Effect of polishing methods on color change by water absorption in several composite resins

PURPOSE: The aim of this study was to evaluate the influence of polishing methods on the color stability of composite resins. MATERIALS AND METHODS: Two bulk-fill and four conventional resin composites were filled in cylindrical molds (6 mm diameter, 4 mm height) and light-cured. The specimens were stored in 34℃ distilled water for 24 h. Spectrophotometer was used to determine the color value according to the CIE L(*)a(*)b(*) color space. Each group was divided into three groups according to polishing methods (n = 5). Group 1 was control group (Mylar strip group), group 2 was polished with PoGo, and group 3 was polished with Sof-Lex Spiral wheels. Color evaluation was performed weekly for 4 weeks after immersion in 34℃ distilled water. The results were analyzed by generalized least squares method (P < 0.05). RESULTS: Generalized least squares analysis revealed that Sof-Lex Spiral wheels group showed the significantly lower ΔE values compared to PoGo and control group (P < 0.05). The ΔE values of polished group showed the significantly lower than the ΔE values of unpolished group (P < 0.05). Regarding color changes of composite resins, there was no significant difference between the ΔE values of Filtek Z250 and Filtek Z350 XT Universal restorative in all time intervals (P < 0.05). Tetric N-Ceram Bulk Fill showed the significantly lower ΔE values compared to other composite resins in 1, 2, 3 weeks (P < 0.05). CONCLUSION: Within the limitations of this study, polishing methods influence the color stabilities of composite resins. The group polished with Sof-Lex Spiral Wheels showed more resistance to discoloration than group polished with PoGo.

Interaction of Hydroxyethylidene bisphosphonate (HEBP) with other endodontic irrigants on tissue dissolving capacity and antimicrobial effect

PURPOSE: The purpose of this study was to evaluate tissue dissolving capacity, antimicrobial effect of Hydroxyethylidene bisphosphonate (HEBP) interacting with sodium hypochlorite (NaOCl), Ethylenediaminetetraacetic acid (EDTA) as conventional endodontic irrigants and to determine tissue dissolving efficacy depended on temperature. MATERIALS AND METHODS: A total of 80 bovine muscles were randomly distributed into 8 groups (n = 10). After their initial weights determined on a precision scale, the specimens in each group were immersed in the solutions for 5, 10 and 15 min and reweighted at each time period. Agar diffusion test inoculated with Enterococcus faecalis was performed for antimicrobial effect of each endodontic irrigants. RESULTS: The ability to dissolve organic matter was greater in NaOCl group following NaOCl and HEBP mixture. Heated NaOCl (40℃) and NaOCl/HEBP mixture was greater tissue dissolving efficacy than room temperature (25℃). Antimicrobial effect was greater and significant in the following order EDTA > EDTA + 1% NaOCl > 1% NaOCl ≥ 1% NaOCl + HEBP. CONCLUSION: HEBP as soft chelating agent does not disturb antimicrobial effect and less affected tissue dissolving efficacy as inherent properties of NaOCl. In the heated NaOCl/HEBP mixture analyzed, it dissolved more the organic matter than room temperature.

Cross-sectional morphology and minimum canal wall widths in C-shaped root of mandibular molars / 대한치과보존학회지

