• The Journal of Advanced Prosthodontics
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• v.13 no.3
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• pp.160-171
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• 2021

Purpose. This in-vitro study evaluated and compared the color stability of 3D-printed and conventional heat-polymerized acrylic resins following aging, mechanical brushing, and immersion in staining medium. Materials and methods. Forty disc-shaped specimens (10 mm in diameter and 3 mm thick) were prepared from two 3D-printed [DentaBASE (DB) and Denture 3D+ (D3D)] and one conventional polymethylmethacrylate (PMMA) denture materials. The specimens were thermo-cycled, subjected to mechanical brushing, and were immersed in either coffee, lemon juice, coke, or artificial saliva (AS) to simulate one and two years of oral use. Color measurements of the specimens were recorded by a spectrophotometer at baseline (T0), and after one (T1) and two years (T2) of simulation. The color changes (ΔE) were determined and also quantified according to the National Bureau of Standards (NBS) units. Descriptive statistics, followed by factorial ANOVA and Bonferroni post-hoc test (α=.05), were applied for data analysis. Results. The independent factors, namely material, staining medium, and immersion time, and interaction among these factors significantly influenced ΔE (P<.009). Irrespective of the materials, treatments, and time, the highest and the lowest mean ΔEs were observed for PMMA in lemon juice (4.58 ± 1.30) and DB in AS (0.41 ± 0.18), respectively. Regarding the material type, PMMA demonstrated the highest mean ΔE (2.31 ± 1.37), followed by D3D (1.67 ± 0.66), and DB (0.85 ± 0.52), and the difference in ΔE between the materials were statistically significant (P<.001). All the specimens demonstrated a decreased color changes at T2 compared to T1, and this difference in mean ΔE was statistically significant (P<.001). Conclusion. The color changes of 3D-printed denture resins were low compared to conventional heat polymerized PMMA. All the tested materials, irrespective of the staining medium used, demonstrated a significant decrease in ΔE values over time.

• Journal of Korean society of Dental Hygiene
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• v.9 no.1
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• pp.153-168
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• 2009

This study was executed to find out the outcome of Incremental Dental Care from September to November, 2004. 40 visitors to oral health center were examined on the oral conditions every week, seven times during above-mentioned period. Various tests were practiced in order to check their oral conditions before and after IDC such as tooth-brushing method/frequency/duration, calculus index, PHP index, halitosis and dental caries activity. Question and answer sheets were presented to student dental hygienists and 40 visitors respectively after IDC program. Results obtained are as follows. 1. Rotation method of toothbrushing increased from 27.8% to 88.9%. for men and increased from 27.3% to 95% for women. 2. Toothbrushing frequency increased from 2.8 times to 3.0 times a day for men and increased from 2.6 times to 3.1 times for women. Toothbrushing duration increased from 2.3 minutes to 2.8 minutes for men and increased from 2.1 minutes to 2.9 minutes for women. 3. Calculus index reduced from 0.5 to 0.1 for men and reduced from 0.7 to 0 for women. PHP index reduced from 3.7 to 3.0 for men and reduced 3.2 to 1.7 for women. However, halitosis didn't mark any significant difference before and after IDC. 4. Saliva buffering capacity of medium plus showed no change for men(94.5%), however increased from 95.4% to 100% for women. Dental caries activity of medium plus in S.mutans reduced by 4.3 times(72.2% to 16.7%) for men and reduced by 2 times(36.4% to 18.1%) for women. LB test results reduced by 1.5 times(50% to 33.3%) for men and reduced by 2.5 times(50% to 18.1%) for women. Alban's test results reduced by 1.4 times(83.3% to 61.1%) for men and reduced by 1.2 times(81.8% to 68.2%) for women. 5. All participants including visitors and students realized the importance of IDC and expressed a great satisfaction with IDC program. In conclusion, it is considered very necessary that IDC program should be maintained and extended to whole country so as to enhance the peoples' oral health conditions.

