Melvin Goldman

A scanning electron microscopic comparison of a high volume final flush with several irrigating solutions: Part 3

This study tested the efficacy of instrumenting the root canal with 1 ml of 5.25% NaOCl solution between each instrument and final flushing with 20 ml of various solutions or combinations of solutions. The scanning electron microscope showed that a final flush with 10 ml of 17% EDTA buffered to pH 7.7 followed by 10 ml of 5.25% NaOCl solution was the most effective.

Endodontic success—Who's reading the radiograph?

Abstract Success and failure in 253 cases selected at random were determined by mounting the films and having six examiners read them, independently and without consulting one another. They agreed on fewer than half of the cases. When the question was only one of determining whether or not an area of rarefaction was present on one film, the agreement was still less than half. Upper molars gave the greatest percentage of disagreement, but all the other teeth gave large percentages of disagreement also.

Reliability of radiographic interpretations

Abstract The same 253 cases that had been examined by six independent examiners previously were re-examined 6 to 8 months later by three of the original examiners. Each examiners results were then compared with his original results. They agreed with themselves anywhere from 72 to 88 per cent of the time in various categories. The analysis, however, showed large discrepancies in almost all categories of comparisons.

The efficacy of several irrigating solutions for endodontics: a scanning electron microscopic study.

The perforated irrigation needle was used to test a high-volume (20 c.c.) final flush of prepared root canals. Three solutions: TEGO 1 percent, NaOCl 5.25 percent, and REDTA were tested. The roots were split longitudinally and were prepared for examination under the scanning electron microscope immediately after preparation and final flushing. In addition, groups were prepared and flushed in the same manner, but after splitting they were soaked in the respective solutions for 3 hours and then examined. The results indicated that the smeared layer is caused by instrumentation, that it is not removed by TEGO or NaOCl, and that it is removed by REDTA. It may be that the smeared layer is a slurry of dentin filings, since REDTA does not remove soft tissue. All solutions produced a canal quite free of debris; however, none of the tested irrigants was completely satisfactory by itself.

The efficacy of several endodontic irrigating solutions: a scanning electron microscopic study: part 2

Extracted teeth were reamed and filed using either REDTA or 5.25% NaOCl during instrumentation, then given a final flush of REDTA or 5.25% NaOCl, singly or in combination. The results indicated that NaOCl used during instrumentation was more effective than REDTA. When the two solutions were used as a final flush, the most effective procedure was REDTA followed by NaOCl.

The morphology of the prepared root canal: A study utilizing injectable silicone

Abstract Postdebridement canal anatomy of 217 teeth was studied. Models of the canals were made with injectable silicone impression material. Many variations in the anatomy of these prepared canals were seen under the dissecting microscope. These included minute lateral canals, webbing between canals, fins, and instrument markings. It was also found that the anatomy of the prepared canal was very dissimilar to the instruments used to prepare them, especially in the apical third. Standard instrumentation techniques tend to leave a considerable portion of the canal wall untouched. Further investigations utilizing similar methods to aid in the development of new instruments and techniques for debridement and canal obturation are under way.

The usefulness of dye-penetration studies reexamined

An in vitro study to determine the usefulness of dye-penetration studies was conducted. In part I, teeth were prepared through the foramen and then left open, either apically, coronally, or at both ends. In all cases, the dye did not penetrate the full length of the canal. The only exception was when both ends were left open and the teeth were placed into the dye in an upright position. In part II, a measurable defect in a canal filling the length of the canal was created and left open apically. When the tooth was immersed in dye, the penetration was incomplete. When the air was removed by vacuum pump prior to placement in the dye, the penetration was total. The validity of dye studies that do not consider entrapped air is open to question.

Gutta-percha root canal fillings

Abstract Eighty-seven extracted teeth were prepared with endodontic instruments, stored in 2.5 per cent sodium hypochlorite to remove organic debris, and then filled with gutta-percha by means of the lateral condensation method. The teeth were then decalcified and dissolved away, leaving the gutta-percha fillings. Examination of these fillings revealed (1) many irregularities in form and condensation, (2) inadequate sealer dispersion, (3) lack of demonstration of canal variations, such as fins and lateral canals, (4) lack of correlation with radiographs, and (5) roughness and pitting, in contrast to the smooth surfaces of previously described silicone models.

The influence of the smeared layer upon dentinal tubule penetration by endodontic filling materials. Part II.

Root canals in instrumented extracted teeth were filled using the following materials: pHEMA, silicone, and laterally condensed gutta-percha with sealer. Fractured and ground specimens were prepared and the materials were examined, in situ, using scanning electron microscopy. Under the conditions of this study, pHEMA, silicone, and the sealers were consistently seen to enter the dentinal tubules when the smeared layer was removed prior to filling. When the smeared layer was present during filling, tubular penetration was unpredictable and infrequent.

Microleakage—Full crowns and the dental pulp

Recent studies have described microleakage under full crowns cemented with several different cements. This study tested three different types of crown margin preparations--a chamfer, a shoulder, and a shoulder plus a bevel to determine whether or not the margin preparation could affect microleakage. All crowns were cemented with zinc phosphate cement. The crowns were tested for leakage in thermocycled dye. All crowns demonstrated significant leakage following the path of the dentinal tubules into the pulp. This could possibly be one of the causes of pulpal inflammation and even pulpal death under full crowns.