An In Vitro Evaluation of the Antibacterial Properties of Barriers Used in Guided Tissue Regeneration
Chogle and Mickel
pH Changes in Root Dentin after Intracanal Placement of Improved Calcium Hydroxide Containing Gutta-percha Points
Ho, Khoo, Tan, Teh, Lim and Sae-Lim
Proliferative Ability and Alkaline Phosphatase Activity with In Vivo Cellular Aging in Human Pulp Cells
Shiba, Nakanishi, Rashid, Mizuno, Hino, Ogawa and Kurihara
Bacteriological Evaluation of Passive Ultrasonic Activation
Spoleti, Siragusa and Spoleti
Comparative Analysis of Torsional and Bending Stresses in Two Mathematical Models of Nickel-Titanium Rotary Instruments: ProTaper versus ProFile
Berutti, Chiandussi, Gaviglio and Ibba
Properties of a New Injectable Type of Root Canal Filling Resin with Adhesiveness to Dentin
Imai and Komabayashi
Bacterial Concentrations Determine the Ability to Implant in the Root Canal System and Translocate to Lymph Nodes in Germ-free Mice
Maltos, Sobrinho, Silva, Nicoli, Carvalho, Vieira, and Farias
The Inhibitory Effect of Alendronate and Taurine on Osteoclast Differentiation Mediated by Porphyromonas gingivalis Sonicates In Vitro
Kum, Park, Yoo, Choi, Lee, and Lee
The Effect of Irrigation with Doxycycline or Citric Acid on Leakage and Osseous Wound Healing
Davis, Jeansonne, Davenport, and Gardiner
In Vitro Cytotoxicity of Medicated and Nonmedicated Gutta-percha Points in Cultures of Gingival Fibroblasts
Szep, Grumann, Ronge, Schriever, Schultze, and Heidemann
Differential Induction of Apoptosis by Capping Agents during Pulp Wound Healing
Kitamura, Ogawa, Morotomi, and Terashita
Antibiotic Susceptibility of Bacteria Associated with Endodontic Abscesses
Baumgartner and Xia
Interleukin-10 Receptor Expression in Human Dental Pulp Cells in Response to Lipopolysaccharide from Prevotella intermedia
Tokuda, Nagaoka and Torii
Antimicrobial Activity of Ca(OH)2 Dental Cements: An In Vitro Study
Morrier, Benay, Hartmann and Barsotti
An In Vitro Evaluation of the Antibacterial Properties of Barriers Used in Guided Tissue Regeneration
Sami Chogle, BDS, MSD and Andŕe K. Mickel, DDS, MSD
The inhibition of growth of Prevotella nigrescens and Enterococcus faecalis by three barriers membrane, (a) polytactic acid (Atrisorb®), (b) laminar bone, and (c) calcium sulfate, was compared using an agar diffusion test. The first group of 20 plates were inoculated with P. nigrescens in a prereduced anaerobically-sterilized brain-heart infusion broth, while the second group of 20 plates were inoculated with E. faecalis in a brain-heart infusion broth. On each plate, a 5.0-mm section of each barrier was placed such that every plate had all three barriers. The plates in the P. nigrescens group were incubated in an anaerobic chamber for 7 days. The plates in the E. faecalis group were incubated at 37°C for 2 days. No zones of inhibition were observed with laminar bone or calcium sulfate. Zones of inhibition were observed with the Atrisborb® barrier membrane in both groups. The zone of inhibition of P. nigrescens was significantly greater than the zone of inhibition of E. faecalis. The hydrophobicity of Atrisborb® and its N-methyl-2-pyrolidine component were suggested as the sources of its antibacterial activity.
