When a tooth shows discoloration and does not respond to the cold test or electric pulp test (EPT) after a traumatic injury, its diagnosis can be even more difficult due to the lack of proper diagnostic methods to evaluate its vitality. In these case reports, we hope to demonstrate that ultrasound Doppler might be successfully used to evaluate the vitality of the tooth after trauma, and help reduce unnecessary endodontic treatments. In all three of the present cases, the teeth were discolored after traumatic injuries and showed negative responses to the cold test and EPT. However, they showed distinctive vital reactions in the ultrasound Doppler test during the whole observation period. In the first case, the tooth color returned to normal, and the tooth showed a positive response to the cold test and EPT at 10 wk after the injury. In the second case, the tooth color had returned to its normal shade at 10 wk after the traumatic injury but remained insensitive to the cold test and EPT. In the third case, the discoloration was successfully treated with vital tooth bleaching.

It is often presumed that apical periodontitis follows total pulp necrosis, and consequently root canal treatment is commonly performed. Periapical lesion development is usually caused by bacteria and its byproduct which irritate pulp, develop pulpitis, and result in necrosis through an irreversible process. Afterwards, apical periodontitis occurs. This phenomenon is observed as an apical radiolucency in radiographic view. However, this unusual case presents a spontaneous healing of periapical lesion, which has developed without pulp necrosis in a vital tooth, through conservative treatment.

Complications resulting from condylar fracture include occlusal disturbance due to loss of leverage from temporomandibular joint (TMJ). In general, closed reduction with active physical training has been performed, and under favorable circumstances, adaptation occurs in attempt to restore the articulation. The patient in this case report had unilateral condylar fracture accompanied with multiple teeth injuries, but he was left without any dental treatment for 1 mon which led to unrestorable occlusal collapse. Fortunately, delayed surgical repositioning of dislocated maxillary anterior teeth followed by consistent long-term physical training has been proved successful. Normal occlusion and satisfactory remodeling of condyle were obtained on 10 mon follow-up.

The development of subcutaneous emphysema is a well-known complication that has been reported after dental extraction, endodontic treatment, or restorative preparation. Gaseous invasion, leading to swelling, crepitus on palpation, is commonly restricted to the connective tisssues immediately adjacent to the entry site. However, the use of compressed air- and water-cooled turbines may allow large amounts of air and water to be driven through the fascial planes into the mediastinum, pleural space, or even the retroperitoneum.

This case report is about the patient who presented with subcutaneous emphysema that occurred after fracture line inspection. Possible cause, treatment, and prevention of emphysema will be discussed.

The purpose of this study was to determine the effect of post types and sizes on fracture resistance in immature tooth model with various restorative techniques. Bovine incisors were sectioned 8 mm above and 12 mm below the cementoenamel junction to simulate immature tooth model. To compare various post-and-core restorations, canals were restored with gutta-percha and resin core, or reinforced dentin wall with dual-cured resin composite, followed by placement of D.T. LIGHT-POST, ParaPost XT, and various sizes of EverStick Post individually. All of specimens were stored in the distilled water for 72 hours and underwent 6,000 thermal cycles. After simulation of periodontal ligament structure with polyether impression material, compressive load was applied at 45 degrees to the long axis of the specimen until fracture was occurred.

Experimental groups reinforced with post and composite resin were shown significantly higher fracture strength than gutta-percha group without post placement (p < 0.05). Most specimens fractured limited to cervical third of roots. Post types did not influence on fracture resistance and fracture level significantly when cement space was filled with dual-cured resin composite. In addition, no statistically significant differences were seen between customized and standardized glass fiber posts, which cement spaces were filled with resin cement or composite resin individually. Therefore, root reinforcement procedures as above in immature teeth improved fracture resistance regardless of post types and sizes.

The purpose of this study is to observe and compare the remineralization tendencies of artificial enamel caries lesion by remineralization solutions of different degree of saturations at pH 5.5, using a polarizing microscope and computer programs (Photoshop, Image pro plus, Scion Image, Excel).

For this study, 48 sound permanent teeth with no signs of demineralization, cracks, or dental restorations were used. The specimens were immersed in lactic acid demineralization solution for 2 days in order to produce artificial dental caries that consist of surface and subsurface lesions. Each of 9 or 10 specimens was immersed in pH 5.5 lactic acid buffering remineralization solution of four different degrees of saturation (0.507, 0.394, 0.301, and 0.251) for 12 days. After the demineralization and remineralization, images were taken by a polarizing microscope (×100). The results were obtained by observing images of the specimens, and using computer programs, the density of caries lesions were estimated.

