What is a Bevel ?
Bevels are the angulation which is made by 2 surfaces of a prepared tooth which is other than 90 degrees. Bevels are given at various angles depending on the type of material used for restoration and the purpose the material serves.
Definition of Bevel: “Any abrupt incline between the 2 surfaces of a prepared tooth or between the cavity wall and the Cavo surface margins in the prepared cavity”
Bevels are the variations which are created during tooth preparation or cavity preparation to help in increased retention and to prevent marginal leakage. It is seen that in Bevels Occlusal cavosurface margin needs to be 40 degrees which seals and protects enamel margins from leakage and the Gingival Cavo surface margin should be 30 degrees to remove the unsupported enamel rods and produce a sliding fit or lap joint useful in burnishing gold.
Types or Classification of Bevels based on the shape and tissue surface involved :
Partial or Ultra Short Bevel:
- Beveling which involves less than 2/3rd of the Enamel thickness. This is not used in Cast restorations except to trim unsupported enamel rods from the cavity borders.
Short Bevel:
- Entire enamel wall is included in this type of Bevel without involving the Dentin. This bevel is used mostly with Class I alloys specially for type 1 and 2. It is used in Cast Gold restoration
Long Bevel:
- Entire Enamel and 1/2 Dentin is included in the Bevel preparation. Long Bevel is most frequently used bevel for the first 3 classes of Cast metals. Internal boxed- up resistance and retention features of the preparation are preserved with Long Bevel.
Full Bevel:
- Complete Enamel and Dentinal walls of the cavity wall or floor are included in this Bevel. It is well reproduced by all four classes of cast alloys, internal resistance and retention features are lost in full bevel. Its use is avoided except in cases where it is impossible to use any other form of bevel .
Counter Bevel:
- It is used only when capping cusps to protect and support them, opposite to an axial cavity wall , on the facial or lingual surface of the tooth, which will have a gingival inclination facially or lingually.
There is another type of Bevel called the Minnesota Bevel or the Reverse Bevel, this bevel as the name suggest is opposite to what the normal bevel is and it is mainly used to improve retention in any cavity preparation
If we do not use functional Cusp Bevel –
- It Can cause a thin area or perforation of the restoration borders
- May result in over contouring and poor occlusion
- Over inclination of the buccal surface will destroy excessive tooth structure reducing retention
Types or Classification of Bevels based on the Surface they are placed on:
Classification of Bevels based on the two factors – Based on the shape and tissue surface involved and Based on the surface they are placed on –
Based on the shape and tissue surface involved:
- Partial or Ultra short bevel
- Short Bevel
- Long Bevel
- Full Bevel
- Counter Bevel
- Reverse / Minnesota Bevel
Based on the surface they are placed on:
- Gingival bevel
- Hollow ground bevel
- Occlusal bevel or Functional cusp bevel
Functions of Gingival bevel:
- Removal of Unsupported Enamel Rods.
- Bevel results in 30° angle at the gingival margin that is burnishable because of its angular design.
- A lap sliding fit is produced at the gingival margin which help in improving the fit of casting in this region.
- Inlay preparations include of two types of bevel Occlusal bevel Gingival bevel
Hollow Ground (concave) Bevel: Hollow ground bevel allows more space for bulk of cast metal, a design feature needed in special preparations to improve material’s castability retention and better resistance to stresses. These bevels are ideal for class IV and V cast materials. This is actually an exaggerated chamfer or a concave beveled shoulder which involves teeth greater than chamfer and less than a beveled shoulder. The buccal slopes of the lingual cusps and the lingual slope of the buccal cusps should be hollow ground to a depth of at least 1 mm.
Functions of Occlusal Bevel:
- Bevels satisfy the requirements for ideal cavity walls.
- They are the flexible extensions of a cavity preparation , allowing the inclusion of surface defects , supplementary grooves , or other areas on the tooth surface.
- Bevels require minimum tooth involvement and do not sacrifice the resistance and retention for the restoration
- Bevels create obtuse-angled marginal tooth structure, which is bulkiest and the strongest configuration of any marginal tooth anatomy, and produce an acute angled marginal cast alloy substance which allows smooth burnishing for alloy.
Functional cusp Bevel:
An integral part of occlusal reduction is the functional cusp bevel. A wide bevel placed on the functional cusp provides space for an adequate bulk of metal in an area of heavy occlusal contact.
thanx alot :)
Truly helpful!
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thanks alooooot sir
is there any pics for counter bevel ??
add something about scalloping bevel
THANK U FOR THE INFO SIR BUT I AM SEARCHING FOR REVERSE BEVEL,IT WILL BE FINE IF ADD A BIT ABOUT REVERSE BEVEL
Have updated the post with Reverse Bevel, there is not much info available about it, what I know is that it is used for retention and is also called as Minnesota bevel. Will try to gather more info and update it in the post.
Do we give bevel on enamel for a composite restoration?
What’s the difference between chamfer and bevel?
It is useful to give a bevel for composite restorations as well because bevel will remove any unsupported dentin on the tooth surface which can lead to marginal leakage later on.
Is there any contraindications for bevel
Bevel is contraindicated on the Cavosurface margins of a Class I amalgam restoration as it will lead to fracture as a thin layer of amalgam is brittle and will fracture easily leading to marginal Leakage in future and it is also difficult to polish.
How can i download it?
Do we give bevel in class 2 amalgam restoration?
Yes, it is important to give a bevel.
At which site we will give bevel in class 2 amalgam restoration?
Which instrument is used for gingival margin bevel?
For Gingival Margin bevel, we use “Enamel Hatchet“
Which one is the most important bevel in inlays please, is it the gingival or the occlusal Bevel ?!
There is nothing as most important, both the bevels serve their purpose in the success of a Restoration so both the bevels are required depending on the cavity and the inlay being prepared.
If the Gingival bevel is not done properly there can be marginal leakage at the gingival level and if the occlusal bevel is not given properly there can be fracture of the restoration leading again to marginal leakage and failure of the restoration.
I came through a question of HAAD exam that says which bevel is the most important in inlay restoration , so am guessing both are important idk how but i think there are two answers that are right .. so thank you so much
am sorry doctor but i would be so thankful if you could help me with some answers , i mean if it won’t disturb you ofcours .. thank you again
I have question about types of bevels used for cast gold restoration thank you
Yeah please let me know what it is about
Sir… I have doubt where bevel is placed in beveled conventional cavity preparation gor composite..??
Yes a Bevel should be used for any type of Restoration as it helps in removing the unsupported Dentin or Enamel. It also helps in giving bulk to the Restorative material at the margins.
Why is it not necessary to bevel the gingival wall of the distolingual tooth preparation?
Why bevel is contraindicated in ceramic inlays
In case of Ceramic Inlays, Retention form is not as important as the Restoration is bonded to the tooth hence Bevels are contra-inditacted in Inlays. Cavosurface angles of 90 degrees are preferred with smooth flowing margins to help in the proper seal in the end restortaion.
Do you have any references regarding the Hollow Ground (concave) Bevel? Thank you much for your help.
Can you preform a bever in a root caries ?
It depends on till what extent the Root caries has progressed, with Root Caries it usually involves the Dentin so proper Isolation and Gingival contouring should be done to achieve proper isolation and to visualize the borders of the Cavity properly. So yes you can give bevel in a Root caries case but that depends on the extent and position of the borders of the prepared cavity.
Why is counter bevel not given on facial surface of premolars and molars?
why we can not do bevel in decedous teeth
We can and should be giving Bevels when required in Decidious teeth as well. It is not given anywhere that Bevles are not required or contraindicated in Decidious teeth.