Contemporary orthodontic diagnosis and treatment planning require an extensive clinical examination and evaluation of diagnostic records. Routine orthodontic records, which include plaster study models, radiographs and photographs, can now be supplemented with three-dimensional (3D) digital scanning of the face and craniofacial skeleton. These 3D digital scans, supported with advanced software functions, can provide more detailed, in-depth and accurate information about craniofacial morphology and volumetric information on functional spaces.

3D digital information can be of immense value in considering different treatment options, simulating treatment outcomes, and maintaining records without using physical storage space.

Recent technologies include 3D imaging of craniofacial skeleton with low dose computed tomography such as cone beam computed tomography (CBCT), non-radiation facial scanning, digital models, virtual treatment planning, their integration and 3D printing. The focus in orthodontics has shifted towards 3D volumetric analyses of the spaces of the stomatognathic system.

The common terminology used in 3D imaging is provided in Table 35.1 .

The workflow in orthodontics can be defined as a sequence of clinical and laboratory processes through which the diagnosis, analysis and treatment goals can be achieved. A typical sequence of procedures in orthodontics diagnosis, treatment planning and execution of treatment involves:

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  Clinical case history taking

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  Diagnostic Records Acquisition, including:

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    Photographs

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    Radiographs

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    Study/working models

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  Case analysis

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  Appliance design and fabrication in orthodontic laboratory

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  Appliance delivery

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  Evaluation of treatment

In the past decade, with the introduction of 3D face scanning, CBCT imaging and intraoral/desktop 3D scanners, the orthodontic clinical practice has entered the digital era. These recent digital technologies have brought a paradigm shift in orthodontic practice by providing a smooth digital workflow from diagnosis to execution of orthodontic treatment.

Contemporary technology in digital orthodontic office ^, ( Figs 35.1 )

3D digital data recording

• 1.

  Scanning of dentition and occlusion (direct intraoral scanning/impression/plaster model scan)

• 2.

  Face scanning

• 3.

  3D scanning of craniofacial skeleton with CBCT.

Comprehensive digital workflow in orthodontics.

Virtual patient and data analysis and treatment planning:

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  Virtual patient creation by integration of above mentioned technologies

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  Analysis of digital models of the dental arches

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  Virtual treatment planning and dental set-up

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  3D cephalometry

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  Volumetric analysis of functional spaces in oral and nasal airway

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  3D orthodontic virtual treatment objectives

Appliances and treatment:

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  Appliance design and fabrication

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  Customisation of brackets

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  Treatment execution

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  Robotic wire bending

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  3D printing of models and clear aligners

Monitoring and follow-up:

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  Monitoring treatment with remote technology.

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  Evaluation of treatment changes.

The 3D evaluation of facial soft tissue morphology is vital in orthodontic practice. The face can be scanned with radiation methods with multidetector computed tomography (MDCT) or methods that allow 3D topography evaluation but without the hazards of the X-rays. Several attempts have been made to measure the 3D complexity of human face, with different techniques such as stereophotogrammetry, image subtraction technique, laser scanning, light luminance scanning and video systems. Recent advances in computer technologies have made 3D facial scanning accessible in day-to-day clinical practice.

Smartphones loaded with LiDAR (light detection and ranging) and TrueDepth technology make them efficient in scanning 3D structures. Laser and stereophotogrammetry surface imaging are widely used in medical/dental fields. ^,

Light detection and ranging technique (LiDAR)

This technique is based on laser energy and depth sensor technology. Concentrated light beams are generated, and time is calculated for the depth sensors to receive the reflections, like a radar, to create a 3D image.

Although there were significant differences (3 mm) between the images of CBCT and by Bellus3D Dental Pro, the study concluded that in cases where the accuracy range is more than 3 mm, mobile apps can be used to conduct the 3D face scan.

Commercially available 3D facial imaging systems and their technical aspects are summarised in Table 35.2 .

