• The Journal of Advanced Prosthodontics
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• 제8권3호
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• pp.194-200
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• 2016

PURPOSE. The prospective follow-up aimed to assess the performance of lithium disilicate crowns and clinical reasons of adverse events compromising survival and quality. MATERIALS AND METHODS. 58 patients were treated with 375 heat-pressed monolithic crowns, which were bonded with resin cement. Annual recalls up to five years included a complete dental examination as well as quality assessment using CDA-criteria. Any need for clinical intervention led to higher complication rate and any failure compromised the survival rate. Kaplan-Meier-method was applied to all crowns and a dataset containing one randomly selected crown from each patient. RESULTS. Due to drop-outs, 45 patients (31 females, 14 males) with the average age of 43 years (range = 17-73) who had 327 crowns (176 anterior, 151 posterior; 203 upper jaw, 124 lower jaw) were observed and evaluated for between 4 and 51 months (median = 28). Observation revealed 4 chippings, 3 losses of retention, 3 fractures, 3 secondary caries, 1 endodontic problem, and 1 tooth fracture. Four crowns had to be removed. Survival and complication rate was estimated 98.2% and 5.4% at 24 months, and 96.8% and 7.1% at 48 months. The complication rate was significantly higher for root canal treated teeth (12%, P<.01) at 24 months. At the last observation, over 90% of all crowns showed excellent ratings (CDA-rating Alfa) for color, marginal fit, and caries. CONCLUSION. Heat pressed lithium disilicate crowns showed an excellent performance. Besides a careful luting, dentists should be aware of patients' biological prerequisites (grade of caries, oral hygiene) to reach full success with these crowns.

• The Journal of Advanced Prosthodontics
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• 제3권2호
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• pp.90-95
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• 2011

PURPOSE. To compare the fracture resistance and the mode of failure of endodontically treated teeth restored with different post-core systems. MATERIALS AND METHODS. Root canal treatment was performed on 40 maxillary incisors and the samples were divided into four groups of 10 each. For three experimental groups post space preparation was done and teeth were restored with cast post-core (Group B), stainless steel post with composite core (Group C) and glass fiber post with composite core using adhesive resin cement (Group D). Control group (A) samples were selected with intact coronal structure. All the samples were prepared for ideal abutment preparation. All the samples were subjected to a load of 0.5 mm/min at $130^{circ}$.until fracture occurred using the universal testing machine. The fracture resistance was measured and the data were analyzed statistically. The fracture above the embedded resin was considered to be favorable and the fracture below the level was considered as unfavorable. The statistical analysis of fracture resistance between different groups was carried out with t-test. For the mode of failure the statistical analysis was carried out by Kruskal-Wallis test and Chi-Square test. RESULTS. For experimental group Vs control group the fracture resistance values showed significant differences (P<.05). For the mode of failure the chi-square value is 16.1610, which means highly significant (P=.0009) statistically. CONCLUSION. Endodontically treated teeth without post core system showed the least fracture resistance demonstrating the need to reinforce the tooth. Stainless steel post with composite core showed the highest fracture resistance among all the experimental groups. Teeth restored with the Glass fiber post showed the most favorable fractures making them more amenable to the re-treatment.

• Imaging Science in Dentistry
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• 제44권2호
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• pp.89-94
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• 2014

Purpose: Vertical root fracture (VRF) is a common complication in endodontically treated teeth. Considering the poor prognosis of VRF, a reliable and valid detection method is necessary. Cone beam computed tomography (CBCT) has been reported to be a reliable tool for the detection of VRF; however, the presence of metallic intracanal posts can decrease the diagnostic values of CBCT systems. This study evaluated and compared the effects of intracanal stainless steel or titanium posts on the sensitivity, specificity, and accuracy of VRF detection using a NewTom VG CBCT system. Materials and Methods: Eighty extracted single-rooted teeth were selected and sectioned at the cemento-enamel junction. The roots were divided into two groups of 40. Root fracture was induced in the test group by using an Instron machine, while the control group was kept intact. Roots were randomly embedded in acrylic blocks and radiographed with the NewTom VG, both with titanium and stainless steel posts and also without posts. Sensitivity, specificity, and accuracy values were calculated as compared to the gold standard. Results: The sensitivity, specificity, and accuracy of VRF diagnosis were significantly lower in teeth with stainless steel and titanium posts than in those without posts. Interobserver agreement was the highest in teeth without posts, followed by stainless steel posts, and then titanium posts. Conclusion: Intracanal posts significantly decreased the VRF diagnostic values of CBCT. The stainless steel posts decreased the diagnostic values more than the titanium posts.

