^{June 2024 Abstracts}

The effect of different deep margin elevation methods on the fracture strength of CAD-CAM restorations

 

Şeyma Nilgün Balcı, ra, Neslihan Tekçe, dds, phd, Safa Tuncer, dds, phd  &  Mustafa Demirci, dds, phd

 

Abstract: Purpose: To evaluate the effect of two resin composites (with different viscosities) and the elevation amount on fracture strength and fracture behavior of molars with and without deep margin elevations (DME). Methods: 70 extracted, caries-free human molars were selected. All teeth were prepared as MOD onlay cavities with a margin 2 mm below the cemento-enamel junction (CEJ) on the mesial and buccal sides and 2 mm above the CEJ on the distal side. The teeth were divided into two groups according to the type of resin composite used in margin elevation, elevated with flowable composite (Universal Flo) or condensable composite (G-Aenial Posterior). These two groups were further subdivided into subgroups in which the elevation was 2, 3, or 4 mm, and a control group in which the non-elevated indirect restoration was directly bonded to the subgingival margin, making a total of seven groups (n= 10). After elevations, the restorations were completed using a nanoceramic CAD-CAM block (Cerasmart A3 HT) and as adhesive cement, G-Cem Link Force. Static force was applied to the restored teeth using a universal testing machine at an angle of 15° until fracture occurred. Fracture strength values were recorded, and fracture types were examined under 6× magnification. One-way ANOVA was carried out to determine the effect of DME on the fracture strength. A two-way ANOVA was conducted to investigate main and interaction effects of the material type used in the elevation and the amount of elevation made on the fracture strength (P< 0.05). Results: Using flowable or condensable composite as elevation material did not affect the fracture strength of CAD-CAM restorations. Flowable and condensable composites of 2, 3, or 4 mm did not significantly affect fracture strength values for either material. Specimen margins with and without elevation exhibited similar fracture strength values. The type of material used in the elevation and the amount did not affect the fracture strength of teeth. (Am J Dent 2024;37:115-120).

 

 

 

 

 

 

 

Mail: Şeyma Nilgün Balcı, Department of Restorative Dentistry, Faculty of Dentistry, University of Kocaeli, Kocaeli, Turkey. E-mail: seyma.nilgun@gmail.com

 

 

Sandblasting increases the microtensile bond strength between resin and sclerotic dentin in noncarious cervical lesions

 

Guilian Zhang, md,  Wensheng He, dd,  Ning Ding, bd,  Ying Su, bd   &   Guoxia Yu, dd

 

Abstract: Purpose: To evaluate the effect of sandblasting on the microtensile strength between sclerotic dentin and resin composite. Methods: 32 premolars with noncarious cervical lesions (NCCLs) were collected, and the teeth were randomly assigned to the control group (C group) and the sandblasted group (S group). Teeth in the S group were sandblasted with 110 μm Al₂O₃ particles at a pressure of 75 psi, while those in the C group received no further treatment. The characteristics of the tooth surface were observed by scanning electron microscopy (SEM), and the relative area of open dentin tubules (OTs) was calculated by IPP6.0 software. Surface roughness (Ra) was also assessed. The noncarious cervical lesions of all teeth were restored with a resin composite and subsequently sectioned into sticks to measure the microtensile bond strength (μTBS). Results: The mean ± SD μTBS (in MPa) of the sandblasted group was 17.9 ± 0.69 and 14.23 ± 0.44 in the control group (P< 0.05). The relative area of OTs at the gingival wall of the sandblasted group was 69.74 ± 5.23%, and 47.24 ± 7.67% in the control group (P< 0.05). The average surface roughness (μm) was 1.01 ± 0.05 in the sandblasted group and 0.16 ± 0.03 in the control group. Sandblasting could increase the bond strength of sclerotic dentin and resin restorations. (Am J Dent 2024;37:121-125).

