• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.4
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• pp.366-376
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• 2013

The purpose of this study is to evaluate the marginal and internal fit of coping made by CAD/CAM using different scanning methods. Zirconia coping was made by each CAD/CAM system followed by intra-oral scanning, model optical scanning and model contact scanning. It was embedded into Epoxy Resin and was cut by buccal to lingual. AMD (Absolute marginal discrepancy), MG (Marginal gap), GA (Gap of axial), GL (Gap of line angle) and GO (Gap of occlusal) of each sample were measured. The result is as followed; 1. The mean value of AMD in Group 1, Group 2, Group 3 are $141.21{\pm}42.94{\mu}m$, $140.63{\pm}31.64{\mu}m$, $109.37{\pm}28.42{\mu}m$. The averages of MG in Group 1, Group 2, Group 3 are $82.52{\pm}43.99{\mu}m$, $90.28{\pm}27.93{\mu}m$, $66.55{\pm}28.77{\mu}m$. Statistically there is no difference in AMD and MG among the three Groups (Anova, P>0.05). 2. GA of Group 2 revealed statistically difference compared with Group 1 and Group 3 (Anova, P<0.05). 3. GL and GO of Group 1 showed statistically significant differences compared with Group 2 and Group 3 (Mann-whitney test (P<0.05). Zirconia copings made by 3 ways of scanning methods have no difference with conventional ceramics in AMD and MG which are known as the most important factors.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.1
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• pp.16-22
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• 2014

Purpose: The purpose of this study was to assess the marginal and mesial fitness of zirconia single copings and 3-unit fixed partial dentures (FPDs) manufactured with an identical model. Materials and Methods: An epoxy model in which the maxillary right 2nd premolar is lost and maxillary 1st premolar and 2nd molar are formed as abutments was manufactured and scanned by using a laser scanner. A ten units of zirconia single copings were manufactured for maxillary 1st premolar and 2nd molar, respectively and the same number of 3-unit FPDs were manufactured. For the measurements of fitness, the manufactured silicone replicas were divided into four parts and the fitness were measured by digital microscope at measurement points (P1, P2, P3, P4 and P5) of each plane. The measured gaps were classified into three categories: marginal gap (MG, P1), axial gap (AG, average of P2 and P3), occlusal gap (OG, average of P4 and P5). Results: The ranges of MG, AG and OG for single copings were 18.47 - 40.54 ${\mu}m$, 39.73 - 73.61 ${\mu}m$ and 116.90 - 134.69 ${\mu}m$, respectively. The ranges of MG, AG and OG for 3-unit FPDs were 45.95 - 87.44 ${\mu}m$, 23.78 - 57.00 ${\mu}m$ and 99.89 - 131.06 ${\mu}m$, respectively. Conclusion: The result of the study shows that the MGs for 3-unit FPDs were higher than those of single copings, though they are within the range of clinical acceptance, indicating that the use of more homogeneous zirconia block and modification of sintering processes are needed to ensure the prevention of increase of gap in 3-unit FPDs.

• The Journal of Advanced Prosthodontics
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• v.8 no.6
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• pp.439-448
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• 2016

PURPOSE. The purposes of this study are to evaluate the internal and marginal adaptation of two widely used CAD/CAM systems and to study the effect of porcelain press veneering process on the prosthesis adaptation. MATERIALS AND METHODS. Molar of a lower jaw typodont resin model was prepared by adjusting a 1.0 mm circumferential chamfer, an occlusal reduction of 2.0 mm, and a $5^{\circ}$ convergence angle and was duplicated as an abrasion-resistant master die. The monolithic crowns and copings were fabricated with two different CAD/CAM system-Ceramil and Zirkonzahn systems. Two kinds of non-destructive analysis methods are used in this study. First, weight technique was used to determine the overall fitting accuracy. And, to evaluate internal and marginal fit of specific part, replica technique procedures were performed. RESULTS. The silicone weight for the cement space of monolithic crowns and copings manufactured with Ceramil system was significantly higher than that from Zirkonzahn system. This gap might cause the differences in the silicone weight because the prostheses were manufactured according to the recommendation of each system. Marginal discrepancies of copings made with Ceramil system were between 106 and $117{\mu}m$ and those from Zirkonzahn system were between 111 and $115{\mu}m$. Marginal discrepancies of copings made with Ceramil system were between 101 and $131{\mu}m$ and those from Zirkonzahn system were between 116 and $131{\mu}m$. CONCLUSION. Marginal discrepancy was relatively lower in Ceramil system and internal gap was smaller in Zirkonzahn system. There were significant differences in the internal gap of monolithic crown and coping among the 2 CAD/CAM systems. Marginal discrepancy produced from the 2 CAD/CAM systems were within a reported clinically acceptable range of marginal discrepancy.

