Objectives: The aim of this study was to investigate whether the diameter and direction of the plunger and simulation of the periodontal ligament (PDL) affected the stress distribution in endodontically treated premolars. Methods: A fracture strength test was simulated via finite element analysis. A base model was set up, and the following parameters were modified: plunger diameter (3 mm vs. 6 mm), plunger direction (vertical vs. $135^{\circ}$ angular to the central fossa), and PDL simulation. The analysis was conducted using the CosmosWorks structural analysis program, and the results are presented in terms of von Mises stresses. Results: The smaller plunger increased the stresses at the contact area of the crown, but the plunger diameter had no effect on the stress distribution within the root. An angular plunger direction increased stresses within the root, as well as at the buccal cusp of the crown, compared with the vertical direction. Simulation of the PDL caused higher stress accumulation, especially in the cervical region of the root. Conclusions: The plunger diameter had no effect on the stress distribution in the roots, whereas the plunger direction and PDL simulation did affect the stress distribution. More stringent standards can be established by taking such parameters into account when performing fracture testing in future studies.
Journal of the Korean Association of Oral and Maxillofacial Surgeons
/
v.49
no.5
/
pp.304-307
/
2023
Venous malformation (VM) is a benign lesion of blood vessels caused by an error in vascular morphogenesis during the embryologic phase. This entity mostly affects the head and neck region, including the lips, tongue, buccal mucosa, gingiva, or palate. VM may cause functional and aesthetic impairments. The anatomical structure and shape of the lips provide an important aesthetic accent for an individual. Therefore, management of VM in the lip area without postoperative defects or scarring is challenging. In this brief communication article, we present a conservative approach to lip VM in a nine-year-old boy using a bleomycin injection that had good aesthetic and functional outcomes. Injection of 2 mL of 1/10 of 15 mg bleomycin in a saline dilution into the lip mucosa may present a drug reaction as a white plaque and reddish owl eye lesion that takes up to three weeks to resolve without a scar. It is important to recognize the characteristics and self-limiting nature of postoperative bleomycin complications to avoid unnecessary treatment.
Kim, Chang-Hyeon;Kang, Jae-Suek;Boo, Soo-Bung;Oh, Snag-Ho;An, OK-Ju;Kang, Dong-Wan
Journal of Dental Rehabilitation and Applied Science
/
v.20
no.2
/
pp.71-81
/
2004
The purpose of this study was to compare the distributing pattern of stress on the finite element models of two units implant prosthesis with one angulated placement of two implant fixtures. The two unit implant crowns simulated to mandibular first and second molars were made. The two kinds of finite element models were designed according to angulation of fixture ($4.0mm{\times}11.5mm$) : Model 1($15^{\circ}$ buccally angulated placement of one fixture on second molar area), Model 2($15^{\circ}$ lingually angulated placement of one fixture on second molar area). Axial loads of 200N were applied to the center of central fossa and to distance of 2mm and 4mm apart from the center of central fossa. Von-Mises stresses were recorded and compared in the fixtures, and buccolingual section of implants. The results were as follows: 1. Under axial loading at the central fossa, the stress was distributed along the straight fixture except apical portion, while on buccally or lingually angulated placement, the highest stresses were concentrated in the neck portion on the opposite side of the angulated fixture. 2. With offset distance increasing, the stresses were concentrated greater in buccal neck of lingually angulated fixture than in lingual neck of buccally angulated fixture. From the above results, in designing of the occlusal scheme for implant prosthesis with the angulated fixture, occlusal contacts should be placed to distribute stress axially in maximum intercuspation and to avoid offset force during eccentric movements.
Journal of the Korean Association of Oral and Maxillofacial Surgeons
/
v.41
no.3
/
pp.133-138
/
2015
Objectives: To evaluate the influence of the type of osteotomy in the inferior aspect of the mandible on the mechanical performance. Materials and Methods: The study was performed on 20 polyurethane hemimandibles. A sagittal split ramus osteotomy (SSRO) was designed in 10 hemimandibles (group 1) with a vertical osteotomy in the buccal side (second molar level) and final osteotomy was performed horizontally on the lingual aspect, while the mandible body osteotomy was finalized as a straight osteotomy in the basilar area, perpendicular to the body. For group 2, the same osteotomy technique was used, but an oblique osteotomy was done in the basilar aspect of the mandibular body, forming continuity with the sagittal cut in the basilar area. Using a surgical guide, osteosynthesis was performed with bicortical screws using an inverted L scheme. In both groups vertical compression tests were performed with a linear load of 1 mm/min on the central fossa of the first molar and tests were done with models made from photoelastic resin. Data were analyzed using Student's t-test, establishing a statistical significance when P<0.05. Results: A statistical difference was not observed in the maximum displacements obtained in the two osteotomies (P<0.05). In the extensiometric analysis, statistically significant differences were identified only in the middle screw of the fixation. The photoelastic resin models showed force dissipation towards the inferior aspect of the mandible in both SSRO models. Conclusion: We found that osteotomy of the inferior aspect did not influence the mechanical performance for osteosynthesis with an inverted L system.
