Computerized Diagnosis of the Study Model

Computerized diagnosis of the study model:

-Introduction:“Now computerized software are commercially available which are capable of scanning study models and storing the scanned data as 3-dimensional images.”*)The scanned data is calibrated to the actual size of the study models then ,certain softwares are now capable of using these digital study models to do certain analysis directly on the computer.

-Plaster cast and the development of 3-D models:1)To obtain an accurate orthodontic diagnosis ,orthodontists use the plaster study cast to perform many analysis and obtain various measurements(include tooth width and arch length). These measurements provide space assessment which is often necessary to determine the appropriate treatment plane.2)When the plaster cast is used ,this procedure involve time(laboratory),space(storage) and retrieval for clinical use. The measurements are obtained manually from the cast using a caliper.3)Today’s 3D sensor technology provides new potential alternatives to replace the manual measurements which

include 3D digital images of scanned objects followed by computerized measuring software.

*Advantages:1)Save valuable storage space with orthodontic digital models.(a cupboard full of plaster models is equivalent to 1 CD Rom of 3D models)

2)Better storage media.(No risk of breahage or being changed with other casts for another patients)

3)Allow more accurate measurements ,especially in case of sever crowding(For example the TELEDENT software which has the cross-section feature which use two fixed parallel cross section planes with a cross-section window which provides a more accurate determination of the widest tooth dimension).

4)Using the available software, it is able not to measure the mesiodistal width only ,but also the mesiodistal angulation and rotation as well as determining contact point\area between two adjacent teeth.

5)Time saving.(Easy and fast retrieval for the clinical use)

6)Allow easy online consultation and presentation possibilities.

*)Constructionn of the 3D cast:

1)currently ,a few companies provide clinically operational digital softwares which enables the users to perform different measurements and calculations from the digital models.

2)3D models can be obtained either using direct or indirect approaches:a)Direct:(Involve the use of an intraoral camera)b)Indirect:-Involve the use of: i)3D scanner with holographic sensor to scan a plaster model. ii)Laser-based system for laser scanning of the study cast. iii)CT method to image the study model or alternatively to image the dental impression and a waxbite directly. N.B\Orthoproof is an example of the companies that make 3D casts from scanning the impression by Flash Computed tomography scanner. -The scanner make 780 slice in a rotation of 360 degree

in about 28 seconds, then image processed in 20 min. -By using specially designed software ,the casts of the 2 Jaws are aligned using the waxbite.

3)Examples for the available softwares:(Ortho-CAD ,Onxy ceph and TELEDENT) -Example for the 3D scanner is (optimet 3D scanner with ConoProbe holographic sensor) this type of the scanners are used with the TELEDENT software.-This scanning system(Optimet 3D) provide precision up to 15um and enables measurements of complex geometric objects as well as angles up to 85 degree which facilitate measurement of undercuts as found in orthodontic casts.

optimet 3D scanner with Conoprobe Holographic sensor

-The TELEDENT software (which is used with the Optimet 3D)provides interactive graphical tools such as cross-

section planes which are used to mimic the digital caliper arms.-These cross-section planes are more accurate than the caliper arms in calculating the mesiodistal width of the teeth especially in cases of sever crowding where it is difficult to use the caliper.

-Computerized diagnostic Radiographs:

Introduction:-Images of the craniofacial region are an important component of the orthodontic patient record.-Nowadays there is a great revolution in term of using the 3D and also 4D(3D during function) images instead of the 2D images with its limitations.-At the same time, with the development of these more detailed and accurate images ,many softwares have been developed for accurate evaluation and analysis of these images.So ,more accurate diagnosis will give more accurate and sophisticated treatment planes.

-Principles of good orthodontic software:1)provided by information and template on different types of analysis and data type.

Cross-section planes

2)Provide mean of communication.3)Can perform comparisons ,treatment simulation ,VTO and different measurements.

