of biofilm formation and more challenging decontamination of the implant surface. This paper reviews treatment modalities that are carried out to eliminate bacterial biofilms and slow their regrowth in terms of their advantages and disadvantages when used on titanium dental implant surfaces with nanoscale features. Such decontamination methods include physical debridement, chemo-mechanical treatments, laser ablation and photodynamic therapy, and electrochemical processes. There is a consensus that the efficient removal of the biofilm supplemented by chemical debridement and full access to the pocket is essential for treating peri-implantitis in clinical settings. Moreover, there is the potential to create ideal nano-modified titanium implants which exert antimicrobial actions and inhibit biofilm formation. Methods to achieve this include structural and surface changes via chemical and physical processes that alter the surface morphology and confer antibacterial properties. These have shown promise in preclinical investigations.

Efficient transfection and long-term stability of rno-miRNA-26a-5p for osteogenic differentiation by large pore sized mesoporous silica nanoparticles

MicroRNA (miRNA) based therapy for bone repair has shown promising results for regulating stem cell proliferation and differentiation, an efficient and stable vector for delivery of microRNA delivery is needed. The present study explored the stability and functionality of lyophilized mesoporous silica nanoparticles with core-cone structure and coated with polyethylenimine (MSN-CC-PEI) as a system for delivering Rattus norvegicus (rno)-miRNA-26a-5p into rat marrow mesenchymal cells (rBMSCs) to promote their osteogenic differentiation. We assessed the cellular uptake and transfection efficiency of nanoparticles loaded with labelled miRNA using confocal laser scanning microscopy and flow cytometry, and the cell viability using the MTT assay. The expression levels of osteogenic genes after one and two weeks were analysed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Extracellular matrix deposition and mineralization at 3 weeks were evaluated using Picro Sirius red and Alizarin red staining. We also assessed the performance of the delivery system after long term storage, by freeze drying rno-miRNA-26a-5p@MSN-CC-PEI with 5% trehalose and keeping them at -30 °C for 3 and 6 months. Osteogenic differentiation, matrix deposition, and mineralization were all significantly increased by rno-miRNA-26a-5p. In addition, this enhancement was not significantly altered by lyophilization and storage. Overall, these findings support the concept of MSN-CC-PEI as a delivery system for gene therapy. The complex of rno-miRNA-26a-5p@MSN-CC-PEI could efficiently transfect rBMSCs and enhance their osteogenic differentiation. In addition, the lyophilized complexes remain functional after 6 months of storage.

Finite element analysis of rotary nickel-titanium endodontic instruments: A critical review of the methodology

Finite element analysis has been a valuable research tool for rotary nickel-titanium endodontic files over the last two decades. This review aims to summarise and critique the methodology as used in currently available endodontic literature for finite element analysis of rotary nickel-titanium instruments. An electronic literature research in PubMed and Scopus databases was performed using the appropriate search terms, and the titles and abstracts were screened for relevance. The review revealed an inconsistent approach to the finite element method, particularly with regards to the boundary conditions in which the instruments are tested. Moreover, there is a lack of experimental data to validate in silico findings. A standardised protocol to finite element analysis of rotary endodontic instruments could be considered for future studies.

The Emerging Regulatory Role of Circular RNAs in Periodontal Tissues and Cells

Periodontitis is a chronic complex inflammatory disease associated with a destructive host immune response to microbial dysbiosis, leading to irreversible loss of tooth-supporting tissues. Regeneration of functional periodontal soft (periodontal ligament and gingiva) and hard tissue components (cementum and alveolar bone) to replace lost tissues is the ultimate goal of periodontal treatment, but clinically predictable treatments are lacking. Similarly, the identification of biomarkers that can be used to accurately diagnose periodontitis activity is lacking. A relatively novel category of molecules found in oral tissue, circular RNAs (circRNAs) are single-stranded endogenous, long, non-coding RNA molecules, with covalently circular-closed structures without a 5' cap and a 3' tail via non-classic backsplicing. Emerging research indicates that circRNAs are tissue and disease-specific expressed and have crucial regulatory functions in various diseases. CircRNAs can function as microRNA or RNA binding sites or can regulate mRNA. In this review, we explore the biogenesis and function of circRNAs in the context of the emerging role of circRNAs in periodontitis pathogenesis and the differentiation of periodontal cells. CircMAP3K11, circCDK8, circCDR1as, circ_0062491, and circ_0095812 are associated with pathological periodontitis tissues. Furthermore, circRNAs are expressed in periodontal cells in a cell-specific manner. They can function as microRNA sponges and can form circRNA-miRNA-mRNA networks during osteogenic differentiation for periodontal-tissue (or dental pulp)-derived progenitor cells.

