• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.119-125
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• 2005

In the primary dentitions, the majority of dental injuries involve the anterior teeth, especially the maxillary primary central incisors. When injuries affecting primary and permanent teeth are compared, it appears that trauma to the primary dentition is usually confined to the supporting structures, i.e. luxation and exarticulation, while the largest proportion of injuries affecting the permanent dentition is represented by crown fractures. But, cases reporting trauma affecting primary molars are unusual in the literature and several reports describe fractures of posterior teeth. The main goal of this report is to describe the repositioning treatment using removable appliances to an uncommon case of lingual displacement of primary molar that happened to a 4 year 5 month-old female child.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.2
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• pp.135-142
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• 2022

Purpose. This study aims to evaluate the combined effect of reduced thickness in different regions on the fracture resistance of monolithic zirconia crowns. Materials and methods. Seven nickel-chromium dies were generated from a 3D model of mandibular first molar using the digital scanner with the following geometries: 1.5 mm occlusal reduction, 1.0 mm deep chamfer. Based on the abutment model, Zirconia blocks (Luxen Zirconia) were selected to fabricate Sixty-three zirconia crowns with occlusal thicknesses of 0.3 mm, 0.5 mm, and 1.5 mm, and different axial thicknesses of 0.3 mm, 0.5 mm, and 1.0 mm. All crowns were cemented by resin cement. Next, the crowns were subjected to load-to-fracture test until fracture using an electronic universal testing machine. In addition, fracture patterns were observed with a scanning electron microscope (SEM). Two-way ANOVA and the Tuckey HSD test for post hoc analysis were used for statistical analysis (P < .05). Results. The mean values of fracture resistancerecorded was higher than the average biting force in the posterior region. The two-way ANOVA showed that the occlusal and axial thickness affected the fracture resistance significantly (P < .05). However, the effect of axial thickness on fracture resistance did not show a statistical difference when thicker than 0.5 mm. The observed failure modes were partial or complete fracture depending on the severity of crack propagation. Conclusion. Within the limitations of the present study, the CAD-CAM monolithic zirconia crown with extremely reduced thickness showed adequate fracture resistance to withstand occlusal load in molar regions. In addition, both occlusal and axial thickness affected the fracture resistance of the zirconia crown and showed different results as combined.

• Restorative Dentistry and Endodontics
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• v.30 no.1
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• pp.49-57
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• 2005

The purpose of this study was to evaluate the effect of multiple application of all-in-one dentin adhesive system on microtensile bond strength to caries-affected dentin. Twenty one extracted human molars with occlusal caries extending into mid-dentin were prepared by grinding the occlusal surface flat. The carious lesions were excavated with the aid of caries detector dye. The following adhesives were applied to caries-affected dentin according to manufacturer's directions; $Scotchbond^{TM}$ Multi-Purpose in SM group, Adper Prompt $L-Pop^{TM}$ 1 coat in LP1 group, 2 coats in LP2 group, 3 coats in LP3 group, $Xeno^{(R)}$ III 1 coat in XN1 group, 2 coats in XN2 group. and 3 coats in XN3 group. After application of the adhesives, a cylinder of resin-based composite was built up on the occlusal surface. Each tooth was sectioned vertically to obtain the $1{\times}1\;mm^2$ sticks. The microtensile bond strength was determined. Each specimen was observed under SEM to examine the failure mode. Data were analyzed with one-way ANOVA. The results of this study were as follows; 1. The microtensile bond strength values were; SM ($14.38{\pm}2.01$ MPa), LP1 ($9.15{\pm}1.81$ MPa), LP2(14.08{\pm}1.75$ MPa), LP3 ($14.06{\pm}1.45$ MPa). XN1 (13.65{\pm}1.95$ MPa). XN2 ($13.98{\pm}1.60$) MPa, XN3 ($13.88{\pm}1.66$) MPa, LP1 was significantly lower than the other groups in bond strength (p < 0.05). All groups except LP1 were not significantly different in bond strength (p > 0.05). 2. In LP1, there were a higher number of specimens showing adhesive failure. Most specimens of all groups except LP1 showed mixed failure.

• Journal of the korean academy of Pediatric Dentistry
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• v.39 no.1
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• pp.66-72
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• 2012

Autogenous tooth transplantation can be defined as the surgical movement of a tooth from one position in the mouth to another in the same individual. The most common reasons for tooth transplantation include replacement of a missing first molar, transplantation of impacted canines to their normal positions in the arch, and transplantation of premolars in areas of missing teeth, especially in the anterior area of the mouth. The key to successful tooth transplantation is proper selection of graft with adequate root development as well as the design of surgical operation. Root development stage with half to three-quarter-developed roots increase the success rate of autotransplantation. We report the cases of successful autotransplantation which resulted in ideal healing of periodontal ligament, gingiva and alveolar bone. All transplanted teeth presented immature root formation at the moment of the procedure. After surgical procedure, we can observe good healing pattern without endodontic problem.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.4
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• pp.488-496
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• 2010

Dens evaginatus is a tooth with cylindrical enamel projection which forms a nodule on occlusal surface. It could be explained as outward overgrowth of inner enamel epithelium or localized hyperplasia of pulpal mesenchymal tissue during tooth development. A problem is that it is likely to be worn out or fractured by mastication ensuing pulpal inflammation. It is occasionally found on the lingual surface of upper anterior teeth as well, called talon cusp. Dens invaginatus is a tooth with deep lingual pit made by invagination of lingual enamel epithelium during tooth development while it is considered normal in terms of size and shape. Radiographically, a part of cervical enamel shows inward growth forming cavity and it is reasonable to say that the base is possibly open to pulpal cavity since they are very close. Talon cusp and dens invaginatus are relatively common abnormality of shape. However it becomes the opposite if the two exist in the same tooth. Once the talon cusp is broken by occlusal force or fissure between cusps is decayed, the complicated structure of canals makes the pulpal treatment difficult. Preventive treatments such as occlusal equilibrium and sealant, and regular oral examination should be preceded and thorough understanding of canal shape, using radiography, is required when pulpal treatment is necessary. This report is about a 9- year-old boy(lower left central incisor), a 8-year-old girl(upper right central incisor), and a 7-year-old boy(upper right central incisor), who have dens invaginatus and talon cusp in the same teeth. The first and the second patients are under pulpal treatments, and the last one is being observed showing no pathologic impressions.

