2005 Scientific Abstracts 11-22
2005 Scientific Abstracts
Numbers 11-22
11. New Biological Functions of Human Serum IgA1, Implications in Periodontal Disease
Quang L. Nguyen, College of Dental Medicine, Medical University of South Carolina
Problem: In periodontal disease, IgG1 and IgA1 antibodies produced in situ co-deposit on periodontopathic bacteria, yet complement-mediated clearance of antigens by combinations of the antibodies is unknown. Objective: To determine complement-mediated function for human serum IgA, which co-deposit alongside human IgG. Methods: Dansylated human albumin was immobilized as antigen in ELISA. Increasing doses of IgA1 with constant amounts of IgG1 were added to the immobilized antigens. In comparison, doses of myeloma IgA1 were directly co-deposited onto microtiter plates with a constant dose of myeloma IgG1. In these experiments, 33% human serum was applied for 30 minutes at 37oC. Complement deposition (C4b, C3b) and IgA1, IgG1 deposition were quantified. Results: It was observed that C4b and C3b deposited directly on the antigenic surface and onto the Fc-region of antigen-bound IgA1 antibodies causing the complement-coated IgA1 antibodies to depart. These fluid-phase complement-coated IgA1 antibodies were easily transferred to antigen-coated microtiter plates, where they became bound to the non-complement-coated antigens. Thus, the complement-coated IgA1 antibodies retained their antigen-binding function, as a proportion of their Fc-bound C3b progressively degraded to iC3b and C3d. In this way, IgA1 antibodies extended the efficiency of the complement system by insuring the specific IgA1 antibody-mediated transport of their captured biologically active complement fragments to those antigens stimulating the IgA1 antibody response but not yet neutralized with complement. Use of genetically engineered carbohydrate-deficient mutant human IgA1 antibodies indicated that the carbohydrate on the Fc-region of IgA1 played a positive role. In addition, when IgA1 was co-deposited with IgG1 antibodies, and serum complement was added, the IgG1 antibodies tended to remain bound to the antigenic surface. In summary, co-deposited IgA1 antibodies maximized the efficiency of the complement system, transported their covalently bound complement fragments to specific antigens and sustained the effective deployment of IgG1 antibodies directed to those same antigens.
Quang L. Nguyen, College of Dental Medicine, Medical University of South Carolina
Problem: In periodontal disease, IgG1 and IgA1 antibodies produced in situ co-deposit on periodontopathic bacteria, yet complement-mediated clearance of antigens by combinations of the antibodies is unknown. Objective: To determine complement-mediated function for human serum IgA, which co-deposit alongside human IgG. Methods: Dansylated human albumin was immobilized as antigen in ELISA. Increasing doses of IgA1 with constant amounts of IgG1 were added to the immobilized antigens. In comparison, doses of myeloma IgA1 were directly co-deposited onto microtiter plates with a constant dose of myeloma IgG1. In these experiments, 33% human serum was applied for 30 minutes at 37oC. Complement deposition (C4b, C3b) and IgA1, IgG1 deposition were quantified. Results: It was observed that C4b and C3b deposited directly on the antigenic surface and onto the Fc-region of antigen-bound IgA1 antibodies causing the complement-coated IgA1 antibodies to depart. These fluid-phase complement-coated IgA1 antibodies were easily transferred to antigen-coated microtiter plates, where they became bound to the non-complement-coated antigens. Thus, the complement-coated IgA1 antibodies retained their antigen-binding function, as a proportion of their Fc-bound C3b progressively degraded to iC3b and C3d. In this way, IgA1 antibodies extended the efficiency of the complement system by insuring the specific IgA1 antibody-mediated transport of their captured biologically active complement fragments to those antigens stimulating the IgA1 antibody response but not yet neutralized with complement. Use of genetically engineered carbohydrate-deficient mutant human IgA1 antibodies indicated that the carbohydrate on the Fc-region of IgA1 played a positive role. In addition, when IgA1 was co-deposited with IgG1 antibodies, and serum complement was added, the IgG1 antibodies tended to remain bound to the antigenic surface. In summary, co-deposited IgA1 antibodies maximized the efficiency of the complement system, transported their covalently bound complement fragments to specific antigens and sustained the effective deployment of IgG1 antibodies directed to those same antigens.
12. Protective Effect of HDL Against LDL Oxidation
K. STEELE*, P. MARMILLOT, and M. LAKSHMAN (Veterans Affairs Medical Center, Washington DC, USA)
Objectives: This research is being conducted to determine if alcohol and/or atherogenic diet alter the protective effect of HDL against LDL oxidation. Method: Three groups of six C57BL/6 mice each were fed for nine weeks the following diets: 1) no alcohol/normal diet, 2) no alcohol/atherogenic diet, 3) alcohol/atherogenic diet. Mouse plasma HDL fraction was prepared by precipitating out VLDL and LDL with heparin/MnCl2. LDL was prepared by sequential flotation from pooled plasma. We monitored the kinetics of LDL oxidation by CuSO4 in the presence of HDL by measuring the increase of absorbance at 234 nm over a period of 5 hours. Increase of absorbance over time is due to the occurrence of diene bonds caused by lipid peroxidation. The extent of LDL oxidation was quantified by calculating the lag time and the slope of the expansion phase from the kinetics curve. Results: HDLs from all groups of mice showed LDL oxidation protection properties, as indicated by increased lag time and decreased expansion phase slope, compared to LDL oxidation without HDL. However, we found no significant distinction between the data obtained from all groups of mice. Conclusion: Although atherogenic diet is associated with increased plaque accumulation and alcohol is associated with its decrease, this experiment did not show the correlation between these agents and the protective effect of HDL against LDL oxidation. Because we could not observe the inhibition of HDL protection property by atherogenic diet or promotion of HDL protection property by alcohol, we conclude that nine weeks of feeding with the corresponding diet was not long enough for plaque accumulation in this batch of mice. This study was supported by Howard University and George Washington University.
