Current applications of three-dimensional (3D) printing in pediatric dentistry: a literature review

3.1 Master models

With the use of intraoral scanners, dentists often prefer to utilize a 3D-printed master model of the scanned jaw (Fig. 1). The production of a master model is not always necessary, but this preference persists due to dentists’ familiarity and comfort with visualizing restorations on a physical model, in spite of their direct digital fabrication. Moreover, the digital archiving of patient model data allows for on-demand printing, which significantly alleviates the burden of physical storage [16].

Fig. 1.Master models. (A) Digital impression obtained by using intraoral scanners (Trios 5, 3Shape, Copenhagen, Denmark). (B) 3D-printed master model produced with SLA technology (Formlabs Form 3B; Formlabs Inc, Sommerville, MA) and model resin.

3.2 Educational models

Recent advancements in 3D printing technologies have enabled the development of innovative educational and clinical instruments in dental education. Integrating 3D scanners, cone-beam computed tomography (CBCT), and 3D printers has revolutionized the creation of anatomically accurate replicas, yielding simulated dental models with a high degree of clinical relevance. These models have proven to be effective tools in education and have enhanced the learning experience [17, 18, 19].

The increased accessibility of 3D printing equipment has significantly improved the prospects of employing 3D-printed educational models for dental professionals. The aim in this regard is primarily to augment dental students’ hands-on skills and substantially improve dental practitioners’ practical competencies [17, 20, 21, 22]. Studies using 3D models in undergraduate and graduate education in dentistry have been carried out in the fields of prosthetics [21, 23, 24, 25], surgery [12, 26, 27, 28], endodontics [29, 30], pediatric dentistry [17], and trauma management [31].

Marty et al. [17] designed and produced a 3D model from a computed tomography (CT) scan, which has been the only 3D-printed model for pediatric dentistry training thus far. Students prepared pulpotomy and stainless-steel crowns on primary molars using industrial and 3D-printed models. While students gave both models high marks regarding learning potential and applicability, the simulation of caries in 3D models was appreciated. Students also reported that 3D models offered a more realistic experience because proximity to the pulp made it possible to understand the need for pulp treatment, which provided an educational advantage [17].

3.3 Fabrication of space maintainers

3D printing is already used in the production of space maintainers in pediatric dentistry [32] (Fig. 2). Dhanotra et al. [33] reported that space maintainers fabricated through CAD-CAM or 3D printing methodologies using biocompatible substances, which are referred to as “Digital Space Maintainers”. They posited that digitally created space maintainers could be used as alternatives to conventionally produce space maintainers. The authors pointed out that the advantages of digitally fabricated space maintainers include high strength, smooth surfaces, quick fabrication time, light weight, and do not cause gingival trauma [33].

Fig. 2.3D-printed space maintainers. (A) The digital design of 3D-printed space maintainer [32]. (B) 3D-printed space maintainer produced with cobalt chromium-based powdered metal material [32].

Pawar [34] and Khanna et al. [35] used 3D printing to produce space maintainers using titanium-based powdered metal material, which provided maximum precision with the least possible errors compared to conventional band-and-loop space maintainers Tokuç and Yılmaz [36] evaluated the band fit of metal 3D-printed space maintainers using SLS technology. They reported no significant difference in the fit of conventional and 3D-printed metal band-and-loop space maintainers. Although space maintainers produced from printable metal powder materials such as CoCr and titanium alloys seem suitable for clinical use, these materials were reported to be hard, inflexible and unesthetic.

Watson et al. [37] assessed the retention properties of 3D-printed space maintainers crafted from various clear resin materials. Their findings revealed that the strength under load of claw-design 3D-printed space maintainers might be sufficient to serve as an alternative to conventional space maintainers. However, they noted lower retention in the 3D-printed space maintainers than conventional ones.

Yangdol et al. [32] produced band and loop space maintainers using 3D printing technology in a child with autism. Cobalt-chromium alloy was used in the production of the space maintainer because it is a more cost-effective biomaterial than titanium. The authors reported that it is beneficial for children in need of special health care, considering the advantages of reducing the time spent at the bedside, using fewer tools, and fast and easy production.

Cengiz and Karayılmaz [38] conducted an in-vivo study to compare the clinical success, retention, and periodontal effect of conventional band-and-loop space maintainers with 3D-printed space maintainers produced from titanium-based metal powder with SLS. That survival time was significantly higher with conventional space maintainers, and there were no differences between baseline and control values in both groups in terms of gingival and plaque indexes. Additionally, 3D printing has been used in the creation of various interceptive orthodontic appliances, including brackets and clear aligners. It has been reported that 3D printing applications will be significantly beneficial in the fields of early orthodontic applications [39, 40].

