Class III Resin Composite Preparation

#8 ML

Overview

Outline Form
Resistance Form
Retention Form
Convenience Form
 
 

Armamentarium

Instruments and Materials

 

Video Demonstration

Procedure

 

Select the appropriate resin composite shade using the shade-matching guide or clinical judgement

  • Clinical note: Perform shade selection with natural light prior to isolation of the tooth

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Envision the cavity preparation outline and extent

  • Clinical notes: 

    • Preparation measurements are determined by the extent of the carious lesion or existing, faulty restoration

    • Class III procedure is performed when caries extends past enamel into dentin. Therefore, the mesial-distal width of the preparation will be at least 0.2 mm into dentin

*Radiographic caries superimposed on preparation

Optional: Draw the outline of the cavity preparation using the red-blue pencil

Obtain isolation of the tooth (e.g. rubber dam, isovac/isolite, etc.)

          

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Position the mirror to achieve indirect vision of the preparation

Place a wedge in between the adjacent teeth to separate the contact areas 

  • Optional: Place a matrix band interproximally to protect the adjacent tooth from iatrogenic damage

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Orient the bur perpendicular to the lingual surface of the tooth, close to but without touching the adjacent tooth   

  • Clinical note: Position the bur over the carious lesion or existing, faulty restoration

Bur options: pear shaped carbide bur (330)

Penetrate the tooth to an initial facio-lingual depth of 1mm-1.5mm

Extend the preparation inciso-gingivally and mesial-distally  

  • Facial wall is at least 90º relative to the axial wall

  • Optional:

    • Leave a small "enamel shell" interproximally

    • Break the enamel shell with a hand instrument

  •  Clinical note:

    • Extension should remove the carious lesion or existing, faulty restoration

 

Hand instrument options: enamel hatchet, enamel hoe

 

          

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Use the probe to check for appropriate dimensions

  • Inciso-gingival length: 2-2.5mm, no greater than 3mm, depending on the length of the contact

  • Gingival floor width: 1-1.25mm

  • Incisal floor width: 1.25-1.5mm

  • Clinical note: The final preparation dimensions are determined by the extent of the carious lesion or existing, faulty restoration

Clinical note: Check for and remove remaining caries

  • Assess for remaining caries using the explorer or spoon excavator 
  • Remove remaining carious tooth structure using the largest round bur that fits into the preparation with rotary instruments (slow speed) or a spoon excavator 

 

Bur options: round carbide burs (4, 6)

          

Round internal line angles using rotary instruments (high speed with water or slow speed)

 

Bur options: pear shaped carbide bur (330)

Smooth the preparation with rotary instruments (high speed with water OR slow speed) or hand instruments  

  • Remove major unsupported enamel   

  • Remove steps/ledges  

 

Bur options: straight fissure or pear shaped carbide (556, 330)

Hand instrument options: enamel hatchet, enamel hoe

          

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Create a 0.25mm-0.5mm bevel circumferentially around the preparation, orienting the bur with rotary instruments (high speed with water or slow speed) at a 45-degree angle to the cavosurface margin

  • Do not bevel in areas subject to masticatory forces (e.g. incisal contact)

 

Bur options: coarse diamond bur (flame)

Clean and dry the preparation using the air-water syringe

Examine the preparation and evaluate for proper dimensions

  • Use the explorer to check for smoothness 

  • Use the probe to check for appropriate depth and width

  • Clinical note: the final dimensions of the preparation are determined by the extent of the carious lesion or existing, faulty restoration

     

  • Axial wall: flat or slightly convex

  • Facial wall: at least 90º relative to the axial wall

  • Facial depth: depends on the facio-lingual depth of the contact area

  • Preserve the facial contact​

  • Gingival floor width: 1-1.25mm

  • Incisal floor width: 1.25-1.5mm

  • Inciso-gingival length: 2-2.5mm, no greater than 3mm

    • Depends on length of contact area​

  • Preserve the incisal contact

  • Gingival contacts broken by: ~0.25mm 

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*Hover for summary details

 

Checklist

Progress