Modern digital pediatric dentistry with the advent of intraoral sensors, computer-aided design/computer-aided manufacturing, and three-dimensional printing technologies: A comprehensive review

Mohammad Kamran Khan

doi:10.4103/jdrr.jdrr_83_22

REVIEW ARTICLE

Year : 2022 | Volume : 9 | Issue : 3 | Page : 195-201

Modern digital pediatric dentistry with the advent of intraoral sensors, computer-aided design/computer-aided manufacturing, and three-dimensional printing technologies: A comprehensive review

Mohammad Kamran Khan
Department of Pediatric and Preventive Dentistry, Faculty of Medicine, Aligarh Muslim University; Private Pediatric Dental Practice, Aligarh, Uttar Pradesh, India

Date of Submission	28-May-2022
Date of Acceptance	15-Jun-2022
Date of Web Publication	14-Nov-2022

Correspondence Address:
Mohammad Kamran Khan
Hamdard Nagar-A, Civil Line, Aligarh, Uttar Pradesh
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jdrr.jdrr_83_22

Abstract

The conventional methods of fabrication of the dental prosthesis/appliances in pediatric dental patients pose many challenges such as prolonged and multiple appointments, discrepancy in the accuracy of the fit of prosthesis, and cumbersome dental laboratory procedures. The conventional impression-making procedures in young children are regarded as quite cumbersome and difficult due to several clinical factors in dentistry. In recent years, digital Intra-Oral Sensors (IOS), three-dimensional printing (3D-printing) technology and computer-aided design/computer-aided manufacturing (CAD-CAM) technology have been described in existing literature related to different aspects of pediatric dentistry. The aim of the current study was to review the literature related to recent innovative applications of IOS, CAD-CAM, and 3D-printing technology in modern pediatric dentistry. Pediatric dental procedures involving the modern digital technologies such as IOS, CAD-CAM, and 3D-printing in the applications for the digital impression procedure and the fabrication of various types of dental appliances have the good potential to deliver optimum oral-health care in children. Furthermore, it can help in motivating the children and also in instilling the positive attitude and behavior toward dentistry.

Keywords: Computer-aided design/computer-aided manufacturing technology, contemporary digital dentistry, digital-impression technique, intraoral sensors, modern digital pediatric dentistry, three-dimensional printings technology

How to cite this article:
Khan MK. Modern digital pediatric dentistry with the advent of intraoral sensors, computer-aided design/computer-aided manufacturing, and three-dimensional printing technologies: A comprehensive review. J Dent Res Rev 2022;9:195-201

How to cite this URL:
Khan MK. Modern digital pediatric dentistry with the advent of intraoral sensors, computer-aided design/computer-aided manufacturing, and three-dimensional printing technologies: A comprehensive review. J Dent Res Rev [serial online] 2022 [cited 2023 Mar 22];9:195-201. Available from: https://www.jdrr.org/text.asp?2022/9/3/195/361141

Introduction

Rendering the optimum dental care to pediatric dental patient and to children with special health care needs is a primary objective in pediatric dental practice. However, current evidence-based dental innovations and advancements are needed to be included in pediatric dental services to deliver the optimum oral health care and also to inculcate the positive dental attitude and to enhance the compliance in children toward dentistry. In the recent decade, many novel inventions relevant to pediatric dentistry have emerged and have been introduced to overcome the shortcomings of the existing techniques in dentistry. Delivering the dental care to child patient in stress free and friendly manner is the most desirable outcome for any formulated dental treatment plan.

