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It has been the purpose of this article to provide a rationale for the restoration of endodontically treated teeth. Treatment recommendations have been made in the areas of post design, placement technique, cements, core materials, and definitive restorations, based on a review of the clinical and laboratory data.
Resistance to torsional forces is critical in restoration of endodontically treated teeth. Seven post designs (Flexi-Post, Flexi-Flange, Para-Post, AccessPost, World Post, Vlock, and Dentatus posts) were cemented in roots of natural teeth with zinc phosphate and Flexi-Flow cements, which resulted in 11 different groupings that were subjected to torsional forces in a clockwise direction. In addition, clockwise and counterclockwise torque was applied to the Flexi-Post and Flexi-Flange systems cemented with zinc phosphate and Flexi-Flow cements. A total of 150 samples were prepared, and groups for this study were: group 1, Flexi-Post/zinc phosphate clockwise and counterclockwise; group 2, Flexi-Post/Flexi-Flow clockwise and counterclockwise; group 3, Flexi-Flange/zinc phosphate clockwise and counterclockwise; group 4, Flexi-Flange/Flexi-Flow clockwise and counterclockwise; group 5, Para-Post/zinc phosphate clockwise; group 6, AccessPost/zinc phosphate clockwise; group 7, AccessPost/Flexi-Flow with grooved dentin clockwise; group 8, World Post/zinc phosphate clockwise; group 9, World Post/Flexi-Flow with grooved dentin clockwise; group 10, Vlock Post/zinc phosphate clockwise; and group 11, Dentatus post/zinc phosphate clockwise. Torsional forces for the groups ranged from 17 ounce-inches (Dentatus/zinc phosphate) to 81 ounce-inches (Flexi-Post/zinc phosphate). Flexi-Post and Flexi-Flange threaded posts exhibited statistically greater resistance to torsional forces. Analyses were computed with one-way and three-way analysis of variance followed by Duncan's multiple range test. Duncan's multiple range test indicated that Flexi-Post/zinc phosphate/clockwise was similar to Flexi-Post/Flexi-Flow/clockwise and that both had significantly higher torque levels than the other treatment conditions in the clockwise direction (p 0.0001). Dentatus/zinc phosphate/clockwise had significantly lower torque levels than the other treatment conditions (p 0.031).
The retentive capacity of three preformed endodontic dowel designs was compared at two lengths and two diameters, with three different cements. The greatest single factor influencing retention of these devices was the design used. Of the types tested in this study, the most retentive were threaded, parallel-sided dowels screwed into tapped channels. Serrated, parallel-sided dowels cemented in matched cylindrical channels provided intermediate retention, and smooth-sided tapered posts were the least retentive. Another major factor in retention was the length of imbedment into dentin. An increase in dowel imbedment depth usually corresponded to increased retention. The effect of cement type was significant only with tapered dowels. Zinc phosphate cement was most retentive, carboxylate cement exhibited intermediate retention, and the epoxy cement was least retentive. For the other post designs, cement type had no significant effect on retentive capacity. Finally, variations in dowel diameter had no significant effect on retentive ability.
A modification of existing designs for resin-bonded retainers has been introduced. This new design is appropriate for the extracoronal splinting of anterior teeth with reduced periodontal support. The design of the splint will accommodate the increased risk of these teeth for endodontic failure. The versatility and advantages of this design have been presented and compared with other anterior splinting techniques. At present, there appears to be no clinically significant difference in the retentiveness of perforated and nonperforated etched metal retainers.
Fractures of restored pulpless teeth without reinforcement are a familiar dilemma to the dentist. This study examined the effect of a metal collar with approximate 3 degrees of taper on the resistance of endodontically treated roots to fracture. Teeth without copings failed at a load of 49.6 kg whereas teeth with metal collars failed at a load of 65.29 kg. Our findings indicated that reinforcement with a metal collar is necessary to enhance resistance to root fracture.
