Purpose: Recently, various metal primers have been developed, and these are known to increase the bond strength between metal and relining resin. In this study, the change in bond strength according to amount of thermocycling was evaluated. Materials and Methods: In this study, 216 specimens were fabricated. Tokuyama Rebase $II^{(R)}$(Tokuyama Corp., Japan) and $Kooliner^{(R)}$(GC America Inc., Japan) as relining material, and MR. $Bond^{(R)}$(Tokuyama Corp., Japan) and Alloy $Primer^{(R)}$(Kuraray Medical Inc., Japan) as a metal primers were used. Using Ni-Cr and various metal surface treatment methods, resin was bonded and the change in bond strength during thermocycling was measured. The data was analyzed by one-way ANOVA, t-test(p<.05 level of significance). Results: When comparing the groups with only sandblasting, rapid decrease in shear bond strength could be seen. In the groups using Tokuyama Rebase $II^{(R)}$, with the exception of the 1000 and 2000 cycle groups, each group showed statistically significant decrease in shear bond strength(p<0.05). In comparison according to relining materials, $Kooliner^{(R)}$ showed higher shear bond strength than Tokuyama Rebase $II^{(R)}$ in all groups. In groups using MR $bond^{(R)}$, $Kooliner^{(R)}$ had higher shear bond strength than Tokuyama Rebase $II^{(R)}$ but, there was no statistical significance(p<0.05). In the other groups, $Kooliner^{(R)}$ showed significantly higher shear bond strength(p<0.05). There was significant difference between groups with sandblasting and metal primer treatments(p<0.05). In comparison according to metal primer materials, Alloy $Primer^{(R)}$ showed the highest shear bond strength but there was no statistical significance(p>0.05). According to the number of thermocycling cycles, when using Tokuyama Rebase $II^{(R)}$, there were no significant differences between the 0, 1000 and 2000 cycle groups regardless of the type of metal primer. There were no differences between the 2000 and 3000 cycle groups. When using $Kooliner^{(R)}$, regardless of the type of metal primer, there were no significant differences between the 0, 1000, 2000 and 3000 cycle groups(p>0.05). Conclusion: The use of metal primers showed increase in bond strength, and the stability after to thermocycling has been authenticated. Thus, the use of metal primers in relining and rebasing of metal frameworks is essential. But when selecting the material various physical properties should be considered.

It is essential to establish the suitable position for artificial maxillary anterior teeth, because of not only esthetics, phonetics, mastication, but also optimal position of artificial posterior teeth for the construction of functional and esthetic prostheses. Anatomic landmarks have been used in the arrangement of artificial teeth. Such as incisive papilla and palatal rugae are useful landmarks for positioning occlusal rim and upper anterior artificial teeth because they are relatively stable and to be identified on master cast. Therefore, if average distance between maxillary anterior teeth and landmarks in dentate subjects are measured and applied, appropriate position of occlusal rim can be initially established. In this study, to present a guide to the position of the occlusal rim for upper anterior teeth of edentulous patients, horizontal distance between anatomic landmarks were measured. Maxillary casts were made in 72 Korean dentate subjects. Horizontal distance between central incisor and incisive papilla, between incisive papilla and intercanine line, and between primary palatine rugae and gingival margin of canine were measured on each cast. The results of this study were as follows ; 1. The mean distance from the incisal edge of central incisor to the posterior border of incisive papilla was 12.1 mm (Male 12.2 mm, Female 11.9 mm). 2. The mean distance between posterior border of incisive papilla and intercanine line was 3.5 mm (Male 3.4 mm, Female 3.6 mm / Left 3.6 mm, Right 3.4 mm). 3. The mean distance from the palatal gingival margin of canine to the lateral border of primary palatine rugae was 2.4 mm (Male 2.4 mm, Female 2.4 mm / Left 2.4 mm, Right 2.3 mm). 4. On all measured items, there were no significant differencies in measured values between male and female, and between left and right sides. (P>0.05).

