Etiological Factors Causing Dentofacial and Craniofacial Anomalies

Teratogens Affecting Dentofacial Development

Teratogens are agents that can cause developmental abnormalities in the fetus. Specific effects on the developing dentofacial structures include:

• Ethyl Alcohol: Associated with central midfacial deficiency.
• Aminopterin: Linked to anencephaly.
• Aspirin, Dilantin, Valium, and Snuff Smoke: Associated with Cleft Lip and Palate (LPH).
• Toxoplasma: Can cause hydrocephalus, microcephaly, and microphthalmia.
• Hypervitaminosis D: May lead to premature closure of sutures.
• X-Rays: Associated with microcephaly.
• Rubella Virus: Can cause deafness, microphthalmia, and cataracts.

Trauma and Growth Disorders

Trauma, particularly during critical developmental periods, can lead to significant growth disorders in the craniofacial region.

Intrauterine and Birth Trauma

• Injury by Intrauterine Molding: Can generate lesions in the mandibular jaw.
• Trauma During Birth: Often affects one or both temporomandibular joints (TMJ), causing deformation, inadequate jaw development, and temporomandibular disorders (TMD).
• Infant Mandibular Fractures: These injuries can later distort the development of the craniofacial skeleton.
• Delivery Trauma (Forceps Use): Especially affects the jawbone.

Environmental Factors in Dentofacial Anomalies

Environmental factors influence normal growth, shape, and function, often interacting with individual gene expression. These factors contribute to the pathogenesis of anomalies in the masticatory system and are classified based on their nature:

• Accidents and Traumas
• Habits
• Local, General, and Nutritional Diseases
• Teratogenic Agents and Systemic Diseases

Environmental factors are also categorized etiologically based on the time of influence:

Prenatal Environment Influences

While the fetus is generally well protected, certain prenatal factors pose risks:

• Nutritional Factors: Generally do not cause direct damage to fetal development.
• Maternal Viral Infections: Can cause teratogenic malformations affecting Branchial Arches I and II, leading to conditions like micrognathia, oligodontia, or anodontia.
• Trauma and Maternal Fibroids: Inappropriate fetal positioning due to these factors can cause craniofacial skeletal asymmetries.
• Obstetric Trauma: Can provoke injuries to the Temporomandibular Joint (TMJ), potentially leading to subsequent joint ankylosis.

Postnatal Environment and Accidents

Accidents or physical trauma occurring postnatally can cause abnormalities affecting tooth eruption in the dental arches or alterations in the Temporomandibular Joint (TMJ).

Local Factors: Oral Habits and Malocclusion

Specific habits act as local factors that trigger the development of malocclusions, depending heavily on their frequency and intensity. These include:

• Finger sucking
• Lip and tongue thrusting
• Pacifier use
• Atypical swallowing
• Mouth breathing
• Bruxism
• Abnormal postures

Dental Abnormalities: Shape, Size, and Number

Shape Abnormalities

Factors such as developmental defects, trauma, and metabolic disorders can alter the initial shape of tooth development, creating morphological abnormalities that lead to malocclusion. Examples include:

• Dilaceration
• Concrescence
• Fusion
• Gemination
• Schizodontia (Twinning)
• Amelogenesis Imperfecta

Size Abnormalities

Tooth size varies greatly among individuals. Reference is usually taken from the relationship between the size of the jaws and the teeth in question. Abnormalities include:

• Microdontia (abnormally small teeth)
• Macrodontia (abnormally large teeth)