• The Journal of Korean Academy of Prosthodontics
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• v.55 no.1
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• pp.38-45
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• 2017

In removable partial denture with crossed occlusion, it is difficult to meet the satisfaction of patient due to variable movement of denture and unfavorable stability under loading. In a case with few unilaterally teeth remaining, additional treatments such as implantation or residual root are required to assure bilaterally stable support. However, due to the medical condition of the patient with hypertension, angina and old age etc., removable partial denture was planned as treatment in this case. Proper diagnosis, accurate analysis and full understanding of the adaptation for neuromuscular system are necessary to recover the vertical dimension of patient from a decreased vertical dimension due to crossed occlusion.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.536-545
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• 1997

The purposes of this study were to evaluate the degree of cavity cleanliness and to observe cavity wall morphology when root-end retrograde cavity preparation was done with ultrasonics. Root resections were done on 20 extracted human maxillary central incisors after canal filling with gutta-percha, and retrocavities were prepared using a slow-speed round bur as a control, and stainless steel ultrasonic tips of power settings of 2 and 6 ($Miniendo^{TM}$, EIE, SA, USA) as experimentals. The degree of the remaining cavity debris and smear layer, and wall morphology were evaluated under the scanning electron microscope. The results were as follows : Cavity prepared with ultrasonics of either power setting showed significantly less smear layer than did slow-speed preparations (p<0.01). However, there was no significant difference in canal debris (p<0.05). Cavity prepared with ultrasonics showed hatcheted appearance of wall, while slow-speed preparation showed relatively plain one.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.1
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• pp.21-27
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• 2016

In removable dental prostheses, it is important to minimize impairment of residual tissue caused by wearing dentures. There are two factors that harm residual tissue. The first is functional load bearing of remaining teeth and alveolar ridges and the second is the effect of poor oral hygiene. Double crown retained removable dental prostheses provide rigid support, and it may reduce impairment caused by load bearing of alveolar ridges. Also, dental plaque and oral deposits, which are attached to outer crowns and dentures, can be easily managed extra-orally. In addition, it is beneficial to the health of the marginal gingiva because inner crowns have easy access for oral hygiene. In this case, double crown retained removable dental prostheses were used for the partially edentulous patient with severe residual alveolar bone resorption and poor oral hygiene, and the result was clinically satisfactory in terms of functional, esthetical, and oral hygiene aspects.

• The Journal of Advanced Prosthodontics
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• v.5 no.2
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• pp.204-208
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• 2013

PURPOSE. The purpose of this study was to evaluate the effectiveness of a promotion campaign for subject recruitment and selection, and reasons of withdrawal from a prospective clinical trial of mandibular two-implant supported overdenture. MATERIALS AND METHODS. The subjects of this study were participants in a randomized controlled clinical trial for investigating prognosis of implants and overdentures with attachments. Recruited subjects were classified by gender, age, and participation motives. Withdrawal rate of the participants before and after enrollment were evaluated. RESULTS. 177 patients were recruited and 51 patients were enrolled for the trial. Among them, 40 participants eventually took part in the trial. 116 subjects (65.5%) were recruited by advertisement and 61 (34.5%) were referred by patients of the hospital or local clinics. Regarding recruitment effectiveness, newspaper recruited the largest number of participants. With respect to referral patients, the proportion of our hospital patients was higher (37/61). Subjects in their 70s comprised the largest proportion (22/51). The male to female ratio was similar (25:26). Final withdrawal rate of all subjects were 74.0%. Among the reasons for withdrawal from enrollment (n=126) presence of remaining teeth and lack of motivation were the most common reasons. CONCLUSION. To facilitate recruitment of clinical trial subjects and improve enrollment rate, it is important to obtain a sufficient number of researchers, perform promotion activity with diverse strategies, cooperate with local dentists, increase the research funding, and alleviate subjects' fear against clinical trials by thorough consultation.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.2
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• pp.120-126
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• 2013

Preserving the pulp is important in the treatment of carious pulp exposure in young permanent teeth. Pulpotomy is a vital pulp therapy in which a portion of the coronal pulp tissue is surgically removed, and the remaining radicular tissue is covered with suitable material that protects the pulp from further injury and permits and promotes healing. It is important to develop biocompatible treatment directed at maintaining pulp vitality and increasing tooth longevity. Platelet-rich fibrin (PRF) has been referred to as a second-generation platelet concentrate. Two clinical cases in which PRF was applied as a medicament after pulpotomy of an immature permanent tooth are presented. After isolation, caries removal and pulpotomy with PRF was performed. A layer of mineral trioxide aggregate (MTA) was placed over the PRF, and the final restoration was performed. Postoperatively, the patient had no pain or discomfort, and follow-up radiographs revealed normal periodontal ligament space and trabecular bone pattern.

