• The Journal of Advanced Prosthodontics
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• v.8 no.5
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• pp.363-371
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• 2016

PURPOSE. On maxillofacial tumor patients, oral implant placement prior to postoperative radiotherapy can shorten the period of prosthetic reconstruction. There is still lack of research on effects of post-implant radiotherapy such as healing process or loading time, which is important for prosthodontic treatment planning. Therefore, this study evaluated the effects of post-implant local irradiation on the osseointegration of implants during different healing stages. MATERIALS AND METHODS. Custom-made implants were placed bilaterally on maxillary posterior edentulous area 4 weeks after extraction of the maxillary first molars in Forty-eight Sprague-Dawley rats. Experimental group (exp.) received radiation after implant surgery and the other group (control) didn't. Each group was divided into three sub-groups according to the healing time (2, 4, and 8 week) from implant placement. The exp. group 1, 2 received 15-Gy radiation 1 day after implant placement (immediate irradiation). The exp. group 3 received 15-Gy radiation 4 weeks after implant placement (delayed irradiation). RESULTS. The bone mineral density (BMD) was significantly lower in the immediate irradiation groups. BMD was similar in the delayed irradiation group and the control group. The irradiated groups exhibited a lower bone-to-implant contact ratio, although the difference was not statistically significant. The irradiated groups also exhibited a significantly lower bone volume and higher empty lacuna count than the control groups. No implant failure due to local irradiation was found in this study. CONCLUSION. Within the limits of this study, the timing of local irradiation critically influences the bone healing mechanism, which is related to loading time of prostheses.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.40
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• pp.16.1-16.5
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• 2018

Background: Proliferative verrucous leukoplakia (PVL) is an oral potentially malignant disorder, characterized by multifocal expression, progressive clinical evolution, and a high rate of malignant transformation. Evidence-based information regarding optimal PVL management is lacking, due to the paucity of data. The present report describes a case of PVL associated with HPV-16 infection and epithelial dysplasia treated by diode laser surgery, and the outcome of disease clinical remission over a 2-year follow-up period. Case report: A 61-year-old Caucasian male with oral verrucous hyperkeratosis presented for diagnosis. The lesions were localized on the maxillary gingiva and palatal alveolar ridge. Multiple biopsy specimens have been taken by mapping the keratotic lesion area. Microscopic examination was compatible with a diagnosis of PVL with focal mild dysplasia, localized in the right maxillary gingiva. Polymerase chain reaction (PCR) was done for human papillomavirus (HPV) detection which revealed presence of HPV DNA, and the genotype revealed HPV 16 in the sample. The PVL in the right gingival area was treated on an outpatient basis by excision with a diode laser. This approach resulted in good clinical response and decreased morbidity over a 2-year follow-up period. Conclusions: This case illustrates the benefit of a conservative approach by diode laser treatment than wide surgical excision for management of the PVL lesions associated with mild dysplasia and HPV-16 infection.

• Radiation Oncology Journal
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• v.21 no.2
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• pp.112-117
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• 2003

Purpose: The effects of hypefractionation radiation therapy, such as the failure pattern and survival, on the treatment results in advanced stage head and neck cancer were studied. Materials and Methods: Between September 1990 and October 1998, 24 patients with advanced stage (III, IV) head and neck cancers, were treated using hyperfractionation radiation therapy in the Department of Radiation Oncology at the Keimyung University Dongsan Medical Center. The male to female ratio was 7 : 1, and the age range from 38 to 71 years with the median of 56 years. With regard to the TNM stage, 11 patients were stage III and 13 were stage IV. The sites of primary cancer were the nasopharynx in six, the hypopharynx in 6, the larynx in five, the oropharynx in three, the maxillary sinus in three, and the oral cavity in one patient. The radiotherapy was delivered by 6 MV X-ray, with a fraction size of 1.2 Gy at two fractions a day, with at least 6 hours inter-fractional interval. The mean total radiation doses was 72 Gy, (ranging from 64.4 to 75.8 Gy). Follow-up periods ranged between 3 and 136 months, with the median of 52 months. Results: The overall survival rates at 3 and 5 years in all patients were 66.7$\%$, and 52.4$\%$. The disease-free survival rates at 3 and S years (3YDFS, 5YDFS) in all patients were 66.7$\%$ and 47.6$\%$. The 3YDFS and 5YDFS in stage III patients were 81.8$\%$ and 63.6$\%$, and those in stage IV patients were 53.8$\%$ and 32.3$\%$. Ten patients were alive with no local nor distant failures at the time of analyses. Six patients (25$\%$) died due to distant metastasis and 12.5$\%$ died due to local failure. Distant metastasis was the major cause of failure, but 2 patients died due to unknown failures and 3 of other diseases. The distant metastasis sites were the lung (3 patients), the bone (1 patient), and the liver (2 patients). One patient died of second esophageal cancer. There were no severe late complications, with the exception of 1 osteo-radionecrosis of the mandible 58 months after treatment. Conclusion: Although this study was peformed on small patients group, we considered hypefractionated radiation therapy for the treatment of advanced stage head and neck cancer might improve the disease free survival and decrease the local failure with no increase in late complications despite of the slight Increase in acute complications.

