Determination of Caries Lesion Activity: Reflection and Roughness for Characterization of Caries Progression

Used by permission. © Operative Dentistry, Inc. Transmission or reproduction of protected items beyond that allowed by fair use requires the written permission of Operative Dentistry, Inc.Caries lesion progression is difficult to determine with visual and tactile examinations. The hypothesis of this study was that reflection and roughness measurements could determine caries progression. Ground/polished sound human enamel specimens were analyzed at baseline (sound) and after two four-day demineralization periods for reflection using optical reflectometry (ORef) and for roughness using optical surface profilometry (SPro). Specimens were demineralized using a microbial–Streptococcus mutans aries model. Comparisons among the periods for ORef and SPro were performed using repeated measures analysis of variance. Two-sample t-tests were used for differences in transverse microradiography. The integrated mineral loss and depth of the four-day demineralization period were significantly smaller than those for the eight-day demineralization period (p<0.01). With increased demineralization time, reflection was significantly decreased and roughness was significantly increased (p<0.01). Correlation between ORef and SPro was moderate (r=−0.63). Both reflection and roughness can be characterized for nondestructive longitudinal assessment of caries lesion progression

A study of the evaporation of organic liquids and mixtures of organic liquids

The purpose of this thesis is to make a study of the evaporation of organic solvents. The relative rates of evaporation of the single substances and binary and ternary mixtures are to be considered. A study of the changes in composition of binary and ternary mixtures that occur on evaporation are to be made. Information on the evaporation of organic liquids is important in relation to lacquers, and for that reason the solvents used in this work are liquids commonly used in making lacquers --Introduction, page 2

Preliminary Performance of the Advanced Dental Admission Test (ADAT): Association Between ADAT Scores and Other Variables for Applicants to Residency Programs at a U.S. Dental School

Historically, dental residency programs have used numerical assessment criteria to evaluate and identify qualified candidates for admission. Recent elimination of such assessment tools has undermined many programs’ holistic evaluation process. The Advanced Dental Admission Test (ADAT) was developed and recently piloted in hopes of addressing this issue. The aim of this study was to evaluate the preliminary performance and validity of the ADAT by exploring the association between ADAT scores and other variables for a sample of applicants to residency programs. The WebAdMIT admissions database was used to identify the test scores and educational and demographic information of 92 individuals who completed the pilot ADAT and were seeking a 2017 postgraduate specialty position at Indiana University School of Dentistry. The results showed that the ADAT had strong to weak correlations with certain applicant variables (p<0.05). No significant differences were found for age, race, school location, or country of origin. However, males performed better than females (p<0.05), and non-Hispanics performed better than Hispanics (p<0.01). ADAT component scores were also higher for individuals with a history of research activity (p<0.05). This study found that significant associations existed between the ADAT and indices typically associated with competitive applicants. These findings suggest that the ADAT may serve as a useful numerical assessment instrument, with the potential to identify high-performing candidates. Furthermore, the ADAT seemed to be a plausible option for programs seeking to incorporate a quantitative assessment instrument as part of a holistic candidate selection process

A CLINICAL AND HISTOMORPHOMETRIC STUDY OF CALCIUM SULFATE (DENTOGEN®), COMPARED TO FREEZE DRIED BONE ALLOGRAFT (FDBA) FOR ALVEOLAR RIDGE PRESERVATION

