Identification of degenerated synaptic boutons in the dorsal claustrum of the cat after electrolytic lesions of the intralaminar thalamic nuclei.

The aim of this study is to investigate whether the dorsal claustrum receives afferent input from the intralaminar thalamic nuclei - centromedian nucleus, central lateral nucleus and paracentral nucleus. The intralaminar thalamic nuclei of eight cats were electrolytically lesioned. We obtained samples from the dorsal claustrum for electron microscopic analysis from the second to the seventh post-procedural day. Two types of degenerated synaptic boutons were observed: electron-dense which formed the majority of boutons, and electron-lucent comprising the remaining samples. Between the second and seventh post-procedural day, we observed a steady increase in the number of electron-dense boutons which were diffusely distributed throughout the dorsal claustrum. Electron-dense degenerated boutons formed asymmetrical contacts with dendritic spines as well as with small and medium-sized dendrites. In contrast, electron-lucent degenerated boutons were observed in earlier post-procedural periods and formed symmetrical axodendritic contacts.

Efficacy of Three Irrigation Methods in Removing Calcium Hydroxide from Curved Root Canals: An In Vitro Micro-CT Study.

Aims and Objectives: This in vitro study aimed to compare the efficacy of three different irrigation methods in removing calcium hydroxide from curved root canals and to estimate the amount of residual medicament using microcomputed tomography. Materials and Methods: Thirty extracted molars with curved mesial root canals, ranging from 25° to 30°, were prepared with ProTaper Next using X2 to full working length and were filled with calcium hydroxide. Teeth also were randomly divided into four groups: group 1 (n = 8)- Erbium: Yttrium-Aluminum-Garnet (Er:YAG) laser; group 2 (n = 8)-EndoActivator; group 3 (n = 8)-EndoVac; and a control group (n = 6)-negative control with no calcium hydroxide. Microcomputed tomography was used to evaluate the residual amount of filling material. Statistical analysis was performed using IBM SPSS Statistics 26, with a significance level of 0.05. Descriptive statistics, student t test, and Chi-square test were applied for data analysis. Results: The greatest amount of residual calcium hydroxide was observed in the samples with EndoVac irrigation (0.515 mm3), followed by EndoActivator (0.381 mm3) and Er:YAG laser (0.121 mm3). However, no statistically significant difference was observed between the groups. The greatest residual amount was observed in the apical third (0.419 mm3), followed by the middle (0.050 mm3) and the coronal (0.015 mm3). Conclusions: No statistically significant differences were observed in the efficacy of the tested techniques for removing calcium hydroxide from curved root canals, whereas a significant difference was observed in the distribution of residual material depending on the technique used. The removal of the calcium hydroxide was more effective in the coronal and middle third of the canal. The greatest residual material was found in the apical portion of the root canal.

Comparative SEM study of the marginal adaptation of MTA and Biodentine after apical resection (in vitro study).

INTRODUCTION: Successful periapical surgery requires appropriate root resection, preparation, and adequate sealing. AIM: The aim of the present study was to assess the marginal adaptation of MTA and Biodentine after apical resection with an Er:YAG laser and a diamond turbine bur using a scanning electron microscope (SEM). MATERIALS AND METHODS: The crown part of forty-eight extracted single-root human teeth was removed, and the root canal length of 15 mm was standardized. The root canals were prepared using rotary Ni-Ti Revo-S files up to an apical stop - AS40 and filled with MTA Fillapex and gutta-percha points (cold lateral condensation). The teeth are divided into 2 main groups: group 1 (n=24) after apical resection with a turbine bur, ultrasonic preparation of the retrograde cavity at 3 mm depth and retrograde obturation with Biodentine and MTA; group 2 (n=24) after apical resection with an Er:YAG laser, ultrasonic preparation of the retrograde cavity at a depth of 3 mm and retrograde obturation with MTA and Biodentine. A SEM was used for assessment of the marginal adaptation of the material to the root dentin. The data was entered into and analyzed with IBM SPSS Statistics 22.0. RESULTS: In the group with apical resection with a turbine bur, a statistically significant difference in the gap size between the material and dentin was found in both materials we studied (MTA and Biodentine). The higher mean value was in MTA (1.72 µm), in Biodentine it was 1.08 µm. In the group with apical resection with Er:YAG laser, no statistically significant difference in the gap size between the material and dentin was found in both studied materials: MTA - 1.88 µm, Biodentine - 1.32 µm. CONCLUSIONS: In the present study, MTA and Biodentine showed good sealing capabilities after apical resection. Biodentine displayed better marginal adaptation when resecting the root tip using a turbine bur. The Er:YAG laser-assisted apical resection shows sealing of the open dentinal tubules around the resected root surface.