Osteogenesis imperfecta (OI) is an inherited disorder of the connective tissue, whose incidence ranges from 1 in 5,000 to 1 in 20,000 live births, with no racial or ethnic predilection (1, 2). The disorder arises from mutations in the genes encoding type I collagen. Many organs are affected due to the widespread presence of this protein in the human body. OI may also be caused by mutations in other genes, including CRTAP, LEPRE 1 and PPIB (3). Patients experience bone fractures, blue discoloration of the sclera, hearing disorders, joint laxity and dentine aberrations. The common dental symptoms include: congenital hypoplasia of the dentine (dentinogenesis imperfecta – DI), malocclusion, ectopic position of the teeth, or impacted teeth. Type I DI is associated with OI, whereas types II and III occur independently. Although the disease affects primary and permanent dentition, changes are more frequent and more severe in primary teeth.

The aim of this paper is to describe the anomalies in the dentition of children with osteogenesis imperfecta.

Based on the available literature, the article reviews the state of knowledge concerning the possible dental abnormalities in patients with osteogenesis imperfecta.

Osteogenesis imperfecta is a hereditary disorder of the connective tissue. It is caused by mutations in the genes (COL1A1 and COL1A2) encoding two polypeptides (proalfa-1 and proalfa-2) of type I procollagen, which results in quantitative or qualitative changes in the synthesis of collagen type I. So far, more than 250 different mutations of COL1A1 and COL1A2 genes have been recognized, possibly accounting for the observed differences in the phenotype of OI (1). Type I fibrillar collagen is the most common form of collagen in the body, and it constitutes 95% of bone collagen. Therefore, the most frequently observed features of OI are changes in the bone structure. However, in all tissues that are rich in type I collagen, such as ligaments, tendons, skin, sclera, teeth and the inner ear, some anomalies may occur (1). Patients may present with increased bone fragility, blue sclera, growth deficiency, hearing loss, bone pain, joint laxity and dentinogenesis imperfecta. Repeated fractures of the femur and spine occur more frequently in young children (4). A triangular shape of the face with a broad forehead is also typical of the condition (5). Platelet function disorders and small vessel fragility associated with OI result in prolonged bleeding. Patients with osteogenesis imperfecta can also demonstrate heat intolerance, increased body temperature, an increased respiratory and resting heart rate (1).

In 1979, osteogenesis imperfecta was classified into four main types by Van Dijk and Sillence (3). The initial classification, based on clinical and radiological symptoms as well as inheritance pattern is still used. Due to the occurrence of osteogenesis imperfecta resulting from mutations in genes other than COL1A1/2, Rauch and Glorieux published in 2014 an extended classification, distinguishing seven OI types (6). In 2007, Cabral et al. additionally described Type VIII, related to a mutation in LEPRE1 gene (7). The most recent classification of osteogenesis imperfecta, introduced by INCDS in 2010, distinguishes five OI types, acknowledging the IV main types and adding a fifth one (tab. 1) (3). It also introduces further disease subtypes depending on the type of the gene mutation involved (3). Type I OI is the most common one (60-70% of all patients with OI), type III is diagnosed in 20% of patients with OI, and type IV – in only in 10% of the patients (8). Type I – the mildest OI form, is caused by reduced production of type I collagen. Other types of OI, the lethal type II accompanied by fractures in utero, as well as type III and type IV are the result of both qualitative and quantitative disturbances in the synthesis of type I collagen (4). Types I and III are further divided into subgroups with or without dentinogenesis imperfecta (9). According to Patterson et al., patients with type I OI accompanied by DI are at a greater risk of fractures at birth than those without DI (10). They are also more prone to bone fractures and severe skeletal deformations (3). Types I and IV are characterized by similar presentation, including a lack of prolonged bleeding, bone pains or cardiac problems (4).