The role of the posterior palatal seal is important in retention of the maxillary complete denture. After taking the final impression, additional retention can be given to the maxillary denture through a mechanical method of forming a groove on master cast, but this is often overlooked in the clinical process. As a result, the posterior palatal seal is formed in a uniform way by the technician without considering the individual characteristics of the patient. Until now, various types of posterior palatal seal have been introduced by many people. This case report describes the process of manufacturing the maxillary complete denture by determining the position and form of an appropriate posterior palatal seal after considering the patient’s anatomical palatal form and tissue displacement during function.

PURPOSE: Grinding with less stress on 3Y-TZP through proper selection of methods and instruments can lead to a long-term success of prosthesis. The purpose of this study was to compare the phase transformation and physical properties after zirconia surface grinding with 3 different grinding burs. MATERIALS AND METHODS: Forty disc-shaped zirconia specimens were fabricated. Each Ten specimens were ground with AllCeramic SuperMax (NTI, Kahla, Germany), Dura-Green DIA (Shofu Inc., Kyoto, Japan), and Dura-Green (Shofu Inc., Kyoto, Japan). Ten specimens were not ground and used as a control group. After the specimen grinding, XRD analysis, surface roughness test, FE-SEM imaging, and biaxial flexural strength test were performed. RESULTS: After surface grinding, small amount of monoclinic phase in all experimental groups was observed. The phase change was higher in specimens, which were ground with Dura-Green DIA and AllCeramic SuperMax burs. The roughness of surfaces increased in specimens, which were ground with Dura-Green DIA and AllCeramic SuperMax burs than control groups and ground with Dura-Green. All experimental groups showed lower flexural strength than control group, but there was no statistically significant difference between control group and ground with Dura-Green DIA and AllCeramic SuperMax burs. The specimens, which were ground with Dura- Green showed the lowest strength. CONCLUSION: The use of dedicated zirconia-specific grinding burs such as Dura-Green DIA and AllCeramic SuperMax burs decreases the grinding time and did not significantly affect the flexural strength of zirconia, and therefore, they may be recommended. However, a fine polishing process should be accompanied to reduce the surface roughness after grinding.
Prostheses and Implants

OBJECTIVE: To identify risk factors for dysphagia in tongue cancer patients. Dysphagia is a common complication of surgery, radiotherapy, and chemotherapy in tongue cancer patients. Previous studies have attempted to identify risk factors for dysphagia in patients with head and neck cancer, but no studies have focused specifically on tongue cancer patients. METHODS: This study was conducted on 133 patients who were diagnosed with tongue cancer and who underwent a videofluoroscopy swallowing study (VFSS) between January 2007 and June 2012 at the Asan Medical Center. Data collected from the VFSS were analyzed retrospectively. Patients with aspiration were identified. RESULTS: Patients showed a higher incidence of inadequate tongue control, inadequate chewing, delayed oral transit time, aspiration or penetration, vallecular pouch and pyriform residue, and inadequate laryngeal elevation after surgery. Moreover, male gender, extensive tumor resection, a higher node stage, and more extensive lymph node dissection were major risk factors for aspiration in tongue cancer patients. CONCLUSION: Tongue cancer patients have difficulties in the pharyngeal phase as well as the oral phase of swallowing. These difficulties can worsen after tongue cancer surgery. Gender, the extent of tumor resection, and lymph node metastasis affect swallowing in tongue cancer patients. Physicians should take these risk factors into account when administering swallowing therapy to tongue cancer patients.
Chungcheongnam-do ; Deglutition ; Deglutition Disorders* ; Drug Therapy ; Head and Neck Neoplasms ; Humans ; Incidence ; Lymph Node Excision ; Lymph Nodes ; Male ; Mastication ; Neoplasm Metastasis ; Radiotherapy ; Retrospective Studies ; Risk Factors ; Tongue ; Tongue Neoplasms*

