Biomaterial investigations in dentistry最新文献

Objective: Bracket detachment remains a frequent complication in orthodontic treatment, often resulting in extended treatment duration and increased clinical workload. Nano-hydroxyapatite (n-HAp), due to the excellent biocompatibility and bioactivity, has been explored as a potential filler to improve the performance of dental adhesive systems. This study aimed to evaluate the effect of incorporating 2 wt% n-HAp derived from Amusium pleuronectes (Asian moon scallop) shells into orthodontic adhesive on shear bond strength (SBS) to enamel and on Adhesive Remnant Index (ARI) scores.

Materials and methods: Thirty-two extracted human maxillary premolars were randomly divided into two groups (n = 16). The experimental group used orthodontic adhesive modified with 2 wt% n-HAp, while the control group used unmodified commercial adhesive. Standard bracket bonding procedures were performed, followed by SBS testing using a universal testing machine. After debonding, the adhesive remnants were evaluated under a stereomicroscope to determine ARI scores. SBS data were analyzed using an independent t-test, and ARI scores were assessed using the Mann-Whitney U test, with significance set at p < 0.05.

Results: The experimental group exhibited a significantly higher mean SBS of 16.54 ± 2.98 MPa compared to 8.91 ± 1.63 MPa in the control group (p < 0.05). ARI scores showed no statistically significant difference between the two groups (p > 0.05), with mean scores of 3.44 ± 1.23 and 3.38 ± 1.22, respectively.

Conclusion: Incorporation of 2 wt% nano-hydroxyapatite derived from Asian moon scallops into an orthodontic adhesive improved bond strength without altering failure patterns, suggesting its potential as an effective bioactive filler in orthodontic applications.

Objective: This study aimed to compare the effect of two different generations of bisphosphonates (BPs) on bone repair assisted by an alloplastic bone graft (spheres of nanostructured carbonate apatite/calcium, CHA) in a non-critical defect in the rat femur.

Materials and methods: Thirty-six female Wistar rats were randomly assigned into six groups: Control group (blood clot), carbonate apatite (CHA) alone, Zoledronate (Zol) with blood clot, Clodronate (Clo) with blood clot, Zol+CHA, and Clo+CHA. Drugs were administered intraperitoneally (Zol: 0.6 mg/kg; Clo: 20 mg/kg) every 30 days for 60 days before surgery. Standardized monocortical femoral defects (2 mm) were created and filled according to group assignment. After 30 days of healing, samples were harvested for histological and histomorphometrical evaluation. New bone formation and remnant biomaterial were quantified. Statistical analysis included the Kruskal-Wallis test and Dunn's post hoc (p < 0.05), along with Pearson and Spearman correlation analyses.

Results: Histological analysis revealed enhanced new bone formation in groups treated with BPs, especially when combined with CHA. The Zol+CHA group exhibited the highest new bone formation (24.0 ± 4.0%), significantly greater than Control (2.0 ± 0.5%; p = 0.011) and CHA (5.0 ± 1.2%; p = 0.0017). The Clo and Clo+CHA groups also showed significant improvements (19%) compared to the Control (p = 0.03) and CHA (p = 0.04). Remnant biomaterial was significantly greater in Zol+CHA (15.0 ± 2.0) and Clo+CHA (15.0 ± 2.0%) than in CHA alone (8.0 ± 1.0%; p = 0.022), suggesting inhibition of bone graft resorption by BPs. Correlation analysis revealed a strong positive association between remnant biomaterial and new bone formation (Spearman ρ = 0.94, p = 0.005; Pearson r = 0.88, p = 0.021), supporting the biological synergy of CHA and BPs in bone repair.

Conclusion: Both bisphosphonates enhanced bone repair in the femoral defect model, demonstrating a synergistic effect when combined with nanostructured CHA. Zoledronate required the presence of the biomaterial to exert its osteogenic influence, while Clodronate stimulated new bone formation independently. These findings indicate that generation-specific differences among bisphosphonates may guide their future use in bone tissue engineering strategies.

Objective: Irrigation is a clinical procedure in which needles of various designs, attached to syringes, are delivered by positive pressure to cleanse the root canals of infection-promoting agents. Despite being available in multiple designs and different materials, the irrigant does not necessarily reach every portion of the canal. This study compared four different needle designs in terms of depth of penetration of the needle (DOP), wear of the needle and fluid dynamics of the irrigant (FD).

