Shear bond strength of conventional glass ionomer cements bound to mineral trioxide aggregate

Comparative Evaluation of the Mechanical and Physical Properties of Mineral Trioxide Aggregate vs. Bacterial Cellulose Nanocrystal-Reinforced Mineral Trioxide Aggregate: An In Vitro Study

AIM

This study aims to compare and assess the compression strength, microhardness, and surface texture of two sets of materials: mineral trioxide aggregate (MTA) PlusTM and bacterial cellulose nanocrystal (BCNC)-reinforced MTA PlusTM.

MATERIALS AND METHODS

According to the ASTM E384 standard, the cylindrical molds made of plexiglass with an internal diameter of 6 mm and a height of 4 mm were fabricated using computer numerical control laser cutting. A total of 20 samples (n=10) in each group were considered in this experimental study: Group I (control group) MTA PlusTM (Prevest DenPro Limited, India) and Group II (experimental group) BCNC (Vedayukt India Private Limited, India)-reinforced MTA PlusTM. After preparation, the molds were incubated at 37°C in a fully saturated condition for about 24 hours, and then the compression strength, microhardness, and scanning electron microscopy analyses were performed at different magnifications. The obtained data were then statistically analyzed.

RESULTS

Quantitative analysis revealed that there is a statistically significant difference between MTA PlusTM and BCNC-reinforced MTA PlusTM  (p<0.002). The Wilcoxon signed-rank test and Mann-Whitney U-test revealed that BCNC-reinforced MTA PlusTM  showed significantly higher compression strength (33.80±3.83 MPa, p=0.00) and surface microhardness (642.85±24.00 μm, p=0.00) than the control group.

CONCLUSION

Based on our findings, it was concluded that there is a statistically significant difference between both study groups. Thus, incorporating BCNC into the MTA PlusTM  significantly increased the compression strength and surface microhardness of the MTA PlusTM cement.

CLINICAL SIGNIFICANCE

Numerous dental applications have been investigated for bacterial cellulose. Many benefits of bacterial cellulose are available, which include its effects on moldability, low cost, high water retention capacity, biocompatibility, and biodegradability. Furthermore, the addition of BCNC to MTA PlusTM  accelerates the material's hardening process and decreases its setting time, which in turn shortens clinical chairside procedural timing and thereby improves patient satisfaction.

Comparative Evaluation of Shear Bond Strength of Resin-modified Glass Ionomer Cement with ProRoot MTA and MTA Angelus

AIM

The aim of the present study was to evaluate the shear bond strength of resin-modified glass ionomer cement with two different types of mineral trioxide aggregate at different time intervals.

MATERIALS AND METHODS

A total of 80 cylindrical blocks were prepared using a self-cure acrylic resin with a central cavity of 4 mm internal diameter and 2 mm height. The prepared samples were randomly divided into two groups (n = 40 each) according to the type of MTA cements used (ProRoot MTA and MTA Angelus). Two groups were further sub-divided into four sub-groups of 10 samples each according to the different time intervals. ProRoot MTA and MTA Angelus were placed in the prepared cavity and a wet cotton pellet was placed over the filled cavity. A hollow plastic tube was placed over the MTA surface and resin-modified glass ionomer cement (RMGIC) was placed into the hollow plastic tube and light-cured (Spectrum 800, Dentsply Caulk Milford, DE, USA) according to the time intervals decided. After light curing the plastic tubes were removed carefully and the specimens were stored at 37°C and 100% humidity for 24 hours to encourage setting of MTA. The specimens were mounted in a universal testing machine (ADMET) and a crosshead speed of 0.5 mm/min was applied to each specimen by using a knife-edge blade until the bond between the MTA and RMGIC failed. The data were statistically analyzed using ANOVA, post hoc Tukey's t-test and Fisher's t-test and p-value ≤ 0.5 was considered significant.

RESULTS

For both ProRoot MTA and MTA Angelus there was no statistically significant difference between 45 minutes and 24 hours (p-value ≥ 0.8). For ProRoot MTA, shear bond strength value at 10 minutes were significantly lower than 45 minutes and 24 hours group. However, for MTA Angelus, shear bond strength value at 10 minute was not significantly different from 45 minutes group (p-value ≥ 0.3). For both ProRoot MTA and MTA Angelus shear bond strength value at 0 minute were the least and were significantly lower than 10 minutes, 45 minutes, and 24 hours, respectively (p-value ≥ 0.000).

