As an alternative, a computer-controlled delivery device (CompuDent, Milestone Scientific, Livingston, N.J.) accommodates a conventional local anesthetic cartridge that is linked by tubing to a disposable, penlike handle with an attached needle (Wand, Milestone Scientific). The device is operated by means of a foot control that delivers local anesthetic at precise pressure and volume ratios. The device has been demonstrated to provide adequate anesthesia for cosmetic procedures and has been well-received by patients.^3,4 However, it has not been evaluated for use during therapeutic scaling and root planing procedures, and some people have perceived use of the device to be time-consuming.

We conducted this study to compare the efficacy of a computer-controlled local anesthetic delivery system with that of conventional syringe delivery of local anesthetic. Specifically, we evaluated the adequacy of anesthesia for performing scaling and root planing on patients with moderate periodontal disease; pain perceived by patients during both types of injections; the adequacy of the anterior middle superior alveolar, or AMSA, block specific to the computer-controlled device for anesthetizing most of the maxillary arch (Figure 1); and time required for the set of injections and treatment.

View larger version (61K): [in this window] [in a new window]   Figure 1. Scope of anesthesia for the anterior middle superior alveolar, or AMSA, injection. Reproduced with permission of Milestone Scientific, Livingston, N.J.

	METHODS AND MATERIALS

TOP ABSTRACT METHODS AND MATERIALS RESULTS DISCUSSION CONCLUSIONS REFERENCES

At the first treatment appointment, we taught subjects the oral hygiene techniques of toothbrushing—using the modified Bass’ method—and flossing, and we provided them with toothbrushes and floss for home use. All subjects were anesthetized using 2 percent lidocaine with 1:100,000 epinephrine. One trained periodontist (P.M.L.) performed all of the baseline and exit examinations and was not aware of which side of the mouth was anesthetized by the computer-controlled delivery device or which side of the mouth was treated first. Three experienced dental hygienists provided the periodontal treatment and collected data for the study. Due to the nature of the study design, the subjects and the dental hygienists knew which treatment was being provided at each visit.

Subjects accepted into the study had probing depths of at least 4 to 6 millimeters; six teeth per quadrant, including at least one molar; and moderate-to-heavy subgingival calculus on more than one-half of the teeth in the mouth. All subjects were in good physical health and did not have any systemic illnesses that would affect healing responses. We obtained written consent from the subjects in accordance with the Committee on Human Research guidelines from the University of California, San Francisco.

The periodontist conducted a complete periodontal examination at the baseline appointment. He recorded the following indexes: probing pocket depth, clinical attachment loss, presence of gingival bleeding and presence of visible plaque. He calculated clinical attachment loss as the sum of the probing depth and the distance from gingival margin to the cementoenamel junction. The periodontist took a diagnostic series of full-mouth radiographs for each subject so he could assess the amount of alveolar bone loss and other treatment needs.

The periodontist conducted the exit examination four to six weeks after the subjects completed treatment to allow sufficient healing time for accurate periodontal data collection.^5,6 At that time, he performed a second complete periodontal examination and repeated all index measurements except presence of visible plaque. Subjects requiring further dental or periodontal therapy were referred for treatment.

Anesthetic injection procedures. At the baseline examination, the periodontist trained subjects to use a visual analog scale, or VAS,⁷ to record the level of pain they felt during treatment procedures. VAS was scored on a 100-mm horizontal line with the left endpoint marked "no pain" and the right endpoint marked "pain as bad as it can be." To eliminate people who were stoic about pain, we enrolled in the study only subjects who registered VAS pain scores of greater than 20 during periodontal probing at the baseline examination.

