Dentinal Walls Research Articles

The investigation of endodontic irrigants and polyhexanide-based solution action on smear layer

AIM. The effect of irrigants on the smear layer on the intracanalicular dentin surface is one of the important issues in endodontics. The objective of this article is to determine the effect of different concentrations of polyhexanide-based solutions and standard irrigants on the smear layer using scanning electron microscopy (SEM).MATERIALS AND METHODS. The present study was conducted on 42 extracted teeth (third molars, first and second premolars) with formed apices that had been extracted for orthodontic indications. The teeth were decoronated and samples were prepared. In order to create a smear layer, the lumen of the canals was instrumented with H-file #40 throughout. A simulation of root canal irrigation was conducted by immersing the specimens in a 5-ml container filled with the proper solution for 1 hour: group 1 – no treatment (n = 6); group 2 – saline (n = 6); group 3 – 2% chlorhexidine (n = 6); group 4 – 3% sodium hypochlorite (n = 6); group 5 – 17% EDTA; group 6 – polyhexanide 0.1% (n = 6); group 7 – polyhexanide 0.2% (n = 6). A ~30 nm thick platinum film was sputtered onto the surface of each sample using a magnetron deposition technique. SEM microphotos were acquired on a Vega3 TESCAN scanning electron microscope (SEM) with an SE secondary electron detector, which enables imaging with high topographic contrast. The initial detector (incamera) was employed for image acquisition, with an electron energy of 30 keV. Images were acquired at magnifications of x20 (overview image), x150, x250, x500, x1000, x2500, x7500 for each sample.RESULTS. The samples from groups 1 and 5 demonstrated the absence of a smear layer on the dentin surface and the absence of smear plugs in the dentinal tubules. Groups 2 and 3 are distinguished by the deposition of a pronounced amorphous smear layer and the obturation of all dentinal tubules. Groups 4, 6, and 7 are distinguished by the deposition of a smaller volume of smear layer on the dentin surface, as well as the presence of semi-open or completely open entrances to the dentinal tubules.CONCLUSION. The data obtained indicates that antiseptic compositions based on polyhexanide in concentrations of 0.1 and 0.2% do not have a pronounced effect on the smear layer. However, in visual evaluation of SEM micrographs, their effect is comparable to that of 3% sodium hypochlorite. In instances where enhanced dissolution of the smear layer and smear plugs from the tubules is necessary to facilitate decontamination of the wall dentin, the combination of antiseptics with chelate compounds, such as 17% EDTA, may be employed.

Marginal adaptation of customized gutta percha cone with calcium silicate based sealer versus MTA and biodentine apical plugs in simulated immature permanent teeth (an in vitro study)

BackgroundThis study aimed to compare the marginal adaptation of a single customized gutta percha cone with calcium silicate-based sealer versus mineral trioxide aggregate (MTA) and Biodentine apical plugs in simulated immature permanent teeth.MethodsThirty-nine extracted human maxillary anterior teeth were selected, prepared to simulate immature permanent teeth with an apical diameter 1.1 mm, placed in moist foam and divided into three groups. Group 1: Obturation with a single customized gutta percha cone and calcium silicate sealer. Group 2: MTA apical plug. Group 3: Biodentine apical plug. After incubation, teeth were horizontally sectioned at 1 mm and 3 mm from the apex and marginal adaptation was evaluated using scanning electron microscope (SEM).ResultsBiodentine showed the least mean gap size at both 1 and 3 mm from the apex with no statistically significant differences compared to MTA (p > 0.05). The single customized cone with calcium silicate based sealer showed the greatest mean gap size at both 1 and 3 mm from the apex with a statistically significant difference compared to the other groups (p < 0.001).ConclusionBiodentine and MTA apical plugs provide a significantly better marginal adaptation to the dentinal walls than a single customized gutta percha cone with calcium silicate based sealer in simulated immature permanent teeth.

