Table of Contents


Inside Dentistry

May 2007, Volume 3, Issue 5
Published by AEGIS Communications

The Single Tooth Anesthesia (STA)™ System From Milestone Scientific

While significant improvements have occurred regarding the formulation and pharmacokinetics of anesthetic drugs, not many have been made with respect to the syringe itself—until now. The Single Tooth Anesthesia (STA™) System (Milestone Scientific Inc, Livingston, NJ) represents the first major breakthrough in the field of local dental anesthesia since the invention of the syringe some 150 years ago. The STA System is a computer-controlled local anesthetic delivery system consisting of a drive unit and single-use disposable handpiece/needle assembly. What makes it unique is the incorporation of patented Dynamic Pressure Sensing (DPS)™ technology, which enables the fluid pressure and flow rate of the anesthetic solution at the needle tip to be precisely controlled and monitored in real time during all phases of the injection process.

The STA System’sDPS technology allows a clinician to easily and accurately identify specific tissue types at the needle position, based on tissue compliance. Applying this new concept to dental injections enables the clinician to perform an easier, faster, more productive, and more reliable dental injection technique.

The STA Systemand PDL Technique

The periodontal ligament (PDL) injection is one of the most efficient dental injections, as it can numb a single tooth at a time. When performed correctly, peripheral numbness can be eliminated, resulting in a more comfortable and less anxious patient, and an overall more positive experience for both patient and practitioner. However, the PDL injection is referred to as a “blind” injection, because of the inherent difficulty of performing an injection within the intraligamentary space. An intraligamentary injection done with the STA System removes the guesswork and unpredictable nature associated with the traditional syringe-delivered PDL injection by providing real-time visual and audible feedback to the clinician during all phases of the injection.

How the STA Intraligamentary Injection Works

During a dental injection using the STA System, the DPS technology in the drive unit continuously monitors the precise exit pressure measurements of the anesthetic in real time during all phases of administration as it is injected into tissues of varying density. Once the needle tip is located in the proper space, the STA System provides real-time confirmation that the needle tip has not moved outside the tissue target during administration of anesthetic solution. Confirmation is provided to the dentist in the form of user-selected audible tones, an on-system visual light display, and computer-generated voice alerts. In effect, the STA System turns what was once a “blind and hopeful” injection into one that assures the dentist that it is not only being administered in the precise intraligamentary space, but also provides the assurance of a successful injection with rapid and profound onset of anesthesia.

Patients and Dentists Prefer Single-Tooth Anesthesia

Clinical findings consistently show a patient preference for intraligamentary injections using computer-controlled local anesthetic delivery systems compared to the alveolar block injection and/or buccal infiltration.1-6 There are also reports of significant reduction in pain-disruptive behavior in pediatric patients with the use of computer-controlled local anesthetic delivery systems.1-6 Operator preference for the PDL injection is also well documented, and is attributed to its immediate onset of anesthesia; the ability to perform dentistry in both quadrants (bilaterally) in the mandible in a single patient visit; and greater patient acceptance because of the lack of collateral numbness.4,7-9 Additionally, intraligamentary injections are considered to be safer when compared to the risks associated with deep-tissue injections, such as transient or permanent lingual paresthesia.


The STA System provides three important benefits that cannot be achieved using the conventional dental syringe, the pistol-grip high-pressure syringe, or other computer-controlled local anesthetic delivery systems:

• An objective means to determine tissue compliance and thereby determine the tissue type into which the needle is inserted.
• Objective, continuous, and real-time feedback of pressure data, ensuring that the prescribed moderate pressure range is maintained within the injected tissues.
• Objective, real-time information as to the occlusion of a needle and/or loss of pressure resulting from intraoral anesthetic solution leakage.


1. Gibson RS, Allen K, Hutfless S, et al. The Wand vs. traditional injection: A comparison of pain related behaviors. Pediatr Dent. 2000;22(6): 458-462.

2. Allen KD, Kotil D, Larzelere RE, et al. Comparison of a computerized anesthesia device with a traditional syringe in preschool children. Pediatr Dent. 2002;24(4): 315-320.

3. Ran D, Peretz B. Assessing the pain reaction of children receiving periodontal ligament anesthesia using a computerized device (Wand). J Clin Pediatr Dent. 2003;27(3): 247-250.

4. Ashkenazi M, Blumer S, Eli I. Effectiveness of computerized delivery of intrasulcular anesthetic in primary molars. J Am Dent Assoc. 2005;136(10): 1418-1425.

5. Versloot J, Veerkamp JS, Hoogstraten J. Computerized anesthesia delivery system vs. traditional syringe: comparing pain and pain-related behavior in children. Eur J Oral Sci. 2005;113(6):488-493.

6. Oztas N, Ulusu T, Bodur H, et al. The wand in pulp therapy: an alternative to inferior alveolar nerve block. Quintessence Int. 2005;36(7-8): 559-564.

7. Malamed SF. The periodontal ligament (PDL) injection: An alternative to inferior alveolar nerve block. Oral Surg Oral Med Oral Pathol. 1982;53(2):117-121.

8. Dower JS Jr, Barniv ZM. Periodontal ligament injection: review and recommended technique. Gen Dent. 2004;52(6):537-542.

9. Nicholson JW, Berry TG, Summitt JB, et al. Pain perception and utility: a comparison of the syringe and computerized local injection techniques. Gen Dent. 2001;49(2):167-173.

For more information, contact:
Milestone Scientific, Inc
Phone: 1-800-862-1125
Web site:


The preceding material was provided by the manufacturer. The statements and opinions contained therein are solely those of the manufacturer and not of the editors, publisher, or the Editorial Board of  Inside Dentistry. The preceding is not a warranty, endorsement, or approval for the aforementioned products or services or their effectiveness, quality, or safety on the part of Inside Dentistry or AEGIS Communications. The publisher disclaims responsibility for any injury to persons or property resulting from any ideas or products referred to in the preceding material.

Figure 1 The STA™ System is comprised of a portable drive unit that is about the size of a cable modem. Separate, single-use disposable handpieces (called the STA-Wand®) attach to the unit. The STAWand consists of a handle, micro-bore tubing, and an anesthetic cartridge holder that accepts any standard dental anesthetic cartridge. The STA-Intraligamentary injection is typically performed using a 30- or 27-gauge half-inch Luer-Lok needle.