Fabrication and characterization of novel glass-ionomer cement prepared from oyster shells.

Glass ionomer cement (GIC) is one of the most widely used restorative materials for temporary fillings and reconstructions in dentistry, but it has relatively poor mechanical properties that make its use limited, especially in places subject to high pressure. Thus, to extend the applicability of GIC, samples based on SiO2, P2O5, Al2O3, CaF2, and NaF were prepared with the addition of calcium oxide CaO extracted from natural sources (oyster shells) in different ratios of 0, 5, 10, 15, 20, and 25% wt. The suggested glass samples were evaluated, and their physical and mechanical properties were compared. XRD, SEM, and FTIR were performed on the samples. 24 specimens were prepared for each test in order to assess the mechanical properties as per the specific requirements. The tests included measuring bending strength, elastic modulus, adjusted direct tensile strength, absorption, water solubility, and diffusion coefficients after the specimens were stored in distilled water for 60 days. All calculations were carried out in accordance with standard procedures. The findings indicated a slight improvement in the bending resistance of the recommended GIC. Glass modified with 20% by weight of calcium oxide was the best among the ratios in terms of the results obtained and compared to the traditional commercial type. The malleable strength of the sample was 54.121 MPa, while the flexural modulus increased, the tensile strength reached 10.154 MPa, and the solubility was 25.87 µg/mm3 after storage for 60 days. These indicate that the developed material is suitable for use as a dental restoration material when compared to international commercial cement specifications.

Elemental analysis and micromorphological patterns of tooth/restoration interface of three ion-releasing class V restorations.

OBJECTIVES: To evaluate and compare the ion-releasing capability of three different restorative systems at the restoration/tooth interface elemental analysis using energy-dispersive X-ray technique. Additionally, micromorphological patterns of the restoration/tooth interfaces was investigated. MATERIALS AND METHODS: Eighteen freshly extracted sound human premolars were collected for the study. The premolars were randomly assigned into 3 groups (n = 6) based on the type of restorative materials used: Giomer (Beautifill II), ion-releasing composite (Activa Presto), and RMGI (Riva Light Cure). Half of the specimens in each group were tested after 24 h (the "immediate group"), while the remaining half were tested after 6 months of storage in deionized water (the "delayed group"). Standardized box-shaped cavities along the cervical area of teeth crowns and restored them with the assigned restorative material following manufacturers' instructions. The specimens were sectioned buccolingually into 2 halves. One half of each specimen was subjected to elemental analysis using energy-dispersive X-ray technique (EDX), while the remaining half was sputter coated and underwent micromorphological analysis of the restoration/tooth interface using a scanning electron microscope (SEM). The collected data from elemental analysis test were tabulated and subjected to statistical analysis. RESULTS: The two-way ANOVA test showed significant differences in both phosphorus and calcium levels among the tested restorative systems (p < 0.05). In the immediate subgroup, RMGI recorded the highest phosphorus level (0.1527), followed by the ion-releasing composite (0.1172), while Giomer exhibited the least levels (0.0326) (p < 0.05). The ion-releasing composite group had the highest calcium level (0.2797), followed by RMGI (0.248), and Giomer (0.2385) respectively (p < 0.05). In the delayed subgroups, Giomer recorded the highest phosphorus level (0.1526), followed by the ion-releasing composite (0.1058), and RMGI group (0.0466) respectively (p < 0.05). RMGI had the highest calcium level (0.2801), followed by the ion-releasing composite (0.2659), and Giomer had the lowest level (0.1792) (p < 0.05). The micromorphological analysis of the restoration/tooth interfaces showed good adaptation between the composite and tooth substrate in different restorative groups. CONCLUSIONS: The ion-releasing capability of the three restorative systems appears to be comparable. The rate of mineral release and diffusion is affected by time and composition.

Immediate and delayed shear bond strength evaluation between root canal sealers and restorative materials: an experimental study.

