• Journal of Biomedical Engineering Research
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• v.17 no.4
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• pp.491-498
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• 1996

The development of a compact two-wavelength Nd:YAG laser for dental and ENT applications is presented. The Nd:YAG resonator generates either 1.06$\mu$m or 1.32$\mu$m. The wavelength selection is made at the control panel. The Nd:YAG laser parameters at 1.06$\mu$m are ; the maximum pulse duration of 150$\mu$s, repetition rates of I-100Hz, and the maximum average power of 25W. At 1.32$\mu$m, the pulse duration is the same where the repetition rates and the maximum average power are I-30Hz and lOW respectively. High voltage power supply consists of a simmer module and two identical high voltage DC converters. In order to make a complete medical laser system, an optical fiber delivery unit, foot pedal and water spray handpiece are also developed. The wavelength selection is reliable since no movement of optical or mechanical components is required. The high voltage power supply is compact, easy to be maintained and applicable for other laser systems due to its modular design.

• Journal of Technologic Dentistry
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• v.31 no.4
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• pp.31-36
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• 2009

This study evaluated the grindability of series of Ti-Cu alloys in order to develop a Ti alloy with better grindability than commercially pure titanium(CP Ti). Experimental Ti-Xwt%Cu alloys(X=2, 5, 10) were made in an argon-arc melting furnace. Slabs of experimental alloys were ground using a SiC abrasive wheel on an electric handpiece at circumferential speed(15000, 30000rpm) by applying a force(250, 300gr). Grindability was evaluated by measuring the amount of metal volume removed after grinding for 2 minutes. Data were compared to those for CP Ti and Ti-6wt%Al-4wt%V alloy. From results, It was observed that the grindability of Ti-Cu alloys increased with an increase in the Cu concentration compared to CP Ti, particularly the 10wt%Cu alloy exhibited the highest grindability at all speeds. By alloying with Cu, the Ti exhibited better grindability at high speed. The continuous precipitation of $Ti_2Cu$ among the ${\alpha}$-matrix grains made this material less ductile and facilitated more effective grinding because small segments more readily formed. The Ti-10wt%Cu alloy has a great potential for use as a dental machining alloy.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.683-693
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• 2001

The purpose of this study was to evaluate the effects of Er:YAG laser on cutting efficacy and its histologic findings. Dentin specimens of human premolars and molars were used and irradiated by Er:YAG laser with noncontact handpiece type delivery system under different treatment condition of irradiation time. Cavity pattern and volume were evaluated to determine the cutting efficacy and following results were obtained. 1. Cutting volume of sound dentin was getting larger with time immersed in water increase 2. With the condition of irradiation (150mJ, 10Hz, 30sec), surface irregularity was more increased in sound dentin comparing to carious dentin. For the light microscopic examination, dentinal tubules were opened and ash flecks and cracks were noted with inconsistence of dentinal tubules. 3. In case of 30 sec. irradiation in carious dentin, dark zone was limited to small focus whereas 1 min. irradiation, more wider, and cracks were noted in the perpendicular to direction of dentinal tubules. For the 2 min. irradiation, cavity was the widest and more cracks were found.

• Journal of Technologic Dentistry
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• v.35 no.4
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• pp.295-302
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• 2013

Purpose: The grindability of Ti-10%Zr-X%Cr(X=0,1,3) alloys in order to develop Ti alloys for dental applications with better machinability than unalloyed titanium has been evaluated. Methods: Experimental Ti-10%Zr-X%Cr(X=0,1,3) alloys were made in an argon-arc melting furnace. Slabs of experimental alloys were ground using a SiC abrasive wheel on an electric handpiece at one of the four rotational speeds of the wheel (12000, 18000, 25000 or 30000rpm) by applying a force(100gf). Grindability was evaluated by measuring the amount of metal volume removed per minute(grinding rate) and the volume ratio of metal removed compared to the wheel material lost, which was calculated from the diameter loss (grinding ratio). Experimental datas were compared the results with those of cp-Ti(commercially pure titanium) Results: It was observed that the grindability of Ti-10%Zr-X%Cr(X=0,1,3) alloys increased with an increase in the Cr concentration. More, they are higher than cp-Ti, particularly the Ti-10%Zr-3%Cr alloy exhibited the highest grindability at all rotational speeds except 12000rpm. There was significant difference in the grinding rate and grinding ratio between Ti-10%Zr-3%Cr alloy and cp-Ti at all rotational speeds(p<0.05). Conclusion: The Ti-10%Zr-3%Cr alloy exhibited better grindability at high rotational speeds, great potential for use as a dental machining alloy.

