Comparison of the Visibility of Fetal Tooth Buds on 1.5 and 3 Tesla MRI

Abstract

Dental anomalies coincide with genetic disorders, and prenatal identification may contribute to a more accurate diagnosis. The aim of this study was to assess whether fetal Magnet Resonance Imaging (MRI) is suitable to visualize and investigate intrauterine dental development in the upper jaw, and to compare the quality of visibility of tooth buds between 1.5 Tesla (T) and 3T images. MR images of fetuses Gestational Week (GW) 26.71 ± 4.97 from 286 pregnant women with diagnoses unrelated to dental anomalies were assessed by three raters. We compared the visibility between groups and field strengths in five gestational age groups, using chi square and Fisher's exact tests. All ten primary tooth buds were identifiable in 5.4% at GW 18-21, in 75.5% at GW 26-29, and in 90.6% at GW 34+. Before GW 30, more tooth buds were identifiable on 3T images than on 1.5T images. Statistical significance was only reached for identification of incisors (p = 0.047). Therefore, 1.5T and 3T images are viable to visualize tooth buds, particularly after GW 25, and their analysis may serve as diagnostic criterion. MRI tooth bud data might have an impact on various fields of research, such as the maldevelopment of teeth and their causes. Analyzing tooth buds as an additional diagnostic criterion is not time consuming, and could lead to an improvement of syndrome diagnosis.

Keywords: dental imaging; fetal MRI; head and neck imaging; magnetic resonance imaging; prenatal diagnosis; tooth buds.

Figure 1

Diagram representing exclusion criteria applied in the current study.

Figure 2

T2-weighted ssFSE axial images of two GW 36 fetus, performed at 1.5T (a) and 3T (b) displaying the tooth buds: i1 (first primary incisivus), i2 (second primary incisivus), c (primary caninus), m1 (first primary molar), m2 (second primary molar), M1 (first permanent molar). The asterisk shows the calcified edge within the tooth bud.

Figure 3

T2-weighted ssFSE images performed with a 3T MRI (a) and with an 1.5T MRI (b) of the dental lamina from GW 20–36, showing a gradual increase in tooth bud visibility, with all tooth buds identifiable at GW 36.

Figure 4

Comparison of 1.5T and 3T images with regard to the GW groups and visibility of tooth buds. (a) Percentage of cases per age group where all tooth buds were visible in both the 1.5T and 3T Images. (b) Average amount of tooth buds visible in different age groups, again in both the 1.5T and 3T Images.

Figure 5

The T2-weighted ssFSE image 1.5T image shows the upper jaw of a patient in GW 27 with a bilateral cleft lip and palate. The frontal tooth buds are not visible. Tooth buds i2 (second incisor), c (canine), m1 (first molar), and m2 (second molar) are visible.

Figure 6

The T2-weighted images above show the dental arch in the GW 24 in vivo (a) and a post mortem image (b) of the same patient. In both images, all primary tooth buds are visible: i2 (first incisivus), i2 (second incisicus), c (canine), m1 (first molar), and m2 (second molar).