Verification of the reliability of current perception threshold and pain threshold testing by application of an electrical current stimulus to mandibular mucosa in young adults.

BACKGROUND: There is little evidence regarding the reliability of CPT and PT measurements to gauge mandibular perception. Thus, this study aimed to evaluate the test-retest reliability of CPT and PT values obtained from the mandibular oral mucosa and to test the bilateral differences in CPT and PT values obtained from the mental foramen region and buccal shelf region by a single operator. METHODS: CPT and PT values were obtained from the mental foramen and buccal shelf regions of 20 volunteers (10 males and 10 females; average age: 26.4 ± 2.6 years) by using the Neurometer CPT/C® device to deliver electrical stimulation. RESULTS: Relative and absolute reliabilities were confirmed over two measurements of CPT and PT over a 7- to 10-day measurement interval. Intra-class correlation coefficients (ICCs) for CPT and PT table obtained from the mental foramen region were >0.8, while most ICC for the buccal shelf region were <0.8. Standard error of measurement, minimal detectable change and Bland-Altman analyses showed that the CPT and PT measurements had no systematic error and could serve as useful methods. At all frequencies, the bilateral difference in CPT and PT values at the mental foramen and buccal shelf region was not significant. CONCLUSION: CPT and PT measurements using a custom-made device that applied an electrical current to the mental foramen region have appropriate reliability to assess intra-oral sensitivity to electrical stimulation in young adults.

Verification of Implant Surface Modification by a Novel Processing Method.

Metals have been used clinically as biomaterials, especially in the orthopaedic and dental fields. Metals used as implants wear at contact surfaces, producing metal particles and metal ions that may be harmful. Newly developed metal implants and methods of implant surface modification are currently under scrutiny. We evaluated the use of electrolytic in-process dressing (ELID) as a surface finishing method for metal implants. Metal implants processed using the ELID method (ELID group) or not processed (Non-ELID group) were inserted surgically into rabbit femurs. The rabbits were sacrificed postoperatively over a 24-week period. We assessed the concentrations of the cytokines, interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α, the resistance to implant pull-out, and histopathology at the implant site. There was no significant difference between the groups regarding the cytokine concentrations or implant pull-out resistance. Many particles indicating wear around the implant were noted in the Non-ELID group (n=10) but not the ELID group (n=13), while a fibrous membrane adhering to the every implant was noted in the ELID group. The formation of a fibrous membrane rather than metal particles in the ELID group may indicate improved biocompatibility, and it suggests that ELID may prevent corrosion in the areas of contact.

The effects of silicone-based resilient denture liners on pain: A randomized controlled trial.

PURPOSE: This randomized controlled trial aimed to study the effects of lining mandibular complete dentures with silicone-based resilient denture liners, especially with respect to sensation. METHODS: The trial included completely edentulous patients who were willing to fabricate new set of complete denture. A random permuted block method (block size: 4) was used to assign participants to one of the following groups: mandibular conventional denture (CD) group or mandibular denture with resilient denture liner (RD) group. The outcomes were evaluated using both, objective measures (current perception threshold (CPT) and pain threshold (PT)) for external stimuli measured using the Neurometer CPT® and subjective measures (physical pain and psychological discomfort measured using the Japanese version of Oral Health Impact Profile for Edentulous patients-OHIP-EDENT-J). The outcomes were measured twice, at immediately after completion of denture adjustments (first measurement), and 3 months after the completion of denture adjustments (second measurement). All outcomes were analyzed using the Student t-test. A p-value of <0.05 was considered statistically significant. RESULTS: CPT was significantly higher with RD than CD only at second measurement with frequency level of 2000 Hz and 5 Hz. The pain thresholds were significantly higher in the RD group than the CD group. The physical pain and psychological discomfort scores were significantly lower in the RD group than in the CD group. CONCLUSION: This study concludes that edentulous patients wearing mandibular complete dentures with silicone-based resilient denture liners dull perception mandibular ridge mucosa and felt less pain than those without the liners.

Receptivity of the mandible versus the maxilla to external stimuli in patients with complete dentures.

