#Graphic Screen Display.
Graphic Screen Display
The requirements for the physical setup of the dental station directly impact the graphic screen display requirements. The clinicians are familiar with some computer-based interactive teaching materials about cavity preparation.
3D oral cavity model
One of the most important components of the GUI (graphic user interface) is the visualisation of a virtual oral cavity. The clinicians gave specific modelling requirements about this. This is discussed in the next section.
Oral cavity magnification, orientation and depth perception As mentioned above, by using loupes, the actual size of teeth are magnified to at least twice their actual size. To get a view of a tooth being operated upon, operators may either move their head or move the patient’s face or they may do both. To some extent, a graphic screen display may need to model at least the different angular views of the oral cavity depending on e.g. simulated operator’s head movements or patient face movement. The researcher mention that the project is considering the possibility of integrating head-tracking and visual techniques (i.e. parallax and stereo vision) to be able to model this. They got enthusiastic about this possibility. Perception of depth by tracking head movements using this technique may also add value to the simulated experience.
Motion representation of hand and drill operating on a ‘haptic tooth’ The graphic image should exactly match the movement of the operator’s hand. While it may not be possible to include operator’s hands virtually, it is important to represent the movement of the dental tools. For example, learner-operators are often reminded to, as much as possible, avoid damaging the healthy part of a tooth when preparing a cavity. The angle that a handpiece makes when drilling a decayed tooth is important in determining the correct angle of entry when preparing a cavity. Another specific example is the use of the mirror to reflect light to a part of a tooth. One of the clinicians referred to a learner-driver metaphor, i.e. learner-operator eventually would acquire the skills of manoeuvring their hands with the mirror automatically as they practice holding them at different angles. When cutting a part of a tooth that is not visible to the eye, the mirror is used to see this part which is then a mirror image of the real tooth. Operators therefore also need to learn to use the other hand holding another tool to do reverse movements as they view what they are cutting through the mirror.
Graphic dental tools Different dental tools need to be produced graphically so that they appear to be treating the tooth. The graphic could be just the ends of tools appearing on the screen as if operators’ hands are just out of view. These are: two types of drills (slow and high speed), two different probes (normal and perio-probe), mirror, and two different burs. The performance of the drill is influenced by the speed. The clinicians suggested that the user interface needs to account for the speed control. The clinicians also asked if it may be possible to include virtual suction and virtual cooling water-spray.
Light illumination In the physical world, operators also move the light sources but what is important is that enough light is focused on a part of a tooth being prepared. They mentioned this and leave it to the developers to consider how it might be possible to represent this graphically.
Graphic workspace As the operator would normally operate using loupes which magnifies the size of the oral cavity, the clinicians suggest that the graphic workspace may need to be the exact specification of 2 to 3 times its actual size. Dental tools could also be scaled similarly.