Impaction of the maxillary second premolar due to a severely infraoccluded deciduous predecessor

Published: December 2012

Bulletin #17 December 2012

Impaction of the maxillary second premolar due to a severely infraoccluded deciduous predecessor

When a maxillary deciduous second molar tooth is extracted early, the permanent molar immediately distal to it will usually drift into the space created, in a mesial tipping and palatal rolling movement. At the same time, but to a lesser degree, the first deciduous molar or first premolar may drift distally and the second premolar space will thus be reduced. The erupting second premolar will eventually become deflected, to the palatal side of the line of the arch, between first premolar and first molar or, less frequently, it may remain in the line of the arch, vertically impacted between the two. Following the early extraction, the orientation of the long axes of the immediately adjacent first premolar and first molar will change from parallel to one another initially, to a mild but definite convergence in the apico-coronal direction. If space is regained early enough, the chances for the eruption path of the second premolar to self-correct are much improved. Simple tipping of the two adjacent teeth is enough to restore the space and to cause their long axes to be paralleled again.

Is the picture the same when there is severe infraocclusion (submergence) of the deciduous second molar?

Infraocclusion of deciduous teeth has been charted by Kurol1-7 and associates in Sweden (ref) and others8 in a number of published studies of the phenomenon. In a series of 3 studies of infraoccluded mandibular second molars, published by our group in Israel9-11, it was concluded that the degree of tip of the adjacent teeth is much greater than that caused by early loss of deciduous teeth due to caries. The reason for this was more because of a distancing of their root apices, rather than actual space closure at the occlusal level. This finding means that simple corrective re-tipping of the first premolar and the first molar back to paralleled long axes will create a space which is mesio-distally larger than needed for the unerupted/infraoccluded tooth between them. Furthermore and in a second significant finding, it was noted that the infraocclusion of the affected deciduous molar secondarily caused the adjacent teeth to be relatively under-erupted.

It is very difficult to measure a difference between the tipping caused by a simple extraction and that due to a mild degree of infraocclusion. What is apparent is that with a greater degree of infraocclusion, the difference becomes much more obvious. Gathering a sample of sufficient size to study the character of the more extreme examples of the phenomenon in the maxilla is more formidable, because of their relative rarity. Nonetheless, clinical observation of some very severe cases of infraocclusion indicates that similar features are seen in relation to angulation and relative under-eruption of the adjacent teeth in the upper jaw, too. For all that, however, these may usually be corrected orthodontically with little trouble. Clearly then, the picture is not the same as that seen following early extraction of a deciduous tooth!

So what is the problem?

The major problem that arises is that infraoccluded deciduous second maxillary molars are closely associated with and possibly directly the cause of a marked displacement and impaction of the second premolar, into locations and angulations that seem to be intractable. The mere thought of trying to bond an attachment to them at the time of surgery is both daunting and intimidating. However, in truth, a simple approach is available, successful with a relatively high degree of reliability and does not require the placement of a bonded attachment.


Fig. 1a. Panoramic view of patient #1 with a maxillary left side impaction of the second premolar, caused by a deeply infraoccluded second deciduous molar.

Fig. 1b. The relevant section of the same panoramic view with labeling of the individual teeth, for ease of reference.

Fig. 1c. The lateral skull view shows the height differential in the maxilla between the superimposed right and left sides, while the mandibular dentition shows no parallel anomaly. The teeth of the affected side of the maxilla are markedly vertically under-developed.

In last month’s bulletin (Bulletin #16 November 2012) on this website, the successfully treated case of a palatally-impacted labial canine was discussed. The neighboring second premolar of the same side was palatally impacted, with an extreme displacement in the three planes of space. Its developing root apex was located mesially and close to the canine root, its crown was pointing distally, inferiorly and lingually and the tooth was at the level of the roots of the adjacent teeth, with a 90 degree rotation. We shall refer to this young male as Patient #1 (Fig. 1a-f).


Fig. 1d. The intraoral photographic views of the dentition.

At the same time, there was the enamel shell of the crown of the unexfoliated deciduous second molar, whose entire root and the dentinal contents of its crown had been resorbed away, high in the maxillary alveolus. It was severely submerged lateral to and slightly above the level of the premolar and had obviously become progressively infraoccluded and buried in the tissues. It was buccally and superiorly located to the second premolar.

The adjacent first premolar (on the mesial) and first permanent molar (on the distal) were tipped towards each other to such an exaggerated degree that their long axes formed an almost 90 degree angle, with their crowns in mesiodistal contact.


Fig. 1e. At the end of treatment, the second maxillary premolar is seen here following its successful spontaneous eruption, following space opening and surgical removal of the enamel shell of the deciduous molar.


