Tissue response to potential root-end filling materials in infected root canals

The tissue responses to two potential root-end filling materials, a light-cured glass ionomer cement (Vitrebond) and a reinforced zinc oxide-eugenol cement (Kalzinol) were compared with that to amalgam. In 27 premolar teeth of beagle dogs (54 roots), a collection of endodontic pathogenic bacteria was first inoculated into the root canals to induce periapical lesions. On each root, an apicectomy was performed and root-end cavities prepared to receive fillings of each material. The teeth and surrounding jaw were removed after 8 weeks (24 roots) and 4 weeks (30 roots); and they were prepared for histological examination. The tissue response to amalgam fillings after 4 and 8 weeks was marked by moderate or severe inflammation on all roots, and extended > 0.5 mm in 10 out of 18 roots. In contrast, after 8 weeks, the majority of roots filled with Kalzinol showed little or moderate inflammation while the tissue response to Vitrebond was the best of the three materials, and was also less extensive. After 4 weeks, the overall best tissue response was with Kalzinol, followed closely by Vitrebond. The differences between materials for both time periods with either none or few inflammatory cells when compared with that with either moderate or severe inflammation were statistically significant (P < 0.01). Similarly, the differences between materials for both time periods with no inflammation or inflammation extending < 0.2 mm when compared with that with inflammation extending > 0.2 mm (< or = 0.5 mm or > 0.5 mm) were statistically significant (P < 0.01). Both Vitrebond and Kalzinol have potential as root-end filling materials as the tissue response was considerably more favourable than that to amalgam.     

Short-term tissue response to potential root-end filling materials in infected root canals

The short-term tissue responses to two potential root-end filling materials, a light-cured glass ionomer cement (Vitrebond) and a reinforced zinc oxide–eugenol cement (Kalzinol), were compared with that to amalgam using a previously devised experimental model. In 24 premolar teeth of beagle dogs (47 roots), a collection of endodontic pathogenic bacteria was first inoculated into the root canals to induce periradicular lesions. On each root, an apiccctomy was performed and root-end cavities prepared to receive fillings of each material. The teeth and surrounding jaw were removed after 2 weeks (23 roots) and 1 week (24 roots); they were then prepared for histological examination. The tissue response to amalgam fillings after 2 weeks and 1 week was marked by moderate or severe inflammation on all roots, and extended to 0.5 mm or >0.5 mm in 15 out of 16 roots. In contrast, after 2 weeks, the majority of roots filled with Kalzinol showed little or moderate inflammation, while the tissue response to Vitrebond was the best of the three materials, and was also the least extensive. After 1 week, the overall best tissue response was with Vitrebond, followed by Kalzinol. The differences between materials for both time periods with either none or few inflammatory cells when compared with that with either moderate or severe inflammation were not statistically significant (P<0.02). However, the differences between materials for both time periods with no inflammation or inflammation extending <0.2 mm when compared with that with inflammation extending >0.2 mm (0.5 mm or >0.5 mm) were statistically significant (P<0.01). Apart from amalgam, in which healing was marked by the persistence of a localized focus of inflammation adjacent to the root-end filling, even though there were intersamlpe variations, there was little overall difference in the temporal and qualitative healing response to Vitrebond and Kalzinol. Both Vitrebond and Kalzinol have potential as root-end filling materials, as the tissue response was considerably more favourable than that to amalgam even in the short-term.     

Pulpal response to an anhydrous glass ionomer luting cement

This investigation was designed to study the pulpal responses to Aquacem, an anhydrous glass ionomer luting cement, and to compare the results with those previously obtained for a conventional glass ionomer luting cement, Chembond. The study was carried out according to the BSI (1980) recommendations for testing restorative materials in vivo. Aquacem caused more pulpal inflammation than the control material, Kalzinol, though by an indirect mechanism. The statistical model demonstrated a significant association between bacterial presence within the experimental cavity and pulpal inflammation. The type of restorative material has no direct association with the degree of inflammation, but the model suggests that it exerts an indirect influence via its antibacterial properties and hence its influence on microbial microleakage.     

