Fracture strength of bovine incisors after intra-radicular treatment with MTA in an experimental immature tooth model

Maxillary Incisor Fragment Reattachment Protocols: Influence on Tooth Fracture Resistance and Strength of Bonding to Orthodontic Brackets

Objectives: Trauma to maxillary incisors is frequent, and requires timely, conservative management for optimal prognosis. This in vitro study evaluated the fracture resistance (FR) and orthodontic bracket bond strength (BS) of incisors following incisal fragment reattachment using various restorative techniques. Materials and Methods: Two independent tests-FR testing (Newtons) and BS testing (megapascals)-were conducted. Eighty intact human maxillary central incisors (n = 40/test), standardized in size and shape using a digital caliper (Mitutoyo, ±0.01 mm), were embedded in acrylic resin and numbered. An uncomplicated crown fracture was induced in 64 teeth (n = 32/test), and the teeth were randomly assigned (simple randomization using Excel's RAND function) to five groups (n = 8/group/test): (1) intact teeth (negative control, NC); (2) nanohybrid composite buildup using Filtek Z250 and Single Bond 2 (positive control, CB); (3) fragment reattachment using flowable composite (Filtek Supreme, FL); (4) reattachment with a palatal veneer using a nanohybrid composite (PV); and (5) reattachment reinforced with a polyethylene fiber band (Ribbond Inc., RB). In BS testing groups, stainless steel orthodontic brackets (PINNACLE) were bonded using Transbond XT, centered over the fracture line. Light curing was performed using an LED unit (Mini LED Standard, Acteon, 1250 mW/cm2, 20 s/bond, 40 s/composite, 2 mm curing tip distance). Specimens were stored in distilled water at room temperature for 24 h before reattachment. FR and BS were evaluated using a universal testing machine (Instron) until failure. Failure modes were analyzed, and data were statistically evaluated using one-way ANOVA, Tukey's post hoc test, and Pearson's correlation analysis. Results: Significant differences were observed among groups for both FR and BS (p < 0.05). The NC group exhibited the highest FR (514.4 N) and BS (17.6 MPa). The RB group recorded the second-highest FR (324.6), followed by the PV (234.6), CB (224.9), and FL (203.7) groups. The CB group demonstrated the second-best BS (16.6), followed by the RB (15.2), FL (13.4), and PV (6.5) groups. FR and BS were negatively correlated. Mixed failures predominated in the reattachment groups, except for the PV group, which showed mainly adhesive failures. In BS testing, mixed failures dominated in the NC and CB groups, while adhesive failures predominated in the PV and FL groups. Conclusions: Ribbond reinforcement improves the mechanical performance of reattached incisal fragments, and composite buildup may provide more reliable bracket bonding than fragment reattachment. Clinical Relevance: In cases where biomimetic, minimally invasive reattachment is indicated, Ribbond fiber reinforcement appears to offer a reliable restorative solution.

Combination of Chitosan Nanoparticles, EDTA, and Irrigation Activation Enhances TGF-β1 Release from Dentin: A Laboratory Study

INTRODUCTION

This study aimed to investigate the effects of sonic (EDDY), ultrasonic (PUI), and laser (shock wave-enhanced emission photoacoustic streaming [SWEEPS]) activation of chitosan-nanoparticles enriched ethylenediaminetetraacetic acid (EDTA) irrigation on the release of transforming growth factor beta 1 (TGF-β1) from dentin in regenerative endodontic treatments (RETs).

METHODS

One hundred twenty extracted human teeth were prepared up to size #100 to mimic the open apex. Root canals were irrigated with 20 mL 1.5% NaOCl according to the RETs protocol. Teeth were divided into 3 main groups according to the irrigation solution (17% EDTA, 0.2% chitosan nanoparticles, and the combination of EDTA + chitosan nanoparticles) and 5 subgroups based on the activation methods (syringe-needle irrigation, Irriflex, PUI, EDDY, and SWEEPS). TGF-β1 release was measured on days 1 and 7 using ELISA. Data were analyzed with the significance level set at P < .05.

RESULTS

TGF-β1 release increased progressively from syringe-needle irrigation to Irriflex, PUI, EDDY, and SWEEPS, with SWEEPS achieving the highest release at both time points (P < .05). The combination of EDTA and chitosan nanoparticles yielded significantly higher TGF-β1 levels compared to EDTA or chitosan nanoparticles alone, particularly with SWEEPS and EDDY (P < .05). The percentage increase in TGF-β1 release from day 1 to day 7 was significantly higher in all activation groups (P < .05).

CONCLUSION

The combination of EDTA and chitosan nanoparticles, particularly when used with advanced irrigation activation methods such as SWEEPS and EDDY, significantly increased TGF-β1 release from dentin. These results suggest that both the choice of irrigant and activation method can influence growth factor release in RETs.

Intraradicular reinforcement of traumatized immature anterior teeth after MTA apexification

This review article describes the methods and clinical recommendations for reinforcing traumatized anterior immature teeth with pulp necrosis treated with mineral trioxide aggregate (MTA) apexification. Traumatic injury can cause pulp necrosis and incomplete root formation in immature teeth. MTA apexification is the treatment of choice for necrotic immature teeth, particularly during the middle or late stages of root development. MTA apexification has a high success rate; however, failures due to cervical or root fractures occasionally occur. The risk of fracture is higher in immature teeth with thin root dentin, particularly those with external root resorption. Furthermore, the loading force from any parafunctional habit also increases fracture risk. Therefore, intra-radicular reinforcement may be necessary after MTA apexification. In vitro, intraradicular restoration with a resin composite/core build-up material or a prefabricated fiber post demonstrated better root reinforcement than root canal obturation materials (i.e., gutta-percha and sealer). However, the root-reinforcement effect of MTA orthograde filling in the entire root canal remains unclear. In vivo, the survival of fractured teeth with intraradicular restorations (resin composite/core build-up material or prefabricated fiber posts) is extremely high. Moreover, the survival of teeth with gutta-percha/sealer obturation or MTA orthograde filling and restoration with resin composite extending into the cervical third of the root canal approximately 1-2 mm below the cemento-enamel junction is acceptably high. Based on this evidence, the remaining tooth/root structure and loading force should be carefully examined when considering intra-radicular reinforcement of immature anterior teeth treated with MTA apexification.

