Dzogbewu and de Beer (2023) identified LPBF as the dominant and most widely investigated additive manufacturing method for NiTi because it offers favorable geometric precision, densification, and functional property control compared with other routes. In LPBF, a thin layer of metal powder is spread over a build platform, and a laser selectively melts regions defined by the digital model. The process is repeated layer by layer until the three-dimensional component is completed (Chowdhury et al., 2022) (Figure 3A). For NiTi, this apparently simple layer-by-layer process is complicated by melt-pool phenomena, including metal circulation, vapor formation, recoil pressure, and local redistribution of nickel and titanium before solidification (Rangaswamy et al., 2026) (Figure 3B). Nevertheless, this manufacturing process is especially attractive for miniature endodontic devices because laser power, scan speed, hatch spacing, layer thickness, build orientation, and scan path can all be adjusted to influence both geometry and microstructure (Adekanye et al., 2026). 

Electron beam melting is also a powder bed fusion process but uses an electron beam under vacuum instead of a laser (Palmquist et al., 2023). It can produce NiTi components and has advantages such as vacuum processing, reduced oxidation, and lower residual stress due to elevated build temperatures. However, its larger beam size and larger melt pool generally reduce feature resolution. Electron beam melting is less suited to highly intricate geometries because it has lower geometric precision and may require more post-processing (Dzogbewu & de Beer, 2023). This limitation is important because endodontic file architecture requires fine cutting edges, thin walls, narrow spaces, and controlled surface quality.

Directed energy deposition uses a focused thermal source to melt powder or wire as material is deposited. It is useful for repair, cladding, larger components, and functionally graded structures. However, it has lower feature resolution than LPBF and is not well suited for thin endodontic microfeatures (Dzogbewu & de Beer, 2023). Wire arc additive manufacturing is best regarded as a subtype of directed energy deposition because it uses wire feedstock and an arc heat source. Wire arc additive manufacturing has lower dimensional precision and lower geometric accuracy than LPBF, electron beam melting, and directed energy deposition. For that reason, wire arc additive manufacturing is relevant to the broader NiTi additive manufacturing landscape, but it is unlikely to be a practical route for rotary endodontic files.

Binder jetting and fused filament fabrication belong to the sinter-based family of additive manufacturing. Binder jetting deposits a binder into a powder bed, followed by debinding and sintering. Fused filament fabrication uses metal-polymer filament, followed by debinding and sintering. These methods offer lower equipment cost and larger build volume. However, shrinkage, porosity, impurity uptake, and transformation-temperature control are major concerns for NiTi. Abel et al. (2021) showed that fused filament fabrication may be used to produce NiTi components and can be hybridized with LPBF to add filigree structures. However, the authors also emphasized that LPBF is the method of choice for small, filigree, and geometrically complex NiTi features. For endodontics, fused filament fabrication is therefore best considered a complementary or hybrid route, and not the primary method for manufacturing the active cutting portion of a miniature rotary file.

Direct evidence for endodontic application comes from the LPBF study of superelastic NiTi self-adjusting file structures. Chernyshikhin et al. (2022) used pre-alloyed NiTi powder with a 15–45 μm particle fraction and an LPBF system with a 55 μm nominal laser spot diameter to fabricate thin-wall and self-adjusting file samples. Their optimized condition used 100 W laser power, 850 mm/s scanning speed, and 20 μm layer thickness for producing self-adjusting file structures with the required resolution (Figure 4). The authors also identified physical, apparatus-related, and software-related limits to LPBF resolution. This study establishes LPBF as the most credible near-term route for miniature NiTi endodontic devices. However, it also shows that printing file-like structures requires device-specific process optimization.

