Mucopolysaccharidosis (MPS) is an inherited metabolic disorder caused by a deficiency in enzymes that participate in the degradation of glycosaminoglycans (GAGs) such as heparin sulfate and dermatan sulfate. Left untreated, patients show progressive mental and physical deterioration due to deposition of GAGs in organs. Death often occurs due to cardiac or respiratory failure before patients reach their early twenties. MPS has several oral and dental manifestations. An enlarged head, short neck, and open mouth associated with a large tongue are major characteristics of MPS patients. Dental complications can be severe, including unerupted dentition, dentigerous cyst-like follicles, malocclusions, condylar defects, and gingival hyperplasia. A 21-year-old female patient with MPS was described in this article, with special emphasis on oral manifestations and dental treatment.

X-linked hypophosphatemia (XLH) is a hereditary metabolic disease caused by the loss of phosphate through the renal tubules into the urine, and an associated decrease in serum calcium and potassium phosphate. Its dental features include spontaneous dental abscesses that occur in the absence of trauma or dental caries. The aim of this case report was to describe the dental problems of XLH patients and to evaluate limitations in their treatment. A 14 year old male and a 38 year old female with XLH were referred to the Department of Conservative Dentistry for endodontic treatment. The dental findings were periapical abscesses without obvious trauma or caries. Conservative endodontic treatment was performed in teeth with pulp necrosis and abscess. In case 1, the treated teeth showed improvements in bone healing, without clinical symptoms. However, in case 2, the implants and the treated tooth showed hypermobility, and the final restoration was therefore postponed. Early diagnosis, periodic examinations, and communication with the patient's pediatrician are important in the dental management of patients with XLH.

A recent treatment option for non-vital immature teeth in young patients is revascularization with triple antibiotic paste (TAP). However, tooth discoloration was reported with the use of conventional minocycline-containing TAP. In this case report, amoxicillin-containing TAP was used for revascularization of non-vital immature teeth to prevent tooth discoloration. At the 1 yr follow up, the teeth were asymptomatic on clinical examination and showed slight discoloration of the crown due to mineral trioxide aggregate (MTA) filling rather than amoxicillin-containing TAP. Radiographic examination revealed complete resolution of the periapical radiolucency, and closed apex with obvious periodontal ligament space. However, the root growth was limited, and the treatment outcome was more like apexification rather than revascularization. These results may be due to unstable blood clot formation which could not resist the condensation force of MTA filling, whether or not a collagen matrix was in place. These cases showed that although revascularization was not successful, apexification could be expected, resulting in the resolution of the periapical radiolucency and the closure of the apex. Therefore, it is worthwhile attempting revascularization of non-vital immature teeth in young patients.

Traditionally, apexification has been used to treat immature permanent teeth that have lost pulp vitality. This technique promotes the formation of an apical barrier to close the open apex so that the filling materials can be confined to the root canal. Because tissue regeneration cannot be achieved with apexification, a new technique called regenerative endodontic treatment was presented recently to treat immature permanent teeth. Regenerative endodontic treatment is a treatment procedure designed to replace damaged pulp tissue with viable tissue which restores the normal function of the pulp-dentin structure. After regenerative endodontic treatment, continued root development and hard tissue deposition on the dentinal wall can occur under ideal circumstances. However, it is difficult to predict the result of regenerative endodontic treatment. Therefore, the purpose of this study was to summarize multiple factors effects on the result of regenerative endodontic treatment in order to achieve more predictable results. In this study, we investigated the features of regenerative endodontic treatment in comparison with those of other pulp treatment procedures and analyzed the factors that have an effect on regenerative endodontic treatment.

The autogenous tooth transplantation is an alternative treatment replacing a missing tooth when a suitable donor tooth is available. It is also a successful treatment option to save significant amount of time and cost comparing implants or conventional prosthetics. These cases, which required single tooth extraction due to deep caries and severe periodontal disease, could have good results by transplanting non-functional but sound donor tooth to the extraction site.

The purpose of this study is to compare the antibacterial effect of Listerine® on two microorganisms (P. gingivalis and E. faecalis) with various root canal irrigants (NaOCl, CHX, EDTA) and to identify possibility of using Listerine® as a root canal irrigant. Porphyromonas gingivalis ATCC 3327 and Enterococcus faecalis ATCC 29212 were used in this experiment. For the test irrigants, 0.5%, 1%, 2.5%, 5.25% NaOCl, 0.1%, 0.2%, 1%, 2% CHX, 0.5M EDTA (18.6% EDTA) and Listerine® were prepared. Distiled water was used as control. Two methods-1) Comparison of turbidity in broth and 2) Agar diffusion test-were used to determine the extent of antibacterial effect of Listerine® and to compare it with that of NaOCl, CHX, and EDTA. All solutions tested were effective against two bacterial strains compared with control (p<0.001). Any concentration of NaOCl, CHX, and EDTA showed similarly high effectiveness against all bacterial strains. In all experiment, Listerine® showed significantly low antibacterial effect compared with the other root canal irrigants (p<0.05).

In conclusion, the results reflect remarkably low antibacterial effect of Listerine® as compared with root canal irrigants in general so it is not suitable for the root canal irrigant.

In this study we evaluated the influence of both the thickness of residual enamel and the color of the composite resins applied to lingual surface on the labial surface color.

Background plates were made by randomly (A1, A2, A6D, B1, B2, B3, C1, C2, C6D) selected colors of Filtek Supreme (3M ESPE, St. Paul, U.S.A.) composite resin.

Crown portion of 9 maxillary central incisors were cut off and embedded with acrylic resin except labial surface. Samples of average thickness of 2.2 mm were obtained after cutting it in a thickness of 2.5 mm from the labial surface and sandpaper polish.

The shade of composite resin background was measured using Spectrophotometer (Spectrolino® GretagMacbeth, Regensdorf, Switzerland). And CIE L^*a^*b^* value of 2.2 mm thickness tooth samples were measured on the 9 composite resin backgrounds. And then, the cutting side of tooth samples was ground to the extent of 1.9 mm, 1.6 mm, 1.3 mm, 1.0 mm and placed on composite resin backgrounds and measured L^*a^*b^* values with the same method.

In all samples, L^* value and b^* value seemed to have a tendency of decreasing as thickness of tooth sample becomes thinner regardless of background colors (p < 0.05). But, a^* value didn't show the significant differences depending on the thickness.

