• The korean journal of orthodontics
• /
• v.36 no.2 s.115
• /
• pp.114-124
• /
• 2006

The purpose of this study was to evaluate the tooth color changes of resin bonding sites and their adjacent sites on orthodontic bracket bonding. Sixty extracted sound premolars were used and the tooth color was recorded according to the CIE $L^*a^*b^*$ color system using a spectrophotometer. The tooth colors of the twenty premolars were measured and compared before bracket bonding and after removal. On a further twenty premolars, the tooth color was measured before and after only primer application. In the change of $L^*$ values, according to the bracket bonding and primer application, the lightness was decreased, and in the change of $a^*\;and\;b^*$ values, the color was changed into a more yellowish color The color differences $({\Delta}E^*)$ were calculated from the $L^*a^*b^*$ values and compared with the standard value of clinical detection $({\Delta}E^*=3.7)$. The color differences between before the bracket bonding and after removal noted exceeded the standard value and those of between before and after the primer application were not larger than the standard value. Toothbrushing was performed after application of the primer to evaluate the color changes according to the primer abrasion. As a control, toothbrushing was performed on the last twenty premolars. The color differences noted were larger than the standard value after toothbrushing. Also, to evaluate the color changes of the tooth which is exposed to sun irradiation after bracket removal, additional photoaging was performed and the color was measured for all teeth. The additional color differences after photoaging were smaller than the standard value. The above results suggest that the tooth color changes after fixed orthodontic treatment.

• Restorative Dentistry and Endodontics
• /
• v.33 no.6
• /
• pp.545-552
• /
• 2008

The purpose of this study was to evaluate the influence of sodium ascorbate on microtensile bond strengths of total-etching adhesive system to pulp chamber dentin treated with NaOCl. Pulp chambers of extracted human non-caries permanent molars were treated as follows: group 1, with 0.9% NaCl; group 2, with 5.25% NaOCl; group 3, with 5.25% NaOCl and 10% sodium ascorbate for 1min; group 4, with 5.25% NaOCl and 10% sodium ascorbate for 1 min and 10ml of water; group 5, with 5.25% NaOCl and 10% sodium ascorbate for 5 min; group 6, with 5.25% NaOCl and 10% sodium ascorbate for 5 min and 10ml of water; group 7, with 5.25% NaOCl and 10% sodium ascorbate for 10 min; group 8, with 5.25% NaOCl and 10% sodium ascorbate for 10 min and 10ml of water. Treated specimens were dried, bonded with a total-etching adhesive system (Single bond), restored with a composite resin(Z250) and kept for 24h at 100% humidity to measure the microtensile bond strength. NaOCl-treated group (group 2) demonstrated significantly lower strength than the other groups. No significant difference in microtensile bond strengths was found between NaCl-treated group (group 1) and sodium ascorbatetreated groups (group 3-8). The results of this study indicated that dentin treated with NaOCl reduced the microtensile bond strength of Single bond. Application of 10% sodium ascorbate restored the bond strength of Single bond on NaOCl-treated dentin. Application time of sodium ascorbate did not have a significant effect.

• The korean journal of orthodontics
• /
• v.25 no.5 s.52
• /
• pp.525-541
• /
• 1995

This study was designed to investigate force systems and tooth movements produced by retraction archwire during retraction of four maxillary incisors after the maxillary canine retraction into the maxillary first premolar extraction space using the computer-aided three-dimensional finite element method. A three-dimensional finite element model, consisting of 2248 elements and 3194 nodes, was constructed. The model consisted of maxillary teeth and surrounding periodontal membranes, .022'$\times$.028'-slot brackets, and 5 types of retraction archwires(.019'$\times$.025' stainless steel archwire) modeled using the beam elements. The contact between the wire and the bracket slot was modeled using the gap elements because of the non-linear elastic behaviors of the contact between them. The forces and moments, End displacements produced by retraction archwire were measured at various conditions to investigate the difference according to types of loops, magnitudes of activation force, gable angle, and anterior lingual root torque. The results were expressed quantitative and visual ways in the three-dimensional method. The following conclusions can be drawn from this study.1. When the tear-drop loop archwire was activated, the mesio-distal and lingual translational movements of the teeth helped to close the extraction space, but unwanted movements of the teeth including intrusions and extrusions, and rotational movements in each direction occurred. 2. Activation of T-loop archwire compared with those of other types of retraction archwires produced the least translational movements of the teeth helped to space closure and also the least unwanted movements of the teeth. 3. Increasing amount of activation in the tear-drop archwire led not only to increase of translational movements of the teeth helped to space closure, but also to increase of unwanted movements of the teeth. 4. Addition of gable bend in the tear-drop archwire helped anterior teeth to translational movements in the mesio-distal direction, but increased unwanted movements of the teeth 5. Addition of anterior lingual root torque in the tear-drop archwire helped central and lateral incisor to improve their facio-lingual inclination, but increased unwanted movements of the teeth.

