Evaluation of biocompatibility of mineral trioxide aggregate with an improved rabbit ear chamber

Present status and future directions: Hydraulic materials for endodontic use

BACKGROUND

Hydraulic materials are used in Endodontics due to their hydration characteristics namely the formation of calcium hydroxide when mixing with water and also because of their hydraulic properties. These materials are presented in various consistencies and delivery methods. They are composed primarily of tricalcium and dicalcium silicate, and also include a radiopacifier, additives and an aqueous or a non-aqueous vehicle. Only materials whose primary reaction is with water can be classified as hydraulic.

OBJECTIVES

Review of the classification of hydraulic materials by Camilleri and the literature pertaining to specific uses of hydraulic cements in endodontics namely intra-coronal, intra-radicular and extra-radicular. Review of the literature on the material properties linked to specific uses providing the current status of these materials after which future trends and gaps in knowledge could be identified.

METHODS

The literature was reviewed using PUBMED, and for each clinical use, the in vitro properties such as physical, chemical, biological and antimicrobial characteristics and clinical data were extracted and evaluated.

RESULTS

A large number of publications were retrieved for each clinical use and these were grouped depending on the property type being investigated.

CONCLUSIONS

The hydraulic cements have made a difference in clinical outcomes. The main shortcoming is the poor testing methodologies employed which provide very limited information and also inhibits adequate clinical translation. Furthermore, the clinical protocols need to be updated to enable the materials to be employed effectively.

Reactions of human dental pulp cells to capping agents in the presence or absence of bacterial exposure

An ideal pulp-capping agent needs to have good biocompatibility and promote reparative dentinogenesis. Although the effects of capping agents on healthy pulp are known, limited data regarding their effects on bacterial contaminated pulp are available. This study aimed to evaluate the reaction of contaminated pulps to various capping agents to assist clinicians in making informed decisions. Human dental pulp (HDP) cell cultures were developed from extracted human molars. The cells were exposed to a bacterial cocktail comprising Porphyromonas gingivalis, Prevotella intermedia, and Streptococcus gordonii before being cocultured with capping agents such as mineral trioxide aggregate (MTA) Portland cement (PC), and Dycal. HDP cell proliferation was assayed by MTS colorimetric cell proliferation assay, and its differentiation was evaluated by real-time PCR for detecting alkaline phosphatase, dentin sialophosphoprotein, and osteocalcin expressions. MTA and PC had no apparent effect, whereas Dycal inhibited HDP cell proliferation. PC stimulated HDP cell differentiation, particularly when they were exposed to bacteria. MTA and Dycal inhibited differentiation, regardless of bacterial infection. In conclusion, PC was the most favorable agent, followed by MTA, and Dycal was the least favorable agent for supporting the functions of bacterial compromised pulp cells.

Systemic bone marker expression induced by grey and white mineral trioxide aggregate in normal and diabetic conditions

AIM

To investigate the relationship between diabetes mellitus and local/systemic effects of both grey and white mineral trioxide aggregate (MTA) Angelus on bone marker expression.

METHODOLOGY

Wistar rats were divided into two groups: healthy and diabetic (Alloxan induced), which were further divided into three subgroups (control, GMTA Angelus and WMTA Angelus). Polyethylene tubes filled with MTA materials or empty tubes were implanted in dorsal connective tissue. On days 7 and 30, blood samples were collected for calcium, phosphorus and ALP measurement. The animals were euthanized; implanted tubes were removed and processed for immunohistochemical analysis of osteocalcin (OCN) and osteopontin (OPN). Kruskal-Wallis followed by Dunn's multiple comparison test was performed for nonparametric data, and anova followed by Tukey's test for parametric data.

RESULTS

No difference in systemic serum calcium levels between both groups was observed. On day 7, serum phosphorus levels within the WMTA healthy group were higher than that of the diabetic group. On day 30, healthy rats exhibited lower phosphorus levels than diabetic ones. At both time points, the diabetic group was associated with more ALP activity than the healthy group. Immunohistochemical analyses of the healthy group revealed OCN- and OPN-positive cells in the presence of both MTA materials. However, under diabetic conditions, both OCN and OPN were absent.

