1 PAIN & HYPERSENSITIVITY. 2 1- Preoperative pain: 2- Pain during operative procedures (might persist post- operatively) 3- Postoperative pain 2 PAIN.

*PAIN & HYPERSENSITIVITY

*1- Preoperative pain:2- Pain during operative procedures (might persist post-operatively) 3- Postoperative pain

*PAIN by definition is an unpleasant sensation in response to a stimulus and is usually associated with a degree of tissue damage.

Causes of pain in the dental field: 1- Preoperative pain: - Dental caries and lesions causing destruction of hard tooth tissues strip dentin from its protective covering of enamel. Exposed dentin is highly sensitive to changes in temperature , changes in osmotic pressure and pressure from food.

- Exposed pulps cause an acute severe type of pain.

- Faulty restorations ( e.g. open proximal contacts, premature occlusal contacts .) can be the cause of pain.

2- Pain during operative procedures (might persist post-operatively) a- Pain of dentinal origin: Dentin is an innervated tissue that can convey insults to the pulp causing pain, through: - cutting in dentin during cavity preparation , esp. when heat is not controlled, causes movement of dentinal fluids inside the tubules which stimulates pain receptors in the plexus of nerves below the odontoblastic layer of the pulp. -

* excessive dryness with the chip syringe or during using ultra high speed ranges without coolant, might cause aspiration of odontoblastic processes inside the tubules, causing immediate and postoperative pain. - cutting along the DEJ &/or locating the floor of the cavity at this location (Metallic restoration) cause immediate and postoperative pain, because the DEJ is an area of anastomosis of a large numberof dentinal tubules with their nerve endings.

b-Pain of pulpal origin: The pulp contains the innervation of the tooth. The only response of the pulp to any stimulus is pain. c- Pain of gingival origin: - rubber dam clamps. - matrix bands. - wedges.

- injury to the interproximal gums during cutting the gingiva floor of proximal cavities.

*d- TMJ pain: - prolonged mouth opening in long appointments. - dentist exerting unnecessary pressure on the mandible.

- vibration as result of eccentricity of the bur ( heat generation ) - lack of proper support from the dentist ( accidental slipping of instruments and injuries ). - chemicals as strong disinfectants during the cavity toilet ( has become totally obsolete ). - acid etching and accidental contact with soft tissues causing a burning sensation. - cotton roll removal from the sulci ( has to be watered before removing it ). e- Iatrogenic: - forceful cheek retraction ( injury to angle of the mouth ). - improper use of hand instruments.

* - Avoiding of pain during operative procedures, through the use of LA does not necessarily indicate the absence of injury. - A certain amount of postoperative discomfort (hyperemia) is very common ,yet excessive acute pain may indicate irreversible pulpitis.3- Postoperative pain :

Dentinal pain is usually localized, mild and has to be initiated by a stimulus. It usually subsides upon removal of the stimulus and even if it persists for some time, it is never lancinating nor acute.

Pulpal pain is more difficult to localize. In hyperemia , it has to be Initiated by a stimulus and disappears shortly after removal of the stimulus, whereas in pulpitis, the pain is severe and lancinating,usually occurs spontaneously without any stimulation, increases atnight ,affects the whole of the affected side and might be referredto the opposing jaw.

Mechanism of dentinal sensation - Noxious stimuli stimulate the C-fibers in the pulp to produce dull, vague & unlocalized type of pain ( pulpal pain ). - Non-noxious stimuli stimulate dentinal pain (A-delta fibers). 1- Odontoblastic receptor theory: The odontoblastic processes act as sensory receptors and transmit sensory sensation through the odontoblasts to the underlying nerve endings in the cell free zone.

*2- Nerve ending theory: The sensory nerve endings migrate inside the dentinal tubules to evoke sensation.

*3- Hydrodynamic theory: Non- noxious stimuli ( e.g. tactile,thermal,osmotic) will cause movement of dentinal fluids and stimulation to A-delta nerve endings present in the odontoblasts causing sensation.

Factors causing dentinal hypersensitivity : 1- Increased depth & width of the cavity : The deeper the cavity is, the larger will be the number of exposed dentinal tubules leading to a more hypersensitivity.

*2- Pressure : through Rough probing, Premature contacts , Polymerization shrinkage of resins will cause a sudden inward movement of dentinal fluids and subsequent hypersensitivity.

*3- Osmotic pressure : through leakage around restorations or cracked teeth or restorations will cause the penetration of fluids

4- Thermal stimuli : From metallic restorations and leakage ,will cause expansion &/or contraction of dentinal fluids with subsequent hypersensitivity.

5- Galvanic stimuli : Dissimilar metallic restorations, having different electric potentials ,will set up an electrolytic reaction in the presence of saliva ( electrolyte ) when they become in contact causing hypersensitivity.

Clinical situations of post-operative hypersensitivity encountered in our daily practice : 1- Restorations with premature contacts : High spots will cause concentration of biting forces, leading to localized periodontitis and possible hypersensitivity. .

*2- Amalgam restorations : Microleakage due to: - lack of adequate condensation - lack of proper dentinal sealing with sealer or bonding system

Thermal conductivity is also ,frequently, met with amalgam restorations,especially when the cavity is deep and not lined nor based. 3- Composite restorations : Post-operative hypersensitivity is a common finding with recently placed, especially large ones. Uncontrolled polymerization shrinkage resulting from poor handling of the material is the main cause of this sensitivity.

*- Composite restorations : Post-operative hypersensitivity due to faulty bonding procedure.

4. Baradontalgia Pain occurring in association with reduced pressure due to expansion of air voids incorporated into the restoration during its application. Voids may be due to: - inadequate condensation - material pulling away from marginal area when carving bonded amalgam

5. Fractured Restoration It may escape unnoticed early after its placement but during mastication, fracture line opens up allowing ingress of micro-organisms and oral fluids eliciting pain.

Most commonly is the isthmus fracture due to: - sharp axio-pulpal line angles in Class II - marginal ridge left too high - incorrect occlusal embrasures form - improper matrix removal - improper carving

Fractured and dislodged amalgam restoration

Isthmus Fracture

6. Faulty occlusal and proximal relationships

Restoration left hightooth in traumatic occlusion tooth sensitive to biting pressure Open proximal contactfood impaction and gingival inflammation Overcontoured interproximal restoration pressure on gingival papilla, chronic inflammation and hyperplasia Overcontoured buccal and lingual restoration prevent oral hygiene measures

Soft tissue response to overhanged amalgam restoration

Soft tissue recovery after 2 weeks with a correctly contoured temporary restoration

Properly contoured amalgam restoration with favorable tissue response

7. Bleaching

Tooth sensitivity is a common side effect of external tooth bleaching.

Cervical root resorptionGingival irritation

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