At the treatment visits, the conventional aspirating syringe delivery injections the dental hygienists used for the mandibular arch were the inferior alveolar, or IA, (which included the lingual block) and the long buccal, or LB. The computer-controlled delivery injections for the mandibular arch used also were the IA and the LB. The conventional aspirating syringe delivery injections the dental hygienists used for the maxillary arch were the posterior superior alveolar, or PSA; the middle superior alveolar, or MSA; the anterior superior alveolar, or ASA; the greater palatine, or GP; and the nasopalatine, or NP. The computer-controlled delivery system injections used for the maxillary arch were the AMSA (Figure 2 and Figure 3) and the PSA. We assessed pain response using a five-point verbal rating scale, or VRS (none, mild, moderate, severe or very severe pain), scored 0 through 4. The dental hygienists obtained the VAS and VRS for each injection immediately after the injection was administered.

View larger version (79K): [in this window] [in a new window]   Figure 2. Position of the needle in relation to skull anatomy for the anterior middle superior alveolar injection. Reproduced with permission of Mark Friedman, D.D.S.

View larger version (89K): [in this window] [in a new window]   Figure 3. Clinical placement of the needle for the anterior middle superior alveolar injection. Reproduced with permission of Mark Friedman, D.D.S.

The hygienists administered the AMSA injection to the middle portion of the anterior palate through the fibrous palatal tissue, and the anesthetic was deposited next to the palatal bone. Once the needle tip had reached the bone, the slow and steady delivery of anesthetic solution was continued until a sufficient amount of solution was deposited and diffused through the tissue. The injection required 0.6 to 0.9 milliliters of anesthetic solution—one-third to one-half of a cartridge of anesthetic. It took 60 to 90 seconds to deliver.

The palatal bone is porous enough to permit the anesthetic solution to diffuse through the tissues and anesthetize both the anterior and middle branches of the superior alveolar nerve when the injection is deliberately slow and steady. For this reason, the successful deposition of the anesthetic solution through the fibrous tissue is said to be accomplished more easily with the use of a computer-controlled delivery device that regulates the pressure and volume ratio of solution delivered.^3,4 Attaining this consistency in deposition of anesthetic solution is difficult to achieve using a manual syringe.

The time needed for injections and treatment was recorded at every visit. The clinician noted the time required for administering injections at each treatment appointment, the start and end times for the injections, and the half-mouth scaling and root planing. This represented the time required to complete the scaling and root planing treatment appointment.

The dental hygienists telephoned the subjects the day after treatment and asked a scripted set of questions to identify possible adverse events.

Data analysis. We analyzed VAS and clinical attachment loss data using the Wilcoxon signed rank test, a nonparametric test for paired samples. We analyzed VRS data using a binomial probability distribution. We used the Student paired t test for nondirectional data and correlated samples to assess data for time needed to complete all injections required to anesthetize the half-mouth and for total treatment time.

	RESULTS

TOP ABSTRACT METHODS AND MATERIALS RESULTS DISCUSSION CONCLUSIONS REFERENCES

 
Twenty subjects were enrolled in and completed the study. There were no adverse events, and no reports of ulcerations, soreness or swelling related to the injections were reported by subjects the day after treatment. In addition, we noted no history or clinical evidence of swelling or ulceration at any treatment visit or the exit examination. Two subjects had incomplete data scores for the PSA injection, and one subject was missing the AMSA injection score. All other data points were recorded and available for analysis.

Each subject received seven injections per half-mouth using the conventional syringe, and four injections for the half-mouth using the computer-controlled delivery system for anesthesia, resulting in 11 injections for each subject. Three subjects requested additional anesthetic during the 40 treatment sessions, for a total of four re-administered injections required of the 220 injections that were administered.

Periodontal healing. We evaluated periodontal healing four to six weeks after treatment^8,9 to ensure that adequate treatment had been performed and that there were no systematic differences in ability to perform treatment based on the type of anesthetic delivery device. Because the dental hygienists were not blinded to treatment, we thought that the periodontal scaling and root planing could have been less vigorous when performed after anesthetic injections administered using the computer-controlled delivery system compared with the conventional syringe techniques that were more familiar and trusted.