Methods: Stereolithography was used to manufacture four 3D-printed single-rooted mandibular premolars with double curvature. The four needle designs used were Group I (NiTi open-ended, notched needle tip), Group II (Stainless steel, single-sided vented needle tip), Group III (Stainless steel, double-ended needle tip), and Group IV (Soft propylene, multi-vented needle tip) (n = 10 in each group). After assigning each tooth to a group, a stereomicroscope was used to measure the DOP. Pre- and post-irrigation scanning electron microscopy images of three randomly chosen needles from each group helped qualitatively determine the wear. Later, particle image velocimetry (PIV) experiments for each of the four needle designs were subsequently compared with those obtained from computational fluid dynamics (CFD).

Results: The open-ended syringe had the significantly lowest mean DOP as determined by one-way ANOVA and Tukey's post hoc test. Wear was significantly lowest in the non-metallic syringes. The PIV and CFD analyses were in close agreement with each other. The non-metallic needle exhibited the highest pressure and axial velocity near the apex.

Conclusion: The validated CFD models showed a greater canal coverage and irrigant flow from the non-metallic syringe in the double curvature root canal simulations; though with the highest risk of apical extrusion.

Objective: To evaluate in vitro the effect of two commercial mouthwashes, Encident Brackets^® (fluoride- and chlorhexidine-containing) and BambooSmile^® (natural formulation) on the surface roughness of nickel-titanium (NiTi) orthodontic archwires.

Materials and methods: Thirty rectangular NiTi archwire segments (0.019 × 0.025", Orthometric) were divided into three groups (n = 10 each): control, Encident Brackets^®, and BambooSmile^®. Samples were pre-immersed in artificial saliva for 24 h, then exposed for 1.5 h to the respective solutions, simulating 30 days of clinical use. Surface roughness (Rz) was measured before and after immersion using a Marsurf PS10 profilometer. Statistical analysis included Student's t-test and ANOVA (p < 0.05).

Results: Both mouthwashes significantly increased surface roughness compared to baseline (p < 0.05). Mean Rz values rose from 0.798 to 2.208 μm in the Encident Brackets^® group and from 0.782 to 2.085 μm in the BambooSmile^® group. However, no significant differences were observed between the two experimental groups after treatment (p > 0.05).

Conclusions: Exposure to both conventional and natural mouthwashes resulted in significant surface alterations of NiTi archwires. Although Encident Brackets^® produced slightly higher roughness values, its effect was comparable to BambooSmile^®. These findings highlight the importance of considering mouthwash composition during orthodontic treatment, as increased surface roughness may compromise sliding mechanics, favor bacterial adhesion, and affect periodontal health. Further in vivo studies are recommended to validate these results under clinical conditions.

Laser-assisted endodontic treatments have gained popularity over the last decade. This study evaluated the flexural strength (FS), fatigue resistance, and surface characteristics of root dentine after laser-assisted endodontic protocols. Forty extracted, caries-free canines were used to prepare root dentine beams (n = 37/group). Beams were irradiated with (1) Er:YAG 2,940 nm (20 mJ, 0.3W, 15 Hz, 50 ms), (2) Er,Cr:YSGG 2,780 nm (2.25W, 50 Hz, 140 ms), and (3) 940 nm diode laser (1W, CW). The non-irradiated beams served as control group. Both erbium groups were treated with laser-activated irrigation with radial firing tips (RFTs); meanwhile, the diode group irradiation protocol, using RFT, was dry. Specimens underwent quasi-static loading (n = 12) and cyclic loading for fatigue behaviour (n = 25) using 4-point flexure test. Scanning electron microscopy analysis was performed. Data were analysed using analysis of variance and Kruskal-Wallis tests (α = 0.05). No significant difference was found in FS or fatigue resistance after laser-assisted treatment (p > 0.05), but endurance limits improved by 18% (Er:YAG) and 19% (Er,Cr:YSGG) compared to controls. These findings suggest that Er:YAG, Er,Cr:YSGG, and 940 nm diode lasers, when applied with recommended parameters, do not compromise dentine fatigue strength. Therefore, they may be safely integrated into root canal treatment protocols.

