virtual articulator used in prosthodontics

Virtual articulators

1. VIRTUAL ARTICULATORS & FACEBOW Sreya Jyothibas Dept of Prosthodontics 07/02/2025

2. CONTENTS INTRODUCTION ARTICULATOR NEED FOR VIRTUAL ARTICULATORS VIRTUAL ARTICULATORS HISTORY TYPES DATA REGISTRATION FOR VIRTUAL ARTICULATORS

3. CONTENTS FACEBOW VIRTUAL FACEBOW TECHNIQUES JAW MOTION RECORDING ADVANTAGES & DISADVATAGES FUTURE CONCLUSION REFERNCES

4. INTRODUCTION Virtual reality refers to “immersive, interactive, multi-sensory, viewer centered, three-dimensional, computer-generated environments”. V irtual reality lets you navigate and view a world of three-dimensional platform in real-time. V irtual reality is a clone of physical reality creating a virtual environment to replace the real-world environment.

5. The equipment and technologies by which we can interact in virtual reality are known as virtual reality equipment and virtual reality technologies. In the field of prosthetic and restorative dentistry, the virtual dental articulator incorporates virtual reality applications to the world of clinical dental practice for the analysis of complex static and dynamic occlusal relations.

6. Its chief application is in the simulation of the mechanical articulator. The virtual articulator requires digital 3D representations of the jaws and patient-specific data on jaw movements. It then simulates jaw movements and provides a dynamic visualization of the occlusal contacts.

7. ARTICULATOR

8. The first mechanical articulator was described in 1756. Ever since, hundreds of articulators have been contracted and used. Mechanical articulators simulate the movement of the mandible and the temporomandibular joints.

9. They are the most important devices for both dentists and dental technicians, because they are commonly used in the production of dental prostheses, as well as in the diagnosis and analysis of the occlusal relationship.

10. DEFINITION A mechanical instrument that represents the temporomandibular joints and jaws to which maxillary and mandibular casts may be attached to stimulate some or all mandibular movements -GPT 9

11. FUNCTIONS To hold the maxillary and mandibular casts in a planned relation. To simulate the patient’s TMJ, Maxilla, and Mandible movements. To mount casts for diagnosis, treatment planning and patient presentation. To fabricate occlusal surfaces of restorations. To arrange artificial teeth.

12. ADVANTAGES OF MECHANICAL ARTICULATORS better view of the patient’s occlusion especially the lingual side. Patient cooperation is not a factor when using an articulator once the appropriate interocclusal records are obtained.

13. ADVANTAGES OF MECHANICAL ARTICULATORS The refinement of CD occlusion in the mouth is extremely difficult because of shifting denture bases and resiliency of the supporting tissues. Considerably more chair time and the patient appointment time is required when utilizing the mouth as an articulator.

14. LIMITATIONS OF MECHANICAL ARTICULATORS They are made up of metal ,although few plastic parts they are subjected to error in tooling and to error resulting from metal fatigue and wear. The problem of making accurate marks in the presence of saliva. The inability to know exact location of the condyle.

15. WHY WE NEED VIRTUAL ARTICULATOR? mechanical articulators replicate the maxillomandibular relationship in a static condition without considering the envelope of motion of the mandible in real time. inaccuracy in locating dynamic occlusal contacts along with development of certain new unwanted occlusal interferences which have to be corrected in the patient increasing the chairside time. Hence the purpose of single visit dentistry is not fulfilled.

16. WHY WE NEED VIRTUAL ARTICULATOR? These problems can be resolved by replacing the conventional mechanical articulators with the newly developed Virtual Articulator software. This software is based on the virtual reality technology which provides an immersive, interactive, multisensory, viewer centered, 3D computer generated environment to replicate patient data .

17. WHY WE NEED VIRTUAL ARTICULATOR? It adds the ability of performing kinematic analysis during the design process by incorporating patient specific jaw motion data and helping clinicians get rid of the unwanted occlusal interferences during the designing phase itself.

18. WHY WE NEED VIRTUAL ARTICULATOR? This software along with the Virtual facebow forms a completely digital workflow for prosthesis design improving the accuracy and precision of the final restoration and reducing the chairside time of the patient during final cementation.