Comparative Evaluation of Dentinal Microcrack Formation During Root Canal Preparation Using Different Rotary Files: An In Vitro Study

Background:The success of endodontic treatment depends on completely removing all vital and necrotic pulp tissue, microorganisms, and microbial toxins from the root canal. During the cleaning and shaping process, the canal is shaped through the interaction between instruments and the dentin walls. These interactions can create several temporary stress points within the dentin, which may lead to the development of dentinal defects, craze lines, or microcracks. As a result, the techniques employed for shaping root canals carry the risk of starting crack formation, which, under functional pressure, could progress into complete fractures. This study was aimed to compare and evaluate the incidence of dentinal microcrack formation during root canal preparation using ProTaper Universal, ProTaper Gold, NeoEndo Flex and Hyflex EDM files. Materials and Methods: A total of 95 freshly extracted single rooted premolars with single straight canal were selected and stored in normal saline. Each specimen was examined using dental operating microscope to exclude cracked samples. Specimens then decoronated using a diamond disc and water as a coolant to a standardized length of 14 mm. Canal patency was determined by passing 10 K file passively and the working length was established 1 mm short of the file length at which the file become visible at the apical foramen. Canal was then enlarged upto15 k size file. Teeth samples were then divided into 5 groups having 19 teeth each. Group 1: Control Group (Uninstrumented teeth), Group 2 : Protaper Universal, Group 3 : Protaper Gold, Group 4 : NeoEndo Flex ,Group 5 : Hyflex EDM. After completion of cleaning and shaping procedure (to a standard apical diameter of 25), canal was rinsed with distilled water. Root was then horizontally sectioned at 3 mm, 6 mm and 9 mm from the apex with diamond disc at low speed under water cooling. All the sections were evaluated under stereomicroscope for presence of cracks and images were recorded. Cracks were observed as lines extending from the root canal lumen to the dentin or from the outer surface into the dentin. Results: All the file systems used in this study showed dentinal microcracks. ProTaper Universal exhibited the highest percentage of dentinal defects, while Hyflex EDM displayed the lowest among the file systems used (ProTaper Universal, ProTaper Gold, NeoEndo Flex and Hyflex EDM). The defects were present more in the apical third (3 mm) as compared to 6 mm (middle third) and 9 mm (coronal third) sections

A Comparative Evaluation of the Effect of Different Endodontic Irrigating Solutions on Microhardness of Root Canal Dentin: An in vitro Study.

During endodontic therapy, irrigation solutions applied in the root canal may affect the physicochemical properties of the dentinal wall, thereby changing its microhardness. This may adversely affect the sealing ability and adhesion of dental materials. Therefore, many studies have focused on the search for an ideal root canal irrigant that has a minimal effect on dentinal microhardness. This in vitro study was conducted to determine the changes in dentin microhardness after root canal irrigation with different endodontic irrigants. Ninety-five freshly extracted maxillary central incisor teeth with straight single canals were selected. These teeth were sectioned transversely at the level of the cementoenamel junction. The working length of each tooth was determined, and canal space was prepared by the HyFlex CM rotary file system. During instrumentation, normal saline was used for irrigation. Then, teeth were split longitudinally into two segments. According to the irrigating solution employed, samples were divided into five groups (n=19): normal saline (Group A), 3% sodium hypochlorite (Group B), 2% chlorhexidine (Group C), 5% calcium hypochlorite (Group D), and 0.2% nanochitosan (Group E).3 mL of the corresponding irrigating solution was administered for total15 minutes in each prepared sample. The Vickers micro-hardness tester was then used to assess micro-hardness. The data was analyzed using one-way analysis of variance (ANOVA). All tested irrigating solutions decreased the dentinal microhardness. Samples irrigated with 5% calcium hypochlorite demonstrated dentinal microhardness of 42.43±1.62, which is the lowest among all the tested groups, followed by nano chitosan, sodium hypochlorite, and chlorhexidine. Samples treated with control group (saline) demonstrated the maximum microhardness of dentin in the present study. Within the limitations of this research, it can be concluded that the tested novel irrigating solutions, 5% calcium hypochlorite and 0.2% nanochitosan, were more detrimental to radicular dentin microhardness when compared with conventional endodontic irrigants.

Glide Path in Endodontics: A Literature Review of Current Knowledge.