pH Changes in Root Dentin after Intracanal Placement of Improved Calcium Hydroxide Containing Gutta-percha Points
Chew Han Ho, BDS, Angela Khoo, BDS, Russell Tan, BDS, Jennifer Teh, BDS, Kian Chong Lim, BDS, MSc, FAMS, and Varawan Sae-Lim, DDS, FAMS
The in vitro pH changes in root dentin over a period of 2 weeks was investigated in 48 extracted bicuspids after intracanal placement of either Roeko Calcium Hydroxide Plus Points, aqueous calcium hydroxide paste, or gutt-percha points (control group) after root canal preparation. Microelectrodes were placed in outer and inner root dentin at cervical, middle, and apical thirds of the root to measure the pH at 1 h, 2 h, 3 h, 1 day, 3 days, 7 days, and 14 days. Roeko Calcium Hydroxede Plus Points reached a peak inner dentine pH of 11.67 and a peak outer dentine pH of 10.82 at 3 h. In addition, Roeko Calcium Hydroxide Plus Points maintained an outer dentine ph above 9.5 for approximately 2 days, whereas the aqueous calcium hydroxide paste did not reach this pH. However, the alkalinity in dentin with Roeko Calcium Hydroxide Plus Points was maintained for 7 days only, whereas aqueous calcium hydroxide paste maintained an alkaline environment throughout the 2-week period.
Proliferative Ability and Alkaline Phosphatase Activity with In Vivo Cellular Aging in Human Pulp Cells
Hideki Shiba, DDS, PhD, Keiji Nakanishi, DDS, PhD, Fahmida Rashid, BDS, Noriyoshi Mizuno, DDS, PhD, Takamune Hino, DDS, PhD, Testsuji Ogawa, DDS, PhD, and Hidemi Kurihara, DDS, PhD
Little is known about the effect of aging on characteristic functions of pulp cells. When damaged pulp is recovered and mineralized tissue is formed to protect remaining pulp tissue, the general responses of pulp tissue after adequate stimuli (pulp cell proliferation and activation of alkaline phosphatase [ALPase]) are thought to be essential. In this study, we compared proliferative ability and ALPase activity between cultures of human pulp (HP) cells obtained from young and aged donors. The in vitro proliferative lifespan of HP cells from young donors was longer than HP cells from aged donors. Growth rates and ALPase activity of HP cells decreased with increasing donor age. These findings suggest that impaired repair of pulp and dentin in aged patients is partly due to a decrease in the proliferative ability and ALPase activity in aged pulp cells.
Bacteriological Evaluation of Passive Ultrasonic Activation
Pablo Spoleti, DDS, PhD, Martha Siragusa, DDS, PhD, and María Julia Spoleti, Bioch
The purpose of this study was to evaluate the influence of passive ultrasonic activation on root canal disinfection. Sixty human teeth (group A: upper incisors, group B: upper canines, and group C: distobuccal root of first upper molars) were selected and sterilized in an autoclave. A standardized inoculum was placed into the canals, and they were incubated for 72 h at 37°C. Then, they were divided into subgroup 1, which received sterile saline (SS) as an irrigant, and subgroup 2, which received sterile saline with passive ultrasonic activation (SU). The endodontic treatment was performed with a crown-down technique. Bacteriological identification of surviving colonies was carried out. Surviving colonies were higher when ultrasonics was not used (group A: SS: x 32.13, SU: x 13.53; group B: SS: x 53.70, SU: x 44.60; group C: SS: x 39.16, SU: x 29.40). The homogeneity proportion tests to compare the results of both subgroups showed that the surviving proportions were higher (p = 0.01) when the ultrasonic activation was not used.
Comparative Analysis of Torsional and Bending Stresses in Two Mathematical Models of Nickel-Titanium Rotary Instruments: ProTaper versus ProFile
Elio Berutti, MD, DDS, Giorgio Chiandussi, D Eng, PhD, Ivan Gaviglio, D Eng, and Andrea Ibba, D Eng
During root canal instrumentation, nickel-titanium rotary instruments are subjected to continual stresses inside the canal due to its anatomy and the hardness of the dentin they must cut. They must therefore be both stress-resistant and elastic. This study aimed to compare the mechanical behavior of two nickel-titanium rotary instruments (ProTaper and ProFile) by applying the finite element analysis method to produce a numerical evaluation. The nonlinear mechanical behavior of the alloy was taken into account during the study. The distribution of stresses due to torsional and bending moments was compared in the two experimental models. The PfoFile model was found to be more elastic than the ProTaper model. Under equal loads, the ProTaper model showed lower and better distributed stresses than the ProFile model.