The purpose of this study was to assess the stress-induced pattern at the supporting bone, the implant fixture, the abutment and the abutment screw according to a friction-fit joint (Astra; Model 1) or slip- fit joint (Frialit-2; Model 2) in the internal connection system under vertical and inclined loading using finite element analysis. In conclusion, in the internal connection system of the implant and the abutment connection methods, the stress-induced pattern at the supporting bone, the implant fixture, the abutment and the abutment screw according to the abutment connection form had difference among them, and the stress distribution pattern usually had a widely distributed tendency along the inner surface of the implant fixture contacting the abutment post. The magnitude of the stress distributed in the supporting bone, the implant fixture, the abutment and the abutment screw was higher in the friction-fit joint than in the slip-fit joint. But it is considered that the further study is necessary about how this difference in the magnitude of the stress have an effect on the practical clinic.

The purpose of this study was to evaluate interaction of restorative method according to amount of remaining clinical crown length. For the study, sixty healthy mandibular premolars with no dental caries were chosen. Specimens with clinical crown length of 1 mm, 2 mm, 3 mm above the cemento-enamel junction(CEJ) were prepared and root canal treatment was conducted using Ni-Ti rotaty files. Thirty specimens were restored with $LuxaCore^{(R)}$ and thirty were restored with casting posts. All specimens were restored with full coverage crowns and the fracture strength was teseted with the MTS universal testing marchine. The fracture pattern was observed by measuring the distance between CEJ and fracture line. From the results above, the fracture strength seems to be influenced more by amount of remaining clinical crown length than restorative method. Good prognosis could be expected, when more than 2mm of clinical crown length is retained. In the future, the further studies on restorative method, to increase fracture strength of teeth will be necessary.

The purpose of this study was to evaluate the most effective method for repairing the exfoliated resin teeth. The specimens were divided into five groups according to repair method and presence of retention holes. The groups were as follows Group1 : Control group Group2 : Sprinkle method with no retention holes Group3 : Sprinkle method with retention holes Group4 : Flask method with no retention holes Group5 : Flask method with retention holes The results were as follows. 1. According to shear bond strength, the value decreased in the order of group1, group5, group3, group2, group4 and there were significant difference between, each group except between group1 and groups5, group2 and group3, group2 and group4(p < 0.05). 2. According to observations of the exfoliation surface, group2 and 4 showed more failure in the denture base resin and repair resin interface, but in group1, 3 and 5 there were more mixed failures. From the results above, there were no significant difference between repair methods without retention holes. But when comparing groups with retention holes, the flask method showed significantly improved results compared to the sprinkle method. Especially, group5 showed similar results as the control group.

The purpose of this study was to compare the v-shape thread with the square shape thread of fixture in the view of stress distribution pattern using finite element stress analysis. The finite element model was designed with the parallel placement of two standard fixtures(4.0 mm diameter ${\times}$ 11.5 mm length) on the region of mandibular 1st and 2nd molars. Three dimensional finite element model was created with the components of the implant and surrounding bone. This study simulated loads of 200 N at the central fossa in a axial direction (load A), 200 N at the buccal offset load that is 2 mm apart from central fossa in a axial direction (load B), 200 N at the buccal offset load that was 4 mm apart from central fossa in a axial direction (load C). These forces of load A',B',C' were applied to a $15^{\circ}$ inward oblique direction at that same site with 200 N. Von Mises stress values were recorded and compared in the supporting bone, fixture, and abutment screw. The following results have been made based on this study : 1. The highest stress concentration occurred at the cervical region of the implant fixture. 2. Von Mises stress value of off-site region was higher than that of central fossa region. 3. Square shape thread type showed more even stress distribution in the vertical and oblique force than V-shape thread type. 4. Stress distribution was the most effective in the case of buccal offset load (2, 4 mm distance from central fossa) in the square shape thread type. 5. V-shape thread type revealed higher von Mises stress value than square shape thread type in all environmental condition. The results from numerical analyses concluded that square shape thread type had the lower destructive stress and more stress distribution between the fixture and bone interface than V-shape thread type. Therefore, square shape thread type was regarded as optimal thread configuration in biomechanical concepts.

