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Maxillary Anesthesia I: Pulpal Anesthesia

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252

● Needle orientation and course. ⚪ Tilt the tip of the needle inward (the syringe tilts outward),

theoretically forming an angle of around 30–45° relative to the sagittal or medial plane to keep it flush against the posterior wall of the maxilla (Figure14.12). The tilt angle must be wider, up to 70°, in children (Hayden1965).

⚪ Advance the needle upward, inward, and slightly rear-

ward, trying to keep as close as possible to the bone without tearing the periosteum. That precaution normally (but not always) protects the pterygoid plexus vessels and the posterior superior alveolar artery from puncture (DuBrul1988).

⚪ If resistance is encountered (because the needle hits

bone), draw the needle back slightly, narrow the angle of the inward tilt, and continue.

● Insertion length (Figure14.13). ⚪ Insert the needle 15–20 mm on average (Loetscher

etal.1988; Pfeil etal.2010). Remember that the deeper the needle, the greater the risk of injuring a vessel and causing hematomas. In children with mixed dentition, insert the needle 10–15 mm (Maljaei etal.2017).

⚪ Remember as well that the posterior superior alveolar

nerve has one to four branches (Jones 1939;

McDaniel 1956; Heasman 1984) that in most individuals lie less than 30 mm from the lower part of the maxillary tuberosity and only rarely higher (maximum 40 distance the 3–12

mm) (Heasman1984). Subtracting from that

mm between the roof of the buccal cavity and the gingival margin in molars (Jorgensen1948) and given that the anesthetic diffuses there, an insertion 15–20 3–12

mm for the roof, total 18–32 mm) deep should

mm (15–20 mm plus the

ensure an effective block.

● Aspire before injecting. Aspiration is positive in 5% of

cases (Annex 22).

● Inject 1.8 ml (one full cartridge) slowly, over the course

of 40–60

seconds. Injecting two cartridges (3.6 ml) yields better results and increases the duration of pulpal anesthesia (Pfeil etal.2010). Inject 1

ml in children with mixed dentition (Hayden 1965: Maljaei etal.2017).

● Subjective symptoms of anesthesia. Soft tissue anesthe-

sia, defined by patients as dullness, numbing, tingling, tickling or “fattening” sensation in the lip (Table13.1, Chapter13), appears after 2–3

⚪ Tests with a 15–20- minute wait (Loetscher etal.1988;

minutes.

Pfeil etal.2010) report better results than those with a 5- minute wait (Padhye et al. 2011). A compromise might be a waiting period of 5–10

minutes after injec-

tion to enable the anesthetic solution to take full effect.

⚪ Optionally some clinicians insert a probe in the buccal

mucosa around the molars to determine soft tissue anesthesia.

⚪ The definitive sign of efficacy is obtained by working

on the molars (i.e. prepping into dentin), initially cautiously and then proceeding normally if the patient expresses no discomfort.

● Soft tissue anesthesia usually lasts 3–4 hours (200 min-

utes), a fact of which the patient should be notified after treatment.

Figure14.13 Needle height necessary to block the posterior

superior alveolar nerve.

Efficacy ofthis Technique

When assessed with an electrical pulp tester or dry ice (at

−78°C), pulpal anesthesia is successful in 90% of maxillary molars, but in only 25–50% of premolars (Table 14.3). Similar results (around 90%) are reported for children with mixed dentition for the first permanent and second primary molars, although the success rate drops to 65% in the first primary molar (Hayden1965) (assessed with the less rigorous extraction method). As the preceding values are referred to the standard local anesthetic, 2% lidocaine, 1:100 000 (10 μg/ml) epinephrine (L- 100), use of a more powerful solution such as articaine (A- 100) would be expected to improve the results.

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Table14.3 Successful (%) pulpal anesthesia withposterior

superior alveolar nerve block (−78 tester assessment andstandard solution L-

Variable

Tooth Second molar (%) 96 97 100

First molar (%) 88 77 84 Second premolar (%) 31 45 68 First premolar (%) 10 10 32

Amount injected (ml) 1.2 1.8 3.6 Stimulus Cold

L- 100 → 2% lidocaine + 1:100 000 (10 μg/ml) epinephrine.

°C dry ice or electrical pulp

Loetscher

etal. (1988) n=45–56

°C)

(−78

100)

Pfeil

(2010) n=31

Electrical Electrical

Pfeil

(2010) n=31

Complications Specific tothis Technique

1) Extraoral hematomas may appear on the face in less

than 0.5% of cases (further to the Kuster and Udin1984; Loetscher etal.1988; Pfeil etal.2010; Padhye etal.2011 series). They occur when the needle pierces a vein in the pterygoid plexus or the buccogingival branches of the posterior superior alveolar artery that course somewhat erratically near the maxillary tuberosity (Harn etal.2002; Padhye et al.2011). They may present with swelling in the malar or superior masseteric region. Swelling appears earlier if an artery rather than a venous plexus vein is injured. In both cases the symptom is a dark brown spot on the skin due to blood extravasation (ecchymosis) that in the next few days spreads forward and downward along the muscular planes of the cheek, while changing to a purplepainless, causing no discomfort through the 10–15

yellowish hue. The process is

days

it takes to reabsorb the spot.

