Mineral trioxide aggregate and other bioactive endodontic cements: an updated overview - part I: vital pulp therapy.

Mineral trioxide aggregate (MTA) is a bioactive endodontic cement (BEC) mainly comprised of calcium and silicate elements. The cement was introduced by Torabinejad in the 1990s and has been approved by the Food and Drug Administration to be used in the United States in 1997. A number of new BECs have also been introduced to the market, including BioAggregate, Biodentine, BioRoot RCS, calcium-enriched mixture cement, Endo-CPM, Endocem, EndoSequence, EndoBinder, EndoSeal MTA, iRoot, MicroMega MTA, MTA Bio, MTA Fillapex, MTA Plus, NeoMTA Plus, OrthoMTA, Quick-Set, RetroMTA, Tech Biosealer and TheraCal LC. It has been claimed that these materials have properties similar to those of MTA without its drawbacks. In this article, the chemical composition and the application of MTA and other BECs for vital pulp therapy (VPT), including indirect pulp cap, direct pulp cap, partial pulpotomy, pulpotomy and partial pulpectomy, have been reviewed and compared. Based on selected keywords, all papers regarding chemical composition and VPT applications of BECs had been reviewed. Most of the materials had calcium and silicate in their composition. Instead of referring to the cements based on their chemical compositions, we suggest the term 'bioactive endodontic cements (BECs)', which seems more appropriate for these materials because, in spite of differences in their chemical compositions, bioactivity is a common property for all of them. Numerous articles were found regarding use of BECs as VPT agents for indirect and direct pulp capping, partial pulpotomy and cervical pulpotomy. Most of these investigations used MTA for VPT. In most studies, newly introduced materials have been compared to MTA. Some of the BECs have shown promising results; however, the number of their studies compared to investigations on MTA is limited. Most studies had several methodological shortcomings. Future investigations with rigorous methods and materials are needed.

Mineral trioxide aggregate and other bioactive endodontic cements: an updated overview - part II: other clinical applications and complications.

Mineral trioxide aggregate (MTA) is a dental material used extensively for vital pulp therapies (VPT), protecting scaffolds during regenerative endodontic procedures, apical barriers in teeth with necrotic pulps and open apices, perforation repairs as well as root canal filling and root-end filling during surgical endodontics. A number of bioactive endodontic cements (BECs) have recently been introduced to the market. Most of these materials have calcium and silicate in their compositions; however, bioactivity is a common property of these cements. These materials include the following: BioAggregate, Biodentine, BioRoot RCS, calcium-enriched mixture cement, Endo-CPM, Endocem, EndoSequence, EndoBinder, EndoSeal MTA, iRoot, MicroMega MTA, MTA Bio, MTA Fillapex, MTA Plus, Neo MTA Plus, Ortho MTA, Quick-Set, Retro MTA, Tech Biosealer, and TheraCal LC. It has been claimed that these materials have properties similar to those of MTA but without the drawbacks. In Part I of this review, the available information on the chemical composition of the materials listed above was reviewed and their applications for VPT was discussed. In this article, the clinical applications of MTA and other BECs will be reviewed for apexification, regenerative endodontics, perforation repair, root canal filling, root-end filling, restorative procedures, periodontal defects and treatment of vertical and horizontal root fractures. In addition, the literature regarding the possible drawbacks of these materials following their clinical applications is reviewed. These drawbacks include their discolouration potential, systemic effects and retreatability following use as a root filling material. Based on selected keywords, all publications were searched regarding the use of MTA as well as BECs for the relevant clinical applications. Numerous publications were found regarding the use of BECs for various endodontic applications. The majority of these investigations compared BECs with MTA. Despite promising results for some materials, the number of publications using BECs for various clinical applications was limited. Furthermore, most studies had several methodological shortcomings and low levels of evidence.

Effect of MTA particle size on periapical healing.

