1st lecture comparative dentistry Flashcards
What has a functional basis?
Every curve and segment of a normal tooth
Four Phylogenetic Classes of Tooth Forms
- Single Cone (haplodont)
- Three Cusps in line (Tricondont)
- Three Cusps in a Triangle (Tritubecular Molar)
- Four Cusps in a quadrangle (quadritubecular molar)
Single Cone
haplodont
Three Cusps in line
trricondont
Four Cusps in a quadrangle
quadritubecular molar
Haplodont
Reptilian Stage
-Simplest form of tooth= single cone
Characteristics of Haplodonts
-Many teeth in both jaws
-Jaw movement is limited, to simple open and close- hinge
-NO OCCLUSIOn of teeth
-Teeth used for prehension or combat
-Main function is procurement of food. Jaw movements are related and government by tooth form in all cases
Tricondont
Easy Mammalian Stage
-Three Cusps in a line in posterior teeth
-The Largest cusp is centered- with a smaller cusp located anteriorly and posteriorly
-Carnivores have teeth representing this form
Tritubercular
Dogs and Carnivores
-THREE Cusps in a Triangle
-Three cornered tritubercular molar arrangement
-teeth bypass each other more or less when jaw is opened or closed
Tritubercular
Dogs and Carnivores
-THREE Cusps in a Triangle
-Three cornered tritubercular molar arrangement
-teeth bypass each other more or less when jaw is opened or closed
Quadritubercular
-First time that one reflects occlusal contact relationship between the teeth of upper and lower jaws.
Four Cusps in a quadrangle!
Apes
Have similar dentition to humans.
Main difference is the development of the canines, arch form, and jaw development!
Lobes
The multiplication and fusion of lobes during tooth development are demonstrated graphically when human teeth are viewed from the mesial or distal aspects. Anterior teeth, which are used for incising or apprehending food, reflect the single cone, whereas the posterior or multicusped teeth, which are used for grinding food in addition to having a shearing action, appear to be two or more cones fused
What represents a primary center of formation?
Each Lobe of a tooth- this ALL teeth appears to be a combo of four or more lobes!
Primary Center of Formation
Mamelon, Cingulum, Cusp Tip
Anterior Teeth
Mesial, Labial/Facial, Distal, and Lingual Lobe
Premolars
Mesial, Buccal, Distal, Lingual- if you are a 3 cusp variety of the Mandibular 2nd Molar, you have a mesiolingual and distolingual lobe!
Molars
Named as the cusps
1: Mesiobuccal Cusp = Mesiobuccal Lobe
Isognathus
Jaws of equal size
Trait is to LIMIT lateral movement
Anisognathous
Jaws of unequal size
Trait tends to increase mobility of the mandible in a lateral direction
Bunodont
Refers to tooth-bearing conical cusps
Selenodont
Characterized by low crowns, crescent shaped cusps when viewed from above
Tooth form and jaw movements of humans
Humans are bunodont and relatively isognathus- not perfectly isognathus because the maxillary arch overlaps horizontally the mandibular arch
Geometries
All aspects of each tooth crown except the incisal or occlusal aspect may be outlined schematically by these three shapes:
1) Triangle
2) Trapezoid
3) Rhomboid
Anterior Teeth from the Proximal Shape
Triangular
Because these teeth are prehensile
Trapezoid
All TEETH from the facial/lingual- with the longest uneven side toward the occlusal/incisal and the shorter side at the cervix
This allows for two antagonist in opposing arch
Shape of the Proximal surface of Maxillary Posterior Teeth
Trapezoids- with the shortest uneven side toward the occlusal, longer side at the cervix
Helps to penetrate food, without constriction, the occlusal forces could be overwhelmed for the base of crown.
Shape of Proximal Surface of Mandibular Posterior Teeth
Rhomboids
The rhomboidal form inclines the crown in a lingual direction.
Long axes of maxillary and mandibular teeth are kept parallel to one another
Each tooth of the dentition has two antagonist– what is the exception
Except the mandibular central incisor
Form and Function
Incision, prehension, and trituration
Human Dentition
Omnivores
A general restorative principle states that occlusal forces in dental restorations should be directed along which axis of teeth?
The long axis
Interproximal Form
*Proximal contacts protect the soft tissue between teeth
Tissue that occupies this space is called the interdental papilla or gingival papilla
Dehiscence
Partial absence of bone over the tooth
Fenestraton
Window or hole in the bone with an intact gingival alveolar process
Root Form
Associated with the overall form of the tooth and the work it has to do.
The angle of the incisal and occlusal surfaces of anterior and posterior teeth are positioned to be placed OVER the center of the root or WITHIN confines of the root trunk
Roots of which teeth are flared for stabilization
Posterior teeth
Is the dental arch flat?
No
Curvature of Spee
Anterior to Posterior curvature of dentition
Curvature of Wilson
FACIAL TO LINGUAL CURVATURE OF THE POSTERIOR TEETH
Compensating Occlusal Curvature
Is a combination of the curve of spee and the curve of Wilson
Overjet
Horizontal overlap
Overbite
vertical overlap
