Benefits of Three-Dimensional Printing in Periodontal Therapy

Abstract

Periodontal disease is one of the most common dental and oral diseases suffered by people in the world, especially in Indonesia. The prevalence of this disease increases from year to year. The most important thing to prevent further destruction due to this disease is a correct and accurate diagnosis and treatment plan, one of which is using 3D (three-dimensional) printing in periodontal treatment. Three-dimensional printing is a process of building 3D objects by adding additional approaches. Using 3D printing, periodontal care procedures such as creating study models, scaffolds, preservation sockets, bone augmentation, and implant implantation can be completed.

1. Introduction

Dentistry technology has developed rapidly. One of the newest technological innovations in dentistry is the use of three-dimensional (3D) printing [1]. 3D printing is considered a disruptive technology that has the power to change the way products are produced. Recently, 3D printing has become a subject of great interest in dentistry [2]. 3D printing allows small quantities of customized items to be produced at relatively low cost. While currently 3D printing is used primarily for prototyping and mock-ups, some promising applications exist in creating replacement parts, scaffolds, dental crowns, and artificial limbs, such as in manufacturing bridges [3].

The term 3D printing is generally used to describe a manufacturing approach that builds an object one layer at a time, adding multiple layers to the shape of an object. This process is more accurately described as additive manufacturing and is also referred to as rapid prototyping [2]. Technology is slowly continuing to make its way into the field of dentistry. Researchers continue to strive to integrate technology into the field of dentistry. Of all the latest technological innovations in dentistry, the most discussed innovation currently is three-dimensional (3D) bioprinting [4].

2. 3D printing

The first 3D object was printed by Charles Hull in 1983 using Stereolithography. Although Francois Duret introduced digital dentistry in the 1970s, it was not readily accepted and took time to be integrated into current dental practice. Hull later founded 3D Systems, which produces the premier 3D printer “Stereolithography Apparatus”. In 1988, 3D Systems launched the SLA-250, the first commercially viable 3D printer [5, 6].

3D printing allows operators to produce objects with more complex designs and shapes using fewer materials than traditional manufacturing methods [7]. 3D printers work similarly to conventional laser or inkjet printers, rather than using colorful inks. 3D printers use a powdered or liquid resin that is slowly created from an image layer by layer. All 3D printers use 3D CAD (Computer-Aided Design) software that measures thousands of cross-sections of each product to determine exactly how each layer should be constructed. The 3D machine dispenses thin layers of liquid resin and uses computer-controlled ultraviolet lasers to harden each layer in a specified cross-sectional pattern. Excess soft resin is removed through a chemical bath at the end of the process [3]. 3D printing technology allows doctors to individually customize the production of body parts for the patient they are treating [7].

3. 3D printing technology

There are three main steps in carrying out the 3D printing process: the first step starts with data acquisition, namely obtaining a 3D object file. In the fabrication process using additive manufacturing technology, initially, 3D images are taken with the help of dental cone beam computer tomography or with medical magnetic resonance imaging, obtaining models from CBCT (Cone Beam Computed Tomography), MRI (Magnetic Resonance Imaging), or CT (Computed Tomography) [6]. Computed Tomography is then transferred to software for designing with the help of a computer, the second step is to create the data obtained with the help of computer software to refine the model so that the file is free from errors. The last stage is to gather the data. A 3D printer uses the revised model’s exported Standard Tessellation Language (STL) to create the appropriate physical model. The materials are selected appropriately, and the printer settings are adjusted for a high-quality 3D printed model [8, 9].

4. Applications of 3D printing in dentistry

4.1 In the field of education

The digital imaging and scanning process is coupled with powerful software and 3D printing, causing drastic changes in training patterns and educational standards globally in the health sector, especially dentistry. Three-dimensional printing allows duplication of orofacial anatomy with high precision. Highly advanced 3D printers can reproduce jaws and hard and soft tissue images, which will be helpful for education training [10].

Dental students can thoroughly understand the anatomical model of the head and the surrounding area because the shape produced by 3D printing resembles the original shape. Siefert et al. and Chen et al., in their research comparing 3D printing models to cadaver models in education, concluded that 3D models could be an alternative model to replace cadavers in providing and training surgical practice for students who will perform oral maxillofacial surgery. Accurate 3D printed models help surgeons to research and train in a variety of different surgical techniques. These trainings can reduce operative time, avoid production errors, and increase surgical success [11, 12].

Apart from improving skills in performing surgery, these 3D printed models can also be used to teach pre-clinical students how to train for fixed prosthodontic treatment. This exercise can provide benefits so that students can practice making crown and veneer preparations. These 3D printing tooth models are made to resemble natural teeth and are perfect for preparation [10]. In the field of orthodontics and craniofacial cases, 3D print documentation is essential, and 3D prints can replace conventional prints. During training, real models from patients are beneficial for making orthodontic appliances, both removable and fixed [13].

