• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.325-335
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• 2008

The junction between resilient denture liner and the denture base is difficult to finish and polish due to difference of the physical property of the materials. Gaps tend to be formed during finishing and polishing procedures. The purpose of this study was measuring the width of junctional gap between $Molloplast-B^{(R)}$ and denture base material after finishing and polishing procedure, and evaluating the effect of method and direction on gap width. $Molloplast-B^{(R)}$ was processed (according to the manufacturer's instruction) against Lucitone $199^{(R)}$ acrylic resin. 50 specimens were fabricated with a raised center section. All of specimens were examined and photographed with a stereoscopic microscope(x120), and the largest gap along the junction of $Molloplast-B^{(R)}$ and acrylic resin on each specimen was measured. One-way analysis of variance(ANOVA) and independent t-test at 95% confidence level were used to analyze the data and to compare groups. The results of this study were as follows. In comparison with finishing tools, the gap width was the largest in $Molloplast^{(R)}$-Cutter and the smallest in FSQ-cross cut bur. There was statistically significant difference between FSQ-cross cut bur and $Molloplast^{(R)}$-Cutter(p<0.05). There was no significant difference in gap width between the direction of polishing. The mean value of gap width was the smallest in case of no polishing, and the largest in case of polishing with pumice & tin oxide. There was statistically significant difference between pumice and pumice & tin oxide. From the results, it is concluded that the use of $Molloplast^{(R)}$-Cutter in clinic need serious consideration even though it has good cutting ability. Further careful study is needed for finishing and polishing methods for decreasing gap width in junction of two materials.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.125-140
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• 2011

The remnant of temporary cement on the intaglio surface of cast restoration may have a negative effect on the retentive strength of permanent cement. This study was to evaluate the effect of temporary cement cleaning methods on the retentive strength of cementation type implant prostheses. Prefabricated implant abutments - height 5.5mm, diameter 4.5mm, 6 degree axial wall taper with chamfer margins were used. Forty copings-abutment specimens were divided into four groups(each n=10) according to the cleaning methods for temporary cement(Temp-$Bond^{(R)}$) as follows : no temporary cementation(the control group), orange solvent, ultrasonic cleaning, air borne-particle abrasion. After the application of temporary cement and the separation, the cleaning procedure was performed according to the protocol of each group. The specimens were cemented with $Premier^{(R)}$ Implant $Cement^{TM}$. After the permanent cementation, the specimens were subjected to thermocycling and pulled out from the specimens with a universal testing machine at a cross-head speed of 0.5mm/min. After the retentive strength test, all the specimens were cleaned using ultrasonic cleaning, abraded with air borne-particles, and steam-cleaned. Likewise, the specimens were temporarily cemented(Temp-$Bond^{(R)}$ NE), cleaned according to the protocol of each group, cemented with $Premier^{(R)}$ Implant $Cement^{TM}$ and subjected to thermocycling and measurement of their retentive strength. The mean of group with orange solvent were significantly lower than those of other groups(p<0.05). There was no significance between group with ultrasonic cleaning and group with air borne-particle abrasion. Group with ultrasonic cleaning and group with air-particle abrasion were no significance at control group. There was no significance between group cemented with Temp-$Bond^{(R)}$ and group cemented with Temp-$Bond^{(R)}$ NE. Within the limitation of this study, it can be concluded that the temporary cement cleaning method with only orange solvent may have a negative effect on the retentive strength of permanent cement. Ultrasonic cleaning and air borne-particle abrasion methods are recommended for the temporary cement cleaning method on cementation type implant prostheses.

• Restorative Dentistry and Endodontics
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• v.34 no.2
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• pp.87-94
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• 2009

The purpose of this study was to assess the current materials, methods and difficulties according to the year of licence and educational background of Korean dentists in Class II direct composite resin restorations. Total 17 questions were included in the questionnaire. Questions were broadly divided into two parts: first. operator's information. and second. the materials and methods used in Class II posterior composite restoration. The questionnaire was sent to dentists enrolled in Korean Dental Association via e-mail. Total 12,193 e-mails were distributed to dentists. 2,612 e-mails were opened, and 840 mails (32.2%) were received from respondents. The data was statically analyzed by chi-square test using SPSS(v. 12.0.1, SPSS Inc. Chicago, IL, USA). Male dentists among respondents was 79%. 60.3% of the respondents acquired their licences recently (1998-2007), and 77% practiced in private offices. 83.4% have acquired their knowledge through school lectures, conferences and seminars. For the Class II restorations, gold inlays were preferred by 65.7% of respondents, while direct composite resin restorations were used by 12.1 % amalgam users were only 4.4% of respondents. For the restorative technique, 74.4% of respondents didn't use rubber dam as needed. For the matrix. mylar strip (53.4%), metal matrix (33.8%) and Palodent system (6.5%) were used. 99.6% of respondents restored the Class II cavity by incremental layering. Obtaining of the tight interproximal contact was considered as the most difficult procedure (57.2%) followed by field isolation (21 %). Among various bonding systems, 22.6% of respondents preferred SE Bond and 20.2% used Single Bond. Z-250 was used most frequently among a variety of composite resins.

