1
Q
Peripheral Nerve Fiber Classification
Which subtype of Type A fibers is efferent; muscle tone?
A
A(gamma)
2
Q
How do you prevent Needle Breakage?
A
- use 25 g or 27 g needles
- Use long - 32mm needle for IA block
3
Q
What are the 2 Needle lengths used in Dentistry?
A
- Long - 32 mm
- Short - 20 mm
4
Q
Peripheral Nerve Fiber Classification
Which subtype of Type A fibers is afferent; proprioception, touch, pressure?
A
Type A(beta)
5
Q
What effect does Sodium bisulfite have on the LA?
A
- decrease solution pH = more acidic = delayed onset
6
Q
What is the relative refractory period due to?
A
hyperpolarization before RMP is established
7
Q
Peripheral Nerve Fiber Classification
Which subtype of Type A fibers is, the largest; fastest; efferent; muscle movement?
A
A(alpha)
8
Q
What are the 2 causes of Facial Paralysis?
A
- LA deposited in parotid gland
- bone not contacted during mandibular block
9
Q
What LA is not used for hemostasis?
A
Mepivacaine
10
Q
What is the MRD per appointment for Mepivacaine?
A
Adult = 400mg Child = 300mg
11
Q
What type of LA should you select if you need hemostasis?
A
- Epi ONLY (no levonordefrin)
- 1:50,000 best
- 1:100,000 is better than 1:200,000
12
Q
What is the Tx of Paresthesia?
A
- 3 wks to 3 months, possible 1 yr
13
Q
Acceptable RR for an Adult?
A
12-20
14
Q
What are the 3 causes of Edema?
A
- Trauma
- Contaminated Anesthetic
- Allergic rxn to LA/sodium bisulfite
15
Q
What is the absolute refractory period due to?
A
inactivation of Na+ channels during repolarization
16
Q
What is the onset time of Bupivacaine?
A
5-10 mins
17
Q
What are the symptoms of Allergic Reactions?
A
- Delayed Hypersensitivity = rash; itching
- Immediate Hypersensitivity = anaphylaxis
18
Q
What length of needle is ALWAYS required for a Mandibular Block?
A
Long - 32mm
19
Q
What concentration of Cetacaine is used?
A
- 14% Benzocaine
- 2% Butamben
- 2% Tetracaine
20
Q
What is the mechanism of action of Topical Anesthetics?
A
- dec Na+ ion permeability = dec depolarization = blocks nerve impulse
21
Q
Relative Contraindications of LAs (6)
A
- H2-receptor blockers
- Beta Blockers
- CNS Depressants
- Pregnancy
- Significant Liver Ds
- Renal Dysfunction
22
Q
How do you prevent a Hematoma?
A
- Use 27g short - 20mm needle for PSA
23
Q
What effect does a Vasoconstrictor in LA have on Duration = Potency?
A
dec BF = inc Duration = inc Potency
24
Q
Acceptable HR for a Child?
A
75-100
25
What is the MRD per appointment for Bupivacaine?
Adult = 90mg Child = 90mg
26
What is the onset time for Lidocaine?
2-3 mins
27
What Amide LA's are metabolized in the Liver ONLY (inc toxicity in liver ds)?
* Lidocaine
* Mepivacaine
* Bupivacaine
28
What 3 factors affect the duraction of LA = Potency?
1. Protein binding of specific LA
2. Vascularity of injection site
3. Vasoconstrictor in LA
29
_Peripheral Nerve Fiber Classification_
* Largest fibers = fastest impulse conduction
* Myelinated
* Afferent or Efferent
Type A Fibers
30
What is the weakest part of the needle?
Hub + Needle Adaptor (1 piece)
31
What size of nerve fibers are MORE sensitive to LAs?
Small diameter
32
Which Amide is the most potent vasodilator?
Bupivacaine
33
What is the effect of inc protein binding of molecules on LA?
inc duration
34
What are the symptoms of Syncope?
* Sweating; nausea, pallor
* inc HR and inc RR
35
What is the duration of topical lidocaine?
15-45 min
36
What vasoconstrictor should be used if the pt is taking tricyclic anti-depressants?
* 0.04mg Epi
* No Levo
37
_Peripheral Nerve Fiber Classification_
## Footnote
Which subtype of Type A fibers is afferent; PAIN; temperature?
A(delta)
38
What is the duration of action of 4% Prilocaine 1:200,000 epi?
60-90 mins
39
What LA is a good choice for readministration, CV ds, and Liver ds pts?
