An evaluation of the biocompatibility of a glass ionomer-silver cement in rat connective tissue

Glass Ionomer Root Canal Sealers

Since their introduction, glassionomer cements have undergone changes in formulations and have been endorsed for a number of clinical applications. Consistent reporting of bio-compatibility, durable adhesion, and beneficial fluoride release have followed the evolving glass ionomer cement. This report recommends the use of glass ionomer cements as root canal sealers and describes their application in the dog.

Antibacterial Effect of Silver-Incorporated Flake-Shell Nanoparticles under Dual-Modality

Silver has been recognized as a broad-spectrum antimicrobial agent and extensively used in biomedical applications. Through a sequential one-pot synthesis strategy, we have successfully incorporated silver into flake-shell nanoparticles. Due to the simultaneous growth of networked nanostructures of silica and in situ reduction of silver ions, homogeneously distributed silver into the shell of the nanocapsule was formed. The antibacterial test indicated that the silver-incorporated silica nanocapsule exhibits effective antibacterial activity, inhibiting the bacterial growth by 75%. In addition, with the encapsulation of other antibiotic agent into the structure, an enhanced antibacterial effect under dual-modality could also be achieved.

A comparison of the in vitro cytotoxicity of conventional and resin modified glass ionomer cements

To evaluate cytotoxicity of experimental conventional and resin modified glass-ionomer cements on UMR-106 osteoblast cell cultures and cell cultures of NIH(3)T(3) mouse fibroblasts specimens were prepared for every experimental material and divided into: group 1.Conventional glass-ionomer cements: GC Fuji IX GP Fast, GC Fuji Triage and Ketac Silver; group 2. Resin modified glass-ionomer cements: GC Fuji II LC, GC Fuji Plus and Vitrebond; group 3. Positive control was presented by specimens of composite Vit-l-ecence® and negative control-group 4. was presented by α-minimum essential medium for UMR-106 - osteoblast-like cells and Dulbecco's Modified Eagle's Medium for NIH(3)T(3) mouse fibroblast cells. Both cell cultures were exposed to 10% of eluate of each single specimen of each experimental material. Experimental dishes were incubated for 24 h. Cell metabolism was evaluated using methyltetrazolium assay. Kruskal-Wallis test and Tukey-Kramer post hoc test for the materials evaluated on NIH(3)T(3) mouse fibroblast cells, as well as UMR-106 osteoblast-like cells showed significantly more cytotoxicity of RMGICs, predominantly Vitrebond to both GICs and composite- Vit-l-ecence®.The lowest influence on cell's metabolism on UMR-106 osteoblas-like cells was shown by Ketac Silver and the lowest influence on cell's metabolism on NIH(3)T(3) mouse fibroblast cells was shown by Fuji IX GP Fast. Statistical evaluation of sensitivity of cell lines UMR-106 osteoblast-like cells and NIH(3)T(3) mouse fibroblast cells, using Mann-Whitney test, showed that NIH(3)T(3) mouse fibroblast cells were more sensitive for the evaluation of cytotoxicity of dental materials.

Clinical applications of glass ionomers in endodontics: a review

Glass ionomer cements (GICs) are biocompatible and have capacities to release fluoride and to bond to dentine, and thus are appropriate for use in endodontics. This paper reviews the composition and properties of different GICs, including their biocompatibility and antibacterial activity, their applications as intraorifice barriers and root canal sealers, and their use in the repair of root perforations, root-end fillings and temporary coronal restorations.

Endodontic materials

This article presents a review of materials currently used in the practice of endodontics. Current endodontic materials include those that have been thoroughly tested by scientific investigation, clinical usage, and time, as well as others that are the result of new knowledge in the field of dental materials. Article sections are devoted to obturation materials, sealers, irrigation materials, smear layer removal, root-end filling materials, and intracanal medicaments. Knowing the particular qualities of materials can aid the clinician in choosing those that are appropriate for a given situation. Properties, components, and rationale for the materials' use are presented to aid the clinician in choosing materials for a particular need.

