Oral function of implant-assisted removable partial dentures with magnetic attachments using short implants: A prospective study.

OBJECTIVES: This prospective study aimed to compare the oral functions of removable partial dentures (RPDs) with those of implant-assisted removable partial dentures (IARPDs) with short implants and magnetic attachments in patients with mandibular Kennedy class I and II. MATERIAL AND METHODS: Thirty participants with mandibular Kennedy class I or II and at least three distal missing teeth were recruited. Oral functions, including mixing ability, comminuting ability, maximum bite force, and occlusal contact area, were assessed for RPDs (stage 0), IARPDs with healing caps (stage 1), and IARPDs with magnetic attachments (stage 2). The implants were loaded with occlusal force in stages 1 and 2. Finally, the data of the 27 participants who completed the evaluation at stage 2 were analyzed. The Wilcoxon signed-rank test with Bonferroni correction was used to assess the differences in the oral functions among the different stages. RESULTS: The implant survival rate was 93.8%. There were significant differences in the comminuting ability and occlusal contact area between stages 0 and 2 (p < .001 and p = .036, respectively) and stages 1 and 2 (p = .003 and p = .015, respectively). Regarding the maximum bite force, there was a significant difference between stages 1 and 2 (p = .018). However, there was no significant difference in the mixing ability between the three stages. CONCLUSIONS: Within the limitations of this study, it was concluded that IARPDs in the mandible with short implants and magnetic attachments may improve oral functions.

Effects of vibratory feedback stimuli through an oral appliance on sleep bruxism: a 6-week intervention trial.

PURPOSE: Various biofeedback stimulation techniques of managing sleep bruxism (SB) have recently emerged; however, the effect of successive application of vibratory feedback stimulation has not been clarified. This study elucidated the effect of vibration feedback stimulation via an oral appliance (OA) on SB when vibration feedback was applied for 4 weeks. METHODS: This was a prospective, single-arm, open-label, intervention study. Ten participants diagnosed with "definite" SB wore a specially designed OA for 45 nights in a home-setting. A force-based SB detection system, including a pressure-sensitive piezoelectric film placed internally in the OA, triggered a vibrator attached to the OA. Vibratory stimulation was withheld during the first 2-week adaptation period (1st-15th nights), applied during the 4-week stimulation period (16th-43rd nights), and again withheld during the post-stimulation period (44th and 45th nights). The number and duration of SB episodes/hour of sleep were calculated based on masseter electromyographic activity recorded with in-home portable polysomnography and compared between the 15th and 45th nights (without stimulation) and the 17th and 43rd nights (with stimulation). RESULTS: The number and duration of SB episodes significantly decreased after vibratory stimulation (15th vs. 17th nights: p = 0.012 and p = 0.012, respectively), then significantly increased upon cessation of vibratory stimulation after the stimulation period (43rd vs. 45th nights: p = 0.023 and p = 0.023, respectively). CONCLUSION: Contingent vibratory stimulation through an OA may suppress SB-related masticatory muscle activity continuously for 4 weeks and may be an effective alternative for the management of SB. TRIAL REGISTRATION: https://jrct.niph.go.jp/ ; trial registration number: jRCTs032190225.

Effect of contingent vibratory stimulus via an oral appliance on sleep bruxism after the splint adaptation period.

BACKGROUND: Contingent vibratory feedback stimuli applied by a specially designed oral appliance (OA) have been reported to be effective in reducing sleep bruxism (SB). However, the inhibitory effects of the OA, which occur immediately after OA delivery, may have confounded this finding. OBJECTIVE: This study sought to shed light on the effects of vibratory stimuli on SB after the OA adaptation period, when its inhibitory effects are diminished. METHODS: Fourteen 'definite' SB patients were enrolled. A force-based bruxism detection system was utilised to trigger a vibrator attached to the OA. Masseter electromyographic activity during sleep was recorded at home using portable polysomnography. After using the OA without vibratory stimulus for 16 nights (adaptation period), intermittent vibratory stimuli were applied every other half-hour for four nights (intervention period). Electromyographic activity over 10% of the maximum voluntary contraction was regarded as a SB episode. The number and the total duration of SB episodes per hour of sleep were calculated for the sessions with and without stimuli separately and averaged for four intervention nights. The effects of stimuli on these two variables were evaluated. RESULTS: The number and the total duration of the sessions without stimuli were 5.2 episodes/h and 35.3 s/h, respectively. These values significantly decreased to 3.9 episodes/h and 15.1 s/h (p < .05) for the sessions with vibratory stimuli. CONCLUSION: Contingent vibratory stimulus via an OA may be effective for the management of SB even after adaptation to OA.