Trends in Australian dental prescribing of antibiotics: 2005-2016

BACKGROUND

Prescribing of antibiotics by dentists for surgical prophylaxis or as an adjunct to managing dental infections is a substantial part of the overall landscape for prescribed antibiotics in health care settings.

METHODS

We explored trends in the antibiotic prescribing patterns of Australian dentists over the 12-year period, 2005-2016. We obtained data on dispensed prescriptions of antibiotics from registered dentists subsidized on the Pharmaceutical Benefits Scheme.

RESULTS

Australian dentists were responsible for almost 7 million dispensed prescriptions of antibiotics over 12 years; an average of 24 prescriptions per year per dentist. The most commonly prescribed antibiotic was amoxicillin, followed by amoxicillin + clavulanic acid and metronidazole. These top three antibiotics constituted more than 80% of all antibiotics prescribed and their use increased dramatically over time. There was a large increase in the prescribing of broad-spectrum antibiotics over time, most of which occurred from 2011 to 2016.

CONCLUSIONS

Excessive prescribing of broad-spectrum antibiotics runs contrary to national antimicrobial stewardship (AMS) initiatives and guidelines. Multifaceted educational strategies are essential to align prescribing with current best practice. High-level evidence to inform clear guidelines on antibiotic prescribing in dental infections, with audit and feedback, should reduce the inappropriate use of antibiotics in dentistry.

Biomedical application of mesoporous silica nanoparticles as delivery systems: a biological safety perspective

The application of mesoporous silica nanoparticles (MSNs) as drug delivery systems to deliver drugs, proteins, and genes has expanded considerably in recent years, using in vitro and animal studies. For future translation to clinical applications, the biological safety aspects of MSNs must be considered carefully. This paper reviews the biosafety of MSNs, examining key issues such as biocompatibility, effects on immune cells and erythrocytes, biodistribution, biodegradation and clearance, and how these vary depending on the effects of the physical and chemical properties of MSNs such as particle size, porosity, morphology, surface charge, and chemical modifications. The future use of MSNs as a delivery system must extend beyond what has been learnt thus far using rodent animal models to encompass larger animals.

Impact of photobiomodulation using four diode laser wavelengths of on cationic liposome gene transfection into pre-osteoblast cells

Gene therapy can be an effective treatment modality for some severe genetic diseases. Despite efforts to improve their performance, non-viral gene delivery methods remain inefficient and costly. As an alternative to viral vectors, cationic liposomes have a good safety profile and low immunogenicity, but relatively low transfection efficiency. They may also be toxic to cells at high concentrations. Given these challenges, the present study explored the impact of photobiomodulation (PBM) on cationic liposome plasmid DNA transfection in terms of its efficiency and toxicity, using Lipofectamine 2000 to carry green fluorescent protein (GFP) encoding plasmid DNA, with the pre-osteoblast MC3T3-E1 cell line as the target. Cultures were irradiated using diode lasers (445, 685, 810, or 970 nm) at 200 mW using pulsed mode (50 Hz), with a power density of 104.64 mW/cm², and irradiance from 6 to 18 joules. To determine transfection efficiency, expression of GFP was assessed using confocal laser scanning microscopy and flow cytometry. Cell viability was evaluated using the MTT assay. PBM using 810 nm and 970 nm lasers significantly enhanced transfection efficiency for GFP, indicating more efficient uptake of plasmid DNA. Conversely, laser irradiation at 445 nm and 685 nm wavelengths reduced the GFP transfection efficiency. Treatment using 685, 810, and 970 nm lasers at 12 J maintained cell viability and prevented toxicity of cationic liposomes. Overall, these findings support the concept that PBM using near infrared laser wavelengths can enhance transfection efficiency and support cell viability when cationic liposomes are used as the vector in gene therapy.