Reactions of connective tissue to amalgam, intermediate restorative material, mineral trioxide aggregate, and mineral trioxide aggregate mixed with chlorhexidine

The aim of this study was to histopathologically examine the biocompatibility of the high-copper amalgam, intermediate restorative material (IRM), mineral trioxide aggregate (MTA), and MTA mixed with chlorhexidine (CHX). This study was conducted to observe the rat subcutaneous connective tissue reaction to the implanted tubes filled with amalgam, IRM, MTA, and MTA mixed with CHX. The animals were sacrificed 15, 30, and 60 days after the implantation procedure. The implant sites were excised and prepared for histological evaluation. Sections of 5 to 6 microm thickness were cut by a microtome and stained with hemotoxylin eosin and examined under a light microscope. The inflammatory reactions were categorized as weak (none or few inflammatory cells < or =25 cells), moderate (>25 cells), and severe (a lot of inflammatory cells not to be counted, giant cells, and granulation tissue). Thickness of fibrous capsules measured five different areas by the digital imaging and the mean values were scored. Amalgam, IRM, and MTA mixed with CHX caused a weak inflammatory response on days 15, 30, and 60. MTA provoked an initial severe inflammatory response that subsided at the 30 and 60 day study period. A clear fibrous capsule was observed beginning from the 15 days in all of the groups. Within the limits of this study, amalgam, IRM, MTA, and MTA mixed with CHX materials were surrounded by fibrous connective tissue indicated that they were well tolerated by the tissues, therefore, MTA/CHX seemed to be biocompatible.

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 an experimental glass-ionomer cement sealer in rat mandibular bone

OBJECTIVE

The purpose of this study was to compare an experimental glass-ionomer cement sealer, KT-308, with a conventional zinc oxide-eugenol sealer, Canals, in terms of tissue compatibility and solubility.

STUDY DESIGN

Tissue reactions were examined under light and electron microscopes at 3 and 20 days after the implantation of either freshly mixed KT-308 sealer or Canals sealer into prepared cavities in rat mandibles.

RESULTS

At 3 days after implantation, no inflammatory reaction was seen around KT-308 sealer, which was in direct contact with the bone surface. In contrast, Canals sealer elicited an initially severe inflammation in the surrounding tissue. At 20 days, the majority of KT-308 sealer remained in the bone cavity. Canals sealer was largely absorbed and surrounded by fibrous tissue with many macrophages. An ultrastructural examination also revealed that no intervening tissue was present between the cut bone surface and the glass-ionomer cement sealer and that disintegrated zinc oxide-eugenol particles were engulfed by macrophages.

CONCLUSIONS

KT-308 sealer possesses better tissue compatibility and lower solubility compared with a conventional zinc oxide-eugenol sealer, suggesting its potential for use as a root canal sealant.

Mast cells in tissue response to dentistry materials: an adhesive resin, a calcium hydroxide and a glass ionomer cement

Synthetic materials used in dentistry may trigger various inflammatory responses. In order to evaluate biocompatibility, standardized implants of Calcium Hydroxide (CH), Glass Ionomer Cement (GIC) and Light-activated Dental Adhesive (LDA) were surgically introduced into Wistar rats' back bone. Six (experimental) animal groups, five each, and two Sham (S) groups were studied after 15 and 30 days from surgery. In each animal, the density of mast cells and interstitial fibrosis volume was evaluated by quantitative light microscopy. In addition, the interaction between the disk material and its fibrous capsule was evaluated by scanning electron microscopy. The density of mast cells per area (N(A)[mast cells]) was lower in CH group than in LDA group. GIC group displayed N(A)[mast cells] results intermediate between CH and LDA groups (p<0.05). The smallest interstitial fibrosis volume density (Vv[f]) was observed in CH group, then in GIC group, while the greatest in LDA group. After 30 days, the fibrosis in LDA group was 30% higher than in CH group (p<0.05). In S group, discreet fibrosis restricted to surgical area was present, with few mast cells near the vessels. Significant interaction between fibrous capsule and the surrounding disk material was most evident in CH group. The implanted materials induced mast cell migration, distinct fibrosis development, suggesting that CH is the most biocompatible material among those tested.

The hemolytic and cytotoxic properties of a zeolite-containing root filling material in vitro

OBJECTIVE

This in vitro study characterized the hemolysis and cytotoxicity of ZUT, an experimental glass ionomer cement (GIC) sealer with an added antimicrobial-containing zeolite (0.2% Zeomic w/w).

