Kokubyo Gakkai zasshi. The Journal of the Stomatological Society, Japan最新文献

Response properties of periodontal single afferents were investigated in cats with inflammatory irritant-induced pulpitis. A deep dentin cavity was prepared on the right mandibular canine in order to apply an inflammatory agent and small fiber excitant, allyl-isothiocyanate (mustard oil: MO), and single afferents innervating the canine periodontal mechanoreceptor were dissected from the mandibular nerve bundle by examining impulse responses while applying mechanical stimuli to the tip of the crown. Evoked impulses by mechanical stimuli were increased in number for 15 minutes with MO application to the pulp when compared with those with mineral oil. The mechanoreceptive thresholds of single nerve fibers were decreased after the MO application to the pulp when compared with those with mineral oil. These results suggest that the alteration of responses in the periodontal afferent fiber, or the peripheral sensitization, can be produced by MO-induced pulpal inflammation probably due to the axon reflex mechanism in the furcating branches of nerve fibers innervating both the tooth pulp and periodontal ligament.

Although highly concentrated hydrogen peroxide (HP) has been used to bleach vital discolored teeth during office whitening, low-concentration HP was recognized to have insufficient whitening ability. We demonstrated that using a visible light-responsive titania photocatalyst (VLRTP) and a vis-Nd : YAG laser, 3 wt% HP-bleached oxytetracycline (OTC)-stained teeth models were more efficient than 30 wt% HP. The stained samples were prepared by soaking synthetic hydroxyapatite ceramic disks in OTC aqueous solutions. Color images of the OTC-stained models before and after whitening were taken with a conventional flatbed scanner and calibrated using a photocell colorimeter. By VLRTP treatment with vis-Nd : YAG laser irradiation, the lightness value (L*) significantly increased and the yellowness index (b*) significantly approached zero. This suggests that a diluted HP agent with VLRTP can more efficiently decolorize stained teeth by visible light irradiation.

The purpose of this study is to state the clinical and colorimetric features of pigmented lesions on oral mucosa. Among 201 pigmented lesions on oral mucosa, there were 74 melanin pigmentations (36.9%), 72 exogenous pigmentations (35.8%), 28 pigmented nevi (13.9%), and 27 malignant melanomas (13.4%). Melanin pigmentations were found mainly on the gingiva and lip, exogenous pigmentations were on the gingiva, pigmented nevi were found on the buccal mucosa, and malignant melanomas were on the upper gingiva. Thirty-six pigmented lesions were measured by colorimeter, and each lesion was evaluated numerically using the CIE L*a*b* colorimetric system. The statistical significance was confirmed by Tukey's test and a p value <0.05 was assumed as a significant difference. The color distribution of melanin pigmentation and exogenous pigmentation and malignant melanoma were significantly lower than normal mucosa in L*. A statistical significance was found between each pigmented lesion and normal mucosa in a* and b*. Among malignant melanoma and melanin pigmentation or exogenous pigmentation, a statistical significance was found in a* and b*. The color difference between melanin pigmentation and malignant melanoma was significant. The color distribution is thought to be different in each pigmented lesion, and we suggest that it is useful to use colorimetric features to diagnose each pigmented lesion.

The purpose of this study is to measure the morphology of the nose and lip of unilateral cleft lip/cleft lip and palate (UCL/UCLP) patients with a three-dimensional (3-D) digitizer before and after secondary cleft lip and nose repair, and to compare them with normal adults, as well as to investigate the effectiveness of philtrum plastic surgery. This study includes 21 UCL/CLP patients who received the same operation. We used 12 normal adults as the control group. We took facial impressions at the time of pre-operation and six months after operation, and constructed the models using hard plaster. These plaster casts were used as materials in this study. The control materials were also made from normal adults in the same manner. All the measurements were taken using calipers and the depth of the philtral dimple was measured with a 3-D digitizer. The distance between the inside of the eye and the alar base, the distance between the bilateral alar bases, the distance between the columella base and the alar base were measured. The length of philtrum ridge showed obvious signs of improvement, and was almost the same as normal adults after our surgical approach. The width of the philtrum and the depth of the philtral dimple of UCL/CLP patients were improved after secondary cleft lip and nose repair. However, further treatment is still essential for better aesthetics and recovery.

Recently, it has been shown that prolonged feeding of a liquid diet after being weaned impedes the functional development and leads to immature mastication in growing rats. Since the jaw muscle spindles play an important role in the control of the jaw movement during the normal masticatory function, in this study we investigated the effects of prolonged feeding of a liquid diet after being weaned on the functional development of the jaw-closing muscle spindles in growing rats. Soon after weaning, 40 female Wistar rats were divided into two equal groups. The control group was fed a solid diet and the experimental group was fed a liquid diet. At 5, 7, 9 and 11 weeks, the rats were anesthetized and the response of the masseter muscle spindles to ramp-and-hold jaw stretches were recorded from the mesencephalic trigeminal nucleus. In the experimental groups, both the dynamic and the static indices were significantly lower than those of the control groups at the age of 5, 7, 9 and 11 weeks old. There was no significant change within the same group during the experimental period in both indices. These results suggest that the long-term masticatory functional change due to feeding of a liquid diet may impede the maturation of the functional properties of the jaw-closing muscle spindles, leading to immature mastication in growing rats.

