Microleakage of retrograde fillings--a comparative investigation between amalgam and glass ionomer cement in vitro

Biocompatibility of furcal perforation repair material using cell culture technique: Ketac Molar versus ProRoot MTA

OBJECTIVE

The objective of this study was to evaluate the cytotoxicity of furcal perforation repair materials, GI and MTA, using cell culture technique.

STUDY DESIGN

The extract of ProRoot MTA and Ketac Molar were treated on PDL cells in a 96-well tissue-culture plate. Cell proliferation after an incubation period of 3 days was determined by using MTT assay.

RESULTS

The growth of cultured human periodontal fibroblast cells were suppressed by both perforation repair materials. The percent of cell viability in the Ketac Molar group was lower than in the ProRoot MTA group (P = .000).

CONCLUSIONS

Although Ketac Molar has the advantage of adhering to dentine, it is more cytotoxic to the PDL cells than MTA. In selecting the perforation repair material, it is recommended not only to consider the sealing ability of the material with dentine but also the biocompatibility of material to the underlying tissue.

A Systematic Review of In Vitro Retrograde Obturation Materials

The purpose of this review was two-fold: (a) to determine which retrograde obturation material(s) best prevents dye/ink penetration in vitro; and (b) to determine whether in vitro results agree with in vivo results. A MEDLINE search was conducted to identify in vitro studies published between January 1966 and October, week 4, 2003, conducted on human teeth, and published in English, German, or French language, testing the resistance to retrograde penetration of retrograde filling materials. The MEDLINE search identified 278 published articles. Of those, 115 studies examined the resistance to penetration of various retrograde filling materials, in vitro. Thirty-four studies met all the inclusion and validity criteria. The results indicate that, beyond 10 days in vitro, the most effective retrofilling materials, when measured by dye/ink penetration are: composites>glass ionomer cement>amalgam>orthograde gutta-percha>EBA. The results of these in vitro studies are not congruent with in vivo study results, suggesting a need to re-evaluate the clinical validity and importance of in vitro studies.

The use of glass ionomer cements in both conventional and surgical endodontics

The capacity to bond to dental tissues, especially to dentine, their long-term fluoride release and their biocompatibility make glass ionomer cements (GICs) advantageous for use in endodontics, as well as in restorative dentistry. This review provides information on the basic properties of GICs, such as adhesion, antimicrobial effects and biocompatibility, particularly as they relate to use in endodontics. Indications for the use of GICs in endodontics are orthograde root canal sealing, root-end filling, repair of perforations and root resorption defects, treatment of vertical fractures and maintenance of the coronal seal. The paper includes a review on each of these indications. It is concluded that in spite of the critical handling characteristics and the inconclusive findings regarding sealing ability and antimicrobial activity, there is substantial evidence to confirm their satisfactory clinical performance. Both soft tissue and bone compatibility make them suitable for use during endodontic surgery.

Biocompatibility of dental materials used in contemporary endodontic therapy: a review. Part 2. Root-canal-filling materials

Root-canal-filling materials are either placed directly onto vital periapical tissues or may leach through dentine. The tissue response to these materials therefore becomes important and may influence the outcome of endodontic treatment. This paper is a review of the biocompatibility of contemporary orthograde and retrograde root-canal-filling materials.

Effect of an acid environment on leakage of root-end filling materials

One hundred fifty-six single-rooted human extracted teeth received root canal treatment, apicoectomy, and ultrasonic root-end preparations. The roots were divided into six groups of 24 teeth. The groups were filled with Amalgam, Geristore, Super-EBA, Mineral Trioxide Aggregate (MTA), Calcium Phosphate Cement (CPC), or MTA with CPC matrix, respectively. Immediately after root-end filling, 12 teeth from each group were exposed to a pH of 5.0 for 24 h, and 12 teeth were exposed to a pH of 7.4 for 24 h. Twelve teeth served as controls. All teeth were exposed to Pelikan Ink for 5 days and cleared. Linear dye leakage was recorded. Data were statistically analyzed. An acid pH significantly reduced dye leakage of Geristore (0.67 vs. 3.93 mm) and MTA with CPC matrix (0.54 vs. 2.41 mm), whereas leakage of all other materials was not affected by pH. In conclusion an acid environment did not hinder the sealing ability of any of the materials tested, and enhanced the sealing ability of Geristore and MTA with CPC matrix.

