The two primary intraosseous injection techniques were similar regarding anesthetic success, onset, duration and perceived heart rate increases.

The Stabident injection system has been evaluated as a primary injection. Leonard¹ reported that a majority of extractions were successful with this system. Coggins and colleagues,² who used the Stabident system as a primary injection in various groups of maxillary and mandibular teeth, reported a 75 percent rate of success (defined as no response to pulp testing) for the mandibular first molar. Replogle and colleagues³ reported that for mandibular first molars, the primary Stabident IO injection of 2 percent lidocaine with 1:100,000 epinephrine was more successful (no response to pulp testing) than was a Stabident primary injection of 3 percent mepivacaine—a 74 percent success rate versus a 45 percent success rate, respectively. Chamberlain and colleagues⁴ found that 95 percent of patients were successfully anesthetized for operative dentistry procedures when using the Stabident IO injection technique.

A second intraosseous system is on the market: the X-tip (X-tip Technologies, Lakewood, N.J.) anesthesia delivery system. The X-tip system consists of two parts: a drill and a guide sleeve component (Figure 2). The drill—a special hollow needle—leads the guide sleeve through the cortical plate, where it is separated and withdrawn. The remaining guide sleeve is designed to accept a 27-gauge needle to inject the anesthetic solution. The guide sleeve is removed after the IO injection is complete.

View larger version (96K): [in this window] [in a new window]   Figure 2. The X-tip anesthesia delivery system (X-tip Technologies, Lakewood, N.J.) consists of an X-tip (top) that separates into two parts: the drill (a special hollow needle) and guide sleeve component (bottom).

We undertook a prospective, randomized blinded study to compare an apical primary X-tip IO injection with a coronal primary Stabident IO injection in mandibular posterior teeth.

	SUBJECTS, MATERIALS AND METHODS

TOP ABSTRACT SUBJECTS, MATERIALS AND METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
Forty-one adult subjects participated in this study. The subjects were in good health and were not taking any medications that would alter their perception of pain. The human subjects review committee of The Ohio State University, Columbus, approved the study, and we obtained written informed consent from each subject.

We tested 24 mandibular left and 17 right sides, with the first molar, second molar and second premolar as the test teeth. We used the contralateral canine as the unanesthetized control to ensure that the pulp tester was operating properly and that the subject was responding appropriately during the experiment. Clinical examinations indicated that all teeth were free of caries, large restorations and periodontal disease, and that none had a history of trauma or sensitivity.

Two appointments at least two weeks apart were scheduled for each of the 41 subjects. According to the study’s crossover design, each subject randomly received either the Stabident IO injection or the X-tip IO injection using 1.8 millimeters of 2 percent lidocaine with 1:100,000 epinephrine (Xylocaine with epinephrine, AstraZeneca, Wilmington, Del.) at two separate appointments. Assigned random numbers determined the order of IO system administration. The principal investigator (J.G.) gave all IO injections.

Trained personnel, who were blinded to the type of IO systems administered, performed all preinjection and postinjection tests. The trained research assistants were dental or hygiene students specifically trained in conducting clinical trials. At the beginning of each appointment and before any injections were given, the research personnel tested the experimental teeth and the control canine three times with a Kerr pulp tester (Analytic Technology, Redmond, Wash.) to record baseline vitality. After isolating the tooth to be tested with cotton rolls and drying it with gauze, the research assistant applied toothpaste to the probe tip, which was placed midway between the test tooth’s gingival margin and its occlusal edge. The current rate was set at 25 seconds to increase from no output (0) to the maximum output (80). The research assistant recorded the number at initial sensation.

Stabident administration. The IO injection with the Stabident system was given in the following manner. With the subjects in a reclining position, the principal investigator determined the area of perforation by the horizontal line of the buccal gingival margins of the first and second molars and a vertical line that passed through the interdental papilla on the distal aspect of the first molar. She selected a point approximately 2 millimeters below the intersection of these lines as the perforation site if the site was in attached gingiva. If this point was in alveolar mucosa (as it was in two subjects), she moved the injection site to just above the junction of the attached gingiva and the alveolar mucosa.

We defined an easy perforation as one that could be completed in less than five seconds using only light pressure, and a difficult perforation as one that required moderate pressure, required longer than five seconds to penetrate the cortical bone or both.

