Neurophysiologic and long-term effects of clinical hypnosis in oral and maxillofacial treatment--a comparative interdisciplinary clinical study

Efficacy of Hypnosis on Dental Anxiety and Phobia: A Systematic Review and Meta-Analysis

Hypnosis is a commonly used therapy option in dentistry and medicine for fear and pain reduction. Nevertheless, it is viewed very critically, as there is still insufficient evidence for a treatment effect. Specific phobia of dental treatment and dental anxiety are prevalent conditions that can cause an oral health impairment. This paper critically reviews 19 clinical trials aimed at reducing dental anxiety and fear avoidance in adults, published in peer-reviewed journals between 1979 and 2021. The search identified 257 papers; 223 were selected after removing duplicates. A total of 188 articles were excluded after title and abstract evaluation; 35 full text articles were assessed for eligibility. Another 10 papers were discharged after full text evaluation, as these were case reports and questionnaires. Six papers were discharged due to the lack of a comparable scale to measure dental anxiety. The following treatment techniques were reviewed: various forms of cognitive-behavioral therapy (CBT), relaxation training, benzodiazepine premedication, self-hypnosis by audio therapy, hypnotherapy, hypnosis, and nitrous oxide sedation. CBT delivered in a variety of formats, including one-session treatment, showed the most evidence for the efficacy of reducing anxiety. A wide heterogeneity of methods allowed only the inclusion of five studies to the performed meta-analysis, showing contrasting results for the application of hypnosis. The main reason for this issue is the great variety in methods used, making a distinct assessment of hypnotic interventions difficult. However, the results of the systematic review are promising in that hypnosis can also be regarded as powerful and successful method for anxiety reduction, while there are also studies with a small or even slightly negative effect. Therefore, further research is needed. Within the limitations of the current study, a more consistent use of methods to examine anxiety for hypnosis research is recommended.

Functional Changes in Brain Activity Using Hypnosis: A Systematic Review

Hypnosis has proven a powerful method in indications such as pain control and anxiety reduction. As recently discussed, it has been yielding increased attention from medical/dental perspectives. This systematic review (PROSPERO-registration-ID-CRD42021259187) aimed to critically evaluate and discuss functional changes in brain activity using hypnosis by means of different imaging techniques. Randomized controlled trials, cohort, comparative, cross-sectional, evaluation and validation studies from three databases—Cochrane, Embase and Medline via PubMed from January 1979 to August 2021—were reviewed using an ad hoc prepared search string and following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. A total of 10,404 articles were identified, 1194 duplicates were removed and 9190 papers were discarded after consulting article titles/abstracts. Ultimately, 20 papers were assessed for eligibility, and 20 papers were included after a hand search (n^total = 40). Despite a broad heterogenicity of included studies, evidence of functional changes in brain activity using hypnosis was identified. Electromyography (EMG) startle amplitudes result in greater activity in the frontal brain area; amplitudes using Somatosensory Event-Related Potentials (SERPs) showed similar results. Electroencephalography (EEG) oscillations of θ activity are positively associated with response to hypnosis. EEG results showed greater amplitudes for highly hypnotizable subjects over the left hemisphere. Less activity during hypnosis was observed in the insula and anterior cingulate cortex (ACC).

FUNCTIONAL CHANGES IN BRAIN ACTIVITY AFTER HYPNOSIS: Neurobiological Mechanisms and Application to Patients with a Specific Phobia-Limitations and Future Directions

Studies of brain-plasticity changes in hypnosis using functional magnetic resonance imaging (fMRI), positron-emission-tomography (PET) and electroencephalography (EEG) were reviewed. The authors found evidence in those studies that hypnosis is a powerful and successful method for inhibiting the reaction of the fear circuitry structures. Limitations of the studies were critically discussed, and implications for future research were made. The authors are currently using a portable fNIRS apparatus to integrate the scanning device into real life situations in medical practice. Their aim is to disentangle the neuronal mechanisms and physiological correlates in patients with severe fear of medical treatments when directly confronted with anxiety-provoking stimuli and to assess the effects of a brief hypnosis. Drawing on evidence from several technological modalities, neuroimaging and physiological studies pave the road to a better scientific understanding of neural mechanisms of hypnosis.

Comparison of conventional therapies for dentin hypersensitivity versus medical hypnosis

This study compared the efficacy of conventional treatments for dentin hypersensitivity (DHS) and hypnotherapy. During a 1-month period at an urban practice in a service area of approximately 22,000 inhabitants, all patients were examined. A total of 102 individuals were included in the evaluation. Values of 186 teeth were analyzed. The comparison of the different treatment methods (desensitizer, fluoridation, and hypnotherapy) did not show significant differences in success rates. However, a noticeable difference was observed in terms of onset and duration of effect. For both desensitizer and hypnotherapy treatments, onset of effect was very rapid. Compared to the other methods studied, hypnotherapy effects had the longest duration. In conclusion, hypnotherapy was as effective as other methods in the treatment of DHS.

Neurophysiological attributes of the hypnotic state and the utility of hypnosis in pediatric medicine and burn care

Three articles of special interest to the hypnosis community recently appeared in the general scientific and medical literatures. The first paper is a thoughtful review of the clinical applications of hypnosis in pediatric settings. The second article reports the findings of a randomized, controlled trial of hypnosis for burn-wound care, carried out at the University of Washington Medical School. The third article describes an innovative EEG laboratory case study tracking the cortex functional connectivity of a highly hypnotizable subject across various baseline and experimental conditions. These three articles are sturdy examples of how hypnosis illuminates (and is illuminated by) medical and psychological science.

Salient findings: hypnotizability as core construct and the clinical utility of hypnosis

Six papers of special interest to the hypnosis community have recently appeared in the general scientific literatures. Three of these papers were published as part of the 2006 Cochrane Collaboration on the utility of medical interventions. These reviews analyze the research literature on the efficacy of hypnosis for treatment of needle-related pain in children, pain management during childbirth, and conversion disorder. Hypnosis is the most promising psychological intervention studied for needle-related procedural pain and distress in children and adolescents; it is effective as an adjunctive analgesic during childbirth; and it is of uncertain usefulness in treatment of conversion disorder. A second cluster of three studies unambiguously demonstrates the central role of hypnotizability as a predictor of responsiveness in laboratory, analogue treatment, and medical practice settings. One of these articles may well be the most important hypnosis paper in many years.