• The Journal of Korean Academy of Prosthodontics
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• v.41 no.5
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• pp.565-581
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• 2003

Statement of problem : A scientific examination and understanding of overall aspects of the natural dentition is the first step involved in making a satisfactory selection in the shade of an aesthetic prosthesis. Proper natural shade selection of the prosthetic restoration that is in harmony with the remaining dentition is as important aesthetically, as harmony of form and function in the anterior dentition. Clinically, the most commonly applied method of shade selection has been visual, but because of the subjective nature inherent to this method, shade selection results are variable and can be influenced by such factors as the technician, the type of shade guide used, and the type and intensity of the lighting. Purpose : The purpose of this study was to develop a more objective and scientific approach to examining and understanding the shade of teeth, which has in turn lead to the development of a number of shade analysis devices that present a more objective method of shade analysis. Material and Method : In this study, the shades of healthy anterior teeth were examined and analyzed using the recently developed digital shade analysis of the $ShadeScan^{TM}$ System. The study examined 80 individuals in their twenties, 40 males and 40 females, presenting 6 healthy, unrestored maxillary anterior teeth. Tooth brushing and oral prophylaxis were performed prior to evaluation. The ShadeScan handpiece was used to acquire images of the 6 maxillary anterior teeth. These images were analyzed using the Vita/Classical mode of the $ShadeScan^{TM}$ Software, and shade maps of each tooth were acquired and divided into cervical, middle, and incisal thirds. The shade distribution of each third, left and right symmetry, and gender differences were investigated and analyzed. Results : The results of the study are as follows : 1. An overwhelming majority of the examined teeth were found to possess shades belong to Group A, with the greatest variations occurring at the middle and cervical thirds of the maxillary central and lateral incisors, in both male and female subjects. 2. Canines of both male and female subjects showed left and right symmetry with uniform shade distribution of A4 and C4, while the lateral and central incisors showed left-right symmetry of the incisal 1/3 with a uniform shade distribution of A2 and A3 shades 3. No significant differences in shade distribution were seen between genders in maxillary canines, whereas maxillary central and lateral incisors showed differences at the middle and cervical thirds between male and female subjects The results of this study show that with the exception of maxillary canines, maxillary anterior teeth display a diverse shade distribution as well as gender differences. Conclusion : Clinically, when making a shade selection using the existing shade guide, one must consider the fact that even a single tooth consists of a variety of shades. The results of this study show that when selecting a shade from a number of groups is difficult, shades from A group are the most consistent with the natural shade or maxillary anterior teeth.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.4
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• pp.580-585
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• 2009

Pediatric dentists often meet children with abnormal in number of tooth. Presence of supernumerary teeth is frequent cause of malocclusion. Etiology for supernumerary teeth is not yet clearly defined, but it is thought to be caused by excessive proliferation of dental lamina by hereditary and environmental factors. Supernumerary teeth occur in the maxilla nine times more frequently than in the mandible. Most common supernumerary tooth is the mesiodens in the maxilla, and some are observed in the maxillary molar and mandibular premolar. It occurs rarely in the mandibular incisor region with the incidence of 1-2% among all supernumerary teeth. A six-year old boy visited the department of the pediatric dentistry, Yonsei University Dental Hospital, with the chief complaint of crowded supernumerary teeth on the mandibular incisor region. Clinical and radiographic examinations revealed six permanent mandibular incisors similar in size, shape, and length. Further investigation using computed tomography(CT) was proceeded on the mandible to measure and compare morphologic features and positions of the six incisors. Then, we decided to remove two incisors which were already erupted. Periodic check-up was followed to monitor the dental development and spontaneous positional enhancement of the remaining four incisors in the mandible.