BACKGROUND: Several calcium silicate-based sealers have recently emerged in endodontics. This study aimed to compare the immediate and delayed shear bond strength between the bioceramic and calcium hydroxide-based sealers and different resin-based restorative materials. METHODS: One hundred and twenty specimens with a 3-mm depth and a 3-mm diameter were prepared. They were evenly divided into two groups, the bioceramic sealer and calcium hydroxide-based sealer groups. Each primary group was subdivided into two subgroups based on the restorative material used; i.e., the flowable resin composite and resin-modified glass ionomer subgroups. Moreover, each subgroup was further divided into the restoration process's timing: either immediately post-sealing or delayed after setting the sealers for seven days. The mode of failure was assessed by stereomicroscopic examination. RESULTS: The highest shear bond strength was found when the bioceramic sealer was used and restored with the flowable resin composite. The strengths were 8.45 (1.17) and 6.67 (1.60) megapascals (MPa) in the immediate and delayed restoration groups, respectively. In contrast, the lowest strength, 2.91 (1.22) MPa, was recorded when calcium hydroxide-based sealer was employed and restored after allowing the sealer to set completely with resin-modified glass ionomer. Notably, there were no cohesive fractures within the tested restorative materials. All observed fractures occurred within the sealer materials, at the interface of the sealer and restorative material, or in combination. Moreover, the most common failure was a mixed failure. CONCLUSIONS: When flowable resin composite was used immediately before complete setting, bioceramic sealers showed a higher bond strength than calcium hydroxide-based sealers.

The effect of thermal aging on microhardness and SEM/EDS for characterisation bioactive filling materials.

BACKGROUND: The aim of this study is to evaluate the surface microhardness, surface chemical composition of bioactive restorative materials pre- and post- thermal aging. METHOD: A total of 200 disc-shaped samples were prepared by using the materials: Cention N, ACTIVA BioActive Restorative, Equia Forte HT Fil, Glass Fill glass carbomer cement (GCP), and Fuji II LC. Vickers microhardness test were used to measure surface hardness. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM/EDS) was used to determine the characterization of the microstructures and elemental analysis of the materials. These measurements were repeated after thermal aging. One-Way ANOVA test, Bonferroni test and the Games-Howell test was used for data analysis. The significance level was accepted as 0.05. RESULTS: Cention N had the highest vickers microhardness value before thermal cycle. The highest fluoride ion ratio among the materials before thermal aging was detected in the Equia Forte HT Fil and Fuji II LC groups. While a decrease in fluorideF ion was detected in all groups except the Cention N group after thermal aging. It is observed that ACTIVA BioActive Restorative has a more microporous and rougher surface in the scanning electron microscopy image after the thermal cycle than in the image before the thermal cycle. CONCLUSIONS: The chemical properties of the materials and the properties of the filler particles may be related to the differences in the mechanical properties, surface characterizations and ion releases of the materials Thermal aging affected the microhardness, surface characteristics and elemental mass ratios of the studied materials. Alkasite bioactive materials are more similar to composite restorative materials and show better mechanical properties than other materials, but do not have the same effect on fluoride release. CLINICAL RELEVANCE: Most of the bioactive materials showed a decrease in the fluoride ion ratio after thermal aging, while no difference was found in the ion exchange of alkasite materials. Material selection should be made more carefully in caries-active individuals whose fluoride release is clinically important.

Evaluation of nanohardness, elastic modulus, and surface roughness of fluoride-releasing tooth colored restorative materials.

Recently, interest in tooth-colored fluoride-releasing dental materials has increased. Although physical and mechanical properties such as surface hardness, elastic modulus and surface roughness of the restorative materials have been investigated, the effect of different immersion media on these properties is still controversial. The aim of this study was to evaluate the nanohardness, elastic modulus and surface roughness of the fluoride release of tooth-colored restorative materials after immersion in acidic beverages. Prepared samples of three restorative materials (a highly viscous glass ionomer (EQUIA Forte; GC, Tokyo, Japan), a compomer (Dyract XP; Dentsply, Weybridge, UK), and a bioactive restorative material (Activa BioACTIVE; Pulpdent, MA, USA)) were randomly divided and immersed in distilled water, a cola and an orange juice for one week. The HYSITRON T1 950 TriboIndenter device (Hysitron, USA) with the Berkovich diamond indenter tip was used for all measurements. The nanohardness and elastic modulus of the samples were measured by applying a force of 6000 µN to five different points on the sample surface. Surface roughness measurements were evaluated on random samples by scanning five random 40 × 40 µm areas. The properties were measured at the initial and one week after immersion. The values of nanohardness, elastic modulus and surface roughness were tested for significant differences using a two-way analysis of variance (ANOVA) with repeated measures (p < 0.05). Tukey's honest significant difference (HSD) test was used for multiple comparisons. AB (Activa BioACTIVE) had the highest initial mean values for nanohardness. After post-immersion, the highest mean value for elastic modulus was the initial AB value. The lowest mean value for roughness of 100.36 nm was obtained for the initial DX (Dyract XP) measurement. Acidic beverages had a negative effect on the nanohardness, elastic modulus and surface roughness of the restorative materials.

