Dens Evaginatus: Literature Review, Pathophysiology, and Comprehensive Treatment Regimen
Marc E. Levitan, DDS, Van T. Himel, DDS
Dens evaginatus (DE) is an uncommon dental anomaly, having been well documented since 1925. It occurs primarily in people of Asian descent and is exhibited by protrusion of a tubercle from occlusal surfaces of posterior teeth, and lingual surfaces of anterior teeth. Tubercles have an enamel layer covering a dentin core containing a thin extension of pulp. These cusp-like protrusions are susceptible to pulp exposure from wear or fracture because of malocclusion, leading to pulpal complications soon after eruption. Endodontic intervention of permanent teeth with immature roots is unpredic for inflamed pulps, and leaves a tooth with compromised root structure when treating necrotic pulps. Efforts to ensure root maturity have involved preventive or prophylactic treatment with varying degrees of pulp invasiveness. Treatment options have changed as technology and materials have improved. The goal is to review the literature and pathophysiology regarding DE, and present a new comprehensive treatment regimen, including a truly prophylactic approach without pulpal invasiveness. A case study of a mestizo with DE is documented. Treatment of four affected mandibular premolars exhibiting three distinct diagnostic categories will illustrate various aspects of the treatment protocol presented, and tooth morphology of the anomaly is shown to aid clinical recognition.
Anatomical Study of C-Shaped Canals in Mandibular Second Molars by Analysis of Computed Tomography
Guang-Chun Jin, DDS, PhD, Seong-Jong Lee, DDS, PhD, Byoung-Duck Roh, DDS, PhD
The aim of this study was to investigate the prevalence and configuration of the C-shaped canal using serial axial computed tomography images of the mandibular second molars that had not been restored severely or treated endodontically, and to compare the thickness of the remaining tooth structure from the center of the canal to the outer surface of the deepest groove area in C-shaped mandibular second molar to that of ‘danger zone of perforation’ in normal mandibular second molar. This distance was measured at the cervical, middle, and apical third level each. From 220 teeth, C-shaped canals were found in 98 teeth (44.5%). Almost all the grooves were directed lingual (99%). The continuous C-shaped canal was the most frequently found (49%) and the separated canal was the least (17.4%). The thinnest remaining tooth structure in the groove area of the C-shaped mandibular second molar was not different from that of the danger zone of normal mandibular second molar at the three levels (p > 0.05).
Incidence of Instrument Separation Using LightSpeed Rotary Instruments
Kenneth I. Knowles, DDS, MS, Nathan B. Hammond, BA, Stephen G. Biggs, DDS, Jose L. Ibarrola, DDS, MS
The use of nickel-titanium rotary instrument systems has gained popularity over the past 10 years. One of these instrument systems is the LightSpeed (LightSpeed Technology, Inc, San Antonio, TX). One drawback for all nickel-titanium rotary instruments is the incidence of instrument separation. The purpose of this study was to evaluate the incidence of nonretrievable instrument separation using the LightSpeed system in a clinical setting. A total of 3543 canals were treated over a 24 month period and during that time, 46 LightSpeed instruments were separated and found to be nonretrievable, resulting in a separation rate of 1.30%. This rate was lower than previous reported studies.