3.4 Prosthetic restorations

Recently, in pediatric dentistry, 3D printing has become widespread in the production of esthetic pediatric dental crowns (Fig. 3) [41, 42, 43, 44, 45]. The American Academy of Pediatric Dentistry (AAPD) recommends the application of full-coverage restorations for children exhibiting extensive multi-surface lesions or at high risk for caries [46]. The most frequently used restoration has been preformed stainless-steel crown. However, prefabricated zirconia crowns have emerged as a notable alternative for restoring primary molars, which offer enhanced esthetics and clinical performance. Despite these advantages, high cost and wear characteristics have limited their usage [44, 47].

Fig. 3.Prosthetic restorations unpolished 3D-printed restoration for primary molars using a 3D printer (Formlabs Form 3B; Formlabs Inc, Sommerville, MA, USA) and printed resin material for definitive prostheses (Formlabs, Formlabs Inc, Sommerville, MA, USA).

Kessler et al. [41] evaluated experimental pediatric composite crowns manufactured industrially using 3D printing. The study compared the wear and fracture behaviors of these resin crowns with those of stainless steel and prefabricated zirconia crowns. The findings indicated that the resin crowns exhibited the lowest fracture rates. Al-Halabi et al. [42] assessed the clinical performance of crowns for primary molar restorations manufactured using 3D printing and CAD-CAM. The researchers reported that crowns produced with 3D printing displayed superior retention and gingival response, suggesting their reliability and efficacy for restoring primary molars. Al-Halabi et al. [43] later compared the clinical performance of 3D-printed crowns with direct composite celluloid crowns in primary molar restorations. Both restorations offered suitable esthetic alternatives, but the 3D-printed crowns exhibited greater marginal integrity and superior gingival health.

Kim et al. [44] evaluated the flexural strength and fracture resistance of 3D-printed crowns of varying thicknesses for the esthetic restoration of primary molars in comparison with prefabricated zirconia crowns. The findings indicated that the 3D-printed crowns had clinically comparable fracture resistance and flexural strength to that of zirconia crowns, allowing them to be a new potential esthetic alternative for the restoration of primary molars. Shin et al. [48] investigated the wear characteristics of primary tooth enamel and the material surface following mastication simulation using four different temporary composite resins employed in additive manufacturing. They found that the wear behavior varied among the different materials used.

Aydın and Uğuz [49] evaluated the shear bond strength of permanent 3D-printed resin to primary tooth dentin using different bonding agents. The shear bond strength values of the newly developed permanent 3D-printed resin were similar to that of primary teeth dentin with resin-modified glass-ionomer cement and self-adhesive resin cement, but glass-ionomer cement showed lower values than the others.

Aktaş et al. [50] evaluated the marginal and internal gaps of resin-based milled and 3D-printed crowns for primary teeth designed with CAD and artificial intelligence software using microcomputed tomography. The tested group 3D-printed resin-based crowns showed clinically acceptable marginal and internal adaptation values. The AI-designed crowns showed better marginal adaptation with 3D printing.

3.5 Surgical guides and obturators

In pediatric dentistry, 3D printing has shown significant promise for accurate diagnosis and treatment planning. Additive manufacturing allows for creating precise 3D models tailored to orofacial defects that could aid in pre-surgical planning and the development of surgical guides. These models are beneficial in pediatric cases and assist in visualizing maxillofacial defects and implant placement. 3D printing has potential for use in pediatric orthognathic surgery but it is essential to note that such surgeries are typically performed on fully grown patients, not pediatric populations [6, 51, 52, 53, 54].

In the feasibility study conducted by Lee et al. [52] , the effectiveness of 3D planned surgical guides was evaluated in the extraction of supernumerary teeth using 3D-printed simulation models. The results of the study demonstrated that the use of surgical guides significantly reduced the operation time and minimized the amount of material removed. These findings suggest that the 3D surgical guide technique is a suitable method for minimally invasive surgery, especially in pediatric patients.

Joseph et al. [51] employed 3D printing for both diagnosis and treatment in a case involving unerupted maxillary central incisors. CBCT and 3D printing were used in dental treatment planning and execution, which enabled precise determination of the position and pathology of unerupted teeth. This facilitated the evaluation of treatment limitations through anchorage and mechanics, and enhanced patient and parental engagement through clear visualization of the malocclusion.