Sealing ability of amalgam, super EBA cement, and MTA when used as retrograde filling materials

OBJECTIVE

To compare apical microleakage of MTA following reverse retrograde root filling with that following amalgam and EBA retrofilling.

DESIGN

Prospective random control trial.

SETTING

It was conducted at the University of Jordan in 1998.

MATERIALS AND METHODS

The root canals of 79 extracted teeth were instrumented and obturated with vertically condensed gutta-percha. Each tooth was apically resected and the apex was prepared ultrasonically to 3 mm depth and the root surface isolated with nail varnish. Teeth were divided randomly into three groups of 25 teeth each. First group was retrofilled with amalgam, second group with EBA and the third group with MTA. Following immersion in 1% methylene blue dye for 72 hours, the roots were sectioned and the depth of dye penetration was evaluated by a stereomicroscope at x10 magnification.

INTERVENTIONS

Super EBA is a reinforced zinc oxide cement based on a mixture of 32% eugenol and 68% ethoxy benzoic acid (EBA). MTA is a mineral trioxide aggregate cement (MTA) based on a mixture of sterile water.

MAIN OUTCOME MEASURES

The sealing effectiveness of the retrograde filling materials used in this study was determined by their ability to inhibit dye penetration.

RESULTS

56% of the group filled with amalgam and 20% of the group filled with EBA showed dye leakage beyond the retrofilling material whereas the MTA group showed none, two samples from MTA group were eliminated because of their fractured roots. The chi-squared test revealed a statistically significant difference among all three groups (P < 0.05).

CONCLUSION

MTA cement provides a better seal than amalgam and EBA cement when used as retrograde filling, but the extrapolation of this result into a clinical practice may be questionable.

Root end filling materials: a review

When non-surgical attempts prove unsuccessful or are contraindicated, surgical endodontic therapy is needed to save the tooth. The procedure usually consists of exposure of the involved area, root end resection, root end preparation and insertion of a root end filling material. Numerous materials have been suggested as root end filling materials. This article is a review of the literature on the suitability of various root end filling materials based on their leakage assessment, marginal adaptation, cytotoxicity, and usage test in experimental animals and humans.

Radiopacity of potential root-end filling materials

OBJECTIVES

In recent years various root-end filling materials have been suggested for clinical use. The purpose of this study was to assess the radiopacity of some potential materials according to ISO specification 6876.

STUDY DESIGN

Radiographs were taken of 1-mm thick specimens of eight materials (amalgam, Kalzinol, IRM, Super EBA, Vitrebond, Fuji II LC, Chemfil, gutta-percha); light transmission was assessed densitometrically and related to equivalent thickness of aluminum.

RESULTS

Commercial glass ionomer cements (Vitrebond, Fuji II LC, Chemfil) had radiopacities below the international standard for root canal sealers (< 3-mm aluminum); three zinc oxide-eugenol cements (Kalzinol, Super EBA, IRM) had radiopacities equivalent to 5 to 8 mm aluminum; and gutta-percha had a radiopacity equivalent to 6.1-mm aluminum.

CONCLUSIONS

We recommend that root-end filling materials should have a radiopacity greater than that for root canal sealers.

Evaluation of the seal of various amalgam products used as root-end fillings

Different formulations of amalgam have physical properties that may make them behave differently in the often-contaminated root end environment. Five different brands of amalgam were evaluated for microleakage of root-end fillings placed in extracted human teeth. These included a zinc-free spherical amalgam, a zinc-free admixture amalgam, two zinc-containing admixture amalgams, and a zinc-containing lathe-cut amalgam. The amalgams were placed either into dry root-end preparations or into preparations contaminated with human blood. The fluid filtration method was used to measure microleakage at 1, 2, 4, 8, 12, and 24 wk after placement. Analysis of variance revealed significant differences in the rates of microleakage at every measurement period. Scheffé's test showed that the zinc-free spherical amalgam had significantly greater leakage than all the other products evaluated. There were no significant differences between any of the other products. Blood contamination did not adversely affect the seal of any amalgam.

