ORCID Profile
0000-0001-6041-4799
Current Organisation
University of Queensland
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Publisher: Wiley
Date: 08-2023
DOI: 10.1002/MBO3.1377
Abstract: Oral biofilms are three‐dimensional (3D) complex entities initiating dental diseases and have been evaluated extensively in the scientific literature using several biofilm models and assessment techniques. The list of biofilm models and assessment techniques may overwhelm a novice biofilm researcher. This narrative review aims to summarize the existing literature on biofilm models and assessment techniques, providing additional information on selecting an appropriate model and corresponding assessment techniques, which may be useful as a guide to the beginner biofilm investigator and as a refresher to experienced researchers. The review addresses previously established 2D models, outlining their advantages and limitations based on the growth environment, availability of nutrients, and the number of bacterial species, while also exploring novel 3D biofilm models. The growth of biofilms on clinically relevant 3D models, particularly melt electrowritten fibrous scaffolds, is discussed with a specific focus that has not been previously reported. Relevant studies on validated oral microcosm models that have recently gaining prominence are summarized. The review analyses the advantages and limitations of biofilm assessment methods, including colony forming unit culture, crystal violet, 2,3‐bis‐(2‐methoxy‐4‐nitro‐5‐sulfophenyl)‐2H‐tetrazolium‐5‐carboxanilide inner salt assays, confocal microscopy, fluorescence in situ hybridization, scanning electron microscopy, quantitative polymerase chain reaction, and next‐generation sequencing. The use of more complex models with advanced assessment methodologies, subject to the availability of equipment/facilities, may help in developing clinically relevant biofilms and answering appropriate research questions.
Publisher: Wiley
Date: 20-03-2012
DOI: 10.1111/J.1600-0501.2012.02448.X
Abstract: The aim of the study was to evaluate the effect of experimental diabetes and metabolic control on de novo bone formation following the GBR principle under titanium dome with a hydrophobic or hydrophilic surface. Three groups of equal number of randomly allocated Wistar strain rats were created: (a) uncontrolled, streptozotocin-induced diabetes (D) (b) insulin-controlled diabetes (CD) (c) healthy (H). Each group was then further ided into two groups according to either 7 or 42 days of healing period, which received either a hydrophobic (SLA: A) or a hydrophilic (SLActive: B) dome. The undecalcified sections were evaluated by qualitative and quantitative histological analysis and the differences between means for the groups (D, CD, and H) and the type of domes (SLA and SLActive) at each of two observational periods (i.e. 7 and 42 days) were assessed by performing a two-way analysis of variance (ANOVA). In all experimental groups, significant de novo bone formation under the domes was observed at 42 days of healing. There was a tendency of increased new total bone (TB) formation in H and CD groups compared to D group at 42 days of healing. Also, the SLActive titanium surface showed a trend of promoting superior TB formation at the early observational period among the experimental groups, however these differences did not reach statistical significance. In regards to the bone-to-implant contact (BIC%) under the both dome treatments (SLA and SLActive), there was no statistically significant difference among the H, CD, and D groups at both 7 and 42 days. Despite of the presence of uncontrolled diabetes, substantial de novo bone formation can be achieved in titanium domes with a hydrophobic and a hydrophilic surface. The use of SLActive titanium surface may present a tendency to promote new bone formation in healthy and diabetic conditions at 7 days of healing, however the obtained data do not allow any robust conclusions.
Publisher: MDPI AG
Date: 22-10-2021
DOI: 10.3390/NANO11112799
Abstract: Soft tissue integration (STI) at the transmucosal level around dental implants is crucial for the long-term success of dental implants. Surface modification of titanium dental implants could be an effective way to enhance peri-implant STI. The present study aimed to investigate the effect of bioinspired lithium (Li)-doped Ti surface on the behaviour of human gingival fibroblasts (HGFs) and oral biofilm in vitro. HGFs were cultured on various Ti surfaces—Li-doped Ti (Li_Ti), NaOH_Ti and micro-rough Ti (Control_Ti)—and were evaluated for viability, adhesion, extracellular matrix protein expression and cytokine secretion. Furthermore, single species bacteria (Staphylococcus aureus) and multi-species oral biofilms from saliva were cultured on each surface and assessed for viability and metabolic activity. The results show that both Li_Ti and NaOH_Ti significantly increased the proliferation of HGFs compared to the control. Fibroblast growth factor-2 (FGF-2) mRNA levels were significantly increased on Li_Ti and NaOH_Ti at day 7. Moreover, Li_Ti upregulated COL-I and fibronectin gene expression compared to the NaOH_Ti. A significant decrease in bacterial metabolic activity was detected for both the Li_Ti and NaOH_Ti surfaces. Together, these results suggest that bioinspired Li-doped Ti promotes HGF bioactivity while suppressing bacterial adhesion and growth. This is of clinical importance regarding STI improvement during the maintenance phase of the dental implant treatment.
