Actual state of the diurnal masseteric electromyogram: Differences between awareness and non-awareness of awake bruxism.

PURPOSE: This study aimed to elucidate the relationship between diurnal masseter muscle activity and awareness of diurnal awake bruxism (d-AB) by conducting a comparative analysis of electromyographic (EMG) data from individuals with and without awareness of diurnal awake bruxism (d-AB), utilizing EMG data gathered from multiple subjects. METHODS: Unilateral masseter electromyography (EMG) recordings were performed during the daytime using an ultraminiature wearable EMG device. A total of 119 participants (59 with awareness of diurnal tooth clenching [d-TC] and 60 without awareness of d-TC) were included. Waveforms longer than 0.25 s with the two amplitude conditions, exceeding twice the baseline and >5% of maximum voluntary clenching, were extracted. In addition, the number of bursts and episodes (groups of bursts), burst duration, and burst peak amplitude were calculated for each participant. RESULTS: There were no significant differences in the EMG parameters between the groups with and without awareness of d-TC. Additionally, the frequency distribution of the number of EMG waveforms exhibited wide ranges and substantial overlap between the two groups. CONCLUSIONS: The variability in the number of bursts and episodes, burst peak amplitude, and burst duration among subjects suggests the need for an objective classification of d-AB severity based on EMG values. The absence of significant differences and large overlap in frequency distributions between the groups with and without awareness of d-TC indicate difficulty in predicting muscle activity solely based on awareness of d-AB.

Radiopaque properties of polyetheretherketone crown at laboratory study.

OBJECTIVES: There have been no reports on the radiopaque properties of new polyetheretherketone (PEEK) crowns for locating crowns during accidental ingestion or aspiration and detection of secondary caries, which is essential information for clinical application. This study aimed to investigate whether the radiopaque properties of PEEK crowns could be used to identify the site of accidental ingestion or aspiration and detect secondary caries. METHODS: Four types of crowns were fabricated: three non-metal crowns (PEEK, hybrid resin, and zirconia) and one full metal cast crown (gold-silver-palladium alloy). Initially, the images for these crowns were compared using intraoral radiography, chest radiography, cone-beam computed tomography (CBCT), and multi-detector computed tomography (MDCT); computed tomography (CT) values were calculated. Subsequently, the images for the crowns placed on the secondary caries model with two artificial cavities were compared using intraoral radiography. RESULTS: The PEEK crowns displayed the lowest radiopaque properties on radiography and very few artifacts were observed on CBCT and MDCT. On the other hand, the CT values of the PEEK crowns were a little lower than those of the hybrid resin crowns and considerably lower than the zirconia and full metal cast crowns. The cavity could be detected in the PEEK crown-placed secondary caries model through intraoral radiography. CONCLUSIONS: This simulated study of radiopaque properties with four types of crowns suggested that a radiographic imaging system can be used to identify the site of accidental ingestion and aspiration of PEEK crowns and to detect secondary caries of the abutment tooth within a PEEK crown.

Clinical report of six-month follow-up after cementing PEEK crown on molars.

We conducted a six-month clinical follow-up on computer-aided design/computer-aided manufacturing-fabricated molar polyetheretherketone PEEK crowns to investigate their therapeutic effect. Only the PEEK crowns were examined as our study focused on short-term clinical evaluation of the new PEEK material. Twenty-three cases of PEEK crowns placed on the molars of 20 subjects (7 males and 13 females, mean age: 60.6 ± 14.2 years) were included in the study. The evaluation items were the condition of the crowns at the time of cementation and after six months, patient satisfaction, masticatory ability, and occlusal force. Mann-Whitney U tests with a significance level of 5% were used to examine the difference in glucose concentration by masticatory ability, occlusal pressure, and occlusal force, with and without PEEK crowns. The occlusion, margin fit, and contact of all 23 cases at the time of cementing were good. Six months after cementation, there was no crown desorption, fracture or crack, and prosthodontics was not needed in the 22 cases (one patient dropped out). No wear of the dental antagonist was observed. Patient satisfaction was generally high. There was no significant difference in masticatory ability between the groups with and without PEEK crowns. The subject's occlusal force was within the normal range. PEEK crowns used on molars can replace metal crowns and hold promise for an appropriate and effective treatment.

