The Effect of Sonophoresis on Topical Anesthesia: A Pilot Study

The Dental Anesthesia Sonophoresis Device (DASD) is a novel device that is intended to reduce the discomfort associated with puncturing the oral mucosa. DASD is a portable, battery-powered device that simultaneously generates ultrasonic energy and sonic vibration in a small applicator head that can easily reach and adapt to injection sites in the oral cavity. The ultrasonic energy provides a sonophoretic effect on the oral mucosa, generating micro channels through the lipids between the keratinized cells that make up the stratum corneum. Once the benzocaine has permeated the stratum corneum, it is quickly absorbed into the soft tissue desensitizing the area and reducing the perception of pain caused by the trauma of puncturing soft tissue. Methods: A split-mouth model using 50 healthy subjects from the ages of 18 to 50 will undergo needle puncture of the maxillary mucobuccal fold at the canine eminence. Prior to the injection there will be randomized application of 20% Benzocaine with a device which is a modified battery operated tooth brush that in appearance and sound is similar to the DASD which only produces sonic vibration which will be known as (SV) or 20% benzocaine with application of the DASD device, that produces ultrasonic as well as sonic vibration. Subjects will rate their pain according to the Visual Analog Scale (VAS).The purpose of this study is to evaluate whether sonophoresis applied using the DASD will eliminate the pain associated with intraoral injections within one minute of application.

Null Hypothesis (Ho): There is no difference in the perception of pain when the DASD is used compared to topical anesthetic applied with sonic vibration.

The Alternative Hypothesis (Ha): There is a difference in pain perception when the DASD is used for application of topical anesthetic compared to topical anesthetic applied with sonic vibration.

Fifty healthy patients between the ages of 18 and 50 will be used for this clinical trial. The anatomical site used for this clinical trial is the maxillary mucobuccal fold above the canine eminence. This site has been selected because it is an anatomical structure that is easily found for all subjects and is reproducible from one side of the patient to the other. One side of the patient's maxillary mucobuccal canine area will be dried with dental 2x2 sponge gauze, then 20% Benzocaine will be applied with an SV for one minute. The site will then be punctured using a short 27-gauge needle inserted to the depth of 3mm.

Immediately after the removal of the needle, the patients will be asked to rate their pain according to the Visual Analogue Scale (VAS) model. The VAS is a measurement instrument 100mm in length anchored by word descriptors at each end. The subject marks on the line the point that they feel represents their perception of their current state.

On the contralateral side, a 2x2 will be used to dry the mucus, and then 20% benzocaine will be applied using the DASD for one minute, followed by a puncture of the oral mucosa with a 27-gauge needle to the depth of 3mm. Immediately after the removal of the needle, the subject will rate their pain according to the same method described above. The application of the topical anesthetic by the DASD and SV will be administered by a single investigator for all subjects. After administration of topical anesthetic the subjects will be divided randomly among six separate investigators who will insert the needle into the mucosa. Neither the investigator giving the injection nor the subjects will be told whether the DASD or SV was used to administer the topical anesthesia. This will insure a double blind trial. A new 27-gauge needle will be used for each injection site to standardize each injection.

Statistical Analysis

Each patient will be treated prior to injection with a topical anesthetic applied either using the SV device or the DASD device. A paired t-test will be used to determine if a statistically significant difference exists between pain scores recorded for each of the injection sites. For the VAS model, the patient's vertical mark is measured from the left hand side in millimeters. The paired t-test will test if the mean difference between SV treated sites and DASD, treated sites to determine which of the two hypotheses are true. The Null Hypothesis (Ho) is that the mean of the differences in pain scores is zero. The Alternative Hypothesis (Ha) is that the mean of the differences in pain scores is not equal to zero . A probability value of 0.05 will be used to determine if the difference is significant.

Eligibility Criteria:
Inclusion Criteria:

1. Good general health as evidenced by the medical history.
2. Ages 18 to 50 (male or female).

Exclusion Criteria:

1. Use of tobacco products.
2. A soft or hard tissue tumor of the oral cavity.
3. Advanced periodontal disease (characterized by the presence of purulent exudate, tooth mobility, and/or extensive alveolar bone loss).
4. Participation in another clinical study or panel test.
5. Pregnant women or women who are breast-feeding.
6. Diabetic.
7. Allergy to benzocaine or ester-type local anesthetic.
8. Previous dental treat in experimental area within 30 days