Publisher: Springer Science and Business Media LLC
Date: 10-2020
DOI: 10.1186/S40824-020-00196-1
Abstract: Biomaterial-based bone tissue engineering represents a promising solution to overcome reduced residual bone volume. It has been previously demonstrated that gradient and offset architectures of three-dimensional melt electrowritten poly-caprolactone (PCL) scaffolds could successfully direct osteoblast cells differentiation toward an osteogenic lineage, resulting in mineralization. The aim of this study was therefore to evaluate the in vivo osteoconductive capacity of PCL scaffolds with these different architectures. Five different calcium phosphate (CaP) coated melt electrowritten PCL pore sized scaffolds: 250 μm and 500 μm, 500 μm with 50% fibre offset (offset.50.50), tri layer gradient 250–500-750 μm (grad.250top) and 750–500-250 μm (grad.750top) were implanted into rodent critical-sized calvarial defects. Empty defects were used as a control. After 4 and 8 weeks of healing, the new bone was assessed by micro-computed tomography and immunohistochemistry. Significantly more newly formed bone was shown in the grad.250top scaffold 8 weeks post-implantation. Histological investigation also showed that soft tissue was replaced with newly formed bone and fully covered the grad.250top scaffold. While, the bone healing did not happen completely in the 250 μm, offset.50.50 scaffolds and blank calvaria defects following 8 weeks of implantation. Immunohistochemical analysis showed the expression of osteogenic markers was present in all scaffold groups at both time points. The mineralization marker Osteocalcin was detected with the highest intensity in the grad.250top and 500 μm scaffolds. Moreover, the expression of the endothelial markers showed that robust angiogenesis was involved in the repair process. These results suggest that the gradient pore size structure provides superior conditions for bone regeneration.
Publisher: Wiley
Date: 17-09-2016
DOI: 10.1111/CLR.12979
Abstract: This study assessed the effect of titanium surface modification on macrophage phenotype polarization and osseous healing under diabetic conditions. Critical-sized calvarial defects were created in healthy and streptozotocin-induced type I diabetic Sprague-Dawley rats. Titanium (Ti) discs with either large-grit sandblasted and acid-etched micro-rough (SLA) or hydrophilic-modified SLA (modSLA) surfaces were used to cover the healing defect for a period of up to 28 days. S les of the exudate within the calvarial defect and beneath the titanium discs were collected 1, 4 and 7 days post-surgery for inflammatory cytokine analysis using an ELISA. The macrophage phenotype(s) on the Ti disc surfaces were determined by CD11c+ (M1) and CD163+ (M2) immunofluorescent staining. S les of the healing defects at days 14 and 28 were also prepared for histomorphometric analysis. Cytokine levels in the diabetic animals were higher than those of the healthy group throughout the observation period. The modSLA surface significantly reduced MIP-2 levels at day 1 in both diabetic and healthy animals, and MCP-1 levels at day 4 in the diabetic animals. Immuno-fluorescent staining showed that an M2-like macrophage phenotype was more frequently found on the modSLA surface at day 1 in healthy and day 4 in both healthy and diabetic animals. Histomorphometric analysis showed more new bone formation on the modSLA surface at days 14 and 28 in both groups, although statistically significant differences were only found in the healthy group. Diabetic conditions greatly increased the expression of proinflammatory cytokines during osseous healing. The modSLA surface was shown to promote an M2-like macrophage phenotypic response in titanium adherent macrophages despite the significantly elevated inflammatory environment induced by uncontrolled type I diabetes. Modulation of the macrophage phenotype by the modSLA surface in the early healing period was associated with osseous healing under both healthy and uncontrolled diabetic conditions.
