Dentistry School Theses and Dissertations

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    Bactericidal Efficacy of EdgePRO Er,Cr:YSGG Laser-Activated Irrigation Against a Mature Endodontic Multispecies Biofilm Using an in vitro Infected Tooth Model
    (2024) Patterson, Samuel B.; Spolnik, Kenneth J.; Gregory, Richard; Ehrlich, Ygal; Movila, Alexandru
    Introduction: Treatment goals of non-surgical root canal therapy (nsRCT) include the removal of all organic tissue material, bacterial biofilm and their by-products, and debris materials, in order to disinfect the canal system to a level compatible with healing and to further prevent infection. Standard chemo-mechanical protocols have several well-documented shortcomings and subsequent areas for improvement regarding their disinfection abilities. In recent years, emerging laser technology and its application in root canal therapy has been gaining popularity as a safe and promising tool for advancing endodontic treatment. The newest FDA-approved laser for endodontic application is the EdgePRO Erbium,Chromium-doped:Yttrium-Scandium-Gallium-Garnet (Er,Cr:YSGG) infrared laser operating at a 2780 nm wavelength. Previous in vitro studies using Er,Cr:YSGG lasers have demonstrated their ability to enhanced canal debridement, cleaning, smear layer removal, and bacterial disinfection. Additionally, a few in vivo trails have been completed using this laser type as an adjunct in RCT procedures, which have yielded safe and highly successful results in the clinical setting. However, research specifically using the EdgePro device as well as a standardized protocol for optimal clinical usage of the laser is lacking. Objectives: The aim of this study was to evaluate the bactericidal and biofilm dissolution effects of laser-activated irrigation using the EdgePro laser against a mature multispecies biofilm in an infected tooth model and to assess the potential increased disinfection and cleaning ability compared to a standard needle irrigation protocol. Materials and Methods: Single rooted teeth (n=36) were decoronated to a standardized length of 16mm. The root canals were endodontically prepared using a standard irrigation, hand-filing, and rotary protocol to a final size of ISO 25.06 while maintaining a fully patent apical foramen. An irrigation solution reservoir was created in the coronal 4 mm of the canal space. Sterile specimens were inoculated with multispecies bacterial sample containing E. faecalis. The mixed bacteria was grown anaerobically for 10 days to form a mature biofilm using a previously established protocol. The teeth were divided into a negative control group (saline rinse, n=12), positive control group (standard needle irrigation – SNI, n=12), and an experimental group (laser-assisted treatment protocol, n=12). The positive control and experimental laser groups utilized the same irrigation solutions of 2 mL 17% EDTA followed by 5 mL 3% NaOCl using a standard 27-gauge side-vented irrigation needle placed as far apically as possible without binding. The experimental group underwent additional laser activation using laser tip #2 (350 m diameter) and settings of: 15 mJ, 0.75 W, 50 Hz, 0% air, and 0% water spray (Mid-Root Solutions 1 preset). The laser tip was inserted halfway into the irrigation filled canals (8 mm from orifice and apex) and fired upon withdrawal at a speed of 0.8 mm/sec, which comprised a single lasing cycle of 10 seconds. Three lasing cycles were completed with EDTA first followed by NaOCl, for a total of six lasing cycles with 60 seconds of irradiation time per tooth. A final rinse of sterile saline was used in all tooth samples prior to bacterial sample collection via Versa-brushes and sterile paper points. The samples were transferred to a laboratory setting where they underwent ultrasonic agitation, serial dilution, spiral plating on blood-agar, and two days of anaerobic incubation for assessment of bacterial growth. Colony forming units (CFUs/mL) were counted as a means of quantitative analysis. Results: The negative control group yielded the highest level of bacterial growth with an average of 934,771 CFUs/mL. The positive control group displayed a statistically significant lower amount of bacterial growth with an average of 4,698 CFUs/mL and yielded 1 sample with no bacterial growth. The experimental laser group had statistically significant lower bacterial growth present compared to both the positive and negative control groups and produced all negative bacterial samples with none of the 12 agar plates demonstrating CFU growth and averaged 0 CFUs/mL.. Conclusion: Within the scope of this study, laser-activated irrigation (LAI) using the EdgePro Er,Cr:YSGG laser was capable of producing no detectable bacterial samples in an in vitro infected tooth model. EdgePro LAI displayed statistically significant superior cleaning and disinfection of infected canal space compared to teeth treated with standard needle irrigation alone. The EdgePro laser system indeed shows promise as an adjunctive tool in clinical root canal treatment procedures. Further investigation is warranted using similar protocols in teeth with more complicated anatomy and with supplemental methods for analyzing bactericidal potential.
