• Restorative Dentistry and Endodontics
• /
• v.25 no.2
• /
• pp.289-298
• /
• 2000

Carbamide peroxide is usually used for vital teeth bleaching at home. Complications such as tooth hypersensitivity and/or gingival irritation are frequently reported. Therefore, this study was performed to evaluate any possible histological changes in pulp and periodontal tissue by carbamide peroxide bleaching gel in rats. 10% and 15% carbamide peroxide containing nightguard for upper molar were worn for 4 hours a day. The rats were sacrificed after 1 day, 2 days, 3 days, 4 days and 6 days application of carbamide peroxide respectively. The results were as follows : Mild infiltration of inflammatory changes below the junctional epithelium and hyperplasia of epithelium were observed in both 10% and 15% carbamide peroxide treated groups. In all experimental groups, odontoblasts were changed from columnar to cuboidal shape and/or obliterated and the focal loss of predentin was observed in pulp horn. With increasing time of application, these changes were more remarkable, but limited in pulp horn. Inflammatory reactions, vacuolar changes and hyaline degenerations of the pup tissue were also observed in some cases. These results suggested that carbamide peroxide gel used in home bleaching could cause reversible pulpal irritation.

• International Journal of Oral Biology
• /
• v.34 no.4
• /
• pp.185-190
• /
• 2009

This study examined the effects of red light generated from a light emitting diode (LED) upon proliferation and mitochondrial stress in human gingival fibroblasts (hGFs). Cells were exposed to LED-generated red light at a clinically relevant intensity and distance with a 610-630 nm wavelength for various times (0-48 min). At different exposure times, cells were processed for the analysis of succinate dehydrogenase (SDH) activity, proliferation, mitochondrial membrane potential (MMP) and cytotoxicity. Cell cycle progression was also investigated by flow cytometry after staining with propidium iodide. Red light exposure was found to inhibit SDH activity and DNA synthesis in hGFs in a time-dependent manner. Light exposure also reduced the MMP levels in these cells and this was closely associated with a $G_0/G_1$ arrest. In contrast, exposure of hGFs to red light for 48 min led to a dramatic loss of MMP with an attendant increase in cytotoxicity. These findings demonstrate that LED-generated red light may cause mitochondrial stress and growth inhibition in hGFs during tooth whitening therapy, depending on the length of the exposure.

• The Journal of Korean Academy of Prosthodontics
• /
• v.59 no.2
• /
• pp.210-219
• /
• 2021

Excessive teeth wear can lead to reduced chewing efficiency, occlusal plane collapse, and facial changes. Full mouth rehabilitation with a change in vertical dimension may cause pain in the temporomandibular joint, masticatory muscle and teeth, so an accurate diagnosis and treatment plan is required. In this case, a 69-year-old man had excessive teeth wear with a loss of posterior support. We evaluated the degree of adaptation to the increased vertical dimension with the removable occlusal splint and provisional restoration. We report this case because the treatment result has been functionally and aesthetically satisfactory by providing stable anterior guidance, proper posterior teeth disclusion, and even contact of all teeth in centric occlusion.

• Journal of dental hygiene science
• /
• v.21 no.1
• /
• pp.45-51
• /
• 2021

Background: Periodontal disease, also known as gum disease, is a major dental inflammatory disease with a very high prevalence; it is the main cause of tooth loss. Therefore, diagnostic biomarkers that can monitor gum inflammation are important for oral healthcare. Since the gingival crevicular fluid (GCF) adequately reflects changes in the periodontal environment, they have become a target for the development of effective diagnostic biomarkers for periodontitis. In the present study, the level of the target molecules suggested as diagnostic biomarkers for periodontitis were analyzed in GCF samples collected from healthy individuals and periodontitis patients. In addition, useful targets for the diagnosis of periodontitis were evaluated. Methods: GCF samples were collected from healthy individuals and periodontitis patients using absorbent paper points. SDS-PAGE and Coomassie staining were performed for protein analysis. The protein concentrations of GCF specimens were determined using the Bradford method. The levels of the target molecules appropriate for diagnosing periodontal disease were measured by ELISA, according to the manufacturer's protocol. Results: The protein concentration of GCF collected from periodontitis patients was 3.72 fold higher than that in an equal volume of GCF collected from healthy individuals. ELISA analysis showed that the level of interukin-6 (IL-6), IL-8, metalloproteinases 2 (MMP-2), MMP-9, tumor necrosis factor-alpha (TNF-α), azurocidin, and odontogenic ameloblast-associated protein (ODAM) were higher in the GCF samples from the periodontitis patients than in those from the healthy individuals. However, the level of IL-6 and TNF-α were relatively low (> 5 pg/ml). The prostaglandin E2 (PGE2) levels were not significantly different between the two GCF samples. Conclusion: These results indicate that IL-8, MMP-2, MMP-9, azurocidin, and ODAM are potentially useful diagnostic biomarkers for periodontitis; combining multiple biomarkers will improve the diagnostic accuracy of periodontitis.

