Impact of Finishing and Polishing Procedures on CAD/CAM In Vitro Milled Ceramics Surfaces: A Systematic Review.

INTRODUCTION AND OBJECTIVES: CAD/CAM prostheses may be produced in prosthetic laboratories or directly by practitioners. Quality of ceramic polishing procedures is a controversial topic and it would be interesting for practitioners working with CAD/CAM devices to determine which method is the most efficient regarding finishing and polishing. This systematic review aims to evaluate the impact of different finishing and polishing procedures on the surface of milled ceramics. MATERIALS AND METHODS: A precise request was launched on the PubMed database. Studies included if they met the criteria of a specifically prepared PICO search. A first selection was performed by analysing titles and abstracts: the articles presenting a study conducted on non-CAD/CAM milled ceramics and research not containing comparisons of finishing procedures were not included. Roughness was evaluated in 15 articles. Nine papers recommended mechanical polishing over glazing regardless of the type of ceramic used. However, no significant differences were detected between the surface roughness of glazed and polished ceramics in nine other publications. CONCLUSIONS: there is no scientific evidence demonstrating the superiority of hand polishing over glazing on CAD/CAM-milled ceramics.

Root and canal morphology of the permanent teeth in medieval and current French population.

OBJECTIVE: This work describes and compares the root and root canal morphology of a medieval population dating from the 8th to 10th century from the southwest of France, and a current French population. DESIGN: The root morphology of 579 teeth from 70 medieval individuals was analyzed using cone beam computed tomography, and compared with 690 teeth from a current French population of 329 individuals. The Vertucci classification was used to describe the root canal configuration. RESULTS: In the medieval population, the maxillary first premolar usually had one root. In contrast, in the current population this tooth predominantly had two roots, and the three-root form had appeared. Mandibular canine with two roots was observed in 5.7% of cases, and in the current population this form was found in 1.6% but the difference was not significative. The greatest variability between the two populations in terms of root canal configuration was in one-rooted maxillary first and second premolars, the mandibular canines, and the distal roots of the mandibular first molars. Differences in root numbers and canal configurations of the maxillary molars investigated among the two populations were not significant. CONCLUSIONS: This study indicated that the upper first premolar of the current population tended to have more than one root, while this tooth type of the medieval group mostly appeared with only one. For the root canal configuration, studies in the upper premolars, lower canines and first molars of the current population apparently revealed a significant simplification compared with the ancient group.

Evaluation of two shaping systems and two sonic irrigation devices in removing root canal filling material from distal roots of mandibular molars assessed by micro CT.

AIM: To compare two preparation systems and two sonic irrigation devices during the removal of root filling material from oval distal canals of extracted mandibular molars. METHODOLOGY: The distal canals in 40 extracted mandibular molars were shaped using the ProTaper Next system (Dentslpy Sirona, Ballaigues, Switzerland), filled with Gutta Percha X2 (Dentsply Sirona), along with AH Plus sealer (Dentsply De Trey, Konstanz, Germany) and randomly divided into two groups (n = 20) according to volume of initial filling, preparation diameter and working length. One group was retreated using the Reciproc system (VDW, Munich, Germany), and the other using the 2Shape system (Micro-Mega, Besançon, France). A micro-CT scan was taken after the initial root filling and after retreatment to evaluate the volume of filling material remnants. The teeth were divided into four groups to test the supplementary effect of two sonic irrigation devices on removing filling material: Eddy (VDW) and MM1500 (Micro-Mega). In the first and second groups, 2Shape was followed subsequently by MM1500 and Eddy; in the third and fourth groups, Reciproc was followed by MM1500 and Eddy. A third micro-CT was taken to compare the remaining root filling material in all groups. Wilcoxon's signed rank tests, Mann-Whitney and Kruskal-Wallis tests were used for statistical analysis. RESULTS: No significant difference was found for the volume of filling material removed between the Reciproc and 2Shape in the entire canal (P = 0.355). The volume dropped significantly from its initial value after removing the bulk of the root filling by 95.8% (from 4.71 to 0.22 mm3 ) with the 2Shape (P < 0.001) and by 94.0% (from 5.05 to 0.33 mm3 ) with the Reciproc (P < 0.001). Sonic activation significantly decreased the residual volume of filling material remnants by 3.21% (P = 0.013) in the first group, 1.38% (P = 0.012) in the second group, 1.83% (P = 0.008) in the third group and 1.83% (P = 0.012) in the fourth group. At the end, the percentage of residual material was not significantly different among the groups in the entire canal (P = 0.163). CONCLUSION: In the distal oval canals of extracted mandibular molar teeth, there was no significant difference between the 2Shape and Reciproc systems in removing gutta-percha/sealer. Sonic activation with MM1500 and Eddy significantly improved filling material removal.

