Hereditary Tooth Anomalies: Amelogenesis Imperfecta, Dentinogenesis Imperfecta, Dentine Dysplasia

Abstract

Amelogenesis imperfecta (AI), dentinogenesis imperfecta (DI), and dentin dysplasia (DD) are hereditary illnesses that affect the growth and architecture of teeth’s hard tissues (enamel and dentine). These diseases present clinical symptoms such as tooth discoloration, enamel/dentine abnormalities, and enhanced tooth sensitivity. AI is defined by teeth enamel flaws, while DI is characterized by anomalies in dentin development, leading to opalescent or yellow-brown teeth, greater translucency, and a higher risk of fractures. DD is less prevalent than AI or DI. The genetic basis of DD, DI, and AI is derived from gene alterations. Mutations in the DSPP, DMP1, COL1A1, and COL1A2 genes are linked to DI, while the DSPP, DMP1, and COL1A2 genes are the cause of DD. Family genetic history was used to detect genetic mutation and confirm diagnosis, with treatment options including endodontic therapy, restorative dentistry, and preventative treatments as in fluoride therapy and oral hygiene guidelines. Early diagnosis and effective treatment are essential for enhancing oral health and quality of life.

1. Introduction

Tooth development anomalies, particularly those related to the enamel and dentin complex, can negatively impact oral health. Genetic and modern lifestyle factors influence enamel and dentin development, such as acidic foods, stress, and inadequate dental care. Hereditary and environmental influences interact to dental abnormalities, leading to Amelogenesis Imperfecta (AI), Dentinogenesis Imperfecta (DI) and odontodysplasia, these conditions could result in tooth sensitivity, structural flaws in the teeth, or complete loss, which would impair mastication and the facial esthetics. Congenital anomalies in enamel and dentin in permanent and deciduous teeth can cause symptoms alone or in systemic syndromes, posing challenges to basic science research and clinical care [1]. Dental agenesis is the most prevalent developmental anomaly in humans and is often linked to multiple other oral abnormalities as in growth hormone-deficient children have tooth anomalies that affect tooth size and enamel growth [2]. Similarly, systemic illnesses such as ectodermal dysplasia are linked to hypodontia or oligodontia and may have etiological involvement from both genetic and environmental sources . The abnormalities known as dental anomalies are associated with genetic mutations in dentin and enamel structure, such as the altered dentin sialophosphoprotein (DSPP) gene [3]. In this context, there is prominent cervical constriction, bulbous crowns, pulpal obliteration, and a crescent-shaped remnant of amelogenesis imperfecta in major teeth, which also include pulp stones, dentin dysplasia type II. Dental agenesis is divided into acquired and developmental anomalies, causing various disorders [4]. Developmental anomalies, characterized by variations in tooth number, size, morphology, structure, and location, are clinically significant in malocclusion, esthetics, and predisposing individuals to tooth caries and periodontal disorders in clinical manifestation [5]. Therefore, understanding dental abnormalities and differential diagnoses is critical for prompt management and appropriate intervention through clinical manifestation, female history, and hereditary pathways [6]. Radiography is used to distinguish missing teeth from impacted or embedded teeth, particularly those in the enamel and dentin complex and developmental anomalies include amelogenesis imperfecta, dentinogenesis imperfecta, dentin dysplasia [7]. More attention will be paid to developmental abnormalities in health society culture; reducing these anomalies requires regular dental care, a healthy diet, and excellent oral health habits. Dentists, pediatric dentists, orthodontists, and oral surgeons must be aware of abnormalities and use best practices for diagnosis and treatment, such as crowns, veneers, and tooth bonding, to maintain good oral hygiene. This chapter discusses current data focusing solely on enamel and dentin abnormalities, which phenotypical variable and difficult diagnosis in some cases and does not cover other dental anomalies, which allow specialists to diagnose and treat patients with amelogenesis imperfecta or dentinogenesis imperfecta in more recognizable ways.

2. Enamel and dentine abnormalities

The inadequate production of dentin and enamel, respectively, results in amelogenesis imperfecta and dentinogenesis imperfecta. Enamel and dentine abnormalities can cause disruptions to the structure of teeth due to hypoplasia, hypomineralization and hypomaturation in organic or inorganic components of the enamel and dentine. Hypoplasia and hypomineralization are common signs of developing enamel defects, whereas dentine abnormalities include dentine dysplasia and dentinogenesis imperfecta [8]. More often than not, the enamel defects present as anomalies of enamel and dentine with wearing, dentine-exposing and enamel cracks are regarded as clinical indicators and symptoms [9]. Sequences of enamel with dentine abnormalities increase endodontic issues due to dentine hypomineralization and pulp irregularities [10]. Due to data limitations, clinical evaluation of enamel defects is difficult. It entails reviewing the physical exams, imaging methods, and dental histories of patients. Gene mutations linked to DI and AI dysplasia, which impact tooth growth and shape, can be found through genetic testing. Tooth sample histological examination can shed light on the underlying reasons for anomalies in the enamel. Working together with pediatric dentists and geneticists can improve the precision and efficacy of clinical evaluations for identifying and treating anomalies in the enamel.