Identification of Cultivable Microorganisms from Root Canals with Apical Periodontitis Following Two-Visit Endodontic Treatment with Antibiotics/Steroid or Calcium Hydroxide Dressings
Frederick C.S. Chu, BDS, MSc, PhD, W. Keung Leung, BDS, MDS, PhD, Peter C.S. Tsang, BDS, PhD, Tak W. Chow, BDS, MSc, PhD, Lakshman P. Samaranayake, BDS, DDS
The study was aimed at comparing the efficacy of disinfection of root canals with periapical radiolucencies when treated with either antibiotics/steroid medicaments (Ledermix or Septomixine) or a calcium hydroxide paste (Calasept). Microbiological samples were taken before and after two-visit endodontic treatment from 88 canals with apical periodontitis. All of the canals but one (87 of 88) had cultivable growth before treatment. After dressing with Ledermix, Septomixine, or Calasept, the percentages of canals remained with positive growth were 48% (13 of 27), 31% (8 of 26), and 31% (11 of 35), respectively. The χ2 tests showed there were no significant differences in the number of canals with positive growth or mean colony forming units counts after instrumentation, irrigation and dressing. In the Ledermix group, 38 strains of bacteria were recovered. The Septomixine group had 25 strains, and the Calasept group had 25 strains. Gram-positive facultative anaerobic cocci (including staphylococci and streptococci) were more prevalent than the Gram-negative obligate anaerobic rods after treatment in all three groups. Similarities in the reduced number of canals with residual growth, and the prevalence of Gram-positive facultative anaerobic cocci suggest that the use of different inter-appointment dressings produced similar microbiological outcomes. However, factors other than the antimicrobial effectiveness of intracanal medicaments may also be responsible for the results observed.
Role of IL-2 and Helper T-Lymphocytes in Limiting Periapical Pathosis
Masahiro Yamasaki, DDS, PhD, Taisuke Morimoto, DDS, Masahito Tsuji, DDS, PhD, Iwama Akihiro, DDS, PhD, Yoshinori Maekawa, DDS, PhD, Hiroshi Nakamura, DDS, PhD
The purpose of this study was to examine the role of IL-2 and helper T-lymphocytes in the development of periradicular lesions in rats. In control animals, periradicular lesions developed within 28 days following pulpal infection. Immunologically, some anti IL-2 and anti CD4-reactive helper T-lymphocytes infiltrated the periapical tissue at 14 days, and their numbers increased at 28 days. In experimental animals, tacrolimus (FK506) was injected every day to inhibit the IL-2 production by helper T-cells. Histologically, the pulpal necrosis and periradicular inflammation in tacrolimus-treated rats were more severe than those in the control rats. Furthermore, the areas of pulpal necrosis and periradicular lesion in the immunosuppressed rat were significantly greater than those in the normal ones. The numbers of IL-2- and CD4-positive cells in the lesion of the experimental rats were statistically lower than those of the control ones. These results show that the decrease in IL-2 might have promoted the development of periradicular lesions.
Examination of the Signal Transduction Pathways Leading to Upregulation of Tissue Type Plasminogen Activator by Interleukin-1α in Human Pulp Cells
Fu-Mei Huang, DDS, MS, Chung-Hung Tsai, DDS, MPH, Yi-Juai Chen, DDS, MSD, Ming-Yung Chou, DDS, PhD, Yu-Chao Chang, DDS, MS, PhD
Tissue type plasminigen activator (t-PA) is one of the important proteolysis factors in the pathogenesis of pulpal inflammation. However, the mechanisms and signal transduction pathways involved in the production of t-PA in human pulp cells are not fully understood. The purpose of this study was to investigate the t-PA activity in human pulp cells stimulated with various pharmacological agents. IL-1α was used to evaluate t-PA activity in human pulp cells using casein zymography and enzyme-linked immunosorbent assay (ELISA). Furthermore, to search possible signal transduction pathways, p38 inhibitor SB203580, MEK inhibitor U0126, and phosphatidylinositaol 3-kinase (PI3K) inhibitor LY294002 were added to test how they modulated the t-PA activity. The main casein secreted by human pulp cells migrated at 70 kDa and represented t-PA. Secretion of t-PA was found to be stimulated with IL-1α during 2 day cultured period (p < 0.05). From the results of casein zymography and ELISA, SB203580, U0126, and LY294002 significantly reduced the IL-1α-stimulated t-PA production, respectively (p < 0.05). Our findings demonstrated that IL-1α enhance t-PA production in human pulp cells, and the signal transduction pathways p38, MEK, and PI3K are involved in the inhibition of t-PA. SB203580, U0126, and LY294002 suppress t-PA activity and may also have important implication for pharmacological intervention.
