An occasionally irregular blog about orthodontics

What can we do about missing lateral incisors?

By on September 26, 2016 in Clinical Research, Recent posts with 13 Comments
What can we do about missing lateral incisors?

What can we do about missing lateral incisors?

One of my most popular posts was on the dilemma of whether we should open or close space to replace missing lateral incisors. This generated a lot of debate. Do we have more evidence on this important question?  A systematic review that the AJO-DDO has just published may help us….

Prosthetic replacement vs space closure for maxillary lateral incisor agenesis: A systematic review

Giordani Santos Silveira et al

Am J Orthod Dentofacial Orthop 2016;150:228-37


screen-shot-2016-09-25-at-13-16-43A study team based in Rio de Janeiro wrote this paper. They started by clearly outlining the issues concerned with space opening or closing and prosthetic replacement. They then listed the factors which influence our treatment decision as:



  • The aesthetics of canine substitution for a lateral incisor
  • The need for canine guidance to keep the occlusion “healthy”.
  • Whether space closure was indicated, if there was crowding
  • Any possible effects on periodontal health
  • The need to avoid prosthetic replacement.

They carried out the systematic review to answer this question

“What is the best treatment for patients with missing lateral incisors”?

What did they do?

I found this review rather difficult to read, but I have interpreted the PICO

Participants: Orthodontic patients treated with fixed appliances

Intervention: Any orthodontic treatment apart from craniofacial and orthognathic care

Comparison: Space opening or closing for missing lateral incisors

Outcomes: Aesthetics, gingival/periodontal health, occlusal function and canine guidance

When I looked closely at their selection criteria for the papers, I found that they did not attempt to restrict the papers to randomised trials. This meant that they included all types of study. This is important and I shall discuss this later.

After their literature search they included 9 studies in the review. These were all case-control retrospective studies.

They assessed the risk of bias with the Newcastle-Ottowa Scale. This showed that the studies were at high risk of bias because of small sample sizes, unclear outcomes, unclear interventions and no blinding.

What did they find?

It was not possible for them to combine any data in a meta-analysis because of the great variation in methods and outcomes between studies. However, they did manage to carry out a narrative review. I found this difficult to interpret. But this is what I worked out

  • Space opening with prosthetic replacement may influence periodontal and gingival health.
  • Space closure resulted in better aesthetics than opening and prosthetic replacement
  • Canine guidance did not seem to be important.

In their discussion, they pointed out that there were problems with this review because the studies were at high risk of bias. They also mentioned that many factors influence the clinical decision and is not straightforward.

What did I think?

I am not sure about this paper. I think I would like to take a step back and consider the merits of carrying out a systematic review, as opposed to a traditional review.

The first is that the study team systematically identifies papers and they do not “cherry pick” a selection of papers that supports any pre-conceptions that they may have. I feel that the authors have done this well.

The second merit of a systematic review is that it should only include papers that are randomised controlled trials or controlled clinical trials. This is essential to ensure that only high levels of evidence are included. This review does not achieve this aim because the papers are retrospective studies at high risk of bias. As a result, it only provides us with a low level of evidence. The authors do clearly state that this was a problem.

If I take all these factors into consideration, I am disappointed to conclude that the conclusions cannot really be supported by the study methodology or the data.

I think that it is also relevant to point out that there has been little research on the replacement of missing lateral incisors with implants.  Most of the papers evaluate the appearance etc of resin bonded bridges.  However, little is known about the long-term appearance and stability of implants.  This adds to the clinical dilemma.

In summary, this paper does not really help us with this clinical problem. We still do not know whether it is best to open or close lateral incisor space. I will still attempt to close as many spaces as possible in order to avoid any problems that may occur with long-term prosthetic replacement. But I know that other orthodontists do not share this viewpoint, which is based solely on my clinical experience. Unfortunately, this may be the highest level of evidence that we have on this tricky problem.

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  1. vicki vlaskalic says:

    THX Kevin – I was interested to note the absence in the authors main list of the first and second factors that I take into consideration – facial balance, particularly upper lip support and secondly existing posterior interdigitation. Wonder if the “aesthetics” evaluation post -treatment included facial soft tissues or simply dental aesthetics?

  2. Hi Dr Kevin
    your blog is very interesting, the question the same I asked myself, I think the timing in the solution of the problem of missing lateral incisors is important because you can’t put implants in a patient that is growing, so I would prefer to close the space for that reason in young patients, not to have to wait so long for the permanent solution, a carefull diagnosis and study of th particular case must be done of course.

