Pronunciation requires speed and accuracy, like many other fundamental activities such as breathing, eating, and walking. People can pronounce almost automatically without paying much attention to correctness, also like other activities. However, people may have to focus carefully on pronunciation when learning a foreign language, wearing dental appliances or rehabilitating after an injury or disease that affects speech. In the present study, we investigated neural changes underlying the process of learning new movement patterns of pronunciation in such cases. Nine healthy adults participated in the study. Difficulty of pronunciation was evaluated and cortical activity was measured under three conditions (overt and covert speaking, and silent reading) by fMRI three times after they wore orthodontic appliances. We found that the right superior temporal gyrus (STG) was involved in the auditory feedback control of pronunciation with the appliances, and the activity of the right STG was well correlated with the subjective difficulty of pronunciation and its time-dependent reduction. On the other hand, neural changes related to somatosensory feedback control and motor control of pronunciation did not show any time-dependent change. Our findings indicate that auditory feedback control of pronunciation is more important than motor control and somatosensory feedback control for learning new movements related to pronunciation.
To examine the neural basis of navigation we recorded the activity of neurons in the monkey medial parietal region (MPR) while monkeys actively navigated through a virtual environment. We found navigation neurons whose responses to the same movement at the same location were modulated depending on the route that the monkey was currently taking, that is, in a route-selective manner. The reversible inactivation of MPR neurons by muscimol resulted in a monkey becoming lost during the navigation task trial. These results suggest that MPR plays a critical role in navigation by integrating location information and self-movement information.
The mechanical characteristics of zirconia, hybrid hard resin and dental metal for crowns and fixed partial dentures (FPD) have been researched for clinical applications. However, for these kinds of restorations, the distribution of mechanical stress around the abutment teeth and periodontium during function has not been sufficiently assessed. The aim of this study was to clarify the influence of these materials upon abutment teeth and periodontium through a two-dimensional photoelastic method. Two-dimensional simulation models of three-unit FPDs were constructed from these materials. By applying a force of 400 N vertically to these FPDs, the stress distribution around the abutment teeth and alveolar bone was analyzed and the fringe orders were recorded with a transmission polariscope. As a result, the fringe order values at the root dentin around the marginal area of the pontic joint were the highest in zirconia, and the smallest in hybrid hard resin. The spread of internal stress around the marginal area was larger in the hybrid hard resin model and dental metal model than in the zirconia model. This study suggested that differences in stress distribution within the abutment teeth and around the alveolar bone were related to differences in elastic coefficients of the materials used in FPDs.
Overexpression of epidermal growth factor receptor (EGFR) is known to be associated with poor prognosis in malignant tumors. Sodium-glucose co-transporter 1 (SGLT1) is a membrane protein that transports glucose across cellular membranes. Recently, EGFR has been shown to stabilize SGLT1 and promote glucose uptake into cancer cells. The purpose of this study was to investigate the coexpression of EGFR and SGLT1 and their relationships with clinicopathological features in oral squamous cell carcinoma (OSCC). Total cell lysates from OSCC cell lines were prepared to check the protein expression of EGFR and SGLT1 by western blotting assay. Both proteins can be detected and the expression levels of SGLT1 were significantly correlated with those of EGFR. Pearson's product-moment correlation coefficient was 0.89 (p = 0.016). Transient overexpression of EGFR in HeLa cells showed that SGLT1 expression was increased by EGFR, suggesting that EGFR can stabilize the protein stability of SGLT1. To see whether mRNA expression of SGLT1 is correlated with protein expression, real-time PCR was performed. The results revealed no compatible expression between mRNA and protein, indicating that this discrepancy is caused by the post-transcriptional modification. Immunohistochemical staining using surgical specimens from 52 tongue SCC patients also showed a significant correlation between EGFR and SGLT1 expression. Moreover, EGFR/SGLT1 expression was inversely correlated with tumor differentiation (p = 0.004). These results indicate that EGFR/SGLT1 coexpression may contribute to the growth and survival of OSCC, but further study is needed to clarify the implication of these proteins in the manifestation of malignancy and clinical significance.