Fig. 1f. Panoramic view at the completion of treatment. No attempt had been made to surgically uncover the second premolar nor to place an attachment before it had erupted spontaneously. The maxillary left second permanent molar had been extracted in order to facilitate the distal tipping of the first molar. (These illustrations appear in Orthodontic Treatment of Impacted Teeth, by Adrian Becker 3rd Edition published by Wiley-Blackwell Publishers, Oxford, 2012 © Adrian Becker)


The etiology of impaction of the second maxillary premolar in these special circumstances is directly related to the presence of its infraoccluded deciduous predecessor. That the over-retention of a deciduous tooth is likely to cause the non-eruption or impaction of its successor is obvious, but why this should produce the frequently seen bizarre displacements of the unerupted premolar, is unexplained.

Differential diagnosis

The principal condition that exhibits similar clinical signs is primary failure of eruption (PFE).12-14 PFE affects all teeth distal to the most mesial involved tooth involved and is associated with a posterior open bite. It does not occur in a single deciduous molar, while the adjacent teeth erupt into occlusion and neither does it generate a loss of space with tipping of the teeth adjacent to the infraoccluded tooth. Furthermore, the teeth affected by PFE are unresponsive to orthodontic forces, while the appearance of the lateral open bite, under-erupted teeth and poorly developed alveolar ridges are very characteristic and recognizable signs of the condition.

Maxillary second premolar displacement and impaction due to the exaggerated infraocclusion and, often, reburial of the tooth in the tissues, has a very typical appearance and is usually unilateral. While similar to PFE in that it is frequently associated with under-eruption of the adjacent teeth and/or lateral open bite, it responds well to orthodontic space opening and removal of the deciduous tooth.

In the case of Patient #4 described below, the long term serial radiographic follow-up of the case presents a confusing picture due to the severity of the bilateral and bimaxillary occurrence of impacted premolars and reduced posterior vertical alveolar development. The diagnosis was confirmed by the combination of the successful achievement of orthodontic space opening and the surgical removal of the deciduous teeth.

Treatment options

Each of the treatment options that could be considered in this case included the extraction of the residual crown of the submerged deciduous second molar. In addition, the following alternatives were thought to be appropriate:-

  1. extract the impacted second premolar and upright the roots of the severely tipped premolar and molar. Close excess space from the distal.
  2. extract the first molar and align the impacted second premolar in its place. The first premolar would need to be uprighted by mesial tipping and close excess space from the distal.
  3. extract the first premolar and align the impacted second premolar in its place. The angulation of the first molar would need to be corrected by mesial root uprighting.
  4. extract the second permanent molar, tip the first molar distally and the first premolar mesially to re-parallel their roots. Align the impacted second premolar into its designated place.

Alternatives #1, #2 and #3 would need for thought to be given to a possible compensating extraction on the opposite side of the arch, where the occlusal relations were ideal, or the use of a temporary anchorage device, in order to resist the likelihood of the treatment secondarily causing a shift in the dental midline. Alternatives #2, #3 and #4 could be recommended only in the event that there was a high degree of certainty that alignment of the second premolar was feasible.

In this particular case, option #4 was chosen. Evidence-based support for the validity of this line of treatment has yet to be published and so the decision was made on the basis of results achieved in similar circumstances in other cases.

The sequence of events in this treatment plan required the extraction of the second permanent molar, followed by distal movement of the first molar and mesial movement of the first premolar, to create the space necessary to provide access for the surgical removal of the buried deciduous tooth. No attempt was to be made to expose the impacted premolar, which was to be monitored over the succeeding months. It was expected that, given the removal of the deciduous obstruction and the availability of space in the dental arch, a favorable and spontaneous improvement in its position and eruptive status was likely – an expectation based on earlier experience.


If we refer back to the description of the case, as it appeared in last month’s bulletin, it will be noted that before attention was turned to the palatally-impacted labial canine, there was a time lapse between the commencement of the treatment in June 2009 and the placement of the fixed appliance in November 2009. Immediately following the extraction of the second permanent molar, a removable orthodontic plate was placed carrying simple finger springs to tip the first molar distally and the first premolar mesially.

An excessive amount of space was deliberately opened up in this 5 month period. During this time, it was noted that the unerupted second premolar had begun erupting into its place in the arch, having side-stepped the over-retained deciduous molar. A transpalatal arch was soldered to molar bands to maintain the molar position and surgery was immediately performed to remove the buried enamel shell of the deciduous tooth. No further treatment was delivered to the second premolar, which continued to erupt into an acceptable position, unaided.

