Comparison of endodontic sealers in terms of their sealing ability

The purpose of this in vitro study was to compare the apical sealing ability of mineral trioxide aggregate and glass ionomer cement by a dye penetration test. It was carried out at Queen Marry and Westfield College, University of London during 2010-2011 session. Time duration was 6 months. A total of 16 samples of elephant tusk dentine [ivory] were prepared and finished for dye penetration test. Mineral trioxide aggregate and glass ionomer cement were mixed and placed in the prepared samples and were left overnight to set. Then two coats of nail varnish was applied onto the set material and allowed to dry. The samples were then suspended in methylene blue dye for 72 hours. Once dyed the samples were sectioned longitudinally and assessed microscopically with a stereomicro-scope. The dye penetration in the samples was assessed for two endodontic sealers. It was found that mineral trioxide aggregate showed a mean dye penetration value of 7.625mm as compared to mean dye penetration value of glass ionomer cement 3.875mm

interface of glass ionomer sealer and conditioned elephant tusk dentine: a scanning electron microscopy study

The purpose of this in vitro study was to characterize the interface of glass ionomer sealer and dentine conditioned with common endodontic irrigants through scanning electron microscope. The interface between Ketac-Cem radiopaque glass ionomer sealer and elephant tusk dentine conditioned with distilled water, citric acid and phosphoric acid was investigated. Cylinder of glass ionomer sealer was formed on the conditioned dentine surface and allowed to set for 60 minutes. The specimens were first shear tested to failure to determine their adhesive bond strength. Three debonded dentine specimens from each group were then processed for scanning electron microscopic study. The test failed surface of the strongest, intermediate and weakest bond strength specimens were examined. The specimens were cross sectioned and the interface was examined. The microscopic detail of the debonded interfaces between glass ionomer sealer and dentine was assessed in this study. Failures in all of the specimens were found to be mainly cohesive in nature

effect of salivation status and denture wearing on oral candidal activity of the patient

The objective of this study was to see the effect of salivation status on the oral candidal activity and also to see the effect of denture wearing/ non-wearing on the salivation status of the patient. In the methodology a cross sectional, comparative study during March-September 2007 was conducted at Khyber College of Dentistry Peshawar and Zoology Department, University of Peshawar [Pakistan]. Using a structured proforma, data were collected from 100 subjects [50 Denture wearers and 50 non denture wearers]. Stimulated salivary samples were collected and measured after vortex for 5 minutes from each subject. One ml of standard dilution saliva was mixed with 4ml sterile liquid Candida -selective medium. The extent of Candida activity was then determined, biochemically, through change in pH of the medium 24hrs after inoculation and incubation at 37 C. The results showed that 65% patients had normal salivation rate, as compared to 35% belonging to the hyposalivatory group. Among the denture wearers 52.3% were having normal salivation status and 45.7% having hyposalivation status. While among non-denture wearers 47.7% participants were having normal and 54.3% with hyposalivation status. Mean pH change in the normal salivation group was 1.2 +/- 1.0 as compared to 1.5 +/- 1.0 in the hyposalivation group. Association between the variable salivation level and candidal activities [average change in pH of the medium] was insignificant with p-value 0.73. Also association found between the case type [denture I non denture wearers] and salivation status of the patients was insignificant, having p-value 0.52. It was concluded that within the limitations of this study, the salivation status of the patients had an insignificant association with the oral candidal activity

Association of pathological activity of oral candida and denture wearing habit in denture wearers

To assess the effect of denture wearing on oral candidal activity through candida selective medium inoculated with standardized dilution salivary samples obtained from denture wearers. A cross sectional, comparative study during March-September 2007 was conducted at Khyber College of Dentistry Peshawar. Using a structured proforma, data were collected from 50 subjects [50 Denture wearers]. Stimulated salivary samples were collected from each subject. One ml of standard dilution saliva was mixed with 4ml sterile liquid candida -selective medium. The extent of candida activity was then determined, biochemically, through change in pH of the medium 24 hrs after inoculation and incubation at 37°C. Pathological candidal activity was seen in denture wearers. However, the association between the denture wearing habit and candidal activity was found significant, meaning that continuous denture wearing always showed a high pH change [t- value of 0.01] and mean pH decrease of 2.2 in continuous denture wearers as compare to 1.6 in only day time wearers. Beside this denture plaque score, type of dentures and denture hygiene maintenance was found to have insignificant association with the candida activity. Within the limits of this study, denture wearing significantly enhanced the pathogenic activity of oral candida. The importance of rest to denture supporting tissue is re-emphasized

Effect of bleaching on shear bond strength of orthodontic brackets

The purpose of this in vitro study was to determine the effect of bleaching on shear bond strength of orthodontic brackets. This randomized control trial was performed over a period of 6 months in the department of orthodontics, de,Montmorency College of Dentistry, Lahore. A total of one hundred and forty extracted premolar teeth were included which were further divided into two groups. Group A was assigned as control group without bleaching and Group B as study group with bleaching. The teeth in both groups were embedded individually in acrylic placed in rubber moulds using a mounting jig so that the labial surfaces would be parallel to the applied force during the shear test. Group B was bleached with Pola office advanced tooth whitening system and were stored in a solution of 0.9% saline till they were bonded. The bonding process for both groups was then performed in a standard manner. After bonding bracket was properly positioned on its respective tooth. An occluso-gingival load was applied to the bracket producing a shear force at the bracket tooth interface using a computerized shear bonding testing machine. The results showed that there was no statistically significant difference between the shear bond strength of unbleached teeth and that of bleached teeth following a two weeks interval after bleaching

shear bond strength of glass ionomer root canal sealer to elephant tusk dentine conditioned with common endodontic irrigants

The purpose of this in vitro study was to evaluate the shear bond strength of glass ionomer sealer to dentine exposed to common endodontic irrigants in both well and poorly prepared dentine surface. In the methodology four groups of elephant dentine sample were used. Each group was well cleaned and prepared with different irrigants for the effective removal of smear layer. One group was treated with distilled water with smear layer retained. All the dentine used for the experiment was cut in form of disks of about 2.4mm thickness with a hole in the centre and subjected to root canal preparation. All the prepared dentine samples were filled with Ketac-Cem sealer and metal pin was inserted. The shear bond strength of metal pin and sealer was tested using Instron universal testing machine. The observations of bond strength in the four sample groups were analysed statistically through ANOVA test. It was found statistically that shear bond strength with phosphoric acid treated samples was quite higher than the other samples