PURPOSEBacterial adhesion on provisional crown materials retained for a long time can influence the duration for which permanent prosthetic restorations can be healthily worn in the oral cavity. The aim of this study was to compare seven different commonly used provisional crown materials with regard to Streptococcus mutans and Candida albicans surface adhesion.MATERIALS AND METHODSFor each group, twenty specimens of the provisional fixed prosthodontic materials TemDent (Schütz), Imıdent (Imıcryl), Tab 2000 (Kerr), Structur Premium (Voco), Systemp (Ivoclar Vivadent), Acrytemp (Zhermack), and Takilon-BBF (Takilon) were prepared (diameter, 10.0 mm; height, 2.0 mm). Surface roughness was assessed by atomic force microscopy. Each group was then divided into 2 subgroups (n=10) according to the microbial suspensions used: S. mutans and C. albicans. The specimens were incubated at 37℃ with S. mutans or C. albicans for seven days. Bacterial adherence on surfaces was assessed using the 2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) assay.RESULTSS. mutans showed maximum adhesion to Structur, followed by Systemp, Acrytemp, Takilon, Tab 2000, Imident, and TemDent (P<.05). The highest vital C. albicans adhesion was noted on Takilon, followed by Imident and Tab 2000; the lowest adhesion was noted on Systemp (P<.05).CONCLUSIONThe materials showed significant differences in the degree of bacterial adhesion. C. albicans showed higher surface adhesion than S. mutans on provisional crown and fixed partial denture denture materials.

No abstract

Introduction: The aim of this study was to evaluate the effect of different heights of attachment and mucosa thicknesses on the stress distribution of two implant-retained mandibular overdenture designs under loading using the photoelastic stress analysis method. Materials and methods: Six photoelastic models of an edentulous mandibula were fabricated with two solitary implants that were placed in the canine regions. The attachment systems studied were ball and locator stud attachments. Both the ball and locator groups included three models that had different residual ridge heights so as to provide different mucosa thicknesses (1 mm–1 mm, 1 mm–2 mm, 1 mm–4 mm). A static vertical force of 135 N was applied unilaterally (each on the right then the left side) to the central fossa of the first molars. Models were positioned in the field of a circular polariscope to observe the distribution of isochromatic fringes around the implants and the interimplant areas under loading. The photoelastic stress fringes were monitored and recorded photographically. Results: The ball attachment groups showed higher stress values than did the locator groups under loading. Both attachment systems produced the lowest stress values in stimulated 1 mm–1 mm mucosa thickness models. The models with 1 mm–2 mm mucosa thicknesses showed higher stress values than did other models for both attachment systems. The highest stress value observed around both attachment systems was the moderate level in all test models. Conclusion: In different height mucosa thicknesses, locator attachment models distributed the load to the other side of the implant and its surrounding tissue, whereas the ball attachment did not. Regardless of mucosal thickness and attachment type, the implant on the loading side was subjected to the highest stress concentration.

Background. The surface properties of implants are effective factors for increasing the osseointegration and activity of osteoprogenitor cells. This study compared the stability of dental implants with sandblasted and acid-etched (SLA) and modified surfaces (SLActive) using the resonance frequency analysis (RFA). Methods. In a split-mouth design, 50 dental implants with either SLA surface properties (n=25) or modified (SLActive) surface properties (n=25) were placed in the mandibles of 12 patients with a bilateral posterior edentulous area. Implant stability was measured using RFA (Osstell) at implant placement time and every week for 1, 2, and 3 months before the conventional loading time. Results. One week following the implantation, implant stability increased from 70 to 77.67 for SLA and from 71.67 to 79 for SLActive (P<0.05). Stability improved each week except in the 4th week in SLActive surface measurements. No significant differences were observed between the groups at 2 and 3 months (P>0.05). Conclusions. For both implant surfaces, increased stability was observed over time, with no significant differences between the groups.

