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References

Varpio M, Wellfelt B Disturbed eruption of the lower second molar: clinical appearance, prevalence, and etiology. ASDC J Dent Child. 1988; 55:114-118
Grover PS, Lorton L The incidence of unerupted permanent teeth and related clinical cases. Oral Surg Oral Med Oral Pathol. 1985; 59:420-425 https://doi.org/10.1016/0030-4220(85)90070-2
Fu PS, Wang JC, Wu YM Impacted mandibular second molars. Angle Orthod. 2012; 82:670-675 https://doi.org/10.2319/102111-656.1
Shpack N, Finkelstein T, Lai YH Mandibular permanent second molar impaction treatment options and outcome. Open J Dent Oral Med. 2013; 1
Shapira Y, Finkelstein T, Shpack N Mandibular second molar impaction. Part I: Genetic traits and characteristics. Am J Orthod Dentofacial Orthop. 2011; 140:32-7 https://doi.org/10.1016/j.ajodo.2009.08.034
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A simple way to manage impacted second molars

From Volume 16, Issue 2, April 2023 | Page 105

Authors

Elizabeth O'Higgins

Consultant Orthodontist, Kings College Dental Institute, London

Articles by Elizabeth O'Higgins

Article

Were you a Damon enthusiast? Wondering what to do with all those self-ligating brackets and molar tubes you still have lying around? Outlined in this Trick of the Trade is a simple method for aligning impacted second molars using self-ligating molar tubes.

Impaction of second molars has a reported incidence of between 0.03% and 1.7% in the general population, with a higher incidence encountered in orthodontic patients.1,2,3,4,5 The second molars are usually mesio-angularly impacted against the distal surface of the first molar, and to attempt disimpaction requires a distalizing and uprighting force. This can be applied using an uprighting spring attached to the main archwire, or a mini-screw.4 The problem with this method is, that apart from involving some intricate wire bending, to ensure adequate vertical anchorage, the main archwire needs to be a minimum of 0.018” stainless steel that can only be placed following levelling and aligning. This can lead to a delay in treatment while the second molar is then aligned before the working archwire can be placed to complete levelling of the lower arch and any space closure. Therefore, it would be better to disimpact the second molar at the same time as the initial phase for levelling and aligning the lower arch. Alternatively, skeletal anchorage can be used in the form of a mini-screw to which an uprighting spring can be applied.6

Sometimes in milder cases of impaction of the second molar, this can be achieved just by placing an attachment on the lower second molar and engaging the archwire. However, in more severe cases, the tooth will need a distalizing force that can be applied using compressed coil spring. With traditional molar tubes this can be very difficult to apply. However, with self-ligating tubes, the coil spring can be placed on the archwire, positioned mesially to the impacted second molar and then engaged and activated as the slot on the self-ligating tube is closed (Figure 1). Once the second molar is distalized and uprighted, it can be then be fully engaged and treatment completed (Figure 2).

Figure 1. (a) Lower left second molar mesio-angularly impacted. (b) Labial fixed appliance with Damon tube on first molar with compressed nickel titanium pushcoil on initially aligning nickel titanium archwire applying distalizing and uprighting force to second molar.
Figure 2. (a) Lower second molar now disimpacted. (b) Working archwire in place and final space closure.