The Effect of Number of Visits, Use of Solvent and Gutta-percha Removal Technique on Postoperative Pain following Nonsurgical Endodontic Retreatment; A Systematic Review and Meta-analysis.

Introduction: The nonsurgical endodontic retreatment (NERT) is the first choice of dental ministration when primary/initial endodontic treatment fails. The present study aimed to investigate the presence of postoperative pain (POP) after NERT in permanent asymptomatic teeth as well as possible factors associated with POP. Materials and Methods: A comprehensive search of literature was performed in Pubmed/MEDLINE, Embase, Scopus and Web of Science databases, up to January 2023; including randomized clinical trials and prospective studies. The risk of bias was assessed with RoB 2.0 and ROBINS-I tools. Subgroups analyses were conducted to evaluate the differences in the incidence or level of POP between the number of visits, the use/not use of solvent, the removal technique of gutta-percha, and the period of POP analysis. Mean differences and confidence intervals (CI) of 95% were used as measures of effect, and meta-regression was used along with subgroup analysis. The certainty of evidence was assessed using GRADE, and the probability value of <0.05 was considered significant. Results: Twenty-four studies were selected, with thirteen included in the meta-analysis. There was a statistical difference between the incidence of POP after 24 h (95% CI, 0.28 to 0.52) and one week (95% CI, 0.02 to 0.13) from the endodontic retreatment (P<0.01). However, there was no statistical difference between different techniques, number of visits and use of solvent (P>0.05) in the same period. In addition, the certainty of evidence was very low. Conclusions: Post-operative pain is a common response to NERT, independent of the retreatment technique(s) applied, number of visits and use of solvent(s); with very low certainty of evidence as well as low risk of bias. Moreover, the current analysis showed a (very) serious risk of inconsistency and imprecision. However, POP was significantly reduced within 1 week of the NERT.

Violet led dental whitening: Effectiveness and biological safety: An in vitro study.

INTRODUCTION: The light-emitting diode (Led) in the violet spectrum associated or not with hydrogen peroxide (HP) has been suggested as a promising technique for dental bleaching. Violet led has a wavelength of 405-410 nm, which is very close to that of ultraviolet (UV) radiation, and this has raised biological safety concerns. AIM: To investigate the effectiveness of the violet led dental bleaching technique by evaluating color parameters, enamel surface microhardness, and biological safety analysis. METHODS: One hundred bovine dental blocks were divided into groups according to the bleaching technique (G1 - only HP; G2 - HP associated with blue led; G3 - only blue led; G4 - HP associated with a violet led; and G5 - only violet led). The color analysis (ΔE, ΔL, and WID) and enamel surface microhardness were assessed before and after bleaching (immediately, 5, 14, and 30 days). The biological safety of the violet led irradiation was assessed by measuring the number of micronuclei formed in human cells in culture in response to irradiation. Data analysis included Kruskal-Wallis test, Friedman test, and Mann-Whitney test. RESULTS: In groups G4 and G5 there was the formation of precipitates on the enamel surface. At the time of 14 days, it was observed that the G2 group had lower values of microhardness than G5. ΔL and ΔE showed differences between groups in experimental times. Mean percentages of micronuclei occurrence were similar in the control group and the violet led group. CONCLUSION: The violet led irradiation can be applied for dental bleaching because this approach produces significant color changes preserving tooth enamel integrity and causes no genotoxic effects on vital cells.

Pro-angiogenic potential of a functionalized hydrogel scaffold as a secretome delivery platform: An innovative strategy for cell homing-based dental pulp tissue engineering.