Pulpal response to two semihydrous glass ionomer luting cements

This study compared the pulpal responses to two innovative semihydrous glass ionomer luting cements (STA and ZIN) with those previously obtained for a conventional anhydrous glass ionomer luting cement, Aquacem. ZIN contained zinc oxide in the formulation. The study was conducted according to the BSI (1989) recommendations for testing restorative materials in vivo. ZIN was associated with minimal pulpal changes and microbial microleakage, and differed little from the control material, Kalzinol. The pulpal response to STA was similar to that observed for Aquacem, but was associated with less microbial microleakage. The statistical model demonstrated a significant association between bacterial presence within the experimental cavity and pulpal inflammation. The closer that bacteria were to the pulp, the more severe was the ensuing inflammation.     

A study of the relationship among pulpal response, microbial microleakage, and particle heterogeneity in a glass-ionomer-base material.

This investigation was designed to study the pulpal responses to glass-ionomer base materials that differ in particle size distribution. The study was carried out according to the BSI (1980) recommendations for testing restorative materials in vivo. The base materials caused more pulpal inflammation than the control material, Kalzinol, although by an indirect mechanism. A significant association was demonstrated in the statistical model between bacterial presence within the experimental cavity and pulpal inflammation. The type of restorative material has no direct association with the degree of inflammation, although the model suggests that it exerts an indirect influence via its antibacterial properties, and hence its influence on microbial microleakage. The base material, with a heterogeneous particle distribution, was associated with greater bacterial microleakage. Particle size distribution, therefore, has some effect upon bacterial microleakage, but, because of its complex effect upon several physical properties of materials, further studies are indicated.     

Effect of various zinc oxide materials as root-end fillings on healing after replantation

This study examined the effect of various zinc oxide materials as root-end fillings of teeth in a replantation model. A total of 35 molar teeth were used from 19 monkeys. After extraction, root ends were resected, the canals contaminated with oral bacteria, root-end cavities prepared and fillings placed prior to replantation. After 8 weeks the teeth and surrounding jaw were removed and prepared for histological examination. Twelve roots were filled with IRM plus dentine chips, and six with Cavit; the tissue response around root ends filled with these materials as assessed by inflammation was similar to that previously reported to IRM and Super EBA cement and was characterized by little or no inflammation of limited extent. In contrast, more severe inflammation was observed around root ends filled with plain zinc oxide–eugenol or Kalzinol; however, the reaction was neither as severe nor as extensive as that to amalgam root–end fillings. Giant cells were observed most often on the surface of fillings with Cavit and zinc oxide–1eugenol. It is concluded that the tissue response to IRM with or without added dentine, Super EBA and Cavit was similar and mild; it was less severe than that to zinc oxide-eugenol and Kalzinol. All these materials had a much more favourable response than amalgam.     

Sealing ability of potential retrograde root filling materials

Abstract The sealing ability of two potential retrograde root filling materials, a light-cured glass ionomer cement (Vitrebond) and a reinforced zinc oxide-eugenol cement (Kalzinol) was compared with that of amalgam using three methods of assessment: bacterial leakage, confocal microscopy and Indian ink leakage. The root canals of 80 extracted human single-rooted teeth were prepared. All the teeth were apicected, retrograde cavities were prepared and then divided into four equal groups of 20 teeth. The teeth were sterilised by autoclaving and the retrograde cavities filled with the test materials. In the control group, retrograde cavities in 10 teeth were left unfilled while cavities in another 10 teeth were sealed with cyanoacrylate cement. The teeth were first subjected to a bacterial leakage test using Enteroccocus faecalis as a leakage marker. After which, the adaptation of the retrograde root fillings was assessed using a confocal optical microscope. Finally, the teeth were processed for the Indian ink leakage test. Bacterial leakage occurred in more teeth filled with amalgam compared with both Vitrebond and Kalzinol (P < 0.001), between which there were no differences. With confocal microscopy, the size of the marginal gap was largest with amalgam and smallest with Vitrebond; all differences were statistically significant (P < 0.001). Finally, there was more Indian ink penetration with amalgam compared with both Vitrebond and Kalzinol (P < 0.001) but there were no differences between Vitrebond and Kalzinol. Although there were individual differences within samples, overall, the three methods of assessment produced similar results. The sealing ability of Vitrebond and Kalzinol was similar and both materials were better than amalgam.     