Introduction: The current research tested the assumption that the addition of nano-carbonated hydroxyapatite (nCHAp) to Mineral Trioxide Aggregate (MTA) Angelus would modify its physicochemical properties and alter compositional characteristics that were relevant to the development of bioactive phases, without altering normal hydration dynamics.

Methods: MTA angelus was blended with 5 wt% nano-CHAp and subjected to controlled hydration. Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) was conducted to identify functional groups and affirm the inclusion of carbonate and phosphate ions. Phase composition was analyzed using X-ray diffraction (XRD). Surface morphology and elemental composition were analyzed by using Field Emission Scanning Electron Microscopy (FESEM) in conjunction with Energy Dispersive X-ray Spectroscopy (EDX). Porosity and microstructural integrity were also examined.

Results: ATR-FTIR spectra showed peaks corresponding to characteristic functional groups of carbonates (CO₃ ^2-) and phosphate (PO₄ ^3-), affirming the incorporation of nano-CHAp chemically. XRD patterns affirmed the preservation of key hydration phases such as portlandite, tricalcium silicate, calcite, and bismuth oxide, with new calcium phosphate phases due to inclusion of nano-CHAp. FESEM images showed more dense microstructure with reduced porosity and reformed particle packing. EDX analysis showed the inclusion of phosphorus and notable increases in calcium and carbon content, corresponding with nano-CHAp inclusion. The modified MTA angelus preserves primary hydration pathways while having enhanced biofunctional availability of ions and surface morphology.

Conclusion: Introduction of nano carbonated hydroxyapatite (nCHAp) brought about discernible changes in the composition of the cement matrix through the phase specific characteristics of XRD, ATR-FTIR, and energy-dispersive X-ray spectroscopy (EDS). These structural changes may create compositional environments that would support the development of mineral-related phases, but it would require further, more specific studies than the current one to confirm biological or clinical outcomes.

Introduction: Debonding of silicone prostheses from metal substructures is a frequently reported complication in prosthodontics. Polyether ether ketone (PEEK) has emerged as a promising alternative framework material owing to its favourable biomechanical properties; however, its limited bond strength to silicone remains a concern. The present study aimed to evaluate the shear bond strength between PEEK and maxillofacial silicone following laser etching of PEEK and subsequent accelerated ageing.

Materials and methods: According to ISO 10477:2020, 128 PEEK specimens were fabricated using Computer-Aided Design and Computer-Aided Manufacturing (CAD/CAM) with 10 mm diameter and 3 mm thickness, and silicone specimens with 5 mm diameter and 2.5 mm height. The specimens were categorised into: Group 1-no surface treatment, Group 2-Al₂O₃ air abrasion, Group 3-98% sulphuric acid etching, and Group 4-laser irradiation. The silicone specimens were bonded to PEEK and kept at room temperature for 24 h for polymerisation, and were subjected to accelerated ageing for 252, 504, and 1,008 h. The shear bond strength was evaluated using universal testing machine at 1 mm/min crosshead speed. The comparison within groups was done using one-way analysis of variance (ANOVA) and multiple group comparison was done using Tukey's HSD (Honestly Significant Difference) post-hoc analysis.

Results: Statistical analysis showed that surface pretreatment had a significant effect on bond strength (p < 0.05). Laser treatment and air abrasion produced significantly higher bond strengths compared to sulfuric acid etching, while no significant difference was found between laser treatment and air abrasion. Accelerated ageing time also had a significant influence, with bond strength values decreasing progressively from 252 h to 1,008 h across all pretreatment groups.

Conclusion: Surface pretreatment significantly influenced the adhesion of maxillofacial silicone to PEEK. Laser treatment and air abrasion provided superior and statistically comparable bond strengths, whereas sulfuric acid etching was less effective. Accelerated ageing reduced bond strength over time, highlighting the effect of ageing conditions on the durability of adhesion.

Objective: The objective of this study was to coat orthodontic nickel titanium (NiTi) archwires with nano-particles (NP) of silver (Ag) combined with nano polytetrafluoroethylene (PTFE) to produce a smooth antimicrobial nanocomposite layer by using a radio frequency (RF) sputtering process and to evaluate the coated surfaces in terms of morphology, nano-roughness, adhesion strength, hardness, and antimicrobial activity.