-Available types of craniofacial images:2D (lateral\frontal cephalometry)3D (cone beam C.T)4D (3D during function)

How to obtain a 3D image?1)Combining frontal and lateral cephalograms to produce a virtual 3D data(old method).2)3D reconstruction utilizing the basic C.T images.3)Spiral CT and cone beam CT.(most recent with low radiation)

3D spectrum:

Data feeding(CBCT ,CT ,spiral CT and MRI)

3D reconstruction

3D image points and planes 3D analysis

Identification (3D points,3D planes 3D measurements)

Examples of the available softwares:-Dolphin.-Maxilim.-VolView-View box-onxy ceph

-Dolphin software:

1)The Dolphin software is a powerful tool that makes processing 3D data extremely simple.2)It enable dental specialists from a wide variety of disciplines to diagnose ,plane treatment ,document and present cases.3)Dolphin can visualize and perform analysis of craniofacial anatomy in 3D as well as the traditional 2D.4)Data for this software can be produced by:(CBCT ,MRI ,Medical CT and also using captured images from existing files ,flatbed scanner or digital x-ray systems to produce 2D images.)

*Uses and features:

1)Simple graphic user interface(GUI):

Panoramic x-ray image created by Dolphin 3D from CBCT image

2)Simple data segmentation and visualization:-3D object is prepared by grouping intensity levels in pre-set ranges for soft tissue and hard tissue.-After this simple procedure ,you can easily review the object’s solid or translucent skeletal surface ,solid ,translucent or photo of soft tissue surface or both simultaneously.-You can use this property to switch from hard tissue to soft tissue views and also you can adjust the factor of translucency and intensity to reveal the structure you desire.

Merge CBCT volume with surface data from 3D facial camera

Left: Tanslucent hard tissue view- Right: Translucent soft tissue view

-Clipping tool allow to visualize hidden structures ,or simply eliminate portions of the contents that are not relevant.

3)Object orientation:-To maximize the consistency of the analysis ,Dolphin allow to orient the 3D image free in many views ,frontal ,back ,right ,left ,top ,bottom ,oblique and isometric views.

-Also it allows definig the med-sagittal ,axial and coronal tools by its comprehensive tools.

View impacted teeth from any angle

4)Multiplaner view and layout:(Chose a layout that is best suited to your task)

5)Instan ceph\pan:-It can use 2D radiograph that is obtained from many sources (eg digital cephalometry system) or create 2D radiographic images from 3D volume dataset in the lateral ,panoramic ,frontal and SMV views.

-The reconstructed radiograph has the advantage that there is no distortion or magnification (i.e 1:1 projection)-various cephalometric analysis for orthodontic and surgical use can be performed by Dolphin using ceph tracing softwares ,for instance:1)Lateral analysis(eg rickets ,McNamara ,Stiener ,Tween….etc)2)Frontal analysis.3)Automated tooth and cephalometric structure templetes including:(sot tissue profile ,airway ,symphysis ,maxilla ,mandible ,condyle and developing 3rd molar) and many more.4)Norm deviation display.5)Fully customizable cephalometric analysis ,structure ,norms.6)Norms categorized by age ,gender and race.7)Superimpositions (eg at different time points)

8)Digitizing\Measuring:-Dolphin 3D makes the collected data from 3D volume simple ,and an excellent tool for research data

collection ,and also accurate measurements either in 2D or 3D.For instance:“Airway exmaintation can be accurately done in 3D giving volumes in cubic mm or in 2D to measure distance between different structures”

Airway measurements

7)3D nerve marking:1)It allows locating and isolating the nerve canal on a panoramic projection.2)Draw the visible nerve canal with your choice of width ,color.3)View cross-sections of nerve position.4)View nerve canals in relation to the skull volume.

8)Slice display at different planes and areas:For example slice display of the airway volume and most constricted areas.

9)TMJ view:

-Viewing the TMJ in different planes and direction and also give cross sections at any chosen axes for accurate diagnosis.

_Maxilim software:

“Maxilim is a plateform for anatomy and for preoperative planning of orthodontics and maxillofacial surgry”-Maxilim approaches the maxillofacial surgeon and orthodontist as a team:

-The input informations:-The input information for Maxilim is a 3D dataset(usually CBCT is the main source of the information)-Also ,3D photographs and 3D cast can be manipulated

using Maxilim.

