OBJECTIVES: This study explores the differences in fluid flow within alveolar cancellous bone at various sites under orthodontic forces and elucidates the relationship between fluid shear stress and bone remodeling. These fin-dings lay the groundwork for understanding the biomechanical mechanisms of orthodontic tooth movement. METHODS: Stress relaxation tests were performed on human alveolar bone samples to determine material parameters by using the Prony series. An inverse model of alveolar bone was then developed for numerical simulations of fluid-structure interactions to calculate fluid flow within cancellous bone. Meanwhile, a rat model of tooth movement was established to investigate variations in bone remodeling speeds across different regions. RESULTS: The microstructural distribution of cancellous alveolar bone was similar in humans and rats. The bone volume fraction and trabecular thickness gradually decreased from root cervical region to root apical region, while the trabecular space gradually increased. Under the influence of orthodontic forces, fluid shear stress within cancellous bone showed spatial variability across different levels, with the highest shear stress occurring at the root apical region, ranging from 0 to 0.936 6 Pa. Additionally, the rat model of tooth movement indicated that bone remodeling occurred more rapidly at the root apical region. CONCLUSIONS Fluid stimulation has a remarkable effect on al-veolar bone remodeling, causing changes in the structure of alveolar bone and ultimately regulating the speed of structu-ral remodeling.
Bone Remodeling ; Animals ; Tooth Movement Techniques ; Rats ; Alveolar Process/physiology* ; Stress, Mechanical ; Humans ; Biomechanical Phenomena ; Cancellous Bone/physiology* ; Shear Strength

OBJECTIVES: This study aims to evaluate the differences in shear bond strength, marginal adaptation, and nano-microleakage after aging among snowplow, layered filling, and lining techniques applied to the resin-bonded restoration of defective primary teeth. METHODS: In this study, 51 freshly extracted, crown-intact primary anterior teeth and 30 primary molars were collected. The experimental groups were as follows: layered filling group, lining group, and snowplow group. Experiments were performed to compare the differences in shear bond strength, marginal integrity, and silver ion nano-microleakage after aging among these groups. RESULTS: The median shear bond strength of the layered filling group, lining group, and snowplow group were 2.45, 5.72, and 9.43 MPa, respectively. The values for lining group and snowplow group were significantly higher than that for layered filling group (P<0.05). No statistically significant difference was found between lining group and snowplow group (P>0.05). The median overall margin integrity of the layered filling group, lining group, and snowplow group were 55.38%, 48.25%, and 65.63%, respectively. The difference among the three groups was not statistically significant (P>0.05). The median percentages of silver ion nano-microleakage in the layered filling group, lining group, and snowplow group were 11.71%, 9.47%, and 11.55%, respectively. The difference among the three groups was not statistically significant (P>0.05). CONCLUSIONS Applying the snowplow technique to restore defective primary teeth can improve the bond strength and margin integrity and reduce nano-microleakage.
Tooth, Deciduous ; Humans ; Dental Restoration, Permanent/methods* ; Dental Leakage ; Shear Strength ; Dental Bonding/methods* ; Molar ; Composite Resins ; Silver

OBJECTIVES: This work aimed to evaluate the ability of two kinds of antioxidants, namely, grape-seed extract and sodium ascorbate, in restoring bond strength at the resin-enamel interface after bleaching. METHODS: Ten groups of samples with 15 teeth per group were prepared for shear-bond-strength test at the resin-enamel interface after bleaching. The groups were as follows: control; no antioxidant; 2.5%, 5%, 10%, or 15% grape-seed extract; and 2.5%, 5%, 10%, or 15% sodium ascorbate. The peak values of shear bond strength when resin was debonded from teeth and the failure modes under a microscope were recorded. Ten other groups of teeth with two teeth per group were prepared and treated in a similar approach before resin bonding. The samples were cut vertically to the bonding interface. The structures of the bonding interface were compared by scanning electron microscopy. RESULTS: No statistically significant difference in shear bond strength was found among the no-antioxidant, 2.5% grape-seed extract, and 2.5%, 5%, or 10% sodium ascorbate groups ( CONCLUSIONS Immediately after bleaching, the bond strength of dental enamel significantly decreased. Bond strength can be restored by 5% grape-seed extract or 15% sodium ascorbate in 5 min.
Antioxidants ; Composite Resins ; Dental Bonding ; Dental Cements ; Dental Enamel ; Humans ; Shear Strength ; Tooth Bleaching