3.1 Additive manufacturing of NiTi alloys

Nickel-titanium is more difficult to print than conventional structural metals because its value depends on reversible martensitic transformation. A dense printed part is not sufficient. The part must also have the intended transformation temperature, superelastic recovery, fatigue resistance, surface integrity, corrosion resistance, and wear behavior. Selective laser melting (SLM), a term previously employed for LPBF, creates a unique microstructure because the material experiences rapid melting, solidification, repeated reheating, steep thermal gradients, and local chemical changes. These features directly influence phase transformation behavior and functional properties.

Composition control is the first major challenge. Nickel-titanium transformation temperatures are highly sensitive to the Ni/Ti ratio. Small changes in nickel content may shift the martensitic and austenitic transformation temperatures enough to alter whether the printed component behaves as austenite, martensite, or mixed phase at clinical temperature. Wang et al. (2018) noted that nickel evaporation, oxygen uptake, precipitate formation, residual stress, dislocation density, and microstructural heterogeneity can all influence transformation behavior. This is highly relevant to endodontic files because flexibility and recoverable deformation depend on the phase state of the file during clinical use.

Elementally blended Ni and Ti powders are more difficult to control because alloy formation occurs during printing, increasing the risk of chemical heterogeneity, oxygen contamination, and brittle secondary phases. Chmielewska et al. (2022) fabricated NiTi by LPBF from blended Ni and Ti powders and showed that the as-built material contained chemical and phase heterogeneity. Heat treatment improved homogeneity, but oxygen pickup promoted oxygen-stabilized secondary phases, including Ni₂Ti₄O. The authors found that two-step heat treatment improved chemical and phase homogeneity, but oxygen control continued to be a major concern. For printed endodontic instruments, this finding highlights the importance of careful powder selection, strong atmospheric control, and validation of phase homogeneity along the active file portion.

Feature size is another important variable. Qu et al. (2023) showed that process optimization based on bulk cubes, cylinders, or dog-bone specimens may not predict the behavior of thin, intricate NiTi structures. Their high-precision LPBF study used a 25 μm beam, 0–25 μm powder, and 10 μm layer thickness. Triply periodic minimal surface (TPMS) is a smooth three-dimensional lattice architecture that repeats in all spatial directions and may be used to create lightweight structures with continuous pores and controlled mechanical behavior (Hossain et al., 2025). When the wall thickness of Gyroid-TPMS (G-TPMS) structures prepared by Qu et al. (2023) decreased below 130 μm, the optimal volumetric energy density shifted from 167 to 140 J/mm³. The result indicates that thin lattice features require process parameters different from those used for bulk specimens. This finding is directly relevant to endodontics because a printed file may contain thin flutes, narrow struts, lattice regions, hollow cores, and small tips that experience different thermal histories during printing.

Scan strategy must also be treated as a functional design variable. Andani et al. (2026) compared 45°, 67°, 90°, island, and hexagonal scan strategies in LPBF-fabricated NiTi with consistent energy input. The 90° rotation strategy produced a strong <001> fiber texture, approximately 6% superelastic recovery, and minimal plastic strain. The use of island and hexagonal strategies reduced transformation onset stress but produced incomplete recovery because austenite finish temperatures increased to approximately 32–34 °C. This finding is central to printed NiTi file design because laser trajectory can alter texture, residual stress, transformation temperature, and superelastic recovery without changing the nominal alloy composition.

Post-print conditioning may become part of the manufacturing process for future NiTi endodontic instruments. Zhang et al. (2025) showed that mechanical training (pre-strain/cyclic compression treatment) of LPBF-fabricated Ni-rich NiTi produced a nearly twofold improvement in wear resistance. The specimens were first compressed to 9% strain, and then subjected to 15 compression cycles at the same compressive strength. This treatment modified dislocation structures and improved martensitic transformation behavior, cyclic compression superelasticity, and adhesion stress during wear. Although the authors did not study endodontic files, the concept is highly relevant because rotary instruments contact canal walls repeatedly and are exposed to friction, cutting stress, cyclic bending, torsional engagement, irrigants, and sterilization. A future printed NiTi file may therefore require a complete process chain: powder specification, LPBF parameter selection, scan strategy, heat treatment, surface finishing, mechanical training, sterilization validation, and fatigue testing.

