EFFECT OF CHICKEN EGGSHELL PASTE ON ENAMEL SURFACE MICROHARDNESS AND COLOUR CHANGE OF ARTIFICIAL CARIOUS LESIONS CREATED ON PERMANENTLY EXTRACTED TEETH.

Remineralizing agents such as fluoride and hydroxyapatite (HA) (Ca5 (po4)3OH) are well-known treatment choices for incipient enamel lesions. Hydroxyapatite has been newly presented to return the color of such enamel lesions. The purpose of this prospective in vitro study was to compare commercial sodium fluoride paste to hydroxyapatite paste (HA) made from chicken eggshells powder (CESP) in terms of how it affected the microhardness and color of the enamel surface of artificially demineralized permanent teeth. Fifty healthy maxillary premolars were gathered, decoronated, and the crowns were placed in acrylic moulds with the buccal enamel surfaces exposed. Baseline microhardness evaluation was done for the baseline group, while the colour assessment was done at baseline to three treatment groups. Then specimens were randomly divided into the following five groups (n = 10) based on the treatment of enamel surface: Group 1: Baseline group; Group 2: Acid group demineralized only; Group 3: demineralized followed by the application of hydroxyapatite paste (HA); Group 4: demineralized followed by the application of sodium fluoride toothpaste (Naf); and Group 5: demineralized followed by application of combination treatments (HA paste at morning and Naf paste at evening. The specimens were stored in deionized water at room temperature during treatments, after one week they were subjected to a Vickers microhardness test, and colour assessment to three treatment groups after treatment. One­way ANOVA and Tukey's post hoc multiple comparison tests were used for statistical analysis (P < 0.05). After artificial demineralization, the enamel's surface microhardness was greatly reduced, and after management, it dramatically increased. The combination group had the greatest mean microhardness value when compared to the HA paste group and the Naf paste group. Statistically, there was no significant variance in microhardness values among the Naf paste and HA paste groups. Hydroxyapatite sourced from chicken eggshell was as effective as Naf paste in remineralizing and restoring the lost microhardness of artificially demineralized enamel, hydroxyapatite paste changed tooth color, while sodium fluoride paste, a combination group neither changed nor masked color of early caries lesion.

A prospective study on the effect of coronal tooth structure loss on the 4-year clinical survival of root canal retreated teeth and retrospective validation of the Dental Practicality Index.

AIM: First, to examine the impact of the residual volume of coronal tooth structure in posterior teeth measured with an intra-oral scanner on the 4-year clinical survival of root canal retreated teeth. Secondly, to assess retrospectively the effectiveness of the Dental Practicality Index (DPI) in predicting the survival of root canal retreated teeth. METHODOLOGY: A total of 156 posterior root canal treated teeth (140 patients) had baseline periapical radiographs (PA) and cone-beam computed tomography (CBCT) scans taken prior to root canal retreatment. These teeth were followed up with a clinical examination at 1, 2, 3 and 4 years (T12, T24, T36 and T48) with periapical radiographs and CBCT images taken at T12, and PA taken at T24, T36 and T48 where appropriate. Root canal retreated teeth were dichotomized into 'survived' versus 'extracted'. Fisher's exact test was used to determine the association between the volume of remaining coronal tooth structure and the 4-year tooth survival. The Dental Practicality Index for each tooth was established using the preoperative clinical and radiographical data. Fisher's exact test was used to establish a relationship between categorical variables, the total score of DPI vs tooth outcome. RESULTS: The percentage of extractions associated with teeth with <29.5% remaining coronal tooth structure was 3 times higher (12.5%) compared to that of teeth with a residual tooth structure > 29.5% (3.5%), but with no significant difference (P = 0.073). There was a significant correlation between the outcome of root canal retreatments at 1 year, assessed by both PA and CBCT, and the 4-year survival (Fisher's exact test, P = 0.007 and P = 0.001, respectively). Teeth with DPI scores ≥ 6 were more likely to be extracted than teeth with DPI score < 6 (18.8% vs. 3.9%) (Fisher's exact test, P = 0.045). CONCLUSION: Teeth with <30% of remaining tooth structure were associated with a survival rate above 80% and teeth with more than 30% of residual tooth structure survived in more than 94% of the cases. The radiographic outcome of root canal treatment can also help to predict tooth survival with teeth having an unfavourable outcome at 1 year more likely to be extracted within 4 years of completion of treatment. The DPI score can potentially be used to identify teeth with failed root canal treatment, which are likely to be extracted following retreatment and cuspal coverage.

