• Journal of Oral Medicine and Pain
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• v.33 no.1
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• pp.85-95
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• 2008

The purpose of this study was to evaluate the effects of oral habits on the muscles of mastication and facial expression by means of two parameters: muscle stiffness and elasticity. 10 healthy, fully-dentate male subjects in their twenties were selected for this study; all had normal Class I occlusal relationships. Muscle stiffness and elasticity were measured with a tactile sensor(Venustron, Axiom Co., JAPAN) while subjects were asked to relax and perform various parafunctional activities such unilateral clenching(biting the bite force recorder with a force of 50kg on each subject's preferred side), jaw thrusting and lip bracing. The following muscles were examined: temporalis anterior(Ta), masseter(Mm), frontalis(Fr), inferior orbicularis oculi(OOci), zygomaticus major(Zm), superior and inferior orbularis oris(OOrs and OOri) and mentalis(Mn). Paired t-test, Correlation Coefficients, ANOVA and Multiple Comparison t-tests were used for statistical analysis. Unilateral clenching was highly correlated with bilateral stiffness and elasticity of all the muscles tested. Mm was affected by all three oral habits; Ta was affected by unilateral clenching(p<0.05); Zm was affected by unilateral clenching and OOrs, OOri and Mn were most affected by lip bracing(p<0.05). This study indicates that not only the masticatory muscles but also the muscles of facial expression, mainly circumoral muscles, can be significantly influenced by parafunctional activities such as unilateral clenching and lip bracing.

• Journal of Dental Rehabilitation and Applied Science
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• v.16 no.1
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• pp.51-60
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• 2000

The purpose of this study was to compare the microleakage at the interface of cast post and tooth according to the type of cement. Forty anterior teeth with single root were used. The teeth were cut 2 mm coronal from the cementoeamel junction and chamfer finish line was made on 1 mm coronal from the cementoeamel junction. After the routine endodontic treatment, post space was prepared using #5.5 Parapost drill to a depth of 7 mm. After the pick up impression, core building was made to 3 mm of clinical crown with burnout wax, then post and core was cast with nonprecious metal. The teeth were divided into four groups of ten each. In Group I, post and core were cemented with Fleck's(Zinc phosphate cement) In Group II, post and core were cemented with Fuji I(Glass ionomer cement) In Group III, post and core were cemented with Superbond C & B(Composite resin cement) In Group IV, post and core were cemented with Panavia 21(Composite resin cement) All cemented teeth were stored in normal saline at $37^{\circ}C$ for 7 days and thermocycled from $5^{\circ}C$ to $55^{\circ}C$ for 500 cycles with a dwell time of 30 seconds. After thermocycling, teeth were immersed in 1% Basic fuchsin dye for 48 hours. All 40 teeth were then embedded in the epoxy resin and cut buccolingually with a cutting instrument. The degree of penetration of dye at interface was graded on a scale of 0 to 4 using a stereomicroscope at 25 to 40 times magnification. Through the findings of this study, the following conclusion were obtained. 1. All the groups showed the microleakage at the interface of cast post core and tooth. 2. Group I showed the highest microleakage score among the groups with a significant difference(p<0.05). 3. Group II showed higher microleakage score than Group III and Group IV with a significant difference(p<0.05). 4. Group IV showed the lowest microleakage score but there were no significant difference with Group III(p>0.05).

• Restorative Dentistry and Endodontics
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• v.30 no.5
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• pp.423-430
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• 2005

Ameloblasts are responsible for the formation and maintenance of enamel which is an epithelially derived protective covering for teeth. Ameloblast differentiation is controlled by sequential epithelial-mesenchymal interactions. However, little is known about the differentiation and maturation mechanisms. OD314 was firstly identified from odontoblasts by subtraction between odontoblast/pulp cells and osteoblast/dental papilla cells, even though OD314 protein was also expressed in ameloblast during tooth formation. In this study, to better understand the biological function of OD314 during amelogenesis, we examined expression of the OD314 mRNA and protein in various stages of ameloblast differentiation using in-situ hybridization and immunohistochemistry. The results were as follows : 1. The ameloblast showed 4 main morphological and functional stages referred to as the presecretory, secretory, smooth-ended, and ruffle-ended. 2. OD314 mRNA was expressed in secretory ameloblast and increased according to the maturation of the cells. 3. OD314 protein was not expressed in presecretory ameloblast but expressed in secretory ameloblast and maturative ameloblast. OD314 protein was distributed in entire cytoplasm of secretory ameloblast. However, OD314 was localized at the proxiamal and distal portion of the cytoplasm of smooth-ended and ruffle-ended ameloblast. These results suggest that OD314 may play important roles in the ameloblast differentiation and maturation.

