SoDM Masters Theses

Comparison of Fracture Behavior among Different One-Stage Implants under Cyclic Loading

Junghoon Yoo — Wed, 02 Mar 2011 11:53:53 PST

Cytotoxicity Evaluation of EndoSequence Bioceramic and GuttaFlow sealers in vitro

Keivan Zoufan — Thu, 02 Dec 2010 06:03:12 PST

Epidemiological Assessment of the Association between Chronic Periodontitis and Psychological Distress/Major Depressive Disorder in General and Renal Populations

Dongha Oh — Wed, 18 Aug 2010 10:26:22 PDT

Periodontal Infections, Inflammatory Markers in Chronic Kidney Disease

Eric Sanjay Choudhury — Wed, 18 Aug 2010 10:22:12 PDT

Effects of Orthodontic Tooth Movement on Osteoblast Differentiation Markers within the Periodontal Ligament

Christopher E. Olson — Wed, 18 Aug 2010 09:39:10 PDT

The Perceived Prognosis of Endodontic Treatment and Implant Therapy Among Dental Practitioners

Rachel Margaret Stockhausen — Thu, 17 Jun 2010 07:19:52 PDT

Little data concerning the perceived success of implant therapy in comparison with endodontic treatment exists. While the criteria used to measure the outcome of each modality are not the same, it is not clear if this is appreciated by practicing dentists. The purpose of the study was to evaluate the perceived outcome of implant therapy in comparison to endodontic treatment. A 23 question Web-based survey was distributed to 648 dentists who matriculated from the University of Connecticut School Of Dental Medicine over the past 30 years. The response rate was 47%. Sixty-seven percent of respondents were general dentists. Forty-nine percent of respondents did not know different criteria exist in the literature and are used to evaluate implant and root canal treatment. Fifty-four percent of dentists felt the prognosis of implant therapy was the same as or better than endodontic treatment of teeth with vital pulps. Thirty percent of responders thought root canal treatment of teeth with necrotic pulp was superior to implants and only 16% thought retreatment was preferable. Treatment planning for implant placement vs. retreatment of a restorable tooth was 46% and 32%, respectively. A third of the respondents felt that the role of endodontics will decline in the future. Dentists’ primary source of information regarding implant therapy was continuing education; however, their primary source of information regarding endodontic treatment was their dental program. Dentists felt the prognosis of implant therapy was as good or superior to endodontic treatment of teeth with vital, necrotic or previously treated pulps.

Effects of Externally Applied, Cyclical, Low Magnitude Forces on Orthodontic Tooth Movement in Rats

Elizabeth Clair Blake — Thu, 17 Jun 2010 05:37:36 PDT

Orthodontic tooth movement requires external orthodontic forces to be converted to cellular signals that result in the coordinated removal of bone on one side of the tooth (compression side) by osteoclasts, and the formation of new bone by osteoblasts on the other side (tension side). The length of orthodontic treatment can take several years, leading to problems of caries, periodontal disease, root resorption, and patient dissatisfaction. It appears that the velocity of tooth movement is largely dependent on the rate of alveolar bone remodeling. Pharmacological approaches to increase the rate of tooth movement are limited due to patient discomfort, severe root resorption, and drug-induced side effects. Recently, externally applied, cyclical, low magnitude forces (CLMF) have been shown to cause an increase in the bone mineral density of long bones, and in the growth of craniofacial structures in a variety of animal models. In addition, CLMF is well tolerated by the patient and produces no known adverse effects. However, its application in orthodontic tooth movement has not been specifically determined. Since factors that increase alveolar bone remodeling enhance the rate of orthodontic tooth movement, we hypothesized that externally applied, cyclical, low magnitude forces (CLMF) will increase the rate of orthodontic tooth movement. In order to test this hypothesis we used an in vivo rat orthodontic tooth movement model. Our specific aims were:

Specific Aim 1: To develop an in vivo rat model for tooth movement.

We developed a tooth movement model based upon two established rodent models (Ren and Yoshimatsu et al, See Figure 1.). The amount of variation of tooth movement in rats exposed to 25-60 g of mesial force activated

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from the first molar to the incisor for 4 weeks was calculated.