• Restorative Dentistry and Endodontics
• /
• v.23 no.1
• /
• pp.487-501
• /
• 1998

In the case of CAD/CAM ceramic inlay restorations, if isthmus width is widened too much, it may cause fracture of remaining tooth structure or loss of bonding at the luting interface because of excessive displacement of buccal or lingual cusps under occlusal loads. So to clarify the criterior of widening isthmus width, this study was designed to test the tensile bond strength and bond failure mode between dentin and ceramic cemented with luting composite resin cements. Cylindrical ceramic blocks(Vita Cerec Mark II, d=4mm) were bonded to buccal dentin of 40 freshly extracted third molars with 4 luting composite resin cements(group1 : Scotchbond Resin Cement/Scotchbond Multi-Purpose, group2 : Duolink Resin Cement/ All-Bond 2, group3: Bistite Resin Cement/Ceramics Primer, and group4:Superbond C&B). Tensile bond test was done under universal testing machine using bonding and measuring alignment blocks(${\phi}ilo$ & Urn, 1992). After immersion of fractured samples into 1 % methylene blue for 24 hours, failure mode was analysed under stereomicroscope and SEM. Results: The tensile bond strength of goup 1, 2 & 4 was $13.97{\pm}2.90$ MPa, $16.49{\pm}3.90$ MPa and $16.l7{\pm}4.32$ MPa, respectively. There was no statistical differences(p>0.05). But, group 3 showed significantly lower bond stregnth($5.98{\pm}1.l7$ MPa, p<0.05). In almost all samples, adhesive fractures between dentin and resin cements were observed. But, in group 1, 2 & 4, as bond strength increased, cohesive fracture within resin cement was observed simultaneously. And, in group 3, as bond strength decreased, cohesive fracture between hybrid layer and composite resin cement was also observed. Cohesive fracture within dentin and porcelain adhesive fracture were not observed. In conclusion, although adhesive cements were used in CAD/CAM -fabricated ceramic inlay restorations, the conservative priciples of cavity preparation must be obligated.

• The Journal of the Korean dental association
• /
• v.56 no.1
• /
• pp.42-48
• /
• 2018

INTRODUCTION The most commonly impacted tooth is the third molar. An impacted third molar can ultimately cause acute pain, infection, tumors, cysts, caries, periodontal disease, and loss of adjacent teeth. Local anesthesia is employed for removing the third molar. This study aimed to evaluate the efficacy and safety of 2% lidocaine with 1:80,000 or 1:200,000 epinephrine for surgical extraction of bilateral impacted mandibular third molars. METHODS Sixty-five healthy participants underwent surgical extraction of bilateral impacted mandibular third molars in two separate visits while under local anesthesia with 2% lidocaine with different epinephrine concentration (1:80,000 or 1:200,000) in a double-blind, randomized, crossover trial. Visual analogue scale pain scores obtained immediately after surgical extraction were primarily evaluated for the two groups receiving different epinephrine concentrations. Visual analogue scale pain scores obtained 2, 4, and 6 h after administering an anesthetic, onset and duration of analgesia, onset of pain, intraoperative bleeding, operator's and participant's overall satisfaction, drug dosage, and hemodynamic parameters were evaluated for the two groups. RESULTS There were no statistically significant differences between the two groups in any measurements except hemodynamic factors (P > .05). Changes in systolic blood pressure and heart rate following anesthetic administration were significantly greater in the group receiving 1:80,000 epinephrine than in that receiving 1:200,000 epinephrine ($P{\leq}01$). CONCLUSION The difference in epinephrine concentration between 1:80,000 and 1:200,000 in 2% lidocaine liquid does not affect the medical efficacy of the anesthetic. Furthermore, 2% lidocaine with 1:200,000 epinephrine has better safety with regard to hemodynamic parameters than 2% lidocaine with 1:80,000 epinephrine. Therefore, we suggest using 2% lidocaine with 1:200,000 epinephrine rather than 2% lidocaine with 1:80,000 epinephrine for surgical extraction of impacted mandibular third molars in hemodynamically unstable patients.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.41
• /
• pp.27.1-27.9
• /
• 2019

