• 대한치과보철학회지
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• 제37권5호
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• pp.607-619
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• 1999

Cortical support is an important factor, as the engagement of the fixture in strong compact bone offers an increased load-carrying capacity and initial stability. Because of the poor bone quality in the posterior mandible and other anatomic considerations, it has been suggested that implant fixtures be placed in these locations with apical engagement of the lingual cortical plate for so-called bicortication. The purpose of this investigation was to determine the effect of cortical engagements and in addition polyoxymethylene(POM) intramobile connector(IMC) of IMZ implant on implant load transfer in edentulous posterior segment of mandible, using three-dimensional (3D) finite element analysis models composed of cortical and trabecular bone involving single implant. Variables such as (1) the crestal peri-implant defect, (2) the apical engagement of lingual cortical plate, (3) the occlusal contact position (a vertical load at central fossa or buccal cusp tip), and (4) POM IMC were investigated. Stress patterns were compared and interfacial stresses along the bone-implant interface were monitored specially. Within the scope of this study, the following observations were made. 1) Offset load and angulation of fixture led to increase the local interfacial stresses. 2) Stresses were concentrated toward the cortical bones, but the crestal peri-implant defect increased the interfacial stresses in trabecular bone. 3) For the model with bicortication, it was noticed that the crestal cortical bone provided more resistance to the bending moment and the lingual cortical plate provided more support for the vertical load. But Angulation problem of the fixture from the lingual cortical engagement caused the local interfacial stress concentrations. 4) It was not clear that POM IMC had the effect on stress distribution under the present experimental conditions, especially for the cases of crestal peri-implant defect.

• 대한구순구개열학회지
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• 제4권1호
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• pp.1-11
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• 2001

Disposable blade is widely used for palatal and oral mucosal incision in oral and maxillofadal surgery nowadays, But its design and durability need for improvement, Especially, there are so many hard tissues intraoral area, such as bone and tooth, therefor the sharpness of the surgical blade was easily destroyed, The purpose of this study was to make basic data for developing new design of surgical blade using in oral and maxillofacial area including for the patients who have cleft lip and palate deformities, Some questionnaires about the usefulness of currently used surgical blades were sent to 150 dentists, the 54 of them made a reply, Secondly, The used-once blade and fresh new blade were examined under the scanning electron microscope with the 4000-times magnification, Lastly, the tissue reaction following the surgical incision with a fresh-new and a used blade on rat buccal cheek mucosa and hard palate was evaluated with light microscope with hematoxilin-eosin staining, The time interval from the surgical trauma to taking a sample were 1 day, 3 days, 7 days, and 14 days, At each time schedule, 2 Sprague-Dawley rats were sacrificed, Many dentists were agreed to need for changing the design of the surgical blades and also demand to improve the durability of the blades, They were also eager to adopt the new design of blade if it was available, The blade used in surgical extraction procedure was heavily damaged in its sharpe edge of number 15 blade, The histological differences were not prominent, but the delayed healing was detected in buccal mucosal defects especially in the surgical group with used blade, There are slight different changes in hard palatal defects between a used and a new blade group, In this study, we could find that there are imperative demanding on improvement of surgical blade design and durability for oral and maxillofadal area, The blade currently using in surgical extraction was easily damaged, The animal model of this study was not perfect for the purpose of this study.

• Imaging Science in Dentistry
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• 제52권3호
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• pp.267-273
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• 2022

Purpose: The aim of this study was to assess the influence of kilovoltage- peak (kVp) and the metal artifact reduction (MAR) tool on the detection of buccal and lingual peri-implant dehiscence in the presence of titanium-zirconia (Ti-Zr) and zirconia (Zr) implants in cone-beam computed tomography (CBCT) images. Materials and Methods: Twenty implant sites were created in the posterior region of human mandibles, including control sites (without dehiscence) and experimental sites (with dehiscence). Individually, a Ti-Zr or Zr implant was placed in each implant site. CBCT scans were performed using a Picasso Trio device, with variation in the kVp setting (70 or 90 kVp) and whether the MAR tool was used. Three oral radiologists scored the detection of dehiscence using a 5-point scale. The area under the receiver operating characteristic (ROC) curve, sensitivity, and specificity were calculated and compared by multi-way analysis of variance (α=0.05). Results: The kVp, cortical plate involved (buccal or lingual cortices), and MAR did not influence any diagnostic values (P>0.05). The material of the implant did not influence the ROC curve values(P>0.05). In contrast, the sensitivity and specificity were statistically significantly influenced by the implant material (P<0.05) with Zr implants showing higher sensitivity values and lower specificity values than Ti-Zr implants. Conclusion: The detection of peri-implant dehiscence was not influenced by kVp, use of the MAR tool, or the cortical plate. Greater sensitivity and lower specificity were shown for the detection of peri-implant dehiscence in the presence of a Zr implant.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제28권5호
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• pp.341-347
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• 2002