The periodontist measured clinical attachment in all subjects (N = 20) for all teeth, six surfaces per tooth. We measured and compared attachment changes for all surfaces, surfaces with severe attachment loss (> 6 mm at baseline), surfaces with moderate attachment loss (4 to 6 mm loss at baseline) and surfaces with mild attachment loss (< 4 mm at baseline). Overall, the subjects demonstrated significant improvement between the baseline and exit examinations. Comparisons between the computer-controlled delivery device data and the conventional syringe delivery data showed that all subjects improved equally. Attachment loss data and statistical comparisons between the computer-controlled delivery data and the conventional syringe data are presented in Table 1.

Pain perception. VAS. We compared individually the pain scores for injections delivered with the computer-controlled device with those of injections delivered using conventional syringes. We also compared the area of the maxillary arch that was anesthetized by the AMSA injection with the mean of the combination of pain scores for the corresponding conventional syringe injections (ASA, MSA, GP and NP). Perceived pain for the conventional syringe delivery NP injection was highly statistically different from that of the computer-controlled delivery of the AMSA (P = .008). Scores for the corresponding conventional syringe injections in the maxillary arch compared with the scores for the AMSA computer-controlled injection revealed a highly significant difference in favor of the computer-controlled device (P < .0001). There were no differences in the pain perceived by the subjects during the IA or LB injections in the mandibular arch. Data are shown in Table 2 and Table 3.

Total treatment time data represent four injections per half-mouth using the computer-controlled device plus treatment time and readministered injections, compared with seven injections per half-mouth using the conventional syringe technique plus treatment time and re-administered injections. Three subjects required a total of four readministered injections. The readministered injections were the LB and GP using the conventional syringe for one subject, the IA using the conventional syringe for one subject, and the AMSA for one subject receiving computer-controlled anesthetic delivery.

The mean minutes of treatment time required for injections plus scaling and root planing was 81.0 ± 23.5 standard deviation, or SD, per subject using the computer-controlled delivery device, and 80.4 ± 24.0 SD for the conventional syringe injections. These means were not statistically different (P = .81). There was considerable variation in total time required to treat the subjects, ranging from 49 to 120 minutes. Fifteen of the subjects had treatment times for the two scaling and root planing appointments that were within 10 minutes or less of each other. The other five subjects had treatment times that varied by 15 or 20 minutes (P = .2874).

Injections administered using the computer-controlled device were scored regularly as less painful than were injections administered using the conventional syringe.

The mean number of minutes required for administering the injection and collecting data for the half-mouths receiving anesthetic using the computer-controlled delivery device was 19.4 ± 4.5 SD; the mean number of minutes for the half-mouths receiving anesthetic using the conventional syringe was 20.5 ± 5.1 SD. These differences were not statistically significant.

	DISCUSSION

TOP ABSTRACT METHODS AND MATERIALS RESULTS DISCUSSION CONCLUSIONS REFERENCES

 
It was important in this study for us to be assured that subjects who received injections of anesthetic using the computer-controlled delivery device demonstrated evidence of expected healing to ensure adequate therapy. Four to six weeks after treatment, periodontal tissues usually have had time to heal and become less inflamed and, therefore, demonstrate less bleeding on probing.^11–13 In addition, probing pocket depths generally are reduced after treatment by 1 to 2 mm, representing both a reduction in gingival swelling and a decrease in the ability of the probe to penetrate the long junctional epithelial attachment.^14,15 Without that assurance in this study, subjects could have been attracted to a different anesthetic technique because it was a novelty and appealed to them on that basis alone, even if the clinician was unable to scale adequately. As a result, we monitored the periodontal parameters during the study to ensure that anesthesia was sufficient enough to permit the clinicians to provide a high level of therapy. Data showed that the percentage of sites with bleeding per subject was reduced from baseline to exit examination without any difference between modes of anesthetic delivery. In addition, we saw substantial healing—measured by 1 to 2 mm improvements in attachment loss—in deep pockets, and, as expected, smaller changes in shallower pockets.¹⁶ These findings were consistent with the healing seen after scaling and root planing procedures in a variety of studies^17,18 and indicated that the level of anesthesia achieved using either the computer-controlled delivery device or the conventional syringe permitted adequate therapy to be performed.

