• Restorative Dentistry and Endodontics
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• v.39 no.3
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• pp.180-186
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• 2014

Objectives: The purpose of this in vitro study was to evaluate the microleakage and penetration of fissure sealant in permanent molar teeth with fluorosis after pretreatment of the occlusal surface. Materials and Methods: A total of 120 third molars with mild dental fluorosis were randomly divided into 6 groups (n = 20). The tooth surfaces were sealed with an unfilled resin fissure sealant (FS) material. The experimental groups included: 1) phosphoric acid etching (AE) + FS (control); 2) AE + One-Step Plus (OS, Bisco) + FS; 3) bur + AE + FS; 4) bur + AE + OS + FS; 5) Er:YAG laser + AE + FS; and 6) Er:YAG laser + AE + OS + FS. After thermocycling, the teeth were immersed in 0.5% fuchsin and sectioned. Proportions of mircoleakage (PM) and unfilled area (PUA) were measured by digital microscope. Results: Overall, there were significant differences among all groups in the PM (p = 0.00). Group 3 showed the greatest PM, and was significantly different from groups 2 to 6 (p < 0.05). Group 6 showed the lowest PM. Pretreatment with Er:YAG with or without adhesive led to less PM than bur pretreatment. There were no significant differences among groups in PUA. Conclusions: Conventional acid etching provided a similar degree of occlusal seal in teeth with fluorosis compared to those pretreated with a bur or Er:YAG laser. Pretreatment of pits and fissures with Er:YAG in teeth with fluorosis may be an alternative method before fissure sealant application.

• The Journal of the Korean dental association
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• v.58 no.3
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• pp.140-151
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• 2020

Purpose: To evaluate reliability of Q-ray view (Aiobio Inc,. Seoul, Korea) for assessing retention status of pit and fissure sealants. Methods: Pit and fissure sealants of 58 permanent molars from 15 third-grade students were examined. Posterior teeth with ≥1 pit and fissure sealants applied to the occlusal surface for >6 months were examined. The teeth were examined using traditional visual-tactile assessments and combined Q-ray view. Pit and fissure sealants were evaluated by assessing marginal plaque, marginal discoloration, marginal integrity, retention, and presence of caries. Fleiss kappa and Cohen's kappa values were calculated to compare inter- and intrarater agreements between visual-tactile and combined Q-ray view assessments. Results: Regarding interrater agreement in visual-tactile assessments, K values of Cohen's kappa for marginal plaque, marginal discoloration, and presence of caries were 0.22-0.57, 0.36-0.57, and 0.43-0.61, respectively, and agreements ranged from slight to moderate. When combined with Q-ray view, the values were 0.81-0.89, 0.69-0.88, and 0.80-0.90, respectively, and agreements ranged from substantial to nearly perfect level, indicating statistical significance. Marginal plaque (0.81-0.83), marginal discoloration (0.57-0.89), and presence of caries (0.69-0.91) showed higher agreements in combined Q-ray view than in visual-tactile assessments, and kappa values of marginal plaques were significantly higher in combined Q-ray view than in visual-tactile assessments. Conclusion: Evaluating retention status of pit and fissure sealants using Q-ray view showed higher reliability than using visual/tactile assessments for marginal plaque, marginal discoloration, and presence of caries. Therefore, Q-ray view may be used to assess the retention status of pit and fissure sealants.

• Restorative Dentistry and Endodontics
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• v.40 no.4
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• pp.290-298
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• 2015

Objectives: Sodium hypochlorite (NaOCl) is an excellent bactericidal agent, but it is detrimental to stem cell survival, whereas intracanal medicaments such as calcium hydroxide ($Ca[OH]_2$) promote the survival and proliferation of stem cells. This study evaluated the effect of sequential NaOCl and $Ca(OH)_2$ application on the attachment and differentiation of dental pulp stem cells (DPSCs). Materials and Methods: DPSCs were obtained from human third molars. All dentin specimens were treated with 5.25% NaOCl for 30 min. DPSCs were seeded on the dentin specimens and processed with additional 1 mg/mL $Ca(OH)_2$, 17% ethylenediaminetetraacetic acid (EDTA) treatment, file instrumentation, or a combination of these methods. After 7 day of culture, we examined DPSC morphology using scanning electron microscopy and determined the cell survival rate with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. We measured cell adhesion gene expression levels after 4 day of culture and odontogenic differentiation gene expression levels after 4 wk using quantitative real-time polymerase chain reaction. Results: DPSCs did not attach to the dentin in the NaOCl-treated group. The gene expression levels of fibronectin-1 and secreted phosphoprotein-1 gene in both the $Ca(OH)_2$- and the EDTA-treated groups were significantly higher than those in the other groups. All $Ca(OH)_2$-treated groups showed higher expression levels of dentin matrix protein-1 than that of the control. The dentin sialophosphoprotein level was significantly higher in the groups treated with both $Ca(OH)_2$ and EDTA. Conclusions: The application of $Ca(OH)_2$ and additional treatment such as EDTA or instrumentation promoted the attachment and differentiation of DPSCs after NaOCl treatment.