STUDY DESIGN

ZUT, Ketac-Cem (GIC component of ZUT), Ketac-Endo, and two AH 26 sealer formulations were tested at various times after mixing. Hemolysis produced by standardized specimens was determined spectrophotometrically (n = 6/material). Cytotoxicity was assessed by using a Millipore Filter test with a HeLa cell monolayer (n = 10/material). Tests were repeated, and results were analyzed with a one-way analysis of variance (alpha = .05).

RESULTS

Disks of AH 26 containing silver produced the most hemolysis of all test groups (P < .0001). Compared to controls, GICs and AH 26 formulations were noncytotoxic at 1 and 6 hours after mixing, respectively (P > .05). Addition of Zeomic did not increase the cytotoxic and hemolytic activity of Ketac-Cem (P > .05).

CONCLUSION

Overall results suggest ZUT is less cytotoxic than AH 26 and possesses characteristics similar to the other GIC formulations tested.

Adhesion of a glass-ionomer root canal sealer to the root canal wall

Glass-ionomer root canal sealer is commonly used because of its chemical bonding and favorable physical characteristics when bonding to dentin. This study was designed to determine the tensile bond strength of a glass-ionomer sealer (Ketac Endo, Espe, Seefeld, Germany) on root canal walls after pretreatment with different conditioners. Flat inner surfaces of root canal specimens were prepared. The specimens were divided into five groups of 10 teeth, and the groups were conditioned with one of the following smear layer removal solutions: 15% EDTA/NaOCl, 10% polyacrylic acid, 35% phosphoric acid, 6% citric acid, and 5.25% NaOCl as a control. Then the exposed root canal areas were coated with Ketac-Endo. Tensile bonding was measured using a universal testing machine until ultimate failure was obtained. The groups that were treated with phosphoric acid and citric acid showed significantly higher bond strengths than the groups that were treated with 15% EDTA and polyacrylic acid (p < 0.05). Bonding to dentin without smear layer removal (NaOCl group) was too low to be measured in the testing apparatus. Scanning electron microscopy confirmed that phosphoric and citric acids were more effective in removing smear layer than EDTA or polyacrylic acid. The result supported the view that pretreatment with phosphoric acid or citric acid should be used in association with glass-ionomer root canal sealer to achieve the most effective removal of the smear layer and to provide better adhesion.

Cytotoxicity of fluoride on human pulp cell cultures in vitro

OBJECTIVES

Numerous studies have revealed that conventional glass-ionomer cements might release fluoride into an aqueous environment. The objective of this study was to examine the effects of fluoride on human pulp cells in vitro.

STUDY DESIGN

H33258 fluorescence, cell proliferation, protein synthesis, and mitochondrial activity assay were used to investigate the pathobiological effects of fluoride on cultured human pulp cells.

RESULTS

Fluoride was found to be a cytotoxic agent to cultured human pulp cells by inhibiting cell growth, proliferation, mitochondrial activity, and protein synthesis.

CONCLUSIONS

Fluoride release has significant potential for pulpal toxicity.

Reaction of bony tissue to implanted silver glass ionomer and a reinforced zinc oxide-eugenol cement

OBJECTIVE

To evaluate the tissue responses to implants of Ketac Silver and Super EBA cement in the guinea pig mandible.

STUDY DESIGN

Sixteen guinea pigs were used for 2 experimental periods of 4 and 12 weeks. Both materials were placed in Teflon applicators and implanted into surgically prepared sites in the mandible. A histologic examination for reaction to the material occurred after the animals were killed and processed.

RESULTS

After 4 weeks, minimal inflammatory reactions were observed in Ketac Silver implants, whereas the Super EBA implants showed minimal to moderate inflammation. Localized foreign body reaction was present in areas of fragmented small particles of Ketac Silver. At 12-weeks observation, no inflammatory reactions were present around either material. Direct bone contact was observed in 1 Ketac Silver implant.

CONCLUSIONS

Ketac Silver and Super EBA cement elicited mild reactions under the conditions of this model. From a biologic point of view, these 2 materials may offer equal utility in endodontic surgery.

