A Review of Ankylosis in Monozygotic Twins
Helpin ML, Duncan WK. Ankylosis in monozygotic twins. ASDC J Dent Child 1986;53:135-139.
Helpin Twin DHH
Helpin Twin HDH
This blog entry is a review of the article that appeared in the ASDC Journal in 1986. It contains some interesting facts that illustrate the pathology that often surrounds ankylosis. The twins have multiple missing permanent teeth and some variation in the location of ankylosis. Each twin has several differences in the location of missing permanent teeth and differences in ankylosed primary molars. A comparison of each panoramic x-ray points out the dissimilarities of the inheritance pattern. The monozygous nature of the twins as reported indicates that the oral structures do not fall into common ground. This blog also details the “Ankylosis and Partial Anodontia in Twins”, indicating that the oral structures are very similar if not identical. In a real sense we have observed differing patterns of odontogenesis in identical twins more than once. The mandibular dentition on each twin is near identical. The primary molar #T is present in rudimentary form indicating that the osteoclasts have engulfed much of the hard structure. In the maxillary arch there are several differences shown in the concordance pattern. The etiology of this patterning in oral development stands out as a dissonance in oral development in monozygotic offspring. Perhaps incomplete penetrance could explain the difference, but are we observing another more recent explanation…epigenetics. Review in this blog “Ankylosis of Primary Molars – Seeking an Answer.”
Concordance Pattern for Twins DHH/HDH
Key
CM = Congenitally Missing
EX = Exfoliated
Bold Face = Discordant
Tooth Number Twin DHH/HDH
1 Excluded/ Excluded
2 CM/ CM
3 Present/ Present
4 CM/ CM
5 CM/ Present
6 CM/ CM
7 CM/ Present
8 Present/ Present
9 Present/ Present
10 CM/ Present
11 CM/ CM
12 Present/ Present
13 CM/ CM
14 Present/ Present
15 CM/ CM
16 Excluded/ Excluded
17 Excluded/ Excluded
18 CM/ CM
19 Present/ Present
20 CM/ CM
21 Present/ Present
22 Present/ Present
23 Present/ Present
24 Present/ Present
25 Present/ Present
26 Present/ Present
27 Present/ Present
28 Present/ Present
29 CM/ CM
30 Present/ Present
31 CM/ CM
32 Excluded/ Excluded
Primary Teeth
A Ankylosed/ Ankylosed
B Ankylosed/ Missing (radiolucency)
C Present/ Present
D Present/ Present
E EX/ EX
F EX/ EX
G EX Present
H EX/ EX
I EX/ EX
J Ankylosed/ Ankylosed
K Ankylosed/ Ankylosed
L EX/ EX
M EX/ EX
N EX/ EX
O EX/ EX
P EX/ EX
Q EX/ EX
R EX/ EX
S EX/ EX
T EX/ Ankylosed