Specific Aim 2: To determine the frequency dose response of externally applied, cyclical, low magnitude forces (CLMF) for maximal tooth movement and osteoclast numbers.

Our working hypothesis for this aim was that the amount of tooth movement would be dose dependent on the frequency of application of the CLMF. In order to test this working hypothesis, we varied the frequency of the CLMF from 30, 60, 100, and 200 Hz, 0.4N, two times per week, for 10 minutes for 4 weeks, and measured the amount of tooth movement. We also looked at the number of osteoclasts for the different frequencies; we hypothesized an increase in osteoclasts for the dose respnse of different frequencies.

Specific Aim 3: To determine the effects of externally applied, cyclical, low magnitude forces (CLMF) on PDL proliferation.

Our working hypothesis for this aim was that PDL proliferation would increase with CLMF. In order to test this hypothesis we compared CLMF (30 Hz, 0.4N, two times per week, for 10 minutes for 4 weeks) performed on the left side (experimental side), to the non-CLMF side, on the right (control side).

This was an experimental study with 24 rats in total. The experimental group contained fifteen (15) rats in total, and they all received a spring plus a different frequency of CLMF. Three (3) received a spring and CLMF at 30 Hz, 0.4N for 10 minutes. Six (6) received a spring and CLMF at 60 Hz, 0.4N for 10 minutes. Three (3) received a spring and CLMF at 100 Hz, 0.4N for 10 minutes. Three (3) received a spring and CLMF at 200 Hz, 0.4N for 10 minutes. The control group contained six (6) rats, and received only a spring. An additional

three (3) rats received CLMF (30 Hz, 0.4N, two times per week, for 10 minutes for 4 weeks) only, with no spring, and were used only for histological purposes.

Rats were subjected to the application of orthodontic force from their maxillary left first molar to their left central incisor. In addition some of the rats received externally applied, cyclical, low magnitude force (CLMF) on their maxillary left first molar. micro-CT was used to measure the amount of orthodontic tooth movement. The distance between the maxillary first and second molars, at the most mesial point of the second molar and the most distal point of the first molar (1M-2M distance) were used to evaluate the distance of tooth movement. Immunohistochemistry was performed with TRAP staining and BrdU quantification.

Externally applied, cyclical, low magnitude forces (CLMF) do appear to have an effect on the rate, while not significant, of orthodontic tooth movement in rats. It appears that lower CLMF decreases the rate of tooth movement, while higher CLMF increases the rate of tooth movement. Future studies with larger sample sizes are needed to clarify this issue. CLMF does not appear to affect the proliferation in PDL cells, and has no effect on the number of osteoclasts.

A Dynamic Analysis: the Smile and Display of Dentition during Speech

Allen Yaghoubzadeh — Tue, 16 Mar 2010 08:34:54 PDT

The objective of this retrospective study is to follow up on a previous Dynamic Smile Analysis and videographically analyze and develop averages for soft tissue norms with respect to the display of dentition during speech. These values would then be compared cross-sectionally across different age groups to see whether changes attributable to the aging process could be seen. A secondary objective was to compare averages for soft tissue norms in the display of dentition during speech to averages for soft tissue norms in the display of dentition during the smile. Materials and Method: Records from a previous study in which video equipment was used to capture video for 26 1 subjects were re-evaluated to find appropriate frames to analyze for speech. Two frames for each subject were selected; one frame representing the maximal display of maxillary incisors during speech and the second representing the widest transverse display of dentition during speech. After excluding 40 subjects the data for the remaining 221 subjects was analyzed. These averages were then compared to averages attained in the previous study to compare the display of the dentition during speech to the display of the dentition during smile. Results: On average, a difference in 1.29 mm was seen in the display of the maxillary incisors during speech at maximal display and during the smile. An average of 7.23 mm of maxillary incisors is readily visible during maximum display of maxillary incisors during speech, as compared to 8.52 mm during the smile. The constructed smile index was also smaller when measured during the speech when compared to the smile index by an average of 2.58 units. Conclusion: This study helps to establish age-related dynamic norms for the display of dentition during speech. The dynamic measures indicate that the display of dectition is greater, on average, during the smile than at speech.