Can a dentin bonding agent prevent color change in regenerative endodontic procedures? An in vitro evaluation

This in vitro study aimed to determine the efficacy of dentin bonding agents in preventing color changes following Regenerative Endodontic Procedures. One hundred twenty bovine incisors were endodontically prepared and randomly assigned to a two main factors design: application of a dentin bonding agent (Scotchbond Adper, 3M ESPE, St Paul, MN, USA) in the pulp chamber (Group 1, n=60) versus no bonding intervention (Group 2, n=60), and five levels of intracanal medication (n=12/subgroup): Triple antibiotic paste (TAP), double antibiotic paste (DAB), calcium hydroxide (CH), modified triple antibiotic paste (TAPM), and Control (CTL). Color changes were measured over 28 days at multiple time points (1, 3, 7, 14, 21, and 28 days) using the CIEDE2000 formula to calculate the color difference (ΔE00) from baseline (T0). The ΔE00 quantifies the perceptible color difference between the initial and final tooth color, with lower values indicating less discoloration. The results were analyzed using repeated measures ANOVA-2 and post-hoc Holm-Sidak tests. The TAP subgroups, both with and without the bonding agent, exhibited the highest color variation. However, a pulp chamber seal with a bonding agent showed a protective effect against discoloration compared to no seal, even though complete prevention was not achieved. All groups demonstrated ΔE00 values beyond acceptable interpretation thresholds for clinical application, primarily driven by a reduction in lightness (L*) and a decrease in redness (a* value, shifting towards green). In conclusion, while the pulp chamber seal with a bonding agent mitigated TAP-induced discoloration, it did not eliminate it.

Fracture Resistance of Simulated Immature Teeth Filled with Three Types of Calcium Silicate Cement after Intracanal Medication with Ca(OH)2: An Ex Vivo Study

Objectives

The aim of this study was to evaluate the 1-day fracture resistance of simulated immature teeth with an apical plug with ProRoot MTA, MTA Angelus, and RetroMTA after calcium hydroxide intracanal medication.

Materials and Methods

Sixty extracted, single-rooted human mandibular premolars were randomly divided into six groups of 10 teeth each. Firstly, to standardize the 9 mm root length, the crowns were cut off at and 9 mm below the cementoenamel junction transversely. Simulations for immature apices were carried out by using No. 1-6 Peeso reamers to pass through the apex to obtain a diameter of 1.7 mm at the apical opening. One group served as a negative control without any treatment, while the other groups received 30 days of calcium hydroxide intracanal medication. Four groups were plugs with 4 mm of ProRoot MTA, MTA Angelus, RetroMTA, and gutta-percha, respectively. The last one was served as a positive control group without filling inside. After 1 day of incubation, specimens were vertically loaded in a universal testing machine at a crosshead speed of 1 mm/min until fracture occurred. The peak load to fracture (Newton) and fracture pattern were recorded. A one-way analysis of variance (ANOVA) followed by Tukey's HSD test was used for data analysis.

Results

The highest mean load to fracture was shown in the negative control group (543.33 ± 37.17 N), followed by ProRoot MTA (432.82 ± 68.06 N), MTA Angelus (396.92 ± 59.93 N), RetroMTA (389.08 ± 56.25 N), and gutta-percha (283.28 ± 43.40 N), and the lowest belonged to the positive control group (239.98 ± 27.19 N). The significant differences were found between both the control and experimental groups with an apical plug with calcium silicate cement (p  < 0.05). There were no significant differences among those three apical plugs (p  > 0.05).

Conclusion

Apical plugs with ProRoot MTA, MTA Angelus, and RetroMTA had an immediate strengthening effect on simulated immature teeth after calcium hydroxide intracanal medication had been used.

Evaluation of the removal of 2-Hydroxyisocaproic acid from the root canal and its effect on the bond strength of MTA

This study aimed to evaluate the removal of 2-hydroxyisocaproic acid (HICA) from the root canal system and its effect on the bond strength of the mineral trioxide aggregate (MTA). 126 single-rooted teeth were divided into 3 experimental groups (n = 36) that were treated with double antibiotic paste (DAP), HICA and calcium hydroxide (CH) and one control group (n = 18). In the first part, 18 teeth from each experimental group (n = 54) were examined to remove HICA from the root canal. In the second part, 72 teeth (3 experimental groups (n = 54) and one control group (n = 18)) were used for the evaluation of the push-out bond strength of MTA. There was no statistically significant difference between HICA, DAP and CH residues (p > 0.05). HICA group showed significantly less push-out bond strength (p < 0.05). DAP, HICA and CH could not be removed entirely from the root canal. HICA significantly reduced the bond strength of the MTA.

Impact of different intraorifice barriers on fracture resistance of non-vital bleached teeth

Background and Aim

This study aimed to evaluate the effects of bleaching agents on the fracture resistance of endodontically treated teeth using different intraorifice barrier (IOB) materials.

Materials and Methods

The endodontic treatment was performed for 160 mandibular premolars, and then, the teeth were divided into four groups according to the IOB: Ionoseal, Biodentine, ProRoot MTA, and TheraBase. Then, these teeth were subdivided into four subgroups (n = 10) based on the bleaching agents as distilled water (control), hydrogen peroxide 35% (HP), sodium perborate (SP), and carbamide peroxide 37% (CP). The access cavities were restored with composite resin after applying the bleaching agents for 7 days. The fracture resistance test was performed using a universal testing machine. Data were statistically analyzed, and the significance level was set at 5%. A scanning electron microscope was used to evaluate the effect of bleaching agents on the surfaces of IOBs.

Results

The highest fracture resistance values were observed in Biodentine groups with significant differences compared to Ionoseal and ProRoot MTA (P <.05). The distilled water groups showed significantly the highest fracture resistance compared to SP and HP groups (P <.05). There was no significant difference between SP, HP, and CP groups (P >.05). It was demonstrated that the morphological surface of the intact IOBs (control) was different from the surface of IOBs treated with bleaching agents.

Conclusion

The intracoronal bleaching procedures affected negatively the fracture resistance of the endodontically treated teeth.

Novel management of internal root resorption with vertical root fracture using mineral trioxide aggregate - A case report

Introduction

This case report presents the diagnosis and management of extensive internal root resorption (IRR) in a 17-year-old male patient, with a 9-year-old history of trauma.

Method

The affected tooth 21 was associated with vertical root fracture (VRF) and incomplete apex closure with a substantial loss of tooth structure, including dentin and cementum. Encouraged by a healthy periodontal condition, the choice was made to use mineral trioxide aggregate (MTA) to reconstruct and reinforce the resorptive defect and the fractured segment. A composite veneer was placed to enhance the aesthetics.

Result

A follow-up of the patient after 2 years revealed healing with a resolution of the lesion.

Conclusion

This case report highlights the use of MTA as a lone-standing filling material for the treatment of IRR with VRF in a non-vital immature tooth.