• Journal of Technologic Dentistry
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• v.31 no.3
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• pp.47-58
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• 2009

Self-leadership means a person's ability to make his thought or behavior in a right way by controlling it himself. Strategies of the same leadership can be largely categorized into three, behavior focused, natural reward and constructive thought strategies. In this study, the foresaid styles of self-leadership strategy are discussed from the perspective of dental lab laboratories' business environment of Gyeongnam region. And accordingly, this researcher examined such strategy styles that dental lab managers, chief technicians and assistant technicians usually have. Results of the study can be summarized as follows. First, out of the self-leadership strategy styles, most remarkably found among the professional of dental technology was constructive thought strategy, followed by behavior-focused and natural reward strategies in order. In general, therefore, the professionals strongly tend to make their thoughts that can a positive effect on their work performance or in a constructive way. In other words, professional dental technicians are more likely to make efforts to persuade or persuade themselves to change their own unreasonable confidence or negative process in more positive way. Second, the extent to which constructive thought strategy is perceived was not different among dental lab managers, chief technicians and assistant technicians. While, behavior-focused and natural reward strategies were found most strongly perceived by dental lab managers, followed by chief and assistant technicians in order. This may be attributed to the fact that the higher professional dental technicians are in position, the higher they are in self-leadership, or in the ability to overcome crises by themselves and make their thought or behavior in a right way. Dental lab managers usually have lots of experiences in relation to behavior-focused or natural reward strategy. Therefore, they are very strongly capable of controlling themselves in order to overcome crises or make their thought or behavior in a right way. In contrast, assistant technicians are still having lots of trials and errors because they are less experienced and skilled. This suggests that chief technicians should make themselves fully capable as a medium that connects between dental lab managers and assistant technicians.

• Korean Journal of Cleft Lip And Palate
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• v.14 no.1_2
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• pp.37-44
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• 2011

Amniotic fluid is a complex and biological reservoir that provides mechanical cushioning and has many nutrients required for fetal growth and development. During our main research works about the fetal surgery of congenital facial defects, we reviewed several recent articles about the effectiveness and composition of amniotic fluid. Among these review processes, amniotic fluid, as the convenient medium to store sking grafts, was focused especially for its growth factors and rich nutrients, and we summarized some experimental investigations of skin grafts stored in amniotic fluid in rats. We reviewed mainly the article, "Turhan-haktanir N. et al. Histological assessment of skin grafts in amniotic fluid and saline. J Plast Surg Hand Surg 2010;44:226-30."

• Journal of Korean society of Dental Hygiene
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• v.8 no.4
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• pp.241-250
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• 2008

In this study, specimens such as tongue, supragingival and subgingival biofilm were taken from total 20 scaling subjects who visited the oral prophylaxis practice lab at department of dental hygienics, J Health College in order to observe bacterial distributions and morphology using scanning electron microscopy(sem). as a result, this study came to the following conclusions: 1. According to observation of tongue, supragingival and subgingival biofilm through sem, it is found that there are round colonies of gram-positive cocci and gram-negative bacilli on blood agar medium. 2. The observation of bacterial morphology on dental biofilm through sem, cocci in chain cocci in cluster and bacillus(rod) respectively. 3. For tongue biofilm, it is found that a variety of bacterial species are detected, such as Granulicatolla adiacens(1), Gemella morbillorum(3), Streptococcus mitis(2), Streptococcus sanguinis(1), Aerococcus viridans (2), Streptococcus equinus(1), Leuconostoc spp.(1), Gemella haemolysans (1) and Lactococcus lactis spp.(1) respectively. 4. For supragingival biofilm, it is found that a variety of bacterial species detected, such as Aerococcus viridans(1), Gemella haemolysans(2), Leuconostoc spp.(2), Gemella morbillorum(1) and Pseudomonas fluoescens (1) respectively. 5. For subgingival biofilm, it is found that a variety of bacterial species detected, such as Leuconostoc spp.(1), Staphylococcus lugdunensis(1) and Streptococcus salivarius(1) respectively.

