Melbourne Dental School - Research Publications
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ItemAntimicrobial nanoparticle coatings for medical implants: Design challenges and prospects(AMER INST PHYSICS, 2020-11)Microbial colonization, infection, and biofilm formation are major complications in the use of implants and are the predominant risk factors in implant failure. Although aseptic surgery and the administration of antimicrobial drugs may reduce the risk of infection, the systemic use of antibiotics can lead to a lack of efficacy, an increase in the risk of tissue toxicity, and the development of drug-resistant infections. To reduce implant-related infections, antimicrobial materials are increasingly being investigated and applied to implant surfaces using various methods depending on the agents and their microbicidal mechanisms. Through the development of biomaterials and nanotechnology, antimicrobial nanoparticles are becoming promising candidates for implant coatings, as their multifactorial antimicrobial mechanisms combat microbial adherence, viability, and biofilm formation. Despite their antimicrobial promise, the application of nanoparticles onto implant surfaces while retaining their antimicrobial potency faces many challenges. Herein, we review the potential and challenges associated with the design and implementation of antimicrobial nanoparticle coatings for the medical implant industry, particularly focusing on manufacturing considerations, sterilization, long-term stability, protein fouling, regulation, and safety, with a view to providing researchers the necessary tools to aid the translation of materials from the bench to the clinic.
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ItemMultifunctional Antimicrobial Polypeptide-Selenium Nanoparticles Combat Drug-Resistant Bacteria(AMER CHEMICAL SOC, 2020-12-16)Antibiotic-resistant bacteria are a severe threat to human health. The World Health Organization's Global Antimicrobial Surveillance System has revealed widespread occurrence of antibiotic resistance among half a million patients across 22 countries, with Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae being the most common resistant species. Antimicrobial nanoparticles are emerging as a promising alternative to antibiotics in the fight against antimicrobial resistance. In this work, selenium nanoparticles coated with the antimicrobial polypeptide, ε-poly-l-lysine, (Se NP-ε-PL) were synthesized and their antibacterial activity and cytotoxicity were investigated. Se NP-ε-PL exhibited significantly greater antibacterial activity against all eight bacterial species tested, including Gram-positive, Gram-negative, and drug-resistant strains, than their individual components, Se NP and ε-PL. The nanoparticles showed no toxicity toward human dermal fibroblasts at the minimum inhibitory concentrations, demonstrating a therapeutic window. Furthermore, unlike the conventional antibiotic kanamycin, Se NP-ε-PL did not readily induce resistance in E. coli or S. aureus. Specifically, S. aureus began to develop resistance to kanamycin from ∼44 generations, whereas it took ∼132 generations for resistance to develop to Se NP-ε-PL. Startlingly, E. coli was not able to develop resistance to the nanoparticles over ∼300 generations. These results indicate that the multifunctional approach of combining Se NP with ε-PL to form Se NP-ε-PL is a highly efficacious new strategy with wide-spectrum antibacterial activity, low cytotoxicity, and significant delays in development of resistance.
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ItemLaboratory Evaluation of Novel Implant Metal-Acrylic Prosthesis Design: Influence of Monolithic Acrylic Veneer(QUINTESSENCE PUBLISHING CO INC, 2020)PURPOSE: To test a novel implant metal-acrylic prosthesis design in comparison to a conventional prosthesis design through simulation of cyclic masticatory loading. The novel design involved digital designing and fabrication of the framework and the matched veneering acrylic resin material. MATERIALS AND METHODS: Ten prostheses were fabricated for each group. All the prostheses exhibited a similar external design on two implants with a distal cantilever. The conventional group comprised a milled metal framework with mechanically retained acrylic denture teeth via vertical pins. The digital prosthesis group incorporated an inverted T-shape bar and a monolithic milled acrylic resin veneer. The resin veneer was subsequently adhesively attached on the bar. All prostheses were thermally aged and subjected to laboratory cyclic loading at the cantilever region. The load-to-failure and the number of cycles until failure were collected. Furthermore, failed specimens were analyzed to determine the mode of failure. RESULTS: The digital prostheses failed at significantly greater load-to-failure (1,570.0 N ± 116.0 N) and number of cycles (124,857 ± 21,608) than the conventional prostheses (load-to-failure = 1,015.0 N ± 47.4 N; number of cycles = 28,452 ± 6,559). The conventional prostheses failed by fracturing of the acrylic teeth and veneering material that led to exposure of the metal framework. Half of the digital prostheses failed by superficial chipping of the veneering material, while the other half failed by the deformation and fracture of screws. CONCLUSION: Within the limitations of this study, the digital prostheses with the novel design and monolithic veneering material showed significantly higher strength compared with the conventional prostheses. The mode of acrylic failure of the digital prostheses was more favorable.
