Melbourne Dental School - Theses
Permanent URI for this collection
Search Results
1 - 10 of 85
-
ItemA study of endodontically-related bacteria(University of Melbourne, 2008)
-
ItemInsertion sequence ISPg4 as a genetic virulence marker for porphyromonsa gingivalis in chronic periodontitis patients(University of Melbourne, 2006)
-
Item
-
ItemThe saliva- a functionally active body juice(University of Melbourne, 1937)
-
ItemThe microscopical pathology of pyorrhoea alveolaris(University of Melbourne, 1935)
-
ItemScreening for Type 2 Diabetes Mellitus initiated through the dental setting: a cost-effectiveness analysis( 2019)Background. Diabetes Mellitus (DM) is the fastest growing chronic condition in Australia. Approximately, 30% of DM in Australia is undiagnosed. Early identification may delay or prevent the onset of DM with minimal complication. In the Western Pacific (WP) region, Australia has the highest per capita spending on DM. With the rising cost of healthcare, increasing emphasis is being made to ensure that health interventions are not only practical but also cost-effective that can save resources which otherwise may have to be spent on complication and hospital admission. By stretching the number of contact points between health care providers and individuals seeking care, there is plenty of opportunity for early identification of asymptomatic individuals with Type 2 Diabetes Mellitus (T2DM). With this link between DM and periodontal disease, dentists may have an unrealized opportunity to identify risk groups and refer them to physicians for further care. For any screening activity in the dental setting, the participation of Oral Health Professionals (OHP) is important. Little is known as to how well oral health professionals incorporate into practice on the evidence supporting the link between DM and periodontal disease. Besides that, no previous studies have reported the cost-effectiveness of opportunistic screening using a diabetes risk assessment tool in the dental setting. As such, the aim of the thesis is twofold. To explore the Victorian oral health professionals (OHP) knowledge, attitude and practice (KAP) around DM and to evaluate the overall economic justification of screening for diabetes and pre-diabetes in the dental setting. Methods. A cross-sectional survey of Victorian OHP was conducted. The questionnaire consisted of sociodemographic, practice characteristics and diabetes-related KAP. Descriptive statistics with frequencies and percentages were used to summarize the variables. A Mann-Whitney and Kruskal-Wallis test was performed to determine differences in OHP response to the KAP questions. The screening model consists of a decision tree and a disease progression Markov model to identify the risk of T2DM over a ten-year period. Literature data were used for the risk categorisation and disease transition for health states. The cost-effectiveness of screening was compared to no screening option. A hypothetical population of 40 to 74-year-old Victorian dental patients with no previous history of DM were screened with the Australian type 2 Diabetes Risk Assessment Tool (AUSDRISK). Those identified as high-risk follow-up with the physician for screen diagnosis using Fasting Plasma Glucose (FPG). Based on the previous finding from two-step screening in the dental setting the model made an assumption that 21.5% of the dental patient identified as high risk follow up with the physician. The cost-effectiveness was analysed from a societal perspective. The main outcome measure includes cost per case detected as undiagnosed T2DM, new cases of T2DM. A univariate sensitivity analysis was performed to determine the effect of different physician follow-up rate from the dental setting to identify undiagnosed T2DM. Results. The survey analysis included 197 OHP. General and specialist dentist constitute 65% and 11% of the response and the remainder were dental hygienist and therapist. Around 86% of the OHP showed adequate knowledge of DM. Further 93% and 81% of the OHP expressed positive attitude and practice behaviour towards T2DM screening and management. For OHP to perform chair-side screening for DM, 58% felt it was essential, and 70% felt it was appropriate. More female (67%) and public sector OHP (79%) felt it is important to conduct chair-side screening for T2DM. The majority (65.4%) of the OHP agreed on consent as the most important and insurance coverage as the least important (43%) consideration for T2DM screening. Under model assumption, the number of dental patients identified as undiagnosed T2DM and pre-diabetes were 4,108 (0.3%) and 10,072 (0.8%). The cost incurred for one new case of undiagnosed T2DM and pre-diabetes were AUD 15,508 and AUD 6,325. The Number Needed to Screen (NNS) to identify one new case of undiagnosed T2DM and pre-diabetes were 288 and 117. Among those followed up with the physician, at the end of five years, 81.5% had Normal Glucose Tolerance (NGT), 8.1% had Impaired Fasting Glucose (IFG), 6.9% had T2DM, and the all-cause mortality was 3.5%. At the end of the ten-year period, 10% had T2DM. The overall and disease-free survival was 92.8% and 82.8%. Discussion. Majority