Fracture necrosis: diagnosis, prognosis assessment, and treatment recommendations.

INTRODUCTION: The presence of cracks and fractures in teeth can pose difficulties in diagnosis, prognosis assessment, and treatment recommendations. When a tooth has no significant restorations or caries, whereby the pulp is nonvital in the absence of a luxation injury, it is suggested that this necrosis is likely caused by a significant longitudinal crack that extends from the occlusal surface and into the pulp. This type of presentation has been termed "fracture necrosis." METHODS: Twenty-seven teeth with nonvital pulps were evaluated that had no restorations or minimally deep restorations and no signs of caries. These teeth were extracted and evaluated as to the depth and location of any potential fracture. RESULTS: All evaluated teeth were found to have cracks that extended from the occlusal surface into the pulp and progressed to an external root surface. CONCLUSION: Pulp necrosis, in the absence of restorations, caries, or luxation injuries, is likely caused by a longitudinal fracture extending from the occlusal surface and into the pulp. Based on the available literature, these types of teeth may have a poor prognosis after endodontic treatment, with the potential ramification of extensive periodontal and/or periapical bone loss. Extraction may be considered as the primary treatment option.

A practitioner survey of opinions toward regenerative endodontics.

The success of regenerative endodontic procedures requires practitioner acceptance, but little or no evidence is available. The purpose of this survey was to collect the opinions of attendee's of the 2008 Endodontic Board of Diplomates 2008 Summer Conference on the issue of regenerative endodontic procedures (REPs). After Nova Southeastern University institutional review board approval, 100 copies of a survey were circulated, and 56 completed surveys were returned anonymously. The survey found that 96% of participants thought that more regenerative therapies should be incorporated into treatments. Although only 14% of participants had used umbilical cord or stem cell banking for themselves or a relative, 63% thought that stem cell banking would be useful to regenerate dental tissues. Most (89%) of the participants would be willing to save teeth and dental tissues for stem cell banking. These results suggest that endodontic practitioners are supportive and optimistic about the future use of REPs.

Mineral trioxide aggregate obturation: a review and case series.

Mineral trioxide aggregate (MTA) has emerged as a reliable bioactive material with extended applications in endodontics that include the obturation of the root canal space. This article examines the literature supporting MTA as a canal filling material, suggests methods for its delivery and placement, and presents clinical cases that demonstrate its effectiveness in resolving apical periodontitis under a variety of circumstances. Case reports are presented documenting clinical outcomes after the application of MTA that include retreatment, obturation combined with root-end resection, apexification, internal resorption, dens in dente, and in conventional endodontic therapy. The review introduces clinicians to an alternative treatment strategy that might improve the healing outcomes for patients presenting with complex and challenging endodontic conditions.

Cell survival within pulp and periodontal constructs.

The purpose of this study was to measure cell survival and degradation within tissue-engineered dental constructs. Dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PLSCs) were seeded on three types of tissue engineering scaffolds: a synthetic open-cell D,D-L,L-polylactic acid (polymer) scaffold, a bovine collagen scaffold (collagen), and a calcium phosphate bioceramic (calcium phosphate) scaffold. The dental pulp and periodontal constructs (n = 144) were maintained in cell culture for between 3 and 14 days. The cell survival and degradation within the constructs were measured using histologic criteria. The DPSC and PLSC survival was optimal in the polymer and collagen constructs but not the calcium phosphate constructs, especially over longer time periods. These in vitro results suggest that both the polymer and collagen scaffolds and the DPSCs and PLSCs can be combined to create pulp and periodontal constructs for use in future regenerative dental treatments.

Antimicrobial efficacy of 4.2% sodium hypochlorite adjusted to pH 12, 7.5, and 6.5 in infected human root canals.