• Journal of Korean Dental Science
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• v.7 no.2
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• pp.94-98
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• 2014

Numerous oral and maxillofacial surgeons have found facial space infections after tooth extraction. Most of these infections can be managed easily, but some of them could be life-threatening. Among the facial infections, temporal space infections are rare. Most temporal space infections could be observed as secondary to maxillary third molar infections, maxillary sinusitis, and maxillary sinus fractures. Note, however, that there are insufficient studies on temporal space abscess due to mandibular second molars, especially with acupuncture. A 74-year-old female came to our hospital with severe trismus and facial swelling on the right temporal, buccal, posterior auricular, and cervical regions. The patient had undergone extraction of tooth #47 secondary to dental caries by a general dentist about a month ago. After the dental procedure, the patient had been treated with acupuncture therapy around the right temporomandibular joint area at the oriental medicine clinic. We performed emergency incision and drainage under general anesthesia and started antibiotic treatment with IV ampicillin/sulbactam 3 g every 24 hours and vancomycin 1 g every 24 hours for 5 days. The patient's symptoms subsided and ultimately disappeared. Temporal space abscess after mandibular molar extraction is quite rare. In this case, the spreading mechanism against gravity is considered to be acupuncture therapy.

• Journal of Periodontal and Implant Science
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• v.30 no.4
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• pp.793-803
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• 2000

Procedures for treatment of molar furcation invasion defects range from open flap debridement, apically repositioned flap surgery, hemisection, tunneling or extraction, to regenerative therapies using bone grafting or guided tissue regenerative therapy, or a combination of both. Several clinical evaluations using regenerative techniques have reported the potential for osseous repair of treated furcation invasions. Regenerative treatment of maxillary molars are more difficult due to the multiple root anatomy and multiple furcation entrances therefore, purpose of this study was to evaluated histologically self-curing glass-ionomer cement and light-curing glass-ionomer cement as a barrier in the treatment of a bi-furcated maxillary premolar. Five adult beagle dogs were used in this experiment. With intrasulcular and crestal incision, mucoperiosteal flap was elevated. Following decortication with 1/2 high speed round bur, degree II furcation defect was made on maxillary third(P3), forth(P4) and fifth(P5) premolar. 2 month later experimental group were self-curing glassionomer cement and light-curing glassionomer cement. After 4, 8 weeks, the animals were sacrificed by vascular perfusion. Tissue block was excised including the tooth and prepared for light microscope with Gomori's trichrome staining. Results were as follows. 1. In all experiment group, there were not epithelial down growth and glass ionomer cement were encapsulated connective tissue. 2. In 4 weeks experiment I group slighly infiltrated inflammatory cells but not disturb the new bone or new cementum formation. 3. In 8 weeks, experiment groups I, II were encapsulated fine connective tissue. 4. Therefore glass-ionomer cement filling to the grade III maxillary furcations with multiple root anatomy and multiple furcation entrances were possible clinical methods and this technique is useful method for Maxillary furcation involvement.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.4
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• pp.472-483
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• 2000

Before impression making in the fixed restorations or other prosthesis, hemostatic solutions are used for hemostasis and moisture control. Hemostatic solutions effectively control bleeding but their major ingredients, acid removes smear layers which are formed in the tooth preparation, exposes the dentinal tubular orifices which are occluded by smear layers, makes dentinal tubular fluid displace more easily to the various external stimulus, and according to the hydrodynamic theory, consequently causes dentin hypersensitivity. To know the effect of hemostatic solutions on dentin permeability, coronal dentin discs, 1mm in thickness, were prepared from extracted third molars free from decay and wear, and a split chamber device was used. Hydraulic conductance values and SEMs, which were measured before and after treatment with $Astringedentr^{(R)},\;Altract^(R)\;and\;Epri-dent^{(R)}$, were compared and ana-lysed. The following conclusions were drawn: 1. Hydraulic conductance values which were measured after the treatment of hemostatic solutions were increased in all groups(p<0.05). 2. %change values of hydraulic conductance were compared but no significant difference was found among the three hemostatic solutions(p<0.05). 3. On SEM observations of all groups, after treatment smear layers were removed and dentinal tubular orifices were partially exposed. On the basis of these conclusions, the reckless use of hemostatic solutions should be restricted, and when in use, various methods should be considered to protect dentin.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.1
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• pp.11-18
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• 2002

Compomer, like resin composite, undergoes shrinkage during setting. But, due to the structure of glass ionomers and their hydrophilic nature, water sorption and subsequent expansion may lead to compensation of the shrinkage. The purpose of this study was to, evaluate the change of mliroleakage after 30day-water-storage of compomer and composite resin. 40 sound third molars were used for the microleakage test. Z-100 resin was used for the control groups(Group I and III), Dyract AP for the experimental groups(Group II and IV). The storage time was 1 day in Group I, II and 30days in Group III, IV. The result from the this study can be summarized as follows; 1. No significant difference could be found in microleakage of occlusal margin between each group(p>0.05). 2. In microleakage of gingival margin, no significant difference could be found between group I and II, and between group I and III (p>0.05). 3. Group IV was showed less microleakage than group II and group III in gingival margin(p<0.05).

