An occasionally irregular blog about orthodontics

Orthodontic space opening or closing for missing upper later incisors: What does the public think?

Orthodontic space opening or closing for missing upper later incisors: What does the public think?

Orthodontic space opening or closing for missing upper later incisors: What does the public think?

We have all been faced with the dilemma of whether to open or close missing lateral incisor space.  This post is is based on a recent paper that investigated lay people’s perception of the aesthetic outcome of this clinical problem.

Space closing versus space opening for bilateral missing upper laterals – aesthetic judgments of laypeople: a web-based survey

Qadri, Salim, Parkin, Nicola A., Benson, Philip E.
Journal of Orthodontics 2016: 3125: 1-10
DOI: 10.1080/14653125.2016.1145880

This paper was written by a team from Sheffield, UK. They are beginning to build a good record in researching patients and lay people’s perceptions of orthodontics and this paper is a nice addition to their work.
The congenital absence of lateral incisors is a common orthodontic problem. The two orthodontic treatment options involve closing spaces and remodelling the canine or opening the space and providing a prosthetic replacement. While this decision is influenced by many factors, for example, space requirements for the treatment of crowding and correction of  overjet, it is important that we consider the final aesthetics. My current preference is to lean toward space closure rather than space opening because of the potential long-term cost of prosthetic replacement. I am also  not sure on the likely long-term (50 years or more) prognosis of implants.

This paper is particularly helpful. The authors aimed to use a web-based survey to gather the views of none dentists concerning the appearance of upper anterior teeth following orthodontic space closure (OSC) or space opening and prosthetic replacement (PR).

What did they do?

In order to answer this question they carried out a study using the following steps;

  1. They asked several orthodontists to send post treatment  photographs of any patient with bilateral developmentally absent lateral incisors. This resulted in 21 usable images.
  2. They prepared these to show a standard view. They then asked five specialist orthodontist and five restorative dentists to rank these photographs in order of attractiveness.
  3. The images that were most frequently highly ranked within prepared for the main survey. (Figure 1).
  4. They then created an online survey in order to ask respondents perception of attractiveness using a Likert scale and their preference for the appearance of matched OSC and PR views.
  5. They then approached volunteers from the University of Sheffield mailing list and asked them to help with the study. This included 25,000 students and 6000 staff.
  6. They analysed the data using logistic regression to test the influence of treatment choice (PR or OSC, gender, age etc on the attractiveness ratings.
Figure 1. The ranked images. Space closure images are on the left and opening are on the right

Figure 1. The ranked images. Space closure images are on the left and opening are on the right

 What did they find?

The total number of responses was 1141 (4% response rate). After eliminating data errors and those who had a job in dentistry, the final number of responses was 959.

The presentation of data was clear and I am only going to describe their main findings;




  1. The raters felt that orthodontic space closure with camouflage was more attractive than space opening and prosthetic replacement. But I thought that the effect size was rather small.
  2. The odds of a PR image judgement being rated attractive or very attractive was significantly greater than an OSC image (odds ratio 0.61 95% CI 0.55 – 0.68).

They concluded;

“This Internet survey of none dental staff and students of the University of Sheffield has found a slightly higher attractiveness rating and majority preference for orthodontic space closure rather than prosthetic replacement when both lateral incisors are missing”.

What did I think?

I felt that this study provided us with useful pointers that are useful when we take the “space closure or opening” decision.  But I would like to consider their  methodology;

A major strength of this study was that they gathered the perceptions of lay people. This step is important as their views are likely to reflect the real world situation.

It was also important that the lay people felt that the results of space closure were better. If we combine this with the benefit of not needing prosthetic restoration with a lifelong maintenance programme, the adoption of space closure could be compelling. Nevertheless, some operators may be concerned that placing the first premolar is in in the position of the canine may be a problem in terms of canine guidance. But I am not aware of good evidence that suggests that this is an issue.

I do have some concerns about “how well” canines can be reshaped to resemble lateral incisors. But equally, I have been disappointed with the appearance of bridges/implants when replacing lateral incisors.

As with all studies there are some shortcomings. The first is that this was a “still life” study and did not attempt to evaluate the aesthetics in a dynamic situation. Furthermore, the response rate was rather low, but I am not sure how this would have influenced the results. My other concern is that this was a university population and I know from personal experience that the inhabitants of the University are very different from those outside! As a result, the externality of this study may be in question. It is also worth pointing out that the authors did draw attention to these problems in their nicely written paper.

Ultimately this is an interesting paper that provides us with useful information. It does reinforce my clinical tendency to wish to close space. I’m not sure what other operators feel but I am little concerned at what appears to be an increasing tendency to open spaces and put the patient into the restorative cycle.  This is certainly a subject that needs further research.

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There Are 8 Comments

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  1. Rami Lotfi says:

    Dear prof, should we use the lateral bracket on canine in space closure method?

