OBJECTIVEThe purpose was to analyze the effects of three sterilization methods (dry heat sterilization, steam sterilization, and chemical sterilization) on the corrosion of dental fissure bur.

METHODS200 dental fissure burs were distributed to 10 groups. Bending strength, elastic modulus, and torsional strength were measured by bending and torsional instrument and calculated with special designed software. Among the three sterilization methods, the steam sterilization group showed the most evident.

RESULTSThe corrosion was most severe in steam sterilization group, followed by chemical sterilization, dry heat sterilization. With the sterilization time increased, bending strength, elastic modulus, and torsional strength decreased respectively. Of the three sterilization methods, the mechanical properties were decreased most evidently by steam sterilization, followed by chemical sterilization and dry heat sterilization.

CONCLUSIONIt is proved that the bending strength, elastic modulus and torsional strength have a tight relationship with the corrosion of dental fissure burs. The corrosion was most severe in steam sterilization group, followed by chemical sterilization, dry heat sterilization. In regards of the corrosive effect, the dry heat sterilization might be the best way to sterilize the dental fissure burs.

Dental Fissures ; Dental High-Speed Equipment ; Dental Instruments ; Steam ; Sterilization

OBJECTIVETo investigate the effects on performances of high-speed dental handpieces subjected to autoclaving.

METHODSThe method of trial used to evaluate the effect of autoclaving included that ten chemical and ten biological indicators were arranged in each trial group being set by one sort of temperature and sterilization time. The range of temperature was from 100 degrees C to 134 degrees C and the sterilization time was from 1 to 45 minutes. The reliability of autoclaving was evaluated by the result of chemical indicator and the endospores of Bacillus stearothermophilus subjected to autoclaving. Ten newly imported and ten new domestic dental handpieces in two different brands were used to carry out this trial. The effects produced by autoclaving on performances of dental handpieces subjected to different type autoclaves were evaluated by some parameters.

RESULTSThe eligible outcome in killing test of the 221 sterilized dental handpieces proved that the sterilization effect of autoclaving on dental handpieces was reliable. The chemical indicators showed that under the condition of 121 degrees C it needed 20 minutes to reach sterilization standard in the inner package and only 15 minutes on the outer package, and under the condition of 134 degrees C it took 4 minutes to reach sterilization standard in the inner package while only 2 minutes on the outer package. This outcome proved that material with package was more time-consuming than that without package during autoclaving. Autoclaving has positive effects on the performance of dental handpieces, while the autoclave with less-time full sterilization cycle has less effect on it. The performance of dental handpieces sterilized by the autoclave with 6-minute full sterilization cycle might be restorable within certain times of sterilization cycle.

CONCLUSIONThe sterilization effect of autoclaving is reliable. In order to reduce the influence on the performance of dental handpieces subjected to autoclaving, it should be reasonable to use the autoclave by which a full sterilization cycle might take less time and no use of package.

Dental High-Speed Equipment ; Equipment Contamination ; prevention & control ; Sterilization ; methods

OBJECTIVEIt has been demonstrated that when a high-speed handpiece stops rotating, negative pressure will form. Thus, contaminating fluid in which there are many kinds of bacteria and viruses from the external environment will retract into various compartments of the handpiece and the dental unit. The purpose of the study is to compare the preventing effect of antisuction designed handpiece and conventional handpiece on viral contamination at different rotating times.

METHODSTwenty handpieces with or without antisuction device (10 of each) were used in the study. Each handpiece was submerged into 10(-6) microg/microl HBV particle solution rotating 5 and 10 times respectively (every time rotating for 10 seconds). Samples were obtained from the water line and chip air line of the handpieces and examined by RT-PCR.

RESULTSAt the same rotating times, there was statistical significance of the viral concentration between the two kinds of handpieces (P < 0.05) . However, there was no statistical significance of the viral concentration between different rotating times in each group (P > 0.05).

CONCLUSIONContamination taking place in both water and air lines of dental handpiece was not enhanced by increasing the number of rotating times of the handpiece. The antisuction devices installed into the water line and chip air line were demonstrated to prevent viral contamination effectively.

Dental High-Speed Equipment ; virology ; Equipment Contamination ; prevention & control ; Suction

OBJECTIVEThe purpose was to analyze the effects of three sterilization methods (dry heat sterilization, steam sterilization, chemical sterilization) on the corrosion of dental fissure burs.

