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.

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.

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Objective(s). The major challenge encountered to decrease the milliamperes (mA) level in X-ray imaging systems is the quantum noise phenomena. This investigation evaluated dose exposure and image resolution of a low dose X-ray imaging (LDXI) prototype comprising a low mA X-ray source and a novel microlens-based sensor relative to current imaging technologies. Study Design. A LDXI in static (group 1) and dynamic (group 2) modes was compared to medical fluoroscopy (group 3), digital intraoral radiography (group 4), and CBCT scan (group 5) using a dental phantom. Results. The Mann-Whitney test showed no statistical significance (α = 0.01) in dose exposure between groups 1 and 3 and 1 and 4 and timing exposure (seconds) between groups 1 and 5 and 2 and 3. Image resolution test showed group 1 > group 4 > group 2 > group 3 > group 5. Conclusions. The LDXI proved the concept for obtaining a high definition image resolution for static and dynamic radiography at lower or similar dose exposure and smaller pixel size, respectively, when compared to current imaging technologies. Lower mA at the X-ray source and high QE at the detector level principles with microlens could be applied to current imaging technologies to considerably reduce dose exposure without compromising image resolution in the near future.

The cervical plexus (CP) has haunted clinicians and scientists for several years. Anatomists, general dentists, endodontists, periodontists, neurologists, pain physicians, anaesthesiologists, researchers and a variety of surgeons have been frustrated by the cranial nerves "accessory innervation" (AI) from the CP. Indeed, AI by the CP likely contributes not only to failed dental anaesthesia in the adult posterior mandible but also to a vast array of unusual head and neck clinical presentations, pain syndromes and postoperative complications. It is certainly disconcerting to fail to induce profound anaesthesia when a patient is in the chair expecting a painless procedure. From an estimated 300 million anaesthetic cartridges used annually in the US alone, anaesthetic fails in 13% (n=39 million) injections overall, with 88% (n=34.32 million) occurring with the inferior alveolar nerve (IAN) block (1). In endodontics, it has been reported that as much as 45% of IAN block fails, especially in mandibular molars with symptomatic irreversible pulpitis (1). The IAN block has the highest failure rate not only in dental local anaesthesia but also among all local anaesthetic blocks in medicine (2). Previous research illustrated several explanations for this, including the central core theory, lowered pH of inflamed tissues, nerve altered resting potentials, anaesthetic-resistant sodium channels, anaesthetic composition, recreational drugs, Ehlers-Danlos syndrome and having red hair. Accessory mental nerves and mylohyoid nerve branches have also been implicated in anaesthetic failures (3).The AI to the IAN theory states that incidents of unsuccessful anaesthesia may result from innervations of the adult mandible arising from the CP in addition to the auriculotemporal, buccal, mental, incisive, mylohyoid and lingual nerves. This theory had not been universally accepted due to the lack of anatomical evidence demonstrating that the CP nerve can extend to the mandible (4). Previous research highlighted that the difficulty in identifying such superficial branches during dissections could be attributed to the small size and thickness of the mandibular accessory foramina and CP, as well as to the dissection technique used (3). However, a three-dimensional nerve mapping method investigation through human cadaver microdissection, tissue transparency, and Sihler's technique for nerve staining presented the first evidence recorded in the literature of the transverse cervical nerve (TCN) from the CP entering the mandible (3). In animal models using primates and cats, it was revealed that the CP entered the mandible and provided direct innervation to the teeth and dental pulps (1, 3, 4). In addition to previous clinical evidence since the AI to the IAN theory introduced by Nevin, 1922, contemporary microdissection technology results confirmed that the CP supplied AI to the inferior border of the posterior mandible in 97% of cases through the TCN and great auricular nerve (4, 5).On the basis of a systematic literature review, human cadaver ...