Surgery

Maxillary nerve block—A new approach using acomputer-controlled anesthetic delivery system formaxillary sinus elevation procedure. A prospective studyDevorah Schwartz-Arad, DMD, PhDVEran Dolev, DMD /Wayne Williams. BDS, MChD^

Objective: The maxiilary (or second division) nerve block is an effective method cf achieving profoundanesthesia of a hemimaxilla. This block can be used for procedures involving the maxillary sinus, includingthe maxillary sinus elevation procedure. Tfie purpose of this study was to evaluate a computer-controlledanesthetic delivery system (Wand) fcr maxillary nerve block injection to attain maxillary sinus anesthesiafor sinus floor elevation procedure. Method and materials: The study population consisted of 61 iiealthyadult patients, ranging in age from 40 to 72 years (mean 45 years), who received 76 maxillary nerveblocks (17 having both right and left maxillary blocks) by means of the Wand system via the greater pala-tine nerve approach, for sinus ficor elevation procedure. Two patients |37o) were excluded from the studydue to the inability to negotiate the greater palatine foramen. For each block, two cartridges of 2% lido-caine hydrochloride with adrenaline (1:100,000) were administered, using a 27-gauge-long needle. Afterensuring the anesthetized areas (waiting time 2.5 minutes), the sinus elevation procedure was performed.Parameters recorded were the success cr failure cf anesthesia, positive (blocd) aspiration, bony obstruc-tions in the greater palatine canal, and complications. Results: The use cf this technique increased tdeability to more easily locate the greater palatine foramen. A local infiltration (at the incisor region) wasneeded in 13 (17%) of the blocks, and seven (9.2%) sites required an extra infracrtital block injection inaddition to the maxillary nerve block. One block had a positive aspiration. There were nc bony obstructionsdemonstrated in the canal interfering with the injection, and no complications were recorded. Conclusion:The Wand appears to offer a number of advantages over the hand-held syringe when the greater paiatineblock technique for the maxillary nerve block is used. It is suggested that, when indicated, and with the re-quired knowledge and respect for the associated anatomy, this technique should be considered withgreater ease and more confidence. (Quintessence Int 2004:35:477-480)

Key words: comptJter-controlled anesthetic delivery system, hemimaxilla, maxillary nerve block

The maxiüaty nerve block (MNB) is an effectivemethod of achieving profound anesthesia of a

hemimaxilla. It is useful in procedures involving quad-rant dentistry or in extensive maxillary surgical proce-dures. One of two approaches is available to gain ac-cess to the terminal point for anesthetic delivery-the

'Lecturer and Coordinator, Department of Orai and MaxiiiDfaciai Surgery,The Maurice and Gabriela Goldschleger School of Oental Medicine, TelAviv Universily, Tel Aviv, Israei.

Clinical Instructor, Department cf Prcsttietic Dentistry, TTie Maurice ardGabriela Goldscfiieger School ot Dental Medicine, Tel Aviv University, Tei

Aviv, Israel,

'Session Appointments, Department of Restorative Oentlstry, university ofPretoria, Pretoria, South Africa: and Clinical Director, Milestone ScientificInc, Livingstone, New Jersey.

Heprint requests: Dr Devorati Schwartz-Arad, Department of Oral andMaxillofaciai Surgery, The Maurice and Gabriela Goldsohieger School ofDental Medicine, Tel Aviv University, Tei Aviv, Israel. E-maii: dubisfi©post.taL.ao.il

greater palatine canal (GPC) and the high tubcrosityapproach (HT). The major difficulty encountered withuse of the respective techniques is locating the canalfor the GPC technique and the higher incidence ofhematoma for the HT.' Few studies on the MNB havebeen published in recent literature. The technique isseldom used for dental procedures in the ofGce, andwhen used, it is conducted with extreme caution.Before attempting this block, the operator should de-velop sufficient confidence and cooperation from thepatient. A sudden movement from the patient due topainful stimulus could compromise the safety of thetechnique or lead to unwanted complications,^

The ahility to better predict and easily anesthetizethe maxillary netre and its branches with a single in-jection could make it possible to perform surgical pro-cedures, such as maxillary sinus elevation for dentaiimplants in the posterior maxilla, as routine proce-dures in the private clinic.

Quintessence International 477

• Schwartz-Ar ad et al

Fig 1 (lefl) Greater palatine foramen: A palatal view of a dry skull

Fig 2 (below) Palatal view of the ma«illary nerve blook througlithe greater palatine foramen approach using the compuler-as-sisted anesthetic delivery system. Note the blood spot on Ihe con-tralateral side immediately after injection.

