الفهرس 
Introduction and review of literatureOnly 14 pages are availabe for public view
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Abstract
Dentine hypersensitivity (DH) is considered the oldest chief complain and it is a major problem worldwide in which people are seeking for solutions. It is defined as a transient sharp pain that is produced from bare dentin and opened dentinal tubules (DT). Hypersensitivity could be a result of abrasion, erosion, abrfaction or gingival recession, this process is characterized by the displacement of the gingival margin apically towards the cement-enamel junction thereby exposing the cementum into the oral cavity, which could be easily chipped away due to mechanical forces or erosion with acids, exposing the root dentine with opened DT.
There are many methods to reduce DH, either “at Home” or “In Office”, and one of these methods is a novel toothpaste containing CSSP is firstly been introduced as a remineralizing toothpaste for initially demineralized enamel, by formation of HA on the enamel surface, so, this could be a benefit by application of this toothpaste on dentine in patients suffering from DH. It was said that the precipitates of HA on dentin surface and within the dentinal tubules, can occlude the dentinal tubules and resist the acid erosion with up to 600 seconds immersed in acids.
Moreover, one of the novel toothpastes used nowadays is the charcoal toothpastes, it was found that the abrasive property of the charcoal particles could make tooth wear by its star shaped irregular particles and affects dentin surface morphology, it was said that particle size found in charcoal toothpaste was larger than that found in a conventional toothpaste, furthermore, it may aid in reducing hypersensitivity by blocking the DT and formation of precipitates on dentine surface as it was claimed that it has a remineralization action.
Studies show that consumption of soft drinks is one of the major causes that lead to dental erosion and subsequently increasing DH, so, an acidic soft drink challenge was made on the specimen using PEPSI, to test the efficiency of the precipitates made by the two toothpastes if it will be lost or not.
So, the aim of this research was to compare the Black charcoal containing toothpaste versus that containing Calcium silicate and sodium phosphate (CSSP) in occluding DT and to evaluate their efficacy to withstand acidic soft drink challenge, aiming to investigate their possible efficacy in reducing DH, this was carried out through SEM-EDAX.
Materials and Methods
Sixty freshly sound premolar teeth recently extracted for orthodontic reasons were collected, they were washed carefully and stored in distilled water until used, then they were divided into two equal groups: group (G1) and group (G2), Those two groups were further divided into 3 sub-groups for each, which were (G1A), (G1B), (G1C), (G2A), (G2B), (G2C).
A three steps procedure was performed on group (G1) and group (G2) as follows:
Step1: Each specimen was numbered and patent DT record was taken for each specimen with SEM and EDAX.
Step2: The previously numbered Specimens were assigned for toothbrushing with Calcium silicate and sodium phosphate (CSSP) containing toothpaste for group (G1B) and with Black charcoal containing toothpaste for group (G2B) for 3.5 minutes with a slurry composed of the toothpaste and distilled water with ratio 2:1 respectively and then SEM examination was carried out to detect the occluded DT and EDAX was also recorded.
Step3: Specimens were then been assigned for acid resistance challenge by application of (Pepsi) for 10 minutes, and then SEM, EDAX examination and statistical evaluation was carried out to show difference between groups.
Results
In this study, SEM examination of the two control groups (G1A and G2A) presented more or less the same surface features of dentin being with patent regular DT with prominent hyperdense peritubular dentin, uniform concentric circles of collagen fibers inside the tubules and uniform inter-tubular dentin.
In the present study, SEM results of the experimental groups (G1B and G2B) showed a completely and partially obliterated DT with different orientations and loss of recognition of peritubular dentin and irregular inter-tubular dentin.
Meanwhile in the experimental group (G1C), a compacted precipitation which was fully and partially obliterating the DT was found, while (G2C) a wide fully patent DT at the expense of inter-tubular dentin were found, a small number of DT were showing to have some debris within its opening, inter-tubular bridging was found between some tubules which became collapsed and irregular in form, the patent DT were seemed to have inter-connecting cracks, a wide destruction of the DT outline was seen which became irregular and discontinuous with an inter-connecting gap between them.
According to image j analysis to measure the surface area of patent and blocked DT, (G1B) and (G2B) showed no significant difference for blockage, but in (G1C) and (G2C), there was a significant difference for blockage, in which (G1C) recorded the higher values for blockage and the less for patency while the opposite was found in (G2C) which recorded the highest values for patency in comparison with all groups.
The statistical results of this study presented an increase in Ca and P mean values in G1B (CSSP brushing) if compared with any other group. The opposite was to the mean C content which decreased with (G1B) which denotes the remineralization process happened in this group, while the opposite was found in (G2B) (charcoal brushing), in which an elevated C content was found which denotes a high C content of charcoal and according to Ca and P, there was no significant difference between (G2B) and its control group. Meanwhile in (G1C) and (G2C), there was a significant difference in Ca and P in which (G1C) recorded the higher values than (G2C).