Dental desensitization in OCE

Dental desensitization in OCE

i-Dental anesthesia

I. Definitions:

1-Anesthesia:

The word anesthesia derives from a Greek word meaning “absence of the faculty of feeling.”

There are 3 types of anesthesia:

• Local anesthesia; Local anesthesia is the loss of sensitivity of a limited region obtained either by contact or by injection of an anesthetic solution, it acts directly on the nerve endings.
• Regional anesthesia: Regional anesthesia is anesthesia applied directly to a nerve trunk affecting a region. 
• General anesthesia: General anesthesia is a state similar to sleep, produced by the injection of medication, intravenously and/or by breathing anesthetic vapors, using an appropriate device.

2-Anesthetics:

Anesthetics are drugs (substances) intended to selectively and reversibly block nerve conduction.

II. Mode of action of local anesthetics:

• Calcium displacement theory

Local anesthesia is produced by the displacement of calcium from sites in the membrane that controlled sodium permeability. Studies have shown that varying calcium concentrations do not affect local anesthetic activity.

• Charged Surface Theory or Repulsion Theory 

Local anesthetic agents act by binding to the nerve membrane; and altering the electrical potential at the membrane surface. The electrical potential at the membrane surface becomes more positive, thereby reducing the excitability of the nerves by increasing the excitability threshold. The resting nerve membrane potential remains unchanged by local anesthetic agents, i.e., it does not become hyperpolarized. 

• Membrane expansion theory
    Local anesthetic molecules diffuse to hydrophobic regions of the excitable membrane causing expansion of critical regions of the nerve membrane; and thereby preventing an increase in sodium ion permeability
• Specific Receptor Theory
    This is the most favored theory today. Local anesthetic agents act by binding to specific receptors on sodium channels of the nerve membrane. Once bound, permeability to sodium ions is reduced or eliminated; and nerve conduction is interrupted.

III. Classification of local anesthetics 

• Based on presence in nature

1. natural, e.g. cocaine 2. Synthetic compounds: a. nitrogenous compounds   i. Para-aminobenzoic acid (PABA) derivatives   -Freely soluble, e.g. procaine o -Sparingly soluble, e.g. benzocaine   ii. Acetanilide derivatives, e.g. lidocaine (xylocaine)   iii. Quinolone derivatives, cinchocaine (nupercaine) iv. Acridine derivatives, e.g. bucricaine b. Non-nitrogenous compounds, e.g. benzyl alcohol, propanediol 








 

3. Various drugs with local anesthetic action, for example, clove oil, phenol, chlorpromazine, some antihistamines such as diphenhydramine.

• Based on the chemical structure
    1-esters
  These can be classified as:
    i. Benzoic acid esters, e.g., cocaine, benzocaine 

  ii. Esters of para-aminobenzoic acid, e.g. procaine, 

     2-Amides For example, articaine, bupivacaine, lidocaine, mepivacaine and prilocaine.   Based on duration of action a. Short acting: Articaine, lidocaine, mepivacaine, prilocaine, etc. b. Long acting: Bupivacaine, etidocaine, bucricaine, etc.

         

IV. Local anesthetics

• Properties of an ideal anesthetic: The ideal local anesthetic should possess the following properties:

1. Have a reversible action.

2. Cause no tissue irritation or local adverse reactions,

3. Possess low systemic toxicity.

4. Its anesthetic effect must manifest itself quickly and last sufficiently long. 5. Its power must be sufficient to provide complete anesthesia without requiring the use of high concentration solutions which could be dangerous.

6. Its diffusion must be sufficient to allow its effective use as a contact anesthetic.

7. It should cause almost no allergic reactions.

8. It must be stable in solution, but it must be easily metabolized in the body.

9. It must be sterile, or able to be sterilized by heat without deterioration of its molecule.

None of the local anesthetics currently available fully meet these conditions, particularly with regard to duration of action. 

• B. CHEMICAL STRUCTURE:

Common structural features:

a hydrophilic group and a lipophilic (or hydrophobic) group, separated by an intermediate chain.

