A laboratory evaluation of Ektaspeed Plus dental X-ray film

The effect of automated nonroller processing on the sensitometric characteristics of 3 intraoral film types

OBJECTIVES

We sought to compare the sensitometric characteristics of 3 intraoral film types processed in an automated roller solution with the characteristics of the films processed in 4 automated nonroller solutions.

STUDY DESIGN

Eastman Kodak Ultra-Speed, Flow X-ray EV-57, and Eastman Kodak InSight films were exposed to varying levels of radiation and processed in 1 automated roller solution and in 4 nonroller solutions. Speed and contrast were measured at various density levels and ranges.

RESULTS

With the exception of 1 nonroller solution, there was little difference in speed between roller and nonroller processing chemicals at various density levels. Some nonroller solutions were faster than the roller chemicals for all films. Nonroller processing mostly increased contrast compared with roller processing over various ranges.

CONCLUSIONS

Sensitometric properties of films processed in automatic nonroller solutions are comparable in many cases to those in roller solutions, sometimes resulting in greater speed and contrast. Different adjustments in exposure factors are required for specific film/processing combinations.

Radiation dose-reduction techniques in North American dental schools

OBJECTIVE

The purpose of this investigation was to describe the extent to which dental schools use materials, equipment, and quality-assurance protocols that reduce radiation exposure to patients.

STUDY DESIGN

Questionnaires soliciting information regarding intraoral and extraoral radiographic practices and quality-assurance procedures were sent to the directors of oral and maxillofacial radiology (OMR) at the 65 schools of dentistry in the United States and Canada.

RESULTS

The response rate was 100%. E-speed film is used at 86% of institutions. Direct digital radiography is used at 58% of institutions for intraoral imaging and 11% for extraoral radiography. Other dose-reducing techniques include long source-film distances (88%), rectangular beam limitation (47%), leaded aprons (95% for extraoral films; 85% with thyroid collars for intraoral films), and rare earth intensifying screens (100%). The most commonly used tube potential is 70 kVp (88%). The director of OMR is solely responsible for radiographic policies at approximately 75% of institutions. Regular tests for film fog, speed, and contrast are done at roughly 75% of schools, while over 90% test darkroom lighting and x-ray equipment.

CONCLUSIONS

Some dose-reducing strategies are commonly used in dental schools, while others have not gained wide acceptance.

Comparison between PAI and quantitative digital radiographic assessment of apical healing after endodontic treatment

OBJECTIVE

The purpose of this study was to compare both subjective (Periapical Index, PAI) and objective (densitometric) radiographic evaluation of healing after endodontic treatment for apical periodontitis.

STUDY DESIGN

Standardized radiographs of 103 teeth taken at baseline (immediately after endodontic treatment) and at 1, 4, 12, 26, and 52 weeks were evaluated. Consensus PAI scores obtained from 7 calibrated observers served as "true scores." Densitometric estimates of periapical status were obtained from digitized radiographs as the ratio of mean gray value of an area of radiolucency (AR) to an adjacent and similar-sized normal (N) area (AR/N). The selected regions of interest on baseline images were automatically superimposed on postoperative images. All estimates of change were measured with respect to baseline. The subtraction estimate was expressed as AR(S)-N(S). Linear regression was used to analyze longitudinal changes against baseline and to assess the relationship of PAI and AR/N and of change in PAI with respect to baseline and AR(S)-N(S).

RESULTS

Five hundred fifty-six PAI scores were generated, with 547 AR/N values and 444 subtraction estimates. PAI, AR/N, and AR(S)-N(S) demonstrated statistical significance for change (P < or = .05) starting at 12 weeks. PAI was significantly correlated with AR/N (P < .0001), as was CHPAI with AR(S)-N(S) (P < .024).

CONCLUSION

The PAI and 2 densitometric estimates (AR/N and AR(S)-N(S)) detected healing of apical periodontitis at 12 weeks after treatment. No difference could be observed among the methods.

A perceptibility curve comparison of Ultra-speed and Ektaspeed Plus films

OBJECTIVE

The purpose of this study was to evaluate the subjectively assessed contrast difference between Kodak's Ultra-speed and Ektaspeed Plus dental radiography films (Eastman Kodak, Rochester, N.Y.) through the use of perceptibility curves.

DESIGN

Four series of 22 radiographs were exposed at 70 and 90 kVp with each film type by means of a Gendex 1000 dental radiography unit (Gendex Corp., Milwaukee, Wis.) for times ranging from 0.05 to 5 seconds at 10 ma. The test object consisted of a 7-mm-thick rectangular aluminum block with 10 circular depth cuts, each 2 mm in diameter, which created wells varying in depth from 50 to 500 microns. The corresponding films were processed concurrently (for 4.5 minutes) in total darkness with fresh Kodak Readymatic solutions (Eastman Kodak) held at a constant temperature of 28 degrees C. The resulting radiographs were viewed in a predetermined random order under ideal conditions by 10 dentists. The evaluators recorded the maximum number of perceptible images on each film. A pair of perceptibility curves were generated at 70 and 90 kVp by plotting the log relative exposure versus the mean number of perceptible images.

RESULTS

There was no statistical difference between the two film types with respect to the mean number of perceptible images, as analyzed by Wilcoxon's signed rank test (p = 0.22; p = 0.44).

CONCLUSIONS

There is no subjectively assessed contrast difference between Kodak s Ultra-speed and Ektaspeed Plus films at 70 and 90 kVp.

In vivo study of approximal caries depth on storage phosphor plate images compared with dental x-ray film

The aim of this in vivo study was to compare approximal caries depth on storage phosphor plate images to conventional film. A Soredex Digora imaging plate was placed in a film bite-wing positioner behind a Kodak Ektaspeed Plus film package without lead foil. The effect of scattered radiation on film without lead foil with a storage phosphor plate at the back was studied in a separate in vitro experiment. Compared with film protected by lead foil, the film showed higher density, but comparable contrast. For the in vivo study, clinical bite-wing exposures were made with the setup described above, with exposure settings for Ektaspeed Plus film. A four-point scale was chosen for approximal caries depth: 0 = no caries; 1 = caries in enamel; 2 = caries reaching dentino-enamel junction; 3 = caries into dentin. The bite-wing film images were shown to a panel of four experts. Sixty surfaces were selected for observer performance, based on identical scorings of the experts consensus classification. Next, six dentists evaluated both film and storage phosphor plate images with the same four point scale. Analysis of variance revealed a significant observer and image modality effect without an interaction effect. In conclusion, caries depth on storage phosphor plate images was underestimated compared with film-based images.