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.

When curing the composite restorations with light curing units, the light guides are often in direct contact with oral tissues, therefore contamination of light guides is inevitable. Curing light guides fall into the "semicritical" instrument category according to the Centers for Disease Control and Prevention (CDC) and must be heat or vapor-sterilized or at a minimum, these semicritical instruments must be sterilized in a liquid chemical agent. Currently, most common methods of maintaining sterility of the light guides are wiping the guide with a disinfectant, such as glutaraldehyde, after each patient use; using autoclavable guides; using presterilized, single-use plastic guides; and using translucent disposable barriers to cover the guide.

The purpose of this study was to compare the effect of curing methods of adhesive resins and resin cements in the root canal. Crown portions of 32 single-rooted mandibular premolars were removed. Routine endodontic treatment was done, and 9 mm deep post spaces were prepared within root canals. No. 3 FRC Postec posts (Ivoclar-Vivadent AG, Liechtenstein) were cemented in the post spaces by self-(SC) or light-curing (LC) using two dual-cured adhesives (Adper Scotchbond multi-purpose plus and Exite DSC )and resin cements (RelyX ARC and Variolink II). They were assigned to 4 groups (n=8); R-SC, R-LC, V-SC, V-LC group.

After stored in distilled water for 24 hours, each root was transversally sectioned with 1.5 mm thick and made three slices. The specimens were subjected to push-out test in a universal testing machine (EZ Test, Shimadzu Co., Japan) with a crosshead speed of 1 mm/min. The data were analyzed with repeated ANOVA and one-way.

ANOVA. Also the interface of post-resin cement and resin cement-canal wall of each group was observed under FE-SEM.

When fiber posts were cemented into the root canal using total-etch adhesives, the bond strength and adaptation between post and root canal dentin was affected by curing method. Self-cure of adhesives and resin cements showed higher bond strength and closer adaptation than light-cure of them.

The purpose of this study was to perform quantitative comparisons of water permeable zones in both the adhesive and the hybrid layer before and after thermocycling in order to assess the integrity of the bonding interface. Twenty eight flat dentin surfaces were bonded with a light-cured composite resin using one of four commercial adhesives [OptiBond FL (OP), AdheSE (AD), Clearfil SE Bond (CL), and Xeno III (XE)]. These were sectioned into halves and subsequently cut to yield 2-mm thick specimens; one specimen for control and the other subjected to thermocycling for 10,000 cycles. After specimens were immersed in ammoniacal silver nitrate for 24 h and exposed to a photo developing solution for 8 h, the bonded interface was analyzed by scanning electron microscopy (SEM) and wavelength dispersive spectrometry (WDS) at five locations per specimen. Immediately after bonding, the adhesive layer of OP showed the lowest silver uptake, followed by CL, AD, and XE in ascending order (p < 0.0001); the hybrid layer of CL had the lowest silver content among the groups (p = 0.0039). After thermocycling, none of the adhesives manifested a significant increase of silver in either the adhesive or the hybrid layer. SEM demonstrated the characteristic silver penetrated patterns within the interface. It was observed that integrity of bonding was well maintained in OP and CL throughout the thermocycling process. Adhesive-tooth interfaces are vulnerable to hydrolytic degradation and its permeability varies in different adhesive systems, which may be clinically related to the restoration longevity.

The purpose of this study was to compare the normal and two times of application time of six self-etching primers applied to enamel using microshear bond strength (uSBS) test and the finding of scanning electronic microscope (SEM).

Crown of sixty human molars were bisected mesiodistally and buccal and lingual enamel of crowns were partially exposed and polished with 600 grit SiC papers. They were divided into one of two equal groups subdivided into one of six equal groups (n = 10) by self-etching primer adhesives.

After the same manufacture's adhesive resin and composites were bonded on the enamel surface of each group, the bonded specimens were subjected to uSBS testing and also observed under SEM.

In conclusion, generally two times of primer application time increased the enamel uSBS, especially with the statistical increase of bond strength in adhesives involving high-pH primers.

The fracture toughness test is believed as a clinically relevant method for assessing the fracture resistance of the dentinal restoratives. The objectives of this study were to measure the fracture toughness (K_1C) and microtensile bond strength of dentin-resin composite interface and compare their relationship for their use in evaluation of the integrity of the dentin-resin bond.

A minimum of six short-rod specimens for fracture toughness test and fifteen specimens for microtensile bond strength test was fabricated for each group of materials used. After all specimens storing for 24 hours in distilled water at 37℃, they were tensile-loaded with an EZ tester universal testing machin. Statistical analysis was performed using ANOVA and Tukey's test at the 95% confidence level, Pearson's coefficient was used to verify the correlation between the mean of fracture toughness and microtensile bond strength. FE-SEM was employed on fractured surface to describe the crack propagation.