The effect of retrograde cavity design on microleakage of amalgam fillings

A phantom head model was modified to simulate as closely as possible the limited access encountered during periapical surgery on maxillary anterior teeth. Extracted human maxillary anterior and mandibular canine teeth were placed in this model in a standardized position for root resection, retrograde cavity preparation and filling with amalgam. Three different designs of retrograde cavities were evaluated: the conventional class 1 cavity, the slot cavity and a previously unreported approach, the funnel cavity. Upon completion of the retrograde filling, the teeth were removed from the model and subjected to microleakage tests by placing radiolabelled lipopolysaccharide in a reservoir created coronal to the retrograde fillings. Leakage was quantified by measurement of radioactivity in scintillation counter. It was found that the retrograde fillings in the funnel cavity leaked significantly less than those in the other two cavity designs. There was no statistically significant difference in leakage between the conventional class 1 and the slot cavities up to the thirtieth day 30.

A comparison of tissue reactions to Ketac-Fil and amalgam

The objective of this study was to compare the bone tissue reactions of Ketac-Fil to the most commonly used retrograde filling material, amalgam, in a rat model. Forty-eight Harlan rats were divided into three groups: amalgam, Ketac-Fil, and controls. Following anesthesia, the right lower incisor was extracted from each animal. A 3-mm long x 1-mm diameter polyethylene tube filled with amalgam or Ketac-Fil was implanted in the extraction site. The animals were killed at 14, 42, and 90 days; and the mandibles were dissected en block and processed histologically. The inflammatory reaction was assessed by the number of plasma cells, lymphocytes, polymorphonuclear neutrophils, giant cells, and osteoclasts within 100 microns of the implant. Bone formation was determined as either present or absent in the same area. There was no statistically significant bone apposition within 100 microns of the Ketac material, and there was a statistically significant increase in inflammation in the amalgam group. This study indicates that both Ketac-Fil and amalgam are relatively biocompatible, and provides support for clinical usage tests of Ketac-Fil as a retrograde filling material.

Long-term results of amalgam versus glass ionomer cement as apical sealant after apicectomy

A total of 67 teeth in 64 patients were treated with apicectomy and retrograde fillings. They were randomized to receive fillings of amalgam or glass ionomer cement in a comparative clinical study. Healing was evaluated clinically and radiographically after 1 and 5 years. Evaluation showed no difference in healing capacity between the two materials. Overall success rates in both groups were registered as 90% at 1 year and 85% at 5 years. Contamination with blood or saliva during insertion of the filling material did not affect healing adversely. The study shows that the 5-year follow-up result can be predicted in more than 95% of the cases at the 1-year follow-up. It can be concluded that glass ionomer cement is a valid alternative to amalgam as an apical sealant after apicectomy with equally good long-term clinical results.

Testing of sealing ability of endodontic filling materials

Incomplete obturation of the root canal system is the major cause of endodontic failure. Endodontic filling materials with ability to seal the root canal are, therefore, essential for successful endodontic therapy. However, assessment of sealing ability is not included in the requirements specified in the current international standard covering root canal sealers. A number of different in vitro methods have been used to evaluate the sealing quality of endodontic filling materials. The tests have usually been leakage tests, i.e. based on assessment of penetration of a tracer along the obturated root canal. Leakage tests have poor reproducibility and are, therefore, not suited for standardized test programs. By selecting the properties necessary for sealing ability and testing them separately, it might be possible to find a number of tests, which individually are suitable for a standardized test program, and which combined will give information on the sealing ability of the test material.

Ultrasonic root-end preparation, Part 2. Microleakage of EBA root-end fillings

The effect of three methods of root-end preparation, following apical resection, on the apical seal of root-end fillings, was studied in vitro. Root canals of 116 single-rooted teeth with mature apices were prepared chemomechanically and obturated with gutta-percha and sealer. The root ends were resected with a diamond bur under water coolant and were prepared as follows: group I a size 010 round bur was used to prepare an apical cavity 2-3 mm down the long axis of the root; group II treatment as per group 1 followed by a 60-s rinse with a solution of 10:3 (10% citric acid: 3% Fe2Cl3); and group III an ultrasonic retrotip was used to prepare a 2-3 mm deep apical cavity. The root end was restored with an EBA cement. Apical leakage was determined using India ink after 7 days and 7 months. The teeth were demineralized, rendered transparent and linear dye penetration was recorded. Results showed that there was no significant difference in leakage between the groups at each time interval (P > 0.05) but there was increased leakage after 7 months (P < 0.01). Cracking of the root surface was seen most often with the ultrasonically prepared roots (P < 0.001).