• 한국치위생학회지
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• 제18권5호
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• pp.821-830
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• 2018

Objectives: This study aimed to examine the factors that affect the school-based oral health education in adolescents. Methods: This study was analyzed using data from the Korea youth risk behavior web-based survey in 2017. A total of 62,276 adolescents participated. The collected data was analyzed using the chi-square test, and logistic regression using SPSS, version 21.0. Results: Among the general factors related to oral health education in schools, male students experienced 1.14 times more oral health education in schools compared to female students, and middle school students experienced 1.81 times more oral health education than other students (p<0.001). With respect to oral health status, the groups without tooth fractures, pain during mastication, or gum pain and bleeding experienced 1.18 times, 0.95 times, and 1.03 times more oral health education in schools, respectively, compared to the group with complaints (p<0.001)(p<0.05). With respect to oral heath behavior, the group that brushed after lunch 'sometimes' during the last seven days received 1.43 times more oral health education compared to the group that 'always'brushed after lunch. Conclusions: It is necessary to supplement, extend, and strengthen oral health education programs in schools as well as motivate and recognize such programs.

• Restorative Dentistry and Endodontics
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• 제17권2호
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• pp.383-397
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• 1992

The purpose of this study was to evaluate the influence of artificial saliva contamination on bonding of several dentin adhesives to dentin. Sixty - three human molar teeth extracted within a month were used. Each tooth was sectioned longitudinally in a buccolingual direction to obtain 126 specimens. These specimens were randomly divided into three groups and were treated by Scotchbond 2, Gluma and All bond. Each group was subdivided into three subgroups; normal group not contaminated with artificial saliva, contaminated with artificial saliva and dried group, and contaminated with artificial saliva and washed and dried group. Enamel/dentin bonding agent(Dental Adhesive of Scotchbond 2) was applied and light cured on the treated dentin surfaces. Thereafter P - 50 were cured on them, and specimens were stored in $37^{\circ}C$ artificial saliva for 24 hours before measuring shear bond strength. Shear bond strengths were determined using an universal testing machine with cross head speed 1mm/min and SEM examinations were conducted to evaluate the resin - dentin interface and degree of penetrating resin string into the dentinal tubules. The following results were obtained. 1. Normal groups not contaminated with artificial saliva showed greater shear bond strength than any other group contaminated with artificial saliva(P<0.01). 2. The shear bond strengths showed no significant difference between washed groups with distilled water and not washed groups after contamination with artificial saliva(P>0.05). 3. In normal groups, the shear bond strength of A group was significantly greater than in any other group(P<0.01). 4. In Sand G groups, fractures after shear bond strength tests occured adhesively on resintooth interface in all specimens. But in A groups, fracture of the normal group occured cohesively in dentin and fracture of the contaminated groups occured adhesively and cohesively. 5. On SEM examination, the number of resin strings penetrated into dentinal tubules were the greatest in normal groups, followed by, in descending order, washed groups and not washed groups after contamination with artificial saliva.