The introduction of nickel-titanium rotary instruments revolutionized shaping procedures as they were able to produce a well-tapered preparation while reducing operator fatigue. The major drawback of rotary instruments was the high risk of fracture due to bending and torsional stress. Thus, the creation of a glide path has been advocated and recommended by most rotary instrument manufacturers. The aim of the present review is to summarize existing knowledge on glide path preparation and identify areas where further research is needed. The primary goal is to provide a comprehensive overview of the techniques and instruments used in glide path preparation, highlighting their advantages and limitations. The secondary goal is to explore the effect of glide path creation on the overall success of endodontic treatment, particularly in terms of reducing procedural errors and improving treatment outcomes. An online search on PubMed, ScienceDirect, UCLA, and Scopus databases was conducted, and 116 articles were identified. Eligible articles were divided into nine categories based on what they researched and compared. The categories included centering ability and/or root canal transportation, cyclic fatigue resistance, glide path and shaping time, tortional stress resistance, apical extrusion of debris and/or bacteria, defects in dentine walls, file separation, postoperative pain assessment, and scouting ability and performance. Establishing a glide path reduces root canal transportation, especially with rotary methods. Reciprocating and heat-treated files offer higher fatigue resistance and shorter preparation time. Instruments with shorter pitch lengths have greater torsional strength. Preparation and coronal preflaring reduce apical debris and bacteria. Glide paths do not affect dentine microcracks, file separation, or defects but reduce immediate postoperative pain and improve cutting ability. Randomized trials are needed to assess their impact on treatment outcomes.

Microhardness and energy dispersive X-ray evaluation of dentinal walls following chemical and electrochemical dissolution of fractured nickel-titanium file: An in vitro study

PurposeChemical dissolution of nickel-titanium (NiTi) files involves the application of a fluoride solution in direct contact with a damaged instrument, whereas electrochemical dissolution involves the application of an electrical current to the electrolyte, which accelerates fragment dissolution. This study aimed to determine the hardness and concentration of calcium and phosphorus (Ca and P) ions in dentinal walls following chemical and electrochemical dissolution of fractured ProTaper F2 files with a novel chemical solution.Materials & Methods: Thirty human maxillary first molar palatal roots with fractured ProTaper F2 files in the middle third (length, 2.5 mm were divided into three groups according to the treatment techniques used with a novel solution (NaF 12 g/L + NaCl2 60 g/L + MgCl2 60 g/L + CaCl2 60 g/L) at pH 5: Group 1: distilled water (control group), Group 2: electrochemical dissolution, and Group 3: chemical dissolution using the novel solution. The novel solution was placed for 10 min using an electrochemical technique, and for 30 min in contact with the separated instrument in the chemical group. The Vickers microhardness test was performed in three areas: at 3, 6, and 9 mm from the apex, and an energy-dispersive X-ray test for both Ca and P ions was performed. The analysis of variance (ANOVA) and Tukey's tests were used for statistical analysis. ResultsAccording to the one-way ANOVA analysis, no difference was observed between the tested approaches (P > 0.05) in the three areas evaluated (3, 6, and 9 mm), with no difference in the Ca/P ratio between the tested groups. ConclusionCompared to the control group, the use of chemical and electrochemical dissolution methods with the novel solution did not affect dentin hardness or dentinal structure in terms of the Ca/P ratio, thereby indicating promising results while saving time.

A review of tissue engineering in regenerative endodontic treatment

Background: Regenerative endodontic treatments are classified based on approach in the procedures and principles. One is cell-free approach that involves a revitalization procedure to achieve continued root growth while the other is cell-based approach which involves pulp/dentin regeneration through isolation and ex vivo expansion of stem cells seeded in the scaffold and then transplanted into the canal space. Technically, the cell-free approach is simpler than cell-based approach because the former does not concern about external stem cell isolation and culture. Currently, the gold standard and the one that has been clinically performed is cell-free approach. Cell-based approach is still not a standard because currently the cell-based approach is still in the clinical trial stage. Purpose: to evaluate the biological basis and clinical protocols recently used in regenerative endodontic treatment and discuss potentially future treatment approaches. Review: The literature review was searched in PUBMED with the keywords: immature permanent teeth, pulp revascularization, stem cells and regenerative endodontics. The regenerative endodontic treatments with various procedures and techniques result in a significant increase in root length and dentinal wall thickness. Stimulation of stem cells in apical root canal system is required to induce tissue formation and continued root maturation. Conclusion: The success of regenerative endodontic therapy relies on the development of a technique that enables clinicians to create functional pulp tissue within cleaned and shaped root canal systems. It is hoped that further research studies are required to define advantages and limitations of cell-free and cell-based approach.

Regenerative endodontic treatment and traumatic dental injuries.