Immediate and Long-Term Pull-Out Bond Strength of 3D-Printed Provisional Crowns.

Background: Over the past decade, 3D printing technology has revolutionized various fields, including dentistry. Provisional restorations play a crucial role in prosthetic rehabilitation, necessitating the evaluation of their bond strength with different provisional cement agents. Aims: This study is aimed at assessing the immediate and long-term bond strength of 3D-printed dental crowns using three provisional cement agents. Materials and Methods: Provisional crowns (N = 36) were manufactured using 3D modeling software and cemented in dentin analogues (G10 Nema resin). After the crowns' fabrication, they were randomly divided into three groups (n = 12) for cementation with Relyx Temp 3M ESPE, Provicol-VOCO, and Meron-VOCO. Tensile strength tests were conducted using a universal testing machine, with half of the specimens subjected to 2000 thermal cycles before testing. Finite element analysis was employed to assess tensile stress distribution. Results: Statistical analysis (two-way ANOVA and Tukey's test at a 95% confidence level) revealed significant effects of cement type (p = 0.006) and thermal aging (p = 0.001) on bond strength. Glass ionomer cement exhibited the highest immediate resistance, while all types of cement were adversely affected by thermal aging, resulting in decreased bond strength. Conclusion: Thermal aging significantly alters the properties of 3D printing resin and affects the bond strength of provisional cement with 3D-printed crowns. Despite the adverse effects of thermal aging, glass ionomer cement demonstrated the highest immediate resistance. Clinicians should carefully consider these findings when selecting provisional cements for 3D-printed crowns.

Impact of restorative material on fracture behaviors of class II restoration in endodontically treated deciduous molars.

The purpose of this study was to investigate the fracture behavior of endodontically treated (ET) deciduous molar when directly restored with different restorative materials in Class II (MO) cavities in comparison with permanent teeth. MO cavities were prepared with 2.4-2.5 mm and 1.9-2.0 mm in buccolingual width, and mesiodistal width of each cavity walls, respectively, followed by direct restoration with different materials: resin-modified glass ionomer cement (RMGIC), composite resin (CR), and composite resin containing 25% short glass-fiber (SFRC). All specimens were subjected to mechanical loading tests at a speed of 1 mm/min and evaluated fracture resistance and fracture modes. A one-way ANOVA followed by a Tukey multiple comparisons analysis was used. Deciduous-SFRC (3,310.5±396.2 N) were significantly higher fracture resistance than permanent-RMGIC (1,633.8±346.8 N) (p<0.001), and permanent-CR (1,400.0±381.3 N) (p<0.001). For the direct restoration of MO cavity after endodontic treatment, SFRC demonstrated its promising performance in load-bearing capacity and failure mode, especially in ET deciduous molars.

Incorporating nanosilver with glass ionomer cement-A literature review.

OBJECTIVES: The objectives of this study were to retrieve and review studies that incorporated nanosilver with GIC and summarise the evidence regarding the properties of nanosilver-modified GIC. MATERIALS AND METHODS: Two independent researchers performed a literature search using the keywords (nanosilver OR nano-silver OR (nano silver) OR (silver nanoparticles)) AND (GIC OR (glass ionomer cement) OR (glass ionomer cements)) in PubMed, Web of Science and ScienceDirect. RESULTS: A total of 368 articles were identified. After removing duplicate results, titles and abstracts were screened for eligibility. Full texts of publications that investigated the manufacture and properties of nanosilver-modified GIC were retrieved and analysed. Finally, 21 studies were included. CONCLUSIONS: All of the studies reviewed in this investigation included the incorporation of nanosilver in GIC. The proportions of nanosilver added into GIC varied from 0.05 % to 50 %. Thirteen studies investigated the antimicrobial properties of nanosilver-modified GIC; all studies supported that adding nanosilver enhanced antimicrobial effectiveness. Nineteen studies reported the mechanical properties including compressive strength, flexure strength, tensile strength, and microhardness of nanosilver-modified GIC; but the results were inconclusive. Four studies tested the bonding strength of nanosilver-modified GIC to dentine and found that adding nanosilver would not influence the bonding property of GIC. Some studies explored fluoride release level, colour stability, and cytotoxicity of nanosilver-modified GIC; but the results were all inconclusive. CLINICAL SIGNIFICANCE: This literature review is the first study to retrieve and summarise the findings and evidence regarding nanosilver-modified GIC research. It can provide clinicians with clinically relevant information about novel GIC materials that can be used in their treatment decisions.

