Thermoplastic Techniques Research Articles

Management Open Apex Using Bioceramic Root Repair Material : A Case Report of Permanent Anterior Teeth

Background: Trauma to immature teeth can cause disrupt of the blood vessel supply in the pulp which leads to pulp necrosis. This can then, indirectly disrupts of root formation and incomplete apex closure.4,5 Young permanent teeth with wide open apex to be a challenge for root canal treatment, especially during obturation. Apexification is a treatment option for open apex with necrotic pulp. The purpose is to create an apical stop at the apical third of the apex so that obturation can be achieved. Case: A 27-year-old man came to RSKGMP UNAIR with chief complaints that his upper front teeth were fracture and discolored and the pain had disappeared since march 2023. From the clinical examination, tooth 21 showed Ellis fracture class III and there was tooth discoloration. Pulp vitality examination with cavity test and unresponsive k-file test, percussion (+) and bite test (+). Radiographic examination show an exposed pulp and exposed apex of tooth 21 accompanied by an unclearly defined radiolucent image at the apex of tooth 21. The diagnosis of this tooth was pulp necrosis with symptomatic apical periodontitis. Treatment: Apexification use bioceramic root repair material as apical plug at the apex. After that, obturation is achieved using a thermoplastic technique. Final restoration with individual customized post and lithium disilicate crown. Conclusion: Apexification is an option in cases of pulp necrosis with an open apex using bioceramic root repair material. Bioceramic root repair material is a bioactive material, that induces osteogenesis, is easier to apply, has faster setting time, biocompatible, hydrophilic, high pH and has anti-microbial properties.

New Ultrasonic Tip for Root Canal Filling of the Mesial Canals of Mandibular Molars with Isthmus: A Laboratory Evaluation Using Computed Microtomography

IntroductionThe obturation quality of the mandibular molar mesial canals and isthmuses with two thermoplastic techniques, ultrasonic vertical condensation (UVC) and continuous wave of condensation (CWC), was evaluated using computed microtomography (μCT). MethodsThirty-six human mandibular molars had been previously scanned and analyzed using μCT for mesial roots with morphologically similar isthmuses for this study. Coronal access and confirmation of foraminal patency were performed, and the actual length of the teeth was established using a clinical microscope (40X magnification). The canals were prepared using ProTaper Gold instruments up to #F3, with 2.5% sodium hypochlorite as the irrigant solution, followed by a passive ultrasonic irrigation protocol. The specimens were randomly divided into the UVC and CWC groups based on the obturation technique to be used. Obturation was performed with #F3 gutta-percha cones cemented using AH Plus Jet sealer. The μCT scans were performed after 15 days, and the images were evaluated by a calibrated examiner blinded to the experimental groups to determine the filling rate of the entire canal area, including the main canal and isthmus. Student's t-test was used for statistical analysis; P values ≤0.05 were considered significant. ResultsNeither of the thermoplastic obturation techniques achieved complete filling of the canals (86.3% for UVC and 91.4% for CWC), with a statistically significant difference between them (P = .029). Conclusions:Under the conditions of the study, it can be concluded that none of the techniques completely filled the canal/isthmus of the mandibular molars; however, the CWC exhibited better performance.

Quantitative analysis of the obturation of oval-shaped canals using thermoplastic techniques.

One of the aim of root canal treatment is filling the root canals in a 3D way. It is not always possible to achieve due to the existence of anatomical variations. The obturation of oval canal usually provides great difficulties. Its complex anatomy can cause obstacles in instrumentation, irrigation and obturation. Aim: The main aim of this study is to quantify the area filled by gutta-percha, the area filled by cement and the area of voids present in oval canals, treated by thermoplastic filling techniques in comparison with the lateral condensation technique and observe the adaptation of the gutta-percha to the anatomy of the oval root canals according to the obturation technique. 80 mandibular incisors were selected. The teeth were instrumented with Protaper Gold® and divided into 4 groups of 20. Group 1 was filled with Thermafill®; group 2 with GuttaCore®; group 3 with continuous wave vertical condensation and group 4 with the lateral condensation technique. Two horizontal sections were cut at 5mm and 7mm from the apex and they were set in putty silicone. The samples were analyzed with a Leica DMS 1000 digital microscope and processed with Leica Suite for Windows XP. The area of gutta-percha, cement and voids and the percentages, of each one, were calculated. A statistical analysis was performed using the T-Student, ANOVA tests and Kruskal-Wallis tests. All thermoplastic techniques achieved a high percentage of obturation. The percentages of voids in group 4 were the highest. Statistically significant differences were found between thermoplastic techniques compared with lateral condensation. Thermoplastic techniques achieve better adaptation of the gutta-percha in the oval canals and low amount of cement and voids in the middle and coronal thirds respect to the lateral condensation group. Moreover, comparing termoplasthicized techniques among them, continuous wave vertical condensation got the lowest percentage of voids. Key words:Warm gutta-percha, thermoplastic obturation, oval canals, oval-shaped canals.

