Innate Immune Responses of the Dental Pulp to Caries
Chin-Lo Hahn, MS, PhD, DDS, Frederick R. Liewehr, DDS, MS
Various cells and inflammatory mediators are involved in the initial pulpal responses to caries. This review focuses on the cellular, neuronal, and vascular components of pulpal innate responses to caries. Discussion will include dentinal fluid, odontoblasts, neuropeptides, and neurogenic inflammation, which are not classic immune components but actively participate in the inflammatory response as the caries progress pulpally. Summaries of innate immune cells as well as their cytokines and chemokines in healthy and reversible pulpitis tissues are presented.
Redefining the Persistent Infection in Root Canals: Possible Role of Biofilm Communities
Luis Chávez de Paz, DDS, MS, PhD
Current concepts suggest that persisting infections subsequent to endodontic therapy are caused by one or two bacterial species that are “too robust” to be eliminated by conventional treatment measures. As a consequence, numerous studies are exploring the characteristics of these “most” resistant organisms to define an effective treatment strategy to eradicate them from root canals. By taking an ecological perspective, the main objective of this review is to present evidence that the nature of persisting endodontic infections depends not on the robustness of the organisms in the infected site, but on their capability of adapting their physiology to the new environmental conditions set by the treatment. Changes in the environment, such as an increase in pH by calcium hydroxide or the effect of antimicrobials, are capable of triggering genetic cascades that modify the physiological characteristics of bacterial cells. Surface adherence by bacteria to form biofilms is a good example of bacterial adaptation and one that is pertinent to endodontic infections. Increasing information is now available on the existence of polymicrobial biofilm communities on root canal walls, coupled with new data showing that the adaptive mechanisms of bacteria in these biofilms are significantly augmented for increased survival. This ecological view on the persisting infection problem in endodontics suggests that the action of individual species in persisting endodontic infections is secondary when compared to the adaptive changes of a polymicrobial biofilm community undergoing physiological and genetic changes in response to changes in the root canal environment.
The Development of a Diagnostic Instrument for the Measurement of Mechanical Allodynia
Asma A. Khan, BDS, PhD, Bryce McCreary, DDS, Christopher B. Owatz, DMD, William G. Schindler, DDS, MS, Scott A. Schwartz, DDS, Karl Keiser, DDS, MS, Kenneth M. Hargreaves, DDS, PhD
Mechanical allodynia, defined as a reduction in mechanical pain threshold, is an essential diagnostic feature of inflammation of the periodontal ligament. Traditional methods for measuring mechanical allodynia in a tooth are not quantitative. This study evaluated the reliability of a new bite force transducer to measure mechanical pain thresholds, which might have application as a quantitative diagnostic aid for measuring mechanical allodynia in patients with apical periodontitis. To determine inter-observer reliability, subjects (n = 40) were given standardized instructions before generating maximal bite force on maxillary first molars; readings were then recorded by three examiners for a total of ten readings per examiner. To determine the test-retest reliability, the initial examiner then retested at two different sessions. The intraclass correlation coefficient was fair to substantial for inter-observer reliability (0.3-0.64) and substantial for intra-observer reliability (0.63-0.68). Thus, the force transducer used in our study is a reliable method to measure mechanical pain thresholds in endodontic patients.