Angiogenesis is a key process that provides a suitable environment for successful tissue engineering and is even more crucial in regenerative endodontic procedures, since the root canal anatomy limits the development of a vascular network supply. Thus, sustainable and accelerated vascularization of tissue-engineered dental pulp constructs remains a major challenge in cell homing approaches. This study aimed to functionalize a chitosan hydrogel scaffold (CS) as a platform loaded with secretomes of stem cells from human exfoliated deciduous teeth (SHEDs) and evaluate its bioactive function and pro-angiogenic properties. Initially, the CS was loaded with SHED secretomes (CS-S), and the release kinetics of several trophic factors were assessed. Proliferation and chemotaxis assays were performed to analyze the effect of functionalized scaffold on stem cells from apical papilla (SCAPs) and the angiogenic potential was analyzed through the Matrigel tube formation assay with co-cultured of human umbilical vein endothelial cells and SCAPs. SHEDs and SCAPs expressed typical levels of mesenchymal stem cell surface markers. CS-S was able to release the trophic factors in a sustained manner, but each factor has its own release kinetics. The CS-S group showed a significantly higher proliferation rate, accelerated the chemotaxis, and higher capacity to form vascular-like structures. CS-S provided a sustained and controlled release of trophic factors, which, in turn, improved proliferation, chemotaxis and all angiogenesis parameters in the co-culture. Thus, the functionalization of chitosan scaffolds loaded with secretomes is a promising platform for cell homing-based tissue engineering.

Dental tissue-derived stem cell sheet biotechnology for periodontal tissue regeneration: A systematic review.

OBJECTIVE: This study aimed to conduct a systematic review of the use of a cell sheet formed by mesenchymal stem cells derived from dental tissues (ddMSCs) for periodontal tissue regeneration in animal models in comparison with any other type of regenerative treatment. DESIGN: PubMed and Scopus databases were searched for relevant studies up to December 2020. The review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. RESULTS: Of the 1542 potentially relevant articles initially identified, 33 fulfilled the eligibility criteria and were considered for this review. Even with a wide variety of selected study methods, the periodontal tissue was always regenerated; this indicates the potential for the use of these cell sheets in the future of periodontics. However, this regeneration process is not always complete. CONCLUSION: Despite the implantation, ddMSCs sheets have a great potential to be used in the regeneration of periodontal tissue. More in vivo studies should be conducted using standardized techniques for cell sheet implantation to obtain more robust evidence of the relevance of using this modality of cell therapy for periodontal tissue regeneration.

Effect of human dental pulp stem cell conditioned medium in the dentin-pulp complex regeneration: A pilot in vivo study.

BACKGROUND: Dental trauma, restorative operative procedures and/or caries lesions can expose the dental pulp. Facing this clinical condition, where the maintenance of the dentin-pulp complex vitality is imperative, is challenging in Dentistry. Dental pulp stem cells conditioned medium contains trophic factors that could help in this task. This in vivo pilot study aimed to evaluate the effects of the human dental pulp stem cells conditioned medium on the dental pulp tissue response to vital pulp therapy. MATERIAL AND METHODS: Concentrated conditioned medium was obtained by incubating characterized human dental pulp stem cells with fresh culture medium. Pulp exposures performed at the first upper molars (n = 20) of Wistar rats were directly capped with: MTA or MTA + Conditioned Medium. Four and 8 weeks later, the samples were qualitatively analyzed in histological sections (H&E). RESULTS: When the conditioned medium was associated with MTA, there were a high percentage of samples presenting formation of dentin bridges and small percentage of pulp tissue with inflammatory signs in both experimental times. The conditioned medium improved the organization of the newly formed hard tissue. CONCLUSIONS: The association of dental pulp stem cell conditioned medium with MTA showed beneficial effects on dentin-pulp complex regeneration and has promising potential for studies in regenerative dentistry.

Development and characterization of a new chitosan-based scaffold associated with gelatin, microparticulate dentin and genipin for endodontic regeneration.

