RESTORATIONS
1. Consider the need for therapeutic agent
If the pulp or the dentinal tubules near the pulp are exposed to external stimuli (heat/ cold/ electricity), this can cause tooth sensitivity and pain. Furthermore, they can become exposed to harmful microbes causing infection. Hence, dentists may choose to protect and cover the pulp in a process known as pulp capping. It also aids in tertiary dentine formation and remineralisation of caries affected dentine.
Indirect pulp capping is when a therapeutic agent is applied onto a thin dentine barrier to seal the dentinal tubules. Only a spot is applied using a ball probe and adapted using a cotton pellet. Quick setting CaOH is recommended for indirect pulp capping. This has antimicrobial activity due to the low pH and it also aids in dissolving necrotic tissue remnants. It is also cost effective.
Direct pulp capping is when a therapeutic agent is applied over the pulp. MTA/ Biodentine is the material of choice over CaOH for direct pulp capping. It has greater marginal adaptation and higher success rate than CaOH. Moreover, tertiary dentine is homogeneous, tubular and has less cellular inclusions in MTA, as opposed to the more irregular, porous tertiary dentine with more cellular inclusions in CaOH. However, MTA with bismuth oxide is shown to cause colour change in the tooth. Hence, MTA containing bismuth oxide should be avoided. MTA can also contain zinc oxide eugenol.
Odontocem
Dycal
MTA
CaOH
2. Consider the need for LINER/ BASE
Another layer may be applied onto the axial and pulpal walls for pulp protection and to avoid post-operative sensitivity for deep restorations. It also provides stress relief during composite shrinkage; adequate cavity geometry and resistance for amalgam restoration.
For moderate cavity restoration (remaining dentine <1.5mm), there is the option of applying the GIC as a liner (0.5-1.0mm in thickness).
For deep cavity restorations, this is applied as a base (>1.0mm in thickness).
The material of choice are glass ionomer cements.
Fuji IX (GC)
Glass ionomer cement (chemical setting)
Mix a Fuji IX inside the machine.
Shake for 8 to 9 seconds.
Dispense into cavity.
Vitrebond (3M ESPE)
Fuji Bond LC (GC)
Fuji VII
Glass ionomer cements have the following benefits.
Chemical bonding
Fluoride release to remineralise caries - affected dentine
Biocompatibility
Coefficient of thermal expansion (CTE) close to dentine. This reduces the tension.
Chemical bonding to dentine reduces microleakage
Shown to extend longevity of the restoration
This is better than composite for moisure control so it can be used for subgingival restorations. However, remember to place GIC below the proximal contact of the adjacent tooth as it is prone to defects.
If recommended with specific GIC, apply a poly-acrylic acid conditioner with a micro-brush and a cotton pellet before its application. Rinse and dry the cavity subsequently.
Remove the smear layer (inorganic, organic debris, bacteria)
Expose dentine for chemical bonding
Create superficial porosity (<1 micron) for micro-mechanical interlocking
If using 20% poly-acrylic acid, apply for 10s. If using 10% poly-acrylic acid, apply for 20s. This is a semi-permanent, luting cement.
Alternatively, flowable composite can be considered. This low viscosity material blocks undercuts to improve adaptation in deep proximal boxes. It is then cured for 10 seconds. However, the more resin that is used, the greater decrease in biocompatibility. Flowable materials do not seem to improve clinical outcomes in terms of reducing micro-leakage.
The third option is a zing eugenol material. However, this is not frequently used anymore, as it adversely affects the polymerisation of adhesives and composite resin.
3. Choose a material for the final restoration
The final restoration is added after the liner/ base.
The material of choice is composite due to improved aesthetics. Before adding composite to the cavity, one can choose the following methods.
3 Step Etch and Rinse (Gold Standard)
Microbrush 37% phosphoric acid to agitate and etch the dentine and enamel for no more than 15s. Over etching can cause dehydration of the dentine collagen fibrils. Wash (rinse) for 20 seconds.
Dry with a cotton pellet and use high velocity suction or careful air-spray.
Microbrush a thin layer of primer to the cavity. Brush away excess first on the back of your glove. Use the back of your hand to ensure light air pressure before gentle air blow for 2 - 5 seconds and glossy surface. Furthermore, apply the bond. Repeat the drying step.
UV light to cure the cavity for 20 seconds minimum (if using ESPE).
Self - etch resin dentine bonding system
For occlusal fillings, the top needs to contain at least 1.5 - 2.0 mm thick of either universal composite or sculptable bulk composite to bear the occlusal forces.
For universal composite, remember to use the incremental technique and cure no more than 2 mm thick at a time. This reduces the C - factor, which refers to the number of bonded to unbonded surfaces. The less the C - factor, the smaller the risk of polymerisation shrinkage. In terms of the lowest to the highest C - factor, it is Class V, Class IV, Class III, Class II and finally Class I.
For sculptable bulk fill composite, the incremental technique does not apply but it does need to be cured every 4.0 -5.0 mm. If the cavity is deeper than 5.0mm, several layers will need to be cured. Place the thickest layer last to ensure enhanced curing. Cure for 20s. Remember not to use sculptable composite for cusp replacement in complex restorations.
Alternatively, restoration using amalgam can be considered.
This is long-lasting. When continual stress is applied to large occlusal fillings, this can cause flexion of the cusps and micro-cracks.
EMERGENCY APPOINTMENTS
Temporisation
Sometimes, the treatment cannot be completed within the same appointment. Hence, temporisation is used. This might be the case for deep caries which cannot be fixed within the same appointment or for endodontic treatment.
Short - Term Temporisation
For medium - term temporisation (up to 3 weeks)*, Cavit (zinc oxide sulphate) is used to fill the entire cavity. There are several brands available:
Pink (recommended) for increased hardness and bearing of occlusal load bearing forces
Grey: removable with hand instruments (spoon excavator) for temporisation of non load bearing areas
White increased adhesiveness for temporisation after endodontic treatment
Long Term Temporisation
For long term temporisation, there are glass ionomer alternatives which last longer which last weeks or months.
GIC- Fuji IX
RMGI - Riva
RMGI - Photac
Note that for all RMGI (resin modified glass ionomer), they will require light curing.
Another option is IRM (immediate restorative material.
This contains zinc eugenol oxide, contains oils, and is also a good seal and pain relief. It can last anywhere up to one year.
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