Diagnosis and Treatment plan of Maxillary Impacted canines using CBCT DICOM data.

Dr. Laura Nicolas
Dr. Alberto Teramoto

Department of Orthodontics. Universidad Latinoamericana Mexico City, Mexico.

Introduction

There is no doubt that an adequate treatment plan of resolving impacted teeth could be very difficult when you don’t have all necessary information. It is mandatory to know the exact location and more importantly what the immediate relationships of the impacted teeth are to surrounding teeth, roots and even the mandibular nerve.

After the third molars, maxillary canines have the highest frequency of impacted localization, with a prevalence ranging from 1% to 3% (1-4), and it is more frequent in female patients to male with a ratio of 2:1 (5). And when surgical treatment is necessary it is not so easy and time consuming to treat when you don’t have enough information. That is why the accurate localization of impacted maxillary canines is very important, when you have to decide to treat orthodontically and especially if surgical intervention is required.

Most of the time in our daily practice the first radiographic image that is required to support the clinical examination is the panoramic radiograph and sometimes in order to have a better localization of impacted teeth we can improve diagnosis by using a combination of other two or more bi-dimensional images: occlusal and periapical, which allow the localization of impacted canines, treatment planning, and evaluation of the treatment result.

Importance of CBCT

It is well known that the diagnostic accuracy of these bidimensional radiographic techniques presents many limitations thus increasing the risk of mistake. Adding a third dimension to the radiographic information may result in another and better diagnostic approach and an improved treatment outcome – using Cone Beam Computed Tomography (CBCT), clinicians can take advantages from 3D information provided by a low radiation dose and with relatively low costs. CBCT provides information which is not revealed during traditional radiographic analysis and is therefore indicated in case of impacted teeth or craniofacial structural anomalies.

However sometimes even we have all this 3D images sometimes they are not enough, and it is because there is much more we can use of CBCT data, another use of DICOM data is using a process called segmentation, a process in which separation of structures of interest from the background and from each other, is an essential analysis function for which numerous algorithms have been developed in the field of image processing, segmentation of an object is achieved either by identifying all pixels or voxels that belong to the object or by locating those that form its boundary. Segmenting teeth from CBCT images is not an easy procedure, there are difficult problems like:

1) DICOM data is acquired in upper-lower jaw in occlusion, so it is hard to separate a tooth from its opposing teeth along their occlusal surface because of the lack of changes in gray values.

2) It is also hard to separate a tooth from alveolar bone by similar densities.

3) Most of the times all teeth possess similar shape and it is difficult to identifying different tooth instances.

There exist in the market some open source software for segmentation procedure, however even you solve those problems it takes a long learning curve and time to perform a good quality segmentation.

Recently, with use of Artificial Intelligence technology, Orca Dental AI created a unique system in a 3D controllable STL format which not only offers a teeth segmentation service but also cephalometric and airway volume analyses and videos of teeth segmentation, making this process much more complete, easy to use and completely informative in disclosing all the impacted relationships.

With data received and for a better diagnostic approach and an improved treatment outcome it is also possible to convert the Data Imaging and Communications in Medicine (DICOM) files of the CBCT to a model using a 3D printer (Zenith D DENTIS Co. LTD), that is a very useful tool to help visualize and have 3D feeling of conditions of impacted teeth, because this process allows to experience an extra dimension for diagnostic, this can help us to decide which is the best treatment plan, and decide for example if it is better to perform an orthodontic treatment to align an ectopic canine or definitively a surgical procedure because the difficult to align ectopic maxillary canines.

CASES

Case 1

Because the position of impacted canine root is close to vestibular side, with extraction of first premolar it is easy to move canine to its ideal position. (Fig.1 a-h)

 

Case 2

It is clear to observe especially how right impacted canine because horizontal position surgically option is the best choice for it. (Fig.2 a-f).

Conclusions

There exist clinical situations for which CBCT is a useful tool like impacted canines, craniofacial anomalies, TMJ assessment and upper airway analysis.

CBCT images in combination with and 3d segmentation impression and videos provide a better diagnosis and is useful to decide to treat these cases orthodontically or surgically.

Special thanks

Orca Dental AI  for segmentation process, video and airway , cephalometric analysis.

Ideas Dentales Mexico for printing  3D models.

References

  1. Mason C, Papadakou P, Roberts GJ. The radiographic localization of impacted maxillary canines: a comparison of methods. Eur J Orthod 2001;23:25-34.
  2. Preda L, La Fianza A, Di Maggio EM, Dore R, Schifino MR, Campani R, et al. The use of spiral computed tomography in the localization of impacted maxillary canines. Dentomaxillofacial Radiol 1997;26:236-41.
  3. Stewart JA, Heo G, Glover KE, Williamson PC, Lam EW, Major PW. Factors that relate to treatment duration for patients with palatally impacted maxillary canines. Am J Orthod Dentofac Orthop 2001;119:216-25.
  4. Walker L, Enciso R, Mah J. Three-dimansional localization of maxillary canines with cone-beam computed tomography. Am J Orthod Dentofac Orthop 2005;128:418-23.
  5. Peck S, Peck L, Kataja M. The palatally displaced canine as a dental anomaly of genetic origin. Angle Orthod. 1994;64:249-56.
  6. Ericson S, Kurol J. CT diagnosis of ectopically erupting maxillary canines – a case repost. European Juornal fo Orthodontics 1988;10:115-21.
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