Biomaterial investigations in dentistry最新文献

Over the past two decades, dental pulp regeneration has become a major focus in endodontology. The currently applied clinical strategies are referred to as 'revitalisation' procedures. These biology-based treatment strategies aim at regenerating lost pulp tissues in necrotic teeth, in the absence or even more in the presence of periapical bone lesion, clinical signs and symptoms. Such approaches are generally - but not exclusively - used in immature teeth to promote root maturation, both in length and in thickness, ultimately to reduce their risk of fracture. A growing body of evidence has led to increased understanding and reliability of these treatment strategies, which are now considered as a valid alternative treatment option besides conventional ones, mainly the apical plug technique. However, all systematic reviews evaluating clinical outcomes concluded that there is a lack of robust long-term studies on the subject; most published cases of revitalisation having a relatively short-term follow-up, usually under 2 years. In this context, several major challenges remain to be addressed to better understand the promises and limitations of revitalisation procedures as compared to other treatment options, mainly the placement of an apical plug made of hydraulic calcium silicate cement. The purpose of this paper was therefore to identify some of the important remaining challenges related to such procedures, which can be broadly categorised into biological and mechanical ones, affecting treatment success and tooth survival. Meeting these challenges requires close collaboration between both researchers and clinicians, to establish guidelines, evaluate and understand treatment outcomes, and update guidelines accordingly. However, it is not always easy for researchers to understand the clinical reality faced by practitioners. In order to facilitate their mutual understanding, the aforementioned challenges were illustrated by providing clinical context through a series of atypical clinical cases with long-term follow-up (4-8 years).

Objective: Considering the effect of bone resorption-inhibiting drugs, such as bisphosphonates, on bone density, the present study evaluated the stability of implants coated with polylactic-co-glycolic acid (PLGA)-alendronate sodium.

Methodology: Ten healthy Swiss rabbits were selected (mean weight: 3.5 kg). Two titanium implants were inserted in each rabbit's tibia bone, one implant coated with PLGA-alendronate sodium and the other functioning as control. Torque meter equipment measured the amount of torque while inserting the implants. Insertion torque was measured during the initial insertion of the implants, and after 4 weeks, the rabbits were anesthetized again, the implants were exposed, and resistance torques were measured and recorded. Using a trephine bur, all implants and the surrounding bone structure were then removed for histological evaluation. Fourier transform infrared spectroscopy was used to investigate alendronate and PLGA biologically. Data analysis was performed using SPSS.v23 software with a significance level of p < 0.05.

Results: The results showed that the difference between insertion torque and final resistance torque after 4 weeks was statistically significant (p = 0.024). The mean number of osteoclasts and macrophages differed substantially between the experimental and control groups (p < 0.001). The ratio of woven bone to lamellar bone and the number of osteoblasts did not differ significantly between the two groups (p > 0.05).

Conclusion: The use of PLGA-alendronate sodium coating decreased the number of osteoclasts and macrophages and increased the stability of implant anchorage.

The objective of this study was to evaluate the influence of mouth rinses on the roughness and optical properties of three polymeric restorative materials. Cylinders were obtained from Ivotion Dent, Ivotion Base, and Empress Direct. Nano-hybrid composite teeth were also investigated (SR Phonares II). Specimens were divided into four subgroups for mouth rinsing simulation according to the mouth rinse: (1) Distilled water; (2) Soft-Tissue; (3) Implants/Cosmetic; and (4) PerioGard. Roughness (Ra) and optical properties were evaluated before and at timepoints during mouth rinsing simulation. Roughness increased after rinsing simulation for Ivotion Dent and Ivotion Base after all mouth rinses. Soft-Tissue and Cosmetic increased the Ra of Empress Direct. Translucency parameter (TP) of Ivotion Dent and Empress Direct increased, while Contrast ratio (CR) values decreased after rinsing simulation, regardless of the solution used. Ivotion Base demonstrated higher TP after rinsing with Soft-Tissue and Implants mouth rinses compared to the control group, while no difference among them was observed for CR. The mouth rinses affected the roughness and optical properties of materials differently after the rinsing simulation.