The variables that determine the behavior of printed NiTi instruments may be organized as a process–structure–property chain, in which powder chemistry, LPBF parameters, scan strategy, post-processing, and surface finishing jointly influence transformation behavior and clinical performance (Table 1).

3.2 Current applications of printed NiTi and implications for endodontics

Printed NiTi has attracted attention in biomedical, aerospace, actuator, and functional-device applications because it combines shape-memory behavior, superelasticity, damping, low modulus, and geometric freedom (Dzogbewu and de Beer, 2023). However, the requirements for a rotating endodontic file are more severe than those for many larger implants or actuators.

Biomedical applications provide the closest translational analogy. Sun et al. (2024) evaluated an LPBF-fabricated NiTi alloy with high tensile performance and reported tensile strain of approximately 15.6% and tensile strength of approximately 700 MPa. Their in vitro study also found favorable biocompatibility and bioactivity compared with Ti-6Al-4V alloy. This finding is encouraging because it links printed NiTi to biological performance. However, endodontic translation would require additional testing in NaOCl, EDTA, repeated sterilization cycles, simulated canal curvature, torsional binding, cutting contact, and cyclic fatigue resistance. 

Miniature and flexible medical devices are especially relevant. Qu et al. (2023) fabricated a robotic cannula tip by high-precision LPBF and demonstrated recovery after bending greater than 90° at room temperature. The endodontic significance is that thin, functional NiTi architectures may be printed when feature size, energy density, and superelastic behavior are optimized together. This is best illustrated by the printing of NiTi self-adjusting file structures by Chernyshikhin et al. (2022).

Wear-resistant applications also provide lessons for rotary instruments. Zhang et al. (2025) showed that LPBF NiTi wear behavior can be improved through mechanical training. This is important because future printed endodontic NiTi rotary instruments will not function as passive implants. They will rotate, cut, abrade against canal walls, accumulate cyclic strain, and contact irrigants. Mechanical training, surface finishing, and post-print heat treatment should therefore be evaluated as part of a manufacturing workflow.

The current evidence indicates that LPBF is capable of fabricating intricate NiTi structures, miniature file-like architectures, and flexible superelastic components. The next research question should therefore be more demanding than whether a NiTi file can be printed. The clinically relevant question is whether additive manufacturing can create a file architecture with safer fatigue behavior, controlled torsional response, predictable cutting, reproducible phase transformation, and better adaptation to canal anatomy than wire-based instruments.

4. Opportunities for Future Endodontic Instrument Design

4.1 Expanded design freedom

The most important opportunity created by metal additive manufacturing is expansion of the instrument design space. The extent of this design freedom is illustrated by additively manufactured woven NiTi structures, including tubular, spherical, toroidal, and knotted geometries, which demonstrate how LPBF can produce complex superelastic architectures beyond simple cylindrical forms (Aguilar Vega et al., 2026) (Figure 5).

Conventional rotary files are designed around a solid wire or rod blank. This starting geometry permits changes in taper, flute depth, pitch, helical angle, cross-section, and surface treatment, but does not permit free control of internal architecture. Additive manufacturing changes the design question. Future NiTi instruments would not have to begin as solid cylinders. They could be designed as digitally defined structures in which external cutting geometry, internal architecture, and local mechanical behavior are developed together. This transition from a solid wire-based instrument to a digitally engineered architecture is illustrated in Figure 6.

These design possibilities include hollow cores, lattice-reinforced shafts, controlled wall thickness, internal channels, and region-specific metal distribution. Lattice and cellular structures have already been examined extensively in metal additive manufacturing (Maconachie et al., 2019; Yu et al., 2022; Biffi et al., 2024; Polo et al., 2025). This is because they allow stiffness, mass, energy absorption, and permeability to be adjusted through unit-cell geometry, strut diameter, and porosity. These concepts are relevant to NiTi files because the clinical problem is not simply cutting dentin. The file must enlarge the canal, preserve curvature, resist torsional binding, tolerate cyclic bending, and avoid excessive dentin removal.