OBJECTIVE: This study aimed to compare the effects of water storage treatment and thermal cycling on the shear bond strength (SBS) of three self-adhesive dual-cure resin cements. METHODS: Six cubic zirconia specimens with side length of 2 cm were obtained by cutting and sintering. Three self-adhering dual-cure resin cements (i.e., Clearfil SAC, RelyX U200, and Multilink Speed) were selected. According to their bonding modes, they were divided into three groups: direct bonding group (direct coating with resin cement), adhesive group (applying universal adhesives and then coating with resin cement), and primer group (applying Z-Prime Plus and then coating with resin cement). According to experimental conditions, each group was divided into two subgroups: subgroup a (water storage at 37 ℃ for 24 h) and subgroup b (thermalcycling for 5 000 times). SBS data were analyzed by one-way ANOVA by using SPSS 19.0 software (P<0.05). The fractured zirconia surface was observed under a stereomicroscope. RESULTS: After water storage for 24 h, the SBS of the adhesive group and the primer group of the three resin cements was higher than that of the direct adhesive group (P<0.05), but the difference in SBS between the adhesive group and the primer group was not significant (P>0.05). After thermalcycling, the SBS of the three types of resin cements decreased (P<0.05); the SBS of the adhesive group was higher than that of the direct adhesive group and the primer group (P<0.05). Fracture mode analysis revealed that the type Ⅲ fracture mode evidently increased after the thermalcycling treatment compared with the water storage treatment. CONCLUSIONS The universal adhesives and the primer can improve the SBS of self-adhesive dual-cure resin cement in water storage at 37 ℃ for 24 h. The universal adhesives had a better bonding durability than the zirconia primer.
Ceramics ; Dental Bonding ; Dental Cements ; Dental Stress Analysis ; Materials Testing ; Resin Cements ; Shear Strength ; Surface Properties ; Zirconium

OBJECTIVE: This study aimed to develop novel self-adhesive resin cement with antibacterial and self-healing properties. Furthermore, the dentin bonding strength, mechanical properties, self-healing efficiency, and antibacterial property of the developed cement were measured. METHODS: Novel nano-antibacterial inorganic fillers that contain quaternary ammonium salts with long-chain alkyls were synthesized. These fillers were added into self-adhesive resin cement containing self-healing microcapsules at mass fractions of 0, 2.5%, 5.0%, 7.5%, or 10.0%. The dentin shear bonding test was used to test the bonding strength, whereas the flexural test was used to measure the flexural strength and elastic modulus of the cement. The single-edge V-notched beam method was used to measure self-healing efficiency, and human dental plaque microcosm biofilms were chosen to calculate the antibacterial property. RESULTS: The dentin shear bond strength significantly decreased when the mass fraction of the nano-antibacterial inorganic fillers in the novel cement reached 7.5% (P<0.05). The incorporation of 0, 2.5%, 5.0%, 7.5%, or 10.0% mass fraction of nano-antibacterial inorganic fillers did not adversely affect the flexural strength, elastic modulus, fracture toughness, and self-healing efficiency of the cement (P>0.1). Resin cement containing 2.5% mass fraction or more nano-antibacterial inorganic fillers significantly inhibited the metabolic activity of dental plaque microcosm biofilms, indicating strong antibacterial potency (P<0.05). CONCLUSIONS The novel self-adhesive resin cement exhibited promising antibacterial and self-healing properties, which enable the cement to be used for dental applications.
Anti-Bacterial Agents ; Dental Bonding ; Dental Cements ; Dental Stress Analysis ; Dentin ; Humans ; Materials Testing ; Resin Cements ; Shear Strength ; Surface Properties

