• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.4
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• pp.595-607
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• 1999

The purpose of this in vitro study was to evaluate the efficacy of self-etching primer which was developed to simplify the bonding procedures by measuring the shear bond strength and observing the interfacial morphology. 90 flat dentinal surfaces were prepared by grinding the buccal and lingual areas of caries-free human deciduous molars. After bonding of composite resin to sample surfaces according to the manufacturer's direction and thermocycling, shear bond strengths were measured using Universal testing machine(Instron). Another groups of specimens were treated by hydrochloric acid to secure the resin only and those tags were evaluated under SEM for their length and forms and the morphology of the bonding sites were also observed. The result as follows. 1. Group III showed higher shear bond strength than group I and II but no statistically significant difference was founded between group I and II(p>.05). 2. Adhesive failure was predominant in group II whereas dentin detachment was the main failure pattern in group I and III. 3. Relating long resin tags of $100-200{\mu}m$ were observed in samples of all groups under SEM. In group I, homogeneously long resin tags were arranged rather tight whereas rather loosely arranged resin tags of various length were found in group II. Lateral branching of resin tags was the characteristic finding observed in group III.

• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.2
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• pp.267-272
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• 2004

This case report describes an uncommon treatment method for crown-root fractured incisor with immature root. A 7-year-old girl was referred for treatment of crown-root fractured maxillary central incisor. The fracture line extended to 1/2 of the total tooth length with incomplete root formation. The prognosis of crown-root fracture is usually poor and extraction is usually undertaken. But, in the mixed dentition, extraction of maxillary permanent incisor results in many complications, such as resorption of alveolar bone, poor esthetics, pronunciation and mastication. Conservative therapy in the permanent dentition comprises of few treatment modalities; supragingival restoration, gingivectomy, orthodontic extraction of apical fragment, surgical extrusion of apical fragment with or without rotational replantation. However, in this case, these indications are not applicable, so intentional replantation with adhesive resin system is the treatment of choice. The tooth was followed-up for 12 months. Currently, there are no symptoms. Since this modality adopts the respective advantages of both intentional replantation and adhesive treatment, it might be the treatment of choice in cases of vertical crown-root fracture.

• The korean journal of orthodontics
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• v.30 no.4 s.81
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• pp.475-481
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• 2000

The purpose of this study was to evaluate the effect of oral environment on the strength of resin bracket wings by comparing fracture mode according to water immersion and thermocycling. Seventy-five resin brackets(Spirit MB, Ormco, California) were divided into three groups and treated for six months as follows; (1) untreated, (2) water immersion in distilled water at $37^{\circ}C$, (3) water immersion in distilled water at $37^{\circ}C$ with total 2,100 times of thermocycling taken 350 times each month. Fracture mode of the wing was tested on universal testing machine. In addition to resin brackets, 25 metal brackets were used as controls. Through the statistical analyses, following results were obtained. 1. Resin bracket wings showed significantly lower fracture strength than metal brackets(p<0.001). 2. Water immersion and water immersion with thermocycling groups showed significantly lower fracture strength than open air condition group(p<0.001). 3. Water immersion with thermocycling group showed significantly lower fracture strength than water immersion group(p<0.001). The above results suggest that the mechanical property of resin bracket wing nay be influenced by oral environment and further research is needed to improve the strength of the wing in the resin bracket.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.225-231
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• 2019

Purpose: This study was undertaken to compare fracture and flexural strength of provisional restorative resins fabricated by additive manufacturing, subtractive manufacturing, and conventional direct technique. Materials and methods: Five types of provisional restorative resin made with different methods were investigated: Stereolithography apparatus (SLA) 3D printer (S3Z), two digital light processing (DLP) 3D printer (D3Z, D3P), milling method (MIL), conventional method (CON). For fracture strength test, premolar shaped specimens were prepared by each method and stored in distilled water at $37^{\circ}C$ for 24 hours. Compressive load was measured using a universal testing machine (UTM). For flexural strength test, rectangular bar specimens ($25{\times}2{\times}2mm$) were prepared by each method according to ISO 10477 and flexural strength was measured by UTM. Results: Fracture strengths of the S3Z, D3Z, and D3P groups fabricated by additive manufacturing were not significantly different from those of MIL and CON groups (P>.05/10=.005). On the other hand, the flexural strengths of S3Z, D3P, and MIL groups were significantly higher than that of CON group (P<.05), but the flexural strength of D3Z group was significantly lower than that of CON group (P<.05). Conclusion: Within the limitation of our study, provisional restorative resins made from additive manufacturing showed clinically comparable fracture and flexural strength as those made by subtractive manufacturing and conventional method.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.1
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• pp.37-41
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• 2019