For pre-clinical students who will carry out dental restorations, this 3D printing also helps students recognize tooth structure and techniques in carrying out cavity preparation. Training in endodontics can also influence prototyping speed. Endodontic training is carried out on teeth with ideal root canal conditions that are the same as the condition of the extracted original tooth. 3D printing can be obtained using scans of the patient obtained from CBCT, producing good results where the prints can be made before surgery (pre-surgical) and after endodontic surgery. This can help deal with problems encountered during surgery, such as bone prominence, morphological complications, root curves, and proximity to nerve bundles. 3D printing is also advantageous in teaching students and improving their perception of normal or complex root canals and the stages of preparation techniques with various root canals, such as access preparation and cleaning-shaping of root canals [14, 15].

In pediatric dentistry, this 3D printing can help students perform the SSC (stainless steel crown) technique. Models from patient radiographs can be used to visualize the pathological conditions that occur in terms of appearance, size, and depth of the caries lesion and the complexity of the tooth [16].

The use of 3D printing in the field of periodontics in education is beneficial in training, such as phantom heads, intra-oral examination of patients, and measurement of periodontal indices. Students can also use 3D printed models to experience the sensation of measurements such as pocket measurements, recession, and other periodontal examinations [7].

4.2 In the clinical field

3D printing in clinical care can be used for surgical guides, models, occlusal splints, and implants. In implant surgery, maxillary and mandibular reconstruction, orthognathic surgery, and temporomandibular joint surgery can be done with the help of 3D printing [13]. 3D printing can be used as a guide for surgery because it can help correct implant placement. Surgical guides have been successfully used in all single-tooth implant surgery types, including sinus lifting, whole oral cavity, and zygomatic implants [17]. Surgical guides such as cutting, drilling, and positioning guides are useful in mandibular and maxillary surgery and can help reduce operative time and improve clinical and esthetic results [18].

Models that are 3D printed and precisely depict the patient’s anatomical state. The contour model represents a positive space model depicting the patient’s anatomy. It is a 3D printed object that can be used for preoperative training on the model and osteosynthesis pre-forming/pre-bending or reconstruction plates according to planned results. When performing jaw surgery to align the mastication and occlusion in the correct position, the splint will be placed in the patient’s mouth, replicating the location after surgery when the patient is in occlusion. This requires 3D printing designed with surgical software to match the condition [18, 19].

The application of 3D printing has resulted in a paradigm shift within the field of prosthodontics. Partial and fixed prostheses can be created without the hassle of a complete digital workflow involving scanning and printing. This digital prosthesis can be compared to conventional. The metal framework of removable partial prostheses can be obtained with excellent results and is easy to install. This causes errors to be eliminated, and this is related to laboratory procedures [20]. This condition aligns with the results of metallic full crowns and temporary acrylic crowns, which show good precision and margins when fitting compared to machined crowns. 3D printing can be used in ceramic restorations, molding, and other prosthodontic applications [21].

Recently, 3D printing has been used more frequently in orthodontics. Orthodontic appliances are made using CAD CAMs, intra-oral scans, and CBCT, with three-dimensional molding; ortho aligning can be done for crowded teeth. The use of occlusal splints with 3D techniques for TMJ disorders has been demonstrated by Salmi et al. [22] 3D printing can also be used in orthodontic brackets. The brackets are molded and adapted to the individual tooth surface. The bracket can be positioned accurately using 3D printing guides. Liu et al. use 3D printing of personalized archwire groove models to assist in giving the individual the appropriate archwire shape, and the process can be done easily and quickly. So, it can increase the effectiveness and perfection of manipulation and bending of wire arches. Additive manufacturing also allows various orthodontic devices, such as mouth guards, retainers, expanders, and apnea devices, to provide better intra-oral adaptation [23, 24].

3D printing in the field of endodontics is useful as a guide to cavity access, root canal treatment, and endosurgical procedures. In apical root canal lesions and calcified root canal conditions, a 3D printing model guide is also helpful in obtaining good results. Dimensional 3D printed guides used in root canal treatment can minimize measurement errors such as incorrect bur direction and root canal perforation, potentially hindering root canal treatment’s success. The accuracy and precision of 3D-printed intra-coronal restorations are higher than conventional methods [7, 25].

Specific Implant patients use implants to repair defects in the cranio maxillofacial, which are related to cases of tumor, trauma, infection, or congenital deformity. This implant is made from polymer, titanium metal, and other compatible materials. During surgery, a mold is made of the patient’s specific implant. This innovative technique has been used for many years for temporomandibular joint reconstruction and, more recently, for surgical rehabilitation in orthodontics [26]. 3D reconstruction of the skeletal frame on the contralateral (fit) side is used for mirroring. The main advantages are that this procedure replicates symmetrically in its use, is very accurate, and can predict the day after surgery. This is not only used on hard tissue but also on soft tissue that is planned to be placed [19].