• Journal of dental hygiene science
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• v.16 no.4
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• pp.317-322
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• 2016

Mineral trioxide aggregate (MTA) is widely used in endodontic therapy as a pulp-capping material, root or furcal perforation repair material, and for apexification and obturation of the root canal system. The purpose of this study was to formally document cases of MTA application in South Korean children and adolescents. Through this research, the practice of using MTA will be introduced and familiarized to the clinical practitioners. This study involved endodontic treatment using MTA for fractured crowns in 11- and 12-year-old. The children were followed up for 12 months until the pulp vitality was confirmed; in young permanent teeth with immature roots, the pulp is integral to the process of apexogenesis. These observational results regarding the use of MTA as an apexification material in non-vital immature permanent incisors appear to provide promising results in the search for new materials to meet existing endodontic needs.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.1-6
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• 2005

Injury of permanent teeth by trauma usually occurs to $8{\sim}10\;years$ old children, in mixed dentition. Fracture, dislocation, intrusion, extrusion, avulsion are the common types of trauma in teeth. The injuries which teeth are dislocated from the alveolar sockets can be treated by reduction and fixation. In this case report two children visited Wonkwang University Dental Hospital after the emergency treatment of tooth injury by other medical institutes. In these cases the injured teeth were not reducted properly and showed premature contact. So the teeth were dislocated from the alveolar sockets intentionally and fixed again in the proper position. Unproper reduction can cause premature contact, delay of healing, difficulty of mastication, and malocclusion. For this reason emergency rooms or local dental clinics where patients with dental trauma can be examined first, must know well about the treatment procedure of the injured teeth and should be consulted to the profession when necessary.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.3
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• pp.537-542
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• 2005

Dentofacial trauma can result in tooth fracture, avulsion, facial bone fracture. The Unites states and Japan mandated the use of mouthguards for contact sports. But, Korean didn't. Mouthguards divided into ready-made type and custom-made type. Mouthguards protect the lips, intraoral soft tissues, teeth and provide the mandible with resilient support to prevent jaw fracture and dislocations. Sports-related accidents have been reported to be one of the most common causes of dentofacial trauma. Sports trauma of involving teeth with incomplete root formation cause long chair time, multiple visit, economic considerations, additional dental services. So, mouthguards can offer considerable protection against sports-related trauma.

• Restorative Dentistry and Endodontics
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• v.34 no.4
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• pp.324-332
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• 2009

The purpose of this study was to investigate the effect of rigidity of post core systems on stress distribution by the theoretical technique, finite element stress-analysis method. Three-dimensional finite element models simulating an endodontically treated maxillary central incisor restored with a zirconia ceramic crown were prepared and 1.5 mm ferrule height was provided. Each model contained cortical bone, trabecular bone, periodontal ligament, 4 mm apical root canal filling, and post-and-core. Six combinations of three parallel type post (zirconia ceramic, glass fiber, and stainless steel) and two core (Paracore and Tetric ceram) materials were evaluated, respectively. A 50 N static occlusal load was applied to the palatal surface of the crown with a $60^{\circ}$angle to the long axis of the tooth. The differences in stress transfer characteristics of the models were analyzed. von Mises stresses were chosen for presentation of results and maximum displacement and hydrostatic pressure were also calculated. An increase of the elastic modulus of the post material increased the stress, but shifted the maximum stress location from the dentin surface to the post material. Buccal side of cervical region (junction of core and crown) of the glass fiber post restored tooth was subjected to the highest stress concentration. Maximum von Mises stress in the remaining radicular tooth structure for low elastic modulus resin core (29.21 MPa) was slightly higher than that for high elastic modulus resin core (29.14 MPa) in case of glass fiber post. Maximum displacement of glass fiber post restored tooth was higher than that of zirconia ceramic or stainless steel post restored tooth.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.1
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• pp.91-95
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• 2009

The use of stainless steel crowns are indicated for restoration of primary or permanent molars with proximal dental caries, extensive dental caries, or previous pulp treatment with increased danger of tooth fracture. Stainless steel crowns were introduced by Humphrey in 1950. For their improved durability, longevity, and success rate, they have been strongly considered for restoring extensive and multi-surfaced dental caries of molars in pediatric dentistry. However, they also have shortcomings, such as possibility of pulpal exposure or damaging proximal surface of adjacent teeth. In addition, when oversized stainless steel crowns are used, eruption of the adjacent permanent teeth may be disturbed by their prominent margin. As a means to compensate the shortcomings of stainless steel crowns, use of orthodontics bands may be considered. It is an alternative restoration method, where an orthodontic band is placed on a tooth first and cavity is restored with filling material, such as composite resin, glass ionomer, or amalgam. The use of an orthodontic band is indicated for molar restoration with cervical dental caries, extensive dental caries, enamel hypoplasia, or previous pulp treatment. Because it requires shorter chair time compared to stainless steel crown, its application is very useful for children with poor behavior. However, restoration using an orthodontic band requires good oral hygiene after its application. This case report illustrates the conservative restoration of primary molars and permanent molars with extensive dental caries using orthodontic bands.