Materials and methods: Super-elastic NiTi archwires (diameter = 0.4 mm, length = 160 mm) were surface cleaned and sterilized prior to the RF sputtering, using a mixture of nano Ag powder (20 nm; purity > 99.95%) and PTFE powder (25 nm; purity > 99.95%). X-ray diffraction apparatus (XRD), flex atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) were used to characterize the morphology and nano roughness of the coated archwires. Lactobacillus acidophilus (L. acidophilus) and Streptococcus mutans (S. mutans) were selected to evaluate the antimicrobial activity.

Results: A uniform and homogeneous nanocomposite coating was obtained without agglomeration. Surface roughness values decreased with increasing sputtering time, while the coated samples exhibited excellent antibacterial activity against both bacterial strains. AFM analysis demonstrated that sputtering time strongly influenced adhesion resistance, hardness, and coating stability, and the antibacterial activity was highly effective against both L. acidophilus and S. mutans.

Conclusion: The sputtering time of 30 min gave a smooth coating layer on the surface of NiTi archwire with strong antimicrobial resistance that offers significant potential for dental applications.

Aim and objectives: To evaluate the antibacterial, antibiofilm, antioxidant, and anti-inflammatory properties of Amphiroa fragilissima and assess its potential for dental and orthodontic use.

Materials and methods: Methanolic extracts of A. fragilissima, collected from Rameshwaram, India, were tested against Streptococcus mutans, Enterococcus faecalis, Escherichia coli, and Shigella sonnei using the Kirby-Bauer method. Antibiofilm activity was analyzed via Crystal Violet staining. Antioxidant potential was assessed using 2,2-Diphenyl-1-picrylhydrazyl radical scavenging, and anti-inflammatory activity was measured via a bovine serum albumin assay.

Results: The extract showed dose-dependent antibacterial activity, with maximum inhibition observed at 100 µg/mL. Biofilm inhibition also increased with concentration. Antioxidant assays revealed significant radical scavenging activity, with results comparable to controls at higher concentrations. Anti-inflammatory testing showed reduced protein denaturation in treated samples, with effects similar to the positive control and significantly better than the blank.

Conclusion: Amphiroa fragilissima demonstrates strong antibacterial, antibiofilm, antioxidant, and anti-inflammatory activities, along with remineralization potential due to its calcium-rich composition. These properties support its potential as a natural, multifunctional agent for dental and orthodontic applications. Further in vivo studies are recommended to validate its clinical use.

Background: Alveolar ridge preservation (ARP) is critical for minimizing post-extraction bone loss and maintaining ridge dimensions essential for prosthetic replacement. Eggshell-derived hydroxyapatite (EHA), owing to its compositional similarity to natural bone and promising biological properties, has emerged as a potential alternative to conventional graft materials such as Demineralized Freeze-Dried Bone Allograft (DFDBA). The aim of the study was to compare the clinical and radiographic outcomes of EHA and DFDBA in ARP.

Materials and methods: This prospective randomized clinical trial involved 20 patients requiring mandibular posterior extractions, which were assigned to two groups: EHA (test) and DFDBA (control). In both groups, bone grafts were combined with injectable Platelet-Rich Fibrin (i-PRF) to form sticky bone and sealed with Advanced Platelet-Rich Fibrin (A-PRF) membranes. Clinical parameters such as Plaque Index (PI), Gingival Index (GI), Width of Keratinized Gingiva (WKG) and radiographic parameters such as Vertical Ridge Height, Horizontal Ridge Width, and Bone Density were evaluated at baseline and Healing Index (HI) was evaluated after 2 weeks.

Results: Both study groups exhibited significant improvements in PI, GI, WKG, vertical ridge height and horizontal ridge width within group with no significant difference between the groups. However, EHA demonstrated less ridge reduction compared to DFDBA with no significant changes in bone density. Wound healing at 2 weeks showed no significant difference between groups.

Conclusions: EHA with platelet-rich fibrin (PRF) is an effective, affordable, and biocompatible option for ARP. EHA demonstrated greater ridge dimensional stability and similar bone density improvements compared to DFDBA, with minimal resorption and favorable healing outcomes.