The effect of printing parameters on tensile properties of thermoplastics prepared by fused deposition modeling (FDM) based additive manufacturing technique

The additive manufacturing technique (AMT) has significantly surpassed the prototype as well as the end engineering application. One of the most widely used AMT techniques for thermoplastics is fused deposition modeling (FDM). In this study, FDM was used to evaluate the mechanical properties of a 3D-printed specimen as a function of raster orientation and layer thickness using thermoplastics such as Nylon 6 (semicrystalline) and ABS (amorphous). The samples were printed with raster orientation angles of 0, 90, +45/-45, and 0/90 degrees with a layer thickness of 0.1, 0.2, 0.3, and 0.4 mm. Modulus of elasticity, ultimate tensile strength, maximum force, and maximum elongation were investigated to determine optimal parameters. The result shows that 90 degree raster orientation and 0.1 mm later thickness gives the highest values of ultimate tensile strength. At higher layer thickness up to 0.4 mm and +45/-45 degree shows the highest ultimate tensile strength. Also, Nylon 6 shows the highest tensile toughness compared to ABS. The work focus on the effect of printing parameters on tensile behaviour of amorphous and crystalline polymers prepared by FDM, which is one of the present global precision manufacturing sector.

In vitro study of the effect of three commercial solvents on gutta-percha cones used for the cold and thermoplastic technique

The sample consisted of 80 gutta-percha cones No. 80 Endomedic and F3 ProTaper Universal. The cones were divided into 4 groups (n = 20) according to the type of solvent, and each one was divided into two subgroups (n = 10) according to the exposure time (5 min and 10 min). The cones were immersed in the respective solvent for 5 or 10 minutes. Then, they were washed with 5 ml of alcohol for 5 minutes and rinsed with water. Finally, after drying at room temperature for one hour, the solvent action was recorded in grams (g) of weight loss. The results were analyzed and compared using Tukey's test (p<0.05). The Endomedic cone exposed for 5 min to eucalyptol obtained the lowest average weight (0.0625 ± 0.0009 g), followed by Lemongrass oil (0.0629 ± 0.0003 g) and orange oil (0.0629 ± 0.0010 g), although not a significant difference (p > 0.05) was found between each one. The experimental solvent of Lemongrass, eucalyptol and orange oil presented a similar solvent effect on the guta-percha cone for cold and thermoplastic technique. At a clinical level, the three solvents studied could be used in endodontic retreatment as alternative solutions with a similar solvent effect.

Progress in Starch-Based Materials for Food Packaging Applications

The food packaging sector generates large volumes of plastic waste due to the high demand for packaged products with a short shelf-life. Biopolymers such as starch-based materials are a promising alternative to non-renewable resins, offering a sustainable and environmentally friendly food packaging alternative for single-use products. This article provides a chronology of the development of starch-based materials for food packaging. Particular emphasis is placed on the challenges faced in processing these materials using conventional processing techniques for thermoplastics and other emerging techniques such as electrospinning and 3D printing. The improvement of the performance of starch-based materials by blending with other biopolymers, use of micro- and nano-sized reinforcements, and chemical modification of starch is discussed. Finally, an overview of recent developments of these materials in smart food packaging is given.

The thermoplastic techniques or single-cone technique on the quality of root canal filling with tricalcium silicate-based sealer: An integrative review.