Bacterial Reduction in Infected Root Canals Treated With 2.5% NaOCl as an Irrigant and Calcium Hydroxide/Camphorated Paramonochlorophenol Paste as an Intracanal Dressing
José F. Siqueira Jr, DDS, MSc, PhD, Karen M. Magalhães, DDS, Isabela N. Rôças, DDS, MSc, PhD
This clinical study investigated the bacterial reduction after instrumentation using 2.5% sodium hypochlorite (NaOCl) as an irrigant and further interappointment dressing with a calcium hydroxide (Ca(OH)2)/camphorated paramonochlorophenol (CPMC) paste. Eleven teeth with primary intraradicular infections and chronic apical periodontitis selected according to stringent inclusion/exclusion criteria followed in the study. Bacterial samples were taken before treatment (S1), after chemomechanical preparation using hand NiTi files and 2.5% NaOCl (S2), and following a 7-day medication with a Ca(OH)2 paste in CPMC (S3). Cultivable bacteria recovered from infected root canals at the three stages were counted and identified by means of 16S rRNA gene sequencing analysis. At S1, all cases harbored bacteria, with a mean number of 2.8 taxa per canal (range, 1–6). At S2, 6 of 11 (54.5%) of the cases yielded positive cultures, with one to three species per canal. At S3, only one case (9.1%) was positive for the presence of bacteria, with Propionibacterium acnes as the only taxon isolated. A significantly high reduction in bacterial counts was observed between S1 and S2, and S1 and S3. Significant differences were also observed for comparisons involving S2 and S3 samples with regard to both quantitative bacterial reduction (p = 0.029) and number of culture-negative cases (p = 0.03). It was concluded that chemomechanical preparation with 2.5% NaOCl as an irrigant significantly reduced the number of bacteria in the canal but failed to render the canal free of cultivable bacteria in more than one-half of the cases. A 7-day intracanal dressing with Ca(OH) 2/CPMC paste further significantly increased the number of culture-negative cases.
Microbial Leakage of Enterococcus faecalis After Post Space Preparation in Teeth Filled In Vivo With RealSeal Versus Gutta-Percha
Hugo Roberto Muñoz, DDS, MSc, Gustavo Adolfo Saravia-Lemus, DDS, Werner E. Florián, DDS, Julio F. Lainfiesta, DDS, MSc
The purpose of this study was to compare microbial leakage of Enterococcus faecalis after post space preparation in teeth filled in vivo with RealSeal (SybronEndo, Orange, CA) versus gutta percha. Twenty-six premolars in which extraction was indicated for orthodontic reasons were endodontically treated before extraction to simulate normal clinical conditions. Ten of these bicuspids were obturated following the RealSeal protocol; the other 10 were filled with gutta percha and Grossman-based formula cement. Post space was prepared immediately after filling leaving 5 mm of apical obturation material. The rest of the teeth were equally divided into the positive and negative control groups. Forty-eight hours later teeth were extracted and submitted to a dual-chamber leakage model using E faecalis. All of the RealSeal-filled teeth showed leakage during the first week, having a mean leakage of 3.5 days (±2.32 days). Gutta-percha–filled teeth showed a mean leakage of 10 days (±11.53 days). Mann-Whitney U comparison between groups revealed a p = 0.09. Under the conditions of the present study, there is no statistically significant difference in the microleakage of teeth filled with RealSeal compared with gutta percha when post space is prepared.
Clinical and Radiographical Evaluation of a Resin-based Root Canal Sealer: A 5-Year Follow-up
Osvaldo Zmener, DDS, Dr Odont, Cornelis H. Pameijer, DMD, DSc, PhD
A retrospective clinical and radiographical analysis of 5-year postendodontic treatment with a resin-based sealer (EndoRez; Ultradent Products Inc, South Jordan, UT) and gutta-percha was conducted. The results after 14 to 24 months were reported previously. Of 180 patients, 120 responded to the 5-year recall. Success of root canal treatments was based on absence of clinical symptoms, a normal or slightly widened periodontal ligament, and absence or reduction of periapical radiolucencies in patients who had preexisting lesions. Root canals had been adequately filled to the working length in 92 teeth (76.66%) and short in 13 (10.83%). Fifteen cases (12.50%), filled flush at the initiation of the experiment, showed slight resorption of the filling material at the apex within the lumen of the root canal. Of the 10 roots with extrusion, none had radiographic evidence of sealer in the periradicular tissues after 5 years. All patients were free of clinical symptoms. Four cases (3.3%) showed partial healing, whereas 8 cases (6.66%) were judged failures. A life table analysis revealed a cumulative probability of success of 86.3% at the 5-year recall with a 95% confidence interval of 79.7 to 91.0. The clinical and radiographical data suggest that the tested resin-based sealer used in conjunction with gutta-percha performed very well as a root canal sealer over a period of up to 5 years.