This study was designed to determine the location of the mandibular canal on lower molar areas. Thirty-three patients were examined with multi-planar reformatted CT scan($Dentascan^{(R)}$). Three kinds of measurements were performed. The first was the distances between the upper border of the mandibular canal and the root apices of the first and second molars, the second was the distance between the cortical plate of the mandible and mandibular canal, and the last was the location of the mandibular canal in the buccolingual plane. The obtained results are as follows 1. The distance between the root apices of lower molars and the superior border of mandibular canal was largest at the mesial root of the first molar, and shortest at the distal root of the second molar(p<0.05). 2. The longest distance between the outer surface of the buccal cortical plate of the mandible and mandibular canal was measured from the distal root of the second molar, and this distance decrease gradually mesially(p<0.05). 3. The distance between the mandibular base and inferior border of mandibular canal was longest at the distal root of the second molar, and shortest at the mesial root of the first molar(p<0.05). 4. The location of mandibular canal was lingually positioned in relation to the axis of teeth and alveolar ridge in molar areas.

• Imaging Science in Dentistry
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• 제31권3호
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• pp.181-184
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• 2001

Thirteen-year-old girl complaining of the swelling and pain on the left midface visited our dental hospital. On the radiographic examination, well-defined radiolucent lesion with hyperostotic border was found in the left maxilla accompanying with the external root resorption of the involved teeth and the displaced second molar. CT showed calcified bodies, thinning of hard palate, inferior orbital wall and lateral wall of nasal fossa, and thinning and perforation of the buccal plate of the maxilla. Enucleation and curettage of the lesion and nasoantrostomy was carried out and histopathologic examination mainly showed a solid tumor tissue composed of odontogenic epithelium and pulp tissues admixed with dentin and enamel formation. And some part of reduced follicular epithelium of tooth germ showed a change mimicking calcifying odontogenic cyst. Taken together, we concluded the lesion is an ameloblastic fibro-odontoma with a change of calcifying odontogenic cyst.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제19권4호
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• pp.383-394
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• 1997

This study was done to examine adherence of oral bacteria to titanium dental implant and to know the effective prophylactic antibiotics using an in vivo model. Three samples each of the implant material were set in an acrylic resin flange and placed in the maxillary buccal sulcus of twenty volunteers. At 6- and 54-hour intervals, each sample was placed on blood agar plate (BAP) and chocolate agar, and then they were incubated and identified. Also antibiotic susceptibility test was performed. The results obtained mere as follows ; 1. The microorganisms were chain-like Gram positive cocci and staphyline Gram positive cocci, Gram positive bacilli in order of frequency were found at 6-hour and 54-hour samples by Gram staining. 2. Streptococci was found predominantly at both 6-hour and 54-hour samples, but number of streptococci was decreased as compared to 6-hour samples. 3. There was no difference in the bacterial species adherent to implant between 6-hour and 54-hour samples. 4. All the microbes were sensitive to AMC (amoxacillin clavulanic acid), chloramphenicol, quinolone and vancomycin in the antibiotic susceptibility test. Above results suggest that streptococcus are mainly adhered to titanium implant after implant was placed in the oral cavity and AMC is the most recommendable antibiotics to prevent the peri-implant inflammation.

• 대한치과교정학회지
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• 제44권4호
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• pp.217-225
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• 2014

Single-tooth implantation has become a common treatment solution for replacement of a root-fractured maxillary incisor in adults, but the long-term esthetic results can be unfavorable due to progressive marginal bone loss, resulting in gingival recession. In this case report, a maxillary central incisor with a root fracture in its apical one-third was orthodontically extruded and extracted in a 21-year-old female. Implant surgery was performed after a 3-month healing period, and the final crown was placed about 12 months after extraction. After 12 years, favorable osseous and gingival architectures were visible with adequate bone height and thickness at the buccal cortical plate, and no gingival recession was seen around the implant-supported crown. Although modern dentistry has been shifting toward simplified, clinical procedures and shorter treatment times, both general dentists and orthodontists should be aware of the possible long-term esthetic advantages of orthodontic extrusion of hopelessly fractured teeth for highly esthetically demanding areas and should educate and motivate patients regarding the choice of this treatment solution, if necessary.