The C-shaped canal system is an anatomical variation mostly seen in mandibular second molars, although it can also occur in maxillary and other mandibular molars. The main anatomical feature of C-shaped canals is the presence of fins or web connecting the individual root canals. The complexity of C-shaped canals prevents these canals from being cleaned, shaped, and obturated effectively during root canal therapy, and sometimes it leads to an iatrogenic perforation from the extravagant preparation. The purpose of this study was to provide further knowledge of the anatomical configuration and the minimal thickness of dentinal wall according to the level of the root. Thirty extracted mandibular second molars with fused roots and longitudinal grooves on lingual or buccal surface of the root were collected from a native Korean population. The photo images and radiographs from buccal, lingual, apical direction were taken. After access cavity was prepared, teeth were placed in 5.25% sodium hypochlorite solution for 2 hours to dissolve the organic tissue of the root surface and from the root canal system. After bench dried and all the teeth were embedded in a self-curing resin. Each block was sectioned using a microtome (Accutom-50, Struers, Denmark) at interval of 1 mm. The sectioned surface photograph was taken using a digital camera (Coolpix 995, Nikon, Japan) connected to the microscope. 197 images were evaluated for canal configurations and the minimal thickness of dentinal wall between canal and external wall using' Root Thickness Gauge Program' designed with Visual Basic. The results were as follows: 1. At the orifice level of all teeth, the most frequent observed configuration was Melton's Type C I (73%), however the patterns were changed to type C II and C III when the sections were observed at the apical third. On the other hand, the type C III was observed at the orifice level of only 2 teeth but this type could be seen at apical region of the rest of the teeth. 2. The C-shaped canal showed continuous and semi-colon shape at the orifice level, but at the apical portion of the canal there was high possibility of having 2 or 3 canals. 3. Lingual wall was thinner than buccal wall at coronal, middle, apical thirds of root but there was no statistical differences.

Immunohistochemical Study of Collagenase-3(Matrix Metalloproteinase-13) in Squamous Cell Carcinomas of the Head and Neck / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Squamous cell carcinomas (SCCs) of the head and neck are known for their aggresive growth and propensity to metastasize, which often results in poor prognosis. Tumor cell interaction with the basement membrane has historically been viewed as the crucial step in tumor invasion and future metastasis. The invasive and metastatic process of malignant tumors requires the expression and activation of proteolytic enzymes which facilitate the progression of tumor cells in different ways. Among these proteolytic enzymes, collagenase-3 (matrix metalloproteinase-13) is a recently identified member of the MMP family, and is expressed in breast carcinomas and in articular cartilage from arthritic patients. The substrate specificity of MMP-13 is exceptionally wide as compared to other MMPs. MATERIALS AND METHODS: We performed immunohistochemical stains on 10 normal mucosas and 35 SCCs of the head and neck with anticollagenase-3 antibody and analysed the staining patterns. RESULTS: As a result, the expression of the MMP-13 were detected in 23 of the 35 SCCs (66%), but no expression was detected in any of the 10 normal mucosa. The expression of MMP-13 in most tumors was localized predominantly in neoplastic cells at the invading periphery of the tumor (74%;17/23). A significant correlation was found between MMP-13 expression and local tumor invasion but no correlation was observed between expression and the age, sex of the patients, histological grade, lymph node metastases, recurrence, or the stage of the tumors. CONCLUSION: These findings suggest that MMP-13 expression may contribute to the progression of a significant subset in SCCs of the head and neck. In the future, it is likely that elucidation of the regulatory mechanisms of the MMP-13 in SCCs may prove to be beneficial in developing novel therapeutic modalities for preventing invasion of these neoplastic cells.

A case of Microcystic Adnexal Carcinoma in the External Auditory Canal / 대한이비인후과학회지

Microcystic adnexal carcinoma (MAC) is a rare malignant skin appendageal tumor first described as a specific entity in 1982. It predominantly affects the head and neck, particularly in the centrofacial region. MAC can have a benign appearance under the light microscope. Despite this bland histologic appearance, MAC can be locally aggressive with permeation of perineural spaces, perichondriums, skeletal muscles and so on. Therefore, this tumor is characterized by high morbidity and frequent recurrence in spite of aggressive treatment such as wide local excision, Mohs' microscopic surgery, or radiation therapy. Close observation for a long term is therefore mandatory even after a satisfactory excision with a wide resection margin. Recently, the authors have experienced a case of MAC in the external auditory canal which was treated by wide local excision and skin graft.

Gallbladder Cancer Associated with an Anomalous Union of the Pancreaticobiliary Duct and a Choledochal Cyst / 대한소화기내시경학회지

An anomalous pancreaticobiliary ductal union is a rare anomaly occurring in the biliary tract. This anomaly has been implicated as a cause of choledochal cysts, bile duct and gallbladder carcinoma, and recurrent pancreatitis. A case is herein reported of a 63 year-old woman who suffered from gallbladder cancer associated with a choledochal cyst and an anomalous pancreaticobiliary union.

