M. Trope

Resistance to fracture of endodontically treated roots

The root canals of 48 single-canal canine teeth were prepared by four different methods. The coronal lingual wall and root canal space were lowered to 2 mm below the buccal wall of the roots. The prepared root was placed into acrylic resin so that 12 mm of buccal root was exposed. A slowly increasing force was applied at the junction of the buccal wall and root canal space until fracture occurred. The force of fracture of the buccal root wall of each root was recorded and the results in each group were compared. All teeth fractured at the buccal wall/acrylic resin junction. Instrumentation of the root canals significantly weakened the roots. Obturation of the canals in conjunction with Roths 801 sealer did not strengthen the roots. Obturation of the canals in conjunction with a glass ionomer sealer significantly strengthened the roots as compared with roots instrumented but not obturated and those obturated with gutta-percha and Roths 801 Sealer.

Efficacy of removing glass ionomer cement, zinc oxide eugenol, and epoxy resin sealers from retreated root canals

Removal of gutta-percha and various sealers was assessed during retreatment of the root canal system. Sixty root canals were prepared and obturated with gutta-percha and Ketac-endo, Roths 801 cement, or AH26. After 14 days, the canals were retreated by hand or ultrasonic technique and the retreatment time was recorded. The roots were split and the amount of debris that remained on the canal walls in three separate levels was recorded by use of a dissecting microscope. The mean scores were compared by one-way and two-way ANOVA. The total score was significantly the highest for Ketac-endo (p less than 0.04), followed by AH26 and Roths 801 cement. The largest amount of debris was consistently found in the apical third, and generally it was comparable for both retreatment techniques. The ultrasonic technique was significantly faster than the hand technique for all sealers tested (p less than 0.0004, p less than 0.0003, p less than 0.02, respectively). Hand retreatment of Ketac-endo was the slowest, whereas ultrasonic retreatment of Roths 801 cement was the fastest. The results indicated that Ketac-endo endodontic sealer can be effectively removed from the root canal by ultrasonic instrumentation.

Dual wavelength spectrophotometry as a diagnostic test of the pulp chamber contents

The purpose of this in vitro study was to determine the feasibility of using dual wavelength spectrophotometry to identify teeth with pulp chambers that are either empty, filled with fixed pulp tissue, or filled with oxygenated blood. In phase I of the experiment, a human third molar was prepared so that its pulp space could be filled with oxygenated blood and later emptied. In phase II, the lower jaw of a beagle dog was removed and placed in formalin, thereby fixing the pulps of the teeth. The pulp of the right canine was removed via an apical approach, and attachments were placed in a similar position to those on the human tooth, to allow filling and emptying of the pulp space. Cavit was placed over the exposed fixed pulp in the left canine. Ten readings, which were separated by light source and detector removal and replacement, were taken of the right canine pulp space when it was empty or filled with oxygenated blood, or the left canine pulp space when it was filled with fixed tissue. Distinct and reproducible changes were measured for pulp spaces filled with air, tissue, or oxygenated blood. In phase III, simulated pulp testing on a dog tooth model was performed. Blood was introduced into the root canal space, the chamber was rinsed with water and replaced with air, according to a predetermined code. Spectrophotometer readings were recorded. The identification of pulpal contents was correctly determined in all 20 of the predetermined conditions. The findings indicate that continuous wave spectrophotometry may become a useful pulp testing method.

Human immunodeficiency virus infection of fibroblasts of dental pulp in seropositive patients

Presence of human immunodeficiency virus (HIV) within noninflamed human dental pulps was documented by polymerase chain reaction assays in 11 of 12 pulps from HIV-seropositive patients. The purpose of the present study was to determine the cellular location of HIV in vivo within these tissues by means of in situ hybridization. Results of the in situ hybridization indicated HIV within fibroblasts of the pulp. These results are especially relevant because fibroblasts lack the CD4 receptor thought necessary for in vivo infection with HIV. These results suggest the fibroblast as a possible reservoir for HIV in the body.