Table 2.

Outcomes and limitations of the studies included for the final analysis

Study	Main findings (outcomes)	Limitations
de Souza Amorim et al.12 (2020)	“The liposomal formulation was able to induce adequate anesthesia in palatal mucosa during dental extraction, avoiding the local anesthetic infiltration. For the first time, a topical formulation allowed upper molars surgical removal without injection of any local anesthetic agent into palatal mucosa in adults.”	• The study used a minimum sample size of 40 people. • The females made up 80% of the sample and there was minimal pharmacokinetics of drugs explanation.
Arapostathis et al.8 (2010)	“Our study found that children aged 6 to 11 years preferred the traditional needle injection over the INJEX method. While we did not find gender or age differences, it is possible that these might be found in children of other ages.”	• Relatively small sample size • The age and gender were not related to the acceptance or preference of either anesthesia method. • The sample was restricted to children who had never received anesthesia before, and who was also previously rated as non-fearful. • Additional studies should be conducted.
Bose et al.6 (2019)	Cooling the soft tissue site significantly decreased the perception of pain (both infiltration and block anesthesia) in children during routine dental procedures. It proved to be an easy, reliable, and cost-effective method of local anesthetic administration.	• Relatively small sample size • The reliability of the results could have been further improved by videotaping the injection procedure and allowing a third investigator to evaluate it. • Could have Increased the patient compliance and improved the quality of care. • All the clinicians should be made familiar with this strategy.
Dabarakis et al.5 (2007)	The INJEX technique exhibits all the advantages of jet anesthesia mentioned in this study. Although it is not a panacea, it is a useful adjunct to local anesthesia. The jet injection technique may be particularly beneficial in pediatric dentistry, where its use would reduce fear of needle view and contribute to limited dose administration, which is an important issue in the local anesthesia in young children.	• Relatively small sample size • The results are not reliable because there are no supportive tables or figures for evidence.
Gupta et al.3 (2018)	“..It can be concluded under the limits of study that needleless jet device (Madajet) and topical anesthetic gel (EMLA) was effective in controlling pain and was well accepted and preferred by the patient.”	• Minimum sample size has been used. • No sample power calculation. • The study relied on pain perception which is subjective and cannot be measured without bias.
Makade et al.4 (2014)	“This technique may be particularly beneficial in reducing fear from needle view and contribute to limited dose administration which is proved to be beneficial for patients suffering from systemic disorders.”	• Relatively small sample size • Additional studies should be conducted. • There were no postoperative complications reports.
Ocak et al.10 (2020)	“Accordingly, the pain or discomfort score of the INJEX method during tooth extraction was significantly higher. Jet injection with the INJEX was not found to be effective for local infiltrative anesthesia, especially teeth extractions. It may be more acceptable when used previous to classical local infiltration anesthesia by patients. The main problem with jet injection was the “pop” sound when the INJEX device was pressed, and also inadequate supplying the anesthesia.”	• Relatively small sample size • Has no evident randomization in the methodology. • The study relied on pain perception which is subjective and cannot be measured without bias. • There needs to be more information regarding the use of INJEX for extractions, not only topical anesthesia prior to extraction, which veered away from the aim of the study.
de Oliveira et al.7 (2019)	The two anesthetics methods did not differ concerning pain experienced during the anesthesia. The anesthetic latency was 2 minutes for all subjects, and the traditional infiltration anesthesia resulted in a longer anesthetic duration when compared with the needleless jet injection.	• Relatively small sample size • Additional studies should be conducted.
Kumar9 (2015)	Although the traditional aspirating syringe is the most common method by which local anesthetics are administered, newer technologies have been developed that can assist the dentist in providing enhanced pain relief with reduced injection pain and fewer adverse effects.	• The results are not reliable because there are no supportive tables or figures for evidence. • Additional studies should be conducted.
Szmuk et al.11 (2005)	The results of this study show that there are various methods used to alleviate pain during dental procedures and that they have to be clinically and cost-effective, needle-less, and ultra-rapidly acting without causing pain or producing frightening sounds when triggered.	• Relatively small sample size • No supportive tables or figures for evidence.