Evaluation of the Apical Seal in Root Canals Prepared with a New Rotary System and Obturated with a Methacrylate Based Endodontic Sealer: An In Vitro Study
Osvaldo Zmener, DDS, Dr.Odont., Cornelis H. Pameijer, DMD, MScD, DSc, PhD, and Elsa Macri, DDS
The purpose of this study was to evaluate in vitro the apical seal of root canals prepared with a new rotary system, Anatomic Endodontic Technology (AET) and filled with a methacrylate based endodontic sealer and single gutta-percha cone and a lateral condensation technique, using the methacrylate based endodontic sealer/filler or Grossman’s cement. Thevroot canals of 45 freshly extracted human maxillary anterior teeth were prepared and then randomly assigned to three groups of 15 teeth each. After cleaning and shaping the teeth were obturated as follows: in group 1 the canals were filled with a methacrylate based sealer and a single gutta-percha cone; in group 2 the canals were filled using a lateral condensation technique with gutta-percha and the methacrylate based sealer; and in group 3, the canals were filled by means of lateral condensation of gutta-percha and Grossman’s cement (control group). The specimens were stored in 100% relative humidity at 37°C for 72 h, after which the coronal portion and the root surface of each tooth was covered with three layers of nail varnish and a final layer of sticky wax. After immersion in 2% methylene blue dye for 7 days, the specimens were imbedded in clear orthodontic resin and sectioned. Dye penetration was evaluated by an independent investigator using a stereo microscope. The results demonstrated that more pronounced leakage occurred in root canals obturated with the lateral condensation technique and Grossman’s cement (p ‹ 0.05). The least amount of dye leakage was observed for group 1 and 2 in which the methacrylate based sealer was used, either with a single gutta-percha cone or with lateral condensation of gutta-percha.
Effect of ProRoot MTA on Pulp Cell Apoptosis and Proliferation In Vitro
Sasan Moghaddame-Jafari, Maria G. Mantellini, Tatiana M. Botero, Neville J. McDonald, and Jacques E. Nor
ProRoot Mineral Trioxide Aggregate (MTA) has been indicated as a pulp capping material. The purpose of this study was to evaluate the effect of tooth-colored (white) MTA on pulp cell apoptosis and cell cycle. Mouse odontoblast-like cells (MDPC-23) and undifferentiated pulp cells (OD-21) were exposed to 0 to 100 mg MTA for 24 h. Propidium iodide staining followed by flow cytometry demonstrated that MTA did not induce apoptosis of MDPC-23 or OD-21 (p › 0.05). Cell cycle analysis showed that MTA induced a modest (but significant) increase in the percentage of MDPC-23 in the S and G₂ phases, and OD-21 in the S phase of cell cycle, as compared to untreated controls (p ≤ 0.05). In conclusion, MTA induced proliferation, and not apoptosis, of pulp cells in vitro. These findings suggest a potential mechanism to explain the regenerative effect observed in the dentin-pulp complex when MTA was used for direct pulp capping.
Three Canals in the Mesiobuccal Root of a Maxillary First Molar: A Case Report
David B. Ferguson DDS, MS, Kirby S. Kjar, DMD, Gary R. Hartwell, DDS, MS
This article describes the identification and treatment of a maxillary first molar exhibiting three canals in the mesiobuccal root. An 18-yr-old male patient presented for nonsurgical root canal therapy of tooth #3. After accessing the pulp chamber, and probing with 2.5× magnification, only one canal was located in the mesiobuccal root initially. Subsequent to troughing the groove between the mesiobuccal and palatal canals with a #2 round bur, two additional canals were located. An electronic apex locator was utilized to ensure a perforation of the pulpal floor had not occurred. A working film confirmed the presence of three canals in the mesiobuccal root, and the canals were cleaned, shaped, and obturated.
