Clinical wear and quality assessment of monolithic and lithium disilicate layered zirconia restorations.

BACKGROUND: Wear and quality assessments of translucent monolithic zirconia and CAD-on® restorations were performed. METHODS: Forty 3-unit posterior fixed partial denture (FPD) in 18 patients (age:18-50 years) were made from translucent monolithic zirconia (tm) (Zenostar T) and zirconia-frameworked, lithium disilicate layered (c) (CAD-on), materials in a split-mouth design. Restorations were digitally fabricated and their internal and marginal adaptations were measured before cementation followed by luting (Multilink Speed). Clinical evaluations were made by modified United States Public Health Service criteria at baseline, 6, 12, and 24-months. Wear of the restorations and the antagonists were digitally evaluated after optical scanning of stone casts at 1st week and 24 m through a software (Cerec 4.4). Statistical analysis was made (analysis of variance, Shapiro-Wilk, Friedman and Wilcoxon tests (SPSS 20)) at α = 0.05 significance level. RESULTS: At 24 m, all restorations were clinically acceptable. Insignificant differences were found between tm and c restorations (P > 0.05). Mean internal and marginal adaptation of c restorations were significantly better (145 µm (premolar)-174 µm (molar)) than tm (190 µm (premolar)-207 µm (molar)) (P < 0.05). C restorations significantly caused more wear (0.3 ± 0.1 mm) than tm (0.1 ± 0.07 mm) on the antagonistic dentition (P < 0.05). CONCLUSIONS: Translucent monolithic zirconia restorations caused less wear and antagonist wear than CAD-on restorations. CAD-on restorations exhibited higher internal and marginal adaptation.

Colour stability of sectional laminate veneers: A laboratory study.

BACKGROUND: This study aimed to evaluate the colour stability of sectional laminate veneers (SLVs) fabricated with four and cemented with two different materials. METHODS: Eighty SLVs were prepared with a thickness of 0.2-0.4 mm from IPS e.max CAD, Lava Ultimate, CEREC Blocs and IPS InLine and were cemented with Variolink Veneer and Variolink N to form eight groups (n:10). After cementation, specimens underwent 5000 thermocyles prior to immersion in a coffee solution. RESULTS: Colour change before and after thermal cycling did not reveal significant differences (P > 0.05). After coffee immersion, significant colour change was observed in all groups (P > 0.05). Only IPS InLine cemented with Variolink Veneer was considered clinically acceptable (∆E < 3.3). According to observer scorings, marginal discolouration was higher in Lava Ultimate, while no discolouration was observed in IPS InLine. Dual or light-curing resin cements showed insignificant differences. CONCLUSIONS: SLVs fabricated with different aesthetic materials underwent perceptible (∆E > 3.3) discolouration except for the IPS InLine cemented with light-curing resin cement. Cementation with either dual-curing or light-curing resin cements does not by itself affect colour stability. The highest marginal discolouration was in the Lava Ultimate group while no discolouration was detected in the IPS InLine group.

The role of concentrated growth factor on implant stability: A preliminary study.

PURPOSE: The purpose of this preliminary study was to evaluate the effect of concentrated growth factor (CGF) on dental implant stability in type 2 bone using the resonance frequency analysis (RFA) device Smartpeg®. METHODS: The researchers carried out a prospective cohort study on a sample group composed of 12 patients (mean age=67) who required dental implants. Implant socket preparation (with and without CGF) was the primary predictor variable. In each patient, two dental implants were inserted in the anterior mandible. For the test group, one dental implant socket was covered with CGF membrane, while the other socket was prepared conventionally for the control group. Implant stability, as measured by RFA, was the outcome variable. Measurements were taken using the Ostell device at the time of implant placement and at the 1st, 2nd and 4th weeks. RESULTS: Mean implant stability quotients (ISQs) were 67.00±4.573 for the study group and 64.75±5.065 for the control group. The difference between the two groups was not statistically significant. CONCLUSION: It was found that CGF did not provide beneficial effect on dental implant stability in the early healing period in type 2 bone.

Nanoleakage inhibition within hybrid layer using new protective chemicals and their effect on adhesion.

Hybrid-layer degradation occurs because of acidic properties of currently used adhesive systems. Titanium tetrafluoride couples with tooth surface, and titanium compounds are not substituted. Caffeic acid phenethyl esther inhibits endogenous matrix metalloproteinases that cause hybrid-layer degradation. It was hypothesized that titanium tetrafluoride and caffeic acid phenethyl esther application on exposed dentine surfaces before adhesive applications would inhibit nanoleakage and hybrid-layer degradation without compromising the bond strength of the adhesives. In ultracut thin sections, human dentine-chemical agent-adhesive composite interfaces were observed under transmission electron microscope with complementary scanning electron microscopy. Microtensile bond strength tests were also accomplished. Titanium tetrafluoride and titanium tetrafluoride + caffeic acid phenethyl esther applications decreased bond strength values. Caffeic acid phenethyl esther showed decreased silver nitrate penetration for cements based on Bisphenol glycydilmethacrylate and methyl methacrylate, whereas cement based on 4-methacryloyloxyethyl trimellitate anhydride methyl methacrylate showed almost no infiltration. Caffeic acid phenethyl esther application before cementation could inhibit nanoleakage and biodegradation of the hybrid layer.