Publications by authors named "Tae-Geon Kwon"

79 Publications

Maxillofacial surgery beyond the perfect storm of COVID-19.

Authors:
Tae-Geon Kwon

Maxillofac Plast Reconstr Surg 2021 Feb 22;43(1). Epub 2021 Feb 22.

Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940, Republic of Korea.

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http://dx.doi.org/10.1186/s40902-021-00293-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7898025PMC
February 2021

Cancer-Associated Fibroblast Subgroups Showing Differential Promoting Effect on HNSCC Progression.

Cancers (Basel) 2021 Feb 6;13(4). Epub 2021 Feb 6.

Department of Microbiology and Immunology, School of Dentistry, Kyungpook National University, Daegu 700-412, Korea.

: The critical effect of the tumor microenvironment on cancer progression is well recognized. Recent research suggests that the cancer-promoting properties of the tumor stroma may be attributed to fibroblasts. However, the effect of cancer-associated fibroblast (CAF) on the progression of head and neck squamous cell carcinoma (HNSCC) is not well known. : From the immunohistochemical analysis of head and neck squamous cell carcinoma (HNSCC) tissues, we divided CAF into two groups depending on the presence or absence of a well-demarcated boundary between epithelial cancer cells and the surrounding extracellular matrix (ECM). Primary culture of CAF was performed, followed by co-transplantation with HNSCC cells into mice oral mucosa, and the tumorigenesis was compared. The mRNA expression patterns between these two CAF groups were compared using DNA microarray analysis. : CAFs from cancer tissues that showed no demarcation between ECM and epithelial cancer cells (CAF-Promote) tended to stimulate Matrigel invasion of HNSCC cells. Conversely, CAFs from cancer tissues that showed a boundary with epithelial cancer cells (CAF-Delay) caused no remarkable increase in Matrigel invasion. Compared with CAF-P, CAF-D is less effective in promoting FaDu tumorigenicity in the mouse model. In DNA microarray analysis, and showed particularly high expression in the CAF-D group. : These cancer stroma-derived collagen proteins might delay the HNSCC progression. These findings are expected to provide vital information for predicting HNSCC prognosis and developing drug targets in the future.
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http://dx.doi.org/10.3390/cancers13040654DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7915931PMC
February 2021

Comparing factors affecting dental-implant loss between age groups: A retrospective cohort study.

Clin Implant Dent Relat Res 2021 Apr 13;23(2):208-215. Epub 2020 Dec 13.

Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, South Korea.

Background: There is a growing interest in factors leading to implant failure in older people as the population aged 65 years or older continues to expand.

Purpose: We sought to identify differences of results in the implant survival rate and the influence of certain factors on implant failure in the older (≥65 years) and younger (<65 years) patients.

Materials And Methods: Patients who underwent their first dental-implant surgery between July 2008 and June 2018 were included. Data on age, sex, smoking habits, medical conditions, implant location, implant size, and the presence and type of bone graft and membrane were collected and analyzed according to age group. Moreover, cumulative survival rates of implants (by Kaplan-Meier analysis) and hazard ratios (HR) of each factor (using Cox regression analysis with shared frailty) in each group were assessed and results compared between groups.

Results: A total of 628 implants in 308 patients and 1904 implants in 987 patients in the older and younger groups, respectively, were assessed, with failure rates of 3.9% and 3.4%. Per Kaplan-Meier analysis, the 11-year patient-level cumulative survival rate of implant treatment was 95.3% (95% CI: 0.91-0.97) in the older and 93.9% (95% CI: 0.88-0.97) in the younger group. The HR for implant failure of the variables, except diameter of dental implants, were not statistically significant in both groups.

Conclusion: The outcomes of implant treatment were not considerably different between the age groups.
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http://dx.doi.org/10.1111/cid.12967DOI Listing
April 2021

Reliability of digital measurement methods on the marginal fit of fixed prostheses: A systematic review and meta-analysis of in vitro studies.

J Prosthet Dent 2020 Sep 19;124(3):350.e1-350.e11. Epub 2020 Jul 19.

Associate Professor, Department of Prosthodontics, School of Dentistry, Institute for Translational Research in Dentistry, Kyungpook National University, Daegu, Republic of Korea. Electronic address:

Statement Of Problem: Digital methods have been increasingly used to evaluate the fit of prostheses, but the accuracy of digital methodology has not been fully clarified.

Purpose: The purpose of this systematic review and meta-analysis was to assess the reliability of digital measurement methods for evaluating the marginal fit of fixed dental prostheses (FDPs) and to identify the potential factors that can influence the accuracy of the measurement methods.

Material And Methods: The differences between digital and conventional measurement methods were analyzed by searching PubMed, Scopus, Web of Science, and Google Scholar databases for studies reporting the marginal fit of FDPs. The agreement of data collection among the reviewers was confirmed by the Cohen kappa coefficient, and the MINORS scale was used to rate the quality of the included studies. The heterogeneity among the studies was evaluated, and meta-analyses with global and subgroup analyses were performed.

Results: Ten in vitro studies were selected according to the eligibility criteria with substantial interreader concordance (κ=0.88). The standard mean difference of the meta-analysis for marginal discrepancy was 0.12 μm (95% confidence interval: -0.12 to 0.35), indicating that no statistically significant differences were found in the marginal discrepancies observed with digital and conventional methods (P=.343). The subgroup analysis for alloy-based prostheses was not significantly different, nor between the material and measurement methods (P=.060).

