Development and validation of a risk-of-bias tool for assessing in vitro studies conducted in dentistry: The QUIN.

STATEMENT OF PROBLEM: Systematic reviews and meta-analyses have emerged as forerunners of evidence-based dentistry, but assessing the quality of the available research is essential so that it can be applied to clinical practice. While a wide variety of risk-of-bias tools are available, each specifically developed for different study designs, a comprehensive tool exclusively framed to assess the quality of in vitro dental studies is lacking. PURPOSE: The purpose of this study was to develop and validate a tool to evaluate the quality and risk of bias of in vitro dental studies. MATERIAL AND METHODS: A Delphi panel was established to conceptualize and develop the Quality Assessment Tool For In Vitro Studies (QUIN Tool). The tool was evaluated by using content validity and reliability testing methods. RESULTS: The QUIN Tool includes 12 points along with scoring and grading options to allow clinicians to evaluate the quality of in vitro studies. This tool shows good content validity and reliability. CONCLUSIONS: The QUIN Tool is user-friendly, efficient, and effective for evaluating the risk of bias of in vitro studies.

Effect of different finish line preparations on the marginal and internal adaptation of cobalt-chromium metal alloy copings fabricated by using CAD-CAM technology: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: The marginal and internal adaptation of a fixed dental prosthesis depends on a variety of factors, finish line designs being one of them. A clear consensus as to which finish line design can provide a better marginal and internal adaptation with respect to cobalt-chromium metal alloy copings fabricated by using computer-aided design and computer-aided manufacturing (CAD-CAM) technology is lacking. PURPOSE: The purpose of this systematic review and meta-analysis was to evaluate the effect of different finish line preparations on the marginal and internal adaptation of cobalt-chromium metal alloy copings fabricated by using CAD-CAM technology. MATERIAL AND METHODS: Electronic (PubMed, Cochrane, EBSCOhost, and Google Scholar) and manual searches were conducted for articles published from January 2010 to December 2020 to identify relevant studies evaluating the effect of different finish line preparations (chamfer, deep chamfer, shoulder, rounded shoulder) on the marginal and internal adaptation of cobalt-chromium metal alloy copings fabricated by using CAD-CAM technology. RESULTS: A total of 573 articles were obtained via electronic search, and 10 articles were obtained through manual search, of which 24 in vitro studies were selected after title, abstract, and full-text screening and were included for both qualitative and quantitative analyses. The marginal adaptation was evaluated under the parameters of marginal gap, absolute marginal discrepancy, and vertical marginal discrepancy, whereas internal adaptation was evaluated under the parameters of internal gap, cervical discrepancy, axial discrepancy, and occlusal discrepancy. The methods of CAD-CAM fabrication (direct metal laser sintering, hard milling, and soft milling) were considered under the subgroup analysis. CONCLUSIONS: An overall better marginal and internal adaptation was observed with shoulder and rounded shoulder finish line designs when CAD-CAM methods were used for coping fabrication. Marginal and internal adaptation in chamfer and deep chamfer finish line designs showed better results with soft milling and direct metal laser sintering methods, whereas shoulder finish line showed better results with hard milling.

A comparative evaluation of internal and marginal fits of custom post and core fabricated using conventional and two digital techniques: An in vitro study.

AIM: The purpose of this in vitro study was to comparatively evaluate the marginal and internal fits of cobalt-chromium metal custom post and core fabricated using a conventional technique with two digital techniques. SETTINGS AND DESIGN: The study was designed in an in-vitro study setting. MATERIALS AND METHODS: Five sets of custom post and core restorations were fabricated using the conventional (Group 1) and two semi digital methods (digital scanning of the resin pattern and computer aided additive manufacturing, and digital scanning of the silicone impression and subsequent computer aided designing [CAD] computer aided manufacturing fabrication) (Group 2 and 3). Marginal and internal fits of the posts were evaluated using a micro computed tomography scan at various points. STATISTICAL ANALYSIS USED: A one way ANOVA test of the scores was made to evaluate the effect of different methods of custom post and core fabrication on marginal and internal fits. Bonferroni adjusted post hoc tests were conducted for intergroup comparison. RESULTS: Least marginal gap was reported in Group 3 (82.5 ± 14.36 µm) followed by Group 1 (110 ± 25.19 µm) and Group 2 (112.5 ± 26.75 µm). Least internal gap at cervical, middle and apical as well as overall values were observed in Group 3 (78 ± 9.25 µm, 72 ± 7.79 µm, 160 ± 15.81 µm, 103.3 ± 4.43 µm) followed by Group 1 (113.5 ± 25.35 µm, 132.5 ± 19.92 µm, 502 ± 74.63 µm, 249.3 ± 25.44 µm) and Group 2 (114.5 ± 21.68 µm, 133.5 ± 19.57 µm, 598 ± 87.86 µm, 282 ± 28.91 µm) respectively. The results of one-way ANOVA and Bonferroni adjusted post hoc tests for marginal gap did not show any statistically significant difference between the three groups (P > 0.05) but revealed statistically significant difference (P = 0.02) in internal gap values at the cervical, middle, and apical regions as well as overall internal gap region between the three groups. CONCLUSIONS: Better marginal and internal fits were observed in custom post and core fabricated by digital scanning of the silicone impression and subsequent CAD as compared to those fabricated by the other two groups.