• Journal of dental hygiene science
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• v.23 no.1
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• pp.51-59
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• 2023

Background: Tea tree oil has antiviral, antimicrobial and antifungal effects and Mastic oil has antifungal and anticancer effects. For synergistic effects of oils, blending oil containing a mixture of two to three oils is recommended. This study aimed to determine the antibacterial effects of Tea tree oil, Mastic oil, and Blending oil containing the two oils in a mixture, to verify and suggest the potential use of these oils as a substance to prevent dental caries. Methods: Tea tree oil, Mastic oil, and Blending oil with a 1:1 blend of the two oils were diluted in liquid medium to 0% (negative control), 0.5%, 1.0%, and 2.0%. Streptococcus mutans was applied to each experimental group of the three diluted oils and after 8 h culture, the optical density (OD) was measured and the growth inhibition rate for S. mutans was estimated. Results: Tea tree oil had significantly low OD values across all concentrations (p<0.05) without significant variation among different concentrations (p>0.05). Mastic oil did not significantly vary in OD compared to the negative control across all concentrations (p>0.05) without significant variation among different concentrations (p>0.05). Blending oil, compared to the negative control, did not significantly vary in OD at 0.5% (p>0.05) but significant variation was found as the concentration increased (p<0.05). Additionally, for Tea tree oil and Mastic oil, the growth inhibition rate showed no significant variation according to concentration (p>0.05), whereas for Blending oil, the growth inhibition rate for S. mutans showed a significant difference at 1.0% (p<0.05) and at higher concentrations. Conclusion: Blending oil containing a Tea tree oil and Mastic oil demonstrated a significant growth inhibition effect on S. mutans from the concentration of 1.0%, which suggested its potential use as an effective antibacterial agent for dental caries.

• Restorative Dentistry and Endodontics
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• v.15 no.1
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• pp.129-139
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• 1990

In order to determine if GK-101E(N-monochloro-DL-2-aminobutyrate) solution was effective in the removal of carious dentin, this study was conducted on 75 extracted human carious teeth. GK-101E solution was compared in effectiveness to saline solution.75 extracted human carious teeth were randomly assigned to two groups accordingly : (1) 50 teeth were treated with GK-101E solution : and (2) 25 teeth were treated with saline solution. Teeth in each group were divided into the medium or medium-hard consistency. Treatment consisted of directing the pulsating stream of each coded test solution utilizing the Caridex$^{TM}$ Caries Removal System against the carious surface for 4 mimutes. One operator treated all teeth with corded solution, and four investigators scored on the treated teeth based on visual examination and tactile evaluation with a dental explorer in conjunction with staining method with Caries Detector$^{TM}$ The results were as follows : 1. All groups showed various effect of carious dentin removal. 2. GK-101E solution was statistically superior to physiologic saline solution in the removal of carious dentin, regardless of carious consistency. 3. GK-101E solution in the medium-hard consistency was statistically superior to that in the medium consistency in the caries removal(p=0.001). 4. Saline solution in the medium consistency was equivalent to that in the medium-hard consistency in caries removal(p>0.1).

• Journal of Korean Academy of Oral Health
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• v.42 no.4
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• pp.210-215
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• 2018

