• The Journal of Advanced Prosthodontics
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• 제12권3호
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• pp.140-149
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• 2020

PURPOSE. This study evaluated the color stabilities of two computer-aided design and computer-aided manufacturing (CAD/CAM) blocks and a nanofill composite resin and the microtensile bond strength (µTBS) between the materials. MATERIALS AND METHODS. Twelve specimens of 4 mm height were prepared for both Lava Ultimate (L) and Vita Enamic (E) CAD/CAM blocks. Half of the specimens were thermocycled (10,000 cycle, 5° to 55℃) for each material. Both thermocycled and non-thermocycled specimens were surface treated with one of the three different methods (Er,Cr:YSGG laser, bur, or control). For each surface treatment group, one of the thermocycled and one of non-thermocycled specimens were restored using silane (Ceramic Primer II), universal adhesive (Single Bond Universal), and nanofill composite resin of 4-mm height (Filtek Ultimate). The other specimens were restored with the same procedure without using silane. For each group, 1 × 1 × 8 mm bar specimens were prepared using a microcutting device. Bar specimens were thermocycled (10,000 cycle, 5° to 55℃) and microtensile tests were performed. Staining of the materials in coffee solution was also compared using a spectrophotometer. Data were analyzed using one-way ANOVA, t-test and post-hoc Scheffe tests. RESULTS. µTBS were found similar between the thermocycled and non-thermocycled groups (P>.05). The highest µTBS (20.818 MPa) was found in the non-thermocycled, bur-ground, silane-applied E group. Silane increased µTBS at some E groups (P<.05). Composite resin specimens showed more staining than CAD/CAM blocks (P<.05). CONCLUSION. CAD/CAM blocks can be repaired with composite resins after proper surface treatments. Using silane is recommended in repair process. Color differences may be shown between CAD/CAM blocks and the nanofill composite after a certain time period.

• 대한치과교정학회지
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• 제46권2호
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• pp.104-110
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• 2016

Objective: Traditional retainers (both metal and fiber-reinforced composite [FRC]) have limitations, and a retainer made from more flexible ligature wires might be advantageous. We aimed to compare an experimental design with two traditional retainers. Methods: In this prospective preliminary clinical trial, 150 post-treatment patients were enrolled and randomly divided into three groups of 50 patients each to receive mandibular canine-to-canine retainers made of FRC, flexible spiral wire (FSW), and twisted wire (TW). The patients were monitored monthly. The time at which the first signs of breakage/debonding were detected was recorded. The success rates of the retainers were compared using chi-squared, Kaplan-Meier, and Cox proportional-hazard regression analyses (${\alpha}=0.05$). Results: In total, 42 patients in the FRC group, 41 in the FSW group, and 45 in the TW group completed the study. The 2-year failure rates were 35.7% in the FRC group, 26.8% in the FSW group, and 17.8% in the TW group. These rates differed insignificantly (chi-squared p = 0.167). According to the Kaplan-Meier analysis, failure occurred at 19.95 months in the FRC group, 21.37 months in the FSW group, and 22.36 months in the TW group. The differences between the survival rates in the three groups were not significant (Cox regression p = 0.146). Conclusions: Although the failure rate of the experimental retainer was two times lower than that of the FRC retainer, the difference was not statistically significant. The experimental TW retainer was successful, and larger studies are warranted to verify these results.

• Restorative Dentistry and Endodontics
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• 제45권1호
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• pp.1.1-1.9
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• 2020

Objectives: The purpose of this study was to determine the incidence of radix molaris (RM) (entomolaris and paramolaris) in the mandibular first permanent molars of a sample Saudi Arabian subpopulation using cone-beam computed tomography (CBCT). Materials and Methods: A total of 884 CBCT images of 427 male and 457 female Saudi citizens (age 16 to 70 years) were collected from the radiology department archives of 4 dental centers. A total of 450 CBCT images of 741 mature mandibular first molars that met the inclusion criteria were reviewed. The images were viewed at high resolution by 3 examiners and were analyzed with Planmeca Romexis software (version 5.2). Results: Thirty-three (4.5%) mandibular first permanent molars had RM, mostly on the distal side. The incidence of radix entomolaris (EM) was 4.3%, while that of radix paramolaris was 0.3%. The RM roots had one canal and occurred more unilaterally. No significant difference in root configuration was found between males and females (p > 0.05). Types I and III EM root canal configurations were most common, while type B was the only RP configuration observed. Conclusions: The incidence of RM in the mandibular first molars of this Saudi subpopulation was 4.5%. Identification of the supernumerary root can avoid missing the canal associated with the root during root canal treatment.