The objective of this study was to evaluate the effect of color measuring instrument by measuring the color of dental composite resins.

Nine shade light cured composite resin disks were prepared (diameter : 15 mm, thickness : 4 mm). CIE L^*a^*b^* color scale of each disk was measured with 3 different types of spectrophotometer [MiniScan XE plus (Model 4000S, Hunter Lab, USA), CM-3500d (Minolta, Japan) and Specbos 2100 Miniature VIS Reflection spectrometer (Serial No: 319416, JETI Technishe VIS Instrumentic GmbH, Germany)]. Miniscan XE Plus and CM-3500d using identical measuring geometry with different size of viewing aperture. But Specbos 2100 using different measuring geometry.

Within the limitation of this study, there were color difference (ΔE^*) from 2.4 to 7.8 between Miniscan XE Plus and CM-3500d, but L^*, a^*, b^* values showed the high correlation. However, there were great color difference (ΔE^*) in the extent of about 20 between instruments with the different measuring geometry.

Therefore, color scale measured by color measuring instrument should be used as a relative value rather than an absolute value in the field of dentistry.

This study was carried out in order to determine in vitro biocompatibility of white mineral trioxide aggregate (MTA), and to compare it with that of the commonly used materials, i. e. calcium hydroxide liner (Dycal), glass ionomer cement (GIC), and Portland cement which has a similar composition of MTA. To assess the biocompatibility of each material, cytotoxicity was examined using MG-63 cells. The degree of cytotoxicity was evaluated by scanning electron microscopy (SEM) and a colorimetric method, based on reduction of the tetrazolium salt 2,3 bis {2methoxy 4nitro 5[(sulfenylamino) carbonyl] 2H tetrazolium hydroxide} (XTT) assay.

The results of SEM revealed the cells in contact with GIC, MTA, and Portland cement at 1 and 3 days were apparently healthy. In contrast, cells in the presence of Dycal appeared rounded and detached. In XTT assay, the cellular activities of the cells incubated with all the test materials except Dycal were similar, which corresponded with the SEM observation. The present study supports the view that MTA is a very biocompatible root perforation repair material. It also suggests that cellular response of Portland cement and GIC are very similar to that of MTA.

This study was performed to assess the radiopacity of a variety of root canal sealers according to the specification concerning root canal sealers.

Ten materials including Tubli-Seal™, Kerr Pulp Canal Sealer™, AH 26®, AH plus®, AH plus jet™, Ad sea l™, Sealapex™, NOGENOL™, ZOB seal™, Epiphany™ and dentin were evaluated in this study. In the first part, densitometric reading of an each step of aluminum step wedge on occlusal film was performed at different voltage and exposure time. In the second part, ten specimens were radiographed simultaneously with an aluminum step wedges on the occlusal films under decided condition. The mean radiographic den sity values of the materials were transformed into radiopacity expressed equivalent thickness of aluminum (mm Al).

The following results were obtained.

1. Among the various conditions, the appropriate voltage and exposure time that meet the requirement density was 60 kVp at 0.2 s

2. All of the materials had greater radiopacity than 3 mm Al requirement of ANSI/ADA specification No. 57 (2000) and ISO No. 6876 (2001) standards.

3. The radiopacity of materials increased as thickness of materials increased.

4. The mm Al value of each specimen at 1mm in thickness has a significant difference in the statistics.

It suggests that root canal sealers have a sufficient radiopacity that meet the requirement.

This study analyzed the influence of dental adhesive/primer on the bond strength between indirect resin composite and the resin cement.

Seventy disc specimens of indirect resin composite (Tescera Dentin, Bisco) were fabricated. And bonding area of all specimens were sandblasted and silane treated for one minute. The resin cements were used with or without application of adhesive/primer to bonding area of indirect resin restoration: Variolink-II (Ivoclar-Vivadent): Exite DSC, Panavia-F (Kuraray): ED-Primer, RelyX Unicem (3M ESPE): Single-Bond, Duolink (Bisco): One-step, Mulitlink (Ivoclar-Vivadent): Multilinh Primer.

Shear bond strength was measured by Instron universal testing machine.

Adhesive application improved shear bond strength (p < 0.05). But Variolink II and Panavia-F showed no statistically significant difference according to the adhesive application.

With the above results, when resin inlay is luted by resin cement it seems that application of dental adhesive/primer is necessary in order to improve the bond strength.

This study was done to evaluate the reliability of the digital color analysis system (ShadeScan, CYNOVAD, Montreal, Canada) for dentistry.

Sixteen tooth models were made by injecting the A2 shade chemical cured resin for temporary crown into the impression acquired from 16 adults. Surfaces of the model teeth were polished with resin polishing cloth. The window of the ShadeScan handpiece was placed on the labial surface of tooth and tooth images were captured, and each tooth shade was analyzed with the ShadeScan software. Captured images were selected in groups, and compared one another.

Two models were selected to evaluate repeatability of ShadeScan, and shade analysis was performed 10 times for each tooth.

And, to ascertain the color difference of same shade code analyzed by ShadeScan, CIE L^*a^*b^*values of shade guide of Gradia Direct (GC, Tokyo, Japan) were measured on the white and black background using the Spectrolino (GretagMacbeth, USA), and Shade map of each shade guide was captured using the ShadeScan.

There were no teeth that were analyzed as A2 shade and unique shade. And shade mapping analyses of the same tooth revealed similar shade and distribution except incisal third.

Color difference (ΔE^*) among the Shade map which analyzed as same shade by ShadeScan were above 3.

Within the limits of this study, digital color analysis instrument for dentistry has relatively high repeatability, but has controversial in accuracy.

The purpose of this study was to evaluate the color stability of resin cements with accelerated test. Four dual curing resin cements: Panavia-F (KURARAY), Duolink (BISCO), Variolink-II (Ivoclar Vivadent), and RelyX Unicem (3M ESPE) and 1 self curing resin cement: Resiment CE (j. l. Blosser) were used in this study. In control group, Gradia Anterior (GC) composite resin and Tescera Dentin (Bisco) indirect composite were used. Ten disk shape specimens were made from each resin cement. The specimens were subjected to an accelerated aging process in a refrigerated bath circulator at 60℃ for 15 and 30 days. Spectrophotometric analyses were made before and after 15 days and 30 days of accelerated aging time.