2.1 Amelogenesis imperfecta (AI)

Deviations in AI development include hypoplastic enamel, hypoplasia, hypomaturation, and hypocalcification, which increases susceptibility to caries, erosion, hypersensitivity, discoloration, and esthetic issues. AI may be linked to clinical dental conditions of other craniofacial abnormalities [11]. A delayed tooth eruption, an anterior open bite, pulp stones, taurodontism abnormalities are other dental conditions that may be linked to AI [12]. AI categories include genetic patterns and clinical and radiological criteria; Witkop [13] classified AI into four major types based on phenotype: hypoplastic, hypomaturation, hypocalcified and hypomaturation-hypoplastic [14]. Aldred and colleagues [15] also subclassified AI into four types (Figure 1) based on the future hereditary dental conditions that will be influenced by phenotype, including radiological, clinical, and other findings, as well as inheritance mode, molecular basis, and biochemical consequences [16]. Patients and specialists are familiar with the Witkop classification of amelogenesis imperfecta (AI) and will follow it in this context. Amelogenesis imperfecta (AI) is mostly caused by genetic abnormalities, whereby changes in genes with autosomal dominant or recessive inheritance patterns result in hypoplastic AI types and hypomature variations [17]. Acid phosphatase 4(ACP4) is the newly discovered gene known to be involved in hypocalcified autosomal dominant AI [18]. So far, there is different treatment plans among dentists on treat AI illness.

Figure 1.

Clinical features of subtypes of Amelogenesis Imperfecta (AI).

2.1.1 Hypoplasia AI type I

Clinical signs of hypoplastic type 1 include decreased enamel thickness, malocclusions, many restorations, opaque white patches, and surface attrition. AI linked to enamel renal syndrome (ERS), a rare autosomal recessive condition characterized by thin enamel, late dental eruptions, intrapulpal calcifications, and bilateral nephrocalcinosis [15]. When compared to dentinogenesis hypoplastic, AI causes a reduction, radiopacity and enamel thickness. Large-scale genetics linked to syndromic types of AI should be included during the diagnostic process and taken into consideration as potential causes. Different genes and the inheritance can be either autosomal dominant or recessive, or X-linked. [14]. Heterozygous mutations in ENAM and LAMB3 genes can cause hypoplastic AI with markedly different phenotypes in Chinese patients [19]. It’s important to note that although amelogenesis imperfecta (AI) subtypes can be linked to both autosomal recessive and autosomal dominant inheritance patterns, the autosomal dominant inheritance pattern (Table 1). In summary, thin or inadequate enamel, pits, or grooves on the surface of the teeth are signs of hypoplasia, which is caused by insufficient production of the enamel matrix during the growth of teeth.

Subtype	Clinical Features	Genetic Basis
1A	General, pitted rough enamels	Autosomal dominant
1B	Local, pitted rough enamel, decays.	Autosomal dominant
IC	Local, pitted rough enamel	Autosomal recessive
ID	Diffuse, Smooth thin enamel	Autosomal dominant
IE	Diffuse, Smooth thin enamel	X-linked dominant
IF	Diffuse, Rough grooved enamel	autosomal dominant
IG	Enamel agenesis, complete / partial	autosomal recessive

Table 1.

Clinical features of subtypes of hypoplastic type 1.