-Hydrophilic pole = secondary or tertiary amine group

– Lipophilic pole = aromatic cycle

•The nature of the bond between this cycle and the intermediate chain makes it possible to define the 2 types:         AL with ester function and AL with amide function

• D. MAIN LOCAL ANESTHETICS:

Cocaine:

Anesthetic	properties
cocaine	-first local anesthetic found in Peru from the leaf of Erythroxylon coca -it is absorbed very quickly in the respiratory tract

Ester-functional local anesthetics:

Anesthetic:	Properties:
Procaine	Vasodilator short duration of action Rapid absorption Often associated with a vasoconstrictor can cause allergic accidents (cutaneous bronchospasms, anaphylactic shock)
Chloroprocaine	Halogenated derivative of procaine Hydrolyzed more rapidly than procaine Less toxic than procaine
Tetracaine	long duration of action More powerful than procaineIt has allergenic properties

Local anesthetics with amide function:

Anesthetic:	Properties:
Lidocaine	The anesthetic power is average and therefore a vasoconstrictor is often used to increase its power and duration of action.
Prilocaine	longer duration of action than lidocaine. Its metabolism is rapid, its toxicity is low.
Etidocaine	More fat soluble than lidocaine, more potent than lidocaine with a short onset of action, greater cardiotoxic effect than lidocaine
Mepivacaine	a duration of action slightly longer than lidocaineAl contraindicated in pregnant women
Articaine	less toxic for pregnant women (passes the placental barrier less), less fat-soluble, rapid elimination, more powerful than lidocaine, slightly longer duration of action.
Bupivacaine	Liposolubility is 10 times that of lidocaine. More potent than lidocaine and Mepivacaine, longer duration of action than lidocaine.
EMLA:	a mixture of prilocaine and lidocaine used only locally for children

Acridine and quinolone derivatives 

Anesthetic	properties
Centbucridine	It is used in the concentration of 0.5%. Its potency is 5-8 times that of lidocaine; with a rapid onset of action. It has a longer duration of action than lidocaine. It has a certain amount of inherent vasopressor activity. Its toxicity to the central nervous system and CVS is lower than that of lidocaine. It can be used in patients with allergy to lidocaine.

V. Vasoconstrictors

a. Definition:

They belong to the catecholamine family also called sympathomimetic amines. 

The vasoconstrictors used in dentistry are all synthesizable, although adrenaline and noradrenaline are naturally present in the body. 

b-Advantages:

1. By delaying the absorption of the local anesthetic, they reduce its toxicity.

2. By delaying the absorption of the local anesthetic, they prolong its duration of action.

3. By delaying the absorption of the local anesthetic, they allow the use of smaller volumes of anesthetic solution.

4. They therefore increase the effectiveness of the local anesthetic solution. 

c. The different types of Vaso-Constrictors:

• Adrenaline (epinephrine): This is the most powerful and effective vasoconstrictor agent associated with dental anesthetic solutions, 

• Concentrations of 1/100,000 (0.01 mg/ml) are used.
• Adrenaline has an influence on the cardiovascular system. 
• The greatest danger lies in injecting adrenaline directly into a blood vessel (hence the need to aspirate at the same time as the injection). 
• Noradrenaline (norepinephrine): 

• is the major amine; it constitutes approximately 15% of the amines contained in the adrenal medulla.
• Noradrenaline should be used with the same caution as adrenaline. It is recommended not to exceed a total dose of noradrenaline of 0.34 mg.
• Felypressin

•  It is available as a vasoconstrictor, in combination with prilocaine, 
• It is a non-sympathomimetic amine; and a synthetic analogue of vasopressin (antidiuretic hormone
•  It works by directly stimulating vascular smooth muscle
•  No direct effects on the myocardium.
• On the Uterus: It has two antidiuretic and oxytocic actions; hence its contraindication in pregnant women. 

d contraindications of vasoconstrictors associated with local anesthetic:

1- Pheochromocytoma: (tumor very rich in adrenaline and noradrenaline) constitutes an absolute contraindication for vasoconstrictors. Patients suffering from this condition must be treated in a hospital environment.