2) Acute trismus, with the inability to open the mouth par-

tially or wholly, normally a painful process sensitive to exploration at the insertion site. The cause is needle penetration in the lateral (external) pterygoid muscle, inducing irritation and spasms (Kramer and Mitton 1973; Stone and Kaban 1979). This complication, which may appear in less than 0.5% of cases (further to the Kuster and Udin1984; Loetscher etal.1988; Pfeil etal.2010; Padhye etal.2011 series), can be treated as described in Chapter22.

● It is identical to buccal infiltration at the second maxillary

molar behind the zygomatic osseous crest of the malar bone except that the needle runs a distance of around

mm instead of 2–3 mm to pass over the buccinator

muscle insertion.

● A 1.8- ml cartridge is injected, forming a sort of subcuta-

neous blister immediately over the buccinator muscle in the molar buccal cavity. The blister should be pushed backward, upward, and inward with the fingertip. This operation is easier if the patient’s mouth is completely closed (Figure14.5).

This procedure facilitates diffusion of the anesthetic solution toward the molar apices as well as toward the upper posterior part of the maxilla, i.e. toward the posterior superior alveolar nerve branches before they course into the foramina in the tuberosity.

The success rate, assessed in extractions only (rather than with the more rigorous electrical pulp tester), comes to nearly 100% in molars and nearly 90% in premolars with the standard lidocaine solution (L-

80) (Adatia1976).

High Tuberosity Approach

This technique aims to block the maxillary nerve (V2), the second division of the trigeminal nerve, within the pterygopalatine fossa, numbing a wide area by anesthetizing all its branches at once.

It is known as high tuberosity because the tuberosity approach (without “high”) is a synonym for PSA nerve block. Here the needle must travel further (higher) into the pterygopalatine fossa, hence the name. Other synonyms for this approach are posterior infraorbital approach because it is like infraorbital block but posterior, or Smith’s technique because it was developed by Dr. Arthur Ervin Smith of Chicago around 1913 (Smith1920).

This is a difficult technique because it is highly arbitrary because of the lack of osseous references to guide the needle during injection. It calls for introducing the needle higher and at a wider angle to avoid the posterior wall of the maxilla (tuberosity) and reach the pterygopalatine fossa (Figure14.1). That raises the risk of hematomas due to puncture of pterygoid plexus veins or branches of the posterior superior alveolar artery. It is also one of the most painful techniques (Annex 23).

Modified Adatia Technique

In 1968, Adatia (1968) introduced a simple method that prevents the risk of hematomas and swelling (Adatia1974,1976).

Uses

As noted earlier, the most common technique in the upper arch is buccal infiltration anesthesia, although on occasion a more powerful anesthetic effect is required, as in the following examples.

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254

1) Lengthy oral surgery in the maxillary zone because the

high tuberosity approach covers a larger area with less anesthetic and fewer injections.

2) After buccal infiltration failure, particularly in the

molar zone.

Zone Anesthetized

Theoretically the technique would affect the entire area innervated by the second division of the trigeminal nerve, the maxillary nerve (V

● Teeth, including pulp and periodontium of molars and pre-

), including the following.

molars on the side injected. Whilst incisors and canines may be anesthetized, as they are contralaterally cross-

innervated,

they may require reinforcement via buccal infiltration.

● Buccal cavity, including fibromucosa (alveolar mucosa,

gingiva, and interdental papillae), bone, and periosteum around molars and premolars. As discussed earlier, the anterior teeth are often contralaterally cross-

innervated. On occasion the upper area in the roof of the buccal cavity at the first maxillary molar may require supplementary infiltration, as it may be innervated by a branch of the ophthalmic nerve (first division of the trigeminal nerve) (Saborido1977).

● Palate, including the fibromucosa, bone, and periosteum

of the entire hemicontralaterally cross-

arch except the anterior part, which is

innervated by the nasopalatine

nerve (Saborido1977).

● Maxillary sinus on the side injected.

● Terminal branches of the infraorbital nerve that inner-

vate the upper half-

lip, the nasi ala, and the lower eyelid

on the side injected.

Technique

● Long (42 mm), 27G or (preferably) 25G needle. In

patients with small mouths or where a high angle is needed (see below), the needle should be bent at a 30–45° angle several millimeters ahead of the cone or hub to facilitate needle progress along the posterior wall of the maxilla. Note that the needle is not bent at the hub itself because as this is the weakest part it might readily break.

