Bacterial colonization in the apical part of extracted human teeth following root-end resection and filling: a confocal laser scanning microscopy study.

OBJECTIVES: The purpose of this study was to evaluate Enterococcus faecalis colonization at the apical part of root canals following root-end resection and filling using confocal laser scanning microscopy (CLSM). MATERIALS AND METHODS: The apical 3-mm root-ends of 55 extracted single rooted human teeth were resected, and 3-mm retrograde cavities were prepared and filled using either mineral trioxide aggregate (MTA), intermediate restorative material (IRM), or Biodentine (n = 10 each); 25 teeth served as controls. The roots were placed in an experimental model, sterilized, and coronally filled with E. faecalis bacterial suspension for 21 days. Then, the apical 3-mm segments were cut to get two slabs (coronal and apical). The slabs were stained using LIVE/DEAD BacLight Bacterial Viability Kit and evaluated using CLSM. RESULTS: The fluorescence-stained areas were larger in the bucco-lingual directions compared with the mesio-distal directions (p < 0.05). The mean and maximal depths of bacterial colonization into the dentinal tubules were 755 and 1643 µm, respectively, with no differences between the root-end filling materials (p > 0.05). However, more live bacteria were found in the MTA group in comparison to IRM and Biodentine groups (p < 0.05). CONCLUSIONS: CLSM can be used to histologically demonstrate bacterial root-end colonization following root-end filling. This colonization at the filling-dentine interfaces and deeper into the dentinal tubules may be inhomogeneous, favoring the bucco-lingual aspects of the root. CLINICAL RELEVANCE: Following root-end resection and filling bacterial colonization may lead to inflammatory reactions at the periapical tissues; the viability of the colonized bacteria may be affected by the type of root-end filling material.

A Comparison of Cone-beam Computed Tomography with Periapical Radiography in the Detection of Separated Instruments Retained in the Apical Third of Root Canal-filled Teeth.

INTRODUCTION: This study compared the diagnostic efficacies of cone-beam computed tomographic (CBCT) imaging and periapical radiography (PR) in the detection of retained separated instruments located at the apical third of filled root canals. METHODS: Sixty single-rooted extracted human teeth were instrumented to size #25 and were randomly divided to a simulated 2-mm #30 K-file (stainless steel or nickel-titanium) segment separation at the apical third of the canal (n = 40) or a control group without a separated instrument (n = 20). The canals were obturated to the separated instrument or the working length for the teeth without an instrument using gutta-percha with AH26 (Dentsply DeTrey GmbH, Konstanz, Germany) or Roth sealer (Roth International Ltd, Chicago, IL). The teeth were invested in a mandible model simulating the bone density and imaged using CBCT imaging and PR. The images were evaluated separately by 2 calibrated observers twice with an interval of 4 weeks. Cohen kappa was used to evaluate the observer agreement. Receiver operating characteristic curve analysis was used to evaluate the discrimination ability. RESULTS: The intraobserver kappa was 0.744 and 0.627, and between the observers, it was 0.593 and 0.275 for PR and CBCT imaging, respectively. Using PR, the mean sensitivity was 71.25%, and the specificity was 93.75%. Using CBCT imaging, the sensitivity and specificity were 41.25% and 71.25%, respectively. Although for PR the area under the curve values ranged between 0.75 and 0.91 (P < .05), for CBCT they ranged between 0.48 and 0.60 (P > .05), regardless of the instrument or the sealer type. CONCLUSIONS: PR performed better than CBCT imaging for the detection of retained separated instruments located at the apical third of extracted human root canal-filled teeth.

VEGF facilitates periosteal distraction-induced osteogenesis in rabbits: a micro-computerized tomography study.

BACKGROUND AND PURPOSE: Distraction osteogenesis is routinely used for reconstruction of bone. Conversely, it was hypothesized that mechanical traction of the periosteum would induce bone formation, and hence the use of periosteal distraction for induction of osteogenesis has been proposed. Further, it was postulated that intracallus administration of vascular endothelial growth factor (VEGF) would facilitate osteogenesis. To investigate this hypothesis, formation of newly synthesized bone was evaluated using micro-computerized tomography (microCT) and histomorphometry. MATERIALS AND METHODS: Periosteal distractors were placed subperiosteally in one side of the mandible of rabbits, whereas the contralateral served as control. One group of animals received VEGF into the forming callus. Formation of bone was measured using microCT and histological analysis. RESULTS: The results demonstrate formation of new bone following periosteal distraction. Addition of VEGF to the distraction site increased bone synthesis. CONCLUSIONS: microCT and histological analysis validate the hypothesis that mechanical distraction of the periosteum induces osteogenesis and that VEGF has a positive effect on osteogenesis. Periosteal distraction is emerging as a reliable technique for bone regeneration.