Effects of a contingent vibratory stimulus delivered by an intra-oral device on sleep bruxism: a pilot study.

PURPOSE: Although sleep bruxism (SB) is one of the most important clinical problems in dental practice, there is no definitive method for controlling it. This pilot study evaluated the effects of contingent vibratory feedback stimuli using an occlusal splint for inhibition of sleep bruxism. METHODS: Thirteen subjects with clinically diagnosed SB participated after providing an informed consent. Portable polysomnographic recordings were conducted in the subjects' home environment to make a definitive SB diagnosis and to evaluate the effects of the vibratory stimuli on SB. A force-based bruxism detection system, which used a pressure-sensitive piezoelectric film embedded in the occlusal splint, was utilized to trigger vibration feedback stimuli, which was scheduled to be applied intermittently for 30 min, at 30-min intervals. RESULTS: The number of SB episodes (times/hour), the total SB duration (seconds/hour), the mean duration of SB episodes (seconds/episode), and the micro-arousal index (times/hour) were scored for each time period (with and without vibration). The effects of the vibration on these scores were tested (paired t test; p < 0.05). The number of SB episodes tended to decrease with the vibration stimuli, and the decrease in the total SB duration was statistically significant (14.3 ± 9.5 vs. 26.0 ± 20.0, p = 0.03). No substantial change was found in terms of the micro-arousal index. CONCLUSIONS: These study results suggested that the SB inhibitory system employing a vibratory stimulus might be able to suppress the total SB duration without disturbing sleep.

Association between patterns of jaw motor activity during sleep and clinical signs and symptoms of sleep bruxism.

The aim of this study was to investigate the association between patterns of jaw motor activity during sleep and clinical signs and symptoms of sleep bruxism. A total of 35 university students and staff members participated in this study after providing informed consent. All participants were divided into either a sleep bruxism group (n = 21) or a control group (n = 14), based on the following clinical diagnostic criteria: (1) reports of tooth-grinding sounds for at least two nights a week during the preceding 6 months by their sleep partner; (2) presence of tooth attrition with exposed dentin; (3) reports of morning masticatory muscle fatigue or tenderness; and (4) presence of masseter muscle hypertrophy. Video-polysomnography was performed in the sleep laboratory for two nights. Sleep bruxism episodes were measured using masseter electromyography, visually inspected and then categorized into phasic or tonic episodes. Phasic episodes were categorized further into episodes with or without grinding sounds as evaluated by audio signals. Sleep bruxism subjects with reported grinding sounds had a significantly higher total number of phasic episodes with grinding sounds than subjects without reported grinding sounds or controls (Kruskal-Wallis/Steel-Dwass tests; P < 0.05). Similarly, sleep bruxism subjects with tooth attrition exhibited significantly longer phasic burst durations than those without or controls (Kruskal-Wallis/Steel-Dwass tests; P < 0.05). Furthermore, sleep bruxism subjects with morning masticatory muscle fatigue or tenderness exhibited significantly longer tonic burst durations than those without or controls (Kruskal-Wallis/Steel-Dwass tests; P < 0.05). These results suggest that each clinical sign and symptom of sleep bruxism represents different aspects of jaw motor activity during sleep.

Effect of treatment with implant-supported fixed partial dentures on oral health-related quality of life in patients with unilateral shortened dental arch.