The principal investigator anesthetized the alveolar mucosal soft tissue adjacent to the determined perforation site with a supraperiosteal infiltration injection of 0.6 mL of 2 percent lidocaine with 1:100,000 epinephrine deposited through a 30-gauge needle attached to an aspirating syringe. Five minutes after the infiltration injection, pressure was applied at the determined perforation site with a periodontal probe. If the subject felt pain, which happened in two cases, the principal investigator administered an additional 0.3 mL of 2 percent lidocaine with 1:100,000 epinephrine.

The cortical bone was perforated with the Stabident perforator (a beveled-ended solid wire attached to a plastic hub) in a contra-angle, slow-speed handpiece. The principal investigator placed the perforator through the gingiva and oriented it perpendicularly to the cortical plate. With the point gently resting against bone, the principal investigator activated the handpiece at full speed while pushing the perforator, with light pressure, against bone, slightly withdrawing the perforator and then pushing it again against bone. She continued this action until she observed a "breakthrough" feeling or the perforator was placed to length. The handpiece was always activated while the perforator was within bone to prevent lodging or breakage that might occur if the perforator was allowed to stop rotating.

We defined an easy perforation as one that could be completed in less than five seconds using only light pressure, and a difficult perforation as one that required moderate pressure, required longer than five seconds to penetrate the cortical bone or both. Before inserting the 27-gauge ultra-short Stabident needle through the perforation, the principal investigator bent the needle at the hub to a 45-degree angle to allow for ease of insertion. She blotted the area of perforation with a sterile cotton roll to control hemorrhage and identify the perforation site (a small dot of hemorrhage on the blanched gingiva). She held the standard syringe in a pen-gripping fashion, inserted the needle into the perforation site and delivered 1.8 mL of 2 percent lidocaine with 1:100,000 epinephrine over a one-minute period. If the principal investigator encountered back-pressure (defined as greater than light finger pressure on the syringe handle to deliver the solution) on solution deposition, she rotated the needle approximately one-quarter turn and reattempted deposition. If this was not successful, she removed the needle and checked it for blockage. When it was blocked (which happened with four subjects), a new needle was used. If it was not blocked, the principal investigator reperforated the site (as was necessary with one subject) with a new perforator and completed the injection.

At completion of the deposition of solution, the principal investigator performed a mock guide sleeve removal so all treatment procedures would seem identical to the subject. The mock guide sleeve removal was accomplished by mimicking the procedure for removing the X-tip guide sleeve. The principal investigator retracted the subject’s cheek, placed the tip of the hemostat in contact with the anesthetized gingiva and rotated the hemostat back and forth for three to five seconds.

X-tip administration. The IO injection with the X-tip system was given in the following manner. With the subjects in a reclining position, the principal investigator determined the area of perforation to be in alveolar mucosa (approximately 3–7 mm inferior to the Stabident perforation site) at a site distal to the mandibular first molar. The alveolar mucosal soft tissue, adjacent to the determined perforation site, was anesthetized with a supraperiosteal infiltration of 0.6 mL of 2 percent lidocaine with 1:100,000 epinephrine deposited through a 30-gauge needle attached to an aspirating syringe. Five minutes after the infiltration injection, the principal investigator applied pressure at the determined perforation site with a periodontal probe. If the subject felt pain (which was the case with five subjects), the principal investigator administered an additional 0.3 mL of 2 percent lidocaine with 1:100,000 epinephrine. The principal investigator secured the guide sleeve of the X-tip system against the drill via finger pressure as the red protective covering was withdrawn. She pulled the alveolar mucosa taut, using the fingers of the other hand, to minimize engaging the mucosal tissue during rotation of the perforator. The principal investigator pushed the perforator through the alveolar mucosa until the X-tip contacted bone. Holding the drill at a 90-degree angle to the bone, she activated the slow-speed handpiece at full speed while lightly pushing the perforator against bone, slightly withdrawing it and then pushing it against bone again. She continued this action until a "breakthrough" feeling was observed or the perforator was placed to length. The handpiece was always activated while the perforator was within bone to prevent lodging or breakage that might occur if the perforator was allowed to stop rotating.