K. STEELE*, P. MARMILLOT, and M. LAKSHMAN (Veterans Affairs Medical Center, Washington DC, USA)
Objectives: This research is being conducted to determine if alcohol and/or atherogenic diet alter the protective effect of HDL against LDL oxidation. Method: Three groups of six C57BL/6 mice each were fed for nine weeks the following diets: 1) no alcohol/normal diet, 2) no alcohol/atherogenic diet, 3) alcohol/atherogenic diet. Mouse plasma HDL fraction was prepared by precipitating out VLDL and LDL with heparin/MnCl2. LDL was prepared by sequential flotation from pooled plasma. We monitored the kinetics of LDL oxidation by CuSO4 in the presence of HDL by measuring the increase of absorbance at 234 nm over a period of 5 hours. Increase of absorbance over time is due to the occurrence of diene bonds caused by lipid peroxidation. The extent of LDL oxidation was quantified by calculating the lag time and the slope of the expansion phase from the kinetics curve. Results: HDLs from all groups of mice showed LDL oxidation protection properties, as indicated by increased lag time and decreased expansion phase slope, compared to LDL oxidation without HDL. However, we found no significant distinction between the data obtained from all groups of mice. Conclusion: Although atherogenic diet is associated with increased plaque accumulation and alcohol is associated with its decrease, this experiment did not show the correlation between these agents and the protective effect of HDL against LDL oxidation. Because we could not observe the inhibition of HDL protection property by atherogenic diet or promotion of HDL protection property by alcohol, we conclude that nine weeks of feeding with the corresponding diet was not long enough for plaque accumulation in this batch of mice. This study was supported by Howard University and George Washington University.
13. Axenfeld-Rieger Syndrome: Involvement of PITX2A and LEF-1 Protein Interactions
L. TREVINO* 1andB. AMENDT 2 ( 1Univ. of Texas HSC-Dental, Houston, TX USA; 2Texas A&M IBT, Houston, TX, USA).
Mutations in PITX2, a homeobox gene, were first cloned from Axenfeld-Rieger Syndrome (ARS) patients. These patients present clinically with anomalies of epithelial derived organs, including teeth. PITX2 is needed, along with b-catenin and lymphoid enhancer factor, LEF-1, for the induction of the above epithelial derived organs. It is known that PITX2A, an isoform of PITX2, activates the LEF-1 promoter to express LEF-1, and that LEF-1 and PITX2A synergistically interact through the PITX2A C-terminus to activate the promoter. To determine whether the HMG box domain of LEF-1 was involved in this synergism, we measured the activation of the promoter using different mutants. Expression plasmid preparations of PITX2A, LEF-1, PITX2A ΔT1261, and LEF-1 ΔC HMG were used to transfect Chinese Hamster Ovary (CHO) cells via electroporation. Transfection was accomplished using different combinations of the plasmids, including cotransfection with the LEF-1luciferase reporter construct and SV-40 β-galactosidase as a transfection efficiency control. Empty plasmid vector, MycHisC, was used as a control. The findings show that a PITX2A C-terminus deletion mutant (PITX2 DT1261) loses synergistic activation with LEF-1 for the LEF-1promoter. This mutant protein has a reading frame change in the distal 3' end of the C-terminal tail. Thus, this region of PITX2 is required for its interaction with LEF-1. We also found that a HMG box nucleotide substitution mutant of LEF-1 does not affect the synergism with PITX2A. Hence we conclude that the HMG box of LEF-1 is not involved in the interaction with PITX2A for synergistic activation of the LEF-1promoter, and that ARS developmental defects can be attributed to defective PITX2 protein interactions. This study was supported by NIH T32-DE015355.
L. TREVINO* 1andB. AMENDT 2 ( 1Univ. of Texas HSC-Dental, Houston, TX USA; 2Texas A&M IBT, Houston, TX, USA).
Mutations in PITX2, a homeobox gene, were first cloned from Axenfeld-Rieger Syndrome (ARS) patients. These patients present clinically with anomalies of epithelial derived organs, including teeth. PITX2 is needed, along with b-catenin and lymphoid enhancer factor, LEF-1, for the induction of the above epithelial derived organs. It is known that PITX2A, an isoform of PITX2, activates the LEF-1 promoter to express LEF-1, and that LEF-1 and PITX2A synergistically interact through the PITX2A C-terminus to activate the promoter. To determine whether the HMG box domain of LEF-1 was involved in this synergism, we measured the activation of the promoter using different mutants. Expression plasmid preparations of PITX2A, LEF-1, PITX2A ΔT1261, and LEF-1 ΔC HMG were used to transfect Chinese Hamster Ovary (CHO) cells via electroporation. Transfection was accomplished using different combinations of the plasmids, including cotransfection with the LEF-1luciferase reporter construct and SV-40 β-galactosidase as a transfection efficiency control. Empty plasmid vector, MycHisC, was used as a control. The findings show that a PITX2A C-terminus deletion mutant (PITX2 DT1261) loses synergistic activation with LEF-1 for the LEF-1promoter. This mutant protein has a reading frame change in the distal 3' end of the C-terminal tail. Thus, this region of PITX2 is required for its interaction with LEF-1. We also found that a HMG box nucleotide substitution mutant of LEF-1 does not affect the synergism with PITX2A. Hence we conclude that the HMG box of LEF-1 is not involved in the interaction with PITX2A for synergistic activation of the LEF-1promoter, and that ARS developmental defects can be attributed to defective PITX2 protein interactions. This study was supported by NIH T32-DE015355.
14. A randomized clinical trial to evaluate the efficacy of physical therapy and interocclusal appliances for the management of myofascial pain.