Osseoperception: An Implant Mediated Sensory Motor Control- A Review.

Osseointegration of dental implants has been researched extensively, covering various aspects such as bone apposition, biomechanics and microbiology etc however, physiologic integration of implants and the associated prosthesis in the body has received very little attention. This integration is due to the development of a special sensory ability, which is able to restore peripheral sensory feedback mechanism. The underlying mechanism of this so-called 'osseoperception' phenomenon remains a matter of debate. The following article reveals the histological, neurophysiologic and psychophysical aspects of osseoperception. A comprehensive research to provide scientific evidence of osseoperception was carried out using various online resources such as Pubmed, Google scholar etc to retrieve studies published between 1985 to 2014 using the following keywords: "osseoperception", "mechanoreceptors", "tactile sensibility". Published data suggests that a peripheral feedback pathway can be restored with osseointegrated implants. This implant-mediated sensory-motor control may have important clinical implications in the normal functioning of the implant supported prosthesis.

A Comparative Evaluation of Shear Bond Strength Between Two Commercially Available Heat Cured Resilient Liners and Denture Base Resin with Different Surface Treatments.

BACKGROUND: Soft denture liners are widespread materials used in prosthetic dentistry. Their mechanical properties have to meet several key requirements such as adequate bond to denture base resins in order to provide right function of masticatory system and oral hygiene. AIM: To evaluate and compare the shear bond strength between two commercially available liners and polymethyl methacrylate (PMMA) denture base resin with different surface treatments. MATERIALS AND METHODS: The two soft denture liners - Luci-Sof (silicone based liner) and Super-Soft (acrylic based liner) and a polymethyl methacrylate denture base resin (Trevalon) were chosen for the study. A total of 80 samples were made, 40 each for each of the two materials under investigation. The 40 samples were further divided into four groups, containing 10 samples each. Group I: Consisted of an untreated surface of polymethyl methacrylate which acted as the control. Group II: The surface of polymethyl methacrylate surface was sandblasted. Group III: The polymethyl methacrylate surface was treated with monomer. Group IV: The lining material was processed with acrylic resin dough. The samples after thermocycling for 500 cycles with temperatures from 5° ± 1°C to 55° ± 1°C and a 60 sec dwell time were subjected to shear loading on universal testing machine at crosshead speed of 20mm/sec. A Scanning Electron Microscope and stereomicroscope analysis of the bond interface between the liner and the denture base was conducted for all the groups of the two materials under study. STATISTICAL ANALYSIS: Data was analyzed using independent samples t-test, analysis of variance (ANOVA) and Post-Hoc Analysis. A significance level of α = 0.05 was used for statistical analyses. RESULTS: The bond strength was significantly different between Super- Soft and Luci-Sof (p<0.05) for all surface treatments. The scanning electron microscopy observations showed that the application of surface treatments modified the surface of the denture base resin. CONCLUSIONS: Super-Soft exhibited significantly higher bond strength than Luci-Sof. It was observed that Super-Soft when packed with the pre-polymerized samples produced highest bond strength values among all the groups for both the materials under study. The lowest bond strength was achieved for pre-polymerized samples when packed with Luci-Sof.

Color stability and flexural strength of poly (methyl methacrylate) and bis-acrylic composite based provisional crown and bridge auto-polymerizing resins exposed to beverages and food dye: an in vitro study.

AIM: To evaluate the color stability and flexural strength of poly (methyl methacrylate) (PMMA) and bis-acrylic composite based provisional crown and bridge auto-polymerizing resins exposed to tea, coffee, cola, and food dye. MATERIALS AND METHODS: Two provisional crown and bridge resins, one DPI self-cure tooth molding powder (PMMA) (Group A), and one Protemp 4 Temporization Material (bis-acrylic composite) (Group B) were used. Disk-shaped specimens for color stability testing (n = 30 for each material) and bar-shaped specimens for flexural strength testing (n = 30 for each material) were fabricated using a metal mold. The specimens were immersed in artificial saliva, artificial saliva + tea, artificial saliva + coffee, artificial saliva + cola, and artificial saliva + food dye solutions and stored in an incubator at 37°C. Color measurements were taken before immersion, and then after 3 and 7 days of immersion. Flexural strength was evaluated after 7 days of immersion. RESULTS: Group A showed significantly higher color stability as compared to Group B, and artificial saliva + coffee solution had the most staining capacity for the resins. Test solutions had no effect on the flexural strength of Group A, but Group B specimens immersed in artificial saliva + cola showed significantly lower flexural strength values as compared to the control group. CONCLUSION: The findings of the study showed that for materials used in the study, PMMA was more color stable than bis-acrylic composite based resin. Also, material based on PMMA was more resistant to damage from dietary beverages as compared to bis-acrylic composite based provisional crown and bridge resin.