Body composition measures and cardiovascular risk in high-risk ethnic groups.

BACKGROUND & AIMS: Cardiovascular disease (CVD) is highly prevalent in Suriname, a middle-income country with predominantly people of African and Asian ancestry. We examined whether the more comprehensive body composition measures determined by bioelectrical impedance analysis (BIA) are superior to the more traditional BMI and waist measures in relation to cardiovascular risk. METHODS: Data from the cross-sectional Healthy Life in Suriname (HELISUR) study were used to calculate BMI, waist-hip ratio, waist-to-height ratio, and waist circumference. BIA was used to estimate fat percentage, fat-free mass index, and fat-to-fat-free mass ratio. High cardiovascular risk was defined as 1) a 10-year Framingham coronary heart disease risk score ≥10% in African-Surinamese and ≥12% in Asian-Surinamese, and 2) an increased arterial stiffness (pulse wave velocity >10 m/s). Using logistic regression analysis, we pre-selected the strongest correlate (i.e. lowest p-value below 0.05) of all body composition items for both outcomes of cardiovascular risk separately, and subsequently, used forward logistic regression modelling to determine whether other measures added value to the initial model with the strongest correlate (-2 log-likelihood (-2LL) of initial model minus -2LL of new model, χ-square statistic >3.841, 1 df). Analyses were adjusted for sex, age and ethnicity. RESULTS: We examined 691 participants (65% women; 48% African-Surinamese) with a mean age of 42 (SD 14) years. Waist circumference was the strongest correlate for high 10-year CVD risk in the total group, in men and African-Surinamese. In Asian-Surinamese, fat-free mass index was the strongest correlate of high 10-year CVD risk. Increased arterial stiffness was most strongly related with waist-to-height ratio in the total group and in African-Surinamese, and with BMI in men. None of the measures were significantly associated in women (for both outcomes) and Asian-Surinamese (for increased arterial stiffness). Forward selection showed that only BMI added value next to waist-to-height ratio in the total group in relation to increased arterial stiffness. CONCLUSIONS: Waist measures, in particular waist circumference and waist-to-height ratio, and BMI should be used in African and Asian-Surinamese to identify who is at increased cardiovascular risk. Overall, we found little advantage in using BIA measures rather than simple anthropometric measures.

Arsenic trioxide-induced osteo-necrosis treatment in a child: mini-review and case report.

BACKGROUND: Arsenic oxide compounds were traditionally used as devitalizing agents. Due to its toxicity, leakage of such compounds into the periodontium can cause gingival and osteo-necrosis. Their use is forbidden in Europe and the USA for decades, however, some dentists seem to still use it. CASE REPORT: We report the case of a 14-year-old girl referred to the paediatric dentistry department of Toulouse University hospital, France, presenting a bone necrosis following the use of an arsenic trioxide product to accelerate pulp necrosis. TREATMENT: The treatment included surgical removal of necrosis bone sequestrum, complete pulpectomy and an intermediate restoration of the tooth 27. FOLLOW-UP: After 1 week, the clinical conditions greatly improved. A restoration using a ceramic crown was performed after 2 months, and complete healing was observed after 1 year follow-up. CONCLUSION: Although arsenic trioxide is neither appropriate nor permitted for use in modern dentistry, especially in paediatric dentistry, some rare cases of arsenic-induced osteo-necrosis can still be encountered. A clearer message must be given to all dental practitioners against the use of arsenic trioxide in modern endodontic treatment.

