Occlusal dysesthesia: a qualitative systematic review of the epidemiology, aetiology and management

Biological and psychological factors affecting the sensory and jaw motor responses to orthodontic tooth movement

Orthodontic tooth movement (OTM) is associated with an inflammatory response, tooth pain (i.e. orthodontic pain) and changes in dental occlusion. Clinical realms and research evidence suggest that the sensory and jaw motor responses to OTM vary significantly among individuals. While some adjust well to orthodontic procedures, others may not and can experience significant pain or not adjust to occlusal changes. This is of concern, as clinicians cannot anticipate an individual's sensorimotor response to OTM. Converging evidence shows that some psychological states and traits significantly affect the sensorimotor response to OTM and may considerably affect an individual's adaptation to orthodontic or other dental procedures. We performed a topical review to synthesize the available knowledge about the behavioural mechanisms regulating the sensorimotor response to OTM, with the intent of informing orthodontic practitioners and researchers about specific psychological states and traits that should be considered while planning orthodontic treatment. We report on studies focusing on the role of anxiety, pain catastrophising, and somatosensory amplification (i.e. bodily hypervigilance), on sensory and jaw motor responses. Psychological states and traits can significantly affect sensory and jaw motor responses and a patient's adaptation to orthodontic procedures, although large interindividual variability exists. Clinicians can use validated instruments (checklists or questionnaires) to collect information about patients' psychological traits, which can assist in identifying those individuals who may not adjust well to orthodontic procedures. The information included in this manuscript also assists researchers investigating the effect of orthodontic procedures and or/appliances on orthodontic pain.

Associations between obstructive sleep apnea and dental pain and chewing discomfort in Korean adults: a nationwide cross-sectional study

Obstructive sleep apnea (OSA) may be linked with oral health issues. This study evaluated the associations between OSA, dental pain, and chewing discomfort. Big data from a nationwide survey involving 6984 participants aged ≥ 40 years were analyzed. The STOP-Bang questionnaire was used to assess the OSA risk, categorizing the participants into low-, intermediate-, and high-risk groups. The associations of OSA risk with dental pain and chewing discomfort were evaluated using multivariate logistic regression analyses (α = 0.05). Results revealed that 50.33%, 37.50%, and 12.17% of the population belonged to the low-, intermediate-, and high-risk groups, respectively. After adjusting for covariates, a significant association emerged between OSA risk and dental pain, with adjusted odds ratios (95% confidence intervals) of 1 (reference), 1.208 (1.003-1.455), and 1.472 (1.131-1.916) for the low-, intermediate-, and high-risk groups, respectively (p = 0.0156). The adjusted odds ratio for chewing discomfort in the high-risk OSA group was 1.307 (0.977-1.748), although not significantly different from that of the low-risk group (p > 0.05). A high risk of OSA was associated with 1.472-fold increased risk of dental pain compared to those at low risk, implicating OSA as a potential risk indicator of poor oral health.

Postoperative dysesthesia after PVCR without anterior support applied in Yang's type A severe spinal kyphoscoliosis

Backgrounds

The incidence and characteristics of postoperative dysesthesia (POD) have not been reported for posterior vertebral column resection (PVCR) in the treatment of severe spinal kyphoscoliosis.

Objective

The objective of the study is to investigate the incidence and characteristics of POD in PVCR without anterior support applied in Yang's type A severe spinal kyphoscoliosis.

Material and methods

From August 2010 to December 2019, 167 patients diagnosed with Yang's type A severe spinal kyphoscoliosis who underwent PVCR without anterior support applied were retrospectively reviewed. All the patients were monitored using five modes of intraoperative multimodal neurophysiological monitoring. Neuromonitoring data, radiographic parameters, and neurological complications were reviewed and analyzed. The incidence and characteristics of POD were further summarized. POD was defined as dysesthetic pain or burning dysesthesia which could be caused by spinal cord kinking or dorsal root ganglion (DRG) injury but with no motor deficits.