A printed NiTi file could therefore be conceived as an architecture and not simply as an alloy with flutes. The coronal shaft might contain greater metal volume for torsional resistance. The apical portion might incorporate lower metal volume, a hollow center, or a flexible lattice to improve bending compliance. Cutting edges could be placed only where dentin engagement is desired. Non-cutting zones could be designed to reduce screw-in tendency or canal transportation. Internal voids or longitudinal channels could also be explored for debris displacement or irrigant movement. These concepts would require careful validation for clogging, cleaning, strength loss, and manufacturing reproducibility. Although Chernyshikhin et al. (2022) provided the first direct indication that LPBF can fabricate miniature NiTi self-adjusting file-like structures, that work should not be interpreted as evidence that printed rotary files are clinically ready. At present, the literature demonstrates printability of NiTi structures, not validated rotary-file performance.

4.2 Functionally graded instruments

Additive manufacturing may also permit functionally graded NiTi instruments. A functionally graded file would not have uniform stiffness, mass distribution, or phase behavior along its length. Instead, the mechanical response could be intentionally varied from the shank to the tip. This concept is attractive because the mechanical demands of a rotary file differ by location. The coronal and middle portions must transmit torque and resist unwinding. The apical portion must negotiate curvature, maintain centering, and avoid transportation. A single homogeneous geometry cannot fully satisfy these competing requirements. This concept is illustrated in Figure 7, in which the coronal portion is designed as a denser load-bearing region, the middle portion provides a transition zone, and the apical portion contains a more open architecture to increase flexibility.

Functional grading could be achieved in several ways. The simplest approach would be geometric grading. Local core diameter, wall thickness, porosity, lattice density, and unit-cell shape could be varied along the file. A denser coronal lattice could increase torsional stiffness. A more open apical lattice could increase flexibility. A gradual transition between these zones could reduce abrupt stress concentration. Additively manufactured lattice materials are particularly suited to this type of design because mechanical response can be controlled by cellular architecture as well as by the base alloy (Biffi et al., 2024).

A second approach would be process-based grading. Laser parameters, scan path, hatch spacing, layer thickness, and build orientation can influence local thermal history and microstructure. In NiTi, these variables may alter transformation temperatures, texture, residual stress, and superelastic recovery. This creates the possibility of linking geometry-based grading with metallurgical grading. For example, a file could theoretically be designed with regions favoring greater recoverable deformation apically and greater torsional stability coronally. This possibility is scientifically attractive but technically demanding because NiTi phase transformation behavior is highly sensitive to composition, thermal history, and post-processing.

Graded designs would also need to respect the clinical failure modes of NiTi files. Increasing apical flexibility is useful only if torsional safety is preserved. Increasing coronal stiffness is valuable only if stress does not concentrate at the transition zone. The goal should therefore be balanced mechanical gradients, not maximal flexibility at one end and maximal stiffness at the other. Additive manufacturing provides a platform for exploring such gradients systematically.

4.3 Adaptive and patient-specific instruments

A further opportunity is the development of adaptive and anatomy-responsive instruments. Root canals vary substantially in curvature, ovality, diameter, isthmus anatomy, and calcification. A single standardized file sequence cannot match every canal form. Additive manufacturing raises the possibility of instruments designed for anatomical categories, canal phenotypes, or, in selected cases, individual anatomy.