CONCLUSION

Resin-modified glass ionomer cement can be layered over MTA Angelus after it is allowed to set for 10 minutes. However, ProRoot MTA should be allowed to set for at least 45 minutes before the placement of RMGIC to achieve better shear bond strength.

CLINICAL SIGNIFICANCE

Due to the variety of types of mineral trioxide aggregate cements available in dentistry, it is justifiable to emphasize on different time intervals as it may affect the shear bond strength of restorative cements. Such information is pivotal for the clinicians while using mineral aggregate-based cements that receive forces from the condensation of restorative materials or occlusion, as the compressive strength may be affected due to different time intervals. How to cite this article: Tyagi N, Chaman C, Anand S, et al. Comparative Evaluation of Shear Bond Strength of Resin-modified Glass Ionomer Cement with ProRoot MTA and MTA Angelus. J Contemp Dent Pract 2024;25(1):35-40.

Does adding accelerators to Mineral Trioxide Aggregate affect the shear bond strength?

Amaç: Bu çalışmada, farklı hızlandırıcı ilave edilen Mineral Trioksit Agregat’ın (MTA) kompozite farklı sertleşme sürelerinde makaslama bağlanma dayanımının (MBD) değerlendirilmesi amaçlanmıştır. Gereç ve Yöntemler: Merkezi boşluklara sahip 120 adet akrilik blok 4 ana gruba ayrıldı. 1. grup (kontrol); sadece MTA, 2, 3 ve 4. grup ise sırasıyla %10 kalsiyum klorür (CaCl2), %23,1 kalsiyum laktat glokonat (CLG) ve %15 disodyum hidrojen fosfat (Na2HPO4) ile karıştırılmış MTA içermektedir. Her grup 2 saat 45 dakika , 24 saat ve 96 saat sertleşme süresine göre 3 alt gruba ayrıldı. Bekleme süreleri tamamlandıktan sonra adeziv sistem (Clearfil SE Bond, Kuraray) ve kompozit rezin (Clearfil Majesty, Kuraray) işlemleri tamamlanan örneklere evrensel test cihazında MBD testi uygulandı. Elde edilen verilerinin karşılaştırmasında, tek yönlü varyans analizi (ANOVA) ve Tukey HSD testleri kullanıldı. Bulgular: Hızlandırıcısız MTA en yüksek ortalama MBD değeri sergiledi. Hızlandırıcısız MTA, hızlandırıcı olarak CLG ve Na2HPO4 eklenen MTA ile kıyaslandığında aralarındaki fark anlamlı bulundu (p&lt;0.0001). Başlangıç sertleşme süresinde alt gruplar arasında istatistiksel olarak anlamlı farklılık gözlenmedi (p&gt;0,05), diğer sertleşme sürelerinde fark anlamlı bulundu (p&lt;0,05). MTA’ya hızlandırıcı olarak CLG ve Na2HPO4 ilavesinin tüm sürelerde MBD değerlerini azalttığı, CaCl2 ilavesinin ise 96 saatin ardından MBD değerini anlamlı olarak yükselttiği gözlendi. Sonuç: MTA içerisine hızlandırıcı eklemek MBD değerini düşürmektedir. Ancak MTA’ya hızlandırıcı olarak %10 CaCl2 eklemek 96 saatin ardından yapılacak restoratif işlemlerde pozitif bağlantı sonuçları ortaya çıkarabilir.

Shear bond strength of resin-modified glass ionomer cement bound to mineral trioxide aggregate after various disinfection protocols

This study compared the effects of 3 different cavity disinfection protocols (CDP) on the shear bond strength (SBS) of resin-modified glass ionomer cement (RM-GIC) to mineral trioxide aggregate (MTA). One hundred eighty standard holes were prepared and filled with MTA. They then divided into 3 main groups based on the chosen time intervals (15 min, 24 h, and 72 h). Main groups were divided into 3 subgroups based on the CDP [chlorhexidine gluconate (CHX), ozone, laser, and control]. RM-GIC was applied on MTA after CDP for all groups. A universal testing device was then used for test and the data was statistically analysed. CHX showed significantly lower SBS values except ozone and laser than the control (p < 0.05). There were no statistically significant differences among the time intervals. As a result, CHX decreased the bond strength between the MTA and RM-GIC while ozone and laser had no negative effect.