2.1.2 Hypomaturation AI type II

Hypomaturation AI type II is a condition characterized by pigmented, hypomature enamel with normal thickness, mottled appearances, and radiopacity. There is a lack of contrast between enamel and dentin, which is easily detached in families and potentially autosomal recessive subtyping [20]. Short stature syndrome, linked to gene mutations, associated with hypoplastic amelogenesis imperfecta is characterized by taurodontism, enamel hypoplasia, calcified dental pulp [21]. This condition is often linked to an open bite and enamel with a rough, creamy white to yellow-brown color that can be sensitive and painful (Table 2). Molar incisor hypomineralization (MIH) is a growing issue in children, causing hypomineralization on the first permanent molars and defined opacities. This can lead to caries due to teeth being fragile and prone to breaking. The exact cause is unknown, but factors such as environmental changes, nursing, respiratory conditions, low oxygen levels, and high-fever illnesses are being researched [22]. MIH affects 3.6–39.3% of children and requires sensitive treatment. Treatment techniques include composite opaques, composite crown buildup, partial enamel removal, and micro abrasion. Dental caries is a risk factor for MIH, and sealants are effective for enamel restorations [23]. For extensive lesions or unresponsive sensitivity, full coronal coverage with stainless steel crowns is necessary. Radiographs showing bifurcation calcification should be used to assess the tooth’s long-term survival [24]. Amelogenesis’s maturity stage is when changes commonly occur that lead to hypocalcification, a disorder that causes incomplete mineralization of enamel, especially in teeth like molars and incisors. Enamel softening, staining, opacity, and greater susceptibility to decay are the characteristics of this disorder [25]. Teeth like these, either general or specialized, may be affected. Occasionally, genetic predispositions or certain medical conditions that affect the body’s ability to properly mineralize enamel can lead to hypocalcification. A diet high in sugar and acid, along with poor oral hygiene practices, might make this issue worse.

Subtype	Clinical Features	Genetic Basis
IIA	Diffuse, pigmented, sensitive	Autosomal recessive
IIB	Diffuse, pigmented, rough teeth	Autosomal, recessive, X-linked
IIC	Snow-capped creamy, teeth	X- linked
IID	Snow-capped so white, teeth	Autosomal dominant

Table 2.

Clinical features of subtypes hypomaturation type II.

2.1.3 Hypocalcified AI type III

Hypocalcified AI type III was rough, opaque, and thinner, often yellow or brown. The patient’s clinical features included an open bite, periodontal disease, and sensitivity (Table 3). Compared to the other subtypes, there are more teeth impacted in most of cases [26]. The radiograph revealed a reduction in enamel thickness and poorer radiopacity of the enamel in comparison to dentin [27]. AI type III is characterized by porous and soft enamel, leading to hypocalcification, discoloration, and increased wear sensitivity. This condition affects both primary and permanent teeth and can vary in severity, with some experiencing mild defects and others experiencing severe teeth prone to frequent cavities and breakage. Autosomal recessive inheritance is common in some cases.

Subtype	Clinical Features	Genetic Basis
III A	General, pigmented	Autosomal dominant
III B	Local, pigmented	Autosomal, recessive

Table 3.

Clinical features of subtypes hypomaturation type III.

2.1.4 Hypomaturation/hypocalcified with taurodontism AI type IV

In one instance of this subtype, hypomaturation and hypocalcification traits are characterized by rough, white, or opaque enamel with opaque white dots. Hypocalcification causes malocclusions, periodontal infections, and decreased enamel thickness (Table 4). Radiography shows radiopacity, enamel loss, and taurodontism in teeth [26]. The families in this subgroup displayed an autosomal recessive inheritance pattern. Rarely, hypomaturation and hypocalcification are present with diastemas, restorations, and susceptibility to temperature fluctuations Besides opaque, thin, and coarse enamel [27, 28]. Taurodontism is a dental anomaly caused by the apical displacement of the pulpal floor, an expanded pulp chamber, and a lack of constriction at the cemento-enamel junction. It is caused by Hertwig’s epithelial root sheath’s failure to invade [29]. Types of taurodontism include hypertaurodontism, mesotaurodontism, and hypotaurodontism, which vary in tooth size and shape relative to the dental arch, each with unique implications for dental health and function [30]. The most severe type causes root furcation at the root apices due to the larger pulp chamber and crown. In mild form, only the pulp chamber is expanded. Radiographic examination is used to identify taurodontism, with a prevalence rate ranging from 2.5 to 11.5%. Clinical problems may require different filling procedures and increase pulpal exposure risk due to the larger pulp chamber [31]. Mineral loss and deterioration in enamel are indicated by cavitations and pits, ranging from brown to yellow to white-yellow. These irregularities suggest poor oral hygiene and potential dental issues. Untreated pits and cavitations may worsen tooth sensitivity and decay. To prevent worsening oral health concerns, individuals with these surface irregularities should consult a dentist even in same cases mixed with different size of detention in terms of taurodontism.

Subtype	Clinical Features	Genetic Basis
IVA	More hypomaturation with taurodontism	Autosomal dominant
	White spots, vertical lines,
IVB	More hypocalcified, with taurodontism brown to yellow, or white to yellow	Autosomal, recessive

Table 4.

Clinical features of subtypes hypomaturation/hypocalcified type IV.