Background/purpose: Implant-supported fixed partial dentures (IFPDs) are a treatment option for partially edentulous dentition with missing posterior-most molars despite the concept of a shortened dental arch (SDA). This study aimed to evaluate the effect of IFPD treatment on oral health-related quality of life (OHRQoL) in patients with unilateral SDA missing two adjacent molars and to compare the effects of single- and two-unit IFPDs. Materials and methods: Forty patients with unilateral SDA missing two adjacent molars (Kennedy Class II) participated in this study; 11 patients received one implant placement in the first molar and were treated with a single-unit IFPD (single-unit group), and 29 received two implant placements and were treated with a two-unit IFPD (two-unit group). The Oral Health Impact Profile (OHIP) questionnaire for OHRQoL assessment and the gummy jelly test for objective masticatory performance were administered before and after IFPD treatment. The Wilcoxon signed-rank test for all patients and Mann-Whitney U test were performed for pre- and post-treatment comparisons and between-group comparisons, respectively. Results: The OHIP summary score and gummy jelly glucose concentration in all patients showed significant improvements after treatment (all P < 0.05). No significant differences were observed between the single- and two-unit groups for any of the items. Using the minimal important difference in the OHIP summary score, 63.6 % and 58.6 % of patients in the single- and two-unit groups, respectively, showed improvement by 6 points or more. Conclusion: IFPD treatment for patients with SDA missing two adjacent molars may provide clinically meaningful improvements in OHRQoL.

Association between the treatment choice of implant-supported fixed partial dentures and oral health-related quality of life in patients with a shortened dental arch: A preliminary observational study.

Background/purpose: In cases of missing posterior teeth, treatment modalities based on the shortened dental arch (SDA) concept may be a viable alternative. However, the association between oral health-related quality of life (OHRQoL) and patients' treatment decisions remains unclear. This study aimed to investigate the association between OHRQoL and the decision to be treated with implant-supported fixed partial dentures (IFPDs) or take a wait-and-see approach in patients with an SDA missing a single second molar and to clarify the impact of IFPD treatment on the OHRQoL. Materials and methods: The Oral Health Impact Profile (OHIP) questionnaire was administered twice (pre- and post-treatment) and once to 41 patients with a unilateral SDA missing a single second molar who chose IFPD treatment (IFPD group, n = 22) and the wait-and-see approach (no treatment group, n = 19), respectively. Logistic regression analysis was performed with IFPD treatment choice as the objective variable and the four OHIP dimension scores, age, and sex as covariates. The pre- and post-treatment values of the OHIP summary and four-dimension scores were compared using a paired t-test. Results: The IFPD treatment choice was significantly associated with sex (male), higher Oral Function dimension scores, and lower Psychosocial Impact dimension scores (all P < 0.05). The OHIP summary and four-dimension scores were significantly lower following IFPD treatment (all P < 0.05). Conclusion: IFPD treatment for a single missing second molar may be clinically beneficial for improving the OHRQoL of patients with an SDA who experience a decline in masticatory function.

Diagnostic accuracy of ambulatory polysomnography with electroencephalogram for detection of sleep bruxism-related masticatory muscle activity.

STUDY OBJECTIVES: This study investigated the diagnostic accuracy of Sleep Profiler, which relies on ambulatory polysomnography (PSG) with electroencephalogram for sleep bruxism (SB) and examined its episode-by-episode agreement in comparison to PSG equipped with audiovisual recordings (avPSG). METHODS: This prospective 2-gate study recruited 10 individuals with probable SB and 10 healthy volunteers. Overnight experimental recordings were performed simultaneously using the ambulatory PSG with masseter electromyography and avPSG with masseter and temporalis electromyography. Sleep staging was performed manually for avPSG and automatically or manually for ambulatory PSG. SB episodes were manually scored based on electromyography signals with reference to sleep stages. The episode-by-episode agreement was analyzed by setting avPSG as the reference standard. The sensitivity, specificity, and accuracy for the diagnosis of SB were calculated after optimizing the cutoff values of the episode index and the burst index. RESULTS: Regarding the episode-by-episode agreement, median sensitivities were 0.825 and positive predictive values were approximately 0.6, regardless of the sleep staging procedure, indicating that approximately 40% of the overall total SB episodes scored by the ambulatory PSG were false positives. Because of overestimation of SB episodes, the optimal cutoff values for the episode index and the burst index were approximately 1.5 times higher than the avPSG-based cutoff values and dramatically improved the diagnostic precision metrics for the ambulatory PSG. CONCLUSIONS: Sleep Profiler can eliminate events during wakefulness by electroencephalogram and may provide a definitive diagnosis in patients with possible SB by applying optimized cutoff values. However, the risk of overestimation must be recognized. CLINICAL TRIAL REGISTRATION: Registry: UMIN Clinical Trials Registry; Name: Accuracy of Portable PSG Device for Detection of Sleep Bruxism-Related Masseter EMG Muscle Activity; URL: https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000037380; Identifier: UMIN000032793. CITATION: Abe Y, Nakazato Y, Takaba M, Kawana F, Baba K, Kato T. Diagnostic accuracy of ambulatory polysomnography with electroencephalogram for detection of sleep bruxism-related masticatory muscle activity. J Clin Sleep Med. 2023;19(2):379-392.