Properties of a New Injectable Type of Root Canal Filling Resin with Adhesiveness to Dentin
Yohji Imai, PhD, and Takashi Komabayashi, DDS
The properties of a new, injectable type of root canal wall, adhesive filling resin, which we developed, were studied for its physical properties, adhesiveness to dentin and the root canal, and sealing ability. The new resin consisted of a powder composed of a specially selected poly(methyl methacrylate) and barium sulfate radiopacifier and liquid composed of methyl methacrylate monomer and tributylborane catalyst. A mixture of both components had a consistency suitable for injection. The physical properties, including radiopacity, were evaluated according to the ISO standard. The adhesiveness to dentin and the root canal was investigated by bond strength testing or by scanning electron microscopy. The apical sealing ability of the new resin was compared by a dye penetration test with that of gutta-percha/sealer. The findings of this study indicated that the new filling resin had physical properties satisfying all the ISO requirements for dental root canal sealing materials: a tensile bond strength to dentin of 7.3 MPa, a significantly better sealing ability compared with gutta-perch/sealer, the capability of forming resin tags in dentinal tubules, and removability.
Bacterial Concentrations Determine the Ability to Implant in the Root Canal System and Translocate to Lymph Nodes in Germ-free Mice
Sandra Maria de Melo Maltos, MSc, Antόnio Paulino Ribeiro Sobrinho, Msc, Fernanda Veloso Silva, MSc, Jacques Robert Nicoli, PhD, Maria Auxiliadora Roque de Carvalho, MSc, Leda Quercia Vieira, PhD, and Luiz de Macêdo Farias, PhD
The purpose of this study was to evaluate the influence of the infecting dose on bacterial colonization in root canal systems (RCS) and translocation to the submandibular lymph node (SML) of gnotobiotic (germ-free) mice. RCS were inoculated with 102 and 101 colony-forming units (CFU) of Enterococcus faecalis (ATCC 4083) or 105, 104, 103, and 102 CFU of Prevotella nigrescens (ATCC 33563). E. faecalis implanted in 83.3% of the cases, for both inocula. Translocation was detected in 58.3% of lymph nodes for the 102 CFU inoculum and in 33.3% of lymph nodes for the 101 CFU inoculum.P. nigrescens implanted in 25%, 16.7%, 8.3%, and 0%, for the 105, 104, 103, and 102 CFU inocula, respectively, and did not translocate at any of the concentrations used. These results indicate that E. faecalis was able to implant in the RCS and translocate to the SML, whereas P. nigrescens implanted in lower percentages in the RCS and did not translocate to the SML.
The Inhibitory Effect of Alendronate and Taurine on Osteoclast Differentiation Mediated by Porphyromonas gingivalis Sonicates In Vitro
Kee-Yeon Kum, DDS, PhD, Joo-Hyun Park, DDS, MSD, Yun-Jung Yoo, DDS, PhD, Bong-Kyu Choi, PhD, Hyun-Jung Lee, MA, and Seung-Jong Lee, DDS, MS
The objective of this study was to investigate the ability of alendronate and taurine in inhibiting in vitro osteoclasts differentiation induced by bacteria. Whole cell sonicates of Porphyromonas gingivalis were used as an osteoclasts-stimulating factor in a mouse coculture system and differentiated osteoclasts were confirmed by tartrate-resistant acid phosphatase (TRAP) staining. Alendronate at the concentrations of 10ˉ7 M, 10ˉ6 M, and 10ˉ5 M and taurine at the concentrations of 4 mM, 8 mM, and 12 mM were used. The cytotoxic effects of alendronate and taurine were examined using methyl-thiazole-tetrazolium bromide (MTT) assay. The amounts of interleukin-6 (IL-6) in culture supernatants were also measured using ELISA. The sonicates of P. gingivalis at the concentration of 0.01-0.1µg/ml significantly stimulated the formation of osteolclasts (p <0.05). Alendronate (10¯5 M) and taurine (12 mM) significantly suppressed the sonicate-stimulated osteoclasts formation. In MTT assay, no cytotoxic effects were evident in all concentrations of alendronate and taurine. Alendronate and taurine did not affect the amount of IL-6 induced by P. gingivalis sonicates. These data indicate that alendronate and taurine have inhibitory effects on bacteria-stimulated osteoclast formation in vitro and that this inhibitory mechanism in not related to the blocking of IL-6 production.