Restoration-repair potential of resin-modified glass ionomer cement.

This in vitro study aimed to evaluate the repair bond strength of resin-modified glass ionomer cement using either the same material or a universal adhesive in the etch-and-rinse and self-etch modes plus resin composite. Twenty-four resin-modified glass ionomer cement blocks were stored in distilled water for 14 d and thermocycled. Sandpaper ground specimens were randomly assigned to three experimental groups according to the repair protocol: resin-modified glass ionomer cement (Riva Light Cure, SDI) and universal adhesive (Scotchbond Universal Adhesive, 3M Oral Care) in etch-and-rinse or self-etch modes and nanohybrid resin composite (Z350 XT, 3M Oral Care). After 24 h of water storage, the blocks were sectioned, and bonded sticks were subjected to the microtensile bond strength (µTBS) test. One-way ANOVA and Tukey's test were used to analyze the data. The failure mode was descriptively analyzed. The highest µTBS values were obtained when the resin-modified glass ionomer cement was repaired using the same material (p < 0.01). In addition, the mode of application of the universal adhesive system did not influence the repair bond strength of the resin-modified glass ionomer cement. Adhesive/mixed failures prevailed in all groups. Repair of resin-modified glass ionomers with the same material appears to be the preferred option to improve bond strength.

Glass ionomer cement particles pre-reacted with chlorhexidine: Physical/chemical properties and antimicrobial activity.

OBJECTIVE: Analyze the effects of the functionalization of pre-functionalized GIC particles with chlorhexidine on the physicochemical properties and antimicrobial activity. MATERIALS AND METHODS: Four groups were prepared: (1) GIC (Bioglass R - Biodinamica) - control group; (2) GIC-CHX 1%: Group containing 1% pre-reacted CHX particles; (3) GIC-CHX 2.5%: Group containing 2.5% pre-reacted CHX particles; (4) GIC-CHX 5%: Group containing 5% pre-reacted CHX particles. Hourglass-shaped specimens (10 mm × 2 mm x 1 mm) were fabricated for mechanical tests including cohesive strength (n = 12), modulus of elasticity (n = 12) and microhardness (n = 10). Discs (10 mm × 2 mm) were prepared for the analysis of Ca+2, PO4- and F- ions release (n = 3), and roughness (n = 12). To evaluate the setting time, a Gilmore needle was used according to ISO 9917-1:2016. Disk-shaped specimens (5 × 1mm) were manufactured and subjected to bacterial activity (n = 9) (Streptococcus mutans ATCC 159). RESULTS: Modulus, roughness, setting time and ions release (Ca+2, PO4-, and F-) there were no statistically significant differences among the groups (p > 0.05). The setting time did not change with the incorporation of CHX. The GIC-CHX 2.5% and GIC-CHX 5% groups exhibited superior antibacterial activity compared to the control group and GIC-CHX 1% (p < 0.001). The GIC-CHX 5% group showed the highest microhardness values (p < 0.041), cohesive strength (p < 0.009) when compared to the control group. CONCLUSION: The pre-reacted CHX in GICs was able to confer antimicrobial activity, improve cohesive strength, microhardness, and did not impair ion release, setting time, and roughness.

Improving the Mechanical Properties of Glass Ionomer Cement With Nanocrystalline Cellulose From Rice Husk.