PURPOSE:The purpose of this study was to clarify the clinico-pathological findings of Warthin's tumors.SUBJECTS AND METHODS:Twenty cases of Warthin's tumors treated at our clinic during the past 22 years and their medical charts and imaging films were reviewed.RESULTS:Warthin's tumors occurred more frequently in middle-aged or elderly men than in women. Solitary tumors were significantly larger (p < 0.05) than multiple tumors. Warthin's tumors that accumulated 99mTc were significantly larger (p < 0.05) than those that did not. In addition, there was no difference in clinical findings between the two histopathologic types of Warthin's tumors.CONCLUSION:The frequent occurrence of multiple Warthin's tumors indicated the importance of an accurate clinical and radiological examination of parotid glands, in order to detect possible multiple lesions prior to treatment.
While oral care is known to play an important role in the prevention of aspiration pneumonia, its influence on immune function is unclear. In this study, we performed oral care on ten dependent elderly individuals and examined its influence on NK cell activity. The study duration was 12 weeks. During the first six weeks, the subjects cleaned their mouths as usual (control period). In the last six weeks, a dental hygienist performed oral care and denture cleaning three times a week (intervention period). The outcome measure was the quantity of oral bacteria and the detection rate of the microbe in connection with an opportunistic infection and NK cell activity before and after the intervention. Samples were collected at three time points: the beginning of the study, after the control period and before the intervention period (i. e., after six weeks), and after the intervention period (i. e., after 12 weeks). There was no significant difference in the number of oral bacteria between the control period and the intervention period. In contrast, while NK cell activity did not change during the control period, activity increased during the intervention period (p = 0.03). This finding suggests that rather than decreasing the number of oral bacteria, oral care increases NK cell activity.
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 association between phenytoin-induced gingival hyperplasia (PIGH) and five major periodontopathic bacteria was investigated by real-time PCR in 12 subjects (30.6 +/- 7.95 years of age) with severe motor and intellectual disabilities. The subjects had not received antibiotics or periodontal therapy within three months. A healthy gingival site or a site with the lowest gingival hyperplasia score (minimum site), and a site with the maximum score of gingival hyperplasia (maximum site) on each subject were selected for investigation. The clinical parameters were measured after microbial sampling. The following results were obtained: 1. The detection rates of both Treponema denticola and Porphyromonas gingivalis were 75% (9/12) at the maximum sites, and that of Tannerella forsythia was 33.3% (4/12). The detection rate of Prevotella intermedia was 58.3% (7/12), but no significant correlation was observed between this bacterium and the other types of bacteria in quantitative analysis. 2. The detection rate of P. gingivalis with type II fimA was 25% (1/4) at the minimum sites, and 83.3% (5/6) at the maximum sites. 3. The samples were divided into three groups; namely, those with no detection of P. gingivalis at either the minimum sites or the maximum sites, no detection at the minimum sites but detection at the maximum sites, and detection at both sites. In conclusion, 1) the detection rates of T. denticola and P. gingivalis were the highest at the maximum sites. In particular, the detection rate of P. gingivalis with type II fimA was high in the present study, and 2) the subgingival microflora was diverse because of the diverse severity of gingival inflammation associated with PIGH.
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.
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 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.
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.
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 connecting rigidity of the retainer and the denture supporting area may influence the distribution of the occlusal load. Three types of retainers (wrought wire clasp, Akers cast clasp and conical crown telescopic retainer) and three outline forms of denture bases designed for distal extension removable partial dentures were assessed in six patients with Kennedy Class II situations. To evaluate the influence of oral function, mandibular displacement, abutment tooth displacement, and denture base exerted pressure were measured simultaneously during maximum voluntary clenching. The mandibular displacement increased when the connecting rigidity decreased or the size of the denture base was reduced. The abutment tooth displacement increased as the denture base was reduced with the Akers clasp. The denture base pressure increased as the denture base reduced with the wrought wire clasp. The conical crown telescopic retainer did not cause overloading to the supporting tissues even when the denture base was reduced. It was also revealed that the abutment tooth tended to displace distally when a distal occlusal rest was prepared on the abutment tooth.