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    Effectiveness of GentleWave CleanFlow on Multispecies Endodontic Biofilm Removal in Single Rooted Extracted Teeth
    (2024-06) Beswick, Adam J.; Spolnik, Kenneth J.; Movila, Alexandru; Gregory, Richard L.; Ehrlich, Ygal
    Introduction: One of the challenges of non-surgical root canal treatment is disinfection. Bacterial biofilms adhere to canal walls and invade the intricate anatomy present within root canal systems. Traditional irrigation methods are unable to deliver irrigation solutions to all parts of the canal system. The GentleWave system is an advanced irrigation method designed to improve irrigation and disinfection, ultimately leading to more successful root canal outcomes. Objective: The aim of this study is to evaluate the GentleWave CleanFlow posterior instrument’s ability to remove a multispecies biofilm from a single canaled extracted tooth compared to traditional irrigation techniques. Materials and Methods: Thirty-six single rooted premolar teeth with single canals were prepared to a uniform size, instrumented to size 25.06 and inoculated with a multispecies bacterial biofilm taken from an adult tooth with pulpal necrosis. Teeth were incubated and biofilm established before teeth were disinfected. Three disinfection groups included: GentleWave irrigation using the Posterior CleanFlow Procedure Instrument on the necrotic tooth cycle, standard needle irrigation with 2.5% NaOCl and 8% EDTA, and needle irrigation with sterile water. Following treatment, canals were swabbed and plated on blood agar plates and incubated for 48 hours when colony forming units were counted. Results: Both GW and standard needle irrigation demonstrated significantly lower CFU/mL than the negative control (p<0.001). However, the GW and positive control groups were not significantly different from one another (p=0.132). Conclusion: The findings of this study suggest that the GentleWave Posterior CleanFlow procedure instrument does not exhibit improved biofilm removal compared to standard needle irrigation. However, based on mixed results when comparing this study to previous GentleWave biofilm removal studies, it is clear that more research is necessary. Future studies should considering using a multispecies biofilm, the GentleWave CleanFlow procedure instrument and multiple techniques to assess biofilm removal.
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    The Effect of Bonded Orthodontic Appliances on Salivary Mutans Streptococci and on Immunoglobulin A Antibody to S. Mutans
    (1997) Wittler, Michelle L.; Gregory, Richard L.; Switalski, Lech M.; Miller, Chris H.; Garetto, Lawrence P.; Shanks, James C.
    The placement of fixed orthodontic appliances creates a number of new retention sites in the oral cavity, which subsequently leads to an increase in the number of cariogenic bacteria, including Streptococcus mutans, during active orthodontic treatment. We hypothesize that the increased prevalence of S. mutans in the saliva of orthodontic patients provides an antigenic challenge to the mucosal immune system, which leads to an elevation of secretory IgA (sIgA) antibodies to S. mutans in saliva. The purpose of this study was to evaluate the change in numbers of salivary mutans streptococci and the concentration of parotid sIgA antibody to S. mutans with the placement of bonded orthodontic appliances. A randomly selected group of 19 patients requiring the placement of orthodontic appliances was tested in this study. Whole and parotid saliva samples were collected three times prior to bonding and four times during bonded appliance therapy over a 30-week period. Whole saliva samples were spiral plated on mitis salivarius sucrose agar and mitis salivarius sucrose bacitracin agar in order to quantify total oral streptococci and mutans streptococci, respectively. Parotid saliva was assayed for IgA antibody to S. mutans using an established ELISA technique. The results demonstrated a significant (p < 0.05) increase in total oral streptococci and mutans streptococci numbers after six months of orthodontic treatment when compared with the baseline values. The level of sIgA to the clinical isolates of S. mutans was also significantly higher six months after the cementation of orthodontic appliances. These elevated numbers of mutans streptococci elicited a mucosa! immune response, which corresponded with a higher concentration of sIgA to S. mutans in the saliva. There was a significant negative correlation (R = -0.22; p = 0.02) between the numbers of mutans streptococci and sIgA antibody levels to the clinical isolates of S. mutans. When the sIgA antibody levels were elevated the numbers of mutans streptococci were lower. These data suggest that sIgA antibody to S. mutans may be a protective mechanism against an elevated level of mutans streptococci caused by the placement of orthodontic appliances. If the mucosal immune response to S. mutans could be enhanced before bonding orthodontic appliances, this could prevent some of the demineralization found adjacent to bands and brackets.
