• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.1
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• pp.72-81
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• 2017

The aim of this study was to evaluate the effectiveness of artificial saliva contamination and decontamination procedures at different stages of a bonding procedure on the microtensile bond strength (MTBS) of two one-step self-etch adhesives and a two-step total-etch adhesive to dentin of primary teeth. Forty-two extracted sound primary molars were randomly divided into three groups depending on three adhesives, Scotchbond Universal Adhesive (SBU), All-Bond Universal (ABU) and Prime & Bond NT (PNT). For each adhesive, the teeth were allocated into seven groups. Except for control group, group 1, the groups were contaminated with artificial saliva at three different stages: the groups 2 and 3 - before adhesive application; the groups 4 and 5 - before adhesive polymerization; the groups 6 and 7 - after adhesive polymerization. Decontaminating procedures were rinsing, air-drying (group 2, 4, 6) and air-drying (group 3, 5, 7). The specimens were restored with composite resin (Filtek, Z350) and microtensile bond strength was measured. The data was analyzed with one-way ANOVA and Tukey HSD test (p < 0.05). In the control group, using PNT resulted in significantly higher bond strength than when ABU and SBU were used (p < 0.001). For three adhesives, the groups 2, 4 and 6 had greater bond strength than the groups 3, 5 and 7. Also, when the artificial saliva was contaminated before adhesive polymerization (group 4, 5), it showed a significantly lower bond strength. Generally the two-step total-etch adhesive generated a higher bond strength than the one-step self-etch adhesive. Artificial saliva contamination before adhesive polymerization led to a drastic decrease in bond strength, and rinsing with water followed by air-drying could not recover the bond strength.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.1
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• pp.37-44
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• 2013

Sodium hypochlorite and ethylene diamine tetra acetic acid are substances usually used during endodontic treatment. Several studies found that the bonding was negated with certain irrigants and some of the used irrigants have demineralizing and chealating effects, so it was advocated to omit the etching step in etch and rinse adhesive systems. The purpose of this in vitro study was to evaluate the influence of NaOCl & EDTA on the bonding strength of ethanol wet bonding. Thirty human molars were selected and mesiodistally sectioned into halves, thus providing sixty specimens. The specimens were randomly assigned to 4 groups(n=15) according to the irrigant regimen used : (1) irrigated with distilled water for 10min (control); (2) irrigated with 5.25% NaOCl(10min), flushed with 5.25% NaOCl(1min) (3) irrigated with 5.25% NaOCl, flushed with 17% EDTA (4) irrigated with 5.25% NaOCl, flushed with 17% EDTA. Each group was acid-etched with 37% phosphoric acid(except group 4) and had their dentin surfaces dehydrated with ethanol solutions : 50%, 70%, 80%, 95%, 3x100%, 30s for each application. After dehydration, a primer( 50% all bond 3 resin + 50% ethanol) was used, followed by the adhesive(ALL-BOND 3 RESIN) application. Resin composite build-ups were then prepared using an incremental technique. Specimens were sectioned into beams and submitted to a tensile load using a Micro Tensile Tester(Bisco Inc.). The data were statistically analyzed using one-way ANOVA and Tukey HSD at p<0.5 level. There was no significant difference on G1(control) and G2(irrigated with NaOCl only ). (p>0.05). G3(flushed with EDTA) showed significantly high tensile bonding strength compared to the G2 (p<0.05). G4( treated with EDTA but no acid-etching) was significantly lower value than G3. (p<0.05) Although there was no significant difference, 5.25% NaOCl seemed to have an adverse effect on the bonding strength of ethanol wet bonding. The flushing with EDTA after NaOCl irrigation prevents the decrease of bonding strength. The use of 17% EDTA as a final flush can enhance the bonding strength but EDTA flushing can't substitute for a acid-etching.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.70-79
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• 2020