Pulp necrosis is the most common complication following dental trauma and is often associated with apical periodontitis. The management of these teeth is challenging in terms of large root canals, open apices, thin dentinal walls, and short roots. Over decades the conventional treatment for these teeth was calcium hydroxide apexification, a time-consuming procedure despite high success rates. Subsequently after the introduction of mineral trioxide aggregate and hydraulic calcium silicate materials single visit apical plug procedures became increasingly practiced with comparable success rates to the conventional apexification. The search continued afterward for a clinical procedure that may stimulate further root development and apical closure to avoid the long-term complication of root fracture after apexification. Regenerative procedures using stem cells derived from the apical papilla and blood clots as scaffolds were then introduced for the management of immature teeth, with variable protocols and success rates. This review will cover the evidence available and current position of regenerative endodontic procedures in traumatized immature teeth with apical periodontitis, in terms of clinical protocols, outcome, and potential prognostic factors.

Comparison of Various Irrigation Techniques for the Removal of Silicone Oil-Based Calcium Hydroxide Intracanal Medicament from the Apical Third: An SEM Study

Abstract Objective To evaluate the efficacy of various irrigants (5.25% sodium hypochlorite [NaOCl] followed by 17% ethylenediaminetetraacetic acid [EDTA] and 0.2% chitosan nanoparticle [NP]) and different irrigation techniques (conventional and EndoVac) for the removal of Metapex from the apical third of the root canal by scanning electron microscopy (SEM) analysis. Materials and Methods Forty extracted single-rooted human premolars were instrumented using a rotary ProTaper file system up to F3. The canals were dried and Metapex was placed inside the root canal. The access cavity was sealed with a cotton pellet and Cavit followed by the storage of specimens at 37°C at 100% humidity for 1 week. Cavit was removed and the samples were divided into: Group 1 (conventional irrigation using 5.25% NaOCl and 17% EDTA, n = 10), Group 2 (conventional irrigation using 0.2% chitosan NP, n = 10), Group 3 (EndoVac using 5.25% NaOCl and 17% EDTA, n = 10), and Group 4 (EndoVac using 0.2% chitosan NP, n = 10). After irrigant activation, the roots were divided in half, and the apical third of one-half of each tooth was subjected to SEM analysis. A five-graded scoring scale was used to evaluate dentinal wall cleanliness. Data were statistically analyzed using one-way analysis of variance. Results There were statistically significant differences in mean canal cleanliness scores observed between the four groups. Chitosan NPs showed lower mean canal cleanliness scores at the apical one-third of the root canal indicating better cleanliness when compared with the other irrigants and techniques. Conclusion None of the irrigation techniques was successful in entirely removing the calcium hydroxide intracanal medicament from the apical third.

Effect of herbal irrigants on surface roughness of intraradicular dentin using quantitative method of 3D surface texture analysis

Replacing the conventional endodontic irrigants with herbal agents could avoid complications associated with using sodium hypochlorite (NaOCl). Endodontic irrigants alter the surface roughness of the dentinal wall surface, which affects sealer mechanical retention. This study aimed to assess the effect of experimental herbal Moringa oleifera and orange peel extract irrigant on intraradicular dentin (IRD) surface roughness using quantitative 3D surface analysis by scanning electron microscopy (SEM) regarding the smear layer assessment. Sixty human root sections were divided into four groups (n = 15): NaOCl combined with 17% ethylenediaminetetraacetic acid (EDTA); negative control (saline); moringa extract (MO); and orange oil (OO). SEM images were assessed quantitatively for surface roughness (Ra) in the coronal, middle, and apical IRD. The data were analysed by Kruskal–Wallis, Friedman, and Dunn’s tests. All groups showed statistically significant differences (P = 0.007). MO exhibited significantly greater Ra values at the coronal, middle, and apical root levels than OO (P = 0.007, 0.009, and 0.046, respectively). There was no significant change in Ra values at various root levels within each group at P = 0.091, 0.819, 0.819, and 0.549 for the EDTA, saline, MO, and OO groups. Considerable (IRD) surface roughness analysis makes Moringa extract a promising herbal endodontic irrigant alternative to the NaOCl plus EDTA regimen.