Pediatric dental patients requiring dental prostheses such as removable space maintainers, resin-based partial dentures, customized mouthguards, occlusal splints, prosthetic crowns, myofunctional appliances, and habit-breaking appliance undergo impression-making procedure, and that is considered the most challenging for dental professionals owing to manage the children's behavioral problems, gagging reflex, foreign body aspiration, and chocking (breathing) concerns.^[1],[2],[3] Earlier and still conventional impression-making methods are still prevalent and are being practiced to record the hard and soft tissues of the oral cavity in children and that is regarded as clinically quite cumbersome and difficult due to several factors.^[1],[2],[3] The conventional methods of fabrication of the dental prosthesis and appliances for managing oral and dental problems in pediatric dental patients also pose many challenges such as; prolonged and multiple dental appointments, delayed delivery of dental appliances/prosthesis, discrepancy in the accuracy of the fit of prosthesis, and cumbersome dental laboratory technical procedures.^{[1],[2],[3],[4],[5],[6],[7]}

Modern dentistry is evolving to overcome the drawbacks or demerits of the traditional techniques. In recent years, the advent of advanced digital intraoral scanners in the field of dentistry has been reported to be quite beneficial to dental patients and clinicians because of various advantages of IOS over traditional impression-making method in the fabrication of different dental prostheses/appliances.^[1],[2],[3] Computer-aided design/computer-aided manufacturing (CAD-CAM)/three-dimensional printing (3D-printing) technology is expanding into the pediatric dentistry field in the construction of various types of prostheses and appliances and also in different kinds of dental treatment modalities.^{[1],[2],[3],[4],[5],[6],[7],[8],[9],[10]} Recently, several original research and case-report articles have been published in existing literature regarding the scientific evaluation and assessment of IOS, CAD-CAM, and 3D-printing technology in different fields of dentistry.^{[1],[2],[3],[4],[5],[6],[7],[11],[12],[13],[14],[15],[16],[17],[18],[19],[20]} Knowledge and awareness about such modern technologies among dental-health-professionals are of paramount importance to enhance the prudent use in pediatric dental procedures with scientific evidence-based approach. However, in existing literature, there is scarcity of comprehensive literature review articles in the context of different aspects of Digital CAD-CAM/3D-printing technology relevant to pediatric dentistry. Hence, the present article has attempted to comprehensively review and highlight the recent significant dental literature pertinent to modern digital technologies/techniques such as intraoral scan (IOS), CAD-CAM, and 3D-printing in the applications of various types of dental appliances or prosthesis and/or dental procedures in the domain of pediatric dentistry.

Methodology

The searches of the electronic databases such as PubMed/MEDLINE, Scopus, Web of Science, Scielo, and Cochrane were carried out for scientific articles related to include them for the literature review comprehensively. The searches for the relevant articles were accomplished using the combinations of the keywords such as; “CAD-CAM technology in dentistry;” “Digital dentistry with CAD-CAM and 3D printing;” “Digital Impression technique;” “ Digital Intra-oral Sensors (IOS) in dentistry;” “Digital Scanning method of Impression-making;” “3D-printing/CAD-CAM in Pediatric Dentistry;” “Digital CAD-CAM/3D-printing technology in dental Prosthesis;” “CAD-CAM/3Dprinting in Orthodontic appliances;” “CAD-CAM/3D printing in pediatric dental procedures;” and “3D-printing techniques in dentistry.” Orginal research articles, cross-sectional, case reports, scientific reviews, narrative reviews, and systematic reviews in English language were included. However, articles such as Editorials, letters to the editor, and opinion articles were excluded. No time limits were applied for searching and screening of the articles. Initially, more than 41 articles were retrieved from different electronic databases. However, after the screening of the full texts of the initially retrieved articles, finally, 26 articles were considered relevant to include in the current literature review article.

