• Asian Pacific Journal of Cancer Prevention
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• v.17 no.8
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• pp.4175-4179
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• 2016

Background: Oral cavity cancer (OCC) is one of the most common cancers worldwide. No studies have reported on the prevalence and epidemiologic risk factors of oral premalignant lesions (OPLs) in Thailand. The purpose of this study was to investigate the prevalence of OPLs and associated factors in Roi Et Province, Thailand. Materials and Methods: To investigate the prevalence of OPLs, a cross-sectional descriptive study was conducted in which 2,300 subjects over 40 years of age were recruited and screened for the prevalence of OPLs. To identify factors associated with OPLs, a matched case-control study was used in which the subjects were 102 cases with OPL and 102 matched controls without OPLs. The studies were conducted in Roi Et Province during the period 1 February, 2014, to 30 April, 2014, and the data were collected by the use of a structured interview questionnaire and by extraction of information from medical records. Data analyses involved the use of descriptive statistics, McNemar's test, and conditional logistic regression. Results: The overall prevalence of OPLs was 3.8%, and no-one was diagnosed with more than one type of OPL. The factors found to be associated with a statistically significant higher risk of an OPL were betel nut chewing, smoking, and alcohol consumption. The associations with these factors were strong, especially for betel nut chewing and smoking. Conclusions: The habits of betel nut chewing, smoking, and alcohol use are confirmed as factors associated with OPLs in a population of Roi Et Province, Thailand. Campaigns to reduce such risk healthy behaviour are needed, but whether any actual decrease will prevent the eventual transformation of an OPL into an OCC remains an open question.

• 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.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.4
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• pp.282-289
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• 2020

Purpose: The aim of this in vitro study was to evaluate the accuracy of three different intraoral scanners (IOSs) on digital impressions of different types of endocrown cavity preparations. Materials and methods: Two human mandibular molar teeth were prepared with different endocrown abutment designs: one with a buccal wall (Class 2) and the other without a buccal wall (Class 3). Both cavity designs were scanned using a reference desktop scanner (E3) and three different intraoral scanners: Trios3 (TRI group), Cerec Omnicam (CER group), and i500 (I5 group). The obtained Standard Tessellation Language (.stl) datasets were exported to metrology software. The precision was evaluated based on deviations among repeated scan models recorded by each IOS. The trueness was evaluated based on deviations between the reference data and repeated scans. For detecting interaction, data were statistically analyzed using a univariate analysis of variance (ANOVA) and for analyzing the comparison of the test groups data were analyzed by one-way ANOVA and post-hoc Tukey test at the significance level of .05. Results: The deviation values for both cavity designs in the I5 group were significantly lower than those in the other IOS groups in terms of trueness. For both cavity designs, the TRI group exhibited better precision than the other IOS groups. Conclusion: Different technologies of IOS device's and different endocrown prepration designs affected the accuracy of the digital scans.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.2
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• pp.125-136
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• 2006

Statement of problem. The success of the bonding between electroforming gold and resin is dependent on the surface-conditioning technique but its effective technique has net been studied widely. Purpose. The purpose of the study was to evaluate the bond strength between the electroforming gold and resin with varying the surface-conditioning technique. Materials and methods. Sixty rectangular shaped metal specimens were made and one side of each specimen were gold hard plated. The sand-blasted specimens were divided into four experimental groups with fifteen specimens in each group and were treated as follows. Group 1: Silicoating (Rocatec, 3M ESPE)+ Sinfony (3M ESPE), Group 2: SR Link+ SR Adoro (Ivoclar Vivadent), Group 3: Tin plating (Microtin, Danville Engineering)+ SR Link+ SR Adoro, Group 4: Tin plating (Micro tin, Danville Engineering)+ Silicoating (Rocatec)+ Sinfony. Shear bond strength at metal-resin interface were measured using universal testing machine. Energy Dispersive x-ray analysis was done and scanning electron microscope images were taken and observed. Results and Conclusion. The following conclusions were drawn. 1. The mean shear bond strength values in order were 11.69MPa (Group 2), 22.35MPa (Group 3), 22.40MPa (Group 1) and 27.71MPa (Group 4). There was no significant difference in Group 1, Group 3 and Group 4(P>0.05). 2. In the EDX line analysis, the Au was detected on the surface of all specimen. $SnO_2$ showed on the surface of Group 2 and $SiO_2$ was detected on the surface of Group 1. 3. Increasing of roughness by sandblasting(Group 2), formation of micro-irregularities and tin crystals by electrolytic tin plating(Group 3) and formation of surface irregularities and $SiO_2$ layer(Group 1,4) were observed in SEM photo. 4. Tin plating(Group 3) and Rocatec treatment(Group 1) showed clinically effective shear bond strength(>20MPa), but when the two surface conditioning method were used together higher bond strength were achieved.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.3
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• pp.215-222
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• 2014

