Search

Introduction: Pigmented gingival tissue is a common complaint of patients as unaesthetic. There is a dearth of literature comparing the efficacy of depigmentation by cryosurgery using a biocompatible material 1,1,1,2-tetrafluoroethylene gas and diode laser, which are relatively newer techniques. The study aims to evaluate and compare the efficacy of two different modalities of gingival depigmentation – 810 nm diode laser and cryosurgery using 1,1,1,2-tetrafluoroethane in managing gingival melanin pigmentation. Materials and Methods: A randomised controlled split-mouth trial was conducted on 15 participants. Depigmentation was done using an 810 nm diode laser and a cryosurgery technique using 1,1,1,2-tetrafluoroethane. Re-evaluation was performed at the 1st, 3rd and 6th months postoperatively. Dummett’s Oral Pigmentation Index (DOPI), Hedin’s Melanin Index (HMI), the Visual Analogue Scale for pain and Photometric analysis (RGB scale) were recorded and analysed. Results: DOPI and HMI in the subjects treated by laser and cryosurgery showed statistically significant differences (P < 0.001) from baseline to 1 month, 3 months and 6 months. Intergroup comparison of RGB scores between the laser and cryosurgery depicted no significant difference at baseline (P = 0.06). Conclusions: Cryosurgery using 1,1,1,2-tetrafluoroethylene and laser ablation using an 810 nm diode laser technique was found to be equally effective for treating gingival pigmentation.

Introduction: Pigmented gingival tissue is a common complaint of patients as unaesthetic. There is a dearth of literature comparing the efficacy of depigmentation by cryosurgery using a biocompatible material 1,1,1,2-tetrafluoroethylene gas and diode laser, which are relatively newer techniques. The study aims to evaluate and compare the efficacy of two different modalities of gingival depigmentation – 810 nm diode laser and cryosurgery using 1,1,1,2-tetrafluoroethane in managing gingival melanin pigmentation. Materials and Methods: A randomised controlled split-mouth trial was conducted on 15 participants. Depigmentation was done using an 810 nm diode laser and a cryosurgery technique using 1,1,1,2-tetrafluoroethane. Re-evaluation was performed at the 1st, 3rd and 6th months postoperatively. Dummett's Oral Pigmentation Index (DOPI), Hedin's Melanin Index (HMI), the Visual Analogue Scale for pain and Photometric analysis (RGB scale) were recorded and analysed. Results: DOPI and HMI in the subjects treated by laser and cryosurgery showed statistically significant differences (P < 0.001) from baseline to 1 month, 3 months and 6 months. Intergroup comparison of RGB scores between the laser and cryosurgery depicted no significant difference at baseline (P = 0.06). Conclusions: Cryosurgery using 1,1,1,2-tetrafluoroethylene and laser ablation using an 810 nm diode laser technique was found to be equally effective for treating gingival pigmentation. [ABSTRACT FROM AUTHOR]

AbstractElastomers are the class of materials that are widely used in a variety of industrial, commercial, and consumer applications due to their unique mechanical properties, including high elasticity, high flexibility, and high resilience. However, there are many challenges in machining of elastomers such as poor surface finish, build up of heat, degradation of elastomers, etc. To overcome these challenges, cryogenic cooling assistance has been introduced as a means of improving the machinability of elastomers. This paper presents a soft computing approach for optimizing the surface roughness and cutting force during turning of elastomers under different lubrication conditions. Three types of elastomers, namely Nitrile Rubber (NBR), Polyurethane Rubber (PU), and Neoprene Rubber (CR), are studied, and a cryogenic fluid delivery system is employed to improve the machining process. Taguchi’s L27 array is used to vary the input parameters, and a Back-Propagation Artificial Neural Network (BPANN) model is developed to predict the cutting force and surface roughness. The cutting force and surface roughness are analyzed under different cooling conditions, cutting speeds, feeds, and depths of cut for various elastomers. The results show that changes in cutting conditions significantly affect the cutting force and that the type of lubrication used affects the cutting force by altering the material’s physical properties. Cutting force is significantly influenced by cutting conditions, and NBR requires the highest cutting force compared to PU and CR. Further, at a cutting speed of 55 m/min, a feed of 0.11 mm/rev, and a depth of cut of 0.25 mm, the cutting force for NBR (85.1 N), while for PU (75.1 N) and CR (80.3 N), respectively. Finally, with LN2 lubrication conditions, the Cutting Force decreased by 45% and Surface Roughness decreased by 16.9%. This study provides insights into the factors affecting the elastomer machining process, which can be useful for optimizing the machining process parameters and improving machining efficiency.