Results

PVCR without anterior support was successfully conducted in all 167 patients. Intraoperative monitoring events occurred in five patients. One out of these five patients showed postoperative spinal cord injury (Frankel level C) but completely recovered within 9 months postoperation (Frankel level E). The number of levels and osteotomy space for vertebra resection were 1.28 and 3.6 cm, respectively. POD was confirmed in three patients (3/167, 1.8%), characterized as kyphosis with the apex vertebrae in T12 with the kyphotic Cobb angles of 100°, 115°, and 122°, respectively. The osteotomy space of vertebra resection in these three patients were 3.9, 3.8, and 4.2 cm, respectively. After the treatment by drug administration, they reported pain relief for 12-36 days. The pain gradually moved to the distal end of a proper DRG innervated region near the end.

Conclusions

In this study, the incidence rate of POD in Yang's type A severe spinal kyphoscoliosis patients who underwent PVCR without anterior support applied was 1.8% (3/167). Evoked potential monitoring could not detect the occurrence of POD. POD in Yang's type A severe spinal kyphoscoliosis after PVCR could be ascribed to spinal cord kinking and DRG injury.

Occlusal Disharmony-A Potential Factor Promoting Depression in a Rat Model

Objectives: Patients with occlusal disharmony (OD) may be susceptible to depression. The hypothalamus−pituitary−adrenal axis, 5-HT and 5HT2AR in the prefrontal cortex (PFC), amygdala, and hippocampus are involved in the modulation of emotion and depression. This study investigated whether OD affects the HPA axis and 5-HT system and, subsequently, produces depression-like behaviors in rats. Materials and methods: OD was produced by removing 0.5 and 0.25 mm of hard tissue from the cusps of the maxillary molars in randomly selected sides of Sprague−Dawley rats. CUS involved exposure to 2 different stressors per day for 35 days. OD-, CUS-, and OD + CUS-treated groups and an untreated control group were compared in terms of behavior, endocrine status and brain histology. Results: There were significant differences among the four groups in the behavior tests (p < 0.05), especially in the sucrose preference test, where there was a significant decrease in the OD group compared to the control group. ACTH and CORT concentrations were significantly higher in the OD + CUS group than the control group (p < 0.05). Expression of GR and 5-HT2AR in the PFC, amygdala and hippocampal CA1 was significantly higher in the OD, CUS and OD + CUS groups than the control group (p < 0.05). Conclusion: OD promotes depression-like behaviors through peripheral and central pathways via the HPA axis, GR and 5-HT system.

Phantom bite syndrome: Revelation from clinically focused review

Phantom bite syndrome (PBS), also called occlusal dysesthesia, is characterized by persistent non-verifiable occlusal discrepancies. Such erroneous and unshakable belief of a “wrong bite” might impel patients to visit multiple dental clinics to meet their requirements to their satisfaction. Subsequently, it takes a toll on their quality of life causing, career disruption, financial loss and suicidal thoughts. In general, patients with PBS are quite rare but distinguishable if ever encountered. Since Marbach reported the first two cases in 1976, there have been dozens of published cases regarding this phenomenon, but only a few original studies were conducted. Despite the lack of official classification and guidelines, many authors agreed on the existence of a PBS “consistent pattern” that clinicians should be made aware. Nevertheless, the treatment approach has been solely based on incomplete knowledge of etiology, in which none of the proposed theories are fully explained in all the available cases. In this review, we have discussed the critical role of enhancing dental professionals’ awareness of this phenomenon and suggested a comprehensive approach for PBS, provided by a multidisciplinary team of dentists, psychiatrists and exclusive psychotherapists.

Occlusal disharmony and chronic oro-facial pain: from clinical observation to animal study

BACKGROUND

Occlusion can be viewed as the most sensitive susceptor of the central nervous system in the oro-facial region. Its inalienable relationships to the temporomandibular joint, the muscles, the stomatognathic system and even the central nervous system are self-evident. Almost all the dental treatments inevitably change the occlusion, potentially or actually, locally or extensively, and immediately or gradually.

OBJECTIVE

The objective of this study was to present a narrative literature on occlusal disharmony and chronic oro-facial pain.