Conclusions: Digital methods appear to be reliable as an alternative to conventional methods for evaluating the marginal fit of FDPs. To confirm the results of this study and to identify the influencing factors on the accuracy of digital measurement methods, further controlled laboratory and clinical studies are needed.
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http://dx.doi.org/10.1016/j.prosdent.2020.04.011DOI Listing
September 2020

Eye Globe Rupture Caused by Dental Implant-Related Maxillary Sinusitis.

J Oral Maxillofac Surg 2020 Oct 11;78(10):1748-1753. Epub 2020 May 11.

Associated Professor, Department of Oral & Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea. Electronic address:

Eye globe rupture with consequent enucleation is an extremely rare complication of orbital infection spreading from maxillary sinusitis related to dental implant surgery. We report a case of orbital abscess leading to rupture of the globe of the eye in a 60-year-old woman with acute unilateral maxillary sinusitis after dental implant surgery on the left maxillary alveolar bone. The patient had uncontrolled diabetes. Despite surgical intervention, infection of the maxillary sinuses spread to the ocular area, causing disastrous results. To our knowledge, this entity has not been reported previously.
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http://dx.doi.org/10.1016/j.joms.2020.05.002DOI Listing
October 2020

How Accurate Is 3-Dimensional Computer-Assisted Planning for Segmental Maxillary Surgery?

J Oral Maxillofac Surg 2020 Sep 26;78(9):1597-1608. Epub 2020 Apr 26.

Assistant Professor, Department of Oral and Maxillofacial Surgery, University of Illinois at Chicago College of Dentistry, Chicago, IL. Electronic address:

Purpose: The 3-dimensional (3D) accuracy of computer-assisted planning (CAP) of segmental maxillary osteotomies has seldom been reported with a comprehensive 3D analysis. The aim of the present study was to measure the accuracy of computer-planned segmental maxillary surgery and to identify the factors associated with accuracy.

Materials And Methods: The present retrospective, cross-sectional study investigated cone-beam computed tomography (CBCT) scans of patients who had undergone segmental maxillary osteotomy with CAP at a single center from January 2013 to October 2019. The predictor variables were age, gender, diagnosis, CAP method, type of maxillary segmentalization, surgeon, surgical sequence, and magnitude of planned and actual movements. The primary outcome variable was surgical discrepancy (linear differences between the actual and planned maxillary movements using CAP in the x, y, and z coordinates) at various 3D landmarks. The mean difference and absolute mean difference (AMD) were computed to estimate the direction and magnitude of the discrepancies. In addition, a 2.0-mm threshold of surgical discrepancy was used to determine clinically acceptable accuracy. The association between the predictor and outcome variables were analyzed statistically using correlation and regression analyses.

Results: The sample included 63 patients (mean age, 20.1 years; 42.9% male). The surgical discrepancy was similar for 2- and 3-piece segmental maxillary osteotomies. Overall, the AMD for all patients was 0.96 ± 0.69 mm transversely, 1.23 ± 0.83 mm vertically, and 1.16 ± 0.80 mm anteroposteriorly (P < .01 for all). The discrepancy between the actual and planned movements was within 2.0 mm for more than 80% of cases. The major predictor variable that affected surgical discrepancy was the magnitude of the actual surgical movements (P < .01).

Conclusions: 3D CAP showed clinically acceptable accuracy for segmental maxillary osteotomies comparable to that of nonsegmental cases. Although the magnitude of actual surgical movements was shown to affect surgical accuracy, the sources of surgical discrepancies requires further investigation.
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http://dx.doi.org/10.1016/j.joms.2020.04.030DOI Listing
September 2020

Three-Dimensional Analysis of Lip Asymmetry and Occlusal Cant Change After Two-Jaw Surgery.

J Oral Maxillofac Surg 2020 Aug 18;78(8):1356-1365. Epub 2020 Apr 18.

Assistant Professor, Department of Oral and Maxillofacial Surgery, University of Illinois at Chicago, College of Dentistry, Chicago, IL. Electronic address:

Purpose: Lip asymmetry greatly influences patient satisfaction after 2-jaw surgery. The purpose of the present study was to identify the influence of skeletal changes on lip cant correction in 2-jaw surgery for mandibular prognathism with asymmetry.

Material And Methods: The present retrospective cohort study included consecutive skeletal Class III patients who had undergone Le Fort I and sagittal split ramus osteotomy with preoperative and 6-month postoperative cone-beam tomography scans available. The primary predictor variables were the postoperative hard tissue changes (canine cant, first molar cant, transverse change at menton [Me] after surgery, and changes postoperatively from preoperatively). The primary outcome variable was the change in the soft tissue lip cant. The secondary outcome variables were the changes in various landmarks representing perioral asymmetry, including center of cupid's bow, lower lip vermilion, and subnasale. Other variables included subject age and gender. Descriptive statistics and regression and correlation analyses were used to investigate the important predictors influencing lip cant change.

Results: A total of 58 patients (33 males; average age, 21.7 years) were included in the present study. The demographic variables of the asymmetry group (Me deviation >4 mm) were not different from those of the control group. Postoperative changes in Me deviation correlated significantly with the changes in the transverse position of the subnasale, upper lip, and horizontal and vertical differences in the mouth corner position (P < .01 for all) but not with the maxillary occlusal cant change. Linear regression analysis showed lip cant correction was associated with changes in Me deviation (P < .001) and molar cant change (P = .032), but not with canine cant change.