The color characteristics (L^*, a^*, b^*) and the color difference (ΔE^*) of the specimens before and after immersion were measured and computed.

Regardless of type of the resin cements, L^* value was decreased and a^* value was increased, but there were no significant difference. But b^* value was increased significantly (p < 0.05). Tescera inlay showed least color change (p < 0.05), but Gradia showed notable color change after 15 days.

After 30 days on accelerated aging, ΔE^* value was increased (Panavia-F < Variolink-II < Resiment CE < Duolink < Unicem) (p < 0.05), but there were no significant difference among Panavia-F, Variolink-II, and Resiment CE groups. After 30 days of accelerated aging, ΔE^* value of all resin cements were greater than 3.0 and could be perceived by the human eye.

This study was performed to assess the radiopacity of a variety of canal filling and retrograde root-end filling materials according to the specification concerning root canal obturation materials.

Ten materials including Gutta-percha pellets, amalgam, Fuji II LC, Dyract® AP, Super EBA®, IRM®, AH 26®, Sealapex™, Tubli-Seal™ and dentin were evaluated in this study. In the first part, densitometric reading of an each step of aluminum step wedge on occlusal film were performed at 60 kVp (0.2, 0.3, 0.4 s), 70 kVp (0.2, 0.3, 0.33 s) to decide appropriate voltage and exposure time. In the second part, ten specimens which are 5 mm in diameter and 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 mm in thickness, were fabricated from each material studied. The specimens were radiographed simultaneously with an aluminum step wedge under decided condition (60 kVp, 0.2 s). The mean radiographic density values of the materials were transformed into radiopacity expressed equivalent thickness of aluminum (mm Al).

The following results were obtained.

Among the various conditions including 0.2 s, 0.3 s, 0.4 s at 60 kVp and 0.2 s, 0.3 s, 0.33 s at 70 kVp, the appropriate voltage and exposure time that meet the requirement of density from 0.5 to 2.0 was 0.2 s at 60 kVp.

It suggests that all experimental canal filling and retrograde root-end filling materials have a sufficient radiopacity that meet the requirement concerning root canal obturation materials except for Fuji II LC and Dyract.

The purpose of this study was to evaluate whether intracanal irrigation method could affect the adhesion between intracanal dentin and root canal filling materials (Gutta-percha/AH 26 sealer and Resilon/Epiphany sealer).

Thirty extracted human incisor teeth were prepared. Canals were irrigated with three different irrigation methods as a final rinse and obturated with two different canal filling materials (G groups : Gutta-percha/AH 26 sealer, R groups : Resilon/Epiphany sealer) respectively.

Group G1, R1 - irrigated with 5.25% NaOCl

Thirty obturated roots were horizontally sliced and push-out bond strength test was performed in the universal testing machine. After test, the failure patterns of the specimens were observed using Image-analyzing microscope.

The results were as follows.

Gutta-percha/AH 26 sealer groups had significantly higher push-out bond strength compared with the Resilon/Epiphany sealer groups (p < 0.05).

The purpose of this study was to evaluate the insertion depth of several brands of master gutta percha cones after shaping by various Ni-Ti rotary files in simulated canals.

Fifty resin simulated J-shape canals were instrumented with ProFile, ProTaper and HEROShaper. Simulated canals were prepared with ProFile .04 taper #25 (n = 10), .06 taper #25 (n = 10), ProTaper F2 (n = 10), HEROShaper .04 taper #25 (n = 10) and .06 taper #25 (n = 10). Size #25 gutta percha cones with a .04 & .06 taper from three different brands were used: DiaDent; META; Sure-endo. The gutta percha cones were selected and inserted into the prepared simulated canals. The distance from the apex of the prepared canal to the gutta percha cone tip was measured by image analysis program.

Within limited data of this study, the results were as follows

1. When the simulated root canals were prepared with HEROShaper, gutta-percha cones were closely adapted to the root canal.

2. All brands of gutta percha cones fail to go to the prepared length in canal which was instrumented with ProFile, the cones extend beyond the prepared length in canal which was prepared with ProTaper.

3. In canal which was instrumented with HEROShaper .04 taper #25, Sure-endo .04 taper master gutta percha cone was well fitted (p < 0.05).

4. In canal which was instrumented with HEROShaper .06 taper #25, META .06 taper master gutta percha cone was well fitted (p < 0.05).

As a result, we concluded that the insertion depth of all brands of master gutta percha cone do not match the rotary instrument, even though it was prepared by crown-down technique, as recommended by the manufacturer. Therefore, the master cone should be carefully selected to match the depth of the prepared canal for adequate obturation.

The most scientific and reliable method for deciding the tooth color is the instrumental measurement. However, such color measuring instrument shows the difference of the measuring value according to the diversified measuring condition.

This study was conducted to evaluate what effect of the labial surface irregularity of the tooth to the result of the color measured by spectrometer.

11 models of the teeth were made by injecting the A2 shade Luxatemp Automix Plus (DMG, Germany) into the impression acquired from 11 adults. Standard disk samples (15 mm diameter, 7 mm thickness) were made with same material. CIE L^*a^*b^* value was measured at the incisal, central, and gingival area of the central incisor, lateral incisor, canine and first premolar using Specbos 2100 (JETI, Germany) spectrometer. Color difference was calculated between labial surface and standard samples.

Among all models of the teeth, L^* and b^* value showed the reducing tendency as they go toward the gingival area, but a^* value showed the increasing tendency.

Color difference between model teeth and standard samples showed the most difference at the incisal area, but the gingival area showed the least difference. And the canine showed the least color difference from the comparison of standard sample, and the central incisor showed the highest difference (p < 0.01).

Although the visually detectable difference of the measuring value showed notably depending on the type and measured area (p < 0.05), L^* and a^* value showed notable differences depending more on the measured areas than on the type of the teeth.

The purpose of this study was to assess the background color-interceptive ability and opacity of opaque shade composites (Universal composite, Filtek Z350, Charisma, Clearfil ST, Palpaque Estelite, Esthet-X, and Metafil Flo).