19. VIRTUAL ARTICULATOR

20. The virtual articulator is an application in prosthetic & restorative dentistry based on virtual reality that will significantly reduce the limitation of the mechanical articulator and by simulation of real patient data, allows analysis of digitized casts with regard to static and dynamic occlusion as well as jaw relation .

21. They also called software articulators, since they exist only as a software programme tool. Combined with CAD/CAM technology, this tool offers a great potential in accurate planning of various treatment procedures. It increases accuracy and precision for the dentist to carry out the treatment and to achieve a better function and provide comfort for the patient as well.

22. HISTORY Virtual articulator software 1 st described by Szentpetery in the late 1990s. 1 st introduced in 2002 with the work of Bisler and his team from the University of Greifswald,Germany . It has been applied to CAD and CAM dentistry. Dent Cam was the 1 st software company includes virtual articulator functionally,it was introduced by Kavo .

23. TYPES

24. Mathematically simulated articulators

25. It was first designed by Szentpetery in 1997 It depends on a mathematical simulation of articulator movements. This device enables a dentist to reproduce the movement of a mechanical articulator, making it a fully adjustable 3D virtual articulator.

26. it is capable of reproducing mandibular movements such as retrusion, protrusion and laterotrusion on the basis of mathematical values of condylar angle and bennett angle. This provides the articulator an edge over the conventional mechanical articulators but it fails to reproduce the individualised movements of each patient as it based on a mathematical approach. Hence a more precise and adjustable software was desired.

27. Consequently, the individual movements for each patient cannot be tracked easily. Egs : Stratos 200 and Szentpetery’s virtual articulators .

28. Completely Adjustable Virtual Articulator

29. First designed by Gaertner and Kordass in 2000 . It records /reproduces exact movement paths of the mandible using an electronic jaw registration system called a Jaw motion analyser Software commercially available as DentCam JMA is composed of a high-speed recording camera and software running on a computer.

30. an ultrasonic motion capture device used to record the movement of jaws during functional conditions It is a 2-part system with the ultrasound emitter array bonded to the labial surfaces of the mandibular teeth via a customized cold cure acrylic jig and the counterpart, a sensor array, positioned on a head frame secured to the patient's head

31. PROCEDURE

32. The device will track the movement of the mandible identifying issues such as retrusion ,protrusion and laterotrusion . The digitised dental arches then moves along these movement paths that can be viewed in the computer screen consisting of three main windows showing the same movement of the arches from different planes

33. The software calculates and visualises both static and kinematic occlusal collisions and is used in designing and correction of occlusal surfaces in computer aided designing (CAD) systems. Eg: KaVo Protarevo 7 , SAM 2 , Artex CR , Stratos 300

34. The recorded data is visualized in different windows. Interpretation screen Occlusion screen Slice window Smaller window

35. Rendering screen: Premature contacts and occlusal collisions can be analyzed in this screen during the mandibular motion. Unwanted occlusal interferences can be avoided

36. Occlusion screen : Occlusal contacts between the maxilla and mandibular teeth can be watched as a function of time.

37. Smaller window: helps co-relate temporomandibular joint problems with harmful occlusal discrepancies. Shows the comprehensive movement of the joint in sagittal and transverse views.

38. Slice window: planning the site of occlusal adjustments as the frontal slice of the dental arch is viewed, showing the height and functional angles of the cusps along with the degree of intercuspation

39. In addition, the interrelationship between the upper and lower teeth, shape of teeth, and height of the cusp can be used to examine the intercuspation and the height and functional angles of the cuspids . the condylar trajectories can also be analyzed in the horizontal and sagittal planes within a virtual setup. The interrelationship between the incisal guidance and the condylar guidance, the impacts of TMJ mobility on the surface of the teeth and the occlusal collisions in both static and kinematic situations can also be analyzed.

40. Drawbacks It requires the use of special devices, such as a mandibular motion-tracking system – costly, complex Its lacks a universal digital format to save the movement of the lower jaw. Lack of standardisation and interoperability The system cannot be used with some virtual articulator software package.

41. Resolved by the introduction of VA software that is based on the type of mechanical articulator to be used. allows the clinician to visualise the final outcome. The articulator is scanned through a scanner and reverse engineering software to obtain data in CAD system. transferred to the Virtual articulator software. allows the clinician to choose the articulator as well as the setting parameters on case-to-case basis - comfortable and user-friendly software to work on.