The purpose of this paper was to observe the influence of Ga-As semiconductor-low power generating laser on she appearance and actions of tenascin, extracellular matrix, as healing process of intentional wound on the experimental animals is taking place. 35 rabbits were divided into control and experimental group. ; and on each, 3mm-long and 2mm-deep, surgical wounds were created on buccal oral mucosa and thoracodorsal portion of skin. Ga-As laser was applied to the experimental group starting a day of the day the wounds were created , the laser was applied for 5 minutes every other day. Tissue samples were taken after the 2, 4, 7, 10, and 14 days after wound formation. Then tile healing process of experimental and control groups were observed and compared, using light microscope. Afterwards, the samples were immunohistochemical stained and again observed tenascin by quantitative measuring. The following results were obtained : 1. Tenascin was observed prevalently on epithelial cells, border area of dermis, and interstitial matrix between connective tissue layers in both experimental and control groups. 2. In oral mucosa, the experimental group showed significant increase in the appearance of tenascin after 4 days compared to the control group, but after 10 days, it decreased to a point which is even less than the control group. 3. In the skin samples, the pattern of appearance of tenascin was the same in both groups, but there was some difference concerning when the peak period was shown, In the experimental group, the peak period of tenascin expression was the 7 days after wound formation in epithelium and connective tissue. In the control group, the peak period was 10 days after. 4. In both the experimental and control groups, tenascin first appeared in the epithelium near the wound area and submucosa, and then spread on the underlying connective tissue. In conclusion, appearance of tenascin is closely related to regeneration of epithelium and development of granulation tissue : therefore, low power laser, which fastnes appearance of tenascin, is sure to faciltate healing process of oral mucosa.
This study surveyed people with hearing impairments and speech defect living in an area of Gyeonggi-do using a self-administered questionnaire and interviewed them with a deaf interpreter's help during the period from January 21 to February 14, 2009 in order to investigate their oral health management attitude according to their general characteristics. The difference between males and females was statistically significant. The results of this study were as follows. 1. As to the number of times of tooth brushing according to gender, 62.5% of males and 34.2% of females brushed their teeth 2 times, and 25.0% and 35.4% 3 times. 2. As to experiences in scaling according to Academic qualification, those with high academic qualification had scaling more regularly 3. As to tooth brushing methods according to cohabitant, the rolling method was most common regardless of cohabitant. As to the number of times of tooth brushing according to residence type, 41.9% of those living with their parents brushed their teeth 3 times, and 69.2% of those living alone and 47.5% of married ones 2 times. 4. With regard to how to access oral hygiene management education, 81.1% of elementary school graduates used multimedia materials and sign language explanation and captions, 48.6% of middle school graduates used multimedia materials and sign language explanation and 14.3% multimedia materials and captions, 50.0% of high school graduates used multimedia materials and sign language explanation and 17.3% multimedia materials and captions. The parish for the buccal cavity hygiene managements of the hearing impairments speech defect and Development of an educational program are needed.