  3. Tony Collett says:

    Thanks Kevin. I am still waiting for a blog I can really disagree with. This is always a tough decision. I prefer to close if we can. If it is Class II/1 at least the space can be burnt while reducing the overjet. The toughie for me is the minimal overjet and spaces to close, but perhaps not enough to open for aesthetic laterals. Trying to stop the incisors coming back and ending up with fremitus. And sometimes I have opened spaces ready for the prosthodontics. The patient is now 18+. Mum and Dad now don’t want to pay (more so if separated since the active treatment) and the patient decides the money would be better spent on the overseas backpacking trip, new car etc. It is frustrating when money gets in the way of a good outcome.

  4. Bob Stoner says:

    After 33 years of treating missing laterals I have tried both. Closing space is almost always better as it reduces cost and susceptibility to problems with the implants. In extraction cases removing the contralateral lateral and the lower 1st premolars works out great. Reshaping laterals and slightly rotating premolars and reducing their lingual cusps slightly is a great treatment. There may at times be some esthetic compromise, but it is a risk reward issue.

  5. Dr. Ramesh says:

    As a Prosthodontist, I am not able to come to terms with the inference of the study that “Canine guidance did not seem to be important”.
    Please don’t let such ideas into the scientific world, as young minds will be negatively influenced by it.

  6. hero breuning says:

    Hello Kevin, I know that this is not a scientific reply at all, but I became interested in orthodontics, because, my sister has agenesis of two lateral incisors, two off my daughtrs have also agenesis of lateral incisors. My sister and oldest doghter were treated without prosthetic replacement of the incisors. The both had problems with their articulation: the central incisor of my sister broke maybe because of articulation problems. My oldest daugther had problems with the first upper molar, the molar broke, possibly becuse of articulation problems. The dentit evaluated the occlusion with the T-scan (another interesting topic for your blog).
    After correction of the occlusion and articulation and a splint during the night solved their problems. I decised to distalize the cuspids during orthodontic treatment of my yougest daughter. She got two implants at the age of 23.
    Esthetically and functionally it is still ok after 10 years. The aesthetics of the dentition of my oldest daughter improved when she got 6 facings at the age of 36.

  7. Ewa Czochrowska says:

    Kevin, I fully agree both with your critisim and your clinical opiion regarding the treatment for missig maxillary lateral inciisors. I think, that it is not necessary to perform a systematic review on this subject, because there are no RCT studies. It can be just a summary of the findings from retrospective studies in this field. In my opinion it is very difficult, if ever possible, to perform the RCT, because treatment choices depend on different factors including occlusion, space condotions, profile, operators’ skills and very important patients’ wishes. I think, that probably a multicenter cooperation is necessary to collect large gropus of patients to perform proper ramdomisastion and evaluate the outcome

  8. John McDonald says:

    Kevin, I think the value of this study is that it shows that when well done, canine substitution is as good if not slightly preferred by many people. I think many restorative dentists have seen one or more poorly done canine substitutions and they don’t realize that it can be set up for a nice result. The fact that this was in the AJO-DO, both case types were well treated examples, and the photography was excellent will insure that this article will be used in discussions of these cases across the country and around the globe. Once dentists (and Orthodontists) overcome a preconceived notion of the overall aesthetic superiority of one over the other, the discussion can move to the many other factors that go into making the right decision in these types of cases.

  9. Peter Doyle says:

    Hi Kevin I Agree with your conclusions about study. I am always surprised facial profile and lip support doesn’t feature more prominently in all these studies . Teeth photographs alone will just not do . We treat faces first, teeth second.

  10. Peter Southall says:

    Kevin thanks for your blog, always educational, and re-assuring when the findings reinforce my own beliefs and habits!
    I totally accept the power of the systematic review and Cochrane in particular, but I have been thinking about whether we might be over using them from time to time. For example this study seems to suggest that if we can either open or close space that one must be better than the other. I would contend that because of other variables (crowding, tooth morphology, facial aesthetics etc) some patients are likely to have a better result with opening, some with closing. It seems to me that under these circumstances a systematic review outcome favouring either treatment modality is merely reflective of the casemix.
    On the other hand, faster space closure with NiTi or steel springs, there’s unlikely to be any pre-existing variable that would favour one material, and the result was clear. I wonder about retainers. Might there be any pre-treatment variables that favour either fixed or removable retainers? How would systematic review work then?

    • Kevin O'Brien says:

      Yes, you have made a good point. I wonder if pre-existing conditions will not have an effect in a trial. But this can only happen if the sample size is sufficiently large and many orthodontic studies are rather small. I will need to give this some thought and return to it in a future blog posting

  11. João Joaquim Neto says:

    Nice evaluation, Dr. O’Brien.
    While many (including me) only read the conclusions, you discussed the method used by the authors. Thank you.

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