Franklin S. Weine

The effect of preparation procedures on original canal shape and on apical foramen shape.

With the use of clear casting resin, simulated curved canals were created so that canal preparation procedures could be directly visualized and compared. Regardless of the type of enlarging instrument or the technique used, undesirable characteristics were produced in all preparations that would make canal filling difficult. To modify the typical preparations, alteration of the enlarging flutes, use of rasping rather than rotation of the instruments, and a flaring technique are recommended.

Canal configuration in the mesiobuccal root of the maxillary first molar and its endodontic significance.

Abstract The mesiobuccal roots of 208 teeth were sectioned buccolingually from the mesial aspect and the canal configurations were categorized. One hundred one (48.5 per cent) had a single canal, 78 (or 37.5 per cent) showed two canals which merged toward a single apical foramen, and twenty-nine (14.0 per cent) displayed two distinct canals with separate apical foramina. The frequency of occurrence of the bifurcated or double canal must be taken into consideration when surgical treatment is planned and as a possible cause of otherwise unexplained failure. Case histories are presented to illustrate these situations.

Long-term evaluation of surgically placed amalgam fillings.

The coauthors of this article had developed the clinical impression that whereas surgically placed amalgam fillings are successful on a short-term basis, the long-term prognosis for these cases may not be nearly as favorable. In order to test this hypothesis, as many patients as could be contacted, either directly or indirectly, who had been treated before 1981 were evaluated. Excluded from this study were cases for which failure could be attributed to any reason other than failure from the amalgam reverse filling. Therefore, all cases included had to demonstrate periapical healing prior to ultimate breakdown. On this basis, 60 of 104 teeth (57.7%) were considered to be successful and 44 teeth (42.3%) were determined to be failures.

Effect of preparation with endodontic handpieces on original canal shape.

Four widely used methods of root canal preparation—two of hand instrumentation (reaming action and flaring and removal of flutes) and two of mechanical instrumentation (Giromatic and W&H hand-pieces)—were compared by using simulated curved canals in resin blocks. Timewise, canal preparation by reaming action was the most efficient technique. Size of apical zips at the site of canal exiting was minimized most by flaring and removal of flutes for canals that had sharp apical curvatures.

Canal configuration of the mandibular second molar using a clinically oriented in vitro method

The canal configuration of 75 extracted mandibular second molars was categorized using radiographs from two directions with files in place at working length. One tooth (1.3%) had a single canal and two teeth (2.7%) were C-shaped. In the mesial root, 3 teeth (4%) were type I, 39 teeth (52%) were type II, and 30 teeth (40%) were type III. In the distal root, 64 teeth (85.3%) had a type I system, 7 teeth (9.3%) had a Type II, and 1 tooth (1.3%) was type III.

Retrospective study of tapered, smooth post systems in place for 10 years or more

A total of 211 consecutive patients of a restorative dentist who received full-mouth radiographs between October 1988 and March 1989 were screened for teeth treated endodontically at least 10 years earlier. In all, 51 patients had 138 teeth treated and restored by the authors. All involved teeth were restored with tapered smooth posts, cores with complete or 7/8 cast ferrules, and an onlay or cast precious metal crown (with or without veneering). No posts, splints, or bridges were loose, and only one crown was loose. There were nine failures in 138 teeth (6.5%)--three restorative, two endodontic, two root fractures, and two periodontal. When tapered smooth posts are used properly, retentive problems do not occur.

Sealing ability of Thermafil with and without sealer

The purpose of this study was to evaluate the apical sealing ability of root canals filled using three obturating techniques. Sixteen maxillary first molars were obturated with Thermafil, 16 with Thermafil and a ZOE sealer, and 16 with laterally condensed gutta-percha. Two canal instrumentation methods were used, conventional step-back preparation with K-Flex files and traditional instrumentation combining reaming with reamers and filing with K-Flex files. Following obturation, the teeth were prepared for evaluation of the seal using India ink and a Profile Projector. The depth of penetration of the dye was statistically evaluated for each of the three roots with an analysis of variance. For sealing ability, there was no significant difference at the p < 0.05 level between the conventional step-back preparation and the traditional instrumentation technique. However, a significant difference was present at the p < 0.05 level for the obturation techniques. The mean linear dye penetration for the Thermafil technique was greater than that for lateral condensation.

Effectiveness of eucalyptol and d-limonene as gutta-percha solvents

Eucalyptol and d-limonene were evaluated for their ability to serve as a substitute solvent for chloroform. The amount of time required to soften and remove the gutta-percha in 72 instrumented and filled simulated root canals in epoxy blocks was measured. After preparation to the apices of the block canals with a #60 file, four different filling techniques were used. These obturations were softened with each solvent and then removed, first using a #15 Hedstrom file inserted to full working length, and then removing the remaining filling mass with a #60 reamer. The two instrument placements were timed: one for the Hedstrom file insertion to the apex and the other for the reamer to remove the filling material. Neither the different solvents nor the filling techniques had a significant effect on the times required for the H-files to reach the apex. However, the times for the reamer to remove the filling materials were effected both by the filling techniques and the solvents used.

Effectiveness of selected irrigants in the elimination of Bacteroides melaninogenicus from the root canal system: An in vitro study

An in vitro study was performed to determine the effectiveness of certain irrigants on Bacteroides melaninogenicus , which has been implicated as an endodontic pathogen. Peptostreptococcus anaerobius was tested in addition to simulate the typical clinical condition. Clorox and Gly-Oxide, full strength and diluted, separately and alternatingly, were evaluated against the test organisms, as was saline. Test tube dilutions indicated that full-strength Clorox and Gly-Oxide were antibacterial, and lesser strengths were effective as well against the tested bacteria. Irrigation procedures on infected extracted teeth indicated that full-strength Clorox and Clorox and Gly-Oxide used alternatingly were antibacterial, whereas full-strength Gly-Oxide had variable effectiveness and saline was completely ineffective.

Case report: three canals in the mesial root of a mandibular first molar (?)

Recent studies on canal configuration have greatly clarified the number and type of canal systems present. The mandibular first molar may have one or two distal canals or roots, but only two mesial canals. This case report describes the treatment of a mandibular first molar in which three canals were located, prepared, and filled in the mesial root. An explanation is provided for this condition which may be applicable to some extremely unusual findings in other reports.