Conclusions: Maxillary occlusal cant correction itself cannot fully account for changes in lip cant. The transverse Me change-rather than maxillary cant correction-had the greatest influence on lip cant. These results suggest that correction of chin deviation must be addressed in lip cant correction for facial asymmetry.
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http://dx.doi.org/10.1016/j.joms.2020.04.011DOI Listing
August 2020

Why most patients do not exhibit obstructive sleep apnea after mandibular setback surgery?

Maxillofac Plast Reconstr Surg 2020 Dec 17;42(1). Epub 2020 Mar 17.

Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940 Republic of Korea.

Maxillomandibular advancement (MMA) is effective for the treatment of obstructive sleep apnea (OSA). In previous studies, the airway was increased in the anteroposterior and transverse dimensions after MMA. However, the effect of the opposite of mandibular movement (mandibular setback) on the airway is still controversial. Mandibular setback surgery has been suggested to be one of the risk factors in the development of sleep apnea. Previous studies have found that mandibular setback surgery could reduce the total airway volume and posterior airway space significantly in both the one-jaw and two-jaw surgery groups. However, a direct cause-and-effect relationship between the mandibular setback and development of sleep apnea has not been clearly established. Moreover, there are only a few reported cases of postoperative OSA development after mandibular setback surgery. These findings may be attributed to a fundamental difference in demographic variables such as age, sex, and body mass index (BMI) between patients with mandibular prognathism and patients with OSA. Another possibility is that the site of obstruction or pattern of obstruction may be different between the awake and sleep status in patients with OSA and mandibular prognathism. In a case-controlled study, information including the BMI and other presurgical conditions potentially related to OSA should be considered when evaluating the airway. In conclusion, the preoperative evaluation and management of co-morbid conditions would be essential for the prevention of OSA after mandibular setback surgery despite its low incidence.
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http://dx.doi.org/10.1186/s40902-020-00250-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7078420PMC
December 2020

Concomitant injuries and complications according to categories of pan-facial fracture: a retrospective study.

J Craniomaxillofac Surg 2020 Apr 29;48(4):427-434. Epub 2020 Feb 29.

Dept. of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940, Republic of Korea. Electronic address:

Purpose: The purpose of this study was to investigate concomitant injuries and complications in patients with panfacial fracture (PF) according to patterns of PF.

Materials And Methods: PF is defined as fractures involving at least three of the four facial parts (frontal, upper midface, lower midface, and mandible). The data for this study were retrospectively analysed. A simple regression analysis, Cramer's V analysis, and Pearson's correlation analysis were used for verifying significance and correlation between the investigated factors and patterns of PF. Short-term postoperative surgical complications were classified according to the Clavien-Dindo classification (CDC).

Results: There was a statistically significant association between age and PF pattern (ULM: 44.9 ± 19.2; FUL: 42.0 ± 16.8; FULM: 33.6 ± 15.3; FUM: 65; p = 0.024), between the cause of injury and PF pattern (p = 0.047), and between operative time and fracture pattern (ULM: 4h 45min ± 2h 21min; FUL: 5h 19min ± 2h 54min; FULM: 7h 19min ± 4h 13min; FUM: 2h 15min ± 0; p = 0.008). 89% of patients had concomitant injuries in other body parts. In the CDC grade groups, rade IVa cases (n = 4) showed statistically significant differences with PF patterns (p = 0.006). Of all the patients, 58.6% (n = 58) complained of postoperative complications.

Conclusion: PF patients can have different fracture patterns, depending on age and cause of trauma. Consequently, different PF patterns have different types of concomitant injuries and complications. PF patients with frontal area fracture have higher CDC grades, and may need ICU care. Therefore, classifying PFs will be a first step towards a systemic approach for treating and reducing complications.
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http://dx.doi.org/10.1016/j.jcms.2020.02.018DOI Listing
April 2020

Median Lingual Foramen, a new midmandibular cephalometric landmark.

Orthod Craniofac Res 2020 Aug 10;23(3):357-361. Epub 2020 Mar 10.

Department of Oral and Maxillofacial Surgery, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.

Purpose: In asymmetrical mandibles, it is often challenging to identify the mandibular midline. The median lingual foramen (MLF) is located at the midline of the anterior mandible. The purpose of this study is to evaluate the reproducibility of identifying the MLF compared to conventional landmarks on cone beam computed tomography's (CBCT's) to mark the mandibular midline.

Material And Methods: Ten symmetrical class II, 10 symmetrical class III, ten asymmetrical class II and 10 asymmetrical class III patients were included. On CBCTs, the cephalometric landmarks menton, pogonion, genial tubercle and MLF were identified twice by two observers.

Results: A high intra- and interobserver reproducibility was found for all landmarks, the highest being the MLF. The gain in accuracy is 0.998 mm, 0.824 mm and 0.361 mm compared to pogonion, genial tubercle and menton, respectively (P-value <.05).

Conclusion: MLF is a reliable and reproducible landmark to indicate the midline of the mandible, particularly in Class II asymmetric mandibles.
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http://dx.doi.org/10.1111/ocr.12372DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7496480PMC
August 2020

Potential Salivary mRNA Biomarkers for Early Detection of Oral Cancer.