42. INTEGRATION OF VA DATA TO PROSTHESIS DESIGNING

43. Intraoral scanners (IOS), which are devices that take a digital impression of a patient’s teeth Two different systems are available. 1. Photographic technology scanner system-records individual images of an object. 2. Video technology scanner system-works similarly to a video camera recording at high speed DATA REGISTRATION FOR VIRTUAL ARTICULATORS

44. During the first stage of using an IOS, such as the Laser Scan 3D an image of the occlusal part of the teeth, of the whole dental arches, and of the interocclusal relations are taken. After scanning, the collected information is converted to digital data and sent to the electronic processing system. Digital data are compiled by the software program, then the image is visualized on the computer screen where it can be manipulated

45. I nput device , eg : 3D scanner. A 3D virtual articulator software for prosthesis modeling. An output device in the form of “rapid prototyping system” with stereoscopic inkjet technology. V irtual articulator system requires three main devices

46. Dental laboratory process

47. FACE BOW

48. The terminal hinge axis (THA) is the axis around which the mandible rotates when the mandible is in centric relation. -The purpose of facebow is to record the patients THA and transfer it to the articulator so that it coincides with the arc of closure/hinge axis of the articulator. -the restorations will be free of interferences and there will be stability in the stomatognathic system

49. Facebows are caliper-like devices that record the relationship of the maxillary teeth to the position of the condyle when it is in the terminal hinge axis position and allow the information to be transferred to the  articulator  when mounting dental casts.

50. Diagnosis of tooth contact that hinders smooth jaw movements (occlusal interference). Treatment in accordance with the patient’s anatomy, therefore providing maximal functional performance and comfort. Clear standardized communication of functional issues to laboratory. Baseline records. Uses of face bow

51. U-shaped frame - main frame to which all other parts are attached Condylar rods/ear pieces - purpose is to locate hinge axis Bite fork - u-shaped plate which is placed inside the mouth What does it consist of?

52. Locking device - fixes the bite fork to the main frame after measurements Third reference point - a reference point on the face in line with condylar points What does it consist of?

53. The facebow and centric relation record have long been used to orient dental casts on an articulator in the same relationship as that in the patient’s mouth.

54. The virtual facebow was developed to locate the maxillary digital cast of the patient in a cranial coordinate system -The present protocol also allows the dentist to locate the mandibular digital cast exactly on the maxillary digital cast by using the virtual interocclusal record. Virtual facebow

55. Cephalometric images Developed by Noguchi et al in 2007 primarily for the purpose of bone position change analysis following orthognathic surgeries. Acquisition of the intraoral and extraoral facial structures via frontal and lateral cephalograms data by using superimposition of various points and coordinates on the cephalogram, and the data is used to simulate the orthognathic system in a 3D-shape analysis programme . Occlusal analysis is done in the Maximal Intercuspal Position (MIP).

56. The drawback - lack of utilization of any real reference plane Building on the above concept, Ghanai et al in 2010 described another technique to create a virtual patient for surgical planning in dysgnathia cases. They made use of a fixed reference plane in the form of Campers plane and kept the occlusal plane parallel to this fixed refence plane.

57. Campers plane was identified via cephalometric landmarks from 2D projections like lateral cephalograms. This allowed a more accurate mandibular rotational axis transfer thus creating a virtual 3D environment for digital jaw movement. Utilization of 2D imaging systems remained a drawback of the technique.

58. Position marker scanning with 3D optical scanner method Explained by Solaberrieta et al in 2103 it eliminates the need of physical mounting of casts and facebow transfer. Extra-oral facial markers are placed on the TMJ and infraorbital notch which orient the maxilla to the cranium and

59. Position marker scanning with 3D optical scanner method 3 points are chosen intraorally on the most prominent cusp tips to act as intraoral markers for orientation of the occlusion plane of the maxillary cast. Once selected, these markers are then scanned by the extraoral scanner and the cast are digitally mounted on the software

60. Facial photographs aided virtual mounting Another technique given by Solaberrieta et al in 2015. adhesive targets are placed on the posterior cutaneous landmarks to identify the facial reference planes. Along with this the maxillary plane is recorded by putting the facebow fork with elastomeric impression material into the patient’s mouth.