• The korean journal of orthodontics
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• v.41 no.2
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• pp.121-126
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• 2011

Objective: The purpose of this study was to evaluate shear bond strength (SBS) and failure site location of brackets bonded to enamel with or without desensitizer application. Methods: Sixty-six freshly extracted human premolar teeth were randomly divided into 3 groups of 22. Group 1 served as the control. Desensitizer was applied to the remaining teeth at two time intervals (Group 2, bonded immediately after Pro-$Relief^{TM}$ (Colgate-Palmolive Co., New York, NY, USA) application and Group 3, bonded 30 days after Pro-$Relief^{TM}$ application with the teeth stored in artificial saliva during the 30 days). Orthodontic brackets were bonded with a light cure composite resin and cured with a halogen light. After bonding, the SBS of the brackets was tested using a universal testing device. Adhesive remnant index (ARI) scores were determined after the brackets failed. Data were analyzed with analysis of variance, Tukey's HSD, and G tests. Results: The SBS was significantly lower in Group 2 than in Groups 1 (p = 0.024) and 3 (p = 0.017). Groups 1 and Group 3 did not differ (p = 0.991). ARI scores did not differ significantly among groups. Conclusions: The Pro-$Relief^{TM}$ desensitizer agent applied immediately before bonding significantly reduces bond strength, but the SBS values still exceed the minimum 5.9 - 7.8 MPa required for adequate clinical performance. Immersing the teeth in artificial saliva for 30 days after applying the Pro-$Relief^{TM}$ desensitizer agent and before bonding increased the SBS to control levels.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.2
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• pp.191-202
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• 1992

The purpose of the present study is to inspect the satisfied degree of each oral function in geriatric patients with the shortened dental arch and when their prosthetic treatment is on schedule, provide some references to such treatment. For the approach to such study, 521 subjects were reviewed by grouping them according to the number of their remaining teeth, and masticatory function, phonetic function, facial change, and TMJ disorders were inspected and clarified through some questionnaires. Also through the questionnaires, the correlations between the geriatiric patients with the shortened dental arch and dentition and between the geriatiric patients with the Free-end RDP at the shortened dental arch and their oral function were found out with their satisfied degree of oral function. Results or findings from such study are as follows : 1. With regard to their satisfied degree of oral function, there was a significant difference of satisfaction between or among the group having only the anterior teeth and the group having the part of premolars and the group having even the part of molars, however no significant difference of satisfaction appeard between the group having 1st molars and the group having 2nd molars. 2. With regard to their satisfied degree of phonetic function, no significant difference appeared between or among the group having only the anterior part of teeth and the group having even the part of premolars and the group having even the part of molars, and with regard to their satisfied degree of facial change, no significant difference of satisfaction appeared between the group having the part of premolars and the group having even the part of molars. 3. With regard to their satisfied degree of masticatory function, phonetic function, TMJ disorders, and facial change, no significant difference appeared between the group having both the anterior part of teeth and the part of premolars and the group attached with the Free-end RPD on the same conditions of the afore-said group.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.2
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• pp.192-199
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• 2016

Triple tooth is rare in primary dentition; it is the abnormal fusion of three teeth. There are a few reports of double teeth, but triple teeth are rare. These multiple teeth create several clinical problems, not only esthetic problems but also a high caries susceptibility, congenital missing permanent tooth germ(s), orthodontic problems, and periodontal problems. They also make it difficult to perform pulp treatment because of the complex tooth structure. A 1-year 7-month-old male underwent a partial pulpotomy with mineral trioxide aggregate (MTA) when pulp exposure caused by deep caries occurred at a maxillary anterior triple tooth in the first case. The second case was a 1-year 9-month-old male presenting with a fracture line at a mandibular anterior triple tooth. After removing the fractured fragment, a pulpectomy was performed at the remaining primary lateral incisors. Specific complications were not observed during 24 and 6 months of follow-up, respectively.