Validation of the effectiveness of the Dental Practicality Index in predicting the outcome of root canal retreatments.

AIM: To assess the effectiveness of the Dental Practicality Index (DPI) in predicting the outcome of root canal retreatment in posterior teeth. METHODOLOGY: One hundred and thirty-seven posterior teeth with symptoms and/or signs of post-treatment endodontic disease requiring root canal retreatment and previously included in a clinical trial were selected. Clinical and radiographic examinations including digital periapical and cone beam computed tomography (CBCT) were obtained pre-treatment and 1-year postoperatively from a previous study. Two calibrated and trained assessors who were unaware of the treatment outcome assessed the pre-treatment clinical records of these cases using the DPI. The DPI score was then compared to the outcome of the root canal retreatment. A Chi-square/Fisher's exact test was used to establish a relationship between categorical variables, the total score of DPI vs outcome. RESULTS: Retreated teeth with DPI scores equal to 6 or above had an unfavourable outcome of 50% vs 14% of teeth with DPI below 6. Teeth with DPI score equal to 3 or above had an unfavourable outcome of 23% versus 2%, for teeth below 3. Molar teeth with a DPI score below 3 had a favourable outcome percentage of 96%. CONCLUSIONS: This study highlighted that using the DPI gave a good outcome prediction for root canal retreatments. However, further research, including the prospective assessment of a wider range of cases undertaken by a larger group of examiners is needed to further validate the DPI.

Pooled analysis of 1-year recall data from three root canal treatment outcome studies undertaken using cone beam computed tomography.

AIM: To provide an estimate of the proportion of successful outcomes of primary and secondary root canal treatments (retreatments) determined by periapical radiographs and cone beam computed tomography (CBCT), a pooled analysis of the data collected from three previous prospective clinical outcome studies was undertaken. METHODOLOGY: The analysis pooled the 1-year results for 354 teeth, including 123 primary treatments and 231 retreatments. All root canals were instrumented with ProTaper Universal and filled using a warm vertical condensation technique. Comparisons of favourable results between root canal treatments and retreatments and between different tooth types were made using chi-square/Fisher's exact test. RESULTS: The overall percentage of favourable results was 91% using periapical radiographs and 80% for CBCT (P < 0.001). With CBCT, the percentage of favourable results for primary treatments (84.7%) was not significantly different (P = 0.316) from that of retreatments (77.9%). When assessed by tooth group, the overall percentage of favourable results with CBCT was 75.5%, 90.6% and 91.1% for molar, premolar and anterior teeth, respectively. When CBCT is used to assess the outcome, the proportion of favourable outcomes in molars was significantly lower than that of premolars and anterior teeth (P < 0.05). Teeth with root fillings terminating more than 2 mm short of the radiographic apex had less favourable outcomes (73%) compared to long (83%) and adequate root filling length (84%). CONCLUSIONS: The proportions of favourable outcomes of primary root canal treatments and retreatments assessed with CBCT were lower when compared to periapical radiographs, and also lower than those historically reported by periapical radiograph-based outcome studies. Considering the very high favourable outcome of anterior teeth and premolars compared to molar teeth, future studies assessing the effect of new materials and techniques on the outcome of root canal treatments should be based on preoperative and postoperative CBCT images, and focus on molar teeth.

A prospective study assessing the effect of coronal tooth structure loss on the outcome of root canal retreatment.