Park, Jung-Ju;Park, Joon-Bong;Kwon, Young-Hyuk;Herr, Yeek;Chung, Jong-Hyuk
Journal of Periodontal and Implant Science
/
v.35
no.3
/
pp.577-590
/
2005
The purpose of this study was to evaluate the effects of toothpaste containing hydroxyapatite for patients who complained dental hypersensitivity. Before baseline of application of toothpaste with hydroxyapatite, tooth brushing instruction was done respectively and the several indices were measured at baseline, 2, 4, 8 weeks. Clinical indices were estimated, and responses to cold, compressive air, tactile stimulus were evaluated with verbal rating score. Relief effects and visual analogue scale were also evaluated. The results of this study were as follows 1. The occurrence rate of hypersensitivity in upper jaw was higher than that of lower jaws, and molar area showed more hypersensitivity than premolar and incisor area. Buccal site was hypersensitive followed by interproximal and lingual site. 2. Plaque index, gingival index and probing depth reduction were gradually improved after Tooth Brushing Instruction and using toothpaste. 3. Subjects showed most sensitive response to cold stimuli than compressive air and tactile stimuli. 4. The relief effect was increased during using tooth paste and complete relief was increased especially at 8 weeks. 5. Visual analogue scale was increased. In conclusion, it was confirmed that toothpaste containing microcrystalline hydroxyapatite have the relief effect of tooth hypersensitivity. During 8 weeks, stimulus responses were decreased and hypersensitivity relief effect was increased.
Kim, Young-Kyun;Lee, Ji-Young;Kim, Su-Gwan;Lim, Seung-Chul
The Journal of Advanced Prosthodontics
/
v.5
no.2
/
pp.167-171
/
2013
PURPOSE. The purpose of this case series was to evaluate the effect of guided bone regeneration using demineralized allogenic bone matrix with calcium sulfate. MATERIALS AND METHODS. Guided bone regeneration using Demineralized Allogenic Bone Matrix with Calcium Sulfate ($AlloMatrix^{TM}$, Wright. USA) was performed at the time of implant placement from February 2010 to April 2010. At the time of the second surgery, clinical evaluation of bone healing and histologic evaluation were performed. The study included 10 patients, and 23 implants were placed. The extent of bony defects around implants was determined by measuring the horizontal and vertical bone defects using a periodontal probe from the mesial, distal, buccal, and lingual sides and calculating the mean and standard deviation of these measurements. Wedge-shaped tissue samples were obtained from 3 patients and histologic examination was performed. RESULTS. In clinical evaluation, it was observed that horizontal bone defects were completely healed with new bones, and in the vertical bone defect area, 15.1% of the original defect area remained. In 3 patients, histological tests were performed, and 16.7-41.7% new bone formation was confirmed. Bone graft materials slowly underwent resorption over time. CONCLUSION. $AlloMatrix^{TM}$ is an allograft material that can be readily manipulated. It does not require the use of barrier membranes, and good bone regeneration can be achieved with time.
The purpose of this study was to evaluate the effect of some resistance form designs on the bond strength of resin-retained prosthesis. Six sub-groups are designed in natural teeth group and resin teeth group . The framework designs in natural teeth group: 1) no groove preparation 2) groove at the center of distal surface 3) groove at the distobuccal line angle 4) 45 degree lateral load with no groove 5) 45 degree lateral load with center groove 6) splint two teeth with no groove. The framework designs in resin teeth group: 1) no groove preparation 2) groove at the center of distal surface 3) groove at the distobuccal line angle 4) metal covered the 1/2 of distal surface 5) metal covered the 1/2 of mesial surface 6) metal extended over the 114 of buccal surface. Specimens were treated electrolytic etching by Oxy-Etch and cemented with Panavia EX. Failure load was measured by Instron. Another 30 specimens were carried out fatigue tests by MTS 810 fatigue testing machine for 5000 cycles at different load level. The following results were obtained from this study. 1. The failure load was significantly increased by resistance forms. 2. The failure load was not increased by increase of total surface area bonded with teeth. The distal surface area played an important role in failure load. 3. In 45 degree lateral load group, the failure load was decreased significantly than that of in vertical load group. 4. Bond failure modes between static test and fatigue test exhibited no differences.
Journal of Dental Rehabilitation and Applied Science
/
v.39
no.4
/
pp.222-228
/
2023
Attrition is the loss of tooth hard tissue due to contact between teeth, and in severe cases, dentin is exposed, accompanied by selective corrosion and excessive wear of teeth, which is called cupping. If these lesions are left untreated, the size of the lesion gradually increases, breaking the unsupported enamel, resulting in a decrease in aesthetics and chewing function. In this case report, patients with cupping and enamel fracture due to severe attrition were directly restored using a resin with soft properties containing organic fillers. In the follow-up observation six years later, most of the filling of the occlusal surface was eliminated, but the filling on the buccal surfaces remained relatively intact, and it was confirmed that this type of resin was suitable for the area where the occlusal force was relatively weak rather than the area where the occlusal force was greatly applied.
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