Elastomers are the class of materials that are widely used in a variety of industrial, commercial, and consumer applications due to their unique mechanical properties, including high elasticity, high flexibility, and high resilience. However, there are many challenges in machining of elastomers such as poor surface finish, build up of heat, degradation of elastomers, etc. To overcome these challenges, cryogenic cooling assistance has been introduced as a means of improving the machinability of elastomers. This paper presents a soft computing approach for optimizing the surface roughness and cutting force during turning of elastomers under different lubrication conditions. Three types of elastomers, namely Nitrile Rubber (NBR), Polyurethane Rubber (PU), and Neoprene Rubber (CR), are studied, and a cryogenic fluid delivery system is employed to improve the machining process. Taguchi's L27 array is used to vary the input parameters, and a Back-Propagation Artificial Neural Network (BPANN) model is developed to predict the cutting force and surface roughness. The cutting force and surface roughness are analyzed under different cooling conditions, cutting speeds, feeds, and depths of cut for various elastomers. The results show that changes in cutting conditions significantly affect the cutting force and that the type of lubrication used affects the cutting force by altering the material's physical properties. Cutting force is significantly influenced by cutting conditions, and NBR requires the highest cutting force compared to PU and CR. Further, at a cutting speed of 55 m/min, a feed of 0.11 mm/rev, and a depth of cut of 0.25 mm, the cutting force for NBR (85.1 N), while for PU (75.1 N) and CR (80.3 N), respectively. Finally, with LN2 lubrication conditions, the Cutting Force decreased by 45% and Surface Roughness decreased by 16.9%. This study provides insights into the factors affecting the elastomer machining process, which can be useful for optimizing the machining process parameters and improving machining efficiency. [ABSTRACT FROM AUTHOR]

The abuse of inhalants has become a public health concern in the USA over the past decade. Compressed air duster cans currently available in the USA contain highly toxic substances including different hydrofluorocarbons (including tetrafluoroethane and difluoroethane) which exert a psychoactive effect on the central nervous system. Several cases of inhalant-induced lethal arrhythmia such as ventricular fibrillation evolving to torsade de pointes and leading to cardiac arrest, have been reported in the literature. Furthermore, multiorgan failure including liver and kidney injury has been described after inhalant abuse. We report the case of a 33-year-old man found diaphoretic and with a near syncopal episode after inhalation of several cans of Surf Onn electronic duster gas cleaner, who subsequently developed acute cardiac, liver and kidney injury.

A superficial skin abscess in a young black female patient was incised after cryoanesthesia with Tetrafluoroethane spray. A hypopigmented area was found at the first follow-up visit in the treated skin area; complete repigmentation occurred during the next 4 months. There are no other similar reported cases in the literature. Since long duration and possibly permanent hypopigmentation can occur after cryoanesthesia with Tetrafluoroethane, especially in black people, this technique should be used with extreme caution.