Articaine
40
What is a good choice if a vasoconstrictor is contraindicated?
Mepivacaine
41
What Amide LA's are metabolized in Liver + Lungs (shorter 1/2 life due to lungs)?
Prilocaine
42
What causes the rapid onset of Nitrous Sedation?
low solubility in blood
43
What Pregnancy Category is Mepivacaine, and is it safe for lactation?
* Category C
* Lactation Safe
44
What is the duration of Cetacaine?
30-60 min
45
How do LA's stabilize the membrane?
Decreases the rate of depolarization; membrane remains polarized
46
What is another name for Benzocaine?
Hurricaine
47
What is the most common cause of a Hematoma?
* Entering the venous Pterygoid Plexus when giving a PSA block
Remember to use a short 20mm, 27g needle @ 45 angles to long axis of tooth and to alveolar bone
48
Is Cetacaine and Ester or Amide?
Ester
49
Which LA is the best choice for long tx and post-op pain control?
Bupivacaine
50
What is the MRD per appointment for Prilocaine?
Adult = 400mg Child = 400 mg
51
What size of nerve fibers require MORE volume of LAs?
Large diameter
52
What Topical Anesthetic is a good choice for thoose allergic to esters?
Lidocaine
53
What is the **active** form of the drug that canNOT cross the membrane?
* RNH+ = cations (acid)
54
Amide LA's are combined with an acid to form what?
HCl Salt = water soluble = stable injectable solution
55
What is the Tx of Trismus?
* 2-3 days
* moist heat (20 min on/ 20 min off)
56
What are the symptoms of Epi Overdose?
* Fight or Flight response - lasts 5-10 mins
57
What is the primary factor associated with the Induction (diffusion of molecules across membrane) of LA's?
* Initial concentration
* inc conc = inc diffusion = rapid onset
58
How does an **inc pKa** = inc cations = dec base affect the diffusion across the membrane?
Slower onset = slow diffusions
59
What LA's are Long-Acting (90min or \> pulpal anesthesia)?
* 0.5% Bupivacaine 1:200,000
60
What is the Tx for Allergic Rxns?
* **Delayed** = antihistamine, and document
* **Immediate** life-threatening Anaphylaxis
* Stabilize pt
* Activate EMS
* Document
61
What level of LA's shows initial CNS Stimulation (inc HR, RR, and BP, muscle twitching, tremors)?
Moderate Overdose of LA's
62
What is the Tx for Epi Overdose?
* Healthy Pts = reassure
* CV Pts = prepare for medical emergency
63
What is the duration of action of Prilocaine without epi (4% Prilocaine Plain)?
40-60 mins
64
What is the tx for Hematoma?
* Apply ice/pressure immediately
* inform pt of swelling/discoloration 7-14 days
65
What is the primary excretory organ for all LA's?
Kidney
66
What is the Tx for Infection?
* Antibiotics after 3 days
67
What level of LA's shows CNS Depression, due to vasodilation (dec HR, RR, and BP, convulsions, unconsciousness, progresses to resp arrest)?
High Overdose of LA's
68
What Pregnancy Category is Articaine, and is lactation safe?
* Category B
* Unknow Lactation Safety
69
How much nerve length must an LA penetrate to block a nerve impulse?
8-10mm (3-4 nodes of Ranvier)
70
At what BP range should you retake; refer for med consult before tx?
160-199/95-114
71
What pregancy category is Bupivacaine, and is it safe for lactation?
* Category C
* Unknown Lactation Safety
72
In the reinjection of LA, if nerve fibers are fully recovered (no numbness) what occurs?
**Tachyphylaxis** = tolerance to LA = LA is ineffective
73
Which LA's are effective topicals?
* Lidocaine
* Prilocaine
74
LA's provide what between the source of impulse and the brain so that the impulse never reaches the brain?
Chemical Block
75
_Peripheral Nerve Fiber Classification_
* **Smallest** & unmyelinated
* **Most numerous**
* Afferent & Efferent
* **Post-ganglionic ANS**; temperature; PAIN
* Dull, achy pain
Type C Fibers
76
Other name for Lidocaine
Xylocaine
77
How does a **dec pKa** = inc anions = inc base, affect the diffusion across the membrane?
Rapid onset = fast diffusion
78
What do Type A fibers require more of?
MORE anesthetic Volume
79
What are the 3 common Topical Anesthetics used in Dentistry?
