Dental Isolation and Caries Access

Inspection of Contact Area

• Find the contact of the LL6 with the adjacent tooth.
• Contact can be buccally or lingually/palatally placed in a crowded tooth.
• Contact area can happen mesially or distally (MO or DO or occlusal)

Rubber Dam Isolation

• Used for moisture control, saliva and blood flow contamination prevention
• Protects patient airways and soft tissues from instruments and chemicals
• Improves direct vision via tissue retraction of the mucosa and tongue 
• Provides barrier protection from fluid-borne pathogen transfer from patient to dentist
• Components include a rubber dam sheet, winged/unwinged clamp, floss, wooden wedge, wedjet, rubber dam frame, rubber dam forceps, and a rubber dam punch.
• The rubber dam clamp is secured with dental floss before placement.

Initial Access to Caries

• It can be achieved using tungsten carbide or diamond bur in a fast handpiece/ air micromotor.

Placement of Bur

• The cutting end of the bur is placed perpendicular to the long access of the tooth
• Caries typically starts at the contact and spreads downwards
• A Diamond 541 bur is 3mm from the cutting end to the neck
• If the whole length is used, it reaches deep enough to break the contact and remove caries
• The bur depth may vary in smaller teeth or with tooth wear
• The bur should go deep enough to access the caries

Accessing Caries Proximally

• The bur must be placed close to the distal/mesial marginal ridge to prevent damage to the adjacent tooth. 
• Placement should be between the distal/mesial pit and the edge of the marginal ridge or 0.5mm away from the distal/mesial marginal ridge

Overcoming the Risk of Damage to Adjacent Tooth

• When drilling close to the marginal ridge, the bur can slip and damage the adjacent tooth.
• Make a ditch cut with a depth of 0.5mm, located as close to the marginal ridge or between the distal pit and marginal ridge.
• a ditch prevents the bur from slipping onto the adjacent tooth

Preventing Damage to Adjacent Teeth When Drilling Down

• Leaving a thin shelf of enamel ensures the bur does not damage the adjacent tooth
• This can be removed using a hand instrument

Instruments for Peripheral Caries

• A rosehead bur with a slow handpiece and a spoon excavator for soft caries

Proximal Box/Cavity

• A thin shelf of enamel can be chipped away ideally with an enamel hatchet or an excavator
• There is a risk, excessive force could fracture the tooth proximally
• If not easily chipped off, make the enamel shelf thinner using a slow handpiece or a fast 541 bur carefully

Box-Shaped Preparation

• Should be initially made small and then enlarged so an excavator removes any soft caries at the periphery
• An excavator or a stainless-steel rosehead bur in a slow handpiece can remove soft caries at the periphery of the distal/mesial box; exercise extra caution when using a bur due to the lack of tactile sensitivity

Accessing Caries Occlusally

• Use a diamond 541 bur is 3mm as a toll to cut an occlusal cavity
• Cut 2mm deep to reach the EDJ
• Follow the fissure pattern to gain access.
• Occlusal caries is accessed and the cavity is enlarged,so instruments reach the caries.

Cleaning the EDJ

• Excavate the pulpal floor and the axial pulpal wall by hand
• Only soft carious dentine should be removed, leaving stained tissue on the cavity floor. 
• Remaining caries texture is checked with a probe to ensure softened, simulated carious dentine get removed from the EDJ and more scratchy, stained caries-affected dentine remains on the peripheral dentine and the cavity floor

Stain-Free Enamel Dentine Junction Preparation

• The dentine adjacent to the EDJ should be stain-free for assessment.

Matrix Band

• The peripheral EDJ should be clear with some stained affected dentine on the pulpal floor of the cavity
• Pulpal integrity is maintained here
• A matrix band and wedge placement is to ensure the matrix's cervical adjustment. 
• The matrix handle should be positioned buccally, but its edge is sharp,avoid pushing too hard. 
• The rubber dam should not be visible in the proximal box after placement
• A proximal wedge is inserted cervically to prevent excess material from seeping underneath and an overhang forming.
• Make sure of a contact point with the adjacent tooth
• Vaseline is applicable on the metal band's inner aspect to prevent GIC from sticking. 

Dentine Conditioner (10% Polyacrylic Acid)

• Dentine conditioner is placed on the cavity and then washed & dried

GIC Placement

• Mix GIC, and fill the cavity quickly. 
• Some morphology creation should be done
• Take a cotton pledget with Vaseline for easier GIC pushing. 