• The Journal of Advanced Prosthodontics
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• 제7권2호
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• pp.160-165
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• 2015

PURPOSE. In this study, a temporal abutment fixation screw, designed to fracture in a controlled way upon application of an occlusal force sufficient to produce critical micromotion was developed. The purpose of the screw was to protect the osseointegration of immediate loaded single implants. MATERIALS AND METHODS. Seven different screw prototypes were examined by fixing titanium abutments to 112 Mozo-Grau external hexagon implants (MG Osseous$^{(R)}$; Mozo-Grau, S.A., Valladolid, Spain). Fracture strength was tested at $30^{\circ}$ in two subgroups per screw: one under dynamic loading and the other without prior dynamic loading. Dynamic loading was performed in a single-axis chewing simulator using 150,000 load cycles at 50 N. After normal distribution of obtained data was verified by Kolmogorov-Smirnov test, fracture resistance between samples submitted and not submitted to dynamic loading was compared by the use of Student's t-test. Comparison of fracture resistance among different screw designs was performed by the use of one-way analysis of variance. Confidence interval was set at 95%. RESULTS. Fractures occurred in all screws, allowing easy retrieval. Screw Prototypes 2, 5 and 6 failed during dynamic loading and exhibited statistically significant differences from the other prototypes. CONCLUSION. Prototypes 2, 5 and 6 may offer a useful protective mechanism during occlusal overload in immediate loaded implants.

• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.487-501
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• 1998

In the case of CAD/CAM ceramic inlay restorations, if isthmus width is widened too much, it may cause fracture of remaining tooth structure or loss of bonding at the luting interface because of excessive displacement of buccal or lingual cusps under occlusal loads. So to clarify the criterior of widening isthmus width, this study was designed to test the tensile bond strength and bond failure mode between dentin and ceramic cemented with luting composite resin cements. Cylindrical ceramic blocks(Vita Cerec Mark II, d=4mm) were bonded to buccal dentin of 40 freshly extracted third molars with 4 luting composite resin cements(group1 : Scotchbond Resin Cement/Scotchbond Multi-Purpose, group2 : Duolink Resin Cement/ All-Bond 2, group3: Bistite Resin Cement/Ceramics Primer, and group4:Superbond C&B). Tensile bond test was done under universal testing machine using bonding and measuring alignment blocks(${\phi}ilo$ & Urn, 1992). After immersion of fractured samples into 1 % methylene blue for 24 hours, failure mode was analysed under stereomicroscope and SEM. Results: The tensile bond strength of goup 1, 2 & 4 was $13.97{\pm}2.90$ MPa, $16.49{\pm}3.90$ MPa and $16.l7{\pm}4.32$ MPa, respectively. There was no statistical differences(p>0.05). But, group 3 showed significantly lower bond stregnth($5.98{\pm}1.l7$ MPa, p<0.05). In almost all samples, adhesive fractures between dentin and resin cements were observed. But, in group 1, 2 & 4, as bond strength increased, cohesive fracture within resin cement was observed simultaneously. And, in group 3, as bond strength decreased, cohesive fracture between hybrid layer and composite resin cement was also observed. Cohesive fracture within dentin and porcelain adhesive fracture were not observed. In conclusion, although adhesive cements were used in CAD/CAM -fabricated ceramic inlay restorations, the conservative priciples of cavity preparation must be obligated.

• Restorative Dentistry and Endodontics
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• 제48권2호
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• pp.16.1-16.11
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• 2023

Objectives: The aim of this study was to evaluate the influence of peak kilovoltage (kVp) and a metal artifact reduction (MAR) tool on image quality and the diagnosis of vertical root fracture (VRF) in cone-beam computed tomography (CBCT). Materials and Methods: Twenty single-rooted human teeth filled with an intracanal metal post were divided into 2 groups: control (n = 10) and VRF (n = 10). Each tooth was placed into the socket of a dry mandible, and CBCT scans were acquired using a Picasso Trio varying the kVp (70, 80, 90, or 99), and the use of MAR (with or without). The examinations were assessed by 5 examiners for the diagnosis of VRF using a 5-point scale. A subjective evaluation of the expression of artifacts was done by comparing random axial images of the studied protocols. The results of the diagnoses were analyzed using 2-way analysis of variance and the Tukey post hoc test, the subjective evaluations were compared using the Friedman test, and intra-examiner reproducibility was evaluated using the weighted kappa test (α = 5%). Results: The kVp and MAR did not influence the diagnosis of VRF (p > 0.05). According to the subjective classification, the 99 kVp protocol with MAR demonstrated the least expression of artifacts, while the 70 kVp protocol without MAR led to the most artifacts. Conclusions: Protocols with higher kVp combined with MAR improved the image quality of CBCT examinations. However, those factors did not lead to an improvement in the diagnosis of VRF.