J Clin Med 2020 Jan 16;9(1). Epub 2020 Jan 16.

Department of Microbiology and Immunology, School of Dentistry, Kyungpook National University, Daegu 700-412, Korea.

We evaluated potential biomarkers in human whole saliva for the early diagnosis of oral squamous cell carcinoma (OSCC). We selected 30 candidate genes with relevance to cancer from recent reports in PubMed. Saliva samples were obtained from 34 non-tumor control and 33 OSCC patients. Real-time PCR was performed, and mRNA levels were compared. Normalized mRNA levels of six genes (NGFI-A binding protein 2 (NAB2), cytochrome P450, family 27, subfamily A, polypeptide 1 (CYP27A1), nuclear pore complex interacting protein family, member B4 (NPIPB4), monoamine oxidase B (MAOB), sialic acid acetyltransferase (SIAE), and collagen, type III, alpha 1 (COL3A1)) were significantly lower in saliva of OSCC patients. Receiver operating characteristics (ROC) analysis was used to individually evaluate the predictive power of the potential biomarkers for OSCC diagnosis. The area under the curve (AUC) values were evaluated for the OSCC vs. non-tumor groups via univariate ROC analyses, as well as multivariate ROC analyses of combinations of multiple potential biomarkers. The combination of CYP27A1 + SIAE showed a favorable AUC value of 0.84. When we divided saliva samples into two groups according to age using a 60-year cut-off, with OSCC patients and controls evaluated together, the AUC of MAOB-NAB2 was more predictive of OSCC in the under-60 group (AUC, 0.91; sensitivity, 0.92; and specificity, 0.86) than any other gene combination. These results are expected to aid the early diagnosis of OSCC, especially in patients under 60 years of age. While more studies with larger numbers of patients are necessary, our result suggest that salivary mRNA would be a potent biomarker for early OSCC diagnosis.
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http://dx.doi.org/10.3390/jcm9010243DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7019677PMC
January 2020

Current status of surgery first approach (part II): precautions and complications.

Maxillofac Plast Reconstr Surg 2019 Dec 3;41(1):23. Epub 2019 Jun 3.

2Department of Oral and Maxillofacial Surgery, College of Dentistry, University of Illinois at Chicago , Chicago, IL 60612-7211 USA.

The choice of surgical technique in orthognathic surgery is based primarily on the surgical treatment objectives (STO), which is a fundamental component of the orthognathic treatment process. In the conventional orthodontics-first approach, presurgical planning can be performed twice, during the preorthodontic (initial STO) and presurgical phases (final STO). Recently, a surgery-first orthognathic approach (SFA) without presurgical orthodontic treatment has been introduced and combined initial and final STO at the same time. In contrast to the conventional surgical-orthodontic treatment protocol that includes preoperative orthodontics for dental decompensations to maximize stable postoperative occlusion, the SFA potentially shortens the treatment period and minimizes esthetic concerns during the decompensation period because skeletal problems are corrected from the beginning. The indications for the SFA have been proposed in the literature, but no consensus exists. Moreover, because dental occlusion of the pre-orthodontic arches cannot be used as a guide for establishing the surgical treatment plan, there are fundamental limitations in accurate prediction of postsurgical results in the SFA. Recently, the concepts of postsurgical orthodontic treatment are continuously changing and evolving to overcome this inherent limitation of the SFA. The elimination of presurgical orthodontics can change the paradigm of orthognathic surgery but still requires cautious case selection and thorough discussion and collaboration between orthodontists and surgeons regarding the goals and postoperative management of the orthognathic procedure.
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http://dx.doi.org/10.1186/s40902-019-0206-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6546776PMC
December 2019

NAB 2-Expressing Cancer-Associated Fibroblast Promotes HNSCC Progression.

Cancers (Basel) 2019 Mar 19;11(3). Epub 2019 Mar 19.

Department of Microbiology and Immunology, School of Dentistry, Kyungpook National University, Daegu 700-412, Korea.

Cancer-associated fibroblast (CAF)-specific proteins serve as both prognostic biomarkers and targets for anticancer drugs. In this study, we investigated the role of NGFI-A-binding protein (NAB)2 derived from CAFs in the progression of head and neck squamous cell carcinoma (HNSCC). Patient-derived HNSCC and paired metastatic lymph node tissues were examined for NAB2 expression by immunohistochemistry. Primary CAF cultures were established from HNSCC patient tissue, with paired non-tumor fibroblasts (NTFs) serving as a control. CAF or NTF was used to evaluate the effect of NAB2 on HNSCC progression using FaDu cell spheroids and an in vivo mouse xenograft model. NAB2 was detected in interstitial CAFs in primary and metastatic lymph node tissues of HNSCC patients. NAB2 mRNA and protein levels were higher in CAFs as compared to paired NTFs. Conditioned medium (CM) of NAB2-overexpressing CAFs increased the invasion of FaDu spheroids in the Matrigel invasion assay as compared to CM of NTF. Co-injection of NAB2-overexpressing CAFs with FaDu spheroids into mice enhanced the growth of tumors. These data suggest that NAB2-overexpressing CAFs promotes HNSCC progression and is a potential therapeutic target for preventing HNSCC metastasis.
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http://dx.doi.org/10.3390/cancers11030388DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6468532PMC
March 2019

Oral tuberculosis mimicking a traumatic denture ulcer.

