Bonding Strength of Lithium Disilicate Adhesive Crowns with Different Occluso-Cervical Preparation Heights and Cement Types

The aim of this study was to evaluate if adhesion technology with CAD/CAM can compensate for the reduction of occluso cervical preparation heights using different types of dental cement. The de-bonding failure types were then assessed. Here, 72 caries-free extracted human premolar teeth were prepared to have a remaining occlusal height of two, three, and four mm. IPS e.max lithium disilicate CAD/CAM crowns were cemented with adhesive resin cement Panavia SA, self-adhesive resin cement, RelyX Unicem Aplicap, and zinc phosphate cement. The cementation techniques were based on the manufacturer’s instructions. After thermocycling, all samples were tested for tensile bond strength via an Instron machine. One-way analysis of variance (ANOVA) with post hoc testing (P < 0.05) was performed. The means TBS for the two, three, and four-mm OCHP groups were 2.72±0.69, 3.06±0.82, and 3.25±0.79.0 MPa; ARC, SARC, and ZPC were 3.41±0.51, 3.45±0.41, 2.08±0.35 MPa, respectively with significant differences in both. The mixed cement had failures in the resin cement groups. Failure was predominantly cohesive in the zinc phosphate group. Resin cement had the highest SBS values versus ZPC values when both bonded to lithium disilicate crowns with different occlusal heights. The failure of the adhesive to the crown and/or to the tooth were the highest for the four types of resin cement. Around 25% were cohesive failures with resin cement, but this was predominately adhesive in crowns in zinc phosphate regardless of the preparation heights.

Influence of Dimethacrylate Monomer on the Polymerization Efficacy of Resin-Based Dental Cements—FTIR Analysis

The degree of polymerization for dimethacrylate resin-based materials (BisGMA, TEGDMA, UDMA, HEMA) ranges from 55 to 75%. Literature data indicate that polymerization efficacy depends, among other factors, on the type of methacrylate resin comprising the material. The aim of this study was to evaluate the polymerization efficacy of four dental cement materials characterized by different polymerization mechanisms using FTIR analysis. In the present study, the FTIR method was adopted to analyze the degree of polymerization efficacy of four resin-based dental cement materials, two of which were self-cured and two were dual-cured cements. The IR spectral analysis was performed 24 h after the polymerization of the cementitious material. RelyX ARC cement exhibits the lowest polymerization efficacy (61.3%), while that of Variolink II (85.8%) and Maxcem Elite is the highest (90.1%). Although the efficacy of self-cured cements appears to be superior, the difference is not statistically significant (p = 0.280). Polymerization efficacy largely depends on the chemical structure of the material in terms of the presence of a particular methacrylate resin and less on the polymerization mechanism itself, i.e., whether it is a self-cured or dually cured dental cement. Thus, in clinical practice, cementitious materials with a higher proportion of TEGDMA compared with BisGMA are recommended.

EXPERIENCE OF USING ENAMEL MATRIX PROTEIN IN COMBINATION WITH A CORONARY ADVANCED FLAP AND A CONNECTIVE TISSUE GRAFT TO ELIMINATE GUM RECESSION