BackgroundThe filling of the root canal system (RCS) is an important step in endodontic treatment and aims to obtain a three-dimensional sealing of the root canal spaces to prevent bacterial contamination. For this, the selection of an appropriate sealer must be performed synchronously with the choice of the root canal filling technique. This study aims, through an integrative review, to evaluate the quality of root canal filling by comparing thermoplastic and single-cone (SC) techniques. Material and MethodsThe Medline/PubMed, Scopus, Web of Science and Virtual Health Library (VHL) databases were used to find articles published until November 2021. The eligibility criteria comprised articles that evaluating the quality of root canal filling comparing thermoplastic techniques with the SC technique using tricalcium silicate-based sealer. Studies that evaluated primary teeth, endodontic retreatment or perforations, different outcomes, and studies that considered artificial teeth or different sealer and material for obturation of different techniques were excluded. For articles that were not available for access, an additional contact with authors were considered. A total of 1699 articles were found. After duplicate removal, the title and abstract of 828 articles were screened. Sixteen articles were considered for full-text analysis, but only ten articles met the eligibility criteria. Data extracted from the studies were discussed and tabulated to allow the comparison of desired factors. ResultsConcerning the formation of gaps/voids, the thermoplastic techniques showed better results than the SC technique in 3 articles. On the other hand, 2 articles reported no statistical difference between the tested techniques. In addition, about the penetration of tricalcium silicate-based sealer in the dentinal tubules, of the 5 articles selected, in 4 there was no significant difference between the tested techniques and only one study showed better penetration of the sealer when using thermoplastic techniques. ConclusionsThe thermoplastic technique was better in most selected studies regarding gaps and voids, but regarding the penetration of the sealer into the tubules, both techniques were effective. Key words:Root canal filling, thermoplastic techniques, tricalcium silicate.

Ultrasonic thermal welding of immiscible thermoplastics via the third phase

Ultrasonic weld (USW) techniques for thermoplastics are used to be limited identical polymers, which obstruct the increasingly development of dissimilar polymers joining. In this study, as a direct-joining method without using environmentally unfriendly adhesives, ultrasonic thermal welding by the third phase (TWTP) was successfully proposed to join the immiscible thermoplastics. Poly(methyl methacrylate) (PMMA) and polyformaldehyde (POM) were chosen as the work piece (WP) materials. The third phase of functionally graded material (FGM) were prepared from PMMA, POM and polylactic acid (PLA). The optimal welded strength of 47 MPa (approximately 80 % of tensile strength of POM matrix) was achieved, which is satisfied to the lightweight demand in automotive industry. Meanwhile, the welded interfacial morphology can be divided into four parts, which is related to the diffusion depths of interposed sheet (IPS) and WP molecules, respectively. Based on the interdiffusion analysis, the interdiffusion chains can give the similar configuration as that of the IPS due to the steric hindrance and Van der Waals force.

Thermal Degradation of Polypropylene Pine Sawdust Composite Filaments through Successive Heating and Reprocessing

Considering the use of the new molding thermoplastic technique, where viscous filaments can be artistically or technically manipulated to create three-dimensional pieces using an extruder, this paper discusses the optimal PP/wood fiber filament preparation conditions especially the thermal degradation. Not only is it essential to know the best processing conditions of the composites but also gain durability and/or advantageous color change when the final products made with viscous filaments are subjected to thermal treatments. Very few papers have been published on polypropylene-pine wood filament composites and the thermal degradation of such filaments. This paper presents the preparation and characterization of filament composites using 5, 10, and 20wt.% pine sawdust with a compatibilizer obtained by hot molding through the use of an extruder, and discusses the effect of both drying time and temperature on the prepared filament composites to understand thermal degradation when subjected to 60°C and/or 120°C. Prepared filament composites are characterized for physical (density, water absorption, and crystallinity), thermal and tensile properties besides their morphology along with fractography. X-ray diffraction results confirmed the data obtained in thermal studies indicating that increased fiber content decreased both the crystallinity and the thermal resistance while decreasing the melting temperature of the filament composites. Fractographic studies revealed low adhesion between the sawdust and the matrix, evidenced by the presence of loose and some unattached sawdust particles in some composites, thus, supporting the observed low strength in these composites, besides the influence of drying time and temperature on the mechanical properties of the composites.

Blending with Poly(l-lactic acid) Improves the Printability of Poly(l-lactide-co-caprolactone) and Enhances the Potential Application in Cartilage Tissue Engineering.

