A test of pre-exposure spacing and multiple context pre-exposure on the mechanisms of latent inhibition of dental fear: A study protocol.

BACKGROUND: Latent inhibition occurs when exposure to a stimulus prior its direct associative conditioning impairs learning. Results from naturalistic studies suggest that latent inhibition disrupts the learning of dental fear from aversive associative conditioning and thereby reduces the development of dental phobia. Although theory suggests latent inhibition occurs because pre-exposure changes the expected relevance and attention directed to the pre-exposed stimulus, evidence supporting these mechanisms in humans is limited. The aim of this study is to determine if two variables, pre-exposure session spacing and multiple context pre-exposure, potentiate the hypothesized mechanisms of expected relevance and attention and, in turn, increase latent inhibition of dental fear. METHODS: In a virtual reality simulation, child and adult community members (ages 6 to 35) will take part in pre-exposure and conditioning trials, followed by short- and long-term tests of learning. A 100ms puff of 60 psi air to a maxillary anterior tooth will serve as the unconditioned stimulus. Pre-exposure session spacing (no spacing vs. sessions spaced) and multiple context pre-exposure (single context vs. multiple contexts) will be between-subject factors. Stimulus type (pre-exposed to-be conditioned stimulus, a non-pre-exposed conditioned stimulus, and an unpaired control stimulus) and trial will serve as within-subject factors. Baseline pain sensitivity will also be measured as a potential moderator. DISCUSSION: It is hypothesized that spaced pre-exposure and pre-exposure in multiple contexts will increase the engagement of the mechanisms of expected relevance and attention and increase the latent inhibition of dental fear. It is expected that the findings will add to theory on fear learning and provide information to aid the design of future interventions that leverage latent inhibition to reduce dental phobia.

A study protocol testing pre-exposure dose and compound pre-exposure on the mechanisms of latent inhibition of dental fear.

BACKGROUND: Dental stimuli can evoke fear after being paired - or conditioned - with aversive outcomes (e.g., pain). Pre-exposing the stimuli before conditioning can impair dental fear learning via a phenomenon known as latent inhibition. Theory suggests changes in expected relevance and attention are two mechanisms responsible for latent inhibition. In the proposed research, we test whether pre-exposure dose and degree of pre-exposure novelty potentiate changes in expected relevance and attention to a pre-exposed stimulus. We also assess if the manipulations alter latent inhibition and explore the possible moderating role of individual differences in pain sensitivity. METHODS: Participants will be healthy individuals across a wide range of ages (6 to 35 years), from two study sites. Participants will undergo pre-exposure and conditioning followed by both a short-term and long-term test of learning, all in a novel virtual reality environment. The unconditioned stimulus will be a brief pressurized puff of air to a maxillary anterior tooth. Pre-exposure dose (low vs. high) and pre-exposure novelty (element stimulus vs. compound stimuli) will be between-subject factors, with stimulus type (pre-exposed to-be conditioned stimulus, a non-pre-exposed conditioned stimulus, and an unpaired control stimulus) and trial as within-subject factors. Pain sensitivity will be measured through self-report and a cold pressor test. It is hypothesized that a larger dose of pre-exposure and compound pre-exposure will potentiate the engagement of the target mechanisms and thereby result in greater latent inhibition in the form of reduced fear learning. Further, it is hypothesized that larger effects will be observed in participants with greater baseline pain sensitivity. DISCUSSION: The proposed study will test whether pre-exposure dose and compound stimulus presentation change expected relevance and attention to the pre-exposed stimulus, and thereby enhance latent inhibition of dental fear. If found, the results will add to our theoretical understanding of the latent inhibition of dental fear and inform future interventions for dental phobia prevention.

Study protocol of an investigation of attention and prediction error as mechanisms of action for latent inhibition of dental fear in humans.