This study aimed to evaluate the effect of incorporating nanocrystalline cellulose (NCC) sourced from rice husk on the mechanical properties of a commercial glass ionomer cement (GIC). NCC was isolated through acid hydrolysis, and its crystallinity, chemical structure, and morphology were characterized through x-ray diffractometry, Fourier-transform infrared spectroscopy, and transmission electron microscopy, respectively. Various concentrations of NCC (0%, 0.5%, 1%, and 1.5%) were added to reinforce the GIC matrix. Mechanical tests including compressive strength, flexural strength, hardness, and shear bond strength were conducted on the modified GIC samples. The addition of NCC resulted in increased hardness and shear bond strength values, with 1% NCC showing the highest values compared to other concentrations. However, there was no significant improvement observed in the compressive and flexural strength of the modified GIC. Failure mode test revealed a reduction in adhesive failure with the addition of NCC. Incorporating small amounts of NCC (0.5%-1%) suggests a promising and affordable modification of GIC restorative material using biomass residue, resulting in improved mechanical properties.

Prevention of secondary caries using fluoride-loaded chitosan nanoparticle-modified glass-ionomer cement.

OBJECTIVE: To study the effect of incorporating chitosan and fluoride-loaded chitosan nanoparticles into a glass-ionomer cement (GIC) to prevent secondary caries. MATERIALS AND METHODS: A standard cervical cavity (mesio-distal width 6 mm, cervico-occlusal width 2 mm, and depth 2 mm) was prepared on 30 molars for the following restoration groups: group 1, conventional GIC restoration; group 2, chitosan (10%) modified GIC restoration; group 3, fluoride loaded chitosan nanoparticles (10%) modified GIC restoration. The restored teeth were subjected to 1,500 thermal cycles before undergoing a multi-species cariogenic biofilm challenge. The restored teeth were examined by micro-computed tomography (micro-CT), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX). Data were analyzed by the one-way ANOVA, Tukey HDS, Kruskal Wallis, and Dunn's test. RESULTS: Micro-CT determined outer lesion depths for groups 1-3 were: 614 ± 20 µm, 589 ± 17 µm, and 560 ± 19 µm respectively. Both modifications with chitosan and fluoride-loaded chitosan nanoparticles significantly affected outer lesion depth (p < 0.05). The modification with fluoride-loaded chitosan nanoparticles statistically significantly decreased the outer lesion depth compared to all other groups (p < 0.05). SEM/EDX showed an increase of calcium, phosphorus, and fluoride at the root dentine adjacent to the restoration in groups 2 and 3 (modified GIC). This increase was statistically significantly higher in the group modified with fluorine-loaded nano chitosan particles compared to the other groups (p < 0.05). CONCLUSION: Incorporation of 10% chitosan and 10% fluoride-loaded chitosan nanoparticles into GIC restorative material can prevent secondary root caries development. 10% fluoride-loaded chitosan nanoparticles were more effective. CLINICAL SIGNIFICANCE: Glass ionomer cement modified with fluoride-loaded chitosan nanoparticles may be a promising restorative material in pediatric and preventive dentistry due to their controlled release properties.

[The effect of erbium laser pretreatment on bond strength between dentin and enamel and microleakage at the edge of CAD/CAM glass ionomer cement restorations for repairing tooth defects].

PURPOSE: To investigate the effects of erbium laser pretreatment on the bond strength of dentin and enamel,as well as microleakage at the edge of tooth defects repaired with computer-aided design (CAD) and computer-assisted manufacturing (CAM) glass-ceramic restorations for repairing dental defects. METHODS: A total of 62 fresh, nondecayed, nondiscoloration and noncracked wisdom teeth were collected from the Oral Surgery Clinic between January 2020 and January 2023. According to different pretreatment methods, they were randomly divided into two groups, erbium laser group and phosphoric acid group, with 31 teeth in each group. Each group was further divided into two subsets for bond strength testing (16 teeth) and microleakage testing (15 teeth).The shear bond strength between enamel and dentin of both groups was compared, as well as the degree and distribution of microleakage.Statistical analysis was performed with SPSS 17.0 software package. RESULTS: The shear bond strength between enamel and dentin of the erbium laser group was significantly higher than that of the phosphoric acid group (P＜0.05); the degree and distribution of microleakage at the lateral walls and gumline of the erbium laser group were significantly lower than those of the phosphoric acid group (P＜0.05). The scores of microleakage at the lateral walls of the erbium laser group mainly concentrated in grade 1 and 2, whereas those of the phosphoric acid group mainly concentrated in grade 2. There was significant difference in the distribution of lateral wall microleakage scores between the two groups (P＜0.05). The scores of microleakage at the gumline of the erbium laser group mainly concentrated in grade 1 and 2, whereas those of the phosphoric acid group mainly concentrated in grade 2 and 3. There was significant difference in the distribution of gumline microleakage scores between the two groups (P＜0.05). CONCLUSIONS: Erbium laser pretreatment can improve bonding strength between glass ionomer cement and dentin and enamel, reduce microleakage at the edge of CAD/CAM glass ionomer cement restorations, and enhance marginal fit.