 

 

 

 

 

 

 

 

Mail: Dr. Guoxia Yu, Department of Stomatology, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Nalishi Road 56, Xicheng District, Beijing, China,10045.  E-mail: yuguoxia@bch.com.cn

 

Effects of natural products-based dentifrices on acrylic resin for denture bases: A simulated period of 4 years

 

Marcela Silva Costa, msc,  Marcela Silva Fernandes, dds,  Viviane de Cássia Oliveira, phd, Evandro Watanabe, phd,  Cláudia Helena Lovato da Silva, phd,  Andréa Cândido dos Reis, phd, César Penazzo Lepri, phd  &  Denise Tornavoi de Castro, phd

 

Abstract: Purpose: To evaluate the antimicrobial activity of dentifrices based on Malva sylvestris and propolis and the effect on the acrylic resin. Methods: The inhibitory effect against Candida albicans, Enterococcus faecalis and Streptococcus mutans was determined. The specimens of resin were divided into groups: Control (brushing with distilled water); brushing with Colgate; brushing with Protex; brushing with Malvatricin, brushing with Proporalcare Dental Gel and brushing with Green Propolis Dental Gel. Brushing was carried out in a brushing machine. Roughness and color were assessed. The data were analyzed by ANOVA, followed by the Bonferroni post test (α= 0.05). Results: The products evaluated showed antimicrobial activity against all microorganisms (P< 0.05), except Proporalcare Dental Gel, which was not effective against E. faecalis. Greater roughness (P< 0.05) was observed in the samples treated with Colgate. The samples from control and Protex groups showed the lowest color variation and the highest luminosity, with a difference in relation to the others (P< 0.05), which showed higher values, although clinically acceptable. (Am J Dent 2024;37:126-130).

 

 

Mail: Dr. Denise Tornavoi de Castro, Faculty of Dentistry, Biomaterials Division, University of Uberaba, Av. Nenê Sabino, 1801, 2D06 – Universitário,  38055-500, Uberaba, MG, Brazil.  E-mail: denise.castro@uniube.br

 

miR-221-3p as a potential biomarker of chronic periodontitis and its regulatory effect on inflammatory response

 

Jiajun Qi, ba,  Qianqian Gui, ms,  Weizhong Lu, ba,  Chao Meng, ba   &  Mei Liu, ba

 

Abstract: Purpose: To explore the function of miR-221-3p in the development and course of chronic periodontitis (CP) and offer a fresh avenue for CP diagnosis and management. Methods: miR-221-3p expression was detected by RT-qPCR. The clinical diagnostic value of miR-221-3p in CP patients was analyzed by receiver operating characteristic (ROC). ELISA was used to determine the IL-1β and IL-6 in CP subjects and healthy controls. Pearson correlation analysis was performed with miR-221-3p. PDLCs were induced by LPS, transfected with miR-221-3p mimics, and their expression was analyzed for the effects of IL-1β, and IL-6. Results: The miR-221-3p expression was lower in the gingival sulcus fluid GCF of CP subjects compared to healthy controls. miR-221-3p showed high potential for clinical diagnosis in CP patients by ROC analysis, with high specificity and sensitivity. miR-221-3p was negatively correlated with Probing pocket depth (PD), Attachment loss (AL), Plaque index (PI), and Bleeding index (BI), and negatively correlated with inflammatory factors IL-1β and IL-6. In LPS-induced PDLCs, IL-1β and IL-6 were significantly increased, whereas miR-221-3p was significantly downregulated. Overexpression of miR-221-3p inhibited the production of inflammatory factors IL-1β and IL-6 in LPS-induced PDLCs. (Am J Dent 2024;37:131-135).