History of digital dentistry with evolution of computer-aided design/computer-aided manufacturing and three-dimensional printing technique

The possibility of acquiring an optical imprint was hypothesized in the 1970s by François Duret, who is considered as the father of “modern digital dentistry.” In fact, he was the first to produce a dental crown by using CAD software (1983). Charles Hull in 1983 invented 3D-printing technology that is called as “Stereolithography.” Charles Hull is regarded as the “Father of 3D Printing technology.” In earlier 1980s, 3D technologies were known as rapid prototyping technologies. Emanuel Sachs in 1992 created the phrase “3D Printing.” Otherwise, it was earlier also known as “additive manufacturing” but now is famous as 3D printing.^[4] Moreover, Hull created the Standard Tessellation Language (STL) file format. STL file is a triangular representation of an object's surface geometry. Each object is built of many triangles and the peak of each triangle is represented by the coordinates system. In 1985, the first chair-side CAD/CAM-generated-inlay was fabricated by using a ceramic block (fine grain feldspathic ceramic). Since 1980s, various CAD/CAM systems have been developed, for example, CEREC. The development of 3D printing was first done by Scott Crump. Hull developed a new 3D-printing process/technique named as “Fused deposition modelling” (FDM).^[5]

The CAD-CAM technology utilizes “subtractive manufacturing” technology that lacks accuracy and that could not completely replace the manual involvement/operation as compared to 3D scanning technology for designing the 3D objects. The advent of digital intraoral scanners (IOS) and also the availability of 3D printers with compatible materials increased the use of 3D-printing methods.^[6] Additive manufacturing is a process of manufacturing the 3D objects from a 3D-model or digital computerized file. Additive manufacturing consists of several techniques to build the 3D objects by “layer by layer” manner.^[7]

Techniques of three-dimensional printing

The digital 3D-printing technology can be accomplished by different types of techniques such as; stereolithography, fused filament fabrication FDM, selective laser sintering/Melting and Electron Beam Melting, digital light processing, Inkjet 3D-Printing and Polyjet.^{[2],[4],[5],[6],[7]}

Concept and mechanism of acquiring the digital impression through digital intra-oral scan

Intraoral scanners (IOS) are devices for recording the direct optical impressions of oral structures. IOS is a device composed of hardware, i.e., camera, a computer monitor, and a software program. These devices project a light source (laser or structured light) onto the object (e.g., dental arches) to be scanned.^[8] The objective of IOS is to record the 3-D geometry of an object (e.g., teeth/dental arch) with precision. The most commonly used digital format or file for digital impression is the Standard Tessellation Language/stereolithography/Standard Triangle Language (STL). This format is described as a succession of triangulated surfaces in which each triangle of STL file is composed of three points having cartesian coordinates (x, y, and z) and a normal surface. Besides that, some other digital files have also been generated to record/capture the color, texture or transparency of orodental tissues (e.g., Polygon File Format, PLY file). Regardless of the type of imaging technology employed by Intraoral scanner, all cameras consist of projection of light which is subsequently recorded as the individual images or video and then compiled by the software after recognition of the points of interest (POI). The x and y coordinates of each point of the triangle are evaluated by software on the image, and the coordinate (z) is then calculated depending on the distance to object technologies of each camera. Such POI can be captured by identification of transition areas like pronounced curvatures, the physical limits, or the grAy intensity's differences, i.e., shape-from-silhouette. Subsequently, the transformation matrix is then calculated to evaluate the similarity among all the images, for example, homothety or rotation. The extreme points are statistically removed to reduce the noise. Consequently, each coordinate of the triangle (x, y, and z) is extracted from the digital projection matrix, and ultimately the STF file is made.^[9]

Materials used for the fabrication of appliances/prosthesis using computer-aided design/computer-aided manufacturing/three-dimensional printing methods

The 3D-printed objects/dental appliances/prosthesis can be prepared using variety of materials such as; Polycaprolactone, Polylactic acid, Acrylonitrile butadiene styrene, Polylactic glycolic acid, Ceramic, Hydroxyapatite, Plaster, Metals (Ti-Zr alloy, titanium alloy, Co-Cr alloy).^[6],[10]

Applications of digital IOS, computer-aided design/computer-aided manufacturing, and three-dimensional printing technology in pediatric dentistry

Various applications of digital intraoral sensors (IOS), CAD-CAM, and 3D-printing technology related to dentistry as reported in recently published scientific literature are summarized in [Table 1].