Histological Study of Periradicular Tissue Responses to Uninfected and Infected Devitalized Pulps in Dogs
Louis M. Lin, BDS, DMD, PhD, Peter M. Di Fiore, DDS, MS, Jarshen Lin, BDS, DDS, Paul A. Rosenberg, DDS
Uninfected necrotic tissue, such as that which follows a myocardial or cerebral infarct, is capable of inducing an inflammatory reaction. Eventually, the infarct is organized by granulation tissue. Why then, does uninfected devitalized pulp tissue, such as in traumatized teeth, not cause periradicular inflammation and does not become organized by granulation tissue? Four beagle dogs were used in this experiment. A total of 48 teeth, which included 24 maxillary and 24 mandibular incisors, were aseptically devitalized, leaving residual pulp tissues in the root canals, and equally divided into two groups. Group A (24 uninfected): A sterile cotton pellet was placed deep into the canal orifice before the pulp chamber and access opening were closed with a layer of zinc-oxide eugenol cement followed by glass ionomer cement. Group B (24 infected): The teeth were left open to the oral cavity for 7 days and then closed with a cotton pellet and zinc-oxide eugenol and glass ionomer cement. The animals were sacrificed one year after the experiment and prepared for histological examination of periradicular tissue responses to uninfected and infected devitalized pulp tissues. The results indicate that uninfected devitalized pulp tissues did not continuously release inflammatory mediators and cause persistent periradicular inflammation over a period of one year. However, infected devitalized pulp tissues induced various degrees of periradicular inflammation. Only the apical few millimeters of uninfected devitalized pulp tissue in the root canals were organized by granulation tissue from vital periodontal ligament tissue.
Effects of Proinflammatory Cytokines on the Expression of Mineralization Markers and Heme Oxygenase-1 in Human Pulp Cells
Kyung-San Min, DDS, MSD, Young-Yim Kwon, DDS, MSD, Hwa-Jeong Lee, MSD, Sun-Kyung Lee, MSD†, Kyung-Hwa Kang, DDS, PhD, Suk-Keun Lee, DDS, PhD, Eun-Cheol Kim, DDS, PhD
The roles of IL-1α and TNF-α in early pulp inflammation were investigated by determining the alkaline phosphatase (ALP) activity, the osteonectin (ON), osteocalcin (OC), bone sialoprotein (BSP), and heme oxygenase-1 (HO-1) expression using an immunoblot method. Primary cultured dental pulp cells were treated with IL-1α, TNF-α, or both for 3, 7, and 14 days. The pulp cells treated with IL-1α for 3 days showed elevated ALP activity and increased ON, OC, and HO-1 expression, whereas TNF-α treatment did not increase the ALP activity and no BSP was expressed until day 14. The pulp cells treated with both IL-1α and TNF-α for 3 days showed increased HO-1 expression compared with that of the control. These data suggest that IL-1α and TNF-α produced in the early inflammatory reaction have different functions in human pulp cells. IL-1α induces ALP, ON, and OC in tooth mineralization and it may play a role in the cytoprotection of pulp cells via HO-1 expression, while long-term treatment of TNF-α may inhibit the tooth mineralization.
