• Journal of dental hygiene science
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• v.17 no.5
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• pp.423-432
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• 2017

This study aimed to investigate the effect of repeated oral health education on the oral health of preschool children. This study classified the control group of children of 5~6 years of age where the oral health education was conducted one time, and the experiment group where the oral health education was conducted 4 times. The oral health conditions of each group and their risk of developing dental caries were also assessed. No significant difference was observed in the participants in terms of general characteristics, oral health conditions, risk of developing dental caries, and oral health behavior after oral health education. The two groups did not show a significant difference (p<0.001) in dental plaque index before and after oral health education, and showed a significant difference (p<0.001) according to the number of education sessions. Before oral health education, the participants in both groups were brushing their teeth incorrectly. However, after the third session, 56.7% of the participants in the experimental group and 9.4% in the control group used the correct method of tooth brushing. A significant difference was observed between the two groups (p<0.05). In addition, when the tooth-brushing time was compared, the two groups showed a significant difference (p<0.001), and a significant difference was observed in terms of the number of education sessions (p<0.05). In summary, repeated oral health education had significant influences on the dental plaque index, tooth-brushing method, brushing occlusal surfaces, and tooth-brushing time. Therefore, when oral health education is carried out, repeated oral health education in children is more effective than one-time oral health education as reflected in the changes in dental plaque index and oral health behavior. Moreover, oral health education is considered effective in changing the oral health behavior of children when conducted at least 3 times.

• Journal of Periodontal and Implant Science
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• v.48 no.2
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• pp.124-134
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• 2018

Purpose: Clinicians must examine tooth wear to make a proper diagnosis. However, qualitative methosds of measuring tooth wear have many disadvantages. Therefore, this study aimed to develop and evaluate quantitative parameters using the cusp area and volume of virtual dental models. Methods: The subjects of this study were the same virtual models that were used in our former study. The same age group classification and new tooth wear index (NTWI) scoring system were also reused. A virtual occlusal plane was generated with the highest cusp points and lowered vertically from 0.2 to 0.8 mm to create offset planes. The area and volume of each cusp was then measured and added together. In addition to the former analysis, the differential features of each cusp were analyzed. Results: The scores of the new parameters differentiated the age and NTWI groups better than those analyzed in the former study. The Spearman ${\rho}$ coefficients between the total area and the area of each cusp also showed higher scores at the levels of 0.6 mm (0.6A) and 0.8A. The mesiolingual cusp (MLC) showed a statistically significant difference (P<0.01) from the other cusps in the paired t-test. Additionally, the MLC exhibited the highest percentage of change at 0.6A in some age and NTWI groups. Regarding the age groups, the MLC showed the highest score in groups 1 and 2. For the NTWI groups, the MLC was not significantly different in groups 3 and 4. These results support the proposal that the lingual cusp exhibits rapid wear because it serves as a functional cusp. Conclusions: Although this study has limitations due to its cross-sectional nature, it suggests better quantitative parameters and analytical tools for the characteristics of cusp wear.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.1
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• pp.67-76
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• 2020

With the evolution of the computer-aided design/computer-aided manufacturing (CAD/CAM) technology, the intraoral scanners are playing an increasingly important role, as they are the first step towards a completely digital workflow. The CAD/CAM double scanning technique has been used to transfer the information from provisional restorations to definitive restorations. In this case, a 67-year-old male with esthetically compromised anterior teeth, generalized severe attrition of teeth, and reduced vertical dimension was treated with full mouth rehabilitation including a re-establishment of the lost vertical dimension of occlusion assisted by the crown lengthening procedure. The provisional restorations were fabricated using an intraoral scanner and the CAD/CAM double scanning technique. After the period of adaption, the definitive monolithic zirconia restorations were delivered. The CAD/CAM double scanning technique successfully transferred the occlusal and morphological characteristics, obtained from the provisional restorations, to the definitive restorations.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.10 no.1
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• pp.63-68
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• 1980

The purpose of this article is to re-examine the roentgenographic appearance of alveolar osseous in an effort to determine the value of the orthopantomogram in the diagnosis of periodontal disease. A total of 158 osseous lesions from 13 human dry skulls were studied. 14 Ultra-speed periapical films, 2 bitewing films and Kodak panoramic film are used to obtain radiographs of all defects. The bisecting technic was used, with a target-film distance of. 8 inches and exposure factors of 70 kVp, 10MA and 0.4 sec. at anterior teeth, 0.6 see at posterior teeth in exposure time. For orthopantomogram, Panoura Eight-C was used with a exposure factors of 90kVp, 10MA. and 15sec. exposure time. All films were developed in a light. tight darkroom at 68°F for 4½ minutes. Comparison of orthopantomogram and intraoral films on the view-box was carefully studied in relation to the types of osseous defect visually evident; Proximal intraosseous defects, Interproximal craters, Interproximal hemisepta, Furcal defects on multirooted teeth, and Facial or Lingual one-walled defects. The results obtained were as follows; 1. Proximal osseous defects throughout the dental arches and furcal defects on facial and lingual surfaces of multirooted teeth can be identified with a high degree of accuracy from their orthopantomographic appearances. 2. Lesions on facial or lingual surface of the alveolar arches are rather difficult to locate or recognize on the dental radiographs. 3. In determining whether the proximal and furcal lesions are located facially or lingually, Orthopantomogram is superior to the conventional film Orthopantomogram obtained with standardization of head in proper position revealed the complete visualization of alveolar bone without showing occlusal surface of molars and proximal superimposition of teeth. Thus, on the standardized orthopantomograms, The roentgenographic characteristics of each defect were determined.