CONCLUSION

Both MTA materials were associated with an increase in serum calcium, phosphorus and ALP, suggesting a potential systemic effect, along with triggered differentiation of OCN- and OPN-positive cells. Moreover, in diabetic conditions, an inhibitory effect on MTA-induced differentiation of OCN- and OPN-positive cells was detected.

The Effect of Mineral Trioxide Aggregate on the Periapical Tissues after Unintentional Extrusion beyond the Apical Foramen

Introduction. Single-step apexification procedures using mineral trioxide aggregate (MTA) have been reported as favorable treatment options for teeth with an open apex, posing greater benefits compared to the other available medicaments. However, controlled apical placement of MTA is a challenging procedure to perform using orthograde approach. This case series describes the outcome of the unintentional extrusion of MTA into periradicular tissues during apexification, in three separate cases. Methods. Three adult patients reported to the Department of Conservative Dentistry and Endodontics for the management of maxillary incisors with open apices. After isolation, conventional access, and cleaning and shaping procedures, one-step MTA apexification was performed. On subsequent radiographs, a considerable amount of MTA was seen to be extruded in all the three cases. Results. During follow-up examination the teeth were seen to be asymptomatic in all cases and radiographically demonstrated repair of the periapical lesion. Conclusion. The results of these cases suggest that extrusion of MTA into the periapical tissues does not cause any detrimental effect, which could be attributed to the biologic properties of MTA.

Mineral trioxide aggregate and portland cement for direct pulp capping in dog: a histopathological evaluation

Background and aims. Mineral trioxide aggregate and calcium hydroxide are considered the gold standard pulp-capping materials. Recently, Portland cement has been introduced with properties similar to those of mineral trioxide aggregate. Histopathological effects of direct pulp capping using mineral trioxide aggregate and Portland cements on dog dental pulp tissue were evaluated in the present study. Materials and methods. This histopatological study was carried out on 64 dog premolars. First, the pulp was exposed with a sterile bur. Then, the exposed pulp was capped with white or gray mineral trioxide aggregates and white or gray Portland cements in each quadrant and sealed with glass-ionomer. The specimens were evaluated under a light microscope after 6 months. Statistical analysis was carried out using Kruskal-Wallis test. Statistical significance was defined at α=5%. Results. There was no acute inflammation in any of the specimens. Chronic inflammation in white and gray mineral trioxide aggregates and white and gray Portland cements was reported to be 45.5%, 27.3%, 57.1% and 34.1%, respectively. Although the differences were not statistically significant, severe inflammation was observed mostly adjacent to white mineral trioxide aggregate. The largest extent of increased vascularization (45%) and the least increase in fibrous tissue were observed adjacent to white mineral trioxide aggregate, with no significant differences. In addition, the least calcified tissue formed adjacent to white mineral trioxide aggregate, although the difference was not significant. Conclusion. The materials used in this study were equally effective as pulp protection materials following direct pulp capping in dog teeth.

Evaluation of the biocompatibility of experimentally manufactured portland cement: An animal study

Objectives: The purpose of this study was to evaluate the biocompatibility of MTA and the experimentally manufactured portland cement (EMPC). Study design: Twenty one Sprague Dawley (SD) rats were allocated to testing of three groups. Group I and Group II included ProRoot MTA and the EMPC. The materials were mixed with distilled water and placed in polyethylene tubes. The tubes were implanted subcutaneously in the dorsal region of the animals. Group III served as control; the implanted polyethylene tubes remained empty. At 7, 14, and 28 days after the implantation, the animals were sacrificed and the implants were removed with the surrounding tissues. The specimens were prepared for histological examination to evaluate the inflammatory response. Results: No significant difference was found between tissue reactions against the tested materials (p>0.05). Also, control group showed similar results (p>0.05). Conclusions: Results suggest that the EMPC has the potential to be used in clinical conditions in which ProRoot MTA is indicated. MTA and the EMPC show comparable biocompatibility when evaluated in vivo. Although the results are supportive for the EMPC, more studies are required before the safe clinical use of the EMPC.

Key words:Mineral trioxide aggregate, portland cement, subcutanous implantation.