The use oí a computer-controlled anesthetic deliv-ery system for maxillary sinus elevation procedure viathe GPC approach is described.

PARTICIPANTS AND METHODS

The study was conducted in a private clinic using acomptiter-controlled device {Wand, MilestoneScientific) by a senior oral and maxillofacial surgeon.Since October 1999, 61 aduU healthy patients, rangingin age from 40 to 72 years {mean 45 years) received 76maxillary nerve blocks (17 had both right and leftmaxillary blocks) by means of the Wand, a computer-controlled anesthetic delivery system, via the GPC ap-proach. Two patients (3%) were excluded from thestudy due to an inability to negotiate the greater pala-tine foramen. Indication for using regional maxillarynerve anesthesia was to perform sinus floor elevationprocedures (on one or both sides).

A detailed technique for maxillary block injectionvia the greater palatine foramen has been previouslydescribed.' Briefly, the palatal soft tissue, directlyover the greater palatine foramen {GPF), is the areaof insertion. A landmark for the GPF is the junctionof the maxillary alveolar process and palatine hone(Fig 1). The needle is oriented toward the palatal softtissues (Fig 2). Immediately prior to the bevel con-tacting the soft tissue, the foot switch is activated tothe slow ñow-rate position to ensure a positive flowof anesthetic at the moment the needle penetrates thetissue. During needle insertion (approximately threefourths of its length), continuous, controlled, positivepressure delivers an anesthetic drip that precedes theneedle, creating an anesthetic pathway without theuse of a topical anesthetic. Auto-aspiration (simpleremoval of the foot from the foot pedal) set at 12 sec-

onds was perfortned immediately after ensuring thatthe needle was located in the GPC at the terminalneedle position.

After injecting the first cartridge (1.8 mL), a secondcartridge was inserted into the machine without re-moving the needle from its position in the GPC. Thedevice should be located at head level or beneath toensure that air does not penetrate into the deliverysystem. Lidocaine hydrochloride {HCI) (2%) with epi-nephrine (1:100,000) as a vasoconstrictor {Lidocadren2%, TEVA Pharmaceutical) was administered for eachblock using a total injection volume of 2.1 cartridges{range 2 to 5). A 27-gaugc, 1 'A-inch-long (30 mm)needle was used (Becton Dickinson).

Successful anesthesia was considered to be presentwhen the entire hemimaxilla was anesthetizeti. Afterensuring that the indicated areas for surgery were ade-quately anesthetized (average waiting time 2.5 min-utes), the sinus elevation procedure was performed.Parameters recorded were the success or failure ofanesthesia, positive (blood) aspiration, bony obstruc-tions in the greater palatine canal, and complications.

RESULTS

The success of anesthesia administration was exam-ined by probing the gingival buccal aspect of the hemi-maxilla on the same side as the injection. Of the 76MNB, 13 (17%) required an additional local infiltra-tion of the anterior superior alveolar nerve, ana inseven blocks {9.2%), an additional infraorbital nerveblock was delivered. Positive (blood) aspiration wasrecorded in one block (Fig 3). There were no bony ob-structions in the canal interfering with the needlepathway, and no complications were observed or re-ported during or after injection.

478 Volume 35, Number 6. 2004

• Schwartz-Arad et ai

Hg 3 Positive blood aspiration. Fig 4 The Wand tiandpiece, rnicrotube, and cartridge tiolder.

DISCUSSION

The maxillary nerve block compared to infiltrationanesthesia provides a greater scope for surgery byanesthetizing the hemimaxilla with one needle pene-tration (injection site). Patients accept this approachbetter than a technique that requires several in-jections.5 A common problem encountered with theuse of the MNB technique is the inability to obtainprofound anesthesia, which is frequently caused bythe operator's inability to flnd the greater palatineforamen,

The use of a bandpiece (Fig 4), held like a pen, pro-vides the operator with increased tactile perceptionand control of the needle and the needle bevel duringplacement. The slow-flow technology contained withinthe computerized delivery system enables a preciseand automated control of the anesthetic flow rate,leaving the operator's hands free to hold the light-weight handpiece and insert it at the correct angle.Thus, the operator's ability to locate the foramen isgreatly improved. The handpiece design also allows forrotation of the needle during penetration, resulting ina potential decrease in needle deflection.-* The abilityto rotate the needle during aspiraflon has been shownto increase the acctiracy and decrease the possihility ofinadvertent accidental intravascular injecflon,

Partial anesthesia is not a technique-related prob-lem. It is probably due to the high vascularity of theinjected area or to the height of the maxilla beinggreater than the reach of the needle tip. Partial anes-thesia has been described in 5% to lS /o of the hlocksusing the traditional syringe as a delivery system,^'Additional reasons for partial anesthesia are partial in-travasctilar injection, collateral innervations, and in-sufflcient volume of anesthetic solution. To minimizethis occurrence, at least two cartridges (1,8 mL each)

should be used, with a minimal waiting time of 2.5minutes hefore beginning the procedure.