BACKGROUND: Evidence suggests that dental anxiety and phobia are frequently the result of direct associative fear conditioning but that pre-exposure to dental stimuli prior to conditioning results in latent inhibition of fear learning. The mechanisms underlying the pre-exposure effect in humans, however, are poorly understood. Moreover, pain sensitivity has been linked to dental fear conditioning in correlational investigations and theory suggests it may moderate the latent inhibition effect, but this hypothesis has not been directly tested. These gaps in our understanding are a barrier to the development of evidence-based dental phobia prevention efforts. METHODS: Healthy volunteers between the ages of 6 and 35 years will be enrolled across two sites. Participants will complete a conditioning task in a novel virtual reality environment, allowing for control over pre-exposure and the examination of behaviour. A dental startle (a brief, pressurized puff of air to a tooth) will serve as the unconditioned stimulus. Using a within-subjects experimental design, participants will experience a pre-exposed to-be conditioned stimulus, a non-pre-exposed to-be conditioned stimulus, and a neutral control stimulus. Two hypothesized mechanisms, changes in prediction errors and attention, are expected to mediate the association between stimulus condition and fear acquisition, recall, and retention. To ascertain the involvement of pain sensitivity, this construct will be measured through self-report and the cold pressor task. DISCUSSION: Dental phobia negatively affects the dental health and overall health of individuals. This study aims to determine the mechanisms through which pre-exposure retards conditioned dental fear acquisition, recall, and retention. A randomized control trial will be used to identify these mechanisms so that they can be precisely targeted and maximally engaged in preventative efforts.

Pilot Study Comparing Nasal vs Oral Intubation for Dental Surgery by Physicians, Nurse Anesthetists, and Trainees.

The purpose of this article was to determine if pediatric dental treatment under general anesthesia utilizing orotracheal intubation takes longer than using nasotracheal intubation techniques. Twenty-six American Society of Anesthesiologists Physical Status Classification I and II pediatric dental patients, ages 2-8 years treated under general anesthesia, were assigned to 1 of 2 groups: (a) nasotracheal intubation (control, n = 13), (b) orotracheal intubation (experimental, n = 13). Times for intubation, radiographic imaging, and dental procedures, as well as total case time were quantified. Data were collected on airway difficulty, numbers of providers needed for intubation, intubation attempts, and intubation trauma. There was a significant difference in mean intubation time (oral = 2.1 minutes versus nasal = 6.3 minutes; p < .01). There was no difference in mean radiograph time (oral = 4.2 minutes versus nasal = 3.4 minutes; p = .144), and overall radiograph image quality was not affected. There was no difference in dental procedure time ( p = .603) or total case time ( p = .695). Additional providers were needed for intubation and more attempts were required for nasotracheal intubation versus orotracheal intubation (6 additional providers/22 attempts vs 0 additional providers/15 attempts, p < .01 and p < .05, respectively). Nine of 13 nasotracheal intubations were rated as traumatic (69%) versus 0 of 13 for orotracheal intubations (0%) ( p < .01). In 7/9 orotracheal intubation cases (78%), the tube was not moved during treatment ( p < .01). Orotracheal intubation does not increase case time, does not interfere with radiographic imaging, and is less traumatic for the patient when performed by physician anesthesiologists, emergency and pediatric medicine physician residents, certified registered nurse anesthetists, and student nurse anesthetists, all with variable nasotracheal intubation experience.

Masking the bitter taste of injectable lidocaine HCl formulation for dental procedures.

Several attempts have been made to mask the bitter taste of oral formulations, but none have been made for injectable formulations. This study aims to mask the bitter taste of dental lidocaine HCl (LID) injection using hydroxypropyl-ß-cyclodextrin (HP-ß-CD) and sodium saccharin. Inclusion complexes of LID and HP-ß-CD were prepared by the solution method in 1:1 and 1:2 M ratios. Inclusion complexes in solution were studied using phase solubility in phosphate buffer solutions (pH 8, 9, and 10). Freeze-dried inclusion complexes were characterized using differential scanning calorimetry (DSC), X-ray, Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and in vitro release. Injectable formulations were prepared using inclusion complexes and characterized for stability and for taste using an Alpha MOS ASTREE electronic tongue (ETongue). The association constants of HP-ß-CD with lidocaine-free base and its ionized form were found to be 26.23 ± 0.00025 and 0.8694 ± 0.00045 M(-1), respectively. Characterization studies confirmed the formation of stable inclusion complexes of LID and HP-ß-CD. Injectable formulations were found to be stable for up to 6 months at 4°C, 25°C, and 40°C. The taste evaluation study indicated that HP-ß-CD (1:1 and 1:2 M ratios) significantly improved the bitter taste of LID injectable formulation. In conclusion, inclusion complex in the 1:1 M ratio with 0.09% sodium saccharin was considered to be optimum in masking the bitter taste of LID.

The pulpectomy in primary teeth.

BACKGROUND: The pulpectomy is an underutilized treatment modality for severely infected primary teeth. CASE DESCRIPTION: The author presents two pulpectomy cases that were filled with Vitapex. CLINICAL IMPLICATIONS: Vitapex is an excellent filling material for primary tooth pulpectomies. Its clinical characteristics and ease of use may make the pulpectomy procedure a more-attractive alternative to extraction.