Our data indicate that injections administered using the computer-controlled device were scored regularly as less painful than were injections administered using the conventional syringe, though when compared individually the differences were statistically significant only for the GP injection. Due to the nature of the computer-controlled delivery device, it was possible for the dental hygienists to use the AMSA injection recently described by Friedman and Hochman³ instead of the four maxillary injections delivered by conventional syringe: the ASA, MSA, GP and NP. The pain scores the subjects reported for the AMSA were significantly lower than the mean scores for the conventional injections it replaced, suggesting that intraoral anesthesia of the anterior maxilla and palate can be achieved with fewer injections and less pain. It is conceivable that if the AMSA injection were administered with a conventional syringe, the pain response would be similar to that of the injection administered using the computer-controlled device. However, we did not compare the delivery of an AMSA injection using the computer-controlled device with delivery using the conventional syringe because of the difficulty of delivering an adequate volume of anesthetic solution over one minute or more with a conventional syringe. The performance of the computer-controlled device is based on the slow and consistent speed of deposition of the anesthetic, which allows for comfortable penetration into the fibrous palatal tissue and adequate diffusion through the tissues in the center of the hard palate to the bone and nerve complex. The consistent finding of lower pain scores with the computer-controlled device was confirmed at the exit examination when subjects expressed clear preferences for computer-controlled delivery of anesthetic. Nineteen of the 20 subjects endorsed the injections as being less painful than any injections they had received previously.

The computer-controlled device uses a conventional dose of anesthetic delivered drop by drop using a slow flow rate of one cartridge over 90 seconds or a faster flow rate of one cartridge over 60 seconds. The slower flow rate is recommended for injections in dense tissue such as palatal mucosa, and we used it for all computer-controlled injections for this study.¹⁹ This could be a concern for clinicians because it might extend the time required for scaling and root planing treatment appointments. During this study, the time required to administer injections and treat the subjects for the half-mouth periodontal scaling and root planing procedures was not statistically different for the two techniques. However, the total time for administering injections—close to 20 minutes per half-mouth—may seem excessive. These total times included the time it took subjects to complete VAS scoring sheets and respond to VRS questions, so the times were greater than would be found in actual dental practice. Although the clinicians found that the computer-controlled injections were slower to administer, fewer injections were required to achieve adequate anesthesia for the half-mouth treatments.

Total time required for administering anesthetic injections and for treatment was consistent among subjects, given that extra time was required to complete the data collection. Total visit times varied from about one hour to about two hours among the subjects. This variation commonly is the amount of time required to adequately scale and root plane half-mouths for patients with moderate periodontal disease characterized by substantial deposition of calculus. The variation in total time required per subject more likely was related to the difference in time required to remove the calculus from the teeth because total injection times were so similar for the subjects.

	CONCLUSIONS

TOP ABSTRACT METHODS AND MATERIALS RESULTS DISCUSSION CONCLUSIONS REFERENCES

 
The two anesthetic delivery techniques were therapeutically equivalent for mandibular injections. The AMSA delivered by the computer-controlled device had clinically significant advantages for maxillary injections. Anesthesia of sufficient depth and duration was achieved to allow therapeutic periodontal scaling and root planing procedures. The time required for providing the injections to achieve half-mouth anesthesia was similar for both techniques, but fewer injections were needed when using the computer-controlled device.

View larger version (111K): [in this window] [in a new window]   Dr. Loomer is an assistant professor of clinical periodontology, Department of Stomatology, University of California, San Francisco School of Dentistry, 521 Parnassus Ave., Room C628, Box 0650, San Francisco, Calif. 94143, e-mail "loomer{at}itsa.ucsf.edu". Address reprint requests to Dr. Loomer.

View larger version (136K): [in this window] [in a new window]   Dr. Perry is the assistant dean for curricular affairs and an associate professor, Department of Preventive and Restorative Dental Sciences, University of California, San Francisco School of Dentistry.