Poly(l-lactide-co-caprolactone) (PLCL, 50:50) has been used in cartilage tissue engineering because of its high elasticity. However, its mechanical properties, including its rigidity and viscoelasticity, must be improved for compatibility with native cartilage. In this study, a set of PLCL/poly(l-lactic acid) (PLLA) blends was prepared by blending with different mass ratios of PLLA that range from 10 to 50%, using thermoplastic techniques. After testing the properties of these PLCL/PLLA blends, they were used to fabricate scaffolds by the 3D printing technology. The structures and viscoelastic behavior of the PLCL/PLLA scaffolds were determined, and then, the potential application of the scaffolds in cartilage tissue engineering was evaluated by chondrocytes culture. All blends demonstrate good thermal stability for the 3D printing technology. All blends show good toughness, while the rigidity of PLCL is increased through PLLA blending, and Young’s modulus of blends with 10–20% PLLA is similar to that of native cartilage. Furthermore, blending with PLLA improves the processability of PLCL for 3D printing, and the compression modulus and viscoelasticity of 3D-printed PLCL/PLLA scaffolds are different from that of PLCL. Additionally, the stress relaxation time (t1/2) of the PLCL/PLLA scaffolds, which is important for chondrogenesis, is dramatically shortened compared with the pure PLCL scaffold at the same 3D-printing filling rate. Consistently, the PLCL90PLLA10 scaffold at a 70% filling rate with much shorter t1/2 is more conducive to the proliferation and chondrogenesis of in vitro seeded chondrocytes accompanied by upregulated expression of SOX9 than the PLCL scaffold. Taken together, these results demonstrate that blending with PLLA improves the printability of PLCL and enhances its potential application, particularly PLCL/PLLA scaffolds with a low ratio of PLLA, in cartilage tissue engineering.

Effect of obturation technique using a new bioceramic sealer on the presence of voids in flattened root canals.

The aim of this study was to evaluate the filling ability of a new ready-to-use calcium silicate-based sealer using thermoplastic or single-cone technique in flattened root canals. Twenty-four flattened distal canals of mandibular molars with a buccolingual diameter 4 or more times larger than the mesiodistal diameter were selected. The root canals were prepared and filled (n = 12), according to the following techniques: thermoplastic or single-cone technique using Bio-C Sealer. The teeth were scanned using Skycan 1176 micro-computed tomography (micro-CT) - voxel size 8.74 µm, before and after filling the root canal. The percentage of voids in the filled root canals was evaluated, and the data were statistically analyzed using the unpaired t-test (α = 0.05). The root canals filled using the thermoplastic technique created a smaller percentage of voids in the cervical/middle thirds than those filled using the single-cone technique (p < 0.05). There was no difference in the percentage of voids using either technique in the apical third (p > 0.05). The flattened root canals in the cervical/middle thirds were better filled using the ready-to-use calcium silicate-based sealer associated to the thermoplastic technique, compared with the single-cone technique. In the apical third, the techniques showed similar filling ability.

Tissue engineering stent model with long fiber-reinforced thermoplastic technique.

This study aims to construct tissue engineering stents by using the long fiber-reinforced thermoplastic (LFT) technique to develop artery stents. The experimental method combines fibers, the LFT technique, and electrospinning technique. First, the biodegradable polyvinyl alcohol yarns are twisted and coated in polycaprolactone/polyethylene glycol blends through the LFT technique. Next, the weft-knitting and heat treatment are used to establish the stent structure, after which poly(ethylene oxide) (PEO) is electrospun to coat the stents. The morphology, mechanical, and biological properties of tissue engineering stents are evaluated. The test results indicated that the use of the LFT technique retains the softness of filaments, which facilitates the subsequent weft-knitting process. The coating of blends and electrospinning of PEO have a positive influence on the tissue engineering stents, as demonstrated by the tensile strength of 59.93 N and compressive strength of 6.10 N. Moreover, the in vitro degradation of stents exhibits a stabilized process. The water contact angle is 20.33°, and the cell survival rate in 24 h is over 80%. The proposed tissue engineering stents are good candidates for artery stent structure.

Use of technology in endodontics by undergraduate dental students in a south-eastern state of Brazil.