Bond Strength of Adhesive Systems to Calcium Silicate-Based Materials: A Systematic Review and Meta-Analysis of In Vitro Studies

Since the adhesion of resin composites to calcium silicate-based cement is considered challenging. Therefore, the best adhesion strategy should be indicated. This review aimed to assess the effect of different adhesive systems on the bond strength of resin composite to calcium silicate-based cement through a systematic review and meta-analysis. The subsequent PICOS framework used was: population, calcium silicate-based cement; intervention, use of self-etch adhesive systems; control, use of total-etch adhesive systems; outcome, bond strength; study design, in vitro studies. The literature search was conducted independently by two reviewers up to 18 February 2021. Electronic databases (PubMed, ISI Web of Science, SciELO, Scopus, and Embase) were searched for applicable articles. In vitro manuscripts studying the effect of adhesive systems on the bond strength of calcium silicate-based cement were considered. The meta-analyses were performed using Review Manager Software version 5.3.5 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark). Bond strength comparisons were made considering the type of calcium silicate-based cement (Mineral Trioxide Aggregate (MTA), Biodentine™, or TheraCal LC®). A p-value < 0.05 was considered statistically significant. A total of 7321 studies were retrieved in databases searched. After full-text evaluation, 37 eligible papers were assessed for qualitative analysis, leaving a total of 22 papers for the quantitative analysis. According to the meta-analysis, the bond strength values of resin composite materials to MTA and TheraCal LC® cement were favored when a total-etch adhesive system was used (p ≤ 0.02). On the other hand, the meta-analysis of the bond strength of resin-based materials to Biodentine™ calcium silicate-based cement was similar between both approaches (p = 0.12). The in vitro evidence suggests that the bond strength of resin-based materials to both MTA and TheraCal LC® cement was preferred by using the total-etch adhesive strategy. However, when bonding to Biodentine™, the use of self-etch or total-etch strategies displayed promising results. Given the lack of evidence related to the chemical interaction of self-etch adhesive materials with the bioceramics, if self-etch adhesives are used for bonding resin-based restorations to calcium silicate-based cement, a pretreatment with phosphoric acid could be recommended.

Comparative Study between Revitalization of Necrotic Immature Permanent Anterior Teeth with and without Platelet Rich Fibrin: A Randomized Controlled Trial

OBJECTIVES

This study was conducted to evaluate the effect of platelet rich fibrin (PRF) during revitalization of necrotic immature permanent anterior teeth after 6 months and 1 year follow up period. The following treatment protocols; Group A: revitalization using blood clot scaffold only, and Group B: revitalization using blood clot and PRF.

STUDY DESIGN

twenty-two patients (7-12 years old) suffering from immature necrotic permanent maxillary central incisors were randomly selected and randomly allocated into 2 groups. Clinical examinations were performed to detect any pain or swelling during the follow up period. Standardized radiographs were digitally evaluated for changes in root length, periapical radiolucency size, presence of apical or cervical calcific bridges.

RESULTS

After a follow-up period of 12 months, most of the cases showed radiographic evidence of periapical healing and showed calcific bridges either cervical and/or apical. No significant differences were shown between both groups.

CONCLUSIONS

The revitalization procedures succeeded to show continued development of roots in teeth with necrotic pulps. The use of PRF was not essential for repair but it helped during the procedures.

Combined endodontic and periodontal management of a class 3 invasive cervical resorption in a mandibular first molar

Dental radiography and cone-beam computed tomography revealed the left mandibular first molar in a 68-year-old female patient with Heithersay Class 3 invasive cervical resorption (ICR). The inhibition of ICR progression and environmental improvement in and around the affected tooth through combined endodontic and periodontal treatments led to a favorable clinical outcome.

Comparison of the Shear Bond Strength of Silorane-Based Composite Resin and Methacrylate Based Composite Resin to MTA

Background. Mineral trioxide aggregate (MTA) is a material that has recently gained popularity in the application of the vital pulp therapy. Along with the increasing use of MTA to this end, the permanent restoration material to be placed on MTA has become a significant issue. The aim of this in vitro study was to investigate the bond strength of the novel low-shrinkage silorane-based composite resin (SBC) to MTA.