Table 1: The various applications of digital intra-oral sensors, Computer-aided design-computer-aided manufacturing, and three-dimensional-printing technology related to dentistry as reported in recently published literature

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In the making of digital scanned impression of the oral tissues

The IOS have revolutionized the impression-making procedure in dentistry by making it more comfortable and acceptable to the patients, especially young patients. In addition, the manufacturing process has also become much faster and easier with its digital workflow through the STL file transfer to the digital dental laboratory without any problem as was used to be associated with the conventional impression-making procedures.^[1],[3],[9]

In the fabrication of space maintainers

The digital 3D intraoral scanners have been employed to capture the replica of topography of the hard and soft tissues of the oral cavity to construct the space maintainers either CAD-CAM or 3D-printing technology with improved accuracy and ease in digital work-flow.

Recently in a case report, an intraoral scanner (IOS) was used to acquire the digital impression for the construction of a fixed space maintainer (lingual-holding arch space maintainer) for mandibular dental arch in mixed-dentition stage of a pediatric patient. It was reported that this contemporary impression method was able to decrease the chair-side time (shorter procedure) with an uncooperative patient, enhance patient comfort and compliance.^[11]

In recent years, a published article reported the usage of a novel technology called 3D-printing technology/additive manufacturing technique/desktop fabrication method for the construction of the Band and Loop space maintainer for a pediatric patient with mixed-dentition stage. The dental cast was scanned digitally using the 3D-digital dental scanner and subsequently digitally fabricated.^[12]

A recent published article reported that a removable space-maintainer can be fabricated in pediatric patients by CAD-CAM technology with Polyether ether ketone (PEEK) material after recording the digital impression using the IOS.^[13]

A published pilot study recently on children, reported the successful use of CAD-CAM technology to fabricate orthodontic space maintainers using PEEK polymer by taking extraoral scanner for taking the digital impressions of the poured models of the pediatric dental patients. Such space maintainers made of PEEK material were proved to be successful in terms of comfort, satisfaction, and of minimally visible SM. Moreover, these appliances were observed suitable to maintain the dental arch space and were dimensional stable, mechanically strong with good biocompatibility for oral tissues.^[14]

Prosthetic dentistry-cleft lip cleft palate patients

Impression-making for fabricating the feeding appliance or obturator in a newborn/infant with cleft lip and palate (CLCP) is considered a cumbersome, risky, and technique-sensitive procedure due to foreign body (impression material) dislodgement (aspiration) or airway obstruction. However, the advent of digital dental technologies and intraoral scanning techniques has been reported in recent literature to facilitate safer, effective, and accurate intra-oral impressions for CLCP pediatric patients. In a published article, a digital intraoral scan was compared with a conventional alginate impression for taking the impression of the cleft region of the lip and palate. The digital scanning of the cleft regions for impression-making was observed rapid, precise, and safer in comparison to a traditional impression technique using alginate impression material.^[15]

A recent article described the three-dimensionally printed obturators called D-clefts and that are prepared by the 3D-printing technology to facilitate the feeding through milk-bottle for proper nutrition in neonates with CLCP.^[16]

A case-report demonstrated the clinical application of digital impression of the oronasal fistula in pediatric patients for making the digital 3D-cast/model and subsequently, palatal obturator/speech aid appliance was made by curing the acrylic resin material over the 3D-printed cast of the patents. Favorable outcomes were received from the patient and parents/caregivers in terms of comfort, managing the behavioral problems of the child, and also the good retention and stability of the appliance.^[17]

Restorative dentistry

An article reported a case-report in which digital impression using IOS in pediatric patient for the immediate zirconia crown-fabrication with the help of digital workflow of chair-side CAD-CAM technology. The immediately delivered restoration (zirconia crown) after pulpectomy was found with good clinical outcomes in follow-ups such as no fracture/chipping, discoloration, and it showed an excellent marginal fit without any plaque accumulation.^[18]