● Dentist’s and patient’s positions. ⚪ Dentist at 9:00–10:00 o’clock. ⚪ Patient in supine position with head slightly hyperex-

tended to enable the dentist to turn it slightly to the left to anesthetize the right side or to the right to anesthetize the left side.

● Advise the patient that during injection they may experi-

ence (i) heart palpitations (up to 30% of individuals in some series; Forloine etal.2010) due to the use of epinephrine solutions and (ii) temporary ocular and visual alterations (up to 10–15% of individuals) (Table14.4).

● Determine the depth of the needle (Jorgensen 1948;

Hayden1965).

⚪ The height of the posterior maxilla or distance the nee-

dle should travel may vary from 30 to 50

mm (Jorgensen 1948), and although the normal range is 30–40 mm with a mean of around 35 mm (Broering etal. 2009; Forloine etal. 2010), the distance must be individually estimated. One fairly reliable procedure is to measure the height of the anterior maxilla from the first maxillary premolar gingival margin to the edge of the inferior orbit because in 90% of individuals this is practically the same distance as the height of the posterior maxilla. The latter is 4–6 mm higher in only 5% of

Table14.4 Successful (%) pulpal anesthesia after thehigh tuberosity approach (electrical pulp tester assessment and3.6 ml

ofstandard solution L- 100): percentage ofocular complications andlower lip anesthesia

Variable

Tooth Second molar (%) 100 100 98

Lower lip anesthesia (%) — 2 32 Ocular complications Diplopia (%) — 10 12–16

Broering etal. (1991) n=40

First molar (%) 78 95 92 Second premolar (%) 52 73 76 First premolar (%) 30 52 58 Canine (%) 22 32 54 Lateral incisor (%) 4 18 8 Central incisor (%) 4 5 10

Blurred vision (%) — 5 0 Mydriasis (%) — 2 0

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Broering etal. (2009) n=40

Forloine etal. (2010) n=50

High Tuberosity Approach 255

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individuals, in which case the needle may not be inserted high enough, and 1–3

mm lower in the other 5%, leading to an overly high insertion site (Jorgensen1948). Only in the presence of open anterior bite is the height of the posterior maxilla 2–9

mm lower than the anterior (90% of individuals affected), raising the risk of overestimating the desired height (Jorgensen1948).

⚪ The height of the anterior maxilla is measured along

the face with a dental caliper from the first premolar gingival margin to immediately below the infraorbital bone margin, taking care not to accidentally injure the eye and marking the distance with a rubber stop on the needle to prevent over-

● Examine the entire roof of the buccal cavity over the maxil-

lary molars with the non-

insertion (Hayden1965).

injection index finger to locate the osseous bridge that protrudes from the zygomatic crest on the malar bone (normally alongside the first maxillary molar).

● Pull the labial commissure outward and upward with the

non-

injection hand to firmly stretch the jugal mucosa

(Figure4.12).

⚪ Stretch the tissue intraorally with the index finger on

the right side and the thumb on the left.

⚪ The aim is to (i) bring the concavity of the buccal cav-

ity around the molars into view and (ii) reduce any injection- induced pain by inserting the needle in a tense mucosa.

● Increase the space for maneuvering in the mouth. ⚪ Ask the patient to partially close their mouth to enlarge

the workspace, which (i) broadens the labial commissure and (ii) shifts the coronoid apophysis of the mandible rearward to prevent it from taking up space and getting in the way (Figure14.5).

⚪ If despite the foregoing the space is insufficient, ask

the patient to shift their mandible toward the side to be injected to increase the separation between the ascending ramus of the mandible and the posterior maxilla (Sicher1950).

● Insert the needle in the roof of the buccal cavity. ⚪ Behind the zygomatic crest of the malar bone, which is

usually the same as saying behind the second or third molar.

⚪ Point the needle upward and as perpendicularly as

possible to the molar occlusal plane. As a full 90° angle is not possible due to the presence of the jugal mucosa, the needle should be rearwardly oblique, which is also desirable.

⚪ Avoid the osseous wall to prevent the needle from hit-

ting or catching in the surface of the maxillary tuberosity (outer and posterior wall of the maxilla).

⚪ Push the needle a few millimeters into the buc-

cal cavity.

● Needle re- orientation and course. ⚪ Tilt the tip of the needle inward (the syringe tilts out-

ward), theoretically forming an angle of around 30–45° relative to the sagittal or medial plane to keep it flush against the posterior wall of the maxilla (Figure14.12).

⚪ Push the needle upward, inward, and slightly rearward,

trying to keep as close as possible to the bone without tearing the periosteum. That protects the pterygoid plexus veins, the posterior superior alveolar artery, Bichat’s fat pads, and the lateral (external) pterygoid muscle from puncture. Note that it is not always possible to avoid impacting the vessels in this zone (Sicher1950).

⚪ If resistance is met (because the needle hits bone),

withdraw the needle slightly, re-

enter at a less inward

angle, and continue.