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    Displacement of Anchorage in Controlled Root Movement at Various Force Values
    (1970) Winkler, Robert A.; Cunningham, Donald; Garner, LaForrest; Mitchel, David; Norman, Richard; Shanks, Jim
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    A Study of the Physical Properties of Latex as Related to Orthodontic Tooth Movement
    (1971) Vornholt, John William
    Latex elastics have long been used in orthodontics, and force decay has always been a disadvantage. Reports differ on the load-deflection properties of rubber. Decay in elastic bands has ranged from 8% to 74.9%, depending on test conditions. A study was designed to ascertain (1) whether better quality controls would minimize decay and give better reproducibility in force from one elastic band to the next; and (2) whether the amount of stretch to which the elastic body is subjected affects the rate of decay. The quality control testing consisted of selecting elastic bands of identical size, shape, and color. This was followed by testing each one with a 100 gram weight and separating out all elastics which tested out to a given length. This test-controlled sample was then used to study the physical properties of latex. A load-deflection study was performed from this test-controlled sample, and revealed a curvilinear relationship. From the load-deflection curve, four force values were chosen which would represent 1) minimal stretching in the elastic deformation range, 2) maximal stretching in the elastic deformation range, 3) minimal stretching in the permanent deformation range, and 4) maximal stretching in the permanent deformation range. In the decay phase of the study, four more groups of elastics from the test-controlled sample were loaded with the four force values previously mentioned. The force was then measured after one and 12 hours and after one, seven, 14 and 21 days. Thus the decay of force could be calculated for each group over a three-week period. The results showed that more rigid quality control does produce a more predictable decay rate and force. The load-deflection properties of latex elastic were shown to be curvilinear, and the decay rate was affected by the amount of stretch to which the elastic body was subjected. However, if the elastic was stretched within the elastic deformation range, the decay rate remained the same regardless of the length of stretch. Therefore, it is recommended that the clinician use latex elastic in the elastic deformation range and thereby reduce the decay rate.
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    Curing Front Shape and Velocity in Cylindrical Bulk-Filled Light-Cured Resin Composite
    (2001) Wright, Chad M.; Katona, Thomas R.; Baldwin, James J.; Shanks, James C.; Chen, Jie; Moore, B. Keith
    Clinical failures of resin composite dental restorations are common phenomena. Such failures occur in part because of the polymerization shrinkage inherent to methacrylate-based materials. Numerous efforts have been attempted to reduce the deleterious effects of polymerization shrinkage. Despite such efforts, it appears that no simple solution to the problem exists. To effectively improve bonding methods, more information must be known about the polymerization process itself. By using the Finite Element Method (FEM), an accurate computer simulation model of the polymerization process may be created. Such a model may allow researchers to test the effects of alternative restorative and bonding techniques without actual in vitro experiments. To create an accurate computer model, much information about the transient events present during the curing process has yet to be obtained. In this non-clinical, data-gathering study, we: 1) verified that the shape of the curing front within a light-cured resin composite model is indeed convex, 2) determined that the curing front shape changes with depth of cure, and 3) measured the velocity of the curing front as it relates to curing light distance. Each of these observations and measurements has yielded information vital to the subsequent development of a resin composite polymerization model. It is anticipated that necessary data regarding other variables or aspects of the polymerization process will be obtained in subsequent research projects.
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    An Analysis of the Fatigue Resistance of Beta Titanium and the Effect of Spot-Welding Upon the Fatigue Resistance of this Alloy
    (1984) Wong, Michael B.; Garner, LaForrest; Baldwin, James; Moore, Keith; Barton, Paul; Shanks, James
    This investigation was designed to establish a fatigue curve for beta titanium, determine the effect of spot-welding upon the fatigue resistance of this alloy, and provide qualitative observations about surface characteristics of different batches of TMA in relation to their fatigue lives. Rectangular .016" x .022" 1MA was evaluated. Twelve specimens in each group were tested, making the total sample size 108. The wire samples were evaluated using a cantilever bend test in which specimens were stressed cyclically at varying deflections. Two welded groups were also tested. An auxiliary .016" x .022" TMA was welded to a main test segment of TMA with the .016" side against the opposing .016" side. The weld overlap varied at 25% for one group and 50% for the other. These specimens were stressed at the area adjacent to the weld. One specimen from each group was viewed under the scanning electron microscope to evaluate the fractured area. Specimens from three different batches of 1MA were tested and their fatigue lives compared at .625 inch deflection. One specimen from each batch was viewed under the scanning electron microscope to evaluate its surface structure. A fatigue curve for TMA was plotted from the data. At .625 inch deflection, welding an auxiliary onto the main segment significantly decreased the fatigue resistance of the wire. However, both welded groups had comparable fatigue lives. These wire specimens fractured at some point adjacent to the welded site. Fatigue resistance differed significantly between one batch of TMA and the other two. The scanning electron micrographs of representative specimens from each batch seemed to indicate that the fatigue resistance of each batch was inversely related to its surface roughness.