We used the same definitions for easy and difficult perforations as with the Stabident procedure. The principal investigator then withdrew the drill from the guide sleeve, leaving the sleeve in place. Before inserting the 27-gauge X-tip needle into the guide sleeve, she bent the needle at the hub to a 60- to 80-degree angle to allow for ease of insertion. She held the standard syringe in a pen-gripping fashion, and inserted the needle into the guide sleeve to its hub and delivered 1.8 mL of 2 percent lidocaine with 1:100,000 epinephrine over a one-minute period. If the principal investigator encountered back-pressure (defined as greater than light finger pressure on the syringe handle to deliver the solution) on solution deposition, she rotated the needle approximately one-quarter turn and reattempted deposition. If this was not successful, she removed the needle and checked it for blockage. No needles were blocked. Owing to backflow of the anesthetic solution into the oral cavity in one subject, the principal investigator removed the guide sleeve using a hemostat and reperforated the site with a new perforator and completed the injection.

On completing deposition of solution, the principal investigator removed the guide sleeve using a hemostat. She rated the removal of the guide sleeve component as easy (within five seconds) or difficult (required more than five seconds).

For both the Stabident and X-tip techniques, the principal investigator instructed each subject to close his or her eyes during all injections, and during the actual or mock guide sleeve removal, to ensure blinding of the techniques. The research personnel were not present during the Stabident or X-tip injections.

At one minute after completion of the IO injection, the research assistants performed pulp testing on the the first and second molars. At two minutes, they tested the second premolar and contralateral, control canine. This cycle of testing was repeated every two minutes. They tested the control canine every six minutes with an inactive pulp tester to test the subjects’ reliability. All testing was stopped at 60 minutes after the IO injection.

At two minutes after deposition of anesthetic solution, the principal investigator asked the subject, "Did your heart feel as if it were beating faster?" (in other words, whether the patient was experiencing palpitations). The principal investigator monitored lip anesthesia every six minutes throughout the 60 minutes by asking the subject, "Is your lip numb?"

We used as our criterion for pulpal anesthesia an absence of response on the subject’s part to the maximum output (an 80 reading) of the pulp tester. We considered anesthesia successful when a subject had two consecutive 80 readings. With a nondirectional alpha risk of 0.05 and a power of 80 percent, a sample size of 40 subjects was required to demonstrate a difference of ± 30 percent in anesthetic success.

We analyzed the data statistically. In our comparisons of the Stabident and X-tip IO injections for anesthetic success, incidence of pulpal anesthesia, perceived heart rate increases (palpitations), lip anesthesia and ease of perforations, we used the McNemar test. We made comparisons between techniques for onset time of pulpal anesthesia using the Wilcoxon signed rank test. Comparisons were considered significant at P < .05.

	RESULTS

TOP ABSTRACT SUBJECTS, MATERIALS AND METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
Forty-one adult subjects, 24 men and 17 women, aged 19 to 43 years with an average age of 26 years, participated.

The rates of anesthetic success are presented in the table. Rates of success in anesthetizing mandibular posterior teeth using the Stabident IO technique and the X-tip IO technique, respectively, were 93 percent and 93 percent for the first molar; 95 percent and 95 percent for the second molar; and 81 percent and 83 percent for the second premolar. There was no significant difference (P > .05) between the two IO techniques in terms of success. Figures 3 through 5 present incidence of pulpal anesthesia (80 readings) for the two techniques. There was no significant difference (P > .05) between the two techniques at any of the postinjection intervals.

View larger version (25K): [in this window] [in a new window]   Figure 3. Incidence of anesthesia for the mandibular first molar as determined by lack of response to electrical pulp testing at the maximum setting (percentage of 80 readings) at each postinjection interval, for the two injection techniques. There were no significant differences (P > .05) between the Stabident and X-tip techniques at any interval. Stabident is manufactured by Fairfax Dental, Miami. The X-tip system is manufactured by X-tip Technologies, Lakewood, N.J.

View larger version (25K): [in this window] [in a new window]   Figure 4. Incidence of anesthesia for the mandibular second molar as determined by lack of response to electrical pulp testing at the maximum setting (percentage of 80 readings) at each postinjection interval for the two injection techniques. There were no significant differences (P > .05) between the Stabident and X-tip techniques at any interval. Stabident is manufactured by Fairfax Dental, Miami. The X-tip system is manufactured by X-tip Technologies, Lakewood, N.J.