A study in vitro of threaded titanium pins used for retrograde obturation of root canals

The microleakage of four retrograde filling materials was compared in vitro. Fifty-three single rooted teeth were instrumentated and root filled with resin chloroform and gutta-percha. The gutta-percha cones were left extruding from the access opening. All teeth were apicected and retrograde fillings placed. The materials used were a non gamma 2 amalgam (Amalcap), a glass ionomer cement (ChemFil II), threaded titanium pins cemented with a glass ionomer cement (ChemFil II) and identical titanium pins cemented with a silicone material (Adheseal). After removal of the gutta-percha with tweezers, a radioactive isotope solution was placed in the teeth. Extraradicular samples were taken at 3, 7, 28, 77 and 104 days. All retrograde fillings showed some microleakage. The group with titanium pins cemented with silicone showed the least leakage: significantly less than the teeth with glass ionomer cement (P < 0.01) and with amalgam (P < 0.01). No significant differences were found between other groups.

The effect of storage time on the degree of dye leakage of root-end filling materials

The quality of the apical seal obtained by root-end filling materials generally has been assessed by the extent of dye penetration. Most investigators have allowed the root-end filling materials to set before they are tested. The purpose of this study was to evaluate if storage time had any influence on the amount of dye leakage. Seventy extracted single rooted human anterior teeth were used. After removal of their anatomical crowns, the roots were instrumented, filled with gutta-percha and Roth's sealer, and subjected to test conditions. The roots were coated with two coats of nail polish. Root ends were resected and class I cavities prepared. Sixty class I root-end cavities were filled with with either amalgam, super EBA, or IRM (20 each). Ten roots in each group were placed immediately into India ink for 48 h, the other 10 were stored for 24 h before placement into the ink. Ten roots (five per group) were used as positive (gutta-percha, no sealer) and negative (bone wax) controls. The roots were then demineralized, linear dye leakage was measured, and the data were evaluated statistically using ANOVA. Super EBA, and IRM showed significantly less dye leakage than amalgam (P < 0.0001). No significant difference existed between Super EBA and IRM. Storage time had no significant influence on the amount of dye leakage observed in this study.

Apical dentin permeability and microleakage associated with root end resection and retrograde filling

This study evaluated the apical leakage associated with various depths of retrograde fillings placed in root apices which had been resected at one of three different angles. Leakage was assessed with a hydraulic conductance apparatus. Teeth were divided into groups corresponding to the angle of apical resection (0, 30, and 45 degrees to the long axis of the root) and apical leakage was determined following incremental increases in the depth of the retrograde filling (Ketac Silver). Increasing the depth of the retrograde filling significantly decreased apical leakage; there was also a significant increase in leakage as the amount of bevel increased. Both the permeability of resected apical dentin and microleakage around the retrograde filling material had a significant influence on apical leakage.

An electrochemical study of the sealing ability of different retrofilling materials

Eighty-eight extracted mandibular and maxillary cuspids were selected for this study. Eighty cuspids were used as experimental groups and eight were used as controls. Anatomical crowns were resected, root canals were prepared, and the apical 2 mm of the roots were removed. The experimental roots received apical cavity preparations and were randomly divided into four equal groups. The apical cavities were retrofilled with amalgam, heat-sealed gutta-percha, zinc polycarboxylate cement, or glass ionomer cement. Leakage was measured using an electrochemical technique. Statistical analysis of the results indicated that glass ionomer sealed significantly better than the other materials, followed by amalgam, heat-sealed gutta-percha, and zinc polycarboxylate cement, respectively.