1. Benzocaine
2. Lidocaine
3. Cetacaine (Benzocaine + Butamben + Tetracaine)
80
What needle is used for Greater Palatine Blocks, and how are they performed?
* 27g needle
* insertion until bevel is buried ~1/4''
* Use 1/4 carpule = 0.25cc or until tissue blanches
81
What is the onset time for Prilocaine?
2 mins
82
What is the duration of action of Mepivacaine without epi (3% Mepivacaine)?
20-40 mins
83
What is the onset time of Mepivacaine?
1.5-2 mins
84
What effect does stronger protein binding have on the duration = potency of specifc LA?
stronger binding = inc Duration = inc Potency
85
What Amide LA's are metabolized 90% in Plasma and 10% in Liver?
Articaine
86
What is the affect of inc vasodilation of LA?
dec potency + dec duration = inc dose needed
87
What are the primary and secondary factors associated with the Onset of Action of LA's?
* dec pKa = rapid onset
* small diameter nerves = rapid onset
88
What is the duration of action of 2% Mepivacaine 1:20,000 levo?
60 mins
89
What 5 things are included in the contents of the carpule?
1. LA durg
2. Sodium hydroxide
3. Sodium chloride
4. Vasocontriction = Epi or Levonordefrin
5. Vasoconstrictor preservative = Sodium bisulfite (allergic rxns)
90
What concentration of Benzocaine is most commonly used?
20%
91
What are the 4 causes of Paresthesia?
1. Trauma to nerve sheath (pt feels a "shock")
2. Edema/hemorrhage near nerve
3. Contaminated Anesthetic
4. Possible association with **Articaine**
92
If nerve fibers are only partially recovered (pt still numb) for the Reinjection of LA what would be effective?
Small volume is effective with Rapid Onset
93
3 Causes of EPi Overdose?
1. 1:50,000 concentration
2. Intravascular injection
3. CV pts
94
How far into the tissue should the needle be for a mandibular block?
* 1 inch
* 2/3 to 3/4 length of long -32mm needle
95
What is the primary factor for the Recovery from LA Block (reversal of LA action)?
Degree of binding to receptor site
96
What are the symptoms of LA Overdose?
* Low Overdose = CNS Excitation
* Higher Overdose = CNS and CV Depression
97
What 4 factors increase Absorption of LA (inc risk of systemic toxicity)?
1. Total Dose Administed (inc dose)
2. LA concentration (inc conc)
3. Route of Admin (topical)
4. Vascularity of Admin site (intravascular injection)
98
Acceptable RR for a Child?
18-30
99
In Topical Anesthetics there is an association between Benzocaine Sprays and what?
Methemoglobinemia
100
In the Depolarization of the Membrane, what does the threshold (+15-20mV) stimulus trigger?
* Ca+ & Na+ ion channels to open
* Na+ ions flow INTO neuron = inside becomes + charged
101
At what BP range should you consider N2O for stress reduction?
140-159/90-94
102
Other name for Mepivacaine
Carbocaine
103
What are the 5 Absolute Contraindications for Nitrous Oxide Sedation?
1. Nasal Obstruction
2. Vit B12 Def
3. Alcoholic/Recovering Addict
4. Uncommunicative
5. Patient Refusal
104
What LA's are Short-Acting (30 min pulpal anesthesia)?
* 3% Mepivacaine - plain
* 4% Prilocaine - plain
105
What are the Topical Ester LA's?
* Benzocaine
* Tetracaine
* Procaine
106
What is the duration of action of 4% Articaine 1:200,00 epi?
45-60 mins
107
Other name for Prilocaine
Citanest
108
What LA should be used for pts with Significant Liver Ds?
Articaine
109
What is the effect of Infection of LA's?
Inadequate Anesthesia
110
What LA has the shortest half life?
Articaine
111
What is the onset of Topical Lidocaine?
2-10 min
112
Is Benzocaine and Ester or Amide?
Ester
113
What is the effect of increased concentration of LA?
Inc diffusion through membrane = Rapid onset
114
What CV effects occur with a Mild Overdose of LA's?
slight inc BP, inc HR, inc RR
115
What is the Tx for Edema?
* NONE
* Resolves within 3-4 days
116
How do neurons maintain RMP polarization?
1. Na/K Pump
2. OPEN K+ channels
3. CLOSED Na+ channels
117
Acceptable HR for a Toddler?
120-160
118
What is the inactive, lipid soluble form of the drug that crosses the membrane?
RN = anions (base)
119
What do Topical LA require?
