• The Journal of Advanced Prosthodontics
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• v.5 no.4
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• pp.374-381
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• 2013

PURPOSE. The purpose of this study was to evaluate the effect of alendronates on bone remodeling around titanium implant in the maxilla of rats. MATERIALS AND METHODS. The maxillary first molars were extracted and customized-titanium implants were placed immediately in thirty male Sprague-Dawley rats. The rats were divided into experimental (bisphosphonate) group and control group. At 4 weeks after implantation, the rats in the bisphosphonate group were subcutaneously injected with alendronate three times a week for 6 weeks where as the rats in control group were injected with saline. The rats were sacrificed at 1, 2, 3, 4, or 6 weeks after starting of injection and maxillary bones were collected subsequently. Alveolar bone remodeling around the implants were evaluated by radiographic and histologic analysis. Microarray analysis and immunohistomorphologic analysis were also performed on one rat, sacrificed at 6 weeks after starting of injection, from each group. Statistical analysis was performed using repeated measures analysis of variance and independent t test at a significance level of 5%. RESULTS. There was no statistically significant difference in the bone area (%) around implant between the bisphosphonate group and the control group. However, the amount of empty lacuna was significantly increased in the bisphosphonate group, especially in the rats sacrificed at 4 weeks after starting of injection compared to that of the corresponding control group. The bisphosphonate group showed the same level of TRAP positive cell count, osteocalcin and angiopoietin 1 as the control group. CONCLUSION. Alendronate may not decrease the amount of osteoclast. However, the significantly increased amount of empty lacuna in the bisphosphonate group may explain the suppression of bone remodeling in the bisphosphonate group.

• Imaging Science in Dentistry
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• v.39 no.1
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• pp.7-11
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• 2009

Purpose: The purpose of this study was to assess the prevalence and radiographic characteristics of the nuchal ligament ossification on lateral cephalometric radiographs in Koreans. Subjects and Method: I review and interpreted the lateral cephalometric radiographs from 4,558 patients (1,857 males and 2,701 females, age range from 2 to 79 years) who visited the Kyungpook National University Dental Hospital from January 1, 2008 to February 3, 2009. I grouped the shapes of nuchal ligament ossification as round, rod-like, and segmented shape. And localized the ossification as the involvement of anterior cervical vertebral body. The data were analyzed by using chi-squared test with two-tailed and at a 5% significance level. Results: Among those who showed the nuchal ligament ossification, he mean age of the 143 males was 51.1 and that of the 97 females was 48.0 years. It as not observed completely below teens, and was observed 1% in twenties, 6.1% in thirties, 18.6% in forties, and 26.3% over fifties. It was significantly prevalent in older age group (P<0.01) and in males than females among the same age group (P<0.05). The shapes of nuchal ligament ossification were as follows in order of frequency: rod-like (49.2%), round (30.4%), and segmented (20.4%). The highest involvement of ossification as found at the level of C5 (67.9%), C4 (29.2%), C6 (22.9%), C3 (3.3%), C7 (2.9%), C2 (0.8%), and C1 (0.4%). Conclusion: The nuchal ligament ossifications on lateral cephalometric radiographs were showed as round, rod-like, or segmented shape. The nuchal ligament ossification is often observed after the age of 40 and is observed more frequently in males than females. The highest shape of nuchal ligament ossification was rod-like shape and the highest involvement of cervical spine was C5.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.1
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• pp.42-47
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• 2014

Decrease of occlusal vertical dimension (OVD) due to loss of teeth structure and destruction of the occlusal plane by severely worn dentition may cause cross bite or temporomandibular joint disorder by following change of facial feature or the loss of anterior guidance. Full mouth rehabilitation via an increase of the OVD can be considered to avoid this problem and proper evaluation of patient's OVD is essential. An 80 year old male visited for overall prosthodontic treatment, cross bite due to continuous wear and following decrease of the OVD were observed. We analyzed the existing occlusal relationship using the diagnostic cast, the radiographic evaluation and clinical test, and then proper increase of OVD was selected. The new OVD on diagnostic wax up was placed by the temporary restoration. After 3 months of observation period, final restoration with fixed partial dentures and implant overdenture were made. Throughout the follow-up period of 8 months, the aesthetic and functional improvement can be obtained.