Comparison of the sealing capabilities of Ketac-silver and extra high copper alloy amalgam when used as retrograde root canal filling

Apical microleakage following reverse retrograde root filling with extra high copper amalgam alloy was compared with that following a silver-glass ionomer retrofilling. The root canals of 56 extracted, single-rooted anterior human teeth were instrumented and obturated with laterally condensed gutta-percha and zinc oxide-eugenol sealer. Each tooth was apically resected at 45 degrees to its long axis and the root surface isolated with nail varnish. Teeth were divided into three groups. The first group received extra high copper amalgam retrograde fillings, the second group was retrofilled with a silver-glass ionomer, and the control group had no retrograde root filling placed. Following immersion in 1% methylene blue dye at 37 degrees C, the roots were sectioned and dye penetration was measured using an image analyzer. The sealing effectiveness of these materials was determined by their ability to inhibit dye penetration at 24 and 48 h. The results of this study show that a silver glass-ionomer is just as effective as extra high copper amalgam in terms of sealing capability. There was no statistically significant difference between the two materials.

A comparative sealability study of different retrofilling materials

The purpose of this study was to compare the sealing ability of high-copper amalgam, glass ionomer cement, and silver glass ionomer cement as retrofilling materials when used with and without varnish. Seventy extracted human single-rooted anterior teeth were instrumented and the root canals obturated with laterally condensed gutta-percha and sealer. The apical 3 mm of each root was resected and a 2 mm-deep apical Class I preparation cut. The roots were then randomly allocated to six groups of 10 teeth and retrofilled with one of the experiment materials. Group I comprised high-copper amalgam; group 2, high-copper amalgam with cavity varnish; group 3, glass ionomer cement without varnish; group 4, glass ionomer cement with varnish; group 5, silver glass ionomer cement without varnish; and group 6, silver glass ionomer cement with varnish. Two groups of five roots each were used as positive and negative controls. The root surfaces were coated with nail polish and specimens immersed in 2% methylene blue solution for 14 days. After vertical sectioning, dye penetration was examined under a stereomicroscope. The results of the study were analysed statistically. The sealing ability of the conventional glass ionomer cement with varnish was significantly better while dye penetration was higher in silver glass ionomer cement without varnish group than the other groups (P < 0.01).

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).

Quantitative radioactive analysis of microleakage of four different retrograde fillings

Sealing properties of four different retrograde filling materials were investigated in vitro. Radioactive isotopes were applied in the root canal, and leakage into an extraradicular fluid was measured at regular intervals. The method permitted repeated observation of the specimens over prolonged periods of time. Forty single-rooted human teeth were biomechanically instrumented and obturated using calcium-hydroxide paste. Following obturation, an apicectomy was performed and retrograde cavities were filled with four different materials: group 1, non gamma 2 amalgam (Amalcap); group 2, glass ionomer cement (Ketac Silver); group 3, calcium-hydroxide-based root canal sealer (Sealapex); group 4, composite resin (Palfique Light-S). After removal of the calcium hydroxide, the teeth were immersed in a fluid. An isotope solution was then placed in the root canals. Samples were taken from the fluid at 0, 3, 7, 28, 56, 105, 210, 285 and 376 days to determine the radioactivity. It was found that Sealapex and Palfique Light-S showed significantly less leakage than amalgam and glass ionomer cement, which had the highest apical leakage.

Efficacy of removing glass ionomer cement, zinc oxide eugenol, and epoxy resin sealers from retreated root canals

Removal of gutta-percha and various sealers was assessed during retreatment of the root canal system. Sixty root canals were prepared and obturated with gutta-percha and Ketac-endo, Roth's 801 cement, or AH26. After 14 days, the canals were retreated by hand or ultrasonic technique and the retreatment time was recorded. The roots were split and the amount of debris that remained on the canal walls in three separate levels was recorded by use of a dissecting microscope. The mean scores were compared by one-way and two-way ANOVA. The total score was significantly the highest for Ketac-endo (p less than 0.04), followed by AH26 and Roth's 801 cement. The largest amount of debris was consistently found in the apical third, and generally it was comparable for both retreatment techniques. The ultrasonic technique was significantly faster than the hand technique for all sealers tested (p less than 0.0004, p less than 0.0003, p less than 0.02, respectively). Hand retreatment of Ketac-endo was the slowest, whereas ultrasonic retreatment of Roth's 801 cement was the fastest. The results indicated that Ketac-endo endodontic sealer can be effectively removed from the root canal by ultrasonic instrumentation.