Nanostructured ZnO thin film to enhance gutta-percha’s adhesion to endodontic sealers

BackgroundGutta-percha (GP) combined with an endodontic sealer is still the core material most widely used for tridimensional obturation. The sealer acts as a bonding agent between the GP and the root dentinal walls. However, one of the main drawbacks of GP core material is the lack of adhesiveness to the sealer. ZnO thin films have many remarkable features due to their considerable bond strength, good optical quality, and excellent piezoelectric, antibacterial, and antifungal properties, offering many potential applications in various fields. This study aimed to explore the influence of GP surface’s functionalization with a nanostructured ZnO thin film on its adhesiveness to endodontic sealers.MethodsConventional GP samples were divided randomly into three groups: (a) Untreated GP (control); (b) GP treated with argon plasma (PT); (c) Functionalized GP (PT followed by ZnO thin film deposition). GP’s surface functionalization encompassed a multi-step process. First, a low-pressure argon PT was applied to modify the GP surface, followed by a ZnO thin film deposition via magnetron sputtering. The surface morphology was assessed using SEM and water contact angle analysis. Further comprehensive testing included tensile bond strength assessment evaluating Endoresin and AH Plus Bioceramic sealers’ adhesion to GP. ANOVA procedures were used for data statistical analysis.ResultsThe ZnO thin film reproduced the underlying surface topography produced by PT. ZnO thin film deposition decreased the water contact angle compared to the control (p < 0.001). Endoresin showed a statistically higher mean bond strength value than AH Plus Bioceramic (p < 0.001). There was a statistically significant difference between the control and the ZnO-functionalized GP (p = 0.006), with the latter presenting the highest mean bond strength value.ConclusionsThe deposition of a nanostructured ZnO thin film on GP surface induced a shift towards hydrophilicity and an increased GP’s adhesion to Endoresin and AH Bioceramic sealers.

Non-surgical management of simultaneous occurrence of internal root resorption and calcific metamorphosis: A case report

Internal resorption and calcific metamorphosis are two sequelae of pulpal necrosis after traumatic injuries like concussion and luxation injuries. After traumatic injury, the pulp may become completely necrosed followed by calcification of the entire root canal by the activity of odontoblastic cells. In some other cases, partial necrosis of the pulp tissue with overstimulation of odontoclastic cells and resorption of the root canal dentinal walls may happened. Commonly any of the cells become active and one of the sequelae may will continue. Rarely these two conditions will happen together. In this particular case report with simultaneous occurrence of these two conditions with symptomatic periapical abscess.

An innovative cell-based transplantation therapy for an immature permanent tooth in an adult: a case report

BackgroundImmature teeth with necrotic pulps present multiple challenges to clinicians. In such cases, regenerative endodontic procedures (REPs) may be a favorable strategy. Cells, biomaterial scaffolds, and signaling molecules are three key elements of REPs. Autologous human dental pulp cells (hDPCs) play an important role in pulp regeneration. In addition, autologous platelet concentrates (APCs) have recently been demonstrated as effective biomaterial scaffolds in regenerative dentistry, whereas the latest generation of APCs—concentrated growth factor (CGF), especially liquid phase CGF (LPCGF)—has rarely been reported in REPs.Case presentationA 31-year-old woman presented to our clinic with the chief complaint of occlusion discomfort in the left mandibular posterior region for the past 5 years. Tooth #35 showed no pulp vitality and had a periodontal lesion, and radiographic examination revealed that the tooth exhibited extensive periapical radiolucency with an immature apex and thin dentin walls. REP was implemented via transplantation of autologous hDPCs with the aid of LPCGF. The periodontal lesion was managed with simultaneous periodontal surgery. After the treatment, the tooth was free of any clinical symptoms and showed positive results in thermal and electric pulp tests at 6- and 12-month follow-ups. At 12-month follow-up, radiographic evidence and three-dimensional models, which were reconstructed using Mimics software based on cone-beam computed tomography, synergistically confirmed bone augmentation and continued root development, indicating complete disappearance of the periapical radiolucency, slight lengthening of the root, evident thickening of the canal walls, and closure of the apex.ConclusionhDPCs combined with LPCGF represents an innovative and effective strategy for cell-based regenerative endodontics.

Role of Platelet Concentrates in Dental-Pulp Regeneration: A Systematic Review of Randomized Clinical Trials.