of OHPs had adequate knowledge and a positive attitude towards T2DM screening in the dental setting. The survey identified patient willingness as the most important consideration among the OHPs for implementing T2DM screening in the dental setting. The screening model identified several methodological challenges due to incongruent data and unsuitable comparator. Despite that, opportunistic screening with AUSDRISK was found to be neither clinically effective nor cost-effective compared to screening in the medical setting. High screening cost, poor predictive ability of AUSDRISK, low prevalence of the disease, unnecessary physician referral besides uncertain benefits, fear of over diagnosis and poor patient compliance makes screening for T2DM in the dental setting difficult to justify. The model findings are in line with previous estimates on AUSDSRISK as a screening tool. In financially constrained health system resource allocation will need to be based on favourable evidence that screening can reduce disease levels in the community, demonstrate health benefits at an acceptable cost. A two-step opportunistic screening that includes a risk assessment followed by a Point-of-Care (PoC) HbA1c may offer some benefits in the low- and middle-income countries.
-
ItemDental implant maintenance and home hygiene – information pathways, clinical practice and patient realities in Australia( 2019)Dental implants have widened treatment paradigms in dentistry since the 1980s and are placed in the millions annually around the world, but plaque-induced peri-implant diseases which can reduce treatment success are not completely understood. The real-life practices of patients and dental practitioners in minimising peri-implant disease risks have not been widely documented. The information sources from which dental practitioners learn peri-implant maintenance are highly variable and also rarely documented. This thesis investigated the flow of information in implant maintenance and hygiene in Australia: from research, to educators, dental practitioners and patients; the limitations present and areas of further development. A series of cross-sectional surveys was conducted to investigate: the hygiene habits of patients with implants in the community, patient-reported outcomes, implant success and peri-implant outcomes; the implant dentistry training attended and provision of implant services by dental practitioners in Australia; dental practitioners’ preferences in implant hygiene instruction, diagnostics and maintenance, including the role of oral health practitioners; and the teaching of implant maintenance topics within implant dentistry education in Australia. A survey of 51 patients in private general dental practice found 7.8% had peri-implantitis and 33.3% had peri-implant mucositis (7.7% and 24.4% of 78 implants respectively). At the implant level, peri-implant disease prevalence was significantly higher where implants were cleaned only with toothbrushing (p<0.001) or had plaque/calculus present (p<0.001). Implant success was significantly reduced if any local factors affecting hygiene accessibility were present (p<0.001). Patients recalled mixed provision of implant hygiene instructions from their treating dentists and reported 7.7% of implants as aesthetically unsatisfactory and 9.0% as having symptoms. A survey of 303 general dentists found continuing professional development was the most common highest level of implant training attended, graduation decade affected the types of implant training attended, and dentists are providing implant treatments increasingly earlier in their careers. Highest attended training level was significantly correlated to greater complexity of implant treatment and maintenance services provided, and a more preventative approach in implant hygiene instruction. Conversely, dentists with little implant training and/or who do not provide implant treatments may not be providing optimum maintenance and preventative information. Compared with the dentists, 154 oral health practitioners surveyed reported more preventative and evidence-based attitudes to implant hygiene instruction, diagnostics and maintenance, and they provided the bulk of preventative services in their workplaces. Implant dentistry education convenors were surveyed (24 respondents outlining 43 programs) and implant maintenance teaching was found to generally reflect the available literature, which is established for diagnostics but limited for patient-performed hygiene, professional maintenance and review. Some respondents acknowledged the need to update their inclusion of implant maintenance topics. As the peri-implant disease, hygiene and maintenance literature develops, current challenges include multi-disciplinary communication and the continuing development of implant dentistry education. By documenting current trends and identifying areas for clinical improvement and further research, it is hoped that this thesis, through the lens of implant hygiene and maintenance, provides possible future pathways for implant dentistry in Australia, to ultimately optimise treatment success and positive patient outcomes.