METHODS

Literature reviews focusing on clinical studies about the relationship between occlusal disharmony and myofascial oro-facial pain, and related preclinical studies about the animal models of, as well as the peripheral and central mechanisms underlying this condition related to, occlusal disharmony were used as starting point and guidelines to describe the topics mentioned. A search of the PubMed database was performed mainly with the following search terms: "occlusion," "occlusal interference," "occlusal disharmony," "occlusal change," "oro-facial pain" and "myofascial pain."

RESULTS

Relevant literature from the past 70 years until the present day was meticulously studied. The literature review together with three related characteristic clinical cases revealed an intimate association between occlusal disharmony and chronic oro-facial pain, involving pathological changes, extending from the peripheral tissues to the central nervous system. The patients suffered from psychological distress, sleep disturbance and poor life quality.

CONCLUSION

Occlusal disharmony-related oro-facial pain is a clinical problem that deserves attention, although there are no universally accepted clinical protocols. The existing literature provides some constructive suggestions, but further research is needed.

Case Report: Iatrogenic Dental Progress of Phantom Bite Syndrome: Rare Cases With the Comorbidity of Psychosis

Introduction: Phantom bite syndrome (PBS) is considered as the preoccupation with dental occlusion and the continual inability to adapt to changed occlusion. These patients constantly demand occlusal corrections and undergo extensive and excessive dental treatments. We present three cases with PBS-suspected iatrogenic concerns and the attribution to underlying psychosis. Case Presentation: A 70-year-old female demanded orthodontic retreatment and complained of tightness and cramped sensation of teeth in the oral cavity, uncomfortable occlusion, and pain in her neck and legs that she was convinced was induced by orthodontic treatment. However, even earlier than the orthodontic treatment, she had kept doctor shopping for over 35 years, not merely dentists but also psychiatrists, neurologists, and so on; she was diagnosed with bipolar disorder. A 48-year-old female complained of malaligned improper occlusion and demanded occlusal adjustment. These symptoms occurred in the absence of a dental trigger and were worsened by orthodontic treatment. She underwent psychiatric treatment for 15 years with a diagnosis of bipolar disorder. A 38-year-old female, who had a history of schizophrenia for over 20 years, complained of occlusal discomfort and revisited with a complaint of abnormal occlusion due to excessive dental procedures. In the last two cases, requests for dental procedures had reduced owing to the collaboration between the psychiatrists and dentists. All the cases first visited our clinic following a succession of dental visits. They were strongly convinced that occlusal correction was the only solution to their symptoms, including the symptoms of discomfort in other body parts. Their misleading perceptions were uncorrectable, and repeated dental treatments exacerbated their complaints. Moreover, the dentists overlooked the psychotic histories of the patients, while the comorbid psychosis resulted in a strict demand for dental treatment by the patients. Conclusions: The presented PBS cases with psychosis suggest that repeated dental treatments and comorbid psychosis exacerbate PBS. Moreover, their persistent demands reflecting comorbid psychosis led dentists to perform numerous procedures. Early detection of underlying psychosis and the prompt collaboration between psychiatrists and dentists are integral to help prevent complications in PBS cases with psychosis.

Physical, psychological and socio-demographic predictors related to patients' self-belief of their temporomandibular disorders' aetiology

BACKGROUND

The aetiology of temporomandibular disorders (TMDs) has been widely discussed in literature, but little is known about patients' self-belief of their TMD aetiology.

OBJECTIVE

For six categories of self-believed aetiology of the TMD complaint (viz., occlusal factors, physical trauma, emotional stress, deep pain input, parafunctions and unknown), associations with physical, psychological and socio-demographic predictors were assessed.

METHODS

In this retrospective study, medical records of 328 TMD patients who had visited a clinic for Orofacial Pain and Dental Sleep Medicine were analysed.

RESULTS

The most frequently reported self-believed TMD aetiology was 'unknown' (42.3%). The category 'occlusal factors' was associated with pain worsening with emotion. 'Physical trauma' as self-believed aetiology was associated with TMD dysfunction score. 'Emotional stress' was associated with awake bruxism and age 18-49 years. 'Deep pain input' was associated with TMD dysfunction score, sleep bruxism, and arthritis or joint pain. 'Parafunctions' were associated with sleep bruxism. 'Unknown' was associated with TMD symptoms severity and work disability.