• The Journal of Advanced Prosthodontics
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• 제6권3호
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• pp.165-170
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• 2014

PURPOSE. This study was aimed to evaluate effect of the desensitizing pretreatments on the micro-tensile bond strengths (${\mu}TBS$) to eroded dentin and sound dentin. MATERIALS AND METHODS. Forty-two extracted molars were prepared to form a flat dentin surface, and then they were divided into two groups. Group I was stored in distilled water while group II was subjected to a pH cycling. Each group was then subdivided into three subgroups according to desensitizing pretreatment used: a) pretreatment with desensitizer (Gluma); b) pretreatment with $CO_2$ Laser (Ultra Dream Pluse); c) without any pretreatment. All prepared surfaces were bonded with Single Bond 2 and built up with resin composite (Filtek Z250). The micro-tensile bond test was performed. Fracture modes were evaluated by stereomicroscopy. Pretreated surfaces and bonded interfaces were characterized by scanning electron microscope (SEM). The data obtained was analyzed by two-way ANOVA (${\alpha}$=0.05). RESULTS. For both sound and eroded dentin, samples treated with desensitizer showed the greatest ${\mu}TBS$, followed by samples without any treatment. And samples treated with $CO_2$ laser showed the lowest ${\mu}TBS$. SEM study indicated that teeth with eroded dentin appeared prone to debonding, as demonstrated by existence of large gaps between adhesive layers and dentin. CONCLUSION. Pretreatment with Gluma increased the ${\mu}TBS$ of Single Bond 2 for eroded and sound teeth. $CO_2$ laser irradiation weakened bond performance for sound teeth but had no effect on eroded teeth.

• Restorative Dentistry and Endodontics
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• 제22권2호
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• pp.739-750
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• 1997

Treatment of root perforation elicits special considerations due to its blood-contaminated circumstances. It is known that conventional dental restorative materials are all leaking. Calcium sulfate is the material which react with water to become chemically set. This study, therefore, was performed to develop a new compound containing calcium sulfate and to evaluate its physical and biological characteristics. Three materials were used, IRM, calcium sulfate, calcium sulfate-hydroxyapatite compound. The composition of the calcium sulfate-hydroxyapatite compound was basically 50 % of calcium sulfate and 50 % of hydroxyapatite mixed with guajacol. The materials were mixed in conventional way and underwent four physical test procedures, setting time, solubility test, compressive strength, and marginal leakage test. All materials were evaluated under the scanning electron microscope to examine the marginal sealing ability. Animal experiment was also performed to test the materials' tissue response. Twenty-four dog's premolars were tested with either furcation perforations or apical retro-fillings. From the results, we found that calcium sulfate possess the good marginal sealing ability. However, calcium sulfate creates many voids which is caused by crystal thrusting action when it reacts with water. It seemed that the voids caused disintegration of the material which eventually lead to tissue reaction. By compounding calcium sulfate and hydroxyapatite, we were able to obtain the better physical properties but it showed larger marginal gap between the material and the root surface. Within the six weeks observation period, both IRM and calcium sulfate-hydroxyapatite compound showed good tissue responses in animal experiment. It is concluded that calcium sulfate would be the material of choice in root perforation repair, but the physical property needs to be further improved.

• Restorative Dentistry and Endodontics
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• 제45권3호
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• pp.28.1-28.13
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• 2020

Objectives: To evaluate the outcome of in vitro studies comparing the effectiveness of QMix irrigant in removing the smear layer in the root canal system compared with other irrigants. Materials and Methods: The research question was developed by using Population, Intervention, Comparison, Outcome and Study design framework. Literature search was performed using 3 electronic databases PubMed, Scopus, and EBSCOhost until October 2019. Two reviewers were independently involved in the selection of the articles and data extraction process. Risk of bias of the studies was independently appraised using revised Cochrane Risk of Bias tool (RoB 2.0) based on 5 domains. Results: Thirteen studies fulfilled the selection criteria. The overall risk of bias was moderate. QMix was found to have better smear layer removal ability than mixture of tetracycline isonomer, an acid and a detergent (MTAD), sodium hypochlorite (NaOCl), and phytic acid. The efficacy was less effective than 7% maleic acid and 10% citric acid. No conclusive results could be drawn between QMix and 17% ethylenediaminetetraacetic acid due to conflicting results. QMix was more effective when used for 3 minutes than 1 minute. Conclusions: QMix has better smear layer removal ability compared to MTAD, NaOCl, Tubulicid Plus, and Phytic acid. In order to remove the smear layer more effectively with QMix, it is recommended to use it for a longer duration.