Why an Isolation

• Moisture control to prevent saliva and blood contamination 
• Protective of patient airways and soft tissues from instruments and chemicals
• Improves direct vision of working area; which aids in tissue retraction of the mucosa and tongue
• Provides barrier protection from fluid-borne pathogen transfer from patient to dentist

Different Types of Dentine

• Sound dentine
• Infected dentine
• Affected Dentine

Differentiation of Infected vs. Affected Dentine

Instruments for Deep (Pulpal) Caries 

• Spoon excavator achieves more tactile feedback and is most conservative

Assessments for Final Restoration

• No overhangs (plaque retentive factor); removal with a polishing strip
• The filling material shouldn't be insufficient or contains voids
• Marginal defects 
• The occlusion is to be checked with articulating paper
• Check proximal contact with floss, prevents food packing
• The straight probe checks the level of the filling compared to the neighboring tooth

Long Term Management

• Secondary Caries prevention takes place to ensure longevity
  • At 6-8 weeks, reduce GIC as a poor load bearer/poor compressive strength.
  • Filling with composite ensures durability and longevity, use the sandwich technique.

GIC

• Water-based plastic direct dental restorative cement
• Formed from an acid-base reaction
• It shows fracture resistance in non high load bearing area
• Releases fluoride initially at high levels then decreases after 8-10 weeks
• Apply for when struggling to gain effective moisture control

GIC Bond To Enamel

• The reaction between the GIC and the tooth enamel involves the exchange of ions where the positively charged ions in the GIC (such as aluminum, silicon, and calcium ions) interact with the negatively charged ions in the tooth enamel, such as phosphate and carbonate ions.

GIC Bond to Dentine

• The material release ions that react with the exposed collagen fibers in the dentine, forming a chemical bond between the two surfaces.
• The reaction between the GIC and the dentine involves the exchange of ions, where the positively charged ions in the GIC (such as aluminum, silicon, and calcium ions) interact with the negatively charged ions in the exposed collagen fibers.
• As the processes progresses, a crystalline structure forms at the interface between the GIC and the dentine creating a strong and durable bond.
• The bond between the GIC and the dentine enhanced by the formation of micro tags: projections extending from the GIC into pores/irregularities making a mechanical bond.

Modifications Before GIC Placement

• The purpose is to enhance retention and margin integrity
• Remove unsupported enamel to reduce fracture chances and leakage
• Create rounded internal line angles to reduce stress in load-bearing areas
• The Enamel margin is lightly beveled to increase the surface area for bonding
• Dentine conditioner is added (10% polyacrylic acid)
  • Removes the smear layer to expose Ca2+ ions making the surface better for chemical adhesion
  • GIC wetability is improved via energy increase of tooth surface. 

Pulpal Protection Required

• Use with Indirect Pulp Cap; where the floor of the cavity is close to the pulp, but not breached
  • GIC treatment plan
    • Promotes remineralisation, releases fluoride
    • Good seal provided, bacterial penetration prevented
    • Prevents infection or trauma to the pulp by providing a barrier and releasing fluoride avoiding further decay or damage
    • GIC provision protects pulp
• Not direct Pulp Cap; where a small breach of the pulp chamber with pulp exposure occurs < 1mm
  • GIC is acidic therefore cannot be placed
  • Treatment plans
    • Mineral Trioxide Aggregate (MTA)
      • Often used for direct pulp capping because it's biocompatible and stimulates dentinogenesis of dentine formation.
      • Seals and encourages a dentin bridge formation at the site of exposure
    • Biodentine
      • It is similar to MTA in terms and properties
      • Shows potential for encouraging the healing process in the pulp
    • Calcium Hydroxide
      • Traditionally used to form dentin
      • Its alkaline pH can act as inflammatory stimuli for odontoblasts may lead to tertiary dentin, less organized and porous
• Root canal treatment is done when a large breach in the pulp occurs and pulp chamber is opened more than 1mm.

Classification of Caries Lesions (Black's classification)

• Class I: Posterior restoration contained within the occlusal surface.
• Class II: Posterior restoration including a proximal surface.
• Class III: Anterior restoration, including a proximal surface only.
• Class IV: Anterior incisal edge restoration.
• Class V: Buccal cervical surface restoration.

Modified ICDAS (mICDAS) scoring system (0-4)

• Links clinical appearance with the equivalent underlying lesion histology.
  • Images show teeth sectioned longitudinally through occluslal lesions, as representative clinical examples of each mICDAS score.
  • Clinical scoring system is useful for inclusion in the patient's notes, for monitoring, and for dento-legal purposes.
    • 0: No or slight change in enamel translucency following prolonged air drying (> 5 s), and no enamel demineralization or a narrow surface zone of opacity.
    • 1: Opacity or discoloration from the enamel (white spot lesion) hardly visible on a wet surface, but distinctly visible after air drying; enamel demineralization limited to outer 50%.
    • 2: Enamel opacity (white spot lesion) or greyish discoloration distinctly visible without need for air drying; demineralization involving inner 50% of enamel through to outer third of dentine.
    • 3: Localized enamel breakdown in opaque or discolored enamel, +/- greyish discoloration/shadowing from underlying dentine; demineralization involving the middle to inner third of dentine.
    • 4: Gross cavitation in opaque or discolored enamel exposing the underlying stained dentine demineralization involving inner third of dentine towards pulp.