Thermafil retreatment using a new "System B" technique or a solvent.

The solid plastic carrier in the Thermafil obturation system must be removed to facilitate retreatment. The purpose of this study was to compare the efficacy and time required to retreat canals obturated with Thermafil with plastic carriers using a new technique based on the System B HeatSource or a solvent. Fifty-two extracted human mandibular premolars with single canals were instrumented and then obturated with Thermafil with plastic carriers. After 2 wk storage at 22 degrees C and 100% humidity, they were randomly divided into 2 groups of 26 teeth each. Group 1 teeth were retreated using chloroform and hand files, whereas teeth in group 2 were retreated with a new technique using the System B HeatSource. The end point of retreatment was defined as complete removal of the plastic carrier. The time required for retreatment was recorded. Then, the apical 5 mm segment of each root was sectioned horizontally at 1 mm intervals and each section digitally imaged. The total area of the canal and the area of the canal occupied by gutta-percha and sealer were measured using NIH image software. Data were analyzed using an unpaired t test. The mean time for retrieval of the plastic carrier was significantly less for the System B technique (1.8 min) than for the solvent technique (3.6 min) (p < 0.001). The difference between the two groups in the amount of filling material (carrier, gutta-percha, and sealer) removed was not significant (p > 0.05).

Evaluation of pigmented intraorifice barriers in endodontically treated teeth.

The purpose of this study was to evaluate the effectiveness of three pigmented glass ionomer cements used as intraorifice barriers to prevent coronal microleakage. One hundred ten extracted mandibular human premolars were divided into four experimental groups of 25 teeth each and two control groups of 5 teeth each. The experimental teeth were instrumented and obturated using thermoplasticized gutta-percha and AH26 sealer. Group 1 teeth received no further treatment. Teeth in groups 2 through 4 had 1 of 3 pigmented glass ionomers (Vitrebond, GC America, and Ketac-Bond) placed as an intraorifice barrier. Positive control teeth were instrumented but not obturated. The negative control teeth were instrumented, obturated, and externally sealed with epoxy resin. The coronal 3 mm of each root was sealed into the lumen of an 18-mm segment of latex surgical tubing. After the apparatus was sterilized, 2.0 ml of a 24 h growth of Proteus vulgaris in trypticase soy broth (TSB) was placed in the coronal reservoir of the tooth. The inoculated apparatus was placed into a presterilized test tube containing 1.5 ml of TSB and incubated for 90 days at 37 degrees C. The TSB in the lower reservoir was observed daily for turbidity, which would indicate leakage along the full length of the obturated root canal. To determine if differences in microbial leakage occurred among the four experimental groups, Pearson's chi 2 and Fisher's exact tests were performed. The confidence level was set at 95%. The positive and negative controls validated the microbial testing method. The teeth without an intraorifice barrier leaked significantly more than teeth with Vitrebond intraorifice barriers (p < 0.05). The difference in leakage among the experimental glass ionomer barriers was not significant (p > 0.05).

Use of a hydroxylapatite-based material and calcium sulfate as artificial floors to repair furcal perforations.

OBJECTIVE: The purpose of this study was to evaluate a hydroxylapatite-based material and calcium sulfate when each was used under a resin-modified glass ionomer cement to repair furcation perforations. STUDY DESIGN: Perforations of pulp chamber floors were made in 72 teeth of 9 dogs. Perforations were divided into 3 equal-sized groups and repaired with resin-modified glass ionomer either alone or over an artificial floor. The artificial floor was either a hydroxylapatite-based material or calcium sulfate. Three dogs were killed at each of 3 intervals (1, 3, and 6 months). The tissue response to the tested materials was evaluated clinically, radiographically, and histologically. RESULTS: The hydroxylapatite-based material showed the highest radiographic success; this was followed by calcium sulfate and glass ionomer. From histologic evaluation, the average success rate was found to be 67% for calcium sulfate, 62% for the hydroxylapatite-based material, and 59% for glass ionomer. However, there was no statistical significant difference with the resin-modified glass ionomer when it was used alone and when it was used over a barrier. There was also no significant difference between the hydroxylapatite-based material and the calcium sulfate when they were used as artificial floors. CONCLUSION: The use of an artificial floor may not be necessary when flowable resin-modified glass ionomer cements are used.

Evaluation of a combined surgical repair and guided tissue regeneration technique to treat recent root canal perforations.