Comparative Osteogenesis of Radiopaque Dicalcium Silicate Cement and White-Colored Mineral Trioxide Aggregate in a Rabbit Femur Model

The radiopaque dicalcium silicate cement (RDSC) displayed a shortened setting time and good biocompatibility. This study aimed to compare the regenerative potential of RDSC and white-colored mineral trioxide aggregate (WMTA) using a rabbit femur model. The animals were sacrificed at one, three and six months to accomplish histological and biochemical analyses. The results indicated that after one month of implantation, WMTA was associated with a greyish color alteration within its mass, while RDSC presented color stability even at six months. Histological assay with Masson's Trichrome and Von Kossa stains showed the presence of newly formed bone surrounding the implanted sites in the rabbit femur. The histochemical data revealed that the RDSC group had significantly more bone regeneration than did the WMTA groups at three and six months. The conclusion drawn is that the encouraging results support the potential applications of RDSC as an improved alternative to WMTA for endodontic uses.

Long-term observation of the mineral trioxide aggregate extrusion into the periapical lesion: a case series

One-step apexification using mineral trioxide aggregate (MTA) has been reported as an alternative treatment modality with more benefits than the use of long-term calcium hydroxide for teeth with open apex. However, orthograde placement of MTA is a challenging procedure in terms of length control. This case series describes the sequence of events following apical extrusion of MTA into the periapical area during a one-step apexification procedure for maxillary central incisor with an infected immature apex. Detailed long-term observation revealed complete resolution of the periapical radiolucent lesion around the extruded MTA. These cases revealed that direct contact with MTA had no negative effects on healing of the periapical tissues. However, intentional MTA overfilling into the periapical lesion is not to be recommended.

Endodontic essay

"It has been said that Mineral Trioxide Aggregate is driving an endodontic revolution. Discuss this statement considering the biological and clinical attributes of this innovative material."

Effects of mineral trioxide aggregate on the differentiation of rat dental pulp cells

The effect of mineral trioxide aggregate (MTA) on the odontoblast-like differentiation of pulp cells was evaluated using heat-shock protein 25 (hsp25) as a marker for odontoblast differentiation. The cells were cultured with tooth-colored MTA or calcium hydroxide-containing cement (Dycal). The effects of the materials on the pulp cells were observed using a confocal laser scanning microscope. The cells were labelled immunocytochemically using polyclonal antibodies against hsp25 and actin. The mRNA expression of hsp25 and dspp in the pulp cells at 2 days were examined by quantitative reverse transcription-polymerase chain reaction (RT-PCR). Most of the cells cultured with MTA showed an intense immunolabelling for hsp25 and the mRNA expressions of hsp25 and dspp at 2 days were higher than those cultured with Dycal. These findings indicate that MTA is an effective pulp capping material and is able to induce the differentiation of odontoblast-like cells and the formation of reparative tertiary dentin with minimum apoptosis.

Effect of tricalcium aluminate on the properties of tricalcium silicate-tricalcium aluminate mixtures: setting time, mechanical strength and biocompatibility

AIM

To prepare biphasic mixtures by adding Ca(3) Al(2) O(6) into Ca(3) SiO(5) and to evaluate the effect of Ca(3) Al(2) O(6) on physical and ex vivo biological properties of the Ca(3) SiO(5) /Ca(3) Al(2) O(6) mixtures derived from mineral trioxide aggregate (MTA).

METHODOLOGY

Combinations of Ca(3) SiO(5) and Ca(3) Al(2) O(6) (0, 5%, 10% and 15%) powders were mixed with deionized water. After hydration, setting time, compressive strength, ex vivo bioactivity and biocompatibility of each mixture were investigated and compared to pure Ca(3) SiO(5) .

RESULTS

With the addition of Ca(3) Al(2) O(6) from 0% to 15%, the initial setting time and final setting time of the Ca(3) SiO(5) /Ca(3) Al(2) O(6) mixtures decreased from 110 to 43min and from 220 to 97min, respectively (P≤0.05). However, the compressive strength increased from 6.75 to 16.20MPa after one day (P≤0.05) and from 17.73 to 29.13 Mpa after 28 days. Furthermore, the mixtures with 10% Ca(3) Al(2) O(6) or less had similar bioactivity and biocompatibility when compared to the pure Ca(3) SiO(5).