A Simple Etching Technique for Improving the Retention of Fiber Posts to Resin Composites
Francesca Monticelli, DDS, MSc, Manuel Toledano, MD, DDS, PhD, Franklin R. Tay, DDS, MSc, PhD, Fernanda T. Sadek, BDSc (Hons), PhD, Cecilia Goracci, DDS, MSc, PhD, Marco Ferrari, MD, DDS, PhD
Coupling of fiber posts to composites is hampered by absence of chemical union between epoxy resins and methacrylate-based resins. This study examined a clinically feasible protocol for creating micromechanical retention on the surface of fiber posts, using hydrogen peroxide etching to remove the surface layer of epoxy resin. This was followed by silanization of the exposed quartz fibers to enhance their chemical bonding to composites. Etching with 24% H2O2 for 10 min or 10% H2O2 for 20 min produced a 50 μm thick surface zone that is depleted of epoxy resin, leaving intact, undamaged quartz fibers for silanization. Low viscosity flowable composites were employed to infiltrate this zone, to simulate the creation of hybrid layers in acid-etched dentin by dentin adhesives. Interfacial strengths were enhanced with the adjunctive use of H2O2 etching and silanization, and were probably dependent on the ability of the flowable composites to completely infiltrate this interdiffusion zone.
A Comparison of Three Methods for Preparing Centered Platforms Around Separated Instruments in Curved Canals
Mian K. Iqbal, BDS, DMD, MS, Helena Rafailov, BS, Samuel I. Kratchman, DMD, Bekir Karabucak, DMD, MS
This study compared three methods for creating the most centered staging platform (SP) around separated instruments (SI) in curved canals. Green .04 ProFiles, notched at D3, were separated in the apical third of 42 mesiobuccal canals of maxillary and mandibular molars. Teeth were divided into three groups. SPs were prepared in group 1 with Gates Gliddens (GG) to a size #3; group 2 with LightSpeed to a size 90; and group 3 with incrementally cut rotary .06 ProFiles to size 82. Pre- and postoperative digital radiographs were imported into AutoCAD to measure the deviation of SP from the head of the separated instrument. Pearson’s correlation showed a positive relationship between deviation of the SP and the distance of the SI from the elbow of the canal. ANOVA showed that LightSpeed instruments were significantly more effective in preparing a centered staging platform around separated instruments in curved canals when compared to GG drills and ProFiles (p < 0.05).
Spreader Penetration During Lateral Compaction of Resilon and Gutta-Percha
Benjamin A. Nielsen, DMD, J. Craig Baumgartner, DDS, PhD
Resilon, a thermoplastic, polyester polymer–based filling material, is a new material used for sealing root canals after chemomechanical preparation. The purpose of this in vitro study was to compare nickel-titanium (NiTi) spreader penetration in root canals having a .04 taper preparation using .02 and .04 tapered master gutta-percha cones and .02 and .04 tapered master Resilon cones. Twenty canals, from extracted human teeth, were cleaned and shaped to a standardized 40/.04 size. Master cones of .02 or .04 tapered gutta-percha and .02 or .04 tapered Resilon were placed in each canal. A fine-fine NiTi spreader was then placed next to the master cone with a 1.5-kg force. The penetration depth was measured, subtracted from working length, and recorded. A significant difference in penetration depth (p < 0.01) was found for both taper of the cone and material used. The depth of spreader penetration from greatest to least was .02 tapered Resilon, .02 tapered gutta-percha, .04 tapered Resilon, and .04 tapered gutta-percha.
