The effect of an anterior biteplate on dental and skeletal Class II correction using headgears: a cephalometric study.

OBJECTIVE: To test the hypothesis that there are significant differences in skeletal and/or dental changes between Class II subjects treated with headgear (HG) compared with those treated with HG plus maxillary acrylic biteplate (BP) discluding teeth. SETTING AND SAMPLE POPULATION: Secondary analysis performed in Department of Orthodontics at the University of Washington. Fifty pre-adolescent Class II subjects were treated with HG as part of a randomized clinical trial (RCT) at the University of North Carolina/Chapel Hill, and 81 similar subjects were treated with HG plus a flatplane maxillary anterior BP for occlusal separation and anterior labial bow at the University of Florida as part of a separate RCT. MATERIAL AND METHODS: This retrospective cohort study examined anteroposterior (AP) and vertical cephalometric changes in two cohorts of Class II subjects. Pre- and post-treatment cephalometric radiographs for each group were obtained from the two centers and measured for dental and skeletal changes. These data were adjusted for differences in magnification and compared using ancova, controlling for important cohort and protocol differences between the two centers. RESULTS: Overbite and maxillary incisor inclinations were reduced significantly more in the HG/BP group. All other vertical and AP changes were not statistically significantly different between the groups. CONCLUSION: The maxillary anterior BP with labial bow is an effective appliance for reducing overbite and retracting incisors but provides no additional AP dental or skeletal benefit over HG treatment.

A longitudinal evaluation of pulpal pain during orthodontic tooth movement.

OBJECTIVES: To examine the longitudinal changes in pulpal sensitivity to electrical stimulation and the relationship to pulpal sensitivity as measured by electrical stimulation and subjective reports of tooth pain after archwire insertion. DESIGN: Non-randomized, prospective trial, with matched controls. SETTING AND SAMPLE POPULATION: Regional Clinical Dental Research Center at the University of Washington School of Dentistry. Eighteen adult subjects of age 13-37 years. Nine experimental subjects planned for orthodontic treatment. Nine control subjects matched for gender and age who did not have orthodontic treatment. EXPERIMENTAL VARIABLE: Fixed orthodontic appliances and initial archwire placement in experimental subjects compared with 'no treatment' control subjects. OUTCOME MEASURE: Subjective assessments of orthodontic tooth pain were made using visual analogue scales. Electrically evoked detection and pain thresholds were determined using a computer-controlled tooth stimulator. Data were gathered at five time points: after bracket placement (baseline), 1 h after placement of initial archwires, 1 day after archwire placement, 1 week after archwire placement, and 1 month after archwire placement. Comparable time intervals were used for the 'no treatment' control subjects. RESULTS: Subjective ratings of treatment-evoked tooth pain in the experimental group were the greatest at the post-archwire day 1 observation and progressively decreased for the remaining observations. Control subjects reported little pain at any of these observation times. The detection and pain threshold changes from baseline showed no statistical differences over time or between groups. While not statistically significant, a trend was noted where reports of greater orthodontic tooth pain were associated with increased sensitivity to electrical stimulation (i.e. lower detection and pain thresholds). CONCLUSION: Orthodontic patients experience significant pain and discomfort 1 day after initial archwire placement (i.e. activation). Future research should investigate whether self-reports of treatment-evoked tooth pain intensity are associated with pulpal sensitivity.

Recruiting phobic research subjects: effectiveness and cost.

Efficiently enrolling subjects is one of the most important and difficult aspects of a clinical trial. This prospective study evaluated strategies used in the recruitment of 144 dental injection phobics for a clinical trial evaluating the effectiveness of combining alprazolam with exposure therapy. Three types of recruitment strategies were evaluated: paid advertising, free publicity, and professional referral. Sixty-three percent of subjects were enrolled using paid advertising (the majority of them from bus advertisements [27.0%], posters on the University of Washington campus [20.1%], and newspaper advertisements [13.2%]). Free publicity (eg, television coverage, word of mouth) yielded 18.8% of enrolled subjects and professionaL referrals 14.6% of subjects. The average cost (1996 dollars) of enrolling 1 subject was $79. Bus and poster advertising attracted more initial contacts and yielded the greatest enrollment.

Reliability of individual differences in initial sensitivity and acute tolerance to nitrous oxide hypothermia.