-
ItemThe Role of Candida in Oral Lichen Planus (OLP)( 2019)Purpose: Oral lichen planus (OLP) is a chronic condition characterised by T cell mediated destructions that is currently of unknown cause. OLP can be variably symptomatic with some patients experiencing no symptoms and others requiring extensive symptomatic management. Candida spp. can be found in association with OLP and due to this prophylactic treatment for Candida spp. is usually accounted for in the symptomatic management of OLP. This is despite current evidence not supporting concurrent use of antifungal therapy in the management of OLP with topical steroids. A potential hypothesis for the cause of OLP is an interaction of host genetic susceptibility combined with an environmental trigger that initiates disease in the susceptible host. Another equally likely hypothesis is that OLP is a true autoimmune condition with autoimmunity directed against a currently unknown epithelial autoantigen. The oral cavity represents a unique microenvironment that plays host to many commensal and opportunistic microorganisms. The oral microbiota, specifically Candida spp., could act as an aetiological trigger for the chronic T-cell mediated inflammation the defines OLP, specifically through activation of mucosal associated invariant (MAIT) cells. The role of Candida in the aetiopathogenesis and symptomatic management of OLP is currently unknown. Hypothesis and Aim: The overall hypothesis was that Candida may play an aetiological role in the OLP disease process exerting an effect on T cells and cytokine expression and that adjunctive treatment is required in the symptomatic management of OLP. The overall aim of this study was to determine whether Candida plays an aetiological role in OLP as well as determine if specific treatment of Candida is required in symptomatic patients with OLP. Materials and Methods: 14 control and 7 OLP test patients, 3 assigned to the placebo and 4 assigned to the antifungal treatment group, completed the clinical study. Assessments of clinical appearance, symptoms, Candida, salivary acetaldehyde and medication use were made at 0, 6 and 12 weeks for OLP patients with assessments of Candida and salivary acetaldehyde made at baseline only for controls. 20 random OLP formalin fixed paraffin embedded (FFPE) samples were stained using a fluorescent multiplex immunohistochemistry (mIHC) protocol for the markers cluster of differentiation (CD)3, CD8, DAPI, interleukin 18 receptor 1 (IL18R1), CD161, MR-1 and T cell receptor (TCR) V alpha 7.2. The slides were scanned with the Vectra Automated Multispectral Imaging System (PerkinElmer, USA) to generate multispectral images (MSI). The MSI were then analysed with tissue segmentation and single antibody algorithms for both HALO (Indica Labs, USA) and inForm 2.4.1 (PerkinElmer, USA) to validate a method for quantitative analysis. Following validation of HALO (Indica Labs, USA) for quantitative analysis the above process was repeated on 89 FFPE biopsy tissue samples from 73 patients with OLP (28 asymptomatic, 30 symptomatic and 16 samples with concurrent Candida (9 symptomatic and 7 asymptomatic), for comparison with 15 patient samples of fibroepithelial polyp (FEP). All samples were tested for presence of Candida with periodic acid-Schiff (PAS) staining. A BioPlex assay was performed to measure the cytokines interferon gamma, tumour necrosis factor alpha, interleukin (IL) 17A, IL-18, IL-12p40, IL-12p70, IL-22 and IL-23. Supernatant for this experiment was collected at 8, 12 and 24 hours following prior incubation of peripheral blood mononuclear cells (PBMC) in PBMC media supplemented with either 10% v/v effluent derived from C. albicans biofilms or 10% v/v artificial salivary media (ASM). In addition, some wells were supplemented with either CD28 and/or phorbol 12-myristate 13-acetate (PMA)/Ionomycin. Flow cytometry was performed using TCRV alpha 7.2, CD3, CD161, CD218a, CD4, CD8 and CD45 to define MAIT cells and T cell subsets. Prior to performing flow cytometry PBMC were incubated for 6 hours in PBMC media supplemented with either effluent derived from C. albicans biofilms or 10% v/v ASM with or without CD28. Results: Results of this study showed no significant differences existed between the control group and the OLP test group at baseline with respect levels of salivary acetaldehyde, and Candida colony forming units (CFU). Downward trends were noted in both groups with respect to clinical appearance and subjective analysis of symptoms from baseline to 12 weeks. Trends noted from assessment of CFU and salivary acetylaldehyde levels between the test groups should be viewed with caution due low levels of detection at baseline and the wide spread of data. Minor variability between the tissue segmentation algorithms with the trained algorithm for inForm 2.4.1 (PerkinElmer, USA) being the slightly less variable of the two. For quantitative cell analysis and identification of single antibody positive cells HALO (Indica Labs, USA) proved to be the least variable of the two trained algorithms. The presence of MAIT cell phenotypes were confirmed within the subepithelial infiltrate of