Objective: Ceramic glazing and polishing are important for patient satisfaction and long-term clinical success. Till date, no study has compared color changes after glazing procedures between conventional and more recently introduced ceramics. In this study; we investigated the effects of glazing procedures on the color stability of conventional and CAD/CAM hybrid ceramics using a spectrophotometer. Materials and Methods: Eighty-four disc-shaped specimens were fabricated with seven different dental porcelain materials according to the manufacturers' instructions (n = 12 each): Ivoclar IPS DSign, Vita Omega 900, Ceramco III, Vita Mark II, Vita Enamic, GC Cerasmart, and Vita Suprinity. Both sides of the specimens were polished with wet 600-, 1000-, and 1500-grit aluminium oxide abrasive papers, and color values (L*, a*, b*) were measured using a spectrophotometer before and after glazing. Treatmentinduced changes in the specimen color and topography were evaluated and recorded. The color change (∆E) was calculated from the changes in the mean L*, a*, and b* values. All data were analyzed using Kruskal-Wallis, Mann-Whitney U, and Wilcoxon tests (95% confidence level). Results: Color changes were below the clinically perceptible level (∆E, <3.7) in all specimens. Color change values after the glazing procedures were 2.27 ± 0.55, 2.99 ± 0.67, 1.01 ± 0.58, 1.62 ± 0.70, 0.74 ± 0.45, 1.35 ± 0.52, and 1.37 ± 0.72 for Ivoclar IPS DSign, Vita Omega 900, Ceramco III, Vita Mark II, GC Cerasmart, Vita Enamic, and Vita Suprinity, respectively; thus, there were significant differences between the conventional and CAD/CAM ceramics (p<0.05). The conventional ceramic Vita Omega 900 presented the least color stability, while the CAD/CAM ceramic GC Cerasmart presented the maximum color stability. Conclusions: Glazing procedures do not cause evident changes in the color of conventional and CAD/CAM hybrid ceramics, although the color stability of the latter is better than that of the former.Amaç: Seramik glaze ve parlatma işlemleri hasta memnuniyeti ve uzun süreli klinik başarı için önemlidir. Bugüne kadar hiçbir çalışma, geleneksel ve daha yeni tanıtılan seramikler arasındaki glaze işlemlerinden sonra renk değişimlerini karşılaştırmamıştır. Bu çalışmada glaze prosedürlerinin bir spektrofotometre kullanarak geleneksel ve CAD/ CAM hibrit seramiklerin renk stabilitesi üzerindeki etkilerini araştırılmıştır.

Self-adhesive resin cements (RCs) activate matrix metalloproteinase (MMP) and cathepsin-related collagen degradation, and gallic acid (GA) inhibits the activity of both MMPs and cysteine cathepsins. The purpose of this study was to evaluate the setting time, biaxial flexural strength, and Vickers hardness of self-adhesive RCs after the addition of two different concentrations of GA. RelyX U200 (3M ESPE) and Panavia SA (Kuraray) were modified with 0.5 and 1 wt% GA. The setting time of five samples in each RC group was assessed using a thermocouple apparatus as described in the ISO 4049 test. Biaxial flexure strength was measured using a universal testing machine until failure. Vickers hardness was measured with three randomized indentations on the surface of each resin disc. RCs without GA were used as control.Data were analyzed using a one-way analysis of variance and Tukey's HSD test (α = 0.05). The setting times ranged from 2.4 to 4.6 min for RelyX and from 4.9 to 6.0 min for Panavia. The biaxial flexure strength ranged from 76.5 to 109.7 MPa for RelyX and from 73.3 to 108.2 MPa for Panavia. Vickers hardness values ranged from 41.6 to 58.6 for RelyX and 27.2 to 33.6 for Panavia. The addition of 0.5 and 1 wt% GA to improve durability of resin-dentin bonds had no adverse effects on setting time, whereas the biaxial flexure strength and Vickers hardness values for the tested materials were significantly reduced.

No abstract

No abstract