Permeability Alterations of Bio-Silicified Treated Human Dentin: an In Vitro Study

Takashi Komabayashi — Thu, 25 Feb 2010 06:57:43 PST

First Order Archwire Deflections: Comparing Conventional, Active Self-Ligating and Passive Self-Ligating Mechanisms

Michael B. Holbert — Tue, 23 Feb 2010 05:55:14 PST

Our aim in this study was to compare conventional, active self-ligating and passive self-ligating mechanisms using first order archwire deflections. A cantilever and three point bend model were used to assess degree of bracket play, deactivation force, and superelastic range. Methods: We studied five different bracket types: victoryTM( 3M-Unitek, St. Paul, MN), smartClipTM( 3M-Unitek, St. Paul, MN), Damon hYTM( ~ rmc oG, lendora, CA), CarriereTM( Ortho Organizers, Carlsbad, CA) and In- Ovation R~~ (GAC Intl., Bohemia, NY). These brackets were tested with round superelastic nickel titanium wires varying in diameter: 0.014", 0.016", 0.018" and 0.020" (Ultimate Wireforms Inc., Bristol, CT). Using a mechanical testing apparatus with custom fixture we recorded the load-deflection curve generated by the deflected archwire over a span of 4mm. The wire was deflected at a rate of 10mmImin and measurements were taken at a rate of 20Hz. Data was compared and analyzed using a single factor ANOVA with the bracket type as the discriminating variable. Group differences were further analyzed using post-hoc T-tests (a = 0.01). Results: Bracket play was significant for both wire diameters (p50.01). The 0.014" wire showed significantly less play with the Victory and In-Ovation R brackets when compared to the passive self ligating brackets (PSLBs). For PSLBs, the Smartclip bracket had significantly less bracket play than the Damon MX and Carriere, which were not significantly different. Both the ligation mechanism and the archwire diameter had a significant effect on deactivation load. Victory and In-Ovation R brackets provided a measurable deactivation load at lmm, while the PSLBs provided no such force with the 0.014" wire. During the cantilever test, PSLBs produced the lowest deactivation forces for all wires tested. The three point bend test showed similar results with small diameter wires. As the degree of deflection and archwire diameter increased, the PSLBs displayed reduced deactivation forces, which are related to significant binding and increased sliding frictional resistance. The superelastic range varied significantly for the various bracket types (p_<0.01). Victory provided the largest superelastic range for all wires except the 0.020". Of the SLBs tested, In-Ovation R displayed the larger superelastic range. The 0.014," test showed a significant difference in superelastic range for all brackets except the Damon MX and Carriere, which were not significantly different from each other. Conclusions: The type of ligation has a significant effect on the degree of bracket play, force of deactivation and superelastic range. These factors influence the clinician's ability to achieve full first-order correction and to maintain light, continuous forces over a wide range of activation. The clinician should consider the degree of correction needed and type of ligation when selecting the appropriate alignment wire.

Effect of Selected Accelerants on pH, Setting Time and Biocompatibility of MTA

Amer Zaal AlAnezi — Thu, 07 Jan 2010 07:55:36 PST

Influence of a Passive Sonic Irrigation System on the Elimination of Bacteria from Root Canal Systems

S. Kirk Huffaker — Wed, 04 Nov 2009 05:45:25 PST

Periodontitis, Inflammatory Markers and Solid Organ Transplant Recipients

Murad Hadi Shaqman — Mon, 02 Nov 2009 08:01:56 PST

The Characterization of Structure and Biologic Activity of Novel Lipids from Porphyromonas endodontalis

Christopher S. Mirucki — Tue, 14 Jul 2009 10:28:22 PDT

Osteoclast Precursors: Regulation by Prostaglandins.