On average, the hypothermia exhibited by rats receiving 60% nitrous oxide (N2O) eventually abates despite the continued inhalation of the drug (i.e., acute tolerance develops). However, large individual differences occur in both the magnitude of hypothermia achieved and the degree of acute tolerance that develops. To determine whether the degree of temperature loss and subsequent recovery during N2O administration are reliable characteristics of an individual, we measured intraperitoneal temperature via telemetry in 77 Long-Evans rats that each received 60% N2O for 5 h during two sessions separated by 14 days. Good intersession reliability (Pearson's r) was observed for simple change and adjusted change scores for both initial N2O temperature sensitivity (.61 < or = r < or = .62), and acute tolerance development (.46 < or = r < or = .52). In a separate experiment, three groups of rats were selected based on their individual body temperature patterns during an initial N2O administration: (1) insensitive to N2O hypothermia (n = 8); (2) marked hypothermia followed by acute tolerance development (n = 6); and (3) marked hypothermia followed by little acute tolerance development (n = 6). When retested 10 days later, each group exhibited a body temperature profile similar to that observed during the initial N2O exposure. Thus, the temperature profile observed during a rat's initial exposure to 60% N2O reflects a reproducible response for that animal.

Human gingival and pulpal blood flow during healing after Le Fort I osteotomy.

PURPOSE: The occurrence of a hypervascular period during healing after orthognathic surgery has not been investigated rigorously in human pulpal and gingival tissues. This study used laser Doppler flowmetry to investigate the effects of Le Fort I osteotomy on maxillary pulpal and gingival blood flow between the first and third week after surgery. PATIENTS AND METHODS: Pulpal blood flow was recorded in maxillary incisors, and gingival blood flow was assessed from a site slightly apical to the interdental papilla of the maxillary central incisors in 10 patients who were undergoing a Le Fort I osteotomy, 10 patients who were undergoing a mandibular osteotomy, and 10 nonsurgical control subjects who were not undergoing orthodontic treatment. Blood flow measurements were made before surgery and at intervals between 7 and 10 days, 14 and 17 days, and 21 and 24 days after surgery. The nonsurgical control subjects were tested at similar intervals. RESULTS: Baseline gingival and pulpal blood flow values did not differ significantly for the 3 groups. In addition, gingival and pulpal blood flow did not change in the nonsurgical control group. Analysis of the postsurgical change from baseline blood flow values indicated a significant increase in pulpal blood flow in the maxillary surgery patients relative to the patients treated with mandibular surgery. However, no significant group difference was found for gingival blood flow. CONCLUSIONS: This study provides evidence that pulpal blood flow is increased between the first and third week after Le Fort I osteotomy, but it did not find a significant change in gingival blood flow.

Psychiatric diagnoses among self-referred dental injection phobics.

In order to determine the psychiatric characteristics of people with dental injection phobia. 118 dental injection phobics were systematically assessed using a structured clinical interview and a written questionnaire. Fifty-four percent of subjects had a current Axis I diagnosis other than dental injection phobia, mainly anxiety, mood or adjustment disorder, and 68.6% of subjects had an additional lifetime Axis I diagnosis. Subjects with additional current Axis I diagnoses reported higher dental anxiety, greater severity of injection fear cognitions, and poorer relationships with dental professionals, than did subjects without any or with past Axis I diagnoses. Further investigation is needed to explore the treatment possibilities for patients with and without additional current diagnoses.

Pavlovian influences over food and drug intake.

Consuming food and taking drugs share several important characteristics. In particular, each causes changes in important physiological parameters that are constantly being monitored and regulated by the brain. As examples, blood glucose increases after meals; and body temperature decreases after ethanol is taken. Such changes elicit neurally-mediated homeostatic responses that serve to reduce the magnitude and duration of the perturbation. It is argued that when an individual can accurately anticipate pending meals or drugs, it can make appropriate responses to minimize or totally neutralize the meal/drug-elicited perturbations. This phenomenon, which is the basis for meal and drug tolerance, relies upon Pavlovian conditioning. Literature is reviewed which documents the role of conditioning processes in the development of tolerance. The argument is made that conditioned responses enable individuals to derive necessary or desirable aspects of food and drugs while minimizing some of their negative effects. In a final section, drug tolerance is discussed as a natural consequence of evolution-derived, meal-related learning processes, with associated negative consequences.

Patient compliance with oral hygiene regimens: a behavioural self-regulation analysis with implications for technology.

