Longitudinal sealing ability of mineral trioxide aggregate as a root-end filling material

Weakened anterior roots--intraradicular rehabilitation

This paper highlights the fact that many anterior teeth requiring restoration are severely weakened having wide, flared canal spaces, and thin dentinal walls that are prone to fracture. Traditionally these teeth have been restored using metal posts and are often unsuccessful because of lack of retention or root fracture. This paper describes how mineral trioxide aggregate (MTA) can be used to form an immediate apical seal rather than waiting months for apexification. Weakened roots can be reinforced using dentine bonding agents and composite resin and if insufficient coronal tooth structure is present a quartz-fibre post can be placed to retain a composite core.

MTA solubility: a long term study

The purposes of this long-term study was to assess the amount of soluble material released by Mineral Trioxide Aggregate to a water medium, to determine if the solubility differences between specimens of various water/powder ratio, as demonstrated in a previous study, would be maintained over time, and to measure the pH of the water that was in contact with the specimens. Specimens were processed at 0.28 and 0.33 water/powder ratios, and immersed in water according to the ISO 6876 standard. The specimens were periodically removed to assess salt content release and reimmersed in fresh water. Assay testing was periodically performed over a 78-day period. Results were expressed as Daily Solubility (solubility rate), and Cumulative Solubility. The mathematical projection from Cumulative Solubility to infinite time showed that MTA could solubilize 22.06% at 0.28 water/powder ratio, and 31.095% at 0.33 water/powder ratio of the specimens' mass in regards to their initial dry weight. MTA did maintain a high pH for an extended period of time under these study conditions.

Longitudinal study on microleakage of three root-end filling materials by the fluid transport method and by capillary flow porometry

AIM

(i) To compare the root-end sealing ability of IRM Caps (IRM), Fuji IX Capsules (Fuji IX) and Pro Root MTA Tooth-Coloured Formula (MTA) in teeth obtained from cadavers. (ii) Further research on leakage study methodology by means of comparison of the fluid transport method (FTM) and capillary flow porometry (CFP).

METHODOLOGY

Root canal treatment was performed on 33 cadaver teeth in situ 2 weeks prior to root resection and ultrasonic retropreparation (S12/90 degrees D-tip on Suni-Max), after which the teeth were retrieved from the cadavers. Two teeth were kept as positive and negative controls. The other teeth were divided in three different groups at random, with each group receiving one of the retrofill materials. Retrofills were exposed to water 5 min after placement. The teeth were stored at 37 degrees C for 12 h after which the root filling was removed. Microleakage (L in microL day(-1)) was measured for 24 h under a pressure of 1.2 atm using FTM and recorded as L = 0, 0 < L < or = 10, L > 10. The measurements were repeated after 1 and 6 months. After 6 months, leakage was also assessed by CFP in order to measure through pores and their diameters. Results were analysed statistically using nonparametric Kruskal-Wallis and Mann-Whitney U-tests, and Spearman correlation coefficients between the results of both methods were calculated. The level of significance was set at 0.05.

RESULTS

(i) A statistically significant difference could be demonstrated between Fuji IX and IRM at 1 month with FTM. FTM revealed a significant difference between Fuji IX and the other materials at 6 months, whereas CFP did not. However, using both methods, Fuji IX showed the best result. (ii) When comparing both techniques, CFP demonstrated through pores in all teeth, whereas with FTM in only 14 of the 31 teeth could through pores be demonstrated. A positive correlation between both methods was demonstrated.

CONCLUSIONS

Under the conditions of this study (i) the conventionally setting glass-ionomer cement Fuji IX showed the best results when used as a root-end material and (ii) CFP appeared to be a useful method for leakage evaluation of through pores in endodontics.

In-Vitro Evaluation of Microleakage of an Orthograde Apical Plug of Mineral Trioxide Aggregate in Permanent Teeth with Simulated Immature Apices

This in vitro study evaluated the seal created by varying depths of mineral trioxide aggregate (MTA) plugs placed in an orthograde fashion in five groups of 10 teeth. One group received a 2 mm thick orthograde apical plug of MTA, the second group a 5 mm apical MTA plug, and the third group a 2 mm apical MTA plug with a second 2 mm increment, 24 h later. The remaining portion of the canal in these groups was left unfilled. Group four received a 2 mm MTA plug that set for 24 h and the canal was then back-filled with gutta-percha and eugenol based sealer. Group five was a positive control without an MTA plug. The apical seal was tested using a bacterial leakage model of Actinomyces viscosus. Results showed a statistically significant difference in only the 5 mm apical plug, which completely prevented bacterial leakage.

