Effective pain control in surgical procedures still remains a challenge for all dental professionals. The optimum profoundness of anesthesia is limited in the mandible area [1]. Wong [2] revealed in his systematic review that inferior alveolar nerve block injection (IANBI) has a success rate of only 69%. Thus, there is a 15% to 20% failure rate associated with IANBI technique. Several patient-related idiosyncrasies contribute to IANBI failure, including the complicated anatomical distribution of the nerve, and the thickness of the cortical plate of the mandible and the zygomatic process bone, which can also prevent the diffusion of the anesthetic agent, leading to failure of the anesthesia [2].

Table 2 shows the subjective onset, objective onset and latency of the anesthetic agent from both techniques. CAIOI provided faster subjective onset (35.40 ± 13.84 sec) than IANBI (65.60 ± 24.38 sec) (results are statistically significant. As for the objective onset, CAIOI provides faster objective onset (90.6 ± 45.21 sec) than IANBI (136.00 ± 66.99 sec), P < 0.001. Table 2 also shows the latency of the anesthetic agent from both techniques. The CAIOI (243.56 ± 38.02 sec) has shorter duration of action than IANBI (291.6 ± 40.28 sec) despite the fact that 4% articaine was used for both techniques (P < 0.001).

EPT testing showed very similar results for both techniques, both for pre-injection EPT and post-injection EPT (P > 0.05) (Fig. 3).

Patients reported feeling more comfortable receiving intraosseous injection with Quicksleeper® than IANBI with conventional syringe. Nonetheless, the data calculation does not show any significant differences between the two techniques (P > 0.05).

Even when additional anesthetic agent was required, patients reported less pain during the operation as shown in Table 3. The statistical analysis did not reveal any significant differences between pain reported from either type of injections (P = 0.408), or on the success rate of anesthesia for the mandibular third molar operation. IANBI had a higher success rate than CAIOI, (72% compared to 68%) but the difference is not statistically significant (P > 0.05) (Table 3).

In a previous study, Gonzales-Castro et al. concluded that the use of CCLAD gives patients more comfort and less anxiety during anesthetic administration [15], while failure of IANBI is the main reason for needing supplementary IOI injection.

Patients report immediate onset, as described in several studies by Daniel Dunbar et al. [16], Replogle et al. [17], Jensen et al. [18], Beneito-Brotons et al. [19] and Prohic et al. [20]. Further reviews show that IOI produces a desirable success rate and can be used as the primary injection technique to anesthetize mandibular molars.

We studied CAIOI versus IANBI, using a 5th generation Quicksleeper® with Bluetooth pedal for the CAIOI, an innovative technology.

Smaïl-Faugeron et al. performed a controlled trial study that compare pain induced by IOI with Quicksleeper versus infiltration with conventional syringes in pediatric patients. The result showed that the use of the Quicksleeper® system is significantly advantageous for dental practitioners. It required less pressure and a lower amount of anesthetic agent. Their study also indicated that Quicksleeper® induced less pain and less anxiety than the conventional anesthetic technique, and that is beneficial when treating children and adolescent patients that require their oral health care [14].

Similarly, in 2012 another study by Beneito-Brotons et al. on intraosseous anesthesia with CAIOI system versus conventional nerve block anesthesia showed that IOI with Quicksleeper® caused less discomfort than IANBI. It also proved that the onset of anesthesia on soft tissue was significantly faster with Quicksleeper® as it took 35–90 sec for patients to feel the numbness, which is different from the conventional IANBI method. In that study, 69.7% of patients preferred Quicksleeper® injection compared to 23.3% that chose the conventional IANBI technique when inquired [19].

Terrer et al. compared osteocentral (intraosseous) anesthesia and local regional block on inferior dental nerves in 39 patients. Twenty-one patients were anesthetized by CAIOI with Quicksleeper® and 19 patients were injected using IANBI. The time of anesthetic onset was 2.9 min for Quicksleeper® injection and 8.1 min for IANBI respectively. In that study, 18 of 21 patients could be treated immediately after Quicksleeper® injection, a success rate of 86% succeeded. Only five patients could undergo dental treatment after the first IANBI, while 11 patients required a second injection and two needed a third injection [21].

Cabasse et al. studied 39 children and adolescents treated for molar and incisor hypomineralization by using CAIOI with Quicksleeper® injection. Around 93.5% of the patients achieved full anesthesia. Failure was related to the density of the bone, when the needle could not penetrate into the spongy bone [22].