poster abstractThere is significant ridge resorption following tooth extraction. Freeze dried bone allograft (FDBA) is most widely used for ridge preservation and calcium sulfate has begun to show popularity. The objective of this study is to evaluate if DentoGen® (calcium sulfate) is as effective in preserving post extraction ridge dimensions compared to FDBA. Thirty consecutive single rooted extraction sites were selected that met the inclusion criteria for the study. Post extraction clinical measurements were made with a pre-fabricated stent and dental calipers. The sites were then divided randomly into the test group (calcium sulfate) or the control group (FDBA). Patients were recalled after 3 months, sites were reentered and clinical measurements were again made. A trephine bone core was harvested and sent for histomorphometric analysis. A total of 21 subjects with 41 potential sites were recruited to this study (IRB approval # 1003-56). Following extraction, 29 sites met the inclusion criteria. To date, no significant change in vertical ridge height pre to post surgery was noted within the test and control groups (0.53 + 1.63mm, 0.35 ± 1.13mm, respectively). There was a significant decrease in buccal-lingual ridge width within both groups, (-1.23 + 1.14mm test group. 0.93 + 0.94mm control group) There was no significant difference in the preservation performance between the two treatment groups for both ridge width and vertical height. Histological samples are currently being analyzed. Results suggest no statically significant differences between the use of calcium sulfate versus FDBA in preserving post extraction ridge dimensions

Comparative Effectiveness of Structural versus Regulatory Protein Gene Transfer on Articular Chondrocyte Matrix Gene Expression

OBJECTIVE: The production of extracellular matrix is a necessary component of articular cartilage repair. Gene transfer is a promising method to improve matrix biosynthesis by articular chondrocytes. Gene transfer may employ transgenes encoding regulatory factors that stimulate the production of matrix proteins, or may employ transgenes that encode the proteins themselves. The objective of this study was to determine which of these 2 approaches would be the better choice for further development. We compared these 2 approaches using the transgenes encoding the structural matrix proteins, aggrecan or type II collagen, and the transgene encoding the anabolic factor, insulin-like growth factor I (IGF-I). METHODS: We transfected adult bovine articular chondrocytes with constructs encoding type II collagen, aggrecan, or IGF-I, and measured the expression of type II collagen ( COL2A1) and aggrecan ( ACAN) from their native genes and from their transgenes. RESULTS: IGF-I gene ( IGF1) transfer increased the expression of the native chondrocyte COL2A1 and ACAN genes 2.4 and 2.9 times control, respectively. COL2A1 gene transfer did not significantly increase COL2A1 transcripts, even when the transgene included the genomic COL2A1 regulatory sequences stimulated by chondrogenic growth factors. In contrast, ACAN gene transfer increased ACAN transcripts up to 3.4 times control levels. IGF1, but not ACAN, gene transfer increased aggrecan protein production. CONCLUSION: Taken together, these results suggest that the type II collagen and aggrecan production required for articular cartilage repair will be more effectively achieved by genes that encode anabolic regulatory factors than by genes that encode the matrix molecules themselves

EVALUATION OF MICROTENSILE BOND STRENGTH AND MICROLEAKAGE OF A ONE-STEP SELF-ETCH ADHESIVE

poster abstractNew dental glue (G-aenial Bond-GB) was developed to increase the strength of bonding the white tooth filling to the tooth. An extra roughening step of the tooth surface using a specific acid should help the flow of the glue to the tooth and increases the strength of the bond between the tooth and the filling. Therefore, this study was done to evaluate how strong the bond is between the filling and the tooth using GB, and how much GB leaks and compare both tests with two other glue products and, with and without adding an extra roughening step. For the bond strength test, human molars teeth were divided into 5 groups, each containing 15 teeth. In 3 groups, each glue type was applied on tooth dentin according to company's instructions. In the last 2 groups an extra roughening step using a specific acid was added before applying the glue. The samples were stored in fake saliva where four samples were soaked for 48h and four samples were placed in a machine (thermocycling) that resembles drinking hot and cold beverages where samples are exposed to hot and cold water for 40 days and then the strength of the bond was tested (α=0.05). The broken edges were examined using a light microscope. For the leak test, human molars were divided randomly into the same 5 groups as bond strength test but each containing 11 teeth. A cavity was pre-pared and filled on the check and tongue sides of the tooth. Teeth were then also subjected to thermocylcling and stored for four weeks, soaked in dye for 24 hours and sectioned. The dye penetration was evaluated using light mi-croscopy (α=0.05). Bond strength of GB was significantly higher when an acid roughening step was added. No significant difference in leak of GB was observed