Measuring Lingual Position of Lower Wisdom Teeth

An interesting study titled “Measurement of the Lingual Position of the Lower Third Molar Roots Using Cone-Beam Computed Tomography,” appears in the January 2015 issue of the Journal of Oral and Maxilofacial Surgery (vol. 73, issue 1) and written by Yusuf Emes and et al. The authors set out to use Cone-beam computed tomography (CBCT) to evaluate the proximity of lower wisdom teeth roots to the lingual cortex, which can be used to determine the potential risk of root displacement during lower wisdom teeth removal.

The study used CBCT images of 32 impacted lower wisdom teeth of 31 patients (5 men and 26 women). The images were collected for reasons not related to surgery including impacted teeth, dental implants, and cysts of the jaws. An evaluation was performed independently by 2 trained oral and maxillofacial surgeons who were experienced in the radiographic evaluation of maxillofacial anatomy. The teeth were grouped according to their positions on the orthopantomogram as vertical, mesioangular, horizontal, and distoangular. Two measurements were performed for each tooth. If 1 tooth had more than 1 root, the root in the most lingual position was considered: 1) the distance from the root apex of the tooth, which is in the most lingual position, to the lingual cortical plate and 2) the distance from the most lingual point on the apical half of the root to the lingual cortical plate.

There was an average distance of 1.03 mm between the apices of the lower third molars and the lingual soft tissues. There was an average distance of 0.65 mm between the most lingually positioned point on the apical half of the root and the lingual soft tissues.

The authors say that the actual risk of a root displacing during wisdom teeth removal is not known (does not happen often). 

The authors state

“The present findings show that 25% of the apices of impacted teeth were in contact with the mouth floor. If a root in the lingual position is fractured during lower third molar surgery, there may not be enough bone volume between the fractured segment and the floor of the mouth. Further, there may be a fenestration in the lingual cortical plate, which renders the root in contact with the lingual soft tissues. Therefore, an improperly applied force vector by the surgeon can displace the root fragment into the soft tissues.”

The authors do not have any advice on what the distance between the roots of impacted wisdom molars to the lingual soft tissues should be in order to minimize the possible risk of displacement of fractured root segments lingually. The study was conducted to determine if the distances can be measured with CBCT images.

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