Assessment of a dental anxiety scale

A number of different sets of data concerning the Corah Dental Anxiety Scale were evaluated. The data indicate that the scale is a reliable, valid, and useful measure of dental anxiety. It can be successfully used in the dental office or in research projects.

Vitamin A-deficient quail embryos have half a hindbrain and other neural defects

BACKGROUND

Retinoic acid (RA) is a morphogenetically active signalling molecule thought to be involved in the development of severely embryonic systems (based on its effect when applied in excess and the fact that it can be detected endogenously in embryos). Here, we adopt a novel approach and use the vitamin A-deficient (A-) quail embryo to ask what defects these embryos show when they develop in the absence of RA, with particular reference to the nervous system.

RESULTS

We have examined the anatomy, the expression domains of a variety of genes and the immunoreactivity to several antibodies in these A- embryos. In addition to the previously documented cardiovascular abnormalities, we find that the somites are smaller in A- embryos, otic vesicle development is abnormal and the somites continue up to and underneath the otic vesicle. In the central nervous system, we find that neural crest cells need RA for normal development and survival, and the neural tube fails to extend any neurites into the periphery. Using general hindbrain morphology and the expression patterns of Hoxa-2, Hoxb-1, Hoxb-4, Krox-20 and FGF-3 as markers, we conclude that segmentation in the myelencephalon (rhombomeres 4-8) is disrupted. In contrast, the dorsoventral axis of the neural tube using Shh, islet-1 and Pax-3 as markers is normal.

CONCLUSIONS

These results demonstrate at least three roles for RA in central nervous system development: neural crest survival, neurite outgrowth and hindbrain patterning.

The distribution of endogenous retinoic acid in the chick embryo: implications for developmental mechanisms

The aim of these experiments was to determine the endogenous distribution of retinoic acid (RA) across a wide range of embryonic stages in the chick embryo. By high pressure liquid chromatography, it was revealed that didehydroRA is the most prevalent retinoic acid in the chick embryo and that the tissues of the stage 24 embryo differed widely in their total RA content (didehydroRA + all-trans-RA). Some tissues such as the heart had very little RA and some such as the neural tube had very high levels, the total variation between these two being 29-fold. We showed that these tissues also synthesised RA and released it into the medium, thus validating the use of the F9 reporter cell system for further analyses of younger staged embryos. With these F9 cells, we showed that, at stage 4, the posterior end of the embryo had barely detectably higher levels of RA than the anterior end, but that a significant level of RA generation was detected as soon as somitogenesis began. Then a sharp on/off boundary of RA was present at the level of the first somite. We could find no evidence for a posterior-to-anterior gradient of RA. Throughout further development, various consistent observations were made: the developing brain did not generate RA, but the spinal part of the neural tube generated it at very high levels so there must be a sharp on/off boundary in the region of the hindbrain/spinal cord junction; the mesenchyme surrounding the hindbrain generated RA whereas the hindbrain itself did not; there was a variation in RA levels from the midline outwards with the highest levels of RA in the spinal neural tube followed by lower levels in the somites followed by lower levels in the lateral plate; the posterior half of the limb bud generated higher levels than the anterior half. With these observations, we were able to draw maps of endogenous RA throughout these early stages of chick embryogenesis and the developmental implications of these results are discussed.

Fears of the dental situation

Ratings of fear in the dental situation indicate that high fear and low fear patients rank the fears associated with the dental situation in about the same way (p = 0.98). Also, the attitude of the dentist is important to the patient, and may, partially, determine his attitude toward dentistry.

The role of vitamin A in the development of the central nervous system

We describe here the defects that arise in the central nervous system (CNS) of quail embryos when they develop in the absence of vitamin A. It has been assumed that because of the effects of excess vitamin A and its metabolites, particularly retinoic acid (RA), on the CNS they are involved in various aspects of CNS development. We show that this is indeed the case, because these deficient quail embryos have three defects in their CNS. First, the posterior hindbrain fails to develop because the cells fated to form this part of the CNS in the very early embryo die by apoptosis. Second, the neural tube fails to extend neurites into the periphery both in vivo and in vitro. Third, the neural crest cells throughout the embryo die by apoptosis. These results demonstrate a crucial requirement for vitamin A in CNS development.

A prevalence study of the clinical signs associated with mandibular dysfunction

A prevalence study was made of the most common clinical signs of mandibular dysfunction in a sample population of 1,000 patients in a general dental practice. Palpable joint irregularities (joint sounds) were found in about a third of the sample. All other frequencies were relatively low. Females had consistently higher frequencies than males, although the differences were generally not significant. A methodology that was quantified for the first time in relation to muscle palpation was used. Results of this study would indicate that the prevalence of the major clinical signs of mandibular dysfunction in the population expected to be seen in a general dental practice is not high and, furthermore, that their occurrence in the absence of pain does not necessarily indicate a need for treatment.