AIM: To examine the effect of reduction in MTA particle size on dento-alveolar and osseous healing in dogs. METHODOLOGY: Root canals of 24 mandibular premolars in four 2-year-old beagles were prepared and filled with gutta-percha and sealer. Two to four weeks later, during periapical surgery, the root-end cavity preparations in these teeth were filled with either grey ProRoot MTA or modified (reduced particle sizes with faster setting time) MTA. The animals were sacrificed 4 months later. Degrees of inflammation, type of inflammatory cells, fibrous connective tissue adjacent to the root-end filling materials, cementum formation over the resected roots and root-end filling materials and bone healing were examined. Data were analysed using the McNemar test. RESULTS: No significant differences in healing of periapical tissues were found when comparing ProRoot MTA to a modified MTA containing reduced particle sizes. CONCLUSION: Reducing the particle sizes of MTA did not impact its biological properties.

Prophylactic treatment of dens evaginatus using mineral trioxide aggregate.

Two case reports with dens evaginatus are presented. Each patient had one tooth affected. There was a prominent tubercle on the occlusal surface of the mandibular second premolar. Under local anesthesia and rubber dam isolation a partial pulpotomy was conducted and mineral trioxide aggregate was placed. After 6 months the teeth were removed as part of planned orthodontic treatment. Histological examination of these teeth showed an apparent continuous dentin bridge formation in both teeth, and the pulps were free of inflammation. These cases show that mineral trioxide aggregate can be used as an alternative to existing materials in the proplylactic treatment of dens evaginatus.

Effect of systemic doxycycline on alveolar bone loss after periradicular surgery.

Studies in the periodontic literature have shown an average of 0.5 mm to > 1.0 mm of bone loss after full thickness flap reflection. Similar literature has revealed that the tetracycline family of antibiotics can prevent bone loss. The purpose of this study was to observe the effect of systemic Doxycycline on crestal alveolar bone loss after periradicular surgery in beagle dogs. Five beagle dogs were used in two phases of this study. In the first phase (control sides), after reflecting full thickness flaps in one mandibular quadrant, notches were placed in the enamel of the third and fourth premolar teeth using a one-quarter round bur. Using magnification, measurements were taken from the reference notches to the height of the alveolar crest. After 8 wk, flaps were reflected in the same quadrant and measurements retaken, and the amount of bone loss was then measured. In the second phase (experimental sides), the same procedure was performed on the contralateral mandibular quadrant, but the dogs were placed on 4.4 mg/kg/day of Doxycycline for 10 days after reflections of full thickness flaps. After another 8 wk, the area was reflapped and measured. There was significantly (p < 0.01) less bone loss on the Doxycycline-treated side.

Treatment of teeth with open apices using mineral trioxide aggregate.

Injuries to the dentition may ultimately result in the interruption of root development. If the pulp remains vital following trauma, this state should be maintained and root-end closure should be induced by apexogenesis. When the pulp is necrotic, the placement of an apical barrier can be utilized as an alternative to establish an environment that facilitates the closure of the apical opening. This article demonstrates the use of mineral trioxide aggregate as an apical barrier material for root-end closure in the permanent teeth of three patients.

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.

A comparative study of root-end induction using osteogenic protein-1, calcium hydroxide, and mineral trioxide aggregate in dogs.

Calcium hydroxide has been the material of choice for apexification. The purpose of this study was to compare the efficacy of osteogenic protein-1 and mineral trioxide aggregate with that of calcium hydroxide in the formation of hard tissue in immature roots of dogs. Sixty-four roots of premolars were used. After induction of periradicular lesions, the canals were debrided and filled with calcium hydroxide for 1 wk. After the removal of calcium hydroxide, the root canals received one of the treatment materials in a balanced design. The animals were euthanized 12 wk later. The degree of hard tissue formation and amount of inflammation were evaluated histomorphically. Data were statistically evaluated using ANOVA, chi 2, and Kruskal-Wallis. Mineral trioxide aggregate produced apical hard tissue formation with significantly greater consistency. The difference in the amount of hard tissue produced among the three test materials was not statistically significant. Furthermore, the degree of inflammation was not significantly different between the various test groups.