Pulp Revascularization of Immature Dog Teeth With Apical Periodontitis
Blayne Thibodeau, DMD, MS, FRCD(C), Fabricio Teixeira, DDS, MSc, PhD, Mitsuo Yamauchi, DDS, PhD, Daniel J. Caplan, DDS, PhD, Martin Trope, DMD
This study examined the ability of a collagen solution to aid revascularization of necrotic-infected root canals in immature dog teeth. Sixty immature teeth from 6 dogs were infected, disinfected, and randomized into experimental groups: 1: no further treatment; 2: blood in canal; 3: collagen solution in canal, 4: collagen solution + blood, and 5: negative controls (left for natural development). Uncorrected chi-square analysis of radiographic results showed no statistical differences (p ≥ 0.05) between experimental groups regarding healing of radiolucencies but a borderline statistical difference (p = 0.058) for group 1 versus group 4 for radicular thickening. Group 2 showed significantly more apical closure than group 1 (p = 0.03) and a borderline statistical difference (p = 0.051) for group 3 versus group 1. Uncorrected chi-square analysis revealed that there were no statistical differences between experimental groups for histological results. However, some roots in each of groups 1 to 4 (previously infected) showed positive histologic outcomes (thickened walls in 43.9%, apical closure in 54.9%, and new luminal tissue in 29.3%). Revascularization of disinfected immature dog root canal systems is possible.
Molecular- and Culture-based Comparison of the Effects of Antimicrobial Agents on Bacterial Survival in Infected Dentinal Tubules
Jerry Cook, DMD, Renu Nandakumar, PhD, Ashraf F. Fouad, BDS, DDS, MS
The aim of this study was to evaluate the effect of root canal obturation with or without prior calcium hydroxide (Ca(OH)2) or 2% chlorhexidine (CHX) on the persistence of bacteria or its DNA in infected dentinal tubules. Canals of 85 extracted teeth were instrumented and inoculated with 104 cells/mL of Enterococcus faecalis. Teeth were incubated at 37°C for 21 days and divided into 3 groups of 25 teeth plus controls. Teeth in group 1 were obturated immediately with gutta-percha (GP) and AH-Plus (Maillefer, Dentsply, Tulsa, OK). In group 2, Ca(OH)2 was placed for 7 days before obturation. In group 3, 10 minutes of irrigation was performed with CHX performed before obturation. After incubation, GP was removed, and dentin specimens were collected and analyzed with culturing and polymerase chain reaction (PCR). No growth occurred in any cultures. By using PCR, E faecalis was detected in fewer roots in group 3 than in groups 1 or 2 (χ2, p = 0.05); 2% CHX treatment followed by obturation was more effective in removing E faecalis DNA than placement of Ca(OH) 2 or immediate obturation.
Influence of the Type of Vehicle and Limit of Obturation on Apical and Periapical Tissue Response in Dogs’ Teeth After Root Canal Filling With Mineral Trioxide Aggregate
Roberto Holland, DDS, PhD, Lucimar Mazuqueli, DDS, MS, Valdir de Souza, DDS, PhD, Sueli Satomi Murata, DDS, PhD, Eloi Dezan Júnior, DDS, PhD, Patrícia Suzuki, DDS, MS
The purpose of this study was to investigate the influence of the type of vehicle (distilled water or propyleneglycol) on the response of apical tissues of dogs’ teeth after root canal filling with mineral trioxide aggregate (MTA) at two different limits. Forty roots of incisors and premolars of two adult dogs were used. After pulpectomy, the root canals were prepared biomechanically, and the roots had the apical cemental barrier penetrated with a #15 K-file and widened to a #25 K-file. The root canals were assigned to four groups according to the vehicle used for MTA (ProRoot-MTA; Tulsa Dental, Tulsa, OK) preparation and the limit of root canal filling: group 1, filling with MTA/distilled water to the limit of the cemental canal; group 2, overfilling with MTA/distilled water; group 3, filling with MTA/propyleneglycol to the limit of the cemental canal; and group 4, overfilling with MTA/propyleneglycol. The animals were killed by anesthetic overdose 90 days after endodontic treatment, and the anatomic pieces were prepared for histomorphological analysis. The sections were stained with hematoxylin and eosin and Brown and Brenn techniques. The results showed that MTA pastes prepared with either distilled water or propyleneglycol as vehicles had similar biological behavior (p > 0.05); root fillings placed at the cemental canal limit showed better results than the overfillings (p = 0.01), and MTA/propyleneglycol paste was more easily placed into the root canals than MTA/distilled water paste.