Nd:YVO4 laser groove treatment can improve the shear bond strength between dental PEEK and adhesive resin cement with an adhesive system.

The purpose of this study was to investigate the effect of various surface treatments on the shear bond strength between dental polyetheretherketone (PEEK) and adhesive resin cement. Two hundred and forty specimens were randomly classified into four groups: no treatment, sandblasted, sulfuric-acid-etched, and laser-grooved treatment. Each group was classified into two adhesive resin cement subgroups. Surface roughness, water contact angle, shear bond strength, and failure mode were measured; SEM and XPS results were obtained. The data were statistically analyzed using one-way or two-way analysis of variance and Tukey's honest significant difference test (α=0.05). Laser-grooved PEEK surface showed regular grooves and carbonization by thermal degradation; the surface roughness as well as water contact angle of were the highest in all groups. Shear bond strength values were significantly higher in the laser-groove-treated and sulfuric-acid-etched groups. Laser-groove-treated specimens showed cohesive failure. Laser-grooved treatment can improve shear bond strength between PEEK and adhesive resin cement.

Effect of laser groove treatment on shear bond strength of resin-based luting agent to polyetheretherketone (PEEK).

PURPOSE: The mechanical properties of polyetheretherketone (PEEK) are ideally suited for fixed dental prostheses. However, PEEK typically has low adhesion strength to resin-based luting agent. This study assessed the shear bond strength between laser groove treated PEEK and resin-based luting agent. METHODS: A total of 230 specimens were randomly divided into five groups (n=46): no-treatment, air abrasion treatment, 100µm-deep, 150µm-deep, and 200µm-deep laser groove treatments. The surface roughness was measured, scanning electron microscopy was used to observe the specimen surfaces, and X-ray photoelectron spectroscopy (XPS) was used to analyze the surfaces. Each group was divided into four resin-based luting agent subgroups: Panavia V5, RelyX Ultimate Resin Cement, G-CEM Link Force, and Super-Bond C&B. After the resin-based luting agent was bonded to the specimens, the bond strength was measured using shear tests and the failure modes were assessed by stereomicroscopy. The surfaces were also observed by scanning electron microscopy (SEM) after the shear bond strength measurements. The data were statistically analyzed using a two-way analysis of variance and Tukey's honest significant difference test (α=0.05). RESULTS: The PEEK surface after laser groove treatment groups exhibited the highest mean Ra values. In the XPS analysis, the laser treated PEEK surface exhibited an effective surface composition for bonding with resin-based luting agent. The shear bond strengths for the laser groove treated samples were significantly higher (p<0.05) than those of the no-treatment and air abrasion treatment groups. CONCLUSIONS: The shear bond strength between PEEK and resin-based luting agent was substantially improved by laser groove treatment.

Application of interconnected porous hydroxyapatite ceramic block for onlay block bone grafting in implant treatment: A case report.

Autogenous block bone grafting as treatment for alveolar ridge atrophy has various disadvantages, including a limited availability of sufficiently sized and shaped grafts, donor site morbidity and resorption of the grafted bone. As a result, interconnected porous hydroxyapatite ceramic (IP-CHA) materials with high porosity have been developed and used successfully in orthopedic cases. To the best of the author's knowledge, this is the first report of clinical application of an IP-CHA block for onlay grafting for implant treatment in a patient with horizontal alveolar atrophy. The present study performed onlay block grafting using an IP-CHA block to restore bone volume for implant placement in the alveolar ridge area without collecting autogenous bone. Dental X-ray findings revealed that the border of the IP-CHA block became increasingly vague over the 3-year period, whereas CT scanning revealed that the gap between the block and bone had a smooth transition, indicating that IP-CHA improved the process of integration with host bone. In follow-up examinations over a period of 5 years, the implants and superstructures had no problems. An IP-CHA block may be useful as a substitute for onlay block bone grafting in implant treatment.

Accelerating effects of cellulase in the removal of denture adhesives from acrylic denture bases.

