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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Cephalometric evaluation of soft tissue effects induced by a class II corrector in different facial patterns

Ward, Robert 06 July 2015 (has links)
Objective: To determine the magnitude of soft tissue changes in subjects with different facial patterns following Class II correction. Materials/Methods: A retrospective sample of 80 subjects exhibiting Class II malocclusions was used. Subjects were categorized into facial types according to pre-treatment values of MPA and Y-axis, which yielded 20 brachycephalic, 40 mesocephalic, and 20 dolichocephalic subjects. Data collection included digital analysis on the pre-treatment (T0) and post-treatment (T1) cephalometric radiographs. A paired t-test statistic was used to investigate the differences between the three facial groups at T0 and T1. Conclusions: There are differences in the soft tissue effects observed in patients treated with the XbowTM appliance which are related to the pre-existing facial pattern (p<0.05): The mesocephalic group showed increased retrusion of the upper lip to E-Plane compared with brachycephalic, and dolichocephalic groups. The dolichocephalic group showed significantly more flattening of the mentolabial fold compared to the mesocephalic group.
42

Assessing the validity of a questionnaire for parents to determine their child’s caries risk

Huminicki, Amanda 08 July 2015 (has links)
Dental caries is a very common chronic infectious disease that is preventable and related to dental behaviours. The objective of this study was to develop a parental questionnaire to predict the child’s caries risk without professional evaluation and assess if risk factors worked together and if behaviours changed over time. At baseline, a survey and examination for caries were administered to 100 subjects aged 1 to 3 years old in Winnipeg, Manitoba. Six months later the same survey and examination were administered. Statistical analysis included logistic regression, Pearson Chi-squared, McNemar’s, Fisher’s exact tests and paired T-tests. The main finding was this survey could not predict future caries risk. Parents’ reports of visible cavities/fillings in their child predicted caries. Few risk factors changed significantly over time. A change in developmental delay corresponded to a change in caries. Overall, caries risk was found to be complex and requires further investigation.
43

Effect of anticipatory guidance on the presence of cariogenic bacteria in preschool children

Lekic, Nikola 15 August 2014 (has links)
Objectives: This study was designed to address whether or not the level (high or low) of Streptococcus mutans in the saliva of preschool children can be used as an indicator of caries risk. Material and Methods: Levels of Streptococcus mutans was assessed in saliva of 100 preschool children, before and approximately 6-months after receiving a health promotion intervention known as anticipatory guidance. The S. mutans bacterial level was assessed using an immunoassay system (Saliva-Check MUTANS) based on monoclonal antibody technology. Bacterial counts were determined at baseline as well as at a six month recall examination. Obtained data was analyzed using SPSS 20.0 for Windows to report frequencies and to look for trends and associations between the dependent and independent variables. Bivariate analysis (ANOVA, Chi Square/Fishers/McNemar exact test) was used to identify associations between variables. Results: The main finding of this study was that higher levels of Streptococcus mutans were associated with higher caries prevalence at baseline, and caries incidence at follow-up. Furthermore following anticipatory guidance, the levels of Streptococcus mutans were reduced at the subsequent follow-up examination, approaching but not reaching statistical significance, and caries incidence was significantly lower in subjects demonstrating low Streptococcus mutans levels. Conclusions: Results from this study have shown that anticipatory guidance, offered to caregivers and children at an initial examination, led to a statistically non-significant reduction in the proportion of children with high Streptococcus mutans levels upon recall six mothers later. Children with low Streptococcus mutans levels were also less likely to develop new dental caries. These findings suggest that Streptococcus Mutans counts could be used to assess caries risk and encourages clinicians to provide anticipatory guidance to their patients to help avoid the development of new caries.
44

Orthodontic shear bond strengths of a self-adhering resin to enamel, restorative composite and porcelain