J Prosthet Dent 2019 Feb 26;121(2):225-228. Epub 2018 Oct 26.

Associate Professor, Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea. Electronic address:

Tuberculosis (TB) of the oral cavity may be overlooked in the differential diagnosis of oral lesions and can be misdiagnosed and managed incorrectly. A 66-year-old man with complete dentures presented with a nonhealing mucosal ulcer in the upper lip. Despite the treatments performed by a local medical clinic, the ulcerative lesion on the denture-bearing area had not improved over 5 months. A partial excisional biopsy was performed to investigate further. Histopathologic examination revealed granulomatous inflammation caused by TB, and a chest radiograph showed consolidation and cavitation of the upper lobes. The patient was diagnosed with pulmonary TB. This clinical report describes the management of oral TB mimicking a traumatic denture ulcer in a patient with long-term complete denture use.
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http://dx.doi.org/10.1016/j.prosdent.2018.04.024DOI Listing
February 2019

Life-threating outcomes after dental implantation in patient with idiopathic thrombocytopenic purpura: a case report and review of literature.

Maxillofac Plast Reconstr Surg 2018 Dec 10;40(1):39. Epub 2018 Dec 10.

Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940 Republic of Korea.

Background: Patients with chronic ITP (idiopathic thrombocytopenia) frequently do not require comprehensive medication for daily life. Usually, it had been regarded that postoperative bleeding after a simple or surgical extraction is easily controlled by simple local measures even in patients with ITP. This lack of regular medication usage can sometimes lead practitioners or patients to underestimate the potential life-threatening risk of ITP. There had been no report on postoperative hemorrhage in a patient with ITP related to dental implant surgery.

Case Presentation: This report presented a life-threatening postoperative hemorrhage after dental implant surgery in an adult with chronic ITP and subsequent emergency management after severe bleeding and airway compromise.

Conclusion: The presented case emphasizes the thorough hematological evaluation of the patients even for patients who do not take any specific medications for asymptomatic, chronic ITP.
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http://dx.doi.org/10.1186/s40902-018-0178-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6286906PMC
December 2018

Orthognathic surgery for patients with fibrous dysplasia involved with dentition.

Maxillofac Plast Reconstr Surg 2018 Dec 3;40(1):37. Epub 2018 Dec 3.

1Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940 Republic of Korea.

Background: Fibrous dysplasia (FD) is characterized by the replacement of normal bone by abnormal fibro-osseous connective tissue and typically treated with surgical contouring of the dysplastic bone. When dysplastic lesions involve occlusion, not only is surgical debulking needed, orthognathic surgery for correction of dentofacial deformity is mandatory. However, the long-term stability of osteotomized, dysplastic bone segments is a major concern because of insufficient screw-to-bone engagement during surgery and the risk of FD lesion re-growth.

Case Presentation: This case report reviewed two patients with non-syndromic FD that presented with maxillary occlusal canting and facial asymmetry. Le Fort I osteotomy with recontouring of the dysplastic zygomaticomaxillary region had been performed. The stability of osseous segments were favorable. However, dysplastic, newly formed bone covered the previous plate fixation site and mild bony expansion was observed, which did not influence the facial profile. Including the current cases, 15 cases of orthognathic surgery for FD with dentition have been reported in the literature.

Conclusion: The results showed that osteotomy did not appear to significantly reduce the long-term stability of the initial fixation insufficiency of the screw to the dysplastic bone. However, based on our results and those of the others, long-term follow-up and monitoring are needed, even in cases where the osteotomized segment shows stable results.
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http://dx.doi.org/10.1186/s40902-018-0176-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6275155PMC
December 2018

Development of an experimental model for radiation-induced inhibition of cranial bone regeneration.

Maxillofac Plast Reconstr Surg 2018 Dec 22;40(1):34. Epub 2018 Nov 22.

1Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940 Republic of Korea.

Background: Radiation therapy is widely employed in the treatment of head and neck cancer. Adverse effects of therapeutic irradiation include delayed bone healing after dental extraction or impaired bone regeneration at the irradiated bony defect. Development of a reliable experimental model may be beneficial to study tissue regeneration in the irradiated field. The current study aimed to develop a relevant animal model of post-radiation cranial bone defect.

Methods: A lead shielding block was designed for selective external irradiation of the mouse calvaria. Critical-size calvarial defect was created 2 weeks after the irradiation. The defect was filled with a collagen scaffold, with or without incorporation of bone morphogenetic protein 2 (BMP-2) (1 μg/ml). The non-irradiated mice treated with or without BMP-2-included scaffold served as control. Four weeks after the surgery, the specimens were harvested and the degree of bone formation was evaluated by histological and radiographical examinations.

Results: BMP-2-treated scaffold yielded significant bone regeneration in the mice calvarial defects. However, a single fraction of external irradiation was observed to eliminate the bone regeneration capacity of the BMP-2-incorporated scaffold without influencing the survival of the animals.

Conclusion: The current study established an efficient model for post-radiation cranial bone regeneration and can be applied for evaluating the robust bone formation system using various chemokines or agents in unfavorable, demanding radiation-related bone defect models.
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http://dx.doi.org/10.1186/s40902-018-0173-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6249347PMC
December 2018

Regulating Osteogenic Differentiation by Suppression of Exosomal MicroRNAs.