Osteoblast biocompatibility of mineral trioxide aggregate.

This study investigated the biocompatibility of variants of mineral trioxide aggregate (MTA), by culturing human MG63 osteosarcoma cells in the presence of materials, observing cytomorphology and cell growth, and then assaying cytokine expression from the cells. Reference materials were employed. Cell growth was quantified by preparing samples (n = 6) at 2, 4 and 7 days, for viewing by scanning electron microscopy and then scoring the amount of material that was covered by healthy cells. Subsequently, samples of culture media were tested using ELISA assays for expression of Interleukin (IL)-1alpha, IL-6, IL-8, IL-11 and macrophage colony stimulating factor (M-CSF). These assays were compared with controls where no material was present, and where media and fetal calf serum had not been exposed to cells. Results showed good cell growth on MTA. Expression of IL-6 from cells was only evident in the presence of MTA and Interpore 200. Interleukin-8 was expressed in high concentrations only in the presence of MTA. There was no evidence of expression of IL-1alpha or IL-11 with any material. Production of M-CSF was high for all materials. It appears that the variants of MTA are biocompatible and suitable for use in clinical trials.

Effects of resorbable membrane placement and human osteogenic protein-1 on hard tissue healing after periradicular surgery in cats.

Periradicular surgeries were performed on the maxillary cuspid teeth of twelve cats. Before reapproximation of the surgical flaps, eight of the osteotomies were covered with a resorbable membrane and eight were filled with human osteogenic protein-1 (hOP-1) on a collagen carrier. The remaining eight sites received no further treatment and served as controls. The animals were euthanized after 12 wk, and the specimens were examined histomorphometrically for the presence or absence of osseous regeneration, inflammation, and cementum formation on the root ends. The results showed that the sites treated with the membrane exhibited significantly more inflammation adjacent to the resected root ends (p < 0.05), and that the use of the membrane had no statistically significant effect on osseous healing or new cementum formation. The use of hOP-1 was associated with a significant decrease in the thickness of new cementum formed on the resected root ends (p < 0.05), but had no statistically significant effect on osseous healing or degree of inflammation. Based on these results, it seems that neither the use of hOP-1 nor resorbable membranes have a positive effect on periradicular tissue healing in endodontic surgery.

Cellular response to Mineral Trioxide Aggregate.

This investigation studied the cytomorphology of osteoblasts in the presence of Mineral Trioxide Aggregate (MTA) and examined cytokine production. MTA and Intermediate Restorative Material (IRM) were prepared and placed in separate Petri dishes. Osteoblasts (cell-line MG-63), grown to confluence in Hams F12/Dulbecco's modified Eagle's medium, were seeded into the dishes, which were incubated for 1 to 7 days. The specimens were viewed by scanning electron microscopy. For cytokine evaluation, cells were grown either alone or in other dishes containing the test materials for 1 to 144 h. Media were removed for ELISA analysis of interleukin (IL)-1 alpha, IL-1 beta, IL-6, and macrophage colony-stimulating factor. Scanning electron microscopy revealed healthy cells in contact with MTA at 1 and 3 days; in contrast, cells in the presence of IRM appeared rounded. The ELISA assays revealed raised levels of all ILs at all periods when cells were grown in the presence of MTA; in contrast, cells grown alone or with IRM produced undetectable amounts. The macrophage colony-stimulating factor was produced by cells irrespective of the group. It seems that MTA offers a biologically active substrate for bone cells and stimulates IL production.

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.

Diagnosis and treatment of extracanal invasive resorption.

Extracanal invasive resorption is not a well-defined phenomenon. This article describes its clinical, radiographic, and histological characteristics. Treatment of affected teeth based on the location of the resorptive defect is also described.

Development of periradicular lesions in immunosuppressed rats.

