Oral Health Group

Timing and Assessment of Ankylosed Deciduous Molar Teeth – A Case Report

September 1, 2013
by Peter Konchak, DDS, Dip. Paed, Dip. Ortho; Brad Low, DMD

Ankylosed or submerged deciduous teeth are teeth that do not keep up with other teeth in the quadrant in their vertical development. As a result, this may cause significant problems in eruption, often with severe bone loss and migration of deciduous and permanent teeth. The first and second deciduous molars are most commonly involved teeth with the second deciduous molars generally causing more damage. In the literature there are two groups, those advocating leaving the ankylosed teeth in position and those who believe the ankylosed teeth should be removed and space maintainers placed.1 Advocates of retaining ankylosed teeth will even place stainless steel crowns or other build ups to maintain occlusal contact with the opposing dentition. This article will advocate that the teeth which are submerging be assessed where submergence is noted taking proper action based on a review of bitewing/pan radiographs taken sequentially. If there is evidence that significant submergence is taking place extraction and space maintenance is indicated. If the deciduous teeth cease to submerge and significant damage has not occurred then the deciduous teeth may be retained. Any change in the axial inclination of teeth, which are next to the teeth submerging strongly indicates removal and indeed may indicate acting too late.

This five-year-old female was first seen in the pediatric clinic (July 24, 2005) and followed subsequently for a period of nine years. A normally developing deciduous dentition with no evidence of submergence was present. The patient was reappointed on January 26, 2007 and again no submergence was noted. However, a pan taken on January 7, 2010 shows deflection of 15, absence of 25 and considerable submergence of all four deciduous molars (Fig. 1). The pan was repeated (Fig. 2) on October 13, 2011 and periapical radiographs (Figs. 3,4,5) were taken of deciduous second molars and developing/missing second permanent bicuspids. After reviewing this pan, it was decided that all the deciduous second molar teeth should be removed. The submerging second deciduous molars were removed on February 2, 2012. Sectioning of some teeth was required. The patient was reappointed and a transpalatal bar (Nance Holding Arch) was constructed to prevent space loss in the maxillary arch and a lingual holding arch for the mandibular arch. Space analysis of both arches indicated that the case be treated non-extraction.


The tendency to wait and see is often what happens in these cases. Some of the literature even supports this action. However, bone is often destroyed as the second deciduous molars sink further into the tissues. The periodontal ligament which is attached to the six-year molars and the first deciduous molars/first bicuspids can cause these teeth to tip into the second deciduous molar space further impacting the second deciduous molars.1 Developing bicuspid teeth can be deflected from where they would normally develop (see position of 15 and 45 on October 13, 2011 pan, Fig. 2). Once the teeth have been removed considerable bone loss is often evident causing loss of attachment and bone. Although it is true that many deciduous teeth which have submerged can be retained the clinician must decide which ones and how long the operator waits. This depends on the degree of submergence and in what time frame. When one notices that a tooth has started to submerge and still does not require any treatment it is advantageous to take a bitewing and measure the vertical distance in millimeters. The patient should be reappointed in a year to see if further submergence has taken place and see if treatment is necessary. If significant submergence is not seen recall the patient in one year. If submergence is continuing the tooth is likely best removed and a space maintainer placed. The trouble with leaving these teeth is that the patient may move or not come in as planned. Monitoring these cases can be done at the same time as the patient’s dental exam; however, the parent should be advised of the consequences of not following these teeth on a yearly basis. Often, first deciduous molars are those submerging deciduous teeth left as damage is usually not as significant as with second deciduous molars.

After 55, 65, 75 and 85 were removed bands were fitted on all permanent first molars and a fixed soldered lingual holding arch (Fig. 6) was constructed from 36 to 46 and inserted on March 8, 2012 and a Nance Holding Arch (Fig. 7) from 16 to 26 on March 23, 2012.

The design of the Nance appliance is shown to consist of the bands, a palatal arch (.036″) and an acrylic button and fingersprings distal to 14 and 24. The arch wire is .036 inches; the appliance was placed to prevent space loss and mesialization and/or rotation of 16 and 26. Figure 6 shows the mandibular space maintainer (.036″) which consists of Wilson loops with the arch soldered directly to the bands on 36 and 46. These appliances are necessary to maintain arch perimeter and the molars in a Class 1 relationship. Adjacent teeth continue to develop and migrate occlusally as alveolar bone continues to develop.

Figure 8 shows the bands in the impression. Figure 9 shows adequate sticky wax to prevent bands from being dislodged when pouring the impression. The coecal mix should be made initially slightly thinner than normal and at no time should a vibrator be used as this causes bands to dislodge from the impression. After the initial mix has been flowed into the impression the mix can be thickened to normal consistency and the base completed. Both casts are then allowed to harden and a prescription completed and sent to the laboratory for construction. At the follow up appointment both appliances are cemented into position and light-cured.

This case shows the steps that may be taken to prevent continued submergence and severe bone loss and tipping of the adjacent teeth into the area of the submerging teeth so often associated with waiting and observing. The rationale for removing the mandibular deciduous second molars is to prevent mesialization, tipping and space loss of 36 and 46 and distal tipping of 34 and 44 into the area of the submerging tooth caused by the periodontal fibers which act as an orthodontic force. In the mandibular arch, the lingual holding arch is the preferred appliance as it can be left in position until 35 and 45 erupt. Tooth 45 may take a considerable time before it erupts into the mouth.

Although 25 is missing, it is a potentially serious mistake to leave 65 in position. Tooth 65 needs to be removed as discussed above to preserve bone, prevent further submergence and preserve space for a future implant or bridge. All too frequently the periodontal fibers will pull the maxillary molars and the permanent bicuspids upwards into and over the deciduous second molars. If the second deciduous molars continue to submerge, when they are eventually removed considerable bone loss has resulted. Figure 10, 11 (September 11, 2012) shows periapical views of 15 and 45 erupting and bringing bone with them as they continue to erupt.

The literature is split on when submerging teeth should/need to be removed. However, the destruction caused by leaving them in place often results in as severe local damage as one sees in patient management of the young child. A submerging tooth, especially in the case of a maxillary second deciduous molar, should be removed and adequate space maintenance provided if there is any continued submergence noted. With families moving as they do nowadays these teeth, which may be identified by the first dentist and left, do cause severe damage. When seen by the next dentist, it is often too late at this time as the destruction has already occurred.

On November 9, 2011, post-treatment photos (Figs. 12-17) and a pan were also taken (Fig. 18). Tooth 35 has erupted into the mouth and tooth 45 with approximately half the root structure, has erupted slightly lingually and will
erupt further. The lingual holding arch will be left until 45 is in. In the upper arch, it appears as though 15 has drifted distally into a better position. It is, however, prudent to wait and see if 15 will erupt or whether it will need orthodontic assistance to erupt. Space is being kept for an implant with bone graft for missing 25.

Extraction of the deciduous teeth with adequate space maintenance has put this case in a much better position than if the case had been left untreated. OH

Professor Konchak is a full-time teacher and Head, Division of Orthodontics, College of Dentistry, University of Saskatchewan.

Brad Low is a graduate of the College of Dentistry, University of Saskatchewan (2013).

Oral Health welcomes this original article.


1. Konchak, P.A. and Koroluk, L.D. Considerations and Options in the Treatment of Ankylosed Teeth Journal of Oral Health, 1992; 82(9):13-18.

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