• Radiation Oncology Journal
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• v.15 no.3
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• pp.225-231
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• 1997

Purpose : Radiation therapy in combination with surgery has an important role in the therapy of the head and neck cancer We conducted a prospective study for patients with head and neck cancer treated with surgery and radiation to evaluate the effect of therapies on the thyroid gland, and to identify the factors that might influence the development of hypothyroidism. Materials and Methods : From September 1986 through December 1994, 71 patients with head and cancer treated with surgery and radiation were included in this prospective study. Patients' age ranged from 32 to 73 years with a median age of 58 years. There were 12 women and 59 men. The primary tumor sites were larynx in 34 patients, hypopharynx in 13 patients, oral cavity in 12 patients, unknown primary of the neck in 6 patients, salivary gland in 3 patients, maxillary sinus in 2 patients, and oropharynx in 1 patient. Total laryngectomy with neck dissection was carried out in 45 patients and neck dissection alone in 26 patients. All patients were serially monitored for thyroid function (T3, T4, free T4, TSH, antithyroglobulin antibody and antimicrosomal antibody) before and after radiation therapy. Radiation dose to the thyroid gland ranged from 40.6Gy to 60Gy with a median dose of 50Gy The follow-up duration was 3 to 80 months. Results :The overall incidence of hypothyroidism was 56.3\%$);7 out of 71 patients $(9.9\%)$ developed clinical hypothyroidism and 33 patients $(46.4\%)$ developed subclinical hypothyroidism. No thyroid nodules, thyroid cancers, or hyperthyroidism was detected. Hypothyroidism developed earlier in patients who underwent total laryngectomy with neck dissection than in patients with neck dissection alone (P<0.05). The risk factor that significantly influenced the incidence of hypothyroidism was a combination of surgery (total laryngectomy with neck dissection) and radiation therapy (P=0.0000), Four of 26 patients $(15.4\%)$ with neck dissection alone developed hypothyroidism while 36 of 45 patients $(80\%)$ with laryngectomy and neck dissection developed hypothyroidism. Conclusion : The hypothyroidism following surgery and radiation therapy was a relatively common complication. The factor that significantly influenced theincidence of hypothyroidism was combination of surgery and radiation therapy. Evaluation of thyroid function before and after radiation therapy with periodic thyroid function tests is recommended for an early detection of hypothyroidism and thyroid hormone replacement therapy is recommended whenever hypothyroidism develops.

• Korean Journal of Head & Neck Oncology
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• v.14 no.2
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• pp.156-163
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• 1998

Background & Objectives: Frameless fractionated stereotactic radiotherapy(FFSRT) is a modification of stereotactic radiosurgery(SRS) with radiobiologic advantage of fractionation without losing mechanical accuracy of SRS. Local recurrence of head and neck cancer at or near skull base benefit from reirradiation. Main barrier to successful palliation is dose limitation secondary to normal tissue tolerance. We try to evaluate the efficacy and safety of FFSRT as a new modality of reirradaton in these challenging patients. Materials & Methods: Seven patients with recurrent head & neck cancer involving at or near skull base received FFSRT from September 1995 to November 1997. Six patients with nasopharyngeal cancer had received induction chemotherapy and curative radiation therapy. One patient with maxillary sinus cancer had received total maxillectomy and postoperative radiation therapy as a initial treatment. Follow-up ranged from 11 to 32 months with median of 24 months. Three of 7 patients received hyperfractionated radiation therapy(1.1-1.2Gy/fraction, bid, total 19.8-24Gy) just before FFSRT. All patients received FFSRT(3-5Gy/fraction, total 15-30Gy/5-10fractions). Chemotherapy(cis-platin $100mg/m^2$) were given concurrently with FFSRT in four patients. Second course of FFSRT were given in 4 patients with progression or recurrence after initial FFSRT. Because IF(irregularity factor; ratio of surface area of target to the surface area of sphere with same volume as a target) is too big to use conventional stereotactic RT using multiple arc method for protection of radiation damage to critical normal tissue, all patients received FFSRT with conformal method using irregular static ports. Results: Five of 7 patients showed complete remission in follow-up CT &/or MRI. Three of these five patients who developed marginal, in-field, and out-field recurrences, respectively. Another one of complete responders has been dead of G-I bleeding without evidence of local recurrence. One partial responder who showed progressive disease 15 months after initial FFSRT has received additional FFSRT, and then he is well-being with symptomatic improvement. One minmal responder who showed progression of locoregional disease 9 months after $1^{st}$ FFSRT has received 2nd FFSRT, and then he is alive with stable disease. Five of 7 case had showed direct invasion to skull base and had complaint headache and various symptoms of cranial nerve involvement. Four of these five case showed improvement of neurologic symptoms after FFSRT. No significant neurologic complicaltion related to FFSRT was observed during follow-up periods. Tumor volumes were ranged from 3.9 to 50.7 cc and surface area ranged from 16.1 to $114.9cm^2$. IF ranged from 1.21 to 1.74. The average ratio of volume of prescription isodose shell to target volume was 1.02 that indicated the improvement of target coverage and dose distribution with FFSRT with conformal method compared to target coverage with FFSRT with multiple arc method. Conclusion: Our initial experience suggests that FFSRT with conformal method was relatively effective and safe modality in the treatment of recurrent head and neck cancer involving at or near skull base. Treatment benefit included good palliation of symptoms and reasonable radiographic response. However, more experience and additional follow-up are needed to better assess its ultimate role in treating these challenging patients.