PROBLEM: The role of bacteria has been well established in pulpal and periapical diseases, but the contribution of the host defenses is less clear. OBJECTIVES: The purpose of this study was to compare periradicular lesion development in immunosuppressed rats with that in normal rats. STUDY DESIGN: Fifteen rats were given weekly injections of Cytoxan (Bristol Laboratories) to suppress their immune systems. The pulps of mandibular first molars of these animals and another 15 rats that had received no medications were exposed and left open to their oral flora. The rats were killed at 2, 4, and 6 weeks. Radiographic analysis was performed by means of a computer linked to a digitizing board and stylus. In addition, specimens were decalcified, sectioned, stained, and examined under a microscope with a grid to quantify relative percentages of surface areas of bone, root, periodontal ligament, marrow spaces, soft tissue, and inflammatory infiltrate. RESULTS: Statistical analysis showed a significantly greater radiographic bone loss in the immunosuppressed group only at 4 weeks. No significant histologic differences were found between the two groups. CONCLUSION: Our results suggest that reduction of circulating leukocytes may not significantly affect the development of periradicular pathosis in rats.

Mineral trioxide aggregate stimulates a biological response in human osteoblasts.

We report a novel material that appears to stimulate cytokine production in human osteoblasts and allow good adherence of the cells to the material. We have examined cultured osteoblasts (MG-63) in the presence of mineral trioxide aggregate (MTA) as set in moist conditions; secondly, we examined the behavior of these MG-63 cells with respect to cytokine and osteocalcin production and alkaline phosphatase activity. Standard ELISA assays were used for assessment of interleukin (IL)-1 alpha, IL-1 beta, IL-6, macrophage colony stimulating factor (M-CSF), and osteocalcin. Furthermore the levels of alkaline phosphatase were measured to establish the level of differentiation of the cells. Cells without MTA served as controls. Cells also were grown in the presence of polymethylmethacrylate (PMA), the commonly used orthopedic cement. In all dishes cells were seen adhering to the base and MTA at 6 h and had increased to confluence at 144 h. IL-1 alpha (175.1 +/- 32.6 pg/mL), IL-1 beta (154.0 +/- 26.7 pg/mL), and IL-6 (214.7 +/- 21.8 pg/mL) were raised when the cells were grown in the presence of MTA at 144 h, with raised values at all time intervals. M-CSF appeared to be unaffected although the overall value was high (7,045.0 +/- 89.5 pg/mL). In contrast, cells grown in the absence of MTA produced negligible amounts of these cytokines (< pg/mL) as did those cells grown in the presence of PMA. Osteocalcin production increased when cells were grown on MTA from 3.8 +/- 0.87 ng/mL to 19.7 +/- 2.8 ng/mL. No osteocalcin could be detected with PMA. Cells in contact with MTA also appeared to have levels of alkaline phosphatase similar to those reported elsewhere (4.3 +/- 0.21 mumol/mg protein/min). No cells could be found attached to PMA and so no alkaline phosphatase activity could be measured.

Healing potential of osteotomies of the nasal sinus in the dog.

UNLABELLED: Maxillary sinus osteotomy is indicated for transantral surgical approaches to palatal roots of maxillary teeth. There are no reports on the healing potential of such defects. OBJECTIVES: To determine by histologic examination, the reparative process of the nasal cavity of dogs after small and large perforations with and without a resorbable collagen membrane. STUDY DESIGN: Five mm and 6 x 12 mm diameter osteotomies were created through the maxilla of 12 beagle dogs. Resorbable collagen membranes were placed over defects on six dogs. After 5 months, sections of the defects were histologically evaluated. RESULTS: Examination revealed partial osseous healing with presence of central areas of fibrous scar tissue in all samples. Defects covered with the resorbable collagen membranes showed no improvement in osseous regeneration. CONCLUSION: Based on our results, defects (regardless of their size) tend to repair with limited bony covering and fibrous scar. Furthermore, resorbable collagen membranes do not improve osseous repair.

Histologic assessment of mineral trioxide aggregate as a root-end filling in monkeys.