• 대한치과의사협회지
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• 제53권8호
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• pp.545-557
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• 2015

The modified ridge splitting/expansion technique combined with guided bone regeneration (GBR) for implant surgery is used to expand the narrow and atrophied edentulous alveolar ridge. Also, the simultaneous implant placement after ridge splitting/expansion technique can reduce the treatment and healing time. This case report includes three patients with a narrow edentulous alveolar ridge of the 2 to 4mm. All three patients underwent a fracture of thin buccal cortical bone plate, and these defects were corrected by the use of the guided bone regeneration (GBR). After 7 to 18 months, all surgical area was stable, and all implant showed a good healing state on the clinical and radiographic examination. In conclusion, though this surgical method is technique sensitive, the modified ridge splitting/expansion technique combined with GBR for implant surgery is recommended for a horizontal augmentation in the narrow edentulous alveolar ridge.

• 대한두개안면성형외과학회지
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• 제20권3호
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• pp.212-216
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• 2019

Zygomaticomaxillary complex (ZMC) fractures account for a substantial proportion of trauma cases. The most frequent complications of maxillofacial fracture treatment are infections and soft tissue flap dehiscence. Postoperative infections nearly always resolve in response to oral antibiotics and local wound care. However, a significant infection can cause a permanent fistula. A 52-year-old man visited our clinic to treat an oroantral fistula (OAF), which was a late complication of a ZMC fracture. Postoperatively, the oral suture site dehisced, exposing the absorbable plate. However, he did not seek treatment. After 5 years, an OAF formed with a $2.0{\times}2.0cm$ bony defect on the left maxilla. We completely excised the OAF, harvested a piece of corticocancellous bone from the iliac crest, inserted the harvested bone into the defect, and covered the soft tissue defect with a buccal mucosal transposition flap. Although it is necessary to excise OAFs, the failure rate is higher for large OAFs (> 5 mm in diameter) because of the extensive defect in the underlying bone that supports the overlying flap. Inappropriate management of postoperative wounds after a ZMC fracture can lead to disastrous outcomes, as in this case. Therefore, proper postoperative treatment and follow-up are essential.

• Journal of Periodontal and Implant Science
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• 제25권1호
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• pp.67-75
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• 1995

The progress of periodontal disease and the wound healing process after treatment result in alveolar bone bone change. So, detection of it is very important in the diagnosis and the radiograph of periodontal disease. Various effects have been made to assess the subtle alveolar bone change and digital subtraction radiography (DSR) has been reported to be the best method in evaluating it qualitatively and quantitatively. The present study was performed to estimate the detectable alveolar bone change qualitatively with digital subtraction radiography. For the in vitro study, 10 intraoral standard radiographs were taken from porcine dry mandible which a rectangular cortical bone chip of 0.1mm to 1.0mm thickness with 0.1mm increment was attached on the buccal surface. The radiographs without and with bone plates were reviewed at the same time by 10 observers and requested to detect the presence of cortical bone plates. Digital Subtraction radiograph was reviewed subsequently by using the DSR system(digital converter-256 grey-levels,DT 2851,Data Translation Co., U.S.A;IBM 386 ; CCD camera, FOTOVIX, Tamrom Co., Japan). The detectable thickness of cortical bone plate was O.4mm on the intraoral radiograph and 0.2mm on the subtaction images. For the human study, radiographs were taken from patients by using intraoral film holding device and aluminum reference wedge before and 3 month after bone graft and 1 week after osteoplasty. The grey level change was estimated in the subtraction images and calculated to aluminum equivalent thickness. The grey level of the grafted site was higher that that of healthy controls. Average grey levels of change on healthy controls were O.48mm aluminum equivalent. However, the amount of changes in grafted sites were 1.87mm aluminum thickness equivalent and in the site of osteoplasty were -1.49mm aluminum thickness equivalent. In conclusion, digital subtraction radiography was more effective in detecting as subtle change of alveolar bone than intraoral standard radiography. With the aid of quantitative analysis of digital subtraction radiography, alveolar bone resorption of apposition can be estimated during diagnosis and treatment of periodontally diseased patients.