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ItemA Validation and Cost-Analysis Study of a Targeted School-Based Dental Check-Up Intervention: Children's Dental Program.(MDPI AG, 2020-11-26)BACKGROUND: Limited evidence exists to inform best practice approaches to implement school-based dental screening to address child retention via referral for dental services. This research tested the null hypothesis that a targeted school-based dental check-up program (intervention) has a 75% child retention rate for public dental care (H0 = 0.75). METHODS: A prospective non-randomised controlled trial was conducted with a convenience sampling approach in metropolitan Melbourne, Australia. Children in the intervention group were recruited from two preschools and two primary schools from a low socioeconomic area. Children in the standard care group were recruited from the local public dental service. Statistical analysis was performed using Stata IC Version 12. RESULTS: Children in the intervention (45%) were significantly less likely to have never had a dental check-up compared to standard care (20%) (p < 0.001). There was no significant difference for the child retention rate for the intervention group when compared against the null hypothesis (p = 0.954). The total society costs were AU$754.7 and AU$612.2 for the intervention and standard care groups, respectively (p = 0.049). CONCLUSIONS: This validation study provides evidence that a targeted school-based dental check-up program can achieve a 75% child retention rate and should be considered for program expansion.
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ItemEffects of Bovine Serum Albumin and High pH Pre-Treatment on the Remineralisation of Enamel Subsurface Lesions in vitro(KARGER, 2020-02)Accumulated intra-lesion protein such as serum albumin has been speculated to impede remineralisation of carious enamel lesions. The aim of this study was to assess whether intra-lesion bovine serum albumin (BSA) affected subsequent remineralisation of enamel subsurface lesions. Confocal microscopy was used to confirm localisation of BSA in artificial enamel subsurface lesions and its subsequent degradation by a high pH sodium hypochlorite treatment. An in vitro remineralisation experiment tested the effect of intra-lesion BSA, and its degradation by sodium hypochlorite, on remineralisation of subsurface lesions by casein phosphopeptide stabilised amorphous calcium fluoride phosphate. In addition, lesions without BSA were pre-treated with one of 2 high pH solutions (sodium hypochlorite or sodium hydroxide) prior to remineralisation to test whether the high pH pre-treatment influenced remineralisation. Data were obtained on remineralisation using transverse microradiography and were analysed with a one-way ANOVA. Intra-lesion BSA had no significant effect on remineralisation compared with that of control lesions. Pre-treatment of BSA-containing lesions with sodium hypochlorite significantly increased remineralisation. The lesions without BSA that were pre-treated with either sodium hypochlorite or sodium hydroxide also showed the same level of remineralisation as the BSA-containing lesions pre-treated with sodium hypochlorite indicating that the increased remineralisation was pH related. Hence, it was concluded that intra-lesion BSA did not affect remineralisation of artificial enamel subsurface lesions in this model system and that a high pH pre-treatment enhanced remineralisation.
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ItemAssociation between Rapid Maxillary Expansion and Nocturnal Enuresis in Children: A Pilot Study for a Randomized Controlled Clinical Trial(MDPI, 2020-12)Objectives: This pilot study was conducted to test the protocol of a randomized controlled trial evaluating whether rapid maxillary expansion (RME) can relieve nocturnal enuresis (NE) and improve breathing in children, after ruling out a placebo effect, and investigating whether the effects of RME and NE are related to the morphology of the upper airway. Methods: Seventy 6–15-year-old patients with NE were assessed for eligibility (e.g., constricted maxilla). Enrolled subjects were randomized to immediate treatment with RME (Group 1) or to have the same treatment (RME) delayed for at least six weeks (Group 2). Outcomes comprised the number of wet nights per week, the nocturnal urine production, and the scores of a pediatric sleep questionnaire at baseline, after active treatment (Group 1) or delayed treatment (Group 2), and after 3 months’ retention. Cone beam computed tomographies were taken at baseline and after retention. Results: Six patients were randomized: three in each group. In four of six patients, the number of wet nights per week decreased. Moreover, in responders, nocturnal urine production was reduced following RME. Conclusions: This pilot study suggested that RME might reduce the severity of NE and showed that the protocol of this randomized controlled clinical trial was appropriate.
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ItemPrevalence of Sleep-Disordered Breathing in Children Referring for First Dental Examination. A Multicenter Cross-Sectional Study Using Pediatric Sleep Questionnaire(MDPI, 2020-11)Background: Sleep-related breathing disorders (SRDB) are a group of pathological conditions characterized by a dysfunction of the upper airways. The value of SRDB's prevalence, in the pediatric population, ranges from 2 to 11% depending on the different methodologies used in measure and the difficulties in the diagnosis. The aim of this study was to assess the prevalence of SRDB using the Pediatric Sleep Questionnaire (PSQ). Methods: 668 patients were enrolled from the Department of Oral and Maxillo-Facial Sciences, Sapienza University of Rome, Italy and from the Unit of Integrated Pediatric Dentistry, University of Murcia, Spain. The questionnaires were administered to patients with no previous orthodontic and surgical treatment who attended on the first visit at the two units of pediatric dentistry. Data regarding general health status were extracted from the standard anamnestic module for first visit. Prevalence and logistic regression models were computed. Results: The ages ranged from 2 to 16 years old (average 7 years old). The prevalence of SRDB was 9.7% for the entire sample. The models showed a positive correlation between three variables (snoring, bad habits, and anxiety) and SRDB. Conclusions: The prevalence obtained demonstrates the relevance of sleep disorders in the pediatric population and highlights the central role of pediatric dentists in the earlier diagnosis of these disorders.
