The entire dental profession mourns the loss of John A. Yagiela, DDS, PhD, an internationally recognized authority on pain and anxiety control in dentistry, who died suddenly on February 22, 2012. John was one of the most brilliant men whom your editor has ever known. We first met soon after the Journal of the American Dental Association published my review of his first pharmacology textbook in 1980, and we subsequently became life-long friends. We traveled with our spouses all over the world to places including Scotland, Germany, France, Israel, New Zealand, Japan, Australia, and South Africa. John was
The aim of this present study was to evaluate the irritative potential of 2 topical anesthetics used in intrapocket anesthesia for periodontal scaling/root planing when applied in subcutaneous tissue of rats. Sixty animals were divided into 4 groups: group 1, saline solution (control); group 2, poloxamer gel (thermosetting vehicle); group 3, lidocaine and prilocaine poloxamer thermosetting gel; group 4: EMLA, a lidocaine and prilocaine dermatological cream. Injections of 2% Evans blue were administrated intravenously into the lateral caudal vein. In order to analyze vascular permeability, the tested substances were injected intradermally. The rats were sacrificed 3, 6, and 9 hours after injection of the substances. The dorsal skin was dissected and removed. The vascular permeability was evaluated by the measurement of area of dye extravasation and the dye was subsequently extracted after immersion in formamide. Statistical analyses were made by ANOVA with Bonferroni's post hoc test and Pearson correlation. The 2 methods to analyze the exudative phase of the inflammatory process showed statistically significant difference among the groups and periods of evaluation (P < .05). Both methods had a significant correlation (P < .0001). Under the tested conditions, the anesthetic agents showed mild initial inflammatory response when implanted in subcutaneous connective tissue.
Dexmedetomidine (DEX) has a minimal respiratory depressive effect, which is beneficial for dentistry; however, it has the disadvantage of permitting an intraoperative arousal response such that the patient appears to be suddenly no longer sedated, and it has a variable amnestic effect. Since midazolam (MDZ) in an appropriate dose has a profound amnesic effect, we investigated whether additional MDZ compensates for the disadvantage of DEX and enables a better quality of sedation. Forty-three subjects were randomly divided into 4 groups. In group 1, MDZ (0.02 mg/kg) was administered intravenously, followed by a dose of 0.01 mg/kg every 45 minutes. After the first dose of MDZ, preloading with DEX (2 µg/kg/h for 10 minutes) was started and maintained with a dosage of 0.5 µg/kg/h. In group 2, MDZ was infused in the same manner as in group 1, followed by preloading with DEX (1 µg/kg/h for 10 minutes) and maintenance (0.3 µg/kg/h). In group 3, MDZ was infused 0.03 mg/kg, and a dose of 0.01 mg/kg was given every 30 minutes; DEX was administered at the same as in group 2. In group 4, DEX was infused using the same method as in group 1 without MDZ. The sedation levels, amnesia, and patient satisfaction were also investigated. Group 2 had a lower sedation level and a poor evaluation during the first half of the operation. Group 4 did not exhibit an amnesic effect at the beginning of the operation. An evaluation of the degree of patient satisfaction did not reveal any differences among the groups. Optimal sedation was achieved through the combined use of MDZ (0.02 mg/kg with the addition of 0.01 mg/kg every 45 minutes) and DEX (2 µg/kg/h for 10 minutes followed by 0.5 µg/kg/h).
We audited the recovery characteristics of 51 patients who had undergone orthognathic maxillofacial surgery at a single center. Patients whose anesthesia had been maintained with intravenous propofol and remifentanil (n = 21) had significantly higher pain scores during the first 4 hours after surgery than those whose anesthesia was maintained with volatile inhalational agents and longer-acting opioids (n = 30) (P = .016). There was a nonsignificant trend towards shorter recovery times in the former group, while there were no differences in early postoperative opioid usage, hemodynamic parameters, or postoperative nausea and vomiting . Given that our data were collected retrospectively and without the ability to control for potential confounders, we interpret the results with caution. Notwithstanding these limitations, we believe this is the first report comparing the effects of different opioid-based anesthetic regimens on early recovery from orthognathic surgery, and we believe this report may be used as the starting point for a controlled study.