• Journal of Technologic Dentistry
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• v.33 no.4
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• pp.263-270
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• 2011

Purpose: The grindability of binary Ti-X%Zr(X=10,20,40) alloys in order to develop a Ti alloy with better machinability than unalloyed titanium has been evaluated. Methods: Experimental Ti-Zr alloys were made in an argon-arc melting furnace. Slabs of experimental alloys were ground using a SiC abrasive wheel on an electric handpiece at circumferential speeds(12000,18000,25000 or 30000rpm) by applying a force(200gr). Grinding rate was evaluated by measuring the amount of metal volume removed after grinding for 1 minute and the volume ratio of metal removed compared to the wheel material lost, which was calculated from the diameter loss (grinding ratio). Experimental datas were compared to those for cp Ti(commercially pure titanium) and Ti-6%Al-4%V alloy were used controls. Results: It was observed that the grindability of Ti-Zr alloys increased with an increase in the Zr concentration. More, they are higher than cp Ti, particularly the Ti-20%Zr alloy exhibited the highest grindability at all circumferential speeds. There was significant difference in the grinding rate and grinding ratio between Ti-20%Zr alloy and cp Ti at any speed(p<0.05). Conclusion: By alloying with Zr, the Ti exhibited better grindability at all circumferential speeds. the Ti-20%Zr alloy has a great potential for use as a dental machining alloy.

• Composites Research
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• v.28 no.4
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• pp.244-248
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• 2015

When a small gear rotates at a very high speed over 40,000 rpm, frictional heat is generated on the gear surfaces. Thermal deformations and stresses arising from frictional heat may lower the efficiency and fatigue life of the high-speed gear. Especially, such frictional heat has much stronger effects on the performance of millimeter-sized high-speed gears used for surgical and dental hand-pieces, due to a small surface area. An analytical equation was derived to calculate frictional temperature on a mating gear surface and conduction heat transfer analysis was performed. Thermal deformation and contact stresses were then calculated using FEM for gears used for medical hand-pieces. The contact stresses of the meshed gear and pinion increase by 19.4% and 16.4%, respectively, when the frictional thermal deformations are considered.

• Journal of dental hygiene science
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• v.15 no.4
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• pp.399-406
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• 2015

The purpose of this study was to investigate the performance of dental infection control. This survey was performed on 158 of the dental hygienist in certain areas. The research was performed using a self-reported questionnaire and interview method from June to July, 2014. The collected data was analyzed by PASW Statistics ver. 18.0. Guideline of infection management, infection controller, regular infection control training, Sterilization of the handpiece/per head resulted 57~74% for dental hospital. It was higher than 13~20% for dental clinics (p<0.05). Infection control guidelines and vaccination recognition of dental were more performed in dental hospital. Patient's hand hygiene performed, tooth brushing before treatment, cross infection educational experience was less than 20%, research cooperation of medical history was over 90% (p<0.05). Performing rate of the dental hospital workers were investigated higher in protective personal devices, infection control of treatment room. A correlation analysis about institutional support, infection control of dental hygienists, patients with infection control cooperation showed a positive correlation statistically significant. Infection control can be enhanced when the medical staff, the patient, the organization combined cognitive and practice. Dental hygienist is required to recognize and practice the infection control guidelines through continuing education.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.1
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• pp.64-80
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• 1998

