Accessory innervation (AI) may account for the persistent sensation perceived after successful mandibular anesthesia in the adult patient. The purpose of this systematic review was to record the quality of evidence pertaining to the cervical plexus (CP) AI in dental anesthesia.
Electronic and manual searches were conducted using Ovid and Medline of articles published from 1922 to March of 2015. Studies written in any language were included as long as they involved: (i) humans, animals, and/or cadavers AND (ii) anatomical and/or research anesthetic-technique approaches and/or clinical approaches. Exclusion criteria were (i) maxillary buccal infiltration, (ii) no abstract/paper available, (iii) studies that do not comprise the description of the branches of the CP branches in dentistry and (iv) duplicated articles. The articles were reviewed and graded by levels of evidence (LOE) through a methodological scoring index (MSI).
Forty-four out of 185 papers fulfilled the inclusion criteria. One randomized control trial, 3 comprehensive reviews, 1 cohort study, 5 case series/reports, 16 poor-quality cohort and case series/reports and 18 reviews/case, reports/expert opinions were found. Of the 44 publications, there were 4 LOE 1, 1 LOE 2, 5 LOE 3, 20 LOE 4 and 14 LOE 5 studies.
The MSI helped to classify papers LOE in a standardized and objective approach. The objective evidence quality occurrence recorded was found to be LOE 4 (n = 20) > LOE 5 (n = 14) > LOE 3 (n = 5) > LOE 1 (n = 4) > LOE 2 (n = 1). The anatomy of the CP needs to be reexamined and understood in the anatomical literature.

Unsuccessful anesthesia of the inferior alveolar nerve (IAN) may be due to supplementary innervations of mandibular molars from other branches, namely the cervical plexus (CP). The purpose of this prospective, randomized, double-blind, controlled trial was to determine the effectiveness of an intraoral cervical plexus anesthetic technique (ICPAT) in mandibular molars with symptomatic irreversible pulpitis (SIR) when the IAN and lingual nerve (LN) blocks failed, and to provide a description of the technique. Forty patients diagnosed with SIR received IAN and LN block anesthesia prior to treatment. After clinical signs of anesthesia, patients were subjected to an electrical pulp test (EPT) at 2-min cycles for 10 min post-injection. The anesthesia was considered unsuccessful if there was a positive EPT response ten minutes following profound lip numbness. The experimental group (n = 20) were administered 2% Lidocaine with 1:100,000 epinephrine using the ICPAT. The control group (n = 20) were administered 0.9% sterile saline using the ICPAT. Success was defined as no response on two consecutive readings from an EPT. In the experimental group, 60% of subjects showed successful anesthesia, whereas none of the subjects in the control group had successful anesthesia. A multiple logistic regression analysis showed that the anesthesia success rate using the ICPAT method was significantly higher (P < 0.05) than in the control group, irrespective of molar tooth type. The ICPAT method may be useful as a supplementary anesthetic technique for mandibular molars with SIR in subjects whom the IAN and LN blocks do not provide adequate anesthesia.

BACKGROUND: The inferior alveolar nerve block (IAN) is the most frequently used mandibular injection technique for achieving local anesthesia in endodontics. Supplemental injections are essential to overcome failure of IAN block in patients with irreversible pulpitis.
OBJECTIVE: To evaluate the anesthetic efficacy of X-tip intraosseous injection (2% lidocaine with 1:80,000 epinephrine) in patients with irreversible pulpitis in mandibular posterior teeth when conventional IAN block failed.
METHODS: Thirty emergency patients diagnosed with irreversible pulpitis in a mandibular posterior tooth received an IAN block and experienced moderate to severe pain on endodontic access or initial instrumentation. The X-tip system was used to administer 1.8 ml of 2% lidocaine with 1:80,000 epinephrine. The success of X-tip intraosseous injection was defined as none or mild pain (Heft-Parker visual analogue scale ratings < 54 mm) on endodontic access or initial instrumentation.
RESULTS: Ninety-three percent of X-tip injections were successful and 7% were unsuccessful. Discomfort rating for X-tip perforation: 96.66% patients reported none or mild pain, whereas 3.34% reported moderate to severe pain. For discomfort rating during solution deposition, 74.99% patients reported none or mild pain and 24.92% reported moderate to severe pain. Ninety-six percent of the patients had subjective/objective increase in heart rate.
CONCLUSIONS: Supplemental X-tip intraosseous injection using 2% lignocaine with 1:80,000 epinephrine has a statistically significant influence in achieving pulpal anesthesia in patients with irreversible pulpitis.

The inferior alveolar nerve block (IANB) has the highest failure incidence of any dental anesthetic technique. Many authors have outlined potential reasons for these failures in permanent lower molars, including accessory innervations from the mylohyoid and mental foramen. However, the potential accessory innervation of posterior mandibular teeth from the transverse cervical nerve (TCN), a branch of ventral rami from the C2-C3 spinal nerves from the cervical plexus (CP), has been difficult to assess as a result of the small size and thickness of the mandibular accessory foramina and nerve branches, as well as due to the dissection technique performed. The goal of this study was to identify and trace the CP branches from fresh human cadaver tissue samples using the Sihler\'s technique. Two fresh human cadaver samples were used. Samples were fixed in neutralized formalin, macerated in potassium hydroxide, decalcified in acetic acid, stained in Ehrlich\'s hematoxylin, destained in acetic acid, and cleared in glycerin. Both specimens skin was dissected. The Sihler\'s technique delineated all nerves three dimensionally and helped to disclose structures of small size and thickness. The TCN from the CP, stained in blue, innervated the posterior mandible in one of the two samples. These results confirmed that the CP may supply accessory innervation to the inferior border of the posterior mandible through the TCN. These findings illustrate variations of anatomy that may account for IANB failures in posterior mandibular teeth and allows for clinical decisions for implementing supplemental anesthetic techniques.