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Premature tooth loss in the primary dentition
A case report of odontohypophosphatasia
A.  Hinrichs, I. Graf, J. Neuschulz , B. Braumann
Department of Orthodontics, University Hospital of Cologne, Germany
INTRODUCTION
We present a case of odontohypophosphatasia
(odonto-HPP), a rare congenital disease
characterized by a genetic deficiency of tissuenonspecific alkaline phosphatase due to ALPLgene mutation. Clinical features of HPP are
premature loss of deciduous teeth without prior
root resorption, deformities, and discoloration of
teeth as well as the susceptibility to caries [1].
CASE REPORT
The 3 year old girl presented at our clinic in 2012 with no history of
diseases or abnormal development except for premature loss of her
deciduous front teeth in the upper and lower jaw. At the age of 2 1/2 the
first loose tooth was noticed and shed half a year later. Until the age of
4 she had lost central and lateral deciduous incisors of the upper and
lower jaw. While under orthodontic surveillance her lower deciduous
canines loosened and shed within a year (Fig.1-3).
06/2014
Fig.1 Lower left primary canine shows substantial periodontal loss
12/2014
Fig. 2 Lower left primary canine shed
05/2015
Fig. 3 Lower right primary canine shows substantial periodontal loss
ANAMNESIS
Our patient was the youngest child in a family of two children.
Pregnancy was without complications. Parents, siblings and
grandparents were healthy and did not show any signs of unusual tooth
loss. No bony deformation was detected. Due to the absence of
adequate trauma, periodontitis or excessive load that would have been
plausible to explain primary tooth loss a genetic background was
suspected.
DIAGNOSIS
Genetic consultation detected low alkaline
phosphatase levels of 67 U/l (minimum level at age 3
125 U/l). ALPL-gene analysis confirmed the
suspected diagnosis odonto-HPP. The same heterozygous pointmutation at c.331G>A i.e. p.A111T was
found in our patient and her mother. As the family did
not plan any more children the father was not tested.
CHARACTERISTICS AND PATHOPHYSIOLOGY
Currently seven forms of ALPL-gene mutation presenting as hypophosphatasia are differentiated by means of disease onset
(prenatal lethal, prenatal benign, early infantile, infantile juvenile, adult, odonto-HPP and pseudo-hypophosphatasia). Time of
onset correlates with the impact on bone metabolism, odonto-HPP being the mildest form [1].
Alkaline phosphatase catalyzes formation of matrix for bones and cementum, and its reduction results in hypoplasia and
defective mineralization of alveolar bone and cementum. Dental tissues are highly sensitive to phosphate metabolism
dysregulation. Therefore it is hypothesized that milder forms of ALPL-gene mutation have an impact on dentition only [2].
CONCLUSION
Odonto-HPP is an inherited disorder of mineral metabolism that should be interdisciplinarily recognized by dental
professionals as a possible cause of premature loss of deciduous teeth without prior root resorption. A therapy
has not been introduced yet. For genotype-phenotype relations have not been defined clearly it is especially
important to identify milder forms of mutations for genetic counseling of the parents.
References
1. Mornet E. Hypophosphatasia. Orphanet journal of rare diseases 2:40, 2007.
2. Foster B.L., Sheen C.R., Hatch N.E., Liu J., Cory E., Narisawa S., Kiffer-Moreira T., Sah R.L., Whyte M.P., Somerman M.J. and Millan J.L. Periodontal Defects
in the A116T Knock-in Murine Model of Odontohypophosphatasia. Journal of dental research 94(5):706-714, 2015.