The risk of cross-contamination in dental clinic is very high. Those who are engaged in dental clinic are exposed to various microorganisms in saliva and blood of patient. Potential possibility of cross-contamination of patient to patient, patient to dentist, dentist to laboratory technician always exist, which is important in the view of public health. It is well known that microorganisms may cause cross-contamination by suck-back of microorganisms into the water supply line or air supply line of dental unit and sprayed back into the next patient's oral cavity. The majority of microorganisms coming from dental unit are water microorganisms from the main water supply which have colonized the tube within the units and multiplied in the relatively warm and stagnant conditions. The purpose of this study is to measure the extent of microbial contamination of dental unit and ultrasonic scaler, to evaluate that dental unit water supply is suitable for drinking water, and to assess the effect of flushing on reduction of microbial contamination of dental unit and ultrasonic scaler. In the first experiment, water samples(50ml) from 20 dental units and 10 ultrasonic scalers in Seoul National Univ. Hosp. were tested for the presence of coliform. The samples were filtered by membrane filtration technique.(Microfil system, Millipore Co. U. S. A.) The filter was then placed onto MacConkey agar plate and the plates with filter on it were incubated aerobically at $37^{\circ}C$ for 5 days. The colors and shapes of colonies were examined if those were coliform. To verify the presence of coliform, the colonies were inoculated into phenol red lactose broth and incubated aerobically at $37^{\circ}C$ for 2 days. The fomation of gas was observed. In the second experiment, water samples from 20 handpieces, 10 ultrasonic scalers and 30 A/W syringes after 0, 2, 4, 6 min. flushing respectively were taken. $200{\mu}l$ water samples were spreaded on Brain Heart Infusion agar plate and the plates were incubated aerobically at $37^{\circ}C$ for 5 days. The number of colony was counted. The results obtained were summarized as follows 1. The water from dental unit and ultrasonic scaler was not suitable for drinking water. 2. No coliform was founded in dental unit and ultrasonic scaler water supply. 3. The number of colony of dental unit and ultrasonic scaler was highest in the group of o min. flushing(p<0.05). 4. There was no statistically significant difference in the extent of microbial contamination among handpiece, ultrasonic scaler and A/W syringe (p>0.05). 5. The number of colony was lowest in the group of 4 min. flushing, but there was no statistically significant difference among 2, 4, 6 min. flushing groups.(p>0.05) 6. It is recommended to flush dental unit water line for 4 min. after use on each patient.

• Imaging Science in Dentistry
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• v.39 no.3
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• pp.149-156
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• 2009

Purpose : The purpose of this study was to develop a stent-based image guided surgery system and to apply it to oral and maxillofacial surgeries for anatomically complex sites. Materials and Methods : We devised a patient-specific stent for patient-to-image registration and navigation. Three-dimensional positions of the reference probe and the tool probe were tracked by an optical camera system and the relative position of the handpiece drill tip to the reference probe was monitored continuously on the monitor of a PC. Using 8 landmarks for measuring accuracy, the spatial discrepancy between CT image coordinate and physical coordinate was calculated for testing the normality. Results : The accuracy over 8 anatomical landmarks showed an overall mean of $0.56{\pm}0.16\;mm$. The developed system was applied to a surgery for a vertical alveolar bone augmentation in right mandibular posterior area and possible interior alveolar nerve injury case of an impacted third molar. The developed system provided continuous monitoring of invisible anatomical structures during operation and 3D information for operation sites. The clinical challenge showed sufficient accuracy and availability of anatomically complex operation sites. Conclusion : The developed system showed sufficient accuracy and availability in oral and maxillofacial surgeries for anatomically complex sites.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.42
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• pp.35.1-35.6
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• 2020

Background: Miescher's cheilitis granulomatosa (MCG) is a rare chronic inflammatory disease and is known as the monosymptomatic clinical form of Melkersson-Rosenthal syndrome (MRS). It is characterised by swelling of one or both lips and more frequently affects the upper lip. Histopathological findings show the presence of numerous inflammatory infiltrates and granuloma formations. Pharmacological treatments and surgery have provided results that are positive yet insufficiently stable in the long term. The clinical case described is of a 68-year-old female patient with a diagnosis of MCG of the upper lip. Case presentation: The patient was diagnosed and treated at the Oral Medicine and Oral Pathology outpatient clinic of Maxillofacial and Odontostomatology Unit, Fondazione Cà Granda IRCCS Ospedale Maggiore Policlinico. The patient was recommended localised treatments of photobiomodulation (PBM) using a diode laser with a 635 nm and 980 nm dual-wavelength (λ) approach, a 600-micron fibre, and a handpiece with a 1-cm-diameter lens at 300 mW. Three treatments a week were administered for four weeks for a total of 12 treatment sessions (T₁-T₁₂). After that, the patient had a long follow-up period of about 2 years. The therapeutic results were clear from the initial stages of treatment. There was an immediate, gradual, and consistent reduction in labial swelling. A reduction in the size of the lip by about 35% at T₁₀-T₁₂ was observed, returning the size and volume of the upper lip within the normal clinical range. The painful symptoms subsided after the seventh treatment (T₇). The histopathological check at 3 months and the follow-up in particular confirmed the disease was in remission with satisfactorily stable treatment results. Moreover, the patient did not use any other treatments on the area from the early laser treatments through to the end of the follow-up period. Conclusions: Our experience describes a clinical case of MCG treated with PBM and effectively resolved with a reduction of the lip swelling. The real success of the treatment emerged over time, showing that the tissue healing was stable. In absence of any collateral phenomena, this confirms the effective and documented therapeutic potential of PBM for chronic inflammatory infiltrates.