New anesthetic technique in periodontal procedures.

Periodontal procedures require injection of local anesthetic solution to avoid patient discomfort. Multiple injections are required to anesthetize the anterior maxilla in the region of the premolars to incisors. Anterior middle superior alveolar nerve block is a single palatal injection technique, which anesthetizes the facial and palatal gingiva as well as pulp in the region of the maxillary central incisors to the premolars without any collateral facial anesthesia. This case series presents the application of the anterior middle superior alveolar nerve block in periodontal therapy.

INTRODUCTION

Often, injection is the only perceived painful part of the dental treatment.[1] Periodontal procedures require injection of local anesthetic (LA) solution to avoid patient discomfort. Achieving adequate local anesthesia in the maxilla requires the administration of postero-superior alveolar nerve block, anterior superior alveolar nerve block, middle superior alveolar nerve block, greater palatine, and nasopalatine nerve block and/or multiple “pricks” for infiltration anesthesia. The infra-orbital nerve block, though not commonly used for periodontal procedures, is associated with collateral anesthesia of the upper lip, side of the nose and lower eyelid,[2] which leaves the patient with a numb lip, side of the nose and lower eyelid. A similar situation can be expected from infiltration anaesthesia in the maxillary anterior region. This can be discomforting for the patient once he is discharged from the office, albeit the duration is for one to one and half hours, especially in a country like India where myths concerning the eyes and the teeth are aplenty.

Friedman and Hochman[3] have described the anterior middle superior alveolar nerve block (AMSA) technique, which anesthetizes the anterior superior alveolar nerve, the middle superior alveolar nerve, and the subneural dental nerve plexus. This results in the anesthesia of palatal mucosa from the midline to free gingiva, facial attached gingiva , and pulp in the region of maxillary premolars, canine and the incisors of one quadrant using a single palatal injection without anesthetizing the lip. The maxillary sinus and the nasal aperture result in the convergence of the anterior superior alveolar nerve, middle superior alveolar nerve, and the subneural dental plexus at the region of the root apices of the premolars. It is at this point that a large volume of anesthetic solution is deposited, which can diffuse through the palatal bone to anesthetize the neural structures.

The AMSA nerve block offers several advantages like single injection, less injection of adrenaline, adequate anesthesia, avoids collateral anesthesia of face, hemostatic control at donor site, no effect on blood supply of maxillary recipient sites and esthetic procedures like evaluation of smile line during crown lengthening can be performed after anesthesia.[4] The drawbacks of this technique are, slow administration time of 3–4 minutes resulting in operator fatigue especially when using manual syringe; rapid injection may result in ischemia, pain and ulceration at the injection site, and the need for supplemental anesthesia in the lateral and central incisor region.

The present case series describes the application of this new nerve block technique in periodontal non-surgical and surgical therapy. The onset and duration of anesthesia was also recorded.

AMSA nerve block technique

The patient is positioned supine on the dental chair with slight hyperextension of the neck in order to have accessibility and visibility. The operator should be seated comfortably at 9 or 10′o clock position. The patient is informed that the anesthetic procedure will require 3 - 4 minutes and he/she will experience a sensation of firm pressure. An imaginary line is drawn from the contact point between the premolars to the midpalatine suture. Midway on this line between the free gingival margin and the mid-palatine suture, a 27-gauge needle is inserted perpendicular to the palate [Figure 1]. With the bevel of the needle firmly on the palatal bone, 1.5 ml of 2% Lignocaine hydrochloride# with adrenaline (1:80,000) is administered slowly over a period of 3 - 4 minutes (0.5 ml/min). Rapid injection should be avoided.

Figure 1

Showing the point of needle insertion for AMSA nerve block and the colored region indicates the extent of anesthesia, i.e., from the central incisor to the first molar

Discomfort to the patient can be reduced by following the anesthetic pathway technique in which local anesthetic solution is deposited as the needle is advanced through the palatal mucosa. Subjective signs include numbness of the teeth and the palatal tissues from the central incisor to the premolar. Blanching of the palatal mucosa and facial attached gingiva is observed in the same region [Figure 2].[2]

Figure 2

Blanching of the palatal mucosa following AMSA nerve block

CASE REPORTS

Case 1

A 45-year-old female was referred to the Department of Periodontics and Oral Implantology. She was diagnosed as a case of chronic periodontitis and had a mean probing depth of 6.5 mm. Scaling and root planing (SRP) was advised as part of initial therapy. The patient had discomfort during SRP in the maxillary anterior region; hence AMSA nerve block was administered. SRP was performed using ultrasonic and manual instrumentation. In both the quadrants depth of anesthesia and the duration was adequate to complete the procedure. The patient did not experience any discomfort while root planing. The lips were not anesthetized.

