March 27, 2023

What should do we do about upper incisors with delayed eruption?

Delayed or non-eruption of upper incisors is commonly caused by a supernumerary obstructing the normal eruption path.  The widely accepted clinical treatment is to ensure there is enough space and remove the supernumerary.  We then wait 6-9 months for the permanent tooth to erupt.  This is usually successful, and the parents think that you are a genius. Nevertheless,  how effective is this type of treatment and should we use any adjuncts to aid the eruption of upper incisors?  These were the questions asked in this new systematic review.

What did they do?

They did a systematic review and meta-analysis.  The team followed standard systematic review methods of electronic and hand searches, identification of papers and data extraction. They registered the study before they started it.

The PICO was


Patients aged <18 presented with unerupted upper incisors because of a supernumerary tooth.


Any treatment that aimed to facilitate eruption.


Any differences between any intervention


Successful eruption of the upper incisors.

They did not confine their search to randomised trials and included retrospective and prospective observational studies.  We need to bear this in mind when we consider the findings.

The team assessed the risk of bias using the Risk of Bias in Nonrandomised studies of interventions (ROBIN-I) tool.

Finally, they did the relevant meta-analysis, evaluated heterogeneity and measured the strength of evidence using the GRADE approach.

What did they find?

At the end of the search and various filtering they identified 15 studies. Fourteen of these were retrospective and only one was prospective.  The total number of patients was 980, with a mean age of 9.1 years.  In ten studies, the supernumerary was removed to enable the eruption of the incisor. In the other five studies, the supernumerary was removed, in addition to space management or surgical exposure and traction.

When they looked at the risk of bias, they rated nine studies as moderate and five as high risk.

The meta-analysis revealed the following.

  • Analysis of 11 studies showed that 57 % of the incisors that had removal of the supernumerary only erupted (95% CI=47.8-67.0).
  • When the supernumerary was removed, space created or maintained, and traction was done, the success rate was significantly higher at 82.4% (95% CI=65.5-93.2) and 96.9% (95% CI 83.8-99.9). However, this data was derived from single studies.
  • The odds of successful eruption were improved if the supernumerary was removed in the primary rather than the secondary dentition OR=0.42 (95% CI= 0.20-0.90).
  • When they evaluated the overall certainty of the evidence with the GRADE method, they found a low level of certainty for all of the comparisons.

The team concluded:

“Limited evidence suggests that adjunctive use of orthodontic measures and removal of any associated supernumeraries might be associated with greater chances of the successful eruption of an impacted incisor compared with removal of the supernumerary alone”.

“Importantly, these findings should be viewed with caution because the certainty is very low because of bias and heterogeneity”.

Finally, the authors pointed out that the findings of this review have been used to inform and justify a trial.

What did I think?

I have previously mentioned that too many orthodontic systematic reviews do not add to our knowledge. Indeed, we could suggest that the most common reason for doing a review is to build a CV. In fact, we should only conduct a systematic review to answer a new question, provide evidence, and inform a trial.  This review satisfies these requirements, which is why I have posted about it.

The authors rightly pointed out that the risk of bias was high. In many ways, this was likely with their decision to include non-randomised studies. As a result, they have been cautious in their findings and conclusions.

We now need to consider whether the findings would change our practice. Whenever I saw a child with a supernumerary and unerupted maxillary incisor. I made the standard approach of creating or maintaining the space (if necessary) and removing the supernumerary. I did not bond a bracket to the incisor; I let it erupt. The results of this review do not provide significant strength of evidence to encourage me to change my practice. But the results of their trial should be interesting. What do you think?

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Have your say!

  1. Agree, sometimes they erupt spontaneously and sometimes they don’t. A prospective randomized study will be very interesting to read. Impressive if they manage to get enough patients as they are not that common. We should do more multicentre studies when it comes to relatively uncommon conditions.

  2. As a perio exposing a lot of impacted teeth, when I am asked to extract a supernumerary tooth adjacent to a central incisor, I think first about the patient and I prefer to do the maximum in one session. So I bond a traction device. Between Jan 2010 and dec 2022, I have exposed 1365 impacted teeth including 60 upper central incisors. The mean age of the surgery was 10y-4m ( from 7y-9m to 14y-1m). 26 females and 30 males. 4 patients with double impaction. 100% crowns in a buccal position. 100% teeth positioned in the dental arch at the end of the combined ortho-perio treatment

  3. I totally agree with above comment . The financial/biological cost and inconvenience of the second surgery ( in case of failure of the spontaneous eruption) are determining factors for me to start traction for most cases.

  4. On the whole, I think traction bonding to the impacted tooth at the time of removal of the supernumerary tooth is the best option to reduce inconvenience and trauma for the patient.
    However, on the few occasions where there is no indication for orthodontic treatment other than the impacted tooth (ie class 1, uncrowded cases), I will ask for the supernumerary to be removed and keep the impacted tooth under observation until it erupts.

  5. Dr. O’Brien,

    The findings of this study somewhat parallel the recommendations of Dr. Adrian Becker who many consider the expert on impacted teeth. He writes that it is imperative to remove the supernumerary and to create adequate space for the central incisor, however, the percentage of teeth that subsequently erupt is difficult to determine. He further divides the problem based on age. One is probably more aggressive in older patients than younger.

  6. I used to remove and wait, few cases erupted with 6 months waiting period. i ended up with surgical exposure of the incisor and traction. I had many parents asking why hadn’t we exposed from the beginning?
    I am now more toward surgical exposure but still giving parents the option.

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