We report the surgical endodontic treatment of a maxillary first premolar with a lateral lesion that originated from an accessory canal. Although lesions originating from accessory canals frequently heal with simple conventional endodontic therapy, some lesions may need additional and different treatment. In the present case, conventional root canal retreatment led to incomplete healing with the need for further treatment (i.e., surgery). Surgical endodontic management with a fast-setting calcium silicate cement was performed on the accessory canal using a dental operating microscope. At the patient's 9-month recall visit, the lesion was resolved upon radiography.

Palatogingival groove (PGG) is an anomaly in the maxillary anterior teeth, often accompanied by the area of bony destruction adjacent to the teeth with no carious or traumatic history. The hidden trap in the tooth can harbor plaque and bacteria, resulting in periodontal destruction with or without pulpal pathologic change. Related diseases can involve periodontal destruction, combined endodontic-periodontal lesions, or separate endodontic and periodontal lesions. Disease severity and prognosis related to PGG depend on several factors, including location, range, depth, and type of the groove. Several materials have been used and recommended for cases of extensive periodontal destruction from PGG to remove and block the inflammatory source and recover the health of surrounding periodontal tissues. Even in cases of severe periodontal destruction, several studies have reported favorable treatment outcomes with proper management. With new options in diagnosis and treatment, clinicians need a detailed understanding of the characteristics, treatment, and prognosis of PGG to successfully manage the condition.

Although several methods including composite resin restoration and microabrasion have been used for management of white spot lesion, tooth jewelry can be considered as another noninvasive option. This case report describes the management of white spot lesions by using tooth jewelry. This report also highlights the patients' preference for tooth jewelry as an esthetic concern.

The aim of this study was to present a method for endodontic management of a maxillary first molar with unusual C-shaped morphology of the buccal root verified by cone-beam computed tomography (CBCT) images. This rare anatomical variation was confirmed using CBCT, and nonsurgical endodontic treatment was performed by meticulous evaluation of the pulpal floor. Posttreatment image revealed 3 independent canals in the buccal root obturated efficiently to the accepted lengths in all 3 canals. Our study describes a unique C-shaped variation of the root canal system in a maxillary first molar, involving the 3 buccal canals. In addition, our study highlights the usefulness of CBCT imaging for accurate diagnosis and management of this unusual canal morphology.

The purpose of this study was to evaluate the viability of periodontal ligament cells of rat teeth after low-temperature preservation under high pressure by means of MTT assay, WST-1 assay. 12 teeth of Sprague-Dawley white female rats of 4 week-old were used for each group.

Both side of the first and second maxillary molars were extracted as atraumatically as possible under tiletamine anesthesia. The experimental groups were group 1 (Immediate extraction), group 2 (Slow freezing under pressure of 3 MPa), group 3 (Slow freezing under pressure of 2 MPa), group 4 (Slow freezing under no additional pressure), group 5 (Rapid freezing in liquid nitrogen under pressure of 2 MPa), group 6 (Rapid freezing in liquid nitrogen under no additional pressure), group 7 (low-temperature preservation at 0℃ under pressure of 2 MPa), group 8 (low-temperature preservation at 0℃ under no additional pressure), group 9 (low-temperature preservation at -5℃ under pressure of 90 MPa). F-medium and 10% DMSO were used as preservation medium and cryo-protectant. For cryo-preservation groups, thawing was performed in 37℃ water bath, then MTT assay, WST-1 assay were processed. One way ANOVA and Tukey HSD method were performed at the 95% level of confidence. The values of optical density obtained by MTT assay and WST-1 were divided by the values of eosin staining for tissue volume standardization.

In both MTT and WST-1 assay, group 7 (0℃/2 MPa) showed higher viability of periodontal ligament cells than other group (2-6, 8) and this was statistically significant (p < 0.05), but showed lower viability than group 1, immediate extraction group (no statistical significance).

By the results of this study, low-temperature preservation at 0℃ under pressure of 2 MPa suggest the possibility for long term preservation of teeth.

The purpose of this study was to evaluate the viability of periodontal ligament cells in rat teeth using slow cryo-preservation method under pressure by means of MTT assay and WST-1 assay. Eighteen teeth of Sprague-Dawley white female rats of 4 week-old were used for each group.

