Cytotoxic effect of dental luting cement on human gingival mesenchymal stem cell and evaluation of cytokines and growth factor release - An in vitro study.

AIM: In routine dental care, various dental luting cements are utilized to cement the dental prosthesis. Thus, the aim of the current study was to assess the Cytotoxic effect of three different dental luting cements on human gingival mesenchymal stem cell and evaluation of cytokines and growth factors release. SETTINGS AND DESIGN: Cytotoxicity of glass ionomer cement (GIC), resin modified glass ionomer cement (RMGIC) and resin cement (RC) on the human gingival mesenchymal stem cells (HGMSCs) was evaluated. Amongst the cements tested, least cytotoxic cement was further tested for the release of cytokines and growth factors. MATERIALS AND METHODS: MTT test was used to evaluate the cytotoxicity of the dental luting cements at 1 h, 24 h, and 48 h on HGMSCs. Cytokines such as interleukin (IL) 1α & IL 8 and growth factors such as platelet derived growth factor & transforming growth factor beta release from the least cytotoxic RC was evaluated using flow cytometry analysis. STATISTICAL ANALYSIS USED: The mean absorbance values by MTT assay and cell viability at various time intervals between four groups were compared using a one way analysis of variance test and Tukey's post hoc test. The least cytotoxic RC group and the control group's mean levels of cytokines and growth factors were compared using the Mann-Whitney test. RESULT: As exposure time increased, the dental luting cement examined in this study were cytotoxic. RC was the least cytotoxic, RMGIC was moderate and glass ionomer cement showed the highest cytotoxic effect. Concomitantly, a significant positive biological response of gingival mesenchymal stem cells with the release of ILs when exposed to the RC was observed. CONCLUSION: For a fixed dental prosthesis to be clinically successful over the long term, it is imperative that the biocompatibility of the luting cement be taken into account in order to maintain a healthy periodontium surrounding the restoration.

Splinting Open Tray Impression Copings Using Long Shank Carbide Burs during Definitive Impression: A Dental Technique.

AIM: To splint implant impression copings using long shank carbide burs for definitive implant impressions. BACKGROUND: The accurate transfer of the orientation recorded by impression copings to a definitive cast is a challenging step in implant prosthodontics. For achieving a passive fit from the mouth to the cast may include some discrepancies. Traditional methods of splinting can be time-consuming and troublesome to handle. TECHNIQUE: This article describes a technique by using long shank carbide burs for splinting implant impression copings. CONCLUSION: The favored implant splinting, evidence was inconclusive, and the data supporting splint pickup was the better performing technique, especially with an increased number of implants. CLINICAL SIGNIFICANCE: This technique causes minimal discomfort and is straightforward when compared to other techniques.

Comparative Evaluation of the Amount of Gingival Displacement Using Three Recent Gingival Retraction Systems - In vivo Study.

BACKGROUND: Gingival retraction cord is the most commonly used gingival displacement material; however, it causes discomfort and produces damage to the periodontium. Various new gingival retraction materials have been introduced to overcome these problems. This in vivo study was conducted to compare the efficacy of three recent gingival displacement materials in achieving gingival tissue displacement. MATERIALS AND METHODS: A total of 10 subjects was selected and 40 samples were made for the study. Samples were divided into four groups depending on the materials used for gingival displacement. The schedule for gingival displacement and impression making followed Latin block design. On day 1, baseline impression was made without gingival displacement. On day 2, day 22, and day 42 impressions were made after gingival displacement on intact maxillary right central incisor with any one of the three agents. The amount of gingival displacement was then measured as a distance from the tooth to the crest of the gingiva in a horizontal plane using stereomicroscope. RESULTS: Statistical analysis was performed using one-way ANOVA test. The amount of gingival displacement obtained by all the experimental groups was more than the control group (P < 0.01). Among the experimental groups, astringent gingival retraction paste showed the highest value for gingival displacement (0.50 mm) followed by the stay-put retraction cord (0.48 mm), whereas expasyl (0.34 mm) showed the least value. CONCLUSION: Within the limitations of this in vivo study, astringent gingival retraction paste showed the highest value for gingival displacement followed by stay-put retraction cord whereas, expasyl showed the least value.

The effect of joint surface contours and glass fiber reinforcement on the transverse strength of repaired acrylic resin: An in vitro study.

BACKGROUND: Denture fracture is an unresolved problem in complete denture prosthodontics. However, the repaired denture often experiences a refracture at the repaired site due to poor transverse strength. Hence, this study was conducted to evaluate the effect of joint surface contours and glass fiber reinforcement on the transverse strength of repaired acrylic resins. MATERIALS AND METHODS: A total of 135 specimens of heat polymerized polymethyl methacrylate resin of dimensions 64 × 10 × 2.5 mm were fabricated. Fifteen intact specimens served as the control and 120 test specimens were divided into four groups (30 specimens each), depending upon the joint surface contour (butt, bevel, rabbet and round), with two subgroups based on type of the repair. Half of the specimens were repaired with plain repair resin and the other half with glass fibers reinforced repair resin. Transverse strength of the specimens was determined using three-point bending test. The results were analyzed using one-way ANOVA and Tukey post-hoc test (α= 0.05). RESULTS: Transverse strength values for all repaired groups were significantly lower than those for the control group (P < 0.001) (88.77 MPa), with exception of round surface design repaired with glass fiber reinforced repair resin (89.92 MPa) which was significantly superior to the other joint surface contours (P < 0.001). Glass fiber reinforced resin significantly improved the repaired denture base resins as compared to the plain repair resin (P < 0.001). CONCLUSION: Specimens repaired with glass fiber reinforced resin and round surface design exhibited highest transverse strength; hence, it can be advocated for repair of denture base resins.