Cyclic Fatigue of Three Types of Rotary Nickel-Titanium Files in a Dynamic Model
James H. Yao, DMD, Scott A. Schwartz, DDS, Thomas J. Beeson, DDS
The cyclic fatigue resistance of three types of nickel-titanium rotary files was compared in a model using reciprocating axial movement. The influence of file size and taper was also investigated and fracture patterns were examined under SEM. The 10 experimental groups consisted of ProFiles, K3s, and RaCe files, size 25 in .04 and .06 tapers, as well as ProFiles and K3s, size 40 in .04 and .06 tapers. Each file was rotated freely at 300 rpm inside a stainless steel tube with a 60 degree and 5 mm radius of curvature. A continuous 3 mm oscillating axial motion was applied at 1 cycle per second by attaching an electric dental handpiece to the most inferior load cell of an Instron machine using a custom-made jig. The number of rotations to failure was determined and analyzed using analysis of variance and Tukey′s post hoc tests. Overall, K3 25/.04 files were significantly more resistant to cyclic fatigue compared to any other group in this study. In the 25/.04 category, K3s were significantly more resistant to failure than ProFiles and RaCe files. Also in the same category, ProFiles significantly outlasted RaCe files. In the 25/.06 group, K3s and ProFiles were significantly more resistant to failure than RaCe files, but K3s were not significantly different than ProFiles. In the 40/.04 and 40/.06 groups, K3s were significantly more resistant to cyclic fatigue than ProFiles. SEM observations demonstrated mostly a ductile mode of fracture. The results suggest that different cross-sectional designs, diameters, and tapers all contribute to a nickel-titanium instrument′s vulnerability to cyclic failure
The Effects of Sodium Hypochlorite (5.25%), Chlorhexidine (2%), and Glyde File Prep on the Bond Strength of MTA-Dentin
Ping Yan, DDS, PhD, Bin Peng, DDS, PhD, Bing Fan, DDS, PhD, Mingwen Fan, DDS, PhD, Zhuan Bian, DDS, PhD
The purpose of this study was to evaluate the effects of sodium hypochlorite (5.25%), chlorhexidine (2%), and Glyde File Prep on the bond strengths of MTA-dentin in vitro. Standardized dentin disks were prepared and the central hole in each disk was filled with mineral trioxide aggregate (MTA). The specimens were randomly divided into four groups to be immersed in saline, 5.25% NaOCl, 2% chlorhexidine, and Glyde File Prep for 2 hours. The bond strengths of MTA-dentin were measured with a material testing system (MTS) and the fractured surfaces on the root walls were observed by scanning electron microscopy. Compared with the control group, the bond strengths were significantly lower in Glyde File Prep group (p < 0.05) and there was no significant difference in the chlorhexidine group or in the NaOCl group (p > 0.05). This study suggested that Glyde File Prep could negatively affect the bond strengths of MTA-dentin.
Comparison of Defects in ProFile and ProTaper Systems after Clinical Use
Ya Shen, DDS, PhD, Gary Shun-pan Cheung, MDS, MSc, MS (FA), Zhuan Bian, DDS, PhD, Bin Peng, DDS, PhD
The purpose of this study was to compare the incidence and mode of instrument separation of the two nickel-titanium (NiTi) rotary systems that were used according to a predefined schedule of clinical use by the same group of operators. A total of 166 ProFile and 325 ProTaper instruments, discarded from this endodontic clinic over 17 months, was analyzed. The incidences of instrument separation were 7% for ProFile and 14% for ProTaper (p < 0.05). The proportion of unwinding defects was 5% in ProFile and 0.3% in ProTaper instruments (p < 0.01). Flexural fatigue was implicated in the majority of separations in both groups. The results of this study indicated that while ProTaper was more likely to separate without warning, ProFile tended to exhibit unwinding of flutes more frequently.
The Quantitative Evaluation of Apical Sealing of Four Endodontic Sealers
Funda Kont Cobankara, DDS, PhD, Hasan Orucoglu, DDS, PhD, Abdülkadir Sengun, DDS, PhD†, Sema Belli, DDS, PhD
The aim of this in vitro study was to evaluate the apical seal obtained with four root canal sealers: Rocanal 2, Sealapex, AH Plus, and RC Sealer. Forty root canals were prepared using the step-back technique. The specimens were divided into four groups of 10 samples and obturated by laterally condensed gutta-percha with one of the tested sealers. The computerized fluid filtration method was used for evaluation of apical sealing properties. The quantitative apical leakage of each specimen was measured after 7, 14, and 21 days. Statistical analysis indicated that the apical leakage of all sealers used in this study decreased gradually from 7 days to 21 days (p < 0.05). Sealapex showed better apical sealing than the other sealers at 7, 14, and 21 days (p < 0.05). RC Sealer, AH Plus, and Rocanal 2 showed similar apical leakage values at every period (p > 0.05).