PURPOSE: The purpose of this study was to evaluate the proper axial thickness of zirconia abutment applied to implant in the anterior region. MATERIALS AND METHODS: Zirconia abutments were prepared at different axial wall thickness by processing pre-sintered zirconia blocks via CAD/CAM to obtain equal specimens. The abutments were each produced with a thickness of 0.5 mm (Group 1), 0.8 mm (Group 2), 1.2 mm (Group 3), or 1.5 mm (Group 4). The implant used in this study was a external connection type one (US, Osstem, Pussan, Korea) product and the zirconia abutment was prepared via replication of a cemented abutment. The crowns were prepared via CAM/CAM with a thickness of 1.5 mm and were cemented to the abutments using RelyX(TM) UniCem cement. A universal testing machine was used to apply load at 30 degrees and measure fracture strength of the zirconia abutment. RESULTS: Fracture strength of the abutments for Group 1, Group 2, Group 3, and Group 4 were 236.00 +/- 67.55 N, 599.00 +/- 15.80 N, 588.20 +/- 33.18 N, and 97.83 +/- 98.13 N, respectively. Group 1 showed a significantly lower value, as compared to the other groups (independent Mann-Whitney U-test. P<.05). No significant differences were detected among Group 2, Group 3, and Group 4 (independent Mann-Whitney U-test. P>.05). CONCLUSION: Zirconia abutment requires optimal thickness for fracture resistance. Within the limitation of this study, > 0.8 mm thickness is recommended for zirconia abutment in anterior implants.
Crowns

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: 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

PURPOSE: The purpose of this study was to investigate the fit and screw joint stability between Ready-made abutment and CAD-CAM custom-made abutment. MATERIALS AND METHODS: Osstem implant system was used. Ready-made abutment (Transfer abutment, Osstem Implant Co. Ltd, Busan, Korea), CAD-CAM custom-made abutment (CustomFit abutment, Osstem Implant Co. Ltd, Busan, Korea) and domestically manufactured CAD-CAM custom-made abutment (Myplant, Raphabio Co., Seoul, Korea) were fabricated five each and screws were provided by each company. Fixture and abutments were tightening with 30Ncm according to the manufacturer's instruction and then preloding reverse torque values were measured 3 times repeatedly. Kruskal-Wallis test was used for statistical analysis of the preloading reverse torque values (alpha=.05). After specimens were embedded into epoxy resin, wet cutting and polishing was performed and FE-SEM imaging was performed, on the contact interface. RESULTS: The pre-loading reverse torque values were 26.0 +/- 0.30 Ncm (ready-made abutment; Transfer abutment) and 26.3 +/- 0.32 Ncm (CAD-CAM custom-made abutment; CustomFit abutment) and 24.7 +/- 0.67 Ncm (CAD-CAM custom-made abutment; Myplant). The domestically manufactured CAD-CAM custom-made abutment (Myplant abutment) presented lower pre-loading reverse torque value with statistically significant difference than that of the ready-made abutment (Transfer abutment) and CAD-CAM custom-made abutment (CustomFit abutment) manufactured from the same company (P=.027) and showed marginal gap in the fixture-abutment interface. CONCLUSION: Within the limitation of the present in-vitro study, in domestically manufactured CAD-CAM custom-made abutment (Myplant abutment) showed lower screw joint stability and fitness between fixture and abutment.
Computer-Aided Design* ; Torque

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 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

Cleft lip and palate is congenital deformity in oral and maxillofacial area. Normal soft palate has velopharyngeal closure action by connecting oral cavity and nasal cavity at rest and moving upward at swallowing and specific pronunciation. Cleft palate patients with velopharyngeal insufficiency have difficulty in mastication, swallowing and pronunciation because velopharyngeal closure is incomplete. At this time, a prosthetic device used to cover palate defects is called a palatal obturator. A palatal obturator separates oral cavity and nasal cavity and recovers pronunciation, mastication, swallowing and esthetic function. The purpose of this case study is to report the results because it reaches a satisfactory result in functional and esthetic aspects through functional impression procedures using modeling compound and tissue conditioner for restoration of a cleft palate patient with velopharyngeal insufficiency.
Cleft Lip ; Cleft Palate* ; Congenital Abnormalities ; Deglutition ; Humans ; Mastication ; Mouth ; Nasal Cavity ; Palatal Obturators* ; Palate ; Palate, Soft ; Velopharyngeal Insufficiency*

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: 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

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