Apical leakage after root canal filling with an experimental calcium hydroxide gutta-percha point

This study was an in vitro analysis of the apical seal of root canals filled with an experimental calcium hydroxide gutta-percha point. One hundred and ten recently extracted human permanent teeth with a single root were used. The root canals were biomechanically prepared, and some received a dressing of calcium hydroxide for 7 days. Root canals not dressed were filled by the lateral condensation technique with either regular gutta-percha or calcium hydroxide gutta-percha points. The dressed root canals were filled with the same sealers and regular gutta-percha points. The specimens were placed into a 2% methylene blue dye solution under vacuum, and the apical leakage was linearly evaluated. The experimental groups with calcium hydroxide dressing and the one with calcium hydroxide gutta-percha points exhibited significantly (p < 0.05) less leakage than the groups filled with regular gutta-percha points. The results obtained indicated that calcium hydroxide guttapercha points produced an improvement in the apical sealing quality of the root canal filling. Copyright © 1996 by The American Association of Endodontists.

Calcium hydroxide root canal sealers: Evaluation of pH, calcium ion concentration and conductivity

The calcium hydroxide ionization of four root canal sealers (Sealapex, CRCS, Sealer 26, and Apexit) was studied by measuring conductivity and pH and by conducting atomic absorption spectrophotometry. Samples 6 mm in diameter and 15 mm long were prepared from these sealers. After setting and 48 h storage in a desiccator, five samples of each material were placed in 50 mL distilled water and analysed after 0,1,2,4, 6 and 24 h and 5, 15 and 30 days. The results showed that Sealapex was the root canal sealer showing the highest pH, ionic calcium and total calcium values (P<0.05) throughout the experimental period, followed by CRCS, Apexit and Sealer 26.

Effect of different root canal sealers on periapical repair of teeth with chronic periradicular periodontitis

Teeth with induced chronic periradicular periodontitis in dogs were root canal treated. After the biomechanical preparation, using K files and 5.25% sodium hypochlorite as the irrigant solution, all root canals were dressed with an antibacterial dressing based on calcium hydroxide, which was left in place for 7 days. After this time, the root canals were obturated with lateral condensation of cold gutta-percha with either a calcium hydroxide root canal filling material (Sealapex) or a zinc oxide-eugenol sealer (Fill Canal). After 270 days, histopathological analysis showed better apical and periapical repair in the teeth obturated with Sealapex (P < 0.05).

Calcium hydroxide and a corticosteroid-antibiotic association as dressings in cases of biopulpectomy. A comparative study in dogs' teeth.

The subject of this paper was to study the behavior of the periapical tissues of dogs' teeth after biopulpectomy and dressing with calcium hydroxide or a corticosteroid-antibiotic association, before root canal filling with zinc oxide eugenol (ZOE) or Sealapex sealers. The teeth were overinstrumented and dressed for 7 days before the root canal filling. The animals were sacrificed 180 days after treatment and the specimens were prepared for morphological analysis. Specimens treated with Sealapex presented a higher number of cases with biological closure than ZOE. When the root canals were filled with ZOE, better results were observed with the use of the Ca(OH)2 dressing.

In vivo antimicrobial activity of 2% chlorhexidine used as a root canal irrigating solution

The aim of the present study was to evaluate the in vivo antimicrobial activity of 2% chlorhexidine gluconate (FCFRP-USP) used as a root canal irrigating solution in teeth with pulp necrosis and radiographically visible chronic periapical reactions. Culture techniques and measurement of the inhibition zone were used. Twenty-two root canals of incisors and molars of 12 patients were used. After accessing the canal, the first root canal sample was collected with two sterile paper points that were transferred to a tube containing reduced transport fluid. The root canal was instrumented using chlorhexidine solution. A small sterile cotton pellet was placed at the root canal entrance, and the cavity was sealed with zinc oxide-eugenol cement. The canals were maintained empty for 48 h. Three sterile paper points were then introduced to absorb the root canal fluid (second sample). One paper point was placed on an agar plate inoculated with Micrococcus luteus ATCC 9341 and incubated for 24 h at 37°C, and the other two were submitted to microbiological evaluation. Present in 10 cases at baseline, mutans streptococci was reduced by 100% at the second assessment. Treatment showed an efficiency of 77.78% for anaerobic microorganisms at the second assessment. These data suggest that chlorhexidine prevents microbial activity in vivo with residual effects in the root canal system up to 48 h. Copyright © 1999 by The American Association of Endodontists.