Achieving optimal oral health through preventive efforts is a hallmark of the dental profession. A primary goal of a preventively-oriented dental practice is to encourage patients to practice appropriate oral self-care behaviours. When patients are asked to follow an oral self-care regimen, they are being given a target or goal (for example, brush twice a day) and their task is to control or regulate their behaviour to achieve that objective. Unfortunately, patients often fail to meet the expectations set forth by the clinical recommendation. This review examines the problem of poor patient compliance with oral hygiene regimens by applying the general principles that govern the self-regulation of behaviour. The component parts of a behavioural self-regulation model are reviewed in the context of oral self-care. Research in the area of toothbrushing behaviour is reviewed and methods for providing patients with feedback about their degree of compliance are discussed.

Effectiveness of local anesthesia in pediatric dental practice.

BACKGROUND: Pain control in dental treatment for children is very important. The purpose of this study is to describe the characteristics of local anesthetic use by pediatric dentists and to examine factors related to its effectiveness in children. METHODS: The authors observed 361 patients in 17 pediatric dental practices in Washington state while each child received restorative or surgical dental treatment. The authors recorded data concerning local anesthetic use and effectiveness. The children's mean age was 87 months, and 181 (50.1 percent) of the patients were girls. A pediatric dentist observer rated each child's anxiety before the initial injection of local anesthetic and the effectiveness of pain control during restorative treatment. The observing dentist asked the treating dentist about the effectiveness of pain control after completion of treatment. RESULTS: Forty-two of 361 children (11.6 percent) were observed to experience ineffective pain control. Fourteen of 17 dentists (82.4 percent) were observed to have at least one patient in whom pain control was ineffective. Lidocaine (2 percent with 1:100,000 epinephrine) was used by 15 of 17 dentists (88.2 percent) and in 312 of 361 cases (86.4 percent). The average amount of agent was one cartridge (36 milligrams of lidocaine). Children who were anxious, who had symptoms before treatment, and who underwent more invasive operative and endodontic procedures were more likely to experience ineffective pain control. CONCLUSIONS: The data suggest that painful treatment is relatively frequent even in specialized pediatric practice. Variability in general practice is likely to be greater. CLINICAL IMPLICATIONS: The incidence of ineffective pain control may be less if clinicians use methods to reduce anxiety and perioperative infection and symptoms.

Effect of maternal soothing on infant stress response.

The effect of maternal soothing to infant inoculation as well as everyday distress on infant cortisol and behavioral responses to stress was examined in two longitudinal samples of 55 and 74 infants, respectively, between 2 and 6 months of age. There was no evidence that maternal soothing was effective in reducing infants' cortisol or behavioral responses to stress. The absence of this relation occurred despite evidence for cross-time stability and cross-situation consistency in maternal soothing. That maternal soothing plays little role in lowering infant responses to stress leaves open the possibilities that other maternal behaviors may mediate children's distress or that infant temperament may be related to infant stress.

Craniofacial morphology and tooth wear: a longitudinal study of orthodontic patients.

Previous research has suggested that a relationship exists between craniofacial morphology and tooth wear. The primary objective of this study was to determine whether an individual's craniofacial morphology during childhood is related to the degree of tooth wear that occurs in that same individual's adult dentition. Pretreatment orthodontic records taken during the mixed dentition (T1) and follow-up records taken an average of 20 years later (T2) were available for 165 orthodontic patients. Incisal/occlusal tooth wear was measured on a tooth-by-tooth basis from T1 and T2 casts using a four-category scoring system. Measures of craniofacial morphology were made from the T1 lateral cephalometric radiograph. Multiple regression analysis indicated that adult wear was associated with the T1 cephalometric measures of ANB (p = 0.017) and the interaction between ramal height and sex (p = 0.039). These results suggest that the craniofacial morphology observed during childhood has a small but significant relationship to adult tooth wear.

Nitrous oxide-induced hypothermia in the rat: acute and chronic tolerance.