Fracture toughness value of Clearfil SE Bond (SE) was the highest, followed by Adper Single Bond 2 (SB), OptiBond Solo (OB), ONE-STEP PLUS (OS), ScotchBond Multi-purpose (SM) and there was significant difference between SE and other 4 groups (p < 0.05). There were, however, no significant difference among SB, OB, OS, SM (p > 0.05). Microtensile bond strength of SE was the highest, followed by SB, OB, SM, OS and OS only showed significant lower value (p < 0.05). There was no correlation between fracture toughness and microtensile bond strength values. FE-SEM examination revealed that dentin bonding agent showed different film thickness and different failure pattern according to the film thickness.

From the limited results of this study, it was noted that there was statistically no correlation between K1C and µTBS. We can conclude that for obtaining the reliability of bond strength test of dentin bonding agent, we must pay more attention to the test procedure and its profound scrutiny.

The purpose of this study was to investigate the effect of calcium hydroxide on dentin bonding strength of various dentin bonding systems as a function of time in composite resin restoration.

Dentin adhesives used in this study were Scotchbond Multipurpose, Single Bond, SE Bond and Prompt L-Pop. Flat dentin surfaces adjacent to pulp chamber were created, then Ca(OH)₂ and saline were mixed and applied on dentin surface of experimental group, then IRM was used to cover the mixture on dentin surface and the specimens were stored at 36.5℃ for experiment period (7 days, 30 days). After removing IRM and Ca(OH)₂, each dentin adhesives were treated on dentin surfaces.

Composite resin (Z-250, 3M) was placed with 5 mm height and was light-cured for 20 seconds. After stored in distilled water for 24 hours, each dentin-composite bonded spicemen was embedded in epoxy resin and sectioned into 1.0 × 1.0 mm² cross section composite-dentin beams. Specimen was mounted on zig of Universal testing machine and µTBS test was performed. SEM analysis was performed to examine the fractured surfaces.

The results suggested that applying calcium hydroxide did not show significant difference in dentin bonding strength.

The purpose of this study was to estimate the relation between techniques used for microleakage from dye penetration and for marginal adaptation from SEM evaluation of the restoration.

Using high speed #330 bur, class V cavities (4 × 3 × 1.5 mm around CEJ) were prepared on the buccal surface of 20 extracted human molars. Six dimples as reference points for SEM and dye penetration evaluation were made with 1/2 round bur. Cavity was bulk filled with microhybrid composite resin (Esthet X) and all-in-one adhesive (Xeno III). Teeth were stored in saline solution for one day, after then, they were finished and polished using Sof-Lex system.

Fifty percent silver nitrate dye solution was used for the evaluation of microleakage and resin replica was used for marginal adaptation. All of these were done after 1000 times thermocycling between 5 and 55℃.

Vertical sections were made through three dimples of restoration to obtain samples for the evaluation of dye penetration and inner marginal adaptation. Outer adaptational estimation was done with an intact restoration before sectioning. Dye penetration was determined in three degrees and percentage of outer and inner leaky margin was estimated from SEM image.

The data were analysed statistically: Spearman's rho test were used to check relationships between two methods.

The result were as follows:

There were significant relationships between degree of dye penetration and inner and outer marginal adaptations each (p < 0.01).

Within the results of this study, relationship between the percentage of marginal adaptation and microleakage shows significant relationship. However, inner and outer marginal adaptation did not show any significant relationship mutually.

Intracanal separation of the rotary files is a serious concern in modern endodontic practice. The objective of this study was to compare the life span and fracture patterns of three NiTi rotary files in molar teeth.

Mesiobuccal roots of upper molar (n = 150) and mesial roots of lower molar (n = 150) were divided into three groups and each group was prepared with Profile, ProTaper, and K3 respectively. Every file was used until separation and/or deterioration of the cutting blade was happened, and then the number of canals to separation and/or unwinding were recorded. Radiographs and Scanning electon microscope (SEM) photographs were taken to evaluate the patterns of separation.

The results were as follows :

1. There were no significant differences in numbers of canals to separation and/or unwinding among the groups.

2. Comparing between flaring files, K3 showed significant lower numbers of canals to separation and/or unwinding (p < 0.05), and there was no significant difference between shaping files

3. Separations of instruments were occurred at the midpoint of curvatures within the canals.

4. In SEM observations, ductile fractures were seen in most of cases, characterized by shallow dimples.

Additional researches is needed to provide a new guideline that informs the appropriate number of times to use NiTi files.

This study was done to evaluate whether there were any differences in microleakage of class V composite restorations according to restoration site and cavity size.