• Imaging Science in Dentistry
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• v.50 no.2
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• pp.81-92
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• 2020

Intelligent systems(i.e., artificial intelligence), particularly deep learning, are machines able to mimic the cognitive functions of humans to perform tasks of problem-solving and learning. This field deals with computational models that can think and act intelligently, like the human brain, and construct algorithms that can learn from data to make predictions. Artificial intelligence is becoming important in radiology due to its ability to detect abnormalities in radiographic images that are unnoticed by the naked human eye. These systems have reduced radiologists' workload by rapidly recording and presenting data, and thereby monitoring the treatment response with a reduced risk of cognitive bias. Intelligent systems have an important role to play and could be used by dentists as an adjunct to other imaging modalities in making appropriate diagnoses and treatment plans. In the field of maxillofacial radiology, these systems have shown promise for the interpretation of complex images, accurate localization of landmarks, characterization of bone architecture, estimation of oral cancer risk, and the assessment of metastatic lymph nodes, periapical pathologies, and maxillary sinus pathologies. This review discusses the clinical applications and scope of intelligent systems such as machine learning, artificial intelligence, and deep learning programs in maxillofacial imaging.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.1
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• pp.33-38
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• 2010

Maxillectomy is a treatment option for maxillary cancer, which leaves the patient with a palatal defect. It may cause problems with facial deformation, swallowing, mastication, and speech. These functional problems and changes in appearance may result in psychological problems. To control these deficits after maxillectomy, surgical reconstruction or prosthodontic treatment can be chosen as a treatment option. Obturator prosthesis has been used as a preferred method of rehabilitation for most maxillectomy patients. This case is a patient who was classified Aramany classification II hemi-maxillectomy patient with residual teeth from #11-25, whose teeth had substantial labioversion and clinically lengthened from alveolar bone involution, thus making it hard to select proper framework design and resist to the rotational dislodging force of the obturator. Therefore we selected swing-lock attachment design to remain pre-existing crown and bridges and obtain retention and stability of obturator. The swing-lock RPD is economical than the conventional RPD because we can remain pre-existing crown and bridges. And residual teeth which have mobility and poor prognosis can be successfully retained through properly designed swing-lock RPD as it is functioning as a removable splint on the teeth.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.3
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• pp.239-245
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• 2018

If complication arises after glossectomy which leads to trouble in forming food bolus or transfer of the food, it is possible that either food bolus may block the airway or dysphagia may occur as the food bolus goes down into the airway. To solve the issue, palatal augmentation prosthesis could be used. In this case, the patient with an oral cancer is having difficulties swallowing food after glossectomy. Through taking impressions of polishing surface of his denture referring his tongue movement, the complete denture for the upper jaw was created using the concept of palatal augmentation prosthesis. This new upper denture increases the palatal-tongue contact pressure, allowing the patient to perform better swallowing and better pronunciation.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.6
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• pp.577-583
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• 2008

Langerhans cell histiocytosis (LCH) is characterized by proliferation of pathological Langerhans cells within different organs. It mainly affects children, but adult cases also occur, with an incidence rate of one to two per million. LCH results from the clonal proliferation of Langerhans cells. And its etiopathogenesis is still unknown. The hypothesis that it is a neoplastic or inflammatory disease, as well as the existence or not of immunological, viral or genetic predisposing factors, has been widely discussed in the literature, but no conclusive proof has ever been provided. Although lesions may appear in tissues of various origins such as skin, hypothalamus, liver, lung, or lymphoid tissue, bone is the most common site of the disease. The head and neck are affected in almost 90% of cases. The maxillary and mandibular bones are affected in 5 to 10% of cases. In our report, we present four cases of LCH in patients aged 3, 4, 7 and 9 years respectively, with primary manifestation in maxillofacial area.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.144-150
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• 2008

Multimodal cancer therapy including surgery, chemotherapy, and radiotherapy could not only improve the prognosis of malignancy but also reduce the dosage and toxicity of cancer drug for treatment of malignant tumor. The effects of radiotherapy are generally localized, additive, and accumulative, and depend on dosage, site and cell sensitivity. However, in growing individuals, the dental and skeletal sequelae to radiotherapy result in dental or facial abnormalities that are irreversible : arrested root development, disturbances in enamel formation, microdontia, anodontia, altered tooth eruption and mandibular or maxillary hypoplasia. Especially, the teeth which are developing is affected according to the stage. We report three cases of developmental disturbance of permanent teeth after radiotherapy. These children had received radiotherapy for malignant tumor at the age of 3 to 4 years, in which root hypoplasia, short tapered root and early apex closure were observed. For the management of radiation caries and radiotherapy-related teeth, periodic recall check and oral hygiene instruction are required.