For the expansion of constricted maxillary arch

A recent published article presented the two cases of constricted maxillary arch treated by “ZeroExpander” a CAD-CAT digital automatic metal-free fixed appliance. Zero-expander was reported as preprogrammed device to expand the narrow dental arch in both deciduous and mixed dentition stages of the pediatric age group. In a patient having deciduous dentition stage was treated with ZeroExpander made of PEEK material while the other patient with a mixed-dentition stage treated with Zero-Expander made of PA12 material. Both of the patients in their case report were treated successfully with palatal expansion using such innovative CAD-CAT technology.^[19]

Rapid maxillary expansion

In a study done by Sánchez-Riofrío et al. reported a palatal expansion in pediatric patient with the help of cone-beam computed tomography (CBCT) scan and CAD-CAM technology in which A maxillary expander made of titanium grade-V, along with two mini-screws and a 3D-printed surgical guide were employed. Favorable clinical outcomes were depicted with 3D images. Mid-palatal suture separation of 3.63 mm in parallel fashion, a higher palatal volume as well as enhanced inter-canine and inter-molar width were reported. In addition, changes in the facial soft tissue were observed with an expansion of the nasal airway and alterations in the nasal morphology.^[20]

Myofunctional appliance

These appliances are used in pediatric age-group with growth potential for the correction of certain malocclusion. Several types of myofuncional appliances manufactured from conventional technique are used for specific malocclusion in growing patients. However, the traditional ways for the fabrication of such appliances are quite lengthy and cumbersome. Recently, functional regulator of Type-3 (FR3) constructed by CAD-CAM technology was investigated in laboratory to analyze certain mechanical properties in comparison to conventional FR3 and in which CAD/CAM-made-FR3 showed superior mechanical properties. Further in future clinical studies were suggested to investigate if such special appliances can serve as substitute/alternative to conventionally made FR3 in dental practice.^[21]

For para-functional habits bruxism and temporomandibular joint disorders

Bite splints/occlusal splints are commonly used for parafunctional habits (bruxism), temporomandibular joint -related disorders and also for disharmonious-occlusion problems. Conventional these appliances are prepared using manually by acrylic resins or vacuum thermoforming methods. However, in a recently published article, CAD/CAM technology using two types of process of fabrication, i.e., milling and 3D printing was investigated for the accuracy of bite splints. In terms of accuracy, both types of CAD-CAM process, i.e., milled and 3D printed for bite splints are found comparable and to be of equal quality.^[22]

For dental educational purposes

It has been reported in recent literature that 3D-printed models for simulation of caries to perform pulpotomy and fabrication of stainless-steel crown. Such digital models made from patient's radiographs can assist in visualization of the dental caries lesion in terms of its extent and size and also aids in demonstrating the morphological complexities and specific variation of tooth structure. Hence, digital dentistry using digital scanning for impression, CAD-CAM, or 3D printing has potential to be a complementary educational tool for effective dental education.^[23]

In sports dentistry

CAD-CAM/3D printing technology can be utilized for the fabrication of mouthguards in sports. Consequently, such protective gears for sports can be delivered quickly to the sports-related people, especially children and adolescents.^[25]

Management of dental and maxillofacial trauma

In dental traumatology, the role of splints is critical in a certain type of dental injuries to stabilize the repositioned teeth. Custom-made splints made by using the digitally scanned information from a CBCT scan can be possible in future as mentioned in recent literature and hence, will enable the fabrication of such a customized splint.^[4]

Pediatric patients with oral-maxillofacial trauma and accompanied malocclusion require prudent treatment plans considering that the growth of bones and development of tooth germs should be negatively affected. An article reported that a combination of digital dentistry involving the CAD/CAM, 3D printing in positioning the bite plane for the surgical guidance in the treatment of an unstable fracture of mandible.^[26]

Removable orthodontic retainers

CAD-CAM and 3D-printing techniques along with CBCT have also been mentioned and described in literature for making the customized removable retainers in orthodontics.^[24]