Effect of ProRootR MTA mixed with chlorhexidine on apoptosis and cell cycle of fibroblasts and macrophages in vitro*

AIM

To compare the percentage of apoptotic cells and the cell cycle profile of fibroblasts and macrophages exposed to either ProRoot mineral trioxide aggregate (MTA) mixed with chlorhexidine (CHX), or exposed to ProRoot MTA mixed with sterile water.

METHODOLOGY

Mouse gingival fibroblasts or mouse macrophages were seeded in six-well plates and allowed to attach overnight. Freshly mixed or set (allowed to dry for 24 h) specimens of tooth-coloured (white) ProRoot MTA were prepared with 0.12% CHX gluconate (MTA/CHX) or with sterile water (MTA/H2O). The cells were exposed for 24 h to the MTA specimens, which were placed over permeable membrane inserts to avoid direct contact with the cells. Untreated cells served as controls. Propidium iodide staining followed by flow cytometry was used to evaluate the effects of ProRoot MTA on cell apoptosis and cell cycle. Statistical analyses were performed by one-way anova followed by post-hoc tests with the use of the SigmaStat 2.0 software, and significance was determined at P < or = 0.05.

RESULTS

MTA specimens containing CHX induced apoptosis of macrophages and fibroblasts (P < 0.05). In contrast, no change in the proportion of apoptotic cells was observed when sterile water was used to prepare the specimens (P > 0.05). Cell cycle analysis showed that exposure to MTA/CHX decreased the percentage of fibroblasts and macrophages in S phase (DNA synthesis) as compared with exposure to MTA/H2O (P < 0.05).

CONCLUSION

This in vitro study demonstrated that the substitution of CHX for sterile water in MTA increases its cytotoxicity. This suggests that the potentially beneficial antimicrobial effect of CHX may be accompanied by an increase in the cytotoxicity of the resulting MTA-based material.

Revascularization of immature permanent teeth with apical periodontitis: new treatment protocol?

A new technique is presented to revascularize immature permanent teeth with apical periodontitis. The canal is disinfected with copious irrigation and a combination of three antibiotics. After the disinfection protocol is complete, the apex is mechanically irritated to initiate bleeding into the canal to produce a blood clot to the level of the cemento-enamel junction. The double seal of the coronal access is then made. In this case, the combination of a disinfected canal, a matrix into which new tissue could grow, and an effective coronal seal appears to have produced the environment necessary for successful revascularization.

The Effects of Chlorhexidine Gluconate (0.12%) on the Antimicrobial Properties of Tooth-Colored ProRoot Mineral Trioxide Aggregate

The purpose of this in vitro study was to determine whether the substitution of 0.12% chlorhexidine gluconate for sterile water as a mixing agent would enhance the antimicrobial activity of tooth-colored ProRoot mineral trioxide aggregate (MTA) against Actinomyces odontolyticus (ATCC17982), Fusobacterium nucleatum (ATCC2586), Streptococcus sanguis (ATCC10556), Enterococcus faecalis (ER3/2S), Escherichia coli (SM10lambdapir), Staphylococcus aureus (ATCC6538), Pseudomonas aeruginosa (UME), and Candida albicans (ATCC10261). Two wells of 5-mm diameter were made in triplicate agar plates inoculated with standardized suspensions of each microorganism. MTA (33 mg) mixed with chlorhexidine (12 microl) or sterile water (12 microl) was placed to fill each well. Plates were incubated at 37 degrees C as required for microbial growth. A blinded, independent observer measured zones of inhibition. All MTA samples inhibited microbial growth regardless of mixing agent. MTA/chlorhexidine showed significantly larger zones of inhibition (p < 0.0002, paired t test). In conclusion, substituting 0.12% chlorhexidine gluconate for water enhanced the antimicrobial activity of tooth-colored ProRoot MTA.