OBJECTIVE: An ideal scaffold for endodontic regeneration should allow the predictableness of the new tissue organization and limit the negative impact of residual bacteria. Therefore, composition and functionalization of the scaffold play an important role in tissue bioengineering. The objective of this study was to assess the morphological, physicochemical, biological and antimicrobial properties of a new solid chitosan-based scaffold associated with gelatin, microparticulate dentin and genipin. METHODS: Scaffolds based on chitosan (Ch); chitosan associated with gelatin and genipin (ChGG); and chitosan associated with gelatin, microparticulate dentin and genipin (ChGDG) were prepared by using the freeze-drying method. The morphology of the scaffolds was analyzed by scanning electron microscopy (SEM). The physicochemical properties were assessed for biodegradation, swelling and total released proteins. The biological aspects of the scaffolds were assessed using human cells from the apical papilla (hCAPs). Cell morphology and adhesion to the scaffolds were evaluated by SEM, cytotoxicity and cell proliferation by MTT reduction-assay. Cell differentiation in scaffolds was assessed by using alizarin red assay. The antimicrobial effect of the scaffolds was evaluated by using the bacterial culture method, and bacterial adhesion to the scaffolds was observed by SEM. RESULTS: All the scaffolds presented porous structures. The ChCDG had more protein release, adhesion, proliferation and differentiation of hCAPs, and bacteriostatic effect on Enterococcus faecalis than Ch and ChGG (p < 0.05). SIGNIFICANCE: The chitosan associated with gelatin, microparticulate dentin and genipin has morphological, physicochemical, biological and antibacterial characteristics suitable for their potential use as scaffold in regenerative endodontics.

Physical and Biological Properties of a Chitosan Hydrogel Scaffold Associated to Photobiomodulation Therapy for Dental Pulp Regeneration: An In Vitro and In Vivo Study.

BACKGROUND: The regeneration of dental pulp, especially in cases of pulp death of immature teeth, is the goal of the regenerative endodontic procedures (REPs) that are based on tissue engineering principles, consisting of stem cells, growth factors, and scaffolds. Photobiomodulation therapy (PBMT) showed to improve dental pulp regeneration through cell homing approaches in preclinical studies and has been proposed as the fourth element of tissue engineering. However, when a blood clot was used as a scaffold in one of these previous studies, only 30% of success was achieved. The authors pointed out the instability of the blood clot as the regeneration shortcoming. Then, to circumvent this problem, a new scaffold was developed to be applied with the blood clot. The hypothesis of the present study was that an experimental injectable chitosan hydrogel would facilitate the three-dimensional spatial organization of endogenous stem cells in dental pulp regeneration with no interference on the positive influence of PBMT. METHODS: For the in vitro analysis, stem cells from the apical papilla (SCAPs) were characterized by flow cytometry and applied in the chitosan scaffold for evaluating adhesion, migration, and proliferation. For the in vivo analysis, the chitosan scaffold was applied in a rodent orthotopic dental pulp regeneration model under the influence of PBMT (660 nm; power output of 20 mW, beam area of 0.028 cm2, and energy density of 5 J/cm2). RESULTS: The scaffold tested in this study allowed significantly higher viability, proliferation, and migration of SCAPs in vitro when PBMT was applied, especially with the energy density of 5 J/cm2. These results were in consonance to those of the in vivo data, where pulp-like tissue formation was observed inside the root canal. CONCLUSION: Chitosan hydrogel when applied with a blood clot and PBMT could in the future improve previous results of dental pulp regeneration through cell homing approaches.

Preparation, Antimicrobial Properties, and Cytotoxicity of Acrylic Resins Containing Poly(diallyldimethylammonium chloride).