Comparison of the physical properties of glass ionomer modified with silver phosphate/hydroxyapatite or titanium dioxide nanoparticles: in vitro study.

Glass ionomer cements (GICs) are the common materials employed in pediatric dentistry because of their specific applications in class I restorations and atraumatic restoration treatments (ART) of deciduous teeth in populations at high risk of caries. Studies show a limited clinical durability of these materials. Attempts have thus been made to incorporate nanoparticles (NPs) into the glass ionomer for improving resistance and make it like the tooth structure. An in vitro experimental study was conducted using the required samples dimensions and prepared based on the test being carried out on the three groups with or without the modification of light-cured glass ionomer. Samples were grouped as follows: control group (G1_C), 2% silver phosphate/hydroxyapatite NPs group (G2_SPH), and 2% titanium dioxide NPs group (G3_TiO2). The physical tests regarding flexural strength (n = 10 per group), solubility (n = 10 per group), and radiopacity (n = 3 per group) were performed. The data were analyzed by Shapiro Wilks test, and one-way analysis of variance (one-way ANOVA), and multiple comparisons by post hoc Tukey's test. The p-value of < 0.05 was considered significant. No statistically significant difference was observed between the control group (G1_C) and (G2_SPH) (p = 0.704) in the flexural strength test, however differences were found between G2_SPH and G3_TiO2 groups, ANOVA (p = 0.006); post hoc Tukey's test (p = 0.014). Pertaining to the solubility, G2_SPH obtained the lowest among the three groups, ANOVA (p = 0.010); post hoc Tukey's test (p = 0.009). The three study groups obtained an adequate radiopacity of >1 mm Al, respectively. The resin-modified glass ionomer cement (RMGIC) was further modified with 2% silver phosphate/hydroxyapatite NPs to improve the physical properties such as enhancing the solubility and sorption without compromising the flexural strength and radiopacity behavior of modified RMGIC. The incorporation of 2% titanium dioxide NPs did not improve the properties studied.

PH VALUE AND ANTIBACTERIAL EFFECT OF ALKASITE RESTORATIVE MATERIALS.

This (in vitro) investigation was conducted to evaluate PH value and antibacterial effect of Alkasite restorative materials against important oral pathogens Streptococcus mutans and lactobacillus plantarum. MATERIAL AND METHODS: Four groups were made of three different type ion releasing materials Cention N= group 1, Primer free Cention Forte=group 2, Primer applied Cention Forte=group 3 and Fuji IX= group 4. A total number of 72 discs in form samples (2 mm height and 5mm diameter) were constructed in polyethylene mold divided according to the evaluating parameters. 32 specimens for PH measurements (n=8) and 40 specimens were utilized for antibacterial effect (n=5) for each bacterial species. The antibacterial properties of groups were assessed by direct contact test. An adjusted diluted broth culture of each bacterium (Streptococcus mutans) and (Lactobacillus plantarum) were prepared. RESULTS: At all intervals of time both Cention N and Primer free Cention Forte has significantly higher PH value in comparison with Fuji IX. Primer applied Cention Forte. There was no significant difference between Cention N, Primer free Cention and Fuji IX in terms of their effect in reducing viable colony count in both bacterial species. CONCLUSION: Along period of (28day) Alkasite material groups (Cention N and Primer free Cention Forte) showed the ability to increase the storage solution PH value. Also, both groups have antibacterial effect against (Streptococcus mutans) and (Lactobacillus plantarum) by inhibiting their numbers. Applying Cention primer showed negative effect on both PH value and the antibacterial effect of the material.

Fracture Resistance and Push-Out Bond Strength of Three Post Types in the Restoration of Anterior Primary Teeth - A In Vitro study.