CONCLUSION

For each category of self-believed aetiology of the TMD complaint, different associations with physical, psychological and socio-demographic predictors were identified. This may suggest that individual phenotypes play a role in the patient's belief in the cause of the TMD complaint. Determination of phenotypic risk factors associated with aetiological self-belief might help clinicians to provide better treatment, including counselling, to their patients.

Prevalence and risk indicators of non-carious cervical lesions in male footballers

Background

Non-carious cervical lesions (NCCLs) have shown a significant incidence and prevalence and have been increasingly associated with people’s lifestyles and youths. This cross-sectional study aimed to determine the prevalence of NCCLs in footballers and to address potential risk indicators.

Methods

Fourty-three male semi-professional footballers with an average of 27 years old completed a questionnaire and were subjected to intraoral examination in terms of cervical tooth wear, morphological characteristics of NCCLs, tooth sensitivity, occlusal/incisal wear, and malocclusion classification. Also, laboratory assays were performed to determine salivary parameters: flow rate, pH, buffer capacity, level of Ca (calcium), Na (sodium), and K (potassium) ions, and level of cortisol. The data obtained from the questionnaire and intraoral examinations were subjected to Chi-square and Poisson regression models while the data obtained from the laboratory assays were analyzed by using analysis of variance (p <  0.05).

Results

The prevalence of NCCLs was 39.5%. The participants presented predominantly initial lesions with signs of mechanical stress. The daily training time was found as a significant risk indicator (p = 0.028). The multivariate analysis showed a significant difference in the variables daily training time (p = 0.023), lemon water intake while fasting (p = 0.002), toothpaste type (p = 0.004), tooth sensitivity (p = 0.006); previous orthodontic treatment (p = 0.003), and occlusion type (p = 0.008). All participants presented normal salivary parameters and levels of cortisol.

Conclusion

The prevalence of NCCLs among footballers was remarkable. The premolars were the most affected teeth and presented symptoms/signs of initial lesions. The daily training time was a dominant risk indicator of NCCLs development. Footballers presented adequate salivary parameters and cortisol levels.

Occlusal dysesthesia-A clinical guideline

Background

The diagnosis and management of patients suffering from occlusal dysesthesia (OD) remain a major challenge for dental practitioners and affected patients.

Objectives

To present the results of a literature‐based expert consensus intended to promote better understanding of OD and to facilitate the identification and management of affected patients.

Methods

In 2018, electronic literature searches were carried out in PubMed, Cochrane Library and Google Scholar as well as in the archives of relevant journals not listed in these databases. This approach was complemented by a careful assessment of the reference lists of the identified relevant papers. The articles were weighted by evidence level, followed by an evaluation of their contents and a discussion. The result represents an expert consensus.

Results

Based on the contents of the 77 articles identified in the search, the current knowledge about clinical characteristics, epidemiology, aetiology, diagnostic process, differential diagnosis and management of OD is summarised.

Conclusions

Occlusal dysesthesia exists independently of the occlusion. Instead, it is the result of maladaptive signal processing. The focus should be on patient education, counselling, defocusing, cognitive behavioural therapy, supportive drug therapy and certain non‐specific measures. Irreversible, specifically an exclusively dental treatment approach must be avoided.

Comparison of Cerebral Blood Flow Patterns in Patients with Phantom Bite Syndrome with Their Corresponding Clinical Features

BACKGROUND

Phantom bite syndrome (PBS) is characterized by an uncomfortable sensation during occlusion without any evident abnormality. A recent case-control study with single-photon emission computed tomography (SPECT) using ^99mTc-ethyl cysteinate dimer could not find the specific features of regional cerebral blood flow (rCBF), which might be due to the heterogeneity of PBS. We analyzed the brain images of PBS corresponding to the clinical features by studying PBS subgroups.

METHODS

This study contributes to elucidating the pathophysiology of PBS by evaluating regional brain perfusion on SPECT and its clinical features. We performed SPECT using ^99mTc-ethyl cysteinate dimer in 44 patients with PBS. The SPECT images were analyzed qualitatively and quantitatively.