PURPOSE: Studies of effective methods for the easy removal of denture adhesives from a denture base are not well represented in the literature. We previously assessed the removability of denture adhesives by immersing within denture cleaners, showing that some cleaners have a weak effect, insufficiently effective in daily use. In this study, we prepared a cellulase, as a potential component for denture adhesive removers, and we examined whether the addition of cellulase to denture cleaners is effective in the removal of cream denture adhesives. METHODS: We prepared the cellulase Meicelase as one component for the liquefaction of denture adhesives. We used two denture cleaners and two cream adhesives. After the immersion of plates in sample solutions, we evaluated the area of the sample plate still covered with adhesives. Biofilm removal assay was also performed using denture cleaners containing cellulase. RESULTS: The addition of cellulase accelerated the removal of cream adhesives in immersion experiments to a rate faster than that of water and denture cleaners. However, it did not influence the removability of Candida albicans biofilms from acrylic resin specimens. CONCLUSION: Cellulase hastened the liquefaction of cream adhesives.

A novel mouthpiece prevents bite injuries caused by intraoperative transcranial electric motor-evoked potential monitoring.

PURPOSE: Intraoperative transcranial motor-evoked potential monitoring causes contraction of the masseter muscles, which may cause injuries to the oral cavity and damage to the orotracheal tube. We developed a mouthpiece made from vinyl-silicone impression material to prevent these injuries. The purpose of this study was to examine its efficacy and safety. METHODS: Twenty-two patients undergoing spinal surgery under transcranial motor-evoked potential monitoring were fitted with bespoke vinyl-silicone mouthpieces by dentists before surgery. On induction of general anesthesia and orotracheal intubation, the mouthpiece was attached to the upper and lower dental arches. A lateral cervical X-ray was taken at the end of surgery to examine the condition of the orotracheal tube. The incidence of endotracheal tube deformation was compared with an historic control group of 20 patients in whom a conventional gauze bite block had been previously used before induction of the mouthpiece. The oral cavity was examined by a dentist the day before surgery and 3 days postoperatively, and intraoral injuries were recorded. RESULTS: No endotracheal tube deformation was found in 22 patients fitted with the new mouthpiece. The incidence of tube deformation (none of 22 patients, 0 %) was significantly lower than in those who had been fitted with the gauze bite block (9 of 20 patients, 45.0 %; p < 0.001). Application of the mouthpiece resulted in no tongue or tooth injuries. CONCLUSION: A novel mouthpiece reduced the incidence of damage to the endotracheal tube caused by intraoperative transcranial motor-evoked potential monitoring.

Evaluation of the efficiency of denture cleaners for removing denture adhesives.

OBJECTIVE: We developed a new scoring index for assessing the removability of denture adhesives and evaluated the removal efficiency of denture cleaners. BACKGROUND: Although our understanding of the importance of denture care is increasing, little is known about the effectiveness and efficiency of denture cleaners on denture adhesives. Therefore, guidelines for proper cleaning are necessary. MATERIALS AND METHODS: We used five denture cleaner solutions on two cream adhesives, one powder adhesive and one cushion adhesive. After immersion in the denture cleaners for a designated time, we evaluated the area of the sample plate still covered by denture adhesive. RESULTS: Cream adhesives were removed more completely after immersion in majority of the denture cleaners than in water. Powder adhesive was removed more quickly than cream adhesives. Cushion adhesive was not removed by immersion in either the denture cleaners or water control. CONCLUSION: Some denture cleaners could liquefy cream adhesives more than water, but these differences were not observed in case of powder and cushion adhesives.

Relationship between behavioral and psychological symptoms of dementia and oral health status in the elderly with vascular dementia.