Although inhalation of nitrous oxide (N2O) causes hypothermia in rats, there is a paucity of information as to whether tolerance develops to this effect. The purpose of this study was to determine whether tolerance to N2O hypothermia develops within a single administration as well as over repeated administrations. Temperature was measured telemetrically by implanting intraperitoneal thermal sensors/transmitters in male Long-Evans rats. Experimental rats received an initial 2-h exposure to 60% N2O and became hypothermic relative to controls breathing placebo gas. Only a few rats demonstrated evidence of acute tolerance over the 120 min. Over the next 10 days, the experimental rats received five additional 30-min exposures to 60% N2O and five 30-min exposures to placebo while the control rats received only placebo gas exposures. Chronic tolerance developed to N2O hypothermia over these repeated administrations. A test for Pavlovian drug conditioning found no evidence that conditioned temperature effects contributed to chronic tolerance development. In a second experiment, naive rats were given a 380-min exposure to 60% N2O and a 380-min exposure to placebo gas in a counterbalanced order. Acute tolerance did develop to N2O hypothermia, with the recovery of temperature beginning after a mean of 141 min of gas administration. Hence, both acute and chronic tolerance develop to N2O's hypothermic effects in rats.

Dental fear among university employees: implications for dental education.

We surveyed 350 University of Washington permanent employees chosen randomly from among both faculty and staff. The aim was to determine the extent and nature of dental anxiety in the university population potentially available for teaching clinics. In addition, the relationship of fears to self-reported dental health, utilization of dental care, and other general and mental health issues was examined. Dental anxiety was prevalent in this population; 13 percent of subjects reported high dental fear. In contrast to respondents with lower dental fear, subjects with clinically significant fear reported poorer perceived dental health, a longer interval since their last dental appointment, a higher frequency of past fear behaviors, more physical symptoms during last dental injection, and higher percentage of symptoms of anxiety and depression. Dental anxiety was not associated with poorer perceived general health or a longer interval since the last dental injection. University employees are a rich source of potential teaching patients for achieving curricular requirements for managing anxious patients. Student clinicians need guidance to be able to recognize fearful patients; they also need instruction about psychiatric conditions like anxiety and depression in order to be able to better manage and prevent dropouts in their patient roster.

CARL: a LabVIEW 3 computer program for conducting exposure therapy for the treatment of dental injection fear.

This paper describes CARL (Computer Assisted Relaxation Learning), a computerized, exposure-based therapy program for the treatment of dental injection fear. The CARL program operates primarily in two different modes; in vitro, which presents a video-taped exposure hierarchy, and in vivo, which presents scripts for a dentist or hygienist to use while working with a subject. Two additional modes are used to train subjects to use the program and to administer behavioral assessment tests. The program contains five different modules, which function to register a subject, train subjects to use physical and cognitive relaxation techniques, deliver an exposure hierarchy, question subjects about the helpfulness of each of the therapy components, and test for memory effects of anxiolytic medication. Nine subjects have completed the CARL therapy program and 1-yr follow-up as participants in a placebo-controlled clinical trial examining the effects of alprazolam on exposure therapy for dental injection phobia. All nine subjects were able to receive two dental injections, and all reduced their general fear of dental injections. Initial results therefore indicate that the CARL program successfully reduces dental injection fear.

Inhalation of 30% nitrous oxide impairs people's learning without impairing people's judgments of what will be remembered.

Many hypotheses have been proposed to account for the effects of nitrous oxide on memory, with one emerging possibility being that it has a global effect on memory-related functioning. This possibility was explored by examining the effects of nitrous oxide on memory performance and on the accuracy of people's judgments about their memory performance. Participants inhaled 30% nitrous oxide or a placebo gas while items were studied and while judgments were made about the likelihood of recall for each item. Next, all participants inhaled the placebo during paired-associate recall. Although administration of nitrous oxide during study impaired recall, it did not affect the predictive accuracy of the metacognitive judgments. These results provide pharmacological evidence for a distinction between memory and metamemory.

Acute tolerance and reversal of the motor control effects of midazolam.

The purpose of this study was to determine whether acute tolerance develops to the motor control effects of the short-acting benzodiazepine, midazolam. Using a bolus and constant infusion scheme, 40 healthy adults received a 70-min intravenous infusion of either saline (n = 20) or 6.1 (SE = 0.2) mg midazolam (n = 20). Following the 70-min infusion period, half of the subjects in each group (n = 10) received a 25-min intravenous infusion of flumazenil (benzodiazepine antagonist); the remainder of the subjects (n = 10/group) received a 25-min infusion of saline. Drug administration during both infusion periods was double blind. Prior to the infusions, subjects were trained in a motor control assessment battery. Throughout both infusions, repeated motor control testing and blood sampling were performed. The initial (10 min) midazolam plasma concentration was 52.0 (SE = 2.2) ng/ml. Plasma midazolam concentration rose gradually to 60.7 (SE = 2.1) ng/ml at the end of the infusion (70 min). Midazolam initially impaired performance on the motor control tasks. However, performance improved in subjects receiving midazolam despite the gradual increase in midazolam concentrations. This suggests that the recovery of motor task performance may be attributable to the development of acute tolerance rather than to waning drug concentrations. Flumazenil immediately reversed midazolam's effects on the visual tracking task. However, there was little evidence for precipitation of muscle force rebound, which has been hypothesized to result from the same underlying mechanism that is responsible for acute tolerance development.

