Oral Pathology 1, Lecture 6

Oral Pathology 1, Lecture 6

• Environmental Alterations of Teeth:

  • Environmental effects on tooth structure development
  • Post-developmental structure loss
  • Environmental discolorations of teeth
  • Localized disturbances in eruption

• Developmental Alterations of Teeth:

  • Developmental alterations in the number of teeth
  • Developmental alterations in the size of teeth
  • Developmental alterations in the shape of teeth
  • Developmental alterations in the structure of teeth

1. Environmental Effects on Tooth Structure Development

• Ameloblasts: Extremely sensitive to external stimuli
• Multiple factors can result in enamel abnormalities.
• Simultaneous factors worsen enamel defects.
• Amelogenesis Imperfecta: Hereditary enamel abnormalities unrelated to other disorders.

Systemic Factors

• Birth trauma
• Chemicals (e.g., amoxicillin, antineoplastic chemotherapy)
• Chromosomal abnormalities
• Infections
• Inherited diseases
• Malnutrition
• Medical conditions (e.g., asthma, diabetes, renal disease)
• Neurologic disorders

Local Factors

• Acute mechanical trauma

• Electrical burns

• Irradiation

• Local infection

• Dental Enamel: Unique, non-remodeling structure, permanent abnormalities.

  • Three major stages: matrix formation, mineralization, maturation.

• Timing of ameloblastic damage affects enamel defect location and appearance.

• Clinical and Radiographic Features:

  • Hypoplasia
  • Diffuse opacities
  • Demarcated opacities
  • Enamel enamel defects can be localized or present on multiple teeth.
  • Enamel hypoplasia: quantitative defects (pits, grooves, missing enamel)
  • Enamel opacities: qualitative defects (diffuse or demarcated, variations in translucency, normal thickness).
  • Diffuse opacities: increased white opacity without clear boundaries.
  • Demarcated opacities: decreased translucence, increased opacity, sharp boundaries.

(1) Turner Hypoplasia

• Frequent enamel defect in permanent teeth.
• Due to periapical inflammatory disease or traumatic injury of a deciduous tooth.
• The enamel defects vary from white, yellow or brown discoloration to extensive hypoplasia.
• Frequently occurs in permanent bicuspids due to relationship to overlying deciduous molars.

(2) Molar-Incisor Hypomineralization (MIH)

• Predominantly affects permanent first molars.
• Characterized by hypomineralization of 1-4 permanent first molars.
• Enamel may appear white, yellow or brown with sharp demarcation.
• Associated with post-eruptive enamel loss, increased sensitivity, and difficulty with anesthetic.
• Incisor involvement correlates with the number of affected molars
• Etiology unclear, possibly multifactorial

(3) Hypoplasia Caused by Antineoplastic Therapy

• Dental developmental alterations due to therapeutic radiation or chemotherapy.
• Severity depends on patient age, treatment type, and dose.
• Associated defects include hypodontia, microdontia, radicular hypoplasia, and enamel hypoplasia.
• Radiotherapy can cause mandibular hypoplasia and reduced vertical development of the lower third of the face.
• Chemotherapy can cause enamel hypoplasia and discoloration.

(4) Dental Fluorosis

• Enamel defects due to excessive fluoride intake.
• Can cause hypomineralized enamel, which leads to white, chalky areas (mottled enamel)
• Severity is dose- and time-dependent.
• Affected teeth are often caries resistant.
• Definitive diagnosis requires bilateral symmetry, prior excessive fluoride intake or elevated fluoride levels.
• Fluorapatite crystal formation is a former thought process that fluoride reduces caries. The current understanding is post-eruptive effects that control demineralization and remineralization. Consumption of properly fluoridated water is associated with a low frequency of mildly altered enamel. Monitor fluoride intake intensely in the first three years of life.

(5) Syphilitic Hypoplasia

• Congenital syphilis causes enamel hypoplasia, though it is rare.
• Anterior teeth (Hutchinson incisors): Crowns that are shaped like screwdrivers, prominent in the middle third aspect
• Posterior teeth (mulberry molars): Disorganized occlusal surfaces

Tooth Wear

• Attrition: Loss of tooth structure due to tooth-to-tooth contact during occlusion and mastication.
• Abrasion: Loss of tooth structure due to mechanical wear by external agents (e.g., tooth-brushing with abrasive materials).
• Erosion: Loss of tooth structure due to chemical processes (e.g., acids in foods and drinks).
• Abfraction: Loss of tooth structure due to occlusal stresses creating repeated tooth flexure at locations away from the point of loading.

Treatment and prognosis

• Normal levels of attrition require no therapy.
• Interventions are reserved for pathologic cases
• Resolve tooth sensitivity and pain.
• Identify causes and protect remaining dentition.
• Treatment varies based on the cause
• Patient education about possible issues with tooth wear is important.