A critical analysis of research methods and experimental models to study root canal fillings

Canal filling materials and techniques have been one of the most studied topics in Endodontics. A simple search using the mesh term "root canal filling" in PubMed revealed more than 11,000 articles, an impressive number that is much higher than "root canal disinfection" (5,544 articles) or even the popular "root canal preparation" (8,527 articles). The overriding importance attributed to root filling procedures is not merely intuitive. It derived from the appealing relevance given by the appearance of the white lines in common radiographs grounded on retrospective clinical data that had identified the quality of a root filling as one of the major causes of treatment failure (lack of healing). Since the publication of the Washington study, impressive efforts have been made for the release of new materials and techniques, as well as, for the development of a plethora of laboratory methods to assess the quality of root filling procedures. This narrative review aims to address and discuss the most relevant laboratory methods to assess the root canal filling. Since filling quality improvements have not translated into higher success rates, as reported in longitudinal clinical studies, more than to deliver a simple methodology-based review, this paper aims to present an in-depth critical view on the assessment of laboratory methods used to study the filling materials and techniques. Recent data indicate that the long-term dimensional stability/degradation over time of endodontic sealers plays a central role in the treatment outcome. In this context, laboratory methods should be developed focusing on predicting, at least to some degree, the long-term clinical behaviour of root canal fillings, rather than simply ranking different materials or techniques.

Comparison of Obturation Quality after MTA Orthograde Filling with Various Obturation Techniques

This study aimed to quantify and compare the obturation quality after mineral trioxide aggregate (MTA) orthograde fillings with three different obturation techniques. Thirty-three extracted human maxillary molars were collected. Distobuccal and palatal canals were prepared to an apical size of #40/06 with a Profile Ni-Ti system. All 66 canals were divided into two groups according to the material (EZ-seal or OrthoMTA) and then obturated using three different techniques: manual compaction using S-kondenser (group H), compactor activation (group C), or reverse rotary motion of Ni-Ti file (group R). The obturated roots were scanned using micro-computed tomography (micro-CT). The percentage of voids located in the apical 5 mm was measured separately, that is, closed, open, and total porosity. There was no relation between the filling material and obturation technique (p > 0.05). The percentage volume of open and total porosity was higher in EZ-seal than in OrthoMTA (open: p = 0.002, total: p = 0.001). Group H showed higher open and total porosity than groups C and R. Micro-CT analysis showed that the void volume after orthograde MTA fillings significantly decreased when the additional activation was accompanied by hand condensation. Obturation with a Ni-Ti file using reverse motion could be recommended as an MTA orthograde filling technique.

The effect of diabetes on Fracture Resistance of Teeth: An in vitro study

The root fracture resistance (RFR) of premolars extracted from diabetic patients and the effect of biomaterials: white mineral trioxide aggregate (WMTA) and WMTA+Na₂ HPO₄ as an additive, on enhancing RFR were evaluated. Diabetic and non-diabetic teeth were divided into 4 subgroups (n = 5): root canals were obturated with WMTA, WMTA+Na₂ HPO₄ , gutta-percha and one unfilled (control). A plunger (1 mm diameter) applied a downward compressive load with crosshead speed of 1 mm min^-1 on the specimens mounted on resin blocks, and the ultimate force to fracture was measured. The mean RFR values of diabetic specimens were significantly lower. The lowest and highest means of RFR were recorded in the control and WMTA, in normal group and the control and WMTA+Na₂ HPO₄ in the diabetic group, respectively. The RFR in diabetic patients was significantly lower, indicating their higher susceptibility to fracture under vertical forces. The use of WMTA (with or without Na₂ HPO₄ ) for obturation enhances the RFR.

Effect of mineral trioxide aggregate and biodentine™ on fracture resistance of immature teeth dentine over time: in vitro study

PURPOSE

The aim of this in vitro study was to evaluate the effect of root filling with White Mineral Trioxide Aggregate (WMTA) and Biodentine™ (BD) on the fracture resistance of simulated immature teeth over different time periods.

METHODS

Sixty sound-extracted human single-rooted premolars were randomly allocated into 3 groups, 2 experimental and 1 control group, with 20 teeth each. Simulation of roots into immature apices were done using Peeso reamers. After preparation, the root canals of teeth in the experimental groups were completely filled with either WMTA or BD. The control group was subdivided into positive controls (n = 10) which received no treatment and negative controls (n = 10) which were prepared the same way and filled with normal saline. The specimens were subjected to fracture testing using a universal testing machine after 2 weeks and 3 months. The peak load to fracture and the fracture location were recorded.

RESULTS

Regarding fracture resistance, the MTA group had the highest fracture resistance at 2 weeks testing, while at 3 months there was no significant difference between the groups (P > 0.05). Regarding fracture location, at 2 weeks there was no significant difference in the fracture location between the groups, while at 3 months, the difference was significant (P < 0.05), the middle root fracture being the most frequent (63.3%).

CONCLUSION

No significant difference in fracture resistant of simulated immature teeth was observed after 3 months when they were filled with Biodentine or WMTA, indicating that Biodentine could be a suitable substitute for MTA. There was no difference in the possible fracture location at 2 weeks, while after 3 months middle root fractures were more frequent.

Evaluation of Stress Distributions in Mandibular Molar Teeth with Different Iatrogenic Root Perforations Repaired with Biodentine or Mineral Trioxide Aggregate: A Finite Element Analysis Study

INTRODUCTION

In this study, finite element analysis was used to evaluate the stress distributions in simulated mandibular molar teeth with various iatrogenic root perforation types after reparation with Biodentine (Septodont, Saint-Maur-des-Fossés, France) or mineral trioxide aggregate (MTA).

METHODS

An extracted human mandibular molar tooth was scanned using a micro-computed tomographic device, and a 3-dimensional solid model was created. Then, 3 different iatrogenic perforation types (furcation perforation [FP], strip perforation [SP], and post drill perforation [PDP]) and 2 different repair materials (MTA and Biodentine [BD]) were simulated on the model. In addition, a sound tooth (ST) model (control) and a model left unrepaired for each type of perforation were created; then, access cavities were restored using resin composite, except for the sound tooth model. Consequently, a total of 10 experimental models were designed. An oblique force of 300 N angled at 45° to the occlusal plane was simulated. Evaluations of von Mises stress were performed in the perforated regions.

RESULTS

Maximum von Mises stress values were 7.76 MPa for ST/corresponding to the FP region, 8.48 MPa for ST/corresponding to the SP region, 14.20 MPa for ST/corresponding to the PDP region, 10.89 MPa for FP /MTA, 7.65 MPa for FP/BD, 14.67 MPa for FP/unrepaired, 15.92 MPa for SP/MTA, 15.82 MPa for SP/BD, 21.95 MPa for SP/unrepaired, 10.20 MPa for PDP/MTA, 9.17 MPa for PDP/BD, and 17.86 MPa for PDP/unrepaired.