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ItemA Danish version of the oral health impact profile-14 (OHIP-14): translation and cross-cultural adaptation(BMC, 2020-09-10)BACKGROUND: The Oral Health Impact Profile-14 (OHIP-14) questionnaire assesses quality of life related to people's perception of oral disorders on their well-being. However, a translated and validated Danish version of OHIP-14 is not yet available. The purpose of this pilot study was to translate and cross-culturally adapt the English version of the OHIP-14 into Danish (OHIP-14-DK). In addition, to assess its content and face validity, internal consistency and test-retest reliability. METHODS: The English version of OHIP-14 was translated into Danish following a standard protocol of cross-cultural adaptation. Stages I-IV: translation phase to generate a pre-final version "OHIP-14-DK". Stage V: pre-testing phase. A random sample of 22 orthodontic patients (mean age 24.7 years, SD ±14.8; 14 females, 8 males) were selected at the Section of Orthodontics, Aarhus University, Denmark. All patients self-completed the OHIP-14-DK and were then interviewed to assess its content and face validity. Internal consistency was assessed with Cronbach's alpha coefficients. All patients completed the same questionnaire again at a one-week interval. Test-retest reliability was assessed using Spearman's correlation coefficient and intra-class correlation coefficient (ICC). RESULTS: The initial and back translations were very similar: the OHIP-14-DK proved to have a good level of equivalence with no translation errors or deviations. Furthermore, the OHIP-14-DK seemed well-adapted to Danish culture and was understood by individuals down to 12 years of age. Pre-testing demonstrated good face and content validity; interviews had a response rate of 100% and confirmed that each item was understandable without inducing reluctance or hesitation. Thus, responses were related to their corresponding item. Therefore, no final adjustments were required for the pre-tested version. Cronbach's alpha for the OHIP-14-DK subscales fell in the 0.75-0.84 range, indicating an adequate-to-good internal consistency. Spearman's correlation coefficient for the OHIP-14-DK total score was 0.77. The ICC for the OHIP-14-DK total score was 0.91. CONCLUSIONS: The OHIP-14-DK seems well adapted to Danish culture, proved to be face and content valid and also showed good internal consistency and excellent reliability. However, its psychometric properties still need to be tested. STUDY REGISTRATION: Not applicable.
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ItemTemporomandibular Disorder: a practical guide for dental practitioners in diagnosis and management(WILEY, 2020-09)Temporomandibular disorder is a broad term encompassing pain and/or dysfunction of the masticatory musculature and the temporomandibular joints. Pain arising from a temporomandibular disorder is a common reason for seeking dental care. It is essential that dental practitioners are able to accurately diagnose and manage this condition. Identifying people at highest risk of developing a temporomandibular disorder and knowing which procedures are more likely to initiate or exacerbate a temporomandibular disorder, are important to reduce the likelihood of its acute and chronic presentation. The aim of this paper is to provide the dental practitioner with a clinical guideline for reference including practical tools to examine, diagnose and manage patients with temporomandibular disorder. In addition the risk profile of patients and procedures is explored to help minimize the occurrence of temporomandibular disorders and mitigate its symptoms. The scope of the dental practitioner in the management of acute and chronic temporomandibular disorders is presented, with guidance about when referral to a specialist is indicated.
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ItemThree-dimensional analyses of short- and long-term effects of rapid maxillary expansion on nasal cavity and upper airway: A systematic review and meta-analysis(WILEY, 2020-08)INTRODUCTION: The purpose of this systematic review was to evaluate the three-dimensional (3D) changes occurring at short- and long-term follow-up after rapid maxillary expansion (RME) in nasal cavity (NC) and upper airway (UA) in growing patients. METHODS: A literature search up to 1 July 2019 was performed. Randomized and non-randomized clinical trials and cohort studies comparing the effects of RME in a paediatric population using 3D analyses based on computed tomography (CT), cone-beam CT and MRI were included. The risks of bias of the included studies were assessed using the Cochrane Collaboration's risk of bias tool, the GRADE approach and a customized tool. The random-effects meta-analyses of the mean differences and 95% confidence intervals of NC and UA volume changes were carried out, followed by subgroup analyses. RESULTS: Twenty-seven studies were included, with 18 selected for quantitative synthesis. Immediately after expansion, the nasopharynx and oropharynx increased significantly. After 3 months of retention, only the NC and nasopharynx showed a significant volume increase. Two studies mentioned the use of a sleep-disordered breathing questionnaire, and one study reported the difference before and after RME. None of the 27 articles included assessed the correlation between the skeletal widening and NC or UA volume changes after RME. CONCLUSIONS: The existing evidence confirmed only the short-term positive effect of RME on expanding the volume of the NC and the upper part of the UA. However, long-term stability could not be sustained.