⚪ Needle progress is interrupted when the rubber stop

(used to mark the insertion length) reaches the second and third molar CEJ or gingival margin. Remember that the mucosa at the roof of the buccal cavity is not a good reference because its depth may vary from 3 to 12 mm (Jorgensen1948).

● Aspire before injecting. Aspiration is positive in 13% of

cases (Goldman and Gray1963).

● Inject the full 1.8- ml cartridge over the course of

40–60

seconds, after which the entire operation is

repeated to inject a second cartridge, for a total of 3.6

ml. Many authors deem a single cartridge to be insufficient because as the tip of the needle does not reach but merely comes close to the pterygopalatine fossa (where the maxillary nerve lies), the anesthetic solution must diffuse across a longer distance to bathe the nerve (Smith1920; Collon1946; Jorgensen1948; Forloine etal.2010).

● Subjective symptoms of soft tissue anesthesia appear in

3–5

minutes with patients describing tickling, tingling, or numbing (Table13.1, Chapter13) at the injection site and (i) the lower eyelid, nasi ala and half of the upper lip and (ii) the half of the palate on the side injected.

⚪ Wait 5–10 minutes after injection to allow the anesthetic

to take effect and anesthetize the pulp of maxillary molars and premolars. Note that this approach takes a little more time.

⚪ Optionally some clinicians insert a probe in the buccal

mucosa around the molars to determine soft tissue anesthesia.

⚪ The definitive sign of efficacy is obtained by working

on the molars (i.e. prepping into dentin), initially cautiously and then proceeding normally if the patient expresses no discomfort.

● Soft tissue anesthesia usually lasts 3–4 hours (200 minutes),

a fact which the patient should be notified of after treatment.

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256

Efficacy ofthis Technique

As Table 14.4 shows, according to several clinical tests pulpal anesthesia is successful in nearly 95% of molars, but just 60% of premolars. The success rate drops even lower in the anterior teeth. Surprisingly, although this is an upper arch approach, it anesthetizes the lower lip in a small percentage of cases. As these findings are referred to a standard 2% lidocaine, 1:100 000 (10 μg/ml) epinephrine solution (L-

100), a more powerful solution such as 4% articaine,

1:100

000 (10 μg/ml) epinephrine (A- 100) would be

expected to deliver somewhat better results.

Complications Specific tothis Technique

1) Anesthetic failure is fairly common due to the difficulty

and arbitrary nature of this approach.

⚪ If the needle is not close enough to the pterygopalatine

fossa, rather than the entire maxillary nerve (V

), its

posterior superior alveolar nerve branches are blocked, anesthetizing the molars only.

⚪ If the solution is injected too outwardly, in the

infratemporal fossa (formerly the zygomatic fossa), it is too far away from the pterygopalatine fossa to anesthetize the whole nerve. This can be corrected by tilting the needle more medially, closer to the posterior side of the maxilla (Collon1946).

⚪ If only one instead of two 1.8- ml cartridges (3.6 ml) is

injected, the amount of the solution diffusing is insufficient to anesthetize the maxillary nerve (V

(Collon1946).

2) An extraoral hematoma on the face is the most common

complication. This dark-

brown purplish, normally swollen spot in the malar or superior masseteric area is generally painless. Its cause is blood extravasation (ecchymosis) due to puncture of a vein in the pterygoid plexus or the buccogingival branches of the posterior superior alveolar artery that course somewhat erratically near the maxillary tuberosity (Harn etal.2002). In either case in the next few days the lesion spreads forward and downward along the muscular planes of the cheek, while changing to a purple- yellowish hue. It is wholly reabsorbed in 10–15 days.

3) Ocular and visual alterations in the eye on the side

injected appear in 10–15% of cases. The most common symptom is double vision (dipoplia), although others such as blurred vision, dilated pupil (mydriasis), and drooping eyelid (ptosis) may also appear. When the anesthetic solution is deposited too high in the pterygopalatine fossa (rather uncommon in this approach), the solution diffuses across the inferior orbital fissure to the interior of the orbit, anesthetizing ocular nerves, and

muscles with the concomitant loss of motor coordination (Collon 1946; Forloine et al. 2010). In such situations, (i) reassure the patient that the effect will disappear spontaneously with the effect of the anesthesia, (ii) protect the eye with a patch until the effect subsides, and (iii) advise the patient that they may neither drive nor operate hazardous machinery while the effect lasts.

4) Acute trismus, with the inability to open the mouth par-

tially or wholly, is normally a painful process sensitive to exploration at the insertion site. The cause is needle penetration in the lateral (external) pterygoid muscle, inducing irritation and spasms (Kramer and Mitton1973; Stone and Kaban 1979). Permanent trismus may appear more rarely (Stone and Kaban 1979) (see Chapter22).

5) Pain is inherent in this technique, one of the most

painful.