Twenty four background specimens (diameter 5.5 mm, thickness 3.0 mm) with Root dentin Mustard (Bisco, Schaumburg, IL, USA) were made. The CIE L^*a^*b^* value of background specimens was measured by a spectrophotometer (Spectrolino, GretagMacbeth, Regensdorf, Switzerland). Three specimens in every group were filled on the background specimens. The surface color of samples was measured by a spectrophotometer in 3.0 mm and every thickness to 0.5 mm while grinding. The color difference in the background color along with 3.0 mm specimen gauged the masking effect in each thickness while grinding and polishing. The opacity was calculated in 1 mm thick specimens.

The opacity was in the decreasing order of Clearfil ST, Metafil Flo, Filtek Z350, Palpaque Estelite, Universal composite, Charisma, and Esthet-X (p < 0.05). As the thickness get reduced, L^* value showed decreasing, a^* increasing tendency. The surface color difference between pair of the 3.0 mm thick specimen and after grinding in same opaque resin was above 3.3 except Clearfil ST and Metafil Flo. The color difference (ΔE^*) between pair of background specimen and opaque resin builtup specimen showed more than 10.0 regardless kinds and thickness.

The variance in opacity characteristics and color of the opaque composites is dependent upon manufacturer. When using the opaque resin, the optical properties of each material must be considered as well as cavity.

This study was performed to verify the possibility of MTA and calcium sulfate as a pulp capping agent through comparing the dental pulp response in dogs after capping with MTA, calcium sulfate, and calcium hydroxide.

24 teeth of 2 dogs, 8 month old, were used in this study.

Under general anesthesia, cervical cavities were prepared and pulp was exposed with sterilized #2 round bur in a high speed handpiece.

MTA, calcium hydroxide, and calcium sulfate were applied on the exposed pulp. Then the coronal openings were sealed with IRM and light-cured composite.

Two months after treatment, the animals were sacrificed. The extracted teeth were fixed in 10% neutral-buffered formalin solution and were decalcified in formic acid-sodium citrate. They were prepared for histological examination in the usual manner. The sections were stained with haematoxylin and eosin.

In MTA group, a hard tissue bridges formation and newly formed odontoblasts layer was observed. There was no sign of pulp inflammatory reaction in pulp tissue.

In calcium hydroxide group, there was no odontoblast layer below the dentin bridge. In pulpal tissue, chronic inflammatory reaction with variable intensity and extension occurred in all samples.

In calcium sulfate group, newly formed odontoblast layer was observed below the bridge. Mild chronic inflammation with a few neutrophil infiltrations was observed on pulp tissue.

These results suggest that MTA is more biocompatible on pulp tissue than calcium hydroxide or calcium sulfate.

The purpose of this study is to develope new dental color-space system. Twelve kinds of dental composites and one kind of dental porcelain were used in this study. Disk samples (15 mm in diameter, 4 mm in thickness) of used materials were made and sample's CIE L^*a^*b^* value was measured by Spectrocolorimeter (MiniScan XE plus, Model 4000S, diffuse/8° viewing mode, 14.3 mm Port diameters, Hunter Lab. USA). The range of measured color distribution was analyzed. All the data were applied in the form of T### which is expression unit in CNU Cons Dental Color Chart.

The value of L^* lies between 80.40 and 52.70. The value of a^* are between 10.60 and 3.60 and b^* are between 28.40 and 2.21. The average value of L^* is 67.40, and median value is 67.30. The value of a^* are 2.89 and 2.91 respectively. And for the b^*, 14.30 and 13.90 were obtained. The data were converted to T### that is the unit count system in CNU-Cons Dental Color Chart. The value of L^* is converted in the first digit of the numbering system. Each unit is 2.0 measured values. The second digit is the value of a^* and is converted new number by 1.0 measured value. For the third digit b^* is replaced and it is 2.0 measured unit apart. T555 was set to the value of L^* ranging from 66.0 to 68.0, value of a^* ranging from 3 to 4 and b^* value ranging from 14 to 16.

The objectives of this study were to evaluate the effect of surface roughness on the surface color and translucency of the composite resins.

Two composite resins (Esthet-X, Dentsply, Milford, USA and Charisma, Kulzer, Domagen, Germany) were used to investigate the surface color. Charisma was used to investigate the translucency. 40 disc samples (diameter: 8 mm, thickness: 5 mm) were made by each product to measure the surface color. Polymerized each sample's one side was treated by Sof-Lex finishing and polishing system (Group C, M, F, SF). 40 disc samples (diameter: 6 mm, thickness: 1 mm) were prepared to measure the opacity. 1 mm samples were ground one side with #600, #1000, #1500 and #2000 sandpapers. CIE L*a*b* values of each 5 mm thickness samples, and XYZ values of 1 mm thickness samples on the white and black background were measured with spectrophotometer (Spectrolino, GretagMacbeth, Regensdorf, Switzerland).

Mean surface roughness (Ra) of all samples before and after surface treatment was measured using the Surface Roughness Tester SJ-301 (Mytutoyo, Tokyo, Japan).

Regardless of type and shade of the composite resin, L* values measured in group C were higher than others (p < 0.05), and L* value decreased as the Ra value decreased except B3 shade of Esthet-X. But there were no significant difference in a* values among groups. In control group and SF, highest b* values were measured (p < 0.05), except B1 shade of Esthet-X.

Contrast ratio decreased as the Ra value decreased (p < 0.05).

With the above results, difference of surface roughness has influence on surface color and translucency of dental composite resins.

This study was conducted to evaluate canal configuration after shaping by ProTaper™ with various rotational speed in J-shaped simulated resin canals.

Forty simulated root canals were divided into 4 groups, and instrumented using by ProTaper™ at the rotational speed of 250, 300, 350 and 400 rpm. Pre-instrumented and post-instrumented images were taken by a scanner and those were superimposed. Outer canal width, inner canal width, total canal width, and amount of transportation from original axis were measured at 1, 2, 3, 4, 5, 6, 7 and 8 mm from apex. Instrumentation time, instrument deformation and fracture were recorded. Data were analyzed by means of one-way ANOVA followed by Scheffe's test.

The results were as follows

Regardless of rotational speed, at the 1~2 mm from the apex, axis of canal was transported to outer side of a curvature, and at 3~6 mm from the apex, to inner side of a curvature. Amounts of transportation from original axis were not significantly different among experimental groups except at 5 and 6 mm from the apex.