CONCLUSIONS

The addition of Ca(3) Al(2) O(6) into Ca(3) SiO(5) accelerated the hydration process, reduced the setting time and improved the compressive strength. Furthermore, these mixtures were bioactive and biocompatible and had a stimulatory effect on the L929 cell growth when the content of Ca(3) Al(2) O(6) was below 10%. Therefore, the mixtures with 10% Ca(3) Al(2) O(6) produced the best compromise between hydration and ex vivo biological properties.

Mineral trioxide aggregate in paediatric dentistry

OBJECTIVE

The aim of this study was to present a review of the reported literature on: (i) the physical and chemical properties; and (ii) clinical applications of mineral trioxide aggregate (MTA) in the practice of paediatric dentistry.

METHOD

Electronic literature search of scientific papers from January 1993 to June 2008 was carried out on the MEDLINE, Embase, Entrez Pubmed, and Scopus databases using specific key words. The search yielded 448 papers, out of which 100 were identified as conforming to the applied criteria. These papers formed the basis of the review and the clinical scenarios presented which demonstrate the application of MTA in the practice of paediatric dentistry.

CONCLUSION

Paediatric dentists have successfully employed MTA in a variety of endodontic/restorative applications since the late 1990s. Clinical impressions have generally been favourable and support the findings of laboratory and animal-based investigations. Very few clinical studies have been reported so far in humans, and although these have been positive, the body of research is currently insufficient to enable a meaningful systematic review and meta-analysis.

Mineral trioxide aggregate: a review of the constituents and biological properties of the material

This paper reviews the literature on the constituents and biocompatibility of mineral trioxide aggregate (MTA). A Medline search was conducted. The first publication on the material was in November 1993. The Medline search identified 206 papers published from November 1993 to August 2005. Specific searches on constituents and biocompatibility of mineral trioxide aggregate, however, yielded few publications. Initially all abstracts were read to identify which fitted one of the two categories required for this review, constituents or biocompatibility. Based on this assessment and a review of the papers, 13 were included in the constituent category and 53 in the biocompatibility category. Relatively few articles addressed the constituents of MTA, whilst cytological evaluation was the most widely used biocompatibility test.

Effects of Gray and White Mineral Trioxide Aggregate on the Proliferation of Oral Keratinocytes and Cementoblasts

Mineral trioxide aggregate (MTA) is used as a repair material and may directly contact cells from different cell lineages. The purpose of this study was to assess cell proliferation of immortalized Murine cementoblasts (OCCM.30) and immortalized keratinocytes (OKF6/TERT1) on gray MTA (GMTA) and white MTA (WMTA) with the DNA intercalating dye Hoechst 33342. Cells were grown for 72 hours on GMTA or WMTA that had been cured for 24 hours or 12 days. WMTA significantly (p < 0.001) increased the proliferation of OCCM.30 cementoblasts compared to control and OKF6/TERT1 keratinocytes. Both cell types grew significantly (p < 0.001) better on the surface of WMTA compared to GMTA. In addition, both cell types showed significantly (p < 0.005) higher proliferation when grown on 12-day-cured GMTA compared to 24-hour-cured GMTA.

Evaluation of genetic damage in human peripheral lymphocytes exposed to mineral trioxide aggregate and Portland cements

summary Mineral trioxide aggregate (MTA) and Portland cement are being used in dentistry as root-end-filling material for periapical surgery and for the sealing of communications between the root canal system and the surrounding tissues. However, genotoxicity tests for complete risk assessment of these compounds have not been conducted up to now. In the present study, the genotoxic effects of MTA and Portland cements were evaluated in peripheral lymphocytes from 10 volunteers by the alkaline single cell gel (comet) assay. The results pointed out that the single cell gel (comet) assay failed to detect the presence of DNA damage after a treatment of peripheral lymphocytes by MTA and Portland cements for concentrations up to 1000 mug mL(-1). In summary, our results indicate that exposure to MTA or Portland cements may not be a factor that increases the level of DNA lesions in human peripheral lymphocytes as detected by single cell gel (comet) assay.