Bernas, Andrew J. 25 July 2013 (has links)
As new adhesive products become available in restorative dentistry, investigating their potential application for orthodontic use is warranted. Vertise Flow (Kerr) is a self-adhering flowable resin and is being marketed for use as a sealant, porcelain repair and small class I restorations. It has potential for use as an orthodontic adhesive. Objective: Determine if Vertise Flow (Kerr) is suitable for bonding fixed orthodontic appliances to enamel, restorative resin composite and porcelain with minimal surface preparation. Methods: Shear Bond Strengths (SBS) from six (6) groups of fifteen (15) bonded stainless steel lingual buttons (Ormco) were obtained over three time points (24hr, 7 days, and 3 months). The six test groups were: 1.Vertise Flow to enamel (Tt) with coarse pumice debridement, 2. Transbond XT (3M, Unitek) to enamel (Tc) with phosphoric acid etching [control], 3.Vertise Flow to Herculite Ultra (Kerr) (Cc) with coarse pumice debridement, 4. Vertise Flow to Filtek Supreme Ultra (3M, ESPE) (Ct) with coarse pumice debridement, 5. Vertise Flow (Kerr) to porcelain (Pt) with diamond bur roughening, and 6. Transbond XT (3M Unitek) to porcelain (Pc) with hydrofluoric acid etching. Samples were stored in distilled water and incubated at 37C. The buttons were then debonded with a Zwick Universal Testing machine using a 10 kN load cell with a crosshead speed of 0.5mm/min. Debonded buttons were evaluated based on a modified Adhesive Remnant Index (ARI). Statistical assessment of the data was performed using parametric and non-parametric tests, with p<0.05 as the threshold for statistical significance. Results: The mean SBS obtained in all groups at each time point were >4MPa and varied between 8.69MPa and 27.44MPa. Statistical differences were found within the composite and porcelain groups at T1, and the enamel and composite groups at both T2 and T3. Nearly half of the sample (47.2%) achieved an ARI score of 5 (100% adhesive left on button base). Conclusion: Vertise Flow potentially provides clinically acceptable bond strengths to enamel, restorative resin composite and porcelain with minimal surface preparation. Furthermore, upon removal, minimal adhesive clean-up is required thus saving valuable chair time. Based on the results in this study, future in vivo investigation is suggested.
45

Shear bond strengths of two new self-etching primers

Ho, Andy CS 25 June 2010 (has links)
Purpose: To evaluate the in vitro shear bond strength (SBS) of orthodontic attachments using 2 self-etching primers (SEP): iBOND and G-Bond. Methods: 180 molars were randomly divided into 12 groups. Teeth were bonded with a stainless steel button using Transbond XT composite. The bonding agents were iBOND, G-Bond, Transbond Plus SEP and Transbond XT primer (control). SBS’s immediately, 24hours and 3months were measured with their Adhesive Remnant Index (ARI). Results: Transbond XT primer (11.22MPa) had a significantly higher immediate SBS than Transbond Plus SEP (5.32MPa), iBOND (6.69MPa) and G-Bond (8.30MPa). 24 hours, Transbond XT primer (16.65MPa) and Transbond Plus SEP (13.20MPa) had a significant increase in their SBS. No difference was observed at 3 months. ARI were significantly different between the groups at all time points. Conclusions: iBOND and G-Bond yielded sufficient SBS’s over the three time points that may be sufficient to withstand occlusal and light archwire forces.
46

The effect of crosshead speed, load cell configuration and curing time on the shear bond strength of orthodontic brackets

Cheba, Vivek 09 August 2012 (has links)
Objective: Evaluate the effect of crosshead speed, load cell configuration and curing time on shear bond strengths. Methods: 160 human molars were divided into equal groups of 20 second and 40 second photopolymerization times and then into 1kN or 10kN load cell groups. Each of the groups were divided into 0.5mm/min or 5mm/min crosshead speeds. Results: Regarding photopolymerization time (20s vs. 40s) and crosshead speeds (0.5mm/min vs. 5.0mm/min) there were no significant differences in SBS (p>0.05). The load cell configuration (1kN vs. 10kN) however showed statistically significant differences (p<0.05) with the 1kN producing higher bond strengths.
47

Composite bond strength of one and two - step adhesive systems used for restorations on primary teeth using varying acid etch application times