Purpose: The purpose of this study was to evaluate the effect of attachments and palatal coverage on stress distribution in maxillary implant overdenture using finite element analysis. Materials and Methods: Four maxillary overdenture 3-D models with four implants placed in the anterior region were fabricated with computer-aided design. 1) Ball-F: Non-splinted ball attachment and full palatal coverage, 2) Ball-P: Non-splinted ball attachment and U-shaped partial palatal coverage, 3) Bar-F: Splinted milled bar attachment and full palatal coverage, 4) Bar-P: Splinted milled bar attachment and U-shaped partial palatal coverage. Stress distribution analysis was performed with ANSYS workbench 14. 100 N vertical load was applied at the right first molar unilaterally and maximum stress was calculated at the implant, peri-implant bone and mucosa. Results: The use of the ball attachment showed lower maximum stress on implant and peri-implant bone than the use of the milled bar attachment. But it showed contrary tendency in the mucosa. Regardless of attachment, full palatal coverage showed lower maximum stress on implant, peri-implant bone and mucosa. Conclusion: Within the limitation of this study, ball attachment improved stress distribution on implant and peri-implant bone rather than milled bar attachment in maxillary implant overdenture. Also, full palatal coverage is more favorable in stress distribution.

• Restorative Dentistry and Endodontics
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• v.36 no.3
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• pp.188-195
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• 2011

Objectives: The purpose of this study was to evaluate the polymerization shrinkage stress among conventional methacrylate-based composite resins and a silorane-based composite resin. Materials and Methods: The strain gauge method was used for the determination of polymerization shrinkage strain. Specimens were divided by 3 groups according to various composite materials. Filtek Z-250 (3M ESPE) and Filtek P-60 (3M ESPE) were used as a conventional methacrylate-based composites and Filtek P-90 (3M ESPE) was used as a silorane-based composites. Measurements were recorded at each 1 second for the total of 800 seconds including the periods of light application. The results of polymerization shrinkage stress were statistically analyzed using One way ANOVA and Tukey test (p = 0.05). Results: The polymerization shrinkage stress of a silorane-based composite resin was lower than those of conventional methacrylate-based composite resins (p < 0.05). The shrinkage stress between methacrylate-based composite resin groups did not show significant difference (p > 0.05). Conclusions: Within the limitation of this study, silorane-based composites showed lower polymerization shrinkage stress than methacrylate-based composites. We need to investigate more into polymerization shrinkage stress with regard to elastic modulus of silorane-based composites for the precise result.

• The korean journal of orthodontics
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• v.31 no.3 s.86
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• pp.381-391
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• 2001

In orthodontic patients, frequently, amalgam restorations are present on the buccal surface of molars. The ability to successfully bond orthodontic brackets and buccal tubes to amalgam restorations would therefore be of clinical value. But the bond strength to total amalgam surface is probably not critical in most instances. Because there is usually a considerable amount of sound enamel surrounding a buccal amalgam filling. The purpose of this study was to evaluate the bond strengths of orthodontic brackets according to surface treatments and size of amalgam restorations. Eighty tooth specimen were assigned to four groups according to amalgam size-1.5mm, 2.0mm, 2.5mm, 3.0mm diameter-and then divided into two groups : one half was sandblasting group the other half was no sandblasting group. After Bracket bonding, shear bond strength for each specimen was determined and bond failure patterns was evaluated. 1. Shear bond strength of amalgam size 1.5mm group was significantly higher than that of the other groups. (p<0.05) 2. There was no significant difference in the bond strength produced by sandblasting. (p<0.05) 3. Shear bond strength of G and H group of which amalgam restoration ratio to the bracket base sizes were $61\%$ were significantly decreased $50-60\% level of that of control group. (p<0.05) 4. There was positive correlation between sandblasting and mARI. (p<0.05) The results of the present study indicate that it may be feasible to bond orthodontic bracket clinically successfully to amalgam restoration with conventional orthodontic resin when its size is less than $50\%$ of that of bracket base.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.53-60
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• 2009

