The main objective is to evaluate the way to graft the dental pulp stem cells (DPSC) in periodontal defects that best regenerate periodontal tissues. Numerous procedures have been done to promote periodontal regeneration. Bone grafts show good gains clinically and radiographically but histologically seem to have minimal osteoinductive capacity. Another option that exceeds conventional surgery in reducing probing depth and increasing insertion is guided tissue regeneration and tissue engineering that could be an alternative approach to help in the regeneration of living functional bone and peri-dental structures. A search was carried out in Cochrane, PubMed-MEDLINE and Scopus databases with keywords: "dental pulp stem cells", "periodontal regeneration", "guided tissue regeneration, periodontal", "tissue regeneration", "periodontal bone defects", "periodontal tissue engineering" and "periodontal defect". Inclusion criteria were articles in English, maximum 10 years old, in which DPSC were used to regenerate a periodontal defect. Exclusion criteria were studies not published in English, case reports, case series, literature reviews, and studies in which periodontal defect was caused by dental extraction. Out of the 185 articles identified, 101 after excluding duplicates, of which 94 were discarded when reading the title and 7 articles were obtained for the full text reading: a case report and a case series were eliminated. The systematic review is performed with 5 animal testing studies in vivo. The DPSC sheets regenerate a greater amount of bone than the injection. If HGF (hepatocyte growth factor) is added, the maximum bone volume regenerated (69.3 ± 3.9 mm3; p<0.01) is achieved. Similar results were obtained in all carriers tested except in the controls. The periodontal ligament stem cells (PDLSC) formed more new bone, compared to DPSC (p<0.001). The presence of new cementum and periodontal ligament induced by CMLPs, was detected histologically but DPSC cannot achieve it alone. Cementum or PDL regeneration does not depend only on DPSC but on other unknown factors. PDLSC has better periodontal regeneration than DPSC. DPSC significantly favours the regeneration of periodontal bone tissue but has few advantages over other grafts. It is necessary to study which growth factors or matrices can enhance their capacity for periodontal regeneration. Key words:Dental pulp, stem cells, periodontal guided tissue regeneration, periodontal bone loss.

Implantoplasty is a mechanical decontamination technique that consists of polishing the supra-osseous component of the dental implant with peri-implantitis. This technique releases metal particles in the form of metal swarf and dust into the peri-implant environment. In the present in vitro study, the following physicochemical characterization tests were carried out: specific surface area, granulometry, contact angle, crystalline structure, morphology, and ion release. Besides, cytotoxicity was in turn evaluated by determining the fibroblastic and osteoblastic cell viability. As a result, the metal debris obtained by implantoplasty presented an equivalent diameter value of 159 µm (range 6–1850 µm) and a specific surface area of 0.3 m²/g on average. The particle had a plate-like shape of different sizes. The release of vanadium ions in Hank’s solution at 37 °C showed no signs of stabilization and was greater than that of titanium and aluminum ions, which means that the alloy suffers from a degradation. The particles exhibited cytotoxic effects upon human osteoblastic and fibroblastic cells in the whole extract. In conclusion, metal debris released by implantoplasty showed different sizes, surface structures and shapes. Vanadium ion levels were higher than that those of the other metal ions, and cell viability assays showed that these particles produce a significant loss of cytocompatibility on osteoblasts and fibroblasts, which means that the main cells of the peri-implant tissues might be injured.

In the field of implant dentistry there are several mechanisms by which metal particles can be released into the peri-implant tissues, such as implant insertion, corrosion, wear, or surface decontamination techniques. The aim of this study was to evaluate the corrosion behavior of Ti6Al4V particles released during implantoplasty of dental implants treated due to periimplantitis. A standardized protocol was used to obtain metal particles produced during polishing the surface of Ti6Al4V dental implants. Physicochemical and biological characterization of the particles were described in Part I, while the mechanical properties and corrosion behavior have been studied in this study. Mechanical properties were determined by means of nanoindentation and X-ray diffraction. Corrosion resistance was evaluated by electrochemical testing in an artificial saliva medium. Corrosion parameters such as critical current density (icr), corrosion potential (E_CORR), and passive current density (i_CORR) have been determined. The samples for electrochemical behavior were discs of Ti6Al4V as-received and discs with the same mechanical properties and internal stresses than the particles from implantoplasty. The discs were cold-worked at 12.5% in order to achieve the same properties (hardness, strength, plastic strain, and residual stresses). The implantoplasty particles showed a higher hardness, strength, elastic modulus, and lower strain to fracture and a compressive residual stress. Resistance to corrosion of the implantoplasty particles decreased, and surface pitting was observed. This fact is due to the increase of the residual stress on the surfaces which favor the electrochemical reactions. The values of corrosion potential can be achieved in normal conditions and produce corroded debris which could be cytotoxic and cause tattooing in the soft tissues.