OBJECTIVE: The purpose of this study was to determine the antimicrobial efficacy of sodium hypochlorite adjusted to pH 12, 7.5, and 6.5 in human root canals infected by Enterococcus faecalis. STUDY DESIGN: One hundred sixty-five human single-rooted teeth were prepared and inoculated with E. faecalis for 48 h. Teeth were divided into 3 experimental groups according to the irrigation pattern used: group 1, 4.2% NaOCl pH 12; group 2, 4.2% NaOCl pH 7.5; and group 3, 4.2% NaOCl pH 6.5. Samples from the root canals were collected, and bacterial growth was analyzed by turbidity of the culture medium. RESULTS: None of the irrigating solutions used in this study demonstrated 100% effectiveness against E. faecalis. The antibacterial effectiveness of 4.2% NaOCl at pH 6.5 was significantly increased (P = .03) compared with 4.2% NaOCl at pH 12 (chi-squared test: P < .05). CONCLUSION: Bactericidal activity of NaOCl solution is enhanced by weak acidification of 4.2% NaOCl solution at pH 6.5.

The comparison of the effect of endodontic irrigation on cell adherence to root canal dentin.

The purpose of this study was to compare the effect of 10 different endodontic irrigation and chelating treatments on dental pulp stem cell (DPSC) attachment to root canal surfaces. Thirty-eight extracted human nondiseased single-canal teeth were cleaned and shaped using ProTaper and ProFile rotary instrumentation (Tulsa Dentsply, Tulsa, OK). The irrigation treatments investigated were 6% sodium hypochlorite, 2% chlorhexidine gluconate, Aquatine Endodontic Cleanser, and Morinda citrifolia juice. The irrigation treatments were used in conjunction with EDTA or MTAD. The instrumented teeth were immediately placed in cell culture with confluent DPSCs for 1 week. The number of attached DPSCs appeared to be correlated with the cytotoxicity of the root canal irrigating solution (analysis of variance, p < 0.0001). The presence or absence of the smear layer had little influence on DPSC activity (chi-square, p > 0.05). The results suggest that biocompatible irrigants are needed to promote DPSC attachment to root canal dentin, which is essential to accomplish some regenerative endodontic therapies.

The evaluation of four electronic apex locators in teeth with simulated horizontal oblique root fractures.

The accuracy of four electronic apex locators (EALs) to locate the apical limit in teeth with simulated horizontal oblique root fractures was investigated. A horizontal oblique incomplete root fracture was simulated on 20 freshly extracted maxillary anterior teeth by means of a notch made on the vestibular root plane 8 mm from the anatomic apex. The EALs investigated were the ProPex (Dentsply Maillefer, Ballaigues, Switzerland), the NovApex (Forum Technologies, Rishon Le-Zion, Israel), the Root ZX (J. Morita Corp, Kyoto, Japan), and the Elements Apex Locator (SybronEndo, Orange CA). The electronic measurements were compared with the real "working length." The accuracy obtained was of 80% (n = 16) and 95% (n = 19) with the ProPex, 70% (n = 14) and 95% (n = 19) with the NovApex, 60% (n = 12) and 90% (n = 18) with the Root ZX, and 60% (n = 12) and 85% (n = 17) with the Elements Apex Locator when tolerances of 0.5-mm and 1.0-mm tolerance were, respectively, allowed. The analysis of variance (p > 0.05) and chi-square test (0.5 mm/p = 0.47 and 1.0 mm/p = 0.63 tolerances) showed no statistical significant differences between the EALs at either tolerance level.

Comparison between a novel nickel-titanium alloy and 508 nitinol on the cyclic fatigue life of ProFile 25/.04 rotary instruments.

ProFile 25/.04 instruments manufactured from three variants of Nitinol (1A, 1B & 2AS) were compared with stock production ProFile 25/.04 instruments and fatigue tested to failure. Cyclic fatigue testing was performed by rotating instruments at 300 RPM in a simulated steel root canal with 5 mm radius and 90 degrees curve until instrument separation. Time to failure was recorded. Torsion testing was undertaken by clamping 3 mm of each instrument tip between brass plates and rotating it at 2 RPM until failure. Data were recorded for torque and angle at fracture. Statistical differences were found with nickel-titanium variant 1B (M-Wire NiTi) nearly 400% more resistant to cyclic fatigue than stock ProFile 25/.04 (P < .001). Torsion testing found differences between all 508 Nitinol groups and M-Wire NiTi (P < .001). ProFile 25/.04 files manufactured from M-Wire NiTi have significantly greater resistance to cyclic fatigue while maintaining comparable torsional properties.