The article presents the experience of complex managing a patient with gum recession in the area of the maxillary premolars. Periodontal treatment of gum recession consisted of initial therapy, including supra- and subgingival scaling, root planing, pharmacotherapeutic support (broad-spectrum antiseptics, drugs that stimulate regeneration), surgical combined method based on the use of enamel matrix protein to stimulate regenerative processes. The clinical material Emdogaine is a combination of an enamel matrix derivative and propylene glycol alginate, which performs the function of a carrier. Biora company has been producing it for more than 20 years (Emdogain, BIORA): now the rights to this material belong to Straumann). This preparation was developed to stimulate regeneration of periodontal tissues. Amelogenin is a specific enamel protein capable of stimulating regeneration of lost periodontal tissues by influencing cell differentiation. Dental cement is an osteoid connective tissue that covers the roots of teeth and serves to attach periodontal fibers. Application of an enamel matrix derivative to the sanitized root surface leads to regeneration of non-cellular cement and to the formation of periodontal tissues, which was observed in our study. Transplantation of free connective tissue grafts to eliminate gum recessions makes it possible to effectively eliminate gum recession in most clinical cases (complete root coverage, an increase in the level of clinical attachment from the keratinized attached gum area). In our clinical case, free grafts were obtained in the donor area of the maxillary tuberosity. Transplantation of free connective tissue grafts provides an aesthetic result and is currently considered a standard technique for eliminating gum recession. According to the clinical study, a combined use of connective tissue grafts and the enamel matrix derivative, an additional use of enamel matrix derivative enabled to obtain a satisfactory result and to improve the appearance of the dentition. Such combined surgeries are indicated in an aesthetically significant area. The described materials, methods and stages of patient's follow up can serve as the basis for the protocol of managing patients with gum recession.

Impact of cement type and abutment height on pull-off force of zirconia reinforced lithium silicate crowns on titanium implant stock abutments: an in vitro study

Background Pull-off forces of cement-retained zirconia reinforced lithium silicate (ZLS) in implant-supported single crowns on stock titanium abutments with respect to abutment height and implant cement were evaluated and compared. Methods Pull-off force of ZLS crowns on stock titanium abutments was evaluated concerning dental cement and abutment height. A total sample size of 64 stock abutments with heights of 3 mm (n = 32) and 5 mm (n = 32) was used. The ZLS crowns were cemented with four different types of cement (one temporary, two semi-permanent, and one permanent). After cementation, water storage, and thermocycling each sample was subjected to a pull-off test using a universal testing machine. Results The temporary cement showed the least pull-off force regardless of abutment height (3/5 mm: means 6 N/23 N), followed by the semi-permanent methacrylate-infiltrated zinc oxide cement (28 N/55 N), the semi-permanent methacrylate-based cement (103 N/163 N), and the permanent resin composite cement (238 N/820 N). Results of all types of cement differed statistically significantly from each other (p ≤ .012). The type of implant cement has an impact on the pull-off force of ZLS crowns and titanium abutments. Conclusions Permanent cements present higher retention than semi-permanent ones, and temporary cements present the lowest values. The abutment height had a subordinate impact.

Zinc phosphate nanoparticles: A review on physical, chemical, and biological synthesis and their applications

: Nanotechnology is considered one of the emerging fields of science that has influenced diverse applications, including food, biomedicine, and cosmetics. The production and usage of materials with nanoscale dimensions like nanoparticles are attractive parts of nanotechnology. Among different nanoparticles, zinc phosphate nanoparticles have attracted attention due to their biocompatibility, biosafety, non-toxicity, and environmental compatibility. These nanoparticles could be employed in various applications like anticorrosion, antibacterial, dental cement, glass ceramics, tissue engineering, and drug delivery. A variety of physical, chemical, and green synthesis methods have been used to synthesize zinc phosphate nanoparticles. All these methods have some limitations along with certain advantages. Chemical approaches may cause health risks and environmental problems due to the toxicity of hazardous chemicals used in these techniques. Moreover, physical methods require high amounts of energy as well as expensive instruments. However, biological methods are free of chemical contaminants and eco-friendly. This review is aimed to explore different methods for the synthesis of zinc phosphate nanoparticles, including physical, chemical, and more recently, biological approaches (using various sources such as plants, algae, and microorganisms). Also, it summarizes the practicable applications of zinc phosphate nanoparticles as anticorrosion pigment, dental cement, and drug delivery agents.

A literature review on selection of dental cement in dentistry

In today's time, the key to achieve the successful restoration is the selection of the proper dental cement. The proper selection of the dental cement ultimately increases the survival rate of the prosthesis or the restoration. From the past few years many new dental cements recently developed and claims better properties as compared to the traditional cements.