Tissue Eng Part A 2019 08;25(15-16):1146-1154

1Department of Microbiology and Immunology, School of Dentistry, Kyungpook National University, Daegu, Korea.

Impact Statement: We investigated the role of exosomes in osteogenesis and the use of miRNA inhibitor-transfected exosomes to control osteogenic differentiation. RNA-sequencing (RNA-seq) of exosomal miRNAs revealed that growth condition of milieu of preosteoblast exosomes harbors high levels of let-7, which plays a critical role in osteogenesis regulation. We modified exosomes by transfecting let-7 inhibitor into exosomes under growth condition in MC3T3-E1 cells and revealed that exosomes whose let-7 was inactivated by engineering lost the ability to recover osteogenic differentiation. Genetically modified exosomes may serve as powerful biomaterials for developmental control, including of osteogenesis regulation.
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http://dx.doi.org/10.1089/ten.TEA.2018.0257DOI Listing
August 2019

A novel Bruton's tyrosine kinase inhibitor, acalabrutinib, suppresses osteoclast differentiation and Porphyromonas gingivalis lipopolysaccharide-induced alveolar bone resorption.

J Periodontol 2019 05 20;90(5):546-554. Epub 2018 Nov 20.

Department of Biochemistry, School of Dentistry, Kyungpook National University, Daegu, Korea.

Background: Periodontitis is not only one of the most prevalent inflammatory diseases among adults, but also commonly linked to numerous systemic conditions including cardiovascular diseases, stroke, and diabetes. Although osteoclasts are responsible for the alveolar bone resorption during periodontitis pathogenesis, the development of pharmacologic strategies targeting these cells has not been vastly fruitful.

Methods: Bone marrow macrophages were cultured in the presence of macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor κB ligand (RANKL) to examine the direct effect of acalabrutinib on osteoclastogenesis. Ca oscillation and nuclear localization of NFATc1 in osteoclast precursors were examined to determine the precise molecular mechanism. LPS-induced alveolar bone loss model was employed for studying effect in in vivo bone resorption.

Results: Acalabrutinib directly inhibited RANKL and LPS-induced in vitro osteoclast differentiation. In addition, acalabrutinib inhibited RANKL-induced phosphorylation of mitogen-activated protein kinases and reduced the expression of NF-κB. The inhibitory mechanism involved suppression of Ca oscillation in osteoclast precursors resulting in the decreased NFATc1 expression and nuclear localization, which is a crucial prerequisite for osteoclastogenesis. The administration of acalabrutinib significantly reduced P. gingivalis lipopolysaccharide-induced alveolar bone erosion in mice.

Conclusion: These data indicate that acalabrutinib is an effective inhibitor of osteoclastogenesis both in vitro and in vivo, with a potential for a novel strategy against bone destruction by periodontitis.
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http://dx.doi.org/10.1002/JPER.18-0334DOI Listing
May 2019

Prevalence and Risk Factors of Atypical Femoral Fracture Bone Scintigraphic Feature in Patients Experiencing Bisphosphonate-Related Osteonecrosis of the Jaw.

Nucl Med Mol Imaging 2018 Aug 16;52(4):311-317. Epub 2018 Jul 16.

1Department of Nuclear Medicine, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.

Purpose: Bisphosphonate (BP) is the first-line therapy for the management of osteoporosis. BP-related osteonecrosis of the jaw (BRONJ) and atypical femoral fracture (AFF) are increasingly common comorbidities in patients with osteoporosis under long-term BP treatment. The aim of this study was to evaluate the incidence and risk factors for AFF features on bone scintigraphy in patients with BRONJ.

Methods: Among total of 373 BRONJ patients treated between September 2005 and July 2014, 237 (220 women, 17 men; median age 73 years) who underwent three-phase bone scintigraphy were enrolled for this retrospective study. AFF features on bone scintigraphy and the related clinical factors were assessed.

Results: Among 237 patients with BRONJ, 11 (4.6%) showed AFF features on bone scintigraphy. BP medication duration ( = 0.049) correlated significantly with AFF features on bone scintigraphy in patients with BRONJ. BP intake duration of 34 months was the cutoff value for predicting the presence of AFF features on bone scintigraphy. Among the patients with BRONJ, all those with AFF features on bone scintigraphy were female patients with osteoporosis who were on oral BP medication; however, these factors were not significantly different along with AFF features on bone scintigraphy.

Conclusion: The incidence of AFF features on bone scintigraphy was relatively high in patients with BRONJ. A careful observation of patients presenting with the AFF features on bone scintigraphy may be needed, particularly for female BRONJ patients with osteoporosis who have been on BP medication for over 34 months.
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http://dx.doi.org/10.1007/s13139-018-0533-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6066490PMC
August 2018

Accuracy and reliability of three-dimensional computer-assisted planning for orthognathic surgery.

Authors:
Tae-Geon Kwon

Maxillofac Plast Reconstr Surg 2018 Dec 25;40(1):14. Epub 2018 Jun 25.

Department of Oral & Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Samduck 2 Ga, Jung Gu, Daegu, 700-421 South Korea.

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http://dx.doi.org/10.1186/s40902-018-0154-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6015791PMC
December 2018

Emphysema following air-powder abrasive treatment for peri-implantitis.

Maxillofac Plast Reconstr Surg 2018 Dec 13;40(1):12. Epub 2018 May 13.

Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, 2177 Dalgubeol-daero, Jung-gu, Daegu, 41940 Republic of Korea.

