A Regenerative Endodontic Approach in Mature Ferret Teeth Using Rodent Preameloblast-conditioned Medium.

BACKGROUND: This study evaluated the effectiveness of a regenerative endodontic approach to regenerate the pulp tissue in mature teeth of ferret. The presence of odontoblast-like cells in the newly-formed tissue of teeth treated with or without preameloblast-conditioned medium was evaluated based on morphological criteria. MATERIALS AND METHODS: Twenty-four canines from six ferrets were treated. The pulp was removed, and the apical foramen was enlarged. After inducing the formation of a blood clot, a collagen sponge with or without preameloblast-conditioned medium was placed underneath the cementoenamel junction. The samples were analyzed at the eighth week of follow-up. RESULTS: Vascularized connective tissue was observed in 50% of teeth, without differences between groups. The tissue occupied the apical third of the root canals. Odontoblast-like cells were not observed in any group. CONCLUSION: Revitalization of mature teeth is possible, at least in the apical third of the root canal. Further experimental research is needed to produce more reliable outcomes.

Guided bone regeneration using beta-tricalcium phosphate with and without fibronectin-An experimental study in rats.

OBJECTIVE: This histomorphometric study compared bone regeneration potential of beta-tricalcium phosphate with fibronectin (ß-TCP-Fn) in critical-sized calvarial defects (CSDs) in rats to assess whether fibronectin (Fn) improved new bone formation. MATERIAL AND METHODS: Critical-sized calvarial defects were created in 30 adult male Sprague Dawley rats, which were divided into four groups according to the time of euthanasia (6 or 8 weeks of healing) and type of filling (ß-TCP-Fn/6 weeks, ß-TCP/6 weeks, ß-TCP-Fn/8 weeks and ß-TCP/8 weeks). The primary variables related to new bone formation were augmented area (AA) and gained tissue (GT; sum of mineralized bone matrix [MBM] and bone substitute [BS]). Secondary variables were the diameter of the defect, MBM, non-mineralized tissue (NMT) and BS. RESULTS: A total of 29 rats and 58 histological samples were evaluated, 28 (48.3%) samples obtained at 6 weeks and 30 (51.7%) at 8 weeks, homogeneously distributed between right and left sides. Thirteen (22.4%) were treated with ß-TCP-Fn, 16 (27.6%) with ß-TCP and 29 (50%) were controls. At 8 weeks, histomorphometric analysis showed significant differences in AA using ß-TCP and ß-TCP-Fn versus controls (p = 0.001 and p = 0.005, respectively). Bone turnover expressed as % within the target area was slightly higher but not statistically significant in the ß-TCP-Fn than in ß-TCP (MBM) at 6 weeks versus 8 weeks (p = 0.067 and p = 0.335, respectively). Finally, the total GT area in mm2 was higher using ß-TCP-Fn as compared to ß-TCP (p = 0.044). CONCLUSIONS: ß-TCP-Fn was slightly but non-significantly more effective than ß-TCP without Fn for improving the volume of regenerated bone in CSDs of rats, possibly allowing a more efficient bone remodelling process. This effect however should continue being investigated.

Enlargement of the apical foramen of mature teeth by instrumentation and apicoectomy. A study of effectiveness and the formation of dentinal cracks.

OBJECTIVE: In the last few years there have been attempts to revascularize mature necrotic teeth instead of performing a standard root canal treatment. Apical foramen enlargement (AFE) would be necessary for regenerative treatments of mature teeth. In the literature, AFE has been made through apicoectomy and instrumentation. However, no standardized methods have been described yet, which may affect the success of the therapy. Our aim was to describe the effectiveness and damage to dental structures of five methods for AFE. METHODS: Two hundred and ten human teeth were assigned to one control group (n = 10) and four treatment groups (n = 50 each): instrumentation was up to file #80 0.5 mm coronal to the apex (I), at apex level (II), 0.5 mm beyond the apex (III) and apicoectomy at 2 and 4 mm from the apex (IV). The apical foramen diameter was measured before and after treatment. The formation of clinically visible fractures (CVF) and microcracks was analysed clinically and with ESEM, respectively. Thirty-two in situ sheep's teeth were also instrumented, to compare damage in in situ and ex vivo teeth. RESULTS: The foramen diameter was augmented by 0.15, 0.47, 0.54 0.06 and 0.32 mm in human teeth of groups I, II, III, apicoectomy at 2 and 4 mm, respectively. CVF were more frequent as the working length was augmented. No statistical differences were found for microcrack formation. In situ teeth showed significantly less damage. CONCLUSIONS: Instrumentation at apex level seems to be the most effective and least harmful technique for AFE, while apicoectomy is not a useful method.