A Review of Ankylosis in Monozygotic Twins

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 DHH

 Helpin Twin HDH

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