Tejeda, F. B.S.*Gonzalez, Y. DDS, MS. Tejeda, C. B.S, M.A. and Dunford, R. M.S. State University of New York at Buffalo Department of Oral Diagnostic Sciences
Myofascial pain is characterized by a regional, dull, aching muscle pain with the presence of localized tender sites in muscle, tendon or fascia. It has been suggested that the use of conservative therapies may result in better pain control and increase function, but clinical trials have not evaluated the effectiveness of the proposed treatment modalities. Objective: The purpose of this study is to evaluate the short term effectiveness of physical therapy (spray and stretch), interocclusal appliances and the combination of both for the management of myofascial pain. Methods: A double blind randomized clinical design was used in order to evaluate the change in pain, interference and range of motion. Subjects were evaluated for TMD by a calibrated examiner using the specifications of the RDC/TMDs. Subjects were randomly assigned to one of the three arms and received weekly interventions a for five weeks; all measurements were taken at baseline and after completed the assigned treatment. A trained clinician provided all the treatments. Results: A total of 23 subjects were enrolled at baseline and 91% of them adhered to the study protocol. 75% of the subjects were female and the mean age was 44 (±16) y.o. The treatment arms were (A) flat interocclusal full coverage appliance (B) physical therapy and (C) a combination of both. Using a one sample t-test the difference in the overall sample pre and post treatment are as follows:(see chart)
Tejeda, F. B.S.*Gonzalez, Y. DDS, MS. Tejeda, C. B.S, M.A. and Dunford, R. M.S. State University of New York at Buffalo Department of Oral Diagnostic Sciences
Myofascial pain is characterized by a regional, dull, aching muscle pain with the presence of localized tender sites in muscle, tendon or fascia. It has been suggested that the use of conservative therapies may result in better pain control and increase function, but clinical trials have not evaluated the effectiveness of the proposed treatment modalities. Objective: The purpose of this study is to evaluate the short term effectiveness of physical therapy (spray and stretch), interocclusal appliances and the combination of both for the management of myofascial pain. Methods: A double blind randomized clinical design was used in order to evaluate the change in pain, interference and range of motion. Subjects were evaluated for TMD by a calibrated examiner using the specifications of the RDC/TMDs. Subjects were randomly assigned to one of the three arms and received weekly interventions a for five weeks; all measurements were taken at baseline and after completed the assigned treatment. A trained clinician provided all the treatments. Results: A total of 23 subjects were enrolled at baseline and 91% of them adhered to the study protocol. 75% of the subjects were female and the mean age was 44 (±16) y.o. The treatment arms were (A) flat interocclusal full coverage appliance (B) physical therapy and (C) a combination of both. Using a one sample t-test the difference in the overall sample pre and post treatment are as follows:(see chart)
No statistical significance differences among the groups were found even though there was a trend towards the combined therapy group. Based on the observed values for the variables of interest power calculation show the need of 129(43 per arm) subjects in order to achieve an 80% power. Conclusion:This study shows that pain reduction and increase function can be obtained by non invasive conservative therapy. Key Words: TMDs, Myofascial Pain, Treatment, Physical Therapy, Interocclusal Appliance.
|
Variables |
Pre |
Post |
Test-Statistic |
P-Value |
|
Pain(VAS) |
3.09 |
2.0 |
3.87 |
0.001 |
|
Interference (VAS) |
2.1 |
1.34 |
3.03 |
0.007 |
|
PFO(mm) |
35.52 |
38.57 |
18.66 |
0.000 |
|
MUO(mm) |
43.90 |
45.29 |
28.31 |
0.000 |
|
MAO(mm) |
46.71 |
48.24 |
29.82 |
0.000 |
|
Tempralis
(% Pain) |
76% |
47% |
3.80 |
0.051 |
|
Massette
(% pain) |
62% |
29% |
0.62 |
0.421 |
2005 Hispanic Dental Association/Dentsply/SCADA Student Research Award Winner
15. Cultural Adaptation of the Research Diagnostic Criteria/TMD in the Hispanic Community
Miranda Y. DMD*,Gonzalez Y. DDS, MS. and Dunford R. MS. State University of New York at Buffalo, Department of Oral Diagnostic Sciences, Department of Periodontics and Endodontics
The assessment of Temporomandibular Disorders (TMDs) has not been done yet in the Hispanic population due to the need of an instrument in the native language that can be used in this population. Objective:The primary aim of this study was to perform the cultural adaptation and validation of the Spanish version of the original instrument of the Research Diagnostic Criteria (RDC) for TMDs among bilingual speakers. Methods:A single-group bilingual design was used in order to evaluate the item percentage of agreement across language. A total of 17 bilingual subjects participated in this study. They were randomly assigned to an English-Spanish and Spanish-English cross design. The mean age was 37 ±12 y/o. 35% of the participants were females with a mean of 17 ±1.5 years of education. All subjects were of Hispanic origin: 35% Puerto Rican, 18% Mexican-American, 36% other Latin American and 12% Spaniards. Results:A total of 76 items were evaluated and 9 items from the Spanish version of the RDC/TMDs did not achieve an 85% agreement with its English counterpart. From these, seven items were from the pain-related disability and psychological status; and two from the history questionnaire specifically the self report of oral health status and oral health self care. Most of the disagreements were confounded with the order in which the instruments were administered, specifically in the Spanish/ English group. Conclusions:The high percent agreement of the items demonstrates that the Spanish version is linguistically and statistically equivalent in both languages and therefore, valid to be use for the assessment of TMDs among Spanish speakers. Further investigation of the items that have low agreement must be conducted in order to determine if the variation in responses was due to the lack of understanding of the translated/adapted words or if in fact was due to the interpretation of the concept within a particular culture.