-Maxilim offers solutions toward:-Diagnosis -Orthodontic surgery.-Distraction osteogenesis -3D cephalometry.

-Features and uses:

1)Maxilim contain all features to perform a 3D cephalometric analysis.2)Maxilim use frontal and lateral cephalograms and combine them to produce a virtual 3D data.3)Also it can use data from CBCT to directly produce 3D image.4)Various planes and landmarks can be defined and visualized for more accurate and repeated analyses and measurements.For instance:(anatomically based 3D reference frame is set up ,and this reference frame is based on Nasion and

Sella)

-VolView from Kitware:

-Volview is an intuitive ,interactive system for volume visualization that allows researchers to quickly explore and analyze complex 3D medical or scientific data on a standard PC.

1)User can easily generate informative images and negative the data for further anaylsis.

2)3D tools include(Volume rendering ,contouring ,cropping and oblique reformatting)3)VolView can work with 2D as well as 3D data.4)It accepts CT images as well as data gained from MR scanner.

-View Box “Advanced software for cephalometric analysis”-It is used for analysis and measurements of different radiograph ,photograph(2D and 3D) and now also in recent versions ,it can perform some tasks on 3D casts.-Input data:-CBCT.-Medical CT.-MRI.Combining frontal and lateral cephalograms to virtually produce 3D data.-2D radiographs (lateral ceph).-Scanned casts.-Onyx ceph:1)It is a 2D system that is used for analysis of (lateral cephalometric ,photographs and casts)2)Data can obtained easily for this software through:(Digital cephalometry system ,scanned or capturing the radiographs)3)Onxy ceph is valuble in: -Growth predictions

-Cephalometric analysis for orthodontic diagnosis. -Planning for orthognathic surgeries. -Soft tissue evalution.-Computerized photographic diagnosis:Introduction:-Technology advances in the past 5 years have started to erode barriers to safely make a human 3D data input as precise and easy to obtain as physical 3D object input.-Nowadays ,many are familiar with the advances in 3D surface images.-This 3D systems enable extraoral imaging protocols to be equally precise in providing highly accurate 3D facial surface images for diagnosis ,analysis ,treatment monitoring ,simulation and outcome evaluation.

-Two types of photographs are available now: I) 2D photographsII) 3D photographs

I)2D photographs:-For example those photographs obtained from the digital cameras.-2D photographs are widely used now because they are easly obtained but they have certain limitations:*Several variables can cause disparity when comparing 2 apparently similar photographs: -Distance between camera and object. -Camera angle. -Head position. -Photography protocol inconsistencies.

*These problems are further compounded when combining a patient’s lateral photograph with a lateral cephalometric image for analysis.*Achieving a repeatable and reliable registration between the two images is unlikely ,considering all the variables involved.-2D photographs can be manipulated using many softwares (eg:Dolphin ,Ceph basic and onxy ceph)

II) 3D photographs:-The 3D images have many advantages over the 2D images:1)Depending on the system used ,the process of imaging a patient in 3D can be simpler and take less time than traditional photograpgy.2)Because some 3D surface imaging systems are noninvasive ,images can be taken as frequently as needed.3)The imaging speeds from some machine-vision camera based stereophotography systems are so fast that even erratic movement by the youngest child or the most restless patient is not an issue.4)Once the 3D image has been acquired ,it becomes the foundation of the visible patient record ready for analysis at any time. 3D photographs can be obtained from many sources: 1)Laser scanning.2)Structured light.3)Stereophotogrammetry (e.g 3dMD face system)4)Direct contact(manual probe)5)Vedio-imaging.

1)Laser scanning:(Laser-scanner was one of the first 3D surface-imaging technologies available)1)It is one of the popular technology for three dimensional facial imaging involve the use of laser.2)Laser scanners are capable of producing detailed models ,however,the scanning process requires the subject to remain still for a period of seconds to a minute or more while the scanner revolves around the subject’s head.3)Because the laser provides only the surface map and cannot provide color information for the texture map, a color camera that is registered with the laser scanner provides this information.