The effects of infiltration anesthesia with ropivacaine on the dental pulp are considered to be weak. This may be partly associated with its permeation into the oral tissue. With the objective of investigating the local pharmacokinetics of ropivacaine and lidocaine following infiltration anesthesia, we injected 3H-ropivacaine or 14C-lidocaine to the palatal mucosa in rats, measured distributions of radioactivity in the maxilla, and compared the local pharmacokinetics of these agents. The animals were sacrificed at various times and the maxillas were removed. The palatal mucosa and maxillary nerve were resected, and the bone was divided into 6 portions. We measured radioactivity in each tissue and calculated the level of each local anesthetic (n = 8). Lidocaine diffused to the surrounding tissue immediately after the injection, whereas ropivacaine tended to remain in the palatal mucosa for a longer period. Lidocaine showed a higher affinity for the maxillary bone than ropivacaine. There was a correlation between the distribution level of local anesthetics in the maxillary bone and that in the maxillary nerve. The lower-level effects of infiltration anesthesia with ropivacaine on the dental pulp may be because ropivacaine has a high affinity for soft tissue, and its transfer to bone is slight.
We report an unexpected failed laryngeal mask airway in a patient with unrecognized lingual tonsil hypertrophy (LTH). A 19-year-old obese woman presented for extraction of multiple teeth via intravenous general anesthesia. Surgery was interrupted due to a laryngospasm midway through the procedure. The laryngospasm required the existing laryngeal mask airway to be removed so the patient could be suctioned. Although it is unclear the extent of obstruction caused by LTH, the surgery had to be postponed due to the discovery of enlarged lingual tonsils, which prevented endotracheal intubation. One reason for unexpected difficult airways is attributed to LTH. It is recognized that LTH is more common in patients with obstructive sleep apnea; however, LTH also has an increased prevalence in obese children with prior palatine tonsillectomies or adenoidectomies. Unexpected LTH can complicate general anesthesia by making placement of a laryngeal mask airway difficult. Thus, further research needs to be conducted to gain a deeper understanding on how to reduce the risks presented by LTH during sedation surgeries.
We read with great interest the anesthetic technique of using a gum elastic bougie (GEB) for nasal intubation in a recent issue of Anesthesia Progress. The authors recommend the use of GEB for the first attempt of nasotracheal intubation in patients with a difficult airway. We agree that this is an excellent alternative. We also have found an excellent variation of this method that utilizes a double bougie technique for insertion of a nasotracheal tube if the difficult airway can be secured initially with an orotracheal tube.
Masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) is a new disease entity characterized by limited mouth opening due to contracture of the masticatory muscles, resulting from hyperplasia of tendons and aponeuroses. In this case series, we report what methods of airway establishment were conclusively chosen after rapid induction of anesthesia. We had 24 consecutive patients with MMTAH who underwent surgical release of its contracture under general anesthesia. Rapid induction of anesthesia with propofol and rocuronium was chosen for all the cases. In 7 cases, intubation using the Macintosh laryngoscopy was attempted; however, 2 of those cases failed to be intubated on the first attempt. Finally, intubation using the McCoy laryngoscopy or fiber-optic intubation was alternatively used in these 2 cases. In 7 cases, the Trachlight was used. In the remaining 10 cases, fiber-optic intubation was used. Limited mouth opening in patients with MMTAH did not improve with muscular relaxation. “Square mandible” has been reported to be one of the clinical features in this disease; however, half of these 24 patients lacked this characteristic, which might affect a definitive diagnosis of this disease for anesthesiologists. An airway problem in patients with MMTAH should not be underestimated, which means that other intubation methods rather than direct laryngoscopy had better be considered.
Local anesthetics have an impressive history of efficacy and safety in medical and dental practice. Their use is so routine, and adverse effects are so infrequent, that providers may understandably overlook many of their pharmacotherapeutic principles. The purpose of this continuing education article is to provide a review and update of essential pharmacology for the various local anesthetic formulations in current use. Technical considerations will be addressed in a subsequent article.
Please see the pdf version for the Continuing Education Program Answer Sheet.