2.2 Dentinogenesis imperfecta

Five categories of inherited dentin defects are recognized: two types of dentin dysplasia (DD) and three types of dentinogenesis imperfecta (DGI). Osteogenesis imperfecta (OGI) [32], a genetic condition causing bone diseases, occurs through mutations in two genes that encode type I collagen fiber formation, always linked with two type of DD and DGI [33]. Dentin sialophosphoprotein (DSPP) mutations cause other various types of dentinogenetic defects, each with a unique inherited pattern in dentition [34]. The genetic revolution has not affected the rare DD-I subtype, which has short, blunt roots and obliterated pulp chambers and whose etiology is currently unknown [35]. Generally, dentinogenesis imperfecta and dentine dysplasia affecting dentin formation, resulting in altered dentin morphology across all teeth (Figure 2). There are three main kinds of dentinogenesis imperfecta, which affect dentin formation and cause changes in morphology in all teeth (Table 5). Type I (DGI-I): Osteogenesis imperfecta is associated with symptoms in the teeth structural defects DGI-I [36]. Type II (DGI-II): traditional hereditary opalescent dentine that has clinical, radiological, and histological characteristics similar to DGI Type I but lacks impaired osteogenesis. Type III (DGI-III): Brandywine isolate is opalescent dentine that has been specifically isolated from the Brandywine region of Maryland. mutations in a number of genes, including DSPP, COL1A1, and COL1A2 [37]. In summary, Dentinogenesis imperfecta is hereditary and genetic in nature and is characterized by abnormalities in dentin formation, leading to fragile, discolored, and wear-prone teeth. It affects both permanent and deciduous dentition, with deciduous teeth being more severely affected. This shed light on the clinical features and genetic basis of each subtype of dentinogenesis imperfecta.

Figure 2.

Clinical features of subtypes of Dentinogenesis Imperfecta (DI).

Subtype	Clinical Features	Genetic Basis
DGI-I with osteogenesis imperfecta	Blue-gray to yellow-brown teeth, enamel fracturing, excessive wear primary teeth more affected than permanent. (occurs as clinical feature of osteogenesis imperfecta), bulbous crown	Mutations of collagen type 1(genes (COLIAI &II)
DGI-II without osteogenesis imperfecta	Pulp obliteration which differentiates between type I & II, Similar to DI-I More severe in permanent more than primary dentitions, irregular crowns.	Commonly, linked to 4921 Locus
DGI-III	Similar clinically to type I & II expressed with enamel wearing and attrition to gingival level. There is a large pulp, thin dentin, bulbus grown.	Probably, linked to 4921 Locus

Table 5.

Clinical features of three types of dentinogenesis imperfecta.

2.2.1 Dentinogenesis imperfecta type I (DGI-I)

Dentinogenesis imperfecta type I (DI-I), is inherited in an autosomal dominant manner as clinical sign of systemic osteogenesis imperfecta. It leads to complex clinical symptoms like pulp obliteration, opalescent brown, tooth wear, and attrition, and is also present in Goldblatt syndromes and Ehlers-Danlos syndromes [38]. It affects both permanent and deciduous dentition and is brought on by mutations in the procollagen type I COL1A1 or COL1A2 gene as in similarity to osteogenesis imperfecta [39]. DGI-I patients have genetic defects that disrupt collagen fibril development in teeth’s dentin, affecting their strength and appearance, resulting in altered dentinal tubule shape, fewer tubules, and smaller widths [40]. The genetic bone-brittle condition known as osteogenesis imperfecta is accompanied by dentinogenesis imperfecta. It is brought on by gene mutations that code for type I collagen, the substance that gives bones their strength [41]. There are different types, but the most common and moderate type is OGI-I. The probability of acquiring OGI is higher in families where the disorder has a history. Individuals with DI-I may experience dental pain and increased sensitivity to hot or cold temperatures. The pre- and post-treatment plans for oral hygiene and rehabilitation are part of the management of dentinogenesis imperfecta (DGI-I) as crowns and restorations are included.

2.2.2 Dentinogenesis imperfecta type II (DGI-II)

Dentinogenesis imperfecta (DGI-II) is an autosomal dominant disorder with clinical and radiological characteristics similar to type I. It has short, constricted roots, opalescent teeth, and soft, blue-brown, transparent teeth [42]. Primary and secondary dentitions have structural irregularities, causing pulp obliteration, which acts as second base to differentiate between type I and II [43]. The DSPP gene, found on chromosome 4q22.1, acts as gene basis mutation of the condition [44]. Bulbous crowns, cervical constriction, and osteogenesis are common, and hearing loss may occur. The degree of symptoms and the demands of the patient determine the treatment options for hereditary dental problems. Frequent check-ups with a dental staff are essential for required modifications.

