It is clinically well known that the additive adrenaline improves the anesthetic potency, increases the duration of action, and decreases the risk of systemic toxicity of local anesthetics. The objectives of this study were to demonstrate experimentally the effects of adrenaline on local and serum pharmacokinetics of lidocaine after infiltration anesthesia. Two percent ¹⁴C-lidocaine with and without 10 µg/ml of adrenaline was injected into the palatal mucosa of rats and radioactivity in the maxilla and serum was sequentially and quantitatively measured.

This study was approved by the Animal Experiment Committee of The Nippon Dental University, School of Life Dentistry at Tokyo, and all procedures were performed according to the prescribed regulations.

After the injection of 20 µl of 2% ¹⁴C-lidocaine and 2% ¹⁴C-lidocaine with 10 µg/ml of adrenaline into the right palatal mucosa proximal to the first molar (Fig. 1), radioactivity (dpm) in the maxillary tissue was measured 2, 5, 10, 20, 30, 40, 50 and 60 minutes after the injection (n = 5). The concentration of lidocaine (ng/mg tissue wet weight) was calculated from dpm. Autoradiograms of frontal sections of the maxilla including the injection site were analyzed visually and quantitatively 2, 20, 40 and 60 minutes after the injection to demonstrate the frontally infiltrated area of lidocaine and the amount of lidocaine (n = 5). The radioactivity in the serum was measured from 2 to 720 minutes after the injection of 2% ¹⁴C-lidocaine with and without 10 µg/ml of adrenaline (n = 7). Radioactive substances extracted from the maxilla and serum 60 minutes after the injection were analyzed by thin layer chromatography (TLC) (n = 4). The effect of 2% lidocaine with and without 10 µg/ml adrenaline on the lip blood flow was observed by laser Doppler flowmetry (n = 4).

The lidocaine concentration in the palatal mucosa (Fig. 2A, B) and maxillary part (Fig. 2C, D) 2 minutes after the injection of lidocaine with adrenaline was more than twice that when injected alone. The increasing tendency of concentration caused by additive adrenaline was also confirmed in the incisive part (Fig. 2E, F), palatal part (Fig. 2G, H) and maxillary nerve (Fig. 2I, J). The autoradio-graphic analysis showed that lidocaine infiltrated into a wide area covering the palatal mucosa on the right and left sides and the ethmoidal sinuses (Fig. 3). When adrenaline was added, the lidocaine concentrations 2, 20, and 40 minutes after the injection were 1.8, 2.1, and 1.7 times higher respectively than those when administered alone (Fig. 4). The lidocaine concentration in the serum reached the maximum value at 90 minutes after the injection. The serum lidocaine concentration after the injection of lidocaine with adrenaline was significantly lower from 2 to 50 minutes and higher after 60 minutes than that when injected alone (Fig. 5). It was confirmed by TLC that more than 70% of the radioactive substances detected in the maxillary tissue and serum within 60 minutes after the injection was authentic lidocaine (Fig. 6A, B). The upper lip blood flow increased from 15 to 55 minutes after 2% lidocaine injection, and decreased from 10 to 45 minutes after 2% lidocaine with 10 µg/ml of adrenaline (Fig. 7).

The role of dental anesthesiologists is not only systemic management and pain control of dental patients, but also medical emergency treatment of outpatients or inpatients. We have accumulated medical emergency records since April 1988. In previous reports about medical emergencies, Agata analyzed the records from April 1988 to March 1996, and Kubo analyzed those from April 1996 to March 2003. These reports suggest that the important factors are early detection of abnormal conditions and appropriate application of emergency care. In this study, we analyzed the medical emergency cases from April 2003 to March 2010, and compared them with previous studies.

We retrospectively analyzed 205 medical emergency cases of outpatients managed in the Department of Dental Anesthesiology, Tokyo Dental College, Chiba Hospital from April 2003 to March 2010.

Their ages ranged from 2 to 84 years old, and the most frequent age range and gender was females in their twenties (Fig. 1). The incidence of medical emergencies among the outpatients was 0.012% (205/1,721,310 cases) (Table 1). These cases occurred frequently during dental treatment (136 cases) and more than half of them were accidental ingestion cases including suspicious cases (95 cases). The most frequently ingested items were metal inlays and crowns. The second-most frequent medical emergencies were vasovagal reflex (44 cases). On the other hand, some critical cases occurred such as hypoglycemia (6 cases), angina pectoris (2 cases), local anesthetic intoxicity (1 case), and pulmonary aspiration (1 case) (Fig. 2).