Dental implants are an effective and predictable treatment for restoration of missing teeth. However, as the use of implants increases, complications are also increasing. The mechanical complications are not only highly frequent, but also increasing as life span of an implant increases, thus, solutions should be prepared. In this report, we will present a case dealing with abutment fracture and abutment screw fracture which are the most common mechanical complication of the implant, focusing on preserving and reusing existing components by reconstructing only the damaged parts.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.1
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• pp.60-69
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• 2016

Complicated crown-root fracture of permanent incisors cause esthetic, functional, and psychological problems to patients. Therefore, treatment is important and multidisciplinary treatment is required. This case report describes the clinical procedures involved in the treatment of trauma-induced complicated crown-root fractures in the maxillary incisor of two young patients. Conventional root canal treatment and apexification were performed in each patient. To expose the fracture margins to the supragingival level and to reestablish the biologic width, orthodontic extrusions with fixed appliances were performed followed by a retention period. During the retention period, fiber-optic posts and cores were built up and provisional crowns were placed. Finally, ceramic crowns manufactured using a computer-aided design/computer-aided manufacturing (CAD/CAM) system were placed. In both patients, the teeth presented satisfactory functional and esthetic outcomes without relapse. The periodontal tissues were healthy.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.1
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• pp.10-20
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• 2018

The aim of this study was to evaluate the factors affecting the healing of root fracture in immature permanent teeth and the prognosis of root fracture by statistically analyzing the relationship with the pulp and root healing. The radiographs of 51 root-fractured maxillary anterior permanent teeth were collected. In radiograph, locations of root fracture, apical foramen width and width of diastasis between the fragments were measured. The value of the studied parameters were compared by independent t-test and rogistic regression test. In conclusion, there was no difference in the prognosis of pulp healing according to the location of root fracture. However, root healing occurs well as the root fracture is located at the root apex (p < 0.05). Lastly, the smaller the width of diastasis between the fragments after reduction, the better the pulp healing was (p < 0.05).

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.1
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• pp.60-66
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• 2015

Screw loosening and screw fracture of abutment is one of most frequent mechanical complications in implant restoration. Fractured fragments in implant restoration like abutment and screw should be completely removed and the procedure needs minimal damage to the fixture of implant. In some cases, it could fail to remove fractured fragments and cause a lot of damage to the fixture of implant. These situations could render implant unusable at the worst. This article describes three different situations and simple techniques for successful removal of fractured fragments without damage of implants. The procedures used are described in this clinical report.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.3
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• pp.204-209
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• 2012

Surgical extrusion, immediate extrusion following tooth luxation, is a method to preserve one's natural tooth and achieve esthetic restoration without additional periodontal surgery when subgingival dental caries or crown fracture occurs. A 16-year-old male was referred to the clinic from the department of operative dentistry for the esthetic restoration of maxillary left lateral incisor. Due to the crown to root fracture, the tooth was endodontically treated with a buccal crown length of 4 mm. When the palatal flap was elevated, the mesiopalatal cervical fracture area was situated 3-4 mm subgingivally. Crown lengthening was achieved through surgical extrusion. After 3 months of clinical observation and provisional restoration, the maxillary left central incisor was restored with all ceramic crown and obtained a satisfactory clinical result.

• Journal of the Korean Arthroscopy Society
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• v.13 no.2
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• pp.170-173
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• 2009

Wiring techniques in the fixation of patellar fracture are commonly used. Rigid fixation is essential for early rehabilitation. Breakages of wires after the fixation of patellar fracture are common with extracapsular migration if not removed for long term. But, we experienced a case of patellar fracture with early breakage of wiring and migration of the broken wire fragment into the popliteal fossa through the popliteal hiatus in 64- year-old man and we successfully treated this case, using both arthroscopic and open procedures. So we report this unusual case with a review of current literatures.