AMSA (Anterior Middle Superior Alveolar) Injection: A Boon To Maxillary Periodontal Surgery

Introduction: Local anesthetics have been in use in dental practice for more than 100 years. The advent of local anesthetics with the development of nerve blockade injection techniques heralded a new era of patient comfort while permitting more extensive and invasive dental procedures. Discussion: Today’s availability of a variety of local anesthetic agents enables dentists to select an anesthetic that posses ses specific properties such as time of onset and duration, hemostatic control and degree of cardiac side effects that are appropriate for each individual patient and for each specific dental procedure. The ease of the technique is its advantage and disadvantage should always be considered before its acceptance. Conclusion: The importance of this review was to bring about awareness among the general clinician who have to use multiple injection for any treatment to be performed in the maxillary arch. The non compliance of the treatment on the maxillary arch is usually due to these factors. Hence introducing this technique can help patient compliance as well ease for the clinician. Also the duration of treatment is reduced. MOHAMMED NAZISH ALAM Case Report D en tis tr y S ec tio n InTRoDuCTIon Maxillary mucogingival or flap surgery usually requires up to five injections to obtain anesthesia of the hard and soft tissues. Posterior superior alveolar, middle superior alveolar, and anterior superior alveolar block injections are used to anesthetize buccal tissues whereas greater palatine and nasopalatine blocks are used for palatal anesthesia. Although this series of injections effectively anesthetizes maxillary tissues, it may also inadvertently affect facial structures such as the upper lip, lateral aspect of the nose, and lower eyelid [1,2]. The palatal soft tissue anesthesia is achieved without numbness to the lips and face or interference with the muscles of facial expression. A bilateral AMSA injection supposedly anesthetizes 10 maxillary teeth extending from the second premolar on one side to the second premolar on the opposite side [3]. The AMSA injection derives its name from the injection’s ability to supposedly anesthetize both the anterior and middle superior alveolar nerves [4]. The middle superior alveolar (MSA) and anterior superior alveolar (ASA) nerves branch from the infraorbital nerve before they exit from the infraorbital foramen. The middle superior alveolar nerve is thought to innervate the maxillary premolars and plays some role in pulpal innervation of the mesiobuccal root of the first molar. The anterior superior alveolar nerve provides pulpal innervation to the central and lateral incisors and canines [5]. The plexus where both nerves join is the target site for the AMSA injection [6]. ARTICAIne Articaine is an analogue of prilocaine in which the benzene ring moiety found in all other amide local anesthetics has been replaced with a thiophene ring. To date, only one formulation has been approved in the United States, a 4% solution with 1:100,000 epinephrine. With a higher per-cartridge unit cost and a pulpal anesthesia duration of approximately one hour with soft-tissue anesthesia for two to four hours, it would initially appear that articaine is a less attractive agent for dental applications. However, with a slightly faster onset of action (1.4 to 3.6 minutes), reports of a longer and perhaps more profound level of anesthesia and most notably frequent practitioner anecdotes of a greater ability to diffuse through tissues, articaine has become a very widely used anesthetic agent in developed countries. The tissue diffusion characteristics of articaine are not well-understood. However, in a variable percentage of patients, a maxillary infiltration injection in the buccal vestibule will result in adequate palatal anesthesia for tooth extraction. The MAxIllA Most problems with maxillary anesthesia can be attributed to individual variances of normal anatomical nerve pathways through the maxillary bone [7]. While the pulpal sensory fibers of the maxillary teeth are primarily carried in the anterior, middle and posterior superior alveolar nerves which also supply the buccal soft tissues, accessory pulpal innervation fibers may be found in the palatal innervations supplied by the nasopalatine and greater palatine nerves [7]. By careful application of topical anesthetics, distraction techniques (application of pressure and/or vibration) and slow delivery of the anesthetic agent, palatal injections can be given with very little to no patient discomfort. With the availability of articaine hydrochloride 4% with epinephrine many practitioners are finding that palatal injections may not be necessary when it is injected into the maxillary buccal vestibule [8]. Additionally, new computer-controlled anesthetic delivery systems are particularly aimed at eliminating or at least minimizing, the discomfort of palatal injections [9,10,11]. AneSTheTIze PATIenT (DIffICulTIeS) Many factors may affect the success of local anesthesia, some within the practitioner’s control and some clearly not. While no