https://www.selleckchem.com/products/sodium-l-ascorbyl-2-phosphate.html Introduction The aim of this investigation was to evaluate the effect of the presence and preparation of middle mesial (MM) canals on the fracture resistance of the mesial root of mandibular molars. Methods Forty intact mesial roots of mandibular first molars having two (n=20) or three (n=20) independent canals from the furcation level for up to at least 5 mm apically were selected based on preoperative micro-CT scanning. The selected roots were then distributed into two experimental (n=10) and two control groups (n=10), according to root length, canal configuration (2 or 3 independent canals), and root thickness at the furcation level. In the experimental groups 1 (2 independent canals) and 3 (3 independent canals), root canals were enlarged up to ProTaper Next X3 rotary instrument, while in groups 2 (2 independent canals) and 4 (3 independent canals) root canals were not prepared. The specimens were embedded in acrylic resin after their surfaces were coated with a thin layer of silicone and subjected to fraIntroduction This study compared the main clinical, radiographic and histologic features of true and bay apical cysts. Methods The material comprised 95 biopsy specimens of apical periodontitis lesions obtained attached to the root tip of both untreated and root canal-treated teeth. Clinical and radiographic data were recorded. Specimens were obtained by extraction or periradicular surgery and were meticulously processed for histopathologic and histobacteriologic methods. All cases diagnosed as apical cysts (n=23) were divided into the true and bay types, which were then compared for tooth location, patient's gender, lesion size, severity of clinical symptoms, presence of sinus tract, previous abscess episodes, and prevalence of bacteria in the main root canal lumen and ramifications, on the outer root surface, and within the cyst cavity. Results Eleven specimens were classified as true (48%