 

 

 

 

Mail: Dr. Mei Liu, Department of Stomatology, Central Hospital of Fengxian District, No. 6600, Nanfeng Road, Fengxian District, Shanghai 201499, China. E-mail: Meiliustom@163.com

 

Effect of primer compositions on the bond strength of resin cement to ceramic materials

 

Dilan Kopuz, dds,  Özlem Erçin, dds,  Engin Saçu,  Göktuğ Yersel  &  Neslihan Tekçe, dds, phd

 

Abstract: Purpose: To investigate the effect of different chemical compositions of primers on the bond strength between nano-ceramic, polymer-infiltrated ceramic, and zirconia ceramic materials and dual-cure cement. Methods: Fifty 2 mm-thick specimens were prepared from Vita Enamic, Cerasmart, and Katana Zirconia UTML. The specimens were embedded in acrylic blocks. To standardize the surfaces, 600 grit silicon carbide abrasives were applied underwater for 60 seconds. Then, each section underwent grit-blasting using Al₂O₃ with a particle size of 50 μm at 10 mm and a pressure of 2 bar for 10 seconds. Each prepared sample from the experimental groups received the appropriate primer (Z-PRIME Plus, G-Multi Primer, Alloy Primer, Clearfil Primer Plus) according to the manufacturers’ instructions. Subsequently, the prepared CAD-CAM specimens underwent cementation using Duo-Link Universal Adhesive Resin Cement with a cylinder mold of 2.6 mm diameter and 3 mm height. The cement was light-cured for 20 seconds from both sides. The specimens obtained were stored in distilled water at 37°C for 24 hours. The shear bond strength test of the specimens was performed using a Bisco Shear Bond Tester device. The data were statistically analyzed using ANOVA and the Kruskal-Wallis test (P< 0.05). Results: The highest bond strength was observed in Z-Prime Plus applied specimens, regardless of material differences (Cerasmart 11.60±4.61; Vita Enamic 12.93±3.86; Katana Zirconia 13.85±4.00). The lowest bond strength, showing differences according to materials (P< 0.05), was found for Clearfil Ceramic Primer Plus-Cerasmart (7.88±3.90), Alloy Primer-Vita Enamic (7.90±2.14), and G Multi Primer-Katana Zirconia UTML (4.98±3.67). (Am J Dent 2024;37:136-140).

 

 

 

 

Mail: Dr. Dilan Kopuz, Department of Restorative Dentistry, Faculty of Dentistry, Istanbul Kent University, Istanbul, Turkey. E-mail: dilan.kopuz@kent.edu.tr

Effect of different polishing methods on roughness and color stability of air-abraded restorative materials after artificial accelerated aging

 

Mahmut Sertac Ozdogan, dds, phd,  Gokce Unsal, dds, phd,  Kubra Aybuke Aydemir, dds,  Mine Tural, dds &  Filiz Aykent, dds, phd

 

Abstract: Purpose: To evaluate the effect of air abrasion and polishing procedures on roughness and color stability of ceramic and composite materials after artificial accelerated aging. Methods: In this study, six restorative materials were tested: feldspathic ceramic (CEREC Blocks), glass ceramic (IPS e.max CAD), resin-based hybrid ceramic (Cerasmart), microhybrid composite (Charisma Classic), nanohybrid composite (Charisma Diamond) and nanoceramic composite (CeramXOne). Forty square-shaped composite specimens were fabricated from each composite and CAD-CAM ceramic material. Initial surface roughness measurements were performed using a profilometer and color measurements of each specimen with a spectrophotometer. Ten control specimens for each group did not receive air abrasion. The other specimens were treated by an air abrasion device and then were randomly divided into three subgroups of 10 specimens (n= 10). After air abrasion, 10 specimens of each group did not receive polishing (Air abrasion group) and others were repolished with Sof-Lex kit (Sof-Lex group) or a rubber kit (Rubber group). Surface roughness and color measurements were repeated before and after 300 hours of artificial accelerated aging (AAA). The univariate test and then three-way ANOVA and two-way ANOVA were performed for comparison of groups (α= 0.05). Results: The univariate statistical analysis revealed that the restorative materials were differently affected after air abrasion, polishing methods and AAA (P< 0.001). Three-way ANOVA showed that the surface roughness of the restorative materials increased after air abrasion and AAA (P< 0.001). Two-way ANOVA showed statistically significant differences between color changes of ceramic (CEREC and IPS e.max CAD) and composite based restorative materials (P< 0.001). (Am J Dent 2024;37:141-146).

