Daniel A Haas’s research while affiliated with University of Toronto and other places

Concerns about the safety of pediatric oral sedation and the incremental use of triazolam in adults prompted a workshop cosponsored by several professional organizations. There is a strong need and demand for adult and pediatric sedation services. Using oral medication to achieve anxiolysis in adults appears to have a wide margin of safety. Mortality and serious morbidity, however, have been reported with oral conscious sedation, especially in young children. Most serious adverse events are related to potentially avoidable respiratory complications. Clinical trials are needed to evaluate oral sedative drugs and combinations, as well as to develop discharge criteria with objective quantifiable measures of home readiness. Courses devoted to airway management should be developed for dentists who provide conscious sedation services. State regulation of enteral administration of sedatives to achieve conscious sedation is needed to ensure safety. Safety in outpatient sedation is of paramount concern, with enteral administration of benzodiazepines appearing safe but poorly documented in the office setting. Conscious sedation by the enteral route, including incremental triazolam, necessitates careful patient evaluation, monitoring, documentation, facilities, equipment and personnel as described in American Dental Association and American Academy of Pediatric Dentistry guidelines.

The aim of this study was to compare recovery for oral surgery patients given a deep sedation regimen of midazolam, propofol, and remifentanil with a standard control of fentanyl in place of remifentanil. This investigation was designed as a randomized, prospective, single-blinded controlled study. Group 1, the control, received midazolam 0.03 mg/kg, fentanyl 1 microg/kg, and propofol initially at 140 microg/kg/min. Group 2 received midazolam 0.03 mg/kg, remifentanil: propofol (1:500) given at an initial propofol infusion rate of 40 microg/kg/min. Outcome measures included time to response to verbal command, Aldrete score = 9, Postanesthesia Discharge Scoring System = 7, and assessment by the Digit Symbol Substitution Test. Forty-seven subjects were entered in the study. Baseline findings were homogenous between the 2 groups. Subjects in group 2 recovered earlier (P < .005) and required less propofol for both the induction (0.8 +/- 0.4 versus 1.2 +/- 0.6 mg/kg; mean +/- SD, P < .01) and maintenance of deep sedation (46 +/- 9 versus 131 +/- 17 microg/kg/min; P < .005). There were minor differences in vital signs. This study demonstrated that this remifentanil regimen provided significantly more rapid recovery and used significantly less propofol compared with the fentanyl regimen.

Permanent paresthesia following a local anesthetic injection is a possible adverse event. Epidemiological studies have suggested that the 4% solutions used in dentistry, namely prilocaine and articaine, are more highly associated with this occurrence. This article reviews the epidemiological evidence regarding articaine and paresthesia.

The aim of this study was to assess the need and demand for sedation or general anesthesia (GA) for dentistry in the Canadian adult population. A national telephone survey of 1101 Canadians found that 9.8% were somewhat afraid of dental treatment, with another 5.5% having a high level of fear. Fear or anxiety was the reason why 7.6% had ever missed, cancelled, or avoided a dental appointment. Of those with high fear, 49.2% had avoided a dental appointment at some point because of fear or anxiety as opposed to only 5.2% from the no or low fear group. Regarding demand, 12.4% were definitely interested in sedation or GA for their dentistry and 42.3% were interested depending on cost. Of those with high fear, 31.1% were definitely interested, with 54.1% interested depending on cost. In a hypothetical situation where endodontics was required because of a severe toothache, 12.7% reported high fear. This decreased to 5.4% if sedation or GA were available. For this procedure, 20.4% were definitely interested in sedation or GA, and another 46.1% were interested depending on cost. The prevalence of, and preference for, sedation or GA was assessed for specific dental procedures. The proportion of the population with a preference for sedation or GA was 7.2% for cleaning, 18% for fillings or crowns, 54.7% for endodontics, 68.2% for periodontal surgery, and 46.5% for extraction. For each procedure, the proportion expressing a preference for sedation or GA was significantly greater than the proportion having received treatment with sedation or GA (P < 0.001). In conclusion, this study demonstrates that there is significant need and demand for sedation and GA in the Canadian adult population.

The purpose of this study was to evaluate the effect of local anesthetic blockade of afferent innervation on the development of capsaicin-induced edema in the rat temporomandibular joint (TMJ) region and on reflex jaw muscle activity. Under halothane anesthesia, 64 male Sprague-Dawley rats were prepared for monitoring of edema development by lateral movement of a needle overlying the left TMJ region and for acute recording of electromyographic activity in ipsilateral digastric and masseter muscles. A double-barrel catheter was inserted into the TMJ region for delivery of saline or 0.5% bupivacaine from 1 needle, followed with the injection of 1% capsaicin, 0.1% capsaicin, or vehicle control from the other needle 5 minutes later. Application of capsaicin into the saline pretreated TMJ region led to dose-dependent edema development and reflex jaw muscle activity; however, only 1% capsaicin solution resulted in significant tissue expansion and muscle activity when compared with the vehicle control. Pretreatment of the rat TMJ region with bupivacaine failed to inhibit capsaicin-induced edema development, although successful blockade of nerve conduction was confirmed with the absence of reflex jaw muscle activity. Capsaicin-induced edema of the rat TMJ region developed independent of axonal conduction, suggesting neurogenic inflammation may arise regardless of functional nerve conduction.

The authors conducted this study to compare the pain on injection of the three mandibular block techniques and to determine the effect that the delivery of nitrous oxide:oxygen, or N2O:O2, had on this pain. Based on sample size calculation, the authors randomly assigned 60 subjects to receive either local anesthetic alone or local anesthetic with N2O:O2 titrated to effect. Each subject received two mandibular block injections bilaterally from three possible pairings: Gow-Gates/standard block, standard block/Vazirani-Akinosi or Gow-Gates/ Vazirani-Akinosi. Subjects scored their pain using a 100-millimeter visual analog scale immediately after each injection. The authors analyzed data using analysis of variance, Student t tests and multiple regression analyses. There were no significant differences in pain on injection among the three injection techniques. The subjects in the group that received N2O:O2 and the local anesthetic demonstrated a statistically significant reduction in pain on injection compared with subjects in the group that received the local anesthetic only (P < .05). When N2O:O2 was used, there was a statistically significant decrease in pain with the first injection (P < .0005), an effect not seen with the second injection. There was no significant difference in pain among the three mandibular block techniques. N2O:O2 can reduce pain on the first injection given, but this effect is not seen subsequently. The decision to select one of the three mandibular block techniques should be based on factors other than pain on injection. N2O:O2 reduces pain on the first injection only.

To assess the validity of recommendations to avoid using cartridges for dental local anesthetic in patients with latex allergies. A MEDLINE search was conducted for the period 1966 to 2001, and relevant publications were reviewed for evidence of allergic reactions precipitated by latex in medication vials or cartridges for dental local anesthetic. Twelve publications met the selection criteria and are summarized here: 4 case reports, 5 experimental studies, 1 clinical update and 2 letters to the editor. The medical literature provides some evidence that latex allergen can be released into pharmaceutical solutions contained within vials, by either penetration through or direct contact with natural latex stoppers. However, there are no reports of studies or cases in which a documented allergy was due to the latex component of cartridges for dental local anesthetic.

Local anesthetics are the most commonly used drugs in dentistry. This article provides a brief update on the pharmacology, adverse effects and clinical applications of these drugs, as well as the role of vasoconstrictors.