Both sides of the first and second maxillary molars were extracted as atraumatically as possible under Tiletamine anesthesia. The experimental groups were group 1 (Immediate control), group 2 (Cold preservation at 4°C for 1 week), group 3 (Slow freezing), group 4 (Slow freezing under pressure of 3 MPa). F-medium and 10% DMSO were used as preservation medium and cryo-protectant. For cryo-preservation groups, thawing was performed in 37°C water bath, then MTT assay and WST-1 assay were processed. One way ANOVA and Tukey method were performed at the 95% level of confidence. The values of optical density obtained by MTT assay and WST-1 were divided by the values of eosin staining for tissue volume standardization.

In both MTT and WST-1 assay, group 4 showed significantly higher viability of periodontal ligament cells than group 2 and 3 (p < 0.05), but showed lower viability than immediate control group.

By the results of this study, slow cryo-preservation method under pressure suggests the possibility for long term cryo-preservation of the teeth.

The purpose of this study was to evaluate the viability of periodontal ligament cell in rat teeth using slow cryopreservation method with magnetic field through MTT assay and TUNEL test. For each group, 12 teeth of 4 weeks old white female Sprague-Dawley rat were used for MTT assay, and 6 teeth in TUNEL test. The Maxillary left and right, first and second molars were extracted as atraumatically as possible under tiletamine anesthesia. The experimental groups were group1 (immediately extraction), group 2 (cold preservation at 4℃ for 1 week), group 3 (rapid cryopreservation in liquid nitrogen), group 4 (slow cryopreservation with magnetic field of 1 G), and group 5 (slow cryopreservation). F medium was used as preservation medium and 10% DMSO as cryoprotectant. After preservation and thawing, the MTT assay and TUNEL test were processed. One way ANOVA and Scheffe method were performed at the 95% level of confidence. The value of optical density obtained after MTT analysis was divided by the value of eosin staining for tissue volume standardization. In both MTT assay and TUNEL test, it had showed no significant difference among group 3, 4, and 5. And group 3 had showed higher viability of periodontal ligament cell than group 2.

From this study, slow cryopreservation method with magnetic field can be used as one of cryopreservation methods.

The purpose of this study was to verify the usefulness of MTT analysis as a tool of measurement of the periodontal ligament cell viability from the extracted rat molar.

A total of 80 Sprague-Dawley white female rat of 4 week-old with a body weight of 100 grams were used. The maxillary left and right, first and second molars were extracted under Ketamine anesthesia. Twenty-four teeth of each group (divided as five groups depending upon the time-lapse after extraction such as immediate, 10, 20, 40 and 60 minutes) were immersed in 200 µl of MTT solution (0.5 mg/ml) and processed for optical density measurements . Another 10 teeth of each group were treated as same as above and sectioned at 10 µm for microscopic examination.

All measurements values were divided by the value of hematoxylin-eosin staining which represented the volume of each corresponding samples. Immediate and 10 minute groups showed highest MTT values followed by 20, 40, and 60 minutes consecutively. Statistical significance (p < 0.05) existed between all groups except in immediate versus 10 minute groups and 40 versus 60 minutes. Histological findings also showed similar findings with MTT results in crystal shape and crystal numbers between the experimental groups.

These data indicate that in vivo MTT analysis may be of value for evaluation of the periodontal ligament cell viability without time- consuming cell culturing processes.

The purpose of this study was to examine the viability of PDL cells in rat molars by using in vivo MTT assay, which was used to compare fast cryopreservation group by liquid nitrogen (-196℃) with 4℃ cold preservation group.

A total of 74 Sprague-Dawley white female rats of 4 week-old with a body weight of 100 grams were used. The maxillary left and right, first and second molars were extracted as atraumatically as possible under ketamine anesthesia.

Ten teeth of each group were divided as six experimental groups depending upon the preservation. Cryopreservation groups were Group 1 (5% DMSO 6% HES in F medium), Group 2 (10% DMSO in F medium), Group 3 (5% DMSO 6% HES in Viaspan®), Group 4 (10% DMSO in Viaspan®) which were cryopreserved for 1 week and cold preservation groups were Group 5 (F medium), Group 6 (Viaspan®) at 4℃ for 1 week. Immediate extraction group was used as a control. After preservation and thawing, the in vivo MTT assay was processed. Two way ANOVA and Duncan's Multiple Range Test was performed at the 95% level of confidence. Another 2 teeth of each group were treated as the same manner and frozen sections 10 µm thick for microscopic observation.