PURPOSE: This pilot study examined the cyclic fatigue of five endodontic post systems (AccessPost, Flexi-Flange, Flexi-Post, ParaPost, and Vlock) with four core materials (Tytin silver amalgam, Ti-Core, Ketac-Silver and G-C Miracle Mix). MATERIAL AND METHODS: In vitro cyclic fatigue was performed with a machine designed to simulate masticatory fatigue forces. An instantaneous force of 22.2 N (5 pounds) was applied to each post and core combination for a test configuration of 4,000,000 repetitions, or until failure occurred. The type of failure and number of repetitions at failure was recorded for each sample tested. Two-way analysis of variance (ANOVA) was used to compare groups. RESULTS: All posts/core samples with Ti-Core composite and Tytin silver amalgam completed the test with no failures. All posts/core samples with Ketac-Silver material failed before the 4,000,000 test cycle configuration and all failures were core failures. All posts/core samples with G-C Miracle Mix material failed in a similar manner. Newman-Keuls multiple comparison test illustrated that, with this simulated fatigue test, Ti-Core material and Tytin silver amalgam were superior to both G-C Miracle Mix and Ketac-Silver materials.
Posts and cores are often required for the restoration of endodontically treated teeth. Many methods for making post-and-core reconstructions have been described. With the increased use of all-ceramic systems for esthetic tooth restorations, there is a need for esthetic core reconstructions. This article describes several methods for fabricating esthetic posts and cores.
Mucocele is not a commonly observed complication of endodontic surgery. A case is reported of a mucocele forming in the incision line following periapical surgery.
The Thermafil device is becoming a popular obturating material. Because endodontic failures inevitably occur with all techniques, questions of retreatment of Thermafil-obturated teeth will also arise. The purpose of this study was to compare retreatment of Thermafil and laterally condensed gutta-percha. Thirty-five mandibular incisors were prepared with a stepback flare technique and divided into two groups. One group (n = 20) was obturated using Thermafil, the other group (n = 15) was obturated with laterally condensed gutta-percha. The teeth were stored in a humidor for 3 months to allow sealer to set. Retreatment of both groups was accomplished using a combination of heat and chloroform solvent. The time for retreatment was recorded. The teeth were split longitudinally and the amount of gutta-percha remaining in the root canal was measured and analyzed statistically. The results showed that in the coronal one-third of the canal, use of the Thermafil device resulted in significantly more remaining gutta-percha than use of laterally condensed gutta-percha. However, in the apical and middle one-third of the canal the difference in remaining gutta-percha between Thermafil and laterally condensed gutta-percha was not significant. The metal carrier was easily removed and the mean time for retreatment was 6.3 min for Thermafil compared with 5.7 min in the lateral condensation group.
The purpose of this investigation was to compare RadioVisioGraphy (RVG) imaging with conventional radiography in determining endodontic file length adjustment. Human cadaver sections with first or second molars were used. Files were inserted into canals at randomly selected lengths, from 4 mm short of the radiographic apex to 3 mm beyond. Radiographs and RVG images were evaluated to determine the adjustment needed to place the file 0.5 mm from the radiographic apex. Results showed no significant difference in the ability of endodontists to make accurate file length adjustments using conventional radiography versus RVG. In this study, it was found that: (a) accurate file length adjustments can be made from an image two times larger than the actual tooth; (b) RVG is not significantly better than conventional radiography; and (c) if both methods are available, RVG is preferred because of the significant reduction in radiation dose.
Maxillary central incisor teeth can vary dramatically in their external and internal anatomy. Endodontic treatment of a most unusual four-canal central incisor with resorption is described and healing is demonstrated.
Endodontic treatment of a permanent mandibular first molar and a second molar presumably joined by cementum is presented. This case illustrates the difficulty in interpreting the vitality testing in such a situation. It also suggests possible irreversible pulp injury of a vital healthy tooth caused by extension of the inflammatory periapical pathosis of the adjacent tooth.
This case report presents the successful endodontic treatment of a taurodontic mandibular second molar with five root canals (four in the mesial root, one in the distal root).