Selective Influence of Dentin Thickness upon Cytotoxicity of Dentin Contacting Materials
Kerstin Galler, DMD, DDS, Karl-Anton Hiller, PhD, Tobias Ettl, DMD, DDS, and Gottfried Schmalz, DMD, PhD, DDS
The effect of three dentin contacting materials on three-dimensional cultures of pulp-derived cells was evaluated in a dentin barrier test device. The test materials (Syntac Classic, Prompt L-Pop, Vitrebond) were applied on dentin disks of different thicknesses ranging from 100 to 500 µm. After 24 h of exposure with and without perfusion of the test chamber, cell survival was evaluated using the MTT assay and related to a nontoxic control material. Syntac Classic decreased cell activity significantly (p ≤ 0.0003), independently of the dentin thickness. For Prompt L-Pop and Vitrebond a significant influence of dentin thickness was found on the cell reaction. After exposure of the control material, photometric readings showed no dependency of the cellular reaction on dentin thickness (p › 0.05). It could be demonstrated that dentin acts as a barrier, decreasing the elicited cytotoxicity with increasing thickness. This effect is material related, showing little influence for the nontoxic or the glutaraldehyde containing material.
The Role of Apical Instrumentation in Root Canal Treatment: A Review of the Literature
Dean Baugh, DDS, and James Wallace DDS, MDS, MSD, MS
The issue of final apical preparation size remains controversial despite considerable clinical and in vitro research. The astute clinician must be aware of this research before choosing any instrumentation system because the informed clinician’s decision must be guided by the best available evidenced-based information. This review article generated a Medline-based search strategy to disclose these studies and provides a critique and summary of the results.
Neutrophil Elastase Levels in Periapical Exudates of Symptomatic and Asymptomatic Teeth
Nilgun Ozlem Alptekin, DDS, PhD, Hale Ari, DDS, PhD, Tamer Ataoglu, DDS, PhD, Seyfullah Haliloglu, VMD, PhD, Tuncay Alptekin, DDS, PhD, and Behic Serpek, VMD, PhD
The aim of this study was to determine neutrophil elastase levels (NE) in periapical exudates and to evaluate its relationship with clinical signs and symptoms of endodontically involved teeth. A total of 42 teeth with periapical periodontitis of 37 patients were clinically examined and spontaneous pain, swelling, pain on palpation or percussion, sinus tract formation and pus discharge were recorded. Additionally, periapical lesion size was measured on periapical radiographs. Periapical exudate samples were obtained during routine root canal treatment by using paper points. Enzyme levels were determined by spectrophotometric assays using the NE specific substrate N-methoxysuccinil-Ala-Ala-Pro-Val- p-nitroanilide. The teeth with signs and symptoms showed higher NE levels than the teeth without symptoms (p ‹ 0.05). The differences were significant when NE levels were presented as total amounts instead of concentration. This study demonstrated that NE in periapical lesions related with clinical symptoms and total enzyme amount may be more reliable mode of data presentation.
Anesthetic Effectiveness of the Supplemental Intraligamentary Injection, Administered with a Computer-Controlled Local Anesthetic Delivery System, in Patients with Irreversible Pulpitis
John Nusstein, DDS, MS, Elizabeth Claffey, DDS, MS, Al Reader, DDS, MS, Mike Beck, DDS, MA, and Joel Weaver, DDS, PhD
The purpose of this study was to determine the anesthetic effectiveness of the supplemental intraligamentary injection, administered with a computer-controlled local anesthetic delivery system, in mandibular posterior teeth diagnosed with irreversible pulpitis when the conventional inferior alveolar nerve block failed. Fifty four emergency patients, diagnosed with irreversible pulpitis of a mandibular posterior tooth, received an inferior alveolar nerve block and had moderate to severe pain upon endodontic access. A computer-controlled local anesthetic delivery system was then used to administer intraligamentary injections of 1.4 ml of 2% lidocaine with 1:100,000 epinephrine. Success of the intraligamentary injection was defined as none or mild pain upon endodontic access or initial instrumentation. The results demonstrated that anesthetic success was obtained in 56% (30 of 54) of the patients. We concluded that when the inferior alveolar nerve block failed to provide profound pulpal anesthesia in mandibular posterior teeth of patients presenting with irreversible pulpitis, the intraligamentary injection administered with a computer-controlled local anesthetic delivery system was successful approximately 56% of the time.