• Journal of Korean Neurosurgical Society
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• v.63 no.6
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• pp.777-783
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• 2020

Objective : To compare the accuracy and breach rates of freehand (FH) versus navigated (NV) pedicle screws in the thoracic and lumbar spine in patients with metastatic spinal tumors. Methods : A retrospective review of adult patients who underwent pedicle screw fixation in the thoracic or lumbar spine for metastatic spinal tumors between 2012 and 2018 was conducted. Breaches were assessed based on the Gertzbein and Robbins classification and only screws placed >4 mm outside of the pedicle wall (lateral or medial) were considered breached. Results : A total of 62 patients received 547 pedicle screws (average 8 per patient) - 34 patients received 298 pedicle screws in the FH group and 28 patients received 249 screws in the NV group. There were 40/547 breaches, corresponding to a breach and accuracy rate of 7.3% and 92.7%, respectively. The breach rate was 9.7% in the FH group and 4.4% in the NV group (chi-squared test, p=0.017); this corresponded to an accuracy rate of 90.3% and 95.6%, respectively. Only one patient from the overall cohort (in the FH group) required revision surgery due to a medial breach abutting the spinal cord (1.6% of all patients; 2.9% of FH patients); no patient suffered organ, vessel, or neurological injury from screw breaches. Conclusion : Navigated pedicle screw placement in patients with metastatic spinal tumors has a significantly higher radiographic accuracy compared to the FH technique. However, the revision surgery was low and no patient suffered from clinically-relevant breach. Navigation also offers the advantage of real-time localization of spinal tumors and aids in targeting and resection of these lesions.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.40 no.5
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• pp.206-210
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• 2014

Objectives: To identify post-treatment prognostic factors for medication-related osteonecrosis of the jaw (MRONJ). Materials and Methods: We evaluated 54 MRONJ patients who visited the Department of Dentistry, Ajou University Hospital, from May 2007 to March 2014. Twenty-one patients were surgically managed with debridement or sequestrectomy and 33 patients were conservatively managed using antibiotics. Correlations of age, sex, stage, bisphosphonate duration and type, and drug holiday with the prognosis of MRONJ were investigated. Correlations were verified by logistic regression analysis and t-tests with a significance level of 0.05. Results: Clinical outcomes were evaluated on the basis of both clinical and radiographic findings. Twelve out of 21 surgically managed patients showed a favorable prognosis and nine patients relapsed. Thirty-one of the 33 conservatively managed patients showed no specific change in prognosis, and two patients worsened. Statistical analyses of the conservative management group did not reveal any correlation of the above factors with the prognosis of conservative management. Drug holiday was the only prognostic factor in the surgical management group (P=0.031 in logistic regression analysis, P=0.004 in t-test). Conclusion: Drug holiday is a prognostic factor in the surgical management of MRONJ. Because the drug holiday in the patients of the poor prognosis group occurred 1.5 to 4 months prior to surgical management, we recommend a drug holiday more than 4 months before surgery.

• Restorative Dentistry and Endodontics
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• v.24 no.4
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• pp.628-632
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• 1999

Currently electronic apex locators have been widely used to determine working length in endodontic treatment. According to Manufacture's recommendation, it is beneficial to find the working length before instrumenting the canal. However, in crown-down pressureless technique, working length of tooth is established following coronal instrumentation 3mm short of radiographic apex. In narrow canals, mechanically formed constriction might be established by coronal instrumentation in some distance from anatomical constriction. The purpose of this study was to evaluate the accuracy of Root-ZX in the canal with mechanical constriction following considerable coronal enlargement with ProFile .06 series. The 40 root canals in 30 extracted mandibular molars were accessed, and their actual length (AL) established by passing a size 10 file just through the minor apical foramen. The teeth were then embedded in an acrylic container with normal saline. The initial canal length(IL) was measured with Root-ZX by negotiating a size 10 file to the apical constriction. The canal was sequentially enlarged to size 40 with ProFile .06 file 3mm short of actual length. The enlarged final canal lengths (FL) were obtained with a size 15 file. The average values of IL, FL were calculated and compared using Repeated measures Analysis of Variance followed Turkey's Studentized Range test. The results were obtained as follows: 1. The initial canal length was 0.12mm shorter than actual canal length(P>0.05). 2. The differences between initial canal length and final canal length were not significant(P>0.05). 3. As a result of this study, regardless of mechanically formed constriction. Root-ZX differentiated between mechanical and anatomic constriction.

• Imaging Science in Dentistry
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• v.32 no.4
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• pp.201-206
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• 2002

