Dental Procedures: Isolation Techniques

Poor Isolation of Operating Area

• Causes:
  • No rubber dam or leaking rubber dam
  • Inadequate cotton roll isolation
  • Careless technique
  • Gingival preparation too deep to isolate
• Potential Solutions:
  • Better technique
  • Matrix use for isolation
  • Non-bonded restorative material
  • Repeat bonding if area is contaminated

White Line/Halo Around Enamel Margin

• Causes:
  • Traumatic contouring/finishing
  • Inadequate etching/bonding
  • High-intensity curing causing polymerization stress
• Potential Solutions:
  • Re-etch, prime, and bond
  • Carefully remove fault and re-restore
  • Use atraumatic finishing techniques (e.g., light intermittent pressure)
  • Use low-start polymerization

Voids

• Causes:
  • Mixing self-cured composite incorrectly
  • Spaces between composite increments during insertion
  • Tacky composite pulling away from the preparation during insertion
• Potential Solutions:
  • More careful technique
  • Repair of marginal voids by preparing and re-restoring the area

Weak or Missing Proximal Contacts (Classes II, III, and IV)

• Causes:
  • Inadequately contoured matrix band
  • Inadequate wedging (pre- and intra-op)
  • Matrix band movement/not in contact with adjacent proximal surface
  • Circumferential matrix used when restoring only one contact
  • Tacky composite pulling away from matrix
  • Matrix band too thick
• Potential Solutions:
  • Properly contour matrix band
  • Ensure matrix contact with adjacent tooth
  • Firm preoperative and insertion wedging
  • Matrix system placed only around the proximal surface
  • Hand instrument to hold matrix during composite placement
  • Be careful with insertion technique

Incorrect Shade

• Causes:
  • Inappropriate operator lighting
  • Shade selection after drying the tooth
  • Shade tab not matching actual composite
  • Incorrect shade selection
• Potential Solutions:
  • Use natural light if possible
  • Select shade before isolation
  • Pre-cure shade on tooth and remove
  • Avoid shining light directly on the area while selecting shade
  • Understanding typical shade zones on natural teeth

Poor Retention

• Causes:
  • Inadequate preparation form
  • Operating area contamination
  • Poor bonding technique
  • Intermingling of different bonding materials
• Potential Solutions:
  • Preparing tooth with bevels/flares for secondary retention
  • Maintain isolation while bonding
  • Follow manufacturer instructions
  • Avoid mixing different bonding materials

Contouring and Finishing Problems

• Causes:
  • Injury to adjacent unprepared tooth structure
  • Over-contouring restoration
  • Under-contouring restoration
  • Cementum ditching
  • Inadequate anatomic tooth form
• Potential Solutions:
  • Care with rotary instruments to avoid adjacent tooth damage
  • Appropriate matrix with axial and line angle contours
  • Embrasure form matching adjacent tooth
  • Avoid roughened surfaces with rotary instruments
  • Use proper contouring instruments
  • View restoration from various angles during contouring