In conclusion, the rotational speed of ProTaper™ files in the range of 250~400 rpm does not affect the change of canal configuration, and high rotational speed reduces the instrumentation time. However, appearance of separation and distortion of Ni-Ti rotary files can occur in high rotational speed.

This study was conducted to evaluate the insertion depth of Buchanan plugger after shaping by various Ni-Ti rotary files. It was conducted to determine which size of plugger are appropriate, when root canals are shaped with Ni-Ti rotary files and obturated by Continuous wave of condensation technique.

Two type of eighty simulated resin blocks were used : J-shaped and straight shaped canal. The simulated canals were instrumented by ProTaper and ProFile. Buchanan pluggers were inserted into the canal, and then the image was recorded to scanner. The distance from the apex of the canal to the plugger tip was measured by image analysis program. Data were analyzed by one-way ANOVA followed by Scheffe's test.

The results were as follows

1. In straight canal finished up to ProTaper F2 and F3 file, F and FM pluggers were inserted more than 5 mm short of working length.

2. In J-shaped canal finished up to ProTaper F2 file, F pluggers were inserted more than 5 mm short of working length. Finished up to ProTaper F3 file, F and FM pluggers were inserted more than 5 mm short of working length.

3. In straight and J-shaped canal finished up to ProFile .06/#20 and .06/#25, any of Buchanan plugger could not be inserted more than 5 mm short of working length.

These results suggest that canals shaped by ProTaper could be obturated by Continuous wave of condensation technique with F and FM size Buchanan plugger.

The purpose of this study was to evaluate the effect of increasing application time of single bottle adhesives (SBA) to microtensile bond strength (MTBS) of dried dentin. To expose the superficial dentin surfaces, human molars were sectioned perpendicular to the long axis of tooth. 32% phosphoric acid gels were applied for 15s and rinsed. The teeth were randomly assigned to 3 groups ; S group (Single Bond), O group (One-Step), P group (Prime & Bond NT). Each group was divided to 3 subgroups (W: dentin wipe with wet gauge and light cured immediately, D: dentin dried for 30s and light cured immediately, 30: dentin dried for 30s and light cured after applying SBA for 30s). Composite resin was built up on the dentin surface and sectioned to obtain 20 specimens with 1 mm² cross sectional area and the MTBS was measured.

For Single Bond, the mean MTBS of S-W and S-30 group were higher than that of S-D group statistically (P < 0.05). For One-Step, the mean MTBS of O-D group was statistically lower than that of O-W group (P < 0.05). For Prime & Bond NT, the mean MTBS of P-30 group was statistically lower than that of P-D group (P < 0.05).

The purpose of this study was to compare the canal configuration after shaping by ProTaper rotary files and ProTaper hand files in resin simulated canals.

Forty resin simulated canals with a curvature of J-shape and S-shape were divided into four groups by 10 blocks each. Simulated root canals in resin block were prepared by ProTaper rotary files and ProTaper hand files using a crown-down pressureless technique. All simulated canals were prepared up to size #25 file at end-point of preparation. Pre- and post-instrumentation images were recorded with color scanner. Assessment of canal shape was completed with an image analysis program. Measurements were made at 0, 1, 2, 3, 4, 5, 6 and 7 mm from the apex. At each level, outer canal width, inner canal width, total canal width, and amount of transportation from original axis were recorded. Instrumentation time was recorded. The data were analyzed statistically using independent t-test.

The result was that ProTaper hand files cause significantly less canal transportation from original axis of canal body and maintain original canal configuration better than ProTaper rotary files, however ProTaper hand files take more shaping time.

The purpose of this study was to evaluate the canal configuration after shaping by ProFile, ProTaper and K-Flexofile in simulated resin canals with different angles of curvature.

Three types of instruments were used : ProFile, ProTaper, K-Flexofile. Simulated root canals, which were made of epoxy resin, were prepared by ProFile, ProTaper with rotary instrument using a crown-down pressureless technique, and hand instrumentation was performed by K-Flexofile using a step-back technique. All simulated canals were prepared up to size 25 file at end-point of preparation. Pre and post instrumentation images were recorded with Scanner. Assessment of canal shape was completed with Image Analysis program. Measurements were made at 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 mm from the apex. At each level, outer canal width, inner canal width, total canal width, and amount of transportation from original axis were recorded. Instrument deformation and fracture were recorded. Data were analyzed by means of one-way ANOVA analysis of variance and the Sheffe's test.

The result was that ProFile and ProTaper maintain original canal shape regardless of the increase of angle of curvature than K-Flexofile. ProFile show significantly less canal transportation and maintained original canal shape better than ProTaper.

The purpose of this study was to evaluate which type of Ni-Ti files are able to maintain canal configuration better in the simulated canal with abrupt curvature near it's apex.

Ninety six simulated root canals were made in epoxy resin and #15 finger spreader was used as root canal templates. The simulated root canals were made with radius of curvature of 1.5 mm, 3.0 mm, 4.0 mm, 6.0 mm respectively and the angle of curvature of all simulated canals were adjusted to 90 degree. The simulated canals were instrumented by ProFile, ProTaper, Hero 642, and K³ at a 300 rpm using crown-down pressureless technique. Pre-instrumented and post-instrumented images were taken by digital camera and were superimposed with Adobe Photoshop 6.0 program. Images were compared by image analysis program.

The changes of canal width at the inner and outer side of the canal curvature, canal transportation were measured at 9 measuring point with 1 mm interval. Statistical analysis among the types of Ni-Ti files was performed using Kruskal-Wallis test and Mann-Whitney U-test.

The result was that ProFile maintain original canal configuration better than other engine driven Ni-Ti files in the canals above 3.0 mm radius of curvature, and in the 1.5 mm radius of curvature, most of Ni-Ti flies were deformed or separated during instrumentation.

This study was done to evaluate the shear bond strength between light-cured glass ionomer cement (GIC) base and resin cement for luting indirect resin inlay and to observe bonding aspects which is produced at the interface between them by SEM.

Two types of light cured GIC (Fuji II LC Improved, GC Co. Tokyo, Japan and Vitrebond™, 3M, Paul, Minnesota, U.S.A) were used in this study. For shear bond test, GIC specimens were made and immersed in 37℃ distilled water for 1 hour, 24 hours, 1 week and 2 weeks. Eighty resin inlays were prepared with Artglass® (Heraeus Kultzer, Germany) and luted with Variolink® II (Ivoclar Vivadent, Liechtenstein).