A comparative pulpal study of two dental amalgam alloys

Summary. Pulpal responses to a conventional amalgam, New True Dentalloy, and a high copper amalgam, Solila Nova, were studied over a period of 6 months. Kalzinol was used as a negative control material. Standardized Class V cavities were prepared in the canine teeth of male ferrets under ketamine/xylazine anaesthesia. The animals were killed with excess pentobarbitone and the teeth extracted after 7, 14, 28 and 183 days. After processing, the teeth were serially sectioned and assessed qualitatively and quantitatively according to standard criteria. There were some variations in the pulpal responses at 7 days and 14 days post-operatively but at 28 days and 183 days, the responses under the two materials were similar with only slight pulpal inflammation being observed. No pulpal inflammation was present beneath surface-sealed Solila Nova cavities. Gram positive micro-organisms were observed at the interface of cavity wall and material in conventional cavities but not within those surface-sealed with Kalzinol.     

Pulpal effects of glass ionomer cements

Summary. The incidence of pulpal damage beneath cavities filled with ASPA, Chemfil and Chembond was studied in class I cavities in human premolar teeth after 1–10 days, 11–30 days, and 31 or more days. Cavities filled with Kalzinol or zinc oxide/eugenol acted as controls. All glass ionomer cements were accompanied by more pulpal damage than controls, but Chemfil was associated with the least changes. Bacteria were demonstrated at the material/cavity wall interface in a number of cavities with all materials, although no significant correlation was demonstrated between them and pulpal inflammation. The use of a base is recommended in cavities where large numbers of previously unaffected dentinal tubules are present.     

Radiopacity of potential root-end filling materials

ObjectivesIn 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 designRadiographs 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.ResultsCommercial 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.ConclusionsWe recommend that root-end filling materials should have a radiopacity greater than that for root canal sealers.     

Microleakage of intermediate restorative materials

This study compares the microleakage of a glass ionomer cement, Ketac Fil, used without cavity conditioning, with the established intermediate restorative materials, Cavit-W, and a reinforced zinc oxide-eugenol cement, Kalzinol. Microleakage was assessed using an electrochemical technique. At the end of 30 days, the materials tested, listed in decreasing order of microleakage, were Cavit-W, Ketac Fil inserted without cavity conditioning, Kalzinol, and the control group of Ketac Fil inserted into conditioned cavities. There was no significant difference in the microleakage observed in Ketac Fil restorations inserted without cavity conditioning and Kalzinol (p = 0.450), while the differences between the other groups were highly significant (p less than 0.001).     

Antibacterial activity of potential retrograde root filling materials

Abstract The antibacterial activity of potential retrograde root filling materials was assessed using the agar diffusion inhibitory test. A light-cured glass ionomer cement (Vitrebond) and three reinforced zinc oxide-eugenol cements (Kalzinol, IRM & ethoxybenzoic acid [EBA] cement) were compared with amalgam, a commonly used retrograde root filling material. Forty standardized pellets of each material were produced. Fresh, and materials aged for 1 week in sterile distilled water, were placed on blood agar plates inoculated with Streptococcus anginosus (milleri) or Enter -ococcus faecalis. At intervals of 3, 7 and 10 days, the presence and diameter of zones of inhibition were recorded. The diameter of the zones of inhibition increased with time for all materials, both fresh and aged. Vitrebond had the most pronounced antibacterial activity against both bacteria, producing the largest zone of inhibition, followed by Kalzinol. Amalgam had no measurable inhibitory effect whether aged or fresh, regardless of the period of exposure. There was no statistically significant difference in the response of the two bacteria. However, there were statistically significant differences between materials, period of exposure, and between fresh and aged materials (P < 0.001). Kalzinol, IRM and EBA cement were more antibacterial when aged than fresh, whilst Vitrebond was more active when fresh. Vitrebond was the only material for which the diameter of the zones of inhibition was reduced after ageing but it had the most pronounced antibacterial activity compared with the other materials. The antibacterial activity of the materials was ranked in the following order: Vitrebond > Kalzinol > (IRM = EBA cement) > amalgam.     