• Restorative Dentistry and Endodontics
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• v.24 no.4
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• pp.570-577
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• 1999

Intuitively, higher bond strengths should result in less leakage. However, the relationship between bond strengths and microleakage value is complex and not clearly understood. The purpose of this study was to evaluate the relationship between tensile bond strengths and microleakage values in the same restorations to understand the behavior of resin bonding to tooth structure. One-hundred and twenty enamel or dentin specimens from freshly extracted bovine mandibular incisors were used. The specimen was treated with 32% phosphoric acid for 15 seconds and rinsed for 20 seconds. the teeth were divided into four groups by means of wet bonding technique or dry bonding. One-Step$^{TM}$ adhesive were applied to the specimen. The specimens were immersed in 2% methylene blue solution for 7 days, and tensile bond strength and microleakage were measured. The results were as follows: 1. Significant negative correlation was found between bond strengths and micro leakage values. Hence, higher bond strengths seem to be associated with lower microleakage, and vice versa (r=-0 50, p<0.05). 2. The Enamel/Wet group showed significantly higher bond strength than Enamel/Dry one, and Dentin/Wet group showed higher strength than Dentin/Dry one (p<0.05). 3. Microleakage was significantly less ill wet bonding than in dry one at dentin (p<0.05), however, there was no significant difference between wet and dry bonding at enamel (p>0.05).

• The korean journal of orthodontics
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• v.27 no.4 s.63
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• pp.549-557
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• 1997

This study was designed to investigate the attrition pattern in Angle Class III malocclusion with facial asymmetry. The sample consisted of three groups, the 20 subjects of normal occlusion group(Group I), the 12 subjects of class III malocclusion without facial asymmetry group(Group II) and 17 subjects of Class III malocclusion with facial asymmetry group(Group III). Attrition areas from canine to second molar on both sides in upper and lower arch, totally twenty, was marked by pencil and mesured by computer system(INTERGRAPH CO. USA) 2 times and the average value was used for date processing. Attrition areas from canine to second molar on both sides in upper and lower arch, totally twenty, was marked by pencil and mesured by computer system(INTERGRAPH CO. USA) 2 times and the average value was used for date Processing. All attrition areas were measured 2 times and the average value was used for data processing The data were statistically analyzed by SAS program. The results of this study were as follows. 1. Total attrition area in Group I was larger than in Group II and III. 2. There was no significant difference in attrition area between right and left side in each group, but attrition area in Group III was larger than in Group I and II. 3. In Group I, Maxillary attrition area was larger than mandibular attrition area, but in Group ll and III, there was no significant difference in attrition area between maxilla and mandible. 4. In Group III, the attrition area of deviated side was target than undeviated side 5. There was no significant difference in attrition area between chewing side and non-chewing side in each group. 6. The total attrition area was unaffected by gender.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.99-107
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• 2009

Statement of problem: Restoring and replacing teeth with fixed prostheses commonly used in dental practice. Because of improper oral hygiene care and inaccurate laboratory procedure, complications of fixed prostheses were found in the mouth of patients. Although many efforts have been continually made to obtain the data of long term prognosis of fixed prostheses, it was difficult to do it. Purpose: The purpose of this study was to evaluate the clinical status of fixed prostheses. Material and methods: In order to assess the clinical status of fixed prostheses, a total of 161 individuals(aged 17-85, 99 women and 62 men with 1596 unit of fixed prostheses, and 1169 abutments) who first visited the Department of Prosthodontics, Pusan National University Hospital, between April to September, in 2007 were examined. Results and conclusion: The results of this study were as follows: 1. Length of service of fixed prostheses was $8.6{\pm}0.6$ years(mean), 10.0 years(median). 2. Location of fixed prostheses was found to have no statistically significant influence on longevity of fixed prostheses(P>.05). But, the success rate was high in posterior region and in mandible where the failure rate was high in combination(P<.05). 3. Longevity of fixed prostheses made of metal was longest(mean: $13.0{\pm}9.3$, median: 14.0), gold, precious ceramic, non-precious ceramic trailing behind(P<.05). 4. Number of units in fixed prostheses was found to have no statistically significant influence on longevity of fixed prostheses(P>.05). But, the success rate was high in Single-unit and the failure rate was high in over 3-unit(P<.05). 5. Condition of opposing dentition was found to have no statistically significant influence on longevity of fixed prostheses(P>.05). But, the success rate was high in natural dentition(P<.05). 6. Defective margin(28.2%), dental caries(23.0%), periodontal disease(19.3%), periapical disease(16.9%) were frequent complications. In 30.1% of the cases, abutment state after removing fixed prostheses was needed to be extracted.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.699-720
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• 1995