CONTEXT: Restoration fractures and displacement are the two main causes of failure after the rehabilitation of severely worn primary anterior teeth. AIMS: Compare the effect of three post types on the fracture and push-out bond strength. METHODS AND MATERIALS: Sixty undamaged maxillary anterior primary teeth were allocated into three groups according to post type: (I) Tetric N Ceram composite post, (II) prefabricated glass fiber post, and (III) high viscous glass ionomer post. Each group was further subdivided into two sub-groups depending on the test used: fracture resistance test and push-out bond strength test. The all specimens were mounted in acrylic resin blocks and tested using a universal testing machine. The fracture and failure mode were determined by a stereomicroscope inspection of all the specimens. Data were analyzed by one-way analysis of variance (ANOVA) and the Bonferroni post hoc test ( P < 0.05). RESULTS: There was a statistically significant difference between fracture resistance and push-out bond strength values for the experimental groups ( P < 0.05). The most significant fracture resistance value was in Group II and core/post fracture (restorable fracture) was the most obvious fracture in the three groups with the highest percentage in Group I. The most significant push-out bond strength value was in Group I and adhesive failure between dentin and luting cement/post was the most common type in the groups. CONCLUSIONS: The fracture resistance and push-out bond strength were affected by the type of post ( P = 0.000). Prefabricated glass fiber posts showed the highest fracture resistance in this study. However, Tetric N Ceram composite posts had the most restorable fracture. Tetric N Ceram composite posts had the highest bond strength with adhesive failure mode.

Long-term retention and survival of cemented implant-supported zirconia and metal-ceramic single crowns: A retrospective study.

OBJECTIVES: To evaluate the effect of different cement types on the incidence of failure and loss of retention of zirconia and metal-ceramic single crowns (SCs) cemented on implant abutments. METHODS: We placed 567 implant-supported SCs in 358 patients and retrospectively evaluated long-term retention for up to 12.8 years. The frameworks were made from metal alloy (n = 307) or zirconia (n = 260). SCs were cemented with permanent (glass-ionomer cement; n = 376) or semipermanent cement (zinc oxide non-eugenol cement; n = 191) on standardized (n = 446) or customized (n = 121) abutments. Kaplan-Meier curves were used to calculate the incidence of decementation. Differences between survival curves were assessed with log-rank tests. Cox-regression analysis was performed to evaluate multiple risk factors. RESULTS: Of the 567 SCs, 22 failed because of technical complications and four because of implant loss. Loss of retention was observed in 50 SCs. Analysis revealed a 7% probability of loss of retention for zirconia and 16% for metal-ceramic SCs after 10 years (p = .011). After 5 years, loss of retention was higher for standardized abutments than for customized abutments (p = .014). The probability of loss of retention was higher with semipermanent than with permanent cement (p = .001). Cox-regression analysis revealed semipermanent cement as the only significant risk factor for SC failure (p = .026). CONCLUSIONS: In contrast to semipermanent cement, permanent cement provides acceptable long-term retention of cemented implant-supported SCs. These possible positive effects of customized abutments have to be controlled with larger sample sizes.

Evaluating the physico-chemical properties of water-based and 2% lidocaine hydrochloride-based aluminum-free glass polyalkenoate cements for distal radius fixation.

Lidocaine hydrochloride is used as an anesthetic for clinical applications. This study considers the effects of the substitution of 2% lidocaine hydrochloride for deionized (DI) water on the rheological, mechanical, ion release, pH and injectable properties of two formulations of aluminum-free glass polyalkenoate cements (GPCs) using two distinct poly(acrylic) acids (PAA), E9 and E11, which have different molecular weights (Mw). The substitution of 2% lidocaine hydrochloride demonstrated increased injectability, but did not affect mechanical properties. The mechanical properties increased with time, as expected, and, in general, E9-based GPCs displayed significantly higher strengths over E11-based GPCs. With respect to ion release, which includes calcium (Ca), strontium (Sr), zinc (Zn) and silicon (Si); all ions displayed a steady and consistent increased release over time. Ca and Sr showed similar ion release patterns, whereby the GPC made with E11 PAA and lidocaine hydrochloride released significantly more ions than all other compositions likely due to similar chemical kinetics. However, Zn is also divalent in nature, but displayed only one significant difference across the GPC series at all time points, which was attributed to its higher electronegativity allowing for increased participation in the setting reaction. Finally, an analysis of the pH confirmed an increase in pH with time, suggesting that H+ ions were attacking the glass structure to allow for ion release. After 1 and 7 days, water-based GPCs environments achieved a higher pH than lidocaine hydrochloride-based GPCs, indicating that the lidocaine hydrochloride may be releasing additional protons upon bond formation with PAA.