OLP. Reduced MAIT cell phenotype expression was noted in the presence of Candida and/or symptoms in OLP with decreased expression of CD161 noted in the presence of symptoms whilst decreased expression of TCRV alpha 7.2 was noted in the presence of Candida. Presence of PMA/Ionomycin and Candida effluent were factors that increased the expression of interferon gamma, tumour necrosis factor alpha, IL-17A, IL-18, IL-22 and IL-23, cytokines that are associated with MAIT cell activation. Across all timepoints the presence of Candida effluent and CD28 resulted in upregulation of IL-18 and tumour necrosis factor alpha. MAIT cells were not significantly affected by the presence of either effluent or CD28 suggesting that neither Candida effluent nor CD28 alone or the combination of the two were shown to induce MAIT cell proliferation. Conclusion: Adjunctive treatment of symptomatic OLP with a topical antifungal did not significantly affect the presence of symptoms, erythema, CFU, Candida spp. or production of salivary acetaldehyde. HALO (Indica Labs, USA) was shown to be the more reliable program for mIHC quantitative cell analysis in FFPE OLP tissue. Analysis of mIHC in OLP FFPE tissue identified MAIT cells within the OLP inflammatory infiltrate with decreased expression of CD161 and TCRV alpha 7.2 noted in the presence of symptoms and Candida respectively. Finally, Candida effluent was unable to induce proliferation of MAIT cells in PBMC. However, cytokines associated MAIT cell activation and OLP, specifically interferon gamma, tumour necrosis factor alpha, IL-17A, IL-18, IL-22 and IL-23, were shown to be upregulated in the presence of Candida effluent derived from C. albicans biofilm.
-
ItemNon-smokers, Non-drinkers: Assessing surgical outcomes in a clinically distinct cohort of Oral Squamous Cell Carcinoma patients( 2019)Background Tobacco and alcohol intake are responsible for approximately 65-70% and 20-35% respectively of oral squamous cell carcinomas (SCC). Non-smoking, non-drinking (NSND) patients represent approximately 13-35% of the oral SCC population and are more likely to be young (Mean 20-35 years) or elderly (Over 70 years) females with a predilection for tongue, gingivae and lower lip sites. Although approximately 24% of head and neck cancers occur in patients over 70 years old, there are few published reports of oral SCC in elderly patients. This group appears to be characterized by a higher proportion of NSND females. Bone invasion by oral SCC necessitates jaw resection. Ideally, pre-operative imaging can be used to guide resection. The current rate of non-invaded mandible resections ranges between 20 and 100%. Even with free-flap reconstruction, segmental resection still results in cosmetic and functional deficits, donor site morbidity and significant physiological strain resulting in increased risk, prolonged recovery and need for rehabilitation. Decreased physiological reserve and multiple medical co-morbidities make complex surgery undesirable in an elderly population. Marginal resection aims to maintain bony continuity to avoid complex reconstruction. Objectives The objectives of this study were: 1. Examine differences in survival and clinical outcomes of elderly patients without traditional risk factors presenting with oral squamous cell carcinoma. 2. Determine the accuracy of computed tomography (CT) and magnetic resonance imaging (MRI) at identifying bone invasion in oral SCC. Materials & Methods Retrospective review of 287 consecutive patients divided into 2 treatment period cohorts treated for oral SCC between the 1st Jan 2007 and 31st Dec 2012.. Patients were classified as either smoker-drinkers (SD) or non-smoking, non-drinking (NSND). Only patients with oral sub-site primaries according to ICD-10 were included. Carcinomas of the lip, tonsil, base of tongue and oro-pharyngeal sub-sites were excluded. A subset of 109 patients who underwent mandibular resection were also reviewed for bone invasion. 83 of these patients had pre-operative CT imaging studies of diagnostic quality available for review and 72 underwent MRI which were compared to histological resection specimens. Results Of the study population (N=287), 24.4% were NSND and 9.75% were NSND elderly (older than 70 years) females. Disease specific survival at 5 years was significantly reduced when NSND elderly females were compared to all other patients (p <0.001) as well as age matched controls (p = 0.006). This effect was verified independently in each cohort. Bone invasion was detected in 44 out of 109 (40.4%) resection specimens. Bone invasion was identified on CT imaging in 31 out of 83 cases (37.3%) and by MRI in 35 out of 72 cases (48.6%). The sensitivity and specificity of CT for detecting bone invasion was 69.0% and 79.6% respectively. The sensitivity and specificity of MRI for detecting bone invasion was 87.1% and 80.5% respectively. Conclusions The results of this study suggest that NSND elderly females are a distinct patient population with poorer disease specific survival outcomes and that negative imaging studies should not preclude an oncologically safe bony resection if indicated on clinical grounds.