• Restorative Dentistry and Endodontics
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• v.15 no.2
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• pp.104-114
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• 1990

The purpose of this study was to evaluate the adaptation of root canal filling material to the dentinal wall of root canal and to compare the sealing ability of the root canal filling materials using ultrasonic endodontic instrument with injection-molded thermoplasticized gutta-percha filling method and lateral condensation method. Fifty fresh human single root exlracted for orthodontic treatment, were randomly selected, and instrumented by step-back technique. And then, the teeth were divided into 5 groups according to each root canal filling methods. In the experimental group 1 and group 2, the root canals were filled with gutta perdia cases using ultrasonic instrument with and without sealer. In the experimental group 3 and 4, using jection-moldeed thermoplasticized gutta-percha method by obtul$^{(R)}$ canals were filled with and without sealer. In the control group, the canals were filled with sealer by lateral candensation. And then, 5 teeth of each group were immersed in black Indian ink, decalcified and cleared. The depth of dye penetration into the root canal were evaluated with stereoscope (Reichert Ltd., USA). Among the 5 teeth remaining in each group, the single longituding grooves were made on the labial and lingual root surfaces and then immersed in the liquid nitrogen to fracture the teeth spontaneously without any distortions of gutta-percha. Each specimens were examined with X-650 Scanning Electron Microscope(Hitachi ltd, Japan) to show the adaptation to the canal wall, void, homogenicity of filling material and location of gutta-percha or sealer in the dentinal tubules of the root canal. The observations were as follows : 1. The experimental group 1 showed smaller mean dye penetration than control group, and showed the penetraton of sealer in the dentinal tubules of apical third of the root canal. 2. The experimental group 2 and group 4 showed the penetration of gutta-percha in the dentinal tubules of root canals. 3. The experimental group 1 and group 3 showed less mean dye penetration than the experimental group 2 and group 4. 4. The experimental group 1 and group 2 showed better adaptation of filling materials than control group.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.710-717
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• 1998

The pH changes in 3 cavities prepared at the facial inner dentin and lingual outer dentin of the cervical portion and apical portion of roots filled with calcium hydroxide containing sealers were investigated. 50 extracted permanent teeth with single canal were instrumented with step-back method. An irrigant of 5% NaOCl was used between files. Then 3 small cavities were prepared. The cavity of apical portion and inner dentin cavity of coronal portion was cut a distance of about 1.0mm from the canal wall and outer dentin cavity of coronal portion was cut to a depth of about 0.5mm from root surface. 10 teeth of control group was not filled. 20 teeth were not flushed with 17% EDTA before using root canal sealers and then divided into 2 groups obturated with Sealapex and Apexit. The remaining 20 teeth were flushed with 17% EDTA and 5% NaOCl to remove smear layer and divided into 2 groups obturated with Sealapex and Apexit. The pH change of the dentin in each cavity was measured at 0, 1, 3, 5, 7, 15, 30 days with pH microelectrode(WPI Co., USA). The results were as follows: 1. The groups obturated with Sealapex and Apexit(calcium hydroxide based-sealers) have no increase in the pH level at root dentin. And there is no significant difference in pH level between groups obturated with Sealapex and Apexit(P>0.05). 2. Differences in pH levels between the treated and untreated groups with EDTA were not significant(P>0.05). 3. There is no significant difference in pH level between apical and cervical dentin, inner and outer dentin throughout the duration of the experiment(P>0.05).

• Restorative Dentistry and Endodontics
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• v.26 no.5
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• pp.379-386
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• 2001