Firm adhesion of composite resin and dentin is the basic premise for building up resin composite cores successfully. To assess the efficacy of several caries detective methods (stained with Caries Detector and probing with sharp probe) for caries affected root canal dentin, microtensile bond strengths of resin composite to caries-affected root canal dentin and failure mode distribution were analyzed in this study. Color and hardness were used for assessment of root caries as follows: Dye stain group (pale pink stained with Caries Detector), Probing group (probing with sharp probe) and Sound dentin group (Control). The bond strengths (mean +/- standard deviation) of the Probing group (64.6 +/- 11.9 MPa) and the Sound dentin group (68.7 +/- 11.1 MPa) were significantly higher than those of the Dye stain group (46.9 +/- 7.9 MPa, p<0.05). However, there is no significant difference in fracture mode between the Dye stain group and the Probing group (p<0.05). This could be attributed to that the thick smear layer caused a loss of hybrid layer strength. In conclusion, the caries removal technique of the root canal dentin affected the bond strength of the resin composite.

A preliminary study revealed that an autopolymerization addition silicone resilient denture relining material (SI) had excellent shock absorption properties similar to those of thermoplastic materials commonly used for mouthguards (ethylene-vinyl acetate: EVA). The aim of the present study was to examine the bonding strength of SI and EVA using a newly-developed adhesive prototype. Delamination tests and tensile strength tests were performed to compare the bonding strengths of SI on EVA prepared under the following four conditions: 1) Control condition (no preparation; C), 2) Sandblasting (S), 3) Bonding with the adhesive prototype (M), and 4) Combination of sandblasting preparation and bonding with the adhesive prototype (SM). The mean bonding strength (S. D.) of the delamination tests under the C, S, M and SM conditions were 0.167 (0.003) N/mm, 0.273 (0.034) N/mm, 0.242 (0.027) N/mm and 0.506 (0.113) N/mm, respectively. The mean bonding strength (S. D.) of the tensile strength tests under the C, S, M and SM conditions were 0.006 (0.011) MPa, 0.081 (0.105) MPa, 0.231 (0.069) MPa and 0.590 (0.041) MPa, respectively. Two-way analysis of variances and Tukey's HSD test detected that the combination of sandblasting preparation and bonding with the adhesive prototype significantly improved the bonding strength between SI and EVA. The results indicate that the self-curing addition silicone resilient denture relining material may adhere to the thermoplastic material prepared by combined application of sandblasting and the adhesive prototype, suggesting the potential of the dental silicone rubber material as a material for repairing mouthguards in clinical practice.

The purpose of this study is to clarify the effect of advance notice of contents of treatment on the patients' physiological stress during dental treatment The subjects of our study comprised 34 non-dental professionals (22 female and 12 male). In simulated dental treatment, the subjects were exposed to predetermined stimulations comprised of blowing air on the molars, percussion on the premolar and usage of an air turbine next to the molar in randomized order, with/without advance notice. The skin potential level (SPL) of the subjects was measured as a physiological stress index during such simulated dental treatment As a psychological profile, the stress-coping style of each subject was examined using Lazarus Type Stress Coping Inventory (SCI). The number of decayed, missing, filled teeth (DMF). and the experience of teeth extraction in the past of each subject was also recorded. The correlation among advance notice, order and kind of stimulation, factors of SCI, DMF, gender of the subject, the experience of teeth extraction, and the subjects' stress (SPL change) was statistically analyzed using the generalized estimating equation. As a result, the effect of advance notice on the subjects' stress was opposite when the stress-coping style differed; therefore, dentists must pay attention to the patients' psychological characteristics when using advance notice for the purpose of relieving the patients' stress during dental treatment.

The objective of this study was to clarify the relation between the occlusal force and the tooth displacement path just after unloading, and to estimate the occlusal force during mastication with healthy natural teeth. Three-dimensional occlusal force was calculated from the magnitude of the occlusal force measured by pressure-sensitive film, and from normal vectors of the occlusal contact areas recorded on the study model. The tooth displacement paths were measured using the three-dimensional tooth displacement transducer type M-3. Three male subjects aged 27, 38, and 46 were selected. The subject teeth were their upper left molars. There are two phases of tooth displacement just after unloading: instantaneous recovery, and the subsequent slow recovery. If the maximum tooth displaced position is R, the critical tooth position at the beginning of slow recovery is C, and the original tooth position is O, then re represents the vector RC-->, and rv represents the vector CO-->. The values of re and rv calculated for each unloading tooth displacement path just after clenching the pressure-sensitive film showed different physical properties. The dominant direction of re was to the buccal side, and that of rv was to the coronal side. The coefficient of correlation between the magnitude of occlusal force and re was 0.81-0.87, and that between the magnitude of occlusal force and rv was 0.20-0.63. Based on these physical properties, it was considered that re depends on the recovery of the distortion of alveolar bone, and rv depends on that of periodontal membrane. As described above, the occlusal force during mastication, which is fast movement, can be estimated from re.

The unilateral bolus passage through the upper esophageal sphincter (UES) is often observed in swallow evaluations of patients following neck dissection. Head rotation toward the paretic side was reported to be useful to prevent aspiration; however, we often encounter cases of head and neck surgical patients in which the bolus passes through the non-surgical side. Therefore, we investigated UES flow after head and neck surgery to evaluate the laterality to find an effective treatment technique after a head and neck operation. Videofluoroscopic swallowing studies (VFSS) were conducted in 23 oral cancer patients who underwent unilateral neck dissection but not tongue resection. Patients comprised 12 males and 11 females, with a mean age of 62 (SD=14) years. Preoperative VFSS showed that none had a predominant side for UES flow. The laterality of the bolus flow through the UES was predominantly on the side of neck dissection in post-operation. Lateral VFSS showed elevation of the hyoid and the larynx on the non-dissected side was greater compared to the dissected side. Therefore, head rotation toward non-dissected side can be effective for head and neck surgical patients.