Ectopic eruption of a bicuspid premolar tooth: a case report

Ectopic eruption
Ectopic eruption of a bicuspid premolar is sometimes found by pediatric dentists in routine oral check-ups. Know all about ectopically erupting teeth in this post.

Ectopic eruption of a bicuspid premolar tooth: a case report


What causes ectopic erupting teeth?


To start, ectopic eruption appears when a tooth erupts in a different position than it should. Usually, this situation in children and teenagers requires intervention of a pediatric dentist.

Ectopic eruption patterns can affect any tooth, in both, primary and permanent dentition. Usually, this phenomenon can occur in any segment of the arch: incisors, canines, premolars and molars.

First, it occurs most frequently in lower permanent incisors. Also frequently, in upper first permanent molars (molars erupt mesially), upper maxillary canines and third molars (wisdom teeth). The problem with third molars appears by late adolescence or in young adults.

Then, we also know that the ectopic tooth eruption can appear on one side of the mouth (of the maxilla) or on both sides. That is, this phenomenon can occur in both the upper and lower jaw.

Whenever we suspect ectopic eruption of any tooth we must proceed to perform a radiographic examination. Also, when we clinically can diagnose it. Panoramic radiographs are the indicated radiographs to evaluate the path of eruption of the misplaced tooth.


Which tooth is most common for ectopic eruption?

First, the most affected teeth are mandibular permanent incisors erupting after mandibular primary incisors. Then, next teeth more affected are maxillary first permanent molars and maxillary canines. Maxillary first permanent molars then cause resorption of the distal roots and distal surface of the primary molar crown.

Ectopic eruption of the maxillary molar teeth can be of reversible type (jump cases), or not reversible (hold cases). This last one will need orthodontic treatment.

In many cases, ectopic eruption of maxillary canines needs the removal of the maxillary primary canines. This will facilitate the eruption of the permanent canines. In other cases, the treatment plan needs to include orthodontic treatment. This will help to bring the canines into the corresponding dental arches.

Ectopic eruption of premolar teeth

Ectopic eruption of maxillary and mandibular premolars (upper and lower jaw) may also occur. It can affect maxillary first premolars, maxillary second premolars, mandibular first premolars and mandibular second premolars (upper and lower premolars).

What is ectopic eruption of a tooth?


As explained, ectopic eruption is the eruption of a tooth in a different place or position from where it should be. So, it does not come into the maxillary or mandibular arch where it is correct. At the end, in this final location it will obtain the proper bite or occlusion. Quite often, orthodontics is needed to bring the tooth to the proper position.

Regarding its origin, the literature does not report a difference between boys and girls. On the other hand, the origin of this problem is not entirely clear.


A combination of multiple factors causes the ectopic eruption of the permanent teeth.

Among them we can highlight:

a) lack of maxillary bone growth,

b) deficiency in dental arch length

In other words, the lack of space to fit all the teeth. The millimeters that we need to fit all teeth in, are less than the millimeters of bone length that we have.

Checking the child when he/she has mixed dentition, i.e. primary and permanent teeth at the same time, is important. Then, we can analyze through a study if all permanent teeth would be able to fit in the future. Finally, we can determine if we need extractions in the presence of a significant lack of space.

c) family inherited factors

For example, patterns of narrow faces have smaller bones than wide faces that have larger and wider bones. We know for sure, children inherit their parents’ facial characteristics.

d) large size of permanent teeth

The larger size of the permanent teeth compared to the primary teeth, or

e) the presence of fibrous tissue

This hinders the eruption of the tooth in question in its correct position, among others.

In many cases, teeth crowding causes ectopia. This increases the possibilities for caries and gum problems to appear.


When does the premolars erupt?

Normally, the premolars generally erupt between 10 and 13 years of age. Usually, teenager girls get these teeth a few months prior to boys.

Some adolescents get the premolars by age of 14 or 15 years. This variation does represent any problem. The only issue is that orthodontics in this phase has to start later than most adolescents.

Lower premolar teeth generally erupt earlier than upper premolars. Premolars follow the same tendency as any other tooth. This means that mandibular (lower) teeth tend to appear (erupt) before maxillary (upper) teeth. This is true for incisors, canines and molars; even for third molars (wisdom teeth).


What are the problems with ectopic eruption?

When a tooth does not follow its usual course, different oral problems may appear, both functional and esthetic.

Therefore, the poor location of the teeth in the mouth can cause:

a) Malocclusions

b) Problems in the patient’s hygiene

Since it is more difficult to clean properly crowded teeth than aligned (straight) teeth,

c) Compromised gum health

Non effective brushing keeps more bacteria in the mouth. A major quantity of bacteria forms more plaque. Then, this plaque will remain in the gums producing inflammation (gingivitis).

d) Resorption of a temporary tooth

Normally, primary front teeth or primary molars.

e) Problems of lack of space

For a correct tooth replacement, or

f) Resorption of an adjacent permanent tooth

Some cases may end up losing the tooth.


Likewise, as a consequence of ectopia, long-term TMJ (temporo-mandibular joint) disorders can occur.


How do you treat an ectopic eruption?

The treatment of ectopic eruption will depend on the tooth affected. For instance, when mandibular permanent incisors appear in the posterior area (distally) of the baby lower incisors. Many times, when this happens we need to extract the primary incisors.

Often, we find permanent upper canines included. These teeth remain in the maxillary bone because they cannot move coming down and erupt normally. These cases would need surgical exposure of the impacted (included) canine. Also, we will need the help of fixed orthodontics with braces to bring the canine into the arch.

A not common case is the case of ectopic eruption of maxillary second permanent molars. These cases cause the resorption of the first permanent molars. Sometimes, the resorption implies a large amount of the crown or the roots and there is the need for extracting the maxillary first molar.

Bicuspid premolar ectopia case report

Premolars are not the most common teeth to show ectopic eruption. But they can also present this problem. In this blog, we present the case of an ectopic bicuspid premolar in a child patient.


Finally, we should emphasize it is essential to have routine pediatric dentistry check-ups. In this way, an early diagnosis is possible in children and young people.



Boj JR, González, P, Hernández M, Cortés O. Odontopediatría. Dudas y aclaraciones. México DF. Odontología Books, 2019.

Boj JR, Catalá M, Mendoza A, Planells P, Cortés O. Odonto Pediatría: Bebés, niños y adolescentes. México DF. Odontología Books, 2019.


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