The most realistic near-term approach is probably not a unique file for every patient. Individualized production would face cost, sterilization, validation, and regulatory barriers. A more practical pathway would be families of anatomy-responsive instruments. For example, different printed architectures could be developed for severely curved canals, long oval canals, calcified canals, or retreatment situations. Each architecture could be designed around a different balance of flexibility, canal contact, cutting activity, debris displacement, and torsional safety. This concept is illustrated in Figure 8, which shows families of additively manufactured NiTi instruments designed for curved, oval, calcified, and retreatment canals, each emphasizing a different balance of flexibility, canal contact, cutting activity, debris displacement, and procedural safety.

Patient-specific instrument design would require integration of imaging, segmentation, digital modeling, and manufacturing. Cone-beam computed tomography could define broad anatomical constraints, although its resolution is insufficient for full canal microanatomy. Micro-computed tomography is valuable for research but not routine clinical design. Therefore, patient-specific printed files should be regarded as a long-term possibility. The nearer opportunity is anatomy-informed design: using large anatomical datasets to create printed instruments optimized for common canal classes.

4.4 Integration of computational design

The full value of additive manufacturing will depend on computational design. Without computation, printed files may simply reproduce shapes that are already familiar. With computation, file architecture can be optimized for bending, torsion, fatigue, cutting contact, canal centering, and manufacturability before fabrication. Figure 9 illustrates a digital engineering workflow in which canal anatomy, instrument design, computational optimization, LPBF fabrication, and mechanical testing are linked in an iterative loop.

Topology optimization and cellular-structure design are especially relevant. These methods can distribute material only where it contributes to a defined mechanical objective, such as stiffness, compliance, mass reduction, or stress reduction (Liu et al., 2024; Shi et al., 2025). In additively manufactured metals, topology optimization has been used to create porous structures, lattice frameworks, and print-ready designs with controlled mechanical behavior (Cheng et al., 2019; Ibhadode et al., 2023; Tajima & Yamada, 2023). Mechanical metamaterials are architected materials whose mechanical behavior is governed primarily by geometry (Biffi et al., 2024). In printed NiTi, lattice density, fiber orientation, pore architecture, and woven topology can be adjusted to tune stiffness, compliance, recovery, and energy absorption without changing the base alloy (Xu et al., 2026). This principle is directly relevant to additively manufactured endodontic instruments because file flexibility, torsional response, and canal-contact behavior could potentially be controlled through architecture instead of only through alloy treatment or external flute design. The effect of architecture on mechanical behavior is illustrated in Figure 10, which compares 9-thread printed NiTi lattice and woven metamaterials under axial and lateral compression. For endodontic instruments, similar methods could be used to create files that flex in preferred directions, resist torsion at specific locations, or reduce stress concentration near the transition from the active file to the shank.

Finite element analysis would be needed to test candidate designs virtually before printing (Chen et al., 2024). Simulations could examine bending in curved canals, torsional locking, canal-wall contact, stress distribution, and fatigue-sensitive regions. Computational fluid dynamics could also be used if internal channels are designed for irrigant or debris movement (Abdollahzadeh et al., 2025). The models would need validation against mechanical testing, simulated canal studies, and fracture analysis.

A future workflow might begin with canal anatomy datasets, define mechanical objectives, generate candidate architectures, screen them computationally, print prototypes by LPBF, and test them under clinically relevant fatigue, torsion, wear, and irrigation conditions. In that workflow, additive manufacturing would become part of a digital engineering loop that connects anatomy, design, simulation, metallurgy, and clinical performance.

5. Scientific and Clinical Challenges

Additive manufacturing does not remove the clinical constraints that govern NiTi rotary instruments. It intensifies them. A printed file would have to satisfy requirements for precise geometry, stable phase transformation, cyclic fatigue resistance, torsional safety, corrosion resistance, sterilization tolerance, and reproducible batch production (Kubášová et al., 2024; Rangaswamy et al., 2026). These requirements are more stringent than those for many printed NiTi implants because an endodontic file is a slender instrument that rotates in a constrained, curved, wet, and chemically aggressive canal space.