A laboratory study of glass ionomer cement as a retrograde root-filling material

This laboratory study investigated the use of various glass ionomer cements for retrograde root filling from the point of view of sealing qualities, ion release and ease of application. The sealing qualities of the material were tested by dye penetration and microscopic and SEM examination. Fluoride and silver ion release tests showed an initial loss of these two ions from the glass ionomer cement. A modified system for mixing and application was developed. Dye penetration did not differ from that of controls using vertically condensed gutta-percha. Glass ionomer cement is possibly a clinical alternative for the sealing of retrograde cavities; however, the silver-reinforced materials may cause tissue irritation from release of silver ions and their corrosion products.

The adaptation and sealing ability of light-cured glass ionomer retrograde root fillings

The adaptation and sealing ability of a light-cured glass ionomer cement when used as a retrograde root filling was assessed using a confocal optical microscope with and without a fluorescent dye. This material was compared with a conventional glass ionomer cement and amalgam. The root canals of 60 extracted human single-rooted teeth were prepared and filled with gutta-percha and sealer. All the teeth were apicected, retrograde cavities were prepared, and then divided into three groups of 20 teeth each and filled with the test materials. The light-cured glass ionomer cement was well adapted to the retrograde cavity and apicected root surface. Within the retrograde cavity the cement was often well adapted to one wall, but gaps were found on the opposite cavity wall. This was probably caused by the polymerization contraction of the material. In contrast, the amalgam retrograde root fillings were poorly adapted to the cavities, with gaps between the cavity walls and amalgam. This group exhibited the poorest sealing ability as measured by the extent of dye penetration. The conventional glass ionomer cement was often found smeared over the root face, and there were unfilled voids at the base of some retrograde cavities. The results of the dye leakage study were analysed statistically. The sealing ability of the light-cured glass ionomer cement was significantly better than that of amalgam (P less than 0.001). The dye penetration around the light-cured glass ionomer cement and the conventional glass ionomer cement was not significantly different (P greater than 0.05). However, the sealing ability of the conventional glass ionomer cement was significantly better than that of amalgam (P less than 0.05).

Dye leakage in retrofilled dog teeth and its correlation with radiographic healing

In a previous study in beagle dogs, statistically significant differences in healing were observed radiographically 6 months after apicoectomy and retrofilling with amalgam and varnish, glass ionomer cement, or a composite resin. The purpose of this study was to compare the leakage of these retrofilling materials and to correlate leakage data with healing. After the dogs were sacrificed, 48 roots were extracted. Half of the roots had been irradiated with a CO2 laser on the bevelled root surface after retrofilling. The roots were coated with nail polish, except for their bevelled surface, and were suspended together with positive and negative controls in 2% methylene blue for 8 h. After the specimens were longitudinally split, they were ranked according to the severity of dye penetration, as observed with a dissecting microscope. The differences in dye leakage among the three retrofilling materials were not statistically significant. Consequently, dye leakage did not correlate with the previously assessed healing. Dye penetrated into the root through the bevelled root surface, regardless of CO2 laser exposure of that surface.

Retrograde approaches in endodontic therapy

The routine use of retrograde fillings during apical surgery, as well as the material of choice for that purpose, have been debated. A retrograde filling is placed so as to seal an infected root canal causing periapical pathosis. Therefore, retrograde root canal fillings should be performed routinely during apical surgery regardless of the apparent technical quality of the root canal obturation, unless orthograde endodontic treatment is performed in conjunction with surgery. When orthograde treatment is not performed, retrograde root canal filling enhances the prognosis of apical surgery. An array of potential retrograde filling materials have been extensively investigated in vitro and in vivo. Once that the biocompatibility of the materials is confirmed a clinical comparison, rather than in vitro sealability studies, is the most valid evaluation method. Some of the difficulties encountered in long term clinical studies in patients may be avoided in animal studies. The review of the relevant literature of the past decade suggests that amalgam used in conjunction with cavity varnish is the retrograde filling material of choice. It must be stressed, however, that retrograde filling is not comparable to debridement and obturation of the entire root canal. Therefore, when the only way to approach the root canal is from the apical direction, rather than placing an apical retrograde filling, a retrograde endodontic treatment of the entire canal should be preferred, if it is feasible.

