Influence of chemical activation of a 35% hydrogen peroxide bleaching gel on its penetration and efficacy--in vitro study

OBJECTIVES: The aim of this study was to evaluate the effects of chemical activation of hydrogen peroxide (HP) gel on colour changes and penetration through the tooth structure. METHODS: One hundred and four bovine incisors were used. One dentine (CD) disc and one enamel-dentine (ED) disc were prepared from each tooth. They were positioned over artificial pulpal chambers and the bleaching was performed with an experimental 35% HP gel. Two control and six experimental groups were prepared. In the positive control group (PC) no chemical activator was used. In the negative control group (NC) the specimens did not receive any bleaching. Each experimental group received a different chemical activator (manganese gluconate-MG; manganese chlorite-MC; ferrous sulphate-FS; ferrous chlorite-FC; and mulberries root extract-MRE). After the bleaching procedure a sample of solution was collected from the artificial pulpal chamber and the HP concentration was measured. The data were analysed using ANOVA, Tukey's, and Dunnett's tests. RESULTS: The groups MG and FS showed a significantly lower penetration of HP than the PC group. For the parameter Delta E, all the groups, with the exception of the group MRE, showed a significantly higher means in relation to the PC group in ED colour. For dentine colour, just the groups MG and FS had significant differences in relation to PC. CONCLUSIONS: The addition of MG and FS decreases the penetration of HP. The chemical activation using metal salts tested was effective in increasing the bleaching effect

The prevalence of the Carabelli cusp in selected Saudi population

AbstractThe Carabelli cusp is a tubercle or cuspule, or a groove often seen on the palatal surface of the mesiopalatal cusp of maxillary permanent molars and maxillary second deciduous molars. The purpose of this study was to determine the prevalence, degree of expression of the Carabelli structure, and caries prevalence in the Carabelli structure in the permanent first and second maxillary molars in selected Saudi population. Two hundred and seventy six Saudi patients attending the college of dentistry clinics at King Saud University in Riyadh city were selected for examination. The patients’ age ranged from 11 to 55years old. Patients with severely carious, restored or missing upper first or second maxillary molars on any side were excluded. Both the first and the second upper molars were carefully examined for the occurrence of the Carabelli structure and the presence of caries. The prevalence of the Carabelli structure was 57.6% with a bilateralism of 91.2% in the first maxillary molars and 86.4% in the second molars. The Carabelli structure was found to be 29.7% as a groove expression, and 35.5% as a cusp expression. It was concluded that more than half of the Saudi population have a degree of expression of the Carabelli structure and the Carabelli trait is associated with increased caries incidence.Clinical relevance: Prominent pits and grooves can be foci for plaque retention and caries development, a large tubercle can pose some problems with orthodontic bands

Back & Neck Problems among Dentists and Dental Auxiliaries.

In the practice of dentistry, stress, tension, and postural practices can contribute to back and neck problems. Two hundred and four dentists and dental auxiliary (87 males and 117 females) in Riyadh city, Saudi Arabia were surveyed to determine the prevalence of postural problems. The candidates were interviewed and observed during practice. The data obtained showed that 111 (54.4%) of the subjects complained of neck pain and 150 (73.5%) complained of back pain. Only 37% of those complaining of back pain sought medical help. Within the limitations of this study, it might be concluded that neck and back pain among dental personnel are not of a severe nature.King Saud Universit