Compared to the previous report in our hospital from April 1996 to March 2003, a small increase in those incidents was observed. In that report, the incidence of medical emergencies was 0.007% including 5 cases of accidental ingestion. In this study, accidental ingestion cases had increased (95 cases). The establishment of a system for reporting emergency cases in our hospital in 2003 may in part explain this increase (Fig. 6). On the other hand, there were no differences among those incidents except for accidental ingestion cases between our series of reports (April 1996 to March 2003: 0.0066%, April 2003 to March 2010: 0.0063%).

We report on a patient who was diagnosed as myotonic dystrophy (MyD) when aspiration pneumonia and respiratory failure occurred after general anesthesia for maxillo-mandibular osteotomy.

The patient was 20 years old, female, 159.4 cm tall and weighed 42.7 kg. Under a diagnosis of open bite and narrow upper arch, maxillo-mandibular osteotomy and genioplasty were scheduled. In the preoperative screenings, creatine kinase was slightly higher than normal (347 U/l and 423 U/l) and a slight restrictive ventilation defect (% VC: 77.8%) was found. When she had undergone transverse distraction osteogenesis under general anesthesia at 16 years old, there had been no other postoperative complications except for slightly-delayed emergence.

On the operation day, atropine sulfate 0.4 mg and pethidine hydrochloride 40 mg were administered as premedications. General anesthesia was maintained with TIVA (propofol, remifentanyl hydrochloride and rocuronium bromide), and the course of anesthesia was uneventful. Following the surgery, adequate spontaneous breathing was observed after a short while and extubation was achieved as usual. For safety, we inserted a nasal airway from the right nostril before leaving the surgery room. At that moment, no problem was observed. However, during the night of the first postoperative day, Spo₂ dropped to 70%, but it improved after re-inserting the nasal airway, suctioning and supplying oxygen. The next day, a chest X-ray suggested pneumonia. Spo₂ dropped again to 70% and blood gas analysis showed severe hypoxemia (pH 7.423, Paco₂ 44 mmHg, Pao₂ 36 mmHg), so she was transferred to the trauma and acute critical care center of Osaka University Hospital. At the hospital, she was diagnosed as aspiration pneumonia, and this postoperative complication was thought to have been caused by myotonic dystrophy (MyD).

Fibrous dysplasia is a disorder characterized by excessive proliferation of bone-forming mesenchymal cells. We describe a case of fibrous dysplasia that caused difficult laryngoscopy and failed nasotracheal intubation.

A 32-year-old female who presented with polyostotic fibrous dysplasia of the costal bones, left maxilla and mandibula with facial asymmetry was scheduled for conservative osteotomy of the mandibula under general anesthesia (Fig. 1, ​,2).2). On physical assessment, the patient had a Class II Mallampati view with two finger width of mouth opening and could not thrust her jaw forward. Preoperative computed tomographic (CT) images, multislice three-dimensional CT images and magnetic resonance images (MRI) showed osteosclerosis and ground glass appearance of the costal bones and the left side of the skull including the maxillary bone, mandibular bone and zygomatic bone. There was obstruction of the left paranasal sinus and nasal cavity but no significant radiological abnormality of the right nasal cavity (Fig. 3).

Inhalation anesthesia was induced with intravenous propofol (80 mg) and inhalation of 1.5% sevoflurane in oxygen. Following confirmation of mask ventilation, laryngoscopy was attempted. Direct laryngoscopy using a Macintosh blade #3 proved difficult and resulted in impaired insertion of the tip into the pharyngeal space, but indirect laryngoscopy was achieved using the GlideScope video laryngoscope (GVL®3). The endotracheal tube was inserted into the trachea via the mouth, and then nasotracheal intubation was attempted. The 8.0 mm ID polyvinyl chloride endotracheal tube could not be passed into the right nostril, so a 7.0 mm ID tube was substituted and inserted into the trachea. High airway resistance was observed and the tube was removed. The part of the tube that was positioned in the nasal cavity was apparently compressed. Then a 7.0 mm ID partially reinforced tube for nasotracheal intubation was inserted into the trachea, but the cuff did not inflate due to compression of the lumen. Nasotracheal intubation was aborted, and volume reduction surgery of the mandible proceeded uneventfully under orotracheal intubation.