• Journal of Technologic Dentistry
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• v.38 no.4
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• pp.365-380
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• 2016

Purpose: The purpose of this study was to ascertain the need to reform curriculums for digital experts in a way that include the practical and educational aspects of dental labs by determining why educational reforms are needed to comply with changes in dental technology business that are brought by the applications of digital scanning and what changes are being actually brought by the use of CAD/CAM. Methods: This study analyzed the need of education and practice in relation to CAD/CAM by using the independent sample t-test and One-way ANOVA. in accordance with the participants demographic characteristics and job-related variables and factors related to CAD/CAM, and provided only some of the analysis results that were found statistically significant. Concerning the need of education and practice in relation to CAD/CAM, the study also used the independent sample t-test to measure difference in the perception of that need within each of the three groups, or those of job performance, job efficiency and knowledge gain at the signficance level of ${\alpha}=.05$. Results: Dental technologists surveyed here were perceiving that the use of CAD/CAM would bring changes in their job performance, job efficiency and knowledge gain. They were expecting that the biggest changes would be made in work climate and product quality as sub-areas of job performance. However, they said that in terms of job efficiency, the use of CAD/CAM would change job contribution, job satisfaction and job efficiency, but not lead to staffing. These results suggest that more special programs for CAD/CAM education are needed to bring up CAD/CAM experts who are more specialized. Conclusion: Among 13 skills related to CAD/CAM, what is most needed to be educated to dental technologists was "molding the occlusal surface" (M=4.19), followed by "designing the 3-D work" (M=4.17), "final shape modification" (M=4.16), "molding the border" (M=4.15) and "checking the fit of prothesis" (M=4.14) in order.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.346-355
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• 1999

To evaluate the micro leakage of compomer, 4 materials were divided into 4 groups of 15 cavities each.(Group 1: Z-100, Group 2: Dyarct AP, Group 3: Fuji II LC, Group 4: Compoglass) After the class II cavities were prepared using carbide bur No. 553, all specimen were restored by incremental filling technique. In group 3, Z-100 was filled with a base of a light curing glass-ionomer. After 7 days, all specimens were thermocycled between $5^{\circ}C$ and $55^{\circ}C$ for 500 cycles, followed by placement in 50% silver nitrate dye for 2 hours at $37^{\circ}C$. After rinsed in distilled water, these teeth were immersed in photodeveloping solution and exposed to fluorescent light for 6 hours. Teeth were then washed in distilled water to remove the photodeveloping solution, sectioned mesio-distally and evaluated. The results were as follows : 1. In the cervical portion, there was significant difference between Fuji II LC and other groups(Z-100, Dyract AP, Compoglass), Fuji II LC had the least value.(p<0.05) 2. In the cervical portion, there was not significant difference among Dyract AP, Z-100 and Compoglass. 3. In the occlusal portion, there was not significant difference among Dyract AP, Z-100 and Compoglass. From the results above, In enamel, microleakage of compomer such as Dyract AP and Compoglass resemble to that of composite resin. It is thought that it is due to characteristics of composite resin portion of compomer. But in dentin, microleakage of compomer is higher than that of resin modified glass ionomer cement, it is thought that in compomer, acid-base reaction is not developed with dentin.

• Restorative Dentistry and Endodontics
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• v.26 no.6
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• pp.464-484
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• 2001

When restoring a tooth, the dentist tries to choose the ideal material for existing situation. One criterion that is considered is its suitability for restoring coronal strength. As more tooth structure is removed, the cusps are weakened and susceptible to fracture. Further, this increased deformation may cause the formation of intermittent gaps at the margin between the hard tissue and the restoration, facilitating marginal leakage. The improvements in ceramic materials now make it possible for alternatives to amalgams, composites, and cast metal to be of offered for posterior teeth. Of the materials used, ceramics most closely approximates the properties of enamel. The introduction of computer-aided design/computer-aided manufacture(CAD/CAM) systems to restorative dentistry represents a major technological breakthrough. It is possible to design and fabricate ceramic restorations at a single appointment. Additionally, CAD/CAM systems eliminate certain errors and inaccuracies that are inherent to the indirect method and provide an esthetic restoration. The aim of this investigation was to study the loading characteristics of CAD/CAM ceramic inlay and to compare the stress distribution and displacement associated with different designs of cavity(the isthmus width and cavity depth). A human maxillary left first premolar was prepared with standard mesio-occlusal cavity preparation, as recommended by the manufacturer Ceramic inlay was fabricated with CEREC 2 CAD/CIM equipment and cemented into the prepared cavity. Three dimensional model was made by the serial photographic method. The cavity width was varied $\frac{1}{3}$, $\frac{1}{2}$ and $\frac{2}{3}$ of intercuspal distance between buccal and lingual cusp tip. The cavity depth was varied 1.5mm and 2.3mm. So six models were constructed to simulate six conditions. A point load of 500N was applied vertically onto the first node of the lingual slope from the buccal cusp tip. The stress distribution and displacement were solved using ANSYS finite element program(Swanson Analysis System). (omitted)