Statement of problem: At present, as the esthetic demands are on the increase, there are many ongoing studies for tooth-colored post and cores. Most of them are about fiber post and prefabricated zirconia post, but few about one-piece milled zirconia post and core using CAD/CAM (computer-aided design/computer-aided manufacturing) technique. Purpose: The objective of this study was to compare microleakage of endodontically treated teeth restored with three different tooth-colored post and cores. Material and methods: Extracted 27 human maxillary incisors were cut at the cementoenamel junction, and the teeth were endodontically treated. Teeth were divided into 3 groups (n=9); restored with fiber post and resin core, prefabricated zirconia post and heat-pressed ceramic core, and CAD/CAM milled zirconia post and core. After the preparation of post space, each post was cemented with dual-polymerized resin cement (Variolink II). Teeth were thermocycled for 1000 cycles between $5-55^{\circ}C$ and dyed in 2% methylene blue at $37^{\circ}C$ for 24 hours. Teeth were sectioned (bucco-lingual), kept the record of microleakage and then image-analyzed using a microscope and computer program. The data were analyzed by one-way ANOVA and Scheffe's multiple range test (${\alpha}=0.05$). Results: All groups showed microleakage and there were no significant differences among the groups (P>.05). Prefabricated zirconia post and heat-pressed ceramic core showed more leakage in dye penetration at the post-tooth margin, but there was little microleakage at the end of the post. Fiber post and resin core group and CAD/CAM milled zirconia post and core group indicated similar microleakage score in each stage. Conclusion: Prefabricated zirconia post and heat-pressed ceramic core group demonstrated better resistance to leakage, and fiber post and resin core group and CAD/CAM milled zirconia post and core group showed the similar patterns. The ANOVA test didn't indicate significant differences in microleakage among test groups. (P>.05)

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.82-90
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• 2009

Statement of problem: Recently, as patients' expectation and interest for esthetics are increasing, concerns of esthetic restoration for removable dentures as well as fixed prosthodontics are also increasing. And the color stability of artificial teeth will affect a long term success rate of the denture. But the stain or discoloration of these artificial teeth as well as denture resin has caused esthetic problem. Purpose: This study was designed to evaluate the influence on color stability of artificial teeth when soy sauce, red pepper paste and coffee which many Koreans have eaten were applied. Material and methods: For artificial teeth type(Endura $Anterio^{(R)}$, Physio $Duracross^{(R)}$, Trubyte $Biotone^{(R)}$) selected for the study, 10 specimens each were soaked into individual beakers of soy sauce, red pepper paste, coffee and distilled water. And $L^*$, $a^*$, $b^*$ value were measured for evaluation of the color difference (${\Delta}E^*$) with spectrophotometer on the 1 day, 1 week, 2 weeks, 4 weeks and 8 weeks after immersion. Results: 1. ${\Delta}E^*$ value of artificial teeth which were soaked in soy sauce and coffee was various according to soaking periods. However there was significant difference between Trubyte $Biotone^{(R)}$ and Physio $Duracross^{(R)}$ in red pepper paste regardless of soaking period(P<.05). 2. Except for 8 weeks of Endura $Anterio^{(R)}$, 4 weeks and 8 weeks of Physio $Duracross^{(R)}$, artificial teeth soaked in red pepper paste regardless of the type had significant difference of ${\Delta}E^*$ value compared with other groups (P<.05). 3. $a^*$, $b^*$ value of Endura $Anterio^{(R)}$ and Trubyte $Biotone^{(R)}$ which were soaked in red pepper paste had significant difference compared with the value of other group(P<.05). Conclusion: Red pepper paste had the greatest effect on color difference of artificial tooth. Physio $Duracross^{(R)}$ showed relatively less color difference than Trubyte $Biotone^{(R)}$ and Endura $Anterio^{(R)}$. But as ${\Delta}E^*$ difference were all less than 3.3, these artificial resin teeth seemed appropriate for clinical use.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.455-469
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• 2008