Shear bond strength of each specimen was measured and fractured surface were examined. Statistical analysis was done with one-way ANOVA.

Twenty four extracted human third molars were selected and Class II cavities were prepared and GIC based at axiopulpal lineangle. The specimens were immersed in 37℃ distilled water for 1 hour, 24 hours, 1 week and 2 weeks. And then the resin inlays were luted to prepared teeth. The specimens were sectioned vertically with low speed saw. The bonding aspect of the specimens were observed by SEM (JSM-5400®, Jeol, Tokyo, Japan). There was no significant difference between the shear bond strength according to storage periods of light cured GIC base. And cohesive failure was mostly appeared in GIC. On scanning electron micrograph, about 30 - 120 µm of the gaps were observed on the interface between GIC base and dentin. No gaps were observed on the interface between GIC and resin inlay.

This study was conducted in order to assess whether the form of the shade guide affects in deciding the color of the teeth using the shade guide.

Eight shade light cured composite resins (Esthet-X, Dentsply, Milford, USA) were used in this study. Shade guides including the model of maxillary central incisors, teeth-form shade guide, doughnut form shade guide, and shade guide with perforated gray shield were prepared with eight shade composite resins and provided the codes randomly.

After arranging the models of teeth, 19 dentists working at the clinic of the Dentistry of Chonnam University Hospital and 65 students of college of dentistry, Chonnnam University selected the shade guides corresponding to the color of each tooth on the gray board under the D65 standard illuminant.

B1 shade showed highest accuracy of about 95% among all shade guides of 3 forms applied to the test and regardless of observer, tooth form shade guide showed the highest accuracy (p < 0.05), and the doughnut form showed the lowest accuracy (p < 0.05).

At the time of deciding on the color of the teeth using the shade guides as a result of above, the forms of the shade guides can affect the accuracy, and it suggests that the development of the diversified forms of shade guides, which may obtain more accurate results, is required.

This study was done to evaluate whether vital bleaching agents could influence on the translucency of the bovine enamel. The anterior bovine teeth that were extracted one day before and without any gross discoloration were obtained and then were preserved in physiologic saline. 6 mm cylindrical tooth specimens were fabricated with diamond puncher perpendicularly on labial surface of bovine tooth. After embedded in transparent acrylic resin with labial surface being exposed, they were cut to a thickness of 1.2 mm with low speed diamond saw (Isomat, Buehler Co., Lake Bluff, IL, USA). They were smoothly ground to 1 mm thickness of enamel with sandpaper. 24 specimens were randomly divided into 3 groups and control group respectively. Opalescence (10% carbamide peroxide, Ultradent, South Jordan, USA), Rembrandt (10% carbamide peroxide, DenMat, USA) and Opalescence F (15% carbamide peroxide with fluoride, Ultradent, USA) were applied on labial sides of the bovine enamel for 7 days (bleaching agents were reapplied every 24 hours) and the opposite surface was contacted to cotton that soaked in distilled water. The control group was soaked in distilled water. Three stimulus value X, Y and Z were evaluated with colorimeter (Color & Color Differencemeter, Model TC-6FX, Tokyo Denshoku Co., Japan) on the labial surface of all specimen three times on white and black background plate before the bleaching agents were applied and on 3rd, 5th and 7th day after applied. The degree of translucency was normally assessed by measuring the inverse property, opacity (contrast ratio).

10% Opalescence, 15% Opalescence-F, and control group showed no significant variation in the translucency of bovine enamel, However Rembrandt decreased the translucency of it (p < 0.01).

In this study we measured the amount of light energy that was projected through the tooth material and analyzed the degree of polymerization by measuring the surface hardness of composites. For polymerization, Optilux 501 (Demetron, USA) with two types of light guide was used: a 12 mm diameter light guide with 840 mW/cm² light intensity and a 7 mm diameter turbo light guide with 1100 mW/cm².

Specimens were divided into three groups according to thickness of penetrating tooth (1 mm, 2 mm, 0 mm). Each group was further divided into four subgroups according to type of light guide and curing time (20 seconds, 40 seconds). Vickers'hardness was measured by using a microhardness tester. In 0 mm and 1 mm penetrating tooth group, which were polymerized by a turbo light guide for 40 seconds, showed the highest hardness values. The specimens from 2 mm penetrating tooth group, which were polymerized for 20 seconds, demonstrated the lowest hardness regardless of the types of light guides (p < 0.05).

The results of this study suggest that, when projecting tooth material over a specified thickness, the increase of polymerization will be limited even if light intensity or curing time is increased.

The purpose of this study was to evaluate the penetration pattern of dentin adhesives according to the orientation of dentinal tubules with confocal laser scanning microscopy. Specimens having perpendicular, parallel and oblique surface to dentinal tubules were fabricated. The primer of dentin adhesives (ALL BOND® 2, CLEARFIL™ SE BOND and PQ1) was mixed with fluorescent material, rhodamine B isothiocyanate (Aldrich Chem. CO., Milw., USA). It was applied to the specimens according to the instructions of manufactures. The specimens were covered with composite resin (Estelite, shade A2) and then cut to a thickness of 500 µm with low speed saw (Isomet™, Buehler, USA). The adhesive pattern of dentin adhesives were observed by fluorescence image using confocal laser scanning microscopy.

The results were as follows.

For the groups with tubules perpendicular to bonded surface, funnel shape of resin tag was observed in all specimen. However, resin tags were more prominent in phosphoric acid etching system (ALL BOND® 2 and PQ1) than self etching system (CLEARFIL™ SE BOND).

This study was done to present a criterion in selection of the most proper light sources and materials by measuring metamerism index(MI) of the light curing composite resins with spectrocolorimeter. Metamerism is defined when two objects appear to be the same color in one illuminant but different in another. This is due to the fact that they have different spectral curves that fail to match under the second illuminant.

In this study, A1 & A3 shade of five light curing composite resins (Esthet-X, Filteck Z250, Filteck A110, Charisma, Vitalescence) were chosen based on Vita shade. Five samples were made for shade of each product with Teflon mold (diameter: 15mm, thickness: 2mm).