• Restorative Dentistry and Endodontics
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• 제48권2호
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• pp.21.1-21.15
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• 2023

Objectives: This study evaluated the effects of Biodentine (BD), Bio-C Repair (BCR), and mineral trioxide aggregate (MTA) plug on the fracture resistance of simulated immature teeth with replacement root resorption (RRR) and in vitro-induced osteoclastogenesis. Materials and Methods: Sixty bovine incisors simulating immature teeth and RRR were divided into 5 groups: BD and BCR groups, with samples completely filled with the respective materials; MTA group, which utilized a 3-mm apical MTA plug; RRR group, which received no root canal filling; and normal periodontal ligament (PL) group, which had no RRR and no root canal filling. All the teeth underwent cycling loading, and compression strength testing was performed using a universal testing machine. RAW 264.7 macrophages were treated with 1:16 extracts of BD, BCR, and MTA containing receptor activator of nuclear factor-kappa B ligand (RANKL) for 5 days. RANKL-induced osteoclast differentiation was assessed by staining with tartrate-resistant acid phosphatase. The fracture load and osteoclast number were analyzed using 1-way ANOVA and Tukey's test (α = 0.05). Results: No significant difference in fracture resistance was observed among the groups (p > 0.05). All materials similarly inhibited osteoclastogenesis (p > 0.05), except for BCR, which led to a lower percentage of osteoclasts than did MTA (p < 0.0001). Conclusions: The treatment options for non-vital immature teeth with RRR did not strengthen the teeth and promoted a similar resistance to fractures in all cases. BD, MTA, and BCR showed inhibitory effects on osteoclast differentiation, with BCR yielding improved results compared to the other materials.

• 구강회복응용과학지
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• 제25권2호
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• pp.139-155
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• 2009

연구목적: 원추형(Superline) 임플란트를 발치와에 1회법으로 즉시 식립한 후 주변 조직의 생물학적 안정성을 관찰하는 것이다. 연구 방법: 치근부에 명백한 병적 소견이 있는 경우는 제외한 기타 치아의 발치와에 원추형 임플란트를 즉시 식립한다. 1회법을 식립한 후 임플란트 주변 연조직의 치유를 도모한다. 수술 후 32주에 획득한 표준화된 방사선상에서, 임플란트 주변골의 변화(depth of the distance from the implant shoulder (IS) and from the alveolar crest (AC) to the bottom of the defect (BD)) 등을 관찰했다. 결과 : 13명의 피검자 (남자 10명/ 여자 3명)를 선별하여 15개의 원추형 임플란트를 발치와에 즉시 식힙하였으며 모든 임플란트의 초기 고정은 양호했다. 평균 수술시간은 $41{\pm}10.0$분이었다. 모든 임플란트survival rate 는100% 였다. Mean ISQ values 는 상대적으로 안정했으며, 술 후 32주까지 계속 관찰에, 임플란트 인접 치조골 감소량은 $1.69{\pm}1.2mm$ (mesial), $1.65{\pm}1.2mm$ (distal) 로 나타났다. FMPS, FMBS, PPD와 각 은의 폭의 유의한 변화는 없었다. 결론: 파절이나, 근관치료의 실패 등의 이유로 해서 치아를 발치할 경우 치근형 (Superline)임플란트를 발칭하에 1회법으로 즉시 식립하는 술식은 임상적으로 예지성있는 치료법으로 판단된다.