Connective tissue responses to calcium hydroxide-based root canal medicaments

Aim: The objective of the present study was to evaluate the tissue inflammatory response induced by calcium hydroxide pastes, with or without paramonochlorophenol and camphor. Methodology: Isogenic BALB/c mice were inoculated into the subcutaneous tissue with either 0.1 mL of a suspension of Calen, Calen with camphorated paramonochlorophenol, Calen with paramonochlorophenol, Calasept paste or phosphate-buffered saline (control). After 6, 12 and 24 h and 2, 3, 5, 7 and 15 days, three animals in each group were sacrificed and the excised lesions processed for histopathological evaluation of the inflammatory response. Events monitored and graded included the assessment of vascular congestion, oedema, haemorrhage, inflammatory infiltrate, necrosis and tissue repair. Results: The pastes induced an inflammatory response at every observation period, although the intensity, duration and extension of inflammation varied. Calen paste always produced an initial short-term inflammatory response whilst the other pastes produced extended reactions. All pastes allowed repair to take place by the end of the experimental period, although the speed of this process varied between the materials. Calen presented the best biocompatibility; the phenolic compound caused greater tissue response, which was even more severe in the absence of camphor. Calasept paste was damaging and the repair process slower. Conclusions: All calcium hydroxide formulations caused an inflammatory response. The severity and longevity of the responses varied between pastes as a result of the various antiseptic agents. Although irritating, repair was apparent with all formulations.

Reaction of dogs' teeth to root canal filling with mineral trioxide aggregate or a glass ionomer sealer

This study was conducted to observe the reaction of apical tissues of dogs' teeth after root canal filling with gutta-percha and mineral trioxide aggregate (MTA) or a glass ionomer (Ketac-Endo) as a sealer. The root canals were instrumented and filled by the lateral condensation technique with the sealers studied. Animals were killed 6 months later, and the specimens were removed and prepared for histological analysis. Results showed no inflammatory reaction of apical tissue and total closure of the apical foramen of all the teeth sealed with MTA. The teeth sealed with Ketac-Endo showed two cases of partial closure and different degrees of chronic inflammatory reaction. In conclusion, MTA exhibited better biological properties than Ketac-Endo. Copyright © 1999 by The American Association of Endodontists.

A comparison of molar root canal preparation using stainless-steel and nickel-titanium instruments

Fifty-four extracted human mandibular molars were embedded and sectioned at two levels. The reassembled mesial root canals were prepared with stainless-steel hand K-files (Flexofiles) and either Nitiflex or Mity nickel-titanium hand K-files using a push-pull anticurvature filing technique. Each of the three experimental groups contained 36 mesial canals randomly distributed. Superimposed pre- and postinstrumentation cross-sectional root images were magnified using a stereomicroscope and transferred to a computer for measurement and statistical analysis. The direction and extent of canal center movement were evaluated. At the apical level, the groups produced no significant difference of direction of canal center movement. In cervical sections, all groups tended to move in a distolingual direction. The three groups, however, produced no significant difference in the cervical sections in the extent of canal center movement. In apical sections, Nitiflex produced the least canal center movement. Copyright © 1999 by The American Association of Endodontists.

Evaluation of cell culture cytotoxicity of five root canal sealers

The cytotoxicity of four calcium hydroxide-based root canal sealers (Sealapex, CRCS, Apexit, and Sealer 26) and one zinc oxide-eugenol-based sealer (Fill Canal) was evaluated microscopically for morphological changes in rat peritoneal macrophages. The least cytotoxic sealer was Fill Canal, followed in increasing order of cytotoxicity by CRCS, Sealer 26, Apexit, and Sealapex. Copyright © 2000 by The American Association of Endodontists.

Mineral trioxide aggregate repair of lateral root perforations

This study was conducted to observe the healing process of intentional lateral root perforation repaired with mineral trioxide aggregate (MTA). Forty-eight root canals of dogs' teeth were instrumented and filled. After partial removal of the filling, an intentional perforation was made with a bur in the lateral area of the root. The perforations were repaired with MTA or Sealapex (control group). Histological analysis occurred 30 and 180 days after treatment. Results showed no inflammation and deposition of cementum over MTA in the majority of the specimens. In the 180-day period, Sealapex exhibited chronic inflammation in all the specimens and slight deposition of cementum over the material in only three cases. In conclusion, MTA exhibited better results than the control group. Copyright © 2001 by The American Association of Endodontists.

Radiographic evaluation of periradicular repair after endodontic treatment of dog's teeth with induced periradicular periodontitis

Eighty-four root canals of premolars from six dogs were left open for 7 days, and then sealed and followed for 45 days until periradicular periodontitis developed. The root canals were then treated endodontically using 5.25% sodium hypochlorite as the irrigating solution. After instrumentation, all root canals were filled with a calcium hydroxide-based antibacterial dressing (Calen PMCC or Calasept) that was left in place for 30 days. After this period the root canals were filled with gutta-percha cones and a root canal sealer (Sealapex or AH Plus)-group I: Calen PMCC + Sealapex; group II: Calasept + Sealapex; group III: Calen PMCC + AH Plus; and group IV: Calasept + AH Plus. Periapical radiographs of the teeth were made after root canal filling and after 90, 180, 270, and 360 days. Radiographic images were digitalized by scanning, and the Mocha program was used to measure the periapical lesions. Analysis showed that the lesions of groups I to III were statistically similar reduction in size, whereas group IV had a smaller reduction in lesion size (p < 0.05). Copyright © 2001 by The American Association of Endodontists.

Calcium hydroxide root canal dressing. Histopathological evaluation of periapical repair at different time periods.