Dental fear among university students: implications for pharmacological research.

University students are often subjects in randomized clinical trials involving anxiolytic and analgesic medications used during clinical dental and medical procedures. The purpose of this study was to describe a typical university student population available for research by using data from a mail survey. Subjects were 350 students chosen randomly from all enrolled, full-time, traditional students on the main campus at the University of Washington in Seattle, WA. The aim was to determine the extent and nature of dental anxiety in this population. In addition, the relationships between subject willingness to receive dental injections and general and mental health and medical avoidance and medical fears were examined. The Dental Anxiety Scale (DAS) was used to measure dental anxiety. Dental anxiety was prevalent in this population; 19% of students reported high rates of dental fear. Thirteen percent of students had never had a dental injection. Students with no experience with dental injections were more reluctant than those with experience to receive an injection if one were needed. DAS scores were correlated with injection reluctance. Students who were reluctant to go ahead with a dental injection also reported poorer general and mental health than those who were less reluctant. These students also reported higher medical avoidance and medical anxiety scores. University students provide a rich source of potential subjects for clinical research. The student population, like the community at large, contains people with high levels of dental and medical fear.

Amnestic and anxiolytic effects of alprazolam in oral surgery patients.

PURPOSE: This study was designed to identify a dose of alprazolam that would reduce anxiety associated with oral surgery without causing accompanying memory impairment. PATIENTS AND METHODS: Thirty-six subjects in experiment 1 and 48 subjects in experiment 2 were pretested on a computerized memory battery to establish baseline performance. Subjects were then randomly assigned to receive placebo, 0.25 mg, or 0.75 mg oral alprazolam (experiment 1) or placebo, 0.25 mg, 0.50 mg, or 0.75 mg oral alprazolam (experiment 2). Forty-five minutes after the double-blind administration of alprazolam, subjects were given a second memory battery. The memory batteries tested story recall and recognition and word recall and recognition. Subjects in experiment 2 subsequently underwent oral surgery for the removal of one to four molars. The subjects completed anxiety questionnaires both before and after surgery. RESULTS: The 0.75-mg and 0.50-mg doses, but not the 0.25-mg dose, impaired word recall. The 0.75-mg dose also impaired story recall and recognition. The proportion of subjects reporting moderate to high anxiety during oral surgery decreased with increasing doses of alprazolam. Multiple regression indicated that the 0.75-mg alprazolam dose significantly decreased anxiety during oral surgery. The 0.25-mg and 0.50-mg doses also tended to reduce anxiety, but beta values for these doses did not reach significance. CONCLUSIONS: These findings indicate that alprazolam produces memory impairment at the dosages necessary to produce clinically significant anxiolysis during oral surgery.

A longitudinal study of tooth wear in orthodontically treated patients.

The primary objective of this study was to determine whether there is a relationship between incisal/occlusal tooth wear during the mixed dentition and subsequent wear of the adult dentition. Pretreatment orthodontic records taken during the mixed dentition (T1), as well as follow-up records taken an average of 20 years later (T2), were available for 223 orthodontically treated patients. Incisal/occlusal tooth wear was measured on a tooth-by-tooth basis from T1 and T2 stone casts with a four-category scoring system. Multiple regression analysis (R2 = 0.33) indicated that wear could be predicted at a given age during adulthood from wear observed on the deciduous mandibular canines and molars at T1 (p < 0.0001). This predictive relationship was modified by the age at which the T1 wear was observed (p = 0.029) and possibly by the sex of the patient (p = 0.10). These results indicate that adult tooth wear is not independent of the tooth wear that occurred as a child. Bruxism is suggested as a possible common etiologic mechanism that may account for the relationship between childhood and adult tooth wear.