• Journal of Oral Medicine and Pain
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• v.39 no.4
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• pp.146-151
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• 2014

Purpose: To determine whether a fatiguing clench significantly affects the changes in pressure pain threshold (PPT) in men compared to women. Methods: The changes of PPTs from before to after a sustained clench in 12 men and 12 women were obtained. We used a decrease in median frequencies of surface electromyography (EMG) power spectra from the start to the end of the sustained clench as evidence of fatigue. Endurance time for the clench was used as a covariate. Results: The median frequencies decreased after the clench in both the anterior temporalis and masseter muscles, did not differ with the muscle or the gender of the subjects, and none of the interaction terms were significant. The PPTs were lower for women for both muscles, were decreased after the sustained clench, but failed to show the hypothesized gender by time interaction. Conclusions: Our results show that women have lower PPTs than men, but do not respond differently than men to jaw muscle fatigue.

• Journal of Oral Medicine and Pain
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• v.24 no.2
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• pp.137-143
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• 1999

Aucubin, the natural product, which is isolated from Aucuba japonica, has a variety of pharmacological effects such as liver-protective function, inhibition of liver RNA and protein biosynthesis, hypotensive activity and antimicrobial effect, etc. This study was performed to investigate the effects of iridoid compounds on wound healing. The author prepared 0.1% aucubin solution and 0.1% aucubin ointment as an active form, aucubigenin to which aucubin was converted by ${\beta}$-glucosidase. Artificial surgical wound was made on either 1cm lateral side of the dorsal midline along the axis of spine of Sprague-Dawley rats under sterile technique. Application of 0.1% aucubin solution or 0.1% aucubin ointment to surgical wound was done daily. Light microscopic examination was performed on the postsurgical 3 days, 5 days, and 9 days. The 0.1% aucubin solution group epithelialized earlier than the control group and the fibrosis of granulation tissue of both aucubin groups were more prominent than the control group. Collectively, this study suggests the possibility of aucubin as a topical agent. Further research should be performed on the mechanism of aucubin on wound healing and proper formulation for effective topical agents.

• Journal of Oral Medicine and Pain
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• v.17 no.1
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• pp.41-50
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• 1992

The authors performed a experimental study to evaluate the effects of masticatory muscle fatigue on tooth contact and masticatory muscle activity in 26 normal healthy women. The experimental masticatory muscle fatigue was induced by unilateral biting of 5kg force on mandibular first molar. The results were as follows : 1. The initial symptom related to muscle fatigue pain appeared in 85.19 seconds of isometric contraction and the endurance time of isometric contraction was 203.15 seconds. 2. The pain occurred more frequently in masseter region than in temporal region. In masseter pain the incidence was almost equal between both sides, whereas the temporal pain was more in contralateral side. 3. The spontaneity and the symmetry of tooth contact during maximum clenching were reduced after isometric unilateral biting. 4. After induction of experimental muscle fatigue, the EMG activities of masseter muscles of both sides and ipsilateral temporal muscle showed the tendency of decreasing activities. 5. The asymmetry indicies of masseter and temporal muscles were reduced after isometric bilateral biting.

• Journal of Oral Medicine and Pain
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• v.17 no.1
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• pp.61-71
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• 1992

52 Dental students without masticatory problems were selected for this study. They were trained on several mandibular position and mandibular movement exercise, that is, rest position, light bite, tapping, hinge opening, habitual opening, opening limitation, stretch exercise, resistance exercise and clenching. The objectives of this study was to investigate the effects of mandibular movement exercise, especially stretch and resistance, on the experimentally guided limited mouth opening. Muscle activity of the anterior temporalis and the masseter on above mentioned position or exercise were recorded with bioelectric processor EM2(Myotronics, U.S.A.) and the data were processed with SPSS. The obtained results were as follows : 1. Activity of the muscles at rest position were decreased with mandibular movement exercise. 2. Forceful mouth opening on opening limitation increased muscle activity greatly, especially of the masseter. 3. On opening limitation, stretch or resistance exercise was very efficient for decrease of muscle activities. 4. There were no difference of muscle activity between on hinge opening and on habitual opening. Therefore, for muscle relaxation, the two movement exercise can be used interchangeably.

• Journal of Oral Medicine and Pain
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• v.17 no.1
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• pp.89-94
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• 1992

To evaluate Helhimo's Anamnestic Dysfunction Index(AI), Helkimo's Clinical Dysfunction Index(HDI), and Friction's Craniomandibular Index(CMI) in Korean Young population, clinical examinations were performed in 207 dental college students who were healthy and had no evidence of the craniomandibular disorders. The obtained results were as follows; 1. The mean values of the Helkimo's Anamnestic Index(AI), Clinical Dysfunction Index(HDI), Fricton's Palpation Index(PI), Dysfunction Index(DI), and Craniomandibular Index(CMI) were 0.35, 0.71, 0.03, 0.05, and 0.04 in male subjects. 2. The mean values of the Helkimo's Anamnestic Index(AI), Clinical Dysfunction Index(HDI), Fricton's Palpation Index(PT), Dysfunction Index(DI), and Fricton's Craniomandibular Index(CMI) were 0.42, 0.72, 0.02, 0.04, and 0.03 in female subjects. 3. There was no statistically significant difference between male and female subjects in each parameter. 4. The palpation index(PI) observed in Korean Young Population was lower than that in American population.