This study evaluated a technique that included retrofill to repair molar root canal perforations and guided tissue regeneration to restore the periodontium that was removed from the furcation area for access to the sites. Six dogs had root canal therapy on mandibular fourth premolars and first molars. The distal root of each tooth was perforated on the furcation aspect halfway between the furcation and the apex. Replaced flap surgery was performed for access to prepare and fill the perforation site with intermediate Restorative Material. A bone xenograft was placed in the access ostectomy site and covered with GoreTex Augmentation Material (GTAM). Controls included unfilled perforations and not using bone grafts and/or GTAM. Dogs were killed at 6, 12, and 24 wk postsurgery. Complications were more common when root perforations were left unfilled. Histomorphometry revealed a statistically significant decrease in inflammation and more bone fill when root perforations were filled and GTAM was used, respectively.

Torsional properties of nickel-titanium versus stainless steel endodontic files.

The purpose of this study was to evaluate and compare the torsional properties of stainless steel K-type .02 taper and nickel-titanium U-type .02 and .04 taper instruments. Torsion tests were performed on all three designs of instruments according to ANSI/ADA specification number 28. For each design, 20 instruments of each of three sizes (15, 25, and 35) were tested. The three parameters measured were maximum torque, torque at failure, and angular deflection. Stainless steel K-type .02 taper and nickel-titanium U-type .02 and .04 taper instruments met or exceeded specification standards for maximum torque. They also satisfied and far exceeded the standards for angular deflection at the failure point. The stainless steel instruments showed no significant difference between maximum torque and torque at failure, whereas both of the nickel-titanium instruments showed a significant differential between maximum torque and torque at failure.

Effect of two obturation techniques on the filling of lateral canals and the main canal.

The three-dimensional obturation of the root canal system is widely accepted as a key factor for successful endodontic therapy. The purpose of this study was to evaluate the obturation of lateral canals and the main canal using cold lateral condensation versus the gutta-percha coated rigid carrier. Thirty epoxy blocks with five lateral canals placed at varying angles from the main canal were used. Each experimental group was obturated by a board certified endodontist with clinical experience in the respective obturation technique. The length of gutta-percha and sealer in the lateral canals was measured under a microscope (x30, Unitron) to the nearest 0.5 mm. The blocks were sectioned with an Isomet Plus precision saw (Buehler, Lake Bluff, IL) and copious water irrigation perpendicular to the main canal at the apex, the height of contour, and at 0.8, 1.6 and 2.4 mm from the canal apex. A microscope (x100, Leitz, Switzerland) was used to determine voids. There was significantly (p < .001) more gutta-percha in the lateral canals with the gutta-percha coated rigid carrier technique. In contrast, the cold lateral condensation technique had significantly (p < .001) more sealer in the lateral canals. However, there was no significant (p < .05) difference, in gutta-percha-plus-sealer filling of the lateral canals, between the two techniques. In the apical 1 mm of the main canal there were significantly (p < .011) fewer voids with the gutta-percha coated rigid carrier technique compared to the cold lateral condensation. In the model chosen, the gutta-percha coated rigid carrier technique and the cold lateral condensation technique were equally effective in filling lateral canals. In filling the main canal, however, the coated rigid carrier technique was more effective.

The University of Tennessee, College of Dentistry philosophy and technique for cleaning and shaping root canal systems.

The introduction of nickel titanium files has caused what the author believes to be revolutionary changes in the cleaning and shaping of root canal systems. New materials and file designs are constantly being evaluated and considered for introduction in the dental school curriculum. It is the purpose of this paper to review the techniques currently being taught and introduce some new ideas and techniques which are being evaluated for introduction into the curriculum in the future. Techniques using hand and rotary files will be presented in addition to a review of nickel titanium files.

Effect of dentin preparation and acid etching on the sealing ability of glass ionomer and composite resin when used to repair furcation perforations over plaster of Paris barriers.

Access openings and furcation perforations were prepared in 60 human extracted teeth and randomly divided into four equal groups. Plaster of Paris barriers were created in all perforations. The defects were obturated using either glass ionomer or composite resin with or without acid etching of the dentin. The pulp chambers and access openings were filled with composite resin. After immersion in 2% methylene blue solution for 2 weeks, the teeth were sectioned longitudinally and dye penetration was measured under a stereomicroscope using the NIH Image 1.47 Macintosh program. The results indicated that light-cured glass ionomer provided a significantly better seal than did the light-cured composite resin with or without dentin preparation and acid etching. The glass ionomer allowed significantly less dye penetration when used on etched dentin than it did on nonetched dentin.