-
ItemThe effectiveness of using a periodontal endoscope as an adjunct to non-surgical periodontal therapy: clinical, radiographic and microbiological results( 2019)ABSTRACT Non-surgical periodontal therapy has been one of the main treatment approaches for managing patients with periodontal disease for decades. The aim of this treatment is to remove bacteria and subgingival deposits, create a “clinically healthy” environment and improve microbial levels to levels that is compatible with health. Conventional non-surgical debridement includes both hand and powered instruments with the ideal end point being a smooth root surface. Periodontal endoscopy was developed in the late 1990s and features miniaturized digital video technology allowing the operator to directly visualise the subgingival environment and at the same time remove any calculus or debris from the root surface with the use of hand or powered instruments. The benefits of direct visualisation technology in improving clinical and inflammatory outcomes were demonstrated in retrospective and prospective studies as well as randomised controlled studies utilizing either split-mouth design or parallel design. However, there was a need to investigate if endoscope scaling and root debridement (SRD) is more effective in reducing levels and numbers of periodontal pathogens as compared to conventional nonsurgical treatment. Also, if bacterial counts decrease, can they be maintained or reduced even further with strict three monthly supportive periodontal maintenance therapy (SPT). Osseous changes can occur after nonsurgical periodontal therapy. However, it is often difficult to determine if changes have occurred due to limitations with conventional radiography. This study included the use of standardized radiographs using customized positioning stents and paralleling x-ray holding devices. Digital radiography and digital software were used to determine areas of osseous change. Aims 1. To compare endoscope-assisted SRD (SRD-with endoscope) to traditional SRD (SRD-only) in reducing clinical parameters over a 12-month period. 2. To assess if endoscope assisted SRD shows more evidence of radiographic changes after the 12-month period compared to conventional SRD. 3. To compare bacterial counts of 11 species including Aggregatibacter(Actinobacillus)actinomycetemcomitans)(A. actinomycetemcomitans); the red complex ((Porphyromonas gingivalis(P. gingivalis); Tannerella forsythia (T. forsythia) and Treponema denticola (T. denticola)); the orange complex ((Prevotella intermedia (P. intermedia); Peptostreptococcus micros (P. micros) ; Fusobacterium nucleatum/periodonticum (F. nucleatum)); the orange-associated complex ((Campylobacter rectus (C. rectus); Eubacterium nodatum (E. nodatum)); the green complex ((Eikenella corrodens (E. corrodens)) and Capnocytophaga species ((Capnocytophaga sp.) (C. sputigena; C. gingivalis; C. ochracea)) in both groups over a 12-month period. 4. To determine the need for surgical intervention in both test and control groups after the 12-month treatment. Materials and Methods The study included 38 participants diagnosed with chronic moderate to advanced periodontitis. Nineteen participants were included in the test group (SRD-with perioscope) and 19 in the control group (SRD-only) by consecutive allocation. Clinical examination included probing pocket depths (PPD), probing attachment levels (PAL), gingival recession, assessment of furcation, mobility, bleeding on probing (BOP) and plaque scores (PI). The measurements were recorded at baseline, three and twelve months and differences in means between groups were calculated for all clinical parameters. The Hain Lifescience Micro-IDent test was utilized for the microbial analyses. Five sterile paper points were inserted into five of the deepest pockets, placed into a sterile test tube and sent in a water-resistant bag to Nehren, Germany for analysis. Eleven putative pathogens namely A. actinomycetemcomitans, P. gingivalis, P. intermedia , T. forsythia, T. denticola, P. micro, F. nucleatum, C. rectus, E. nodatum, E. corrodens and Capnocytophaga sp., were analysed at each time point and compared between the control (SRD-only) and