The main translational question is whether a printed file can deliver predictable clinical behavior after powder handling, laser melting, post-processing, cleaning, sterilization, packaging, and use. This distinction is essential because additive manufacturing can create architectures that are mechanically attractive in principle. However, endodontic instruments must also cut dentin, transport debris, resist separation, preserve canal anatomy, and remain biologically safe.

5.1 Surface quality

Surface quality is the first barrier to clinical translation. Laser powder bed fusion produces surfaces that are influenced by powder particle size, layer thickness, scan-track overlap, melt-pool stability, local energy input, and post-processing (Chowdhury et al., 2022; Kubášová et al., 2024). The microscopic melt-pool behavior illustrated in Figure 3B is therefore clinically relevant because local instability can create adherent particles, balling, re-solidified spatter, layer striations, and rough strut surfaces (Rangaswamy et al., 2026).

These features are not merely cosmetic defects. In rotary endodontic instruments, surface irregularities may act as stress concentrators during repeated flexural loading and may accelerate fatigue crack initiation (Cheung, 2009; Plotino et al., 2009). This concern is magnified for printed files because the active portion is small; a surface particle or notch that appears minor on a larger implant may represent a substantial local defect relative to file diameter or strut thickness (Figure 4B).

Post-processing will therefore be mandatory for any printed NiTi endodontic instrument. Electropolishing, passivation, laser finishing, chemical polishing, abrasive flow finishing, and micro-machining could reduce surface defects. However, each method may also change flute geometry, edge sharpness, taper, cross-sectional area, and transformation behavior. Dimensional control after finishing should be evaluated against endodontic instrument requirements. These requirements include tip size, taper, active cutting geometry, and resistance to deformation (International Organization for Standardization, 2020).

Surface finishing also raises a design conflict. A smoother surface may improve fatigue resistance and corrosion behavior, but aggressive polishing may blunt cutting edges or narrow lattice openings intended for flexibility, debris displacement, or irrigation exchange. For printed NiTi files, the type of surface treatment cannot be an afterthought; it must be part of the original digital design and manufacturing workflow.

5.2 Mechanical performance

Conventional NiTi rotary instruments fail mainly through cyclic fatigue, torsional overload, or a combination of both mechanisms (Cheung, 2009; Plotino et al., 2009; Yon et al., 2021). Printed NiTi instruments would need to satisfy the same failure thresholds, but with the added complexity of internal architecture, anisotropic build orientation, residual stress, porosity, surface roughness, and local phase heterogeneity.

Cyclic fatigue testing should include static and dynamic canal models with clinically relevant curvature, radius, rotational speed, temperature, and irrigant exposure. Plotino et al. (2009) noted that cyclic fatigue results depend strongly on testing geometry and experimental conditions. This issue becomes even more important for additively manufactured files because small differences in local architecture could change the bending strain distribution along the active portion.

Torsional resistance also requires careful evaluation. A printed lattice or hollow-core file may become more flexible. However, excessive reduction in polar moment of inertia could increase the risk of plastic twisting or separation when the tip binds. The ISO 3630-5 standard provides baseline requirements for endodontic instruments. Additive manufacturing-specific validation should extend to repeated torsional loading, cyclic torsion, and combined bending-torsion testing that is not currently addressed by the ISO 3630-5 standard (International Organization for Standardization, 2020).

The same architecture that improves flexibility may alter cutting efficiency, screw-in tendency, debris removal, and canal transportation. Lattice or variable-wall designs could reduce restoring force against canal walls. Yet, they may also reduce cutting edge support or change flute space. Therefore, mechanical testing should be paired with shaping experiments in standardized resin blocks, extracted teeth, and micro-computed tomography models that quantify centering ability, transportation, untouched canal wall area, debris accumulation, and preparation time.