 

 

 

 

 

 

Mail: Dr. Mahmut Sertac Özdoğan, Department of Prosthodontics, Faculty of Dentistry, Ankara Yıldırım Beyazıt University, Etlik Campus, Ankara, Turkey. E-mail: msozdogan@aybu.edu.tr

 

Comparison of surface properties of universal shade and conventional resin-based composites after degradation and repolishing

 

Mayumi Maesako, dds, phd,  Nagisa Matsui, dds,  Morioki Fujitani, dds, phd, Franklin Garcia-Godoy, dds, ms, phd, phd   &  Akimasa Tsujimoto, dds, phd

 

Abstract: Purpose: To investigate the discoloration, line roughness and gloss of conventional and universal shade resin-based composites. Methods: Clearfil AP-X (AP-X) and Estelite Sigma Quick (EQ) samples were prepared. Discoloration, roughness, and gloss were measured on mirror-polished, alkaline-degraded, and repolished surfaces. The superficial layer degraded by alkaline immersion (degraded layer) was ground off from the sample surface. After removing the degraded layer, the surface was polished with aluminum oxide powder (1.0 μm and 0.3 μm), to create a repolished specimen. Scanning electron microscopy observations were made of the specimens. Results: The results were compared with those for Omnichroma (OC) from a previous study. All the materials showed different responses to degradation and repolishing, but repolishing of AP-X, for surface roughness and gloss, was more effective at restoring pre-degradation properties. Repolishing effectively removed discoloration in all materials. (Am J Dent 2024;37:147-153).

 

 

 

Mail: Prof. Akimasa Tsujimoto, 2-11 Suemori-dori, Chikusa-ku, Nagoya 464-8651, Japan.  E-mail: aki-tj@dpc.agu.ac.jp

 

 

Modeler liquids: Effect on the cohesive strength, color and staining resistance of stratified resin composite restorations

 

Bárbara Sousa Mello, dds,  Waldemir Francisco Vieira-Junior, dds, ms, phd,  Roberta Tarkany Basting, dds, ms, phd, Fabiana Mantovani Gomes França, dds, ms, phd  &  Cecilia Pedroso Turssi, dds, ms, phd

 

Abstract: Purpose: To evaluate the effect of filled and unfilled modeler liquids on the cohesive strength and color stability when applied in between the resin composite layers in the stratification technique and on the uppermost surface layer. Methods: For the cohesive strength test (n= 10), 30 cylindrical samples were packed into a Teflon mold (6×2 mm) in 2 mm increments. Firstly, a dentin-shade resin composite (Empress Direct) was placed, followed by the accommodation of a body-shade resin composite (Filtek Z350 XT) and an enamel-shade resin composite (Estelite Omega. Before photoactivation of each increment, an unfilled (Signum Liquid) or filled (Modeling Resin) modeler liquid was applied between the first and second layers and on the uppermost surface layer. The control group (n= 10) did not receive modeler liquid. Cohesive strength was measured in a universal testing machine. For the color test (n= 10), the other 30 samples were fabricated for the cohesive strength test, except for the difference in the diameter (6×6 mm). Before and after the staining of the samples, color was measured using the CIEL*a*b* system with a spectrophotometer (EasyShade). Data were submitted to ANOVA, Kruskal-Wallis test, or Mann-Whitney test (α= 5%). Results: Modeler liquids significantly increased cohesive strength (P= 0.008), while ΔE_ab (P= 0.003) and ΔE₀₀ (P= 0.005) values presented significantly lower changes for the groups that received modeler liquids, with no significant difference between unfilled and filled modeler liquids. (Am J Dent 2024;37:154-158)