Objective: The aim of this study was to compare the needle and irrigant penetration depth of a newly developed multi-vented polymer needle (30G), with three established needle designs - an open-ended metal needle (30G), a side-vented polymer needle (30G), and a notched metal needle (27G) used as a reference control. The effect of manual dynamic activation (MDA) was also measured. The null hypotheses were that the irrigant penetration would be the same regardless of needle tip, and the addition of MDA would make no difference in terms of irrigant penetration.

Materials and methods: A total of 120 mesial roots from mandibular molars were instrumented to a size 25/07, with reciprocating files. The maximum needle penetration depth was measured for each needle tip, using a rubber stop. Syringe irrigation was performed using a sodium diatrizoate solution, first with needle placement halfway down the root canal (working length subtracted from the canal length), and then 1 mm from the working length. MDA was performed. A digital radiograph was taken before the initial irrigation, after the initial irrigation, after the final irrigation, and after MDA. Digital subtraction was performed, and irrigant penetration was measured by a blinded operator. Non-parametric statistical tests were conducted using Mann-Whitney U-test and Wilcoxon signed-rank test.

Results: The multi-vented polymer needle had a significantly deeper needle penetration (mean value: 99%), compared to other test needles. The deepest irrigant penetration was achieved using the multi-vented polymer needle (mean value: 98%) and the open-ended metal needle (mean value: 99%). A significantly deeper irrigant penetration, was achieved by adding MDA, regardless of needle tip.

Conclusions: The multi-vented polymer needle and the open-ended metal needle showed superior performance in terms of irrigant penetration. However, the irrigant penetration only managed to reach the working length when MDA was added.

Purpose: The purpose of this study was to evaluate the effect of silver diamine fluoride (SDF) on microhardness and microleakage of composite and glass ionomer cement restorations.

Materials and methods: Cavities were prepared in 28 extracted teeth and restored according to four regimens (GIC, composite, GIC and SDF conditioned, composite and SDF conditioned). The restored teeth were thermocycled and autoclaved and then exposed to cariogenic challenge (inoculated with Lactobacillus acidophilus and Streptococcus mutans) for 30 days. The restored teeth were sectioned mesio-distally. One half was subjected to microleakage testing (dye penetration using 2% methylene blue) and the other to Vickers hardness test.

Results: Group 4 SDF + Composite had the highest mean microleakage at 1.59 ± 0.02 (mm), and Group 1 (GIC) and Group 3 (Composite) had the lowest mean microleakage (0.63 ± 0.009 mm and 0.63 ± 0.02 mm, respectively). The highest mean microhardness (HV) was observed in Group 3 (Composite) at 327 ± 2.16 and lowest in Group 2 (GIC + SDF) at 283 ± 1.95. Results were statistically significant with a p value < 0.05.

Conclusion: SDF conditioning negatively impacted microhardness and increased microleakage, which could negatively impact the longevity of restorations. Therefore, in this study, SDF was not suitable as a treatment to decrease the occurrence of secondary caries.

Objective: Glass ionomer cements (GICs) require protective surface coatings to enhance their clinical performance. This study developed novel protective resin coatings for GICs containing monocalcium phosphate monohydrate (MCPM), bioactive glass nanoparticles (BAGs), and poly-L-lysine (PLS) and evaluated their physical, mechanical, and biological properties when applied to GICs.

Materials and methods: Experimental resin coating materials were formulated with 5-10 wt% of MCPM, BAGs, and PLS. The degree of monomer conversion was measured usingAttenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) (n = 6). GICs coated with the experimental materials were evaluated for biaxial flexural strength and modulus after 24 h water immersion using a universal testing machine (n = 8). Vickers surface microhardness up to 4 weeks of water immersion was also determined (n = 5). Fluoride and elemental release in water were analyzed using a fluoride-specific electrode and inductively coupled plasma optical emission spectrometry (n = 3). Cell viability was assessed using an MTT assay with mouse fibrosarcoma (n = 3). A commercial resin coating (EQUIA Forte Coat, EQ) served as control. Data were analyzed using one-way ANOVA and Tukey HSD test.

Results: While EQ showed higher monomer conversion (87%) compared to experimental materials (72-74%) (p < 0.05), GICs coated with experimental materials demonstrated comparable strength to EQ-coated GICs. The experimental coatings exhibited similar F, Al, Na, and Si releases to EQ-coated GICs, with enhanced P release. All experimental coatings exhibited comparable cell viability (>70%) to the commercial material.