Eugenol Suppressed the Expression of Lipopolysaccharide-induced Proinflammatory Mediators in Human Macrophages
Ya-Yun Lee, DDS, Shan-Ling Hung, PhD, Sheng-Fang Pai, DDS, Yuan-Ho Lee, PhD, Shue-Fen Yang, DDS, MS
Eugenol is commonly used as an analgesic agent during acute pulpitis and is a major component of root canal sealers. Despite the frequent applications of eugenol in the practice of dentistry, little is known about the role of eugenol under the status of inflammation. This study was aimed to investigate the influence of eugenol on human macrophages (U937) under the stimulation of lipopolysaccharide (LPS). Eugenol was shown to block the release of the bone resorbing mediators, including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and prostaglandin E2 from LPS-stimulated macrophages. In contrast, eugenol alone did not alter the expression levels of these proinflammatory mediators in macrophages. Consistent with downregulation of bone-resorbing mediators, eugenol suppressed the messenger RNA expression of LPS-induced IL-1β, TNF-α, and cyclooxygenase-2 in macrophages. The results suggest a potential anti-inflammatory effect of eugenol in the acute inflamed pulps and apical periodontitis.
Expression of Mineralization Markers in Dental Pulp Cells
Xi Wei, MS, MDS, Junqi Ling, PhD, Liping Wu, MS, Lu Liu, MD, Yin Xiao, PhD
There is an increasing interest in the utility of dental pulp stem cells (DPSCs) for dentin regeneration. The mechanisms involved in DPSC differentiation remain poorly understood. The purpose of the study was to investigate the mineralization capacity of human dental pulp cells (DPCs) and identify potential markers for odontoblast differentiation. The isolated DPCs expressed mesenchymal stem-cell markers as shown by flow cytometry and could differentiate in vitro into odontogenic, adipogenic, and chondrogenic lineages. Alkaline phosphatase activity of DPCs elevated over time, with significant upregulation on day 21 in odontogenic induction. Quantitative RT-PCR revealed that osteocalcin, dentin sialophosphoprotein (DSPP), and matrix extracellular phosphoglycoprotein (MEPE) expression also increased time dependently in the induction cultures. In conclusion, we isolated DPCs with stem cell characteristics. MEPE and DSPP showed a similar regulatory pattern of DPCs mineralization. MEPE along with DSPP may be potential odontogenetic differentiation markers.
Correlation Between Platelet-derived Growth Factor B Chain and Bone Resorption in Rat Periapical Lesions
Li Wang, DDS, Bin Peng, DDS, PhD
The purpose of this study was to examine the relationship between platelet-derived growth factor B chain (PDGF-B) and bone resorption in rat periapical lesions. Periapical lesions were induced in Sprague-Dawley rats by occlusal exposure of the pulp of their mandibular first molars. Animals were sacrificed randomly at 0, 7, 14, 21, and 28 days after the exposure, and frontal sections were prepared for immunohistochemistry and enzymehistochemistry. PDGF-B–positive cells and osteoclasts could be observed on day 7. From day 7 to day 14, the number of PDGF-B–positive cells and osteoclasts were ascending, and a significant correlation was found between them; from day 21 to day 28, more PDGF-B–positive cells and fewer osteoclasts could be observed, and the positive expression of PDGF-B was negatively correlated with osteoclasts. These findings showed that PDGF-B could be observed, which might be associated with the bone resorption of periapical lesions.