• Journal of dental hygiene science
• /
• v.14 no.2
• /
• pp.248-255
• /
• 2014

The objective of the paper is to analyze the extent to which elementary school students acquired, perceived, and practiced oral health knowledge provided by an elementary school-based oral health clinic (SBOHC). It is respectively investigated by gender and year of school. The paper will be relevant for developing specified oral health programs in elementary SBOHCs. By choosing three elementary schools that operate SBOHC in the school district of Daejeon Metropolitan City from April 11 to April 30, 2013, a self-administered questionnaire was given out to be answered directly by 350 students in the 4th, 5th, and 6th grades and their responses were collected. Of the collected responses, 326 responses were explored by using the SPSS 12.0. Those students' scores of oral health knowledge are found to be statistically meaningful for school year, not for gender. In them are included correct tooth brushing time, dental caries symptoms, gum disease symptoms, and correct tooth brushing method. Change in tooth brushing method after oral health education showed the statistically meaningful difference for gender and school year. In conclusion, every SBOHC should develop a variety of specified educational programs that depend on gender and grade in each elementary school.

• The Journal of Korean Academy of Prosthodontics
• /
• v.48 no.3
• /
• pp.202-208
• /
• 2010

Purpose: This study was aimed to evaluate the effect of rhPMP-2 coated implants on alveolar ridge augmentation in dogs. Materials and methods: Six Beagle dogs were used in this study. Six 8.0 mm long anodized surface titanium implants were placed 5 mm into the mandibular alveolar ridge following 6 month of healing period after extraction. Each animal received three implants coated with rhBMP-2 and three uncoated control implants using the randomized split-mouth design. Radiographic examinations were undertaken immediately at implant placement (baseline), at weeks 4 and 8 after implant placement. The amount of bone augmentation was evaluated by measuring the distance from the uppermost point of the coverscrew to the marginal bone. Implant Stability Quotient (ISQ) values were measured immediately at implant placement and 8 weeks after implant placement. For the statistical analysis, Man-Whitney ranksum test and Wilcoxon signed rank test of SPSS 12.0 software were used (P=.05). Results: The BMP group exhibited radiographic vertical bone augmentation about $0.6{\pm}0.7$ mm at 8 weeks later while controls showed bone loss about $0.4{\pm}0.6$ mm. There was significant difference among the rhBMP-2 group and controls in bone level change (P<.05). The ISQ values were significantly higher in the BMP-2 group than the control group at 8 weeks later (P<.05), while there was no significant difference at surgery. Conclusion: Within the limitation of this study, the rhBMP-2 coated on anodized implant could stimulate vertical alveolar bone augmentation, which may increase implant stability significantly on completely healed alveolar ridge.

• The korean journal of orthodontics
• /
• v.31 no.3 s.86
• /
• pp.311-323
• /
• 2001