• Restorative Dentistry and Endodontics
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• v.29 no.3
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• pp.205-211
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• 2004

This study evaluated the microleakage and interfacial gap between enamel and composite resin under the dry and wet condition of the enamel surface. V shaped class 5 cavities were prepared on the occlusal portion of extracted human molars. Samples were divided into three groups：D group (air dry for 10-15s), BD group (blot dry with moist cotton pellet), and DR group (air dry for 10-15s and rewet with Aqua-Prep F for 20s), Cavities were filled using Aelitefil composite resin after applied One-Step. Microleakage was tested by 2% methylene blue dye solution and the data were statistically analysed by Kruskal-Wallis test and Mann-Whitney test. Also Enamel-resin interface was observed under SEM. Group BD showed statistically lower microleakage than group D (p < 0.05). but there was no statistically significant difference between group BD and DR (p > 0.05). At the enamel-resin interface, group D showed the gap of $2{\;}{\mu}m$ thickness, but group BD and DR showed close adaptation. In conclusion, the use of blot dry and rewetting agent (Aqua-Prep F) resulted in decreased microleakage and improved adhesion between enamel and resin when using One-Step.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.1
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• pp.15-23
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• 2011

This is the fourth series of article on dental occlusal relationship to TMD and systemic symptoms. In this part of the series, Myodontics theory is overviewed and its theoretical background, treatment sequence and methods are presented.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.5
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• pp.622-632
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• 2005

Statement of problem: Silicone Index Tooth Tray impression system which does not use gingicord has a shortcoming. It takes time to remove internal wall of Silicone Index Tooth Tray for space of wash impression material. Purpose: This study was to evaluate whether providing certain space to impression body can prevent from doing complicated laboratory work. Material and methods: After mounting metal dies with shoulder and chamfer margins arbiturarily, SITT was produced using $Blu-mousse^(R)$. In one experimental group, wash impression was taken using $Fit-tester^(R)$ without removing interior surface of SITT and in the other group, wash impression was taken using $Fit-tester^(R)$ providing 0.5mm space in the SITT and then compared the differences in two groups. Results: 1. There was no significant difference between a group which did not allow space and a group which granted equal 0.5mm space. 2. There was no significant difference between gingival diameter, occlusal diameter of metal die that has shoulder margin and gingival diameter, occlusal diameter of metal die that has chamfer margin. 3. There was no significant difference between a group which did not take pick-up impression and a group which took pick-up impression through relining method using SITT 4. There was no significant difference between a group that poured immediately after taking primary impression and a group that poured after removing poured stone die. Conclusions: When taking an impression of an abutment using SITT impression system, it is considered to obtain clinically identical results between a group that did not grant a 0.5mm space within SITT for wash impression and a group which invest a space. Furthermore, it is considered possible to produce an individual die through secondary pouring.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.2
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• pp.336-347
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• 2006

Pit and fissure sealants has been proven as safe and effective method of caries prevention. But improper application of pit and fissure sealant may masking the caries process in occlusal fissure. Dentists have to understand the correct and exact application method of pit and fissure sealant for he good result of caries prevention. A key factor to enhanced the effectiveness of caries prevention is retention of pit and fissure sealant. Deep penetration of material into fissure and least marginal leakage around the fissure orifice are the major concerns for dentists to achieve the successive application of pit and fissure sealants. This paper reviewed the literature on the pit and fissure sealants under the following subtitles for enhanced retention : (1) application timing, (2) Indication, (3) Occlusal prophylaxis, (4) Materials, (5) Penetration, (5) Recall check Dental profession must perform the exact application of pit and fissure sealant because this procedure is one of the most technique-sensitive one in dental field.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.732-743
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• 1995