In periodontal treatment cases, 3D printing can be used as a surgical guide to obtain zone esthetics in periodontal surgery. To obtain accuracy and precise treatment from gingival surgery, surgical template models are made with 3D printing. Besides, this mold can also help make scaffolds in regenerative periodontal surgery. The scaffold used can be obtained from 3D printing, namely bioprinting [7].

5. The role of 3D bioprinting in periodontal treatment

In dentistry, 3D printing has diverse applications and is a promising technology, potentially leading to new and exciting treatments. The use of 3D bioprinting technology for various applications has been proven to provide successful patient treatment options. Apart from rapid prototyping, currently, 3D printing can be used in various applications in dentistry, such as producing models and making scaffolds to help the periodontal regeneration process [27].

3D bioprinting is the first technology in the field of regenerative treatment that allows the creation of living tissue using living cells through a printing process. Periodontitis has become a more common disease among the public; thus, there is a need to increase periodontal regenerative procedures to restore normal periodontium for patients. Regenerative procedures require the placement of biocompatible tissue that is bioresorbable, supporting cell growth and proliferation in repairing the damage. Such structures can be created from 3D bioprinting technology that uses multiple bioinks and various bioprinting methods such as autonomous self-assembly, extrusion-based, and laser bioprinting to print tissue [1].

Imaging biomedical systems such as Cone Beam Computer Tomography is a valuable tool in the field of periodontics for diagnosing and better planning treatment by enabling visualization of disease, implant placement, and topography of the bone. Imaging CBCT provides scope for developing personalized scaffolding. CBCT topography data can be used to create a three-dimensional resolution image of the potential scaffolding, which can then be precisely erected over the damaged area. Three-dimensional printing has been applied to the development of polymer or ceramic scaffolds, as well as the creation of surgical guides and multiple scaffolding regeneration generations for clinical usage. A “system scaffolding bioactive” meant for network regeneration and repair can be created by combining this scaffolding technology with biological therapies or cells [28]. Periodontal tissue has a complex organization that requires the construction of multi-layered biomaterials to restore structural and functional integrity to the bone and periodontal ligament surfaces [29].

Periodontitis is an inflammatory disease caused by periodontal pathogens. The interaction of periodontal pathogens with host cells will affect the periodontium, causing tissue damage [7]. Damage that occurs to periodontal tissue will cause problems for the sufferer. Periodontal treatment is performed to treat and prevent further periodontal destruction. Periodontitis treatment aims to control inflammation through mechanical plaque removal and regenerate the periodontal. Conventional periodontitis treatment can only achieve long junctional epithelial attachments, so it cannot achieve total periodontal regeneration [30]. The need for treatment to achieve periodontal regeneration is increasing. Therefore, much clinical research is ongoing in 3D bioprinting to restore lost periodontal structures for individuals suffering from periodontitis. The periodontium structure has a quite complex morphology and requires special technical knowledge in the printing process [1].

Bioprinting is an advanced technology in the field of regeneration that facilitates tissue creation. Bioprinting is a technique used to design complex biological structures using bioinks. Before gaining insight into 3D bioprinting of the periodontium, it is important to understand the evolution of 3D bioprinting in the medical field [1, 4]. 3D bioprinting is a cutting-edge technology in the regeneration field facilitating multi-scale, biomimetic, multi-cellular tissue fabrication with highly complex tissue environments, intricate cytoarchitecture, structure–function hierarchy, and tissue-specific composition and mechanical properties [4]. As the term bioprinting implies, the process involves printing living tissue. This is done using a 3D bioprinter with a model designed on a computer. In this model, the bioink is coated through an additive manufacturing process to create tissue that imitates natural tissue [31].

6. Steps in 3D bioprinting

Several steps that are important to pay attention to in 3D Bioprinting are Pre-bioprinting: This step is the first step in the printing process, where the structure to be printed is designed and modeled as a 3D structure using Computed Tomography (CT) and MRI scanning. Every fine detail is recorded, and tomographic reconstruction is performed on the image to be printed in layers. Then, the bioink is prepared by isolation from living tissue and allowed to grow [7, 31]. The next step is bioprinting: in this process, bioinks are inserted into a printer cartridge, and based on a digital model, cells are accumulated in layers [32]. The post-bioprinting step involves maintaining the mechanical integrity and function of the 3D printing structure. In this step, tissue remodeling and growth are controlled by sending signals. More recently, the evolution of bioreactor technology has resulted in rapid tissue maturation, tissue vascularization, and increased transplant survival rates. The bioreactors differ depending on the tissue type [31, 33].