Methods. Twenty acrylic blocks filled with MTA were prepared for this study. SBC was the test group and methacrylate-based composite resin (MBC) was used as the control group. Shear bond strength test was performed to determine the bond strength. The surfaces of broken samples were evaluated under a stereomicroscope and grouped as adhesive, cohesive and mixed. Data were examined by statistical analysis.

Results. Statistical analysis revealed that SBC exhibited higher shear bond strength than the control group. It was observed that most of the failures in the test group were of cohesive type within MTA.

Conclusion. Based on the results, SBC showed higher shear bond strength than the control group; however, clinical follow-up is needed to evaluate the clinical success.

Rheological Characterization as an Alternative Method to Indentation for Determining the Setting Time of Restorative and Endodontic Cements

This study explored an alternative approach using rheology to assess setting time. The following cements were tested: ProRoot^® MTA (Dentsply, Tulsa, OK, USA), Biodentine^® (Septodont, Saint Maur des Fosses, France), Fuji VII^®, FujiVII^® EP, and Fuji IX^® (from GC Corporation, Tokyo, Japan), RealSeal SE™ Sealer (SybronEndo, Amersfoort, The Netherlands), AH 26^® and AH Plus (both from Dentsply DeTrey, Konstanz, Germany). Freshly mixed cements were placed into a strain-controlled rheometer (1 rad·s^-1 with an applied strain of 0.01%). From measurements of elastic modulus over time, the time taken to reach 90% of the plateau elastic modulus (designated as the setting time) was determined for each cement. In increasing order, the setting times were as follows: Fuji VII EP 3.3 min, Fuji VII 3.6 min, Fuji IX 3.7 min, ProRoot MTA 5.1 min, Biodentine 15.9 min, RealSeal 22.2 min, AH Plus 5933 min, and AH 26 5067 min. However, ProRoot MTA did not yield reliable results. The time to reach the 90% plateau elastic modulus correlates well with the setting time of glass ionomer cements and Biodentine. Using this approach gives much longer setting times for endodontic sealers than previously recognized.

Shear bond strength of a novel light cured calcium silicate based-cement to resin composite using different adhesive systems

The shear bond strength (SBS) of TheraCal LC to resin composite was evaluated in comparison to Mineral trioxide aggregate (ProRoot MTA) and conventional glass ionomer cement (GIC) using two adhesive systems. A hole was prepared in 90 acrylic blocks (6 mm diameter, 2 mm deep) then filled with TheraCal LC, MTA or Fuji IX (n=30/group). Each group was bonded with either an etch and rinse or 1-step self-etch adhesive. Filtek Z250 composite was bonded to each capping material. Bond strength was tested in a universal testing machine, and data were analyzed using 2-way ANOVA and Duncan's Multiple range test (p<0.05). TheraCal LC displayed the highest SBS (p<0.001). MTA bonded with the 1-step self-etch adhesive showed the lowest SBS (p<0.001), while SBS of TheraCal LC and Fuji IX did not differ between either adhesive (p>0.05). TheraCal LC is the preferred choice in pulp capping procedures when using resin composite restorations.

"Evaluation of shear bond strength of a composite resin to white mineral trioxide aggregate with three different bonding systems"-An in vitro analysis

Background

Mineral trioxide aggregate (MTA) is a biomaterial that has been investigated for endodontic applications. With the increased use of MTA in pulp capping, pulpotomy, perforation repair, apexification and obturation, the material that would be placed over MTA as a final restoration is an important matter. As composite resins are one of the most widely used final restorative materials, this study was conducted to evaluate the shear bond strength of a composite resin to white mineral trioxide aggregate (WMTA) using three different bonding systems namely the two-step etch and rinse adhesive, the self-etching primer and the All-in-one system.

Material and Methods

Forty five specimens of white MTA (Angelus) were prepared and randomly divided into three groups of 15 specimens each depending on the bonding systems used respectively. In Group A, a Two-step etch and rinse adhesive or ‘total-etch adhesive’, Adper Single Bond 2 (3M/ESPE) and Filtek Z350 (3M ESPE, St Paul, MN) were placed over WMTA. In group B, a Two-step self-etching primer system, Clearfil SE Bond (Kuraray, Medical Inc) and Filtek Z350 were used. In Group C, an All-in-one system, G Bond (GC corporation, Tokyo, Japan) and Filtek Z350 were used. The shear bond strength was measured for all the specimens. The data obtained was subjected to One way Analysis of Variance (ANOVA) and Scheffe’s post hoc test.