View larger version (24K): [in this window] [in a new window]   Figure 5. Incidence of anesthesia for the mandibular second premolar as detemined by lack of response to electrical pulp testing at the maximum setting (percentage of 80 readings) at each postinjection interval, for the two injection techniques. There were no significant differences (P > .05) between the Stabident and X-tip techniques at any interval. Stabident is manufactured by Fairfax Dental, Miami. The X-tip system is manufactured by X-tip Technologies, Lakewood, N.J.

In response to subject questioning, 85 percent of the subjects with the Stabident IO injection and 93 percent with X-tip IO injection reported a perceived increase in heart rate (palpitation). There was no significant difference (P > .05) between the IO techniques.

Lip anesthesia was recorded in 100 percent of the Stabident IO injections and 94 percent of the X-tip IO injections. There was no significant difference (P > .05) between the IO techniques.

For the Stabident system, the principal investigator rated perforation as easy in 76 percent (31 of 41) of the injections and difficult in 24 percent (10 of 41). For the X-tip system, perforation was rated as easy in 78 percent (32 of 41) of the injections and difficult in 22 percent (9 of 41). There was no significant difference (P > .05) between the IO techniques. No perforators broke, using either system, during the study.

For the X-tip system, the principal investigator rated removal of the guide sleeve component as easy in 68 percent (28 of 41) of the injections and difficult in 32 percent (13 of 41).

	DISCUSSION

TOP ABSTRACT SUBJECTS, MATERIALS AND METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
We based our use of the pulp test reading of 80—signaling maximum output—as a criterion for pulpal anesthesia on the studies of Dreven and colleagues⁷ and Certosimo and Archer.⁸ These studies showed that an 80 reading ensured pulpal anesthesia in vital asymptomatic teeth. Additionally, Certosimo and Archer⁸ demonstrated that electric pulp test readings less than 80 resulted in pain during restorative procedures.

Anesthetic success for both IO injections was 93 percent for the first molar, with no statistically significant differences between the Stabident and X-tip injections (Table). Using a similar methodology, Replogle and colleagues³ and Coggins and colleagues² reported anesthetic success rates (success being an absence of response to pulp testing) of around 75 percent for the mandibular first molar, using a primary Stabident IO technique and 1.8 mL of 2 percent lidocaine with 1:100,000 epinephrine. The lower success rates in these early studies of the Stabident IO technique may be related to back-pressure during solution deposition, which resulted in backflow of the anesthetic solution into the oral cavity. Although Replogle and colleagues³ and Coggins and colleagues² did not state specifically how often this type of failure occurred, they did report back-pressure occurring in 9 to 19 percent of the injections. Inadvertently, backflow into the oral cavity may have been included as failure of pulpal anesthesia.

In our study, we did not observe any backflow of anesthetic solution into the oral cavity, except in the one subject who required reperforation. The lack of 100 percent success with both IO techniques may be related to constricted cancellous spaces that limited the distribution of the anesthetic solution around the apices of the teeth. On the basis of the results of this study, we can conclude that the Stabident and X-tip IO techniques are similar in success rates in mandibular first molars when used as primary IO injections in a manner similar to that used in this study. Because we studied a young adult population, the results of this study may not apply to children or elderly patients. The X-tip manual⁶ recommends using the X-tip system in attached gingiva rather than the alveolar mucose as we did in this study. Future studies may determine if the location in the attached gingiva affects the success rate of the X-tip system. However, we can speculate that they should be similar.

For both of the IO injections, anesthetic success was 95 percent for the second molar (Table, page 1479). There was no statistically significant difference between the Stabident and X-tip techniques. When the Stabident IO injection was given at a distal site to the first molar, Replogle and colleagues³ and Coggins and colleagues² reported a similar success rate for the second molar when compared to the first molar. Therefore, for both the Stabident and X-tip IO systems, as used in this study, success rates for the second molar would be similar to the first molar.