TABLE 35.2

Commercially available 3D facial imaging systems

S. no.	Facial Imaging System	Company Name and Location	Facial Imaging Features
1	3dMD	3dMD LLC 3200 Cobb Galleria Parkway, #203 Atlanta, Georgia 30339 USA Home	3dMD is a non-radiation 3D medical imaging system. It is available in various modules for different body parts
2	Di3D	Canfield Scientific Vectra 3D, Parsippany, New Jersey, USA	It involves two off-the-shelf digital single lens reflex (SLR) cameras and requires no bright white lights, no pattern projections, and especially no lasers. It works by triangulating the high-resolution images shot from paired cameras to instantaneously capture 3D surface images called ‘image correlation’ or more technically ‘passive stereo photogrammetry’
3	Fuel 3D	Greenville, North Carolina, United States	Human face 3D scanning is one of the highlights of SCANIFY
4	Motion View Facial Insight 3D	Hixson, Tennessee, United States	3D IMAGE Organizer Photos + X-Rays + 3D Data Integrated in One Place Search patient database that includes 2D images, 3D scans, reports and treatment plans. Easily import photos, X-rays, 3D scans of teeth/models and 3D facial scans • Crop, rotate and align photos. • Arrange photos in multiple layouts such as ABO format. • Print composite of photos. • Present slideshow of images. • Overlay grids on images. • Automatically saves originals.
5	RayFACE scanner	Pangyo Techno Valley, Seoul, South Korea	Extra-oral scanners, capture 3D images of the patient’s dentition from outside the mouth. RAY’s advanced optical technology creates accurate digital impressions of the mouth, face, and head-shape, resulting in a digital scan that precisely represent the patient’s oral anatomy and physical appearance.
6	MegaGen Face scanner	Daegu, South Korea	R2STUDIO: ONE STEP collection and digitisation of patient data within 10 min (CBCT + 3D facial scan +.stl dentition file) R2GATE facial analysis: a unique function that defines mid-facial plan, skeletal asymmetries, and aesthetic problems
7	Artec Eva	Senningerberg, Luxembourg	This structured-light 3D scanner is the ideal choice for making quick, textured and accurate 3D models of medium-sized objects such as a human bust, an alloy wheel, or a motorcycle exhaust system. It scans quickly, capturing precise measurements in high resolution. Light, fast and versatile, Eva is our most popular scanner and a market leader in handheld 3D scanners. Based on safe-to-use structured-light scanning technology, it is an excellent all-around solution for capturing objects of almost any kind, including objects with black and shiny surfaces.

3dMD is a non-radiation 3D medical imaging system. It is available in various modules for different body parts. 3dMD face analysis system can capture facial contours at 180–200 degrees from ear to ear at the ultra-fast speed of fewer than 1.5 ms, which means cameras can record the images unaffected by the movement. This is a great support and facility with 3dMD whereby face scans of newborns and children can be accurately obtained without concerns for unavoidable body movements ( Fig. 35.2 ).

3D photograph of the face (Courtesy 3dMD).

Source: Metzger TE, Kula KS, Eckert GJ, Ghoneima AA. Orthodontic soft-tissue parameters: a comparison of cone beam computed tomography and the 3dMD imaging system. Am J Orthod Dentofacial Orthop 2013; 144(5):672–81. PubMed PMID: 24182583.

The system works through two modular units of six machine vision cameras and an industrial-grade flash system synchronised in a single capture. The geometric accuracy of the 3dMD system is <0.2 mm root mean square (RMS) or even better depending upon the mode with a 3D image rendering speed of 7 seconds. It automatically generates a continuous 3D polygon surface mesh with a single x, y and z coordinate system from all synchronised stereo pairs. The 3dMD software automatically maps all the colour information to the mesh. The system accurately documents the patient’s natural head position and multiple facial expressions non-invasively during various stages of the treatment cycle.

In the medical and dental fields, the 3dMD system is now considered the standard reference system for 3D anthropometric analysis. The system has been used to study the growth of the face and to evaluate treatment changes, the outcome of surgical treatment and modifications of the face with ageing.

Assessing facial soft tissue structures has traditionally relied on 2D static photographs and video techniques. The 3D method of evaluation face has been introduced recently for this purpose. The assessment and quantification of facial muscle movements are critical for diagnosis, surgical treatment planning and evaluation of surgical outcomes in patients with facial deformities such as cleft lip and palate.

For this purpose, motion capture stereophotogrammetry systems were introduced. Four-dimensional (4D) facial imaging can be defined as a time sequence of 3D models of facial animations.

The 4D technology acquires accurate 3D surface information at approximately 60 frames per second from various coordinated standpoints for up to a 10-min acquisition-long resolution cycle. The commercially available 4D imaging systems are:

• 1.

  3dMDface dynamic system (3dMD, Atlanta, GA, USA)

• 2.

  4D capture system (DI3D, Dimensional Imaging, Glasgow, Scotland)