The value of optical density obtained after in vivo MTT analysis was divided by the value of eosin staining for tissue volume standardization. Group 1, 2 had significantly higher optical density than Group 3 and 4 which had the lowest OD value. Group 6 had higher OD value than in Group 5 (P < 0.05). Histological findings of periodontal ligament cell, after being stained with MTT solution were consistent with the in vivo MTT assay results.

In this study, the groups which were frozen with DMSO as a cryoprotectant and the groups with F medium showed the best results.

This study compared the microshear bond strength (µSBS) to end and side of enamel rod bonded by four adhesives including two total etch adhesives and two self-etch adhesives.

Crown segments of extracted human molars were cut mesiodistally. The outer buccal or lingual surface was used as specimens cutting the ends of enamel rods, and inner slabs used as specimens cutting the sides of enamel rods.

They were assigned to four groups by used adhesives: Group 1 (All-Bond 2), Group 2 (Single Bond), Group 3 (Tyrian SPE/One-Step Plus), Group 4 (Adper Prompt L-Pop). After each adhesive was applied to enamel surface, three composite cylinders were adhered to it of each specimen using Tygon tube. After storage in distilled water for 24 hours, the bonded specimens were subjected to µSBS testing with a crosshead speed of 1 mm/minute. The results of this study were as follows;

1. The µSBS of Group 2 (16.50 ± 2.31 _MPa) and Group 4 (15.83 ± 2.33 _MPa) to the end of enamel prism was significantly higher than that of Group 1 (11.93 ± 2.25 _MPa) and Group 3 (11.97 ± 2.05 _MPa) (p < 0.05).

2. The µSBS of Group 2 (13.43 ± 2.93 _MPa) to the side of enamel prism was significantly higher than that of Group 1 (8.64 ± 1.53 _MPa), Group 3 (9.69 ± 1.80 _MPa), and Group 4 (10.56 ± 1.75 _MPa) (p < 0.05).

3. The mean µSBS to the end of enamel rod was significantly higher than that to the side of enamel rod in all group (p < 0.05).

The purpose of this study was to investigate the effects of estrogen deficiency on pulpodentinal complex of tooth in ovariectomized rats. Thirty female Sprague-Dawley rats, 10 weeks old, were used. Rats were grouped into two groups. One group (n = 15) was subjected to sham surgery (SHAM) and the other group (n = 15) was ovariectomized bilaterally (OVX). Animals were sacrificed 12 weeks later, and their mandibular molars and associated periodontal supporting tissues were dissected out, and fixed in 10% buffered formalin. For comparison of groups, immunostained for osteonectin. Histomorphometrical measurement of change of teeth was performed using an image analysis system and paired t-test was used and the level of significance for overall differences was set at p < 0.05.

In immunostaining of osteonectin, they were significantly different from each other. The predentin thickness in OVX rats was wider than in SHAM rats. And in SHAM rats, osteonectin was more specifically stained in predentin areas than in OVX rats. These results indicate that estrogen deficiency increased the unmineralized predentin areas and decreased osteonectin content in pulpal tissues in rats. If our result is applicable to human studies, odotoblast is affected by estrogen deficiency.

The purposes of this study were to evaluate the effect of adhesive property on microtensile bond strength and to determine the failure mode.

Flat occlusal dentin surfaces were prepared using low-speed diamond saw. The dentin was etched with 37% phosphoric acid. The following adhesives were applied to the etched dentin to manufacturer's directions; Scotchbond Multi-Purpose in group SM, Prime&Bond NT in group NT, Scotchbond Multi-Purpose followed by Tetric-flow in group TR. After adhesive application, a cylinder of resin-based composite was built up on the occlusal surface. Each tooth was sectioned vertically to obtain the 1 × 1mm² "sticks". Microtensile bond strength were determined. Each specimen was observed under stereomicroscope and scanning electron microscope (SEM) to examine the failure mode. Data were analyzed using one way ANOVA.

The results of this study were as follows;

1. The microtensile bond strength value were; group SM (18.98 ± 3.01MPa), group NT (16.01 ± 4.82MPa) and group TR (17.56 ± 3.22MPa). No significant statistical differences were observed among the groups (P>0.05).