For the Stabident and X-tip IO injections, anesthetic success was 81 percent and 83 percent respectively for the second premolar, with no statistically significant differences between the techniques (Table, page 1479). Replogle and colleagues³ and Coggins and colleagues² also reported lower anesthetic success rates for the second premolar when the Stabident system was used as a primary injection of the first molar. The lower anesthetic success rate for the second pre-molar most likely is related to the selection of the perforation site distal to the first molar. That is, using a distal injection site to the first molar decreases the amount of anesthetic available to the second premolar. As shown by Reitz and colleagues,⁹ if pulpal anesthesia is required of the second premolar, selecting an IO injection site distal to this tooth would provide better pulpal anesthesia than selecting a site distal to the first molar.

The duration of pulpal anesthesia in our study, for both IO techniques, showed a steady decline over the 60-minute observation period.

Onset of pulpal anesthesia occurred within the first 2 minutes in the first molar with both IO injection techniques (Figure 3, page 1480). Replogle and colleagues³ and Coggins and colleagues² also reported that a primary IO injection resulted in a fairly quick onset of pulpal anesthesia.

The duration of pulpal anesthesia in our study, for both IO techniques, showed a steady decline over the 60-minute observation period (Figures 3–5). For example, approximately 76 percent (Stabident technique) and 73 percent (X-tip technique) of the first molars were anesthetized at 30 minutes (Figure 3). At 60 minutes, approximately 51 percent (Stabident technique) and 39 percent (X-tip technique) of the first molars were still anesthetized (Figure 3). There were no significant differences between the two techniques at any of the postinjection intervals. Other authors using the Stabident technique as a primary injection also reported a declining rate of pulpal anesthesia.^2,3 The principal investigator should be aware of this when using either the Stabident or X-tip IO technique as a primary technique. In operative and restorative procedures of 60 minutes’ duration, the true value of the IO injection may be its use as a supplemental injection.^10,11 Using 1.8 mL of 2 percent lidocaine with 1:100,000 epinephrine, Dunbar and colleagues¹⁰ and Guglielmo and colleagues¹¹ evaluated the Stabident IO system in mandibular first molars as a supplemental injection to the inferior alveolar nerve block. They recorded a high incidence of pulpal anesthesia (100 percent); with 85 to 90 percent of the first molars still anesthetized at 60 minutes.

Various authors^2,9–14 have subjectively reported a perceived increase in heart rate, or palpitations, 46 to 90 percent of subjects with the Stabident IO injection of solutions containing epinephrine and levonordefrin. In the current study, 85 percent (35 of 41) of the subjects reported that they perceived an increase in heart rate, in response to questioning, after receiving the Stabident injection and 93 percent after the X-tip injection. Replogle and colleagues¹⁴ and Coggins and colleagues² found that 60 percent and 75 percent of subjects, respectively, reported a perceived increase in heart rate (as reported via subject questioning) with the Stabident IO injection of 1.8 mL of 2 percent lidocaine with 1:100,000 epinephrine. The difference in heart rate between the current study and that in subjects studied by Replogle and colleagues¹⁴ and Coggins and colleagues² probably is related to the greater number of anesthetic successes in our study. That is, there would be a greater likelihood of an increase in heart rate if more of the anesthetic were delivered into the cancellous bone.

Four studies^11,13–15 have evaluated heart rate using subjective questioning and objective measurements (electrocardiogram and pulse oximetry) during and after IO injections. The studies found that subjective and objective measurements of heart rate were similar for IO anesthesia.

Replogle and colleagues¹⁴ reported 67 percent of her subjects objectively (electrocardiogram recordings) had an increased heart rate with the Stabident IO injection of 1.8 mL of 2 percent lidocaine with 1:100,000 epinephrine. The mean increase was 28 beats per minute. Chamberlain and colleagues⁴ found that the Stabident IO injection of 2 percent lidocaine with 1:100,000 epinephrine resulted in a mean heart rate increase of 12 beats per minute. Guglielmo and colleagues¹¹ reported that the supplemental Stabident IO injection of 1.8 mL of either 2 percent lidocaine with 1:100,000 epinephrine or 2 percent mepivacaine with 1:20,000 levonordefrin resulted in a mean increase in heart rate of 23 to 24 beats per minute (as measured with a pulse oximeter) in 80 percent of their subjects. Stabile and colleagues¹³ found that the supplemental IO injection of 1.8 mL of 1.5 percent etidocaine with 1:200,000 epinephrine resulted in a mean heart rate increase of 32 beats per minute (as measured with a pulse oximeter) in 90 percent of their subjects. Generally, all these studies showed that the heart rate returned to baseline readings within four minutes in most patients. Therefore, injection of anesthetic solutions containing vasocon-strictors, using either the Stabident or X-tip systems, would result in a transient heart rate increase as has been recorded in previous studies of IO injections.