● Needle progression may induce moderate to severe

pain in 50% of patients (Annex 23).

● Moderate to severe post- operative pain around the

injection site may last 1–3

days in 25% of individuals (Broering etal.2009; Forloine etal.2010), subsiding spontaneously with no sequelae.

Remarks

The high tuberosity approach is not recommended for routine dentistry practice because it is difficult, entails more complications, and delivers results only marginally better

)

than simple buccal infiltration anesthesia. The most important factors for success with this approach are as follows:

1) The tip of the needle must be placed at the right height.

2) The tip of the needle must be oriented at the angle that

brings it closest to the pterygopalatine fossa.

3) Two 1.8- ml (3.6- ml) cartridges must be injected to pro-

vide sufficient volume for the solution to diffuse to the pterygopalatine fossa and reach the maxillary nerve (V

Transpalatal Technique

As in the high tuberosity approach, this technique aims to block the maxillary nerve (V trigeminal nerve, within the pterygopalatine fossa, rendering a wide area numb by anesthetizing all its branches at once.

It is also known as the greater palatine canal technique. The term “transpalatal,” coined by Dr. Gerardo Saborido (1977), seems to be much more illustrative of what the technique actually involves. It was first described in 1921 by Juan Ubaldo Carrea of Buenos Aires, who recommended it in molars and premolars (Carrea1921a,b), and subsequently

), the second division of the

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Transpalatal Technique 257

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applied in 1922 by Otto Hofer of Vienna (Hofer 1922b). It was also described in 1922 by Mendel Nevin of New York, who claimed to have developed it in 1917, but did not recommend it due to the high frequency of obstructions in the canal and the risk of injury to the vascular nervous package (Nevin 1922). The following year Samuel Silverman of Atlanta (Silverman 1923), apparently unaware of Carrea’s work, described it as his own.

Note: In the 1921 paper the surname “Carrea” is mis-

spelled as “Carrba.”

In this relatively simple technique (an enormous advantage over the high tuberosity approach) the needle penetrates the greater palatine foramen through the greater palatine canal to reach the pterygopalatine fossa, where the second division of the trigeminal nerve (maxillary nerve,

) transmits before entering the infraorbital canal.

Uses

As noted earlier, buccal infiltration is the most common technique to anesthetize the upper arch, although on occasion a more powerful anesthetic is required, such as in the following examples.

1) Lengthy oral surgery in the maxillary zone, as the

transpalatal approach covers a larger area with less anesthetic and fewer injections.

2) After buccal infiltration failure, particularly in the

molar zone.

3) In acute buccal cavity infection around molars and pre-

molars. Under such circumstances the buccal infiltration, superior alveolar nerve block, and high tuberosity procedures are contraindicated since the needle must be inserted in this area (Szerlip and Morristown1950; Sved etal.1992). Today, in 95% of the cases where the transpalatal technique is chosen it is for this reason (Sved etal.1992).

Zone Anesthetized

Theoretically the technique would affect the entire area innervated by the second division of the trigeminal nerve, the maxillary nerve (V

● Teeth, including pulp and periodontium of the molars

and premolars on the side injected. Whilst incisors and

canines may be anesthetized, as they are contralaterally

cross- innervated, they may require reinforcement via

buccal infiltration.

● Buccal cavity, including fibromucosa (alveolar mucosa,

gingiva, and interdental papillae), bone, and periosteum

around molars and premolars. As discussed earlier, the

anterior teeth are often contralaterally cross- innervated.

● On occasion the upper area in the roof of the buccal cav-

ity at the first maxillary molar may require supplementary infiltration, as it may be innervated by a branch of the ophthalmic nerve (first division of the trigeminal nerve) (Saborido1977).

● Palate, including the fibromucosa, bone, and periosteum

of the entire hemicontralaterally cross-

arch except the anterior part, which is

innervated by the nasopalatine

nerve (Saborido1977).

● Maxillary sinus on the side injected.

● Terminal branches of the infraorbital nerve that inner-

vate the upper half-

lip, the nasi ala, and the lower eyelid

on the side injected.

Technique

● Very long (42 mm), 27G needle (preferred over 25G as it is

more flexible and less prone to jamming as it progresses; Cohn1986). In patients with small mouths or where a sharp angle is needed (see below), the needle should be bent at a 30–45° angle, several millimeters ahead of the cone or hub to facilitate needle progress along the greater palatine canal (Cook1950b; Mercuri1979; Lepere1993; Douglas and Wormald2006). Note that the needle is not bent at the hub itself because as this is the weakest part it could break.

● Dentist’s and patient’s positions. ⚪ Dentist at 9:00–10:00 o’clock. ⚪ Patient in supine position with head slightly hyperex-

tended to enable the dentist to turn it slightly to the left to anesthetize the right side or to the right to anesthetize the left side.