Association of genetic, psychological and behavioral factors with sleep bruxism in a Japanese population.

Sleep bruxism is a sleep-related movement disorder that can be responsible for various pains and dysfunctions in the orofacial region. The aim of the current case-control association study was to investigate the association of genetic, psychological and behavioral factors with sleep bruxism in a Japanese population. Non-related participants were recruited and divided into either a sleep bruxism group (n = 66) or control group (n = 48) by clinical diagnoses and 3-night masseter electromyographic recordings by means of a portable miniature device. The Epworth Sleepiness Scale, Temperament and Character Inventory, NEO-Five Factor Inventory and custom-made questionnaires that asked about familial aggregation, alcohol intake, caffeine intake, cigarette smoking, past stressful life events, daytime tooth-contacting habit, temporomandibular disorder, daily headache, snoring, apnea/hypopnea symptoms, leg-restlessness symptoms and nocturnal-myoclonus symptoms were administered. In addition, 13 polymorphisms in four genes related to serotonergic neurotransmission (SLC6A4, HTR1A, HTR2A and HTR2C) were genotyped. These factors were compared between case (sleep bruxism) and control groups in order to select potential predictors of sleep-bruxism status. The statistical procedure selected five predictors: Epworth Sleepiness Scale, leg-restlessness symptoms, rs6313 genotypes, rs2770304 genotypes and rs4941573 genotypes. A multivariate stepwise logistic regression analysis between the selected predictors and sleep-bruxism status was then conducted. This analysis revealed that only the C allele carrier of HTR2A single nucleotide polymorphism rs6313 (102C>T) was associated significantly with an increased risk of sleep bruxism (odds ratio = 4.250, 95% confidence interval: 1.599-11.297, P = 0.004).This finding suggests a possible genetic contribution to the etiology of sleep bruxism.

A pilot study to test the validity of a piezoelectric intra-splint force detector for monitoring of sleep bruxism in comparison to portable polysomnography.

PURPOSE: To test the validity of a force-based detection system (ISFD: intra-splint force detector) to record sleep bruxism (SB) in comparison to portable polysomnography (PSG). METHODS: Simultaneous portable PSG recordings with a masseter electromyography (EMG) channel and ISFD with a deformation-sensitive piezoelectric film were performed on six participants with definite SB. First, simulated bruxism behaviors (static clenching, grinding, tapping, and rhythmic clenching) were recorded using both EMG and ISFD. Using these data, interval and duration criteria for ISFD data conditioning were established. Then, portable PSG recordings were conducted with the ISFD during sleep. Using the above criteria, ISFD events were compared with EMG-based SB episodes (the gold standard), and the sensitivity and positive predictive value of ISFD events were calculated. Spearman's correlation coefficients between true-positive ISFD events and SB episodes were then calculated. RESULTS: Among the tested conditioning criteria, a 3-s interval combined with a 1-s duration was selected. The median sensitivity and positive predictive value for the ISFD were 0.861 and 0.585, respectively. The duration of true-positive ISFD events was correlated with that of EMG-based SB episodes (rho = 0.658, P < 0.01). CONCLUSION: ISFD has validity for SB detection and could be an alternative to single-channel EMG-based recordings.