test group (SRD-with perioscope). Analysis of pathogens in their respective complexes namely the red, orange, orange-associated and green complexes were also included. Standardised radiographs were taken at sites with the deepest pockets and in sites displaying angular/vertical bone loss using positioning stents at the baseline and 12-months. The Digimizer Image Analysis software (2005-2018 MedCalc Software bvba, Belgium) was used to measure from the cemento-enamel junction (CEJ) to the alveolar bone crest and changes were tracked in millimetres between radiographs taken pre-SRD and at twelve months. Linear measurements were utilized to determine mean radiographic bone levels (RBL). Results There were no significant differences between groups with regards to age, gender, medical history and disease severity. Both groups showed significant improvements in all clinical parameters after therapy (p<0.05). At three months, no statistically significant differences could be found between groups with mean PPD, mean PAL, BOP and PI. However, for PPDs 7-9 mm the test group had a significantly lower percentage as compared to the control group. At twelve months, the mean PPD was found to be significantly lower in the test group (2.70+0.2 mm) as compared to the control group (2.96+0.4 mm) (p<0.05). In addition, the test group also had lower BOP (4.3+3.2%) percentage as compared to the control group (11.95+7.1%). PI percentage (25.61+3.9%) was also reported to be lower in this group as compared to the control group (30.11+6.3%). The test group had less change in gingival recession (-0.13+0.2 mm) as compared to the control group (-0.5+0.6 mm) from baseline to twelve months (p<0.05). There were no statistically significant differences found between the test and control groups with regards to reduction of periodontal pathogens and their complexes (p>0.05). Both SRD-only and SRD-with perioscope resulted in decreases in numbers of periodontal pathogens including, P. gingivalis, T. forsythia, T. denticola, P. intermedia, P. micro, E. nodatum and E. corrodens post-therapy and at twelve months with numbers remaining below pre-treatment levels. However, A. actinomycetemcomitans, C. rectus, and Capnocytophaga sp. decreased post-therapy in both groups but increased at twelve months. F. nucleatum increased in both groups post-SRD and then were reported at lower levels at twelve months. Both the red and orange complex had lower numbers in the test group at twelve months, with the control group having lower numbers of the green and orange-associated complexes. The mean change in RBL was significantly higher in the test group (0.69+0.3 mm) as compared to the control group (0.49+0.2 mm) (p<0.05). This positive change in mean RBL is indicative of more radiographic bone gain in the test group. There were no differences reported between groups with regards to mean change in RBL for single-rooted teeth (p>0.05). However, for multi-rooted teeth more radiographic bone gain was observed in the test group (0.83+0.5 mm) with a higher mean change in RBL as compared to the control group (0.46+0.4 mm) (p<0.05). The test group had a higher frequency of RBL between 0.5 mm and 1.0 mm and 1.0 mm to 1.5 mm as compared to the control group, inferring that the test group had more sites with radiographic bone gain in this range as compared to the control group. Conclusions Both non-surgical treatment methods used resulted in positive outcomes in clinical, microbiological and radiographic parameters. The adjunctive use of the perioscope significantly improved PPDs 7-9 mm at three and twelve months. The mean PPD at twelve months was significantly lower in the test group as compared to the control group. Less change in gingival recession was observed using the endoscope. The test group had significantly lower BOP% and PI% at twelve months. No significant differences between groups were observed with analyses of the eleven pathogens and complexes of bacteria. The significantly higher mean RBL observed in the test group as compared to the control group is suggestive of more radiographic bone gain in this group. This outcome was also observed for multi-rooted teeth in the test group.