While the group with the lowest degree of saturation (0.251) showed total remineralization feature from the surface to the subsurface of the lesion, the group with the highest degree of saturation (0.507) showed demineralization mainly on the surface of the lesion at the constant organic acid concentration 0.01 M and pH 5.5.

The purpose of this study is to observe and compare the remineralization tendencies of artificially demineralized enamel by remineralization solutions of different degree of saturations at pH 5.5, using a polarizing microscope and computer programs (Photoshop, Image pro plus, Scion Image, Excel).

For this study, 36 sound permanent teeth with no signs of demineralization, cracks, or dental restorations were used. The specimens were immersed in lactic acid demineralization solution for 3 days in order to produce dental caries artificially that consist of surface and subsurface lesions. Each of 9 or 10 specimens was immersed in pH 5.5 lactic acid buffered remineralization solution of three different degrees of saturation (0.25, 0.30, 0.35) for 12 days. After the demineralization and remineralization, images were taken by a polarizing microscope (× 100). The results were obtained by observing images of the specimens, and using computer programs, the density of caries lesions were determined.

In conclusion, in the group with the lowest degree of saturation, remineralization occurred thoroughly from the surface to the subsurface lesion, whereas in the groups with greater degree of saturation showed no significant change in the subsurface lesion, although there was corresponding increase in the remineralization width on the surface zones.

The aim of this research was to study the effect of intermittent polymerization on marginal adaptation by comparing the marginal adaptation of intermittently polymerized composite to that of continuously polymerized composite.

The materials used for this study were Pyramid (Bisco Inc., Schaumburg, U.S.A.) and Heliomolar (Ivoclar Vivadent, Liechtenstein). The experiment was carried out in class II MOD cavities prepared in 48 extracted human maxillary premolars. The samples were divided into 4 groups by light curing method; group 1- continuous curing (60s light on with no light off); group 2- intermittent curing (cycles of 3s with 2s light on & 1s light off for 90s); group 3- intermittent curing (cycles of 2s with 1s light on & 1s light off for 120s); group 4- intermittent curing (cycles of 3s with 1s light on & 2s light off for 180s). Consequently the total amount of light energy radiated was same in all the groups. Each specimen went through thermo-mechanical loading (TML) which consisted of mechanical loading (720,000 cycles, 5.0 kg) with a speed of 120 rpm for 100 hours and thermocycling (6000 thermocycles of alternating water of 50℃ and 55℃). The continuous margin (CM) (%) of the total margin and regional margins, occlusal enamel (OE), vertical enamel (VE), and cervical enamel (CE)) was measured before and after TML under a × 200 digital light microscope.

Three-way ANOVA and Duncan's Multiple Range Test was performed at 95% level of confidence to test the effect of 3 variables on CM (%) of the total margin: light curing conditions, composite materials and effect of TML. In each group, One-way ANOVA and Duncan's Multiple Range Test was additionally performed to compare CM (%) of regions (OE, VE, CE).

The results indicated that all the three variables were statistically significant (p < 0.05). Before TML, in groups using Pyramid, groups 3 and 4 showed higher CM (%) than groups 1 and 2, and in groups using Heliomolar, groups 3 and 4 showed higher CM (%) than group 1 (p < 0.05). After TML, in both Pyramid and Heliomolar groups, group 3 showed higher CM (%) than group 1 (p < 0.05). CM (%) of the regions are significantly different in each group (p < 0.05). Before TML, no statistical difference was found between groups within the VE and CE region. In the OE region, group 4 of Pyramid showed higher CM (%) than group 2, and groups 2 and 4 of Heliomolar showed higher CM (%) than group 1 (p < 0.05). After TML, no statistical difference was found among groups within the VE and CE region. In the OE region, group 3 of Pyramid showed higher CM (%) than groups 1 and 2, and groups 2,3 and 4 of Heliomolar showed higher CM (%) than group 1 (p < 0.05).

It was concluded that intermittent polymerization may be effective in reducing marginal gap formation.

The purpose of the present study was to evaluate the relationship between the amount of cuspal deflection and linear polymerization shrinkage in resin composite and polyacid modified resin composite. For cuspal defelction and shrinkage measurement, Dyract AP, Compoglass F, Z100, Surefil, Pyramid, Synergy Compact, Heliomolar and Heliomolar HB were used.