CONCLUSIONS

The results of this finite element analysis indicated that BD models showed lower maximum von Mises stress values than the MTA models, and SPs exposed higher stress concentrations in root perforation regions than FPs and PDPs. The use of MTA and BD may reduce the risk of potentially harmful stress in root perforation regions.

Comparative evaluation of fracture resistance of simulated immature teeth and its effect on single visit apexification versus complete obturation using MTA and biodentine

AIM AND OBJECTIVES

This study sought to evaluate and compare the fractured resistance of simulated immature teeth and the effect of single visit apexification versus complete obturation using MTA and biodentine.

MATERIAL AND METHODOLOGY

Forty-five freshly extracted sound maxillary central incisors with single canal were selected. The apical 5 mm of each sample was then sectioned to simulate Cvek's stage 3 root development access cavity preparation, followed by preparation using peeso reamers. Irrigation was carried out followed by randomization of samples. Obturation was performed using different materials. Fracture resistance was checked under universal testing machine, by recording the ultimate load to fracture in Newtons.

STATISTICAL ANALYSIS

Statistical analysis was performed using SPSS 20.0 Software. One-way analysis of variance followed by pair wise comparison of the groups was performed using Tukey's post-hoc test. The significance level was set at P < 0.05.

RESULTS

All the experimental groups showed statistically higher value of fracture resistance than the control groups. Group I (entire canal obturated with MTA) reported highest value of fracture resistance followed by group III (entire canal obturated with biodentine), group II, and group IV.

CONCLUSION

In apexification cases, reinforcing the immature teeth with bioceramic materials such as MTA and biodentine is advantageous.

CLINICAL SIGNIFICANCE

Clinically in patients, high success rate of apexification can be achieved with complete MTA obturation as compared to MTA and biodentine apical plug and gutta percha obturation.

Bioactive tri/dicalcium silicate cements for treatment of pulpal and periapical tissues

Over 2500 articles and 200 reviews have been published on the bioactive tri/dicalcium silicate dental materials. The indications have expanded since their introduction in the 1990s from endodontic restorative and pulpal treatments to endodontic sealing and obturation. Bioactive ceramics, based on tri/dicalcium silicate cements, are now an indispensable part of the contemporary dental armamentarium for specialists including endodontists, pediatric dentists, oral surgeons andfor general dentists. This review emphasizes research on how these materials have conformed to international standards for dental materials ranging from biocompatibility (ISO 7405) to conformance as root canal sealers (ISO 6876). Potential future developments of alternative hydraulic materials were included. This review provides accurate materials science information on these important materials. STATEMENT OF SIGNIFICANCE: The broadening indications and the proliferation of tri/dicalcium silicate-based products make this relatively new dental material important for all dentists and biomaterials scientists. Presenting the variations in compositions, properties, indications and clinical performance enable clinicians to choose the material most suitable for their cases. Researchers may expand their bioactive investigations to further validate and improve materials and outcomes.

Fracture Resistance of Immature Incisors Following Root Filling with Various Bioactive Endodontic Cements Using an Experimental Bovine Tooth Model

Objective The aim of this study was to compare the fracture resistance of immature bovine roots when using ProRoot MTA, CEM Cement, and Biodentine as root filling materials.

Materials and Methods An immature bovine tooth model was developed by removing the coronal and apical portions of 70 bovine incisors 8 mm above and 12 mm below the cementoenamel junction (CEJ). The specimens were then divided into five groups: ProRoot MTA, CEM Cement, Biodentine, gutta-percha/AH26 sealer, and control. All groups received a 5-mm apical plug with a temporary restorative material. Then, the remaining root canal space was filled with one of the afore-mentioned materials. After setting, the specimens were mounted in acrylic resin. Then, 3 mm coronal to the CEJ from the buccal side of the teeth and at a 135°angle to the long axis, the specimens were loaded until fracture.

Results The specimens in the Biodentine (2196 N) and ProRoot MTA (2103 N) groups had significantly greater fracture resistance in comparison to the control group ( p = 0.01). No significant difference was found between CEM Cement, gutta-percha and sealer AH26, and control groups. No significant differences occurred between the four experimental groups ( p = 0.45).

Conclusion Filling the root canal space with ProRoot MTA and Biodentine contributed to higher fracture resistance values.

Comparison of the Effects of Intraradicular Materials on the Incidence of Fatal Root Fracture in Immature Teeth Treated with Mineral Trioxide Aggregate Apexification: A Retrospective Study

INTRODUCTION

This study aimed to compare the incidence of root fractures that led to extraction in immature teeth endodontically treated by mineral trioxide aggregate (MTA) apexification and were restored with either reinforced (resin composite or fiber post) or nonreinforced (gutta percha or MTA) intraradicular materials.

METHODS

Necrotic immature teeth treated with MTA apexification from 1996 to 2017 were selected according to the inclusion and exclusion criteria. Intraradicular materials and preoperative and treatment factors were obtained from dental charts and radiographs. The incidence of fatal root facture was identified. Kaplan-Meier survival analysis and the Cox proportional hazard model were used to show the survival rate and predisposing factors at a significance level of .05.

RESULTS

The average recall period was 30 months. The incidence of root fracture in the teeth restored with the reinforced materials was 5.5%, which was not significantly different from the nonreinforced materials (8.3%). Furthermore, the fracture rates between the fiber post and resin composite groups were not significantly different. Two significant predisposing factors influencing the incidence of root fracture were detected: preoperative external inflammatory root resorption (hazard ratio = 26.86; P < .05) and patient age > 15 years (hazard ratio = 8.60, P < .05).

CONCLUSIONS

Immature teeth treated with MTA apexification and restored with the reinforced or nonreinforced intraradicular materials exhibited a similar rate of root fracture. Preoperative external inflammatory root resorption and patient age > 15 years were found to be the predisposing factors that significantly increased the incidence of root fracture.

Do the intracanal medicaments affect the marginal adaptation of calcium silicate-based materials to dentin?

Background/purpose

In order to prevent reinfection of the pulp canal space and dressing for regenerative purpose, the coronal seal should have a perfect marginal adaptation. Mineral trioxide aggregate (MTA) and Biodentine are among the most popular sealing materials. These are commonly used in combination with antibiotic medicaments, to ensure disinfection. Aim of the present study was to evaluate the effect of 3 different medicaments on the marginal adaptation of MTA and Biodentine to the dentin.

