Functionalized surface of PLGA nanoparticles in thermosensitive gel to enhance the efficacy of antibiotics against antibiotic resistant infections in endodontics: A randomized clinical trial.

Enterococcus faecalis plays the key role in endodontic infections and is responsible for the formation of biofilm on dentin, which causes a resistance against periradicular lesions treatment, consequently the aim of this study is to use nanoparticles entrapping anibacterial agents coated with chitosan that in authors previous study showed a successful in vitro biofilm inhibition, additionally incorporated in thermoresponsive gel.to benefit nanoparticles` small size, and the positive charge of their surfaces that binds with the negatively charged surface of bacterial cell causing its destruction, in addition to the sustained release pattern of the drug based nanoparticles in gel. Therefore, Ciprofloxacin hydrochloride (CIP) encapsulated in PLGA nanoparticles coated with chitosan (CIP-CS-PLGA-NPs), in addition to free CIP, were incorporated in Pluronic® 407/188 to form thermosensitive gels (F1) and (F2), respectively. The thermosensitive gels were tested with regards to rheology, gelling temperature and the release pattern of the drug. A clinical study of the efficacy of F1 and F2 as antibacterial treatments was conducted on patients followed by a comparative studies against CIP and Ca(OH)2 pastes in terms of biofilm inhibition assay and total bacterial reduction count and percent.The results revealed that F1 and F2 exhibited gelation temperature of 36.9 ± 0.3 °C and 36.0 ± 0.4 °C, viscosity was 15,000 ± 360.6 and 7023.3 ± 296.8 cP respectively. The cumulative release of F1 and F2 after 72 h was 50.03% ± 0.7345 and 77.98% ± 3.122 respectively. F1 was the most efficient treatment against recurrent E.faecalis infection in endodontics that was evident by the highest total bacterial reduction count and percent and biofilm inhibition percent that were recorded in the group treated with F1followed by the group treated with F2. Nanocarriers succeeded in carrying the drug deeply in the root canal and sustaining its effect to abolish the obstinate E. faecalis recurrent infection and its biofilm formation.

Efficacy of using chitosan and chitosan nanoparticles as final irrigating solutions on smear layer removal and mineral content of intraradicular dentin.

Background: This study evaluated the effect of using chitosan, nano-chitosan, and ethylenediaminetetraacetic acid (EDTA) as final irrigating solutions on smear layer cleanliness and Ca/P ratio of dentin. Methodology: Forty-eight decoronated human single-rooted teeth were used. They were divided randomly into four groups (n = 12) based on the final irrigating solution used as follows: (a) control group (IA; n = 6) normal saline, (IB; n = 6) were left unprepared; group II - 0.2% chitosan; group III - 0.2% nano-chitosan; and group IV - 17% EDTA. Samples were prepared using ProTaper Next and irrigated with 2.6% NaOCl 5 ml after each instrument using 31-gauge needle. Final rinse was used 5 ml/3 min according to the assigned group. The specimens were prepared for evaluation. Results: Best smear layer removal was observed in group IV. No statistically significant differences (P > 0.05) were observed between the experimental groups (II, III, and IV) coronally; however, a statistically significant difference (P < 0.05) was observed between groups II and IV at middle and apical thirds. Intragroup comparison showed that apical third exhibited the highest mean smear layer score among all experimental groups. The highest mean Ca/P ratio was in the 0.2% nano-chitosan group, while the highest calcium loss was in the 17% EDTA group. Conclusions: 17% EDTA is a potent chelating agent that can successfully remove the smear layer but compromises the Ca/p ratio of dentin. However, 0.2% chitosan and its nanoparticles have comparable chelating effects and induce remineralization of the root canal dentin.

Effect of Proximal Caries-driven Access on the Biomechanical Behavior of Endodontically Treated Maxillary Premolars.

INTRODUCTION: This study investigated the effects from the carious cavity and access from it on the fracture resistance of endodontically treated maxillary premolars using finite element analysis (FEA). METHODS: A maxillary premolar was used to compare 3 types of access cavity related to having a proximal carious defect: caries-driven access (CDA), conservative access that has a mesial component (MCA), as well as traditional access with the same mesial component (MTA). Cyclic loading was simulated on the occlusal surface, and number of cycles until failure (NCF) was compared with the intact tooth model (IT). Mathematical analysis was done to evaluate the stress distribution patterns and calculated maximum von Mises (vM) and maximum principal stresses (MPS), with emphasis on pericervical region as a specific area of interest. RESULTS: Maximum vM registered on the IT was 6.14 MPa. CDA provided the highest NCF with 92.28% of the IT, followed by MCA (84.90%) and MTA (83.79%). The vM and MPS analysis showed that the stress values and patterns are affected more by the proximity of the occlusal load to the tooth/restoration interface. Concerning the pericervical region, maximum vM was registered for IT (4.11 MPa), followed by CDA (4.85 MPa) and then MCA (8.13 MPa) and MTA (8.61 MPa), whereas the MPS analysis revealed that CDA showed the highest magnitude of tensile stresses. CONCLUSIONS: A proximal CDA benefits the mechanical properties of maxillary premolars; however, its impact on the biological aspect should be assessed to provide a ruling for/against it.