Miranda Y. DMD*,Gonzalez Y. DDS, MS. and Dunford R. MS. State University of New York at Buffalo, Department of Oral Diagnostic Sciences, Department of Periodontics and Endodontics
The assessment of Temporomandibular Disorders (TMDs) has not been done yet in the Hispanic population due to the need of an instrument in the native language that can be used in this population. Objective:The primary aim of this study was to perform the cultural adaptation and validation of the Spanish version of the original instrument of the Research Diagnostic Criteria (RDC) for TMDs among bilingual speakers. Methods:A single-group bilingual design was used in order to evaluate the item percentage of agreement across language. A total of 17 bilingual subjects participated in this study. They were randomly assigned to an English-Spanish and Spanish-English cross design. The mean age was 37 ±12 y/o. 35% of the participants were females with a mean of 17 ±1.5 years of education. All subjects were of Hispanic origin: 35% Puerto Rican, 18% Mexican-American, 36% other Latin American and 12% Spaniards. Results:A total of 76 items were evaluated and 9 items from the Spanish version of the RDC/TMDs did not achieve an 85% agreement with its English counterpart. From these, seven items were from the pain-related disability and psychological status; and two from the history questionnaire specifically the self report of oral health status and oral health self care. Most of the disagreements were confounded with the order in which the instruments were administered, specifically in the Spanish/ English group. Conclusions:The high percent agreement of the items demonstrates that the Spanish version is linguistically and statistically equivalent in both languages and therefore, valid to be use for the assessment of TMDs among Spanish speakers. Further investigation of the items that have low agreement must be conducted in order to determine if the variation in responses was due to the lack of understanding of the translated/adapted words or if in fact was due to the interpretation of the concept within a particular culture.
16. SEM Study of Effects of Beverages on Margins of Restorations
P. JAIN,and H.R.HUDSON, Southern Illinois University, Alton, USA
Objective: To evaluate morphological changes in enamel and dentin margins and surfaces of restorations, following exposure to 3 soft drinks, milk and water using scanning electron microscopy. Methods: Class V preparations (n=33) were cut on extracted premolars. These were restored with Tytin amalgam (sds Kerr, Orange, CA), Point 4 composite resin (sds Kerr, Orange, CA)or Fuji II LC glass ionomer (GC Corp., Japan). Half of each restoration, including 1 mm of the enamel and dentin margins was covered with sticky wax. Two samples from each group were cyclically exposed to either Coca Cola, Fanta, Mountain Dew, 2% milk or tap water. Exposure cycles consisted of a 15 minute immersion in the beverage followed by 2 hours in artificial saliva. This cycle was repeated 4 times a day for 5 days. A sample from each group was etched with 37.5% phosphoric acid for 15 seconds to provide a positive control. Sticky wax was removed before samples were viewed and photographed under the SEM. Changes at the exposed and unexposed halves of each restoration and its enamel and dentin margins were evaluated and ranked. Results: Kruskal-Wallis test followed by Wilcoxon signed-rank test showed that enamel margins were significantly affected by Coca Cola, Mountain Dew and Fanta (p<0.05), in that order. Dentin margins were most affected by Mountain Dew followed by Coca Cola and Fanta (p<0.05). Coca Cola and Mountain Dew etched all enamel and dentin margins respectively to the same degree as phosphoric acid. Milk and water had no detectable effect on enamel margins. Milk removed the smear layer from all dentin margins. The beverages had no detectable effect on restorative material surfaces. Conclusions: Coca Cola, Mountain Dew and Fanta etch enamel and dentin margins of amalgam, composite resin and glass ionomer restorations significantly (p<0.05), after a 5 day simulated exposure.
P. JAIN,and H.R.HUDSON, Southern Illinois University, Alton, USA
Objective: To evaluate morphological changes in enamel and dentin margins and surfaces of restorations, following exposure to 3 soft drinks, milk and water using scanning electron microscopy. Methods: Class V preparations (n=33) were cut on extracted premolars. These were restored with Tytin amalgam (sds Kerr, Orange, CA), Point 4 composite resin (sds Kerr, Orange, CA)or Fuji II LC glass ionomer (GC Corp., Japan). Half of each restoration, including 1 mm of the enamel and dentin margins was covered with sticky wax. Two samples from each group were cyclically exposed to either Coca Cola, Fanta, Mountain Dew, 2% milk or tap water. Exposure cycles consisted of a 15 minute immersion in the beverage followed by 2 hours in artificial saliva. This cycle was repeated 4 times a day for 5 days. A sample from each group was etched with 37.5% phosphoric acid for 15 seconds to provide a positive control. Sticky wax was removed before samples were viewed and photographed under the SEM. Changes at the exposed and unexposed halves of each restoration and its enamel and dentin margins were evaluated and ranked. Results: Kruskal-Wallis test followed by Wilcoxon signed-rank test showed that enamel margins were significantly affected by Coca Cola, Mountain Dew and Fanta (p<0.05), in that order. Dentin margins were most affected by Mountain Dew followed by Coca Cola and Fanta (p<0.05). Coca Cola and Mountain Dew etched all enamel and dentin margins respectively to the same degree as phosphoric acid. Milk and water had no detectable effect on enamel margins. Milk removed the smear layer from all dentin margins. The beverages had no detectable effect on restorative material surfaces. Conclusions: Coca Cola, Mountain Dew and Fanta etch enamel and dentin margins of amalgam, composite resin and glass ionomer restorations significantly (p<0.05), after a 5 day simulated exposure.
17. University of Kentucky Saturday Morning Clinic Parent Survey Analysis
L. Suzanne Parham, University of Kentucky College of Dentistry, Dr. Juan Yepes, DDS, MD, Dr. DavidNash, DMD, MS, EdD
Introduction The University of Kentucky College of Dentistry has had the wonderful opportunity to provide a free clinic for underprivileged children ages 12 and under of the Lexington/Fayette county area for over 25 years. The clinic specifically targets those children who do not qualify for Medicaid and cannot afford private dental insurance.