Total sixty-four restorations were made in molar teeth using Esthet-X. Small (2 × 2 × 1.5 mm) and large (4 × 2 × 1.5 mm) restorations were made at the buccal/lingual surface and the proximal surface each. After 1,000 times of thermocycling (5℃ - 55℃), resin replica was made and the percentage of marginal gap to the whole periphery of the restoration was estimated from SEM evaluation.

Thermocycled tooth was dye penetrated with 50% silver nitrate solution. After imbedding in an auto-curing resin, it was serially ground with a thickness of 0.25 mm. Volumetric microleakage was estimated after reconstructing three dimensionally.

Two-way ANOVA and independent T-test for dye volume, Mann-Whitney U test for the percentage of marginal gap, Spearman's rho test for the relationship between two techniques were used.

The results were as follows:

1. The site and size of the restoration affected on the microleakage of restoration. Namely, much more leakage was seen in the proximal and the large restorations rather than the buccal/lingual and the small restorations.

2. Close relationship was found between two techniques (Correlation coefficient = 0.614 / P = 0.000).

Within the limits of this study, it was noted that proximal and the large restorations leaked more than buccal/lingual and the small restorations. Therefore, it should be strictly recommended large exposure of margins should be avoided by reducing unnecessary tooth reduction.

Established microleakage tests have their own disadvantages. In this study, 3D reconstruction method was tried to overcome these disadvantages.

Four types of microleakage tests were used and relationships among them were estimated: penetrated dye volume; marginal adaptability; degree of dye penetration and relative penetrated length to cavity wall.

Twenty-four Class V cavities were bulk filled with composite (Esthet X) following surface treatments: N group (no treatment); E group (etching only); T group (etching + Prime & Bond NT). 50% silver nitrate was used as a dye solution after thermocycling (5℃ & 55℃, 1,000 times). Teeth were serially ground with a thickness of 0.2 mm. Volume of dye penetration was estimated from a three-dimensionally reconstructed image with a software (3D-DOCTOR). Percentage of margin without gap was estimated from SEM and degree of dye penetration and the relative length of dye penetration to overall cavity wall were also estimated.

ANOVA and Scheffe test for dye volume, Kruskal-Wallis and Mann-Whitney test for marginal quality, Spearman's rho test for checking of relationships among methods were used.

The results were as follows:

1. Dye penetration could be seen from several directions, furthermore, its volumetric estimation was possible.

2. Reverse relationship was found between dye volume and marginal quality (r = -0.881 / p = 0.004).

3. Very low relationship was seen between dye volume and two-dimensional tests (degree of dye penetration and relative length). However, 2D evaluation methods showed high relationship (p = 0.002-0.054) each other.

4. Three times vertical section could be recommended as a 2D test.

The purpose of this study was to evaluate the efficiency of the preparation of oval canals using hand and engine-driven instruments with SEM observation. Thirty single-rooted teeth with oval canal were used in this study. The teeth were divided into 3 groups. In group A, the teeth were instrumented up to a size 35 K-file using RC-prep and irrigated with 5% NaOCl between each file size. In group B, the teeth were instrumented with Profile according to the manufacture's instructions using RC-Prep and irrigated with 5% NaOCl between each file size. In group C, the teeth were instrumented with GT file according to the manufacture's instructions using RC-prep and irrigated with 5% NaOCl between each file size. Then, in all teeth, a final flush of 5ml of distilled water delivered for 30s. Canals were dried with sterile standardized paper points. After preparing the canals, the teeth were sectioned along their mesial and diatal surfaces by using low-speed diamond disc, chisel and mallet. Each root section was then dehydrated in graded concentration of alcohol (70, 80, 90, 100%), mounted on an aluminum stub, sputter-coated with gold-palladium and observed with scanning electron microscope (HITACHI S-4200) in middle and apical area.

The results of this study were as follows:

In the middle area, group B and group C showed less smear layer than group A, and it was statistically significant (p < 0.05).

All-in-one adhesives were recently developed for reducing the techique sensitivity and chair time, but lots of concerns were made on bondability, longevity, and microleakage.

The object of this study was to evaluate microleakage and marginal quality of all-in-one adhesives using electrochemical method and SEM analysis quantitatively.

After making Class V cavities, they were bulk filled with Heliomolar(#A1) after surface treatment with three adhesives: Adper Prompt (Group A), One up bond F (Group O), Xeno III (Group X). Electrical conductivity (microamphere, µA) was checked two times: before and after cavity filling.

Percentage of leaky margin was estimated from SEM image (×1,000).

The data were statistically analysed: ANOVA and Paired T test for electrical conductivity, Kruskal-Wallis and Mann-Whitney test for marginal quality, Spearman's rho test for checking of relationships between 2 methods.