Placement of Mineral Trioxide Aggregate Using Two Different Techniques

The purpose of this study was to determine if the adaptation of mineral trioxide aggregate (MTA) would differ when placed into simulated root canals of varying length when using two different placement and condensation methods. Hand condensation was compared to ultrasonic condensation. Eighty polyethylene tubes were divided into four groups of 20 tubes each. The tubes in the four groups were prepared to receive 3-, 5-, 7-, and 10-mm lengths of MTA respectively. Each group of 20 tubes was subdivided; 10 samples of each length had MTA placed and condensed by the hand method and the other 10 by the ultrasonic method. After condensation the samples were evaluated with a light microscope and radiographs for the degree of adaptation of the MTA to the tube walls and for the presence of voids within the MTA material itself. The results demonstrated an 80% agreement for findings between the light microscopy and radiographic evaluation. Hand condensation resulted in better adaptation to the tube walls and less voids than the ultrasonic method. There was no significant difference in the results for any of the four lengths of MTA placed by the hand method (p > 0.9). At this time hand condensation should be considered the preferred method for placement of MTA.

Measurement of periapical pressure created by occlusal loading

AIM

To develop an in vitro model in which the pressure in the periapical tissues can be measured during loading.

METHODOLOGY

Extracted human maxillary central incisors were embedded in resin blocks that had physical characteristics similar to those of bone and periodontal ligament. Each tooth was loaded with 20, 40, 50, 60, 75, 85, 100, 200, 300 and 450 N vertical forces from the incisal edge of the crown on three consecutive occasions. A minute resistor embedded in the periapical space was used to detect apical pressure changes during occlusal loading. The ratio of apical pressure changes (DeltaP) to the loading force changes (DeltaF) was calculated.

RESULTS

The periapical pressure detected was in direct proportion to the loading force. The mean value of DeltaP/DeltaF was 5.994 kPa N-1 (SD = 2.04).

CONCLUSIONS

Direct proportionality was found between the coronal loading and the apical hydrostatic pressure. The DeltaP/DeltaF ratio determined in this study makes it easier to estimate the apical hydrostatic pressure values during occlusal loading of single-rooted teeth. In this study, the apical pressure generated under occlusal loading was the same magnitude as that estimated with the finite element method.

Fluid movement along the coronal two-thirds of root fillings placed by three different gutta-percha techniques

AIM

To compare fluid movement (FM) along the coronal two-thirds of gutta percha/sealer root fillings placed by three different techniques.

METHODOLOGY

Three groups consisting of the roots of mandibular incisors were instrumented and obturated by cold lateral compaction (LC), warm vertical compaction (VC) or the single-cone technique (SC), using RoekoSeal Automix (RSA) as the sealer. The apical 4 mm of each root filling was removed, and FM along the remaining 7 mm of the root filling was measured.

RESULTS

The VC group displayed more FM than the other two groups (P = 0.023). No significant difference in FM was found between the LC and SC groups (P = 0.629).

CONCLUSIONS

The coronal two-thirds of the VC root fillings did not prevent FM when RSA sealer was used.

Osteoblasts and MG-63 osteosarcoma cells behave differently when in contact with ProRoot MTA and White MTA

AIM

To test the hypothesis that MG-63 osteosarcoma cells and primary osteoblasts react differently to ProRoot trade mark MTA (mineral trioxide aggregate) and White MTA by: (i) investigating the attachment of primary osteoblasts and MG-63 osteosarcoma cells to ProRoot trade mark MTA and White MTA; and (ii) comparing the osteogenic behaviour of both cell lines in contact with these endodontic materials.

METHODOLOGY

Primary osteoblasts were harvested from foetal rat calvaria by sequential digestion and MG-63 osteosarcoma cells were purchased. Cells were exposed to ProRoot trade mark MTA and White MTA prepared according to the manufacturer's instructions. All samples and controls were prepared in quadruplicate. After 6, 9 and 13 days exposure to MTA, the cells were fixed and prepared for SEM examination. In addition, both the cell types were grown to confluence and exposed to beta-glycerophosphate and dexamethasone to assess mineralized nodule formation as a function of osteogenic behaviour.

RESULTS

The number of cells on the surface of the culture dish and on top of the materials increased in all samples throughout the 3 time periods, except for White MTA where no primary osteoblasts were visible on top of the material by the end of 13 days. After exposing cells to differentiation medium nodules were observed in cultures of primary osteoblasts, but not of MG-63 osteosarcoma cells.