• The korean journal of orthodontics
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• v.51 no.6
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• pp.375-386
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• 2021

Objective: To evaluate the accuracy of a one-piece bracket jig system fabricated using computer-aided design and manufacturing (CAD/CAM) by employing three-dimensional (3D) digital superimposition. Methods: This in vitro study included 226 anterior teeth selected from 20 patients undergoing orthodontic treatment. Bracket position errors from each of the 40 arches were analyzed quantitatively via 3D digital superimposition (best-fit algorithm) of the virtual bracket and actual bracket after indirect bonding, after accounting for possible variables that may affect accuracy, such as crowding and presence of the resin base. Results: The device could transfer the bracket accurately to the desired position of the patient's dentition within a clinically acceptable range of ± 0.05 mm and 2.0° for linear and angular measurements, respectively. The average linear measurements ranged from 0.029 to 0.101 mm. Among the angular measurements, rotation values showed the least deviation and ranged from 0.396° to 0.623°. Directional bias was pronounced in the vertical direction, and many brackets were bonded toward the occlusal surface. However, no statistical difference was found for the three angular measurement values (torque, angulation, and rotation) in any of the groups classified according to crowding. When the teeth were moderately crowded, the mesio-distal, bucco-lingual, and rotation measurement values were affected by the presence of the resin base. Conclusions: The characteristics of the CAD/CAM one-piece jig system were demonstrated according to the influencing factors, and the transfer accuracy was verified to be within a clinically acceptable level for the indirect bracket bonding of anterior teeth.

• Journal of Dental Rehabilitation and Applied Science
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• v.40 no.2
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• pp.39-45
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• 2024

The residual alveolar ridge below the denture base undergoes physiologic changes over time, which results in the existing dentures becoming less accurate with the residual alveolar ridge. In addition, changes of the occlusal plane, decreasing in vertical dimension and loss of denture retention and facial support can occur. Consequently, denture relining may be required to accommodate these changes and ensure an ongoing close fit. Relining a denture can be performed directly on the chairside using autopolymerizing relining materials or indirectly in the laboratory using heat-cured relining materials. A direct relining method is not only simple but also time and cost effective. However, irritation or burning sensation of the mucosa can occur, and poor bonding of the relining material to the denture base can be cited as disadvantages. The indirect relining method exhibits relatively high bonding strength between the relining material and the denture base, but the patient might experience discomfort during relining process period. This report will examine the characteristics of relining materials, including those used in the relining of CAD-CAM dentures, and explore the clinical considerations for relining procedures.

• The Journal of Advanced Prosthodontics
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• v.16 no.1
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• pp.12-24
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• 2024

PURPOSE. This study aimed to evaluate the maximum vertical wear, volume wear, and surface characteristic of antagonist enamel, opposing monolithic zirconia or lithium disilicate crowns. MATERIALS AND METHODS. The study comprised 24 participants (n = 12), who were randomly allocated to receive either a 5 mol% Y-TZP or a lithium disilicate crown in positions which would oppose the natural first molar tooth. The contralateral first molar along with its antagonist was considered as the enamel opposing natural enamel control. Data collection was performed using an intraoral scanner and polyvinylsiloxane impression. The means of the maximum vertical loss and the volume loss at the occlusal contact areas of the crowns and the various natural antagonists were measured by 3D comparison software. A scanning electron microscope was subsequently used to assess the wear characteristics. RESULTS. The one-year results from 22 participants (n = 11) indicated no significant differences when comparing the zirconia crown's antagonist enamel (40.28 ± 9.11 ㎛, 0.04 ± 0.02 mm³) and the natural enamel wear (38.91 ± 7.09 ㎛, 0.04 ± 0.02 mm³) (P > .05). Also, there is no significant differences between lithium disilicate crown's antagonist enamel (47.81 ± 9.41 ㎛, 0.04 ± 0.02 mm³) and the natural enamel wear (39.11 ± 7.90 ㎛, 0.04 ± 0.02 mm³) (P > .05). CONCLUSION. While some studies suggested that monolithic zirconia caused less wear on opposing enamel than lithium disilicate, this study found similar wear levels to enamel for both materials compared to natural teeth.