Metamerism index of each samples on a Barium sulfate plate (L*=96.54, a*=0.19, b*=0.01) prepared for sample fixation were measured with spectrocolorimeter(Miniscan XE plus, Model 4000s, Hunter Lab, USA) by applying standard light source D₆₅, C, Fcw, TL84 and A. Standardization was done with reference standard (X=80.8, Y=85.7, Z=90.8) and light trap. The results were as follows.

Different resins with same Vita shade showed recognizable color difference(ΔE*>2).

This study was performed to evaluate the actual temperature rise on the surface of Buchanan plugger using thermocouple. The heat carrier system 'System B Heatsource' (Model 1005, Analytic Technologies, Redmond, WA, USA) and the Buchanan pluggers of F, FM, M and ML sizes are used for this study. The temperature was set to 200℃ on digital display and the power level on it was set to 10. Five thermocouples were placed in direct contact with the surface of each size of Buchanan's pluggers at 1 mm increments from the tip to the 4 mm length of shank. The heat control spring was touched for 5 seconds, and the temperature rise on the surface of the pluggers were measured at 1 sec intervals for more than 5 seconds with an accuracy of 0.01 using Data Logger. The data were statistically analyzed by one-way ANOVA.

The results were as follows.

The position at which the temperature peaked was approximately at 1~2 mm far from the tip of Buchanan plugger (p<0.01).

This results suggest that the actual temperature on the surface of the pluggers does not correlate well with the temperature set on digital display. Heat concentrates around the tip. The larger plugger reveals lower temperature rise relatively.

This study was conducted to evaluate the temperature rise on the root surface while the root canal is being obturated using continuous wave of condensation technique. Maxillary central incisor was prepared for repeated canal obturation. Ten thermocouples (Omega Engineering Inc., Stanford, USA) were placed at 1 mm increment from the anatomical root apex. The real temperature of Buchanan plugger was recorded before insertion into the root canal. The root canal was obturated with continuous wave of condensation technique as described by Buchanan and the root surface temperature was recorded during obturation at 150℃, 200℃, 250℃ and 300℃ temperature settings of System B HeatSource (Model 1005, Analytic technologies, Redmond, WA, USA). After completion of the temperature recording, the dentinal-cementum thickness at each sites was measured. The data were analyzed using one-way ANOVA followed by Scheffe' s test and linear regression test.

The results were as follows.

When the temperature was set at 150℃, 200℃, 250℃ and 300℃ on the digital display of System B HeatSource, the real temperature of the plugger at the 1mm point from the tip revealed 130.82±2.96℃, 158.00±5.26℃, 215.92±6.91℃ and 249.88±3.65℃ respectively.

These results suggest that it be relatively kind to the supporting tissues of the root that the root canal is obturated using continuous wave of condensation technique at 150℃, 200℃, 250℃ and 300℃ temperature settings on digital temperature display of System B HeatSource.

This study was performed to evaluate the interfacial shear bond strength of base (direct and indirect) and repair composites with aging and surface treatment methods.

Direct composite resin specimens (Charisma®, Heraeus Kulzer, Germany) were aged for 5 min, 1 hour, 24 hours, and 1 week in 37℃ distilled water before surface treatment, and then divided into five groups: Group 1, grinding; Group 2, grinding and application of bonding agent; Group 3, grinding, etching with 37% phosphoric acid for 30sec, and application of bonding agent; Group 4, grinding, etching with 37% phosphoric acid for 30sec, silane treatment, and application of bonding agent; Group 5, grinding, etching with 4% hydrofluoric acid for 30sec, silane treatment, and application of bonding agent.

Indirect composite resin specimens (Artglass®, Heraeus Kulzer, Germany) were aged for 1 week in 37℃ distilled water and divided into seven groups: Group 1 - Group 5, equal to Charisma specimens; Group 6, grinding, etching with 37% phosphoric acid for 60sec, silane treatment, and application of bonding agent; Group7, grinding, etching with 4% hydrofluoric acid for 60 sec, silane treatment, and application of bonding agent.

The repair material(Charisma®) was then added on the center of the surface (5 mm in diameter, 5 mm in height). The shear bond strength was tested and the data was analyzed using one-way ANOVA and the Student-Newman-Keuls test.

The following conclusions were drawn.

1. The shear bond strength of Charisma® specimens aged for 1 hour was significantly higher in Group 2 and Group 5 than in Group 1 (p<0.05), and that of Charisma® specimens aged for 1 week was significantly higher in Group 3 and Group 5 than in Group 1 (p<0.05). No significant difference was found in the bond strength of specimens aged for 5 min and 24 hours.

2. In Group 2 of the Charisma® specimens, there was significant difference between the bond strength of 24 hours and that of 1 week (p<0.05).

3. In Group 4 of the Charisma® specimens, the shear bond strength of specimens aged for 24 hours was significantly higher than the others(p<0.05).

4. There was no significant difference between the shear bond strength of the Artglass® specimens.

5. Most of the Charisma® specimens showed cohesive fractures. Artglass® specimens that were etched with acid (phosphoric or hydrofluoric) for 30 sec showed more cohesive fractures.

Purpose of this research is estimating polymerization depth of different source of light. XL 3000 for halogen light, Apollo 95E for plasma arc light and Easy cure for LED light source were used in this study. Different shade (B1 & A3) resin composites (Esthet-X, Dentsply, U.S.A.) were used to measure depth of cure. 1, 2, and 3 mm thick samples were light cured for three seconds, six seconds or 10 seconds with Apollo 95E and they were light cured with XL-3000 and Easy cure for 10 seconds, 20 seconds, or 40 seconds. Vicker's hardness test carried out after store samples for 24 hours in distilled water.

Results were as following.

Curing time increases from all source of lights, curing depth increased(p<0.05).

One fifth dilution of formocresol is usually used for pulpotomy of the primary teeth and emergency pulpotomy of the permanent teeth. However, the use of formaldehyde has been subjected to criticism because it may be absorbed into the blood stream and become distributed systemically, it may also alter the pulp tissue rendering it immunologically active, and have carcinogenic potential. Recently Depulpin®(VoCo., Germany) gains popularity as a devitalizing agent during root canal therapy in spite of high concentration of 49% paraformaldehyde because it facilitate devitalization of pulp and make root canal therapy easier. But there have been not enough publications about the reaction of pulp and periapical tissue caused by Depulpin.