Treatment of immature necrotic teeth is a problematic situation. Conventional root canal therapy is challenging and leaves a weak, fragile, and undeveloped tooth for lifetime. This review was aimed to assess the outcome of available randomized clinical trials (RCTs) on the efficacy of platelet concentrates (PC) in dentine-pulp complex regeneration. In this systematic review, an electronic search was conducted on MEDLINE, EMBASE, Cochrane, and Google scholar databases. A further manual search was performed on the list of related articles in order to ensure inclusion of potentially missed articles in earlier electronic search. Those proved RCTs matched with the standard criteria were included following an initial assessment of abstracts and the text independently by the reviewers. From the total 602 harvested articles, only 13 met the criteria and were evaluated with 11 having parallel design and 2 split mouth. Only one study featured low risk of bias, while three had moderate risk and the rest were at high risk of bias. Six studies had used platelet rich plasma (PRP), 4 employed platelet rich fibrin (PRF), one utilized injectable platelet rich fibrin (I-PRF), and three used both PRF and PRP for their experimental groups while blood clot (BC) was used as the control group for all. The success rate was reported at 87.3% judged by the absence of pathologic signs and symptoms. Dentin wall thickening, root lengthening and apex closure were higher in PC groups, however, these differences were not statistically significant in reported studies. It can be concluded that PCs promote the pulp tissue revitalization and continuation of root development. However, a consensus on its potency for true pulp regeneration is yet to be reached.

Shaping ability of three instrumentation system in moderately curved canals: A micro-CT study.

This study aims to compare the shaping ability of three systems using micro-computed tomography (micro-CT). Moderately-curved mesial canals of 36 mandibular molars were assigned to three groups (n = 24); Protaper Next (PTN, 0.25, 0.06), WaveOne Gold (WOG, 0.25, 0.07), TruNatomy (TRN, 0.25, 0.04), and instrumentation was performed. Pre- and post-micro-CT scans were obtained. Canal volume and surface, structure model index (SMI), centroid shift, canal transportation, and untouched canal were analyzed. One-way ANOVA and Student's t-test were used for statistics. There was no difference in SMI, centroid shift, and centering ability between the study groups (p > .05). Removed dentin and canal surface changes were lower in TRN, while untouched dentin walls were higher (p < .05). Cross-sections became more rounded (p < .05), but not significant between groups (p > .05). Considering the removed dentin by TRN, it can be used in critical dentin thickness, such as the danger zone (DZ). PTN, WOG, and WOG kept the original canal course similarly. Untouched dentin by TRN (41%) was wider than PTN and WOG, consequently, meticulous irrigation is recommended. TRN, which provides a controlled increase in canal volume, can be used in thin dentin such as the DZ, however, its use should be supported by copious irrigation and brushing considering the rate of untouched dentin walls. RESEARCH HIGHLIGHTS: TRN presented a higher untouched dentin wall compared to PTN and WOG. Canal volume and surface changes were the lowest in the TRN group. The centering abilities were similar in PTN, WOG, and TRN.

Impact of using XP-endo finisher and nanobubble water during EDTA dentin conditioning on TGF-β1 release in regenerative endodontic procedures.

Transforming Growth Factor-Beta 1 (TGF-β1) plays a crucial role in the success of Regenerative Endodontic Procedures (REPs) as they directly impact the proliferation and differentiation of stem cells. TGF-β1 is released by conditioning of the dentin matrix using 17% EDTA. EDTA was found to have deleterious effects on dentin especially in immature teeth with fragile dentin walls. Decreasing the irrigation time was reported to decrease these effects. Accordingly, enhancement and activation of the EDTA solution to maintain its efficiency in TGF-β1 release from dentin and thus compensating the reduction in irrigation time was employed. EDTA solution was enhanced by adding Nanobubble (NB) water which contains oxygen filled cavities less than 200nm in diameter. Additionally, EDTA was activated with XP-endo Finisher rotary file. The aim of this study was to assess the impact of NB enhancement and/or XP-endo Finisher activation of the EDTA solution on the TGF-β1 release from dentin. Fifty standardized root segments with open apex were allocated to two main groups according to whether EDTA was enhanced with NB water or not, and within each group whether XP-endo Finisher activation was used or not in addition to a Negative Control group. The concentration of the released TGF-β1 in the root canal was measured using enzyme-linked immunosorbent assay (ELISA). The statistical analysis was done using the Shapiro- Wilk, Kolmogorov Smirnov, ANOVA and Post-hoc Tukey tests. All groups released a considerable amount of TGF-β1 with the highest values in the EDTA/NB/XP group, followed by EDTA/NB, EDTA/DW/XP, EDTA/DW and Negative Control groups respectively. The results of this study suggest that NBs can promote the success of REPs since it revealed a significant increase in the TGF-β1 release following its use in the enhancement of the EDTA solution. A comparable effect was obtained by XP-endo finisher activation of the EDTA solution. The combined use of NBs and XP-endo Finisher can be a promising addition in REPs. Accordingly, Enhancement and activation of the EDTA solution may compensate decreasing the EDTA irrigation time attempted to avoid the deleterious effect of EDTA on dentin.