CONCLUSIONS

Under the conditions of this study, whilst primary osteoblasts initially bound to White MTA, they did not survive on the surface by the end of 13 days. Primary osteoblasts formed mineralized nodules when exposed to differentiation medium, whilst MG-63 cells did not form nodules. As MG-63 cells do not behave osteogenically by forming mineralized nodules, and primary osteoblasts are more sensitive than MG-63 osteosarcoma cells to White MTA in cell culture, primary osteoblasts are more appropriate than MG-63 cells for testing endodontic materials in cell culture.

Treatment of a non-vital immature incisor with mineral trioxide aggregate (MTA)

- A case of severe crown fracture and luxation in the upper permanent incisors of a 9-year-old boy is reported. The treatment of one of the injured teeth included apexification with calcium hydroxide and endodontic treatment with gutta-percha obturation. The other incisor was also treated with calcium hydroxide, but as there was no apical stop after 3 years of treatment, it was decided to use a new root-end filling material: mineral trioxide aggregate (MTA). At follow-up 12 months later, the tooth was asymptomatic and radiographically showed the initial repair of the radiolucent apical lesion.

Effect of root resection on the apical sealing ability of mineral trioxide aggregate

OBJECTIVE

The purpose of this in vitro study was to determine the minimum depth of mineral trioxide aggregate (MTA; ProRoot; DENTSPLY/Tulsa Dental, Tulsa, Okla) required to maintain an apical seal following root resection. Study design. In 10 instrumented teeth, MTA was used to obturate the apical 6 mm of the root canal and was allowed to set for 48 hours. Leakage was determined by means of a fluid filtration method at a pressure of 20 cm H(2)O. Leakage was measured before root resection, and after 3, 4, 5, and 6 mm apical resections. Data were analyzed by means of a Kruskal-Wallis one-way analysis of variance with P <.05.

RESULTS

Fluid leakage was shown to increase after each resection, but did not reach statistical significance (P <.05) until 4 mm of the apex had been removed.

CONCLUSION

The results indicate that root resection did not significantly affect the sealing ability of MTA when at least 3 mm of the MTA remained. Although there was a statistically significant difference in leakage following the 4 mm resection, it is unknown what the biological difference would be between the 3 mm and 4 mm resections.

Mineral trioxide aggregate (MTA) and calcium hydroxide as pulp-capping agents in human teeth: a preliminary report

AIM

To compare mineral trioxide aggregate (MTA) with calcium hydroxide when used as pulp-capping materials in human teeth.

METHODOLOGY

Eleven pairs of maxillary third molars in subjects between 20 and 25 years of age were subjected to mechanical pulp exposure. The exposed pulps were capped with MTA or calcium hydroxide, covered with ZOE and restored with amalgam. A total of 14 teeth were extracted after periods of 1 week (two molars) 2 months (three molars), 3 months (five molars), 4 months (two molars) and 6 months (two molars).

RESULTS

Histological evaluation demonstrated less inflammation, hyperaemia and necrosis plus thicker dentinal bridge and more frequent odontoblastic layer formation with MTA than calcium hydroxide.

CONCLUSIONS

Although the results favour the use of MTA, more studies with larger samples and a longer follow up are suggested.

The effect of irrigation with doxycycline or citric acid on leakage and osseous wound healing

This study investigated the effect of doxycycline irrigation on wound healing and the apical seal of three filling materials. Part 1: 220 extracted teeth received root canal therapy followed by root resection (2 mm) and ultrasonic root end preparations (3 mm). Groups of 20 were irrigated with saline, citric acid, or doxycycline and filled with amalgam, Super EBA, or MTA. Leakage was measured (mm) after decalcification and clearing. Part 2: two defects were made on each side of the mandible of 10 New Zealand rabbits. On each side, one defect was irrigated with saline and one with either citric acid or doxycycline. The animals were killed in groups of five at 9 and 18 days. Sections of each defect were stained with hematoxylin and eosin for evaluation of healing and bone fill. Super EBA and MTA leaked significantly less than amalgam, regardless of irrigant. Leakage after irrigation with doxycycline compared to citric acid or saline was not significantly different for Super EBA or MTA but was lower for amalgam. There was no significant difference in healing or bone fill among irrigants at 9 or 18 days.