Purpose : To evaluate the radiographic change of operation sites after orthognathic surgery using the digital image processing and fractal analysis. Materials and Methods : A series of panoramic radiographs of thirty-five randomly selected patients who had undergone mandibular orthognathic surgery (bilateral sagittal split ramus osteotomy) without clinical complication for osseous healing, were taken. The panoramic radiographs of each selected patient were taken at pre-operation (stage 0), 1 or 2 days after operation (stage 1), 1 month after operation (stage 2), 6 months after operation (stage 3), and 12 months after operation (stage 4). The radiographs were digitized at 600 dpi, 8 bit, and 256 gray levels. The region of interest, centered on the bony gap area of the operation site, was selected and the fractal dimension was calculated by using the tile-counting method. The mean values and standard deviations of fractal dimension for each stage were calculated and the differences among stage 0, 1, 2, 3, and 4 were evaluated through repeated measures of the ANOVA and paired t-test. Results : The mean values and standard deviations of the fractal dimensions obtained from stage 0, 1, 2, 3, and 4 were 1.658±0.048, 1.580±0.050, 1.607±0.046, 1.624±0.049, and 1.641 ±0.061, respectively. The fractal dimensions from stage 1 to stage 4 were shown to have a tendency to increase (p < 0.05). Conclusion: The tendency of the fractal dimesion to increase relative to healing time may be a useful means of evaluating post-operative bony healing of the osteotomy site.

• Imaging Science in Dentistry
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• v.46 no.2
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• pp.87-92
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• 2016

Purpose: The aim of this study was to assess and compare the diagnostic performance of panoramic and occlusal radiographs in detecting submandibular sialoliths. Materials and Methods: A total of 40 patients (20 cases and 20 controls) were included in this retrospective study. Cases were defined as subjects with a submandibular sialolith confirmed by computed tomography (CT), whereas controls did not have any submandibular calcifications. Three observers with different expertise levels assessed panoramic and occlusal radiographs of all subjects for the presence of sialoliths. Intraobserver and interobserver agreement were assessed using the kappa test. Sensitivity, specificity, accuracy, positive and negative predictive values, and the diagnostic odds ratio of panoramic and occlusal radiographs in screening for submandibular sialoliths were calculated for each observer. Results: The sensitivity and specificity values for occlusal and panoramic radiographs all ranged from 80% to 100%. The lowest values of sensitivity and specificity observed among the observers were 82.6% and 80%, respectively (P=0.001). Intraobserver and interobserver agreement were higher for occlusal radiographs than for panoramic radiographs, although panoramic radiographs demonstrated a higher overall accuracy. Conclusion: Both panoramic and occlusal radiographic techniques displayed satisfactory diagnostic performance and should be considered before using a CT scan to detect submandibular sialoliths.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.339-345
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• 1998

The purpose of this study was to evaluate the in vitro accuracy of Root ZX(Morita Co., Japan) which is the ratio type electronic apex locator. The 86 extracted human palatal roots of maxillary molar with fully formed apices were used. File lengths with the file tip just visible at the foramen were compared to those measured with Root ZX. For length measuring with Root ZX, saline test model with which the apical 1/3 of each root was submerged into normal saline were designed. The root canal lengths were determined with Root ZX and the radiographs were taken with a file in the canal. The distances from file tips of Root ZX lengths to apecies in radiographs also were measured with Profile projector PJ311(Mitutoyo Co., Japan). The results were as follows : 1. The root canal length determined with electronic apex locator was $0.78{\pm}0.53mm$ shorter than the length with visual measurement. 2. The file tip of Root ZX lengths was located at $0.85{\pm}0.49mm$ away from the apex in radiograph. 3. The accuracy of the Root ZX was 79.1% within 0.5mm of visual working length and 96.5% within 1.0mm.

• Restorative Dentistry and Endodontics
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• v.40 no.1
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• pp.58-67
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• 2015

Objectives: This study aimed to compare the accuracy of conventional intraoral (CI) radiography, photostimulable phosphor (PSP) radiography, cone beam computed tomography (CBCT) and multidetector computed tomography (MDCT) for detection of strip and root perforations in endodontically treated teeth. Materials and Methods: Mesial and distal roots of 72 recently extracted molar were endodontically prepared. Perforations were created in 0.2, 0.3, or 0.4 mm diameter around the furcation of 48 roots (strip perforation) and at the external surface of 48 roots (root perforation); 48 roots were not perforated (control group). After root obturation, intraoral radiography, CBCT and MDCT were taken. Discontinuity in the root structure was interpreted as perforation. Two observers examined the images. Data were analyzed using Stata software and Chi-square test. Results: The sensitivity and specificity of CI, PSP, CBCT and MDCT in detection of strip perforations were 81.25% and 93.75%, 85.42% and 91.67%, 97.92% and 85.42%, and 72.92% and 87.50%, respectively. For diagnosis of root perforation, the sensitivity and specificity were 87.50% and 93.75%, 89.58% and 91.67%, 97.92% and 85.42%, and 81.25% and 87.50%, respectively. For detection of strip perforation, the difference between CBCT and all other methods including CI, PSP and MDCT was significant (p < 0.05). For detection of root perforation, only the difference between CBCT and MDCT was significant, and for all the other methods no statistically significant difference was observed. Conclusions: If it is not possible to diagnose the root perforations by periapical radiographs, CBCT is the best radiographic technique while MDCT is not recommended.