 

 

 

 

Mail: Prof. Cecilia Pedroso Turssi, São Leopoldo Mandic Dental Research Institute and Center, Rua José Rocha Junqueira, 13 - CEP 13045-755, Campinas, SP, Brazil.  E-mail: cecilia.turssi@slmandic.edu.br

Effects of different polishing procedures on the color stability of recent resin composites

 

Esra Özyurt, dds, Aliye Tansu Akçağlar, dds  &  Ekin Görkem Uysal Uzel, dds

 

Abstract: Purpose: To evaluate different polishing methods’ effects on the color stability of recent resin composites. Methods: 160 samples for color stability evaluation and 40 samples for the degree of conversion evaluation were prepared with four different resin composites [Harmonize (H), Filtek Universal (F), Omnichroma (O), Essentia Universal (E)] and light cured. For color stability evaluation, samples prepared from each resin composite were divided into four groups: three polishing procedures and a control group. The ΔE₀₀ was calculated between initial, and after immersion in coffee solution for 12 days. The degree of conversion was evaluated with Fourier Transform Infrared Spectroscopy. The statistical analysis of ΔE₀₀ values was made with the two-way ANOVA, Tukey HSD, and Tamhane’s T2 tests. One-way ANOVA and Tukey HSD tests were used to compare the degree of conversion values (P< 0.05). Results: In all composite groups, mylar (control) groups had the highest ΔE₀₀, and no differences between other polishing procedures. According to the polishing procedures, Omnichroma showed the highest ΔE₀₀ values (on mylar groups O vs F, P< 0.001; O vs H, P< 0.001; O vs E, P< 0.001). There was a significant difference between the composite groups in terms of the degree of monomer conversion (P< 0.05). Omnichroma showed, significantly, the highest discoloration. (Am J Dent 2024;37:159-163).

 

 

 

 

 

 

Mail: Dr. Esra Özyurt, İzmir Training Dental Hospital, Department of Restorative Dentistry, İzmir, Turkey. E-mail: dr.esraozyurt@gmail.com

 

Influence of different abutment materials on the color of implant-supported restoration: A laboratory study

 

Tingting Wang, mds,  Yue Hu, mds,  Lan Jia, bds  &  Lijuan Ye, mds

 

Abstract: Purpose: To investigate the effect of different abutments and crowns on the color of implant-supported restorations. Methods: Zirconia and lithium disilicate (e.max) disks with A2 shade were fabricated to represent two crowns. The implant abutments were untreated titanium, opaqued titanium, anodized titanium, A2 shade zirconia and white zirconia. 4.0 mm-thickness zirconia and e.max specimens were used as references respectively. The crowns were placed on tested abutments with a drop of clear glycerin between them and the color was measured using a digital spectrophotometer. CIELab values were recorded to evaluate color differences (DE) between tested specimens and the references. Results: Titanium abutments presented higher color differences than zirconia. The DE values with untreated titanium were higher than those with opaqued titanium. No differences were found between untreated titanium and anodized titanium for zirconia crowns. The DE values of zirconia crowns showed no significant differences between shade A2 zirconia and white zirconia abutments; e.max crowns showed a significant difference. The zirconia crown DE values were lower than those of e.max for all titanium and A2 zirconia abutments. Lithium disilicate crowns and zirconia abutments may be more suitable for implant-supported restorations. Opaqued titanium abutment may improve color in esthetic regions when a ceramic abutment cannot be used. (Am J Dent 2024;37:164-168).

 

 

 

 

 

 

Mail: Dr. Liyuan Ye, 280 Mohe Road, Shanghai, 201999, China.  E-mail: 2001wtt@sina.com; Mail: Dr. Lan Jia, 280 Mohe Road, Shanghai, 201999, China.  E-mail: ad540894098@126.com