• The Journal of the Korean dental association
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• v.56 no.2
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• pp.84-93
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• 2018

Purpose: This study evaluated the apical root canal system of maxillary second molars, in which conventional endodontic treatment had failed. Materials and Methods: One hundred eighteen extracted endodontically failed maxillary second molars were examined to investigate the root canal morphology using clinical photographs. High-resolution cross-sectional images at the 3mm level from the root apices were taken to evaluate the anatomic variations and canal cleanliness. The incidence of anatomic variations and canals containing debris were evaluated statistically. Results: One (0.85%) maxillary second molar had four separate roots, while 52 (44.07%) had three separate roots. The remaining 65 (55.08%) showed 6 different types of fusion in their roots. As the number of fused roots increased from none to three, the incidence of isthmuses in the cross-sectional images increased significantly from 43.40% to 76.92% in 2-root fusion and 88.46% in 3-root fusion. In addition, the occurrence of less-cleansed canals increased from 22.64% to 38.46% and 53.85%, respectively (p<0.05). Sixty four teeth (54.24%) had 3 canals while 38(32.2%) had additional canals; most of them were located in the MB roots (81.58%). Seventy six (64.41%) had isthmuses in the apical region and 58 out of 76 were located in MB roots. Condlusions: Logistic analysis indicated that the less division of roots was associated significantly with the occurrence of insufficient cleaning during endodontic treatment (OR=1.765, p<0.05), while the presence of an additional canal showed no association.

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.231-254
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• 1994

Fracture of cusp, on posterior teeth, especially those carious or restored, is major cause of tooth loss. Inappropriate treatments, such as unnecessarily wide cavity preparations, increase the potential of further trauma and possible fracture of the remaining tooth structures. Fracture potential may be directly related to the stresses exerted upon the tooth during masticatory function. The purpose of this study is to evaluate the fracture resistance of tooth, restored with composite resin inlay. In this study, MOD inlay cavity prepared on maxillary first premolar and restored with composite resin inlay. Three dimensional finite element models with eight nodes isoparametric solid element, developed by serial grinding-photographing technique. These models have various occlusal isthmus and depth of cavity, 1/2, 1/3 and 1/4 of isthmus width and 0.7, 0.85 and 1.0 of depth of cavity. The magnitude of load was 474 N and 172 N as presented to maximal biting force and normal chewing force. These loads applied onto ridges of buccal and lingual cusp. These models analyzed with three dimensional finite element method. The results of this study were as follows : 1. There is no difference of displacement between width of occlusal isthmus and depth of cavity. 2. The stress concentrated at bucco-mesial comer, bucco-disal comer, pulpal line angle and the interface area between internal slopes of cusp and resin inlay. 3. The vector of stress direct to buccal and lingual side from center of cavity, to tooth surface going on to enamel. The magnitude of vector increase from occlusal surface to cervix. 4. The crack of tooth start interface area, between internal slop of buccal cusp and resin inlay. It progresses through buccopulpal line angle to cervix at buccomesial and buccodistal comer. 5. The influence with depth of cavity to fracture of tooth was more than width of isthmus. 6. It would be favorable to make the isthmus width narrower than a third of the intercuspal distance and depth of cavity is below 1 : 0.7.