While the heart rate increase with the Stabident or X-tip IO injection of 2 percent lidocaine with 1:100,000 epinephrine likely would be noticed by the patient, it would not be clinically significant in most healthy patients.¹⁴ Replogle and colleagues¹⁴ addressed the clinical significance, cardiovascular effects and contraindications to the use of vasoconstrictors in IO injections. In patients whose medical condition or drug therapies suggest caution in administering anesthetic solutions containing epinephrine or levonordefrin, 3 percent mepivacaine would be an alternative for IO injections.^15,16

The Stabident and X-tip manuals^5,6 state that there is a lack of lip anesthesia when the IO injection is given. Lip numbness subjectively occurred in 100 percent of the Stabident injections and in 94 percent of the X-tip injections. Replogle and colleagues³ and Coggins and colleagues² also reported lip anesthesia when using 1.8 mL of 2 percent lidocaine with 1:100,000 epinephrine in a primary Stabident injection of the mandibular first molar. Klein and colleagues¹⁷ demonstrated with computer tomography that a Stabident injection of 1.4 mL of a mixture of lidocaine with a radiological contrast medium, distal to the mandibular first molars in dogs, showed intramedullary deposition with considerable extravasation of solution from the mental foramen. This effect may occur in humans as well and thereby account for the lip numbness (mental nerve anesthesia) in the current study.

Concerning the ease of perforation, most Stabident perforations were rated as easy (76 percent of the injections). The subjective impression the operator experienced during a difficult perforation (24 percent incidence) was that the bone felt more dense or thicker than normal. For the X-tip perforation, easy perforations were recorded in 78 percent of the perforations. There were no statistical differences between the two techniques. Therefore, even though the X-tip perforation was performed in a more apical location, the two systems were comparable clinically in terms of ease of perforation. None of the perforators broke in either technique—that is, there was no metal fracture. Other authors^2,3,9,11 also reported a lack of perforator breakage with the Stabident system.

Concerning the ease of guide sleeve removal with the X-tip system, most were rated as easy (68 percent of the injections). While difficult removal (32 percent incidence) was based on time, it is worth mentioning that in approximately five to seven subjects (12–17 percent), guide sleeve removal required both moderate effort and time. In one subject, the guide sleeve separated from the plastic sheath and a 3-mm metal segment projected from the bone. The principal investigator removed it with Stieglitz forceps. This was the most difficult removal among those performed in this study. It is possible that the difficult removals were related to bone density at the apical location. Future studies may determine if the injection site’s location in the oral cavity affects the difficulty of guide sleeve removal.

No subjects reported symptoms of a pulpal nature postoperatively, and all subjects who received the IO injection at the first appointment had similar baseline pulp test readings at the subsequent appointment. Other authors^2,3,7,9,10 have reported similar results.

	CONCLUSION

TOP ABSTRACT SUBJECTS, MATERIALS AND METHODS RESULTS DISCUSSION CONCLUSION REFERENCES

 
The findings of our study indicate that when pulpal anesthesia is required in a clinical procedure involving asymptomatic mandibular first molars, both the Stabident and X-tip intraosseous anesthetic systems using 1.8 mL of 2 percent lidocaine with 1:100,000 epinephrine will provide quick onset of anesthesia (within two minutes) and an initial high rate (93 percent) of anesthesia. The adjacent second molar and second premolar had initial success rates of 95 percent and 81 to 83 percent, respectively. However, both techniques resulted in a steady decline of pulpal anesthesia over 60 minutes.

Concerning the ease of perforations, both systems resulted in easy perforations in 76 to 78 percent of the subjects. Removal of the guide sleeve in the X-tip system was rated as easy in 68 percent of the injections. Both systems resulted in a high rate of lip anesthesia (94 to 100 percent).

Eighty-five percent of patients with the Stabident injection and 93 percent of patients with the X-tip injection noticed (subjectively) a transient increase in heart rate (palpitations).