Background: The objective of this study was to evaluate the accumulation of ions in blood and organs caused by titanium (Ti) metal particles in a mandibular defect in rats, together with a description of the local reaction of oral tissues to this Ti alloy debris.Methods: Twenty Sprague‐Dawley rats were randomly distributed into three groups: an experimental group with a mandibular bone defect filled with metallic debris obtained by implantoplasty; a positive control group; and a negative control group. Thirty days after surgery, the rats were euthanized and perilesional tissue surrounding the mandibular defect was removed, together with the lungs, spleen, liver, and brain. Two blood samples were collected: immediately before surgery and before euthanasia. The perilesional tissue was histologically analyzed using hematoxylin‐eosin staining, and Ti, aluminum, and vanadium ion concentrations in blood and organs were measured by TQ‐ICP‐MS. Descriptive and bivariate analyses of the data were performed.Results: All rats with implanted metal debris showed metal particles and a bone fracture callus on the osseous defect. The metal particles were surrounded by a foreign body reaction characterized by the presence of histiocytes and multinucleated giant cells (MNGCs). The experimental group had a significant higher concentration of Ti ions in all studied organs except lung tissue (p < 0.05). In addition, there were more V ions in the brain in the experimental group (p = 0.008).Conclusions: Although further studies are required to confirm the clinical relevance of these results, Ti metal particles in the jaw might increase the concentration of metal ions in vital organs and induce a foreign body reaction.

To assess the accuracy and patient reported outcome measures (PROMs) of the computer-guided "double factor" technique for treating fully edentulous patients. A proof of concept prospective study was designed. Ten consecutive patients requiring full arch dental implant supported rehabilitation in a private practice were enrolled between October 2021 and March 2022. All patients were treated by means of an All-on-four®, and implants were planned and placed according to the "double factor" technique. This technique merges the static and dynamic computer-guided surgical approach in the same surgery. The primary outcome was the accuracy of implant placement, measured by overlapping post- and pre-operative cone-beam computerized tomography with the implant planning. Additionally, PROMs and patient quality of life after surgery were evaluated using different questionnaires. Descriptive and bivariate data analyses were performed. Statistical significance was considered for p < 0.05. A total of 48 implants were placed using the "double factor" technique, and 12 full-arch immediate loading prostheses were delivered. The mean angular deviation was 3.74° (standard deviation [SD]: 2). The total linear deviation at the apex and platform of the implant was 1.25 mm (SD: 0.55) and 1.42 mm (SD: 0.64), respectively. No statistically significant differences were found between tilted and axial implants, the upper and lower jaw, or the right and left side. High self-reported satisfaction was registered, and the Oral Health Impact Profile-14 (OHIP-14) score improved postoperatively (p = 0.002). The "double factor" technique is a valid and accurate treatment approach for fully edentulous patients. The double factor technique merges the advantages of both the dynamic and static computer assisted surgery approaches, affording accurate and predictable results when treating fully edentulous patients in a minimally invasive manner.

Oral implant rehabilitation should be considered a treatment option for any edentulous patient and Implant Dentistry is currently a discipline taught in the undergraduate formation. The level of knowledge acquired and how the students perceive the quality of training in Implant Dentistry could assess to know if it is necessary to improve the syllabus. A questionnaire was developed with 11 questions: Basic knowledge (7); Perception of training received (2); Ways in which students would receive training (2). To be responded anonymously and voluntarily for undergraduates students in the Faculty of Dentistry (University of Barcelona, Spain). One hundred and seven students, 76 third year (Group A) and 31 fourth year (Group B) answered the questionnaire. In Group A, 98.68% of students and in Group B 93.54% believed they were poorly informed; 100% of both groups would prefer to receive more training as part of the degree or as postgraduate training through modular courses imparted by experts (A: 71,05%, B: 70,96%) Training through postgraduate programs or training given by private businesses were the least desirable options (A: 42%, B: 64.51%). Questions about basic knowledge acquired received varying responses, which might indicate a certain level of confusion in this area. The undergraduate syllabus must be revised to include sufficient content and training to allow the student to indicate implant-based treatments based on evidence. Students would prefer training to be included in the undergraduate syllabus. Key words:Dental implants, dental students, dental education, dental syllabus, implant dentistry.