Kiavash Kevin Badii — Thu, 25 Jun 2009 10:13:48 PDT

A Comparison of Absolute Translucency and Relative Translucency of Dental Ceramics

Lisa Spink — Thu, 25 Jun 2009 10:02:12 PDT

Wear Parameters of Zirconia and Titanium at the Implant-Abutment Interface

Michael William Klotz — Thu, 18 Jun 2009 12:43:24 PDT

Characterization of Structural Changes in the Subchondral Bone and Fibrocartilage from a Mouse Model of Temporomandibular Joint Osteoarthritis

Tina Rattan Gupta — Tue, 26 May 2009 07:33:13 PDT

Dynamic Smile Analysis : Changes with Age

Shyam G. Desai — Wed, 04 Feb 2009 04:54:15 PST

Introduction: The objective of this study was to define age-related changes in the human smile. The areas of interest were: upper lip length at smile and repose, upper lip thickness at smile and repose, maxillary incisal display at smile, interlabial gap height at smile, smile index, percent buccal corridors, intercommissural width at rest, smile height, and smile arc. A secondary objective was to study the perioral changes from rest to smile and compare them on the basis of age.

Materials and Method: Video equipment was used to capture video for 261 subjects. Two frames for each subject were selected; one frame representing the lips and rest and the second representing the widest smile. After excluding 40 subjects the data for the remaining 221 subjects was analyzed.

Results: There was a decrease of 1.5 to 2 mm in the maxillary incisor display during smile, with increase in age. Smile index significantly increased with increase in age. Most (78%) subjects displayed an average smile height. No subjects in the 50 and over age group displayed a high smile while no subjects in the 15-19 year old age group presented with a low smile. All the dynamic measures indicated there was a pattern of decreasing change from rest to smile especially evident after the 30-39 year old age group.

Conclusions: This study helps to establish age related dynamic norms. As the person ages the smile gets narrower vertically and wider transversely. The dynamic measures indicate that the muscles' ability to create a smile decreases with increasing age.

Characterization of Chemical and Biological Properties of Purified Porphyromonas gingivalis Free Dihydroceramides

Andrew Robert Chapokas — Mon, 29 Dec 2008 08:04:11 PST

The aim of the present investigation is to purify, characterize, and determine the chemical and biological properties of Porphyromonas gingivalis free dihydroceramides (fDHC). Effects were tested by examination of human gingival fibroblast morphologic changes in addition to their synthesis of prostaglandin E2 (PGE2) and prostaglandin F2α (PGF2&#;) produced in vitro. Free dihydroceramides as well as phosphoglycerol dihydroceramide (PGDHC), and de-esterified phosphoglycerol dihydroceramide (PGDHC-C15:0) were obtained by total lipid extraction of P. gingivalis followed by high performance liquid chromatography (HPLC). Confirmation and structural analysis was obtained by electrospray mass spectrometry (ES-/+MS) and nuclear magnetic resonance spectroscopy (NMR). A synthetic free dihydroceramide (A) was obtained, and its purification and structural analysis was similar. Ethanol solvent served as a negative control, and PGDHC served as a positive control. HGF were obtained from tissue samples of two periodontally healthy volunteers during clinical crown lengthening procedures, and cell cultures were introduced to 35 mm wells previously coated with ethanol or 20&#;g of each lipid/well. Additional experimentation was carried out to investigate fibroblast response to different concentrations of P. gingivalis fDHC. These experiments were carried out in a similar manner except P. gingivalis fDHC were studied at 0.2, 2, and 20 &#;g/35 mm well. After one hour, 30 ng of interleukin-1&#; (IL-1&#;) was added to each sample. After 24 hours, supernatants were harvested and 100 ng of both deuterated prostaglandin E2 (DPGE2) and prostaglandin F2α (DPGF2&#;) were added. Analyses were performed by derivatization of samples followed by gas chromatograph mass spectrometry (GC-MS). HGF synthesis of PGF2α was unaffected for all lipids tested. IL-1&#; mediated HGF synthesis of PGE2 was greater for all treatment groups compared to control; however, statistical significance was only achieved for PGDHC and P. gingivalis fDHC (p < .05). P. gingivalis PGDHC and fDHC treated HGF resulted in similar PGE2 synthesis approximately 1.8 fold compared to ethanol vehicle. Morphologic changes suggestive of HGF atrophy and apoptosis were evident only for PGDHC, and this was noted for the majority of PGDHC experiments. These findings suggest that IL-1&#; mediated HGF secretion of PGE2 can occur even in the absence of a phosphate linkage and 15-carbon isobranched methyl ester, but these structural elements seem to play an important role in the induction of cellular morphological changes observed in phase contrast microscopy.