Mineral Trioxide Aggregate (MTA) has been shown in a number of experiments to be a potential root-end filling material. The purpose of this study was to examine the periradicular tissue response of monkeys to MTA and amalgam as root-end fillings. The pulps were removed from all the maxillary incisors of three monkeys. The root canals were prepared and filled with laterally condensed guttapercha and sealer, and the access cavities were restored with amalgam. Buccal mucoperiosteal flaps were raised, and root-end resections were performed before root-end cavity preparation with burs. The root-end cavities in half of the teeth were filled with MTA, while amalgam was placed in the other cavities. After 5 months the periradicular tissue response was evaluated histologically. The results showed no periradicular inflammation adjacent to five of six root ends filled with MTA; also five of six root ends filled with MTA had a complete layer of cementum over the filling. In contrast, all root ends filled with amalgam showed periradicular inflammation, and cementum had not formed over the root-end filling material, although it was present over the cut root end. Based on these results and previous investigations, MTA is recommended as a root-end filling material in man.

Using mineral trioxide aggregate as a pulp-capping material.

This study examined the dental pulp responses in monkeys to mineral trioxide aggregate, or MTA, and a calcium hydroxide preparation when used as pulp-capping materials. After the pulps of 12 mandibular incisors were exposed with a No. 1 round bur, they were capped with either MTA or the calcium hydroxide preparation. After five months, the authors noted no pulpal inflammation in five of six samples capped with MTA, and all six pulps in this group had a complete dentin bridge. In contrast, all of the pulps capped with the calcium hydroxide preparation showed pulpal inflammation, and bridge formation occurred in only two samples. Based on these results, it appears that MTA has the potential to be used as a pulp-capping material during vital pulp therapy.

Wound healing after mucoperiosteal surgery in the cat.

The purpose of this study was to examine possible tissue-dependent differences in rate of healing after mucogingival flap surgery. After intrasulcular incision and a vertical-releasing incision distal to the maxillary and mandibular cuspids, buccal, full-thickness mucogingival flaps were raised in four quadrants of 10 adult cats. The triangular flaps were left open for 30 min and then repositioned and sutured. Tissue reactions were studied histologically after 1, 3, 7, 14, and 28 days of healing. Although new collagen occasionally was observed in the wound space in the free gingiva at 3 days, collagenous union between the cut dentogingival fibers and the flap seemed well established at 7 days. Flap reattachment to the denuded cortical bone was seen at 14 days in the region of the attached gingiva. In the region of the alveolar mucosa, however, residual coagulum and inflammatory reaction was present as late as at 28 days in several specimens. These observations indicate a marked difference in rate of healing among the different interfaces involved. These variations seem to be related to variations in size of the resulting wound space when a full-thickness mucoperiosteal flap is readapted over cervical root surfaces, alveolar bone crest, and denuded cortical bone, respectively.

Measurement of blood flow with radiolabeled microspheres in reflected mucogingival flaps in cats.

To quantify and compare blood flow in maxillary mucogingival flaps, a total of 16 cats (32 mucogingival specimens) were divided into two groups. In group I the blood flow in attached or reflected maxillary tissues were measured. In Group II the effects on blood flow were measured in reflected tissues after the injection of the following solutions: (1) saline solution; (2) 2% lidocaine plain; (3) 2% lidocaine with 1:50,000 epinephrine; (4) no injection. After an injection of 153 Gadolinium microspheres into the left ventricle of the heart, the tissues were harvested and placed in a gamma counter. Group I had a mean blood flow value of 34.4 ml/min/100 gm of tissue for the unreflected samples and 152.3 ml/min/100 gm of reflected tissue. The levels of blood flow in tissue samples in group II results were: no injection (control), 41.2 ml/min/100 gm; saline solution, 46.8 ml/min/110 gm; 2% lidocaine with 1:50,000 epinephrine, 60.6 ml/min/100 gm; and 2% lidocaine plain, 90.2 ml/min/100 gm. On the basis of these results it appears that reflection of gingival tissue and injection of 2% lidocaine plain induces increased blood flow 90 minutes postoperatively.