Cytotoxicity of potential retrograde root-filling materials

Abstract The Cytotoxicity of potential retrograde root-filling materials was assessed using the Millipore filter method. A light-cured glass ionomer cement, Vitrebond (VB), and three reinforced zinc oxide-eugenol cements, Kalzinol, IRM and ethoxybenzoic acid (EBA) cement, were compared with amalgam. Twenty standardized pellets of each material, 10 fresh and 10 aged by storage in sterile distilled water for 72 h were produced. Ten filters were included as controls: five filters with a cell monolayer, but without test specimens, and another five without cells but with test specimens. Fresh IRM exhibited the most pronounced cytotoxic effect and the difference was statistically significant compared with all the other materials. There was no statistically significant difference between fresh VB, Kalzinol, EBA cement and amalgam. When aged, Kalzinol was the most cytotoxic and the difference was statistically significant compared with the other materials. Aged IRM was the second most cytotoxic material and this too was statistically different. The Cytotoxicity of VB, EBA, and amalgam did not differ significantly from one another.     

Effect of addition of hyroxyapatite on the physical properties of IRM

The aim of this study was to evaluate the effect of adding 10% and 20% hydroxyapatite (HAP) to Intermediate Restorative Material (IRM) on physical properties such as working time, setting time, compressive strength and disintegration rate. The working and setting times were determined by an indentation method. The ISO recommended method was used to determine compressive strength. The rate of disintegration in vitro was evaluated in buffered sodium citrate at pH 4.5, 5.8, buffered phosphate at pH 7.0 and in bovine serum (pH 6.8), and examined using a replica method and scanning electron microscopy. Kalzinol and EBA were used as control materials for the disintegration experiment. IRM had longer mean working (4 min 43.5 s) and mean setting (6 min 28.5 s) times than IRM + 10 or 20% HAP (P<0.001), the mean reductions being 16% and 9% for IRM + 10% HAP, and 29% and 19% for IRM + 20% HAP, respectively. IRM had a greater compressive strength (68.5 MPa, P<0.01) than IRM + 10% HAP (65.0 MPa) or IRM + 20% HAP (60.0 MPa, P<0.001). Kalzinol, IRM + 10% HAP and IRM + 20% HAP were found to disintegrate after 8 weeks in buffered phosphate and in bovine serum. In contrast, IRM and EBA showed no noticeable signs of disintegration after 6 months in the same media. The physical properties of IRM + 10% HAP and IRM + 20% HAP were reduced compared with IRM but the reductions were not considered to be of clinical significance.     

The effects on the dental pulp of a composite resin and two dentine bonding agents and associated bacterial microleakage

The pulpal reaction associated with a composite resin alone and composite resin used in conjunction with two dentine bonding agents was studied. Class V cavities were prepared on the labial surfaces of the canine teeth of 18 male ferrets. After acid etching of the enamel margins, the cavities were restored with either a composite resin alone or in combination with one of two dentine bonding agents, Scotchbond and Gluma. One cavity in each animal was filled with Kalzinol as a control. The animals were killed after 7, 14 and 28 days. After histological processing, the pulpal changes were assessed qualitatively and quantitatively according to standard criteria. There were variations in the pulpal response at all time intervals. The responses to the two dentine bonding agents were similar to those found with composite resin alone. No pulpal inflammation was observed in the control teeth. Gram-positive micro-organisms were identified at the interface of restoration and cavity wall, or within the dentinal tubules in virtually all cases in which pulpal inflammation was observed.     

A comparison of two liner materials for use in the ferric sulfate pulpotomy

OBJECTIVES: The aim of this study is to compare the success rate obtained when applying either a calcium hydroxide (Dycal) base or a zinc oxide-eugenol (Kalzinol) base following the traditional ferric sulfate pulpotomy. METHODS: Patients were either treated in the chair or under general anaesthesia. All teeth had to have radiographic evidence of caries close to the pulp. After haemostasis was achieved with damp cotton pellets, ferric sulfate was applied to the pulpal stumps. Half of the cases then received a Dycal base followed by a cured layer of Vitrebond and a permanent amalgam restoration. The other half of the cases received a base of zinc oxide-eugenol (Kalzinol) followed by an amalgam restoration. The cases were followed up every 6 months for one year (ie. 2 follow-up visits). Radiographs were taken at each follow-up visit. RESULTS: Overall, teeth treated with Dycal demonstrated a higher failure rate when compared with those that received the Kalzinol base. Abscess formation and internal resorption were the most common causes of failure. Even though the Kalzinol base demonstrated greater success, there were still quite a few failures. CONCLUSION: This study demonstrates that calcium hydroxide cannot be recommended as a medicament in primary tooth pulpotomies.     