Laser-assisted nucleic acid delivery: A systematic review

Gene therapy has become an effective treatment modality for some conditions. Laser light may augment or enhance gene therapy through photomechanical, photothermal, and photochemical. This review examined the evidence base for laser therapy to enhance nucleic acid transfection in mammalian cells. An electronic search of MEDLINE, Scopus, EMBASE, Web of Science, and Google Scholar was performed, covering all available years. The preferred reporting items for systematic reviews and meta-analyses guideline for systematic reviews was used for designing the study and analyzing the results. In total, 49 studies of laser irradiation for nucleic acid delivery were included. Key approaches were optoporation, photomechanical gene transfection, and photochemical internalization. Optoporation is better suited to cells in culture, photomechanical and photochemical approaches appear well suited to in vivo use. Additional studies explored the impact of photothermal for enhancing gene transfection. Each approach has merits and limitations. Augmenting nucleic acid delivery using laser irradiation is a promising method for improving gene therapy. Laser protocols can be non-invasive because of the penetration of desirable wavelengths of light, but it depends on various parameters such as power density, treatment duration, irradiation mode, etc. The current protocols show low efficiency, and there is a need for further work to optimize irradiation parameters.

The Queensland Birth Cohort Study for Early Childhood Caries: Results at 7 Years

AIMS

This study investigated caries predictors in 378 children remaining from a birth cohort of 1,052 at 7 y and compared the efficacy of home visits (HVs) and telephone contacts (TCs) for early childhood caries (ECC) prevention.

METHODS

The HVs or TCs were made at ages 6, 12, 18, 30, and 42 mo with annual dental clinic examinations at ages 2 to 7 y. At every visit, the parents completed validated questionnaires regarding the children's family, medical, dental, and dietary histories.

RESULTS

The caries prevalence increased from 2% and 6% at ages 2 and 3 y to 15%, 33%, 42%, and 52% at ages 4 to 7 y. The mean caries experience (decayed, missing, and teeth extracted due to caries) of the total cohort increased from 0.1 ± 0.5 at age 2 y to 0.2 ± 1.1 at 3 y, 0.5 ± 1.6 at 4 y, 1.1 ± 2.4 at 5 y, 1.6 ± 2.6 at 6 y, and 2.0 ± 2.7 at 7 y. The prevalence of mutans streptococci (MS) in the total cohort at years 2 to 7 was 22%, 36%, 42%, 42%, 39%, and 44%, respectively. MS was strongly correlated with caries prevalence for all years (all P < 0.001). Statistical modeling employing the generalized estimating equations identified caries predictors as holding a Health Care Card (low socioeconomic status) (P = 0.009; odds ratio [OR] = 2.05; confidence interval [CI]: 1.20-3.52), developmental defects of enamel (DDEs) (P < 0.001; OR = 1.09; CI: 1.05-1.14), and MS counts ≤10⁵/mL (P = 0.001; OR = 1.63; CI: 1.24-2.14). By contrast, HVs were more protective than TCs for caries (P = 0.008; OR = 0.42; CI: 0.22-0.80).

CONCLUSIONS

This study provides prospective, clinical evidence that MS, DDEs, and low socioeconomic status are strongly correlated with early childhood caries and that HVs are more efficacious than TCs in ECC prevention.

KNOWLEDGE TRANSFER STATEMENT

This 7-y birth cohort study provides longitudinal clinical evidence that mutans streptococci, developmental defects of enamel, and low socioeconomic status are key risk indicators of early childhood caries.

Acid Resistance of Glass Ionomer Cement Restorative Materials

In view of the need for aesthetics, restorations of teeth will typically be completed using tooth colored restorative materials. With the advent of biomimetic restorative materials, such as glass ionomer cements (GIC), much greater emphasis is now being placed on how well such materials can resist the challenge of acids that are present in foods and drinks, or gastric contents that are regurgitated. This laboratory study compared the dissolution and behavior of five GIC materials (GC Fuji® VII, GC Fuji® Bulk, GC Fuji® IX Fast, Fuji® IX Extra and GC Equia® Forte Fil) when exposed to three acids (citric acid, phosphoric acid and lactic acid), versus ultrapure deionized water, which was used as a control. Discs of each material GIC were submerged in solutions and percentage weight changes over time determined. Subsequently, the GIC materials were also placed as a part of standardized Class II sandwich restorations in bovine teeth (n = 20), and submerged in the solutions, and the extent of GIC dissolution and protection of the adjacent tooth was scored. Weight loss increased with time and with acid concentration. Overall, the most soluble material was GC Fuji® IX Extra, while GC Fuji® IX Fast and GC Fuji® Bulk were less soluble, and the least soluble material was GC Equia® Forte Fil. The most destructive solution for both the discs and for GIC restorations in teeth was 10% citric acid, while the least destructive acid was 0.1% lactic acid. The more recent GIC materials GC Fuji® Bulk and GC Equia® Forte Fil showed increased acid resistance over the older GIC materials, and this further justifies their use in open sandwich Class II restorations in more hostile environments.