• Restorative Dentistry and Endodontics
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• v.42 no.3
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• pp.188-199
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• 2017

Objectives: This in vitro study evaluated the effect of dentin biomodifiers on the immediate and long-term bond strengths of a simplified etch and rinse adhesive to dentin. Materials and Methods: Flat coronal dentin surfaces were prepared in 120 extracted human molars. Teeth were randomly divided into 5 groups (n = 24) according to 5 different surface pre-treatments: No pre-treatment (control); 1M carbodiimide (EDC); 0.1% epigallocatechin-3-gallate (EGCG); 2% minocycline (MI); 10% sodium ascorbate (SA). After surface pre-treatment, adhesive (Adper Single Bond 2 [SB], 3M ESPE) was applied. Composite was applied into transparent plastic tubes (2.5 mm in diameter), which was placed over the bonded dentin surface. From each group, 10 samples were subjected to shear bond strength (SBS) evaluation at 24 hours (immediate) and remaining 10 samples were tested after 6 months (delayed). Additionally, 4 samples per group were subjected to scanning electron microscopic analysis for observation of resin-dentin interface. The data were statistically analysed with Shaperio-Wilk W test, 2-way analysis of variance (ANOVA), and post hoc Tukey's test. Results: At 24 hours, SBS of all surface pre-treatment groups were comparable with the control group, with significant differences found between EDC and SA groups only (p = 0.009). After 6 months storage, EDC, EGCG, and MI pre-treatments preserved the resindentin bond strength with no significant fall. Conclusions: Dentin pre-treatment with all the dentin biomodifiers except SA resulted in significant preservation of resin-dentin bond over 6 months storage period, without negatively affecting the immediate bond strength of the etch and rinse adhesive tested.

• Restorative Dentistry and Endodontics
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• v.38 no.3
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• pp.154-159
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• 2013

Objectives: The aim of this study was to compare the cleaning efficacy of different final irrigation regimens in canal and isthmus of mandibular molars, and to evaluate the influence of related variables on cleaning efficacy of the irrigation systems. Materials and Methods: Mesial root canals from 60 mandibular molars were prepared and divided into 4 experimental groups according to the final irrigation technique: Group C, syringe irrigation; Group U, ultrasonics activation; Group SC, VPro StreamClean irrigation; Group EV, EndoVac irrigation. Cross-sections at 1, 3 and 5 mm levels from the apex were examined to calculate remaining debris area in the canal and isthmus spaces. Statistical analysis was completed by using Kruskal-Wallis test and Mann-Whitney U test for comparison among groups, and multivariate linear analysis to identify the significant variables (regular replenishment of irrigant, vapor lock management, and ultrasonic activation of irrigant) affecting the cleaning efficacy of the experimental groups. Results: Group SC and EV showed significantly higher canal cleanliness values than group C and U at 1 mm level (p < 0.05), and higher isthmus cleanliness values than group U at 3 mm and all levels of group C (p < 0.05). Multivariate linear regression analysis demonstrated that all variables had independent positive correlation at 1 mm level of canal and at all levels of isthmus with statistical significances. Conclusions: Both VPro StreamClean and EndoVac system showed favorable result as final irrigation regimens for cleaning debris in the complicated root canal system having curved canal and/or isthmus. The debridement of the isthmi significantly depends on the variables rather than the canals.

• Journal of Dental Anesthesia and Pain Medicine
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• v.21 no.5
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• pp.441-449
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• 2021

Background: The efficacy of local anesthesia decreases in patients with symptomatic irreversible pulpitis. Therefore, it was proposed that the use of premedication with an anti-inflammatory drug might increase the success rate of pulpal anesthesia in mandibular posterior teeth with vital inflamed pulp. Methods: One hundred thirty-four patients who were actively experiencing pain willingly participated in this study. The Heft Parker (HP) visual analog scale (VAS) was used to record the initial pain intensity. Patients were randomly allocated to receive a placebo, 10 mg of ketorolac, and 650 mg of paracetamol. The standard inferior alveolar nerve block (IANB) was administered to all patients using 2% lidocaine with 1:200,000 adrenaline after one hour of medication. After 15 min, the patient was instructed to rate the discomfort during each step of the treatment procedure, such as access to remaining dentin, access to the pulp chamber, and during canal instrumentation on the HP VAS. IANB was considered successful if the patient reported no or mild pain during access preparation and instrumentation. Moderate or severe pain was classified as a failure of IANB and another method of anesthesia was used before continuing the treatment. Results: The rate of successful anesthesia in the placebo, paracetamol, and ketorolac groups was 29%, 33%, and 43%, respectively, and no statistically significant difference was found between the groups. Conclusion: Preoperative administration of paracetamol or ketorolac did not significantly affect the success rate of IANB in patients with irreversible pulpitis. No significant difference was observed between the paracetamol and ketorolac groups.