For measuring polymerization shrinkage, a custom made linometer (R&B, Daejon, Korea) was used. The amount of shrinkage among materials was compared using One-way ANOVA analysis and Tukey's test at the 95% of confidence level.

For measuring cuspal deflection of teeth, standardized MOD cavities were prepared in extracted maxillary premolars. After a self-etching adhesive was applied, cavities were bulk filled with one of the filling materials.Fifteen teeth were used for each material. Cuspal deflection was measured by a custom made cuspal-deflection measuring device. One-way ANOVA analysis and Tukey's test were used to determine differences between the materials at the 95% of confidence level.

Correlation of polymerization shrinkage and cuspal deflection were analyzed by regression analysis.

The amount of polymerization shrinkage from least to greatest was Heliomolar, Surefil < Heliomolar HB < Z100, Synergy Compact < Dyract AP < Pyramid, Compoglass F (p < 0.05).

The amount of cuspal deflection from least to greatest was Z100, Heliomolar, Heliomolar HB, Synergy Compact Surefil < Compoglass F < Pyramid, Dyract AP (p < 0.05).

The amount of polymerization shrinkage and cuspal deflection showed a correlation (p < 0.001).

The purpose of present study was to evaluate the polymerization shrinkage stress and cuspal deflection in maxillary premolars resulting from polymerization shrinkage of composites and compomers.

Composites and compomers which were used in this study were as follows: Dyract AP, Z100, Surefil, Pyramid, Synergy Compact, Heliomolar, Heliomolar HB, and Compoglass F. For measuring of polymerization shrinkage stress, Stress measuring machine (R&B, Daejon, Korea) was used. One-way ANOVA analysis with Duncan's multiple comparison test were used to determine significant differences between the materials.

For measuring of cuspal deflection of tooth, MOD cavities were prepared in 10 extracted maxillary premolars. And reduction of intercuspal distance was measured by strain measuring machine (R&B, Daejon, Korea) One-way ANOVA analysis with Turkey test were used to determine significant differences between the materials.

Polymerization shrinkage stress is 『Heliomolar, Z100, Pyramid < Synergy Compact Compoglass F < Dyract AP < Heliomolr HB, surefil』 (P < 0.05). And cuspal delfelction is 『Z100, Heliomolar, Heliomolar HB, Synergy Compact Surefil, < Compoglass F < Pyramid, Dyract AP』 (P < 0.05).

Measurements of ploymerization shrinkage stress and those of cuspal deflection of the teeth was different. There is no correlation between polymerization shrinkage stress and cuspal deflection of the teeth (p > 0.05).

The aim of this study was to measure and compare the micro shear bond strengths of the following dentin bonding systems to the dentin surfaces under simulated pulpal pressure; All Bond 2®, Second®, AdheSE®, Adper Prompt L-Pop®. The occlusal surfaces of 180 extracted human molars were prepared so the dentin bonding surfaces could be exposed. The teeth were randomly assigned to 3 equal groups of 60 each and subdivided. The dentin surfaces were treated with the above mentioned bonding system and resin composite cylinders were built up under a simulated pulpal pressure when saline (Group II) or diluted bovine serum (Group III) was used as the pulpal fluid. As a control, the same procedures were performed in the dried dentin surfaces (Group I). After one day of storage in water, the micro shear bond strengths were measured using an EZ tester. Group II and III showed significantly lower shear bond strength than Group I statistically (p < 0.05). SEbond® and AdheSE® showed no difference among the different dentin condition. In the Adper Prompt L-Pop®, a simulated pulpal pressure were applied to the specimens using diluted bovine serum, which showed a higher strength than the specimens in which saline was used (p < 0.05).

This study evaluated the effectiveness of the light emitting diode(LED) units for composite curing. To compare its effectiveness with conventional quartz tungsten halogen (QTH) light curing unit, the microhardness of 2mm composite, Z250, which had been light cured by the LEDs (Ultralume LED2, FreeLight, Developing product D1) or QTH (XL 3000) were compared on the upper and lower surface. One way ANOVA with Tukey and Paired t-test was used at 95% levels of confidence. In addition, the amount of linear polymerization shrinkage was compared between composites which were light cured by QTH or LEDs using a custom-made linometer in 10s and 60s of light curing, and the amount of linear polymerization shrinkage was compared by one way ANOVA with Tukey.