An evaluation of accelerated Portland cement as a restorative material

Biocompatibility of two variants of accelerated Portland cement (APC) were investigated in vitro by observing the cytomorphology of SaOS-2 osteosarcoma cells in the presence of test materials and the effect of these materials on the expression of markers of bone remodelling. Glass ionomer cement (GIC), mineral trioxide aggregate (MTA) and unmodified Portland cement (RC) were used for comparison. A direct contact assay was undertaken in four samples of each test material, collected at 12, 24, 48 and 72 h. Cell morphology was observed using scanning electron microscopy (SEM) and scored. Culture media were collected for cytokine quantification using enzyme-linked immunosorbent assay (ELISA). On SEM evaluation, healthy SaOS-2 cells were found adhering onto the surfaces of APC variant, RC and MTA. In contrast, rounded and dying cells were observed on GIC. Using ELISA, levels of interleukin (IL)-1beta, IL-6, IL-18 and OC were significantly higher in APC variants compared with controls and GIC (p<0.01), but these levels of cytokines were not statistically significant compared with MTA. The results of this study provide evidence that both APC variants are non-toxic and may have potential to promote bone healing. Further development of APC is indicated to produce a viable dental restorative material and possibly a material for orthopaedic

Sealing ability of mineral trioxide aggregate and super-EBA when used as furcation repair materials: a longitudinal study

Immediate sealing of furcation perforations enhances the repair process. The purpose of this study was to longitudinally compare the ability of mineral trioxide aggregate (MTA) and Super-EBA to seal furcation perforations. Fifty-one extracted human maxillary molars were decoronated 3 mm above the CEJ, and the roots were amputated 3 mm below the furcation. A #2 high-speed round bur was used to perforate the center of the furcations. The canals were obturated with gutta-percha, and the root ends were sealed with C&B Metabond. Three experimental groups of 15 teeth each were restored with MTA, Super-EBA, or a combination of MTA in the perforation and a Super-EBA dome on the pulpal floor. Six teeth served as controls. Each tooth was affixed to a fluid filtration device and subjected to a pressure of 20 cm H2O. The integrity of the perforation seal was evaluated initially at 30 min for the Super-EBA and the combination groups and at 4 h for the MTA group. Additional measurements were then made at 24 h, 1 week, and 1 month. The controls behaved as expected. A two-way ANOVA revealed a significant difference (p = 0.01) between materials. Tukey's test isolated the difference to Super EBA as producing a superior seal but only at 24 h. There was no significant effect with time (p = 0.57) or the interaction of the materials with time (p = 0.66). All materials sealed the perforations very well. The maximum leakage of all materials was <0.007 microL min(-1) cm H2O(-1).

Leakage associated with intermediate restorative material and glass-ionomer cement retrograde fillings: a human and sheep teeth comparison with 2 different aging procedures

OBJECTIVES

Leakage around retrograde fillings is an important cause of endodontic surgery. This in vitro study sought to compare the following: (1) methylene blue dye leakage linked to retrofillings in human and sheep teeth with the degree of dye penetration when intermediate restorative materials and Chemfil were used as retrofillings, (2) the apical microleakage in filled with that in unfilled root canals, and (3) 2 storage techniques, incubator-based and subcutaneous implantation in rats.

STUDY DESIGN

Tested were 198 human and 196 sheep teeth that were retrofilled with intermediate restorative material or Chemfil, then stored in an incubator or subcutaneously in rats for 10, 20, and 30 days before immersion in methylene blue dye for 24 hours. Linear dye penetration was evaluated, and the results were statistically analyzed by means of analysis of variance.

RESULTS

Leakage between sheep and human teeth was significantly different (P <.05). Chemfil had significantly less leakage than intermediate restorative material after storage in rat (P <.05) for up to 20 days, but not after 30 days. No differences were found between leakage of unfilled and filled human root canal teeth.

CONCLUSIONS

The sheep incisor is a poor experimental model of the human tooth, and both aging procedures demonstrate extensive leakage of retrofilling materials after long-term storage.