Background: Subcutaneous emphysema refers to swelling caused by the presence of air or gas in the interstices of loose connective tissue. In the head and neck area, it may follow the fascial planes and is characterized by sudden swelling, crepitus on palpation, infrequent pain, and air emboli on radiography. It usually occurs as a complication in dental treatment. Some reports have described subcutaneous emphysema caused by dental procedures; however, severe emphysema related to peri-implantitis after treatment has not been documented. Accordingly, the current report describes a rare case of subcutaneous cervical emphysema resulting from the use of an air-powder abrasive device to treat peri-implantitis.

Case Presentation: Based on a review of the existing literature and the present case, nine cases of subcutaneous emphysema due to air-powder abrasive device have been reported. In most cases, the emphysema resolved over time after treatment with prophylactic antibiotics; among these, two were related to peri-implantitis management.

Conclusion: Considering the frequent use of air-powder abrasive devices to treat peri-implantitis, the potential risk of iatrogenic emphysema related to this procedure needs to be addressed more extensively.
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http://dx.doi.org/10.1186/s40902-018-0151-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5949097PMC
December 2018

Magnesium phosphate ceramics incorporating a novel indene compound promote osteoblast differentiation in vitro and bone regeneration in vivo.

Biomaterials 2018 03 7;157:51-61. Epub 2017 Dec 7.

Department of Pathology and Regenerative Medicine, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea. Electronic address:

Incorporating bioactive molecules into synthetic ceramic scaffolds is challenging. In this study, to enhance bone regeneration, a magnesium phosphate (MgP) ceramic scaffold was incorporated with a novel indene compound, KR-34893. KR-34893 induced the deposition of minerals and expression of osteoblast marker genes in primary human bone marrow mesenchymal stem cells (BMSCs) and a mouse osteoblastic MC3T3-E1 cell line. Analysis of the mode of action showed that KR-34893 induced the phosphorylation of MAPK/extracellular signal-regulated kinase and extracellular signal-regulated kinase, and subsequently the expression of bone morphogenetic protein 7, accompanied by SMAD1/5/8 phosphorylation. Accordingly, KR-34893 was incorporated into an MgP scaffold prepared by 3D printing at room temperature, followed by cement reaction. KR-34893-incorporated MgP (KR-MgP) induced the expression of osteoblast differentiation marker genes in vitro. In a rat calvaria defect model, KR-MgP scaffolds enhanced bone regeneration and increased bone volume compared with MgP scaffolds, as assessed by micro-computed tomography and histological analyses. In conclusion, we developed a method for producing osteoinductive MgP scaffolds incorporating a bioactive organic compound, without high temperature sintering. The KR-MgP scaffolds enhanced osteoblast activation in vitro and bone regeneration in vivo.
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http://dx.doi.org/10.1016/j.biomaterials.2017.11.032DOI Listing
March 2018

Three-dimensional surgical simulation for facial asymmetry: soft tissue-, skeleton-, and occlusion-based planning.

Authors:
Tae-Geon Kwon

Maxillofac Plast Reconstr Surg 2017 Dec 5;39(1):36. Epub 2017 Dec 5.

Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Samduck 2 Ga, Jung Gu, Daegu, 700-421 South Korea.

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http://dx.doi.org/10.1186/s40902-017-0135-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5714943PMC
December 2017

Nasal Deviation in Patients With Asymmetric Mandibular Prognathism.

J Craniofac Surg 2017 Oct;28(7):e700-e704

*Department of Dentistry and Oral Surgery, Dong-san Medical Center, School of Medicine, Keimyung University, Dong-san dong, Jung Gu †Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook, National University ‡Department of Dentistry and Oral Surgery, Dong-san Medical Center, School of Medicine, Keimyung University, Dong-san dong §Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, Korea.

Purpose: This study was aimed to evaluate the nasal deviation in patients with asymmetric mandibular prognathism.

Materials And Methods: Thirty-five patients with skeletal class III malocclusion were included in the study. Significant mandibular asymmetry of >4 mm menton deviation in three-dimensional (3D) reformatted cone beam computed tomography images was defined as asymmetry group (n = 20). Patients without mandibular asymmetry served as control group (n = 15). The mandibular asymmetry was evaluated pre- and postoperatively.

Results: Nasal tip was significantly shifted to the deviated side of the mandible (short side) in the asymmetry group, as compared to the control group (1.5 ± 0.9 degree, P < 0.01). Alar base angle (ABA) was significantly narrower in nondeviated side (long side) than in the deviated side in asymmetry group. However, control group showed no bilateral difference in ABA. Correction of deviated mandibular prognathism by isolated mandibular surgery resulted in change in the ABA but not the columella base position or nasal asymmetry. ABA on nondeviated side significantly decreased in proportion to the amount of transverse menton movement by surgery (r = -0.560, P < 0.01).

Conclusion: Our results showed that mandibular chin deviation was accompanied by nasal deviation. Isolated mandibular surgery can potentially influence the alar base position on the contralateral side of deviation but not the nasal tip asymmetry. Therefore, clinicians should inform patients preoperatively of the fundamental limitation of mandibular surgery in cases with preexisting nasal asymmetry.
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http://dx.doi.org/10.1097/SCS.0000000000003894DOI Listing
October 2017

Perioral soft tissue change after isolated mandibular surgery for asymmetry patients.