The objective of this study was to evaluate periapical and apical repair using calcium hydroxide root canal dressings for different lengths of times in teeth with induced chronic periapical lesions. A total of 61 root canals of maxillary and mandibular premolars from 4 dogs were used. After mechanical preparation of the root canals using the crown-down technique, and 5.25% NaOCl as irrigating solution, the apical foramen was enlarged in all cases. A calcium hydroxide root canal dressing was applied. The control group did not receive a root canal dressing. The animals were killed at 7, 15 or 30 days. After histological preparation, serial sections were stained with hematoxylin-eosin and Mallory's trichrome. The best histopathological results occurred at 15 and 30 days, and the worst results occurred at 7 days and in the control group.

Diagnostic agreement of conventional and inverted scanned panoramic radiographs in the detection of the mandibular canal and the mental foramen.

The aim of this study was to evaluate the diagnostic agreement of conventional panoramic radiographs and their inverted scanned images in the detection of the mandibular canal and mental foramen. A total of 77 panoramic radiographs obtained from the files of totally edentulous patients were used. Digitization was done by means of a scanner with brightness and contrast adjustment, as well as image inversion. The extension of mandibular canal was divided into anterior, middle, and posterior regions, and the presence of a radiopaque line that characterized the mandibular canal was classified according to a 5-point confidence scale. The mental foramen was classified in 4 types: continuous, separated, diffuse, and unidentified. Both conventional and inverted scanned panoramic radiographs were evaluated by 3 calibrated implantologists at 2 distinct moments with a minimum interval of 10 days between them. Intraexaminer agreement was evaluated by Kappa statistics by point and by 95% confidence interval. Because the intraexaminer level of agreement was low, interexaminer agreements could not be carried out. The results showed a substantial (in 2 situations), moderate (in 16 situations), and fair (in 18 situations) intraexaminer agreement for mandibular canal and a substantial (in 1 situation), fair (in 1 situation), and moderate (in 10 situations) intraeaminer agreement for mental foramen. There were no statistically significant differences in most instances. In conclusion, the diagnostic agreement of conventional and inverted scanned panoramic radiographs for detection of mandibular canal and mental foramen was low.

Comparative study of MTA and other materials in retrofilling of pulpless dogs' teeth

This in vivo study compared the effect of mineral trioxide aggregate (MTA), IRM, Super EBA and ZOE in a puttylike consistency, used as retrofilling materials, in the healing process of periapical tissue of pulpless dogs' teeth submitted to a conventional retrofilling technique. Twenty-four premolars obtained from three dogs were used. At the first intervention, the animals were anesthetized, coronal access was obtained and pulpectomy was done. Root canals were kept open to the oral environment for 180 days to induce the formation of apical lesions. After surgical removal of the lesions with curettes, 2 mm of the apical root was cut out perpendicular to the long axis of the teeth, and root-end cavities were shaped with a low-speed round bur. The bone cavities were irrigated and dried, and the root-end cavities were filled with MTA, IRM, Super EBA and ZOE in a puttylike consistency. The bone cavities were passively filled with blood and flaps were sutured. The coronal access openings were cleaned and double-sealed with ZOE and amalgam. After 180 days, the animals were killed by anesthetic overdose, maxilla and mandible were removed and the pieces were processed for histomorphologic analysis. Data were evaluated blindly on the basis of several histopathologic events and the scores obtained were analyzed statistically using the Kruskal Wallis test. No significant differences were observed among MTA, Super EBA and IRM (p>0.05). However, ZOE had a significantly more negative influence on the apical healing (p<0.05). In conclusion, MTA, Super EBA and IRM had similar histopathologic effects among each other and better performance than ZOE used in a puttylike consistency. Furthermore, only MTA stimulated hard tissue deposition in direct contact with the retrofilling material, even when it was inserted under critical conditions.

Effects of copper vapor laser radiation on the root canal wall of human teeth: A scanning electron microscope study

Objective: The aim of this study is to analyze the effects of copper vapor laser radiation on the radicular wall of human teeth. Materials and Methods: Immediately after the crowns of 10 human uniradicular teeth were cut along the cement-enamel junction, a chemical-surgical preparation of the radicular canals was completed. Then the roots were longitudinally sectioned to allow for irradiation of the surfaces of the dentin walls of the root canals. The hemi-roots were separated into two groups: one (control) with five hemi-roots that were not irradiated, and another (experimental) with 15 hemi-roots divided into three subgroups that were submitted to the following exposure times: 0.02,0.05, and 0.1 s. A copper vapor laser (510.6 nm) with a total average power of 6.5 W in green emission, frequency of 16.000 Hz, and pulse duration of 30 ns was used. Results: The results obtained by scanning electron microscope analysis showed the appearance of a cavity in the region of laser beam impact, with melting, recrystallization, and cracking on the edges of the dentin of the cavity due to heat diffusion. Conclusions: We determined that the copper vapor laser produces significant morphologic changes in the radicular wall of human teeth when using the parameters in this study. However, further research should be done to establish parameters that are compatible with dental structure in order to eliminate thermal damages. © Mary Ann Liebert, Inc.