Common features seen with this anomaly

No two patients are the same, nevertheless, in these cases of infraocclusion and impaction, there is a common thread that links them in their clinical and radiological features and in the response of the impacted tooth to the orthodontic provision of space after the infraoccluded tooth has been extracted.


Fig. 2a, b. Panoramic views of a young girl before and after space regaining and surgical extraction of the buried deciduous tooth.

Fig. 2c. Right and left bite wing radiographs of the same case, seen by chance 38 years post-treatment, to show complete normality of the spontaneously erupted right second molar. (These illustrations appear in Orthodontic Treatment of Impacted Teeth, by Adrian Becker 3rd Edition published by Wiley-Blackwell Publishers, Oxford, 2012 © Adrian Becker)

Patient #2 (Fig. 2a-c) was treated in the late 1970’s. The right maxillary first molar was strongly tipped mesially and the deciduous first molar strongly tipped distally, although there was still a 4mm space between them. The deciduous second molar was severely infraoccluded, not visible in the mouth and completely covered by the soft tissues. The panoramic radiograph view shows the severity of the infraocclusion and the wide angle of convergence formed by the coronal extension of the long axes of the adjacent teeth. The film was taken when the patient was 8.5 years of age and the permanent tooth buds of the canines and premolars can be seen to be ideally situated in the apical regions of their deciduous predecessors in 3 quadrants of the mouth. The only exception is the second premolar of the affected side. This tooth is located above the developing root of the first premolar, with a distinct distal tip and 900 rotation. Its bucco-lingual relation to the other teeth is not possible to assess from this film.

The permanent molar was tipped distally with a simple removable appliance before the infraoccluded tooth was extracted. No other treatment was provided and the second premolar erupted spontaneously and in its normal location some months later. The follow-up bite wing radiographs were taken about 35 years later.


Fig. 3a. Right and left intraoral views of the teeth in occlusion. The infraoccluded mandibular and right maxillary deciduous second molars were extracted. There is under-eruption and extreme tipping is seen on the right side of the maxilla.

Patient #3 (Fig. 3a-f) was seen at age 18 with congenitally missing mandibular second premolars and markedly infraoccluded deciduous second molars. She also exhibited extreme unilateral infraocclusion of the right maxillary second deciduous molar which was buried in the tissues at the level of the midpoint of the roots of the permanent molar. The two adjacent permanent teeth were strongly inclined towards one another with their long axes forming a 900 angle. The impacted second premolar was displaced mesially, high above the tipped premolar, with the characteristic distal tip and 900 rotation.

_17_Fig.3b__c _17_Fig.3d

Fig. 3b, c. Panoramic views taken before and shortly after extraction of the 3 infraoccluded teeth.

Fig. 3d. The colored plastic guide jigs clearly illustrate the 90 degree angle between the long axes of the first premolar and permanent molar, at the time of bracket bonding.


Fig. 3e. Following space opening, the rapid eruptive progress of the second premolar can be identified by the bulge in the mucosa (arrow) seen on the lateral and occlusal views.


Fig. 3f. The clinical and radiographic view to show the result of the completed orthodontic treatment. (These illustrations appear in Orthodontic Treatment of Impacted Teeth, by Adrian Becker 3rd Edition published by Wiley-Blackwell Publishers, Oxford, 2012 © Adrian Becker)

The deciduous second molar was removed surgically before the patient was referred to the orthodontist, in October 2009. Orthodontic space opening took a matter of 4 months employing fixed appliances and the second premolar erupted spontaneously a month later, 10 months after the deciduous tooth had been extracted.


Fig. 4a. The original practitioner’s radiographic follow-up of the developing infraocclusion is seen in these 3 panoramic progress views and the cephalogram. The lack of vertical alveolar and dental development is well illustrated, as is the point in time when molar tipping occurs.

Patient #4 (Fig. 4a-c) was a 10.9 year old boy with four severely infraoccluded deciduous second molars. The maxillary first permanent molars were only mildly mesially tipped, while the first premolars were strongly distally tipped. All the posterior teeth appeared under-erupted and there was a lateral open bite present bilaterally, which included the first permanent molars. The maxillary affected teeth were deeply buried in the alveolus and their dentine content of crown and root totally resorbed, leaving only an enamel shell. Both maxillary second premolars had been displaced mesially above the first premolars and both were tipped with their crowns pointing distally. Neither was significantly rotated._17_Fig._4b

Fig. 4b. Compares the condition immediately prior to the commencement of orthodontic space-opening/deciduous tooth extraction treatment in the maxilla with a confirmatory panoramic view close to the completion of the treatment.