Materials and methods

Teeth were divided into 4 groups (n = 20) that were treated with the following medicaments; triple antibiotic paste (TAP), double antibiotic paste (DAP), a calcium hydroxide (CH) and a control group. The specimens were then assigned into two subgroups (n = 10), which received a coronal barrier of MTA or Biodentine. The specimens were scanned using an ex vivo micro-CT scanner. The data were statistically analysed using one-way ANOVA and the unpaired Student's t-test (P < 0.05).

Results

Percentage volume of external voids in the MTA group was as follows: DAP > TAP > Control > CH. In the Biodentine group, the percentage of voids was determined in the following order: TAP ≥ DAP > CH > Control. Significantly lower percentage of voids was observed in the CH-medicated specimens in the MTA group when compared to all test groups (P = 0.04).

Conclusion

The application of CH as an intracanal medicament reduced the void occurrence between the ProRoot MTA and root dentin. However, TAP and or DAP decreased the marginal adaptation in both ProRoot MTA and Biodentine.

Fracture resistance of simulated immature teeth treated with a regenerative endodontic protocol

This study aims to evaluate fracture resistance of simulated immature teeth after treatment with regenerative endodontic procedure (REP) using tricalcium silicate cements (TSCs) as cervical plugs. Bovine incisors were sectioned to standard crown/root ratio. Pulp tissue was removed and canals were enlarged to a standardized diameter. Teeth were then treated with a REP protocol consisting of NaOCl and EDTA irrigation, intracanal medication with triple-antibiotic paste for 14 days followed by a TSC cervical seal and composite restoration. Teeth were divided into groups according to the material used; Mineral-Trioxide-Aggregate (MTA), Biodentine, TotalFill. Teeth filled with guttapercha (GP) and intact teeth served as controls. All teeth subjected to an increasing compressive force (rate of 0.05 mm/s at a 45° angle to the long axis of the tooth) until fracture. All treated teeth exhibited significantly lower resistance to fracture compared to the intact teeth but no difference was found between the TSC groups (Kruskal-Wallis, Dunn’s multiple comparison, p < .05). TSCs applied at the cervical area of simulated immature teeth treated with REP did not reinforce fracture resistance.

Effect of titanium tetrafluoride addition on the physicochemical and antibacterial properties of Biodentine as intraorfice barrier

OBJECTIVE

To evaluate the influence of titanium tetrafluoride (TiF₄) incorporation on the physicochemical and antibacterial properties of Biodentine (BD; Septodont, Saint Maur des Faussés, France) as an intraorfice barrier material.

METHODS

Three different proportions of TiF₄ powder were used with BD; 1wt%, 2wt%, and 3wt%; respectively. BD without TiF₄ addition was used as the control group. The setting time (ST) was determined using Gillmore needle apparatus. Diametral tensile strength (DTS) and fracture resistance were measured in a universal testing machine. Solubility was assessed using mass variation after 7days water storage. The hardness test was conducted using Vickers microhardness tester. The antibacterial activity was assessed using direct contact test against Enterococcus faecalis. Radiopacity was assessed and expressed in thickness of aluminum. Surface topography and elemental composition of modified BD were also assessed. The pH of soaking water was measured up to 168h. Data of tested properties were analyzed using one-way analysis of variance, the paired t-test, two-way repeated measures analysis of variance, and Tukey post hoc tests (P<0.05).

RESULTS

BD-incorporating 2wt% TiF₄ revealed the highest surface microhardness, DTS, and fracture resistance compared with the unmodified group (P<0.001). Higher concentrations of TiF₄ (3wt%) compromised the solubility and prolonged the ST of BD (P<0.05). Bacterial growth of BD-incorporating TiF₄ was significantly reduced when compared with the control group (P<0.05). The tested materials induced alkalization of the soaking water that decreased with time.

SIGNIFICANCE

Biodentine-incorporating TiF₄ (1wt% and 2wt%) is a promising intraorfice barrier material with enhanced physicochemical and antibacterial properties.

Effect of Different Intraorifice Barriers and Bleaching Agents on the Fracture Resistance of Endodontically Treated Anterior Teeth

INTRODUCTION

Intraorifice barriers (IOBs) are usually used before internal bleaching for coronal sealing and the prevention of cervical resorption. The aim of this study was to investigate the effect of different IOBs on the fracture resistance (FR) of endodontically treated anterior teeth bleached with various bleaching agents (BAs).

METHODS

After performing root canal treatment for 72 extracted bovine upper incisors, the coronal 3 mm of gutta-percha was removed, and samples were classified into 3 based on the type of IOB: calcium-enriched mixture, mineral trioxide aggregate, and resin-modified glass ionomer. After applying IOBs, samples of each group were subdivided into 4 based on the BA: carbamide peroxide 45% (CP), hydrogen peroxide 35% (HP), sodium perborate (PB), and distilled water as the control. At the end of bleaching, the access cavities were restored with composite resin. The FR was measured with a universal testing machine at a crosshead speed of 5 mm/min. The data were analyzed using 2-way analysis of variance and least significant difference post hoc tests (P < .05).

RESULTS

The effect of BAs on the FR was significant (P < .05); however, the effect of the IOB and the interactive effect of these variables were not significant (P > .05). The FR in the HP and PB groups was significantly different from the control (P < .05) but that of CP was not significantly different from the control (P > .05).

CONCLUSIONS

Mineral trioxide aggregate and calcium-enriched mixture act similarly to resin-modified glass ionomer as an IOB. CP, unlike HP and PB, did not significantly decrease the FR.

Comparative evaluation of the vertical fracture resistance of endodontically treated roots filled with Gutta-percha and Resilon: a meta-analysis of in vitro studies

Background

Teeth treated endodontically are more susceptible to vertical root fracture (VRF). Some studies have suggested that obturating the root canals with Gutta-percha or Resilon can reinforce endodontically treated teeth, but a few others have presented conflicting results. These inconsistent results cannot guide clinicians in determining clinical approaches. The objective of this meta-analysis is to evaluate and compare the vertical fracture resistance of endodontically treated root canals obturated with Gutta-percha/AH plus and the Resilon system.

Methods

Comprehensive literature searches were performed in the PubMed, Cochrane Library, ScienceDirect, Web of Science and Embase databases. The titles and abstracts of all of the retrieved articles were independently assessed by two authors according to predefined selection criteria. Data in the included articles were independently extracted. Statistical analyses were conducted using Review Manager 5.3 and Stata 12.0 software. The pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated for the outcome indicators. The level of statistical significance was set at p < 0.05. The Cochran Q test (I² test) was used to test for heterogeneity among studies.