* Increased concentrations (needed to penetrate mucosa)
* Increased Toxicity
120
What level of LA's shows no CNS effects; may have anti-convulsant properties?
Low blood levels of LA's
121
What are the 3 causes of Allergic Rxns?
Hypersensitivity Rxn to:
1. Methylparaben
2. Sodium bisulfite
3. ester topical
122
What Pregnancy Category is Lidocaine, and is it safe for lactation?
* Category B
* Lactation Safe
123
What is the cause of Syncope?
* Drastic drop in BP
* Emotional Response (to injection)
124
_Peripheral Nerve Fiber Classification_
* Slightly myelinated
* Efferent
* Preganglionic ANS; vascular smooth muscle
Type B Fibers
125
What is the onset time for Articaine?
1-3 mins
126
Acceptable HR for an Adult?
60-100
127
What is the duration of Benzocaine?
5-15 mins
128
Prior to 1984 what was added to LA solutions without Epi?
Methylparaben (allergy)
129
Overdose of vasoconstrictors usually occurs via
Intravascular injection
130
What is the duration of action of 0.5% Bupivacaine 1:200,000 epi?
1.5-3 hrs
131
What factor decreases absorption of LA?
increased vasoconstrictor
132
What is the effect of increased Lipid solubility on LA's?
* inc Potency = dec dose needed
* inc diffusion through membrane = Rapid onset
133
What is the MRD of Topical Lidocaine?
200 mg
134
What CV effects occur with a High Overdose of LA's?
CV Depression (dec HR, RR, and BP, slurred speach, disorientation, unconsciousness, progress to Cardiac Arrest)
135
What are the Absolute Contraindications to LA's?
Allergy
136
What LA is highly lipid soluble and has high diffusion through bone?
Articaine
137
What is the least toxic LA in dentistry?
Prilocaine
138
What are the 8 Absolute Contraindications for Vasoconstrictors?
1. MI/Coronary Bypass surgery within 3-6 months
2. Uncontrolled Hypertension
3. Uncontrolled Angina Pectoris
4. Uncontrolled Arrhythmias
5. Uncontrolled Hyperthyroidism
6. Sulfite allergy
7. Glaucoma
8. Cocaine/Meth Use
139
What is the MRD per appointment for Articaine?
Child = 500mg
140
What gauge needle is the safe choice in high risk areas?
25 g (large diameter) provides reliable aspiration
141
What is the MRD per appointment for Lidocaine?
Adult = 500mg Child = 300mg
142
How does LA prevent Na+ ions from moving inside the cell?
LA's bind to Na+ channels inside the cell, preventing them from opening
143
What LA is the best choice for pregnant and CV pts?
Prilocaine
144
Acceptable RR for a Toddler?
25-32
145
What are the 3 needle gauge sizes used for intraoral injections?
1. 25 g
2. 27 g
3. 30 g
146
What LAs should be used if pregnant?
* Prilocaine or Lidocaine
147
At what BP range should you retake; refer for immediate med consult?
\>200/\>115
148
What does Repolarization of the membrane begin with?
* Movement of K+ ions to OUTSIDE
* Na/K pump moves Na+ ions to OUTSIDE = restores RMP
149
What Pregnancy Category is Prilocaine, and is lactation safe?
* Category B
* Unknown Lactation Safety
150
What is the onset of Cetacaine?
30 sec
151
Other name for Bupivacaine
Marcaine
152
What is most commonly used in dentistry for nerve block?
Lidocaine
153
What CV effects occur with a Moderate Overdose of LA's?
initial CV Stimulation (inc HR, inc RR, inc RR, headache, lethargy)
154
* Which LA is the most potent and most toxic LA used in dentistry
* Highly lipid soluble and binds strongly
Bupivacaine
155
What concentration of Topical Lidocaine is used?
2-5%
156
Other name for Articane
Septocaine
157
What are the 4 functions of Vasoconstrictors in LA's?
1. Constrict bv's = dec Dose of LA
2. inc Duration of LA x6
3. Hemostatis
4. dec Absorption rate of LA = dec risk of Toxicity
158
What is the MRD of Cetacaine?
200 mg
159
What effect does an increased vascularity of the injection site have on the Duration = Potency of LA?
inc vascularity = dec Duration = dec Potency
160
What is the duration of action of 4% Articaine 1:100,00 epi?
60-75 mins
161
What is the onset of Benzocaine?
Rapid onset = 30sec - 2mins
Pain & Anxiety
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