A fixed-point observation method was designed to research the dynamic tribological performance of one certain resin-based friction materials. The friction test was performed through a constant speed friction tester un...A fixed-point observation method was designed to research the dynamic tribological performance of one certain resin-based friction materials. The friction test was performed through a constant speed friction tester under various temperature conditions. It was found that the dynamic tribological performance of materials has a good consistency with the dynamic evolution of worn surfaces. At lower temperatures, the friction coefficient and wear rate were constant, resulted from the stable worn surfaces. At higher temperatures, the friction coefficient increased gradually, while the wear rate decreased, due to the increasing contact area and Fe concentration. A fade occurred above 250 ℃, which can be explained by the degradation of binders.展开更多
Introduction: The effective sterilization of reusable instruments in dental care is a crucial issue for public health. The aim of this study was to contribute to improving the processing conditions of reusable care in...Introduction: The effective sterilization of reusable instruments in dental care is a crucial issue for public health. The aim of this study was to contribute to improving the processing conditions of reusable care instruments in dental practices in the city of Conakry. Methods: We carried out an observational and cross-sectional study of a descriptive type lasting three months from January to April 2022 in public and private dental practices approved for activities. Results: A total of 48 dental practices were surveyed, including 7 public and 41 private. 91.67% had the trays for instrument sterilization. 77.08% had a sterilization device. The instruments were: cleaned 100%, disinfected 70.83%, sterilized 20.83% and 20.83% reused the instruments without being sterilized. 72.97% sterilized the instruments at the end of the day. 50% of respondents declared that there were six stages of sterilization. According to standard standards, one dental office or 2.70% respected the normal sterilization process and 13.51% respected the duration and temperature. The storage quality was inadequate at 95.83%. 95.83% of dental practices are at high risk of contamination. The difficulties encountered by staff in daily activity during our study were lack of hygienists (87.50%), insufficient material resources (58.33%), and lack of protocol procedure (45.83%). Conclusion: This study allowed us to note shortcomings of dental surgeons in the process of processing reusable care materials.展开更多
True unilateral posterior crossbite in adults is a challenging malocclusion to treat,especially when we need to correct cross-arch segments with unwanted effects on non-cross segments.Conventional expansion methods ar...True unilateral posterior crossbite in adults is a challenging malocclusion to treat,especially when we need to correct cross-arch segments with unwanted effects on non-cross segments.Conventional expansion methods are expected to have some shortcomings;the Unilateral dental expander appliance used to restore unilateral cross bite dental arch is an uncommon appliance;for this,a designed new device is needed.This paper aimed to invite a new unilateral dental expander appliance(UDEX)to treat unilateral dental posterior crossbite in adults using available dental material,easy to use and handle,well tolerated by the patient,and biocompatible with oral structure.It could find that in all dental markets and dental clinics—an eighteen-year-old female with bilateral crossbite and upper and lower dental arch crowding.During active orthodontic treatment,a quad-helix expander had broken from one side at soldering between band and wire attachment.The patient did not show up to the clinic for a while due to COVID 19 pandemic lockdown,leading to a true unilateral crossbite at the dental arch’s upper left side,especially at the molar premolars area.This unilateral cross bite was treated using a new specially designed expanded appliance as a unilateral posterior cross bite dental maxillary expander.As a result of this study,orthodontic treatment was finished within(15)months,much less than expected.We obtained Class I molar and canine relationships with uncrossed dental arches in both upper arch sides,proper overbite and overjet with well-leveled and aligned teeth as it confirmed by clinical examination and radiographic images(OPG Orthopantomogram)and cephalometric radiograph(WebCeph analysis digitalized computer program).Conclude from that,the newly designed unilateral dental expander(UDEX)is proven to be useful for treating real unilateral posterior crossbites as single molar or premolar tooth and multiple joint unilateral crossed posterior teeth.Also,it could easily modify it for future unilateral crossed purposes.This appliance was fabricated using readily available dental material,well tolerated by patients,and reduced the need for excessive patient compliance.An orthodontist could fabricate devices,or cautious laboratory work is required;it can rapidly achieve favorable results.展开更多