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.
Much research has been reported about post and core systems with composite resin, but the influence of the different types of prefabricated posts on the distribution of stress in the root has not yet been elucidated. It is necessary to clarify the influence of the relationship between core and crown materials to obtain combined restorations. The aim of this study is to analyze the influence of the combination of various post and core systems and different kinds of crown material on the stress distribution in the root. Six 2-dimensional photoelastic premolar models were designed. Three types of post and core systems (composite resin post and core, composite resin core with the fiber post, and composite resin core with a prefabricated stainless steel post) and two kinds of crown materials (metal and hybrid-type hard composite resin) were fabricated and cemented to each model. In these models, we applied a load of 200 N at an angle of 45 degrees to the tooth axis and analyzed the fringe order using a transmission polariscope. As a result, it has been clarified that the combination of the post and core and the crown plays an important role in preventing stress concentration within root Stress concentration can be prevented using a crown fabricated with a high-elastic modulus for the post and core with a high-elastic modulus, and a crown fabricated with a low-elastic modulus for the post and core with a low-elastic modulus.
Photodynamic diagnosis (PDD) is a form of cancer detection based on the administration of an exogenous photoactivated compound that accumulates in malignant cells, followed by appropriate photo-irradiation. 5-aminolevulinic acid (5-ALA), which is one of these compounds, is a prodrug of the photosensitizer protoporphyrin IX (PpIX). This report describes a spectroscopic study of 5-ALA-generated PpIX fluorescence in human oral cancer cell lines. After transplanting five human oral squamous carcinoma cell lines into scid mice, the degree of tumor differentiation was evaluated by hematoxylin-and-eosin staining. Two, one, and two cell lines were poorly, moderately, and well differentiated, respectively. Under cell culture conditions, well and moderately differentiated cancer cells showed higher positive staining rates of AE1/AE3 than poorly differentiated ones in immunohistochemistry. 5-ALA-induced PpIX fluorescence intensities of five cell lines, which were cultured in Dulbecco's Modified Eagle's Medium (DMEM) treated with or without deferoxamine mesylate (DFO), were measured. In all cell lines, the maximum 5-ALA-generated fluorescence intensity was found in the presence of DFO. The fluorescence intensity varied with the degree of tumor differentiation in the following order: poorly differentiated, moderately differentiated, well differentiated. These results suggest that the fluorescence intensity of oral cancer cells differs according to the degree of tumor differentiation. However, even with well differentiated cancer cells, addition of DFO could increase the photodynamic sensitivity of 5-ALA as a result of greater cellular accumulation of PpIX.
A surgical guiding system with simulation software has recently been used for safe implant treatment. We report a clinical case in which we successfully used this system for implant treatment of a congenital tooth missing region with severely restricted mesiodistal space. The patient was a 19-year-old female whose mandibular right deciduous canine was wobbling without a successional permanent tooth and who desired implant treatment. CT images showed that this site was narrow buccal-lingually and only five millimeters in mesiodistal width. The implant position was planned using simulation software (SimPlant : Materialise Dental) based on CT data and a surgical guide template (SurgiGuide : Materialise Dental) was fabricated prior to the implant surgery. During the implant surgery, the deciduous canine was extracted under local anesthesia. The implant bed was prepared with the surgical guide template and an implant was installed. One month after surgery, the position of the implant was examined with a cone-beam CT, which demonstrated that the implant position was exactly the same as planned. At 5 months, a provisional prosthesis was delivered and optimal soft-tissue condition was formed by modifying the provisional prosthesis. Then, the final impression was taken and a ceramo-metal implant-supported crown was delivered. In this case of a congenital tooth missing region with narrow space, implant treatment with simulation software and the surgical guide system provided excellent clinical results.