Advantages of digital dentistry in pediatric dentistry

Accuracy/precision

In contrast to traditional dental casts/models might which have inherent technical errors and distortions, 3D-printed digital models (appliances/prostheses) are more accurate as well as less number of clinical and laboratory steps without manual work in processing. Impression materials having inherent shrinkage, distortion are avoided with such techniques.^{[1],[2],[3],[11]}

Comfort to the patient

No elicitation of gag reflex, no risk of foreign body aspiration, or dislodgment of impression material into the cleft region are some of the advantageous factors for patient's safety which are offered using digital impression using IOS as reported in existing literature. Therefore, the digital scanning procedure for intraoral impression has been reported more comfortable for the pediatric patients and more accepted by the pediatric and their parents/caregivers for dental procedures in comparison to traditional impression technique.^{[1],[2],[3],[11]}

Faster processing of prosthesis/appliance fabrication

Owing to the absence of analogic conventional dental impressions, dental professional can directly send digital STL files to digital dental laboratory for further processing, leading to digital workflow with rapidly. There is faster fabrication of the appliance/prosthesis from the 3D printer. The proper powder ratio of the impression material, handling of the mix, waiting for the material to set and selection of the appropriate size impression tray are not required in the digital IOS.^{[1],[2],[3],[11]}

Digital impressions have the potential to increase efficiency along with the enhanced comfort for the patient, and also reduce the long-term costs/expenses of the dental procedure. Digital impressions using IOS have been employed routinely in other specialties of dentistry, and now emerging in the field of pediatric dentistry successfully that can be beneficial to the patients and the dental professionals. A previous study reported that 77% of patients preferred the intraoral scanning method than conventional impression-making method with alginate because of the provided comfort.^[11] Furthermore, the IOS are environment-friendly because no disposal of wastage of the impression material is needed as in the case of conventional impression materials.

All the above-mentioned factors are critical to manage the young pediatric dental patients in terms of favorable clinical behavior for rendering the optimum dental treatment effectively and efficiently.^[1],[11]

Disadvantages of digital workflow and computer-aided design/computer-aided manufacturing/3D-printing technology

Higher cost of the digital devices and machines: As compared to the analogic workflow (traditional dental procedure). Longer learning curve: The specific and advanced knowledge and training is required for dentists to use the IOS and to perform the digital workflow. The suitable size of the IOS for scanning inside the oral cavity is another crucial factor, especially for child patient requiring impression-making for dental prosthesis/appliance.^{[10],[11],[25]} There is a requirement of referral to special and specific digital dental laboratories for 3D printing/CAD-CAM processing for digital workflow.^[10] There may be health risk associated with 3D-printed prostheses/appliances because of the uncured resins of monomers or polymers.^{[10],[11],[25]} Moreover, as 3D-printing machine generates the product through layer-by-layer technology, and thereby in certain conditions it may delaminate under certain stresses or orientations.^{[10],[11],[25]}

Future perspectives

Digital dentistry using devices and machines integrated with digital computerized technologies should be made easily available and accessible in cost-effective manner for the dental professionals and thereby, it can be highly beneficial for the contemporary pediatric dentistry. Digital pediatric dentistry using IOS/CAD/CAM/3D printing has significant scope in the field of contemporary pediatric dentistry.

Conclusion

From the current review article, it can be concluded that pediatric dental procedures involving the modern digital technologies such as IOS, CAD-CAM, and 3D-printing in the applications for the digital intraoral scanned impression-making procedure and in the fabrication of various types of prosthesis or orthodontics appliances have the good potential to render the optimum dental care in pediatric patients. Furthermore, it can motivate the dental patients and can also instill the positive and cooperative behavior and attitude toward dentistry. However, further clinical researches/studies are required to assess the different clinical aspects and factors of the digital dentistry involving IOS, CAD-CAM, 3D printing in various pediatric dental procedures.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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