A protocol for a comparative evaluation of the fracture resistance of endodontically treated teeth reinforced with Cention N, resin-modified glass ionomer cement (RMGIC) and short fiber reinforced flowable composite as an intraorifice barrier.

Background: Endodontic treatment is the most common method for resolving pulpal and periapical pathology. However, various studies have reported that almost 11%-13% of all teeth that undergo extraction after endodontic treatment show the presence of cracks, craze lines, and vertical root fractures. Teeth with inadequate post endodontic restoration are more prone to fracture and coronal leakage, resulting in the diffusion of oral fluids, bacteria, bacterial products, and possibly root canal treatment failure. Furthermore, studies have advocated the use of endodontically treated teeth with restorative materials that have a similar or higher elastic modulus than the tooth for providing stiffness against forces that cause root fracture. Intraorifice barriers made of restorative materials that can bond to radicular dentin could thus be used to reinforce the radicular dentin while also preventing coronal microleakage. Although the sealing ability of intraorifice barriers has been widely compared in the literature, there have been few studies on the strengthening effect of the materials used in the study as intraorifice barriers when placed into the root canal. As a result, the current in vitro study aims to assess the effect of various materials as intraorifice barriers (Cention N, Resin modified glass ionomer cement, and short fiber reinforced flowable composite) on the force required fracture teeth after root canal treatment. Methods: This in vitro study will be done on extracted human mandibular premolars with single root canal where after doing root canal treatment 2-3 mm obturating material would be replaced by intra orifice barriers (Cention N, resin modified glass ionomer cement [RMGIC], and short fiber reinforced flowable composite). The force required to fracture teeth will be calculated using universal testing machine.

Ion release of the glass ionomer restoration with silver diamine fluoride dentin pretreatment.

OBJECTIVE: To assess the fluoride and silver ion release of glass ionomer cement (GIC) restorations, including conventional GIC (CGIC) and resin-modified GIC (RMGIC) restorations, with 38 % silver diamine fluoride (SDF) solution dentin pretreatment. METHODS: Eighty dentin blocks were allocated into 4 groups and restored with SDF+CGIC, CGIC, SDF+RMGIC and RMGIC, respectively. Each block was stored in deionized water at 37 °C for 2 years. Fluoride and silver ion concentration in storage solution was measured using ion-selective electrode and inductively coupled plasma-optical emission spectrometry for up to 2 years. The cross-sectional surfaces of restored dentin blocks were assessed by X-Ray diffraction analysis (XRD), scanning electron microscope (SEM) with energy-dispersive X-ray spectroscopy (EDS) after 1 week and 2 years, respectively. RESULTS: The mean ± standard deviation (SD) of accumulative fluoride releasing in SDF+CGIC, CGIC, SDF+RMGIC and RMGIC for 2 years were 0.13±0.005 mg, 0.09±0.006 mg, 0.15±0.008 mg and 0.05±0.003 mg, respectively (Groups SDF+RMGIC > SDF+CGIC > CGIC >RMGIC, p < 0.05). The mean ± SD of accumulative silver releasing in SDF+CGIC, CGIC, SDF+RMGIC and RMGIC for 2 years were 0.03±0.009 mg, 0.00±0.00 mg, 0.01±0.003 mg, and 0.00±0.00 mg, respectively (Groups SDF+CGIC > SDF+RMGIC > CGIC&RMGIC, p < 0.05). Groups SDF+CGIC and SDF+RMGIC showed sustainably higher fluoride and silver releasing compared to Groups CGIC and RMGIC (p < 0.05). XRD analysis indicated the fluorapatite and silver chloride were observed only in Groups SDF+CGIC and SDF+RMGIC, but not in Groups CGIC and RMGIC. SEM images of the cross-sectional view of the dentin blocks showed silver crystals within dentinal tubules 1 week and 2-year in Groups with SDF pretreatment. CONCLUSION: The 38 % SDF dentin pretreatment sustainably increased the fluoride and silver release of GIC and RMGIC restorations for up to 2 years.