This study was performed to evaluate the sealing ability of various retrograde filling materials by using bacterial penetration and dye penetration test. One hundred and forty extracted human teeth with single, straight canals and mature apiece were collected and used for this study. All canals were instrumented using an engine driven Ni-Ti file (ProFile). After removing 3mm from the apex of tooth, a standardized 3mm root end cavity was prepared using an ultrasonic instrument. The 70 teeth were randomly divided into 7 groups : 6 groups for retrograde filling using Super-EBA, ZOE, Chelon-Silver, IRM, ZPC and amalgam. The 7th group was used as a negative control. Nail varnish was applied to all external root surfaces to the level of the reseated root ends to prevent lateral microleakages. The specimens were then sterilized in an ethylene oxide sterilizer for 24 hours. 2 mm of the reseated root was immersed in a culture chamber containing a Tripticase Soy Broth with a phenol red indicator. The coronal access of each specimen was inoculated every 72 hours with suspension of Proteus vulgaris. The culture media were observed every 24hours for color change indicating bacterial contamination. The specimens were observed for 4weeks. The remaining 70 teeth were submitted to a dye penetration test. The canals of all teeth were first sealed with AH26 and obturated using an Obtura II system. Root resection, root end preparation and retrograde filling was performed as above. All specimens were suspended in 2% methylene blue dye for 72 hours before being ion gitudinally split. The degree of dye penetration was then measured using a stereomicroscope at 10 magnification and evaluated. The results were as floows : 1. In the bacterial penetration, the degree of leakage was the lowest in the Super-EBA, followed by, in ascending order, ZOE, Chelon-Silver IRM and ZPC. The amalgam showed highest bacterial leakage of all(p<0.01). 2. In the dye penetration, the degree of microleakage was the lowest in the Chelon-Silver and Super-EBA, followed by, in ascending order, IRM, ZPC. The ZOE and amalgam showed the highest microleakage of all (p<0.05). These results suggested that the eugenol based cement, Super-EBA, have excellent sealing ability as a retrograde filling material.

• Restorative Dentistry and Endodontics
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• v.44 no.3
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• pp.31.1-31.9
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• 2019

Objectives: To compare the formation of dentinal defects using stainless-steel hand K-files (HFs), rotary files, reciprocating files, and Self-Adjusting File (SAF), when used for oval root canals. Materials and Methods: One hundred and forty extracted human mandibular premolar with single root and oval canal were selected for this study. Oval canals were confirmed by exposing to mesio-distal and bucco-lingual radiographs. Teeth with open apices or anatomic irregularities were excluded. All selected teeth were de-coronated perpendicular to the long axis of the tooth, leaving roots segments approximately of 16 mm in length. Twenty teeth were left unprepared (control), and the remaining 120 teeth were divided into 6 groups (n = 20) and instrumented using HF (size 40/0.02), Revo-S (RS; size 40/0.06), ProTaper NEXT (PTN; size 40/0.06), WaveOne (WO; size 40/0.09), RECIPROC (RC; size 40/0.06), and the SAF (2 mm). Roots were then sectioned 3, 6, and 9 mm from the apex, and observed under stereomicroscope, for presence of dentinal defects. "No defect" was defined as root dentin that presented with no visible microcracks or fractures. "Defect" was defined by microcracks or fractures in the root dentin. Results: The control, HF, and SAF did not exhibit any dentinal defects. In roots instrumented by RS, PTN, WO, and RC files exhibited microcracks (incomplete or complete) in 40%, 30%, 55%, and 50%, respectively. Conclusions: The motor-driven root canal instrumentation with rotary and reciprocating files may create microcracks in radicular dentine, whereas the stainless-steel hand file instrumentation, and the SAF produce minimal or less cracks.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.2
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• pp.174-182
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• 2024

In patients with multiple missing molars, wear patterns or displacement of anterior teeth, collapsed occlusal plane, and reduction in vertical dimension may occur. Particularly, in case of a few remaining teeth on one side, a removable partial denture has biomechanical disadvantage. For this reason, an implant-assisted removable partial denture with a few implant surveyed crowns can be an alternative. In this case, due to the right mandibular posterior teeth loss, the anterior teeth were severely worn and the occlusal plane was collapsed. With minimal increasing vertical dimension, oral rehabilitation was performed using a maxillary fixed prosthesis and mandibular implant-assisted removable partial denture. As a result, functional and aesthetic clinical outcomes were obtained.