The study of Couderc et al. followed 25 patients who came for emergency treatment at the dental hospital. Most of the patients were diagnosed with pulpitis, either reversible or irreversible. The study followed those patients who fail to control the pain after the first attempt. The supplementary techniques used were intraosseous injection with Quicksleeper® or intraligamentary injection. That study reported that all patients who received additional injection with Quicksleeper® were able to complete the treatment and required less amount of anesthetic agent [23].

Chang and colleagues [24] conducted a study using CCLAD as the primary anesthesia technique in chronic periodontitis patients who required surgical debridement. The result indicated that the mean VAS pain score in patients treated with the CCLAD procedure was significant lower than the group that received conventional injection.

A case report study by Han et al. [25] and Kim et al. [26] showed that none of the patients that received a Quicksleeper® injection prior to their periodontal surgery claimed discomfort after the treatment despite undergoing multiple root planning on both the mandible and the maxilla.

A split-mouth study by Demir and Ataoglu [27] on surgical removal of impacted mandibular third molars reported that more than 60% of the patients showed high level of satisfaction after receiving injection with Quicksleeper®. They reported significantly less pain, less tissue numbness, and a faster onset of anesthesia.

In our study patients reported onset of numbness at 35.40 ± 13.84 sec in CAIOI and 65.60 ± 24.38 sec in IANBI (P < 0.05). The subjective onset in our study is longer than previously reported by Beneito-Brotons et al. in 2012 [19]. In that study, it took 0.48 ± 0.32 min, average 28 sec for patients to realize the numbness sensation after using Quicksleeper®. That subjective onset is significantly shorter than the one reported by Terrer et al. [21] (2.9 minutes). In another study, Kiattavorncharoen et al. [12] reported a subjective onset of 5.8 ± 3.5 min, and an objective onset was 14.6 ± 10.6 min, which are longer than in our current study. The reason for that may be the different injection point used, as they injected at the retromolar trigone area to perform mandibular third molar surgery. In that study the complete loss of numbness in the CAIOI group was at 243.56 ± 38.02 min compared to 291.6 ± 40.28 min for the IANBI group. In comparison, in the previous study by Kiattavorncharoen et al. [12], the soft tissue numbness was shorter than in this study. The different in onset might probably due to the density of the cortical bone in the mandible.

The profoundness of anesthesia has been the object of many discussions. It has been suggested that IOI is not suitable for longer duration of dental treatments such as mandibular third molar surgery. The EPT test after injection showed that the EPT value in the CAIOI group was lower than in the IANBI group but the P-value showed no statistical significance.

In our study, one-third of the cases where CAIOI was used required additional anesthesia during the operation. The requirement of additional anesthesia may result from inadequate effect of IOI. This explains why the hypersensitivity disappeared after an additional minimal amount of articaine was administered using a conventional syringe.

A study by Ozer did not show any significant difference between injections. In contrast, the previous study of Kiattavorncharoen et al. [12] used the previous generation Quicksleeper® and was injected at the interdental papillary bone of the first and second molar by using 4% articaine as their local anesthetic. They mentioned that the CAIOI produced less pain during injection that is parallel to this current result, which shows that IANBI causes discomfort during the needle insertion. However, all study outcomes showed less pain during injection in CAIOI versus IANBI but the differences do not reach statistical significance.

The success rate in this study was 68% in CAIOI group and 72% in IANBI group. The profoundness of anesthesia was sufficient in 32% of the case in CAIOI group, and 36% more cases could be completed with mild sensitivity if intra-pulpal injection was added. The result is similar to the study by Ozer et al. [13], which found that in 70% of the cases when CCLAD was used they were able to complete the surgical removal of third molar, even in those patients who feel sensitivity.

We conclude that the use of CAIOI with Quicksleeper® in mandibular third molar operation could provide faster onset of anesthesia, both subjective and objective, and shorter duration of action than IANBI with conventional syringe. The major drawback of this device is the lack of profoundness of anesthesia. The success rate in these two injections technique is 68% and 72% for CAIOI and IANBI respectively.

In conclusion CAIOI could be an alternative injection technique to perform the operation instead of IANBI with traditional syringe. The researcher recommends further studies to address the weaknesses of this study. Some of the caveats include that the researcher could not blind the patients, as there two different injection techniques despite having turned the Quicksleeper® on when injecting with the conventional syringe. The patients' experience, as well as their anxiety about the removal of the mandibular third molar might have a strong impact on the hemodynamic changes observed during this study.