METHODS100 dental fissure burs were distributed to 10 groups. One was control, the burs in the other 9 groups were treated by dry heat sterilization, steam sterilization, chemical sterilization with 5, 10, 15 cycles respectively. Weight method, scanning electron microscope, micro-hardness measurement were used to analyze the corrosion of dental fissure burs.

RESULTSThe fissure burs gained their weight with cycles of sterilization. 5, 10, 15 cycles of dry heat sterilization, 10, 15 cycles of steam sterilization and 15 cycles of chemical sterilization, the weight of fissure burs were significantly increased (P < 0.05). Scanning electron microscope showed differences on the surfaces of dental fissure burs among the three sterilization groups. After sterilization, spot or partial erosion were seen on the surface of the burs. The steam sterilization groups showed the most evident changes, followed by chemical sterilization groups and dry heat sterilization groups. X-ray energy spectrometer showed the steam sterilization groups had the largest percentage of W, followed by dry heat sterilization groups, chemical sterilization groups and control group. Fe had the opposite trends. Micro-hardness reduced after sterilization. The reduction was most clear in steam sterilization group, followed by chemical sterilization and dry heat sterilization ( P< 0.05). The difference between 5 and 10 times of steam sterilization and 5, 10, 15 times of chemical sterilization were significant difference (P < 0.05). There was no significant difference between 5, 10, 15 times of dry heat sterilization (P > 0.05).

CONCLUSIONThe corrosion is most severe in steamsterilization group, followed by chemical sterilization, dry heat sterilization. Dry heat sterilization shows less corrosion.

Corrosion ; Dental Fissures ; Dental High-Speed Equipment ; Dental Instruments ; Steam ; Sterilization

The pneumomediastinum after a dental treatment occurs rarely and shows almost good prognosis, however it is potentially life-threatening complication. Here we report a case of pneumomediastinum, occurred by air bubbles originated from dental high speed equipment, via head and neck fascial space with literatures review.
Dental High-Speed Equipment ; Head ; Mediastinal Diseases ; Mediastinal Emphysema ; Neck ; Prognosis ; Subcutaneous Emphysema

OBJECTIVETo observe the influence of chemomechanical caries removal on dentin adhesion by scanning electron microscope.

METHODSThe ultrastructure of dentin surfaces and adhesives-dentin bonding interfaces after caries removal by chemomechanical method or drilling were observed.

RESULTSLess smear layer in dentin surface, resin tags in the interface between dentin and Prime&Bond NT/compomer and numerous resin tags and more uniform and closer hybrid layer in the interface between dentin and Adper Prompt-L-Pop/composite were found in chemomechanical preparation than in drilling preparation.

CONCLUSIONSChemomechanical caries removal can benefit dentin adhesion.

Acid Etching, Dental ; Dental Bonding ; Dental Caries ; pathology ; therapy ; Dental High-Speed Equipment ; Dentin ; drug effects ; ultrastructure ; Dentin-Bonding Agents ; pharmacology ; Humans ; Microscopy, Electron, Scanning ; Surface Properties

OBJECTIVEThe purpose of this study was to evaluate the morphological changes of Er, Cr: YSGG laser irradiated dental hard tissues by scanning electron microscopy (SEM).

METHODS12 freshly extracted premolars were treated with fissure bur, Er, Cr: YSGG laser at 4 watt, Er, Cr: YSGG laser at 6 watt, respectively, and then bisected transversally and longitudinally. The tooth slice were prepared with conventional methods and observed by SEM.

RESULTSCompared with fissure bur, laser treatment resulted in a rather scaly and rough surface. The sections were free of smear layer, with open dentinal tubules. No carbonization and thermal damages were observed. The laser at 6 watt appeared rougher than at 4 watt, occasionally caused micro-cracks.

CONCLUSIONThe utilizing of Er, Cr: YSGG laser can contribute to enhance the bond strength between restorative materials and dental hard tissues. It suggests that higher energy could be applied in cutting enamel, whereas the lower energy in dentin.

Dental Cavity Preparation ; instrumentation ; methods ; Dental Enamel ; radiation effects ; ultrastructure ; Dental High-Speed Equipment ; Dentin ; radiation effects ; ultrastructure ; Hardness ; Humans ; In Vitro Techniques ; Lasers ; Microscopy, Electron, Scanning ; Tooth ; radiation effects ; ultrastructure