This study aimed to evaluate the surface roughness and wetting properties of various dental prosthetic materials after different durations of non-thermal atmospheric plasma（NTAP）treatment.One hundred and sixty discs...This study aimed to evaluate the surface roughness and wetting properties of various dental prosthetic materials after different durations of non-thermal atmospheric plasma（NTAP）treatment.One hundred and sixty discs of titanium（Ti）（n：40）,cobalt chromium（Co-Cr）（n：40）,yttrium stabilized tetragonal zirconia polycrystals（Y-TZP）（n：40）and polymethylmethacrylate（PMMA）（n：40）materials were machined and smoothed with silicon carbide papers.The surface roughness was evaluated in a control group and in groups with different plasma exposure times [1-3-5 s].The average surface roughness（Ra）and contact angle（CA）measurements were recorded via an atomic force microscope（AFM）and tensiometer,respectively.Surface changes were examined with a scanning electron microscope（SEM）.Data were analyzed with two-way analysis of variance（ANOVA）and the Tukey HSD test α=0.05）.According to the results,the NTAP surface treatment significantly affected the roughness and wettability properties（P 〈 0.05）.SEM images reveal that more grooves were present in the NTAP groups.With an increase in the NTAP application time,an apparent increment was observed for Ra,except in the PMMA group,and a remarkable reduction in CA was observed in all groups.It is concluded that the NTAP technology could enhance the roughening and wetting performance of various dental materials.展开更多
In the mouth, biofilm formation occurs on all soft and hard surfaces. Microbial colonization on such surfaces is always preceded by the formation of a pellicle. The physicochemical surface properties of a pellicle are...In the mouth, biofilm formation occurs on all soft and hard surfaces. Microbial colonization on such surfaces is always preceded by the formation of a pellicle. The physicochemical surface properties of a pellicle are largely dependent on the physical and chemical nature of the underlying surface. Thus, the surface structure and composition of the underlying surface will influence on the initial bacterial adhesion. The aim of this review is to evaluate the influence of the surface roughness and the restorative material composition on the adhesion process of oral bacteria. Both in vitro and in vivo studies underline the importance of both variables in dental plaque formation. Rough surfaces will promote plaque formation and maturation. Candida species are found on acrylic dentures, but dentures coating and soaking of dentures in disinfectant solutions may be an effective method to prevent biofilm formation. Biofilms on gold and amalgam are thick, but with low viability. Glass-ionomer cement collects a thin biofilm with a low viability. Biofilms on composites cause surface deterioration, which enhances biofilm formation. Biofilms on ceramics are thin and highly viable.展开更多
Doped calcium carbonate-phosphate is a biocompatible material that influence actively on the osteogenesis, bone regenerate, strengthening of bone and dental tissues including through the skin. A mechanism of the synth...Doped calcium carbonate-phosphate is a biocompatible material that influence actively on the osteogenesis, bone regenerate, strengthening of bone and dental tissues including through the skin. A mechanism of the synthesis reactions of doped nanocrystalline calcium carbonate-phosphate an oscillating type of model for these reactions is proposed. The results indicate that the synthesis involves the formation of hydroxy carbonate complexes from the three calcium carbonate polymorphs (calcite, vaterite, and aragonite) in a solution of ammonium chloride and ammonium carbonate, followed by reaction with orthophosphoric acid. The formation of nanocrystalline calcium carbonate-phosphate doped with Fe2+, Mg2+, Zn2+, K+, Si4+, and Mn2+, has been studied by X-ray diffraction, IR spectroscopy, differential thermal analysis, and energy dispersive X-ray fluorescence analysis. This ensures the preparation of a bioactive material based on octacalcium hydrogen phosphate, and calcium chloride hydroxide phosphates containing cation vacancies. Particle-size analysis data show that the materials contain nanoparticles down to 10 nm in size. Heat treatment of the doped calcium carbonate phosphates produces calcium hydroxyapatite containing cation vacancies, which can be used as a bioactive ceramic.展开更多
目的:观察成熟恒磨牙去龋未净时露髓使用无机三氧化物聚合体(Mineral trioxide aggregate,MTA)和生物陶瓷类材料(iRoot BP Plus)行直接盖髓术的临床疗效,探讨此类术式的可行性及其影响因素,比较两种盖髓剂疗效的差异。方法:选取2018年4...目的:观察成熟恒磨牙去龋未净时露髓使用无机三氧化物聚合体(Mineral trioxide aggregate,MTA)和生物陶瓷类材料(iRoot BP Plus)行直接盖髓术的临床疗效,探讨此类术式的可行性及其影响因素,比较两种盖髓剂疗效的差异。方法:选取2018年4月-2019年10月就诊于笔者科室符合纳入标准的53例患者,共53颗患牙,随机分为M组和B组,分别使用MTA与iRoot BP Plus行直接盖髓术,术后定期复查,比较两组的临床疗效。结果:共计45例患者(45颗患牙)完成2年随访,总体成功率84.4%;M组和B组分别为85.7%、83.3%,两组比较差异无统计学意义(P>0.05)。性别、年龄、露髓孔大小等因素对疗效均无显著影响(P>0.05)。结论:成熟恒磨牙术中露髓时使用MTA或iRoot BP Plus行直接盖髓术均可获得良好疗效;相较于性别、年龄、露髓孔大小等因素,如何简单准确评判牙髓状态及避免龈下微渗漏更加值得关注。展开更多
基金Funded by the National High-Tech R&D Program of China(863 Program)(SS2015AA042502)
文摘A fixed-point observation method was designed to research the dynamic tribological performance of one certain resin-based friction materials. The friction test was performed through a constant speed friction tester under various temperature conditions. It was found that the dynamic tribological performance of materials has a good consistency with the dynamic evolution of worn surfaces. At lower temperatures, the friction coefficient and wear rate were constant, resulted from the stable worn surfaces. At higher temperatures, the friction coefficient increased gradually, while the wear rate decreased, due to the increasing contact area and Fe concentration. A fade occurred above 250 ℃, which can be explained by the degradation of binders.