  2. Jonathan Sproson says:

    These were the best views of restorative replacement of laterals they could find ?? – no wonder people were un impressed.
    As a dentist who undertakes smile design both orthodontic and restorative, I would make the following remarks.
    1. canines usually make less than ideal laterals they are too wide and bulky but with the right canine and skill with composite an effective job can be done. Therefore a restorative assessment of the tooth size and shape should be undertaken by a dentist who does restorative rather than an orthodontist prior to the orthodontic decision.
    2. It also depends on the first premolar size and position – often they are small teeth and the balance looks completely wrong with large laterals(disguised canine)
    3. too many orthodontists in my experience fail to rotate 14 24 sufficiently to hide the palatal cusp
    4. the narrowing of the arch by closing the spaces creates a narrowing of the arch which is aesthetically poor with dark buccal corridors
    5. Yes lack of canine guidance can be an issue later – however anterior occlusion can be an issue especially where incisors are over retracted to close space deepening the overbite and restricting the envelope of function – leading to severe incisal wear later in life.
    6. Intra oral shots like those illustrated are for dentists, – patients assess smiles so unretracted views that showed smiles would have been a more valid way of assessing the public opinion of what looked best.
    7.Get your point about implants or bridges likely to need replacement later in life but so will the disguising restorative dentistry i.e. bonding or veneers to make the canine look like a lateral etc
    8. what about the single missing canine. This looks abysmal when the space is closed the centre line lost and huge asymmetry results. I am currently in process of a major restorative case to improve the smile on a lady on which this was allowed to happen. I will make it look loads better but will never get it perfect without major oath to restore the centre line if it is even feasible

    Hope this is helpful, – ok not evidence based but as a result of 40 years experience

    • peter doyle says:

      Agreed , upper lip support is the most critical aesthetic factor that seems to have been missed here ! Its not really about twisted premolars or large laterals , these are very secondary considerations .
      Does the lip require more support or less .
      (9 times out of 10 more is required for a balanced face )

  3. I was interested to read this blog when I saw the headline, but I think it’s more difficult to make a definitive call on approach A or B when more and more factors are involved. Principal non orthodontic factors here would include restorative capability, cost, tooth morphology and colour and the principal ortho factors are basically where were the teeth to begin with and what is required to move them to somewhere else (and whatever headaches skeletal pattern and root resorption predispositions bring).

    Fair play to the authors on their colossal work here.

    Your own reasoning for choosing a natural tooth over a prosthesis is quite legit, and the paper’s conclusions seem valid but the paper is based on a distillation of high quality results from (I presume) a wide pool of treatments, and critically are bilateral absent incisor solutions.

    I think symmetry allows you to get away with a lot – I can’t back that up with any papers to mind, but the idea that symmetry/balance/proportion are important for aesthetics gets trotted out often.

    To decide one approach is better than another would usually have the small print “….all things being equal”. When they aren’t equal then by definition other factors come into play. And left and right not being equal is a pretty big not equal.

    Anterior tooth morphology will have a big bearing on it too. A patient with one absent incisor may well have an abnormally shaped incisor on the other side, which might make it more difficult for a canine to simulate a lateral incisor. And the canine on the side WITH the incisor may be too mesial. Sometimes the canine has erupted into the lateral incisor space leaving the deciduous canine distal to it and the molars class I on that side – but the canines are class I on the other side. Either way would have anchorage and compliance demands, but it’s easier to distalise a canine to class I than mesialise the rest of the buccal segment to class II relation.

    I think this paper is a great contribution, but I still think making the clinical decision for a given patient will be a head wrecker more days than I’d like.

    keep up the good work

  4. Adel Zakhary says:

    It is interesting to take opinion from lay people. However, beauty is in the eye of the beholder so it is really subjective measure “attractiveness” and I don’t believe applicable to all cases. I think this should’ve been the subject to dentists as they know more about aesthetics (they are grilled for X number of years to get it right!!) as opposed to lay people. I like the methodology but just pointing out that it is still considered weak evidence (4%) and if I were leading it, I’d survey dentists instead on their subject matter.

  5. Michael Donovan says:

    My observation is that the images of replacement lateral incisors are all except one poor examples of restorative dentistry. Maybe what you are saying is that it is difficult to get a good aesthetic result on a low budget! This should not be a deciding factor when it comes to dentistry. It may have to be at some point in practice but should not govern our research.

  6. I am most concerned about lip support, broad arches and smiles and upper incisor inclination. Motherhood issues I know. But with passive self-ligation I extract very few teeth and I have never been happier with the results. To me it very seldom makes sense to treat a non-extraction case with extractions or space closure in the face of missing teeth. And I like to leave the options open for my patients in the future. How long will it be until we are growing teeth in test tubes and implanting real living teeth?

    For my own kids, I would opt for planning a non-extraction case without space closure. That is what I choose for most of my patients.

  7. Giordani Santos Silveira says:

    I invite all of you interested in this polemic issue of the Dentistry, to read the article entitled “Prosthetic replacement vs space closure for maxillary lateral incisor agenesis: A systematic review” published in the August 2016 edition of the AJO-DO.

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