2-   Irradiated bone  : it seems desirable to avoid the association of vasoconstrictors with local anesthetic during conservative and especially non-conservative care on bone irradiated [beyond 40 GY].

 3- Arrhythmic patient: Intraosseous injections of local anesthetic + adrenaline should be avoided in arrhythmic patients.

4. patients with acute myocardial infarction less than 6 months 

5. patients with acute angina episodes 

6. Uncontrolled hypertension: PS >200mm Hg and PD>110mm Hg

7. Recent stroke (cerebral vascular accident): less than 6 months

VI. Materials 

1-Anesthesia syringes:

• A-Syringes without suction: made of chromed steel or stainless steel, they are robust and easily sterilized. They consist of 2 parts: a body and a piston.
• B-Syringes with suction:

Manual suction syringes: the ergo it presents sinks into the diaphragm of the cartridge and allows suction 

Self-aspirating syringes : once the pressure is released on the plunger, if the needle is in a vessel, the blood enters the syringe simply by venous arterial pressure

• c-Syringes for intra ligament anesthesia:

They can be presented in “gun” shapes and “pen” shapes.

• d-The “Jet injector” without needle

These injectors do not use a needle and are based on the principle that liquids or medications propelled under very high pressure can pass through intact skin or mucous membranes.

• e-Electronically controlled injection systems

It consists of a lightweight, sterile, single-use handpiece that is operated with a pencil grip and is connected to a small central unit that manages and controls the flow of the anesthetic solution. The injection is activated by a foot pedal.

• f-single-use syringes:

They are delivered in sterile packaging, allowing you to adapt the needle of your choice and use the analgesic solution adapted to the patient.

2- Needles:

Most dental needles are single-use, stainless steel, and silicone-coated. The needles consist of:

a- the rod, a hollow metal tube which has a bevel at one end, and whose diameter and length are variable,

b- a metal or plastic seal that attaches the needle to the syringe

3- Cartridges:

The contents of each cartridge include:

• An anesthetic agent or mixture of anesthetic agents
• A vasoconstrictor whose concentration per milliliter can vary. 
• Sufficient distilled water to obtain the desired volume of solution
• The volume of the cartridges is standardized at 1.8ml. 

VII. Oral anesthesia techniques 

1. Local contact anesthesia 

a- DEFINITION:

• Contact anesthesia is obtained by applying an anesthetic substance to a mucous membrane, providing relative and short-term insensitivity.

B- Indications

• Before infiltration techniques to anticipate a painful injection 
•  Before proceeding with the incision and drainage of an abscess
• Before suture removal.

C- Presentation: 

Spray: either in the form of lidocaine drops sprayed onto the surgical site or by refrigeration of methyl chloride gas.

Ointment: Application of lidocaine-based ointment to the area to be anesthetized  

 jet injection : This is a technique by which a small amount of local anesthetic is expelled as a jet into the submucosa without the use of a needle.

2. Infiltration anesthesia:

1. Periapical anesthesia :

Definition: It consists of depositing the anesthetic product in contact with the internal and external bone tables, at the apical region.

Technique: 

• Injection on the vestibular side: The oblique needle with bevel turned towards the bone, the infiltration point is located at the bottom of the vestibule opposite the apex in the loose mucosa
• First inject a few drops 
• Continue the injection until bone contact is reached and inject the largest amount of anesthetic solution (2/3 of the cartridge).
• Injection on the lingual or palatal side (1/3 remaining of the cartridge).
• On monorooted patients, anesthesia will be performed only on the vestibular side.

b- Regional anesthesia in the maxilla :

1. Anesthesia of the anterior and superior dental nerve (infraorbital foramen):

• Endobuccal technique (premolar approach): 

• The patient is positioned so that the maxillary occlusal plane is at a 45° angle to the roadway.
• The operator stands on the right side of a patient for the right side block
• Tissues at the injection site should be prepared with an antiseptic.