Results

The results suggested that the Two-step etch and rinse adhesive when used to bond a composite resin to white MTA gave better bond strength values and the All-in-one exhibited the least bond strength values.

Conclusions

The placement of composite used with a Two-step etch and rinse adhesive over WMTA as a final restoration may be appropriate.

Key words:Composite resins, dentin bonding agents, mineral trioxide aggregate, shear bond strength.

Methodologies for measuring the setting times of mineral trioxide aggregate and Portland cement products used in dentistry

Objective The current standard used to measure setting time for Mineral Trioxide Aggregate (MTA) involves indentation testing with arbitrary weights. This study compared indentation testing against rheological measurements and assessed the influences of particle size and the inclusion of bismuth oxide on the setting time of experimental MTA and Portland cement (PC).

Material and methods Two PCs (P1 and P2) of different particle sizes were produced using the same clinker. From these two PCs, two experimental MTAs (M1 and M2) were created with the addition of bismuth oxide. Particle size distributions were assessed using laser diffraction analysis. Indentation setting time tests were performed in accordance to the Gillmore needle test. Elastic modulus was assessed using a strain-controlled rheometer at 1 rad s⁻¹ and an applied strain of 0.01%.

Results P1, P2, M1 and M2 cements had median particle sizes of 6.1, 12.5, 6.5 and 13.0 μm, respectively. Using indentation testing, final setting times were ranked P1 < M1 < P2 < M2. The ranking of the final setting time corresponded with the rheological assessment of time required to reach 95% of the elastic modulus plateau.

Conclusions The time to reach 95% elastic modulus plateau of 9.3 min corresponds to a time close to the point where the material can be overlaid with another restorative material to give a final restoration. The 95% plateau value for elastic modulus may be a more useful parameter for determining how the setting reaction of PC and MTA cements progress over time.

Evaluation of shear bond strength of two resin-based composites and glass ionomer cement to pure tricalcium silicate-based cement (Biodentine®)

Objectives

Tricalcium silicate is the major constituent phase in mineral trioxide aggregate (MTA). It is thus postulated that pure tricalcium silicate can replace the Portland cement component of MTA. The aim of this study was to evaluate bond strength of methacrylate-based (MB) composites, silorane-based (SB) composites, and glass ionomer cement (GIC) to Biodentine^® and mineral trioxide aggregate (MTA).

Material and Methods

Acrylic blocks (n=90, 2 mm high, 5 mm diameter central hole) were prepared. In 45 of the samples, the holes were fully filled with Biodentine^® and in the other 45 samples, the holes were fully filled with MTA. The Biodentine^® and the MTA samples were randomly divided into 3 subgroups of 15 specimens each: Group-1: MB composite; Group-2: SB composite; and Group-3: GIC. For the shear bond strength (SBS) test, each block was secured in a universal testing machine.

Results

The highest (17.7±6.2 MPa) and the lowest (5.8±3.2 MPa) bond strength values were recorded for the MB composite-Biodentine^® and the GIC-MTA, respectively. Although the MB composite showed significantly higher bond strength to Biodentine (17.7±6.2) than it did to MTA (8.9±5.7) (p<0.001), the SB composite (SB and MTA=7.4±3.3; SB and Biodentine^®=8.0±3,6) and GIC (GIC and MTA=5.8±3.2; GIC and Biodentine=6.7±2.6) showed similar bond strength performance with MTA compared with Biodentine (p=0.73 and p=0.38, respectively).

Conclusions

The new pure tricalcium-based pulp capping, repair, and endodontic material showed higher shear bond scores compared to MTA when used with the MB composite.

Comparison of shear bond strength of resin-modified glass ionomer to conditioned and unconditioned mineral trioxide aggregate surface: An in vitro study

INTRODUCTION

The aim of this study was to compare the shear bond strength of resin modified glass ionomer cement to conditioned and unconditioned mineral trioxide aggregate surface.