Fig. 4c. Lateral cephalogram and panoramic view of the fully erupted dentition, illustrating a return to normal vertical development. (These illustrations appear in Orthodontic Treatment of Impacted Teeth, by Adrian Becker 3rd Edition published by Wiley-Blackwell Publishers, Oxford, 2012 © Adrian Becker)

Treatment to reopen space was performed with a bonded appliance, followed by extraction of the remains of the deciduous molars. Eruption was spontaneous, without any further orthodontic assistance, although these teeth were included into the appliance scheme after their eruption, in order to attend to a marked rotation of the left premolar.


Fig. 5a. The right maxillary first permanent molar is horizontally orientated, as seen in the cephalogram and the panoramic views. Note the associated anomalies: congenitally missing mandibular second premolar, 3 infraoccluded deciduous second molars, 2 absent third molars. (Courtesy of Dr. Elisha Reichenberg)


Fig. 5b Intra-oral views of the dentition, showing lessened vertical development of the alveolus of the right side.

Fig. 5c. A progress panoramic radiograph during the successful uprighting of the horizontal first molar, shows rapid spontaneous improvement in the position of the second premolar.


Fig. 5d. The orthodontic treatment is uncompleted but shows the premolar in place.

Patient #5 (Fig 5a-5d) presented in the early permanent dentition period, with 2 mandibular infraoccluded second deciduous molars. In the right side of the maxilla, the first permanent molar was lying horizontally, with its occlusal surface jammed against the distal of the infraoccluded second deciduous molar.

Patient #6 (Fig. 6a-d) A child in the mixed dentition period presented with erupted permanent incisors and first molars only, in each quadrant of the mouth. The same basic pattern existed on the left side of the maxilla, with a strongly mesially tipped first permanent molar and distally tipped deciduous first molar. These teeth were under-erupted, with a degree of over-eruption of the antagonist teeth in the mandible. The deciduous second molar was buried in the tissues and the impacted second premolar high above the developing root of the first premolar and in close relation to the floor of the sinus. The tooth had a strong distal tip and its root appeared on the panoramic view to cross over that of the unerupted canine, with its root development proceeding mesial to that of the canine. The tooth was not rotated.

_17_Fig.6a _17_Fig.6b

Fig. 6a. Occlusal and lateral views of the left maxillary area, showing the strong tip of the permanent molar and the first deciduous molar.

Fig. 6b. The panoramic view has been annotated to identify the teeth involved in this complex inter-relation between the involved teeth.


Fig. 6c. A simple removable appliance is constructed with a finger spring to re-open the second premolar space by tipping the permanent molar.

Fig. 6d. Space is held with a transpalatal bar soldered to the molar bands. The second premolar (arrow) can be seen in its early eruption stage.(These illustrations appear in Orthodontic Treatment of Impacted Teeth, by Adrian Becker 3rd Edition published by Wiley-Blackwell Publishers, Oxford, 2012 © Adrian Becker)

Following space opening with a simple removable appliance and extraction of the offending deciduous tooth, the premolar erupted rapidly without further treatment.


Hard and fast conclusions cannot legitimately be drawn from such a small sample of individuals sharing a common phenomenon. Nevertheless, guidelines and recommendations are certainly in order, if we are proposing to offer our patients treatment for what otherwise must be considered a seriously compromising condition. The condition has potentially harmful implications regarding the impaction of a healthy tooth, the periodontal condition of the tipped adjacent teeth, the height of the occlusal plane, occlusal interferences and prematurities and over-eruption of opposing teeth.

The features exhibited by the impacted teeth themselves on the panoramic view include a mesially located root apex, with a strong distally directed orientation of the crown of the tooth. The tooth is often markedly rotated. The tooth is also palatally displaced, which may be at least part of the reason for its being represented on the panoramic view in what seems to be an exaggerated mesial position. It should be remembered that imaging of this tooth in the panoramic view is made when the x-ray source is behind the ear of the opposite side and any object displaced palatal to the line of the arch will be projected to a more mesial location in relation to the other teeth in the arch. 15

Treatment should be aimed at the early re-location of the tipped adjacent teeth by simple tipping mechanics to their appropriate places, thereby creating more-than-adequate space in the arch. This will also provide the surgeon with good access for the removal of the remains of the infraoccluded deciduous molar although, if it can be extracted easily and with a minimum degree of surgical trauma at the beginning, this should be encouraged.

Spontaneous improvement of the impacted tooth in these circumstances is usually very rapid and, for the most part, it will erupt within a half year or so without the need for surgical exposure or orthodontic traction. Accordingly, attempts to expose, bond and apply traction to these teeth at the outset are to be avoided.


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