An evaluation of nitinol and stainless steel files used by dental students during a laboratory proficiency exam.

Eighty-one dental students instrumented two curved canals in acrylic blocks with the use of stainless steel files in one block and nitinol files in the other. Overlay tracings were made of photographs taken before and after instrumentation of the acrylic blocks and differences between the tracings were measured along the canal walls. The canals instrumented with nitinol files were shaped better than those instrumented with stainless steel files; working length was maintained more often without ledging the canal walls and with less zipping of the apical foramen.

An in vitro evaluation of plaster of Paris barriers used under amalgam and glass ionomer to repair furcation perforations.

Furcation perforations were created in the pulpal floor of 60 teeth and were repaired with amalgam alone, plaster of Paris under amalgam, light-cured glass ionomer alone, and plaster of Paris under light-cured glass ionomer. After the access openings were filled with composite resin, the teeth were immersed in 2% erythrocin B dye solution for 2 wk, sectioned longitudinally, and dye penetration was measured. The light-cured glass ionomer group provided the least amount of leakage, followed by the group of plaster of Paris under glass ionomer. The groups using amalgam alone and plaster of Paris under amalgam showed the most leakage. The plaster of Paris barrier prevented the overextension of the repair materials when used under amalgam and glass ionomer.

A combined endodontic retrofill and periodontal guided tissue regeneration technique for the repair of molar endodontic furcation perforations: report of a case.

This is a report of a case in which the techniques of endodontic retrofill and guided tissue regeneration were used together to treat a perforation of the mesiofacial root of a maxillary left first molar (a strip perforation). After full-thickness flap reflection, the root received a retrograde filling and a large fenestration defect was surgically created to allow access to the furcal (distal) surface of the mesiofacial root. The roots were treated with tetracycline, the defect was filled with freeze-dried, demineralized, irradiated human cadaver bone, and the access fenestration was covered with a piece of barrier membrane. Healing was uneventful and the defect showed 100% bone fill at the time of reentry to retrieve the membrane 7 months after the initial surgery. Fifteen months after surgery the area appears clinically and radiographically healthy and the tooth has been employed as an abutment for a fixed partial denture.

Comparative study of the sealing ability of light-cured versus chemically cured materials placed into furcation perforations.

Two light-cured materials, Vitrebond and Prisma VLC Dycal, were compared with two chemically cured materials, Ketac Fil and Dycal, for ability to seal furcation perforations. Access openings and furcation perforations were prepared in 60 teeth and randomly divided into four equal groups. Furcation perforations were repaired with each of the tested materials, and the access openings were filled with composite resin. After teeth were immersed in 2% erythrocin B dye solution for 10 days, they were sectioned longitudinally and dye penetration was measured. The light-cured materials allowed statistically significant less dye leakage than did the chemically cured materials.

An evaluation of the durability of apex locator insulated probes after autoclaving.

The purpose of this study was to evaluate the durability of insulated probes designed to be used with the Endocater Apex Locator when put through multiple cleaning and autoclaving cycles. The manufacturer has reported that the plastic coating on the probes is reliable with normal use and sterilizable up to a maximum of three cycles. The quality of the seal provided against electrical conductivity by the coating was evaluated using 60 probes of various sizes (10, 15, 20, 25, 40) before and after autoclaving. Visual and electrical field methods were used to detect any leakage in the insulated coating. Defects were detected electronically before they could be detected visually. Statistically significant differences in millimeters of coating lost were found between the original evaluation and after each autoclaving cycle. The size 40 probes lost statistically significantly more coating than did any of the other sizes. The loss of coating seemed to be related to the millimeter markings. The quality of the probes as they came from the manufacturer was excellent; no defects were found in the coating prior to autoclaving.

Effect of three obturation techniques on the filling of lateral canals and the main canal.

The three-dimensional obturation of the root canal system is widely accepted as a key factor for successful endodontic therapy. The purpose of this study was to evaluate the obturation of lateral canals and the main canal using three gutta-percha sealer techniques: cold lateral condensation, warm lateral condensation, and warm vertical condensation. Sixty epoxied blocks with five lateral canals placed at varying angles from the main canal were used. Each experimental group was treated by a board-certified endodontist with training and clinical experience in that obturation technique. There was no statistically significant difference (p < 0.05) between the obturation techniques in the ratio of the void area to the gutta-percha-plus-sealer area for the main canal. There was significantly (p < 0.001) more sealer in the lateral canals for the two lateral condensation techniques. The warm obturation techniques had significantly (p < 0.001) more gutta-percha in the lateral canals.