Objectives: The main objectives of this study were to verify the antibacterial activity of two essential oils, lavender and peppermint, against dental caries and to review their synergistic effect when used in combination. Our results provide basic data for the evaluation of the use of these two substances towards the prevention and cure of dental caries. Methods: The sample solutions of lavender and peppermint oils were prepared in three different concentrations (30%, 50%, and 70% (v/v)) by diluting them with third-distilled water and Tween 20. Streptococcus mutans was selected as the bacterial species for testing. The disk diffusion method was used to measure the antibacterial activity of the sample solutions. For generating growth curves and measuring the number of clusters of the bacterial, the liquid medium-dilution method was used; the absorbance of the medium was measured at 600 nm after 3, 6, 12 and 24 hours. Results: When the antibacterial activity of the oils was tested via the disk diffusion method, the activity improved with increasing concentrations of all the sample solutions of peppermint, lavender, and the blend, but there was no significant difference between them with respect to the type of oil. In the growth curves of S. mutans, growth inhibition was observed after 12 hours. The inhibitory effect of 30% lavender oil on growth was 64.9% and 80.1% after 12 and 24 hours of treatment, respectively whereas that of peppermint oil was 71.3% and 80.1% after 12 and 24 hours of treatment, respectively. The inhibitory effect of the blended oil was 71.9% and 81.0% after 12 and 24 hours of treatment, respectively. Conclusions: Further research is still required in order to determine the efficacy of lavender and peppermint oils, as well as other essential oils, for wider use in preventing dental caries.

• Restorative Dentistry and Endodontics
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• v.48 no.2
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• pp.12.1-12.11
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• 2023

Objectives: The present study evaluated the pulp response of human mandibular incisors subjected to in-office dental bleaching using gels with medium or high concentrations of hydrogen peroxide (HP). Materials and Methods: The following groups were compared: 35% HP (HP35; n = 5) or 20% HP (HP20; n = 4). In the control group (CONT; n = 2), no dental bleaching was performed. The color change (CC) was registered at baseline and after 2 days using the Vita Classical shade guide. Tooth sensitivity (TS) was also recorded for 2 days post-bleaching. The teeth were extracted 2 days after the clinical procedure and subjected to histological analysis. The CC and overall scores for histological evaluation were evaluated by the Kruskal-Wallis and Mann-Whitney tests. The percentage of patients with TS was evaluated by the Fisher exact test (α = 0.05). Results: The CC and TS of the HP35 group were significantly higher than those of the CONT group (p < 0.05) and the HP20 group showed an intermediate response, without significant differences from either the HP35 or CONT group (p > 0.05). In both experimental groups, the coronal pulp tissue exhibited partial necrosis associated with tertiary dentin deposition. Overall, the subjacent pulp tissue exhibited a mild inflammatory response. Conclusions: In-office bleaching therapies using bleaching gels with 20% or 35% HP caused similar pulp damage to the mandibular incisors, characterized by partial necrosis, tertiary dentin deposition, and mild inflammation.

• The Journal of Advanced Prosthodontics
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• v.16 no.2
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• pp.77-90
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• 2024

PURPOSE. The study aims to investigate the influence of the ferrule effect and types of posts on the stress distribution in three morphological types of the maxillary central incisor. MATERIALS AND METHODS. Nine models were created for 3 maxillary central incisor morphology types: "Fat" type - crown 12.5 mm, root 13 mm, and buccolingual cervical diameter 7.5 mm, "Medium" type - crown 11 mm, root 14 mm, and buccolingual cervical diameter 6.5 mm, and "Slim" type - crown 9.5 mm, root 15 mm, and buccolingual cervical diameter 5.5 mm. Each model received an anatomical castable post-and-core or glass-fiber post with resin composite core and three ferrule heights (nonexistent, 1 mm, and 2 mm). Then, a load of 14 N was applied at the cingulum with a 45° slope to the long axis of the tooth. The Maximum Principal Stress and the Minimum Principal Stress were calculated in the root dentin, crown, and core. RESULTS. Higher tensile and compression stress values were observed in root dentin using the metallic post compared to the fiber post, being higher in the slim type maxillary central incisor than in the medium and fat types. Concerning the three anatomical types of maxillary central incisors, the slim type without ferrule height in mm presented the highest tensile stress in the dentin, for both types of metal and fiber posts. CONCLUSION. Post system and tooth morphology were able to modify the biomechanical response of restored endodontically-treated incisors, showing the importance of personalized dental treatment for each case.