61. Facial photographs aided virtual mounting With this armamentarium in place, a series of 8-10 high-definition facial photographs of the patient are taken. These are then superimposed and reverse engineered to obtain the spatial relationship between the head and adhesive targets which is utilized to build a 3D virtual model of the patient’s face onto which the casts are digitally aligned.

62. Virtual axis technqiue Introduced by Solaberrieta et al in 2015. utilized scanned computer-generated arches and positioned them relative to the coordinates of the skull. more precise determination of the ICHA without the need for physical instrumentation higher accuracy specially when compared to the conventional maxillary transfer methods.

63. Stereophotogrammetry involves capturing three-dimensional images of the patient's head and facial structures using multiple cameras from different angles. By calibrating these images, precise measurements can be obtained, allowing for accurate virtual articulator mounting.

64. Standardized extra-oral photographs employing these standardized background images, clinicians can ensure consistency and accuracy in capturing the patient's natural head position, which is essential for precise articulation of dental models. followed by taking standardized 2D facial photographs and superimposing the same onto the CAD software by using reverse engineering. The drawback : operator-dependent step of marking the cutaneous landmarks

65. TECHNIQUES It includes two phases Phase 1: obtaining photographs and transferring data Phase 2: alignment of 3D face-facebow fork and impression-facebow fork

66. Phase 1: obtaining photographs and transferring data Scan the maxillary and mandibular dental arches of the patient with an intraoral dental scanner (3Shape TRIOS; 3Shape A/S) to obtain digital casts

67. Place 3 adhesive targets onto the patient’s head. Locate the first 2 points next to the temporomandibular joints and the third point onto the infraorbital point

68. Locate irreversible hydrocolloid or scannable elastomeric impression material on a plastic, colored facebow fork and introduce the facebow fork into the patient’s mouth, pushing it against the maxillary arch

69. Make 8 to 10 photographs by using a digital camera and reverse engineering software to obtain the 3D spatial relationship of the shape of the head with target points related to the facebow.

70. Load the images into the software and build the 3D geometry of the patient’s face with targets positioned on the facebow fork.

71. Scan the impression and the front side of the facebow fork with an intraoral dental scanner

72. Using reverse engineering software, load the facebow fork 3D geometry and align it to the maxillary digital cast by using the best-fit command.

73. Repeat the protocol, aligning the 3D face bow fork and impression facebow .

74. Blend the different surfaces of the scanned maxillary digital cast into a single virtual cast, eliminate surface abnormalities, remesh the organization of the triangulated mesh of points, and fill in the surface gaps that remain after data elaboration. Phase 2: Alignment of 3D face-facebow fork and impression-facebow fork

75. Create the cranial coordinate system by using the 2 temporomandibular points and the infraorbital point, locating the maxillary digital cast on this reference system

76. Transfer the maxillary digital cast to the virtual articulator software, bringing the cranial coordinate system to coincidence with the virtual articulator’s coordinate system

77. Locate the mandibular digital cast, scanning the virtual interocclusal record with an intraoral scanner in centric occlusion from 3 directions (left, right, and front). Match these scans with the maxillary and mandibular digital casts, positioning the mandibular digital cast towards the maxillary digital cast in the virtual articulator in maximum intercuspation.

78. JAW MOTION RECORDING

79. after articulation of the digital casts is programming the virtual articulator software with real time jaw motion data of the patient prime importance in completely adjustable VA software. Kordass and Gartner VA software utilized the JMA for recording the jaw motion wherein the mandibular movement is recorded by ultrasonographic emissions and calculated as the pulse travel time between the emitters and the sensors. This device - bulky and expensive for daily practices. Newer jaw motion recording devices are available

80. Helps record real-time jaw motion of patient and create a digital dynamic twin. It has the unique ability of merging all patient data including 3D models, 4D movements and CBCT. It records the markers on the lower facebow utilising high-definition cameras along with scan of certain facial areas to deliver the computer stereo version and record real time jaw movement. MODJAW SYSTEM

81. The advantage it possess over the conventional techniques includes, no continuous radiation exposure to the patient, lightweight of the device and the ability to constantly upgrade itself. MODJAW SYSTEM

82. optical measuring method. Optoelectronic registration device is utilized to register all jaw movement and the individual mandible position. The ultralight carbon reference bow is placed on the ears and it is fitted to the nose’s bridge. FREECORDER BLUEFOX

83. Other light modular arch is fitted to the mandible to capture its movement. 4D video recording method Thanks to special cameras, high resolution images are obtained by capturing 100 times per second.