Tissue reaction to implanted root-end filling materials in the tibia and mandible of guinea pigs

The purpose of this study was to examine the tissue reaction to implanted mineral trioxide aggregate (MTA), amalgam, Intermediate Restorative Material, and Super-EBA in the tibias and mandibles of guinea pigs. After anesthetizing 20 guinea pigs, raising tissue flaps, and preparing bony cavities, the test materials were placed in Teflon cups and implanted in the tibias and 10 days later in the mandibles. The animals were euthanized 80 days later and the tissues prepared for histological examination. The presence of inflammation, predominant cell type, and thickness of fibrous connective tissue adjacent to each implant were recorded. The tissue reaction to MTA implantation was the most favorable observed at both sites; as in every specimen, it was free of inflammation (p < 0.01). In the tibia, MTA was the material most often observed with direct bone apposition. Based on these results, MTA seems to be a biocompatible material.

Apical leakage of a new glass ionomer root canal sealer

A new glass ionomer root canal sealer (Ketac-Endo) has been developed. The purpose of this study was to compare the apical leakage of Ketac-Endo and AH26 using two different filling techniques and a controlled vacuum procedure. Sixty-four extracted human maxillary anterior teeth were instrumented and divided into four groups of 15 roots each. The groups were obturated as follows: group 1, a single cone technique and Ketac-Endo; group 2, a lateral condensation technique and Ketac-Endo; group 3, a single cone technique and AH26; and group 4, a lateral condensation technique and AH26. After storage in 100% humidity at 37 degrees C for 1 wk, the root surfaces were coated with two layers of nail polish and sticky wax. All specimens were immersed in a vacuum flask containing 2% methylene blue dye solution. The air was evacuated with a vacuum pump. The roots were sectioned longitudinally, and the linear extent of dye penetration was measured. Statistical analysis revealed that there were no significant differences between any of the groups.

Inhibition by glass-ionomer cements of protein synthesis by human gingival fibroblasts in continuous culture

The effects of several glass-ionomer cements (Baseline and Chem Fil of De Trey; Ketac Fil and Ketac Bond of ESPE; Vitrebond and Vitremer of 3 M) on the protein synthesis of cultured gingival fibroblasts were studied. The presence of cements in the culture medium inhibited protein synthesis, although the relative effectiveness varied significantly. The cements tested have been ranked in three groups, group A (Chem Fil and Ketac Fil), group B (Ketac Bond and Baseline) and group C (Vitrebond and Vitremer), showing 50, 75 and 100% reduction in protein synthesis, respectively. Incubation of cells with medium previously conditioned by Baseline and Ketac Fil caused only transient inhibition of protein synthesis followed by almost complete recovery. This recovery was not observed when the medium was conditioned with Vitrebond. A characterization of the factors determining the inhibitory effect of one cement in each group was attempted. The cements, irrespective of the type, produced small but reproducible decreases in the pH of the medium but released fluoride ions to a different extent. Both changes in the pH of the medium and in the fluoride concentration inhibited protein synthesis by cultured gingival fibroblasts. The different action of cements can be explained, at least in part, by a differing release of fluoride ions.

In vitro antibacterial activity of a glass ionomer endodontic sealer

The aim of this study was to evaluate the antibacterial activity of a recently introduced glass ionomer endodontic sealer, Ketac Endo (KE), compared to a commonly used ZOE-based endodontic sealer, Roth's cement (RC). With the use of E. faecalis as a test organism, the agar diffusion test (ADT) and direct contact test (DCT) were performed. For the DCT, the sealers were mixed and placed on the side wall of microtiter plate wells. A 10 microL bacterial suspension was placed on the tested material samples 20 min, 24 h, and 7 days after mixing. Bacteria were allowed to directly contact the sealers for 1 h at 37 degrees C. Fresh media was then added and bacterial growth was measured every 30 min over 15 h. The results showed that in the ADT, freshly mixed KE exhibited a twofold greater inhibition zone than RC (p < 0.05); in the DCT, freshly mixed KE and RC completely inhibited bacterial growth. The 24-h and 7-day samples of KE showed no antibacterial activity, whereas RC continued to exhibit a strong effect with similar samples. It has been concluded that KE possesses a short-acting very potent and diffusable antibacterial activity, whereas RC extends its effect over 7 days after setting.