Objective To identify the characteristics of the children being treated at the University of Kentucky Saturday Morning Clinic.
Materials and Methods A two page survey was given to parents of children attending the clinic during three clinic sessions held in the spring of 2005. Each parent was asked to complete one survey per child attending the clinic.
Data Analysis 38 surveys were completed and returned during the three clinic sessions. Of these, 22 were for Hispanic children and of those 22, 6 speak only Spanish and 2 can speak both English and Spanish.
L. Suzanne Parham, University of Kentucky College of Dentistry, Dr. Juan Yepes, DDS, MD, Dr. DavidNash, DMD, MS, EdD
Introduction The University of Kentucky College of Dentistry has had the wonderful opportunity to provide a free clinic for underprivileged children ages 12 and under of the Lexington/Fayette county area for over 25 years. The clinic specifically targets those children who do not qualify for Medicaid and cannot afford private dental insurance.
Objective To identify the characteristics of the children being treated at the University of Kentucky Saturday Morning Clinic.
Materials and Methods A two page survey was given to parents of children attending the clinic during three clinic sessions held in the spring of 2005. Each parent was asked to complete one survey per child attending the clinic.
Data Analysis 38 surveys were completed and returned during the three clinic sessions. Of these, 22 were for Hispanic children and of those 22, 6 speak only Spanish and 2 can speak both English and Spanish.
Conclusions The number of Hispanic children seen at the Saturday Morning Clinics seems quite large in comparison to the total number of children treated. However the clinic was designed to target the underprivileged population of children in the Lexington/Fayette county area and as is seen by the population studies, this population is growing at a very high rte. Due to the government regulations placed on these immigrants, our clinic is the family's only source of dental care for their children.
18. Association of Periodontal Disease History and Parkinson’s and Alzheimer’s Conditions
G. GATA, G. NAVARRETE, L. LOPEZ, A. ELIAS, C. BUXO, University of Puerto Rico, San Juan, USA
Exposure to mercury from dental amalgam has been related to changes in memory, motor-visual and neurobehavioral changes, renal and neurological disorders. Objective:The purpose of this case-control study is to explore the association between mercury exposure from dental amalgam and Parkinson's and Alzheimer's diseases in people 50 years and older. Methods: A sample of 108 male and female volunteers were selected and divided into cases (Parkinson's and Alzheimer's) and controls (without neurological disorders) selected from the same source. Participants signed consents approved by IRB and questionnaire was administered before oral examination. The questionnaire consists of four sections to eliminate confounders like other exposure sources to mercury different from dental amalgam. Trained examiners using the NIDCR diagnostic criteria performed oral examinations blinded for neurological disorders. Mean decayed, missing, and filled component of the DMFS Index were calculated by participant and group using ANOVA analysis of variance. Results: In the present study, no statistical association was observed between dental amalgams and neurological disorders (p=0.92). Statistically significant associations with neurological disorders were found for mean decayed surfaces, DMFS, and tooth loss due to periodontal disease (p<0.05). Significant association between periodontal disease and neurological disorders (OR=28.8) was observed; Alzheimer's (p=0.00) and a clinical tendency for Parkinson's (OR= 7.43 and p=0.10). Conclusion: Tooth loss findings from periodontal disease or caries agree with the reported leading causes of tooth loss in older adults. The association between periodontal disease and neurological disorders are relevant for the prevention and control of neurological disorders in the projected increase in population of older adults.
G. GATA, G. NAVARRETE, L. LOPEZ, A. ELIAS, C. BUXO, University of Puerto Rico, San Juan, USA
Exposure to mercury from dental amalgam has been related to changes in memory, motor-visual and neurobehavioral changes, renal and neurological disorders. Objective:The purpose of this case-control study is to explore the association between mercury exposure from dental amalgam and Parkinson's and Alzheimer's diseases in people 50 years and older. Methods: A sample of 108 male and female volunteers were selected and divided into cases (Parkinson's and Alzheimer's) and controls (without neurological disorders) selected from the same source. Participants signed consents approved by IRB and questionnaire was administered before oral examination. The questionnaire consists of four sections to eliminate confounders like other exposure sources to mercury different from dental amalgam. Trained examiners using the NIDCR diagnostic criteria performed oral examinations blinded for neurological disorders. Mean decayed, missing, and filled component of the DMFS Index were calculated by participant and group using ANOVA analysis of variance. Results: In the present study, no statistical association was observed between dental amalgams and neurological disorders (p=0.92). Statistically significant associations with neurological disorders were found for mean decayed surfaces, DMFS, and tooth loss due to periodontal disease (p<0.05). Significant association between periodontal disease and neurological disorders (OR=28.8) was observed; Alzheimer's (p=0.00) and a clinical tendency for Parkinson's (OR= 7.43 and p=0.10). Conclusion: Tooth loss findings from periodontal disease or caries agree with the reported leading causes of tooth loss in older adults. The association between periodontal disease and neurological disorders are relevant for the prevention and control of neurological disorders in the projected increase in population of older adults.