This study aimed to determine the level of incorporation of current technologies for endodontic treatment in undergraduate dentistry courses in a south-eastern state of Brazil. For data collection, a self-assessment-based online questionnaire was created using the "Google Forms" platform, consisting of 12 multiple-choice and a few open-ended questions. The questions were related to the use of current technologies for diagnosis, imaging, use of ultrasonics in endodontics, instrumentation, use of apex locator, microscopy, photodynamic therapy and thermoplastic techniques during endodontic treatment. The questionnaire was sent to 54 dental schools in Minas Gerais. The results show low technological incorporation during the various stages of endodontic treatment by undergraduate students in dentistry courses in Minas Gerais. Despite the availability of several technologies to help perform different stages of endodontic treatment, it was observed that most universities do not teach the use of these technologies. Additional studies are needed to correlate how the lack of incorporation of these technologies could impact on the quality of the endodontic learning for undergraduate students.

Sucesso no tratamento endodôntico em incisivo lateral superior com reabsorção radicular interna inflamatória não perfurante: relato de caso

As reabsorções dentárias internas são geralmente assintomáticas e quase sempre diagnosticadas em exames radiográficos de rotina. O objetivo deste estudo é apresentar um relato de caso clínico de um dente acometido por reabsorção radicular interna inflamatória não perfurante, com intuito de divulgar informações que sirvam de subsídios para orientar os profissionais frente a esses casos, auxiliando na conduta terapêutica. Paciente do sexo feminino, 53 anos de idade, foi encaminhada ao curso de especialização da Faculdade CIODONTO após realização de um exame radiográfico periapical de rotina, o qual mostrou reabsorção interna não perfurante à nível de terço médio radicular do dente 12. Radiograficamente foi verificado que o contorno dos limites pulpares sofre uma expansão relativamente simétrica de aspecto balonizante, contornos regulares e arredondados. Após a abertura coronária, foi observado sangramento compatível à polpa vital, irrigando-se, inicialmente, com água de Cal. O preparo biomecânico pela técnica coroa-ápice sem pressão foi realizado e como medicação intracanal foi selecionado o Callen por 30 dias e pasta L&amp;C por 90 dias. Após esse período, foi realizada a obturação dos canais radiculares pela técnica termoplástica híbrida de Tagger e cimento endodôntico à base de hidróxido de cálcio. A proservação foi realizada após 1 ano e o sucesso da terapia endodôntica foi constatado. Dessa forma, de acordo com o protocolo indicado na literatura é permitida a resolução clínica efetiva de dentes acometidos por reabsorção interna não perfurante, mostrando-se uma ótima alternativa de tratamento conservador.

Evaluation of apical debris extrusion during endodontic retreatment by different systems

Abstract Aim: This study sought to evaluate the amount of apical debris extrusion during the removal of filling material (RFM) performed by the ProTaper-Retreatment (ProTaper-R), Mtwo-Retreatment (Mtwo-R), Reciproc, and hand files. Materials and Methods: Sixty lower premolars were prepared using the ProTaper Universal system and filled with thermoplastic technique. Subsequently, the samples were randomly divided into four groups (n = 15) according to the system used for the removal of the filling material: Mtwo-R (R25/.05); ProTaper-R (D1, D2, and D3); Reciproc (R25); and hand file (type K and Hedstroem stainless steel files). The apical debris extrusion was evaluated before and after the RFM from the root canal by weighing Eppendorf tubes on a high-precision balance. Statistical analysis was performed using the ANOVA test followed by the Tukey's test (P &lt; 0.05). Results: All of the systems produced apical debris extrusion; however, the Mtwo-R group demonstrated significantly more extrusion as compared with the ProTaper-R and Reciproc groups (P &lt; 0.05). There was no statistically significant difference between the Reciproc, ProTaper-R, and hand file groups (P &gt; 0.05). Conclusions: The Mtwo-R group produced significantly more extrusion than did the ProTaper-R and Reciproc groups. There was no difference between the Reciproc, ProTaper-R, and hand file groups.