Comparison of the intraosseous biocompatibility of Vitremer and super EBA by implantation into the mandible of rabbits

OBJECTIVES

This study compared the intraosseous biocompatibility of Vitremer, a new hydrophilic glass-ionomer cement, to that of Super EBA.

STUDY DESIGN

Twenty-two New Zealand rabbits were anesthetized, the mandibular bone exposed, and two holes were drilled through the cortical plate. The materials were loaded into silicone carriers and inserted into the mandibles. Eleven rabbits were killed 4 weeks after implantation, 11 animals after 12 weeks. The mandibles were prepared with standard histologic procedures; the tissue reactions were graded from none to very severe.

RESULTS

At 4 weeks Vitremer implants showed very slight to slight reactions, and the Super EBA implants showed slight reactions and one moderate reaction with no significant difference between the two materials. At 12 weeks, bone healing had occurred, despite the persistence of some fibrous tissue interposition. The reactions were classified as none to very slight for Vitremer and very slight to slight for EBA. Statistical analysis showed better results for Vitremer at 12 weeks.

CONCLUSION

The intraosseous biocompatibility of Vitremer was similar at 4 weeks and superior at 12 weeks to that of Super EBA. Its other properties should be evaluated before considering its use in clinical practice.

Comparison of the intraosseous biocompatibility of Dyract and Super EBA

The purpose of this study was to compare the intraosseous biocompatibility of Dyract, a new hydrophilic glass-ionomer cement, to that of Super EBA. Twenty-four New Zealand rabbits were anesthetized, one leg was shaved, the femur exposed, and two holes were drilled through the cortical plate. The materials were loaded into silicone carriers and inserted into the femur. Half of the rabbits were killed 4 weeks after implantation and the other half at 12 weeks and the femurs were prepared using standard histological procedures. The tissue reactions were graded from none to severe. At 4 weeks both materials showed slight to moderate reactions, characterized by the presence of fibrous tissue interposition and inflammatory cells. At 12 weeks, bone healing had occurred, despite the persistence of some fibrous tissue interposition, and the reactions were classified as slight. At both observation periods, statistical analysis failed to show any difference between the two materials indicating that Dyract and Super EBA had similar intraosseous biocompatibility.

Excisional wound healing following the use of IRM as a root-end filling material

Intermediate Restorative Material (IRM) has been advocated as a root-end filling material based primarily on reports of clinical success and various leakage studies. The objectives of this study were to determine the excisional wound healing responses of the periradicular tissues to IRM root-end filling material and to compare this with the wound healing responses to amalgam and orthograde gutta-percha root-end filling materials. Mandibular premolars in dogs were obturated, root-ends resected, and the healing responses associated with root-end fillings of IRM, amalgam, and orthograde gutta-percha were evaluated microscopically and radiographically at postsurgical intervals of 10 and 45 days. The excisional wound healing responses associated with IRM root-end fillings were normal at both postsurgical intervals. There was no evidence of inhibition of dentoalveolar or osseous wound healing associated with IRM, amalgam, or orthograde gutta-percha. Statistical analysis showed no difference in wound healing between the 3 root-end filling materials.

Root perforations: classification and treatment choices based on prognostic factors

Root perforations are common complications of endodontic treatment or post preparation and often lead to tooth extraction. Successful treatment depends mainly on immediate sealing of the perforation and prevention of infection. Several factors affect the achievement of these goals, most important of which are: time of occurrence, size, and location of the perforation. A classification of root perforations, based on the above factors, is presented to assist the clinician in the choice of the treatment protocol which will give the best possible results when a perforation is diagnosed.

Extraoral apical elongation of deeply damaged roots with titanium posts. A comparison of 2 methods

42 very deeply fractured or otherwise damaged single roots which could not be saved by intra-alveolar transplantation only were replanted to a supragingival level after extraoral transapical elongation by either an ordinary titanium root screw (method 1) or a specially designed titanium post (TransApex, Dentatus) (method 2). After observation periods of x = 73 months (method 1) and x = 34 months (method 2), 61% and 85% of the cases-respectively, were considered successful, fulfilling all 5 predefined success criteria. No other resorptions than slight surface resorptions were seen and all teeth showed very shallow pocket depths and physiological mobility, indicating that the long extraoral treatment had not caused lasting traumatic injury to the PDL cells. The most frequent complication in method 1 was periapical osteitis, indicating that the elongation system had become insufficient. On the other hand, the method showed the capacity to heal many of the pre-existing osteitis cases. Both root elongation techniques described in this report are comparatively inexpensive and safe, since the apical elongation is never extended beyond the lamina dura structure of the alveolus. Method 2 is to be preferred, however, as the specially designed through-and-through post-system which simultaneously provides apical closure, transapical elongation and coronal retention, allows treatment of even very short roots and seems to give better results.