• The thumb of the hand should spread the upper lip and the index finger should locate the suborbital orifice and block any passage beyond the needle.
• A long needle is inserted into the bottom of the vestibule opposite the first premolar, a few drops of anesthesia are injected and then the needle is penetrated parallel to the axis of the premolar until it stops at a distance of 4-5 mm.
• Intraoral technique (Central incisor approach)
• The needle is inserted at the bottom of the vestibule and facing the canine, it must be oriented towards the central incisor so as to divide the vestibular face of the latter into 2 similar parts (disto-cervical towards mesio-occlusal) then the penetration of the needle is done in the same way as the previous technique  
• Exoral technique 

• The skin is smeared with an antiseptic solution
• The skin is anesthetized by infiltrating a few drops of anesthetic
• The needle is inserted in and down into the hole at a 45° angle  

2. Upper canine anesthesia

• consists of infiltrating the superior-anterior alveolar nerve before it gives off its dental filaments at the moment when it obliquely crosses the frontal process of the maxilla
• With the body of the syringe positioned parallel to the alveolar wall at the height of the first premolar, the needle penetrates from the bottom of the vestibule for 1.5 cm.
• This technique is completely painless and provides a long duration of analgesia for the incisor-canine block. 

3. Anesthesia of the posterior and superior dental nerve (retro-tuberosity):

• It is performed at the level of the posterior face of the tuberosity.
•  The patient is in a lying position with his mouth half open,
•  the needle enters the bottom of the vestibule at the level of the distal root of the 2nd molar, is inserted obliquely upwards and backwards and inwards without losing bone contact.
• The injection of the contents of a cartridge takes place throughout the journey; 

4. Nasopalatine nerve anesthesia 

• Labile approach 

•  The injection is made by inserting the needle into the intraseptal labial tissues between the maxillary central incisors (gingival papilla) 
•  The needle is inserted at a right angle to the vestibular cortex and passed into the tissues until resistance is felt.
• Palatal approach; The needle is inserted at the level of the retro-incisive papilla and directed upwards and backwards; injection of half a cartridge is sufficient.

5. Greater palatine nerve anesthesia: The palatine foramen is located opposite the space between the 2nd molar and the wisdom tooth. The injection is performed in the palatine depression.
6. Anesthesia of the maxillary dental nerve trunk

• Indications 

1. When anesthesia of the entire distribution of the maxillary nerve is required for extensive surgery.

2. When it is desirable to block all subdivisions of the maxillary nerve with a single needle insertion; and with a minimum of anesthetic.

3. infection, trauma, 

4. For diagnostic or therapeutic purposes, such as tics or neuralgia of the upper divisions of the fifth cranial nerve.

• Technical    

1. Cleaning the area with an antiseptic
2. Locating the middle of the zygomatic arch 
3. Marked the depression in its lower part  
4. Identification of the coronoid process by opening and closing movement of the mouth
5. Marked the needle with a silicone stop at a length of 4.5cm
6. The needle is inserted into the skin papule forward and slightly upward 

c- Regional anesthesia in the mandible :

1. SPIX’S spine technique

• The patient, placed in the supine position, is asked to keep his mouth wide open in order to stretch the pterygomandibular ligament.
• the pulp of the left thumb palpates the anterior edge of the ascending ramus and locates the coronoid notch
• First, the needle penetrates 8 to 10 mm above the level of the occlusal plane of the mandibular molars. We quickly come up against the retromolar triangle.
• *In a second step, the body of the syringe is moved towards the opposite canine in order to pass the temporal crest.
• *In a third step, the needle is inserted 15 mm, along the medial face of the branch and maintaining bone contact. Aspirate, then inject slowly.

2. GOW GATE Technique

• simultaneous anesthesia of the inferior dental nerve, buccal nerve and lingual nerve

1. Ask the patient to open his mouth very wide.

2. Using the thumb or finger, palpate the coronoid notch and slide it to the internal oblique crest.

3. Raise your thumb or finger about 10 mm.

4-Rotate the thumb or finger parallel to an imaginary line drawn from the corner of the mouth to the tragus of the ear on the same side.

5-Insert the needle at the height of the middle of the nail of the finger used to palpate until the bony contact.