7. The role of bioprinting in periodontal regeneration

Periodontal tissue has a complex structure that requires multi-layered biomaterial construction to restore structural and functional integrity to the bone and ligament surfaces [7, 29]. Using additive biomanufacturing technology, periodontal regeneration may create hierarchical scaffolds that mirror the architectural characteristics and configurations of the periodontium, which is made up of hard and soft tissues including cementum, alveolar bone, periodontal ligament and gingiva. These scaffolds are called multiphasic constructs, as they have various compartments that recapitulate the original structure of the periodontal complex and are helpful in periodontal regeneration treatments [33, 34]. The main cells involved in periodontal regeneration are cement oblasts, osteoblasts, and periodontal fibroblasts. One source of renewable cells is stem cells. The several phases of periodontal regeneration include cell adhesion, migration, proliferation, and differentiation [35]. 3D printing innovation is a groundbreaking technology resulting in a paradigm shift in periodontal treatment. This helps in treatments such as installing dental implants, surgical guides, anatomical models, and so on, using computer-aided design data [7, 29].

Tissue engineering is one of the top areas of research interest in the medical field today. This process combines biological theory and engineering principles, helping injured tissue or organs recover and restore function through germ cells, biocompatible scaffolds, and bioactive factors [36]. Periodontal regeneration has been a research focus in oral tissue engineering for a long time. Guided tissue regeneration (GTR) is a common regeneration operation in periodontology [37].

The goal of regenerative tissue engineering is the regeneration of tissue and organs, either through the in vivo implantation of biomaterials in the form of grafts or the in vitro creation of replacement materials enriched with growth factors and cells, which are then transferred into the body at the defect site to promote regeneration. Tissue engineering is an interdisciplinary field encompassing stem cell biology, chemistry, materials science, medicine, and the production of biomaterials [38].

The environment surrounding periodontal defects can greatly influence the success rate of guided tissue regeneration (GTR), and biocompatible scaffolds provide a stable healing environment for periodontal tissue restoration. Therefore, making suitable scaffolding is very important. Due to the limited area of periodontal defects, constructing a scaffold appropriate to the size of the defect is challenging. Due to its high accuracy and efficiency, 3D bioprinting is becoming a new strategy. Existing 3D bioprinting methods are mainly divided into extrusion, droplet-jet bioprinting, and photocuring-based bioprinting [39]. When it comes to 3D bioprinting, bioink is unavoidable. The main material in 3D bioprinting is the composition of biocompatible materials, bioactive factors, and cells to create the final shape of the intended construction, determining the properties and biological features of the 3D bioprinting scaffold, which ultimately influences the results of periodontal tissue restoration [40].

A PCL (Polycaprolactone)—PGA (Polyglycolic Acid) scaffold created by manufacturing computers overcome these problems. This scaffold consists of special compartments of periodontal ligament and bone. Indirect 3D printing is used to create hybrid scaffolds. According to Park et al., to prepare the mold, the design of the pore size, channel orientation, and tissue-specific compartments is given great attention. Following fabrication, a PCL or PGA polymer solution is cast into the mold. Both compartments are combined with a thin layer of PCL to form a single scaffold. Mouse subcutaneous pockets were used to evaluate biomimetic random hybrid scaffolds for tooth and ligament surface engineering. They demonstrate the capacity for bone and periodontal ligament regeneration as well as the formation of parallel and obliquely oriented fibers. Adjustments were made to the design to simulate periodontal tissue better [41].

As an expansion of the biphasic scaffold, Lee et al. created the triphasic scaffold. Its goal is to incorporate different tissue regeneration. Using fused deposition modeling, the scaffold was made with compartments for the periodontal ligament, alveolar bone, and cementum/dentin contact. Biological cues and biophysical characteristics are anticipated to promote periodontal tissue regeneration. One design drawback of the PCL scaffold is its stiffness, which makes it challenging to adapt to the intricate 3D anatomy of different periodontal abnormalities [42].

Although 3D bioprinting technology has been available for many years, the high cost of 3D bioprinters, high energy consumption, operation and maintenance costs, clearance from ethical boards for using cells, and the requirement of trained operators have proven to be barriers to its development. Periodontal tissue engineering aims to use cells, scaffolds, and signaling molecules to restore the structure and functionality of both hard and soft tissues. The size of bone defects in periodontal disease varies, ranging from microscopic intraosseous flaws to massive horizontal and vertical bone defects that are significant in implant rehabilitation and periodontal healing [43]. For decades, efforts have been made to achieve predictable and reliable bone regeneration using various methods to improve the results of periodontal treatment.