PURPOSE: This study aimed to investigate whether the mandible is more receptive to external stimuli than the maxilla in patients with complete dentures by comparing regional current perception thresholds (CPTs) and pain threshold (PTs). METHODS: A single operator obtained measurements from maxillae at the incisor foramen and the left side of the greater palatine foramen region and the mandible at the left side of the mental foramen region, using the Neurometer CPT/C device, CPT and PT values from the oral mucosa of 20 edentulous individuals wearing complete dentures were analyzed. Participant characteristics such as mucosal thickness, occlusal force, age, and sex. Mucosal thickness over target regions and occlusal force were measured by the same operator using Krupp SDM and Occlusal Force-Meter GM10s devices. Differences in CPT and PT among the three measurement regions were tested with an analysis of covariance, and post hoc t-tests with the Bonferroni correction. RESULTS: There were no significant differences between the mental foramen, incisor papilla, and greater palatine regions CPT values. PTs obtained at all current frequencies (2000Hz, 250Hz, and 5Hz) were lowest in the mental foramen region and highest in the greater palatine region. Covariates including sex, mucosal thickness, and occlusal force had no significant influence on CPT or PT values at all frequencies. CONCLUSIONS: The mandible exhibits higher receptivity to external pain stimuli than the maxilla.

Characteristics of the pain tolerance threshold induced by electrical stimulation of the alveolar ridge.

The purpose of this study was to determine the characteristics of the pain tolerance threshold (PTT) induced by electrical stimulation of the alveolar ridge. A total of 100 healthy volunteers studying or working at Nihon University School of Dentistry at Matsudo and patients from Nihon University School of Dentistry at Matsudo Affiliated Hospital, including 51 men (58.7 ± 17.6 years old) and 49 women (60.7 ± 17.1 years old), participated in this study. The volunteers were enrolled after obtaining written informed consent. PTT measurements were obtained using a Neurometer CPT/C® device to deliver electrical stimulation around the left greater palatine foramen at frequencies of 5 and 250 Hz. When the stimulus could no longer be tolerated, the participant released a button to automatically discontinue the stimulus. After the distribution of the PTT values was analyzed, the influence of gender, age, and Eichner index on PTT was analyzed. The Eichner index values were divided into three categories: group A (four supporting zones), group B (less than four supporting zones but with anterior tooth contact), and group C (no occlusal contact). The PTT values did not show a normal distribution. There were no significant differences in PTT between men and women. PTT was significantly associated with age (P = 0.017) at 5 Hz in men. There were no significant differences in PTT among the Eichner index groups. The characteristics of the PTT of the alveolar ridge are as follows: (1) age and PTT at 5 Hz are significantly associated with men but not with women, and (2) the Eichner index has no influence on the PTT.

Maxillary sensory nerve responses induced by different types of dentures.

PURPOSE: The purpose of this study was to investigate whether different types of dentures induced different responses to stimulations in sensory nerve underlying the denture-supporting mucosa using current perception threshold (CPT). MATERIALS AND METHODS: The study population comprised 45 complete denture wearers with a mean age of 69.7 years (CD), 30 partial denture wearers (PD) with a mean age of 67.1 years, and 40 dentulous participants with a mean age of 69.0 years (Dent). Current perception threshold (CPT) on the greater palatine nerve at 2000 Hz, 250 Hz, and 5 Hz, corresponding to A-beta, A-delta, and C fibers respectively, were measured by the Neurometer® NS3000 device. The differences CPTs among CD, PD, and Dent groups were analyzed by Kruskal-Wallis test and Mann-Whitney U test with adjusting the multiple comparisons' inflation of type 1 error rate by a Bonferroni correction. RESULTS: CPTs of CD, PD, and Dent group at 2000 Hz were 61.5±45.8, 53.5±25.3, 33.0±11.4 (10(-2) mA) respectively. CPTs of CD, PD, and Dent group at 250 Hz were 29.2±28.2, 20.1±13.2, 14.3±5.9 (10(-2) mA) respectively. CPTs of CD, PD, and Dent group at 5 Hz were 28.9±23.4, 17.8±12.2, 12.2±5.6 (10(-2) mA) respectively. The CPTs at all frequencies increased in the following order: Dent