● Anesthetize the greater palatine nerve where it exits

from the greater palatine foramen and wait 2

minutes before continuing (Chapter 15). This measure aims to minimize possible discomfort during the rest of the procedure.

● Advise the patient that during the injection they may feel

(i) pressure below the maxillary facial tissues on the side injected and (ii) temporary ocular and visual alterations such as double vision (diplopia), drooping eyelid (ptosis), or blurred vision (10% of cases) (Table14.5).

● Determine the depth (length) of the insertion. ⚪ In dry skulls, the mean length along the greater palatine

canal between the greater palatine foramen and the roof of the pterygopalatine fossa is around 35 mm, normally ranging from 20 to 45 mm (Table A 42.6, Annex 42). As the 4–6 mm (3–7 mm) thickness of the fibromucosa over the greater palatine foramen (Table14.6) must be added to that dimension, and take away 1–2 mm of soft tissues overlaying the alveolar crest in bicuspids

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258

Table14.5 Percentage ofvisual/ocular alterations andtheir

relationship toneedle length andamount (ml) ofsolution injected withthe transpalatal technique

Percentage of

Sample

Reference

Dickson and Coates (1945)

Malamed and Trieger (1983)

Sved etal. (1992) 101 39 42 4.4 Schwartz- Arad

etal. (2004) Broering etal.

(2009) Torres etal. (2011) 82 7 41 1.2–1.8

Mean 11, 8 Rounded mean 10

Computer- controlled device (the wand).

Table14.6 Depth ofsoft tissue overlaying thegrater palatine

foramen

Reference Sample Depth (mm)

Dickson and Coates (1945) Patients 3–4 Cook (1950b) Patients 4–7 Canter etal. (1964) Patients 2–7 Viegas and Hemphill (1961) Patients 2–5 Malamed and Trieger (1983) Patients 3–4 Methathrathip etal. (2005) Cadavers 6.7 ± 2.3 (2–13) Douglas and Wormald (2006) Cadavers 6.9 Nimigean etal. (2013) Patients 6 (4–8) Shalaby etal. (2015) Cadavers 4, 9 ± 1, 9

size

80 6 42 2.0

150 1 35 1.8

76 0 30 3, 2

40 18 —

visual/ocular

alterations (%)

Rounded mean 4–6

Needle length (mm)

3.6

Mean 4.7

Amount injected (ml)

(Malamed and Trieger 1983), the total may come to around 37–39 mm on average. Clinical trials yield lower heights, however, around 33 mm (29–35 mm), because the needle need not reach the roof of the pterygopalatine fossa (Broering etal.2009).

⚪ Two methods for a more personalized estimate, par-

ticularly for children or adults with very small or large faces, are in place and closely correlated to the posterior part of the maxilla.

1) Measurement of the low anterior height. This con-

sists of measuring the distance between the infraorbital foramen and the alveolar crest of the second

maxillary premolar.The mean is 30–35

mm (Table

A 2.5, Annex 2).

2) Measurement of the high anterior or orbit height.

This consists of measuring the distance between the upper rim of the orbit and the lower rim at the infraorbital foramen. The mean is 33–34

(Canter etal.1964; Slavkin etal.1966).

⚪ The measurement as estimated with one method or

the other should be increased by 5

mm to accommodate the fibromucosa over the greater palatine foramen. A stop is placed on the needle to prevent over-

insertion (silicone or rubber stop) (Figure14.14).

● Ask the patient to open their mouth as widely as possible

for full vision and to insert the needle in the greater palatine canal. A mouthmay be optionally placed on the non-

opener (bite block or mouth prop)

injection side

(Mercuri1979; Malamed and Trieger1983).

● Locate the greater palatine foramen. ⚪ This formation lies on the horizontal hard palate at the

abutment with the vertical alveolar process: in nearly 90% of individuals it is located around the third maxillary molar (Annex 42) (Figure14.15). The third molar

zone refers to the area ranging from a point slightly forward of the third molar (between it and the second molar) to a point slightly backward of the third molar and including the third molar zone.

⚪ It also helps to know that it lies around 15 mm, later-

ally, from the midline of the palate (Szerlip and Morristown1950; Annex 42).

⚪ It is around 4 mm forward of the posterior edge of the

hard palate (Annex 42). This is important when the maxillary arch is edentulous (Mercuri1979; Wong and Sved1991). One way of distinguishing the hard and soft palate is by locating the line where the color of the palatal mucosa changes.

● Insert the needle in the greater palatine foramen. ⚪ The approach is from the opposite side of the mouth to

more readily locate and insert the needle into the greater palatine canal (Figure14.14).

⚪ Insert the needle slightly forward of where the fora-

men is presumed to be (Figure14.15). Remember that the foramen is covered by around 4–6 mm of fibromucosa (Cook etal.1950b) (Table14.6).