84. Simple control by computer monitor or touchscreen monitor. The movement information and position information can be integrated in XML that enables date export and import Doesnot use any harmful radiations for recording position transfer

85. ARCUS DiGMA Introduced by Kavo the jaw movements can be simply and quickly detected by using ultrasound transmission. Four microphones adopted a bow is fixed to head and a support with three pingers is set on the jaw.

86. it captures a comprehensive range of data related to mandibular movement, occlusal positions, temporomandibular joint health, and even muscle activity through EMG analysis..

87. for diagnosing issues related to bite alignment, jaw function, and overall oral health. offering practitioners a more precise understanding of their patients oral dynamics

88. When using digma articulator, a new face-bow measurement is not required to confirm model mounting. Perfect hygiene through regular rubbing disinfection on smooth surfaces.  Overall savings by massively reducing occlusal adaptations in the patient's mouth. M ain features 

89. Electronic analysis of movement during prosthetic treatment. Electronic motion analysis for diagnostics. You do not need to use the computer keyboard.

90. PLANMECA 4D JAW MOTION CBCT integrated solution for recording, tracking, visualizing, and analyzing jaw movements in 3D. It offers visualization creating a fourth dimension in diagnostics Integrated Planmeca ProFace camera are used to track mandibular movements relative to the maxilla providing comprehensive data for diagnosis and treatment planning.

91. The recording of eight spheres, half integrated into glasses and half into a bow, allows for precise tracking of jaw movements. By correlating the movement of these spheres with the position of the glasses (representing skull movement) and the bow (attached to the lower arch for detecting relative distances), the software can accurately replicate mandibular movements.

92. ADVANTAGES better communication between the dentist, dental technician, and patient, ensuring alignment in treatment goals and outcomes. Integration with CAD/CAM - precise occlusal surfaces, enhancing the accuracy and fit of restorations and prosthetics. detailed analysis of gnathic (jaw) and joint conditions, aiding in the diagnosis and treatment planning of temporomandibular joint disorders (TMDs) and other related issues.

93. ADVANTAGES dynamic occlusion analysis - patient's bite functions during various movements. accurate 3D visualization and data - eliminate manufacturing problems associated with traditional methods, leading to better-fitting restorations and prosthetics. more time-efficient - allowing for quicker diagnosis, treatment planning, and fabrication of dental restorations.

94. ADVANTAGES facilitates modifications to restorations educates patients about their treatment options and expected outcomes. The data directly used for 3D printing, enabling the fabrication of patient-specific dental appliances and prosthetics with high precision

95. DISADVANTAGES Expensive, requiring investment in specialized hardware, software, and training for dental professionals. The technology may have a steep learning curve for dental professionals technical limitations such as hardware calibration errors or software bugs can affect the accuracy of the simulations, leading to potential inaccuracies in treatment planning.

96. DISADVANTAGES Access may be limited in certain regions or dental practices, particularly in less-developed areas or smaller clinics with budget constraints. ethical considerations regarding patient privacy, data security, and informed consent. Integrating - challenges due to differences in data formats and interoperability standards.

97. FUTURE 3D VA system An input device in the form of a 3D scanner is used for digitizing the casts. The output device is in the form of a rapid prototyping system helps manufacture the final prosthesis. The designing is done via the help of 3D VA software. It has been useful in planning implant placement locations specially in cases of pterygoid or zygomatic implants. Occlusal examination can also be incorporated

98. Haptic based first touch enable VA Intellifit's VA enables for dynamic settings to fulfil patient requirements while simulating the feel and functionality of a physical articulator The newest iteration of the IntellifitTM TE (Touch Enabled) Digital Restoration System from Sensable Dental Technologies gives dental labs even more options, performance, and flexibility when digitally designing and fabricating a variety of dental restorations.

99. both fixed and removable restorations, including entire ceramic monolithic crowns, bridges, and prepared veneers, which are produced more quickly and precisely Additionally, lab technicians can really feel how the teeth, including the new restoration they are creating, will fit together in the patient's mouth thanks to Intellifit's innovative 3D "Virtual Touch" interface and integrated touch-enabled articulator.