Increased excitability of human iPSC-derived neurons in HTR2A variant-related sleep bruxism.

Sleep bruxism (SB) is a sleep-related movement disorder characterized by grinding and clenching of the teeth during sleep. We previously found a significant association between SB and a single nucleotide polymorphism (SNP), rs6313, in the neuronal serotonin 2A receptor gene (HTR2A), and established human induced pluripotent stem cell (iPSC)-derived neurons from SB patients with a genetic variant. To elucidate the electrophysiological characteristics of SB iPSC-derived neural cells bearing an SB-related genetic variant, we generated ventral hindbrain neurons from SB patients and unaffected controls, and explored the intrinsic membrane properties of these neurons using the patch-clamp technique. We found that the electrophysiological properties of iPSC-derived neurons mature in a time-dependent manner in long-term control cultures. SB neurons exhibited higher action potential firing frequency, higher gain, and shorter action potential half duration. This is the first in vitro modeling of SB using patient-specific iPSCs. The revealed electrophysiological characteristics may serve as a benchmark for further investigation of pathogenic mechanisms underlying SB. Moreover, our results on long-term cultures provide a strategy to define the functional maturity of human neurons in vitro, which can be implemented for stem cell research of neurogenesis, and neurodevelopmental disorders.

Differences between sliding mechanics with implant anchorage and straight-pull headgear and intermaxillary elastics in adults with bimaxillary protrusion.

The aim of this retrospective study was to determine differences between the outcomes of treatment using implant anchorage compared with straight-pull headgear and intermaxillary elastics in bimaxillary protrusion patients. The lateral cephalograms of 28 adult orthodontic patients (3 males and 25 females; age, 24.9 ± 5.0 years) who had an Angle Class I malocclusion with bimaxillary protrusion were selected. Group 1 (14 patients; 1 male and 13 females; age, 25.0 ± 5.1 years) received sliding mechanics with implant anchorage and group 2 (14 patients; 2 males and 12 females; age, 24.8 ± 5.1 years) a straight-pull headgear and intermaxillary elastics. Lateral cephalometric radiographs obtained before and after treatment were traced, 13 landmarks identified, and differences in the skeletal and dental changes compared between the groups. Wilcoxon's signed-rank test was used to determine changes within the treatment groups and a Mann-Whitney U-test to evaluate significant differences. More anchorage loss occurred at the maxillary posterior teeth in group 2 (2.1 mm) than in group 1 (0.1 mm). Closing rotation of the mandible occurred in group 1, while opening rotation of the mandible was observed in group 2. These results suggest that sliding mechanics with implant anchorage may provide absolute anchorage and could control mandibular rotation more than the conventional technique.

Structural equation modeling for factors influencing patients' willingness to replace removable dentures.

PURPOSE: To investigate the factors influencing patients' willingness to replace removable dentures using structural equation modeling (SEM). METHODS: A total of 153 patients who sought consultations for removable dentures self-evaluated denture quality using a visual analog scale (VAS); health-related quality of life using the 36-item Short-Form Health Survey; and oral health-related quality of life using the Oral Health Impact Profile. Dental clinicians evaluated denture quality using a VAS and by assessing the presence of defects. After being informed of various treatments, patients were asked whether they would prefer denture replacement. SEM was applied to analyze the relationships and interactive effects among the variables. RESULTS: The final model showed high goodness-of-fit indices (chi-square/degree of freedom = 1.009, comparative fit index = 1.000, Tucker-Lewis index = 0.999, standardized root mean square residual = 0.421, and root mean square error of approximation = 0.008). SEM demonstrated that two latent constructs indirectly predicted patients' willingness to replace dentures; the standardized total effects of good oral health and poor denture quality were -0.154 and 0.503, respectively. CONCLUSION: These findings provide a unified understanding of the shared decision-making process for denture replacement and highlight the pretreatment assessments that play a relevant role in patient treatment preferences.