The Effect of Irrigation with Doxycycline or Citric Acid on Leakage and Osseous Wound Healing
Joanna L. Davis, DDS, MS, Billie G. Jeansonne, DDS, PhD, William D. Davenport, PhD, and Diana Gardiner, PhD
This study investigated the effect of doxycycline irrigation on wound healing and the apical seal of three filling materials. Part 1: 220 extracted teeth received root canal therapy followed by root resection (2 mm) and ultrasonic root end preparations (3 mm). Groups of 20 were irrigated with saline, citric acid, or doxycycline and filled with amalgam, Super EBA, or MTA. Leakage was measured (mm) after decalcification and clearing. Part 2: two defects were made on each side of the mandible of 10 New Zealand rabbits. On each side, one defect was irrigated with saline and one with either citric acid or doxycycline. The animals were killed in groups of five at 9 and 18 days. Sections of each defect were stained with hematoxylin and eosin for evaluation of healing and bone fill. Super EBA and MTA leaked significantly less than amalgam, regardless of irrigant. Leakage after irrigation with doxycycline compared to citric acid or saline was not significantly different for Super EBA or MTA but was lower for amalgam. There was no significant difference in healing or bone fill among irrigants at 9 or 18 days.
In Vitro Cytotoxicity of Medicated and Nonmedicated Gutta-percha Points in Cultures of Gingival Fibroblasts
Susanne Szep, Dr med dent, Ljiljana Grumann, Karin Ronge, Anette Schriever, Dr med dent, Myriam Schultze, Dr med dent, and Detlef Heidemann, Prof Dr med dent
This investigation was designed to test the cellular toxicity of two medicated (Roeko activ point and Roeko Calcium Hydroxide) and four nonmedicated brands of gutta-percha (GP) points (Antaeos, De-Trey White, Roeko color, and Roeko Top color). The test points were transferred into a culture medium including the GP-point material with a concentration of 6 mg/ml, and eluates were obtained after 72 h. Five milliliters of each eluate were pipetted onto fibroblast cultures, incubated, and subsequently stained. Mitotic rates, cell densities, and the distribution of normal cells, pathologically altered and dead cells were determined and correlated with control cell cultures. Roeko active point (containing chlorhexidine) resulted in the highest number of dead cells. The difference was statistically significant in comparison with all other materials. Concerning all parameters mentioned, the cytotoxicity of the points containing calcium hydroxide (Roeko Calcium Hydroxide) was not significantly different from all other points tested, with the exception of those containing chlorhexidine. All tested gutta-percha materials caused cytotoxic reactions in varying extents. Taking into consideration the limitations of an in vitro experiment, points containing calcium hydroxide and nonmedicated points containing calcium hydroxide and nonmedicated points seem to be the most recommendable products for clinical use.