Purpose: The aim of this study was to investigate differences between the morphology of the mandibular symphysis and four facial skeletal types. Materials and Methods: 40 cone-beam computed tomographies were selected and classified in to 4 groups according to their vertical and anterior-posterior skeletal patterns. The bone volume ($mm^3$) of the symphysis, the cross sectional area corresponding to the 4 mandibular incisors' axis: the cross sectional area of total bone ($mm^2$), the area of the cancellous bone ($mm^2$) and the thickness (mm) of labial and lingual alveolar bone at 2 mm, 3 mm under the cemento-enamel junction (CEJ) were measured. General linear model (GLM), Kruskal-Wallis test and Tukey honestly significant difference (HSD) test were subsequently used for statistical analysis. Results: The lingual cortical bone thickness of the lateral incisors at 2, 3 mm under CEJ was greater in the Class I low angle group than the other 3 groups (P < 0.05). There were no statistically significant differences in the volume of the mandibular incisor bony support, cross-sectional area of total bone and cancellous bone at the mandibular incisor' axis. Conclusion: Patients in Class I, low angle group have a thicker lingual mandibular symphysis than Class I, high angle patients.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.1
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• pp.7-18
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• 2017

Purpose: Nonsteroidal anti-inflammatory drugs that prohibit biosynthesis of arachidonic acid metabolites have been considered potent host modulation agents. The aim of this review was to determine the effect of nonsteroidal anti-inflammatory drugs adjunctive with nonsurgical periodontal treatment in patients with periodontal disease. Materials and Methods: Three electronic databases were searched to identify relevant studies. The methodological quality and mean differences of the change in clinical attachment level and probing depth were analyzed according to Cochrane review methods. Results: Twelve studies were included in the methodological assessment and nine studies were suitable for inclusion in the meta-analysis. The mean difference in the clinical attachment level gain did not differ significantly between the nonsteroidal anti-inflammatory drugs and control groups at any observation time. The highest mean difference in clinical attachment level gain was 0.30 mm at 4 weeks (95% confidence interval = -0.37 to 0.97). There was a significant mean difference in the probing depth reduction, of 0.34 mm (95% confidence interval = 0.29 to 0.40) at 6 weeks. Conclusion: Therefore, nonsteroidal anti-inflammatory drugs have additional therapeutic effect when administrated with nonsurgical periodontal treatment.

• The korean journal of orthodontics
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• v.28 no.3 s.68
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• pp.371-377
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• 1998

To estimate the possibility of clinical application of TiN ion-Plated Elgiloy(Co-Cr wire), measurements of tensile strength and hardness were made on the four tempers on each of the manufactured Elgiloy, the (heat-treated) Elgiloy for 30 minutes at $250^{\circ}C$ and the TiN ion-plated Elgiloy. For comparison, the tensile strength and hardness of Stainless Steel wires were also measured. The following are the results of the study: $\cdot$In the 4 tempers, tensile strength was the greatest in the TiN ion-plated group, followed by the heat-treated Elgiloy group and the manufactured Elgiloy group, but no statistical difference was noticed between heat-treated and manufactured Elgiloy groups(p>0.05). $\cdot$In each temper, tensile strength of ion-plated Elgiloy increased about $10kgf/mm^2$ in comparison with the values of the manufactured Elgiloy $\cdot$In yellow, green and red tempers except the blue, hardness was the greatest in ion-plated group. In the blue temper, there was no statistical difference between heat-treated and manufactured Elgiloy groups(p>0.05). $\cdot$In each temper, hardness of ion-plated Elgiloy increased about 50-90VHN in comparison with the values of the manufactured Elgiloy. $\cdot$The tensile strength of Stainless Steel wire was similar to that of the red temper of manufactured Elgiloy and the green temper of ion-plated Elgiloy.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.22 no.1
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• pp.30-46
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• 2013