PURPOSE: This study was conducted to obtain difference in fracture strength according to the diameter of one-body O-ring-type of mini implant fixture, to determine the resistance of mini implant to masticatory pressure, and to examine whether overdenture using O-ring type mini implant is clinically usable to maxillary and mandibular edentulous patients. MATERIALS AND METHODS: For this study, 13 mm long one body O-ring-type mini implants of different diameters (2.0 mm, 2.5 mm and 3.0 mm) (Dentis, Daegu, Korea) were prepared, 5 for each diameter. The sample was placed at 30degrees from the horizontal surface on the universal testing machine, and off-axis loading was applied until permanent deformation occurred and the load was taken as maximum compressive strength. The mean value of the 5 samples was calculated, and the compressive strength of implant fixture was compared according to diameter. In addition, we prepared 3 samples for each diameter, and applied loading equal to 80%, 60% and 40% of the compressive strength until fracture occurred. Then, we measured the cycle number on fracture and analyzed fatigue fracture for each diameter. Additionally, we measured the cycle number on fracture that occurred when a load of 43 N, which is the average masticatory force of complete denture, was applied. The difference on compressive strength between each group was tested statistically using one-way ANOVA test. RESULTS: Compressive strength according to the diameter of mini implant was 101.5 +/- 14.6 N, 149 +/- 6.1 N and 276.0 +/- 13.4 N, respectively, for diameters 2.0 mm, 2.5 mm and 3.0 mm. In the results of fatigue fracture test at 43 N, fracture did not occur until 2x106 cycles at diameter 2.0 mm, and until 5x106 cycles at 2.5 mm and 3.0 mm. CONCLUSION: Compressive strength increased significantly with increasing diameter of mini implant. In the results of fatigue fracture test conducted under the average masticatory force of complete denture, fracture did not occur at any of the three diameters. All of the three diameters are usable for supporting overdenture in maxillary and mandibular edentulous patients, but considering that the highest masticatory force of complete denture is 157 N, caution should be used in case diameter 2.0 mm or 2.5 mm is used.
Bite Force ; Collodion ; Compressive Strength ; Denture, Complete ; Denture, Overlay ; Fatigue ; Fractures, Stress ; Humans

OBJECTIVE: To investigate whether patterns of dysphagia and swallowing laterality differ according to the location of brain lesions in patients with stroke. METHODS: Patients with stroke >20 years of age were enrolled in this study. A videofluoroscopic swallowing study (VFSS) including the anterior-posterior view was used to assess swallowing. Patterns of swallowing were classified into three types according to the width of barium sulfate flow while passing the pharyngoesophageal segment: right-side-dominant flow, left-side-dominant flow, and no laterality in flow. Laterality was defined when the width of one side was twice or more the width of the other side. RESULTS: A total of 92 patients who underwent swallowing function evaluations by VFSS were enrolled from Sep-tember 2012 to May 2013. Of these, 72 patients had supratentorial lesions (group I) and 20 patients had infratento-rial lesions (group II). Only 10 patients (13.9%) in group I and three patients (15.0%) in group II showed laterality. Of these 13 patients, laterality occurred on the left side regardless of the side of the brain lesion. No relationships were found between swallowing laterality and location of stroke or motor weakness. CONCLUSION: The results suggest that swallowing laterality was not prevalent among patients with stroke and that lesion side, location of the brain lesion, or motor weakness did not influence swallowing laterality. Although stroke can cause symptoms of dysphagia, it is difficult to conclude that stroke has a crucial impact on swallowing laterality.
Barium Sulfate ; Brain ; Deglutition Disorders ; Deglutition* ; Humans ; Stroke*

PURPOSE: The purpose of this study was to analyze the antimicrobial, antioxidant activity and cytotoxicity of Dendropanax morbifera Léveille extract for assessing whether Dendropanax morbifera Léveille can be used for the development of natural mouthwash and denture cleaning solution. MATERIALS AND METHODS: The extract was obtained from branches of Dendropanax morbifera Léveille. The solvent fractions were acquired by fractionating Dendropanax morbifera Léveille extract using n-hexane, ethyl acetate, chloroform and butanol solvent. Paper disc test was used to evaluate the antimicrobial and antifungal activity of Dendropanax morbifera Léveille extract and solvent fractions against Streptococcus mutans and Candida albicans. The analysis of antioxidant activity was carried out through DPPH radical scavenging assay. The cytotoxicity of Dendropanax morbifera Léveille extract was analyzed through MTT assay using normal human oral keratinocytes. RESULTS: Dendropanax morbifera Léveille extract showed antimicrobial activity against Streptococcus mutans and especially Candida albicans. The solvent fractions of Dendropanax morbifera Léveille showed strong antimicrobial activity against Streptococcus mutans and Candida albicans in n-hexane and butanol solvent fraction, respectively. Dendropanax morbifera Léveille extract also showed outstanding antioxidant activity. Butanol, ethyl acetate, and chloroform solvent fraction of Dendropanax morbifera Léveille tended to have increased antioxidant activity as the concentration increased. Dendropanax morbifera Léveille extract showed high cell survival rate in cytotoxicity test. CONCLUSION: Dendropanax morbifera Léveille extract turned out to have antimicrobial, antioxidant activity and cytophilicity. Based on these results, it is expected that Dendropanax morbifera Léveille is applicable as an ingredient for natural mouthwash and denture cleanser.
Candida albicans ; Cell Survival ; Chloroform ; Denture Cleansers ; Dentures* ; Humans ; Keratinocytes ; Streptococcus mutans

