Case of the Month

An intriguing dental scan and how to interpret it

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Dental Agenesis
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EFFECTIVE DOSE:  Upper Jaw kV: 130, Tempo di Esp.: 1.8s, Spessore Assiale: 0.253mm

Lower JawkV: 130, Tempo di Esp.: 1.8s, Spessore Assiale: 0.271mm

CLINICAL INFORMATION: DENTALSCAN CT specialist exam – DOUBLE ARCH, requested by a dentist, for upper arch evaluation, with particular attention to deciduous teeth regions and bone evaluation with their measurement; Lower arch for checking of a suspected cyst (area 4.4), with evaluation of its extension up to the mental foramen and general standard control with possible further investigations.




  • Examination of the CT scan of the upper arch. 
  • The maxillary sinuses have proved free from any findings and normally pneumatized.
  • The nasopalatine duct shows normal radio-morphology.
  • There is a slight left convex deviation of the nasal septum at the level of the left lower nasal concha. 
  • Mucosal inclusion of the 1.8 is noted, the apices of which project into the ipsilateral maxillary sinus.
  • The 13 is dislocated in position 1.4, whereas in position 1.3, a deciduous element with signs of Rhizolysis can be observed.
  • Presence of a 5.5 deciduous with slight signs of Rhizolysis. Agenesis of 1.5
  • Presence of deciduous teeth, 6.4 – 6.5 with slight signs of Rhizolysis. Agenesis of 2.4 and 2.5.




  • Examination of the CT of the lower arch. 
  • The thickness of the bone cortex appears within physiological limits.
  • The medullary trabecular architecture appears free of any pathological changes.
  • The lower mandibular canal is found to have normal radiomorphology.
  • A radiolucent periapical cyst-like formation can be noted, with a maximum diameter of 8 mm, which includes the apex of both 4.3 and 4.2. (Odontogenic cyst)
  • A cyst-shaped periapical radiolucency is evident near the mesial root of 4.6, not in contact with the lower mandibular canal nor with the matching mental foramen.
  • Presence of 7.5 – 8.5 deciduous teeth, without signs of rhizolysis. 
  • Agenesis of 3.5 – 4.5.
  • There is evidence of an osteo-mucous inclusion of 3.8, which appears in a disto-mesial inclination in contact with the lower mandibular canal, which runs in a parietal direction inferior to the apices of the element.


Dental agenesis is the congenital absence of one or more teeth due to problems with the dental follicle, meaning the embryo that will make up the tooth. In case of young patients, these could be deciduous teeth (milk teeth). In this case, the pedodontist must monitor carefully, evaluating when and how the absence of deciduous teeth requires intervention. However, if the teeth are already permanent, as is the case in adult patients, surgery will be mandatory


This pathology is quite widespread, and can effectively represent an annoying aesthetic problem capable of causing discomfort in social relationships, because in most cases (a good 80%), the missing teeth are lateral incisors, so the gap caused by absent teeth is very noticeable. For reasons still unknown, agenesis affects women more frequently than men, especially in the case of permanent dentition; it is usually bilateral, i.e. it involves both sides of the mouth, with the lower arch being the most affected.

Apart from aesthetic damage, phonation problems, malocclusion, chewing or dental crowding can arise, because the teeth close to the missing ones tend to occupy the empty space by twisting or moving. Possible secondary consequences range from an increased risk of dental cavity, as partially overlapping teeth hinder proper cleaning, to temporomandibular disorders, if no action is taken in time. It goes without saying that in old age, it is more likely to be on the receiving end of implant surgery, or aesthetic surgery whenever needed.

 ARCATA SUPERIORE (1.5 ; 2.4 – 2.5) (Cross Sections T:1mm; S:2mm)



 ARCATA INFERIORE (4.5 ; 3.5) (Cross Sections T:1mm; S:2mm)


There are different types of dental agenesis, which can be classified depending on number and type of teeth involved. These are the three main categories:

  • partial agenesis (or hypodontia): absence of one or more teeth, less than 6 in number
  • multiple agenesis (or oligodontia): absence of over 6 teeth
  • total agenesis (or ablastodontia): complete absence of permanent dentition.

The last type, also called ablastodontia, is a consequence of an agenesis of deciduous teeth (so-called agenodontia): it is a very rare pathology, almost always related to other diseases of genetic origin.


The causes and risk factors of dental agenesis are many and rather varied. However, the most common reasons leading to the onset of this disorder have been identified and are listed below:

  • hereditary factors and family history of the disease.
  • genetic factors such as trisomy 21 (down syndrome), or other genomic alterations in turn correlated with additional types of dental or cranio-maxillofacial anomalies.
  • heavy medical treatments such as chemotherapy.
  • somatic diseases such as scarlet fever or syphilis.
  • malnutrition, to be countered through prevention or changes to the nutritional regime, correcting it to avoid further damage.
  • rickets, often due to malnutrition and, more rarely, derived from diseases altering calcium metabolism, such as dysfunction of the parathyroid glands.
  • other hormonal imbalances.
  • failure in the formation of the tooth bud, or delay in dental eruption (appearance of permanent tooth) during childhood development.
  • destruction of the dental germ following trauma.
  • traumatic events or of an infectious nature to the teeth.


In all cases, it is always advisable to proceed with a careful and accurate diagnosis through the execution of a suitable radiological investigation. In first instance, it is crucial to run a OPG scan (Orthopanoramic), in order to check bone structure and thickness of the jawbone, to fully evaluate the conditions of the oral cavity. Thus, it is necessary to evaluate whether the absence of a tooth can be traced back to dental agenesis or not: in fact, sometimes it could be a bone inclusiona pathology of the oral cavity due to which the teeth tend to remain within the jawbone, due to not having the necessary space to come out. If agenesis is confirmed, the radiography will also verify the presence of dental crowding or crooked teeth, in order to have the complete picture of the situation and allow the dental practitioner to establish the best type of treatment.

Fortunately, the techniques for dealing with agenesis are many and of different types, in order to meet any patient’s need depending on their age and conformation and on the severity of the pathology as well.
Particularly, there are three possible types of intervention for curing an agenesis:

  • insertion of a traditional prosthesis in place of the missing tooth.
  • closure of the gap left empty through orthodontic intervention.
  • implant surgery.

For further information regarding the pathology described in this article or others, as well as for the performance of the relative radiological services, please contact any of the DentQ centers in your country.


Elaborated by Dr. Lucisano Francesco, Lead Radiographer – DentQ Italy

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