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.

Repair of incomplete vertical root fractures in endodontically treated teeth--in vivo trials

An in vivo clinical study was performed to evaluate the healing of a new approach to the repair of incomplete vertical root fractures. The two-stage surgical procedure incorporated ultrasonic fracture cleaning, bonding of the fracture repair with silver glass-ionomer cement, placement of a bone graft material, and application of guided-tissue regeneration. Of the six roots in the study, five failed within 2 to 11 months. One root continued to be symptom-free, without periodontal pocket formation for 1 yr, but then failed because of extension of the incomplete root fracture to the lingual of the root.

An in vitro evaluation of microleakage of a new root canal sealer

An in vitro dye leakage study was performed to compare the apical microleakage of Ketac-Endo root canal sealer with that of Roth's 801E and AH26 sealers. Sixty-four single-rooted human teeth were instrumented and randomly divided into four groups. Three groups were obturated with laterally condensed gutta-percha and either Roth's 801E, AH26, or Ketac-Endo as the sealer. A fourth group was obturated using a single master cone and the Ketac-Endo sealer. The teeth were suspended in 1% methylene blue dye for 6 days. The teeth were then longitudinally sectioned and evaluated for linear apical dye penetration. In general, Ketac-Endo root canal sealer showed greater dye penetration than Roth's 801E and AH26. There was no statistical difference in leakage between the laterally condensed Ketac-Endo group and the single-cone-obturated Ketac-Endo group.

Tissue reaction to implanted super-EBA and mineral trioxide aggregate in the mandible of guinea pigs: a preliminary report

In vitro sealing ability and biocompatibility tests on mineral trioxide aggregate (MTA) have shown similar or better properties for this material than for existing root-end filling substances. The purpose of this study was to examine the tissue reaction of implanted Super-EBA and MTA in the mandibles of guinea pigs. After anesthetizing seven guinea pigs, raising a tissue flap and preparing two bony cavities, the test materials were placed in Teflon cups and implanted in the mandibles. Two bony cavities without implanted materials were left to heal and used as negative controls. The presence of inflammation, predominant cell type, and thickness of fibrous connective tissue adjacent to each implant was recorded. The tissue reaction to MTA implantation was slightly than that observed with Super-EBA implantation. Based on these results , it seems that both Super-EBA and MTA are biocompatible.

Redemption of a perforated furcation with a multidisciplinary treatment approach

A long-standing lesion associated with an undetected perforation of the furca in a mandibular molar was successfully managed using a multidisciplinary treatment approach. The sequence of therapeutic procedures involved conventional endodontic retreatment, an initial orthograde sealing of the perforation, guided tissue regeneration, and a subsequent orthograde resealing of the perforation with Ketac-Endo and Intermediate Restorative Material.

Cytotoxicity of four root end filling materials

Leakage and scanning electron microscopic studies have shown that a mineral trioxide aggregate (MTA) used as root end filling material permits significantly less leakage and has better adaptation than other commonly used root end filling materials. Because these materials are in contact with the periradicular tissues, their cytotoxicity should be evaluated before in vivo tests. Using the agar overlay and radiochromium methods, the cytotoxicity of amalgam, Super EBA, IRM, and the MTA was evaluated. Statistical analysis of the data from the agar overlay technique shows that freshly mixed and set amalgam were significantly less toxic than the rest of tested materials (p< 0.00005). Fresh and set MTA ranked second when tested for cytotoxicity with this technique. Similar statistical tests revealed a significant statistical difference between the toxicity of freshly mixed and set materials after 24 h of incubation with radiochromium-labeled mouse L929 cells. The degree of cytotoxicity of fresh and set materials was MTA least toxic followed by amalgam, Super EBA, and IRM. Based on the results of the cell culture methods used in this study it appears that MTA is a potential root end filling material and warrants further in vivo evaluations.