AIM: To evaluate the outcome of secondary root canal treatment (retreatment) on posterior teeth in relation to the residual volume of coronal tooth structure, measured with an intraoral scanner, using periapical radiography and cone beam computed tomography (CBCT). METHODOLOGY: A total of 137 posterior teeth in 121 patients were assessed clinically and radiographically using periapical radiographs and CBCT scans at baseline and 1 year after root canal retreatment. The increase or decrease in the size of preoperative periapical radiolucencies and development of new radiolucencies were assessed by a consensus panel consisting of two pre-calibrated examiners. A clinical impression was obtained for each tooth after completion of root canal retreatment, before the placement of the temporary restoration and following cast restoration placement to produce two casts. All casts were scanned using an intraoral digital scanner and the three-dimensional volume of remaining tooth structure calculated. Teeth were also classified according to the number of remaining coronal walls before core build-up. χ2 test was used to determine the association between the outcome of root canal retreatments and the volume of remaining coronal tooth structure. RESULTS: At the 1-year recall, teeth retaining less than 30% of their original tooth structure volume had a significantly higher proportion of unfavourable outcomes (χ2 , P < 0.05, odds ratio [OR], 2.58; 95% CI, 1.026-6.487). CONCLUSIONS: The loss of tooth structure volume is an objective parameter that can be used to predict the probability of success of root canal retreatments. At 1-year follow-up, the percentage of unfavourable outcomes of root canal retreated teeth was significantly higher when less than 30% of the original tooth tissue structure was present at baseline.

The detection of simulated periapical lesions in human dry mandibles with cone-beam computed tomography: a dose reduction study.

AIM: To assess in an ex vivo model the accuracy of detection of simulated periapical lesions using two cone-beam computed tomography (CBCT) dose modes and periapical radiography. METHODOLOGY: Small and large artificial periapical lesions were created with burs at the base of the socket of eleven mandibular molars, in seven human dry mandibles. Digital periapical radiographs, 360° and 180° rotations CBCT scans with standard dose and dose reduction (DR) modes were obtained before and after periapical lesions were prepared. Six blinded examiners scored the presence/absence of lesions. Inter- and intra-examiner reliability were determined. Sensitivity, specificity, positive predictive values and negative predictive values and receiver operating characteristic (ROC) area under the curve (overall accuracy) were determined for each modality. RESULTS: The mean sensitivity and specificity of both CBCT rotations with dose reduction mode were higher compared to that of standard dose CBCT scans. The ROC Az mean values for periapical radiographs, 360° scan with standard dose and dose reduction and 180° scans with standard dose and dose reduction were 0.62, 0.94, 0.95, 0.95 and 0.97, respectively. No significant difference in the diagnostic accuracy of CBCT scans taken with standard and dose reduction modes, whilst their accuracy was significantly higher than periapical radiographs. CONCLUSIONS: Using dose reduction with 360° and 180° CBCT scans demonstrated good diagnostic accuracy in the detection of simulated periapical lesions whilst reducing the radiation dose by 54% and 51%, respectively, compared to conventional settings. Clinical evaluation is now needed to determine whether this is applicable to patients.

Human papillomavirus vaccination uptake and factors related to uptake in a traditional desert city in the United Arab Emirates.

It is important to assess uptake of a new vaccine. The present survey estimated the uptake of the recently introduced human papillomavirus vaccine (HPVV) in the emirate of Abu Dhabi and also explored barriers to uptake. A questionnaire survey was conducted in secondary schools, enrolling 334 girls. The uptake percentage was estimated and factors associated with uptake were assessed with multilevel logistic regression. Crude vaccination uptake was 53%. Factors positively associated with uptake were, among others, having knowledge on human papillomavirus (vaccine) and having United Arab Emirates (UAE) nationality. The HPVV uptake of just over 50% could probably be improved by educating the target group and their parents before offering the HPVV and by making it free of costs for everyone.

Purification of the cytoplasmic oestrogen receptor from mammary tumours induced in rats with dimethylbenzanthracene.

The oestrogen receptor from mammary tumours induced in rats by dimethylbenz(a)-anthracene has been extensively purified by affinity chromatography and isoelectric focusing. The unpurified cytoplasmic 8 S oestrogen receptor had a molecular weight of 240,000, a Stokes radius of 5.4 nm and a frictional ratio of 1.32; the Km (dissociation constant) at 4 degrees C for [3H]oestradiol-17 beta was 0.184 nmol/l. At the end of affinity chromatography the molecular weight was still 240,000 but under the conditions of isoelectric focusing it was reduced to 110,000, with a Stokes radius of 4.0 nm, a frictional ratio of 1.26 and an isoelectric point of 6.4.