OBJECTIVE: To compare the bonding durability of three different self-etch adhesives to primary enamel and dentin, and to investigate the effect of mild salivary contamination followed by air drying on the bonding durability. METHODS: Two hundred and forty enamel specimens were divided randomly into 16 groups (n=15/group)according to the adhesive system [self-etch adhesives: Clearfil SE Bond(SE), AdperTM Easy One (EO), Scotchbond Universal (SBU); total-etch adhesive: AdperTM Single Bond Plus(SL)], contamination status (non-contaminated vs. salivary-contaminated) and storage condition (stored in distilled water for 24 h vs. aging mode 5 000 thermal cycles in 5 ℃ and 55 ℃). Two hundred and forty dentin specimens were assigned in the same way. Shear bond strength for 12 specimens in each group were measured. The adhesive interface for the residual specimens in each group was observed by scanning electron microscopy(SEM). Data were analyzed by three-way analysis of variance and Tukey test(P < 0.05). RESULTS: For primary enamel, total-etch adhesive showed higher initial shear bond strength values (28.92±1.83) MPa and shear bond strength values (27.27±3.03) MPa after thermal cycles compared with the other groups, and the difference between the groups was statistically significant (P < 0.01). Shear bond strength values of EO decreased significantly in salivary-treated groups, regardless of storage conditions, and the difference was statistically significant (P < 0.01). For primary dentin, shear bond strength values of EO decreased significantly in salivary-treated groups after 24 h (P < 0.01). After 5 000 thermal cycles, total-etch adhesive showed significantly lower shear bond strength values (14.31±1.97) MPa compared with the other groups, and the difference between the groups was statistically significant (P < 0.01), and shear bond strength values of EO were significantly lower than those in SE and SBU groups (P < 0.01), regardless of contamination status. CONCLUSION Total-etch adhesive SL has better bonding durability to primary enamel. SE and SBU have better bonding durability to primary dentin and have a certain resistance to salivary contamination, while the bonding performance of EO is compromised greatly by mild salivary contamination followed by air drying.
Acid Etching, Dental ; Adhesives ; Dental Bonding ; Dentin ; Dentin-Bonding Agents ; Materials Testing ; Resin Cements ; Shear Strength ; Tooth, Deciduous

PURPOSE: The aim of this study was to evaluate the microshear bond strength (µSBS) of four computer-aided design/computer-aided manufacturing (CAD/CAM) blocks repaired with composite resin using three different surface treatment protocols.MATERIALS AND METHODS: Four different CAD/CAM blocks were used in this study: (1) flexible hybrid ceramic (FHC), (2) resin nanoceramic (RNC), (c) polymer infiltrated ceramic network (PICN) and (4) feldspar ceramic (FC). All groups were further divided into four subgroups according to surface treatment: control, hydrofluoric acid etching (HF), air-borne particle abrasion with aluminum oxide (AlO), and tribochemical silica coating (TSC). After surface treatments, silane was applied to half of the specimens. Then, a silane-containing universal adhesive was applied, and specimens were repaired with a composite, Next, μSBS test was performed. Additional specimens were examined with a contact profilometer and scanning electron microscopy. The data were analyzed with ANOVA and Tukey tests.RESULTS: The findings revealed that silane application yielded higher µSBS values (P<.05). All surface treatments were showed a significant increase in µSBS values compared to the control (P<.05). For FHC and RNC, the most influential treatments were AlO and TSC (P<.05).CONCLUSION: Surface treatment is mandatory when the silane is not preferred, but the best bond strength values were obtained with the combination of surface treatment and silane application. HF provides improved bond strength when the ceramic content of material increases, whereas AlO and TSC gives improved bond strength when the composite content of material increases.
Adhesives ; Aluminum Oxide ; Ceramics ; Clinical Protocols ; Dental Bonding ; Dental Restoration Repair ; Hydrofluoric Acid ; Microscopy, Electron, Scanning ; Polymers ; Shear Strength ; Silicon Dioxide

OBJECTIVE: To assess the effects of two surface treatments (sandblasting, SB; microarc-oxidation, MAO) and resin luting on shear bond strength and durability of titanium alloy and composite-resin. METHODS: Eighty cylindrical titanium alloy specimens with a diameter of 10 mm and a height of 8 mm were fabricated by CAD/CAM technique. It was divided into two groups according to the surface treatment methods: sandblasting with Al2O3 particles on the surface of SB specimens; porous ceramic film structure could be formed on the surface of MAO specimens after surface treatment. Each group was classified into SB-resin luting-N group (not used), SB-resin luting-Y group (used), MAO-resin luting-N group (not used), MAO-resin luting-Y group (used) depending on whether or not resin luting was applied. Each specimen was bonded and cured with the Cemerage resin, and the shear bond strength after 0 and 5 000 thermocycling was tested. The results were statistically analyzed. The surface morphology of titanium alloy specimens before and after the shear bond strength test was observed by scanning electron microscopy (SEM). RESULTS: The shear bond strength between titanium alloy and composite-resin was the highest in the SB combined with resin luting group after 0 thermocycling (16.2±1.8) MPa; was the lowest in MAO group after 5 000 thermocycling (8.9±1.5) MPa. The shear bond strength of SB and MAO surface treatment methods combined without resin luting group after 5 000 thermocycling were (10.7±2.2) MPa and (8.9±1.5) MPa, which were statistically lower than those in the thermocycling 0 (P=0.000 and P=0.001). The shear bond strength of SB and MAO surface treatment methods combined with resin luting group after 5 000 thermocycling were (15.5±2.1) MPa and (11.7±1.3) MPa, respectively, which were lower than those in the thermocycling 0 group, but there was no statistical significance (P=0.087 and P=0.234). CONCLUSION Both the surface treatment methods of SB and MAO combined with resin luting can improve the shear bond strength and durability of titanium alloy and composite-resin. The SB combined with resin luting is more significant. At present, the effect of SB is better than that of MAO due to the limitation of technical parameters of micro-arc oxidation.
Alloys ; Composite Resins ; Dental Bonding ; Materials Testing ; Resin Cements ; Shear Strength ; Surface Properties ; Titanium