The result were as follows:

1. There was no difference in microleakage between adhesive systems and every specimen showed some of microleakage after filling.

2. Microleakage was reduced about 70% with composite resin filling.

3. Marginal quality was the best in group A, decreasing among groups in the following order: group O, followed by group X. There were significant differences between group A and group X (p=0.015), and between group O and group X (p=0.019).

4. There was no relationship between the microleakage measured by electrochemical method and marginal quality measured by SEM analysis.

Within the results of this study, there was no difference in microleakage among groups by electrical conductivity. However, significant difference in marginal quality was seen among groups. It was believed that these dissimilar results might be induced because of their own characteristics. Analysis of microleakage needs various methods for accuracy.

The purpose of this study was to compare shear bond strength and interfacial pattern of composite bonded to dentin using self-etching adhesive systems.

Sixty extracted human molars with exposed occlusal dentin were divided into four groups and bonded with four adhesives and composites: Single Bond/Filtek Z 250(SB), Tyrian SPE-One-Step Plus/Aelitefil(TY), Prompt L-Pop/Filtek Z 250(LP), and One-Up Bond F/Palfique Toughwell(OU).

The results of this study were as follows;

Shear bond strength for OU was significantly lower than that of other groups(p<0.05). No significant difference was founded among SB, TY, and LP.

The purpose of this study was to compare in vitro interfacial relationship of restorations bonded with three self-etching primer adhesives and one self-etching adhesive.

Class I cavity preparations were prepared on twenty extracted human molars. Prepared teeth were divided into four groups and restored with four adhesives and composites: Clearfil SE Bond/Clearfil™ AP-X (SE), UniFil Bond/UniFil® F (UF), FL Bond/Filtek™ Z 250 (FL) and Prompt L-Pop/Filtek™ Z 250 (LP)

After storing in distilled water of room temperature for 24 hours, the specimens were vertically sectioned and decalcified. Morphological patterns between the enamel/dentin and adhesives were observed under SEM.

The results of this study were as follows;

1. They showed close adaptation between enamel and SE, UF and FL except for LP.

2. The hybrid layer in dentin was 2 µm thick in SE, 1.5 µm thick in UF, and 0.4 µm in both FL and LP. So, the hybrid layers of SE and UF were slightly thicker than that of FL and LP.

3. The lengths and diameters of resin tags in UF and FL were similar, but those of LP were slightly shorter and slenderer than those of SE.

4. The resin tags were long rod shape in SE, and funnel shape in other groups.

Within the limitations of this study, it was concluded that self-etching primer adhesives showed close adaptation on enamel. In addition, the thickness of hybrid layer ranged from 0.4-1.5 µm between adhesives and dentin. The resin tags were long rod or funnel shape, and dimension of them was similar or different among adhesives.

This study compared the dentin adhesion to composite resin according to air-dry, blot dry, application of rewetting agent on air-dry or blot dry dentin surface by microleakag test and SEM observation.

For microleakage test, class V cavity preparations with dentinal margins were prepared on both buccal and lingual surfaces of 40 extracted human molars. For SEM observation, occlusal dentin of 20 extracted human molars were exposed.

After etched the dentin, prepared teeth were randomly divided into four groups;

D group: air dry for 10-15 sec., B group: blot dry with moist cotton pellet, D-R group: air dry and rewet with Aqua-Prep F for 20 sec., B-R group: blot dry and rewet with Aqua-Prep F for 20 sec.

Treated cavities and surfaces were filled or constructed using One-Step adhesives and Aelitefil composite resins. Specimens were stored in distilled water for 24 hours. For microleakage test, the specimens were thermocycled and soaked into 2% methylene blue. The specimens were sectioned longitudinally and evaluated for microleakage under steromicroscope. The data were statistically analysed by Kruskal-Wallis Test, Mann-Whitney and Wilcoxon signed ranked tests. For SEM observation, the specimens were bisectioned mesiodiatally. After decalcified and deproteinized, specimens were observed under SEM.

The results of this study were as follows;

1. The microleakges on dentinal margin were the highest in D group compared with B group, D-R group, and B-R group(p<0.05). But there was no significant difference between B group, D-R group and B-R group.

2. D group showed gap and a few resin tags between dentin and composite resin.

3. B group, D-R group, and B-R groups showed close adaptation between dentin and composite resin. It showed that resin rags in B group were numerous and long, in D-R group were few and short, in B-R group were numerous and short or long.

4. Adhesive layer showed in D-R group (10 µm) and B-R group (3 µm)

In conclusion, use of rewetting agent to dry dentin was efficient to dentin adhesion, also it did not provide reverse effect on blot dry dentin.