A comparison of different treatments for nocturnal bruxism

One hundred bruxers were evaluated for bruxing activity before, during, and after treatment with a portable electromyograph (EMG). A six-month post-treatment follow-up of bruxing activity was obtained. Experimental treatment groups consisted of diurnal biofeedback, nocturnal biofeedback, massed negative practice, and splint therapy. A no-treatment control group was included. The comparative efficacy of treatments was determined by analyses of variance. Both EMG-measured frequency of bruxing episodes and duration of bruxing activity decreased significantly for nocturnal biofeedback and splint therapy treatments but not for massed negative practice, diurnal biofeedback (relaxation), or the no-treatment control group. The two-week treatment effects were transient, and bruxing activity generally returned to baseline levels when treatment was withdrawn. These findings are consistent with the findings of previous researchers with regard to nocturnal biofeedback and splint therapy but differ from previous findings for massed negative practice therapy.

Hindbrain respecification in the retinoid-deficient quail

We report here the development and rescue of the truncated hindbrain of retinoid-deprived quail embryos. The embryo is completely rescued by an injection of retinol into the egg; this confirms retinol, or a related retinoid, as a required molecule in hindbrain development. Staging the retinoid replacement enabled us to determine that the 3-4 somite stage is the period when retinoids are required for normal development. Analysis of the development of the retinoid-deprived hindbrain phenotype through somitogenesis has revealed a pathway of retinoid action in early hindbrain regionalization. The hindbrain of the retinoid-deprived embryo is normal in size, during early somitogenesis, but has a respecified pattern of Krox-20 expression. From the earliest expression of Krox-20, at the 5 somite stage, the rhombomere 3 stripe fills the caudal third of the developing hindbrain to the level of the first somite. Morphologically only 2, instead of the normal 5, rhombomere bulges form. These 2 bulges express genes and, later, develop morphology characteristic of rhombomeres 1 and 2 and rhombomere 3. Posterior hindbrain specific genes, Hoxb-1, Fgf3, MafB, and the rhombomere 5 stripe of Krox-20 are never expressed in the head neuroepithelium of these embryos. From the initial formation of the neural plate, there is no evidence of rhombomere 4-7 specific characteristics. These results indicate the specification of the posterior hindbrain is lost and its cells participate in the formation of an enlarged anterior hindbrain. In our previous study, we reported the absence of the posterior hindbrain in retinoid-deprived quails (Maden, M., Gale, E., Kostetskii, I., Zile, M., 1996. Vitamin A-deficient quail embryos have half a hindbrain and other neural defects. Curr. Biol. 6, 417-426). Here, we show this phenotype to be the result of respecification of the hindbrain cells. This provides evidence for a region specific response to a single stimulus, retinol, which suggests a pre-rhombomeric regionalization of the hindbrain.

Psychological stress reduction during dental procedures

Behavioral methods of patient stress reduction during amalgam restorations were evaluated. Eighty adult patients were randomly assigned to one of four groups of 20 each: a control group, a relaxation group, a perceived control group, and an active distraction group. Both relaxation and distraction were found to be effective in reducing patient discomfort.

Late effects of retinoic acid on neural crest and aspects of rhombomere

We exposed st.10 chicks to retinoic acid (RA), both globally, and locally to individual rhombomeres, to look at its role in specification of various aspects of hindbrain derived morphology. Previous studies have looked at RA exposure at earlier stages, during axial specification. Stage 10 is the time of morphological segmentation of the hindbrain and is just prior to neural crest migration. Rhombomere 4 localised RA injections result in specific alterations of pathways some crest cells that normally migrate to sites of differentiation of neurogenic derivatives. The r4 crest cells that give rise to mesenchymal derivatives are unaffected. In addition, r4 gene expression is also partially altered by RA; within 6 hours of r4 exposure to RA, ectopic expression of Krox-20 is seen in r4 and Hoxb-1 expression is lost while Hoxa-2 expression continues normally. When we examined these RA-treated animals later in development, they showed an anterior displacement of the facial ganglion in addition to a mis-direction of the extensions of its distal axons and a dramatic decrease in the number of contralateral vestibuloacoustic neurons normally seen in r4. Only this r4-specific neuronal type is affected in r4; the motor neuron projections seem normal in experimental animals. The specificity of this result, combined with the loss of Hoxb-1 expression in r4 and the work by Krumlauf and co-workers showing gain of contralateral neurons co-localised with ectopic Hoxb-1 expression, indicates a role for Hoxb-1 and RA in the specification of this cell type in normal development. These results suggest that RA, at st.10, is able to affect some aspects of segment identity while leaving others unchanged.