3D printing has promising potential for future applications in the field of pediatric orthognathic surgery [55]. Temporomandibular joint ankylosis in children is a challenging problem and is usually due to tumors, congenital anomalies or trauma [56, 57]. A significant challenge in orthognathic surgery for young patients is the issue of autorotation of the temporomandibular joint, which can potentially lead to condylar instability. Detailed 3D computed tomography and the preparation of stereolithographic models have allowed the construction of individual prostheses for each patient thanks to the application of 3D-printing [58]. The utilization of a personalized orthognathic surgical guide system, incorporating screws and titanium plates produced through 3D printing addresses concerns by facilitating the precise positioning of the condyle. This innovative approach enhances surgical compatibility and ensures a high level of accuracy [59].

Mao et al. [60] compared the surgical method and safety of bilateral mandibular distraction osteogenesis using 3D printing and conventionally manufactured surgical guides for the treatment of infants with severe Pierre Robin sequence. 3D-printed surgical guides have been used successfully and show superior effectiveness and safety compared to conventional guides in many regards, such as hospital stay and surgery time [60]. In the context of orthognathic surgery, 3D printing is playing a crucial role in various aspects, including 3D diagnosis, virtual planning, and the creation of surgical guides. While surgical guides are valuable tools, it is important to recognize that they may not always be necessary for optimal outcomes in oral surgery.

The clinical application of an obturator is significantly limited due to patients with large oronasal fistula discomfort in impression taking and difficulties in prosthesis fabrication. Digital technology such as intraoral scanning and additive manufacturing has been applied in dentistry to improve the fabrication of obturators for patients with oronasal fistula clefts. Digital obturators are produced by 3D printing method from models obtained by more precise and accurate impression procedures such as intraoral scanning or CBCT. These digital techniques have many advantages, such as avoiding the inevitable errors associated with the impressions and plaster revisions [61]. Digital obturators can be produced using 3D printing to perfectly adapt to any tissue defect and in a much shorter time [62]. It has been reported that polymethylmethacrylate is widely used as a 3D-printed material in obturators due to its low density, aesthetics, cost effectiveness, stability and biocompatibility [61, 62].

3.6 Splint design and fracture treatment

The primary objective of a dentoalveolar trauma splint is to maintain injured teeth in a natural position and promote the gradual repair of supporting tissues. Additionally, it serves as a guide for the proper repositioning of teeth. The digital construction of a 3D splint is facilitated by CT scan information, and the resulting splint can be cemented or cured in place in the traumatized region [53].

Managing pediatric fractures poses a significant challenge given the crucial role of patient cooperation in most cases. In addition, fractures are treated differently than in adults. In cases of mild jaw fractures where the displacement is not pronounced, a conservative approach is generally advised. Nonetheless, when there is clear displacement, the necessity for accurate and minimally invasive surgical intervention becomes paramount to mitigate effects on the growth and development of the jaw and the eruption of permanent teeth in pediatric patients. Such interventions are rendered more intricate due to the unique anatomical and physiological properties of children’s jawbones, which are notably thin and elastic [63].

In the study presented by Yang et al. [64], the normal anatomical form of the mandible was reconstructed in the software program using CT images taken from the maxillofacial region in the management of pediatric patients with mandible fractures. The three-dimensional longitudinal position of the tooth germ was measured, and the length of the titanium plate, the number of screws, the direction and length of the screws were adjusted according to the tooth stretch and fracture line. The plates, which will help position both titanium plates and titanium plates and screws, are produced with 3D printing technology.

Case report, have demonstrated notable benefits in the preoperative workflow with the use of a 3D-printed patient-specific splint, including reduced operative time and minimal trauma to adjacent anatomical structures [65]. Du et al. [66] used CAD and 3D printing technologies in the treatment of a pediatric patient with multiple mandibular fractures. They used 3D printing with the aim of preventing injury to tooth germs during the surgical intervention and reported that if facilitated the design and precise placement of titanium plates. The authors reported that it is not possible to establish a stable occlusal relationship in children due to incomplete eruption of permanent teeth in the oral cavity of children, short crowns of milk teeth, and root resorption that causes loosening of primary teeth. For this reason, it has been reported that splints and bite plates designed with special software using data obtained from the patient and produced with 3D printing technology can repair the occlusal relationship more accurately, facilitate the restoration of mandibular continuity during surgery, and guide fracture reduction. However, it should be kept in mind that not being able to perform a CT scan beforehand for reduction and fixation may limit the feasibility of using 3D technology in a situation that requires urgent intervention, such as dental trauma [66].