19. Radiographic Findings Associated with Renal Failure Patients – a Retrospective Study
C. CANALES*, D. KARAKI, and S. MAKHIJA w(UAB School of Dentistry, Birmingham, AL, USA)
The UAB Hospital in Birmingham performs over 300 kidney transplants each year. Protocols for patient evaluation include dental examination for pre-transplant candidates. The renal transplant patient is particularly vulnerable to onset of dental infections and other adverse oral conditions that can complicate recovery from transplant surgery. The purpose of this research was to find a correlation of significant dental radiographic findings common among patients with end-stage renal failure progressing to transplant surgery. This retrospective study focused on determining common features in patients slated for renal transplants. Examiners reviewed 153 pre-transplant evaluation panographs and 152 panographs of patients without end stage renal disease (control group). Five examiners reviewed each panograph to ascertain presence or absence of the following features in the mandible: anterior teeth; posterior teeth; radiographic caries evidence; alveolar bony crest height; periapical radiolucencies/ radiopacities; and bone entity radiolucencies/ radiopacities. All examiners were blinded to patient history and identity. Analysis of variance and logistic regression were used to determine if there was a difference between the two groups (end-stage renal failure patients vs control group) and between the gold standard and other examiner’s results. Kappa was used to measure the agreement between the evaluations of the examiners. Agreement between examiners was significant for missing anterior and posterior teeth. Renal patients were found to be 2.75 times more likely to have missing posterior teeth, 1.79 times more likely to have missing anterior teeth (not statistically significant), and 1.11 times more likely to have bone entity radiolucencies (not statistically significant) than non-renal. A significant correlation of missing posterior teeth was found among patients with end-stage renal failure. |This study was supported by NIH grant T35 HL-07473).
C. CANALES*, D. KARAKI, and S. MAKHIJA w(UAB School of Dentistry, Birmingham, AL, USA)
The UAB Hospital in Birmingham performs over 300 kidney transplants each year. Protocols for patient evaluation include dental examination for pre-transplant candidates. The renal transplant patient is particularly vulnerable to onset of dental infections and other adverse oral conditions that can complicate recovery from transplant surgery. The purpose of this research was to find a correlation of significant dental radiographic findings common among patients with end-stage renal failure progressing to transplant surgery. This retrospective study focused on determining common features in patients slated for renal transplants. Examiners reviewed 153 pre-transplant evaluation panographs and 152 panographs of patients without end stage renal disease (control group). Five examiners reviewed each panograph to ascertain presence or absence of the following features in the mandible: anterior teeth; posterior teeth; radiographic caries evidence; alveolar bony crest height; periapical radiolucencies/ radiopacities; and bone entity radiolucencies/ radiopacities. All examiners were blinded to patient history and identity. Analysis of variance and logistic regression were used to determine if there was a difference between the two groups (end-stage renal failure patients vs control group) and between the gold standard and other examiner’s results. Kappa was used to measure the agreement between the evaluations of the examiners. Agreement between examiners was significant for missing anterior and posterior teeth. Renal patients were found to be 2.75 times more likely to have missing posterior teeth, 1.79 times more likely to have missing anterior teeth (not statistically significant), and 1.11 times more likely to have bone entity radiolucencies (not statistically significant) than non-renal. A significant correlation of missing posterior teeth was found among patients with end-stage renal failure. |This study was supported by NIH grant T35 HL-07473).
20. A Novel Approach to Increase the Efficacy of Anti-Tumor Therapies
F.R. Urzua*, P. Kumar*, R.J. Benedict*, P.J. Polverini**
*Department of Biological and Material Sciences, **Oral Medicine, Pathology, and Oncology, University of Michigan School of Dentistry
Objectives: Radiotherapy is widely used in cancer treatment. However, treatment failures often result, due to the development of radio-resistant tumor cells and endothelial cells. We have previously shown that endothelial cells are protected against radiation via activation of the phosphoinositide-3-kinase (PI3K) - Akt - Bcl-2 survival pathway. We therefore hypothesize that a combination treatment consisting of low doses of PI3K inhibitor (LY294002), cisplatin and radiation could significantly enhance the therapeutic efficacy of traditional therapies, while dramatically decreasing untoward side effects associated with the maximum tolerated doses of these anti-tumor agents. Methods: In vivo SCID Mouse Model –Human dermal microvascular endothelial cells (HDMEC 9x105) and oral squamous cell carcinoma cells (OSCC-3 1x105) were mixed with Matrigel (100µl) and injected into the hind limbs of SCID mice. Additionally, two PLG-scaffolds (HDMEC+VEGF) were implanted in the dorsal region (subcutaneously). The animals were then treated (14 days) with LY294002, cisplatin, and irradiation, either alone or in combination. Tumors and scaffolds were then removed, weighed, and measured. The samples were fixed (10%-phosphate-buffered-formalin) overnight and paraffin embedded. The tumor cells undergoing apoptosis were analyzed by in situ TUNEL staining. Immunolocalization of blood vessels – Human blood vessels in the tumors and scaffolds were immunostained using anti-human Von Wiillebrand factor and anti-human CD31 antibodies. The stained micro-vessels were counted blindly in random fields at 200x. Metamorph software was used to quantify vessel area in all samples. Results: Combination treatment significantly inhibited tumor growth in vivo (>90%), and showed significantly higher tumor cell death than those treated with single therapies. The combination treatment also significantly inhibited tumor angiogenesis (>90%), while it had significantly less effect on physiological angiogenesis (<30%). Conclusion: The combination of low doses of LY294002 and cisplatin significantly enhanced the therapeutic efficacy of radiation therapy by targeting tumor blood vessels. These results suggest a novel approach to increase the therapeutic efficacy of current anticancer therapies while decreasing negative side effects. Acknowledgments: This work was supported by NIH Grant DE13161(P.J.P)