文摘Introduction: The effective sterilization of reusable instruments in dental care is a crucial issue for public health. The aim of this study was to contribute to improving the processing conditions of reusable care instruments in dental practices in the city of Conakry. Methods: We carried out an observational and cross-sectional study of a descriptive type lasting three months from January to April 2022 in public and private dental practices approved for activities. Results: A total of 48 dental practices were surveyed, including 7 public and 41 private. 91.67% had the trays for instrument sterilization. 77.08% had a sterilization device. The instruments were: cleaned 100%, disinfected 70.83%, sterilized 20.83% and 20.83% reused the instruments without being sterilized. 72.97% sterilized the instruments at the end of the day. 50% of respondents declared that there were six stages of sterilization. According to standard standards, one dental office or 2.70% respected the normal sterilization process and 13.51% respected the duration and temperature. The storage quality was inadequate at 95.83%. 95.83% of dental practices are at high risk of contamination. The difficulties encountered by staff in daily activity during our study were lack of hygienists (87.50%), insufficient material resources (58.33%), and lack of protocol procedure (45.83%). Conclusion: This study allowed us to note shortcomings of dental surgeons in the process of processing reusable care materials.
文摘True unilateral posterior crossbite in adults is a challenging malocclusion to treat,especially when we need to correct cross-arch segments with unwanted effects on non-cross segments.Conventional expansion methods are expected to have some shortcomings;the Unilateral dental expander appliance used to restore unilateral cross bite dental arch is an uncommon appliance;for this,a designed new device is needed.This paper aimed to invite a new unilateral dental expander appliance(UDEX)to treat unilateral dental posterior crossbite in adults using available dental material,easy to use and handle,well tolerated by the patient,and biocompatible with oral structure.It could find that in all dental markets and dental clinics—an eighteen-year-old female with bilateral crossbite and upper and lower dental arch crowding.During active orthodontic treatment,a quad-helix expander had broken from one side at soldering between band and wire attachment.The patient did not show up to the clinic for a while due to COVID 19 pandemic lockdown,leading to a true unilateral crossbite at the dental arch’s upper left side,especially at the molar premolars area.This unilateral cross bite was treated using a new specially designed expanded appliance as a unilateral posterior cross bite dental maxillary expander.As a result of this study,orthodontic treatment was finished within(15)months,much less than expected.We obtained Class I molar and canine relationships with uncrossed dental arches in both upper arch sides,proper overbite and overjet with well-leveled and aligned teeth as it confirmed by clinical examination and radiographic images(OPG Orthopantomogram)and cephalometric radiograph(WebCeph analysis digitalized computer program).Conclude from that,the newly designed unilateral dental expander(UDEX)is proven to be useful for treating real unilateral posterior crossbites as single molar or premolar tooth and multiple joint unilateral crossed posterior teeth.Also,it could easily modify it for future unilateral crossed purposes.This appliance was fabricated using readily available dental material,well tolerated by patients,and reduced the need for excessive patient compliance.An orthodontist could fabricate devices,or cautious laboratory work is required;it can rapidly achieve favorable results.