Publisher: Wiley
Date: 21-09-2021
DOI: 10.1111/JCPE.13543
Abstract: The aim of this study was to explore general dental practitioners' (GDPs) attitude to periodontal furcation involvement (FI). An online survey focused on diagnosis and management of periodontal FI was circulated to GDPs in seven different countries. A total of 400 responses were collected. Nearly a fifth of participants reported rarely or never taking 6‐point pocket charts 65.8% of participants had access to a Nabers probe in their practice. When shown clinical pictures and radiographs of FI‐involved molars, the majority of participants correctly diagnosed it. Although 47.1% of participants were very/extremely confident in detecting FI, only 8.9% felt very/extremely confident at treating it. Differences in responses were detected according to country and year of qualification, with a trend towards less interest in periodontal diagnosis and treatment in younger generations. Lack of knowledge of management/referral pathways (reported by 22.8%) and lack of correct equipment were considered the biggest barriers to FI management. Most participants (80.9%) were interested in learning more about FI, ideally face to face followed by online tutorials. Plans should be put in place to improve general dentists' knowledge and ability to manage FI, as this can have a significant impact on public health.
Publisher: Wiley
Date: 26-01-2021
DOI: 10.1111/JDI.13477
Abstract: Periodontal disease, a chronic inflammation induced by bacteria, is closely linked with diabetes mellitus. Many complications associated with diabetes are related to epigenetic changes. However, the exact epigenetic changes whereby diabetes affects periodontal disease remain largely unknown. Thus, we sought to investigate the role of diabetes‐dependent epigenetic changes of gingival tissue in the susceptibility to periodontal disease. We studied the effect of streptozotocin‐induced diabetes in minipigs on gingival morphological and epigenetic tissue changes. Accordingly, we randomly ided six minipigs into two groups: streptozotocin‐induced diabetes group, n = 3 and non‐diabetes healthy control group, n = 3. After 85 days, all animals were killed, and gingival tissue was collected for histology, deoxyribonucleic acid methylation analysis and immunohistochemistry. A diabetes mellitus model was successfully created, as evidenced by significantly increased blood glucose levels, reduction of pancreatic insulin‐producing β‐cells and histopathological changes in the kidneys. The gingival tissues in the diabetes group presented acanthosis of both gingival squamous epithelium and sulcular/junctional epithelium, and a significant reduction in the number and length of rete pegs. Deoxyribonucleic acid methylation analysis showed a total of 1,163 affected genes, of which 599 and 564 were significantly hypermethylated and hypomethylated, respectively. Immunohistochemistry staining showed that the hypomethylated genes – tumor necrosis factor‐α and interleukin‐6 – were positively expressed under the junctional epithelium area in the diabetes group. Diabetes mellitus induces morphological and epigenetic changes in periodontal tissue, which might contribute to the increased susceptibility of periodontal diseases in patients with diabetes.
Publisher: Wiley
Date: 06-2018
Publisher: Wiley
Date: 30-08-2019
DOI: 10.1111/CLR.13522
Abstract: As biomaterial-induced modulation of mediators of the immune response may be a potential therapeutic approach to enhance wound healing events, the aim of this study was to delineate the effects of titanium surface modification on macrophage phenotype and function. Rodent bone marrow-derived macrophages were polarized into M1 and M2 phenotypes and cultured on micro-rough (SLA) and hydrophilic modified SLA (modSLA) titanium discs. Macrophage phenotype and cytokine secretion were subsequently assessed by immunostaining and ELISA, respectively. Osteoblast gene expression in response to culture in the M1 and M2 macrophage conditioned media was also evaluated over 7 days by RT-PCR. M1 macrophage culture on the modSLA surface promoted an M2-like phenotype as demonstrated by marked CD163 protein expression, Arg1 gene expression and the secretion of cytokines that significantly upregulated in osteoblasts the expression of genes associated with the TGF-ß/BMP signalling pathway and osteogenesis. In comparison, M2 macrophage culture on SLA surface promoted an inflammatory phenotype and cytokine profile that was not conducive for osteogenic gene expression. Macrophages are able to alter or switch their phenotype according to the signals received from the biomaterial surface. A hydrophilic micro-rough titanium surface topography elicits a macrophage phenotype associated with reduced inflammation and enhanced pro-osteogenic signalling.
