VM - Enamel + Enamel Caries Flashcards
Longitudinal Ground Section Permanent Tooth
Digital Sections: Teeth Longitudinal 1,2,4,7,8 and Oral Biology 61 and 61A
Incremental lines: Striae of retzius
Longitudinal Ground Section Permanent Tooth
Digital Sections: Teeth Longitudinal 1,2,4,7,8 and Oral Biology 61 and 61A
The general direction of enamel prisms in cuspal, mid crown & cervical regions
Longitudinal Ground Section Permanent Tooth
Digital Sections: Teeth Longitudinal 1,2,4,7,8 and Oral Biology 61 and 61A
Gnarled enamel
Longitudinal Ground Section Permanent Tooth
Digital Sections: Teeth Longitudinal
1,2,4,7,8 and Oral Biology 61 and 61A
In which part of the crown are Enamel spindles best developed?
Enamel spindles are best developed near the dentinoenamel junction, where the dentin and enamel meet. Their presence and density decrease as they extend toward the outer surface of the enamel. So, you’ll find a higher concentration of enamel spindles closer to the dentin, especially near the inner portions of the enamel layer.
What is the relationship of one enamel spindle to the dentinal tubules?
Enamel spindles are associated with the dentinoenamel junction (DEJ), the interface between dentin and enamel.
The odontoblast processes that create enamel spindles are extensions from the odontoblast cells, which reside in the pulp and produce dentin, contributing to the dentinal tubules.
Enamel spindles are formed by these odontoblast processes inadvertently crossing the DEJ into the enamel during tooth development.
So, while enamel spindles and dentinal tubules are closely related in terms of their developmental origin from odontoblasts, they exist in different dental tissues (enamel for spindles and dentin for tubules) and serve distinct functions in the tooth structure and sensory perception.
Is there any relationship between the long axis of spindles and the direction of enamel prisms?
The direction of enamel prisms in a tooth is generally parallel to the long axis of the enamel rods. Enamel rods are formed by the mineralization of enamel matrix secreted by ameloblasts (cells responsible for enamel formation). These rods or prisms extend from the dentinoenamel junction (DEJ) toward the tooth surface.
Enamel spindles, which are formed by the intrusion of odontoblastic processes, are oriented perpendicular to the dentinoenamel junction (DEJ). Therefore, the long axis of enamel spindles tends to be perpendicular to the direction of enamel prisms within the enamel structure.
Horizontal Ground section of permanent tooth
Digital section:Tooth Horizontal 1,4,5
Horizontal Ground section of permanent tooth
Digital section:Tooth Horizontal 1,4,5
What are the 3 potential origins of enamel lamellae?
Striae of Retzius: Enamel lamellae can originate from interruptions or irregularities in the deposition of enamel matrix during tooth development. Striae of Retzius are incremental growth lines in enamel caused by variations in the rate of enamel formation. Enamel lamellae can form along these incremental lines due to pauses or changes in the enamel matrix deposition.
Cracks or Stress Lines: Enamel lamellae might also arise from structural stress or trauma during tooth development or post-eruption. These can result from mechanical stresses or even from normal masticatory forces on the teeth. Over time, these stress lines might become partially calcified, forming enamel lamellae.
Fusion of Enamel Rods: Enamel lamellae can form as a result of the fusion or incomplete fusion of adjacent enamel rods during tooth development. This fusion can lead to the formation of structural defects within the enamel, resulting in the presence of enamel lamellae.
Horizontal Ground section of permanent tooth
Digital section:Tooth Horizontal 1,4,5
Is there any relationship between the direction of the tufts and that of the enamel prisms?
The direction of enamel tufts is often related to the direction in which enamel prisms are oriented. Enamel tufts are typically perpendicular to the long axis of enamel prisms. This means that where enamel prisms change direction or curve, forming small deviations or irregularities in their path, enamel tufts may be observed.
How can enamel tufts and spindles be distinguished from each other?
Origin:
Enamel Tufts: Enamel tufts arise due to localized defects during enamel maturation, often associated with areas of increased organic content and slight hypomineralization. They extend from the enamel-dentin junction (EDJ) towards the enamel surface.
Enamel Spindles: Enamel spindles are formed during tooth development when odontoblast processes from the dentin extend into the enamel matrix, crossing the dentinoenamel junction (DEJ) and penetrating into the enamel layer.
Appearance:
Enamel Tufts: Enamel tufts appear as small, irregular, brush-like structures that extend from the EDJ towards the enamel surface. They are hypomineralized and may contain more organic material compared to the surrounding enamel.
Enamel Spindles: Enamel spindles are microscopic structures that represent areas where odontoblast processes have crossed the DEJ into the enamel. They are thin, elongated structures oriented perpendicular to the DEJ, with no visible brush-like appearance.
Location:
Enamel Tufts: Enamel tufts are found scattered within the enamel and can be observed near the EDJ but extending towards the outer enamel surface.
Enamel Spindles: Enamel spindles are mainly concentrated near the dentinoenamel junction (DEJ), representing the interface between dentin and enamel. They are primarily located close to the DEJ and diminish in frequency towards the outer enamel surface.
What is the significance of hunter-schreger bands ?
The significance of Hunter-Schreger bands lies in their structural complexity and their impact on the mechanical properties of enamel. Here are some key points about their significance:
Strength and Resilience: The alternating pattern of Hunter-Schreger bands reflects the arrangement of enamel rods in a wave-like or zigzag pattern. This structural organization contributes to the strength and resilience of enamel, providing resistance against forces encountered during biting and chewing.
Resistance to Fracture: The changing directions of enamel rods between adjacent bands can help in distributing forces more effectively, reducing the likelihood of crack propagation and fracture within the enamel tissue.
Adaptation to Function: The variation in the direction and arrangement of enamel rods within Hunter-Schreger bands is believed to be adaptive, potentially related to the specific functional demands and occlusal forces experienced by different areas of the dentition. This adaptation can vary between species or even within different tooth types in the same species.
Clinical Significance: Understanding the orientation and structure of Hunter-Schreger bands is essential in various dental procedures, including restorative dentistry, prosthodontics, and understanding enamel wear patterns. It provides insights into the natural architecture of enamel and aids in creating restorations or treatments that mimic its natural characteristics.
Research and Evolutionary Studies: Hunter-Schreger bands are studied in comparative anatomy and evolutionary biology to understand variations in enamel structure among different species. These bands can provide clues about the evolutionary adaptations of teeth to different diets and functions across various mammalian taxa.
Decalcified preparation of human enamel (H+E stain)
Digital section : decalcified enamel
Identify the visible zones of the carious lesions