The purpose of this study was to evaluate the adaptation of light cured dentin bonding agents to tooth structure by measuring contraction gaps on interfaces between cavity wall and composite resin under SEM study. In this study, class V cavities with cementum margin were prepared on the buccal surfaces of 15 extracted human premolar teeth and teeth were randomly assigned 3 groups of 5 teeth each. The cavities were filled with three dentin bonding agents and two composite resins were investigated for this study: three dentin bonding agents; Scotchbond 2, Scotchbond Multi-Purpose. All-Bond 2, two composite resins; Silux Pius, Z-100. Group 1 : Scotchbond 2 + Silux Plus Group 2 : Scotchbond Multi~Purpose + Z-100 Group 3 : All-Bond 2 + Z-100 The restored teeth were stored in 100% relative humidity at $37^{\circ}C$ for 7 days. And then, the roots of the teeth were removed with the tapered fissure bur and the remaining crowns were sectioned occlusogingivally through the center of restorations. Adaptation at tooth-restoration interface was assesed occlusally, gingivally, and axially by scanning electron microscope. The results were as follows : 1. In Group 1, the adaptation to dentinal wall of Scotchbond 2 was poor, but the adaptation to enamel wall of Scotchbond 2 was excellent. 2. In Group 2, the adaptation to occlusal was axial wall and gingival wall of Scotchbond Multi-Purpose was excellent. Especially in axially wall, the dentin bonding agents infiltrated into dentinal tubules and there was excellent adaptation to dentinal wall. 3. In Group 3, the adaptation to occlusal wall and axial wall of All-Bond 2 was excellent. But in gingival wall, there was gap formation between composite resin and dentin bonding agent.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.42 no.3
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• pp.144-150
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• 2016

Objectives: We compared the transbuccal and transoral approaches in the management of mandibular angle fractures. Materials and Methods: Sixty patients with mandibular angle fractures were randomly divided into two equal groups (A, transoral approach; group B, transbuccal approach) who received fracture reduction using a single 2.5 mm 4 holed miniplate with a bar using either of the two approaches. Intraoperatively, the surgical time and the ease of surgical assess for fixation were noted. Patients were followed at 1 week, 3 months, and 6 months postoperatively and evaluated clinically for post-surgical complications like scarring, infection, postoperative occlusal discrepancy, malunion, and non-union. Radiographically, the interpretation of fracture reduction was also performed by studying the fracture gap following reduction using orthopantomogram tracing. The data was tabulated and subjected to statistical analysis. A P -value less than 0.05 was considered significant. Results: No significant difference was seen between the two groups for variables like surgical time and ease of fixation. Radiographic interpretation of fracture reduction revealed statistical significance for group B from points B to D as compared to group A. No cases of malunion/non-union were noted. A single case of hypertrophic scar formation was noted in group B at 6 months postsurgery. Infection was noted in 2 patients in group B compared to 6 patients in group A. There was significantly more occlusal discrepancy in group A compared to group B at 1 week postoperatively, but no long standing discrepancy was noted in either group at the 6 months follow-up. Conclusion: The transbuccal approach was superior to the transoral approach with regard to radiographic reduction of the fracture gap, inconspicuous external scarring, and fewer postoperative complications. We preferred the transbuccal approach due to ease of use, minimal requirement for plate bending, and facilitation of plate placement in the neutral mid-point area of the mandible.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.210-217
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• 2016

Purpose: The aim of this study was to evaluate the marginal and internal adaptation of monolithic zirconia restoration made without physical model by digital intraoral scanner. Materials and methods: A prospective clinical trial was performed on 11 restorations as a pilot study. The monolithic zirconia restorations were fabricated after digital intraoral impression taking by intraoral scanner (TRIOS, 3shape, Copenhagen, Denmark), computer-aided designing, and milling manufacturing process. Completed zirconia crowns were tried in the patients' mouth and a replica technique was used to acquire the crown-abutment replica. The absolute marginal discrepancy, marginal gap, and internal gap of axial, line angle, and occlusal part were measured after sectioning the replica in the mesiodistal and buccolingual direction. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U test (${\alpha}=.05$). Results: From the adaptation analysis by replica, the statistically significant difference was not found between mesiodistal and buccolingual sections (P>.05), but there was significant difference among the measurement location (P<.01). The amount of absolute marginal discrepancy was larger than those of marginal gap and internal gap (P<.01). Conclusion: Within the limitations of this study, the adaptation accuracy of model-free monolithic zirconia restoration fabricated by intraoral scanner exhibited clinically acceptable result. However, the margin of zirconia crown showed tendency of overcontour and cautious clinical application and follow up is necessary.