Results

Fourteen randomized controlled in vitro trials were included in the meta-analysis. The results demonstrated that the vertical root fracture resistance of unprepared and unfilled roots was significantly higher than that of roots obturated with Gutta-percha/AH plus (SMD = − 0.69, 95% CI = − 1.34 to − 0.04, p = 0.04) or the Resilon system (SMD = − 0.54, 95% CI = − 1.07 to − 0.00, p = 0.05). The differences in fracture resistance between the roots filled with Gutta-percha/AH plus and the prepared unfilled root canals was not significant (SMD = 0.59, 95% CI = − 0.02 to 1.21, p = 0.06). Roots obturated with Resilon had higher fracture resistance than instrumented unfilled roots (SMD = 0.83, 95% CI = 0.44 to 1.22, p < 0.0001) or roots filled with Gutta-percha/AH plus (SMD = 0.62, 95% CI = 0.01 to 1.23, p = 0.05).

Conclusions

The present study suggests that filling with Gutta-percha/AH plus dose not reinforce endodontically treated roots, whereas obturating with the Resilon system can increase vertical root fracture resistance of prepared roots. As this meta-analysis was based on in vitro studies, it should be careful to extrapolate its conclusion to the clinical context.

Stress distributions in internal resorption cavities restored with different materials at different root levels: A finite element analysis study

The aim of this study was to evaluate the stresses within simulated roots with internal resorption cavities at the apical, middle and coronal root levels, after obturation with gutta-percha and/or MTA utilising finite element analysis (FEA). Mandibular premolar teeth with internal resorption cavities at different root levels were modelled. Models were restored with gutta-percha and/or MTA. An oblique force of 300 N was applied and stress evaluations were carried out. In the MTA-filled resorption models, the stresses were distributed more homogeneously than the gutta-percha filled models, and the stress concentrations were lower in the remaining dentinal tissues. If the whole root is considered, the fully gutta-percha-filled models generated the highest stress values. Differences between the fully MTA-filled models and hybrid techniques were present only in the apical resorption models. Both the MTA and combination of MTA and gutta-percha can be suggested for use in clinical practice, in cases of internal root resorption cavity obturation.

Reinforcement of Simulated Immature Permanent Teeth after Mineral Trioxide Aggregate Apexification

OBJECTIVES

The objectives of this study were to compare the fracture resistance of simulated human immature teeth that have undergone mineral trioxide aggregate (MTA) apexification and have been root-filled with fiber post, composite resin, MTA, or gutta-percha.

METHODS

Fifty-six human permanent maxillary incisors were selected. Ten teeth received no treatment (intact teeth group). The root canals of 46 teeth were prepared to an internal diameter of 1.75 mm. Six teeth were used as simulated immature teeth group. The remaining teeth received MTA apexification and were divided into 4 groups: MTA, fiber post, composite resin, and gutta-percha groups. The root canals of each group were filled with each test material. All teeth were thermocycled and received cyclic loading before compression testing by an Instron universal testing machine. The load to fracture was recorded. Data were subjected to statistical analysis by using one-way analysis of variance and Tukey multiple comparison test.

RESULTS

All teeth fractured at the cervical area of the root. The mean load to fracture of the intact tooth, MTA, fiber post, composite resin, gutta-percha, and the simulated immature tooth groups was 1988 N, 1921 N, 1691 N, 1623 N, 1476 N, and 962 N, respectively. Statistically, load to fracture of the simulated immature tooth group was significantly lower than in the intact tooth, MTA, fiber post, and composite resin groups but was not significantly different from the gutta-percha group.

CONCLUSIONS

Within the limit of this study, after MTA apexification, intraradicular reinforcement with MTA, fiber post, or composite resin increased the fracture resistance of simulated immature teeth.

Fracture resistance of simulated immature teeth after internal bleaching procedures

The aim of this study was to evaluate the fracture resistance of simulated immature teeth after internal bleaching. The teeth were assigned as follows (n = 12/group); Group-1: The pulp chamber was filled with ProRootMTA and bleached intracoronally with sodium perborate mixed with 37% carbamide peroxide gel; Group-2: The pulp chamber was filled with ProRootMTA without bleaching; Group-3: The pulp chamber was filled with Biodentine and bleached intracoronally as Group-1; Group-4: The pulp chamber was filled with Biodentine without bleaching; and Group-5: Teeth received no intervention (control). The specimens were loaded vertically until root fracture occurred. The data were analysed with Kruskal-Wallis and Dunn tests. There was no significant difference between the fracture resistances of the experimental groups (P > 0.05). However, all experimental groups had significantly lower fracture resistance than the control group (P < 0.05). Neither the tested calcium silicate cements nor the bleaching procedures had a significant impact on fracture resistance values.

Behavior of mineral trioxide aggregate apical plugs and root fillings under cyclic loading

AIM

The aim of the present study was to develop a methodology for constant monitoring of the resistance to fluid flow during functional loading and to then compare the efficacy of 4-mm mineral trioxide aggregate (MTA) apical plugs and full-length MTA root fillings.

METHODS

The root canals of 24 single-rooted teeth were instrumented and assigned into two groups: group 1 (filled with a 4-mm MTA apical plug and gutta percha) and group 2 (filled with MTA to cementoenamel junction level). All teeth were subjected to stepwise cyclic loading with a constant simulated interstitial pressure of 25 cm H₂ O applied apically. A Flodec machine (De Marco Engineering, Geneva, Switzerland) constantly monitored the rate and direction of fluid flow. Student's t-test, Kruskal-Wallis test, Fisher's exact test, and Newcombe-Wilson test were used for statistical analysis, with P < 0.05.

RESULTS

Crown fractures occurred in 21 teeth with no change in the rate of fluid flow. Three teeth (filled with full-length MTA) showed sudden change in the rate of fluid flow through the root canal after cyclic loading.

CONCLUSIONS

The methodology reliably monitored fluid flow during cyclic loading. There was no difference between a 4-mm MTA apical plug and full-length MTA root filling after cyclic loading using a dynamic fluid-flow monitoring technique.

Effect of Mineral Trioxide Aggregate Apical Plug Thickness on Fracture Resistance of Immature Teeth

INTRODUCTION

The aim of this study was to compare the fracture resistance of simulated immature teeth after using different thicknesses of mineral trioxide aggregate (MTA) apical plugs.

METHODS

Fifty-two human maxillary anterior teeth were used. Five teeth were the positive control group; they were prepared using Peeso reamers to simulate immature teeth without any access cavity preparation. Access cavities of the 47 teeth were prepared, and the canals were instrumented with Peeso reamers. Five teeth served as the negative control; they were filled with calcium hydroxide. Forty-two teeth were divided into 3 groups; in groups 1, 2, and 3, MTA was placed into canals as a 3-mm and a 6-mm apical plug and a thorough canal length, respectively. The rest of the canals in groups 1 and 2 were filled with gutta-percha and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany). After the storage period, the roots were covered with a polyether impression material and were embedded into self-curing resin blocks. Each specimen was then subjected to fracture testing using a universal testing machine. Data were analyzed using 1-way analysis of variance with the Tukey post hoc test for multiple comparisons.