⚪ If the needle does not go in after the first puncture,

repeat the operation several times until the foramen is reached (Hofer 1922b; Peckham 1938; Wong and

Sved1991). Contrary to what some authors contend, the foramen is not readily found by touch and must be located by trial and error (Wong and Sved1991). It is nearly impossible to detect the foramen if the diameter is too small (it varies from 3 to 4 mm; Annex 42) and/ or the fibromucosa is thick.

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Transpalatal Technique 259

Foramen

Occlusal

https://t.me/med1917

Table14.7 Angulation toocclusal plane andmid- sagittal

plane (°) inthe transpalatal technique

Silicone st

Figure14.14 Silicone stop or rubber stop to mark the needle

insertion limit; maneuver facilitated by non- injection side approach.

Reference Sample

Angle occlusal

plane (°)

Angle sagittal

plane (°)

Carrea (1921a) Patients — 5–10 Dickson and Coates

Patients 45 5–10

(1945) Cook (1950b) Patients 60–70 Ries Centeno (1979) Dry skulls 60 — Malamed and Trieger

Dry skulls 46 (20–70) —

(1983) Chentanez etal.

Dry skulls 60 ± 9 —

(1985) Austin (1987) Dry skulls 60 ± 8

(51–76)

7 ± 5 (−3 to

20) Wong and Sved (1991) Patients 60 5–8 Methathrathip etal.

Dry skulls 58 ± 6 7 ± 5

(2005) Douglas and Wormald

Cadavers 60 —

(2006) Howard- Swirzinski

CBCT 63 —

etal. (2010) Shalaby etal. (2015) Dry skulls 50 —

Mean 57.7 7.1

Rounded mean 50–60 5–10

Boundary between horizontal hard palat and vertical alveolar process

Needle insertion ar

Greater palatine foramen

Figure14.15 Location of greater palatine foramen and needle

insertion area.

● Push the needle slowly and gently across the greater pal-

atine canal.

⚪ Direct the needle rearward and upward at an angle of

rotundum

erygopalatine

fossa

Greater

palatine canal

3rd molar

Infraorbital canal

Greater palatine foramen

plane

60°

Figure14.16 Needle angle relative to the occlusal plane of the

maxillary molars. Schematic representation in saggital section.

around 50–60° relative to the occlusal plane of the upper molars (Table 14.7 and Figure 14.16) (sagittal section: antero- posterior direction). It is frequent that the needle has to be bent in the shaft but not in the hub, the weakest part.

⚪ Needle movement relative to the medial plane should

be 5–10° outward (Table 14.7 and Figure 14.17) (coronal section: medial- lateral direction).

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Maxillary Anesthesia I: Pulpal Anesthesia

Medial plane

https://t.me/med1917

260

● Subjective symptoms of anesthesia appear in 3–5 min-

erygopalatine

fossa

Nasal cavity

utes, with patients describing soft tissue anesthesia as tickling, tingling, or numbing (Table13.1, Chapter13) at the injection site and (i) the lower eyelid, nasi ala and

Maxillary sinus

Greater

palatine canal

Greater

palatine

foramen

5–10°

half of the upper lip; and (ii) the half of the palate on the side injected.

⚪ Wait 5–10 minutes after injection to allow the anes-

thetic to take effect and anesthetize the pulp of maxillary molars and premolars. Note that this approach takes a little more time.

⚪ Optionally some clinicians insert a probe in the buccal

mucosa around the molars to determine soft tissue anesthesia.

⚪ The definitive sign of efficacy is obtained by working

on the molars, initially cautiously and then proceeding

Figure14.17 Needle angle relative to the medial plane

(coronal section).

normally if the patient expresses no discomfort.

● Soft tissue anesthesia usually lasts 2–3 hours (Sved

et al. 1992; Lepere 1993), a fact of which the patient

⚪ Never force the needle. Any resistance is an indication

should be notified after treatment. that it is not running parallel to the canal walls. This minor angle deviation can be corrected by drawing the needle back by 1–3

mm to free it of any contact with the bone and readjusting the orientation with minor movements (Peckham1938; Dickson and Coates1945; Saborido1977; Malamed and Trieger1983; Wong and Sved 1991). Note that the scant space available in a greater palatine canal with a narrow diameter (1.5 mm) severely limits any possible redirection of the needle (Cook 1950b). This circumstance is fortunately not very common.

⚪ The clinical impression is that maneuvering inside the

canal causes patients little discomfort (Silverman1923; Malamed and Trieger 1983) and clinical tests show

Efficacy ofthis Technique

As Table 14.8 shows, according to several clinical tests pulpal anesthesia is successful in nearly 95% of molars, but just 65% of premolars. The success rate drops even lower in the anterior teeth. Surprisingly, although this is an upper arch approach, it anesthetizes the lower lip in a small percentage of cases. The clinical success rate in maxillary molars and premolars determined via extractions, oral surgery, and dental treatment (less rigorous method) is in the order of 80% (Table14.9). As these findings are referred to a standard 2% lidocaine, 1:100 000 (10 μg/ml) epinephrine solution (L-

100), a more powerful anesthetic that this technique is less painful than the tuberosity approach (Annex 23).