2. Most of specimens showed mixed failure. In group TR, there was a higher number of specimens showing areas of cohesive failure in resin.

The purpose of this study was to evaluate the effect of immediate or delayed composite resin filling on dentinal microtensile bond strength (µTBS) after applied the adhesive.

The coronal dentin of human third molars was exposed. Single-Bond or One-Step was applied on the dentin surfaces, and composite resin were constructed immediately (group 1) or 5 min., 10 min., 15 min., 20 min. and 30 min. (groups 2-6) after an adhesive was applied. The specimens were sectioned and made bar-shaped. Each surface area of them was about 1mm². The µTBS test was performed by EZ test. The results were analysed by One-way ANOVA and Tukey's test at 95% significance level.

The results suggested that the µTBS of Single-Bond to dentin was decreased when the composite resin was constructed 20 min. and 30 min. after Single-Bond was applied. But the µTBS of One-Step was not affected by delayed composite resin filling.

This study evaluated the microleakage and interfacial gap between enamel and composite resin under the dry and wet condition of the enamel surface. V shaped class 5 cavities were prepared on the occlusal portion of extracted human molars. Samples were divided into three groups: D group (air dry for 10-15 s), BD group (blot dry with moist cotton pellet), and DR group (air dry for 10-15 s and rewet with Aqua-Prep F for 20 s).

Cavities were filled using Aelitefil composite resin after applied One-Step. Microleakage was tested by 2% methylene blue dye solution and the data were statistically analysed by Kruskal-Wallis test and Mann-Whitney test. Also Enamel-resin interface was observed under SEM. Group BD showed statistically lower microleakage than group D (p < 0.05), but there was no statistically significant difference between group BD and DR (p > 0.05). At the enamel-resin interface, group D showed the gap of 2 µm thickness, but group BD and DR showed close adaptation.

In conclusion, the use of blot dry and rewetting agent (Aqua-Prep F) resulted in decreased microleakage and improved adhesion between enamel and resin when using One-Step.

This study evaluated the influence of application time of self-etching primers on microtensile bond strength (μTBS) to dentin using three self-etching primer adhesive systems.

Dentin surfaces were exposed from forty-eight human molars. They were conditioned with three self-etching primers (Clearfil SE Bond [SE], Unifil Bond [UF], Tyrian SPE + One Step Plus [TY]) and different primining times (10s, 20s, 30s and 40s). Composite resins were bonded to dentin surfaces and specimens were made. μTBS was tested and statistically compared using by one-way ANOVA and Tukey’s Test.

The results of this study presented that priming time for 10s in SE and UF groups and for 30s and 40s in TY group was highly decreased μTBS to dentin.

The purpose of this study is to examine the viability of PDL cells in rat molars by using MTT assay and to verify the MTT assay through the histologic observation. Thirty of Sprague-Dawley white female rats of 4-weeks old with a body weight of about 100 grams were used. Groupings are as follows:

Immediate Group : Positive control group(n=10)-after extraction immediately.

Dried Group : Negative control group(n=10)-after drying for an hour under warm dry.

ViaSpan® Group : 1hour ViaSpan® group(n=10)-after storing in ViaSpan® at 4℃ for 1hour.

Ten teeth of each group were treated as same as above and replanted to the original socket of experimental animals. After two weeks of replantation, all the experimental animals were sacrificed. And after fixation, extracted maxillary jaw was dimineralized. After it was embedded in paraffin, serial section by 5µm was carried out and for construction of specimen, hematoxylin-eosin dye was used.

The mean MTT measurement of immediate group(positive control) is 2.81 and the mean measurement of dried group(negative control) is 0.98 which is significant differnt(P<0.05). The mean measurement of ViaSpan® group is 2.65 and there is significant difference between dried group and ViaSpan® group(P<0.05). However, there is no difference between immediate group and ViaSpan® group. The average resorption points of immediate group is 3.03 points. In the dried group, average 6.44 points resorption and 2.68 points showed resorption in the ViaSpan® group. Unlike with MTT assay, there was no significant difference between the immediate group and ViaSpan® group.

The usage of MTT assay as a viable cell marker may give us a better indication of the maintenance of periodontal ligament cell vitality.