OBJECTIVES: The aim of this study was to clarify the relationship between behavioral and psychological symptoms of dementia (BPSD) and oral status in the elderly with vascular dementia. BACKGROUND: There have been some reports of a relationship between disease symptoms and oral status in the elderly with Alzheimer's disease, but few reports have been conducted in the elderly with vascular dementia. Until now, the relationship between BPSD and oral status has been unknown. MATERIALS AND METHODS: An investigation was conducted concerning BPSD and oral status among 57 subjects with vascular dementia (mean age, 85.7 ± 5.5 years). The wearing of dentures and oral activities of daily living (oral ADL) were examined. RESULTS: Subjects with activity disturbances and those with aggressiveness had significantly lower rates of denture wearing than those without these two symptoms (p < 0.05). Significantly lower oral ADL scores were obtained from subjects with delusional ideas, hallucinations, activity disturbances and diurnal rhythm disturbances (p < 0.05), as well as those with affective disturbances (p< 0.01). CONCLUSION: This study indicated a relationship between BPSD and the wearing of dentures in the elderly with vascular dementia. The study also demonstrated relationships between BPSD and oral ADL.

Nutritional status and oral status of the elderly with dementia: a 2-year study.

OBJECTIVES: To determine the relationship between denture wearing and nutritional status in the elderly with dementia. BACKGROUND: There could be a correlation between nutrition, oral health, dietary habits, patients' satisfaction, and their socio-economic status in the elderly, and the relationship between compromised oral status and nutritional status in the elderly with dementia. SUBJECTS AND METHODS: A 2-year follow-up study of 63 elderly Japanese women with and without dentures from a nursing home was undertaken to investigate their oral, physical and mental, and nutritional status. RESULTS: Each item for 2006 and 2008 in this study showed no significant difference between 2006 and 2008, except the calories/day. The elderly with dementia without complete dentures during the 2 years of the study only significantly decreased the mean of the calories/day. CONCLUSION: The calories/day of the elderly with dementia without dentures decreased after 2 years. Denture wearing for the elderly with dementia could be necessary to maintain a satisfactory intake of calories.

Association between sleep bruxism and stress sensitivity in an experimental psychological stress task.

The objective of this study was to examine the association between sleep bruxism and psychological stress. The subjects consisted of 76 volunteers, who were divided into those with and without bruxism according to the diagnostic criteria for sleep bruxism outlined by the American Academy of Sleep Medicine (AASM). Stress sensitivity was evaluated before and after an experimental stress task, which involved simple mathematical calculations. It was assessed objectively by measuring the subjects' salivary chromogranin A (CgA) levels and subjectively using a ten-division visual analog scale (VAS). Compared with those observed before the stress task, the mean salivary CgA levels of the non-bruxism group (n = 54) were not significantly increased after the stress task. Conversely, the mean salivary CgA levels of the bruxism group (n = 22) were significantly increased after the stress task (P < 0.01). The mean VAS scores of the groups without (n = 54) and with (n = 22) bruxism were significantly (P < 0.01) increased after the stress task compared with those observed before the stress task, but no differences were detected between the two groups in the stress task. These findings suggest that there is an association between sleep bruxism and psychological stress sensitivity.

The initial effects of occlusal splint vertical thickness on the nocturnal EMG activities of masticatory muscles in subjects with a bruxism habit.

PURPOSE: The objective of this study was to investigate the initial effects of the vertical thickness of occlusal splints on the electromyographic (EMG) activities (integrated EMG values) of temporal and masseter muscles during sleep in subjects with a nocturnal bruxism habit using a portable EMG recorder. MATERIALS AND METHODS: The subjects consisted of 12 volunteers (4 men and 8 women, average age of 25.3 years). All subjects had never worn splints before and had a habit of nocturnal bruxism. Two types of splint were made for every subject: a splint with a 3-mm vertical thickness at the central incisors (S3) and a splint with a 6-mm vertical thickness (S6). The muscle activities of the left anterior temporal muscles and masseter muscles were recorded without occlusal splints (NS), with the S3 splint, and with the S6 splint by a portable EMG recorder. The integrated EMG values were calculated to examine muscle activities under the 3 different conditions. RESULTS: The integrated EMG values of masseter and temporal muscles decreased following insertion of the S3 splint but were not significantly affected by the S6 splint. Six subjects in masseter EMG and 7 subjects in temporal EMG got worse with the S6 splint compared to NS. CONCLUSIONS: When the occlusal splints were used as a bruxism countermeasure, it was suggested from the analysis of muscle activities during sleep at night that the S3 splint was superior to the S6 splint.