The computerized delivery system aflows an emptycartridge to he replaced outside of the oral cavity with-out having to withdraw and reinsert the needle duringinjection. In this way, the two recommended cartridgescan be delivered by a single penetration, thus, signifl-cantly decreasing potential complications. In addition,there is no need for cartridge sterilization when usingthis system because cartridge replacement is via an ex-traoral manipulation of the cartridge holder at a pointfar removed from the handpiece and needle.

It is of great interest that the interpretation of MNBis not unifonn in the literature,'^*' Success of MNBanesthesia has been descrihed when the teeth, gingiva,and sinus, up to the flrst premolar on the ipsilateralside, is "completely anesthetized."* Success in the pre-sent study was recorded only when complete hemi-maxiUa anesthesia was achieved (up to the flrst incisorof the ipsilateral side). This difference can explain therelatively high rate of partial anesthesia in the presentseries.

Additionally, there was only one positive blood as-piration. The vessels within the canal, which are usu-ally pushed aside as the needle advances, should hetaken into consideration. If there is a positive aspira-tion, the needle should he slightly withdrawn and thenreadvanced.'-^ Intravascular injection (positive hloodaspiration) has been descrihed as a complication in8% of patients,^ Other complications were nasalbleeding (epistaxis), diplopia (35%), strabismus (12%),ptosis (10%), constrictions in the canal (6%), and in-jury to neural tissue (1%), None of these occurred inthis study.

It has heen recommended that the operator ac-quire the patient's complete confidence and coopera-flon hefore attempflng this block. The success of the

Quintessence International 479

Schwartz-Arad et al

MNB could be compromised or lead to complicationswhen the patient moves suddenly because of a painfulstimulus.^

The subjective pain response from a computer-as-sisted palatal injection has been evaluated. Out of 50dentists, 48 reported that this injecfion caused minimalor no pain for the patient.* Others^'" also reported agreater sense of comfort among the patients duringanesthesia with the computerized delivery system. Thisis probably due to the light and pen-grasp handle,which eliminates the need for the operator to usethumb pressure to administer the injecfion, resulfing ingreater tactile feedback, precision, and operator ease.

CONCLUSION

1. The computer-controlled anesthetic delivery systemoffers advantages over the hand-held syringe whenthe maxillary nerve block through the greater pala-tine canal approach is used.

2, With the required knowledge and respect for theassociated anatomy, this technique should be con-sidered with greater ease and more confidence,when indicated.

REFERENCES

1. Malamed SF. Handbook of Local Anesthesia, ed 4. StLouis: Mosby, 1997:187-191.

2. Shira RB. Oral surgery-Intraoral second division nerveblock. Oral Surg Oral Med Oral Pathol 1979;47:109-113.

3. Thomas EP, Françoise MX Maxillary nerve block: A usefultechnique. J Oral Surg 1973:31:749-755.

4. Hochman MN, Friedman M¡. In vitro study of needle deflec-tion: A linear insertion technique versus a hidircctional rota-tion insertion technique. Quintessence Int 2000:31:33-39.

5. Lipp MDW. Local Anesthesia in Dentistry. Chicago: Quin-tessence. 1993.

6. Wong JD, Sved AM. Maxillary nerve block anaesthesia •the greater palatine canai: A modified technique and casereports. Aust Dent J 1991;36:15-2I,

7 Sved AM, Wong JD, Donkor P, et al. Complications associ-ated with maxillary nerve block anaesthesia via the greaterpalatine canal. Aust Dent J 1992;37:340-345.

8. Friedman MJ, Hochman MN. A 21st century computerizedinjection system for local pain control. Compend ContinEduc Dent 1997;18:995-1003.

9. Friedman MJ, Hochman MN. The AMSA injection: A newconcept for local anesthesia of maxillary teeth using a com-puter-controlled injection system. Quintessence Inl1998;29:297-303.

10. Friedman MJ, Hochman MN, P-ASA Block injection: Anew palatal technique to anaesthetize maxillary anteriorteeth, J Esthet Dent 1999;11:63-71.

Volume 35, Number 6 2C04