2)Structured light:1)The principle behind structured light system is the projection of a pattern(eg line ,grids or circles) onto a surface that is distorted and interpreted as three dimensional information to produce a surface map.2)Several images are taken to obtain frontal ,left and right views of the face.3)To produce a full-face model(from ear to ear) with these systems ,different views are combined in a process called stitching to produce one model.

3)Stereophotogrammetry:1)The stereophotogrammetry technique is sophisticated software approach based on the fundamental principle of taking 2 pictures of the same object ,at a distance similar to the distance between a person’s eye ,to create a stereo pair and to record depth.2)Stereophotogrammetry uses sophisticated stereo triangulation algorithms to identify and match unique external surface features between the 2 photographs and generate a composite 3D model.Example: the 3dMD face system which use 3 cameras(frontal ,right and left) each side camera is on a distance to the frontal similar to the distance between the two eyes ,to produce 3D facial model from ear to ear.

-Data gained from these sources then are processed using many softwares ,for instance:-Dolphin(imaging plus)-Ceph basic-Onyx ceph-Image-pro-CT-analyser-CAD viewer

-Dolphin (imaging plus):1)Imaging Plus allow easy capturing ,organizing and presenting image records.2)It also includes a set of powerful and user-friendly tool for conveying treatment plans and easily communicate idea.3)Options and features:i)Slide presentation:(Slide show presentation of stored images in different formats and layouts eg:organizing the extra and intra-oral photos in one frame) ii)Enhancement abilities:(Photos can be easily enhanced(eg contrast ,brightness)using this software)

iii)Orthodontic and dental procedure simulation(optional module):(demonstrate how the patient might look with braces on ,with straight teeth ,or after a bleaching procedures)

iv)Orthodontic and surgical simulation:(in both the profile and the frontal view)

Ceph basic-On of the most common software whaich allow facial analysis on photograph ,for example:(vertical proportions-horizontal proportions-detection of facial asymmetry)

-Compares between two or more photographs(pre- treatment, during and post-treatment)

-Onyx ceph:-Onyx ceph is one of the most simple softwares.

-It uses 2D photographs to perform various analysis.-It allow comparing the profile photographs with the lateral cephalomtries and performing various analysis.

-Integration of digital dental casts in 3-dimensional facial photographs:-The integration of the digital dental casts in the anatomically correct position in the 3D facial photographs has a great value increasing the accuracy of the diagnosis and it also allows better understanding to the relation of the dentition and the surrounding soft and hard tissues.

-For the integration ,3 digital data set were constructed:(a digital dental cast ,a digital 3D photograph of the patient with teeth visible and a digital 3d photograph of the patient with the teeth in occlusion)

-After matching the three data sets ,we obtained a 3D digital model with the dental cast visible through the transparent picture of the patient’s face. -Method:-For the integration ,3 digital data set need to be constructed:i)a digital dental cast.ii) digital 3D facial photograph of the patient with the teeth visible (using cheek retractor)iii)a digital 3D facial photograph of the patient with the teeth in occlusion.

i)Digital dental cast:1)For the digital dental cast ,impressions were made for the patient and a wax bite was made to register the relationship between the arches.2)The impression and the cast were used for the fabrication of the 3D cast using different method(eg scanning of the impression and the bite)ii)Digital 3D facial photograph:-A 3D stereophotogrammetrical camera setup and the software modular system(eg:3dMD face system) are used to get the required pictures.

-To match the three 3D models ,Maxilim software is used for the matching as follow:

Stage I:-This stage involve positioning the 3D cast in the 3D picture.-This is performed by identifying 4 corresponding landmarks spread over the dental surface on both the digital dental cast and the digital 3D picture( patient with the retractor) -This allow initial registration of the cast to this picture.Stage II:-This stage involve projecting the first picture(with the cast) into the 3D picture of the patient with his teeth in occlusion.-This procedure was the same as the matching between the digital dental cast and the digital 3D picture of the patient with cheek retractor.-The only difference is that the surface matching was done on the forehead instead of the teeth.

(By using Maxilim software program ,it was possible to show only the digital dental cast and the digital 3D picture of the patient with the teeth in occlusion. The digital 3D picture of the patient’s face can be made transparent to see the digital dental cast in the patient face)