PURPOSE: To design and analyze the biologic properties (antibacterial and antifungal, as well as cytotoxicity) of a dental biomaterial based on incorporation of the biocide poly(diallyldimethylammonium chloride) (PDADMAC) into the masses of self- and thermopolymerizable acrylic resins. MATERIALS AND METHODS: PDADMAC was diluted into tetrahydrofuran (4 wt%) and incorporated into self- and thermopolymerizable acrylic resins. PDADMAC inclusion was verified by measuring the contact angle with water droplets. Plain resins were used as controls. The antibacterial activity was evaluated against Staphylococcus aureus (ATCC 6538P) and Escherichia coli (ATCC 8739), and the antifungal activity was tested against Candida albicans (ATCC 10231) and Aspergillus niger (ATCC 16404). The cytotoxicity of substances leached from these materials was analyzed in human dental pulp stem cells using MTT reduction assay. RESULTS: Reduction of contact angle confirmed the incorporation of PDADMAC in the resins. Both resins containing PDADMAC were more effective against Gram-positive and Gram-negative bacteria than their controls. The modified resins were also significantly more effective against Candida albicans than controls, but no resin was effective against Aspergillus niger. The cell viability of cultures submitted to substances leached from the PDADMAC resins was similar to that of cells cultured under ideal conditions. CONCLUSION: The incorporation of PDADMAC into the acrylic resins achieved the desired antibacterial effect, with no changes in the biocompatibility properties of the resins. Moreover, the modified resins were effective against Candida albicans, the most common fungus in the oral cavity. Thus, the incorporation of PDADMAC in biomaterials seems to be promising in dentistry.

Knowledge, attitudes, and practices of undergraduate students concerning Regenerative Endodontics.

BACKGROUND: Knowledge, attitudes, and beliefs of the students are important for the Tissue Engineering in Endodontic practice. The opinion of these future dentists would ultimately will decide the endurance of REPs as routine procedures in endodontic practice. The aim of this study was to perform a survey to identify the knowledge, attitudes, and practices of undergraduate students about regenerative endodontic procedures (REPs). METHODS: The questionnaire was obtained after cross-cultural adaptation of a questionnaire previously applied in USA and was applied to two hundred forty-eight undergraduates. Data were statistically analyzed. RESULTS: Most of the students (82.9%) agreed that regenerative therapy should be incorporated to dentistry and 87.5% of them believed that stem cells banks would be useful for the tissue regeneration. Most participants (58.1%) would like to obtain an internship/tutoring that addresses REPs and 80.8% of participants think that the major obstacle to a patient accepting a REP was the expected high cost of the treatment. The freshmen students were more optimistic about offering stem cell treatments to their patients (P≤0.05). CONCLUSIONS: The undergraduates were very optimistic about the future of REPs, stem cell banking, and tissue engineering. Although seniors demonstrated less enthusiasm towards REPs than the freshman, most students are willing to recommend these treatments to their patients.

Efeito da associação de meio condicionado por células tronco de polpa dentária humana e MTA ProRoot no reparo de polpas expostas de ratos / Effect of the association of human dental pulp stem cells conditioned medium and MTA ProRoot in the repair of exposed rat pulps