Clinical performance and physical properties of twelve amalgam alloys

An assessment of the marginal failure rate of 1,041 restorations of twelve alloys was made at one year. In addition, physical property tests were conducted. A correlation was found between the clinical performance and creep (.79), flow (.62) and 24-hour compressive strength (.60).

Positional apoptosis during vertebrate CNS development in the absence of endogenous retinoids

We have previously shown that quail embryos that develop in the absence of vitamin A have severe defects in their central nervous system. One defect is a completely missing posterior hindbrain. Here we have studied how this comes about by examining cell death using a wholemount technique. In these A- embryos we observe two narrow bands of ectopic apoptosis. One is in the mesenchyme in the region of the first somite and occurs at the 4–6 somite stage, before neural tube closure. The second band follows immediately afterwards and occurs in the neuroepithelium of the presumptive posterior hindbrain at the 6–8 somite stage. Electron microscopy shows that the dying neuroepithelial cells exhibit the characteristics of apoptosis. Rescuing the embryos by injecting retinol before gastrulation completely prevents these apoptotic events. In an effort to identify some of the genes that may be involved in the apoptotic pathway we show that Msx-2 is upregulated in the apoptotic neuroepithelium and thus may be involved, whereas Bmp-4 is not altered and thus presumably not involved. Since these apoptotic event take place at the time of specification of axial identity and segmentation in the mesenchyme and neuroepithelium we conclude that these cells die because they are wrongly specified in terms of their rostrocaudal position, a novel phenomenon which we refer to as positional apoptosis.

Human masticatory muscle activity and jaw position under experimental stress

The purpose of the present study was to determine whether stress induced a consistent pattern of increased electromyographic (EMG) activity in different masticatory muscles, and whether stress produced changes in jaw position. Thirty-five dental students at Taipei Medical College volunteered for this study. Mental arithmetic was used to create a stress condition and relaxation instruction was used to help relax the subjects. Subjects were asked to evaluate the stress they felt under each experimental condition with a visual analogue scale (VAS). Surface electrodes were used to monitor the EMG activities of the right masseter, right posterior temporalis and suprahyoid muscles. A kinesiograph was used to observe the jaw position. Data collected before mental arithmetic or relaxation monitored the baseline level. The VAS means were significantly increased during the stress condition and significantly decreased following relaxation, compared with the baseline. There was also a significant increase in EMG activity of all three muscles during mental arithmetic compared with baseline; different patterns of increased EMG activity were noticed in the three muscles under a continuous stress condition. Under stress, the incidence of tooth contact at intercuspal position was also increased.

Patient self-monitoring of blood glucose and refinements of conventional insulin treatment

The compelling evidence that blood glucose control will slow or prevent microvascular complications has stimulated research to find better ways of managing insulin-dependent diabetes. The excellent results obtained with "open loop" insulin infusion systems suggest that the relative failure of conventional treatment is the result of (1) a lack of appropriate feedback to the patient and (2) the use of insulin regimens which do not mimic physiologic insulinemia, particularly in the basal state. Doctors regard blood glucose measurements as an essential part of diabetic management and extension of this technology to patients has added a new dimension, particularly in the assessment of control. Nevertheless, home blood-glucose monitoring will not necessarily improve diabetic control; the best results have been obtained when it has been offered as part of a package deal which includes more investment of time and interest by patients and doctor together with joint discussions of problems and changes in treatment. The biggest problem with conventional twice daily insulin regimens is to sustain constant basal insulin levels during the night. Attempts to obtain fasting normoglycemia with an injection before supper often result in nocturnal hyperinsulinemia and hypoglycemia. This can usually be resolved by changing to a three times daily regimen with an extra injection of NPH insulin at bedtime. Three times daily insulin injections with feedback from home blood-glucose monitoring give as good blood glucose control as infusion systems and are cheaper and more acceptable to patients.

Factors associated with nocturnal bruxism and its treatment

Using a single-subject design, two methods of treating nocturnal bruxism were evaluated. Neither technique was successful; both resulted in a rebound effect when treatment was stopped. In addition, the role of anxiety in bruxing behavior was evaluated. Contrary to most theoretical beliefs, bruxing resulting from anxiety was not as important as "anticipatory" anxiety resulting in bruxing.

Biofeedback in the treatment of long-term temporomandibular joint pain: an outcome study

Eleven patients with long-term pain related to the temporomandibular joint (TMJ) were trained in tension awareness and relaxation using feedback of muscle tension level in the masseter through a digital display. At a follow-up examination 4-15 months after the termination of treatment, 8 of the 11 patients were totally symptom-free or significantly better; 1 patient was slightly better, and there was no effect for 2 patients. Possible reasons for failure and sex differences are discussed.