Silver glass ionomer cement as a retrograde filling material: a study in vitro

Comparison was made of the apical microleakage of retrograde fillings with amalgam and with silver glass ionomer cements using a modified dye penetration method. Forty instrumented human teeth were divided into four groups. Each group was characterized by a different retrograde filling material or technique: Group 1--silver glass ionomer (SGI); group 2--SGI with previous acid wash of the cavity; group 3--SGI in a previously acid washed cavity, protected with varnish; and group 4--zinc-free amalgam. A paper cone for dye adsorption analysis was placed in contact with retrofill and the main canal was obturated with thermoplasticized gutta-percha. All teeth were coated, immersed in methylene blue dye, and evacuated to assure complete penetration of the dye in any possible void. Later the teeth were cleared and evaluated under stereomicroscope. Statistical analysis showed that group 1 had the least microleakage of all. In addition, the biocompatibility of the SGI and varnish was compared with that of amalgam using the 51Cr release evaluation method. The results showed that SGI and varnish were less cytotoxic than amalgam. It was concluded that SGI cement can be considered an alternative retrograde filling material.

Apicectomy: a comparative clinical study of amalgam and glass ionomer cement as apical sealants

Healing capacity after apicectomy was investigated in a randomized clinical study of 105 teeth apically sealed with either amalgam or glass ionomer cement. The results were evaluated clinically and radiographically after 1 year. The success rate was high for both materials: 91% for amalgam and 89% for glass ionomer cement. Contamination with moisture and blood adversely affected the outcome for both materials and was significantly more frequent in unsuccessful cases.

The effect of post space preparation on the apical seal of root fillings using chemically adhesive materials

The effect on the apical seal of root filling teeth with two sealer cements that reacted chemically with tooth structure was studied in vitro. In addition, apical leakage of teeth obturated with these materials and subsequently prepared to accept a post was tested. Ninety single-rooted teeth with mature apices were prepared chemomechanically by the stepback technique using files and copious irrigation with 2.5 per cent sodium hypochlorite. The teeth were then randomly allocated to six groups of 15 teeth each. Two groups were root filled by lateral condensation of gutta-percha and one of three sealer cements: Tubliseal, a radiopaque glass ionomer luting cement, Ketac Cem, and a chemically active composite resin, Panavia Ex. Thirty minutes later, in one group for each material, a post space was prepared leaving 4-5 mm of root filling at the apex. The extent of apical leakage in each group was determined after immersion in Indian ink for 14 days. The teeth were demineralized, dehydrated and immersed in methyl salicylate, which rendered them transparent, and a linear measurement of dye penetration was recorded. No statistically significant difference in the extent of leakage was found between the sealers in those groups which were filled by lateral condensation and left intact. However, the degree of leakage increased after post space preparation with the glass ionomer and Tubliseal groups, but was reduced in the Panavia Ex group.

In vivo efficacy of various retrofills and of CO2 laser in apical surgery

The purpose of the present study was to radiographically assess the efficacy of various retrofilling materials and of the use of CO2 laser in apical surgery. The mandibular premolars of six beagle dogs were infected, resulting in periapical lesions. Apical surgery was performed without root canal treatment. Amalgam with cavity varnish, glass ionomer cement and a lightcured composite resin were the retrofilling materials used. In half of the material CO2 laser was used on the root surface and the bone, for occlusion of the dentinal tubuli and sterilization. The healing following surgery was observed radiographically for six months. The highest success rate (89%) was found in the roots retrofilled with amalgam and varnish, and the lowest (60%) in those retrofilled with the composite resin. The difference between these groups was statistically significant. The success rate following retrofilling with glass ionomer cement was 69%, and was not significantly different from both the other groups. Under the conditions of this study, the use of CO2 laser during surgery did not affect the treatment results.

Tissue response to glass ionomer retrograde root fillings

The periapical tissue response to glass ionomer cement retrograde root fillings was investigated both in the presence and in the absence of fillings in the root canals of eight upper incisor teeth of four monkeys. The pulps of the teeth were extirpated and one canal in each pair was filled with laterally condensed gutta-percha immediately after canal preparation. The other canal was prepared but left open to oral contamination. Apicectomies were performed on both teeth in each pair 1 week later, and glass ionomer cement retrograde root fillings were placed. After 5 months, the teeth and surrounding tissues were removed and prepared for histological examination. All four of the teeth without root canal fillings showed severe periapical inflammation, and bacterial were present in the interface between the dentine and the retrograde root filling. The teeth with root canal fillings showed little or no periapical inflammation. This study showed that adhesive retrograde root fillings were successful when the root canal was completely filled, but in the absence of a gutta-percha canal filling they failed to provide a seal.