RESULTS

The negative group showed the lowest fracture resistance compared with the other groups. The 3-mm apical plug group showed the highest fracture resistance (P < .05). No significant differences were found between the 3-mm and 6-mm apical plug groups (P > .05).

CONCLUSIONS

MTA should be used as an apical plug instead of root canal filling material to increase the fracture resistance of immature teeth.

Crown discoloration promoted by materials used in regenerative endodontic procedures and effect of dental bleaching: spectrophotometric analysis

Regenerative endodontic procedure (REP) has been proposed as a new approach to treat immature permanent teeth. However, materials used in REP for root canal disinfection or cervical sealing may induce tooth discoloration.

Fracture resistance of simulated immature teeth after different intra-radicular treatments

The aim of this study was to evaluate the fracture resistance of simulated immature teeth after different intra-radicular treatments. Crowns and roots of bovine incisors were cut transversally and removed to simulate immature teeth. Root canal preparation and flaring were performed using a bur in crown-apex and apex-crown direction. The samples were distributed into 5 groups (n=10): Positive control (PoC) - no root canal flaring or filling; Negative control (NeC) - teeth were sectioned and their root canals were flared; Direct anatomical glass fiber post (RaP) - #2 Reforpost main glass fiber post relined with composite resin; Double tapered conical glass fiber posts (ExP) - #3 Exacto glass fiber post; and #2 Reforpost main glass fiber + Reforpin accessory glass fiber posts (RrP). In RaP, ExP and RrP, 4.0-mm apical plugs were done with MTA Angelus. The specimens were embedded in polystyrene resin inside cylinders and the periodontal ligament was simulated with a polyether-based impression material. The specimens were submitted to compressive fracture strength test (0.5 mm/min at 135° relative to the long axis of the tooth) in a servo-hydraulic mechanical testing machine MTS 810. Data were subjected to one-way ANOVA and Dunnett's C or Tukey's tests (α=0.05). The control groups (PoC and NeC) showed lower fracture strength than the experimental groups. NeC presented the lowest resistance and ExP presented the highest resistance among the experimental groups. The flaring procedures produced a detrimental effect on the fracture resistance of the bovine teeth. Glass fiber intra-radicular posts increased significantly the fracture resistance of simulated immature teeth.

Effect of obturating materials on fracture resistance of simulated immature teeth

Aim:

The aim of this study was to evaluate the fracture resistance of simulated immature teeth, when the root canals were completely filled either with mineral trioxide aggregate (MTA) or Biodentine, comparing with that of roots filled with apexification procedure.

Materials and Methods:

Sixty mandibular premolar teeth with single, straight canals decoronated at cementoenamel junction were divided into five groups (n = 12 each). Group 1 samples served as negative control and remaining four groups root samples were shaped and cleaned using ProTaper rotary files. To simulate immature roots, a #5 Peeso reamer was passed beyond the apex so that apices were enlarged to a diameter of 1.5 mm. Group 2 and 4 samples were filled with 5 mm of MTA or Biodentine apical plug and backfilling with gutta-percha using AH Plus sealer. Group 3 and 5 root samples were completely obturated with MTA and Biodentine, respectively. All the teeth were loaded vertically until fracture, using the universal testing machine.

Statistical Analysis:

Forces at which fracture of the roots occurred were subjected to statistical analysis using SPSS/PC version 2 software, and the results were analyzed with the one-way analysis of variance and Newman–Keuls multiple post hoc test.

Results:

Complete root canal obturation with MTA or Biodentine has shown significantly higher fracture resistance (P < 0.05) when compared to apexification with MTA or Biodentine.

Conclusion:

Obturation of the root canals with bioactive materials has shown highest fracture resistance when compared to apexification groups.

On the Causality Between Dentinal Defects and Root Canal Preparation: A Micro-CT Assessment

Abstract This study aimed to evaluate the cause-effect relationship between canal preparation with ProTaper Universal (PTU) system and dentinal defects formation using micro-computed tomography (micro-CT) analysis. Forty mesial canals of mandibular molars with a type II Vertucci's canal configuration were scanned at an isotropic resolution of 14.16 µm. The sample was assigned to an experimental (n = 30) and a control (n = 10) groups, and the mesial canals were prepared with PTU system up to F2 instrument. The specimens from the experimental group were scanned and the cross-section images of the mesial roots, before and after preparation, were screened to identify the presence of dentinal defects. In the control group, the specimens were sectioned perpendicularly to the long axis of the root into 1-mm-thick slices (n = 80) and examined under optical microscope. Once a dentinal defect was detected, the slice was scanned through micro-CT. In the experimental group, dentinal micro-cracks were observed in 4,828 slices (24.04%). In all cross-section images, dentinal defects identified in the postoperative images were already present in the corresponding preoperative image. In the control group, 13 out of 80 slices (16.25%) had at least one dentinal defect visualized under stereomicroscopy, which was identified after a further micro-CT scanning. Micro-CT showed reliability as similar as optical microscopy in detecting dentinal defects, adding the possibility of tracking the dentinal tissue, before and after canal preparation, and providing a clear visualization of micro-cracks. Root canal preparation with PTU system did not induce the formation of new dentinal defects.

Long-Term Fracture Resistance of Simulated Immature Teeth Filled with Various Calcium Silicate-Based Materials

Objective. The aim of this in vitro study was to evaluate the long-term fracture resistance of simulated human immature permanent teeth filled with BioAggregate™ (BA), mineral trioxide aggregate (MTA), and EndoSequence® Root Repair Material (ERRM). Material and Methods. 40 teeth, simulated to average root length of 13 ± 1 mm (Cvek's stage 3), were included in the study. The teeth were randomly divided into four groups: Group 1: DiaRoot® BA, Group 2: MTA-Plus™ (MTA-P), Group 3: MTA-Angelus (MTA-A), and Group 4: ERRM. The root canal filling materials were applied according to the manufacturers' instructions. After 24 months of incubation, the roots of the teeth were embedded in acrylic blocks and subjected to fracture testing. The resultant data were analyzed statistically by Kruskal-Wallis and Mann-Whitney U tests. Results. Mean (±SD) failure loads (MPa) were 20.46 ± 2.53 for BA, 18.88 ± 5.13 for MTA-P, 14.12 ± 1.99 for MTA-A, and 17.65 ± 4.28 for ERRM groups. BA group exhibited the highest and MTA-A group showed the lowest resistance to fracture. Significant differences in fracture resistance were found between the groups of BA and MTA-A (p < 0.001), MTA-P and MTA-A (p < 0.05), and ERRM and MTA-A (p < 0.05). Conclusion. Within the limitations of this study, data suggests that BA-filled immature teeth demonstrate higher fracture resistance than other groups at 24 months appearing to be the most promising material tested.