Publisher: Elsevier BV
Date: 2021
Publisher: Elsevier BV
Date: 09-2023
Publisher: Elsevier
Date: 2017
Publisher: Wiley
Date: 12-06-2019
DOI: 10.1111/JRE.12664
Abstract: To evaluate the influence of systemic zoledronate administration on the osseointegration of titanium implants with different surface topography in rat maxillae. Twenty Sprague-Dawley rats were ided into two groups-test (bisphosphonate) and control (healthy). Bisphosphonate administration began three weeks prior to implant placement, and the animals received zoledronate (66 μg/kg) three times per week. Forty endosseous implants with a moderately rough (20 implants) or a turned surface (20 implants) were immediately placed bilaterally into extraction sockets of maxillary first molars. Animals were sacrificed after 14 and 28 days of healing, and en bloc specimens were harvested for histological and histomorphometric analysis. Osseointegration was quantified by measuring the percentage of bone-to-implant contact. Bone-to-implant contact (BIC) (mean ± SD) values of moderately rough and turned implants at day 14 in test group were 17.62 ± 6.68 and 10.69 ± 1.48, respectively, while in the control group, they were 46.36 ± 5.08 and 33.29 ± 8.89, respectively. At day 28, BIC values of moderately rough and turned implants in the test group were 25.94 ± 7.87 and 7.83 ± 4.30, respectively, while in the control group, they were 72.99 ± 6.60 and 47.62 ± 18.19, respectively. Statistically significant higher BIC values were measured on moderately rough implants compared to turned implants at 28 days, and the control group compared to the test group for both implant surfaces. Histological observations for the control and the test groups demonstrated initial bone formation around moderately rough implants not only on the surface of the parent bone, as was the case with the turned surfaced implants, but also along the implant surface itself. Systemic zoledronate administration negatively influences osseointegration. Osseointegration was enhanced adjacent to moderately rough compared to turned implants in both the presence and absence of systemic zoledronate administration. Therefore, topographical surface modification may partially offset the negative impact of zoledronate administration.
Publisher: Wiley
Date: 18-02-2016
DOI: 10.1111/CLR.12571
Abstract: Published information regarding the use of rat jawbones for dental implant osseointegration research is limited and often inconsistent. This study assessed the suitability and feasibility of placing dental implants into the rat maxilla and to establish parameters to be used for dental implant research using this model. Forty-two customized titanium implants (2 × 3 mm) were placed bilaterally in the maxillary first molar area of 21 Sprague-Dawley rats. Every animal received two implants. The animals were subsequently sacrificed at days 3, 7, 14, 28 and 56 post-surgery. Resin-embedded sections of the implant and surrounding maxilla were prepared for histological and histomorphometric analyses. The mesial root of the first molar in the rat maxilla was the optimal site to place the implant. Although the most apical 2-3 threads of the implant penetrated into the sinus cavity, 2 mm of the remaining implant was embedded in the bone. New bone formation at day 7 around the implant increased further at day 14, as measured by the percentage of bone-to-implant contact (%BIC) and new bone area (%BA) in the implant thread chambers (55.1 ± 8.9% and 63.7 ± 7.7%, respectively). There was a further significant increase between day 14 and 28 (P < 0.05), however, no significant differences were found between day 28 and 56 in either %BIC or %BA. The mesial root socket of the first molar in the rat maxilla is a useful model for dental implant research. Osseointegration following implant placement as measured by BIC plateaued after 28 days. The recommended implant dimensions are 1.5 mm in diameter and 2 mm in length.
Publisher: Wiley
Date: 30-11-2017
DOI: 10.1111/PRD.12150
Abstract: The integrity of the peri-implant soft-tissue seal is crucial for maintaining peri-implant tissue health. Whilst the transmucosal component of the restored implant shares some common features with teeth, namely the presence of a junctional epithelium and a connective tissue component, there are some important differences. A key difference is the nature of the relationship of the connective tissue with the implant surface, whereby there is 'adaptation' of collagen fibers in a parallel orientation in relation to the implant, but insertion of fiber attachment perpendicularly into cementum in the case of teeth. This, combined with reduced cellularity and vascularity in the peri-implant connective tissue, may make implants more susceptible to disease initiation and progression. Furthermore, the presence of a subgingival connection between the implant and the abutment/restoration poses some specific challenges, and maintaining the integrity of this connection is important in preserving peri-implant tissue health. Implant design features, such as the nature of the connection between the implant and the abutment, as well as the surface characteristics of the abutment and implants, may influence the maintenance of the integrity of soft tissue around implants. Iatrogenic factors, such as incorrect seating of the abutment and/or the restoration, and the presence of residual subgingival cement, will lead to loss of soft-tissue integrity and hence predispose to peri-implant disease.
Publisher: Elsevier
Date: 2017
Publisher: Wiley
Date: 19-09-2023
DOI: 10.1002/JPER.23-0086
Location: Brazil
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Ryan SB Lee.