Impacted upper canines occur, in buccal or palatal sites, in about 3% of the population and pose a threat to neighbouring teeth. Before orthodontists can bring them into their proper positions in the arch, oral surgeons often have to uncover them. In this article we discuss the traction pathways, open or tunnelised, that orthodontists can then use to begin moving them. While orthodontists can use both techniques successfully, they should understand the advantages and disadvantages of both before making a decision.

When a maxillary canine has not appeared in the arch at its scheduled time of arrival, the treating dentist should make a precise analysis of the possible factors responsible for its absence and devise the best therapeutic plan for correcting the problem. Factors to be considered are its agenesis or the more likely possibility of anomalies of tooth size and eruption patterns. Deciding whether to bring an absent canine into place orthodontically or to replace it prosthetically or with an implant almost always constitutes a sort of therapeutic wager.

This article proposes a method for the systematic appraisal of the management of a missing maxillary canine using a decisional tree of the “in cases where” type. It allows for questionable issues to be grouped in logical order, starting with diagnostic procedures that lead to the beginning of a step-like therapeutic sequence that concludes, if it proves negative, with the development of an alternative to the initial treatment plan (fig. 1).

This arboreal schema is comprised of three parts:

     1 – The first deals with diagnosis;

     2 – The second takes up the start of treatment in consideration of the position of the tooth and the possibility of its being ankylosed or becoming ankylosed;

     3 – The third is concerned with replacing the missing canine tooth in accordance with the dictates of implant or prosthetic therapy, or of an orthodontic solution to the problem.

In view of the present environmental awareness, the reduction of spray wastage, which in turn lessens environmental contamination, can be achieved by reducing spray volumes and improvement on spray efficiency through the use of correct ranges of spray droplet sizes. Published data on droplets collected by some insects consistently suggest that the optimum droplet sizes lie below 60 μm.

An experiment was conducted in a wind-tunnel to assess the locust collection efficiency when subjected to a spectrum of droplet size ranges with a view to determine the optimum droplet size.

Locusts were induced to fly in a wind-tunnel and then exposed to spray droplets which were produced by a spinning disc atomiser. Droplets collected on antennae, head, abdomen, legs and wings were sized and counted. The collection efficiency at wind-speeds ranging from 2 m/sec to 6 m/sec was calculated for the different body parts in the droplet size range 10–40, 40–60 and 60–80 μm. The calculated collection efficiency for the 10–40 μm size range was comparatively higher for all locust body parts.