RESULTS

Asymmetrical rCBF patterns were detected, corresponding to symptom laterality. Patients with PBS with right-side symptoms showed right-side-predominant rCBF asymmetry in the parietal region and left-side-predominant rCBF asymmetry in the thalamus, and vice versa. Moreover, the analysis of the association between rCBF and patient behaviors revealed that patients who blamed their dentists for their symptoms tended to have a symmetrical rCBF pattern.

CONCLUSION

Patients with PBS showed blood flow imbalance in the thalamus and parietal region corresponding to symptom laterality. There are two types of symmetrical and asymmetrical rCBF patterns in the pathophysiology of PBS despite similar clinical manifestations.

Comorbid depressive disorders and left-side dominant occlusal discomfort in patients with phantom bite syndrome

BACKGROUND

Phantom bite syndrome (PBS) is characterised by occlusal discomfort without corresponding dental abnormalities. Despite repeated, failed dental treatments, patients with PBS persist in seeking bite correction. PBS has been regarded as a mental disorder. However, we have reported that PBS patients with a dental trigger tend to have less psychiatric history than those without. Hence, the symptoms of PBS cannot be explained by a mental disorder alone, and it is unclear if mental disorders affect occlusal sensation.

OBJECTIVE

To elucidate the pathophysiology of PBS, we analysed the dental history, PBS symptom laterality and psychiatric history of patients.

METHODS

In this retrospective study, we reviewed outpatients with PBS who presented at our clinic between April 2012 and March 2017. Their medical records were reviewed for demographic data, medical history and laterality of occlusal discomfort.

RESULTS

Approximately half of the 199 enrolled patients had bilateral occlusal discomfort. In the others, the side with occlusal discomfort generally tended to be the one that had received dental treatment. There was no significant relationship between the side chiefly affected by occlusal discomfort and whether dental treatment had been received; however, the affected side differed depending on whether the patient had comorbid psychiatric disorders (P = .041).

CONCLUSIONS

The distributions of the side with symptoms of PBS were different between those with and without comorbid psychiatric disorders, suggesting that psychiatric disorders might affect occlusal sensation due to a subtle dysfunction in brain areas central to sensory integration. Central dysfunction might play an important role in PBS.

Change of Cerebral Blood Flow After a Successful Pharmacological Treatment of Phantom Bite Syndrome: A Case Report

Background

“Phantom bite syndrome,” a persistent complaint of an uncomfortable bite sensation with no obvious occlusal abnormal finding, recently was suggested to be related with central nervous system dysfunction. Here, we report a case of phantom bite syndrome in which the occlusal discomfort was improved with mirtazapine and aripiprazole combination parallel with regional cerebral blood flow change.

Case report

A 60-year-old-female patient came to our clinic with the chief complaint of a “loosely bite” after dental treatment and various uncomfortable sensations of body sites. One year after the medication therapy, the prosthodontic retreatment was carried out successfully, and a good outcome was obtained for over 24 months so far. In addition, a subsequent change of regional cerebral blood flow was observed in single-photon emission computed tomography: the right and left asymmetry of cerebral blood flow in the frontal lobe has disappeared along with the improvement to the symptoms improvement.

Conclusions

This case suggests that some central nervous system dysfunction involving dopaminergic system might be related to the pathophysiology of phantom bite syndrome.

A multi-centered epidemiological study evaluating the validity of the treatment difficulty indices developed by the Japan Prosthodontic Society

PURPOSE

The Japan Prosthodontic Society developed a multi-axis assessment protocol to evaluate the complex variations in patients who need prosthodontic care, and to classify the level of treatment difficulty. A previous report found the protocol to be sufficiently reliable. The purpose of this multi-center cohort study was to evaluate the validity of this multi-axis assessment protocol.

METHODS

The treatment difficulty was evaluated using the multi-axis assessment protocol before starting prosthodontic treatment. The time required for active prosthodontic treatment, medical resources such as treatment cost, and changes in the oral health-related QOL before and after treatment, were evaluated after treatment completion. The construct validity of this protocol was assessed by the correlation between the dentist's pre-operative subjective assessment of the treatment difficulty, and the level of difficulty determined by this protocol. The predictive validity was assessed estimating the correlations between a "comprehensive level of treatment difficulty" based on the four axes of this protocol and total treatment cost, total treatment time, and changes in the oral health-related QOL before and after treatment.