Adhesion of a glass ionomer cement to human radicular dentine

The adhesion of cements to root canal surfaces is a crucial factor for strengthening non-vital teeth--weakened due to extensive loss of tooth structure--by cemented posts. The aim of this study was to determine the tensile strength of a glass ionomer cement (Ketac-Cem) on root canal walls following pretreatment with conditioners. Upon cleaning and shaping, 56 straight root canals--divided into seven groups--were conditioned with one of the following solutions: NaOCl (1%) + EDTA (20%), H3PO4 (37%), HNO3 (2.5%), citric acid (6%), polyacrylic acid (10% and 20%) and NaCl (0.9%) as control. Standardized dentine cylinders were prepared out of the coronal half of each root perpendicular to the root axis and subsequently split. The exposed root canal areas were coated with Ketac-Cem. Using an universal testing machine a tensile force was applied to Ketac-Cem up to fracture. Pretreatment with EDTA-NaOCl provided the strongest bond strength (2.2 MPa). The median values for the other conditioning solutions ranged from 1.2 to 1.9 MPa. The significantly weakest bond (0.5 MPa) was recorded for NaCl. The elimination of the smear layer appeared to be an essential factor in order to improve the adhesion.

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.

Comparison of apical leakage between Ketac Endo sealer and Grossman sealer

Forty-eight extracted human teeth were prepared for study to compare Ketac Endo cement with Grossman's cement in preventing leakage of a dye. Four groups were formed: (1) Grossman's sealer with a single gutta percha cone; (2) Grossman's sealer with lateral condensation of gutta percha; (3) Ketac Endo sealer with a single cone of gutta percha; and (4) Ketac Endo sealer with lateral condensation of gutta percha. The teeth were immersed in the dye for 10 days, after which they were rinsed in running tap water and cleared for observation. In the groups of teeth evaluated by three individual evaluators, the results consistently showed less leakage with glass ionomer sealers (groups 3 and 4) than with the Grossman's sealers (groups 1 and 2). The best results were noted when Ketac Endo sealers were used with lateral condensation.

An evaluation of apical leakage of a glass ionomer root canal sealer

An in vitro dye leakage study was performed to compare the apical microleakage of a glass ionomer root canal sealer to Roth's 801 sealer. Forty-five single-rooted teeth were randomly divided into three groups: Ketac-Endo, Roth's 801, and the control group (no sealer). All groups were instrumented using a step-back technique and obturated with laterally condensed gutta-percha. The teeth were placed in a vacuum chamber under a pressure of 710 torr for 15 min and then immersed in India ink under vacuum for 24 h. The teeth were allowed to passively stain for 4 days and were cleared and evaluated for linear dye leakage using a binocular dissecting microscope. Statistical analysis revealed that sealer significantly improves the apical seal of laterally condensed gutta-percha. However, the apical seal exhibited by Ketac-Endo was not significantly different from that provided by Roth's 801 sealer.

An in vitro evaluation of microleakage of two new and two old root canal sealers

An in vitro comparison of apical microleakage of four root canal sealers was performed using a dye leakage/clearing method. Ketac-Endo, Tubliseal (old formula), Tubliseal (new formula), and Roth's 801 cement were compared with a control group of teeth obturated with laterally condensed gutta-percha and no sealer. Teeth were instrumented, obturated, demineralized, and cleared. Linear dye penetration was determined by dissecting microscope. Results were analyzed statistically. All groups obturated with sealer displayed significantly less leakage than the control group. There was no difference between the Tubliseal formulations, and the Ketac-Endo showed significantly more leakage than the three zinc oxide-eugenol-based sealers.

Biocompatibility of glass ionomer cements

Glass ionomer cements (GICs) are widely used in the dental field and are increasingly being considered as materials with potentially good osteogenic properties. This paper details a comprehensive biocompatibility evaluation of a number of GICs. These include conventional, commercially available materials, novel formulations and a new light cured material. The experimental programme entailed in vitro cell culture studies using direct contact and extraction tests and an in vitro rat model in which the GICs were in intimate contact with bone for periods up to 8 wk. The results demonstrate clear differences between the materials and in particular highlight the poor cellular response to the light cured material. Methylthiazolyldiphenyl tetrazolium assay demonstrates stimulation of cell growth by some GIC formulations and indicates that cytotoxic leachable agents can be removed from others. The results obtained following implantation into bone are comprehensively presented using photomicrographs. New bone formation with time is demonstrated with a number of formulations.