6-Make sure that the body of the syringe rests on the contralateral premolars.

7. Make sure the syringe remains parallel to the imaginary line between the corner of the mouth and the tragus of the ear

8. Aspirate, then inject the entire contents of the cartridge.

3. Buccal nerve anesthesia:

The buccal nerve can be anesthetized by infiltration. The mucosa is pricked just above the vestibule near the 3rd molar

4. Mental nerve anesthesia:

• Block of this nerve is used in surgery of the lower lips and chin
• The needle is directed downward and outward and inserted 2 mm; injecting 0.5 to 1 mL is sufficient to block this nerve.

d- Complementary anesthesia :

• 1. Intra-diploic anesthesia (intraosseous or intracortical):

Purpose : This involves bringing the anesthetic product into direct contact with the teeth for a faster, more significant and less dangerous anesthetic effect. 

             Advantage : 

• painless, 
• with immediate effect, 
• has little or no effect on the surrounding soft tissues; these advantages are due to the fact that the anesthetic is deposited directly into the supporting tissues of the tooth.

  Disadvantages: 

-the duration of action is short.

-The relative difficulty of execution

– access is often difficult at the level of the mandibular molars

-the risks of root damage with drills

Indications : This technique can be used for all oral interventions; even when other types of anesthesia are contraindicated or unsuitable (interventions in severe haemophiliacs

• Technical:
• After a light gingival anesthesia if necessary…  
• Step 1: Perforate the cortex with the drill mounted on a contra-angle
• 2nd step: remove the drill bit while holding the hollow tube in place with tweezers 
• Step 3: Insert the needle into the hollow tube and inject the solution
• 2. Intra-septal anesthesia:

Same as intra-dental anesthesia except that the insertion point is located in the interdental septum  

• 3. Intrapulpal anesthesia:

Aim: 

• To deposit the anesthetic product directly into the pulp parenchyma, therefore immediate effect.
• This is sometimes the last resort to achieve operative silence in endodontics.

 Indications : 

It is indicated as a last resort, when other methods have failed.    

Technical:

 When the pulp ceiling is preserved, it is necessary to make a hole in the region presumed closest to the pulp using a small round burr and crimp the syringe needle into this hole before starting the injection at high pressure. 

    0.2 to 0.4 ml of solution is sufficient to control pain. The important factor of the technique is undoubtedly the injection under pressure, whenever there is a reflux of the solution, anesthesia is not obtained.

• 4. Intra-ligamentous anesthesia:

Definition: The goal of intraligamentous analgesia is to bring the solution to the level of the desmodontal space in order to obtain analgesia of the alveolus and the dental pulp.

Indications: 

• It will be used as a first-line treatment for localized conservative treatment of a maxillary tooth with divergent roots, the extraction of an isolated tooth or in patients taking anticoagulants.
• as a second-line treatment, in addition to regional infiltration, if the duration of the latter is insufficient.

Technique: This technique requires a special syringe, short and sturdy needles. The penetration is made vertically in the sulcus along the roots, the needle must travel into the desmodontal space and meet resistance there. 

• With each press of the syringe handle, 0.2 ml of solution is injected. The anesthesia lasts 30 minutes and gives good results in 85% of cases. 

 Contraindications:

• formal in periodontal diseases.
• They are relative in first intention for baby teeth and, for long-term care, on one tooth or care on several teeth of the molar group.
• In patients at high risk of infection 

ii-Dental desensitization by escharification

• It is a dental desensitization technique by using a mortifying agent in contact with the pulp, arsenic , which causes tissue hemorrhage leading to tissue death.
• This technique is abandoned because of the risk of arsenical rocket to the surrounding bone tissues and the arsenical osteitis that it can cause.    

  Untreated cavities can reach the nerve of the tooth.
Porcelain veneers restore a bright smile.
Misaligned teeth can cause headaches.
Preventative dental care avoids costly treatments.
Baby teeth serve as a guide for permanent teeth.
Fluoride mouthwash strengthens tooth enamel.
An annual checkup helps monitor oral health.
 

Dental desensitization in OCE