Evaluation of Outcomes in Immature Teeth After Revitalization or Apexification Procedures: A Systematic Review and Meta-Analysis.

There are two main treatment options for immature teeth with necrotic pulp and apical periodontitis. Apexification creates a mineralized tissue barrier, while revitalization aims to regenerate vital tissue in the canal space. There is no conclusive evidence to determine the most effective procedure regarding root length and dentin wall thickness. The objective of this systematic review was to compare the outcomes of revitalization and apexification procedures in immature non-vital teeth in terms of root length and dentin wall thickness. A literature search was conducted using the PubMed, ScienceDirect, Google Scholar, and Embase databases. Articles relevant to the study topic were gathered according to the selection criteria, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The included studies had to be published in English, conducted over a six-year period, and compared the outcomes of revitalization and apexification procedures in immature non-vital teeth. Data were collected using appropriate keywords from the eligible studies. Six articles were included for qualitative and quantitative analysis. The eligible studies showed a low risk of bias. In all revitalization cases, the root length increased significantly (mean difference (MD) (%) = 5.91; 95% confidence interval (CI) = 2.39-9.43; p = 0.0010; MD (mm) = 2.43; 95% CI = 2.05-2.80; p < 0.00001). The dentin wall thickness was statistically significant in most cases (MD (%) = 10.94; 95% CI = 7.01-14.88; p < 0.00001), MD (mm) = 0.16; 95% CI = 0.07-0.25; p = 0.0007). The systematic review and meta-analysis showed both procedures to be credible treatment options for necrotic immature teeth. Apexification had a positive impact, to some extent, on the development of root length. Revitalization yielded a significantly greater increase in root length and root dentin wall thickness and appeared to be superior in promoting root development.

Biomechanical impact of different isthmus positions in mandibular first molar root canals: a finite element analysis.

This study used image-based finite element analysis (FEA) to assess the biomechanical changes in mandibular first molars resulting from alterations in the position of the root canal isthmus. A healthy mandibular first molar, characterized by two intact root canals and a cavity-free surface, was selected as the subject. A three-dimensional model for the molar was established using scanned images of the patient's mandibular teeth. Subsequently, four distinct finite element models were created, each representing varied root canal morphologies: non-isthmus (Group A), isthmus located at the upper 1/3 of the root (Group B), middle 1/3 of the root (Group C), and lower 1/3 of the root (Group D). A static load of 200 N was applied along the tooth's longitudinal axis on the occlusal surface to simulate regular chewing forces. The biomechanical assessment was conducted regarding the mechanical stress profile within the root dentin. The equivalent stress (Von Mises stress) was used to assess the biomechanical features of mandibular teeth under mechanical loading. In Group A (without an isthmus), the maximum stress was 22.2MPa, while experimental groups with an isthmus exhibited higher stresses, reaching up to 29.4MPa. All maximum stresses were concentrated near the apical foramen. The presence of the isthmus modified the stress distribution in the dentin wall of the tooth canal. Notably, dentin stresses at specific locations demonstrated differences: at 8mm from the root tip, Group B: 13.6MPa vs. Group A: 11.4MPa; at 3mm from the root tip, Group C: 14.2MPa vs. Group A: 4.5MPa; at 1mm from the root tip, Group D: 25.1MPa vs. Group A: 10.3MPa. The maximum stress in the root canal dentin within the isthmus region was located either at the top or bottom of the isthmus. A root canal isthmus modifies the stress profile within the dentin. The maximum stress occurs near the apical foramen and significantly increases when the isthmus is located closer to the apical foramina.

The Safety of Removing Fractured Nickel-Titanium Files in Root Canals Using a Nd: YAP Laser.