Tissue reactions to endodontic materials implanted in the mandibles of guinea pigs

Teflon, Intermediate Restorative Material, and Prisma VLC Dycal were implanted in the mandibles of 16 guinea pigs. After experimental periods of 4 and 12 weeks, the animals were killed and tissue sections were prepared. No severe inflammatory response was noted in any of the groups except for a persistence of moderate inflammation in the poorly condensed Teflon group. Bone apposition occurred in the Prisma VLC Dycal group; none-to-mild inflammation and a thin fibrous capsule characterized the IRM group; and the Teflon group had a thick fibrous encapsulation except for samples where the Teflon material appeared to be poorly condensed and dispersed into the bony tissue. In areas where the teflon was loosely condensed, chronic inflammation and active phagocytosis were seen along the surface of the 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).

Reinforced glass-ionomer cements--a review of properties and clinical use

In recent years, two new metal-reinforced Glass-ionomers have been introduced. The aim has been to develop a cement which can be used successfully as a replacement for amalgam. This paper reviews the published literature on the mechanical properties and clinical use of both the cermet and so-called 'Miracle Mix' cements. The published results do not suggest an improvement in strength or adhesion to tooth material; wear resistance is improved, however. One problem encountered in reviewing this literature is the wide variation in test methodology and hence results. In clinical use, the metal-reinforced cement has been successful in Class I and II restorations, particularly using the tunnel technique, and has potential for use in a number of other applications.

Comparative tissue tolerance of a new endodontic sealer

An experimental radiopaque resin root canal sealer was tested for tissue biocompatibility in rat connective tissue. The controls were four widely used sealers: Sealapex, Kerr's sealer, AH-26, and Roth's sealer. Polyethylene tubes were filled with the sealers and allowed to set for 24 hours in 100% humidity. Each sealer was implanted in the connective tissue of Sprague-Dawley rats and removed after 3, 10, 20, 30, and 60 days, fixed, and histologically prepared for light microscope evaluation. At each time period there was practically no difference in the reaction of all the sealers. By 60 days, the total picture was one of well-tolerated biocompatibility.

Resistance to fracture of endodontically treated roots

The root canals of 48 single-canal canine teeth were prepared by four different methods. The coronal lingual wall and root canal space were lowered to 2 mm below the buccal wall of the roots. The prepared root was placed into acrylic resin so that 12 mm of buccal root was exposed. A slowly increasing force was applied at the junction of the buccal wall and root canal space until fracture occurred. The force of fracture of the buccal root wall of each root was recorded and the results in each group were compared. All teeth fractured at the buccal wall/acrylic resin junction. Instrumentation of the root canals significantly weakened the roots. Obturation of the canals in conjunction with Roth's 801 sealer did not strengthen the roots. Obturation of the canals in conjunction with a glass ionomer sealer significantly strengthened the roots as compared with roots instrumented but not obturated and those obturated with gutta-percha and Roth's 801 Sealer.

A new glass ionomer root canal sealer

Various physical characteristics of a new glass ionomer root canal sealer were tested. These included setting time, ease of delivery to the root canal, adaptability and adhesion to the dentinal wall of the root canal, and radiopacity. Scanning electron micrographs and electron microprobe analyses were made. The characteristics were compared with those of Grossman's sealer. The results indicated that, with respect to the properties tested, the glass ionomer sealer was superior to Grossman's sealer.

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.

Experimental oral foreign body reactions. Commonly employed dental materials

Foreign bodies and tissue reactions to foreign materials are commonly encountered in the oral cavity. The more common lesions include apical deposition of endodontic materials, mucosal amalgam and graphite tattoos, myospherulosis, oil granulomas, and traumatically introduced dental materials and instruments. Since many foreign materials are unidentifiable histologically, commonly used dental materials were experimentally implanted subcutaneously in rats to assess local host responses and characterize the nature of these materials microscopically. The histologic characteristics of these foreign body reactions are detailed herein. The implanted materials corresponded to reactions seen in human subjects.