Evaluation of the sealing ability of amalgam, Cavit, and glass ionomer cement in the repair of furcation perforations.

Perforations created in the pulpal floors of 30 extracted molars were repaired with amalgam, Cavit, and light cured glass ionomer cement. After the pulp chambers and access openings were filled with composite resin, the teeth were then immersed in 2% Erythrocin B solution for 1 week. After longitudinal sectioning of the teeth, dye penetration was measured. The results indicated significant differences between the three materials. Light cured glass ionomer exhibited the least dye penetration followed by Cavit and amalgam.

An evaluation of the number of condenser insertions needed with warm lateral condensation of gutta-percha.

The purpose of this investigation was to determine the number of condenser insertions needed to obturate root canal systems using warm lateral condensation. Forty epoxide blocks with one major and five lateral canals placed at varying angles were used. The blocks received either one, three, five, or seven insertions of the warm instrument. The findings revealed gutta-percha and or sealer in every lateral canal. Cold compaction of the heated gutta-percha produced more material in the lateral canals than did the use of the heated condenser alone. The optimum number of condenser insertions depended upon the position of the lateral canal, the size of the canal, and the bulk of material being heated. The areas of the main canal with a smaller diameter required fewer insertions of the warm condenser to push the gutta-percha into the lateral canals located in those areas.

An evaluation of two electronic apex locators in a dental student clinic.

The purpose of this study was to compare the accuracy and efficiency of two electronic apex locators to those of a conventional technique of determining working length with radiographs. Data were collected from 53 patients with a total of 96 canals treated by dental students. No significant difference was noted in the accuracy of the two apex locators. The readings from these units exactly agreed with the working lengths established by the students and faculty in 34% of the canals and were within 1.0 mm of the length in 80 to 86% of the canals. The data seem to indicate that apex locators have the potential for reducing the number of radiographs required if used before the working length radiographs are taken. Working lengths should be verified radiographically, because electronic apex locators were not accurate in every case.

Diagnostic procedures for evaluating pulpally involved teeth.

Pulpal and periapical problems are often difficult to diagnose because of seemingly conflicting or unclear symptoms. This difficulty increases when there is an emergency situation, and improper diagnosis can lead to improper treatment, causing distress to both the patient and clinician. Because the histopathologic condition of the pulp cannot be determined with clinical means or other diagnostic data, the clinician should focus on making an accurate clinical diagnosis using the patient's history and description of pain, clinical examination, and various diagnostic tests. This review discusses these factors and stresses the importance of making an accurate diagnosis.

An in vitro study of the effect endodontic access preparation and amalgam restoration have upon incisor crown retention.

Endodontic access preparation leads to a significant reduction in crown retention. This study sought to determine whether this retention can be regained after access. Eighteen extracted human maxillary incisors had PFM crowns fabricated. Crowns were cemented, retention measured, recemented, access preparations cut, and retention once again measured. Then, crowns were recemented and accesses restored with dental amalgam and new retention measured. This format allowed each crown to be used as a control of itself. For crowns cemented with zinc phosphate cement and restored with amalgam, a 126% increase over original retention was measured. For crowns cemented with polycarboxylate cement and restored with amalgam, a 237% increase over original retention was measured. For crowns cemented with polycarboxylate cement and restored with amalgam, a 237% increase over original retention was measured. These results suggest that recementing crowns secondary to endodontic access and restoring the access with amalgam regains and even surpasses the original retention.

Treatment of the endodontic emergency: a decade later.

A questionnaire was sent to diplomates of the American Board of Endodontics to determine changing trends in the treatment of endodontic emergencies since Dorn's survey 10 yr ago. There is a definitely greater trend toward complete instrumentation of the root canals to the apex regardless of the emergency condition than there was a decade ago. The number of respondents who leave teeth open when the pulp is nonvital has dropped dramatically in the past decade. When there is no periapical involvement, over one third of the respondents are completing treatment in one visit. A decrease in the use of classic phenolic medicaments was noted with a corresponding increase in calcium hydroxide or no medication at all.