Prognostic Significance of Ki-67 Index and Expression of Cyclin D1 in Squamous Cell Carcinoma of the Larynx and Hypopharynx / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Various host and tumor parameters, particularly by the tumor size and lymph node metastasis have been studied in an attempt to evaluate and decide the optimal treatment of the patients with head and neck squamous cell carcinoma. However, it has been necessary that the prognostic parameters can be useful to evaluate the biological behaviors of the malignancy. The Ki-67 is a proliferative marker of tumor cells and cyclin D1 is a cell cycle regulator essential for G1 phase progression. Loss of regulation of cyclin D1 is likely to contribute to tumor development. The author evaluated the prognostic significance of cyclin D1 and Ki-67 in the carcinoma of larynx and hypopharynx to determine the relationship with the various clinicopathological parameters. MATERIALS AND METHODS: Paraffin embedded tissue specimens from 40 cases of squamous cell carcinoma of the larynx and hypopharynx were studied by immunohistochemical method using the Ki-67 and cyclin D1 antibody. K1-67 index and expression of cyclin D1 were compared with the recurrence, survival rate, disease free time and other clinicopathological parameters such as, primary site, pathologic differentiation, tumor stage and lymph node metastasis. RESULTS: The higher Ki-67 index was significantly correlated with poorer pathologic differentiation, and shorter disease free time. But there was no significant correlation between over expression of cyclin D1 and any factor for the head and neck cancer. However, the expression of cyclin D1 had a significant positive relationship with Ki-67 index (p<0.05). CONCLUSION: Ki-67 index is a good prognostic factors and cyclin D1 may be important in tumorigenesis for squamous cell cancer of the larynx and hypopharynx.

Craniofacial Resection with Subfrontal Approach / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: The classic craniofacial resection for anterior skull base tumor uses bifrontal craniotomies together with lateral rhinotomies. This approach requires frontal lobe retraction and may be associated with the development of brain edema and encephalomalacia. The subfrontal approach by use of supraorbital-frontal bone osteotomy permits removal of anterior skull base lesions with minimal retraction of frontal lobe and provides excellent exposure by reducing the depth and obliquity of the approaches and lowering the inferior visual angle. MATERIALS AND METHODS: We reviewed 3 cases of anterior skull base tumor involving the frontal, sphenoid sinus and partially clivus, or frontal lobe. They were 1 female patient and 2 male patients aging from 56 to 64. RESULTS: We obtained sound results, both functionally and cosmetically, except for one who died of brain metastasis. CONCLUSION: The craniofacial resection with subfrontal approach using supraorbital-frontal bone osteotomy provides excellent exposure, particularly in high grade malignancy of the anterior skull base, and can reduce postoperative morbidities.

Anatomical Study of the Artery and the Nerve of the Thyroid Gland / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: An awareness of the surgical anatomy and the possible dispositions of the superior, recurrent laryngeal nerve and the thyroid arteries are very helpful in avoiding injury during thyroidectomy. MATERIALS AND METHODS: The relationship of the superior and recurrent laryngeal nerve to the superior and inferior thyroid artery and the incidence of the thyroid ima artery were studied in 43 adult cadavers. RESULTS: The superior thyroid artery (STA) arose commonly from the external carotid artery (59.3%). And the superior laryngeal nerve (SLN) was closely related to the STA. The inferior thyroid artery (ITA) arose commonly from the thyrocervical artery (81.4%) and eight different types of relationship between the ITA and the recurrent laryngeal nerve (RLN) were found. Among them, the most common type was the RLN which passed in front of the ITA (39.5%). And the incidence of the thyroid ima artery was 9.3%. CONCLUSION: The course and anatomic relationship of laryngeal nerve to the thyroid arteries is not constant, therefore careful identification of these structures should be performed during operation to decrease the surgical complications, such as vocal cord paralysis or hemorrhage.