The needle is inserted along the long axis, at a 30-degree angle, of the mesial or distal root for single rooted teeth and on the mesial and distal roots of multi-rooted teeth. Bevel orientation toward the root provides easier advancement of the needle apically. When the needle reaches between the root and crestal bone, significant resistance is experience. Anesthetic deposition is recommended at 0.2 mL, per root or site, over minimally 20 seconds. For its success, the anesthetic must be administered under pressure. It must not leak out of the sulcus into the mouth. Withdraw needle for minimally 10–15 seconds to permit complete deposition of solution. This can be slower than other injections as there is pressure build-up from the anesthetic administration. Blanching of the tissue is observed and may be more evident when vasoconstrictors are used. It is caused by a temporary obstruction of blood flow to the tissue.Syringes:

Standard syringes can be used. The intraligamentary syringe offers mechanical advantage by using a trigger-grasp or click apparatus to employ a gear or lever that improves control and results in increased force to push the anesthetic cartridges rubber stopper forward for medication deposition with greater ease. C-CLADs (computer controlled local anesthetic delivery devices) can be used. Its usage of computer microprocessors allows for control of fluid dynamics and anesthetic deposition. This minimizes subjective flow rates and variability in pressure.
Presence of systemic health problemsILI utilization is expected to increase because dental patients prefer fewer soft tissue anesthesia and dentists aim to reduce administration of traditional inferior alveolar nerve block (INAB) for routine restorative procedures.Injection methodology: The periodontal ligament space provides an accessible route to the cancellous alveolar bone, and the anesthetic reaches the pulpal nerve via natural perforation of intraoral bone tissue.Advantages of ILI over INAB: rapid onset (within 30 seconds), small dosage required (0.2-1.0 mL), limited area of numbness, lower intrinsic risks such as neuropathy, hematoma, trismus/jaw sprain and self-inflicted periodontal tissue injury, as well as decreased cardiovascular disturbances. Its usage as a secondary or supplementary anesthesia on the mandible has reported a high success rate of above 90%.Disadvantages: Risk of temporary periodontal tissue damage, likelihood of bacteriemia and endocarditis for at-risk populations, appropriate pressure and correct needle placement are imperative for anesthetic success, short duration of pulpal anesthesia limits the use of ILIs for several restorative procedures that require longer duration, postoperative discomfort, and injury on unerupted teeth such as enamel hypoplasia and defects. Technique description:

All plaque and calculus to be eradicated, optimally before the operative visit to assist gingival tissue healing. Before injection, disinfect gingival sulcus with 0.2% chlorhexidine solution. Administration of soft tissue anesthesia is recommended prior to ILI administration. This helps to enhance patient comfort. Needle gauges of sizes 27-gauge short or 30-gauge ultra-short needle are usually utilized.