F.R. Urzua*, P. Kumar*, R.J. Benedict*, P.J. Polverini**
*Department of Biological and Material Sciences, **Oral Medicine, Pathology, and Oncology, University of Michigan School of Dentistry
Objectives: Radiotherapy is widely used in cancer treatment. However, treatment failures often result, due to the development of radio-resistant tumor cells and endothelial cells. We have previously shown that endothelial cells are protected against radiation via activation of the phosphoinositide-3-kinase (PI3K) - Akt - Bcl-2 survival pathway. We therefore hypothesize that a combination treatment consisting of low doses of PI3K inhibitor (LY294002), cisplatin and radiation could significantly enhance the therapeutic efficacy of traditional therapies, while dramatically decreasing untoward side effects associated with the maximum tolerated doses of these anti-tumor agents. Methods: In vivo SCID Mouse Model –Human dermal microvascular endothelial cells (HDMEC 9x105) and oral squamous cell carcinoma cells (OSCC-3 1x105) were mixed with Matrigel (100µl) and injected into the hind limbs of SCID mice. Additionally, two PLG-scaffolds (HDMEC+VEGF) were implanted in the dorsal region (subcutaneously). The animals were then treated (14 days) with LY294002, cisplatin, and irradiation, either alone or in combination. Tumors and scaffolds were then removed, weighed, and measured. The samples were fixed (10%-phosphate-buffered-formalin) overnight and paraffin embedded. The tumor cells undergoing apoptosis were analyzed by in situ TUNEL staining. Immunolocalization of blood vessels – Human blood vessels in the tumors and scaffolds were immunostained using anti-human Von Wiillebrand factor and anti-human CD31 antibodies. The stained micro-vessels were counted blindly in random fields at 200x. Metamorph software was used to quantify vessel area in all samples. Results: Combination treatment significantly inhibited tumor growth in vivo (>90%), and showed significantly higher tumor cell death than those treated with single therapies. The combination treatment also significantly inhibited tumor angiogenesis (>90%), while it had significantly less effect on physiological angiogenesis (<30%). Conclusion: The combination of low doses of LY294002 and cisplatin significantly enhanced the therapeutic efficacy of radiation therapy by targeting tumor blood vessels. These results suggest a novel approach to increase the therapeutic efficacy of current anticancer therapies while decreasing negative side effects. Acknowledgments: This work was supported by NIH Grant DE13161(P.J.P)
21. Mechanisms for Increased Mechanical Properties of Low Shrinkage Dimethacrylate Resins
Edward J. Gonzalez,1,* N Satsangi,1 BK Norling,1 ST Wellinghoff,2 BR Furman,1 D. Hanson,2 R. Gonzalez III,1 HR Rawls.1
1 University of Texas Health Science Center of San Antonio and 2 Southwest Research Institute, San Antonio, TX.
Liquid-Crystal (LC) diacrylates have cure shrinkages of ~2-4 vol% but also low modulus (E´) and flexure strength (FS). Several comonomers increase E´ and FS with little increase in shrinkage (IADR abst. 1473, 2005).
Objective: Investigate the mechanism(s) involved.
Hypothesis: Comonomers, cured with low-shrinkage dimethacrylates (LSM), increase modulus and strength by increasing crosslinking or suppressing the rate of increase in glass-transition temperature (Tg) such that conversion (DC) proceeds higher, prior to solidification when Tg exceeds ambient.
Methods: Resins were formulated with conventional (3:2:3w/w Bis-GMA, TEGDMA, Bis-EMA, “GTE”) and experimental low-shrinkage (1,4(di-4-(methacryloxyhexyloxy)-benzoyloxy)-2-t-butylbenzene) monomers. Four groups were compared in which 10% comonomer (plasticizing-IBM or crosslinking-TMPTMA) and type of resin (conventional or LSM) were compared for DC, E´, FS, cure-shrinkage and Tg. DC vs exposure was determined by FTIR. Beams 2x2x25mm were cured to maximum DC (Jeneric-Pentron light oven) and stressed in 3-point bending (MTS-Instron 1125). The broken halves were scanned in a dynamic mechanical analyzer (Perkin Elmer, DMA-7). Tg was taken from the tan δ peak. Shrinkage was measured with a density-gradient column.
Results: IBM and TMPTMA both increased E´ and FS of GTE and LSM, with little effect on shrinkage (8.0-8.4 vol%, GTE; 4-5.7 vol%, LSM). IBM suppressed cure rate of GTE and LSM, while TMPTMA increased rate in GTE but suppressed it in LSM. In GTE, Tg was unchanged by IBM and depressed by TMPTMA, while in LSM both IBM and TMPTMA increased Tg. Overall, both comonomers increase E´ and FS in LSM to exceed GTE with half the shrinkage (p<0.05).
Conclusions: Both plasticizing and crosslinking enhance mechanical properties of the low-shrinkage dimethacrylates without affecting shrinkage, due to increased conversion prior to gelation, primarily through plasticizing effects that reduce the rate of increase in Tg in the developing crosslinked network while maintaining a high level of free volume.Funding: NIH P01-DE11688 and UTHSCSA-Hispanic Center Of Excellence- Dentistry
Edward J. Gonzalez,1,* N Satsangi,1 BK Norling,1 ST Wellinghoff,2 BR Furman,1 D. Hanson,2 R. Gonzalez III,1 HR Rawls.1
1 University of Texas Health Science Center of San Antonio and 2 Southwest Research Institute, San Antonio, TX.
Liquid-Crystal (LC) diacrylates have cure shrinkages of ~2-4 vol% but also low modulus (E´) and flexure strength (FS). Several comonomers increase E´ and FS with little increase in shrinkage (IADR abst. 1473, 2005).
Objective: Investigate the mechanism(s) involved.
Hypothesis: Comonomers, cured with low-shrinkage dimethacrylates (LSM), increase modulus and strength by increasing crosslinking or suppressing the rate of increase in glass-transition temperature (Tg) such that conversion (DC) proceeds higher, prior to solidification when Tg exceeds ambient.
Methods: Resins were formulated with conventional (3:2:3w/w Bis-GMA, TEGDMA, Bis-EMA, “GTE”) and experimental low-shrinkage (1,4(di-4-(methacryloxyhexyloxy)-benzoyloxy)-2-t-butylbenzene) monomers. Four groups were compared in which 10% comonomer (plasticizing-IBM or crosslinking-TMPTMA) and type of resin (conventional or LSM) were compared for DC, E´, FS, cure-shrinkage and Tg. DC vs exposure was determined by FTIR. Beams 2x2x25mm were cured to maximum DC (Jeneric-Pentron light oven) and stressed in 3-point bending (MTS-Instron 1125). The broken halves were scanned in a dynamic mechanical analyzer (Perkin Elmer, DMA-7). Tg was taken from the tan δ peak. Shrinkage was measured with a density-gradient column.