• Restorative Dentistry and Endodontics
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• 제6권1호
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• pp.109-114
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• 1980

Ease of manipulation, adequate mechanical properties, long years of experience and economical cost are the factors which have established amalgam as the most widely used material for dental restorations. But amalgam restoration may require replacement because of secondary caries, fracture, "fall-out", dimensional change, tarnish or corrosion etc.. These failures of amalgam restorations seem to arise from failures during operations rather than from the inherent shortcomings of the material itself or of the patient's mismanagement. It is anticipated that notonly number of analgam restoration, but failures will be increase after more extensive utilization of the medical insurance which began in 1977. Then authors think that it would be helpful for the development of better treatment in daily dental practice, to know the duration of amalgam restorations and the reasons for their replacement. The data for this survey was compiled from 2, 856 out-patients of the Department of Dentistry, Ewha Woman's University Hospital from January 1975 to December 1977. 260 cases among 1,718 fillings were studied, of which 205 cases both had a single reason for replacement and recognized the date of the previous filling. The results obtained were as follows; 1. Amalgam fillings were 58. 5 percent of all dental restorative materials. Of these, 15. 13 percent of the amalgam restorations had to be replaced. 2. The first reason for replacement of amalgam restorations was secondary caries (56.10%), the second was fracture (23.80%) and the third was "fall-out" (8.78%). 3. Among those amalgms requiring replacement, 52.2 percent had been in place less than 3 years, 70.7 percent within 5 years and 89.8 percent had been in place less than 10 years. Only 10.2 percent had been in place more than 10 years.

• Restorative Dentistry and Endodontics
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• 제43권4호
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• pp.36.1-36.12
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• 2018

Objectives: Direct pulp capping is a treatment for mechanically exposed pulp in which a biocompatible capping material is used to preserve pulpal vitality. Biocompatibility tests in animal studies have used a variety of experimental protocols, particularly with regard to the exposure site. In this study, pulp exposure on the occlusal and mesial surfaces of molar teeth was investigated in a rat model. Materials and Methods: A total of 58 maxillary first molars of Wistar rats were used. Forty molars were mechanically exposed and randomly assigned according to 3 factors: 1) the exposure site (occlusal or mesial), 2) the pulp-capping material (ProRoot White MTA or Bio-MA), and 3) 2 follow-up periods (1 day or 7 days) (n = 5 each). The pulp of 6 intact molars served as negative controls. The pulp of 12 molars was exposed without a capping material (n = 3 per exposure site for each period) and served as positive controls. Inflammatory cell infiltration and reparative dentin formation were histologically evaluated at 1 and 7 days using grading scores. Results: At 1 day, localized mild inflammation was detected in most teeth in all experimental groups. At 7 days, continuous/discontinuous calcified bridges were formed at exposure sites with no or few inflammatory cells. No significant differences in pulpal response according to the exposure site or calcium-silicate cement were observed. Conclusions: The location of the exposure site had no effect on rat pulpal healing. However, mesial exposures could be performed easily, with more consistent results. The pulpal responses were not significantly different between the 2 capping materials.

• 대한치과보철학회지
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• 제60권3호
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• pp.254-262
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• 2022

편악 부분 무치악 환자를 치료하는 경우, 적절한 수복 재료를 사용하는 것이 중요하다. 적절하지 않은 수복 재료는 보철 수복의 결과에 좋지 않은 영향을 줄 수 있다. 현재 널리 사용되고 있는 재료들인 지르코니아와 치과용 합금은 피질골보다 탄성 계수가 높아 외력 발생시 임플란트 및 임플란트 주위 골에 유해한 힘을 가할 수 있다. 최근 새롭게 소개된 재료인 Polyetherketoneketone (PEKK)은 피질골과 유사한 탄성계수를 가졌으며, 물리적 특성 및 생체 친화성에 있어서도 많은 이점을 가지고 있다. 본 증례에서는 PEKK를 이용한 임플란트 지지형 고정성 보철치료를 진행하였고 기능적, 심미적으로 만족할 만한 결과를 얻었기에 이를 보고하는 바이다.

• 한국심리학회지:법
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• 제13권1호
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• pp.53-74
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• 2022

본 연구는 현행 교정 처우의 보완적 방안으로서 소년 교정시설 내에서의 '용서하기'의 가능성을 고찰하는 데 그 목적이 있다. 문헌 고찰을 통해 지난 30여 년간 심리학자들을 중심으로 논의되어 온 용서의 개념과 용서 프로그램이 기반하고 있는 주요 용서 모델을 개관하였다. 그리고 최근 형사사법에서 주목받고 있는 회복적 사법에서 통용되는 용서와의 차이점을 살펴보았다. 또한, 교정시설에 수용된 소수의 고위험군 소년범은 상대적으로 심각성과 위험도가 낮은 소년범보다 아동기 부정적 생애경험을 비롯한 피해 사건을 더 많이 겪는다고 보고한 선행연구와 다양한 배경에서 시행된 용서 프로그램 결과를 토대로 소년 교정 현장에서의 '용서하기'의 가능성을 논증하였다. 이러한 논의 결과를 바탕으로 가해자인 소년범들도 이전에 경험한 피해 사실의 범주 내에서 제한적으로 '용서하기'가 가능하며, '용서하기'를 통한 심리적 어려움의 경감과 타인에 대한 부정적 태도의 개선이 교정 처우의 효과 제고에 기여할 수 있다는 점이 결론으로 제시되었다. 마지막에서는 본 연구의 제한점과 후속 연구에 대해 논의하였다.