Dental Imaging with Elaine Halley

Dental imaging describes the act of digitally enhancing or altering a patient’s teeth to demonstrate how they could look if certain changes were made to their teeth and smile using systems such as ‘Smile Imaging’ (smileimaging.co.uk), which I will mention later.

In the early stages of discussing the possible outcomes of dentistry affecting the smile, it can be a very useful aid to case presentation and serves as a tool to discuss possible outcomes. This process helps patients understand the impact of changing their smile in two dimensions.

This is often confused with, but is not the same, as Digital Smile Design (digitalsmiledesign.com) as advocated by Christian Coachman and team. 2-D design is part of the process but Digital Smile Design is a philosophy and a clinical workflow which involves designing the ideal smile maximising interdisciplinary communication and then being able to link this design to a prescribed 3-D process involving a trial smile and ultimately the clinical end result. The ethos of DSD is about showing the patient the potential end result in their mouths, ideally with two videos side by side where the contrast is focused on the teeth.

Psychology of the smile
When we consider communication with our patients and indeed with our colleagues, it is important to remember that we are visual beings. There are some important characteristics of the human visual system which impact on our perception of the smile.

Firstly, as humans, we perceive objects in relation to their surroundings. This gives us perspective. For example, when we hang a picture on the wall, our eyes compare the level of the frame to the horizontal of the wall and the ceiling join and we can instantly tell if it is level or not. Our brains are wired for these comparisons.

Social anthropologists believe that this comes from our hunter-gatherer days when we relied on our vision to be able to note specific landmarks in the landscape and to be able to tell where we are in relation to them ... to be able to map the surrounding area. In other words, we see or perceive things by constantly comparing with the surroundings.

Secondly, for everyone who is not in the dental profession, the smile or the teeth make up part of the picture of the face. The smile is an expression in motion and the teeth are part of that expression.

They can appear to be in harmony and pleasing to the eye as part of the human expression of that entire face, or they can appear in disharmony, obviously with different degrees. But the smile must be taken in context or it is largely meaningless.

For this reason, it is difficult for lay people to identify with our words when we are describing changes to teeth for anything more than the very simplest of changes. Obviously if there is one dark tooth or stained filling then the proposed change can be understood, but when we start talking about changing the position of teeth or closing spaces, this is much harder to visualise if you have no prior experience to draw on.

To visualise something based on words, we, as humans, need to draw on past experience to create an image of that possibility in our minds. For those of us in the dental profession, we have those experiences.

Most of our patients do not. It is therefore very important to use actual images such as photographs of smiles to improve communication. It is also important to use full face photographs. Nobody outside the dental profession looks at pictures of smiles only, and especially not of retracted smiles.

We need to be showing full faces with expression for our patients to make sense of what they are seeing, remembering that the smile is an expression—i.e., it reflects a mood or an emotion.

Our patients do not want dentistry. Much like when we go to the doctor, none of us want the operation or even the blood test. We do want to be healthy. We want to enjoy our lives with a feeling of well being.

Dentistry is the same but because much of what we do in aesthetic dentistry is elective, we can forget that, and we can get very excited and animated about the wonderful techniques and technology that we have available, and we forget that patients don’t want any of it.

They don’t want the implant, the tooth whitening, the bonding or the orthodontics. They want the end result—health, comfort and the self-confidence to interact with other human beings in a free and relaxed way, without feeling self-conscious about their smiles.

Obviously, this means different things for different people. Fortunately, cosmetic dentistry has progressed past the point of making everyone look the same restoratively, and there has been excellent research and development of systems for analysing, diagnosing and treatment planning with health and function and conservation of tooth structure as the ultimate goals, but also being able to enhance aesthetics.

And so, when we are discussing the options with a patient who is considering or asking about cosmetic or aesthetic changes, our most powerful tool is photography and video. A picture of the patient on a large screen can start the conversation as to whether there is anything that the patient may change about their smile, and even before that is asking the patient to rate their smile on a scale of 1 to 10.

There are three things that make up the composition of a smile: colour, shape and position. The relative interactions of all of these factors for every tooth in the smile give us the perception of harmony or disharmony.

So how does dental imaging help us? Imaging softwares have been around for well over 20 years, as long as dentists have been using computers. It is very easy now to take high quality digital images of our patients, full face smile from the front.

Some key points here, for imaging to be effective it helps if we standardise how we take these pictures. Certain things can be altered digitally but others cannot.