Factors influencing the sealing behavior of retrograde amalgam fillings

In this study, the sealing behavior of apical (retrograde) amalgam fillings was evaluated with particular regard to the nature of the amalgam and the manipulative procedures used. With the use of an in vitro air pressure test, four high-copper alloys and one traditional composition low-copper alloy were selected for determination of their microleakage characteristics. Measurements were made on both normal and water-contaminated mixes, and the effect of mix plasticity was evaluated. In addition, both setting and postsetting dimensional changes of these alloys were determined. The results showed that amalgams differ in their ability to provide a complete seal and that low plasticity mixes result in greater microleakage. All zinc-containing alloys that were contaminated with water exhibited a postsetting or delayed expansion. However, only the low-copper alloy exhibited a delayed expansion of a magnitude that might induce root fracture.

Evaluation of sealing properties of 70 degrees C thermoplasticized gutta-percha used as a retrograde root filling

The efficacy of low temperature (70 degrees C) thermoplasticized gutta-percha used to seal root canals by the retrograde approach following apicectomy was assessed. A dye leakage technique was used, and gutta-percha was compared with amalgam. Two groups of different sized roots were apicected, and their root canals instrumented and filled conventionally with laterally condensed gutta-percha. Each group was randomly divided into four sub-groups; one was the control group in which no further treatment was carried out. In the other three groups the apical 3 mm of gutta-percha was removed, and the apical cavities filled as follows: group I with 70 degrees C thermoplasticized gutta-percha with sealer; group II with 70 degrees C thermoplasticized gutta-percha without sealer; group III with amalgam. The roots were rendered transparent by acid demineralization, and maximum dye penetration was measured. The results showed statistically significant ranking of leakage between the four sub-groups: 70 degrees C thermoplasticized gutta-percha with sealer less than 70 degrees C thermoplasticized gutta-percha without sealer less than amalgam less than control. The larger canals in all four sub-groups also exhibited significantly greater leakage than the smaller ones.

Sealing ability of materials used as retrograde root fillings in endodontic surgery

The sealing ability of retrograde root fillings of amalgam plus cavity varnish, EBA cement, glass ionomer cement, light-cured composite resin, dentine bonding agent, and light-cured composite resin plus dentine bonding agent were compared with laterally condensed conventional root fillings. A dye penetration technique was used to assess microleakage and it was concluded that none of the materials produced a perfect seal but that glass ionomer cement, light-cured composite resin, light-cured composite resin plus dentine bonding agent and dentine bonding agent alone produced better seals than conventional laterally condensed gutta-percha, amalgam plus cavity varnish and EBA cement.

One visit apicectomy technique using calcium hydroxide cement as the canal filling material combined with retrograde amalgam

A prospective study was set up to evaluate a one-visit apicectomy technique. Calcium hydroxide cement was used as the root canal filling material. The calcium hydroxide cement set rapidly and clearly revealed the position, size and outline form of the root canals at the level of resection. This facilitated preparation of the apical cavities to a depth of 3 mm. Each cavity was varnished before placement of the amalgam. Sixty-eight patients (93 teeth) were included in the study. Five patients (8 teeth) were lost to follow-up. The success rate, based on clinical and radiographic examination after a minimum of 2 years, was 91.8 per cent.

Retrograde root filling using antibiotic-containing, radiopaque, bone cement

An investigation is reported on the in-vitro behaviour, characteristics and properties of three gentamicin-containing radiopaque bone cements that are considered to be promising retrograde root-filling materials. Three commercially available cements, CMW-1G, CMW-3G and Palacos R with gentamicin were studied with regard to bacteriocidal properties, tissue compatibility in cell culture, and ability to seal tooth cavities as evidenced by dye diffusion. Results were compared and contrasted with those obtained with an amalgam. The antibiotic-containing cements investigated are considered to have some distinct advantages over amalgam when used as retrograde root-filling materials in vitro. Amalgam was found to have poor bacteriocidal properties and poor tissue compatibility but slightly better apical sealing abilities than the cements. No apparent drawbacks were found with the cements.