Abstracts

Table Clinic Winners

Dental Student Winners

Comparison of Post and Core systems on Widely-flared Root Canals

Sam Kim, Caroline Le, Dan Nguyen, Junior Dental Students; Douglass B. Roberts, DDS, MS, Faculty Advisor, Loma Linda University School of Dentistry, Loma Linda, California.

Purpose: This study examined four methods of restoring anterior teeth with widely flared root canals.

Significance: Research has been conducted on post and core systems for parallel-sided anterior root canals. However, there remains a need for more research on reliable post and core systems for anterior teeth with widely-flared root canals.

Methods and Materials: Four groups plus a control group of ten maxillary central incisors each were prepared with different post and core systems as follows:

Group A: Cast Post/Core
Group B: Composite Post/Core
Group C: Steel Post (1mm diameter)/Composite Core
Group D: Carbon Fiber Post (1.4 mm diameter)/Composite Core
Group E: Control: Crown Restoration Only (no endo)

Root canal treatment was performed on all teeth ( except Group E) with gutta percha filling the apical 3mm. A cylindrical post space, 2mm in length and 1mm in diameter, was then prepared coronal to the gutta percha. The incisal 6mm of the root canal was flared until a rim of dentin 0.5mm in thickness remained. The post and core restorations were then constructed. The cores, including a 2mm ferrule, were prepared for gold crown placement. Crowns were fabricated with a lingual notch 8mm incisal to the gingival margin and were luted with glass ionomer cement.

All samples were thermocycled for 300 cycles at temperature extremes of five and 55 degrees Celsius. The samples were stressed to failure with an Instron testing machine with the stylus placed in the lingual notch at an angle of 135 degrees to the long axis of the tooth. The forces (in kilograms) necessary to induce systemic failure were statistically analyzed using the one-way ANOVA method.

Results: The control group was most resistant to failure. There was a statistically significant difference between groups A, B, C and group E (p..05). Group D, the Carbon fiber Post/Core group, was statistically similar to both the experimental groups A, B, C and to the control group (p>.05) due to the large standard deviation of group E.

Conclusion: The forces necessary to induce failure, averaging 60kg, suggest that any of the four examined post and core systems may be viable treatment alternatives. The Carbon Fiber Post/Core system demonstrated a statistical advantage over the other three experimental groups that may translate into a clinical benefit. Care must be exercised in applying these laboratory results to the clinical situation.

Hygiene Student Winners

Microbial Leakage in Examination Gloves Subjected to ASTM Water Leakage Testing

Rex Gabel, Jill Honce, Jennifer Moon, dental hygiene students; and James Kettering, PhD, faculty advisor; Loma Linda University, Loma Linda, California.

Introduction and Purpose: Concern over infection control in the dental setting has resulted in increased use of examination gloves as a protective barrier. Commercially available gloves are tested for water leakage by a procedure developed by the American Society for Testing and Materials (ASTM). Studies have shown failure rates of two to 35 percent, with a failure of four percent considered acceptable. Interestingly, the ASTM testing standard makes no warranty regarding the size or type of defect that allows water leakage. The purpose of this study was to test four latex brands and one vinyl brand of examination gloves for ASTM water leakage and microbial leakage.

Method: This experiment involved testing 200 latex gloves from each of four brands and 200 vinyl gloves from one brand for water leakage as described by the ASTM method (D 5151-92). Any glove failing the water leakage test was subjected to a second examination for the leakage of Serratia marcesens (S. marcesens).

A pilot study was conducted to determine the type of contamination present on gloves taken directly from the manufacturer's packaging. None of the five brands tested showed contamination with S. marcesens.

Thirty milliliters of a S. marcesens culture were placed inside each glove. The gloves were then suspended in individual containers with 80 mls of sterile trypticase soy broth (TSB) and incubated at 370 C for two days. The TSB was then plated and evaluated after two days for the presence of red colonies of S. marcesens.

Twenty gloves of each brand that passed the water leakage test were also tested for bacterial leakage as a negative control.

Results: The four latex brands had failure rates in the water leakage test of 7%, 6.5%, 4% and 2.5%(p=0.002). All of the latex gloves failing the water leakage test also failed the microorganism leakage test. Of the negative controls, two latex brands allowed 30 percent leakage of S. marcesens, one 5% and one 0% (p=0.000). The vinyl gloves showed no failures in the ASTM water leakage test, however, five percent had bacterial leakage. The results of this study were analyzed using the Chi Square statistical test. The Chi Square for the water fill test was 17.448 and the Chi Square for the negative control was 51.000.

Conclusion: This study demonstrates a need for continued concern regarding the possibility of bacterial and viral leakage in gloves that are commercially available to the dental community.