Longitudinal evaluation of the seal of endodontic retrofillings

The apical seal obtained with various retrofilling materials placed in prepared, extracted human anterior teeth was measured at various time intervals. Materials evaluated were cold-burnished gutta-percha, amalgam, amalgam with a cavity varnish, SuperEBA cement, and a glass ionomer restorative material (Ketac-Silver). Control groups included teeth retrofilled with either gutta-percha without sealer or TERM. The root canals were cleaned and shaped and the root ends were prepared for retrofilling. The materials were placed into the preparations and allowed to set for 24 h. Microleakage was measured at 24 h, 1, 2, and 3 wk, and 1, 2, and 3 months after insertion of the retrofilling using a fluid filtration technique. Multiple range analysis indicated that Ketac-Silver produced a significantly inferior seal when compared with the other materials at all time periods. There was no significant difference among SuperEBA, amalgam, and amalgam with a cavity varnish.     

An evaluation of the retrograde apical seal using dentine bonding materials

Summary. The purpose of this investigation was to compare in vitro retrograde apical leakage of four dentine bonding procedures with amalgam and hot burnished gutta-percha.
Single-rooted teeth were prepared using a standardized stepback flare technique with recapitulation. The teeth were obturated with gutta-percha and sealer using the lateral condensation technique and placed into a saline bath at 37°C for 30 days. The teeth were then randomly divided into seven groups of 22 teeth each. Groups I and II were apically bevelled, and dentine bonding agent with composite resin and dentine bonding agent with unfilled resin applied to the bevelled root faces, respectively. Groups III, V and VI were apically bevelled and prepared to accept a retrograde filling material of dentine bonding agent with composite resin, amalgam with cavity varnish and amalgam without cavity varnish, respective. Group IV had dentine bonding agent and unfilled resin applied to the apical third of the root, and Group VII was apically bevelled and the gutta-percha hot burnished. The teeth were then placed into a water bath at 37°C for 30 days, stained with silver nitrate and the linear dye penetration measured.
The lowest mean leakage value was recorded in Group I, i.e. dentine bonding agent and composite resin (0.31 mm), and the highest value was observed in group VII, i.e. hot burnished gutta-percha (4.60mm); the difference was statistically significant.     

Cyanoacrylate as a retrofilling material

The sealing ability of cyanoacrylate as a retrograde root canal filling material was evaluated in vitro. Fifty roots were cleansed, shaped, and assigned to five groups of ten roots each. The root canals were obturated with gutta-percha and Grossman's sealer. The apical 2 mm of each root in the five groups was resected. In groups I, II, and III, retrofilling preparation was made and filled with amalgam, varnish and then amalgam, and cyanoacrylate, respectively. In group IV, a hot instrument was used to seal the gutta-percha, and in group V, a cold burnisher was used for the same purpose. All of the teeth were immersed in 1% methylene blue dye for 24 hours and sectional longitudinally; dye penetration was then measured. One-way analysis of variance performed on the means of the groups indicated that group III had the least amount of leakage (p less than 0.05). This study indicates that cyanocrylate may have potential as a retrograde filling material.     

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).     

Retrograde seal in ultrasonically prepared canals

The sealing ability of various retrofilling materials was compared. The root canals of 85 single-rooted teeth were cleansed and obturated with gutta-percha without sealer using lateral condensation. The apical 3 mm of the roots were resected and divided into positive control, negative control, and five experimental groups. The experimental teeth received root-end cavity preparation to 3 mm depth using an ultrasonic retroprep tip. The retrocavities were dried and divided into five groups to receive the following materials: amalgam with varnish, amalgam with Clearfil Liner Bond II, thermoplasticized gutta-percha (TGP) with sealer, Ketac-fil, and Super-EBA. After immersion in India ink for 7 days, the roots were demineralized, cleared, and evaluated for dye leakage under a stereomicroscope. Statistical analysis showed that Super-EBA, Ketac-fil, and TGP with sealer demonstrated less leakage than amalgam with varnish and amalgam with Clearfil Liner Bond II (p < 0.05). Super-EBA also leaked significantly less than Ketac-fil or TGP sealer (p < 0.05). No significant difference was found between Ketac-fil and TGP or between the two groups filled with amalgam (p > 0.05).     

A 24-week study of the microleakage of four retrofilling materials using a fluid filtration method.

The microleakage after retrofillings of amalgam, amalgam with cavity varnish, silver-containing glass ionomer cement, and intermediate restorative material was compared in vitro. Thirty-six extracted human incisors and canines were instrumented, obturated with gutta-percha without sealer, subjected to apicoectomy, and retrofilled with the materials described above. After removal of the gutta-percha filling, the microleakage from both directions (apically and coronally) was measured quantitatively and longitudinally for 24 wk after filling by a fluid filtration technique. All four retrofilling materials revealed some apical and coronal leakage at all time periods. The amalgam group showed statistically significant (p less than 0.001) apical leakage at 1.5 h. The use of cavity varnish significantly reduced the apical leakage of the amalgam group at 1.5 h. The silver-containing glass ionomer cement and intermediate restorative material groups showed significantly (p less than 0.05) less coronal leakage compared with the amalgam group at 1.5 h. Scanning electron microscopy of selected samples showed marginal defects of approximately 5 microns between the root dentin and the retrofilling material.     

