Participation of Bacterial Biofilms in Refractory and Chronic Periapical Periodontitis
Noiri, Ehara, Kawahara, Takemura, and Ebisu
Adhesion of Endodontic Sealers to Dentin and Gutta-Percha
Lee, Williams, Camps, and Pashley
Biofilm Formation in Medicated Root Canals
Distel, Hatton, and Gillespie
Radiographic Evaluation of the Effect of Endotoxin (LPS) Plus Calcium Hydroxide on Apical and Periapical Tissues of Dogs
Filho, Leonardo, Bezerra Silva, and Assed
Loss of Hydroxyl Ions from Gutta-Percha Points with Calcium Hydroxide in Their Composition: An In Vivo Study
Azabal-Arroyo, Menasalvas-Ruiz, Martin-Alonzo, Hidalgo Arroquia, and Vega-del Barrio
Participation of Bacterial Biofilms in Refractory and Chronic Periapical Periodontitis
Yuichiro Noiri, DDS, PhD, Atsushi Ehara, DDS, PhD, Takashi Kawahara, DDS, Naoki Takemura, DDS, and Shigeyuki Ebisu, DDS, PhD
The aim of this study was to examine morphologically the participation of extraradicular biofilm in refractory periapical periodontitis. Six teeth and five extruded root filling gutta-percha points associated with refractory periapical periodontitis were investigated by scanning electron microscope.
In nine of 11 samples examined, bacterial biofilms were seen at the extraradicular area. The gutta-percha surface was covered with glycocalyx-like structures, and filaments, long rods, and spirochete-shaped bacteria were predominant in the extraradicular sites. Planktonic cells, which were filaments and spirochete-shaped bacteria, emigrated from the glycocalyx structures in some spots. In the extracted teeth, biofilm consisting of both bacteria and glycocalyx-like structures were observed on the periapical root surfaces. Next to the residual periodontal ligament, a few filaments, rods, and fusiforms were attached on the healthy cementum surface.
The present findings suggested that bacterial biofilms formed in the extraradicular areas were related to refractory periapical periodontitis.
Adhesion of Endodontic Sealers to Dentin and Gutta-Percha
Kwang-Won Lee, DDS, PhD, Michael C. Williams, BS, Jean J. Camps, DDS, PhD, and David H. Pashley, DMD, PhD
Adhesion of endodontic sealers to dentin and gutta-percha offers clues into their interaction with the wall of the root canal and the filling material. In this in vitro study, four classes of endodontic sealers (Kerr, a ZOE-based sealer; Sealapex, a calcium hydroxide-based sealer; AH 26, an epoxy resin-based system; and Ketac-Endo, a glass-ionomer based sealer) were compared for their ability to bond to dentin or gutta-percha. Flat coronal dentin or gutta-percha surfaces were created by using a diamond-impregnated saw blade. Aluminum cylinders (ca. 5-mm diameter) were stabilized on the substrates with small amounts of wax and then filled with one of the sealers. After setting in 100% humidity for 25 h, their tensile bond strengths were measured. Controls were the unfilled cylinders stabilized with wax. The bond strengths and modes of failure were measured. The results were statistically analyzed by using a two-way ANOVA (materials versus substrates) and Student-Newman-Keuls test at α = 0.05.
The results indicated that sealant bond strengths to dentin (from lowest to highest mean ± SD, n = 10) were: Kerr 0.13 ± 0.02; Sealapex 0.30 ± 0.08; Ketac-Endo 0.80 ± 0.24; AH 26 2.06 ± 0.53 MPa. The latter two were significantly different (p < 0.05) from the first two sealers and from themselves. The sealant bond strength to gutta-percha (from lowest to highest mean ± SD, n = 10) were: Ketac-Endo 0.19 ± 0.01; Sealapex 0.22 ± 0.01; Kerr 1.07 ±0.19; AH 26 2.93 ± 0.29 MPa. AH 26 gave the significantly highest bonds to gutta-percha.
Biofilm Formation in Medicated Root Canals
John W. Distel, DMD, MS, John F. Hatton, DMD, and M. Jane Gillespie, PhD
The hypothesis that Enterococcus faecalis resists common intracanal medications by forming biofilms was tested. E. faecalis colonization of 46 extracted, medicated roots was observed with scanning electron microscopy (SEM) and scanning confocal laser microscopy. SEM detected colonization of root canals medicated with calcium hydroxide points and the positive control within 2 days. SEM detected biofilms in canals medicated with calcium hydroxide paste in an average of 77 days. Scanning confocal laser microscopy analysis of two calcium hydroxide paste medicated roots showed viable colonies forming in a root canal infected for 86 days, whereas in a canal infected for 160 days, a mushroom-shape typical of a biofilm was observed.
Analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis showed no differences between the protein profiles of bacteria in free-floating (planktonic) and inoculum cultures. Analysis of biofilm bacteria was inconclusive.
These observations support potential E. faecalis biofilm formation in vivo in medicated root canals.
Radiographic Evaluation of the Effect of Endotoxin (LPS) Plus Calcium Hydroxide on Apical and Periapical Tissues of Dogs
Paulo Nelson-Filho, DDS, PhD, Mario Roberto Leonardo, DDS, PhD, Lea Assed Bezerra Silva, DDS, PhD, and Sada Assed, DDS, PhD
The aim of this study was the radiographic evaluation of the apical and periapical region of dog teeth submitted to intracanal bacterial endotoxin (lipopolysaccharide, LPS), associated or not with calcium hydroxide. After removal of the pulp, 60 premolars were divided into four groups and were filled with bacterial endotoxin (group 1), bacterial endotoxin plus calcium hydroxide (group 2), saline solution (group 3), or periapical lesions were induced with no treatment (group 4), for a period of 30 days. Similar periapical lesions were observed in groups 1 and 4. The lamina dura was intact in groups 2 and 3. Bacterial endotoxin (LPS) caused radiographically visible periapical lesions, but when associated with calcium hydroxide, this endotoxin was detoxified.
Loss of Hydroxyl Ions from Gutta-Percha Points with Calcium Hydroxide in Their Composition: An In Vivo Study
Magdalena Azabal-Arroyo, PhD, Gracia Menasalvas-Ruiz, PhD, Javier Martin-Alonzo, PhD, Juan Jose Hidalgo Arroquia, PhD, and Jose Maria Vega-del Barrio, PhD.
The aim of this study was to quantify variations in the pH of calcium-hydroxide, gutta-percha cones that had remained for 1 week inside the root canals of molars or premolars whose endodontic treatment could not be concluded in a single visit.
All teeth were instrumented and dried before the placement of the points. The cones were removed, and placed in vials with distilled water. Additional, new gutta-percha cones were also studied as a control. The pH was measured by a pH meter, model CRISON MicropH 2001. The average pH mensurations obtained for new, calcium-hydroxide, gutta-percha points was 10.11; for cones that were used 1 week, it was 7.08. There was a statistically significant difference observed between the two groups by the Student’s t test (p > 0.001). After 7 days, a significant decrease takes place in the alkalinity of these points.