Evaluation of Lipophilic Properties of Thermoplastic Granule in Formulation of Sustained Release Matrix in Solid Dosage Forms

This study was aimed at developing a new, technically simple method for the preparation of a once-daily sustained release matrix formulations, which would enable reproducible release of the active ingredient. Thermoplastic granulation is a new technique in pharmaceutical formulation. Coated particles of an active pharmaceutical ingredient (API) in sustained release matrix are prepared by thermoplastic granulation technique via heating (50 – 75°C) in fluid-bed dryer (FBD) granulator. The FBD creates ideal conditions for the most intense heat and mass transfer by spraying melted liquids onto the granular API. A variety of innovative processes such as granulation, agglomeration, coating and microencapsulation can be realized. Melted mixture of cetyl alcohol, glyceryl monostearate, and polyethylene glycol 4000 (PEG 4000) was used for fluid-bed coating. The present article deals with assessing the influence of rheological properties and hydrophile-lipophile balance (HLB) parameter of thermoplastic granules on the mechanism of drug delivery from sustained release matrix in solid dosage forms. The drug release kinetics model is affected by rheology, HLB of cetyl alcohol, and physicochemical properties of API granules.

Evaluation of different root canal filling techniques in severely curved canals by micro-computed tomography

AimTo fill the severely curved root canals with different filling techniques and to compare these techniques using micro-computed tomography (micro-CT). Materials and methodsSixty extracted mandibular first molars (degree of root canal curvature >25°) were selected. All samples were divided into four groups and filled with one of the following techniques: lateral condensation, single-cone, continuous-wave obturation, and core carrier. After they were scanned by micro-CT, the total area, filled area and void area of the root canal were calculated. The Mann–Whitney U and Kruskal–Wallis tests were used for statistical analysis (p < 0.05). ResultsIt was shown that significantly more filling material was used in the lateral condensation and core carrier technique groups at 2 and 5 mm than in the single-cone and continuous-wave obturation technique groups (p < 0.05). It was observed no statistically significant difference at 8 mm (p > 0.05). ConclusionNo technique could completely fill in root canal. Regarding the coronal part, all techniques can be used for more effective filling as long as a good condensation is achieved. The use of a plugger with an optimal size according to the localisation of root canal curvature and the choice of a heat-resistant root canal sealer affects the success of the treatment in the thermoplastic techniques.

A Review of the Mechanical Joining Techniques for Thermoplastics

A Review of the Mechanical Joining Techniques for Thermoplastics

Influence of the internal anatomy on the leakage of root canals filled with thermoplastic technique.

The aim of this paper is to evaluate the influence of the internal anatomy on the leakage of root canals filled with the thermoplastic technique. The upper central incisors (UCI) and mesial roots of the lower molars (MRLM) (n=12 each) were tested regarding leakage using the gas-enhanced permeation test (GEPT) after root filling. The quality of the root fillings was assessed using micro-computed tomography (μCT) by superimposing scans before and after treatment to calculate unfilled volume. The calculated void volume was compared between the groups and correlated to the measured leakage values. Data were analyzed using t test and Pearson's correlation tests (p<0.05). The mean void volume did not differ between UCI and MRLM (13.7±6.2% vs. 14.2±6.8%, respectively). However, significantly more leakage was evident in the MRLM (p<0.001). While the leakage correlated highly to the void volume in the MRLM group (R 2=0.981, p<0.001), no correlation was found in UCI (R 2=0.467, p=0.126). MRLM showed higher leakage values, which correlated to the void volume in the root canal fillings. Care should always be taken while doing root canal treatments, but attention to teeth with known/expected complex root canal anatomy should be considered.

Mechanical properties and state of miscibility in poly(racD,L-lactide-co-glycolide)/(L-lactide-co-ε-caprolactone) blends

Polymers based on lactic acid (PLA) are a very promising category of biopolymers. As they are multi-stimuli responsive, can, in many ways, positively interact with the host, stimulating the innate reparative machinery of the human body. Since biopolymers for medical applications are subject to restrictive regulations, blending stands out as an effective method for obtaining tailored properties within a reduced time to market if compared to synthesis. Hence, in this study a set of PDLGA/PLCL blends was obtained by means of thermoplastic techniques and then further characterized. Evaluation techniques include GPC, NMR, DSC, tensile testing and SEM. Although mixtures proved to be immiscible, a full range of tensile properties was achieved. Observation of the surfaces of fracture provided visual evidence of the deformation mechanisms that occurred during the tensile tests which in the end led to failure. Interpretation of the thermal events based on molecular characterization parameters revealed phase separation, crystallization and plasticisation mechanisms that are relevant to any potential applications based on mechanical performance and shape memory behaviour.