Biomechanical Behavior and Life Span of Maxillary Molar According to the Access Preparation and Pericervical Dentin Preservation: Finite Element Analysis.

INTRODUCTION: This study investigated the significance of pericervical dentin after coronal canal flaring on the biomechanical behavior and life span of a maxillary molar using finite element analysis (FEA). METHODS: In addition to the intact tooth (IT) model, 4 experimental FE models were designed: conservative access cavity model (CON), and 3 models with different radicular preparations for the coronal 4 mL considering 3 instruments: ProTaper SX model (SX), OneFlare model (OF), and Gates-Glidden model (GG). Cyclic loading of 50 N was applied on the occlusal surface and number of cycles until failure (NCF) was compared with the IT model. Mathematical analysis was done to evaluate the stress distribution patterns and calculated maximum von Mises (VM) and maximum principal stresses. RESULTS: Access cavity preparation (CON) decreased NCF significantly when compared with the IT model (93.99%). The coronal preparation of the root canal did not have a significant effect even when the preparation was taken to the extreme (GG: 92.02%). VM analysis confirmed apical dispersion of stresses, with maximum value registered on the occlusal surface in the GG model (7.88 MPa), and minimum on the IT model (7.01 MPa). The furcation area showed higher maximum principal stresses, yet stress values remained minimal and distributed over larger surfaces with the progressive enlargement among models. CONCLUSIONS: Within the limitations of this study, coronal canal flaring affects tooth integrity minimally, and when loading conditions lie within normal functional ranges, tooth structure has the capacity to disperse increasing stresses over a wider surface area.

Fracture resistance of root canal-treated molars restored with ceramic overlays with/without different resin composite base materials: an in vitro study.

The objective of the study was to evaluate the effect of different restorative protocols on fracture resistance of root canal-treated molars. 48 mandibular first molars were used and divided into six groups (n = 8); G1 (negative control): teeth kept intact. G2 (positive control): teeth had root canal treatment and standard MOD cavity preparations but kept unrestored. G3: prepared as G2 and directly restored with VitaEnamic ceramic overlays (CO). G4: as G3, but the pulp chamber was restored first with smart dental restorative (SureFil SDR flow = SDR) bulk-fill flowable composite base. G5: as G3, but the pulp chamber was restored first with SonicFill (SF) bulk-fill composite base. G6: as G3, but the pulp chamber was restored first with a fiber-reinforced composite (FRC) base. All samples were subjected to thermocycling between 5 °C and 55 °C in a water bath for a total of 2000 cycles with 10 s dwell time. Then specimens were individually mounted on a computer-controlled testing machine with a load cell of 5 kN, and the maximum load to produce fracture (N) was recorded. Data were analyzed using one-way ANOVA followed by Tukey's post hoc test (P = 0.05). There was a significant difference between the groups (P < 0.001). Teeth restored with FRC and ceramic overlays had the highest load-bearing capacity. Pulp chamber restoration with either FRC or SDR before ceramic overlay fabrication provided significantly better tooth reinforcement than ceramic overlay alone (P < 0.001). Fracture modes were analyzed to determine the type of fracture as repairable or catastrophic, where FRC + CO and SDR + CO groups had favorable fracture modes that were mostly repairable. When restoring root canal-treated molars with overlays, the pulp chamber should be sealed with either FRC or SDR to ensure the best possible fracture resistance. The clinical relevance of the study is that a new simple restorative protocol is presented to enhance the survival of root canal-treated molars using ceramic overlays.

Design of novel injectable in-situ forming scaffolds for non-surgical treatment of periapical lesions: In-vitro and in-vivo evaluation.

Periapical lesions are considered one of the common pathological conditions affecting alveolar bone. The primary focus of this study was to investigate the effectiveness of formulating an injectable in-situ forming scaffold-loaded with risedronate (bone resorption inhibitor) and with lornoxicam (anti-inflammatory drug) for the non-surgical treatment of periapical lesions. The scaffolds were prepared using solvent-induced phase inversion technique. Two insoluble copolymers were investigated namely; PLGA (ester-terminal) and PLGA-A (acid-terminal), additionally, SAIB was added as a high viscosity water-insoluble carrier. The addition of porogenic agents like hydrolyzed collagen was also investigated. The prepared scaffolds were characterized by analyzing their in-vitro release, DSC and rheological properties, besides their morphological properties. The results showed that the scaffolds prepared using 30% (w/v) PLGA or combined PLGA: SAIB (1:1, w/w) with total polymer concentration of 30% (w/v) possessed the most sustained drug release profile. Selected scaffolds were tested for their therapeutic effect to study the effect of porogenic agent, anti-inflammatory drug and risedronate in periapical lesions induced in dogs' teeth. Results declared that the selected scaffolds succeeded in improving the inflammation and enhancing the formation of new bony regions confirming the success of the prepared scaffolds as an innovative approach in the treatment of bone defects.