• Imaging Science in Dentistry
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• v.49 no.3
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• pp.229-234
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• 2019

Central odontogenic fibroma (COF) is defined as a fibroblastic odontogenic tumor characterized by varying density of the tooth epithelium. It is an extremely rare benign neoplasm that occurs in the maxilla and the mandible; only a few reports of COF are available in the literature. Diagnosis of the lesion based only on the radiological features of COF is difficult due to variation in the findings regarding this condition. This report describes 2 clinical cases of middle-aged women with COF. Clinical examination revealed palatal mucosal depression; additionally, oral examination, as well as panoramic radiographs, intraoral radiographs, and computed tomography scans, revealed severe root resorption. This report highlights the clinical and radiological imaging features of COF, with the goal of enabling straightforward differential diagnosis of the lesion by the clinician and thereby appropriate treatment of the patient.

• Imaging Science in Dentistry
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• v.47 no.3
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• pp.189-197
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• 2017

Purpose: To quantify artifacts from different root filling materials in cone-beam computed tomography (CBCT) images acquired using different exposure parameters. Materials and Methods: Fifteen single-rooted teeth were scanned using 8 different exposure protocols with 3 different filling materials and once without filling material as a control group. Artifact quantification was performed by a trained observer who made measurements in the central axial slice of all acquired images in a fixed region of interest using ImageJ. Hyperdense artifacts, hypodense artifacts, and the remaining tooth area were identified, and the percentages of hyperdense and hypodense artifacts, remaining tooth area, and tooth area affected by the artifacts were calculated. Artifacts were analyzed qualitatively by 2 observers using the following scores: absence (0), moderate presence (1), and high presence (2) for hypodense halos, hypodense lines, and hyperdense lines. Two-way ANOVA and the post-hoc Tukey test were used for quantitative and qualitative artifact analysis. The Dunnet test was also used for qualitative analysis. The significance level was set at P<.05. Results: There were no significant interactions among the exposure parameters in the quantitative or qualitative analysis. Significant differences were observed among the studied filling materials in all quantitative analyses. In the qualitative analyses, all materials differed from the control group in terms of hypodense and hyperdense lines (P<.05). Fiberglass posts did not differ statistically from the control group in terms of hypodense halos(P>.05). Conclusion: Different exposure parameters did not affect the objective or subjective observations of artifacts in CBCT images; however, the filling materials used in endodontic restorations did affect both types of assessments.

• Journal of Oral Medicine and Pain
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• v.40 no.1
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• pp.1-2
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• 2015

• Imaging Science in Dentistry
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• v.50 no.2
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• pp.141-151
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• 2020

Purpose: This study aimed to quantify the influence of tooth position within the field-of-view (FOV) on cone-beam computed tomography (CBCT) imaging artifacts' intensity when assessing teeth restored with various intracanal materials. Materials and Methods: Seventy single-rooted teeth were divided into 7 groups (10 teeth per group): NiCr post (NC), AgPd post (AP), metal core fiberglass post (MCFG), fiberglass post (FG), anatomical fiberglass post (AFG), fiberglass post cemented with core build-up cement (FGCo), and anatomical fiberglass post cemented with core build-up cement (AFGCo). All posts were cemented using a regular dual-curing resin cement (Allcem), except FGCo and AFGCo which were cemented with a core build-up dual-curing resin cement (AllcemCore). Each tooth was scanned on a CS9000 in 5 positions within the FOV: a central position, anterior horizontal peripheral, peripheral superior, peripheral inferior, and posterior horizontal peripheral position. Hyperdense, hypodense, remaining teeth areas and ROI areas were quantitatively analyzed using ImageJ software. Results: Posterior horizontal peripheral position increased the intensity of artifacts on FGCo and AFGCo post groups (P<0.05), and specifically the hypodense artifact intensity on FG and AFG post groups (P<0.05). NC and AP groups presented greater intensity of artifacts than any other post groups(P<0.05). Conclusion: Artifact intensity increases in the presence of high atomic number materials and when the object is not centered within the FOV. The impact of positioning within the FOV on artifact was greater for fiberglass posts cemented with core build-up dual-curing cement than for metal posts and fiberglass posts cemented with regular dual-curing cement.

• Imaging Science in Dentistry
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• v.50 no.1
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• pp.23-30
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• 2020

Purpose: This study was conducted to assess the effectiveness of a metal artifact reduction (MAR) algorithm activated at different times during cone-beam computed tomography (CBCT) acquisition on the magnitude of artifacts generated by a zirconium implant. Materials and Methods: Volumes were obtained with and without a zirconium implant in a human mandible, using the OP300 Maxio unit. Three modes were tested: without MAR, with MAR activated after acquisition, and with MAR activated before acquisition. Artifacts were assessed in terms of the standard deviation (SD) of gray values and the contrast-to-noise ratio (CNR) in 6 regions of interest with different distances (10 to 35 mm, from the nearest to the farthest) and angulations(70° to 135°) from the implant region. Results: In the acquisitions without MAR, the regions closer to the implant(10 and 15mm) had a higher SD and lower CNR than the farther regions. When MAR was activated (before or after), SD values did not differ among the regions (P>0.05). The region closest to the implant presented a significantly lower CNR in the acquisitions without MAR than when MAR was activated after the acquisition; however, activating MAR before the acquisition did not yield significant differences from either of the other conditions. Conclusion: Both modes of MAR activation were effective in decreasing the magnitude of CBCT artifacts, especially when the effects of the artifacts were more noticeable.