Influence of the major and minor foramen diameters on apical electronic probe measurements.

There have been conflicting reports on the accuracy of electronic devices used for determining working length. The influence of the major and minor diameters on electronic probe measurements were evaluated to ascertain whether anatomical features of the apical portion of the canal might be responsible for these discrepancies. Forty-seven nonrestorable teeth selected from 22 patients were studied. Conventional access was made. A Kerr file was placed to a position 0.5 mm from the major foramen as registered by the Neosono-D apex locator. The electronic probe length was then measured. After the tooth was extracted, the file was fixed with autopolymerizing composite in the canal. A Buehler Isomet lapadary saw was used to prepare specimens to a thickness of 500 microns. A Bioquant II Image Analysis System was used to measure and record distances. It was found that as the width of the major foramen increased, the discrepancy between the electronic probe tip length induction and the actual position of the major foramen increased.

Straight-line endodontic access to anterior teeth.

Straight-line access provides an unimpeded pathway for endodontic procedures. One hundred ninety-eight anterior teeth were examined to determine the location of the access preparation which would allow straight-line access for intracanal procedures. A radiographic analysis of these teeth indicated that a more labial orientation of the access opening would provide straight-line access to the canal more consistently than the "traditional" lingual access opening. The more labial placement of the access opening on maxillary or mandibular anterior teeth which will require full coverage will make endodontic treatment more efficient and may, therefore, increase endodontic success rates in these teeth.

Endodontic access to maxillary lateral incisors.

One hundred thirty-one maxillary lateral incisors were radiographed from a mesiodistal vantage point. Projections of the buccal and lingual walls onto the incisal showed that 16 percent opened to the buccal of the incisal edge; 32.9 percent were buccal and inclusive of the incisal edge, 43.5 percent were buccal and lingual to the incisal edge, 6.9 percent were inclusive of the lingual to the incisal edge, and 0.8 percent were entirely to the lingual of the incisal edge. Theoretically, the highest success rate that could be achieved for that portion of endodontic therapy that depends upon canal débridement would be gained by having the occlusal access opening in the most direct path to the long axis of the root canal. In this study it has been shown that, for maxillary lateral incisors, that path would necessitate that out occlusal opening be made inclusive of and slightly buccal to the incisal edge.