Radiological assessment of the effects of potential root-end filling materials on healing after endodontic surgery

Abstract The effects of three root-end filling materials on healing following endodontic surgery were assessed radiologically and correlated with histological findings reported elsewhere. The materials compared were a light-cured glass ionomer cement (Vitrebond), a reinforced zinc oxide-eugenol cement (Kalzinol) and amalgam. The root canals of 27 two-rooted mandibular premolar teeth of six beagle dogs were inoculated with endodontic pathogenic bacteria to induce periradicular lesions. The roots were apicected and root-end cavities filled with the tested filling materials. The teeth and surrounding jaw were removed after 4 weeks (30 roots) or 8 weeks (24 roots). Radiographs were taken of each jaw section and subjected to image analysis. Healing was evaluated based on measurements of the size of the periradicular radiolucent areas. ANOVA disclosed no statistically significant differences in the size of the periradicular areas either between time periods or between materials. These results did not correlate with the tissue responses in the same material as assessed histologically and previously reported. The use of radiographs alone to assess healing after endodontic surgery in the dog mandible is unsatisfactory, and should not be regarded as a substitute for histological examination for the determination of healing.     

The sealing ability of IBM® with the addition of hydroxyapatite as a retrograde root filling

Abstract The effect of adding 10% & 20% hydroxyapatite (HAP) on the sealing ability of IRM (Intermediate Restorative Material) when used as a retrograde root filling was assessed using a confocal optical microscope with a fluorescent dye. This was compared with another reinforced zinc-oxide eugenol cement (Kalzinol), ethoxybenzoic acid (EBA) cement and amalgam. The root canals of 70 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 groups of 10 teeth each and filled with the test materials. A remaining group of 10 teeth were used as controls. The extent of dye penetration around IRM, IRM + 10% and IRM + 20% HAP was not significantly different. There was also no difference in the extent of dye penetration between EBA cement and IRM. However the sealing ability of both these materials was better than Kalzinol and amalgam. All the amalgam retro- grade root fillings leaked, exhibiting the poorest sealing ability. Dye penetrated into the root canals of all the positive controls whereas there was no dye penetration in the negative controls. The addition of 10% or 20% hydroxyapatite did not adversely affect the good sealing ability of IRM.     

Antibacterial activity of dental restorative materials

Summary. The antibacterial activity of several dental materials (zinc oxide-eugenol cement, Kalzinol, zinc phosphate cement, Silicap, Super Syntrex, Aspa, Chembond, Chemfil and Aquacem) was investigated in vitro against six micro-organisms isolated from ferret plaque ( Moraxella spp., Escherichia coli, Corynebacterium spp., Actinomyces viscosus, Enterococcus, Streptococcus sanguis ). All freshly mixed materials showed some degree of antibacterial activity, though the effects varied between micro-organisms. A ranking order was obtained for each material, and each material exhibited some reduction of effect after 72 hours' culture.
There was a substantial reduction in bactericidal properties of all materials 24 hours and 7 days after setting, this reduction being least for zinc oxide-eugenol cement. The possible relationship between the antibacterial activity of the materials, bacterial contamination of the cavity and the pulpal response is discussed.     

In vivo biocompatibility and biomineralization of calcium silicate cements

A new mineral trioxide aggregate (MTA) material has been developed with a modified composition that requires investigations to support its clinical use. This study evaluated the biocompatibility and biomineralization of this new MTA material and compared it with that of two other MTA cements over time. Tubes containing materials (or empty tubes as controls) were inserted into the subcutaneous tissues of 40 rats. On days 7, 15, 30, 60, and 90, the tubes were removed with the surrounding tissues, which were either stained with haematoxylin and eosin or von Kossa for further analyses or unstained for observation under polarized light. On days 7 and 15, moderate inflammation was observed in most specimens, and the fibrous capsule was thick. On day 30, there was mild inflammation in all groups, and the fibrous capsule was thin. On days 60 and 90, there was mild inflammation in the material groups, while the control group showed no inflammation, although no statistically significant difference between the groups was observed and the fibrous capsule was thin. All material groups showed structures that stained with von Kossa and could be observed under polarized light; this was not found for the control. In conclusion, the new MTA material had biocompatibility and biomineralization properties similar to those of the two existing MTA materials.