Leakage evaluation of root end filling materials using endotoxin

Mineral trioxide aggregate (MTA) has been shown to possess excellent sealing ability when tested with dye, bacteria, and a fluid filtration technique. Endotoxin, a component of the cell wall of Gram-negative bacteria, has been proposed to play a role in the pathogenesis of periradicular lesions. This study used a modified Limulus Amebocyte Lysate test for the presence of endotoxin as a tracer and compared the sealing ability of Super-EBA, IRM, amalgam, and MTA. The results showed that MTA permitted less endotoxin leakage than IRM and amalgam at 1, 2, 6, and 12 wk (p < 0.05), and leaked less than Super-EBA at 2 and 12 wk (p < 0.05).

Obturation of a retained primary mandibular second molar using mineral trioxide aggregate: a case report

This case report demonstrates Mineral Trioxide Aggregate obturation of the root canal system of a retained primary mandibular second molar where no succedaneous permanent tooth was present. The technique seemed to provide a biocompatible seal of the root canal system in this case. It is not recommended for obturation of primary teeth that are expected to exfoliate since it is anticipated that Mineral Trioxide Aggregate would be absorbed slowly, if at all.

The outcome of endodontic resurgery: a systematic review

AIM

The aim of this paper is to establish an outcome standard for the assessment of healing radiographically after resurgery of persistent periradicular lesions by systematically reviewing the results from published studies.

METHODOLOGY

The systematic review process requires the definition of predetermined criteria delineating the inclusion parameters of studies reviewed. Of 42 papers that were reviewed, eight qualified for inclusion. A weighted-average was calculated from the results taken from the eight eligible, peer-reviewed studies, published between 1970 and 1997.

RESULTS

Three hundred and thirty patients out of 2375 (14%) from the included studies underwent resurgery for failure of healing as determined radiographically. Of this population, 35.7% healed successfully after resurgery, 26.3% healed with uncertain results and 38% did not heal at the one-year follow-up.

CONCLUSIONS

Although there is nearly equal distribution of results between all categories, a 35.7% rate of healing as assessed radiographically is essentially equivalent to the 38% failure rate. This paper will allow an evaluation of current research results to establish an outcome standard and enable techniques and filling materials to be evaluated and compared. Furthermore, the outcome standard can assist in defining demographic and aetiological factors that contribute to the potential outcome of resurgery cases.

A comparative evaluation of three root-end filling materials: an in vitro leakage study using Prevotella nigrescens

This study used Prevotella nigrescens to evaluate the sealing ability of Geristore, Super-EBA, and ProRoot when used as root-end filling materials. One hundred single-canal, extracted, human teeth were cleaned and shaped with Gates-Glidden burs and .04 Taper (ProFile Series 29) rotary instruments. The root-ends were resected, and a 3-mm deep root-end preparation was made with ultrasonic tips. After steam sterilization, the teeth were randomly divided into three groups of 30. Each group was root-end-filled with a different material. Five root-end cavities were left open and served as positive controls; another five root-end cavities filled with sticky wax and covered with two layers of nail polish acted as negative controls. The teeth were attached to presterilized snap-on plastic caps; the root-ends submerged into 12-ml vials of chopped meat carbohydrate broth and placed in an anaerobic chamber. Twice a week, a sterile micropipette was used to inoculate 0.1 ml of a broth culture of Prevotella nigrescens into the root canal of each tooth. Results after 47 days indicated there were no significant differences between the three root-end filling materials against penetration of Prevotella nigrescens.

A new mineral trioxide aggregate root-end filling technique

Carrier and syringe-type devices are currently used to deliver mineral trioxide aggregate as a root-end filling material. In certain surgical situations these devices may be too difficult to use because of the location of the surgical site and the small size of the root-end preparation. This paper describes a new technique to overcome these difficulties by the formation and delivery of mineral trioxide aggregate pellets.

Longitudinal microleakage evaluation of Super-EBA as a root-end sealing material

This study evaluated the sealing ability of fast and regular set Super-EBA with different powder-to-liquid ratios as a root-end filling material. Fifty extracted maxillary central incisors were uniformly cleaned and shaped using a crown-down technique with Gates-Glidden drills and Profile series 29.04 taper rotary instruments. After root-end resection and ultrasonic preparation, 48 root sections were randomly assigned to 4 groups of 12 teeth each and filled with a thick or thin mix of fast or regular set Super-EBA. Fast and regular set Super-EBA were mixed to a thick (1 scoop powder:1 drop liquid) or a thin (1 scoop powder:2 drops liquid) consistency. Positive and negative controls were used. Microleakage was assessed at 24 h, 72 h, 1 wk, 2 wk, 4 wk, 6 wk, and 8 wk using a fluid filtration system. There were no significant differences in the microleakage measured for any group at any of the time points evaluated. These results suggest that either fast or regular set Super-EBA mixed to various consistencies may be acceptable for root-end filling.

