Influence of minimally invasive endodontic access cavities on root canal shaping and filling ability, pulp chamber cleaning and fracture resistance of extracted human mandibular incisors.

AIM: To evaluate the influence of the location and design of endodontic access cavities on root canal shaping and filling ability, pulp chamber cleaning and fracture resistance of extracted human mandibular incisors. METHODOLOGY: After pre-selection using periapical radiographs, forty extracted intact human mandibular incisors were scanned in a micro-computed tomographic device. The teeth were matched based on similar anatomical features of the canals and assigned to four experimental groups (n = 10) according to the endodontic access cavity and root canal preparation protocol: traditional/TRUShape (T/TRU); traditional/MTwo (T/MT); minimally invasive/TRUShape (MI/TRU); and minimally invasive/MTwo (MI/MT). The samples were scanned after root canal instrumentation and filling procedures. The parameters evaluated were as follows: volume and area of the root canal, noninstrumented canal areas, canal transportation and centring ratio, accumulated hard tissue debris, voids in root canal fillings and remnants of root canal filling materials in the pulp chamber. After root canal filling and cavity restoration procedures, the samples were submitted to a fracture resistance test. Data were statistically analysed using Shapiro-Wilk, one-way anova and Bonferroni tests with a significance level of 5% (α = 0.05). RESULTS: There was no difference regarding all parameters evaluated before and after root canal preparation (volume and area of the root canal, noninstrumented canal areas, canal transportation and centring ratio, and accumulated hard tissue debris) amongst the groups (P > 0.05). MI/TRU and MI/MT groups were associated with significantly more voids in root canal fillings when compared to the T/TRU and T/MT groups (P < 0.05). Percentage of root canal filling material remnants in the pulp chamber after cleaning procedures and mean fracture resistance values were not significantly different amongst the four experimental groups (P > 0.05). CONCLUSIONS: The location and design of the endodontic access cavity did not impact on root canal preparation nor resistance to fracture of extracted mandibular incisors, regardless of the instrument used. Minimally invasive access cavities were associated with significantly more voids in root canal fillings.

Effects of several storage media on viability and proliferation capacity of periodontal ligament cells.

AIM: The purpose of this study was to investigate the effect of different storage media on viability and proliferation capacity of periodontal ligament cells. METHODS: Plates with periodontal ligament fibroblasts (PDLF) cells were incubated in skimmed and whole milk, recently prepared Hank's balanced salt solution (HBSS), Save-A-Tooth system's, coconut water, propylene glycol with 20% propolis, egg white, tap water (negative control) at 5 °C and 20 °C, for 24 h. In one of the plates of each temperature, cell viability was determined by MTT assay. In the remaining plates, the wells were filled and incubated with Minimum Essential Medium (MEM) at 37 °C for 24, 48, 72, 96, and 120 h. The proliferation capacity of PDFL cells was also evaluated by MTT assay. Data were statistically analyzed by Kruskal-Wallis, Scheffé and Mann-Whitney tests (α = 5%). RESULTS: At 5 °C, milk maintained more viable cells than other storage media immediately after exposure (0 h) and allowed greater proliferation capacity. At 20 °C, milk and HBSS had similar and allowed similar proliferation ability at 24 and 48 h. From 72 h onwards, capacity to maintain cell viability the proliferation rate of cells incubated in HBSS was superior than milk. At both temperature and experiments, Save-A-Tooth system was similar to tap water. CONCLUSION: Milk and HBSS were more effective in maintaining cellular viability and proliferation capacity than any other storage media. At 5 °C, the most viable alternative was milk. At 20 °C, HBSS had better results.

Retracted: Micro-computed tomography evaluation of apical transportation and centring ability of Reciproc and WaveOne systems in severely curved root canals.

The following article from International Endodontic Journal, 'Micro-computed tomography evaluation of apical transportation and centring ability of Reciproc and WaveOne systems in severely curved root canals' by D. A. de Meireles, T. C. C. A. de Brito, A. A. F. Marques, A. D. B. Garrido, L. F. R. Garcia & E. C. Sponchiado Jr, published online on 5 February 2015 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal Editor in Chief, Prof. Paul Dummer, and John Wiley & Sons Ltd. The retraction has been agreed due to the use of techniques for crucial measurements in canal shaping and a lack of clarity regarding the measuring methodology. The use of inadequate measuring methodologies makes the findings of the paper invalid.