Printed NiTi metamaterials show that stiffness and recovery can be tuned by design. Aguilar Vega et al. (2026) demonstrated that printed NiTi lattice and woven architectures can produce markedly different load-strain behavior under axial and lateral compression. That principle is attractive for future endodontic file designs. Nonetheless, direct extrapolation to rotary instrumentation would be premature because most mechanical testing and finite element analyses have been performed on larger printed specimens or simplified architectures. Testing on fully printed objects with the size, slenderness, taper, and rotational loading conditions of an endodontic file has not yet been demonstrated.

5.3 Biological considerations

Biological safety must be evaluated independently from mechanical performance. Nickel-titanium has a strong clinical history because its titanium-rich oxide layer contributes to corrosion resistance and biocompatibility. However, nickel release is a concern for any Ni-containing medical material (Navratilova et al., 2024; Liu et al., 2025). Printed NiTi rotary instruments add new variables, including surface roughness, residual porosity, partially melted particles, heat-affected regions, oxygen uptake, and local composition changes that may alter oxide stability.

Sun and colleagues (2024) reported favorable in vitro biocompatibility for an SLM/LPBF-fabricated NiTi alloy with strong tensile properties. Although this finding is encouraging, it does not establish biological safety for printed endodontic files. Root canal instruments are exposed to sodium hypochlorite, EDTA, irrigant agitation, repeated autoclave sterilization if reusable, dentin debris, blood, inflamed tissue remnants, and microbial biofilms. These conditions may alter corrosion behavior and nickel ion release (Sussman et al., 2022).

The ISO 10993-1:2025 standard provides the overarching risk-management framework for biological safety evaluation of medical devices, including devices produced by additive manufacturing (International Organization for Standardization, 2025a). ISO 5092:2025 adds an additive manufacturing-specific medical-device perspective for additively manufactured non-active implants (International Organization for Standardization, 2020, 2025b), whereas ISO 3630-5:2020 provides the closest endodontic instrument framework for shaping and cleaning instruments. These standards should be considered complementary for LPBF-fabricated NiTi files because none is specific to printed endodontic rotary instruments. Final-device testing should therefore reflect the printed geometry, surface condition, cleaning protocol, sterilization method, and clinical chemical exposures. The major biological, chemical, and cleanability issues requiring validation are summarized in Table 2.

In addition, a single-use printed file may require different validation from a reusable file that undergoes sterilization cycles. A hollow or lattice-containing instrument may also require more stringent cleaning validation because internal pores, channels, and lattice spaces could retain organic debris or microorganisms. For this reason, printed endodontic file design should avoid inaccessible internal surfaces unless cleaning, sterilization, and manufacturing residues can be convincingly controlled.

5.4 Manufacturing and economic feasibility

Manufacturing feasibility is the final translational barrier. Laser powder bed fusion can create complex NiTi structures. Producing a research prototype, however, is different from producing a regulated, quality-assured, commercial endodontic instrument (Chernyshikhin et al., 2022). Powder chemistry, powder reuse, particle-size distribution, oxygen control, laser calibration, build orientation, scan strategy, support removal, post-processing, cleaning, inspection, and packaging would all require documented control (Chowdhury et al., 2022; Rangaswamy et al., 2026).

Modeling and process simulation may reduce development time by linking powder behavior, melt-pool physics, heat transfer, residual stress, and defect formation. Abdollahzadeh et al. (2025) described computational fluid dynamics modeling of LPBF-fabricated NiTi as a route for understanding coupled thermal and fluid-flow behavior. Such models could eventually help define safe processing windows for miniature endodontic designs. However, they must be validated against dimensional accuracy, phase transformation behavior, surface quality, and mechanical testing.

The ISO/ASTM 52920:2023 standard provides qualification principles and requirements for industrial additive manufacturing processes and production sites (International Organization for Standardization & ASTM International, 2023). It is relevant to process control, documentation, production-site qualification, and quality assurance. However, it is not specific to medical devices or endodontic instruments. ISO 5092:2025 has a different role: it provides a medical additive manufacturing framework for non-active implants. For printed NiTi files, both frameworks would need to be interpreted together with ISO 3630-5:2020, ISO 10993-1:2025, and device-specific testing.