基金supported by the Department of Scientific Research,Eskisehir Osmangazi University,Turkey(No.201441045)
文摘This study aimed to evaluate the surface roughness and wetting properties of various dental prosthetic materials after different durations of non-thermal atmospheric plasma（NTAP）treatment.One hundred and sixty discs of titanium（Ti）（n：40）,cobalt chromium（Co-Cr）（n：40）,yttrium stabilized tetragonal zirconia polycrystals（Y-TZP）（n：40）and polymethylmethacrylate（PMMA）（n：40）materials were machined and smoothed with silicon carbide papers.The surface roughness was evaluated in a control group and in groups with different plasma exposure times [1-3-5 s].The average surface roughness（Ra）and contact angle（CA）measurements were recorded via an atomic force microscope（AFM）and tensiometer,respectively.Surface changes were examined with a scanning electron microscope（SEM）.Data were analyzed with two-way analysis of variance（ANOVA）and the Tukey HSD test α=0.05）.According to the results,the NTAP surface treatment significantly affected the roughness and wettability properties（P 〈 0.05）.SEM images reveal that more grooves were present in the NTAP groups.With an increase in the NTAP application time,an apparent increment was observed for Ra,except in the PMMA group,and a remarkable reduction in CA was observed in all groups.It is concluded that the NTAP technology could enhance the roughening and wetting performance of various dental materials.
文摘In the mouth, biofilm formation occurs on all soft and hard surfaces. Microbial colonization on such surfaces is always preceded by the formation of a pellicle. The physicochemical surface properties of a pellicle are largely dependent on the physical and chemical nature of the underlying surface. Thus, the surface structure and composition of the underlying surface will influence on the initial bacterial adhesion. The aim of this review is to evaluate the influence of the surface roughness and the restorative material composition on the adhesion process of oral bacteria. Both in vitro and in vivo studies underline the importance of both variables in dental plaque formation. Rough surfaces will promote plaque formation and maturation. Candida species are found on acrylic dentures, but dentures coating and soaking of dentures in disinfectant solutions may be an effective method to prevent biofilm formation. Biofilms on gold and amalgam are thick, but with low viability. Glass-ionomer cement collects a thin biofilm with a low viability. Biofilms on composites cause surface deterioration, which enhances biofilm formation. Biofilms on ceramics are thin and highly viable.
文摘Doped calcium carbonate-phosphate is a biocompatible material that influence actively on the osteogenesis, bone regenerate, strengthening of bone and dental tissues including through the skin. A mechanism of the synthesis reactions of doped nanocrystalline calcium carbonate-phosphate an oscillating type of model for these reactions is proposed. The results indicate that the synthesis involves the formation of hydroxy carbonate complexes from the three calcium carbonate polymorphs (calcite, vaterite, and aragonite) in a solution of ammonium chloride and ammonium carbonate, followed by reaction with orthophosphoric acid. The formation of nanocrystalline calcium carbonate-phosphate doped with Fe2+, Mg2+, Zn2+, K+, Si4+, and Mn2+, has been studied by X-ray diffraction, IR spectroscopy, differential thermal analysis, and energy dispersive X-ray fluorescence analysis. This ensures the preparation of a bioactive material based on octacalcium hydrogen phosphate, and calcium chloride hydroxide phosphates containing cation vacancies. Particle-size analysis data show that the materials contain nanoparticles down to 10 nm in size. Heat treatment of the doped calcium carbonate phosphates produces calcium hydroxyapatite containing cation vacancies, which can be used as a bioactive ceramic.
文摘目的:观察成熟恒磨牙去龋未净时露髓使用无机三氧化物聚合体(Mineral trioxide aggregate,MTA)和生物陶瓷类材料(iRoot BP Plus)行直接盖髓术的临床疗效,探讨此类术式的可行性及其影响因素,比较两种盖髓剂疗效的差异。方法:选取2018年4月-2019年10月就诊于笔者科室符合纳入标准的53例患者,共53颗患牙,随机分为M组和B组,分别使用MTA与iRoot BP Plus行直接盖髓术,术后定期复查,比较两组的临床疗效。结果:共计45例患者(45颗患牙)完成2年随访,总体成功率84.4%;M组和B组分别为85.7%、83.3%,两组比较差异无统计学意义(P>0.05)。性别、年龄、露髓孔大小等因素对疗效均无显著影响(P>0.05)。结论:成熟恒磨牙术中露髓时使用MTA或iRoot BP Plus行直接盖髓术均可获得良好疗效;相较于性别、年龄、露髓孔大小等因素,如何简单准确评判牙髓状态及避免龈下微渗漏更加值得关注。