The amount of polymerization shrinkage at 10s was

XL3000 > Ultralume 2, 40, 60> FreeLight, D1 (P<0.05)

The amount of polymerization shrinkage at 60s was

XL3000 > Ultralume 2, 60> Ultralume 2,40> FreeLight, D1 (P<0.05)

The microhardness on the upper and lower surface was as follows;

It was concluded that the LEDs produced lower polymerization shrinkage in 10s and 60s compared with QTH unit. In addition, the microhardness of samples which had been cured with LEDs was lower on the lower surfaces than the upper surfaces whereas there was no difference in QTH cured samples.

The purpose of present study was to evaluate the polymerization shrinkage stress and amount of linear shrinkage of composites and compomers for posterior restoration.

For this purpose, linear polymerization shrinkage and polymerization stress were measured.

For linear polymerization shrinklage and polymerization stress measurement, custom made Linometer (R&B, Daejon, Korea) and Stress measuring machine was used (R&B, Daejon, Korea). Compositers and compomers were evaluated; Dyract AP (Dentsply Detrey, Gumbh. German) Z100 (3M Dental Products, St. Paul, USA) Surefil (Dentsply Caulk, Milford, USA) Pyramid(Bisco, Schaumburg, USA) Synergy Compact (Coltene, Altstatten, Switzerland), Heliomolar (Vivadent/Ivoclar, Liechtenstein), and Compoglass (Vivadent Ivoclar/Liechtenstein) were used. 15 measurements were made for each material. Linear polymerization shrinkage or polymerization stress for each material was compared with one way ANOVA with Tukey at 95% levels of confidence.

For linear shrinkage; Heliomolar, Surefil<Synergy Compact, Z100<Dyract AP<Pyramid, Compoglass F (p<0.05)

For Shrinkage stress; Heliomolar<Z100, Pyramid<Synergy Compact, Compoglass F<Dyract AP<Heliomolar HB, Surefil (p<0.05)

Chewing simulator, which can partly mimic the motion of chewing motion of human, has been successfully developed. The purpose of its development was to make a new machine which can anticipate the clinical results of restoration in the human teeth more accurately in vitro condition It is composed of 4 major parts; chewing part, motor part, water bath, controlling part. The controlling part control the chewing force, frequency, the temperature and running time of water. Additionally, the actual chewing force and remaining time is shown in the monitor of controlling part. At present, the chewing cycle is composed depending on the pre-published data of foreign people. Long term clinical data should be additionally collected for the simulator to mimic the clinical results more accurately.

The purpose of this study was to evaluate the effectiveness of plasma arc curing (PAC) unit for composite and compomer curing. To compare its effectiveness with conventional quartz tungsten halogen (QTH) light curing unit, the polymerization shrinkage rates and amounts of three composites (Z100, Z250, Synergy Duo Shade) and one compomer, that had been light cured by PAC unit or QTH unit, was compared using a custome made linometer. The measurement of polymerization shrinkage was performed after polymerization with either QTH unit or PAC unit. In case of curing with the PAC unit, the composite was light cured with Apollo 95E for 6s, the power density of which was recorded as 1350 mW/cm² by Coltolux Light Meter. For light curing with QTH unit, the composite was light cured for 30s with the XL2500, the power density of which was recorded as 800 mW/cm² by Coltolux Light Meter. The amount of linear polymerization shrinkage was recorded in the computer every 0.5s for 60s. Ten measurements were made for each material. The amount of linear polymerization shrinkage for each material in 10s and 60s which were cured with PAC or QTH unit were compared with t test. The amount of polymerization shrinkage in the tested materials were compared with 1way ANOVA with Duncan's multiple range test.

As for the amounts of polymerization shrinkage in 60s, there was no difference between PAC unit and QTH unit in Z250 and Synergy Duo Shade. In Z100 and Dyract AP, it was lower when it was cured with PAC unit than when it was cured with QTH unit (p<0.05).

