An orthodontic perspective on replacing missing maxillary incisors.

This is an unusual post because I am going to look at an opinion piece in the AJO-DDO on whether we should space-close or use an implant to replace maxillary incisors. I decided to do this because I thought it was interesting and clinically relevant.  Furthermore, this is a controversial area, and this paper provides an excellent basis for discussion.  Nevertheless, we need to remember that the role of an opinion piece is to stimulate discussion, and it is not a high level of evidence. I will try to stick to my normal style.

A team from South Africa, the USA and South Korea wrote the paper. The AJO-DDO published the paper.

What did they ask?

They wrote this paper to provide information on 

“The treatment considerations for treatment selection, complications and evidence-based guidelines for the management of missing anterior teeth”.

What did they do?

They condensed the available evidence on options for replacing missing maxillary incisors.  Importantly, this was a “traditional” non-systematic review.

What did they find?

Firstly, they suggested that the options for this problem were canine substitution to close the space, bridges, autotransplantation and implants. They then discussed these options in more detail, with an emphasis on how facial growth affects treatment success.

Growth and implants 

We all know that we are experts in facial growth. However, we need to remember that facial growth doesn’t simply cease in the late teens. It continues at a much slower rate throughout adulthood. As a result, compared with an ankylosed implant, the vertical and horizontal movement of the teeth and the alveolus increases the risk of implant submergence. This is referred to as implant infraposition and is a considerable problem because its correction can be difficult. 

Some may argue that growth potential can be determined using hand-wrist radiographs and cervical vertebral maturation; however, these methods have been shown to be comparatively inaccurate for the individual patient. As a result, no definitive criteria or diagnostic methods exist to indicate when dental alveolar changes have ceased. 

The authors of this paper noted that systematic reviews have shown that nearly half of patients with implants develop an infraposition. As a result, we should carefully consider the appropriate timing for implant placement or look for alternatives.

Alternative Treatment Options 

One of these is of bridges. There is, of course, reluctance to prepare unblemished teeth as abutments for a fixed bridge. As a result, this form of treatment is not popular. 

The other alternative is, of course, orthodontic space closure. They pointed out that we have to consider the whole malocclusion when planning this treatment, but importantly, the use of temporary anchorage devices may make this an option in many cases. 

It goes without saying that one consequence of replacing a missing lateral incisor with a canine is that treatment is necessary to ensure the canine resembles the lateral incisor. This may be rather complex, but it should be within the skill set of most dentists and certainly of specialists.  

This also depends on the canines’ morphology, size, and colour. Another concept to consider is whether group function, rather than canine guidance, is acceptable. Importantly, there is no evidence supporting a preference for either option. 

There are, of course, other issues, such as symmetry, when one lateral incisor is missing. Finally, we need to consider whether there is an age at which we can safely placed an implant in the anterior region without adverse effects. I felt that they suggested there was no definitive answer to this question because the craniofacial complex continues to adapt. 

Key takeaways

At the end of their discussions, they identified several key takeaways for us to bear in mind. 

“Growth and development will continue well into the third decade, and there are no reliable methods to determine when dental alveolar development ceases. Importantly, the reported incidence of IIP is between 50% and 75%, and it is very prevalent when implants are placed during the second and third decades. As a result, treatment methods that promote stable and aesthetic outcomes should be recommended”. 

What did I think?

This was an interesting overview of a relatively complex clinical problem. They wrote a clear paper and outlined several concepts very well. I think it is still important to point out that these guidelines are not necessarily based on high levels of evidence. We also need to remember that guidelines are not mandatory.

However, in the absence of high-level research, when we consider the concept of evidence-based care, this information is, arguably, useful. This paper achieves its aim of encouraging discussion.

Some may feel the content of this review is rather obvious, and we are well aware of the decisions we need to take and the factors that influence them. Nevertheless, I can’t help feeling that if these concepts are obvious, why do so many patients end up with implant infraposition in the anterior maxillary arch? 

My only concern with this paper is that I wish the authors had been a little more definitive in their conclusions and had made a recommendation on which option was best: space opening or space closure. After reading this paper several times, I felt that the decision still remained mine. This may have been their intention, but it does nothing to diminish my poor tolerance of uncertainty.

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