Electrochemical corrosion in the failure of apical amalgam. Report of two cases

Effect of methods of evaluation on sealing ability of mineral trioxide aggregate apical plug

Aim:

The purpose of the study was to evaluate and compare the sealing ability of mineral trioxide aggregate (MTA) with three different methods.

Materials and Methods:

Forty single canal teeth were decoronated, and root canals were enlarged to simulate immature apex. The samples were randomly divided into Group M_D = MTA-angelus mixed with distilled water and Group M_C = MTA-angelus mixed with 2% chlorhexidine, and apical seal was recorded with glucose penetration method, fluid filtration method, and dye penetration methods and compared.

Results:

The three methods of evaluation resulted differently. The glucose penetration method showed that M_D sealed better than M_C, but difference was statistically insignificant (P > 0.05). The fluid filtration method resulted that Group M_C was statistically insignificant superior to Group M_D (P > 0.05). The dye penetration method showed that Group M_C sealed statistically better than Group M_D.

Conclusion:

No correlation was found among the results obtained with the three methods of evaluation. Addition of chlorhexidine enhanced the sealing ability of MTA according to the fluid filtration test and dye leakage while according to the glucose penetration test, chlorhexidine did not enhance the sealing ability of MTA. This study showed that relying on the results of apical sealing by only method can be misleading.

Evaluation of effect of addition of 2% chlorhexidine on the sealing ability of Biodentine: An in vitro study

Aim:

To evaluate the effect of the addition of 2% chlorhexidine on the sealing ability of Biodentine.

Materials and Methods:

Forty-six extracted human premolar teeth with single canal and apical foramen were selected, cleaned, and decoronated to standardize the length of 17 mm. Canals were prepared using ProTaper rotary files till size F4. The samples were divided into 2 experimental groups of 20 samples each on the basis of absence/presence of 2% chlorhexidine in liquid: Group B_M = Biodentine mixed with the provided liquid, Group B_C = Biodentine mixed with 2% chlorhexidine in provided liquid. Three samples, each were assigned to control groups: Group B_P (positive control) = No root end filling was placed, Group B_N (negative control) = Root ends were filled as in Group B_M, and entire external surface was coated with sticky wax. The samples were then evaluated for the apical sealing using fluid filtration method.

Results:

Results were analyzed using Student's t-test (P ≤ 0.05). Group B_C showed the better sealing ability (3.06) as compared to Group B_M (3.85). However, the difference was statistically insignificant (P > 0.05).

Conclusion:

Addition of 2% chlorhexidine to the liquid enhanced the sealing ability of Biodentine.

A systematic review of in vivo retrograde obturation materials

PURPOSE

The aim of this study was to answer the question: For patients requiring apicoectomy (apicectomy/root-end resection) and retrograde (root-end) obturation (filling), which retrograde obturation (root-end filling) material(s) is/are the most effective, as determined by reduction in periapical radiolucency and elimination of signs and symptoms?

MATERIALS AND METHODS

A MEDLINE and a Cochrane search (two specified searches) were conducted to identify randomised (RCT) and nonrandomised controlled clinical trials (CCT), cohort studies (CS) and case-control studies (CCS), published between 1966 and 2002, October week 4, conducted on humans, and published in English, German and French language, relating to retrograde obturation materials following apicoectomy.

RESULTS

The MEDLINE and the Cochrane search identified 324 and 21 published articles, respectively. The Cochrane search identified three additional articles to the MEDLINE-search articles. Fourteen studies met the inclusion criteria: two were RCTs, six were CCTs, none was a CS and six were retrospective CCSs. Nine of the 14 studies compared a new retrograde (root-end)-filling material to amalgam, 4 of the 14 studies compared orthograde root canal fillings to retrograde (root-end) amalgam and the fourteenth study compared variations of a resin composite (Retroplast) when used in combination with the bonding agent Gluma (Bayer AG, Gluma 1 and 2). The two RCTs indicated that glass ionomer cement appeared to be equivalent to amalgam. The six CCTs indicated that orthograde filling with gutta-percha and sealer was more effective than amalgam retrograde (root-end)-filling (one trial). Similarly, retrograde (root-end)-filling with (i) composite and Gluma (Bayer AG, Leverkusen, Germany) as bonding agent (one trial), (ii) reinforced zinc oxide eugenol cement (EBA cement) (Stailine, Staident, Middlesex, England; one trial) and (iii) gold leaf (one trial) appeared to be better than amalgam retrograde (root-end)-filling. Finally, gutta-percha retrograde (root-end)-filling appears to be less effective than amalgam (one trial) and Retroplast with ytterbium trifluoride is better than Retroplast with silver, when they are both used with Gluma as bonding agent (one trial).

