• Restorative Dentistry and Endodontics
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• v.26 no.2
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• pp.180-187
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• 2001

The structure of current guides is largely illogical and without any rational use of color ordering. The shade guides are generally made of plastic (rather than the actual composite material) and do not accurately depict the true shade. translucency. or opacity of the composite resin after polymerization. To solve this problem, information based on evaluations of natural teeth and material that use the same method and experimental conditions is necessary. The present investigation measured the color of natural maxillary anterior teeth in vivo and compared the results with those of composite resins. 269 Korean subjects were selected for this study. Intact central incisor. lateral incisor. and canine were selected. The clinical crowns were free of caries or restorations. The middle site of the coronal portion on the labial surface of the tooth was measured by Chroma Meter. The five light activated. resin-based materials (Amelogen, Denfil, Elitefil, Spectrum, Z100) were used in this study. Resin composite was condensed into plastic mold with a diameter of 8mm and a thickness of 4mm. pressed between glass plates to flatten the surfaces. and polymerized using a Visilux II visible light activation unit. The surfaces were polished sequentially on wet sandpaper. Color measurements of each specimen were accomplished by Chroma Meter. A computer program that compares each tooth color with each composite resin color was written and the minimum CIELAB color difference ($\Delta$E$^*$) between tooth and each material was calculated. Under the conditions of this study: 1. Teeth tend to become darker with advancing age. 2. Canines were darker. more yellow. and less green than incisors. 3. The teeth from the women were lighter. more green. and less yellow than the male teeth. 4. In general. composite resins were lighter. more green. and less yellow than teeth. Deficiencies were noted in Hues in YR range. 5. Mean color differences between the five composite resin products and teeth were detectable to the naked eye($\Delta$E$^*$>1.0). 6. In comparing the mean $\Delta$E$^*$ values of materials. Spectrum showed the least followed by Z100, Elitefil, Amelogen, Denfil in increasing order.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.1
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• pp.47-61
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• 1998

The purpose of this study was to compare the microleakage pattern of glass ionomer with resin restoration in microleakage pattern of primary and permanent teeth. Microscopical observation of interface between tooth structure and restoration was also performed. 80 and 8 sound molar teeth were used for the microleakage test and SEM study respectively. Data were analyzed statistically using ANOVA test and/or t-Test. The results of the present study were as follows: 1. According to the result of microleakage pattern between primary and permanent tooth, primary tooth generally showed more micro leakage than permanent tooth in all groups (p<.05). 2. In the resin-filled groups, occlusal margin was shown to have more microleakage than gingival margin(p<.05). Whereas the glass ionomer-filled groups showed no statistically significant differences between them(p>.05). 3. No statistically significant differences in microleakage could be found between two different resin groups(p>.05), while Fuji II LC group showed less microleakage than Ketac-Fil group(p>.05). 4. The various type hybrid layer was evident under SEM in resin-filled groups both in primary and permanent teeth with generally thicker layer in primary group. Among glass-ionomer group, Fuji II LC group showed more intact adhesion to tooth surface than Ketac-Fil group

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.4
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• pp.670-674
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• 2005

Supernumerary tooth develops as a result of abnormal proliferation of the dental lamina during the initiation stage of dental development. It could be a sporadic occurrence or a hereditary transmission. Supernumerary tooth occurs with a frequency of 1 to 3%. Generally, there is a 2:1 preference for boys. It is usually found in the anterior portion of the maxilla and may be associated with complications such as impaction, malposition of permanent teeth, formation of diastema, cysts and eruption into nasal cavity, The position of supernumerary tooth found in the anterior portion of the maxilla is determined by the axis of the tooth. One third of supernumerary tooth in the anterior portion of the maxilla has no possibility of eruption due to its invertedly impacted position. However, as long as the coronal part of the follicle remains intact, migration of supernumerary tooth is possible. The migration may occur into the palate, the premolar region, the sinus or the nasal cavity. Also, growth of vertical dimension of maxilla could make surgical approach difficult as time goes by For this reason, we have found invertedly impacted mesiodens moved to the vault of the palate in the two cases, and extracted supernumerary tooth surgically.