Background: Treatment at an early stage of trigeminal nerve injury is likely to be effective, and yet referrals to a specialist are delayed. This is because practitioners have no simple method of evaluating nerve injury without special devices and definite criteria. We tried to evaluate the extent of nerve injury by the patient's impression of recovery and the presence of abnormal sensation.

Method: Twenty-seven patients who visited the Pain Clinic in Kyushu Dental College Hospital with complaints of paralysis of perception after tooth extraction were enrolled in this study. The patient's impression of recovery, electric detection threshold (EDT), and abnormal sensation in the mental region were evaluated at the post-traumatic period (PTP), 1 day (1 D), 1 week (1 W), 2 weeks (1 W), 1 month (1 M), and three months (3 M). The impression of recovery was evaluated by comparing the symptom at PTP1D with that of the evaluation day and using a Numeric Rating Scale (NRS). NRS was divided into four stages of not cured (0), slightly cured (1), almost cured (2) and cured (3). The subjects were divided into two groups: NRS 2 or 3 (Satisfactory Group (Group S), n = 12), and NRS 0 or 1 at PTP 3 M (Non Satisfactory Group (Group NS), n = 15).

Results: According to EDT, Group S showed better recovery than Group NS. The injured trigeminal nerve in Group S had completely recovered at PTP1M. It is considered that the extent of nerve injury in Group S was not severe (Fig. 1). The existence of abnormal sensation in Group NS was significantly higher than in Group S at each evaluation time. The existence of abnormal sensation shows that the extent of nerve injury is serious (Fig. 2). Group S recognized recovery significantly at each evaluation time compared with Group NS (Fig. 3). The impression of recovery could be used as a criterion for prognostic prediction.

Conclusion: It may be possible to predict the prognosis after trigeminal nerve injury based on the patient's impression of recovery and abnormal sensation. The patients in Group NS did not recognize recovery and had abnormal sensation at the evaluation time of one week after trigeminal nerve injury. Therefore, patients who cannot recognize recovery and/or who have abnormal sensation at one week after nerve injury have a low possibility of natural recovery and should be referred to a specialist.

A sensitive gag reflex in dental patients can be disruptive to dental treatment. Gagging is evoked by psychological factors, physiological factors, or both of them. When a psychological factor is associated with sensitive gag reflex, intravenous sedation is recommended to suppress gag reflex during treatment. However, the relationship between occurrence of gag reflex and sedation level is not known. The Bispectral Index (BIS) has been shown to predict the level of sedation. We investigated whether BIS is a useful indicator for gag reflex.

Fourteen patients (17 cases) with a past history of severe gag reflex during dental procedures were sedated using 0.05 mg/kg midazolam followed by propofol intravenously based on target-controlled infusion (TCI) toward a clinical optimum sedation level (according to Modified Observer's Assessment of Alertness/Sedation Scale (OAA/ S) 3). Intravenous sedation was maintained with propofol using a TCI pump to keep the initial sedative state (according to the initial BIS score) and a dose of propofol was arranged to the same sedative level or in order to suppress gag reflex. BIS score, Cepc and OAA/S scale were monitored continually during the procedures and recorded at 5-minute intervals.

The average BIS score was 73.2 ± 8.38 during operation and propofol was administered at 1.02 ± 0.415 µg/ml to maintain a clinically optimum sedation level (Table 2).

Gag reflex occurred in 7 cases (7 of all 148 points) during dental treatments, which were impression, cavity preparation, endodontics, mouth gag insertion and suction. BIS scores at gag reflex were between 70 and 97; these scores were more than the initial BIS scores (Table 3). The cut-off index of BIS at gag reflex was over 75 (p<0.045) (Table 4). There was no relation between dental procedure and BIS score to prevent gag reflex (Table 5). This study suggested that sedation at a BIS score of less than 75 prevented gag reflex during the dental treatments.