Patient-reported outcomes of implant-assisted removable partial dentures with magnetic attachments using short implants: A prospective study.

Purpose Implant-assisted removable partial dentures (IARPDs) with short implants improve the oral functions of removable partial dentures (RPDs). This study aimed to compare the patient-reported outcomes of RPDs and IARPDs with short implants retained by magnetic attachments.Methods We recruited 30 participants with mandibular Kennedy Class I or II and distal extension defects of three or more teeth. RPDs, IARPDs with a healing cap, and IARPDs with a magnetic attachment were evaluated across stages using patient-reported outcomes. All participants completed questionnaires (oral health-related quality of life [OHRQoL], patient general satisfaction, and patient's denture assessment [PDA]) at each stage. The OHRQoL was evaluated using the Oral Health Impact Profile-J 54 (OHIP-J 54) score. The general patient satisfaction was evaluated using a 100 mm visual analog scale. The Wilcoxon signed-rank test and Bonferroni correction were used to evaluate differences between the groups (α=0.05).Results The OHRQoL of IARPDs was significantly higher than that of RPDs. IARPDs with a magnetic attachment had significantly better patient general satisfaction and PDA than IARPDs with a healing cap.Conclusions The OHRQoL, patient general satisfaction, and PDA were improved by IARPD with a short implant using a magnetic attachment.

Generation of neural cells using iPSCs from sleep bruxism patients with 5-HT2A polymorphism.

PURPOSE: Sleep bruxism (SB) is classified as a sleep-related movement disorder characterized by grinding and clenching of the teeth during sleep, which is responsible for a variety of clinical problems such as abnormal tooth attrition and fracture of teeth or roots. Little is known about the etiology of SB. Our previous study identified a genomic association of the serotonin 2A receptor (5-HT2A) single nucleotide polymorphism (SNP), rs6313 C>T, with SB, where the C allele carrier is associated with a 4.25-fold increased risk of SB. Based on this finding, the aim of this study was to generate of neural cells using SB patient-specific induced pluripotent stem cells (iPSCs). METHODS: Two SB patients with C/C genotype of rs6313 and two controls with T/T genotype were screened by laboratory-based polysomnographic recordings and the TaqMan genotyping assay. Four lines of iPSCs, two from SB patients and two from controls, were established from peripheral blood mononuclear cells by introduction of reprogramming factors. We performed quality control assays on iPSCs using expression of markers for undifferentiated pluripotent cells, immunostaining for pluripotency markers, a three-germ layer assay, and karyotype analysis. The established iPSCs were differentiated into neurons using the neurosphere culture system. 5-HT2A gene expression in these neurons was evaluated by quantitative real-time PCR. RESULTS: Patient-specific iPSCs were successfully differentiated into neurons expressing 5-HT2A. CONCLUSIONS: This report is the first successful generation of neural cells using iPSCs from sleep bruxism patients with 5-HT2A polymorphism, which has the potential to elucidate the etiology and underlying mechanism of SB.

Effects of citalopram on jaw-closing muscle activity during sleep and wakefulness in mice.

In this study, we investigated the effects of chronic administration of the selective serotonin reuptake inhibitor (SSRI) citalopram on sleep/wake cycles and masseter (jaw-closing) muscle electromyogram (EMG) activity over a 24-h period. From the dark to the light period, the times of wakefulness decreased, while those of non-rapid eye movement (NREM) and REM sleep increased. Citalopram did not induce major alterations in the temporal changes of sleep-wake distributions, except for leading to a decrease in the time of NREM sleep during the light period and an increase in the durations of REM sleep episodes. Moreover, citalopram did not modify mean masseter EMG activity during any of the vigilance states and did not affect the temporal changes related to the shifts between dark/light periods. However, citalopram increased the time engaged in masseter EMG activation during NREM sleep in the second and the first halves of the dark and light periods, respectively. These results suggest that chronic citalopram treatment does not affect the temporal changes of sleep-wake distributions, but has a limited facilitatory influence that fails to increase the number of epochs of high levels of masseter muscle activation.