A Scanning Electron Microscopy Evaluation of Microfractures, Deformation and Separation in EndoSequence and Profile Nickel-Titanium Rotary Files Using an Extracted Molar Tooth Model
Keven S. Herold, DDS, Bradford R. Johnson, DDS, MHPE, Christopher S. Wenckus, DDS
The development of microfractures in the EndoSequence nickel-titanium rotary (NTR) file (Brassler USA, Savannah, GA) and Profile NTR file was evaluated by using scanning electron microscopy (SEM). Seventy-three maxillary buccal roots and 53 mandibular mesial roots with an average canal curvature of 37° were randomly assigned to one of three groups and prepared with 21-mm .06 taper NTR files as follows: (1) EndoSequence at 300 rpm, (2) EndoSequence at 600 rpm, and (3) ProFile at 300 rpm. File sizes .45 to .20 were used in a crown-down technique to a master apical file (MAF) size of .35/.06. The MAF instruments were evaluated by SEM before use, after completion of 7 canals, and after completion of 14 canals. All EndoSequence instruments developed microfractures by the seven-canal evaluation. The ProFile instruments showed no microfractures at the 7- or 14-canal evaluations. EndoSequence files separated at a higher rate than ProFile instruments. Under the conditions of this study, unique file design and electropolishing did not inhibit the development of microfractures in EndoSequence NTR.
Evaluation of Chlorhexidine Toxicity Injected in the Paw of Mice and Added to Cultured L929 Fibroblasts
Gisele Faria, DDS, MSc, Mara R.N. Celes, MSc, Andiara De Rossi, DDS, MSc, Lea Assed B. Silva, DDS, PhD, João S. Silva, PhD, Marcos A. Rossi, MD, PhD
Because chlorhexidine (CHX) has been recommended as either an endodontic irrigant or root canal dressing, this study aimed to characterize, in vivo, the lesion induced by injections of CHX in the paw of mice at selected time intervals (24 and 48 hours and 7 and 14 days) and, in vitro, the mode of cell death, necrosis and/or apoptosis, and the cellular stress caused by exposition of cultured L929 fibroblasts to ascending concentrations of CHX for 24 hours. CHX injected in the subplantar space of the hind paw of mice induced severe toxic effects, as evidenced by necrotic changes in the epidermis, dermis, and subcutaneous tissue in association with reactive inflammatory response, particularly at higher concentrations. In addition, in cultured fibroblasts, CHX induced apoptosis at lower concentrations and necrosis at higher concentrations and increased expression of heat-shock protein 70, an indicator of cellular stress. Taken together, these findings suggest that CHX may have an unfavorable effect on the resolution of apical periodontitis.
Comparative Analysis of Endodontic Pathfinders
Michael J. Allen, DDS, Gerald N. Glickman, DDS, MS, Jason A. Griggs, PhD
Because no scientific literature exists regarding endodontic pathfinders, the aim of this study was to compare such instruments. Ten different pathfinder-type files were analyzed with respect to dimensional characteristics, pitch, and rigidity; efficiency, wear, and distortion were assessed by using an in vitro simulation exercise. SEM cross-sections and tip images were obtained and analyzed. To assess efficacy and distortion, 10 operators attempted to achieve patency with the files in small, S-shaped canals in acrylic blocks. Trends in canal negotiation efficiency and file distortion were recorded. Results showed that the Hi-5 (Miltex, York, PA) and C+ files (Dentsply/Maillefer, Johnson City, TN) were the least flexible, whereas the Pathfinder CS (SybronEndo, Glendora, CA) and Pathfinder SS (SybronEndo) files were the most. Pathfinder SS, S finder (JSDental/Sendoline, Ridgefield, CT), and D finder (Mani, Tochigi-ken, Japan) were the most efficient during the simulation exercise. Within the parameters of this study, pitch, taper, cross-section, heat tempering, metal type, tip geometry, and operator skills all influenced pathfinder efficiency.
Development of a Finite Element Analysis Model With Curved Canal and Stress Analysis
Ran Cheng, MDS, Xue-Dong Zhou, PhD, Zhan Liu, PhD, Tao Hu, PhD
This study aimed to establish a model of a curved canal by finite element analysis (FEA). To develop a repeatable and comparable model, simulated curved canals with uniform shape were selected as prototype canals, and a suitable extracted single-root tooth was chosen as the outline. Subsequent combinations and modifications were performed by using the analysis program ABAQUS. By using a series of imitational occlusive forces loaded onto the incisive edge of the model, color plots and the maximal stresses at the apical region were analyzed. Stresses increased when the angle of the loads rose, and loads in the distal and mesial directions induced more stresses in the target region than did loads in the buccal and lingual directions. This study has established a standardized FEA model with a curved canal. Consequently, this model may be applied for future estimations in endodontic procedures for a curved canal.