RESULTS

The construct validity of this protocol was well documented except for psychological assessment. Regarding the predictive validity, the comprehensive level of treatment difficulty assessed before treatment was significantly correlated with the three surrogate endpoints known to be related to the treatment difficulty (total treatment cost, treatment time, and improvement in the oral health-related QOL). To further clarify the validity of the protocol according to patients' oral condition, a subgroup analysis by defects was performed. Analyses revealed that treatment difficulty assessment before treatment was significantly related to one or two surrogate endpoints in the fully edentulous patients and the partially edentulous patients. No significant relationship was observed in the patients with mixture of full/partial edentulism and the patients with teeth problems, possibly due to the small sample size in these groups.

CONCLUSION

This study revealed that the multi-axis assessment protocol was sufficiently valid to predict the level of treatment difficulty in prosthodontic care in patients with fully edentulous defects and with partially edentulous defects.

The postoperative trismus, nerve injury and secondary angle formation after partial masseter muscle resection combined with mandibular angle reduction: a case report

A patient, who underwent partial masseter muscle resection and mandibular angle reduction at a plastic surgery clinic, visited this hospital with major complaints of trismus and dysesthesia. A secondary angle formation due to a wrong surgical method was observed via clinical and radiological examinations, and the patient complained of trismus due to the postoperative scars and muscular atrophy caused by the masseter muscle resection. The need for a masseter muscle resection in square jaw patients must be approached with caution. In addition, surgical techniques must be carefully selected in order to prevent complications, and obtain effective and satisfactory surgery results.

Diagnosis of occlusal dysesthesia utilizing prefrontal hemodynamic activity with slight occlusal interference

Clinical diagnosis of occlusal dysesthesia (OD), also referred to as phantom bite syndrome, is currently based on the absence of objective occlusal discrepancy despite the persistent complaint of uncomfortable bite sensation. We previously demonstrated that the subjective feeling of occlusal discomfort generated by artificial occlusal interference can be objectively evaluated using prefrontal hemodynamic activity in young healthy individuals. The aim of this study was to investigate whether dental patients with and without OD show distinct prefrontal activity during grinding behavior with an occlusal interference. Six dental patients with OD (OD group) and eight patients without OD (control group) grinded piled occlusal strips placed between their first molars and reported their perception and discomfort thresholds during continuous monitoring of prefrontal hemodynamic activity with a portable functional near-infrared spectroscopy. Although patients without OD showed the typical hemodynamic pattern of increased oxyhemoglobin and reduced deoxyhemoglobin (HHb) concentration, those with OD showed persistent incremental increases of HHb concentration that began at the loading of occlusal strips on their molars before they executed grinding. The intensities of the task-related HHb activities showed statistically significant differences between OD and control groups, particularly at channel 3, arranged over the left frontal pole cortex. When the discrimination criterion was set using the intensity values of channel 3 from both groups, the overall accuracy of the OD discrimination was 92.9%. Although physiological interpretation has yet to be elucidated, the task-related response of an increase in HHb may be a useful neuronal signature to characterize dental patients with OD.

Psychosomatic problems in dentistry

Many dental patients complain of oral symptoms after dental treatment, such as chronic pain or occlusal discomfort, for which the cause remains undetermined. These symptoms are often thought to be mental or emotional in origin, and patients are considered to have an "oral psychosomatic disorder". Representative medically unexplained oral symptoms/syndromes (MUOS) include burning mouth syndrome, atypical odontalgia, phantom bite syndrome, oral cenesthopathy, or halitophobia. With an increasing prevalence of these MUOS, dentists are being asked to develop new approaches to dental treatment, which include taking care of not only the patient's teeth but also the patient's suffering. Progress in the understanding of mind-body interactions will lead to investigations on the pathophysiology of MUOS and the development of new therapeutic approaches.