An ultrastructural investigation of tissue-engineered pulp constructs implanted within endodontically treated teeth.

BACKGROUND: The authors conducted an ultrastructural scanning electron microscopic (SEM) investigation of tissue-engineered pulp constructs implanted within endodontically treated teeth. METHODS: Stem cells from human exfoliated deciduous teeth were seeded on a synthetic open-cell D,D-L,L-polylactic acid scaffold with or without the addition of bone morphogenic protein-2 and transforming growth factor beta1 to create pulp tissue constructs. The pulp constructs were implanted into 105 extracted human premolar teeth with a single root canal that had been cleaned and shaped by using rotary instrumentation in a crown-down manner to ISO size no. 35. RESULTS: An ultrastructural examination of the SEM micrographs at x2,000 magnification revealed cell adherence within all of the pulp constructs, with little difference between the scaffold types or with the addition of growth factors. CONCLUSIONS: These results support the proof-of-concept that it is possible to implant tissue-engineered pulp constructs into teeth after cleaning and shaping. CLINICAL IMPLICATIONS: Future regenerative endodontic treatment may involve the cleaning and shaping of root canals followed by the implantation of vital dental pulp tissue constructs created in the laboratory.

Evaluation of Morinda citrifolia as an endodontic irrigant.

The purpose of this study was to compare the in vitro effectiveness of Morinda citrifolia juice (MCJ) with sodium hypochlorite (NaOCl) and chlorhexidine gluconate (CHX) to remove the smear layer from the canal walls of endodontically instrumented teeth. Sixty extracted, single-rooted, mature, permanent, human premolar teeth with a single canal were inoculated with Enterococcus faecalis at 37 degrees C in a CO2 atmosphere for 30 days. The teeth were randomly allocated to 6 treatment groups; the pulp chamber was accessed, cleaned, and shaped by using ProTaper and ProFile rotary instrumentation to a size 35. During instrumentation the irrigation was provided by MCJ, NaOCl, CHX, MCJ/CHX, followed by a final flush of 17% ethylenediaminetetraacetic acid (EDTA). MCJ irrigation was also followed by a final flush of saline, and saline irrigation was also used as a negative control. The teeth were then processed for scanning electron microscopy, and the removal of smear layer was examined. Data were analyzed by chi2 statistical tests (P values) at a significance of 95%. The most effective removal of smear layer occurred with MCJ and NaOCl, both with a rinse of 17% EDTA. Both MCJ and NaOCl treatments were similarly effective with a rinse of 17% EDTA (P < .2471) to completely remove up to 80% of the smear layer from some aspects of the root canal. MCJ was more effective than CHX for removing smear layer (P < .0085) and saline as the negative control (P < .0001). The efficacy of MJC was similar to NaOCl in conjunction with EDTA as an intracanal irrigant. MJC appears to be the first fruit juice to be identified as a possible alternative to the use of NaOCl as an intracanal irrigant.

Retention of three endodontic post systems.

PURPOSE: To evaluate the retention of three post systems using one adhesive and one cement. The hypothesis tested was that there was no significant difference among the posts. METHODS: 90 freshly extracted single rooted lower bicuspids were evaluated for similar root morphology. The teeth were decoronated using an Isomet saw leaving a 15 mm-long sample. Preoperative digital radiographs were taken of all samples from the buccal and mesial direction. A glide path was established with #15K type file. Roots were then instrumented to working length to a size #40 .04 using Profile nickel titanium files. 1cc of distilled water was used as an irrigant after each file to remove dentinal debris. The teeth were then obturated with custom fit #40 0.04 taper gutta percha points and AH Plus as a sealer, using a warm vertical compaction technique. Residual gutta percha of 5 mm was left. The samples were divided into three experimental groups to receive posts. Group 1: Fiber White Para-Post No. 2 red; Group 2: No. 1 DT Light Post; Group 3: PeerlessPost No. 3. Post spaces were created in Groups 1 and 2 with the appropriate drills supplied by the manufacturer using a slow speed handpiece. The post spaces from Group 3 required no further preparation after endodontic treatment. All posts were cemented with Nexus 2 Universal Luting System. A layer of excess cement was left in the most coronal portion of the tooth for visual confirmation of tensile strength failure. Using an Instron the teeth were mounted in a custom-made jig to prevent crushing of the post and to ensure extension perpendicular to the long axis of the post. Samples were then subjected to tensile stresses until failure occurred. Failure was defined as the maximum load produced under tensile load that corresponded to visual separation of the post from the tooth. The maximum load at failure in kilograms was recorded. The average of each group was compared for significant difference. Data was analyzed using ANOVA at a significance level of P= 0.016 (Bonferroni correction for multiple t-tests). RESULTS: Maximum load at failure, measured in kilograms, were as follows: PeerlessPosts 126.07 kg, Fiber White Posts 90.14kg, and DT Light Posts 88.46 kg. ANOVA revealed a statistically significant difference among the three posts systems. PeerlessPosts required statistically significantly higher force to be removed while there was no statistically significant difference between the Fiber White Posts and the DT Light Posts; therefore, the hypothesis was rejected.