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    Digital Microradiography: In Vitro Validation of a Novel Imaging Technique
    (2004) Yip, Gary Ka Fai; Roberts, W. Eugene; Everett, Eric; Garetto, Lawrence P.; Hancock, E. Brady; Kowolik, Michael J.; Parks, Edwin T.; Platt, Jeffrey A.; Zunt, Susan L.
    Microradiography has been widely used in mineralized tissue research in determining the mineral content within the specimens being studied. There are considerable limitations of this ageing gold standard such as unavailability of the high-resolution spectroscopic plates and prolonged imaging and processing times. The present study aimed at developing and validating a novel digital microradiographic technique that is not restricted by the limitations of conventional microradiography. Reproducibility of digital microradiography was investigated by studying 4 repeated images of 10 randomly selected sectioned implant-bone specimens acquired by 2 examiners over 2 weeks. The acquired images were analyzed by both manual and automated digital subtractions. Correlation between digital and conventional microradiography was performed by digital subtraction of 23 matching images acquired by both microradiographic techniques. A comparison between manual and automated digital subtraction enabled evaluation of the influence of the digital subtraction protocols on the results of the subtraction. A direct digital microradiographic technique has been developed which does not require analogue recording medium and film processing. The robustness of the digital microradiography was evidenced by the narrow range of means and standard deviations for intra- and inter-examiner reproducibility. The intra-examiner means and standard deviations ranged from 126.54-128.42 and 4.11-5.34 respectively. The inter-examiner means and standard deviations ranged from 126.71-129.87 and 4.68-5.70 respectively. The detection threshold for the digital microradiography was 5 gray scales or 3.9 percent, which was comparable to digital radiography. The high concordance between conventional and digital microradiography was demonstrated by the mean and standard deviation of 8.69 and 1.75 gray scales respectively. There was a statistically significant difference between the results obtained by manual and automated digital subtraction, but the clinical significance is yet to be determined.
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    An Assessment of Malocclusion in Caucasian Eighth Graders in the Indianapolis Public School System
    (1979) Sputh, Frederick L.
    An investigation was conducted to determine the quantitative incidence and severity of malocclusion in a sample of 455 Caucasian eighth grade students in Indianapolis. The following data were collected on each student: race, sex, age, dental I.Q., zip code, right and left molar relationship, crossbite, slides, dental age, overbite, overjet, missing permanent teeth and caries. Statistically, the data were compiled and compared using percentage, mean, range and chi square, yielding the following results. Approximately 85% of the children had some form of malocclusion: 39.3% Class I, 36.5% Class II and 8.7% Class III. Bilateral crossbites occurred in 4.3% of the sample while 17.6% showed unilateral crossbite and 78.0% no crossbite. The mean chronological age was 14 years and 1 month and 88.8% had lost all primary molars. Missing permanent teeth were found in 9.7% of the sample. The mean carious teeth per pupil was .582. The mean overjet was 2.63 mm while the mean overbite was 3.73 mm. No differences related to sex were found in any of the above results.
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    Tensile Bond Strength of Stainless Steel Orthodontic Brackets on Microabraded Teeth
    (1997) Wentz, Holly Diane; Sanders, Brian J.; Avery, David R.; Katona, Thomas R.; Moore, B. Keith; Shanks, James C.
    Microabrasion with PREMA Compound (Premier Dental Product Co., King of Prussia, Penn.) has been advocated for the removal of superficial enamel stains. This procedure eliminates stains by removing a microscopic layer of enamel. The objective of this study was to determine whether the use of PREMA microabrasion prior to orthodontic bonding affects the tensile bond strength of an adhesive precoated stainless steel orthodontic bracket. Sixty noncarious extracted human premolar teeth were randomly divided into three groups of 20 and stored in 3-percent buffered formalin solution. Group I was a control group that was etched and bonded in the usual manner. Group II received PREMA Compound microabrasion immediately prior to bonding. Group III received PREMA microabrasion followed by a six-week storage period prior to bonding. After bonding, specimens were thermocycled and stored in distilled water at 37 °C for 14 days. The specimens were then loaded to failure in the tensile mode of an Instron testing machine (Instron Corp., Canton, Mass.). A ·stress-breaking apparatus was utilized to minimize all forces other than tensile. The data was statistically analyzed using one-way analysis of variance at the 0.05 level. No statistically significant differences were found among the three groups. From these results it was concluded that microabrasion with PREMA did not affect bond strength. Enamel microabrasion can be provided prior to orthodontic treatment without any detriment to bracket bond strength.