Patients generally have a pose position that they go to, having taught themselves with selfies or in from of the mirror. Imaging works best, currently, on a fully frontal image ie without any degree of turn of the head. This can be checked by the operator looking at how much of either ear is showing. Horizontal shifts can be edited in the software, saggital shifts cannot. Chin down is very important as this can create a false reverse smile if the chin is up, and this is common when people are trying to minimise a double chin! And lastly the teeth slightly apart so that the edges of the maxillary teeth have a dark background. The degree of opening will depend on the occlusion, Class 2 deep bites need to open much further than a Class 1 or 3, and we only want enough opening to just separate the anterior teeth. Too much and again, the smile is distorted.

Once we have a good smile photograph, imaging can do several things;

1. Lightening the whole smile to simulate whitening. This can be an easy and effective tool. Key reference factors like the whites of the eyes can be used.
2. Manipulating individual teeth. E.g., duplicating and flipping a central and lateral from one side to the other, simulating bonding to lengthen teeth or close diastemas.
3. Overlaying another smile to demonstrate large changes. This is, at the basic level, cutting and pasting someone else’s smile into this patient’s face, and can be effective for demonstrating large-scale change. Most softwares come with a smile library and the operator can manipulate these to suit the patient’s smile.

Criticisms of dental imaging often centre around the idea that by showing a patient a digitally enhanced image, we are therefore creating a potentially unrealistic outcome, and leaving ourselves open to setting unrealistic expectations in the eyes of the patient.

Steps can be taken however to overcome these potential risks. Firstly, before showing the patient an image, it is important to explain that this is an image created on a computer to give us an idea of how the patient could look if dentistry was carried out. Indeed, sometimes the images do look artificial and so we do not want the patient to be put off treatment because they do not like the artificial image.

A disclaimer can be printed under every image to the same effect. In addition, it is important that the person doing the imaging or showing it to the patient has some understanding of what is possible. For instance, if there is a large jaw discrepancy that can only be corrected with orthognathic surgery, this may be simple to simulate on a computer but the reality of the procedure is much more complicated.

This needs to be communicated to the patient sensibly so that there are no false expectations. Imaging is not the treatment plan per se, the dentistry still needs to be diagnosed and planned appropriately, taking biology and function into account.

The software that I have found the easiest to use in practice for 2-D imaging is Smile Imaging (smileimaging.co.uk). This program is very user-friendly and full training is provided so that team members such as treatment co-ordinators can easily be trained to set up the imaging. All the changes I have mentioned above can be made, saved and ‘befores’ and ‘afters’ organised for easy discussion and communication with patients.

Dental 2-D imaging can be outsourced to companies that will accept an emailed photograph with some simple instructions and will return a before-and-after for a fee. E.g., SmileVision.

Thirdly, images can be manipulated within keynote or using photo software. This is generally less intuitive and needs more understanding of the nondental software by the operator but is also effective.

The 2-D images, if accompanied by an .STL file from a digital impression or a model scan, can also be converted to 3-D and this can also be outsourced, for example to the DSD Planning Centre in Madrid. This is definitely the future for dentistry.

Software such as Nemotech can be used to design the case in 2-D and 3-D. The future also holds other advances which will make this process simpler for the user. For example, the work being done by Disney where teeth are constructed from simple photographs or video will likely eventually impact the image-capture capabilities of dentistry.

In summary, dental imaging is a very useful tool to be able to demonstrate to the patient in photographic form the potential outcome of changing elements of the smile. This is most powerful when used with the full face. Although smiles can be designed digitally—e.g., following the DSD protocol by Christian Coachman and team—it is not always possible to take these to the mouth in the first instance.

Trial smiles can be designed digitally and photographed and videoed in the mouth to produce 3-D images for some patients.

For non-additive case­s—e.g., perio where teeth have drifted forward, or to demonstrate simple things like colour change or bonding before going to the mouth—2-D dental imaging with for example ‘Smile Imaging’ is a simple, effective way to initiate further discussion and can be used to increase case acceptance.

Elaine Halley BDS, MFGDP (UK), MSc qualified in 1992 in Edinburgh and gained her MFGDP(UK) in 1995.

She is the owner of Cherrybank Dental Spa in Edinburgh and Perth. Her main interest is in cosmetic and restorative dentistry and she is a Master Clinician and an Instructor for DSD - Digital Smile Design.

She is a past president and an accredited member of the British Academy of Cosmetic Dentistry.

Elaine has a Masters of Science Degree in Aesthetic and Restorative Dentistry which she was awarded with Distinction in 2012.