MATERIALS AND METHOD

White Mineral Trioxide Aggregate (WMTA) and Resin Modified Glass Ionomer Cement (RMGIC) were used for the study. 60 WMTA specimens were prepared and stored in an incubator at 37° C and 100% humidity for 72 hrs. The specimens were then divided into two groups- half of the specimens were conditioned and remaining half were left unconditioned, subsequent to which RMGIC was placed over MTA. The specimens were then stored in an incubator for 24 hrs at 37° C and 100% humidity. The shear bond strength value of RMGIC to conditioned and unconditioned WMTA was measured and compared using unpaired 't  ' test.

RESULTS

The mean shear bond strength of value of RMGIC to conditioned and unconditioned WMTA was 6.59 MPa and 7.587 MPa respectively. Statistical analysis using unpaired t-test revealed that the difference between values of two groups was not statistically significant (P > 0.05).

CONCLUSIONS

During clinical procedures like pulp capping and furcal repair, if RMGIC is placed as a base over MTA, then conditioning should be done to increase the bond strength between RMGIC and dentin and any inadvertent contact of conditioner with MTA will not significantly affect the shear bond strength value of RMGIC to MTA.

Effect of mineral trioxide aggregate surface treatments on morphology and bond strength to composite resin

INTRODUCTION

The aim of this study was to evaluate the micromorphologic changes that accompany different surface treatments on mineral trioxide aggregate (MTA) and their effect on the bond strength to the composite resin with 4 adhesive systems.

METHODS

Three types of MTA cement, ProRoot MTA (WMTA) (Dentsply, Tulsa, OK), MTA Angelus (AMTA) (Angelus, Londrina, PR, Brazil), and Endocem MTA (EMTA) (Maruchi, Wonju, Korea), were prepared and stored for a week to encourage setting. Surface treatment was performed using phosphoric acid or self-etch primer, and an untreated MTA surface was prepared as a control. The surface changes were observed using scanning electron microscopy. MTA surfaces were bonded with 4 adhesive systems, including Scotchbond Multipurpose (3M ESPE, St Paul, MN), Single Bond 2 (3M ESPE), Clearfil SE BOND (Kuraray, Osaka, Japan), and AdheSE One F (Ivoclar Vivadent, Schaan, Liechtenstein), to evaluate the adhesive effectiveness of MTA followed by composite resin restoration. The shear bond strength of the polymerized specimens was tested.

RESULTS

For WMTA and AMTA, untreated surfaces showed an irregular crystalline plate with clusters of globular aggregate particles. For EMTA, the untreated surface presented a reticular matrix with acicular crystals. After surface treatment, superficial crystalline structures were eroded regardless of the MTA cement and adhesive system used. WMTA bonded significantly more strongly than AMTA and EMTA, regardless of the adhesive system used. In the WMTA and AMTA groups, AdheSE One F showed the highest bond strength to the composite. For EMTA, no significant differences were found across adhesive systems.

CONCLUSIONS

Acidic treatment of the MTA surface affected the micromorphology and the bond strength to the composite. Within the limitations of this study, using a 1-step self-etch adhesive system might result in a strong bond to WMTA when the composite resin restoration is required over MTA cement.

In vitro bonding effectiveness of new self-adhering flowable composite to calcium silicate-based material

The purpose of this study was to compare in vitro bonding effectiveness of Vertise Flow (VF), a new self-adhering flowable composite (FC), and Ultimate Flow (UF), a conventional FC, to BioAggregate (BA), and to investigate whether the use of self-etch or etch-andrinse adhesive improved the bond strength of VF to BA. Shear bond strengths of FC to BA were measured for this reason. Data were analyzed using Wilcoxon and Mann-Whitney U-tests (p=0.05). There were significant differences of bond strengths after 24- and 72-h (p<0.05, p<0.001). After 72-h, self-adhering FC may be used successfully with BA and no other adhesive, as an alternative to the combined use of conventional FC and self-etch adhesives. The use of etch-and-rinse adhesives with self-adhering FC may improve adhesion to BA.

The shear bond strength of resin-based composite to white mineral trioxide aggregate

BACKGROUND

It is unknown if resin-based composite can be placed on top of mineral trioxide aggregate (MTA) immediately after placement of the MTA. The authors aimed to measure the bond strength of a resin-based composite to white MTA (WMTA) with different bonding strategies at different intervals.