One of the various mechanics used to treat unilateral Class II malocclusion is head gear with asymmetric face bow. We made the finite element models of unilateral Class II maxillary dental arch and power arm asymmetric face bow. We designed this experiment to observe stress distribution of periodontal ligament, reaction force, and displacement and to understand force system, so to predict the therapeutic effect. On the basis of computerized tomograph of maxillary dental arch of 25 years old male with normal occlusion without extraction and orthodontic treatment history, we made finite element models of maxillary dental arch and periodontal ligament. Then we modified that model to unilateral maxillary Class II malocclusion model of which maxillary left molar displaced mesially. Also, We made finite element model of asymmetric face bow of which right outer bow shorter than left by 25mm(RMO, Penta-FormTM/Medium size, 0.045 inch iner bow, 0.072 inch outer bow). After that, retraction force of 250g, 300b, 350g were applied to maxillary first molar. We concluded as follow. 1. The Net force that both maxillary first molars were received increased as the retraction force increased. Mesially positioned tooth received more force than normally positioned tooth. But, both tooth were received distal force, so distal movement occured. 2. Both tooth received buccal lateral force. In analysis of force element, as the retraction force were increased, force of X-axis at mesially positioned tooth decreased, and force of X-axis at normally positioned tooth increased. so lateral force component moved to the side received less force from more force. 3. There were rotation, tipping with distal movement in maxillary first molar. As retraction force were increased, rotation and tipping also increased. More tipping and rotation occured at the side received more force, that is, mesially positioned tooth. Though it Is small change, displacement of same pattern occur in normally positioned tooth

• Journal of Dental Rehabilitation and Applied Science
• /
• v.27 no.3
• /
• pp.327-336
• /
• 2011

Reported causes of mandibular nerve injury in relation to neuropathic pain in dentistry include extraction, dental implant surgery, oral and maxillofacial surgery, periodontal treatment, and root-canal therapy. This study analyzed the characteristics of pharmacologic management of neuropathy after root-canal therapy. 32 patients who complain of abnormal sensation or pain after root-canal therapy and were referred to Department of Oral Medicine and the Temporomandibular Joint and Orofacial Pain Clinic at the Dental Hospital of Yonsei University, Seoul, Korea from 2004 to 2011 enrolled in this analysis and improvement of symptom was evaluated after pharmacologic management. Thirty-two patients who had hypoesthesia or dysesthesia at the initial visit were analyzed(9 men, 23 women; mean age: 44 years). The causes of neuropathy were local anesthesia(46.9%), chemical trauma from the sealant in root-canal(25%), endodontic surgery(15.6%), and unknown causes(12.5%). Medications such as steroids, anticonvulsants, antidepressants, and analgesics were took for improvement of symptoms and titrated for a variety of period from 1 week to 11 months. It was found that neuropathy of the inferior alveolar nerve and the lingual nerve was in 25 and 7 patients. The improvement of neurosensory disturbance and no improvement after pharmacotherapy was in 21(66%) and 11(34%) patients respectively. The hypoesthesia and dysesthesia was improved 67% and 65% respectively. These results suggest that symptomatic improvement by pharmacologic management can be possible in patients with neuropathy after root-canal therapy. But improvement of symptoms was influenced by the causes and degree of nerve injury, the periods of pharmacotherapy, and the choice of treatment methods. So, further investigation is needed by quantitative measurement of more variables in more individuals.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.25 no.3
• /
• pp.225-235
• /
• 2009

A common procedure of restoration of endodonticlly treated tooth with fiber-reinforced post is followed by core build-up after post cementation. However, this technique is complex and time-consuming. The aim of this study was to compare fracture strength of premolar, restored with various methods of core fabrications on fiber-reinforced posts and casting metal restoration. Forty five freshly extracted human mandibular premolars were obtained and devided into 5 groups acconding to the type of post and methods of core build-up. In Group A, D.T. $Light-post^{(R)}$ were cemented with $DUO-LINK^{TM}$ and then $LIGHT-CORE^{TM}$ was used for core restoration. In Group B, D.T. $Light-post^{(R)}$ and $DUO-LINK^{TM}$ were used for cementing in the postspace, and $DUO-LINK^{TM}$ was used again for core restoration. In Group C, $Light-post^{(R)}$ bonding and the core build-up were performed simultaneously by using $DUO-LINK^{TM}$. In Group D, $LuxaPost^{(R)}$ was bonded by using $LuxaCore^{(R)}-Dual$. Again, $LuxaCore^{(R)}-Dual$ was used for core restoration. In Group E, $LuxaPost^{(R)}$ bonding and the core build-up were performed simultaneously by using $LuxaCore^{(R)}-Dual$. Axial reduction was formed parallelly as possible and 45 degree bevel was made at buccal occlusal surface. Crowns were fabricated and cemented. Each tooth was embedded in self-curing acrylic resin to the level of 2mm below the CEJ. Specimens were fixed on universal testing machin such that the axis of the tooth was at 45 degree inclination to the horizontal plane, and compressive force was applied at a crosshead speed of 1mm/min until failure occurred. The mean fracture strength was the highest in group A followed by descending order in group B, D, E and C. However, there were no statistically significant differences between groups with regard to the fracture strength. The type of the post or build-up methods of the core does not seem to influence the fracture strength.