Influence of cone beam CT parameters on the output of an automatic edge-detection based endodontic segmentation.

OBJECTIVES: To determine the optimal cone beam computed tomography settings for an automatic edge-detection based endodontic segmentation procedure by assessing the accuracy of the root canal measurements. METHODS: Twelve intact teeth with closed apexes were cut perpendicular to the root axis, at predetermined levels to the reference plane (first section made before acquisition). Acquisitions of each specimen were performed with the "9000 3D®" (76µm, 14 bits) by using different combinations of milliamps and kilovolts. 3 dimensional images were displayed and root canals were segmented with the MeVisLab software (edge-detection based method). Histological root canal sections were then digitized with a 0,5 to 1µm resolution and compared with equivalent 2 dimensional cone-beam reconstructions for each pair of settings using Pearson correlation coefficient, regression analysis and Bland-Altman method for the canal area and Feret's diameter. After a ranking process, a Wilcoxon paired test was done to compare the pair of settings. RESULTS: The best pair of acquisition settings was: 3.2mA/60kV. Significant differences were found between 3.2mA/60kV and other settings (p <0.05) for root canal area and for Feret's diameter. CONCLUSIONS: The quantitative analyses of the root canal system with edge-detection based method could depend on acquisition parameters. Improvements in segmentation still need to be done to ensure the quality of the reconstructions when we have to deal with closer outlines and because of the low spatial resolution.

Influence of CBCT parameters on the output of an automatic edge-detection-based endodontic segmentation.

OBJECTIVES: To determine the optimal CBCT settings for an automatic edge-detection-based endodontic segmentation procedure by assessing the accuracy of the root canal measurements. METHODS: 12 intact teeth with closed apexes were cut perpendicular to the root axis, at pre-determined levels to the reference plane (the first section made before acquisition). Acquisitions of each specimen were performed with Kodak 9000(®) 3D (76 µm, 14 bits; Kodak Carestream Health, Trophy, France) by using different combinations of milliamperes and kilovolts. Three-dimensional images were displayed and root canals were segmented with the MeVisLab software (edge-detection-based method; MeVis Research, Bremen, Germany). Histological root canal sections were then digitized with a 0.5- to 1.0-µm resolution and compared with equivalent two-dimensional cone-beam reconstructions for each pair of settings using the Pearson correlation coefficient, regression analysis and Bland-Altman method for the canal area and Feret's diameter. After a ranking process, a Wilcoxon paired test was carried out to compare the pair of settings. RESULTS: The best pair of acquisition settings was 3.2 mA/60 kV. Significant differences were found between 3.2 mA/60 kV and other settings (p < 0.05) for the root canal area and for Feret's diameter. CONCLUSIONS: The quantitative analyses of the root canal system with the edge-detection-based method could depend on acquisition parameters. Improvements in segmentation still need to be carried out to ensure the quality of the reconstructions when we have to deal with closer outlines and because of the low spatial resolution.

Evaluation of the preparation of the coronal part of the mesial canals of lower molars.

Canal entrances can be flared using specific, low speed, continuously rotating Ni-Ti instruments. Two such instruments were evaluated for their capacity to flare the canal entrance while respecting the initial canal axis. Lower molars (n = 20) with two distinct mesial canals were prepared to within 2.5 mm of the pulp chamber floor using Bramante's technique. Canal entrances were flared with a QUANTEC FLARE LX or an ENDOFLARE. They both had a 0.12 taper and a #25 tip diameter. The instruments were first inserted in the canals using an axial movement and then withdrawn with a selective circumferential brushing action. Photographs taken before and after each preparation were compared. No ledging or significant modification of the working length was noted. The centre of mass was displaced on average by 0.138 mm with no brushing action and 0.274 mm with brushing action. In most cases (87.5%), the centre of mass was displaced mesially. The two instruments behaved in an identical mode, both before (p = 0.3497) and after (p = 0.9304) the brushing action. Ni-Ti flaring instruments can be used to flare the canal entrance with little displacement of the initial canal axis, even when a brushing action is used.