METHODS

The authors bonded resin-based composite to MTA with three bonding protocols (n = 45 per group) (group 1, total-etching adhesive; group 2, two-step self-etching adhesive; or group 3, one-step self-etching adhesive), immediately (subgroup A), 45 minutes (subgroup B) or 24 hours (subgroup C) after placement of the MTA. The authors measured shear bond strength by means of a universal testing machine and performed statistical analysis of the data by means of two-way and one-way analysis of variance (P < .05).

RESULTS

In all three groups, subgroup A demonstrated greater bond strengths than the other subgroups. Group/subgroup 3/A demonstrated the highest bond strength (mean [standard deviation] 49.2 [2.1] megapascals), which was significantly higher than that in all other groups (P < .05). This was followed by group/subgroup 1/A (40.2 [2.5] MPa), 2/A (38.4 [1.3] MPa) and 1/B (38.5 [1.91] MPa). The lowest bond strength was shown by group/subgroup 2/C (14.7 [1.90] MPa). There was a significant difference between the two-step and one-step self-etching adhesives at all three intervals (P < .05).

CONCLUSIONS

Within the limitations of this study, the representative one-step self-etching adhesive demonstrated the strongest bond to WMTA immediately after fabrication of MTA samples.

CLINICAL IMPLICATIONS

One-step self-etching adhesive may be used to bond resin-based composite to WMTA immediately after placement, thereby offsetting the need for a second appointment for permanent restoration.

Characterization of the mineral trioxide aggregate-resin modified glass ionomer cement interface in different setting conditions

INTRODUCTION

Mineral trioxide aggregate (MTA) has been used successfully for perforation repair, vital pulpotomies, and direct pulp capping. However, little is known about the interactions between MTA and glass ionomer cement (GIC) in final restorations. In this study, 2 null hypotheses were tested: (1) GIC placement time does not affect the MTA-GIC structural interface and hardness and (2) moisture does not affect the MTA-GIC structural interface and hardness.

METHODS

Fifty cylinders were half filled with MTA and divided into 5 groups. The other half was filled with resin-modified GIC either immediately after MTA placement or after 1 or 7 days of temporization in the presence or absence of a wet cotton pellet. The specimens were then sectioned, carbon coated, and examined using a scanning electron microscope and an electron probe microanalyzer (SEM-EPMA) for interfacial adaptation, gap formation, and elemental analysis. The Vickers hardness numbers of the interfacial MTA were recorded 24 hours after GIC placement and 8 days after MTA placement and analyzed using the analysis of variance test.

RESULTS

Hardness testing 24 hours after GIC placement revealed a significant increase in hardness with an increase of temporization time but not with a change of moisture conditions (P < .05). Hardness testing 8 days after MTA placement indicated no significant differences among groups. SEM-EPMA showed interfacial adaptation to improve with temporization time and moisture. Observed changes were limited to the outermost layer of MTA. The 2 null hypotheses were not rejected.

CONCLUSIONS

GIC can be applied over freshly mixed MTA with minimal effects on the MTA, which seemed to decrease with time.

Comparison of shear bond strength of calcium-enriched mixture cement and mineral trioxide aggregate to composite resin

AIM

Adhesion of composite resin and pulp capping biomaterials remarkably influences treatment outcomes. This in vitro study aimed to compare the shear bond strength of composite resin to calcium enriched mixture (CEM) cement, mineral trioxide aggregate (MTA) and resin modified glass ionomer (RMGI) with or without acid etching.

MATERIALS AND METHODS

A total of 90 cylindrical acrylic blocks containing a central hole, measuring 4 mm diameter and 2 mm height were prepared. The blocks were randomly divided into three experimental groups based on being filled with CEM, MTA or RMGI. Samples in each group were then randomly divided into two subgroups, i.e. with or without phosphoric acid etching. Placing composite resin cylinders on the samples, shear bond strengths were measured using a universal testing machine. Failure modes of the samples were evaluated under a stereomicroscope. Data were analyzed using two-way ANOVA and Tukey tests.

RESULTS

Shear bond strengths in the etched and nonetched samples were not significantly different (p = 0.60). There was a significant difference in shear bond strength values of the three experimental materials (p < 0.001) and RMGI showed the highest strength values (p < 0.001); no significant difference was observed between MTA and CEM (p = 0.51). The interaction of the type of material and surface etching was statistically significant (p < 0.001). All of the samples showed cohesive failure mode.