Conclusion: The novel GIC protective coatings containing MCPM, BAGs, and PLS demonstrated acceptable in vitro performance comparable to commercial materials while potentially offering enhanced remineralization through increased elemental release.

The placement of root filling materials aims to prevent the occurrence of post-treatment apical periodontitis following completion of endodontic treatment. Materials should possess properties that will not permit bacterial invasion and infection, namely excellent sealing ability and/or antibacterial properties. In root-end filling procedures or repair of root perforations, the root filling materials are placed in a particularly challenging clinical environment, as they interface with a relatively large area with the periradicular tissues. The biological properties of these materials are therefore of significant importance. The current review discusses the most widely used materials for endodontic surgery (i.e., root-end filling and perforation repair), with particular focus on their biological characteristics, namely antibacterial properties and interactions with host tissue cells, together with clinical studies. Properties of amalgam, glass ionomer cements (GICs), resin systems, zinc oxide eugenol-based cements and hydraulic calcium silicate cements (HCSCs), together with representative and well-researched commercial materials in the context of their use in endodontic surgery are presented. While the use of HCSCs seems to offer several biological advantages, together with addressing issues with the initial formulation in the most recent versions, materials with different chemical compositions, such as zinc oxide eugenol-based cements, are still in use and appear to provide similar clinical success rates to HCSCs. Thus, the significance of the currently available materials on clinical outcomes remains unclear.

Objectives: To investigate whether acid etch contamination of silane-treated composite influenced repair bond strength and whether silane contamination on dentin influenced composite bond strength to dentin.

Materials and methods: Forty composite blocks stored in water for 4 weeks were divided into four groups. Specimens in groups 1-3 were coated with Bis-Silane and contaminated with acid etch + water spray (group 1) or water spray (group 2). Group 3 was not contaminated. Group 4 was untreated. The occlusal third of 60 third molars was cut off, ground flat, and divided into three groups. After etching, the surfaces in groups A and B were contaminated with Bis-silane. The contaminated surfaces in group A were re-etched.Each composite repair group and composite-dentin group was divided into two subgroups receiving Adper Scotchbond 1 XT or Clearfil SE Bond 2 adhesives followed by a composite build up. After ageing for 3 months, specimens were sectioned into 1.1 mm × 1.1 mm rods for tensile testing and strength calculated at fracture. The fracture was examined using microscope.

Results: Bis-Silane surface treatment increased the repair bond strength. Contamination with acid reduced the strength of the repair bond. Similar results were obtained for both adhesives. Tooth surface contamination with silane reduced the bond strength between dentin and composite. Additional acid etching or water spray on silane contaminated dentin did not influence the weakened bond strength. Most fractures were adhesive type.

Conclusions: Silane contamination on etched dentin and acid etch contamination on silanized composite surfaces significantly reduced tensile bond strength.

Objectives: To assess inter- and intrarater reliability and agreement for measurements of root lengths using multiplanar reconstruction (MPR) in cone beam computed tomography (CBCT) examinations.Furthermore, to determine whether using MPR from different CBCT machines was a reliable and reproducible method for assessment of root length during orthodontic treatment of adolescents.

Materials and methods: A total of 40 CBCT examinations obtained before, during and after orthodontic treatment of 14 adolescents, with fixed appliances from a multicentre randomised controlled trial, were used. All roots from the incisors to the first molars were measured by two independent raters and in accordance with a protocol preceded by a multi-step calibration. Reliability was assessed by intra class correlation (ICC). Agreement was assessed by measurement error according to the Dahlberg formula and Bland-Altman plot.

Results: The number of repeated measurements varied from 436 to 474 for the different timepoints. Good to excellent inter- and intrarater reliability for different tooth groups and timepoints were shown. Measurement error for inter- and intrarater agreement varied between 0.41 mm and 0.77 mm. The Bland-Altman plot with 95% limits of agreement varied between +1.43 mm and -2.01 mm for different tooth groups and timepoints.

Conclusions: The results of this study indicate that CBCT using MPR from different machines is a reproducible method for measuring root length during different phases of orthodontic treatment. When interpreting root shortening measurements in CBCT using MPR for clinical or research purposes, values below 2 mm should be approached with caution, as they may contain measurement errors.