Multiple assessment methodologies in determining the antibiofilm actions of sodium hypochlorite mixed with clodronate or etidronate in endodontic irrigation

This study aimed to use multiple methodologies, including a novel usage of scanning electron microscopy (SEM), to evaluate the antimicrobial actions of sodium hypochlorite (NaOCl) admixed with clodronate or etidronate in root canal irrigation. The study also examined the usefulness of colony counting as a biofilm assessment methodology. Seven day Enterococcus faecalis biofilms were grown on hydroxyapatite discs. The discs were disinfected with 0.26 M clodronate-5% NaOCl, 0.26 M etidronate-5% NaOCl, 5% NaOCl, or treated with phosphate buffered saline (PBS). Assessments were performed using colony counting, SEM and the XTT reduction assay. The XTT assessment used the same groups but with 2.5% NaOCl. For colony counting, bacteria were removed from the discs by vortex mixing, followed by plating. The discs were subsequently fixed for SEM imagining and evaluators scored the SEM micrographs for remaining bacteria. Antibiofilm actions were assessed with the Kruskal-Wallis and Dunn's multiple comparison tests. SEM micrographs and the XTT assay revealed no differences between the NaOCl controls and the clodronate or etidronate mixtures with NaOCl (P > 0.05). It was concluded that the chelator mixtures with NaOCl had antibiofilm actions comparable to NaOCl. Furthermore, vortex mixing incompletely removed biofilm from HA discs in the PBS controls and hence colony counting using E. faecalis biofilms on hydroxyapatite discs could not be used for intergroup comparisons involving PBS. Additionally, colony counting could not be used for comparisons between the NaOCl treatment groups because the removal of bacteria from the substrate by vortex mixing was affected by the irrigant type.

Prevalence and Distribution of the Middle Mesial Canal in Mandibular First Molar Teeth of the Kerman Population: A CBCT Study

PURPOSE

Missed additional canals are one of the most important reasons for RCT failures in molar teeth. This study aimed to determine the prevalence and distribution of middle mesial canals in mandibular first molars of the Kerman population.

MATERIALS AND METHODS

A retrospective study was performed on de-identified cone beam image sets from 3 private radiology centers in Kerman. A total of 100 mandibular first molars from 62 patients (mean age 32 years) were included. Information regarding the patient's age and gender, the location of teeth, and the presence or absence of a MMC and also a second distal canal in MMC cases was recorded in an Excel table. Data were analyzed using SPSS software (IBM-USA).

RESULTS

The overall prevalence of MMCs in the mandibular first molars was 8.1% (10.0% in females and 6.3% in males). More cases of MMCs were seen on the right side (12.2%) than the left side (3.4%). One case of bilateral MMCs combined with bilateral second distal canals in the mandibular first molars was seen in a 26-year-old female. A further case of bilateral MMCs was found in a 32-year-old male but with single-canal distal roots on both sides.

CONCLUSION

The overall prevalence of MMCs in the Kerman population (8.1%) is at the lower end of the reported range of the international literature (0.26% to 53.8%). In the cohort examined in this study, mid mesial canals were more prevalent in females and on the right side. There was no definite relationship between MMCs and second distal canals in the mandibular first molar teeth in the same subject. MMCs may be unilateral or bilateral. Careful exploration of the pulpal floor between canal orifices is essential to prevent missing the MMC, as this would cause undesirable clinical outcomes.

Resistance to compressive force in continuous chelation

Continuous chelation involves the simultaneous use of sodium hypochlorite and a chelating agent. Given the combination of a proteolytic agent and a demineralising chelator, this study aimed to investigate whether mixtures containing the weak chelators etidronate or clodronate and sodium hypochlorite could adversely affect the mechanical strength of teeth compared to the sequence sodium hypochlorite/EDTA/sodium hypochlorite. Matching pairs of bovine teeth were tested on a universal testing machine, and the compressive load at fracture was recorded. One root from each pair was prepared with the sequence, and the matching tooth was prepared with either water, the clodronate mixture or the etidronate mixture. No differences in load at fracture were seen between either mixture and the sequence. However, loads were higher in the teeth irrigated with water compared to the sequence. The results indicated that the continuous chelation mixtures did not alter tooth mechanical properties compared to the standard sequence.