A comparative scalability study of different retrofitting 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 retrofitting 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 retrofitled with one of die 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).     

Fluoride release from glass ionomer-lined amalgam restorations

This study evaluated the amount of fluoride released from glass ionomer-lined amalgam restorations. 50 human extracted molars were divided into five groups of 10 teeth each. Group 1: No restorations. Group 2: Class V cavities (2 x 2 x 7 mm) were made on the facial and lingual surfaces and restored with Dispersalloy amalgam. Group 3: Same as Group 2 except 1 mm of Ketac-Bond glass ionomer cement (GIC) was placed on the axial wall before amalgam insertion. Group 4: Same as Group 2 except 1 mm of Chelon-Silver glass ionomer cement (GIC) was placed on the axial wall before amalgam insertion. Group 5: Same as Group 2 except 1 mm of Ketac-Silver GIC was used before amalgam insertion. Before any treatment, all samples were placed in polyethylene vials with 4 ml of deionized water and thermocycled (100x) for baseline fluoride release levels. After restoration, each tooth was placed in a vial with 4 ml of fresh deionized water. At weekly intervals, each tooth was removed from its aqueous medium and transferred to another vial containing 4 ml of deionized water. Fluoride release was measured four times at weekly intervals with an Orion #9609 fluoride-ion electrode. At one week, Ketac-Bond released significantly more fluoride than Ketac-Silver (P less than 0.01) which released significantly more fluoride than Chelon-Silver (P less than 0.01). At four weeks, there was no significant difference in fluoride release between Chelon-Silver and Ketac-Silver, but Ketac-Bond released significantly more fluoride than either of the other materials (P less than 0.01).     

An in vitro evaluation of injectable thermoplasticized gutta-percha, glass ionomer, and amalgam when used as retrofilling materials

An in vitro dye leakage study was performed to evaluate the sealing ability of the following retrofilling materials: high- and low-temperature injectable thermoplasticized gutta-percha with and without sealer, a glass ionomer cement, and amalgam with and without varnish. The roots of 105 extracted human maxillary anterior teeth were instrumented and obturated with single cones of gutta-percha and sealer. The apical 3 mm of the roots were then resected and 2-mm deep retrograde preparations were prepared. Each root was then randomly placed into one of seven groups and retrofilled with one of the test materials. After 72 h in India ink, the roots were cleared and evaluated for leakage using a stereomicroscope. Statistical analysis of the results indicated that injectable high-temperature gutta-percha without sealer demonstrated significantly more leakage than the other materials. There were no significant differences in leakage among the other evaluated materials.     

The effect of varnish and pit and fissure sealants on the sealing capacity of retrofilling techniques

Freshly extracted teeth with single canals were instrumented and filled with laterally condensed gutta-percha and sealer. After obturation, the tooth apices were treated with various retrograde techniques. The sealing ability of these techniques, namely laterally condensed gutta-percha, heat-sealed gutta-percha, and silver amalgam retrofilling, was compared on the basis of dye penetration. The apical foramen of the treated canals was then coated with different sealing materials--HelioSeal (light-activated sealant), Delton pit and fissure sealant (chemically activated sealant), and varnish--to examine their effect on the leakage resistance of these materials. Statistical analysis indicated that laterally condensed gutta-percha, as well as retrograde amalgam filling, produced a statistically significantly better seal than heat-sealed gutta-percha. Coating of the apical foramen with different sealing materials showed that HelioSeal had significantly improved the sealing capacity of all the materials tested at each time period. Delton pit and fissure sealant did not increase the sealing ability in the first week. However, this material has significantly improved the sealing ability after the first week. On the other hand, sealing of the apical foramen with varnish did not produce any significant change in the sealing capacity of the filling materials. Finally, dye penetration around all the filling and retrofilling materials, in the presence or absence of the apical seal, continued and increased with time. However, root canals sealed with Helioseal consistently showed the least amount of apical leakage of all the canals tested.     

A dye penetration study of retrofilling materials

The apical sealing ability of amalgam, cold-burnished gutta-percha, amalgam with cavity varnish, and SuperEBA cement was evaluated in extracted human teeth. For each experimental group, the roots of 20 single-rooted teeth were sectioned from their crowns. Canals were cleaned, shaped, and obturated with vertically condensed warmed gutta-percha and Kerr Pulp Canal Sealer. Following apical preparation and placement of test materials, root ends were placed in 1% methylene blue dye for 2 wk, after which the roots were sectioned longitudinally, and linear measurements of dye penetration were recorded. Results demonstrated statistically less linear dye penetration in the test group sealed with amalgam and cavity varnish. Statistical differences were not detected among the other test groups.     