BACKGROUND: Three-dimensional (3D) printing with a direct metal fabrication (DMF) technology has been innovatively introduced in the field of surface treatment of prostheses. The purpose of this study was to determine whether such modifications on the surface of cobalt-chromium (CoCr) alloy by titanium powder coating using DMF improves the osseointegration ability of CoCr alloy. METHODS: We compared the in vitro and in vivo ability of cells to adhere to DMF-coated CoCr alloy with machining. Biological and morphological responses to human osteoblast cell lines were examined by measuring cell proliferation rate and observing expression of actin filament. For in vivo study, we inserted different specimens in each medulla of the distal femurs of rabbit. After 3 months, the distal femurs were harvested, and a push-out test and histomorphometric analyses were performed. RESULTS: The cell proliferation rate and cell adhesion in the DMF group were higher compared with those in the machined group. Human osteoblast cells on the DMF-coated surface were more strongly adhered and well-proliferated compared with those on the other surface. In the in vivo test, there was a significant difference in the ultimate shear strength between the DMF and machined groups (2.49 MPa vs. 0.87 MPa, respectively, p = 0.001). In the histomorphometric analysis, there was a significant difference in the mean bone-to-implant contact percentages between the DMF and machined groups (72.3 ± 6.2% vs. 47.6 ± 6.9%, respectively, p < 0.001). CONCLUSION: Titanium coating of CoCr alloy with 3D metal printing provides optimal surface characteristics and a good biological surface both in vitro and in vivo.
Actin Cytoskeleton ; Alloys ; Cell Adhesion ; Cell Line ; Cell Proliferation ; Femur ; Humans ; In Vitro Techniques ; Osseointegration ; Osteoblasts ; Printing, Three-Dimensional ; Prostheses and Implants ; Shear Strength ; Titanium

PURPOSE: The purpose of this study was to evaluate the shear bond strength (SBS) of an indirect resin composite (IRC) to the various resin matrix ceramic (RMC) blocks using different surface treatments. MATERIALS AND METHODS: Ninety-nine cubic RMC specimens consisting of a resin nanoceramic (RNC), a polymer-infiltrated hybrid ceramic (PIHC), and a flexible hybrid ceramic (FHC) were divided randomly into three surface treatment subgroups (n = 11). In the experimental groups, untreated (Cnt), tribochemical silica coating (Tbc), and Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) laser irradiation (Lsr) with 3 W (150 mJ/pulse, 20 Hz for 20 sec.) were used as surface treatments. An indirect composite resin (IRC) was layered with a disc-shape mold (2 × 3 mm) onto the treated-ceramic surfaces and the specimens submitted to thermal cycling (6000 cycles, 5 – 55℃). The SBS test of specimens was performed using a universal testing machine and the specimens were examined with a scanning electron microscope to determine the failure mode. Data were statistically analyzed with two-way analysis of variance (ANOVA) and Tukey HSD test (α=.05). RESULTS: According to the two-way ANOVA, only the surface treatment parameter was statistically significant (P<.05) on the SBS of IRC to RMC. The SBS values of Lsr-applied RMC groups were significantly higher than Cnt groups for each RMC material, (P<.05). Significant differences were also determined between Tbc surface treatment applied and untreated (Cnt) PIHC materials (P=.039). CONCLUSION: For promoting a reliable bond strength during characterization of RMC with IRC, Nd:YAG laser or Tbc surface treatment technique should be used, putting in consideration the microstructure and composition of RMC materials and appropriate parameters for each material.
Aluminum ; Ceramics ; Composite Resins ; Fungi ; Shear Strength ; Silicon Dioxide ; Yttrium