Differential Induction of Apoptosis by Capping Agents during Pulp Wound Healing
Chiaki Kitamura, DDS, PhD, Yukio Ogawa, DDS, Takahiko Morotomi, DDS, and Masamichi Terashita, DDS, PhD
Effects of capping agents on two waves of apoptosis during pulp wound healing were examined. After cavity preparation of rat molars, cavities were filled with calcium hydroxide, zing oxide eugenol cement, or 4-META/MMA-TBB resin (4MMT) and some were unfilled. One hour or 1 day after filling, we examined the distribution and the number of apoptotic cells by terminal deoxynucleotidyl trans-ferase-mediated labeling (TUNEL) assay. One hour after filling, there were no differences in distribution patterns or the number of apoptotic odontoblasts among the four groups. One day after filling, we found differences in distribution patterns and the number of apoptotic pulp cells among the four groups. Especially in the 4MMT group, the distribution pattern of apoptotic cells was more broadly spread, and the number of apoptotic cells was significantly larger than those of other groups. These results suggest that capping agents may have an effect on pulp apoptosis and that 4MMT may actively induce apoptosis during pulp wound healing.
Antibiotic Susceptibility of Bacteria Associated with Endodontic Abscesses
J. Craig Baumgartner, DDS, PhD, and Tian Xia, DDS
Antibiotics to treat endodontic infections are routinely prescribed based on previously published susceptibility tests. There is increased concern that bacteria have increased resistance to the currently recommended antibiotics. The purpose of this investigation was to perform antibiotic susceptibility tests on a panel of bacteria recently isolated from endodontic infections. The bacteria in this study were aseptically aspirated with a needle from endodontic abscesses, cultivated, and identified at the species level. Each of the 98 species of bacteria was tested for antibiotic susceptibility to a panel of six antibiotics using the Etest. The antibiotics were penicillin V, amoxicillin, amoxicillin + clavulanic acid, clindamycin, metronidazole, and clarithromycin. The percentages of susceptibility for the 98 species were penicillin V: 83/98 (85%), amoxicillin: 89/98 (91%), amoxicillin + clavulanic acid: 98/98 (100%), clindamycin: 94/98 (96%), and metronidazole: 44/98 (45%). Metronidazole had the greatest amount of bacterial resistance; however, if it is used in combination with penicillin V or amoxicillin, susceptibility of the combination with penicillin V or amoxicillin increased to 93% and 99% respectively. Clarithromycin seems to have efficacy, but it is still considered an antibiotic under investigation because the minimum inhibitory concentration has not been established.
Interleukin-10 Receptor Expression in Human Dental Pulp Cells in Response to Lipopolysaccharide from Prevotella intermedia
Masayuki Tokuda, Shigetaka Nagaoka, and Mitsuo Torii
Interleukin-10 receptor (IL-10R) expression in human, dental pulp, fibrolblast cultures was investigated by using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique. After exposure to lipopolysaccharide (LPS) from Prevotella intermedia, the IL-10R mRNA levels increased after 4h, peaked at 7 h, and dropped back to the unstimulated level at 24 h. Maximal production of the IL-10R protein in dental pulp fibroblast cultures was detected by Western blot analysis after 12 h of LPS stimulation. In contrast, the human skin fibroblast (SF-MA) and human monocyte (U937) cell lines expressed IL-10R mRNA. Anti-CD14 antibodies inhibited P. intermedia LPS-induced IL-10R mRNA expression. These results indicate that P. intermedia LPS induces IL-10R gene expression in human, dental pulp fibroblasts in vitro.
Antimicrobial Activity of Ca(OH)2 Dental Cements: An In Vitro Study
Jean-Jacques Morrier, DDS, PhD, Geneviève Benay, Chrystel Hartmann, DDS, and Odile Barsotti, DDS, PhD
The effect of five commercial calcium hydroxide root canal medications (XR-SPAD, Calcicur, Hycal, Root-cal, Hypo-cal) and two calcium hydroxide mixtures (with water or glycerin) on the growth of (a) three anaerobic bacteria associated with endodontic infections; and (b) saliva bacterial strains was determined using the agar diffusion inhibitory test. Statistically significant zones of bacterial growth inhibition for all the bacteria tested were observed. Calcium hydroxide mixed with glycerin showed the largest zones of bacterial inhibition, whereas Root-cal was the least active. These results underline the necessity to evaluate the antibacterial potential of endodontic medications against the different bacterial strains commonly isolated from infected root canals.