Apical sealing efficacy of two reverse filling techniques versus cold-burnished Gutta-percha

The apical seal produced by the cold-burnished gutta-percha method and two amalgam reverse filling techniques was investigated in an in vitro study using 36 extracted human single-rooted teeth. Following root canal obturation, 27 teeth were divided into three experimental groups and each group was subjected to one of the three following filling techniques: (a) cold-burnishing of gutta-percha; (b) amalgam reverse filling; and (c) amalgam reverse filling in conjunction with cavity varnish. The remaining nine teeth served as controls (4). The teeth were placed in methylene blue dye for a period of 1 wk, after which they were retrieved, washed, sectioned, and the apical dye penetration measured. The results showed that amalgam with cavity varnish demonstrated less dye penetration than the other experimental groups. The difference was statistically significant (p less than 0.0001).     

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.     

In vitro sealing ability of dentin bonding agents and cavity varnish with amalgam as retrofills.

The aim of this study was to test the effect on the seal produced by an amalgam retrofill of two dentin bonding agents (Amalgambond and All-Bond) and a cavity varnish (Copalite). The three materials were tested when placed before the retrofill (group I) and before and after the retrofill (group II). Ninety teeth distributed into three groups were prepared for the retrofilling. Each group was divided into subgroups of I and II. Linear apical leakage was measured by a stereomicroscope after 1 month in dye. All materials permitted dye leakage around the retrofill, regardless of the application type. No statistical difference was found between the Amalgambond subgroups or between the All-Bond subgroups. There was less leakage in varnish group I than group II. Amalgambond group I leaked significantly less than All-Bond group I.     

Fracture resistance of posterior teeth restored with glass ionomer-composite resin systems

This study compared the fracture resistance of posterior teeth restored with one of four composite resin systems or amalgam. Mesio-occlusodistal cavity preparations were placed in 50 maxillary premolars. Dimensions of the preparation were such that remaining tooth structure was weakened. Five groups of 10 specimens each were designated as follows: I, amalgam; II, Ketac-Bond glass-ionomer base; III, Ketac-Silver glass-ionomer base; IV, GC lining cement glass-ionomer base; and V, Tenure dentinal bonding agent. Specimens in groups II through V were restored with P-30 posterior composite resin. Testing was accomplished by applying an occlusal load to the point of failure for each specimen. Results indicated no significant difference among restorative systems in resistance to cuspal fracture. These findings suggest that neither Tenure nor glass-ionomer cement used in conjunction with posterior composite resin strengthen weakened cusps to any greater extent than does amalgam.     

In vitro microleakage of glass-ionomer composite resin hybrid materials.

The purpose of this study was to evaluate the microleakage of six glass-ionomer composite resin hybrid materials compared with a glass-ionomer cement and a composite resin. Standardized class 5 dentin cavities were prepared on root surfaces of 240 extracted human teeth that were randomly assigned to eight groups and restored using the following restorative systems: (I) Vitremer, (II) Compoglass, (III) Photac-Fil Aplicap, (IV) Variglass, (V) Dyract, (VI) Fuji II LC, (VII) Ketac-Fil Aplicap, and (VIII) Z100. The teeth were thermocycled, placed in a 2% methylene blue solution, and sectioned with diamond disks. Dye penetration was scored on a scale of 0-3. Results showed no significant differences among groups VIII, IV, I, V, VI, III, and II. There were also no significant differences among groups VI, III, II, and VII.     

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.     

Leakage in vitro with high-temperature thermoplasticized gutta-percha, high copper amalgam, and warm gutta-percha when used as retrofilling materials

An in vitro dye leakage study was performed to compare the sealing ability of high-temperature thermoplasticized gutta-percha, high copper amalgam, and warm gutta-percha when used as retrofilling materials. Forty-five extracted anterior teeth were obturated with gutta-percha, the apical 3 mm of the roots were resected, and 2-mm-deep retrograde preparations were prepared. The roots were then randomly placed into three groups and retrofilled with one of the experimental materials. After 72 h in India ink, the teeth were cleared and evaluated for leakage using a stereomicroscope. No leakage was evident in the three teeth used as negative controls. Complete leakage was noted in the three positive control teeth. Statistical analysis of the results showed that high-temperature thermoplasticized gutta-percha had significantly less leakage than did high copper amalgam.     

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.     

Leakage in vitro with IRM, high copper amalgam, and EBA cement as retrofilling materials

An in vitro dye leakage study was performed to compare the sealing ability of high copper amalgam with Copalite, IRM, and EBA cement when used as retrofilling materials. Fifty-one extracted anterior teeth were instrumented and then obturated with gutta-percha. The apical 3 mm of the roots were resected and 2-mm deep apical preparations were made. The roots were then randomly placed into three groups and retrofilled with one of the experimental materials. After 72 h in India ink, the teeth were cleared and evaluated for leakage with a stereomicroscope. No leakage was evident in the three teeth used as negative controls and complete leakage was noted in the three positive control teeth. Statistical analysis showed that IRM and EBA cement had significantly less leakage than amalgam with Copalite. The difference between the EBA cement and IRM was not significant.