Klus, Bradley 19 August 2014 (has links)
The objective of this study was to determine whether the composite bond strength acquired using a single step self-etching bonding system is as or more effective when compared to the two step etch-rinse-bond system at clinically relevant in-vitro standards. A total of 80 extracted human deciduous with at least one intact smooth surface were collected with parental consent. Collected teeth were randomly assigned to one of four treatment protocols (n=20): single step self-etch (Adper Prompt L-Pop, 3M ESPE), two step etch (15s)-rinse-bond (Optibond Solo Plus, Kerr), single step self etch (Adper L Pop, 3M ESPE) with 30s pre-etch, and two step etch (30s)-rinse-bond (Optibond Solo Plus, Kerr). A composite cylinder of uniform shape was bonded to each tooth using the designated adhesive system and specimens were tested with a universal testing machine. Descriptive statistics and statistical analysis was performed. Median shear bond strengths for all specimens, regardless of treatment group, ranged from 3.25 MPa to 43.13 MPa. These values are above suggested minimum clinical required values of 3MPa. A Kruskal-Wallis analysis between treatment groups found statistical significance (p<0.05) for shear bond strength between the groups and both one step system protocols, had higher mean and median shear bond strength values than the two step systems. An adhesive remnant index (ARI) was analyzed to confirm uniform adhesive fracture between all four treatment groups. Both a Fisher’s exact test, and a Hantel-Haenszel statistic found no significant difference (p<0.05) between the samples. Based on these findings we concluded that: 1. The ARI score for all treatment groups was not statistically significant, suggesting that the type of bond breakage was consistent regardless of adhesive system used. 2. Both Optibond Solo Plus and Adper Prompt L-Pop systems achieve adequate shear bond strengths as described by current literature. 3. The use of a one-step system to save chair time and aid in patient behavior management may be clinically useful.
48

Spheno-occipital synchondrosis maturation as related to the development of cervical vertebrae, mandibular canine and chronologic age: A cone-beam computed tomography analysis

Halpern, Richard Michael 15 December 2014 (has links)
To investigate the relationship between maturation of the spheno-occipital synchondrosis (SOS) with cervical vertebrae (CVM), dental development of the canine (DI), chronologic age and intra-rater / inter-rater reliability using retrospective cone-beam computed tomography, seventy-seven subjects were randomly selected into six groups based on age and sex. Spearman correlation coefficients and tabulations between stages of maturation indices were evaluated. SOS maturation was significantly correlated with CVM and age (r > 0.8). A weaker significant correlation coefficient was found between SOS and DI (r > 0.6). All males with fused SOS were in CVM stage 4 or later, while all females were in at least CVM stage 3. No subjects with open SOS were in the post-pubertal growth spurt age group and no subjects with closed SOS were in the pre-pubertal growth spurt age group. SOS maturation showed substantial and significant inter-rater and intra-rater reliability (kappa > 0.7). / February 2015
49

New dental materials

Ogden, Jill January 1993 (has links)
No description available.
50

AWARE-WS:a multipurpose science dashboard

Korhonen, M. (Mikko), Koski, H. (Henri), Visuri, A. (Aku) 24 March 2015 (has links)
AWARE is a mobile instrumentation framework for Android devices that focuses on users, researchers and application developers. In this paper we introduce AWARE’s web services (AWARE-WS), a multipurpose dashboard for science. AWARE-WS allows researchers to manage and interact with longitudinal, largescale and distributed user studies that focus on human behavior. Additionally, developers can manage and share their own plugins or sensors for extending the AWARE framework. AWARE-WS was designed and implemented taking into account AWARE’s secure, private, scalable, and interoperable data exchange requirements and has been thoroughly evaluated for its performance, scalability and usability. We stress-tested AWARE-WS with an increasing amount of generated data streams (e.g., sensor data), from 1000 to 10 Million devices, to improve the overall system’s performance. Using pagination and on-demand data loading, we achieved a reasonable average loading time of 1,9 seconds. / AWARE on mobiili instrumentointikehys Android-laitteille, joka keskittyy sen käyttäjiin, tutkijoihin ja sovelluskehittäjiin. Tässä tekstissä esittelemme AWARE web servicen (AWARE-WS), joka on monikäyttöinen tieteellinen graafinen käyttöliittymä (dashboard). AWARE-WS sallii tutkijoiden hallinnoida pitkä-aikaisia, suurimittaisia ja jaettuja käyttäjätutkimuksia, jotka keskittyvä ihmiskäytökseen. Lisäksi sovelluskehittävät voivat hallinnoida ja jakaa heidän omia liitännäisiään (plugin) ja antureitaan (sensor) jotka laajentavat AWARE:a. AWARE-WS kehitettiin huomioonottaen AWARE:n turvallisuus-, yksityisyys-, laajennettavuus- ja yhteentoimivuusvaatimukset ja on arvioitu sen suorituskyvyn, laajennettavuuden ja käytettävyyden perusteella. Parantaaksemme järjestelmän suorituskykyä, suoritimme rasitustestejä generoimalla sensoridataa, joka vastasi määrältään tuhannesta kymmeneen miljoonan laitteen tuottamaa dataa. Käyttämällä sivutusta ja lataamalla vain tarvittavan datan, saavutimme sivustolle 1,9s keskimääräisen latausajan.

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