Background: Implants are becoming the first choice of rehabilitation for tooth loss. Even though they have a high success rate, failures still occur for many reasons. The objective of this study is to analyze the reasons for recurring failure at the same site and the results of re-implantation. Methods: Thirteen patients (11 males and 2 females, mean age 60 ± 9.9 years) who experienced implant surgery failure at the same site (same tooth extraction area) two or more times in the Department of Oral and Maxillofacial Surgery, Seoul National University Bundang Hospital, between 2004 and 2017 were selected. The medical records on a type, sites, diameter, and length of implants; time and estimated cause of failure; and radiographs were reviewed. Data were collected and analyzed retrospectively, and the current statuses were evaluated. Results: A total of 14 implants experienced failure in the same site more than two times. Twelve implants were placed in the maxilla, while 2 implants were placed in the mandible. The maxillary molar area was the most common site of failure (57.1%), followed by the mandibular molar, anterior maxilla, and premolar areas (14.3% each). The first failure occurred most commonly after prosthetic treatment (35.7%) with an average period of failure of 3.8 months after loading. Ten cases were treated as immediate re-implantation, while the other 4 were delayed reimplantation after an average of 3.9 months. The second failure occurred most commonly after prosthetic treatment (42.9%), with an average of 31 months after loading; during the healing period (42.9%); and during the ongoing prosthetic period (14.3%). In 3 cases (21.4%), the treatment plan was altered to an implant bridge, while the other 11 cases underwent another implant placement procedure (78.6%). Finally, a total of 9 implants (64.3%) survived, with an average functioning period of 60 months. Conclusions: Implants can fail repeatedly at the same site due to overloading, infection, and other unspecified reasons. The age and sex of the patient and the location of implant placement seem to be associated with recurring failure. Type of implant, bone augmentation, and bone materials used are less relevant.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.40 no.2
• /
• pp.106-117
• /
• 2013

Normal eruption of the canine is important for the transition to the permanent dentition. Etiologies, including premature loss or delayed retention of deciduous teeth, neoplasm and abnormality of lateral incisor can cause impaction of the maxillary canine. Untreated canine impaction can result in malocclusion, cyst formation and obstacles in orthodontic treatment. The aim of this study is to evaluate location of the impacted maxillary canine and to identify correlation between location and management of the impaction including complications. Using panoramic radiographs and CBCT scan, images of 89 children diagnosed with impaction of the maxillary canine, location of impacted canines was evaluated. The choice of treatment and complications were investigated to identify correlation. Results show that the most commonly impacted location of the maxillary canine was in the mid-alveolar area, followed by buccal side and palatal side. Orthodontic traction was selected more frequently than the other treatments. As complications, displacement of adjacent tooth was occurred most frequently. Buccally impacted canines showed increased tendency towards displacement. The more buccally the canine was impacted, the less orthodontic traction was chosen as the treatment. The canine impacted mesially to the central incisor showed increased tendency to occur root resorption. Therefore, early diagnosis by periodic examination, appropriate treatment and intervention is required.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.26 no.4
• /
• pp.405-417
• /
• 2010

Previous studies have already shown that mouthguard is effective in protecting jaw bone, teeth and oral tissue against sports trauma. However, other than severe trauma, repetitive force, such as disorders like clenching, cause teeth or oral tissue damage. These kinds of disorders usually present pathologic attrition in the posterior teeth, resorption in alveolar bone, loss of teeth and destruction of occlusion. Wearing a mouthguard is believed to be effective in preventing these disorders. But its effect is not examined thoroughly enough. The purpose of this study is to identify whether mouthguard is effective in reducing strain caused by clenching. Mandibular first molars in the normal occlusal relationship without any history of dental treatment were chosen. Biaxial type strain gauge was placed on the buccal surface of the tooth. Having maximum occlusal force, measured by load cell, as a standard, clenching intensity were divided into three stages; moment of slightly tooth contact, medium bite force (50% of maximum bite force), maximum bite force. Strain occurring in dentition in each stage with and without mouthguard was measured. Changes in strain (on dentition) between each stage and difference in strain, between with or without mouthguard were recorded by PCD-300 analyzer and PCD-30 soft ware. The data was statistically analyzed by Wilcoxon signed rank test. The following results were drawn; Without mouthguard, strain given on dentition increased as the clenching force increased. With mouthguard, strain given on dentition also increased as the clenching force increased. With mouthguard, strain decreased, in all cases of clenching force stages. Data on the moment of slightly tooth contact stage, had no statistical significance. However, with mouthguard, 50-90% of decrease in strain could be obtained in maximum occlusal force, compared to the group without mouthguard. Mouthguard decreased the strain on the dentition, caused by clenching. Therefore, mouthguard seems to be effective in preventing damage on dentition, by acting against clenching, which occurs both consciously and unconsciously during sports activities.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.35 no.4
• /
• pp.260-269
• /
• 2019

The prolonged neglect of the posterior teeth missing area may cause mesial drift, extrusion, unexpected movement of the adjacent teeth and alveolar bone loss with occlusion collapse. Therefore it is recommended to treat that area by the prosthesis as soon as possible after tooth missing. However, if orthodontic treatment is applied to move the remained teeth, it can create improved biomechanical dentoalveolar environment. The use of the third molars in teeth missing area provides advantages as optimizing of prosthesis size. However, crown shape, location, soundness of the third molar and possible of eruption failure should be considered. In this case report, two patients closed a second teeth missing site and reduced the size of the first and second teeth missing area for an implant by protraction of impacted third molars. This case reports the considerations for closing or reducing the posterior teeth space with protracting the third molars by comparing two patients.