A laboratory study was performed on Gates Glidden and Peeso drills to determine the incidence of shaft fracture when a bending deflection was superimposed on the rotating drills. Samples of sizes #1 to #6 stainless steel Gates Glidden drills, sizes #1 to #6 stainless steel and carbon steel-type P Peeso drills, and sizes #009 to #023 carbon steel-type B-1 Peeso drills from each of two manufacturers were evaluated with a unique apparatus that applied a 2-mm bending deflection while rotating the instruments. The apparatus did not restrict movement of the bur head during rotation. The test drills were rotated at 2500, 4000, and 7000 revolutions per minute, and the number of revolutions at failure was recorded. Scanning electron microscopic observations established that the stainless steel Gates Glidden and Peeso drills failed by ductile fracture, whereas the carbon steel Peeso drills failed by brittle fracture. Instrument fracture was always near the handpiece shank with this test, and the length of the fractured drills was measured from the working tip. It is recommended that this additional test be adopted to determine fatigue properties of engine-driven rotary endodontic instruments in establishing international performance standards.
Four manual endodontic instruments, an ultrasonic and an endosonic system were studied with a view to evaluating the morphology of the smear layer and the amount of debris and pulpal residues in the apical third of human extracted straight teeth from 55- to 75-yr-old patients. The manual instruments were K files, Ergoflex files used with the step-back technique, Canal Master with its own technique, and Flex-R with the Roane technique. The ultrasonic system was Suprasson Piezo and the endosonic was Excalibur. Human extracted teeth with straight canals were used and examined under a scanning electron microscope. All manual instrumentations showed a homogeneous compact smear layer and no pulp residues. No statistical differences were observed among the four manual techniques. Ultrasonic technique showed the complete removal of the smear layer, leaving small amounts of pulp debris at the apical third, while the Excalibur showed an almost complete elimination of the smear layer, leaving a homogeneous layer of pulpal residues along the canal.
This study used a modified Bramante technique and new digital subtraction software to compare root canals prepared by nickel-titanium (Ni-Ti) hand, Ni-Ti engine-driven, and stainless steel hand endodontic instruments. Sixty mesial canals of extracted human mandibular molars were randomly divided into five groups. The roots were embedded in clear resin and cross-sectioned in the apical and mid-root areas. In group A, canals were instrumented using a quarter turn/pull technique with K-Flex files. In group B, canals were prepared with Ni-Ti hand files (Mity files) using the same technique as in group A. Group C was prepared with NT Sensor engine-driven files. Group D canals were prepared with Ni-Ti Canal Master "U" hand instruments. Group E was prepared with engine-driven Ni-Ti Lightspeed instruments. Digitized images of the uninstrumented canals were compared with images of the instrumented canals. Engine-driven Ni-Ti instruments (Lightspeed and NT Sensor file) and hand instrumentation with the Canal Master "U" caused significantly less canal transportation (p < 0.05), remained more centered in the canal (p < 0.05), removed less dentin (p < 0.05), and produced rounder canal preparations than K-Flex and Mity files. Engine instrumentation with Lightspeed and NT Sensor file was significantly faster than hand instrumentation (p < 0.05).
Apical surgery is known to be an effective and practical way of treating endodontic failures. However, in spite of seemingly proper root end management, surgical failures may occur as a result of lateral canal, dentinal tubule, end retrograde leakage. Since surgical retreatment of such failures would likely result in failure, the alternative of a nonsurgical retreatment should be carefully considered. An understanding of the relationship which exists between the quality of the orthograde treatment and the surgical prognosis is necessary to properly direct the course of treatment.
The purpose of this study was to evaluate the Thermafil endodontic obturation technique and to compare it with laterally condensed gutta-percha. Thirty-seven maxillary central incisors were similarly prepared and divided into groups. Seventeen were obturated with Thermafil and 17 with lateral condensation. Three served as controls. After vacuum staining, all teeth were cleared and apical dye penetration was evaluated by two independent observers. Average leakage values were 0.24 mm and 1.32 mm for Thermafil and 0.47 mm and 1.18 mm for lateral condensation. There was no significant difference between the techniques, although a difference between evaluators was noted. Final results point to the relative subjectivity of in vitro leakage studies. When comparing the obturation times of both techniques, the Thermafil technique averaged 2 min 56 s while lateral condensation took 3 min 26 s. Statistical analysis showed no significant difference in obturation times.