• Korean Journal of Cleft Lip And Palate
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• v.4 no.2
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• pp.19-27
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• 2001

This study was performed to determine the prevalence of hypodontia and hyperdontia of permanent teeth among Korean schoolchildren, and to compare differences in the prevalence between Korea, other country, and other ethnic groups. The sample consisted of 346 girls aged 6.9～0.3 yr and 375 boys aged 6.8～0.4 yr on whom a panoramic radiograph was taken at Yeonchun-Gun community in Korea. The prevalence of congenitally missing teeth (third molars excluded) was 6.7% in boys and somewhat higher, 9.5% in girls, and 8.0% for both sexes combined. On the average, number of missing teeth per affected child was 1.9 teeth. The most commonly congenitally missing teeth were the mandibular second premolar (32.7%), followed by the mandibular incisor (28.7%), the maxillary second premolar (16.7%), and the maxillary lateral incisors (10.2%). The prevalence of supernumerary teeth was 2.1 % in boys, 1.4% in girls, and 1.8% for both sexes combined. The most common supernumerary teeth were the mesiodens (76.9%), followed by the supernumerary premolar (23.1 %). The affected male-female ratio was 1.6: 1.0. The prevalence of congenital missing teeth in this study was similar to in studies of Japanese, Danish, American and German. The frequency of hyperdontia was lower in this study than in studies of Chinese children, Japanese and American.

• The Journal of Advanced Prosthodontics
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• v.4 no.4
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• pp.192-196
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• 2012

PURPOSE. The purpose of this study was to evaluate the effect of provisional cement removal by different dentin cleaning protocols (dental explorer, pumice, cleaning bur, Er:YAG laser) on the shear bond strength between ceramic and dentin. MATERIALS AND METHODS. In total, 36 caries-free unrestored human third molars were selected as tooth specimens. Provisional restorations were fabricated and cemented with eugenol-free provisional cement. Then, disc-shaped ceramic specimens were fabricated and randomly assigned to four groups of dentin cleaning protocols (n = 9). Group 1 (control): Provisional cements were mechanically removed with a dental explorer. Group 2: The dentin surfaces were treated with a cleaning brush with pumice Group 3: The dentin surfaces were treated with a cleaning bur. Group 4: The provisional cements were removed by an Er:YAG laser. Self-adhesive luting cement was used to bond ceramic discs to dentin surfaces. Shear bond strength (SBS) was measured using a universal testing machine at a 0.05 mm/min crosshead speed. The data were analyzed using a Kolmogorov Smirnov, One-way ANOVA and Tukey HSD tests to perform multiple comparisons (${\alpha}$=0.05). RESULTS. The dentin cleaning methods did not significantly affect the SBS of ceramic discs to dentin as follows: dental explorer, pumice, cleaning bur, and Er:YAG laser. CONCLUSION. The use of different cleaning protocols did not affect the SBS between dentin and ceramic surfaces.

• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.2
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• pp.405-421
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• 1997

The main purpose of this study was to evaluate the acid resistance and antimicrobial effect of fluoride-laser combined application. Recently extracted third molars were used. $5{\times}3mm$ of the buccal and lingual specimens were exposed and incipient artificial carious lesions were formed by keeping them in the artificial cariogenic solution for 5 days. They were divided into five groups and treated with fluoride and laser according to the predetermined regimen. The acid resistance was compared between groups by chemical quantitative analysis of the calcium and phosphorous released into the test solution after single or combined application of fluoride and laser. The antimicrobial effect of each group was analyzed by counting the number of colony forming units after microbial incubation. The results from the present study can be summarized as follows; 1. Experimental groups showed lower values in calcium and phosphorous contents as well as in $CFU/m{\ell}$(colony forming units) than control group. Combined application groups showed lower values than single application groups. 2. Acid resistance and antimicrobial effect by fluoride and laser treatment were confirmed in this study. 3. Based upon the above-mentioned results of this study, it can be assumed that the use of laser-fluoride combined application may provide the child and adolescent patient population with antimicrobial effect as well as acid resistance. Further studies using various materials and experimental conditions are being encouraged.