The fracture of nickel-titanium (Ni-Ti) instruments during root canal instrumentation leads to compromised outcomes in endodontic treatments. Despite the significant impact of instrument facture during a root canal treatment, there is still no universally accepted method to address this complication. Several previous studies have shown the ability of a Neodymium: Yttrium-Aluminum-Perovskite (Nd: YAP) laser to cut endodontic files. This study aims to determine safe irradiation conditions for a clinical procedure involving the use of a Neodymium: Yttrium-Aluminum-Perovskite (Nd: YAP) laser for removing fractured nickel-titanium files in root canals. A total of 54 extracted permanent human teeth (n = 54) were used. This study involved nine distinct groups, each employing different irradiation conditions. Groups 1 s, 3 s, 5 s, 10 s, and 15 s simply consist of irradiation for 1, 3, 5, 10, and 15 s, respectively. After identifying the longest and safest duration time, four additional groups were proposed (labeled A, B, C, and D). Group A was composed of three series of irradiations of 5 s each separated by a rest time of 30 s (L5s + 30 s RT). Group B consisted of three series of irradiations of 5 s each separated by a rest time of 60 s (L5s + 60 s RT). Group C consisted of two series of irradiations of 5 s each separated by a rest time of 30 s (L5s + 30 s RT), and group D consisted of two series of irradiations of 5 s each separated by a rest time of 5 s (L5s + 5 s RT). In all groups, during the rest time, continuous irrigation with 2.5 mL of sodium hypochlorite (3% NaOCl) was carried out. The variation in temperature during irradiation was registered with a thermocouple during irradiation with different protocols. The mean and standard deviation of the temperature increase was noted. The calculation of the temperature was made as the Δ of the highest recorded temperature at the root surface minus (-) that recorded at baseline (37°). Additionally, scanning electron microscopy (SEM) was used after irradiation in all groups in order to assess the morphological changes in the root dentinal walls. The Nd: YAP laser irradiation parameters were a power of 3W, an energy of 300 mJ per pulse, a fiber diameter of 200 µm, a pulsed mode of irradiation with a frequency of 10 Hz, a pulse duration of 150 µs, and an energy density of 955.41 J/cm2. Our results show that the safest protocol for bypassing and/or removing broken instruments involves three series of irradiation of 5 s each with a rest time of 30 s between each series. Furthermore, our results suggest that continuous irradiation for 10 s or more may be harmful for periodontal tissue.

Influence of pretreating radicular dentin with different polyacrylic acids and isopropanol on the retention of posts

The optimal pretreatment of radicular dentin before cementing a post with glass ionomer cement is unclear. The purpose of this in vitro study was to evaluate the retention of prefabricated tapered titanium posts to endodontically treated teeth after applying different pretreatment protocols on the radicular dentin. The coronal part of 32 single-rooted human teeth was removed 1-mm coronally to the cemento-enamel junction. All specimens received endodontic treatment, and the root canals were prepared with an instrument to a depth of 10mm to receive a titanium post. The dentin walls of each specimen were roughened with a hand-held diamond cutting instrument. The specimens were randomly divided according to the surface treatments into 4 groups (n=8): KW: etched with 20% to 30% polyacrylic acid (PAA) (Ketac Conditioner) and rinsed with water; KWI: etched with 20% to 30% PAA, rinsed with water and 70% isopropanol; DW: etched with 30% to 50% PAA (Durelon Liquid) and rinsed with water; DWI: etched with 30% to 50% PAA, rinsed with water and 70% isopropanol. The prefabricated titanium posts were airborne-particle abraded and cemented with glass ionomer cement. The specimens were fixed in custom-made brass cylindrical holders with autopolymerizing acrylic resin with the holder parallel to the long axis of the post. All specimens were stored in water for 3 days at 37°C. Retention was evaluated using a tensile test with a universal testing machine (Zwick Z010) at a crosshead speed of 2mm/min. Data were statistically analyzed with a 1-way ANOVA, followed by the Tukey post hoc test for pairwise comparisons between groups (α=.05). Mean ±standard deviation retention values ranged from 201.8 ±55.5N (KW) to 328.1 ±70.9N (DWI). Groups DWI and KWI (316 ±58.3N) showed statistically higher retention values than group KW (P<.05) but did not significantly differ from retention values obtained in group DW (P>.05). An additional final rinse with isopropanol after using PAA increased the retention of the post significantly for all groups. Although group DWI achieved the highest retention values, pretreatment of radicular dentin as in group KWI may also be considered.