Results: IBM and TMPTMA both increased E´ and FS of GTE and LSM, with little effect on shrinkage (8.0-8.4 vol%, GTE; 4-5.7 vol%, LSM). IBM suppressed cure rate of GTE and LSM, while TMPTMA increased rate in GTE but suppressed it in LSM. In GTE, Tg was unchanged by IBM and depressed by TMPTMA, while in LSM both IBM and TMPTMA increased Tg. Overall, both comonomers increase E´ and FS in LSM to exceed GTE with half the shrinkage (p<0.05).
Conclusions: Both plasticizing and crosslinking enhance mechanical properties of the low-shrinkage dimethacrylates without affecting shrinkage, due to increased conversion prior to gelation, primarily through plasticizing effects that reduce the rate of increase in Tg in the developing crosslinked network while maintaining a high level of free volume.Funding: NIH P01-DE11688 and UTHSCSA-Hispanic Center Of Excellence- Dentistry
22. Effect of Crosslinking and Plasticizing Comonomers on Low- and High-Shrinkage Resins
R. Gonzalez III,* N. Satsangi, B.R. Furman, B.K. Norling, E.J. Gonzalez, B.A. Shirley, S.N. Percy, H. Ralph Rawls
University of Texas Health Science Center at San Antonio
Objective: Investigate the effect of plasticizing or crosslinking comonomers on the mechanical properties and cure shrinkage of a low-shrinkage liquid crystal-like (LC) resin. Hypothesis: modulus (E') and flexure strength (FS) of low shrinkage LC-like dimethacrylate (LCM) monomers can be increased with minimal increase in shrinkage by either increasing crosslink density and/or by plasticizing the developing crosslinked structure. Methods: trimethylolpropane trimethacrylate (TMPTMA, Mw 338, a crosslinker) and Isobornyl methacrylate (IBM, Mw 222, a plasticizer) were formulated with a conventional (Bis-GMA based, “GTE”) monomer blend and an experimental LCM (2001 IADR abst. 119). Double bond conversion was determined as a function of exposure time using FTIR techniques. Cure shrinkage, FS and E' were determined at maximum degree of conversion, DC, using conventional methods. Results: The rate of conversion of LCM was retarded by both comonomers while rate for GTE was retarded by IBM but accelerated by TMPTMA. IBM and TMPTMA each increased E’ and FS (p<0.01) for both LCM and GTE with little or no effect on cure shrinkage. However, IBM had the greater effect on LCM while TMPTMA had the greater effect on GTE. Addition of 10% IBM produced the best balance of properties with both GTE and LCM. LCM+10% IBM had superior E’ (2062±69MPa), FS (79±6 MPa), DC at 60s (50%) and shrinkage (4.1 vol%) compared to GTE alone or GTE with 10% of either IBM or TMPTMA (p<0.05). All GTE formulations had ~8 vol% shrinkage.
Conclusions: Flexure strength and modulus can be increased with both crosslinking (TMPTMA) and plasticizing (IBM) monomers. This is most likely due to increasing the proportion of reactive groups that are converted prior to gelation and solidification. IBM enhances mechanical properties while maintaining low shrinkage through a plasticizing effect that lowers the glass transition temperature, Tg, of the monomer blend.
Funding from NIDCR T32-DE14318 and P01-DE11688 are gratefully acknowledged.
R. Gonzalez III,* N. Satsangi, B.R. Furman, B.K. Norling, E.J. Gonzalez, B.A. Shirley, S.N. Percy, H. Ralph Rawls
University of Texas Health Science Center at San Antonio
Objective: Investigate the effect of plasticizing or crosslinking comonomers on the mechanical properties and cure shrinkage of a low-shrinkage liquid crystal-like (LC) resin. Hypothesis: modulus (E') and flexure strength (FS) of low shrinkage LC-like dimethacrylate (LCM) monomers can be increased with minimal increase in shrinkage by either increasing crosslink density and/or by plasticizing the developing crosslinked structure. Methods: trimethylolpropane trimethacrylate (TMPTMA, Mw 338, a crosslinker) and Isobornyl methacrylate (IBM, Mw 222, a plasticizer) were formulated with a conventional (Bis-GMA based, “GTE”) monomer blend and an experimental LCM (2001 IADR abst. 119). Double bond conversion was determined as a function of exposure time using FTIR techniques. Cure shrinkage, FS and E' were determined at maximum degree of conversion, DC, using conventional methods. Results: The rate of conversion of LCM was retarded by both comonomers while rate for GTE was retarded by IBM but accelerated by TMPTMA. IBM and TMPTMA each increased E’ and FS (p<0.01) for both LCM and GTE with little or no effect on cure shrinkage. However, IBM had the greater effect on LCM while TMPTMA had the greater effect on GTE. Addition of 10% IBM produced the best balance of properties with both GTE and LCM. LCM+10% IBM had superior E’ (2062±69MPa), FS (79±6 MPa), DC at 60s (50%) and shrinkage (4.1 vol%) compared to GTE alone or GTE with 10% of either IBM or TMPTMA (p<0.05). All GTE formulations had ~8 vol% shrinkage.
Conclusions: Flexure strength and modulus can be increased with both crosslinking (TMPTMA) and plasticizing (IBM) monomers. This is most likely due to increasing the proportion of reactive groups that are converted prior to gelation and solidification. IBM enhances mechanical properties while maintaining low shrinkage through a plasticizing effect that lowers the glass transition temperature, Tg, of the monomer blend.
Funding from NIDCR T32-DE14318 and P01-DE11688 are gratefully acknowledged.