100. As any other technique, the use of virtual articulator requires a through understanding of its principles and working mechanism. Virtual facebow and articulator is intended to use as a tool for analysis of the complex static and dynamic occlusal relations. The main goal is to improve the design of the dental prosthesis, adding kinematic analysis to the design process CONCLUSION

101. Virtual technology shows promising technology of the future, where a more convenient and precise treatment can be achieved with better patient comfort. CONCLUSION

102. REFERENCES Essentials of complete denture by Sheldon wrinkle,3 rd edition Koralakunte PR, Aljanakh M. The role of virtual articulator in prosthetic and restorative dentistry. J Clin Diagn Res. 2014 Jul;8(7):ZE25-8. doi : 10.7860/JCDR/2014/8929.4648. Epub 2014 Jul 20. PMID: 25177664; PMCID: PMC4149170. Lepidi L, Galli M, Mastrangelo F, Venezia P, Joda T, Wang HL, Li J. Virtual Articulators and Virtual Mounting Procedures: Where Do We Stand? J Prosthodont . 2021 Jan;30(1):24-35. doi : 10.1111/jopr.13240. Epub 2020 Sep 2. PMID: 32827222.

103. REFERENCES Shetty S. Virtual articulators and virtual facebow transfers: Digital prosthodontics!!! J Indian Prosthodont Soc. 2015 Oct-Dec;15(4):291. doi : 10.4103/0972-4052.171825. PMID: 26929529; PMCID: PMC4762356. Solaberrieta E, Mínguez R, Barrenetxea L, Otegi JR, Szentpétery A. Comparison of the accuracy of a 3-dimensional virtual method and the conventional method for transferring the maxillary cast to a virtual articulator. J Prosthet Dent. 2015 Mar;113(3):191-7. doi : 10.1016/j.prosdent.2014.04.029. Epub 2015 Jan 2. PMID: 25557006.

104. REFERENCES Kalman L, Chrapka J, Joseph Y. Digitizing the Facebow: A Clinician/Technician Communication Tool. Int J Prosthodont . 2016 Jan-Feb;29(1):35-7. doi : 10.11607/ijp.4748. PMID: 26757326. Lam WY, Hsung RT, Choi WW, Luk HW, Pow EH. A 2-part facebow for CAD-CAM dentistry. J Prosthet Dent. 2016 Dec;116(6):843-847. doi : 10.1016/j.prosdent.2016.05.013. Epub 2016 Jul 28. PMID: 27475920 .

105. THANK YOU

106. Q & A

107. VIRTUAL ARTICULATORS & FACEBOW

108. Commercially available facial scanners used in dentistry 3Shape TRIOS : intraoral scanner that also offers facial scanning capabilities iTero Element 5D: both intraoral and facial scanning, allowing for comprehensive digital impressions and facial analysis

109. Commercially available facial scanners used in dentistry CEREC Omnicam : for both intraoral and facial scanning, aiding in various dental procedures including implants and orthodontics. Vectra XT: dedicated extraoral facial scanner that captures high-resolution 3D images of the face, which can be integrated with other digital dentistry tools. Lee, J.D.; Nguyen, O.; Lin, Y.-C.; Luu, D.; Kim, S.; Amini, A.; Lee, S.J. Facial Scanners in Dentistry: An Overview. Prosthesis 2022 , 4 , 664-678.

110. Facial scanners and facebow Fanyu 3D Face Scanner an electronic facebow gather comprehensive data on jaw positioning and mandibular movement. creation of a 3D virtual patient model

111. Facial scanners and facebow combining facial scan data, CBCT data, intraoral scan data, and electronic facebow data. precision and effectiveness of diagnosis and treatment planning in dental applications.

112. Virtual patient 3D Face Scanning

113. Analysis of facial changes

114. Transfer of Jaw Relation Electronic Facebow Function Trajectory analysis of mandibular movement

115. Photogrammetry This technique involves capturing a series of photographs from different angles around the patient's face and head. These images are then processed using specialized software to create a 3D digital model of the patient's facial structures. iMETRIC iCAM 4D

116. Photogrammetry Applications in Digital Dentistry Full Arch Implants & Prosthodontics Temporomandibular Joint (TMJ) Analysis Smile makeovers WHAT IS Photogrammetry? It's Uses in Dentistry & Introducing the iMETRIC iCAM 4D

117. THANK YOU