The use of relaxation and distraction to reduce psychological stress during dental procedures

Relaxation and distraction techniques designed to reduce stress during operative dental procedures were evaluated with a number of different measures. The results indicate that both techniques can be effective in alleviating anxiety and reducing stress. Some findings suggested that relaxation was more effective with women than with men whereas distraction may be more effective with men than with women. Further research is needed to refine these techniques that should be readily adaptable to dental practice.

Detecting radiographic knee osteoarthritis: what combination of views is optimal?

OBJECTIVE

The failure to image the patellofemoral joint or the posterior knee compartment when evaluating persons for knee osteoarthritis may result in missed cases. While the skyline view has been recommended due to more reproducible assessment of the patellofemoral joint space, the lateral view may be easier to acquire and provides different information. We evaluated the sensitivity of different combinations of X-ray views (anteroposterior and lateral; anteroposterior and skyline; all three views) in 377 persons with knee symptoms who had all three views available and had a definite osteophyte on at least one view.

RESULTS

Of the different views, skylines had to be excluded most often because the image of the patellofemoral joint was technically unsatisfactory. In the remaining knees, adding either a lateral or a skyline view to an anteroposterior view yielded roughly equal and high sensitivity (94-97%) when compared with the gold standard of a positive X-ray on any of the three views.

CONCLUSION

As long as at least an anteroposterior view and one image of the patellofemoral joint is obtained (either skyline or lateral), few cases with radiographic disease will be missed. For clinical or epidemiological studies the lateral view may be easier to acquire with high quality than the skyline view.

Three-year clinical comparison of three amalgam alloy types emphasizing an appraisal of the evaluation methods used

Five different evaluation techniques were used to measure the marginal breakdown of three-year-old amalgam restorations. The most useful method appeared to be one in which photographs of all restorations were ranked in descending order starting with the restoration that had the least marginal breakdown and ending with the restoration that had the greatest deterioration. Three different alloys were evaluated and the results confirm those of previous studies; the alloy having the lowest creep was superior whereas restorations placed with the alloy having the highest creep displayed the greatest marginal breakdown.

The role of retinoic acid in the morphogenesis of the neural tube

We have examined the role of the signalling molecule, retinoic acid, in the process of neurulation and the subsequent growth and differentiation of the central nervous system using quail embryos that have developed in the absence of retinoic acid. Such retinoic acid-free embryos undergo abnormal neural tube formation in terms of its shape and structure, but the embryos do not display spina bifida or exencephaly. The neural tubes have a wider floor plate, a thicker roof plate and a different dorsoventral shape. Phalloidin staining and electron microscopy revealed alterations in the actin filaments and the junctional complexes of the cell layer lining the lumen. Initially the neural tubes proliferated at the same rate as normal, but later the proliferation rate declined drastically and neuronal differentiation was highly deficient. There were very few motoneurons extending neurites into the periphery, and within the neural tube axon trajectories were chaotic. These results reveal several functions for retinoic acid in the morphogenesis and growth of the neural tube, many of which can be explained by defective notochord signalling, but they do not suggest that this molecule plays a role in neural tube closure.

Treatment of temporomandibular joint syndrome with biofeedback training

Treatment of temporomandibular joint syndrome by the use of biofeedback training involves two stages. First, the patient is made aware of the level of tension in the masseter muscle and, second, he is taught to reduce the level of tension. In those individuals whose pain most likely is associated with high muscle tension, this treatment method is apparently successful. The successful treatment of a patient with a history of long-term TMJ pain is described.

Stress-induced muscular activity in mandibular dysfunction: effects of biofeedback training

Surface electromyographic (EMG) recordings from the left and right masseteric areas during physical and psychological induced stress were obtained from 20 patients with mandibular dysfunction and 20 healthy controls. Integrated electromyographic activity was not significantly different for the two sides but was higher for patients than for controls during both stress and relaxation. Anxiety level, as measured with the Taylor Manifest Anxiety Scale, was higher for patients. Biofeedback treatment for the patients resulted in significantly reduced signs and symptoms of mandibular dysfunction. When the test procedures were repeated, the controls had not changed in their electromyographic responses during stress, whereas the patients showed a significant decrease in this respect. The results obtained are discussed in terms of a systems-oriented etiological concept.

A method for assessing the clinical solubility and disintegration of luting cements

A test was designed for evaluating the distintegration of cementing agents in the oral cavity. The cements were placed in small holes located in the proximal surfaces of cast gold restorations so that the materials were not subject to abrasion. Each cement was placed in one hole located occlusally and one located gingivally. Four commercial cements of four different types (zinc phosphate, zinc silicophosphate, polycarboxylate, and EBA-Alumina zinc oxide/eugenol) were tested in 15 patients, and differences were observed in the deterioration rates of the different cements over the 6 month period. The disintegration rate of a given cement was the same in the gingival and occlusal positions. No correlation was observed between the clinical data on loss of material and the solubility of the cements as measured by conventional in vitro tests.