Case 2

A 48-year-old male patient with a 7-mm pocket distal to the right maxillary canine was scheduled for periodontal flap surgery. AMSA nerve block was administered. Adequate depth and duration of anesthesia was achieved. A mucoperiosteal flap was reflected from 2nd premolar to the lateral incisor and the defect was debrided. The anatomy of the defect was not conducive for regenerative procedures. The flaps were secured with silk sutures. The surgery lasted for 55 minutes. The patient did not complain of any pain or discomfort during the procedure. No supplemental anesthesia was required.

Case 3

A 37-year-old male patient with 6-mm pocket distal to left maxillary canine was administered AMSA nerve block and a mucoperiosteal flap was reflected from the 1st premolar to the lateral incisor. The defect was debrided and the flaps secured with silk sutures. The surgery lasted for 65 minutes. No pain or discomfort during the surgery was experienced by the patient. No supplemental anesthesia was administered.

Case 4

A 42-year-old female with 7-8 mm pockets in the right maxillary premolar – lateral incisor region underwent a periodontal flap surgery under AMSA nerve block. The defects were deep necessitating reflection beyond the mucogingival junction in the canine region. During deep reflection patient experienced pain and hence supplemental infiltration anesthesia was administered. The defects were debrided and the flaps secured with silk sutures.

Case 5

A 36-year-old male diagnosed as moderate chronic periodontitis was scheduled for access flap surgery from premolar to central incisor in the 1st quadrant of maxilla. Access flap surgery was performed under AMSA nerve block. Mucoperiosteal flap was reflected, debridement was performed, root planing done, and the flaps were secured with silk sutures. The depth of anesthesia was inadequate in the region of the incisors. This may be due to cross innervations in the mid-line region of the maxilla. This necessitated supplemental infiltration anesthesia resulting in the lips being anesthetized, thus nullifying the advantage of the AMSA nerve block, i.e., preventing the anesthesia of the lips.

Case 6

A 28-year-old male reported to the department with a complaint of a long tooth in the lower front region of the jaw. Clinical examination revealed a millers grade I recession with lower right central incisor. A root coverage procedure with free gingival graft was planned. The recipient site was prepared and the graft was harvested from the premolar – molar region of the left palate under AMSA nerve block. The harvesting of the graft was associated with much less bleeding. The graft was then sutured to the recipient site with 5-0 vicryl sutures.

DISCUSSION

Literature concerning AMSA nerve block in periodontal procedures is scarce. One study compared the administration of AMSA nerve block by computer controlled delivery system and by conventional syringe delivery during SRP, without a control group.[5] There are no comparative studies that have evaluated the efficacy, pain at administration, and duration in non-surgical and surgical periodontal procedures under AMSA nerve block and conventional nerve blocks. Pulpal anesthesia using this technique has been widely studied.[67]

In the present case series, anesthesia of the palatal mucosa and the facial gingiva was achieved in all the subjects. The gingiva of the premolars was most consistently anesthetized followed by the canine, the lateral incisor, and the least was in central incisor, similar to the pattern observed in case of pulpal anesthesia.[6] Cross innervations at the midline may be responsible for the decreased effectiveness of anesthesia towards the midline (Case 5).

Injecting palatally is generally associated with more discomfort, reason being the tight adherence of the palatal mucosa to the underlying bone. None of our patients reported any discomfort while administration of the block despite of the fact that a large volume of LA (1.5 ml) was administered. This could be because of the first few drops of LA deposited, anesthetized the tissue resulting in no discomfort apart from the initial prick.

The onset of anesthesia ranged from five to twelve minutes. Onset of pulpal anesthesia with this technique has been in the range of nine to twelve minutes.[7] The duration of anesthesia was 55–65 minutes, which was similar to pulpal anesthesia.[7]

Good hemostatic control during the retrieval of free mucosal grafts from the palate has been reported with the AMSA nerve block.[4] Similar results were observed during the retrieval of free gingival graft, wherein the retrieval time was considerably reduced (Case 6).

The AMSA nerve block can be administered using the conventional syringes or the automated local anaesthetic delivery devices like the Wand®. With the computer controlled local anesthetic delivery systems, the operator discomfort is reduced and the rate of local anesthetic delivery is controlled. Rapid delivery of LA solution may result in pain and palatal ulceration.[2] None of the subjects in this case series reported of any complication.

AMSA nerve block is a relatively new technique that can be easily mastered. In periodontal therapy it can be administered in clinical situations like SRP, flap surgery in localized defects involving the premolars, canine, and the lateral incisor in which the reflection is not beyond the mucogingival junction and in the harvesting of the free mucosal grafts from the palate. It is helpful in reducing the patient apprehension by avoiding anesthesia of the lips and the number of injections. Further, controlled clinical trials are required to ascertain the benefits of AMSA nerve block in periodontal surgeries.