Prefrontal Hemodynamic Changes Associated with Subjective Sense of Occlusal Discomfort

We used functional near-infrared spectroscopy to measure prefrontal brain activity accompanying the physical sensation of oral discomfort that arose when healthy young-adult volunteers performed a grinding motion with mild occlusal elevation (96 μm). We simultaneously evaluated various forms of occlusal discomfort using the visual analogue scale (VAS) and hemodynamic responses to identify the specific prefrontal activity that occurs with increased occlusal discomfort. The Oxy-Hb responses of selected channels in the bilateral frontopolar and dorsolateral prefrontal cortices increased in participants who reported increased severity of occlusal discomfort, while they decreased in those who reported no change or decreased occlusal discomfort during grinding. Moreover, the cumulative values of Oxy-Hb response in some of these channels were statistically significant predictive factors for the VAS scores. A generalized linear model analysis of Oxy-Hb signals in a group of participants who reported increased discomfort further indicated significant cerebral activation in the right frontopolar and dorsolateral prefrontal cortices that overlapped with the results of correlation analyses. Our results suggest that the increased hemodynamic responses in the prefrontal area reflect the top-down control of attention and/or self-regulation against the uncomfortable somatosensory input, which could be a possible marker to detect the subjective sense of occlusal discomfort.

Psychiatric comorbidities and psychopharmacological outcomes of phantom bite syndrome

OBJECTIVE

Phantom bite syndrome (PBS) is characterized by a persistent uncomfortable sensation of occlusion without an evident occlusal discrepancy. The aims of this retrospective cross-sectional study were to assess psychiatric comorbidities and evaluate psychopharmacological outcomes of PBS.

METHODS

The database of the Psychosomatic Dentistry Clinic of Tokyo Medical and Dental University Dental Hospital was reviewed for cases of PBS diagnosed between April 2009 and March 2012. Clinical Global Impression indices were used to assess psychopharmacological outcomes.

RESULTS

The review revealed 130 patients (107 women, 23 men) with a mean age of 53.0 ±13.1 years. They previously visited 4.4 ±3.4 dental clinicsand had a mean symptom duration of 5.3 ±5.4 years. Only 24 (18.5%) of 63 (48.5%) patients with psychiatric comorbidities had schizophrenia, major depressive disorder, or bipolar disorder. The frequency of psychiatric comorbidities was significantly lower in PBS with a dental trigger than that without a specific trigger. Moreover, patients without a psychiatric comorbidity showed significantly better outcomes than those with a psychiatric comorbidity. Forty patients (30.8%) showed remarkable clinical improvement after receiving amitriptyline, mirtazapine, or aripiprazole.

CONCLUSION

PBS is generally not associated with severe psychiatric disorders. Absence of a dental trigger predicts a psychiatric comorbidity, which affects the psychopharmacological outcome. Antidepressant or antipsychotic therapy may be effective for symptom management in PBS.

Identification and adjustment of experimental occlusal interference using functional magnetic resonance imaging

BACKGROUND

The purpose of this study was to use functional magnetic resonance imaging (fMRI) to quantify changes in brain activity during experimental occlusal interference.

METHODS

Fourteen healthy volunteers performed a rhythmical tapping occlusion task with experimental occlusal interference of the right molar tooth at 0 mm (no occlusion), 0.5 mm, and 0.75 mm. The blood-oxygen-level dependent (BOLD) signal was quantified using statistical parametric mapping and compared between rest periods and task periods.

RESULTS

In tapping tasks with experimental occlusal interference of 0.75 mm or 0.5 mm, there was clear activation of the contralateral teeth-related primary sensory cortex and Brodmann's area 46. At 0 and 30 minutes after removal of the experimental occlusal interference, the activation clearly appeared in the bilateral teeth-related primary sensory cortices and Brodmann's area 46. At 60 minutes after the removal of the experimental occlusal interference, the activation of Brodmann's area 46 had disappeared, and only the bilateral teeth-related primary sensory cortices were active.

CONCLUSIONS

The present results suggest that adjustments for experimental occlusal interference can be objectively evaluated using fMRI. We expect that this method of evaluating adjustments in occlusal interference, combined with fMRI and the tapping task, could be applied clinically in the future.