This study was performed to evaluate the histological changes in pulp and periapical tissue of rats after pulpotomy using formocresol and Depulpin and to elucidate the toxic effects of these agents. Thirty six Sprague-Dawley rats were anesthetized by intraperitoneal injection of ketamine. Maxillary first molar teeth were used for pulpotomy with formocresol and Depulpin. Rats were sacrificed after 2 days, 4 days, 1 week, 2 weeks, 3 weeks and 4 weeks respectively. Specimens were histologically observed by light microscope changes in pulp and periapical tissue. The obtained results were as follows.

1. Formocresol group

A zone of fixed tissue, in which odontoblasts could clearly be defined, was present directly underneath the pulpotomy dressing in almost all teeth of this group. This was followed by an area of necrotic tissue which resembled dried out fibrous tissue with no cellular detail except some pyknotic nuclei. In the specimens of after 2 days, 4 days, 1 week, 2 weeks in which vital tissue was present, it was separated from the fibrous area by a zone of inflammation. In the specimens of after 3 weeks and after 4 weeks, inflammatory infiltrate was in the periodontal ligament adjacent to the apical foramina of the teeth.

2. Depulpin® group

The area of necrotic tissue which had no cells and fibers, was present adjacent to the dressing. This was followed by dried out fibrous tissue with no cellular details except some pyknotic nuclei. A short stump of vital pulp with odontoblasts was present at the end of the canal after 2 days. Inflammatory infiltrate was in the periodontal ligament after 4 days and after 1week. Severe root resorption and necrosis of periapical tissue opposite the root resorption site were defined after 2 weeks and after 3 weeks. Periapical lesion which consist of necrotic tissue surrounded by a fibrous connective wall, was found after 4 weeks.

The results indicated that Depulpin can cause more adverse reaction to the dental pulp and periapical tissue than formocresol, and further studies are needed for its clinical use with safety.

This study was performed to evaluate the temperature rise on various position of the Buchanan plugger, the peak temperature of plugger's type and the temperature change by its touching time of heat control spring.

The heat carrier system 'System B'(Model 1005, Analytic Technologies, USA) and the Buchanan's pluggers of F, FM, M and ML sizes are used for this study. The temperature was set to 200℃ which Dr. Buchanan's "continuous wave of condensation" technique recommended on digital display and the power level on it was set to 10. In order to apply heat on the Buchanan's pluggers, the heat control spring was touched for 1, 2, 3, 4 and 5 seconds respectively. The temperature rise on the surface of the pluggers were measured at 0.5 mm intervals from tip to 20 mm length of shank using the infrared thermography (Radiation Thermometer-IR Temper, NEC San-ei Instruments, Ltd, Japan) and TH31-702 Data capture software program (NEC San-ei Instruments, Ltd, Japan). Data were analyzed using a one way ANOVA followed by Duncan's multiple range test and linear regression test.

The results as follows.

1. The position at which temperature peaked was approximately at 0.5 mm to 1.5 mm far from the tip of Buchanan's pluggers (p<0.001). The temperature was constantly decreased toward the shank from the tip of it (p<0.001).

2. When the pluggers were heated over 5 seconds, the peak temperature by time of measurement revealed from 253.3±10.5℃ to 192.1±3.3℃ in a touch for 1 sec, from 218.6±5.0℃ to 179.5±4.2℃ in a touch for 2 sec, from 197.5±3.0℃ to 167.6±3.7℃ in a touch for 3 sec, from 183.7±2.5℃ to 159.8±3.6℃ in a touch for 4 sec and from 164.9±2.0℃ to 158.4±1.8℃ in a touch for 5 sec. A touch for 1 sec showed the highest peak temperature, followed by, in descending order, 2 sec, 3 sec, 4 sec. A touch for 5 sec showed the lowest peak temperature (p<0.001).

3. A each type of pluggers showed different peak temperatures. The peak temperature was the highest in F type and followed by, in descending order, M type, ML type. FM type revealed the lowest peak temperature (p<0.001).

The results of this study indicated that pluggers are designed to concentrate heat at around its tip, its actual temperature does not correlate well with the temperature which Buchanan's "continuous wave of condensation" technique recommend, and finally a quick touch of heat control spring for 1sec reveals the highest temperature rise.

The bleaching of discolored nonvital teeth is conservative treatment that satisfy the cosmetic desire. The most common method for this treatment, walking bleaching, is using 30% hydrogen peroxide and sodium perborate.

Many alternatives are suggested for preventing the external cervical root resorption that is the common complication of the nonvital teeth bleaching with 30% hydrogen peroxide.

The same extent of oxidation reactions as that resulted by the bleaching with the application of 30% hydrogen peroxide and sodium perborate can also be acquired more safely by materials that contain 10% carbamide peroxide, used primarily for the bleaching of vital teeth. Therefore, this study was performed to evaluate the efficacy of 10% and 15% carbamide peroxide bleaching gel in nonvatal teeth bleaching.

The internal bleaching of intentionally discolored teeth was performed in vitro with 10% carbamide peroxide (Group 1), 15% carbamide peroxide (Group 2), mixture of distilled water and sodium perborate (Group 3), and mixture of 30% hydrogen peroxide and sodium perborate (Group 4). The bleaching materials were refreshed following 3, 6, 9 and 12 days. To evaluate the bleaching effect, the color change of the crowns was measured at 1, 2, 3, 4, 7 and 15 days of bleaching using the colorimeter.

The results were as follows :

1. L* and ΔE* values were increased with time in all bleaching agents(p<0.01).

2. There was no significant difference in L* and ΔE* value among bleaching agents.

3. ΔE* value higher than 3 was shown after 3 days of bleaching with 10% carbamide peroxide gel, 1 day with 15% carbamide peroxide gel, 4 days with mixture sodium perborate and distilled water and 4 days with mixture sodium perborate and 30% hydrogen peroxide, respectively.

These results revealed that the use of 10% and 15% carbamide peroxide bleaching gel in non-vital teeth bleaching is as effective as mixture of distilled water and sodium perborate and mixture of 30% hydrogen peroxide and sodium perborate. Accordingly, carbamide peroxide could be used clinically to bleach discolored non-vital teeth.