The purpose of this study was to compare the stress distribution around the surrounding bone according to the splinted and non-splinted conditions on the finite element models of the two implant crowns with the different vertical bone level. The finite element model was designed with the parallel placement of the two fixtures ($4.0mm{\times}11.5mm$) with reverse buttress thread on the mandibular 1st and 2nd molars. As the bone quality, the inner cancellous bone and the outer 2 mm cortical bone were designed, and the cortical and cancellous bone were assumed to be perfectly bonded to the implant fixture. The splinted model(Model 1) had 2 mm contact surface and the non-splinted model(Model 2) had $8{\mu}m$ gap between two implant crowns. Two group (Splinted and non-splinted) was loaded with 200 N magnitude in the vertical and oblique directions on the loading point position on the central position of the crown, the 2 mm and 4 mm buccal offset point from the central position. Von Mises stress value was recorded and compared in the fixture-bone interface in the bucco-lingual and mesio-distal sections. The results were as follows; 1. In the vertical loading condition of central position, the stress was distributed on the cortical bone and the cancellous bone around the thread of the fixture in the splinted and non-splinted models. In the oblique loading condition, the stress was concentrated toward the cortical bone of the fixture neck, and the neck portion of 2nd molar in the non-splinted model was concentrated higher than that of 1st molar compared to the splinted model. 2. In the 2 mm buccal offset position of the vertical loading compared to the central vertical loading, stress pattern was shifted from apical third portion of the fixture to upper third portion of that. In the oblique loading condition, the stress was distributed over the fixture-bone interface. 3. In the 4 mm buccal offset position of the vertical loading, stress pattern was concentrated on the cortical bone around the buccal side of the fixture thread and shifted from apical third portion of the fixture to upper third portion of that in the splinted and non-splinted models. In the oblique loading, stresses pattern was distributed to the outer position of the neck portion of the fixture thread on the mesio-distal section in the splinted and non-splinted models. Above the results, it was concluded that the direction of loading condition was a key factor to effect the pattern and magnitude of stress over the surrounding bone of the fixture under the vertical and oblique loading conditions, although the type with or without proximal contact did not effect to the stress distribution.

There is no single or simple answer for effective communication between laboratory technician and clinical dentist. Love-hate could be used to describe the relationship between dentists and their labs. Great lab work can make a dentists life much easier and can result in getting many referrals. However, if the lab work is not up to par and/or late, it can add stress and agony to a dentists practice. Also the opposition is right. If the preparations are calibrated, the impressions clear, and the bite registrations accurate, most labs can do their work reasonably well. Unfortunately, many cases received by labs are barely adequate, especially when it comes to reading margins, which are frequently created by the imagination of the person trimming the dies. In other words, both dentists and lab technicians need to be able to understand how each party operates so that solutions to problems can be found. Effective communication with the laboratory is critical if any degree of success is desired.

Traditionally, the implant treatment require load-free healing period of at least 3 months in the mandible and 6 months in the maxilla. But this long healing period provides patients with the discomfort and economical trouble. Many experiments has been attempted for the outcome of such disadvantage, so recently the immediate loaded implant is getting popularity. Several literature has been published for clinical success of immediate loaded implant. The studies for the success rate of immediate loaded implant in multi-way has been reporting, nevertheless, we don't have yet a probable success. Various studies have been practiced that the advantages and disadvantages associated with immediate loaded implant, and factors that may influence the success of immediate implant, including patient selection, type of bone quality, required implant length, structure of the implant, surgical skill, need for achieving primary stability, control of occlusal force, peri-implant bone activity. The objective of this study is to review the literature related to immediate loading of implants and to discuss factors that may influence this treatment modality, based on scientific evidence.