Reduction of Intracanal Bacteria Using GT Rotary Instrumentation, 5.25% NaOCl, EDTA, and Ca(OH)2
Robin McGurkin-Smith, DDS, MS, Martin Trope, DMD, Daniel Caplan, DDS, PhD, Asgeir Sigurdsson, DDS, MS
This study was conducted to determine the bacterial reduction using Profile GT® files and a strict irrigation protocol utilizing 5.25% NaOCl and EDTA. The additive antibacterial effect of Ca(OH)₂ was also evaluated. In addition, the study compared the bacterial reduction with the GT protocol versus larger instrumentation. Thirty-one subjects with apical periodontitis were recruited. Bacterial samples were taken upon access (S1), after instrumentation and a strict irrigation protocol (S2), and following ›1 wk of Ca(OH)₂ (SC). A log₁₀ transformation of colony forming units was done since sample bacterial counts are not normally distributed. At S1, 93.55% of canals sampled bacteria. At S2, 52.72% of the cases sampled bacteria. At SC, 14% of the cases cultured bacteria. The McNemar test showed a significant reduction (p ‹ 0.0009) in bacteria between S1 and S2. This was also true between S2 and SC (p ‹0.0019). It was concluded the GT protocol significantly reduced the number of bacteria in the canal but failed to render the canal bacteria free in more than half of the cases Ca(OH)₂ application significantly further reduced bacteria. Lastly, large apical instrumentation removed more bacteria than small apical instrumentation.
The Shaping Effects of Three Nickel-Titanium Rotary Instruments in Simulated S-Shaped Canals
Y. Yoshimine, DDS, PhD, M. Ono, DDS, and A. Akamine, DDS, PhD
The purpose of this study was to compare the shaping effects of three nickel-titanium rotary instruments, Pro-Taper, K3, and RaCe, with emphasis on canal transportation. Simulated canals with an S-shaped curvature in clear resin blocks were prepared with a torque-control, low-speed engine. Canals were prepared using the crown-down technique to the size of #30. Canal aberrations were assessed by comparing the pre- and postinstrumentation images under a stereomicroscope. ProTaper instruments caused greater widening of canals compared to K3 or RaCe. Furthermore, ProTaper files showed a tendency to ledge or zip formation at the end-point of preparation. These canal aberrations may be caused by ProTaper finishing files, which appear to be less flexible than other files of the same tip-size, because of their greater taper-size. These results suggest that nickel-titanium file systems including less tapered, more flexible instruments, like K3 and RaCe should be used in the apical preparation of canals with a complicated curvature.
MTA Solubility: A Long Term Study
Marcela Fridland, DDS, and Rafael Rosado, Chem Eng
The purposes of this long-term study was to assess the amount of soluble material released by Mineral Trioxide Aggregate to a water medium, to determine if the solubility differences between specimens of various water/ powder ratio, as demonstrated in a previous study, would be maintained over time, and to measure the pH of the water that was in contact with the specimens. Specimens were processed at 0.28 and 0.33 water/ powder ratios, and immersed in water according to the ISO 6876 standard. The specimens were periodically removed to assess salt content release and reimmersed in fresh water. Assay testing was periodically performed over a 78-day period. Results were expressed as Daily Solubility (solubility rate), and Cumulative Solubility. The mathematical projection from Cumulative Solubility to infinite time showed that MTA could solubilize 22.06% at 0.28 water/powder ratio, and 31.095% at 0.33 water/powder ratio of the specimens’ mass in regards to their initial dry weight. MTA did maintain a high pH for an extended period of time under these study conditions.
The Susceptibility of Starved, Stationary Phase, and Growing Cells of Enterococcus faecalis to Endodontic Medicaments
Isabelle Portenier, DDS, Tuomas Waltimo DDS, PhD, Dag Ørstavik DDS, PhD, Markus Haapasalo DDS, PhD
The purpose of this investigation was to compare the susceptibility of cells of Enterococcus faecalis during exponential growth, stationary phase and starvation phase to three endodontic medicaments. E. faecalis strains VP3-80 and A197A in different growth phases were exposed to saturated calcium hydroxide solution, 0.05% chlorhexidine digluconate and 0.0001% sodium hypochlorite. Cells in the exponential growth phase were the most sensitive to all three medicaments and were killed between 3 s and 10 min. Cells in stationary phase were more resistant and living cells could be recovered at 10 min. However, cells in starvation phase were the most resistant and were not totally eliminated by the medicaments during the 10-min test period. Number of surviving cells of E. faecalis cells to the tested medicaments increased 1000- to 10,000-folds in aging cultures.