Effect of New Obturating Materials on Vertical Root Fracture Resistance of Endodontically Treated Teeth
Mohammad Hammad, MSc, Alison Qualtrough, PhD, Nick Silikas, PhD
The aim of this study was to compare vertical forces at fracture of teeth obturated with different materials. Single-rooted teeth were divided into five groups. The first group served as a negative control. The remaining four groups were shaped using ProTaper rotary files (Dentsply Maillefer, Ballaigues, Switzerland). The second group was obturated with gutta percha and a zinc oxide sealer. The third group was obturated with EndoRez points and EndoRez sealer (both from Ultradent, South Jordan, UT). The fourth group was obturated with Resilon (Pentron Clinical Technologies, Wallingford, CT) and RealSeal sealer (Pentron Clinical Technologies). The fifth group was obturated with Guttaflow (Colténe/Whaledent, Altstätten, Switzerland). Roots were then fixed into a universal testing machine and loaded with a spreader until fracture. It was found that forces at fracture were statistically significantly higher in the Resilon and EndoRez groups. It was concluded that obturation of roots with resin-based obturation materials (Resilon and EndoRez) increased the resistance of root canal filled teeth to vertical root fracture.
Effect of Clinical Use on the Cyclic Fatigue Resistance of ProTaper Nickel-Titanium Rotary Instruments
Hani F. Ounsi, DCD, DESE, MSc, FICD, Ziad Salameh, DCD, DESP, MSc, Thakib Al-Shalan, DDS, MSc, PhD, Marco Ferrari, MD, DDS, PhD, Simone Grandini, DDS, PhD, David H. Pashley, DMD, PhD, Franklin R. Tay, BDSc (Hons), PhD
The resistance of ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) nickel-titanium rotary instruments to cyclic fatigue was examined after their initial use in straight or curved canals in vivo. These instruments were rotated freely inside a steel phantom until separation. The number of rotations before failure and the lengths of the separated fragments were compared with data derived from new instruments under the same experimental setup (n = 20). With the exception of F1 and F3, instruments previously used in curved canals were more susceptible to cyclic fatigue than those previously used in straight canals (p < 0.05). Separation occurred predominantly at the D10 to D12 level. For the F series, a negative correlation (p < 0.05) was observed between the number of rotations before failure and the file diameters at their separation levels. ProTaper F3 instruments are highly susceptible to cyclic fatigue failure and should be reused with caution irrespective of whether they are initially used for shaping straight or curved canals.
New Tetrasilicate Cements as Retrograde Filling Material: An In Vitro Study on Fluid Penetration
Maria G. Gandolfi, PhD, Salvatore Sauro, DDS, Francesco Mannocci, MD, DDS, PhD, Timothy F. Watson, BSc, BDS, PhD, FDS, Silvano Zanna, PharmD, Michela Capoferri, PharmD, Carlo Prati, MD, DDS, PhD, Romano Mongiorgi, MS
We aimed to compare the apical sealing ability of two experimental retrograde root-filling cements and mineral trioxide aggregate using a fluid filtration method. X-ray diffraction (XRD) and X-ray fluorescence spectrometry (XRF) were used to evaluate structural and qualitative characteristics. Thirty single-rooted extracted teeth were treated, root-end prepared, and obturated using MTA and two experimental cements. Fluid filtration was measured during a 5-minute period after 4, 24, and 48 hours and 1, 2, and 12 weeks. The results were statistically compared by using a two-way analysis of variance (p < 0.05). The marginal adaptation was evaluated by using a SEM replica technique. XRD analyses showed similar patterns. XRF showed lower amounts of SiO2 and FeO3 in the experimental cements. All cements showed a reduced fluid flow rate over time. No significant differences were found between the cements. The SEM replica indicated a good marginal adaptation to dentinal walls. Both experimental cements showed suitable properties as retrograde root-filling materials.