CONCLUSION

Acid etching of MTA, CEM and RMGI do not improve the shear bond strength of these materials to composite resin. Besides, shear bond strength values of MTA and CEM to composite resin, are favorable due to their cohesive mode of failure.

CLINICAL SIGNIFICANCE

When MTA and CEM biomaterials are used in vital pulp therapy, it is advisable to cover these materials with RMGI. In addition, if it is not possible to use RMGI, the surface etching of MTA and CEM biomaterials is not necessary prior to composite restoration using total-etch adhesive resin.

Scanning electron microscopic evaluation of the material interface of adjacent layers of dental materials

OBJECTIVE

Many dental materials are used in contact with each other in sandwich techniques. Liners, bases and permanent restorative materials are placed adjacent to each other and allowed to set under the same conditions. The same applies for endodontic materials where irrigating solutions and root canal dressings come in contact with root canal obturating materials and root-end fillers. The aim of this research was to investigate the material interface of mineral trioxide aggregate (MTA) in contact with non-setting calcium hydroxide paste (CH), glass ionomer cement (GIC) and intermediate restorative material (IRM).

METHODS

All materials were mixed according to manufacturer's instructions. Freshly mixed MTA (Dentsply) was placed in a plastic container and another dental material was compacted on it while still unset. These materials included GIC (Fuji IX), non-setting calcium hydroxide (Calasept) and IRM (Dentsply). The materials were allowed to set for 28 days at 37°C and 100% humidity. The layered materials were sectioned longitudinally embedded in resin and polished to expose the interface between the two materials. Scanning electron microscopy (SEM) was performed of the interface and X-ray energy dispersive analysis (EDX) was conducted at 50 μm intervals to establish elements present at specific distances from the material interface.

RESULTS

The calcium hydroxide paste did not affect the hydration of MTA. Migration of silicon, aluminum and bismuth from the MTA to the CH occurred. The GIC exhibited a high degree of micro-cracking and some porosity in the interfacial region. Strontium from the GIC was detected at 200 μm within the MTA. The zinc from the IRM cement was detected at 100 μm within the MTA. The zinc affected the hydration of the MTA leading to retardation of setting and increased porosity.

CONCLUSIONS

MTA interacts with other dental materials with resultant elemental migration in adjacent materials. Zinc oxide eugenol based cements should be avoided in the presence of MTA as zinc causes retardation of cement hydration with increased porosity. Glass ionomer cements absorb the water of hydration from the MTA also resulting in increased porosity and incomplete hydration of MTA.

"MTA"-an Hydraulic Silicate Cement: review update and setting reaction

OBJECTIVES

To review the current status and understanding of Portland cement-like endodontic materials commonly referred to by the trade designation "MTA" (alias "Mineral Trioxide Aggregate"), and to present an outline setting reaction scheme, hitherto unattempted.

METHOD

The literature was searched using on-line tools, overlapping an earlier substantial review to pick up any omissions, including that in respect of ordinary Portland cement (OPC), with which MTA shares much. The search was conducted for the period January 2005 to December 2009 using 'MTA', 'GMTA', 'WMTA', and 'mineral AND trioxide AND aggregate' as keywords, with various on-line search engines including ScienceDirect (http://www.sciencedirect.com), SAGE Journals Online (http://online.sagepub.com), Wiley Online Library (http://onlinelibrary.wiley.com), SciELO Scientific electronic library online (http://www.scielo.br/scielo.php), JSTOR (http://www.jstor.org), and Scopus (http://www.scopus.com). References of articles found were cross-checked where appropriate for missed publications. Manufacturers' and related websites were searched with Google Search (http://www.google.com.hk).

RESULTS

A generic name for this class of materials, Hydraulic Silicate Cement (HSC), is proposed, and an outline reaction scheme has been deduced. HSC has distinct advantages apparent, including sealing, sterilizing, mineralizing, dentinogenic and osteogenic capacities, which research continues to demonstrate. However, ad hoc modifications have little supporting justification.

SIGNIFICANCE

While HSC has a definite place in dentistry, with few of the drawbacks associated with other materials, some improvements in handling and other properties are highly desirable, as are studies of the mechanisms of the several beneficial physiological effects. Reference to the extensive, but complex, literature on OPC may provide the necessary insight.