CONCLUSIONS

For the highest level of evidence (RCT) retrograde (root-end)-filling with glass ionomer cement is almost as effective as amalgam. However, there was a significant caveat as there were only two RCTs. At the next highest level of evidence (CCT), and given the additional caveat that there was only one controlled trial for each material, retrograde (root-end) EBA cement, composite with Gluma and gold leaf, as well as orthograde gutta-percha, may be more effective than retrograde (root-end) amalgam filling. In conclusion, these results suggest that additional validating CCTs and RCTs are needed.

Scanning electron microscopic evaluation of finishing techniques on IRM and EBA retrofillings

Various techniques have been advocated for finishing retrofilling materials. This study evaluated marginal interfaces between tooth structure and the retrofilling material following three techniques of finishing IRM and EBA. This interface was evaluated for the presence of flash and for adaptation to the prepared canal walls. Thirty-one teeth were divided into six groups of five and one control. The teeth were instrumented to a minimum of a 35 K-file, obturated with gutta-percha, resected perpendicular to their long axes and ultrasonically prepared to receive a retrofilling. The teeth were filled with either IRM or EBA cement and finished by ball burnishing, burnishing with a moistened cotton pellet, or with a carbide finishing bur in a high-speed handpiece with air/water spray. Photomicrographs were made and examined by four evaluators. Retrofillings finished with a finishing bur displayed significantly better marginal adaptation and little evidence of flash when compared to the other techniques (p < 0.05). There were no significant differences between ball burnished or moistened cotton pellet techniques or between retrofilling materials used in this study (p < 0.05).

Sealing ability of cermet ionomer cement as a retrograde filling material

An in vitro dye leakage study was performed to compare the sealing ability of high copper amalgam with cavity varnish and cermet ionomer cement with and without varnish when used as retrofilling materials. The root canals of 54 maxillary anterior teeth were instrumented and obturated with gutta-percha and sealer. The apical 3 mm of the roots were resected and apical class I cavity preparations were made. The roots were then randomly divided into three groups and retrofilled with one of the experimental materials. After 72 h of immersion in India ink, the roots were cleared and evaluated for leakage with a stereomicroscope. Statistical analysis indicated that the cermet ionomer cement with varnish group had significantly less leakage than the amalgam group (P < 0.0014) and the cermet ionomer cement without varnish group (P < 0.001). There was no significant difference between the other two groups (P > 0.05).

Relation of pre- and intraoperative factors to prognosis of posterior apical surgery

The relation of preoperative and intraoperative factors to the prognosis of apical surgery was studied in 136 premolar and molar roots. The evaluated factors were: clinical signs and symptoms, size of the periapical lesion, root canal obturation, tooth restoration, apical retrofilling, and the operating surgeon. A significantly higher success rate was found in roots obturated 2 mm or shorter of the apex, in roots without post restoration, and after retrofilling of roots with apparently well-condensed obturation. The prognosis differed significantly following treatment by various operators but was unrelated to their experience.

Quantitative microleakage study on a new retrograde filling technique

An in vitro endodontic leakage model was used to compare the sealing ability of conventional retrograde amalgam fillings with a new retrograde filling technique by measuring dye leakage quantitatively. The new technique consisted of retrograde preparation of the root canal using the Endocursor, an endodontic handpiece. The canal was then filled with sealer and injection-moulded gutta-percha, using either the Hygenic Ultrafil system or the Unitek Obtura method. In both cases the gutta-percha was vertically condensed and subsequently cold-burnished. The two experimental groups and the amalgam group each consisted of 20 extracted human canine teeth and lower premolars. The results were analysed statistically by ANOVA and a Student-Newman-Keuls multiple comparison test. After 1 week at 37 degrees C, very little leakage was observed in the amalgam and gutta-percha groups. After a second week, during which leakage was enhanced by gas pressure, leakage in the amalgam group was significantly greater than that in the gutta-percha groups (P less than 0.01). There were no significant differences between the two experimental gutta-percha groups. It is concluded that the new retrograde filling technique causes less leakage than the conventional amalgam retrograde filling technique in an in vitro model.

The comparative leakage behavior of reverse filling materials

This study compares the in vitro apical seal achieved with thermoplasticized gutta-percha used with and without a sealer cement and that achieved with dental amalgam and a varnish liner following an apicoectomy and a Class I preparation of single root teeth. The teeth were immersed in methylene blue dye for 10 days, were sectioned longitudinally, and the amount of leakage was determined. No difference in leakage was found between the apical seals achieved with thermoplasticized gutta-percha used with a sealer cement and that obtained with dental amalgam with varnish. The leakage found with thermoplasticized gutta-percha used without a sealer cement was significantly greater.