As células-tronco são capazes de secretar, no meio em que são cultivadas, fatores tróficos importantes para a regeneração tecidual. Estudos já revelaram que o meio condicionado (MC) por células-tronco da polpa dentária humana (hDPSCs) pode desencadear respostas angiogênicas e de modulação da inflamação que podem ser importantes no processo de reparo. O objetivo desse trabalho foi avaliar o efeito da associação do MC pelas hDPSCs (MC-hDPSCs) e do MTA ProRoot no capeamento pulpar direto em ratos. Para isso, foram utilizados ratos da linhagem Wistar divididos em 5 grupos experimentais: CT (controle negativo; sem material capeador); BD (controle positivo; Biodentine); MTA (MTA ProRoot); MC (MC-hDPSC); e MTA+ (MTA ProRoot + MC-hDPSC). As hDPSCs foram descongeladas, recaracterizadas imunofenotipicamente através de citometria de fluxo e cultivadas até P4. Quando observada a subconfluência, as células foram incubadas com meio clonogênico fresco sem suplementação. Após 24h, esse meio foi coletado e centrifugado para obtenção do MC-hDPSC concentrado. Cavidades classe I foram preparadas na oclusal dos dois primeiros molares superiores de cada animal e uma pequena exposição pulpar padronizada foi realizada. O procedimento de capeamento pulpar foi realizado de acordo com cada grupo e, então, as cavidades foram seladas. Os animais foram sacrificados após 4 e 8 semanas (n=6 dentes por grupo e tempo experimental) e as peças foram preparadas para análise histológica. Os seguintes quesitos foram avaliados: formação de dentina reparadora, grau de cobertura das pontes formadas, vitalidade e condição do tecido pulpar. As células apresentaram perfil imunofenotípico de hDPSC. O grupo CT demonstrou 33,3% e 25% de formação de ponte dentinária nos tempos experimentais de 4 e 8 semanas, respectivamente. Essas pontes foram sempre incompletas e o tecido pulpar apresentou vitalidade somente em 33,3% das amostras em 4 semanas. O grupo MC apresentou formação de ponte em 100% das amostras em 4 semanas e em 60% das amostras em 8 semanas. Houve vitalidade pulpar em 100% das amostras em 4 semanas, mas essa taxa caiu para 20% em 8 semanas. Os grupos BD e MTA+ apresentaram formação de ponte em 100% das amostras nos dois tempos, enquanto o grupo MTA não foi capaz de formar pontes em 40% e 20% das amostras em 4 e 8 semanas, respectivamente. Ainda, dentina reparadora apresentando túbulos dentinários foi observada em algumas amostras apenas dos grupos MTA+ e BD. Todas as amostras (100%) apresentaram vitalidade pulpar para esses 3 grupos em 4 semanas. Quanto a condição do tecido pulpar vital, para BD, MTA e MTA+ houve maior porcentagem de tecido livre de inflamação no tempo de 8 semanas, se comparado ao de 4 semanas. MTA+ apresentou maiores taxas de tecido com ausência de sinais inflamatórios se comparado ao MTA isolado, sendo essas porcentagens de 75% para o grupo MTA+ e 25% para MTA em 8 semanas. O MChDPSC associado ao MTA demonstrou melhorias no desempenho da formação de ponte dentinária, organização do tecido neoformado e modulação da resposta inflamatória e parece demonstrar potencial promissor para aplicação em procedimentos capeadores.

Cell sheets of human dental pulp stem cells for future application in bone replacement.

OBJECTIVES: To analyze the potential of human dental pulp stem cells (hDPSCs) for maintaining their undifferentiated status and osteogenic differentiation capacity when arranged in cell sheets (CSs) for future application in bone replacement. MATERIALS AND METHODS: CSs were formed after being induced for 10-15 days by clonogenic medium containing additional vitamin C (20 µg/ml). The cell viability of hDPSC4s in the CSs was followed until 96 h using the Live/Dead® assay. The cells of the CSs were enzymatically dissociated and then compared with the original hDPSC4s. The two cell types were characterized immunophenotypically by flow cytometry using specific mesenchymal stem cell-associated markers (CD105, CD146, CD44, STRO-1, and OCT3/4) and non-associated markers (CD34, CD45, and CD14). Osteogenic differentiation was analyzed with the Alizarin red assay. RESULTS: Living cells were observed until 96 h in the CSs. Both cell types exhibited osteogenic differentiation and expressed the specific undifferentiated MSC-associated markers. Cells spontaneously detached from the CSs attached and proliferated at the bottom of the culture dishes. CONCLUSIONS: Cells in the hDPSC4s cell sheets survived for at least 96 h. Moreover, the cells in the cell sheets retained their stemness and their osteogenic differentiation potential. CLINICAL RELEVANCE: Cell sheets of hDPSCs could be employed as natural tri-dimensional structures for treating bone loss. This technique would be useful particularly for critical bone defects or any type of bone defects in patients carrying diseases that impair bone regeneration, such as diabetes mellitus, medication-related osteonecrosis of the jaw (MRONJ), and osteoporosis.