Statement of problems: In the area of dental care, the institutionalized elderly have placed the most vulnerable state, and we cannot find their subjective need of dental treatment because of the physical and mental disabilities, But we have no basic investigation of their oral health conditions. Purpose: The aims of the current study were to investigate the oral health status of institutionalized elderly patients who are in the least benefited side of dental service, and to analyze their dental treatment needs. Material and methods: The survey of the oral status was carried out on 758 institutionalized elderly, and 212 elderly who was more than 65 years old from D dental office, and it was based on the Guidelines of Oral Health Research of year 2000 in Republic of Korea. Results and conclusion: The DMFT index of the institutionalized elderly appeared higher than that of the same ages in control group, and it increased with age. The number of residual teeth of the institutionalized elderly appeared lower than that of the same ages in control group, and it decreased with age (P < .05). The number of fixed partial denture in institutionalized elderly was lower than that of the same ages in control group (P < .05). The percentage wearing removable partial denture was not significant between the elderly in institutions and the control group, and was not different according to age between the two groups. The percentage of institutionalized elderly wearing complete denture appeared lower than that of the same ages in control group, and it increased with age. The percentage of institutionalized elderly needing complete denture was higher than that of control group, and the percentage of elderly needing complete denture on the maxilla was higher than that of the mandible. 16.35% of the institutionalized elderly was living without denture in spite of their fully edentulous state. The need for complete denture increased rapidly with age. The number of valued teeth and dental prostheses in shortened dental arch concept and number of occluding pairs of teeth of institutionalized elderly were lower than that of the control group (P < .05). In institutionalized elderly, the number of residual teeth, the number of fixed partial dentures, and the percentage wearing removable partial dentures were higher in the mandible, and the percentage wearing complete dentures was higher in the maxilla (P < .05). The rate of institutionalized elderly needing prosthodontic treatment appeared to be 67.82%, where the number of occluding pairs of teeth was less than 10. When it is difficult to evaluate the subjective need of dental treatment as with the institutionalized elderly, estimation using the number of occluding pairs of teeth can be a useful indicator that can project treatment needs. For the oral health care of institutionalized elderly, it is essential to increase the awareness of nurses and caregivers who take care of them, about the importance of the oral health. Since the average life span and number of residual teeth are increasing gradually, the welfare policy should be changed to implementing regular dental examinations, preservative treatment forms and oral health control of dentulous patients where the traveling-treatment system and visit system are supplemented. And principles should be set that the present denture project of edentulous patients should be done by specialists who'll also be responsible for postmanagement. Through this research of institutionalized elderly, the oral health status which is worsened by aging could be confirmed. And the interest and positive participation of dental society on the elderly should come first in order to solve the rising treatment needs of the elderly patients.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.2
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• pp.292-299
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• 2000

The purpose of this study was to investigate parental knowledge and attitude and practices relating to infant oral health care and to promote their motivations to their children's oral health care. Authors interviewed 350 persons in Ilwon-Dong and whose children were between 0 to 36 months old and acquired questionnaire from them. The questionnaire constituted of questions about general knowledge of tooth eruption, methods of oral hygiene care, and opinions about preventive dental visit. The collected data were analysed and compared with other researches. The important results obtained from this study were : 1. Females and highly educated persons had more dental knowledge than males and poorly educated persons. But age and economic status did not affect their level of dental knowledge. 2. Fifty nine percents of respondents thought that tooth began to be formed before birth. 3. Seventy six percents of respondents thought that infant oral health care should begin before tooth eruption, but actually only 63% started oral hygiene care before age one. 4. Seventy percents of respondents used gauze for infant oral care. 5. Fifty seven percents of respondents still gave bottles to their children after they reached age one or more and 55% of respondents never heard of nursing caries. 6. Ninety percents of respondents agreed that carious deciduous teeth need restorations, and 31% of respondents thought that age two is the appropriate time for the first dental visit. 7. Forty seven percents of parents did not think that dental caries is an infectious disease. 8. Only Thirty three percents of parents visited dental clinics for examination and prevention during pregnancy and only 11% of expecting parents were offered dental health care education in pediatric or obstetrician clincs. 9. Information about oral health care was mostly given from baby megazines. 10. Overall parental knowledge about infant oral health care was not sufficient to maintain appropriate dental care for infants.

• Restorative Dentistry and Endodontics
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• v.36 no.5
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• pp.425-430
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• 2011

Objectives: This in vitro study investigated whether short-term application of calcium hydroxide in the root canal system for 1 and 4 wk affects the fracture strength of human permanent teeth. Materials and Methods: Thirty two mature human single rooted mandibular premolars in similar size and dentin thickness without decay or restorations were hand and rotary instrumented and 16 teeth vertically packed with calcium hydroxide paste and sealed coronally with caviton to imitate the endodontic procedure and the other 16 teeth was left empty as a control group. The apicies of all the samples were sealed with resin, submerged in normal saline and put in a storage box at $37^{\circ}C$ to mimic the oral environment. After 1 and 4 wk, 8 samples out of 16 samples from each group were removed from the storage box and fracture strength test was performed. The maximum load required to fracture the samples was recorded and data were analysed statistically by the two way ANOVA test at 5% significance level. Results: The mean fracture strengths of two groups after 1 wk and 4 wk were similar. The intracanal placement of calcium hydroxide weakened the fracture strength of teeth by 8.2% after 4 wk: an average of 39.23 MPa for no treatment group and 36.01 MPa for CH group. However there was no statistically significant difference between experimental groups and between time intervals. Conclusions: These results suggest that short term calcium hydroxide application is available during endodontic treatment.