OBJECTIVE: To investigate whether virtual reality (VR) training will help the recovery of cognitive function in brain tumor patients. METHODS: Thirty-eight brain tumor patients (19 men and 19 women) with cognitive impairment recruited for this study were assigned to either VR group (n=19, IREX system) or control group (n=19). Both VR training (30 minutes a day for 3 times a week) and computer-based cognitive rehabilitation program (30 minutes a day for 2 times) for 4 weeks were given to the VR group. The control group was given only the computer-based cognitive rehabilitation program (30 minutes a day for 5 days a week) for 4 weeks. Computerized neuropsychological tests (CNTs), Korean version of Mini-Mental Status Examination (K-MMSE), and Korean version of Modified Barthel Index (K-MBI) were used to evaluate cognitive function and functional status. RESULTS: The VR group showed improvements in the K-MMSE, visual and auditory continuous performance tests (CPTs), forward and backward digit span tests (DSTs), forward and backward visual span test (VSTs), visual and verbal learning tests, Trail Making Test type A (TMT-A), and K-MBI. The VR group showed significantly (p<0.05) better improvements than the control group in visual and auditory CPTs, backward DST and VST, and TMT-A after treatment. CONCLUSION: VR training can have beneficial effects on cognitive improvement when it is combined with computer-assisted cognitive rehabilitation. Further randomized controlled studies with large samples according to brain tumor type and location are needed to investigate how VR training improves cognitive impairment.
Brain Neoplasms* ; Cognition ; Humans ; Male ; Neuropsychological Tests ; Rehabilitation ; Trail Making Test ; Verbal Learning ; Virtual Reality Exposure Therapy

PURPOSE: The aim of this retrospective study was to evaluate the influence of implant diameter, length and placement to implant stability. MATERIALS AND METHODS: Total 90 implants (US II plus(TM), Osstem co, Busan, Korea) of 72 patients were determined as experimental samples. The factors of diameters(o 4 mm, o 5 mm), lengths (10 mm, 11.5 mm, 13 mm), and implant placement (maxilla, mandible) were analyzed. The stability of the implants was measured by resonance frequency analysis (RFA) at the time of implant placement and impression taking. The difference of ISQ values according to patient's gender was evaluated by Independent t-test. ISQ values were compared between implant diameter, length and placement using one-way ANOVA and Tukey HSD test (alpha=.05). To compare ISQ values between at the time of surgery and impression taking, paired t-tests were used (alpha=.05). RESULTS: The change of implant length did not show significant different on the ISQ value (P>.05). However, 5 mm diameter implants had higher ISQ values than 4 mm diameter implants (P<.05). Implants placed on the mandible showed significantly higher ISQ values than on the maxilla (P<.05). CONCLUSION: In order to increase implant stability, it is better to select the wider implant, and implants placed on mandible are possible to get higher stability than maxilla. ISQ values at impression taking showed higher implant stability than ISQ values at implant placement, it means that RFA is clinically effective method to evaluate the change of implant stability through the osseointegration. The consideration of the factors which may affect to the implant stability will help to determine the time of load applying and increase the implant success rate.
Dental implants* ; Humans ; Mandible ; Maxilla ; Osseointegration ; Retrospective Studies*

PURPOSE: The aim of this study was to analyze the shapes of lingual polished surfaces in lower complete dentures formed by polished surface impressions and to provide reference data for use when manufacturing edentulous trays and lower complete dentures. MATERIALS AND METHODS: Twenty-six patients with mandibular edentulism were studied. After lower wax dentures were fabricated, wax was removed from the lingual side of the wax denture and a lingual polished surface impression was obtained with tissue conditioner. The definitive denture was scanned with a three-dimensional scanner, and scanned images were obtained. At the cross-sections of the lingual frenum, lateral incisors, first premolars, first molars, and anterior border of the retromolar pads, three points were marked and eight measurements were taken. The Kruskal-Wallis test and a post hoc analysis with the Mann-Whitney test were performed. RESULTS: Each patient showed similar values for the same areas on the left and right sides without a statistically significant difference. The height of the contour of the lingual polished surface at the lingual frenum was halfway between the occlusal plane and lingual border, it moved gradually in a downward direction. The angle from the occlusal plane to the height of the contour of the lingual polished surface was increased as it progressed from the lingual frenum towards the retromolar pads. CONCLUSION: The shape of the mandibular lingual polished surface was convex at the lingual frenum, lateral incisors and gradually flattened towards the first molars and retromolar pads.
Bicuspid ; Dental Occlusion ; Denture, Complete* ; Dentures ; Humans ; Incisor ; Lingual Frenum ; Molar

PURPOSE: The purpose of this in vitro study was to evaluate the effect of surface grinding and polishing procedures using high speed zirconia diamond burs with different grit sizes on the phase transformation and flexural strength of zirconia.
Dental Instruments ; Diamond ; In Vitro Techniques ; Occlusal Adjustment