Porcelain fused to metal crown has been used mostly over the last 50 years for restorations in dentistry. However, the patients' awareness of aesthetic aspect, biocompatibility and the problems such as an allergy to metals led to the growing interest in the 'metal free restoration'. In particular, the price of the precious metals that have been mainly used to date has risen drastically, which made them impossible to play their role as oral restorative materials anymore, and in addition, the PFM restoration has intrinsic problems of chipping and fracture. Therefore, the CAD/CAM has been drawing more attention than ever due to the popular needs for the material that is more aesthetic and stronger for restoration of the molar implant. Considerations in carrying out the full zirconia restoration are as follows: 1) strength, 2) combination work, 3) light penetrability, 4) treatment of cracks, 5) the color reproducibility of the block, 6) the abrasivity of antagonistic tooth, 7) low temperature degradation. In this presentation, the color reproducibility of the block will be discussed. One of the biggest reasons for avoiding the full zirconia restoration is that it is difficult to reproduce the natural color compared to the conventional PFM restoration. Thus, many clinicians show reluctance due to the exposure of the ugly block when the coloring on the surface is removed after occlusal adjustment. From the experience of using blocks by Zirkonzahn for more than 4 years, it is considered that these problems can be addressed to some degrees. Accordingly, how to make restorations that are well in harmony with surrounding prosthesis or natural teeth will be discussed.

• Child Health Nursing Research
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• v.19 no.3
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• pp.159-167
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• 2013

Purpose: The purpose of this study is to find out preschool children's health status and their mothers' health management in the vulnerable classes. Methods: The assessment tool was developed, taken into consideration existing studies, materials produced by the customized visiting health care system, and review of visiting nurses of health centers and related experts. Data were collected January to February 2010 from 259 mothers by visiting nurses, and analyzed using SAS program for descriptive statistics. Results: Body weight less than 3 percentile was found for 5.0% children and over 97 percentile for 7.7%. Atopy was found in 17.8% children, no hand-washing after toileting and before meal in 30.9% and 36.7% respectively, no breakfast in 15.8%, and irregular meal in 32.0%. Sex education was made by 45.7% mothers, regular dental check by 56.6%, and hearing and eyesight test by 61.1% and 66.8% respectively. Home environment for upbringing is 34.3 in the scale of 41, and accident prevention 17.5 in the scale of 22. Conclusion: It is necessary to make an intervention on children's weight, personal sanitation and meal time in the vulnerable classes. Mothers need to be educated for appropriate health care, and home environments to improve upbringing and accident prevention.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.3
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• pp.189-198
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• 2017

Purpose: This study aims to analyze the stress distribution of mandibular molar restoration supported by the implants with external hex and internal taper abutment connection design. Materials and Methods: Models of external connection (EXHEX) and internal connection (INCON) implants, corresponding abutment/crowns, and screws were developed. Supporting edentulous mandibular bony structures were designed. All the components were assembled and a finite element analysis was performed to predict the magnitude and pattern of stresses generated by occlusal loading. A total of 120 N static force was applied both by axial (L1) and oblique (L2) direction. Results: Peak von Mises stresses produced in the implants by L2 load produced 6 - 15 times greater than those by L1 load. The INCON model showed 2.2 times greater total amount of crown cusp deflection than the EXHEX model. Fastening screw in EXHEX model and upside margin of implant fixture in INCON model generated the peak von Mises stresses by oblique occlusal force. EXHEX model and INCON model showed the similar opening gap between abutment and fixture, but intimate sealing inside the contact interface was maintained in INCON model. Conclusion: Oblique force produced grater magnitudes of deflection and stress than those by axial force. The maximum stress area at the implant was different between the INCON and EXHEX models.