As for the amounts of polymerization shrinkage in 10s, there was no difference between PAC unit and QTH unit in Z100 and Dyract AP. The amounts of polymerization shrinkage was significantly higher when it was cured with PAC unit in Z250 and Synergy Duo Shade (p<0.05). The amounts of polymerization shrinkage in the tested materials when they were cured with QTH unit were Z250 (6.6um) < Z100 (9.3um), Dyract AP (9.7um) < Synergy Duo Shade (11.2um) (p<0.05). The amount of polymerization shrinkage when the materials were cured with PAC unit were Dyract AP (5.6um) < Z100 (8.1um), Z250(7.0um) < Synergy Duo Shade (11.2um) (p<0.05).

The aim of this study was to investigate the effect of light irradiation modes on polymerization shrinkage, degree of cure and microleakage of a composite resin.

VIP™ (Bisco Dental Products, Schaumburg, IL, USA) and Optilux 501™ (Demetron/Kerr, Danbury, CT, USA) were used for curing Filtek™ Z-250 (3M Dental Products, St. Paul., MN, USA) composite resin using following irradiation modes: VIP™ (Bisco) 200mW/cm² (V2), 400mW/cm² (V4), 600mW/cm² (V6), Pulse-delay (200 mW/cm² 3 seconds, 5 minutes wait, 600mW/cm² 30seconds, VPD) and Optilux 501™ (Demetron/Kerr) C-mode (OC), R-mode (OR).

Linear polymerization shrinkage of the composite specimens were measured using Linometer (R&B, Daejeon, Korea) for 90 seconds for V2, V4, V6, OC, OR groups and for up to 363 seconds for VPD group (n=10, each).

Degree of conversion was measured using FTIR spectrometer (IFS 120 HR, Bruker Karlsruhe, Germany) at the bottom surface of 2 mm thick composite specimens. V2, V4, V6, OC groups were measured separately at five irradiation times (5, 10, 20, 40, 60 seconds) and OR, VPD groups were measured in the above mentioned irradiation modes (n=5, each).

Microhardness was measured using Digital microhardness tester (FM7, Future-Tech Co., Tokyo, Japan) at the top and bottom surfaces of 2mm thick composite specimens after exposure to the same irradiation modes as the test of degree of conversion(n=3, each).

For the microleakage test, class V cavities were prepared on the distal surface of the ninety extracted human third molars. The cavities were restored with one of the following irradiation modes: V2/60 seconds, V4/40 seconds, V6/30 seconds, VPD, OC and OR. Microleakage was assessed by dye penetration along enamel and dentin margins of cavities.

Mean polymerization shrinkage, mean degree of conversion and mean microhardness values for all groups at each time were analyzed using one-way ANOVA and Duncan's multiple range test, and using chi-square test for microleakage values.

The results were as follows:

·Polymerization shrinkage was increased with higher light intensity in groups using VIP™ (Bisco): the highest with 600mW/cm², followed by Pulse-delay, 400mW/cm² and 200mW/cm² groups. The degree of polymerization shrinkage was higher with Continuous mode than with Ramp mode in groups using Optilux 501™ (Demetron/Kerr).

·Degree of conversion and microhardness values were higher with higher light intensity. The final degree of conversion was in the range of 44.7 to 54.98% and the final microhardness value in the range of 34.10 to 56.30.

·Microleakage was greater in dentin margin than in enamel margin. Higher light intensity showed more microleakage in dentin margin in groups using VIP™ (Bisco). The micoleakage was the lowest with Continuous mode in enamel margin and with Ramp mode in dentin margin when Optilux 501™(Demetron/Kerr) was used.

The first purpose of present study was to compare the anticariogenic effect of compomer, resin modified glass ionomer cement and composite (RMGIC).

The second purpose was to evaluate the recently introduced methods, which use confocal scanning microscope, in detecting initial caries around restoration.

2×4×1.5mm cavities were prepared from the recently extracted 50 human teeth on the buccal or lingual surface. The prepared teeth were randomly devided into 5 groups and restored with each filling material. Group 1: Dyract AP, Group 2: compoglass F, Group 3: F2000, Group 4: Z100, Group 5:Fuji Ⅱ LC. The teeth were stored for 30 days in the distilled water, then stored in the buffer solution for artificial caries development; pH 4.3, lactic acid 100 mM, calcium 16 mM, phosphate 8mM, sodium azide 3mM. Then, the samples were sectioned longitudinally and examined with confical scanning microscope. The results showed that the use of compomer and resin modified glass ionomer cement showed caries inhibition zone whereas the composite did not. There was no difference in the width of caries inhibition zone between compomers and RMGIC. The confocal scanning microscope was useful in detecting initial caries around restoration.