Fracture resistance of immature teeth filled with mineral trioxide aggregate, bioaggregate, and biodentine

Objective:

The purpose of this study was to evaluate fracture resistance of teeth with immature apices treated with coronal placement of mineral trioxide aggregate (MTA), bioaggregate (BA), and Biodentine.

Materials and Methods:

Forty-one freshly extracted, single-rooted human premolar teeth were used for the study. At first, the root length was standardized to 9 mm. The crown-down technique was used for the preparation of the root canals using the rotary ProTaper system (Dentsply Maillefer, Ballaigues, Switzerland) of F3 (30). Peeso reamer no. 6 was stepped out from the apex to simulate an incompletely formed root. The prepared roots were randomly assigned to one control (n = 5) and three experimental (n = 12) groups, as described below. Group 1: White MTA (Angelus, Londrina, Brazil) was prepared as per the manufacturer's instructions and compacted into the root canal using MAP system (Dentsply Maillefer, Ballaigues, Switzerland) and condensed by pluggers (Angelus, Londrina, Brazil). Group 2: The canals were filled with DiaRoot-BA (DiaDent Group International, Canada). Group 3: Biodentine (Septodont, Saint Maur des Fosses, France) solution was mixed with the capsule powder and condensed using pluggers. Instron was used to determine the maximum horizontal load to fracture the tooth, placing the tip 3 mm incisal to the cementoenamel junction. Mean values of the fracture strength were compared by ANOVA followed by a post hoc test. P < 0.05 was considered statistically significant.

Results:

No significant difference was observed among the MTA, BA, and biodentine experimental groups.

Conclusion:

All the three materials tested, may be used as effective strengthening agents for immature teeth.

Fracture resistance of simulated immature teeth after apexification with calcium silicate-based materials

Objective:

To compare the fracture resistance of simulated immature teeth filled with an apical barrier of mineral trioxide aggregate (MTA), Biodentine, and calcium-enriched mixture (CEM).

Materials and Methods:

Fifty-two single-rooted human maxillary central incisors were used. For standardization, the teeth were sectioned 6 mm above and 9 mm below the cementoenamel junction to simulate immature apex. Simulations of roots into immature apices were carried out using 1.5 mm diameter drills. The specimens were then randomly divided into three experimental groups (n = 13) and one control group (n = 13). In experimental groups, MTA, Biodentine, and CEM were placed to apical 4 mm of the simulated immature roots. The samples were stored at 37° C and 100% humidity for 1 week. A load was applied on the crown of all teeth at 135° to their long axis until fracture. The data were analyzed using one-way analysis of variance and Tukey post-hoc tests.

Results:

No statistically significant differences were found among MTA, CEM, and Biodentine (P > 0.05), and these groups demonstrated higher fracture resistance than control group (P < 0.05).

Conclusions:

Using any of the MTA, Biodentine, and CEM as an apical plug and restoring with fiber post and composite resin increases the fracture resistance of immature teeth.

Cytotoxicity and osteogenic potential of silicate calcium cements as potential protective materials for pulpal revascularization

OBJECTIVES

In pulpal revascularization, a protective material is placed coronal to the blood clot to prevent recontamination and to facilitate osteogenic differentiation of mesenchymal stem cells to produce new dental tissues. Although mineral trioxide aggregate (MTA) has been the material of choice for clot protection, it is easily displaced into the clot during condensation. The present study evaluated the effects of recently introduced calcium silicate cements (Biodentine and TheraCal LC) on the viability and osteogenic differentiation of human dental pulp stem cells (hDPSCs) by comparing with MTA Angelus.

METHODS

Cell viability was assessed using XTT assay and flow cytometry. The osteogenic potential of hDPSCs exposed to calcium silicate cements was examined using qRT-PCR for osteogenic gene expressions, alkaline phosphatase enzyme activity, Alizarin red S staining and transmission electron microscopy of extracellular calcium deposits. Parametric statistical methods were employed for analyses of significant difference among groups, with α=0.05.

RESULTS

The cytotoxic effects of Biodentine and TheraCal LC on hDPSCs were time- and concentration-dependent. Osteogenic differentiation of hDPSCs was enhanced after exposure to Biodentine that was depleted of its cytotoxic components. This effect was less readily observed in hDPSCs exposed to TheraCal LC, although both cements supported extracellular mineralization better than the positive control (zinc oxide-eugenol-based cement).

SIGNIFICANCE

A favorable tissue response is anticipated to occur with the use of Biodentine as a blood clot-protecting material for pulpal revascularization. Further investigations with the use of in vivo animal models are required to validate the potential adverse biological effects of TheraCal LC on hDPSCs.

Influence of periodontal ligament simulation on bond strength and fracture resistance of roots restored with fiber posts

Objective

Considering that periodontal ligament simulation may influence the stress distribution over teeth restored with intraradicular retainers, this study aimed to assess the combined effect of mechanical cycling and periodontal ligament simulation on both the bond strength between fiber posts and root dentin and the fracture resistance of teeth restored using glass fiber posts.

Material and Methods

Ninety roots were randomly distributed into 3 groups (n=10) (C-MC: control; P-MC: polyether; AS-MC: addition silicone) to test bond strength and 6 groups (n=10) (C: control; P: polyether; AS: addition silicone, without mechanical cycling, and C-MC, P-MC and AS-MC with mechanical cycling) to test fracture strength, according to the material used to simulate the periodontal ligament. For the bond strength test, fiber posts were cemented, cores were built, mechanical cycling was applied (2×106 cycles, 88 N, 2.2 Hz, and 45º incline), and the teeth cut into 3 slices (2 mm), which were then subjected to the push-out test at 1 mm/min. For the fracture strength test, fiber posts were cemented, cores were built, and half of the groups received mechanical cycling, followed by the compressive strength (45° to the long axis and 1 mm/min) performed on all groups.

Results

Periodontal ligament simulation did not affect the bond strength (p=0.244) between post and dentin. Simulation of periodontal ligament (p=0.153) and application of mechanical cycling (p=0.97) did not affect fracture resistance.

Conclusions

The materials used to simulate the periodontal ligament did not affect fracture or bond strength, therefore periodontal ligament simulation using the tested materials could be considered optional in the conditions of the study.