Influence of Irrigating Needle-Tip Designs in Removing Bacteria Inoculated Into Instrumented Root Canals Measured Using Single-Tube Luminometer
Thilla Sekar Vinothkumar, BDS, Sanjeev Kavitha, MDS, Lakshmikanthanbharathi Lakshminarayanan, MDS, Narayanan Shivaram Gomathi, MSc, Vanaja Kumar, PhD
This study tested the mechanical efficacy of various irrigating needle tip designs on bacteria inoculated into instrumented root canals. Root canals of 30 extracted permanent canines were prepared to size 60 at working length (WL) using ProFile 0.04 taper rotary nickel-titanium files. Root canals were autoclaved and inoculated with a 20-μl suspension (1.4 × 107 cells) of genetically engineered Escherichia coli pYUB556. Bioluminescence was measured before inoculation (baseline), after inoculation and after irrigation with 6 ml of saline using luminometer. Safety-ended needles with single (group 1) and double (group 2) side-port and hypodermic needles (group 3) were used upto 1 mm short of WL. The percentage of bacteria remaining after irrigation was 67.9 ± 9.5, 75.3 ± 12.9 and 77.7 ± 11.8 respectively (p < 0.05; Kruskal-Wallis) with no difference between group II and group III (p > 0.05; Mann-Whitney). Irrigation using safety needles with single side port was significantly effective.
A Comparison of Gutta-Percha and Resilon in the Obturation of Lateral Grooves and Depressions
Nicole Alicia Karr, DMD, J. Craig Baumgartner, DDS, PhD, J. Gordon Marshall, DMD
The purpose of this study was to compare the flow of gutta-percha and Resilon (RealSeal; SybronEndo, Orange, CA) into lateral grooves and depressions in the apical 7 mm of a root canal by using warm vertical compaction. A split-tooth model was constructed with lateral grooves and depressions prepared at 1, 3, 5, and 7 mm from working length (WL). Groups A, B, and C were obturated with gutta-percha with a System B plugger placed 5 mm, 4 mm, and 3 mm from WL. Groups D, E, and F were obturated with Resilon with a System B plugger placed 5 mm, 4 mm, or 3 mm from WL. Gutta-percha and Resilon showed similar movement into lateral grooves and dentin depressions, with a significant difference found only with increased flow of gutta-percha into depressions at the 1-mm level when the System B plugger was placed 3 mm or 4 mm from WL (p ≤ 0.05).
Conventional Endodontic Therapy of Upper Central Incisor Combined with Cyst Decompression: A Case Report
Scott A. Martin, DDS
Treatment of a maxillary central incisor with an associated cystic lesion by conventional endodontic therapy combined with decompression is reported. Although small cystic lesions frequently heal simply with endodontic therapy, larger lesions may need additional treatment. If surgical enucleation is elected, other teeth or structures may be damaged unnecessarily. Therefore, a case can be made for first attempting the more conservative treatment of decompression, and a workable protocol for this is presented. In this case, 6 weeks with latex tubing in place and daily irrigation with 0.12% chlorhexidine led to complete healing with no need for further surgery or other root canal therapy on teeth initially surrounded by this lesion. At the 2-year recall, the lesion has completely resolved, and the adjacent teeth remain vital and normal.
An Aiming Device for an Extraoral Radiographic Technique
Chia-Hui Chen, BS, Shui-Hui Lin, BS, Hui-Lin Chiu, BS, Yu-Ju Lin, DDS, Yuk-Kwan Chen, DDS, MS, Li-Min Lin, DDS, MS, PhD,
To assist certain patient populations who are unable to tolerate intraoral films and/or sensors during endodontic therapy, an alternative technique (extraoral film placement) has been innovated by Newman and Friedman (2003). In this study, we devise and test a film/sensor-beam alignment aiming device for taking a periapical radiograph using this extraoral radiographic technique. An instrument is assembled from the following components: (1) two locator rings for bite-wing radiography, (2) two metal supporting indicator rods for bite-wing radiography, (3) a bite block for horizontal bite-wing radiography, and (4) a rubber tube of about 2 cm in length. Using our newly-devised aiming device to take periapical radiographs using the extraoral technique, appropriate images of the left upper and right lower molar areas for a series of 12 adult volunteers were successfully obtained. Angulation of the x-ray cone, with reference to the horizontal plane, was −20° to −30° and −10° to −15° for the upper and lower teeth, respectively. This study therefore shows that appropriate images can be easily obtained using this aiming device.