Apical Anatomy in Mesial and Mesiobuccal Roots of Permanent First Molars
Il-Young Jung, DDS, PhD, Myoung-Ah Seo, DDS, MSD, Ashraf F. Fouad, DDS, MS, Larz S.W. Spångberg, DDS, PhD, Seung-Jong Lee, DDS, MSD, Hee-Jin Kim, DDS, PhD, and Kee-Yeon Kum, DDS, PhD
The purpose of this in vitro study was to investigate the canal configuration types, and the prevalence and location of anatomical variations in the mesiobuccal (MB) and mesial roots of permanent maxillary and mandibular first molars after instrumentation. The number and the type of canals were determined before instrumentation using conventional methods. All root canals from the 47 MB roots and 42 mesial roots were then instrumented to size #30 with ProFile .04 taper rotary instruments in a crown-down method and then filled with a single gutta-percha cone and sealer. Transverse 1 mm-thick cross-sections at 2, 3, 4, and 5 mm from the apex were obtained, stained and examined using a stereomicroscope. The canal configuration types and the prevalence and location of isthmi and accessory canals in roots with two canals were evaluated. The prevalence of two canals was 80.8% in the maxillary MB roots and 95.2% in the mandibular mesial roots. There were six types of canal configurations in the instrumented root apices. The prevalence of anatomical variations was highest at the apical 4 mm level, and was more frequent in mandibular first molars, and in roots with Weine type III canal. χ² test showed that the prevalence of the anatomical variations was statistically higher in the maxillary MB roots with Weine type III canals than in those with Weine type II canals (p < 0.05). Different canal configurations were often found at different levels in the same root. The results indicate that anatomical variations persist following instrumentation of roots with two canals in first molars. These anatomical variations should be considered during surgical or nonsurgical endodontic procedures of the permanent first molars.
The Expression of α₄ Integrins by Human Polymorphonuclear Neutrophils in Response to Sonicated Extracts of Enterococcus faecalis
WonJun Shon, DDS, MSD, SungSam Lim, DDS, PhD, Kwang-Shik Bae, DDS, PhD, SengHo Baek, DDS, PhD, and WooCheol Lee, DDS, PhD
This study was undertaken to investigate immunopathologic mechanism of Enterococcus faecalis in relation to persistent apical periodontitis. We monitored the expression levels of _4 integrin in human olymorphonuclear neutophils (PMNs) after stimulated with sonicated extracts of E. faecalis (SEF) and compared with lipopolycaccarides (LPS) of Escherichia coli for various incubation time. Venous blood was collected from healthy volunteers and then PMNs were isolated and cultured with various concentrations of SEF for different periods of time. The levels of α₄ integrin were measured by flow cytometry analysis. E. coli LPS group was used as a positive control and untreated PMNs as a negative control. Results showed that the expressions levels of α₄ integrin were increased in human PMNs stimulated with E. coliLPS in comparison with unstimulated control cells (p < 0.05). In case of SEF stimulated group, the expression levels were decreased in timedependent manner in comparison to E. coli LPS group (p < 0.05). Notably, after 12 h for incubation with SEF, the expression of α₄ integrin was decreased in dosedependent manner (p < 0.05). These findings suggest that E. faecalis seem to suppress PMNs recruiting activity by down-regulating α₄ integrin expression, providing the possible mechanism that E. faecalismay play a crucial role in persistent apical periodontitis.
A Systematic Review of In Vitro Retrograde Obturation Materials
Joanna N. Theodosopoulou, DDS, MSc, Richard Niederman, DMD, MS
The purpose of this review was two-fold: (a) to determine which retrograde obturation material(s) best prevents dye/ink penetration in vitro; and (b) to determine whether in vitro results agree with in vivo results. A MEDLINE search was conducted to identify in vitro studies published between January 1966 and October, week 4, 2003, conducted on human teeth, and published in English, German, or French language, testing the resistance to retrograde penetration of retrograde filling materials. The MEDLINE search identified 278 published articles. Of those, 115 studies examined the resistance to penetration of various retrograde filling materials, in vitro. Thirty-four studies met all the inclusion and validity criteria. The results indicate that, beyond 10 days in vitro, the most effective retrofilling materials, when measured by dye/ink penetration are: composites > glass ionomer cement > amalgam > orthograde gutta-percha > EBA. The results of these in vitro studies are not congruent with in vivo study results, suggesting a need to re-evaluate the clinical validity and importance of in vitro studies.