A superficial skin abscess in a young black female patient was incised after cryoanesthesia with tetrafluoroethane spray. A hypopigmented area was found at the first follow-up visit in the treated skin area; complete repigmentation occurred during the next 4 months. There are no other similar reported cases in the literature. Since long duration and possibly permanent hypopigmentation can occur after cryoanesthesia with tetrafluoroethane, especially in black people, this technique should be used with extreme caution. [ABSTRACT FROM AUTHOR]

Aim: This clinical study evaluated the reliability of the 1,1,1,2‐tetrafluoroethane (Endo Ice) cold test to determine the pulpal diagnosis of teeth with full‐coverage restorations (FCR). The effect of several variables on its reliability was also investigated. Methodology: Data collected from 825 patients treated in the Advanced Education Program in Endodontics at the University of Iowa, USA were analysed. The experimental group included 425 teeth with FCR, whilst the control group consisted of 400 teeth with natural crowns (NC). The pulp sensibility test results, tooth type, tooth number, type of crown, age, gender, presence or absence of caries and recent use of analgesics were recorded. Bivariate analyses were performed to assess the variables associated with the accuracy of dental pulp sensibility tests for either teeth with crowns or teeth without crowns using chi‐square tests, Fisher's exact tests, Cochran–Mantel–Haenszel tests, and the Wilcoxon rank‐sum tests. A P‐value of less than 0.05 was used as a criterion for statistical significance, and a P‐value in 0.05 < P < 0.10 was used as a criterion for marginal relevance. Results: The sensibility test results for FCR teeth had an accuracy of 0.866; sensitivity of 0.835; specificity of 0.879; a positive predictive value of 0.746; and a negative predictive value of 0.926. The data indicated a significant difference in the accuracy of pulp sensibility test results between the experimental and control groups (P < 0.001). Although the cold test in FCR teeth still had high accuracy, teeth with NC were significantly more likely to have true‐positive and true‐negative results (91.5% NC vs. 86.6% FCR, P = 0.024). No significant differences between FCR and NC were found concerning gender, tooth type, type of crown, the presence of abutment and recent use of analgesic (P > 0.05). Conclusion: Pulp sensibility cold testing with 1,1,1,2‐tetrafluoroethane (TFE) on teeth with FCR was less accurate than on teeth without full‐coverage crowns. However, the use of TFE cold testing is still a relevant and reliable diagnostic tool, particularly for teeth with a pulpal diagnosis of symptomatic irreversible pulpitis. Clinicians should routinely carry out cold pulp sensibility testing on teeth when making a pulpal diagnosis. [ABSTRACT FROM AUTHOR]

This paper was presented at the ESE Congress 2009, Thursday 24th to Saturday 26th September,at the Edinburgh International Conference Centre, Edinburgh, UK.Aim: The purpose of this study was to compare the anaesthetic efficacy of inferior alveolar nerve block (IANB) using 1.7 ml of 4% articaine with 1:100,000 epinephrine in reversibly and irreversibly inflamed mandibular molars.Materials and methods: Thirty-six adult patients diagnosed with reversible or irreversible pulpitis of a mandibular molar received 1.7 ml of 4% articaine with 1:100,000 epinephrine, using a conventional IANB. Following administration, teeth were tested with Endo-Ice® (1,1,1,2 tetrafluoroethane; Hygenic)at 5- and 10-minute intervals. The parameters to evaluate were onset of lip numbness, onset of pulpal anaesthesia and a painful or non-painful response during the procedure. Success was defined as none or mild pain upon cavity preparation or during access and instrumentation of the root canals. In case of failure, supplemental anaesthesia was administered. Statistical analysis was performed using Fisher's exact test, data on time to lip anaesthesia were analysed through survival analysis techniques, and response to cold and pain during the procedure by two-way tables.Results: The pain was too severe to proceed in 5.3% of the reversible pulpitis group and 66.7% of the irreversible pulpitis group. The trend for more pain in the irreversible pulpitis group was statistically significant (P < 0.001). Pain during the procedure did not show any statistically significant association with response to cold at 5 minutes after IANB (P > 0.999) or time to onset of lip anaesthesia (P = 0.122).Conclusion: The IANB using 1.7 ml of 4% articaine with 1:100,000 epinephrine is much more likely to be inefficient in patients presenting with irreversible pulpitis than in patients with reversible pulpitis.In addition, the absence of pulpal response to Endo-Ice does not guarantee pain-free root canal procedures. [ABSTRACT FROM AUTHOR]