• The korean journal of orthodontics
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• v.51 no.5
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• pp.329-336
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• 2021

Objective: To compare the magnitude of external apical root resorption (EARR) 6 months after starting orthodontic treatment using orthodontic aligners (OAs) and fixed appliances (FAs). Methods: This parallel randomized clinical trial included 40 patients randomized into two groups: OA group (n = 20, 160 incisors) and FA group (n = 20, 160 incisors). For evaluation of the tooth length, periapical radiographs and standardized linear measurements of the maxillary and mandibular incisors were acquired before (T0) and 6 months after treatment initiation (T1). EARR was calculated through the difference in length between the two time points (T1-T0). Statistical comparisons were performed by means of using t-tests, chi-squared test and covariance analysis (a = 5%). Results: Rounding of the root apex was observed in both groups; the resorption involved 2.88% of the root length, so 97.12% of the tooth length remained intact. Intragroup comparisons between the two time points revealed a significant difference, with (T1-T0) ranging from -0.52 to -0.88 mm in the FA group and from -0.52 to -0.85 mm in the OA group. In the intergroup comparisons, only tooth #21 presented a statistically significant difference (OA: -0.52 ± 0.57 mm, FA: -0.86 ± 0.60 mm); however, the overall differences between groups were not clinically relevant, ranging from 0.03 to 0.35 mm. Conclusions: OA and FA treatment resulted in a similar degree of EARR in the maxillary and mandibular incisors at 6 months after treatment initiation. However, the amount of resorption was small and does not impair tooth longevity.

• The Journal of Advanced Prosthodontics
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• v.8 no.6
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• pp.489-493
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• 2016

PURPOSE. This in-vitro study aimed to evaluate the fracture resistances and failure modes of endodontically treated mandibular premolars restored with endocrowns and conventional post-core retained crowns. MATERIALS AND METHODS. Thirty mandibular premolars were assigned into three groups (n=10): GI, intact teeth; GE, teeth with endocrowns; GC, teeth with conventional post-core supported crowns. Except for the teeth in group GI, all specimens were cut to 1.5 mm above the cementoenamel junction and endodontically treated. Both endocrowns and conventional crowns were fabricated from lithium-disilicate blocks using a CEREC 3D CAD/CAM unit. All specimens were subjected to thermocycling and then to $45^{\circ}$ oblique compressive load until fracture occurred. The fracture resistance and failure mode of each specimen were recorded. Data were analyzed with one-way ANOVA and LSD Post Hoc Test (${\alpha}=.05$). RESULTS. The fracture resistances of GE and GC were significantly lower than that of GI (P<.01), while no significant difference was found between GE and GC (P=.702). As of the failure mode, most of the specimens in GE and GC were unfavorable while a higher occurrence of favorable failure mode was presented in GI. CONCLUSION. For the restoration of mandibular premolar, endocrown shows no advantage in fracture resistance when compared with the conventional method. Both of the two methods cannot rehabilitate endodontically treated teeth with the same fracture resistances that intact mandibular premolars have.

• The korean journal of orthodontics
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• v.1 no.1
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• pp.15-20
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• 1970

The author investigated on the responses of pulp and dentine following tooth movements. The material consisted of fifty-four intact teeth from twenty-seven adult white rats. The half of the teeth were employed as controls and the other half served as experimental group. These teeth were moved with forces ranging from 30 grams to 120 grams for from 3 to 7 days. All these were extracted immediately after the force was relieved. The main pulp changes in the experiment were vacuolization of the pulp tissue and circulatory disturbances. The magnitude of the force had an important role. In addition to these changes, the resorption in dentine and cementum was observed, which was related to the magnitude of the force and the duration of experiment.

• The Journal of Advanced Prosthodontics
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• v.4 no.3
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• pp.134-138
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• 2012

PURPOSE. The study was conducted to evaluate the efficacy of implant supported tooth replacement in diabetic patients. MATERIALS AND METHODS. The study involved placement of implants (UNITI implants, Equinox Medical Technologies, Zeist, Holland, diameter of 3.7 mm and length 13 mm) in five diabetic patients (three females and two males) of age ranging from 35-65 years with acceptable metabolic control of plasma glucose. All patients included in the study were indicated for single tooth maxillary central incisor replacement, with the adjacent teeth intact. The survival of the restored implants was assessed for a period of three months by measurement of crestal bone heights, bleeding on probing and micro flora predominance. Paired t-test was done to find out the difference in the microbial colonization, bleeding on probing and crestal bone loss. P values of less than 0.05 were taken to indicate statistical significance. RESULTS. Results indicated that there was a significant reduction in bleeding on probing and colonization at the end of three months and the bone loss was not statistically significant. CONCLUSION. The study explores the hypothesis that patients with diabetes are appropriate candidates for implants and justifies the continued evaluation of the impact of diabetes on implant success and complications.

• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.2
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• pp.475-483
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• 1997

Fracture of the crown in a permanent incisor is relatively common. When it occurs with pulp exposure, it presents both restorative and endodontic problems. In the restoration of a fractured incisor, reattachment of the original fragment or restoration with a composite resin is preferred over a temporary crown. If fractured fragment is intact, the tooth can be restored with reattachment of the fragment. An exposed pulp in a young crown-fractured incisor is usually treated with either pulp capping or pulpotomy depending on the size of an exposure and time elapsed since injury. However, in teeth showing vital and/or hyperplastic pulp tissue at the exposure, only superficial layers of the pulp and surrounding dentin should be removed : i.e. partial pulpotomy can be performed in immature as well as mature teeth. This paper reports 2 cases of crown-fractured permanent incisors with pulp exposure that had been treated by reattachment of original fragment followed by partial pulpotomy or partial pulpectomy. The following results are obtained. ; 1. Fragment reattachment is an acceptable semi-permanent restoration of crown fractured young permanent incisor. 2. Partial pulpotomy is recommended as the treatment of choice in crown-fractured permanent teeth with pulp exposure.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.39
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• pp.29.1-29.5
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• 2017

Background: The surgical extraction of the third molar is the most frequently encountered procedure in oral and maxillofacial surgery and is related with a variety of complications. This study examined the efficacy of intentional partial odontectomy (IPO) in the third molars which have no periapical lesions and are located near important anatomical structures such as inferior alveolar nerve. Methods: Seven patients (four males, three females, $39.1{\pm}11.6years$), who received IPO to reduce the risk of inferior alveolar nerve injury (IANI), were followed long-term. The treated teeth were horizontally impacted third molars in the mandibular left (n = 5) or mandibular right (n = 4) areas and were all ankylosed with the surrounding alveolar bone. During the IPO, the bone around the crown was removed to expose the crown, and then the tooth was resected at cement-enamel junction (CEJ). Any secondary trauma to the healthy root was minimized and remained intact after primary suture. Results: The mean follow-up time was $63.2{\pm}29.8months$, and all sites showed good bone healing after the crown removal. Also, sensory abnormality was not found in any patients after IPO. In one patient, the bone fragments erupted 4 months after IPO. In other patient, an implant placed on second molar site adjacent to the third molar that received IPO was explanted about 2 years after the patient's persistent discomfort. Conclusions: In case where high risk of IANI exists, IPO may be chosen alternatively to surgical extraction to reduce the risk of nerve damage.

• Restorative Dentistry and Endodontics
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• v.44 no.1
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• pp.3.1-3.10
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• 2019

Objectives: It was the aim of this study to evaluate the effect of cooling water temperature on the temperature changes in the pulp chamber and at the handpiece head during high-speed tooth preparation using an electric handpiece. Materials and Methods: Twenty-eight intact human molars received a standardized occlusal preparation for 60 seconds using a diamond bur in an electric handpiece, and one of four treatments were applied that varied in the temperature of cooling water applied (control, with no cooling water, $10^{\circ}C$, $23^{\circ}C$, and $35^{\circ}C$). The temperature changes in the pulp chamber and at the handpiece head were recorded using K-type thermocouples connected to a digital thermometer. Results: The average temperature changes within the pulp chamber and at the handpiece head during preparation increased substantially when no cooling water was applied ($6.8^{\circ}C$ and $11.0^{\circ}C$, respectively), but decreased significantly when cooling water was added. The most substantial drop in temperature occurred with $10^{\circ}C$ water ($-16.3^{\circ}C$ and $-10.2^{\circ}C$), but reductions were also seen at $23^{\circ}C$ ($-8.6^{\circ}C$ and $-4.9^{\circ}C$). With $35^{\circ}C$ cooling water, temperatures increased slightly, but still remained lower than the no cooling water group ($1.6^{\circ}C$ and $6.7^{\circ}C$). Conclusions: The temperature changes in the pulp chamber and at the handpiece head were above harmful thresholds when tooth preparation was performed without cooling water. However, cooling water of all temperatures prevented harmful critical temperature changes even though water at $35^{\circ}C$ raised temperatures slightly above baseline.