Susceptibility of a polycaprolactone-based root canal filling material to degradation. Evidence of biodegradation from a simulated field test.

PURPOSE: To examine if Resilon, a polycaprolactone-based root filling material, was susceptible to microbial biodegradation by using a simulated field test that consisted of incubating the material in wet dental sludge under mesophilic and aerobic conditions. METHODS: Pressed disks prepared from Resilon, polycaprolactone (positive control) and gutta-percha (negative control) were incubated in wet dental sludge for up to 4 months and examined for topographical changes using scanning electron microscopy. RESULTS: Gutta-percha exhibited minimal changes in surface integrity, while polycaprolactone and Resilon exhibited severe surface pitting and erosion. In the latter, disappearance of the polymer matrix was accompanied by exposure of mineral and bioactive glass fillers. Bacteria and hyphae-like structures were present on the disk surfaces.

Upregulation of basic fibroblast growth factor in human periapical lesions.

Basic fibroblast growth factor is one of a class of heparin-binding growth factors that stimulates endothelial cell proliferation and migration in vitro and angiogenesis in vivo. The purpose of this study was to investigate the expression of basic fibroblast growth factor in chronic periapical lesions of endodontic origin. Ten chronic inflammatory periapical lesions were examined using immunohistochemical staining. The experimental control group consisted of four specimens of uninflamed periodontal ligament tissue. Two independent observers graded the staining intensity for basic fibroblast growth factor. An immunopositive, cytoplasmic, and nuclear reaction for basic fibroblast growth factor, with varying degrees of upregulation was observed in all 10 chronic periapical lesions. We speculate that the formation of granulation tissue and the activation of epithelial cell rests in chronical apical lesions might be associated with a local rise in the tissue level of basic fibroblast growth factor. Therefore, this growth factor could play an important role in the pathogenesis of chronic apical periodontitis and periapical cysts.

The impact of post space preparation with Gates-Glidden drills on residual dentin thickness in distal roots of mandibular molars.

BACKGROUND: Posts frequently are used to retain buildups. The authors examined the effects of post space preparation with Gates-Glidden drills on residual dentin thickness in distal roots of mandibular molars. METHODS: The authors embedded 26 root-treated mandibular molars in endodontic cubes and sectioned them perpendicularly to their long axis at 1.8-millimeter intervals. They placed Gates-Glidden drills nos. 3, 4, 5 and 6 sequentially to 5 mm short of working length in the distal canals. After using each drill size, the authors measured the dentin thickness from light microscopic images of the tooth slices. RESULTS: The authors analyzed data to detect changes resulting from canal instrumentation. They performed statistical analysis by partitioning the variability in a nested analysis of variance. Strip perforations occurred with a no. 4 Gates-Glidden drill 7.3 percent of the time and more frequently with larger drills. After endodontic treatment alone, the canal wall on the furcal side was less than 1 mm thick 82 percent of the time and less than 0.5 mm thick 17.5 percent of the time. CONCLUSIONS: Dentin thickness correlates inversely to post space diameter. A no. 4 Gates-Glidden drill caused strip perforations in 7.3 percent of the canals studied, and therefore the authors recommend that Gates-Glidden drills larger than a no. 3 not be used in these roots. After endodontic treatment, the furcation-side dentin thickness was less than 1 mm in 82 percent of the teeth. CLINICAL IMPLICATIONS: Post space preparation in mandibular molars carries significant risk of perforation. Post space in such teeth should be limited to the endodontically prepared canal.