J Craniomaxillofac Surg 2017 Jun 12;45(6):962-968. Epub 2017 Feb 12.

Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu 41940, Republic of Korea. Electronic address:

Introduction: This study was intended to determine whether isolated mandibular surgery for the correction of asymmetry could also change perioral soft tissue asymmetry.

Patients And Methods: Skeletal class III patients who had undergone mandibular set-back surgery were included. The subjects were composed of two groups with (n = 20) or without (n = 30) menton (Me) deviation over 4 mm. The perioral lip landmarks were analyzed on three-dimensional image from cone-beam computed tomography taken before and 6 months after the operation. The bilateral and inter-group differences and pre- and post-operative changes were statistically analyzed.

Results: The corner of mouth on the deviated side was 1.9 mm shorter vertically than that on the contralateral side in patients with asymmetry. After mandibular surgery, the deviated Me moved 5.5 mm to the contralateral side and the lip canting was corrected by 2.4° in the asymmetry group. The degree of Me deviation was significantly correlated with the degree of midline asymmetry in perioral soft tissue landmarks including subnasale, upper and lower lip midline. The predictor variable that affected the changes in lip cant was the surgical correction of Me deviation.

Discussion: The correction of chin deviation by isolated mandibular surgery could significantly improve the subnasal and lip asymmetry.
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http://dx.doi.org/10.1016/j.jcms.2017.01.039DOI Listing
June 2017

Displacement of Dental Implants Into the Mandibular Bone Marrow Space: Cause and Treatment. A Case Study and Literature Review.

J Oral Implantol 2017 Apr 13;43(2):151-157. Epub 2017 Jan 13.

Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea.

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http://dx.doi.org/10.1563/aaid-joi-D-16-00205DOI Listing
April 2017

Botulinum toxin related research in maxillofacial plastic and reconstructive surgery.

Authors:
Tae-Geon Kwon

Maxillofac Plast Reconstr Surg 2016 Dec 5;38(1):34. Epub 2016 Sep 5.

Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, 2177 Dalgubeoldaero, Jung Gu, Daegu, 41940 South Korea.

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http://dx.doi.org/10.1186/s40902-016-0080-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5011153PMC
December 2016

Surgical correction of septal deviation after Le Fort I osteotomy.

Maxillofac Plast Reconstr Surg 2016 Dec 4;38(1):21. Epub 2016 May 4.

Center for Orthognathic surgery, Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Samduck 2 Ga, Jung Gu, Daegu, 700-421 South Korea.

Background: The Le Fort I osteotomy is one of the most widely used and useful procedure to correct the dentofacial deformities of the midface. The changes of the maxilla position affect to overlying soft tissue including the nasal structure. Postoperative nasal septum deviation is a rare and unpredicted outcome after the surgery. There are only a few reports reporting the management of this complication.

Case Presentation: In our department, three cases of the postoperative nasal septum deviation after the Le Fort I osteotomy had been experienced. Via limited intraoral circumvestibular incision, anterior maxilla, the nasal floor, and the anterior aspect of the septum were exposed. The cartilaginous part of the nasal septum was resected and repositioned to the midline and the anterior nasal spine was recontoured. Alar cinch suture performed again to prevent the sides of nostrils from flaring outwards. After the procedure, nasal septum deviation was corrected and the esthetic outcomes were favorable.

Conclusion: Careful extubation, intraoperative management of nasal septum, and meticulous examination of pre-existing nasal septum deviation is important to avoid postoperative nasal septum deviation. If it existed after the maxillary osteotomy, septum repositioning technique of the current report can successfully correct the postoperative septal deviation.
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http://dx.doi.org/10.1186/s40902-016-0067-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4856713PMC
December 2016

Simultaneous gap arthroplasty and intraoral distraction and secondary contouring surgery for unilateral temporomandibular joint ankylosis.

Maxillofac Plast Reconstr Surg 2016 Dec 3;38(1):12. Epub 2016 Mar 3.

Department of Oral and Maxillofacial Surgery, School of Dentistry, Kyungpook National University, Daegu, 700-421 Korea.

Background: Temporomandibular joint (TMJ) ankylosis can be accompanied by various degrees of functional and esthetic problems. Adequate mouth opening, occlusal stability, and harmonious facial form are the main goals of treatment for ankylosis. Distraction osteogenesis has proven to be an excellent treatment for lengthening the ramus-condyle unit. However, various timings for distraction have been suggested, and there is no consensus on selection criteria for performing the procedure in stages or simultaneously with other treatments.

Case Presentation: In this case report, concomitant intraoral distraction and gap arthroplasty was planned to treat TMJ ankylosis and associated facial asymmetry. After gap arthroplasty and 23 mm of distraction, the ramus-condyle segment was successfully lengthened and mouth opening range was significantly increased. The resultant interocclusal space was stably maintained with an occlusal splint for 4 months after distraction. Finally, good occlusion was achieved after prosthetic treatment. The remaining mandibular asymmetry was corrected with osseous contouring and augmentation surgery. The mouth-opening range was maintained at 35 mm 24 months after treatment.

Conclusion: Gap arthroplasty with intraoral distraction as a one-stage treatment and subsequent contouring surgery can be applied to correct ankylosis with moderate malocclusion and facial asymmetry.
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http://dx.doi.org/10.1186/s40902-016-0058-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4778145PMC
December 2016