What do biological contours do
Stimulate natural healthy teeth
Protect the supporting tissues
Maintain the health of gingiva + periodontum
Minimize trauma and irritiation to bony tissue
What do Improper Contours do
Early breakdown of supportive structures
Early loss of teeth
Biologic Contour Check List
Facial and LIngual convexities Mesial and sital concavities Transitional line Contact area and embrasures Cervical Curvatures Marginal ridges Tooth reduction
The greatest convexity on the axial surface of the crown
Crest of Curvature/ Height of Contour
What are the shapes a contour
Curved shape
Where are the curvatures unifrom when viewing a tooth from the mesial and distal aspect
the cervical and middle third
What does the proper degree of curvature allow for
Deflecting food over the gingival margin preventing irritiation
stimulation of soft tissue
What happens if the curvature is absent
Gingival tissue will driven Apically and will result in pathological changes
What happens if the curvature is too great
Gingiva is protected too much and loses gingival tone
Food and debris may back and lead to chronic inflammation
How far facial should something be contoured
1/2 mm facially beyond the CEJ
Where is the Height of Contour facially
in the cervical 1/3
How far should the lingual curve go
no more than 1/2 mm lingually beyond the CEJ
where si the Height of contour lingually
in the middle 1/3(except mandibular second premolars and molars which are3/4 to `1mm lingual
The tooth surface that is gingival to the height of contour and above the gingival crest
Emergence profile
The emergence profile
THe profile of the gingival 1/3 of a restoration as it emerges from the gingival crevice
What should the emergence profile look like
Be flat for 2-3 mm above the gingiva
What do Proximal surfaces look like
Always flat or slightly concave betwen the contact area and the CEJ to allow room for the Papillae
How many locations can the contact area have
Various locations
Function of Contact areas
Aids in proper development of the arches
Prevents food from packing between the teeth
Allows the teeth to be self cleaning (to some extent)
Prevents injury to the interproximal tissues
What do contacts points become as teeth mature
Contact areas
Why do contacts between teeth get wider wimeth ti
To wear as the teeth move during function
Where should the contact areas of all posterior teeth be
Buccal to the central fossa and in the occlusal 1/3
- exception (between max molar: junction of occlusal and middle 1/3 or middle 1/3 not occlusal 1/3)
- Exception (between max molars in middle 1/3 not buccal)
location of distal and mesial contacts in relation to one another
Distal contacts are more cervical (except mandibular premolars)
Where is the transitional line
Betweent he faciolingual convexities and proximal concavities