This study was conducted to evaluate the effect of benzalkonium chloride solution as a wetting agent instead of water on dentin bonding with NTG-GMA/BPDM system (All-bond 2, Bisco.) and DSDM system (Aelitebond, Bisco.). Benzalkonium chloride solution is a chemical disinfectant widely used in medical and dental clinics for preoperative preparation of skin and mucosa due to its strong effect of cationic surface active detergent. Eighty freshly extracted bovine lower incisor were grinded labially to expose flat dentin surface, and then were acid-etched with 10 % phosphoric acid for 15 second, water-rinsed, and dried for 10 second with air syringe. The specimens were randomly divided into 8 groups of 10 teeth. The specimens of control group were remoistured with water and the specimens of experimental groups were remoistured with 0.1 %, 0.5 %, and 1.0 % benzalkonium chloride solution respectively. And then, the Aelitefil composite resin was bonded to the pretreated surface of the specimens by use of All-bond 2 dentin bonding system or Aelitebond dentin bonding system in equal number of the specimens. The bonded specimens were stored in $37^{\circ}C$ distilled water for 24 hours, then the tensile bond strength was measured, the mode of failure was observed, the fractured dentin surface were examined under scanning electron microscopy, and FT-IR spectroscopy was taken for the purpose of investigating the changes of the dentin surface pretreated with benzal konium chloride solution followed by each primer of the dentin bonding systems. The results were as follows : In the group of bonding with NTG-GMA/BPDM dentin bonding agent(All-bond 2), higher tensile bond strength was only seen in the experimental group remoistured with 0.1 % benzal konium chloride solution than that in water-remoistured control group(p<0.05). In the group of bonding with DSDM dentin bonding agent (Aelitebond), no significant differences were seen between the control and each one of the experimental group(p<0.05). Higher tensile bond strength were seen in NTG-GMAIBPDM dentin bonding agent group than in DSDM dentin bonding agent group regardless of remoistur ization with benzal konium chloride solution. On the examination of failure mode, cohesive and mixed failure were predominantly seen in the group of bonding with NTG-GMAIBPDM dentin bonding agent, while adhesive failure was predominantly seen in the group of bonding with DSDM dentin bonding agent. On SEM examination of fractured surfaces, no differences of findings of primed dentin surface between the groups with and without remoisturization with benzal konium chloride solution. FT-IR spectroscopy taken from the control and the experimental group reve::.led that some higher absorbance derived from the primers binding to dentin surface was seen at the group pretreated with 0.1 % benzal konium chloride solution than at the control group of remoisturizing with water.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.685-698
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• 1995

This study was conducted to the effect of temporary cement on the adhesiveness of dentin bonding agent to dentin surface. One hundred freshly extracted bovine mandibular incisors were grinded to expose flat labial dentin surface. The dentin surfaces were temporarized with either eugenol-containing temporary cement(TemBond and Zinc Oxide Eugenol cement) or non-eugenol temporary cement(Nogenol and TempBond NE) for 7days, and then the temporarization was removed with surgical currette and the exposed dentin surfaces were water-rinsed. Bonding specimens were made by use of All-Bond 2 and Super-Bond C&B dentin bonding agent, and stored in $37^{\circ}C$ distilled water for 24hours. The tensile bond strenth and the cohesive failure rate were measured, and then the pretreated dentin surfaces which the temporary cement had been applied to and removed from and the fractured dentin surfaces after bonding test were examined under scanning electron microscope. The results were as follows : In case of bonding with All-Bond 2, tensile bond strength of each experimental group was lower than that of the control group(p<0.05), but there was no significant difference between the bond strengths of the control group and each experimental group in case of bonding with Super-Bond C&B(p>0.05). No significant difference between tensile bond strength of experimental group, whether temporary cement contains eugenol or not, was seen(p>0.05). In case of bonding with All-Bond 2, the control group showed cohesive-adhesive mixed failure mode and the experimental groups mainly showed adhesive failure mode, but in case of bonding with Super-Bond C&B, almost of the control and the experimental groups mainly showed cohesive failure mode. On SEM examination, all of the dentin specimens pretreated with either 10 % phosphoric acid or 10% citric acid after application of the temporary cements demonstrated remnants of temporary cement attached to dentin surface.