Introduction to Mechanical Behavior and Biomechanics in Dentistry

A set of practice flashcards covering basic biomechanical concepts, dental materials' mechanical behavior, occlusal forces, stress-strain curves, and specific mechanical properties.

How did Hatze H (1974) define biomechanics?

It is the study of the structure and function of biological systems by means of mechanics.

What is mechanics defined as in the context of biomechanics?

Mechanics is the science that studies the effect of FORCE on bodies.

How is biomechanics conceptualized in terms of force?

It is the science that studies the effect of FORCE on the structure and function of a biological system (or a body).

How does Susan J. Hall define biomechanics in "Basic Biomechanics"?

Biomechanics uses the principles of mechanics to solve problems related to the structure and function of living organisms.

Why is the knowledge of basic biomechanical concepts essential for a dentist?

It is essential to provide the best therapy when using dental materials designed to play a specific role or replace injured tissues.

What is expected of biomaterials when placed in a biological system?

They are subjected to a number of challenges and are expected to behave and function exactly as the structure they are replacing.

What is the stomatognathic system?

An anatomical system comprised of teeth, jaws, their junction, and all associated soft tissues, whose functions (mastication, deglutition, speech, and respiration) are dependent on dynamic and mechanical activities.

Which dental fields present clinical scenarios challenging biomaterials' mechanical behavior?

Restorative dentistry, endodontics, prosthodontics, implantology, temporomandibular joint prosthesis, and orthodontics.

How does force (load) originate in biomechanics?

It is the product or result of interaction between at least two bodies when one directly interacts with another by contact.

What are the three defining characteristics of a load?

Point of application, magnitude, and direction of application.

What is stress, and how is it calculated?

Stress is the internal reaction of a body being loaded or interacting with another body. It is calculated as the ratio of force (load) per area, with the unit $N/m^2$.

What is the hinge axis in the oral environment?

An imaginary line around which the condyles can rotate without translation.

What is the significance of the terminal hinge position?

It is the most retruded hinge position, which is learnable, repeatable, and recordable, coinciding with the position of centric relation.

What is the range of maximum occlusal forces in humans?

Maximum occlusal forces range from $200$ to $3500\,N$.

How do occlusal forces vary across the dental arch?

They are higher in magnitude in the posterior region of dental arches (closer to the mandibular hinge axis), decreasing from molars towards incisors.

What three factors must be considered when planning/designing restorations and selecting dental materials?

1) Tooth location, 2) Force-generating capacity of the individual, and 3) Type of opposing dentition (natural vs. restored).

What is a stress-strain curve?

It is the graphical relationship between stress and strain in an object under load, unique for each material/object, revealing many of its mechanical properties.

How are the Proportional Limit (PL), Elastic Limit (EL), and Yield Stress (YS) defined on a stress-strain curve?

They are defined as the highest stresses at which the stress-strain curve is a straight line, representing the highest stress under elastic deformation.

What is the difference between Ultimate Tensile Strength (UTS) and Ultimate Compressive Strength (UCS)?

UTS is the maximum stress a material can withstand before failure in tension, while UCS is the maximum stress a material can withstand before failure in compression.

What is fracture stress?

The stress at the moment of fracture, which can occur due to tensile, compressive, shear, or flexural stresses.

What is the Modulus of Elasticity (Elastic Modulus)?

It is defined as the ratio between stress and strain within the elastic regimen (the steepest slope), measuring a material's resistance to being deformed elastically (degree of rigidity or flexibility).

What is resilience in dental materials?

The amount of energy necessary to deform the material to the proportional limit, measured by the area under the elastic portion of the stress-strain curve.

What is toughness in dental materials?

The amount of energy necessary to cause fracture, represented by the total area under the elastic and plastic portions of a stress-strain curve.

How is yield strength defined according to Ferracane (2013)?

An arbitrary property representing the borderline between elastic and plastic deformation.

How is fatigue resistance defined in dental materials?

Resistance to repeated mechanical loading and unloading cycles.

How is flexure strength defined in dental materials?

Resistance to fracture under combined tensile and compressive stresses.

How is hardness defined in dental materials?

Resistance to indentation or penetration.