3.7 Fluoride application

The topical application of fluoride faces challenges in maintaining a sufficient concentration in the oral cavity over an extended period as factors like food and continuous saliva flow can wash it away. In response to the limitations of commercially available fluoride formulations, 3D printing is emerging as a potential solution. It allows for the customization of fluoride formulations and enables the creation of a thin film that can be applied to the tooth surface (Fig. 4). This thin film serves as a covering layer that slowly releases fluoride and offers prolonged effectiveness [67].

Fig. 4.Fluoride application Fluoride adhesive film made by 3D printer is attached to the labial/buccal surface of the teeth [67]. NaF: Sodium fluoride.

3.8 Autogenous dental transplantation

Dental autotransplantation has emerged as an integral component of orthodontic surgical treatment for children and adolescents experiencing dental agenesis or non-preservable teeth. In autogenous tooth transplantation, 3D printing can be beneficial by enabling the construction of a new recipient socket with the assistance of a surgical replica of the tooth intended for transplantation. This enables an individualized preparation of the new tooth socket (neo-alveolus) before extraction of the donor tooth is performed. Subsequently, the donor tooth can be placed directly in the neo-alveolus. CBCT provides 3D measurement of the space and tooth dimensions. The tooth is segmented from tomography, and data are obtained as an STL file. 3D printing has enabled the production of biocompatible and sterile dental replicas for use during surgery [68, 69].

A multicenter prospective clinical study by Verveij et al. [68] evaluated a facial 3D autotransplantation procedure and analyzed the extra-alveolar time and number of fitting attempts during 3D-guided autotransplantation. The transplantation was performed with an extra-alveolar time of less than 1 minute and an immediate good fit of the donor tooth in most cases. In 4% of cases, the extra-alveolar time exceeded 3 minutes, but this time was within the safe limit for the protection of the periodontal ligament. The authors reported that this may help minimize the risk of damage to the periodontal ligament and prevent subsequent root resorption or ankylosis [68].

It has been reported that the application of 3D technology in pediatric dentistry has facilitated the procedure in autotransplantation. Cahuana-Bartra et al. [70] performed a dental transplant on a pediatric patient, and produced a surgical replica of the tooth was produced with 3D printing. The tooth was transferred to the planned location in a short time with a 3D copy and was shown to be successful during follow-up. It has been reported that 3D additive manufacturing technology is a suitable method for creating a copy of a tooth to be transplanted [70]. The use of 3D dental replicas created from radiological data can be a reliable, reproducible, and valid therapeutic solution with a favorable benefit-to-risk balance.

3.9 Anterior teeth restoration

Xia et al. [71] described an uncomplicated approach using a 3D-printed template and resin composites to restore and enhance the aesthetic appearance of the anterior tooth. In the presented cases, aesthetic restoration of the central incisors was carried out with the help of a template produced by 3D printing. Expected results were achieved, including appropriate color, tooth anatomy, and translucency of the tooth and the 3D-printed template was reported an acceptable and reliable alternative. The composite injection technique, which offers a complete digital workflow, and in recent case reports, it was used in the restoration of post-orthodontic treatment in the anterior teeth and teeth with microdontia. 3D-printed guides offer a non-invasive approach that can precisely transfer a design made in the software, reducing chair time and simplifying the direct composite restoration procedure [72, 73, 74].

3.10 Pediatric endodontics and regenerative treatments

Analyzing a complex root-canal system with obliterated and lateral canals using 2D radiographic images can be challenging. Using 3D-printed models of pediatric patients’ root canal architecture derived from digital data from CBCT scans can prove invaluable in treatment planning and access preparation, especially in complex root-canal cases or surgical endodontic procedures like apicoectomy [75, 76]. In this century, the focus in pediatric dentistry will be regenerative endodontics, where additive manufacturing plays a crucial role. It facilitates the delivery of stem cells, the production of biocompatible pulp scaffolds, and the creation of carrier membranes for platelet-rich plasma.

3D printing is instrumental in developing injectable calcium hydroxide molecules, growth factors, and gene therapy for regenerative endodontics. It also aids in the regeneration of the pulp-dentin complex by creating injectable calcium hydroxide molecules, growth factors, and gene therapy. Porous scaffolds developed through 3D printing using calcium hydroxide medicament and calcium phosphate cement can further contribute to the regeneration of the pulp-dentin complex [77, 78].