Economic feasibility is equally important. Conventional NiTi files are already manufactured at scale by wire drawing, heat treatment, grinding, twisting, electropolishing, and coating. Fully printed files would need to justify higher production cost through a clinically meaningful advantage, such as improved safety in severe curvature, controlled torsional release, better canal adaptation, or specialized retreatment function. Early adoption is therefore more likely to involve specialty instruments, hybrid manufacturing, or limited high-value designs than routine replacement of all conventional rotary files.

Commercialization will also depend on regulatory classification and evidence. A printed NiTi endodontic file would probably be treated as a new device design and not merely a new manufacturing route. The evidence package should therefore include manufacturing validation, sterilization validation, biological risk assessment, mechanical testing, bench-top canal shaping, preclinical studies, and eventually clinical evidence. Until these requirements are satisfied, additive manufacturing should be presented as a promising engineering pathway, and not as an imminent replacement for established NiTi file manufacturing.

6. Future Directions 

To date, no additively manufactured NiTi endodontic rotary file is commercially available for clinical use. This point should be stated clearly because the current field is still at the proof-of-concept stage. Printed NiTi structures, including file-like and lattice-based geometries, demonstrate that additive manufacturing can create shapes that are difficult or impossible to obtain by wire grinding (Chernyshikhin et al., 2022; Aguilar Vega et al., 2026). However, these studies do not establish clinical readiness for rotary instrumentation.

The next stage should move from printing feasibility to file-scale validation. Future studies should fabricate complete endodontic instruments with clinically relevant tip sizes, tapers, flute geometry, slenderness, and working lengths. These instruments should then be tested in simulated canals, extracted teeth, and canal-like mechanical models, including cyclic fatigue in curved canals, torsional loading, bending stiffness, cutting efficiency, debris removal, canal transportation, and fracture behavior. Testing should also include repeated sterilization, NaOCl exposure, EDTA exposure, corrosion behavior, nickel ion release, and cleaning of internal channels or lattice regions.

Process control will be equally important. LPBF-fabricated NiTi files would require reproducible powder quality, validated scan parameters, control of nickel-titanium composition, predictable transformation temperatures, surface finishing, residual powder removal, and final-device inspection. Micro-computed tomography, surface metrology, differential scanning calorimetry, mechanical testing, and corrosion testing should be integrated into the validation pathway. Although ISO 3630-5:2020, ISO 10993-1:2025, ISO 5092:2025, and ISO/ASTM 52920:2023 may provide useful frameworks, none of these standards alone is sufficient for printed NiTi endodontic rotary instruments.

A realistic near-term goal is not fully patient-specific instrumentation. A more practical pathway is the development of standardized families of anatomy-responsive printed files for curved canals, long oval canals, calcified canals, and retreatment procedures. Until file-scale mechanical, biological, manufacturing, and clinical data are available, additively manufactured NiTi endodontic instruments should be regarded as a future engineering opportunity, not a current clinical product.

7. Conclusion

Metal additive manufacturing could expand NiTi endodontic instrument design beyond the limitations of wire-based grinding by enabling hollow regions, lattice architectures, graded stiffness, and anatomy-responsive geometries. These possibilities are attractive because they may allow future files to balance flexibility, torsional safety, cutting efficacy, and canal preservation in ways that are difficult to achieve with conventional manufacturing. However, printed NiTi endodontic rotary files are not currently available for clinical use. Existing evidence is limited to printed NiTi specimens, lattice structures, and preliminary file-like geometries. Translation will require file-scale validation of print resolution, phase transformation behavior, cyclic fatigue resistance, torsional performance, surface finishing, corrosion behavior, cleaning, sterilization, and biological safety. At present, additively manufactured NiTi files should be viewed as a promising engineering direction, not an established clinical technology.