• Journal of Oral Medicine and Pain
• /
• v.33 no.1
• /
• pp.15-26
• /
• 2008

Purpose : To investigate the actual conditions of diagnosis and treatment of oral medicine inpatient with systemic disease. Methods : A total of 110 subjects, inpatient due to systemic disease for diagnosis and treatment of oral disease was requested to answer the medical history and dental treatment record. Results : Systemic disease is composed of Non-insulin-dependent diabetes mellitus 26%, Cerebral infarction 25.2%, Intracerebral hemorrhage, Polyarthrosis, Coxarthrosis 4.7%, Nerve root and plexus disorders, Hypertensive heart and renal diseases, Ankylosing spondylitis 2.4%. Chief complain of oral disease is composed of toothache 28.6%, routine check 23%, tooth mobility 8.7%, hypersensitivity 7.1%, periodontal bleeding 6.4%. Oral disease is composed of Gingivitis and periodontal diseases 28.9%, Dental caries 17.1%, Diseases of pulp and periapical tissues 15.1%, Diseases of salivary glands 10.5%, Other diseases of hard tissues of teeth 8.6%, Within Normal Limit 5.3%. Treatment of oral disease is composed of periodontal treatment 17.95%, rejection of treatment 16.67%, medication for halitosis & dry mouth 13.46%, extraction 12.18%, prosthetic treatment 8.97%. Chief complain in oral medicine is composed of oral soft tissue problem 6.4%, craniomandibular disorders 5.6%, halitosis 4%, total 16%. Conclusion : These findings indicate that inpatient due to the systemic disease is significantly correlated to the oral disease. The patients of oral disease interrelationship between inpatient and outpatient of systemic disease should be validated by future research.

• The Journal of Korean Academy of Prosthodontics
• /
• v.47 no.1
• /
• pp.53-60
• /
• 2009

Statement of problem: At present, as the esthetic demands are on the increase, there are many ongoing studies for tooth-colored post and cores. Most of them are about fiber post and prefabricated zirconia post, but few about one-piece milled zirconia post and core using CAD/CAM (computer-aided design/computer-aided manufacturing) technique. Purpose: The objective of this study was to compare microleakage of endodontically treated teeth restored with three different tooth-colored post and cores. Material and methods: Extracted 27 human maxillary incisors were cut at the cementoenamel junction, and the teeth were endodontically treated. Teeth were divided into 3 groups (n=9); restored with fiber post and resin core, prefabricated zirconia post and heat-pressed ceramic core, and CAD/CAM milled zirconia post and core. After the preparation of post space, each post was cemented with dual-polymerized resin cement (Variolink II). Teeth were thermocycled for 1000 cycles between $5-55^{\circ}C$ and dyed in 2% methylene blue at $37^{\circ}C$ for 24 hours. Teeth were sectioned (bucco-lingual), kept the record of microleakage and then image-analyzed using a microscope and computer program. The data were analyzed by one-way ANOVA and Scheffe's multiple range test (${\alpha}=0.05$). Results: All groups showed microleakage and there were no significant differences among the groups (P>.05). Prefabricated zirconia post and heat-pressed ceramic core showed more leakage in dye penetration at the post-tooth margin, but there was little microleakage at the end of the post. Fiber post and resin core group and CAD/CAM milled zirconia post and core group indicated similar microleakage score in each stage. Conclusion: Prefabricated zirconia post and heat-pressed ceramic core group demonstrated better resistance to leakage, and fiber post and resin core group and CAD/CAM milled zirconia post and core group showed the similar patterns. The ANOVA test didn't indicate significant differences in microleakage among test groups. (P>.05)