• Journal of Oral Medicine and Pain
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• v.31 no.1
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• pp.59-67
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• 2006

There exist patients complaining speech problem due to dysesthesia or anesthesia following dental surgical procedure accompanied by local anesthesia in clinical setting. However, it is not clear whether sensory problems in orofacial region may have an influence on motor speech abilities. The purpose of this study was to investigate whether transitory sensory impairment of mandibular nerve by local anesthesia may influence on the motor speech abilities and thus to evaluate possibility of distorted motor speech abilities due to dysesthesia of mandibular nerve. The subjects in this study consisted of 7 men and 3 women, whose right inferior alveolar nerve, lingual nerve and long buccal nerve was anesthetized by 1.8 mL lidocaine containing 1:100,000 epinephrine. All the subjects were instructed to self estimate degree of anesthesia on the affected region and speech discomfort with VAS before anesthesia, 30 seconds, 30, 60, 90, 120 and 150 minutes after anesthesia. In order to evaluate speech problems objectively, the words and sentences suggested to be read for testing speech speed, diadochokinetic rate, intonation, tremor and articulation were recorded according to the time and evaluated using a Computerized Speech $Lab^{(R)}$. Articulation was evaluated by a speech language clinician. The results of this study indicated that subjective discomfort of speech and depth of anesthesia was increased with time until 60 minutes after anesthesia and then decreased. Degree of subjective speech discomfort was correlated with depth of anesthesia self estimated by each subject. On the while, there was no significant difference in objective assessment item including speech speed, diadochokinetic rate, intonation and tremor. There was no change in articulation related with anesthesia. Based on the results of this study, it is not thought that sensory impairment of unilateral mandibular nerve deteriorates motor speech abilities in spite of individual's complaint of speech discomfort.

• Journal of Oral Medicine and Pain
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• v.25 no.2
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• pp.173-189
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• 2000

The purpose of this study was to evaluate the effect of specific head positions on the mandibular rotational torque movements in maximum mouth opening, protrusion and lateral excursion. Thirty dental students without any sign or symptom of temporomandibular disorders(TMDs) were included as a control group and 90 patients with TMDs were selected and examined by routine diagnostic procedure for TMDs including radiographs and were classified into 3 subgroups : disc displacement with reduction, disc displacement without reduction, and degenerative joint disease. Mandibular rotational torque movements were observed in four head postures: upright head posture(NHP), upward head posture(UHP), downward head posture(DHP), and forward head posture(FHP). For UHP, the head was inclined 30 degrees upward: for DHP, the head was inclined 30 degrees downward: for FHP, the head was positioned 4cm forward. These positions were adjusted with the use of cervical range-of-motion instrumentation(CROM, Performance Attainment Inc., St. Paul, U.S.A.). Mandibular rotational torque movements were monitored with the Rotate program of BioPAK system (Bioresearch Inc., WI, U.S.A.). The rotational torque movements in frontal and horizontal plane during mandibular border movement were recorded with two parameters: frontal rotational torque angle and horizontal rotational torque angle. The data obtained was analyzed by the SAS/Stat program. The obtained results were as follows : 1. The control group showed significantly larger mandibular rotational angles in UHP than those in DHP and FHP during maximum mouth opening in both frontal and horizontal planes. Disc displacement with reduction group showed significantly larger mandibular rotational angles in DHP and FHP than those in NHP during lateral excursion to the affected and non-affected sides in both frontal and horizontal planes(p<0.05). 2. Disc displacement without reduction group showed significantly larger mandibular rotational angles in FHP than those in any other head postures during maximum mouth opening as well as lateral excursion to the affected and non-affected sides in both frontal and horizontal planes. Degenerative joint disease group showed significantly larger mandibular rotational angles in FHP than those in any other head postures during maximum mouth opening, protrusion and lateral excursion in both frontal and horizontal planes(p<0.05). 3. In NHP, mandibular rotational angle of the control group was significantly larger than that of any other patient subgroups. Mandibular rotational angle of disc displacement with reduction group was significantly larger than that of disc displacement without reduction group during maximum mouth opening in the frontal plane. Mandibular rotational angle of disc displacement without reduction group was significantly larger than that of disc displacement with reduction group or degenerative joint disease group during maximum mouth opening in the horizontal plane(p<0.05). 4. In NHP, mandibular rotational angles of disc displacement without reduction group were significantly larger than those of the control group or disc displacement with reduction group during lateral excursion to the affected side in both frontal and horizontal planes. Mandibular rotational angle of disc displacement without reduction group was significantly smaller than that of the control group during lateral excursion to the non-affected side in frontal plane. Mandibular rotational angle of disc displacement without reduction group was significantly larger than that of disc displacement with reduction group during lateral excursion to the non-affected side in the horizontal plane(p<0.05). 5. In NHP, mandibular rotational angle of the control group was significantly smaller than that of disc displacement with reduction group or disc displacement without reduction group during protrusion in the frontal plane. Mandibular rotational angle of disc displacement without reduction group was significantly larger than that of the disc displacement with reduction group or degenerative joint disease group during protrusion in the horizontal plane. Mandibular rotational angle of the control group was significantly smaller than that of disc displacement without reduction group or degenerative joint disease group during protrusion in the horizontal plane(p<0.05). 6. In NHP, disc displacement without reduction group and degenerative joint disease group showed significantly larger mandibular rotational angles during lateral excursion to the affected side than during lateral excursion to the non-affected side in both frontal and horizontal planes(p<0.05). The findings indicate that changes in head posture can influence mandibular rotational torque movements. The more advanced state is a progressive stage of TMDs, the more influenced by FHP are mandibular rotational torque movements of the patients with TMDs.