The properties of Endocal 10 and its potential impact on the structural integrity of the root.

The purpose of this research was to determine if the use of Endocal 10 (previously called Biocalex 6.9) is associated with root fracture and to assess its sealability. Thirty-six freshly extracted, single canal human mandibular incisors were instrumented and randomly divided into two equal groups (n = 15). Canals in group A were obturated with vertically compacted gutta-percha and Sealapex, and those in group B were filled with Endocal 10 placed with a #25 Lentulo spiral per manufacturer's instructions. Two blinded investigators evaluated the teeth for fractures using transillumination and an operating microscope at 12 x magnification. Three of the fifteen samples filled with Endocal 10 had vertically fractured in half, whereas none of the teeth filled with gutta-percha had any evident fracture lines. The remaining teeth were tested for leakage via a fluid filtration model at 1 wk and 30 days postobturation. No leakage was found among any of the samples whether filled with gutta-percha or with Endocal 10 at either time interval. Statistical analyses were completed using Fisher's exact test (p = 0.023), which showed that there was a significant increase in chance of fracture when using Endocal 10 versus gutta-percha. The results indicate that, although Endocal 10 is able to seal the tooth as well as gutta-percha and sealer, there is a significant potential risk of root fracture.

An in vitro evaluation of the sealing ability of a new root-canal-obturation system.

In this study the sealing ability of a new urethane methacrylate resin-based sealer, EndoRez, was evaluated using a fluid-filtration model. Sixty-four single-rooted lower bicuspids were decoronated, instrumented, and divided into 3 groups of 20 each with 4 teeth used as controls. In group A, the roots were obturated with EndoRez and a single cone of gutta-percha, group B with AH Plus and a single cone of gutta-percha, and group C was obturated using gutta-percha with warm vertical compaction and AH Plus sealer. All specimens were allowed to set for 7 days in 100% humidity at 37 degrees C. The groups were compared for differences in the amount of leakage (mm/h) using a Chi-square test. The leakage of group A was significantly higher at p = 0.01 than the other two groups. There was no significant difference in leakage between groups B and C.

The crystallization of sodium hypochlorite on gutta-percha cones after the rapid-sterilization technique: an SEM study.

The purpose of this study was to identify the presence, crystallization, and subsequent removal of sodium hypochlorite crystals on gutta-percha cones after rapid sterilization. Seventy-two, fresh, standardized, gutta-percha cones were randomly selected. Each cone was observed under the scanning electron microscope and the elemental analysis machine before and after rapid sterilization using 5.25% and 2.5% sodium hypochlorite. Gutta-percha cones were rinsed after sterilization with 96% ethyl alcohol, 70% isopropyl alcohol, and distilled water independently to determine which of these agents removed the sodium-chloride crystals. There were no crystals present on the gutta-percha cones directly from the box. All gutta-percha cones had sodium-chloride crystals present after the rapid-sterilization technique using 5.25% and 2.5% sodium hypochlorite. However, the sodium-chloride crystals were removed by 96% ethyl alcohol, 70% isopropyl alcohol, and distilled water.

Effect of electronic apex locators on cardiac pacemaker function.

The purpose of this study was to assess the effects of five electronic apex locators on pacemaker function in vitro. A Biotronik Actros DR+ pacemaker was evaluated at maximum sensitivity on a flat bench top. The pacemaker lead, electronic apex locator, and oscilloscope were connected across a 150-ohm resistor. Pace monitoring was carried out with a Biotronik EPR 1000 programmer and a Tektronix TDS 220 2-channel digital real-time oscilloscope. Four of five electronic apex locators tested did not cause inhibition or interfere with normal pacemaker function. It seems that electronic apex locators can be used safely in patients with pacemakers.