Mineral trioxide aggregate: a new material for endodontics

BACKGROUND

Mineral trioxide aggregate, or MTA, is a new material developed for endodontics that appears to be a significant improvement over other materials for procedures in bone. It is the first restorative material that consistently allows for the overgrowth of cementum, and it may facilitate the regeneration of the periodontal ligament.

CASE DESCRIPTION

The authors present five cases in which MTA was used to manage clinical problems. These included vertical root fracture, apexification, perforation repair and repair of a resorptive defect. In each case, MTA allowed bone healing and elimination of clinical symptoms.

CLINICAL IMPLICATIONS

Materials such as zinc oxide-eugenol cement and resin composite have been used in the past to repair root defects, but their use resulted in the formation of fibrous connective tissue adjacent to the bone. Because it allows the overgrowth of cementum and periodontal ligament, MTA may be an ideal material for certain endodontic procedures.

A comparison of MTA, Super-EBA, composite and amalgam as root-end filling materials using a bacterial microleakage model

AIM

The aim of this study was to compare traditional and newly developed root-end filling materials for resistance to bacterial microleakage.

METHODOLOGY

Sixty extracted single-rooted teeth were randomly divided into five groups for root-end filling with mineral trioxide aggregate, Super-EBA, TPH composite resin with ProBond dentine bonding agent, Dispersalloy amalgam with and without ProBond, and positive and negative control groups. Root canals were instrumented using the step-back technique and simulated root-end resections performed. Root-end filling materials were placed in 3 mm ultrasonic retropreparations. Nail varnish was applied to all external root surfaces to the level of the resected root ends to prevent lateral microleakage. Samples were sterilized in an ethylene oxide sterilizer for 12 h. Using a newly designed model system, the apical 3-4 mm of the roots were immersed in BHI culture medium with phenol red indicator within culture chambers. The coronal access of each specimen was inoculated every 48 h with a suspension of Streptococcus salivarius. Culture media were observed every 24 h for colour change indicating bacterial contamination. Media demonstrating colour change were plated for S. salivarius. Samples were observed for 12 weeks.

RESULTS

At 4 weeks 10% of specimens from each experimental group had evidence of leakage. At 8 weeks 20% of specimens filled with amalgam without dentine bonding agent, Super-EBA and MTA had evidence of leakage. At 12 weeks minor differences between materials were noted.

CONCLUSIONS

Under the conditions of the study, despite some variations, there were no statistically significant differences in rate of microleakage among the five groups tested at either 4, 8 or 12 weeks.

Clinical applications of mineral trioxide aggregate

An experimental material, mineral trioxide aggregate (MTA), has recently been investigated as a potential alternative restorative material to the presently used materials in endodontics. Several in vitro and in vivo studies have shown that MTA prevents microleakage, is biocompatible, and promotes regeneration of the original tissues when it is placed in contact with the dental pulp or periradicular tissues. This article describes the clinical procedures for application of MTA in capping of pulps with reversible pulpitis, apexification, repair of root perforations nonsurgically and surgically, as well as its use as a root-end filling material.

Dental materials: 1996 literature review

This critical review of the published literature on dental materials for the year 1996 has been compiled by the Dental Materials Panel of the UK. It continues the series of annual reviews started in 1973 and published in the Journal of Dentistry. Emphasis has been placed upon publications which report upon the materials science or clinical performance of the materials. The review has been divided by accepted materials classifications (fissure sealants, glass polyalkenoate cements, dentine bonding, dental amalgam, endodontic materials, casting alloys, resin-bonded bridges and ceramo-metallic restorations, ceramics, denture base resins and soft lining materials, impression materials, implants materials, orthodontic materials, biomechanics and image processing, resin composites and casting investment materials and waxes). Three hundred and thirteen articles have been reviewed.