2.2.3 Dentinogenesis imperfecta type III (DGI-III)

Dentinogenesis imperfecta type III, also known as the “Brandywine” variety, is an uncommon disorder affecting the Brandywine community in Maryland, USA. The DSPP gene produces dental sialoprotein, dental glycoprotein, and dental phosphoprotein, all derived from the dentin matrix [45]. The DSPP gene can result in reduced DSPP protein, incorrect calcification, insufficient dentin mineralization, or accumulation in odontoblasts, impacting protein processing and transport during dentin matrix formation [46]. When dentine production stops after the mantle layer forms, multiple pulpal exposures occur in the primary dentition, giving teeth the radiographic appearance of shell teeth.

2.3 Dentine dysplasia

Dentine dysplasia is a condition where teeth lack roots, with symptoms like pulpal obliteration, periapical radiolucency, and short or absent roots (Figure 3). It can be classified into two types: type I, known as radicular dentine dysplasia, where roots are completely absent, and type II, also known as coronal dentine dysplasia, with short or malformed roots (Table 6). Dentine dysplasia is a rare hereditary condition affecting 1% of permanent and 1% of deciduous teeth [47]. It causes dental anomalies like radiolucent lesions, undeveloped roots, enlarged pulp chambers, and premature tooth loss. The SIBLING family, consisting of dentin and sialophosphoprotein (DSPP), is involved in producing defects like DSP, DGP, and DPP [48]. Its clinical feature similar to dentinogenesis imperfecta, to control symptoms and improve oral health, specific dental treatments may be needed. The condition is distinguished by aberrant dentin production, resulting in short roots, radiolucency, and early exfoliation.

Figure 3.

Clinical features of subtypes of dentine dysplasia (DD).

Subtype	Clinical Features	Genetic Basis
DD-I	Misaligned teeth, permanent teeth have normal to slight blue gray color,	Unknown,
DD-II	dentin frequent absent in primary teeth. Pulp obliteration in both primary or permanent teeth	Unknown

Table 6.

Clinical features of dentine dysplasia subtypes.

2.3.1 Dentine dysplasia type I (DD-I)

It is an uncommon disorder, likely an allelic condition of the DSPP gene, that causes small crowns in primary and permanent dentitions, smaller crescentic pulps, and periapical radiolucency. It results in abnormal tooth dentine development, making weakened teeth prone to decay and breakage. Type I dentin dysplasia, also known as DD-I, is a rare genetic disorder that affects the development of dentin, the hard tissue that forms the majority of a tooth [49]. It is characterized by short, conical, pointed roots or teeth without roots, impacting both primary and permanent dentition with minor frequency of DD-I is estimated to be 1/100,000 [50]. This condition can result in weakened teeth that are prone to fractures and premature loss.

2.3.2 Dentine dysplasia type II (DD-II)

It is a minor form of dentinogenesis abnormalities, characterized by clinically normal permanent teeth with a thistle-shaped pulp and stones, and no periapical radiolucency. It is caused by a mutation in the DSPP gene and is a less severe form of type I dentine dysplasia [51]. Dentin dysplasia type II, also known as coronal dentin dysplasia, is a rare genetic condition affecting dentin formation. Clinically, causing brownish-blue staining teeth and pulp destruction.

3. Conclusion

Abnormalities in the enamel-dentine can lead to cavities, attrition, erosion, cosmetic issues, and tooth sensitivity, which can be inherited. A balanced diet, regular dental care, and good oral hygiene practices are essential for preserving tooth structure and enhancing function. Early identification and management are critical for these outcomes. Dentine dysplasia can be difficult to diagnose and treat and can cause orthodontic and endodontic treatment failure. Dentists, pediatric dentists, orthodontists, and oral surgeons must be aware of these abnormalities and adhere to best practices, considering genetic variables and family history.

Acknowledgments

I would like to express my gratitude to associate professor M.E. Önger for his encouragement and help during the figure’s preparation processes. My profound appreciation to the manager of Ondokuz Mayis University’s teaching dentistry hospital.

Conflict of interest

The authors declare no conflict of interest.

Appendices and nomenclature

AI	amelogenesis imperfecta
DI	dentinogenesis imperfecta
DD	dentine dysplasia
DSPP	dentine sialophosphoprotein
MIH	molar-incisor hypomineralization
DGI	dentinogenesis imperfecta
OGI	osteogenesis imperfecta
CPP-ACP	calcium phosphopeptide-amorphous calcium phosphate
DSP	dentine sialoprotein
DGP	dentinogenesis protein
DPP	dentine phosphoprotein