⚪ Advance the needle until the rubber stop used to mark

the insertion depth is reached. Allow at least 2–3 mm of the needle to protrude outside the mucosa over the greater palatine foramen so it can be withdrawn in the event of breakage (Dickson and Coates 1945; Mercuri1979; Wong and Sved1991).

● Aspire before injecting. Aspiration is positive in 5% of

Table14.8 Successful (%) pulpal anesthesia withthe

transpalatal technique (electrical pulp tester assessment and3.6 ml ofstandard solution L- 100) andpercentage oflower

lip anesthesia

Variable

Broering etal. (1991) n=40

Broering etal. (2009) n=40

cases (Annex 22).

● Slowly inject a 1.8- ml cartridge of solution over the

course of 40–60 seconds and then a second cartridge for a total of 3.6 ml. Some authors deem 1.8 ml to be too little and therefore recommend two (Wong and Sved 1991; Sved etal. 1992). Either repeat the entire operation or, where the patient is highly cooperative, unscrew the needle from the syringe while still in the mouth, load another cartridge and re- screw the syringe onto the needle for the second injection (Wong and Sved1991).

Tooth Second molar (%) 96 100

First molar (%) 83 95 Second premolar (%) 65 80 First premolar (%) 35 68 Canine (%) 26 60 Lateral incisor (%) 17 43 Central incisor (%) 4 23

Lower lip anesthesia (%) — 12

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Transpalatal Technique 261

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Table14.9 Clinical successful (%) inmolars andpremolars

withthe transpalatal technique

Reference Sample size Success rate (%)

Dickson and Coates (1945) 80 80 Corbett and Helmore (1948) — Malamed and Trieger (1983) 150 90 Sved etal. (1992) 101 89 SchwartzTorres etal. (2011) 82 60

Arad etal. (2002) 66 91

Mean 81.3

Rounded mean 80

such as 4% articaine, 1:100 000 (10 μg/ml) epinephrine

100) would be expected to deliver somewhat better

(Aresults.

Complications Specific toThis Technique

1) Full or partial anesthetic failure for the following

reasons.

● The greater palatine foramen cannot be located

(Mercuri1979; Schwartz-

Arad etal.2004), especially in edentulous patients. In such cases, review the anatomy (Mercuri1979).

● The needle continuously catches on the posterior wall

of the canal, a common occurrence in canals highly angled relative to the occlusal plane. Bending the

needle is very useful in such cases, as noted earlier (Mercuri1979; Cohn1986).

● The needle is not inserted far enough and the tip fails

to reach the pterygopalatine fossa, so the gravitydriven anesthetic solution flows downward (Wong and Sved1991). In such cases, repeat the technique with a longer needle (Mercuri1979).

● The amount of anesthetic administered is insuffi-

cient. The solution is to inject another cartridge (Wong and Sved1991).

2) Anatomical variations may induce failure.

● Canal obstructed because it is contorted or irregular,

with osseous protrusions that hinder passage of the needle, a situation found in 5% of individuals (Table14.10). In such cases desist and seek alternative techniques such as the high tuberosity approach (Dickson and Coates1945; Mercuri1979; Cohn1986; Wong and Sved1991). Nonetheless, when the obstacle is less than 15

mm from the total length envisaged

the injection may often be successful (Sved etal.1992).

● Excessive rearward slant on the greater palatine canal

at a very small angle relative to the occlusal plane of the maxillary molars. This anatomic variation may result in the dose being delivered anterior to the pterygoid process, preventing the needle from reaching the pterygopalatine fossa (Cook1950b). This circumstance is uncommon.

● Excessive lateral slant on the greater palatine canal,

which empties into the lateral side the pterygoid process without reaching the pterygopalatine fossa (Cook1950b). This circumstance is also uncommon.

Table14.10 Percentage ofobstructed greater palatine canal indry skulls andclinical trials

Reference n Obstructed (%) Reference n Obstructed (%)

Canter etal. (1964) 205 39 Dickson and Coates (1945) 80 2.5 Slavkin etal. (1966) 58 37 Mercuri (1979) — 5 Jorgensen and Hayden (1970) 200 15 Cohn (1986) — Ries Centeno (1979) 50 6 Sved etal. (1992) 101 6 Malamed and Trieger (1983) 204 3 Schwartz- Arad etal. (2002 and2004) 66–76 0 Chentanez etal. (1985) 120 54 Broering etal. (2009) 40 8 Austin (1987) 42 5 Ferreira etal. (1990) 100 10 Sharma and Garud (2013) 100 4

The values used are from clinical trials; dry skull values are not representative of clinical reality.

Dry skulls Clinical trials

Mean 19.2 5.2

Rounded mean 20 5

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