Effects of calcium hydroxide intracanal medicament on push-out bond strength of endodontic sealers: A systematic review and meta-analysis.

OBJECTIVE: To investigate the effect of calcium hydroxide intracanal medicament on the push-out bond strength of resin-based and calcium silicate-based endodontic sealers. METHODS: A comprehensive search of was conducted for all relevant in-vitro studies. All randomized controlled in-vitro studies that evaluated the effect of calcium hydroxide on the push-out bond strength of resin-based or calcium silicate-based endodontic sealers were assessed. The variables of interest were extracted, and the risk of the included studies was evaluated. The standardized mean difference was calculated and the significance level was set at p value <0.05. RESULTS: A total of 26 studies were eligible for analysis. There were 45 independent comparison groups and 1009 recruited teeth. The pooled data showed no significant difference in push-out bond strength between calcium hydroxide and control group in the resin-based group (SMD = 0.03; 95% CI = -0.55, 0.60; p = 0.93), and calcium silicate-based group (SMD = 0.02; 95% CI = -0.31, 0.35; p = 0.90). Most of the studies (21 out of 26) were at medium risk of bias and five studies showed a low risk of bias. CONCLUSION: The available evidence suggests that calcium hydroxide used as intracanal medication does not influence the push-out bond strength of the resin- and calcium silicate-based endodontic sealers. CLINICAL SIGNIFICANCE: The results of this meta-analysis suggest that calcium hydroxide used as intracanal medication does not influence the push-out bond strength of resin-based and calcium silicate-based endodontic sealers.

UV/Vis dose response of a reusable PMMA-NaCl polymer composite.

PURPOSE: Two-dimensional dosimeters are convenient tools for quickly checking the radiation profile in radiotherapy. The currently used solution is costly, especially in busy institutions with extensive quality control procedures. This study fabricates a reusable 2-mm-thick PMMA-NaCl polymer composite sheet and assesses its dosimetric properties. METHODS: The PMMA-NaCl composite sheets were prepared using hot melting procedures. For dosimetric evaluations, the samples were irradiated using 6 MV X-ray photons from a medical linac. The absorbed doses were measured as changes in the optical absorption spectrum using a UV-Vis spectrometer. RESULTS: The lowest dose detected by the samples was 5 Gy, with a linear dose response of at least 20 Gy. The repeatability of the measurements was good, with a standard deviation of 5.03%. The signal was bleachable by using a 100 W filament-type lamp for dosimetric reuse. CONCLUSION: The 2-mm-thick PMMA-NaCl polymer-composite sheet could measure absorbed radiation doses from 6 MV X-ray photons down to 5 Gy. Because the sample is reusable, it can be used in a cost-effective two-dimensional radiation dosimeter to ensure the quality of medical linacs.

A review of bioceramics scaffolds for bone defects in different types of animal models: HA andß-TCP.

Increased life expectancy has led to an increase in the use of bone substitutes in numerous nations, with over two million bone-grafting surgeries performed worldwide each year. A bone defect can be caused by trauma, infections, and tissue resections which can self-heal due to the osteoconductive nature of the native extracellular matrix components. However, natural self-healing is time-consuming, and new bone regeneration is slow, especially for large bone defects. It also remains a clinical challenge for surgeons to have a suitable bone substitute. To date, there are numerous potential treatments for bone grafting, including gold-standard autografts, allograft implantation, xenografts, or bone graft substitutes. Tricalcium phosphate (TCP) and hydroxyapatite (HA) are the most extensively used and studied bone substitutes due to their similar chemical composition to bone. The scaffolds should be testedin vivoandin vitrousing suitable animal models to ensure that the biomaterials work effectively as implants. Hence, this article aims to familiarize readers with the most frequently used animal models for biomaterials testing and highlight the available literature forin vivostudies using small and large animal models. This review summarizes the bioceramic materials, particularly HA andß-TCP scaffolds, for bone defects in small and large animal models. Besides, the design considerations for the pre-clinical animal model selection for bone defect implants are emphasized and presented.

New bioactive glass-ceramic: synthesis and application in PMMA bone cement composites.

In present study, a new composition of glass-ceramic was synthesized based on the Na2O-CaO-SiO2-P2O5 glass system. Heat treatment of glass powder was carried out in 2 stages: 600 °C as the nucleation temperature and different temperature on crystallization at 850, 950 and 1000 °C. The glass-ceramic heat-treated at 950 °C was selected as bioactive filler in commercial PMMA bone cement; (PALACOS® LV) due to its ability to form 2 high crystallization phases in comparison with 850 and 1000 °C. The results of this newly glass-ceramic filled PMMA bone cement at 0-16 wt% of filler loading were compared with those of hydroxyapatite (HA). The effect of different filler loading on the setting properties was evaluated. The peak temperature during the polymerization of bone cement decreased when the liquid to powder (L/P) ratio was reduced. The setting time, however, did not show any trend when filler loading was increased. In contrast, dough time was observed to decrease with increased filler loading. Apatite morphology was observed on the surface of the glass-ceramic and selected cement after bioactivity test.